\iXKiKiS»»i»'m'«iC'>SS)S»»- 
 
 ^'VERBAL^' NOTES 
 
 -. SKETCHES 
 FOR Marine Engineers 
 
 J.W. M. SOTHERN 
 
 M.I.E.S. 
 
 25/- NET. 
 
 NINTH 
 EDITION 
 
GIFT OF , 
 Arthur K, ;,.orica.3ter 
 
n 
 
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4^ C^ x;^^l«^^«>^^-.=e^:.^^^^^^ 
 
 "Verbal" Notes and Sketches 
 FOR Marine Engineers 
 
PRINTED AT 
 
 THE IJARIEN IFESS 
 
 EDINBVROIl 
 
3- I 
 
 
 H ^ ffi 
 
 I ^ 
 
"VERBAL NOTES AND SKETCHES 
 FOR MARINE ENGINEERS 
 
 A MANUAL OF 
 
 MARINE ENGINEERING PRACTICE 
 
 INTENDED FOR THE USE OF NA VAL AND MERCANTILE 
 MARINE ENGINEERS OF ALL GRADES, AND STUDENTS, 
 FOREMEN ENGINEERS, ETC., AND IS SPECIALLY COM- 
 PILED FOR THE USE OF ENGINEERS PREPARING FOR 
 EXAMINATIONS OF COMPETENCY AT HOME OR ABROAD 
 
 BY 
 
 J. W. M. SOTHERN 
 
 Member, Institute of Engineers and Shipbuilders in Scotland; Hon. Member, Glasgow and 
 West of Scotland Association of Foremen Engineers and Draughtsmen. 
 
 Author of "Marine Indicator Cards," "The Marine Steam Turbine," "Simple Problems in 
 Marine Engineering Design," "Elementary Mathematics for Marine Engineers," etc. 
 
 Principal, Sothern's College of Alarine Engineering, Glasgow. 
 
 700 ILLUSTRATIONS 
 
 NINTH EDITION 
 
 GREATLY ENLARGED IN BOTH TEXT 
 AND ILLUSTRATIONS 
 
 Copscigbt.-EntcrcB %^\\\ B,\ at Stationers' Ibalf 
 
 GLASGOW: JAMES MUNRO & CO. LIMITED 
 
 60 BROWN STREET 
 
 1917 
 
i'^ngines.— ( ylinclers, 27;) 
 
 Stroke, 60 inc 
 Cut-off, 70 pel 
 
 Type of Valve Gear. — St( 
 
 'I'ravcl of \'alves. — 8 incll 
 
 Note. — For H.P., 1st 
 
 Not 
 
"VERBAL" NOTES AND SKETCHES 
 FOR MARINE ENGINEERS 
 
 A MANUAL OF 
 
 MARINE ENGINEERING PRACTICE 
 
 INTENDED FOR THE USE OF NAVAL AND MERCANTILE 
 MARINE ENGINEERS OF ALL GRADES, AND STUDENTS, 
 FOREMEN ENGLNEERS, ETC., AND IS SPECIALLY COM- 
 PILED FOR THE USE OF ENGINEERS PREPARING FOR 
 EXAMINATIONS OF COMPETENCY AT HOME OR ABROAD 
 
 BY 
 
 y. W. M. SOTHERN 
 
 Member, Institute of Engineers and Shipbuilders in Scotland; Hon. Member, Glasgow and 
 West of Scotland Association of Foremen Engineers and Draughtsmen. 
 
 Author of "Marine Indicator Cards," "The Marine Steam Turbine," "Simple Problems in 
 Marine Engineering Design," "Elementary Mathematics for Marine Engineers," etc. 
 
 Principal, Sothern's College of Alarine Engineering, Glasgow. 
 
 700 ILLUSTRATIONS 
 
 NINTH EDITION 
 
 GREATLY ENLARGED IN BOTH TEXT 
 AND ILLUSTRATIONS 
 
 CopBriflbt.-!entcrc6 J-, / I S. at Stationers' Iball. 
 
 GLASGOW: JAMES MUNRO & CO. LIMITED 
 
 60 BROWN STREET 
 
 1917 
 
MM ^00 
 
 ':(^:l^./:o^ kX^-y E, \\<.y.zJic/ 
 
 Seventh Edition published September 1911 
 
 Eighth Edition (with new appendix) pub- 
 lished September 1913 
 
 Re-issue (with numerous additions) pub- 
 lished January 1915 
 
 Re-issue (with further additions) published 
 October 191S 
 
 Fourth Re-issue (with additions) published 
 September 1916 
 
 Ninth Edition published October 1917 
 
PREFACE TO NINTH EDITION. 
 
 Till-; present volume, it nia)' be pointed out, contains much new 
 matter and many new illustrations, in addition to which the work, as a 
 whole, has been carefully revised and corrected. Important additions 
 have been made to the sections treating of Diesel Oil luigines, 
 Marine Steam Turbines, and Electric Light, and to the other sections 
 generally and it is hoped that the book will be found to be even 
 more useful than before as a general reference volume for marine 
 engineers of all grades. It may also be pointed out that the work 
 now contains a full set of Board of Trade First Class Examination 
 Drawings with dimensions, and a set of forty Board of Trade Second 
 Class Examination Drawings, also fully dimensioned, for the use of 
 second class students under the new and revised Regulations (1917). 
 The author desires to express his pleasure in the knowledge that the 
 book is steadily rising in popularity yearly, and that the increasing 
 sales now extend to all parts of the world, and it may interest readers 
 to know that the volume enjoys an extensive circulation even in far 
 Japan. " Verbal " Notes is also in general use among the engineering 
 personnel of the Royal Navy, and in short, appears to be the most 
 popular technical work on marine engineering published. 
 
 The author specially desires to thank A. N. Somerscales, Esq., 
 Hull, for most kindly revising and correcting the work, also for 
 many useful suggestions towards improvement in the text, etc. ; also 
 R. M. Sothern, Esq., for preparing many of the drawings and check- 
 ing the various calculations. The author's thanks are also due to 
 the editor and proprietor of the Mechanical World for kind 
 permission to reproduce a number of the illustrations from the pages 
 of that journal ; to the proprietors of Engineering for illustrations 
 and accompan\'ing descriptions of Diesel Engine sets ; to Messrs 
 the British-Thomson-Houston Co. Ltd., Rugby, for kind permission 
 to reproduce illustrations and text relativ^e to Curtis turbines ; and 
 specially to Messrs Richardson, Westgarth & Co. Ltd., Hartlepool, 
 for the handsome illustration and the data which form the frontispiece 
 of the volume ; also to W. B. Hird, Esq., of Messrs Mavor & Coulson, 
 electrical engineers, Glasgow, for kind permission to reproduce an 
 article on Electric Motor Practice. Finally, and as on former 
 occasions, the author has again to thank numerous friends and students 
 for much valuable data taken from actual practice. 
 
 Marine Engineering College, 
 59 Bridge Street, Glasgow, October 1917. 
 
 72615S 
 
PREFACE TO EIGHTH EDITION. 
 
 Ix the New Appendix wliich is included in this luh'tion the author 
 has introduced a number of new ch^awings, notes, and calculations, 
 referring chieflx' to Diesel Oil ICngines, Boilers, and Marine Turbines, 
 the latter including exhaust turbines and geared down turbines, thus 
 bringing the work right up to date. 
 
 The author's thanks are due to A. P. Chalkley, Esq., for kind per- 
 mission to reproduce detail drawings of the Diesel type oil engine 
 from •' Diesel Engines," by A. P. Chalkley, B.Sc, A.M.I.C.E. ; to the 
 Council of the Institution of Naval Architects for permission to repro- 
 duce the illustration of the " Vespasian " gear wheels from a Paper 
 read before that Institution by Sir Charles Parsons, and entitled 
 "The Application of the Marine Steam Turbine and Mechanical 
 Gearing to Merchant Ships" ; to the editors of Eiiginccruig for illus 
 trations of the turbine machinery of O.SS. " Reina Victoria Eugenia," 
 and SS. " King Orr)'," and for permission to reprint the descriptions 
 of the machinery which appeared originally in E)igineenng\ also for 
 permission to rej)roduce the illustrations showing the Diesel four-cycle 
 and two-cycle action, from a Paper entitled "The Diesel Oil Engine," 
 by Dr Rudolph Diesel of Munich, and read before the Institution of 
 Mechanical Engineers. The author has also to thank Messrs G. & J. 
 Weir for the illustration of their patent " Dual " type Air Pumps, etc. 
 
 Marine Kncinekrino Coli.fi.e, 
 59 BRn)GE Street, Glasgow, September 191 3. 
 
CONTENTS. 
 
 SECTION I. 
 
 \\'OKKSHOP PrACTICK. 
 
 pa<;e-^ 
 
 Types of Engines — Paddle Engines — Screw Engines — Steam Flow — 
 Balanced Engines — \'alves — Pistons-Connecting Rods — Val\ e Gear 
 — Eccentrics — Main Hearings —Crank-shafts — Columns — Soleplate 
 — Crank-shafts and Columns — Cutting of Eccentric Keyseats— Erect- 
 ing of Columns — Cylinders and Valve Chests — Training Connecting 
 Rods and Running Ciear — Training \''alve Gear — Cylinder Clearance 
 and Valve Setting — Cylinder and Pump Connections, (S:c. — Propeller 
 Shaft Liners — Marking off Ship for Boring Out— Thrust Block — 
 Erecting Machinery in Ship — Pipe Connections — Auxiliary Marhinery 
 — Trial Trips — Care and Upkeep — Howto Keep a Watch — Economical 
 Working- ........ 1-70 
 
 SECTION II. 
 
 Boilers. 
 Strength of Plates — Elastic Limit and Factor of Safety — Stresses on Shell 
 Seams — Strength of Shell — Shell Pressure, &c. — Strength of Joints — 
 Riveting — Types of Joints — To Prove Joint Strength— Examples of 
 Joints — Circumferential .Seam Riveting — Combined Strength of Seam 
 and Rivets— Steam Space Stays — Flat Surfaces and Stays— End 
 Plates and Stays — Water Space Stays — Pitch of Stays Combustion 
 Chambers — Combustion Chamber Stays and Girders —Tubes — Stay 
 Tubes — " Adamson " Rings — " Bowling " Hoops — Corrugated Fur- 
 naces - Furnace Joint Repairs — Furnace Riveting — Boiler Upkeep 
 and Repair, &c. — Strengthening a Furnace — P^urnace Manufacture — 
 Collapse of Furnaces — Furnace Temperatures — F"ire-bars and Bearers 
 — Manholes—Natural Draught — Forced Draught — Pitting and Cor- 
 rosion — P>oiler Repairs — Examples of Plate Corrosion, &c. — Tube 
 Stoppers — Leaky Tubes — Safety X'alves — Superheated Steam — Steam 
 Pipes — Water Hammer — Circulation and Priming — Doubling Plates 
 — Scarfed Joints — Zinc Plates — Water Gauge — Boiling Points — 
 Salinometer, Density — Ash Ejector — Tait's Patent Water Circulator 
 —Tube Expander — Cutting Out of Tubes — Reducing Valves — Auto- 
 genous Welding Process — Hand Sketches of Boilers— Efficiency of 
 Boiler — " Equivalent Evaporation " — Weight of Gases — .Shortness of 
 Water — \'elocity of Gases — Boiler Dimensions — Donkey Boiler Re- 
 pair — Fire Box Repair — \'ertical Donkey Boiler — Cochran Patent 
 Boiler — Haystack Boiler — Yarrow Boiler — Babcock P)Oiler— Bellville 
 Boiler— Schmidt Type Superheater - - - - - T^-'^ll 
 
\iii Contents 
 
 SECTION III. 
 
 NoTKS AND Sketch Ks of \'ai<iou.s Detau.s. 
 
 Crank pin Lubrication — Reversing Gear — Turning Engine — H.P. Steam 
 Connections — Stern Tube — Condenser Tubes — Thrust Bloci< — Start- 
 ing Valve — L. P. Piston — Air Pump— Edwards Air Pump Bucket — 
 Valve Spindle Eye Bush — Double Beat Valve and Expansion Joint — 
 Column, Pump Lever, Air and Feed Pumps — Air Pump \'alves— " A" 
 Brackets — Connecting Rod Bolts and Nuts — Edwards Pump — Engine- 
 Room Gauges — Air Pump Connections — Piston Rod and Shoes -- 
 Balance Weights — Circulating Water Connections — Connecting Rod 
 — Piston Rod — Oil Feed Boxes — Reversing Bell Crank — Pumping 
 Diagram — Feed Pump Connections - . . - . 178-198 
 
 SECTION IV. 
 
 Slide Valves, Piston Valves, Valve Data, &c. 
 
 Duties of Valve — Valve Travel — Steam Lap and Exhaust Lap — Lead — 
 Double- Ported Valves — Piston Valves — Trick Valve — Andrews- 
 Martin Valve — Piston Valve Rings — Expansion Valve — Joy's Assistant 
 Cylinder — Open and Crossed Eccentric Rods — Reversing Gear — 
 Measurement of Lead — Lead Adjustments — Valve Settings — Con- 
 necting Rod Angle — Patent Valve Gears — Link Motion — Linking 
 Up — Eccentric Keyseat Templates— Valve Setting Tables— Zeuner 
 Valve Diagrams — Cranks and Eccentric Rods — "Linked Up" \'alve 
 Diagram — Bellis and Morcom Engine — Effects of Link Adjustments 
 — Marking of Eccentric Keyseat Positions on Shaft - - -199-263^' 
 
 SECTION V. 
 
 General Notes amd Descriptions. 
 
 Manufacture of Iron and Steel — Alloys — Properties of Metals and Alloys 
 — Composition of Steel, &c. — Tempering Steel — Annealing — Case- 
 Hardening — Brazing — Welding — Strength of IMaterials — Stresses on 
 Working Parts — Built Shafting— Strength of Shafting — Torsion and 
 Bending Moments — Torsional Stress and Constant 5.1 — Twisting 
 Stress and Shaft Diameter — Mean Twisting Moment, &c. — Board 
 of Trade Constants — Lloyds' Rules for Shafting — Crank Angles — 
 Flaws on Shafts — Shaft Repairs — Thomson Patent Coupling — Stop- 
 ping of Engines — Engine Breakdowns — Engine Testing — Pumps — 
 Breakdown of Pumps — Loss of Vacuum — Pet Valves — Air Vessels — 
 Condenser and Air Pump — Oscillating Engine — Weir "Uniflux" 
 Condenser' — Diagonal Engines — Paddle Enj^ine Shafts — Paddle 
 Wheels — Weir P'ced Heater — Weir Evaporator — Weir Feed Pump — 
 Weir Pump Steam V^alves — Feed Water Filter — Aspinall Governor — 
 Worthington Feed Pump — Lamont Pump — Engine and Boiler Data 
 
Contents ix 
 
 PAOF.S 
 
 Pressure (laiige Indications — The Barometer — The Thermometer — 
 Tail Shaft Corrosion — Propeller Pitch— To Find Cut-oft"- -Crank on 
 Centre — Cuttini^ of Keyseats — Vahe in Mid-Travel — Shaft Sighting 
 
 — Lining up Shafting — Flaws on Shafts — Various Engine Adjust- 
 ments — Pressure ("lauge Tube — Main and iJilge Injection— Thrust 
 Block — Crankpin and Piston Travel — Broken L.P. Cylinder Cover — 
 Sight Feed Lubricator — Hydraulic Accumulator — Brown's Steam and 
 Reversing Gear — Steering Gears — Brown's Steam Tiller — Metallic 
 Packings — Stern Tube and Shaft — Drawing the Propeller Shaft — 
 Pulsometer — Hot-well Temperature— General Definitions —Density 
 of Steam — Brake Horse-Power — Dryness of Steam — Total Heat and 
 Latent Heat — Potential and Kinetic Energy— Adiabatic Expansion — 
 Hyperbolic Expansion — Heat and British Thermal Unit — Saturated 
 Steam, Wet Steam, and Superheated Steam — Boyle's Law of Expan- 
 sion — Charles' Law — Steam Expansions by Pressures and \'olumes 
 
 — Heat Efficiency — Initial Condensation — Advantages of Multi- 
 Cylinder Engines — Cylinder Ratios and Expansions — Cut-off and 
 Pressures — Suction Lift of Pumps — Stresses on Shafting — To line 
 up Crank-shaft— Pistons— Stresses on Beams— Consumption and 
 Speed — I.H.P. and Consumption — Coal, I.H.P., and Distance— H. P. 
 Cut-oft" and Consumption — Efficiency of Boilers and Engines, &c. — 
 Squared Paper Diagrams — Curves of Speed, Consumption, Power, 
 
 and Slip ----.-.-. 264-407 
 
 SECTION VI. 
 
 Marine Engineering Chemistry Notes. 
 
 Composition of Coal — Heat Values — Chemistry of Gases — Atmospheric 
 Air — Water — Carbonic Acid Gas and Carbonic Oxide Gas — Free 
 Nitrogen — Marsh Gas — Petroleum Vapour — Ammonia — Iron Oxide 
 — ^Hydrochloric Acid — Sodium Chloride — Calcium Chloride — Acids — 
 Alkalies — Spontaneous Combustion — Treatment of Fires — Sealing-off 
 — Air Required for Combustion — Carbon — Nitrogen — Hydrogen — 
 Combustion — Coal Gases — General Notes on Combustion — Complete 
 and Incomplete Combustion —Burning of CO — Scale, Density, and 
 Corrosion — Composition of Fresh and Sea Water — Incrustation — 
 Composition of Boiler Scale— Scale and Oil Deposit — Temporary and 
 Permanent Hardness— Corrosion of Boilers — Causes of Corrosion — 
 Prevention of Corrosion — Hydrochloric Acid — Scale and Plate 
 Temperature — Magnesium Chloride— Corrosion of Tubes — Test for 
 CO2 — Evaporator Scale — Boiler Deposits — Leaky Tubes — Density 
 and Scale — General Notes on Scale and Density— Solids in Sea 
 Water — Calcium Carbonate — Calcium Sulphate — Soda — Lime — 
 Rusting— Grooving — Paraffin Oil— Carbonate of Soda— Nitrate of 
 Silver Test — Caustic Soda— Test for Acid — Hydrometer — Oils — 
 Viscosity— Gumminess of Oil — Classes of Oils— Oil Emulsion — 
 Saponification — Care of Boilers — Acid Test — Viscosity Test— Other 
 Tests— Alkala Boiler Composition — Remedies for Pitting — Galvanic 
 Action — Rusting — Condenser Tube Cerrosion - - - 408-431 
 
X Contents 
 
 SECTION VII. 
 
 MaKIXI'; r^I.KC'lklC LUIHIINC. 
 
 I'AfiES 
 
 (Galvanic Cells or Hatteries — Daniell Cell — Electro-Magnets — Field 
 Magnets — Armature — Commutator — Brushes — Action of Dynamo — 
 Switchboard — Volt Meter — Ampere Meter — Main Switches — Fuses — 
 Wiring — Three-Wire System -Distribution lioxes — Lamp Switches 
 — Incandescent Lamps — Types of Lamps— Arc Lamps — Projector — 
 Resistance Coils — Testing for Faults — Hints on Running — Jointing 
 of Wires — Electric Motors -Motor Starters- Types of Motors 
 Electric Notes— General Electrical Notes and Sketches— Motor 
 Starting Resistance, ^:c. - - - - - - 43--5J3 
 
 SFXTIOX VIII. 
 
 I'ropki.i.krs. 
 
 General Remarks — Thrust — Pitch — Right and Left Hand Screws — Cir- 
 cumference and Thread — Pitch Variation — Pitch Ratio^Diameter 
 and Length of Propeller — Length of Blade — Moulding of Blades — 
 Slip and Wake Speed — Disc Area and Developed Area— Area Ratio 
 — ^Projected Area — Thrust and Drag Surface of Blades — Cavitation 
 —Apparent Negative Slip— Racing — Designing of Propellers with 
 Examples — To Fit on a New Propeller — Motor Launch Propellers — 
 Blade Interference — Twin Screws — Surface of Blades — Bronze Pro- 
 pellers — Propulsive Efficiency — Resistance — Power Losses — Utili-,a- 
 tion of Power- -Slip ------- 514-53S 
 
 SECTION IX. 
 
 Rkkrigkratiox. 
 
 The Ammonia System — Pressures — Evaporator Pressures — Compressor 
 (iland — Oil Extraction— Charging with Ammonia — OverhaulingCom- 
 jjressor— Making up of Brine- Density of Brine — Circulation of Brine 
 — Chamber Temperatures — Air in System — Carbonic Anhydride 
 System — Properties of C0._.— Compressor — Gland- Separator— Con- 
 denser Evaporator — Safety \'alve — Joints — Testing Parts— Instruc- 
 tions for Charging and Working — Charging with Gas — Latent Heat 
 of Ammonia (NH:;) and COj — Critical Temperature of COo and NH:- — 
 The Compressed Air System — Compressor and Expander Diagrams- 
 General Notes on Refrigeration — Pressures and Temperatures- 
 Temperature Difference — Leaky Compressor Piston and \'alves — 
 Testing of Brine --Air Extraction — Overhauling Compressor— Brine 
 Temperature Difference— Joint Testing - - - . 539-5; 
 
Contents xi 
 
 SFXTION X. 
 
 Intkkn^i. CoMMUs'iioN Enc.ines. 
 
 I'AC.E 
 
 Producer das — "Cooler" and Scrubber — Steam (ienerator— Action — 
 EtViriency — Consumption — Heat \'alue - Test Burner — Explosion 
 Systems — Paraflln and Petroleum — Petrol — Two-Cycle — -Four-CycIe 
 
 — Comparison of Steam-Engine and Oil-Engine — Pistons — Revolu- 
 ^ tions — Water Jacket — Pressures and Temperatures— Carburetter — 
 
 Valves — Sleeve \'alve — Flywheel— Firing Plug — Cranking — Ignition 
 — Jump Spark— Make-and-Break — Magneto — Setting Magneto — 
 Motor Troubles — Loss of Power in Engine — Leaky Pistons — Exhaust 
 Gases — Reversing — Crank Arrangements — Starting — Speed Regula- 
 tion — Engine Troubles, Causes and Remedies — Tests — Diagrams 
 from Oil Motors— Mean Pressure — Indicated Horse-Power — Brake 
 Horse- Power — Types of Motors — Oil Fuel — Oil and Coal Compared 
 
 — Composition of Oil— Methods of Working — Oil Spray —Burners — 
 Kermode Burner — Control — Starting L'p— Leakage Test — Colour of 
 Gases — Flash Point and Firing Point — Sand — Black Smoke — White 
 Smoke — X'entilation Pipes — Air X'essel — Settling Tanks — Air Cone 
 
 — Evaporation of Oil — Water in Oil — White \'apour — Diesel Engine 
 Notes and Sketches ------ 574-641 
 
 APPENDIX. 
 
 Marine Steam Turbines — Ue-Laval Turbine — Parsons Turbine — Flow 
 of Steam — Turbine Arrangements — Dummies — Blading List — Tip 
 Clearance — Combination Arrangement — Geared- Do wn Turbines — 
 SS. " \'espasian "— SS. " King Orry " — Turbines of Liner " Britannic " 
 — Blading — Curtis Turbines — Port Turbines and (iear Wheels, 
 T.S.S. "Tuscania" — Manoeuvring Valves — Practical Operation of 
 Turbine Machinery — Weir " Dual " Air Pumps — Three-Wire System 
 of Lighting — Knocking in Engines— Engine Data — Economy of Feed 
 Water Heating — Valve Settings — Standard Specification for Cargo 
 S.teamer Engines - Vertical Donkey Boiler — Riveted Joints, i!v:c. — 
 First Class and Second Class Examination Drawings with 
 Full Dimensions --...-. 642 704 
 
 "able of the Properties of Saturated Steam — Table of Circumferences and 
 
 Areas of Circles — Hyperbolic Logarithms - . . . 705-716 
 
I 
 
 INDEX. 
 
 A^' brackets 189 
 
 ibsolute pressure, definition of ... 3G9 
 
 accumulator .electrical) described 492 
 
 ,, I hydraulic) ... ... 335 
 
 Lcidity of oils, how tested ... ... 429 
 
 Lcids, properties of ... ... ... 412 
 
 iction of dynamo ... ... ... 445 
 
 „ lime in boilers ... ... 427 
 
 ,, pressure-gauge tube ... 329 
 
 steam in cylinder ... 238 
 
 steering gear vahes ... 343 
 
 .damson ring furnace ... ... 110 
 
 j.diabatic expansion curve ... ... 368 
 
 i.djusting stroke of Weir pump ... 312 
 
 j.djustment of lead 216-19 
 
 [ ,, ., examples of 217-18 
 
 |.dvantages of corrugated furnaces 116 
 
 „ feed heating ... 306 
 
 high-pressure steam 384 
 
 ,, hydraulic system ... 335 
 
 ,., multi cylinders ... 384 
 
 ,, patent valve gears... 222 
 
 ,, superheated steam... 137 
 
 head and astern positions of gear 212 
 
 it and feed pumps ... 187 
 
 ir e.xtraction I ammonia) ... ... 573 
 
 lir pump 185 
 
 I „ and condenser ... ... 296 
 
 bucket 292 
 
 clearance ... 327 
 
 connections ... to face 193 
 
 Edwards type ... 186,292 
 valves and vacuum 188, 365 
 ir recjuired per pound coal ... 410 
 
 vessels 295 
 
 lignment of cylinders and shafting 
 
 to face 35 
 
 A.lkala" boiler composition 
 Ikalies, properties of 
 
 Ikaline test 
 
 tley & ArLellan 
 
 gear 
 
 jloys, Babbit's white metal 
 Brass... 
 
 type steermg 
 
 429 
 412 
 
 429 
 
 348 
 274 
 274 
 
 Alloys, strength and composition of 274 
 
 Ammonia 412 
 
 ,, air in system ... ... 544 
 
 „ brine circulation 544 
 
 „ „ density .. ... 543 
 
 ,, „ making 543 
 
 ,, chamber temperatures ... 544 
 
 ,. charging of machine ... 543 
 
 ,, compressor ... ... 539 
 
 „ gland ... .542 
 
 ,, condenser ... ... 539 
 
 „ description of plant ... 541 
 
 ,, evaporator ... ... 539 
 
 „ ,, pressures ... 542 
 
 ,, oil extraction ... ... 543 
 
 ,, overhauling compressor 543 
 
 „ system ... ... ... 5.39 
 
 xAmmonia and COo systems to face 540 
 
 Ampere, definition of 491 
 
 „ meter ... ... ... 449 
 
 Amperes, B. of T. allowance ... 491 
 Andrews-Martin balanced valve 205, 207 
 
 Aneroid barometer ... ... ... 320 
 
 Angle of connecting rod ... ... 221 
 
 Angold arc lamps ... ... ... 460 
 
 Animal oils ... .. .. ... 428 
 
 Annealing ... ... ... ... 276 
 
 Arc lamps ... ... ... ... 461 
 
 G.E.C. type 462 
 
 ,, in series 466 
 
 „ resistance ... ... 466 
 
 Area (projected) of propeller blades 519 
 
 ,, ratio of propellers ... ... 519 
 
 Armature, description of ... ... 438 
 
 ,, shaft 445 
 
 „ testing 469 
 
 winding ... .. ... 443 
 
 Arrangement of cranks in oil motors •591 
 
 Ash ejector (See's) ... ... ... 149 
 
 Aspinall governor ... ... ... 314 
 
 Assistant cylinder (J oy'sj ... ... 209 
 
 ,, „ diagrams from ... 210 
 
 .Atmospheric air, composition of ... 409 
 
 „ pressure ... ... 369 
 
 Auld's reducing valve ... ... 155 
 
XIV 
 
 Autogenous welding 
 Auxiliary machinery 
 
 ]:>: 
 
 Ind 
 
 -162 
 <J2 
 
 B 
 
 Balance piston 202 
 
 „ weight for crank ... ... 194 
 
 Balanced engines 4 
 
 „ „ Yarrow-Schiick- 
 
 Tweedy system ... ... ^ 
 
 Balanced valve, Andrews- Martin -lO't, 207 
 
 " Bandy " punkah ... 488 
 
 Barometer (aneroid) 320 
 
 „ (mercurial) ... ... 310 
 
 Basic process of steel manufacture 272 
 
 Batteries, galvanic ... 432 
 
 Bayonet Joints ... ... ... 4o9 
 
 IJeam calculations ... ... ...390-4 
 
 Beams... ... ... ... ... 389 
 
 Rearing, main ... ... ... 19 
 
 Bearings, main ... ... ... 16 
 
 Bed-plate chocks 60 
 
 Bell crank for reversing 198 
 
 „ reversing 43 
 
 Bellis and Morcom engine 260 
 
 Bending stress 279 
 
 Bessemer process of steel manufac- 
 ture ... 271 
 
 Bilge and main injection 329 
 
 Blade interference (propeller; ... 531 
 
 Block for crosshead 198 
 
 Blow-off and circulating connec- 
 tions l"il 
 
 Board of Trade allowance of 
 
 amperes ... 491 
 
 „ ,, rules for shafting ... 282 
 
 „ ,, test for steel 27."i 
 
 Boiler and engine data 318 
 
 Babcock type ... ... 171 
 
 Bellville „ 173 
 
 bottom blow-off 163 
 
 Cochran type 168 
 
 corrosion, causes of ... ... 421 
 
 „ e.xamples of 129-31 
 
 „ parts affected ... 421 
 
 „ prevention of ... 422 
 
 deposits ... ... ... 423 
 
 dimensions of ... ... 16.") 
 
 donkey, repairs 167 
 
 efficiency ... ... ... 398 
 
 of 163 
 
 end plate joints ... fo/acelA 
 
 ,, manhole ... fo face 120 
 
 „ riveting ... ... 89 
 
 Haystack type 169 
 
 how secured ... ... ... 156 
 
 jointb, strength of 75 
 
 mountings to face 163 
 
 e.\ 
 
 Boiler repairs 
 riveting 
 
 scale, composition of 
 shell pressure 
 „ strength of 
 „ stresses 
 tube, to cut out 
 tubes ... 
 upkeep and repair, notes on 
 
 1271 
 75 
 
 420: 
 74 
 74, 
 73 
 
 152; 
 
 106' 
 114* 
 
 Boilers 
 
 \'ertical donkey type 
 Water tube ... 
 
 ^'arrow type 
 
 ,, buckled plates 
 
 ,, corrosion in 
 
 „ emptying of 
 
 ,, hand sketches of 
 
 ,, hydrogen gas in 
 
 „ laid up 
 
 „ leakage in ... 
 
 ,, lime and soda 
 
 „ zinc plate allowance 
 Boiling points and steam tempera 
 
 tures 
 Bolt for main bearing 
 Bolts (connecting rod), proportion 
 
 of 
 
 Boring out main bearings ... 
 „ of stern post, iS:c. 
 
 Bottle type salinometer 
 Bottom end "leads" 
 Bottoms of cylinders 
 Bowling hoop furnace 
 Bow-M'Lachlan type steering gear 
 
 Boxes (distribution) 
 
 Boyle's Law of E.xpansion . . . 
 Bracket (guide) for valve spindle 
 Brackets of twin screw steamers 
 Brake (friction) 
 
 „ horse-power, definition of 
 Branch wires, jointing of 
 Brazing 
 
 „ spelter for ... 
 Break in main wires 
 Breakdown of engines 
 „ of pumps 
 
 Brenmie's valve gear 
 Brine temperature difference (re 
 
 frigeration) 
 Brine test for corrosion 
 British Thermal Unit 
 Brock's \alve gear ... 
 Broken armature coil test 
 
 „ L.P. cover ... 
 
 ,, wire test by detector 
 lamp 
 Brown's reversing gear 
 
 „ steam tiller 
 
 „ Telemotor ... 
 
 to f<ue 167 
 
 170 
 
 170 
 
 71 
 
 114* 
 
 114* 
 
 114* 
 
 to face 163 
 
 114* 
 114* 
 114* 
 114* 
 114* 
 
 147 
 18 
 
 il»o 
 
 21 
 
 ."i6 
 
 148 
 
 37 
 
 33 
 
 111 
 
 345 
 
 455 
 
 376 
 
 40 
 
 189j 
 
 599 
 
 372 
 
 480 
 
 277 
 
 274 
 
 467 
 
 290 
 
 294 
 
 223 
 
 573 
 572 
 375 
 227 
 473 
 :»3 
 4C8 
 468 
 214 
 351 
 3.53 
 
Index 
 
 xv 
 
 Bruwn 5 Telemotor, inslruttionb for 
 
 working ... ... ... ... 3.")(j 
 
 Brush holders, test for short circuit 47U 
 
 Brushes i, dynamo) described ... 144 
 
 Bryce-Douglas valve gear 227 
 
 Buckley type piston rings ... ... 54 
 
 Built shafting 278 
 
 Bush of main bearing ... ... 23 
 
 „ valve spindle eye ... ... 186 
 
 Butt (double) strap joint, with dimen- 
 sions to f(UC 83 
 
 Butt (double) strap joint, with dimen- 
 sions ... ... ... ... 8.") 
 
 Butt .double) strap joint, with dimen- 
 
 sioHb ... ... ... lo face 8(> 
 
 Butt straps, thickness of 87 
 
 Cabin fan and motor 
 
 ... 486 
 
 Calcium carbonate 
 
 ... 425 
 
 ,, chloride 
 
 ... 412 
 
 „ sulphate 
 
 ... 420 
 
 Calculations for beams 
 
 ... 393 
 
 „ on Boyle's Law 
 
 ... 378 
 
 Caldwell type steering gear 
 
 ... 344 
 
 Capillary attraction 
 
 ... 370 
 
 Capstan and motor ... 
 
 ... 487 
 
 Carbon 
 
 ... 415 
 
 ,, dioxide 
 
 ... 410 
 
 „ heat in 
 
 ... 41S 
 
 Carbonate anhydride system 
 
 of 
 
 refrigeration 
 
 547-64 
 
 Carbonate of soda 
 
 ... 426 
 
 Carbonated hydrogen gas ... 
 
 ... 411 
 
 Carburetter (Thornycroft type) 
 
 ... 601 
 
 (Wolseley type) 
 
 ... 600 
 
 Care of boilers 
 
 ... 428 
 
 ,, machinery 
 
 ... 67 
 
 Case-hardening 
 
 ... 276 
 
 Casings for piston valves ... 
 
 ... 20 
 
 Cast iron 
 
 ... 274 
 
 „ pistons 
 
 ... 10 
 
 Castings 
 
 ... 267 
 
 Cast-steel pistons 
 
 ... 53 
 
 Caulking tool... 
 
 ... 91 
 
 Caustic soda 
 
 ... 427 
 
 Cavitation of propellers 
 
 ... .520 
 
 Cell Daniellj 
 
 ... 433 
 
 Cementation process of steel manu- 
 
 facture 
 
 ... 26!) 
 
 Jentrifugal force, definition of 
 
 ... 367 
 
 >, pump 
 
 ... 293 
 
 'Chain ' patch 
 
 ... 127 
 
 Charging machine with COj 
 
 ... 564 
 
 -harles' Law of Expansion 
 
 ... 380 
 
 Jheck valve defective 
 
 ... 328 
 
 rhemistry of gases 
 
 ... 40!) 
 
 r.\GLs 
 
 Chloride of magnesium ... ... 423 
 
 ,, of sodium ... ... ... 412 
 
 Chlorine gas and corrosion of stays !)3 
 
 Chocks for bed-plate 60 
 
 Circulating connections ... ... 151 
 
 „ pump 2!j3 
 
 Circulation and priming ... ... 140 
 
 Circumference of propeller... ... 516 
 
 Circumferential shell riveting ... 85 
 Clearance of air pump ... ... 327 
 
 of piston ... ... ... 328 
 
 „ of pumps ... ... ... 52 
 
 CO, burning of ... ... ... 417 
 
 C O.J i carbonic anhydride, pressures 
 
 and temperatures 
 Coal, composition of 
 
 ,, evaporation per pound 
 
 „ gases 
 
 Cock (water gauge; to fuc 
 
 Coil (resistance) 
 Cold-air system of refrigeration 
 Collapse of furnaces, causes of 
 Collapsed furnace, how to strengthen 
 Colour of exhaust gases (oil motors) 
 Column, pump lever, air and feed 
 
 pumps 
 Columns 
 
 ,, how erected 
 ., how lined off 
 ,, types of ... 
 Combined efficiency of plant 
 
 „ steam and hydraulic re- 
 
 versing engine ... 
 '' Combined " strength of steam and 
 
 rivets 
 Combined twisting and bending ... 
 Combustion, air supply required ... 
 „ chamber, bottoms 
 
 „ „ girders 
 
 „ „ method of 
 
 support ... 
 Combustion chamber stays 
 
 „ top riveting... 
 
 ,, chambers 
 
 Combustion, definition of ... 
 general notes on 
 
 565 
 
 407 
 
 164 
 
 416 
 
 163 
 
 . 465 
 
 565-71 
 
 . 117 
 
 116 
 
 590 
 
 187 
 
 16 
 
 ... 26 
 
 ... 28 
 
 to face 16 
 
 ... 399 
 
 337 
 
 86 
 
 282 
 
 415 
 
 101 
 
 101-6 
 
 99 
 101 
 
 88 
 100 
 .369 
 417 
 
 „ (spontaneous) in bunkers 413 
 
 Compensating ring of manhole ... 120 
 
 Composition and strength of steel 274 
 
 ,, of fresh and sea water 418 
 
 „ of exhaust gases (oil 
 
 motors) ... ... 5!)0 
 
 Compression of safety-valve springs 135 
 
 ,, systems of refrigeration 
 
 to face 540 
 Compressor rammonia),overhaulingof 573 
 
 Compressor diagrams I'cold air) ... 570 
 
 Condensation of water in cylinders 383 
 
 Condenser and air pump ... ... 296 
 
XVI 
 
 ndex 
 
 181 
 522 
 221 
 
 60-1 
 to face 198 
 ... 370 
 ... 279 
 16 
 . . . 398 
 ... 395 
 ... 394 
 
 396 
 342 
 
 PAGES 
 
 Condenser and air pump connec- 
 tions to fncc 193 
 
 Condenser on centre ... ... 323 
 
 Condenser ;ind ( irculation connec- 
 tions to face 194 
 
 Condenser back pressure 306 
 
 „ data 296a 
 
 „ tube corrosion, causes of 431 
 
 „ tubes 
 
 Cone for propellers 
 
 Connecting rod angle, effect of ... 
 
 ,, „ length, how measured 327 
 
 ,, proportions ... 195 
 
 rods ... ... ... 12 
 
 ,, rods, training of ... 36 
 
 Connections for main steam to face 180 
 ,, for motor starters ... 484 
 
 „ of feed pumps to face 198 
 
 ,, of pipes 
 
 ,, of pumps 
 
 Conservation of energy 
 
 Constant, 5'1, for torsion 
 
 Construction of engines 
 
 Consumption and H.P. cut-off 
 
 „ I-H.P 
 
 ,, ,, speed 
 
 ,, I.H.P., speed, and 
 
 distance ... 
 
 Control valve of steering gear 
 Corrosion and bronze propeller 
 
 blades ... 
 
 Corrosion and pitting 
 
 „ density and scale 
 
 „ of boilers, causes of 
 
 „ parts affected 
 
 129-31, 420 
 „ ,. prevention of 422 
 
 „ of tail-end shaft 321 
 
 „ of tubes 423 
 
 Corrugated furnaces, advantages of 116 
 
 „ „ manufacture of 116 
 
 Coupling (fle.xible) for paddle shaft 301 
 
 „ (Thomson's patent) 
 Cover of L.P. cylinder broken 
 Crank arrangements in oil motors 
 ,, balance weight 
 ,, balanced 
 
 Cranking of oil motors 
 
 Crank-pin and piston travel 
 ,, ,, flaws 
 
 „ „ lubricator 
 
 Cranks of paddle engines 
 
 Crank-shaft, how lined up 
 
 „ material for ... 
 
 Crank-shafts and columns 
 
 "Crossed" and "open 
 
 rods 
 
 Crosshead and shoe (" single " type) 193-4 
 block 198 
 
 533 
 
 126 
 
 418 
 421 
 
 289 
 
 333 
 
 .591 
 
 194 
 
 23 
 
 585 
 
 331 
 
 332 
 
 178 
 
 299 
 
 388 
 
 16 
 
 23 
 
 eccentric 
 
 211, 256 
 
 Crucibles for above ... ... ... 270 
 
 Crushing strength of materials ... 277 
 
 Current strength, how calculated 493 
 
 Curve of adiabatic e.xpansion ... 368 
 
 „ hyperbolic expansion ... 36K 
 
 Curves, combined ... 405 
 
 „ data for ... ... ... 407 
 
 „ (jf consumption and speed 40<> 
 
 „ of I. H.P. and speed ... 401 
 
 „ of speed and revolutions ... 403 
 
 slip 404 
 
 Cut-off and pressures ... ... 3«5 
 
 „ how affected by connecting 
 
 rod angle ... ... ... 231 
 
 Cut-off, how measured ... 19, 323 
 
 ,, sooner with main valve ... 200 
 
 Cut-outs ... ... ... ... 450 
 
 Cutting by oxygen jet 162 
 
 „ of eccentric keyseats 25, 326 
 
 „ out boiler tubes ... ... 154 
 
 Cylinder clearance allowance ... 377 
 
 „ clearances ... ... ... 44 
 
 „ connections ... ... -51) 
 
 „ covers and bottoms ... 32-3 
 
 „ false face, how secured ... 34 
 
 „ (I. P.) starting valve ... 183 
 
 „ Joy's assistant type ... 209 
 
 „ liner ... ... ... 31-2 
 
 ,, ratios and steam expan- 
 sions 385 
 
 Cylinder ridge, how prevented ... 328 
 Cylinders and shafting, alignment 
 
 of to face Z5 
 
 Cylinders and valve chests 29 
 
 D 
 
 Uaniell cell 4.33 
 
 Data for curves ... 407 
 
 „ of pressures with superheat ... 177 
 
 Davis type steering gear 346 
 
 Defective check valve ... ... 328 
 
 Density and salinometer 147 
 
 ,, and scale ... ... ... 424 
 
 ,, „ general notes on 424 
 
 ,, of steam ... ... ... 371 
 
 „ scale, and corrosion ... 418 
 
 Deposit of oil 420 
 
 „ scale and plate temperature 42i 
 
 Deposits of boilers ... ... ... 423 
 
 Depth of slide-valve face, to find ... 22(i 
 Design of propellers ... 522-29 
 
 Detector (electrical tests) ... ... 467 
 
 Developed area of propeller blades 519 
 
 Diagonal engine ... ... ... 298 
 
 „ pitch of rivets 91 
 
 „ type engines 3 
 
 Diagram of pump connections to face 198 
 
 Diagrams for linked-up gear ... 258 
 
Index 
 
 W'U 
 
 I'AGKS 
 
 Diagrams from cold-air compressor :>H) 
 „ „ ,, expander 571 
 
 „ ,, Joy's cylinder ... 210 
 
 ,, ,, oil motors ... 585-88 
 
 „ of ship performance ... 400 
 
 „ of valve motion ... ... 248 
 
 Diameter and pitch of rivets ... 79 
 
 „ of safely valves ... ... 1.3() 
 
 ,, of shafting,ho\v calculated 281 
 
 Diameter of propeller 518 
 
 Diesel type oil-engine ... 013-19 
 
 Diesel engine, notes and sketches 024-41 
 „ ,, compressor arrange- 
 
 ments 
 Diesel engine, consumption of fuel 
 „ „ cooling circulation ... 
 
 „ „ description of en- 
 
 gines of motor ship " Fionia " 
 Diesel engine, forced lubrication 
 
 system 
 Diesel engine fuel valve lift 
 
 „ „ general description of 
 
 two-cycle 
 Diesel engine heat efficiency 
 ,, „ lubrication ... 
 
 „ power control 
 „ pressures and tem- 
 peratures of three-stage com- 
 pressor ... 
 Diesel engine, reversing 
 
 „ smoke 
 
 „ starting 
 
 „ tests 
 
 ,, wear of valves 
 „ working data of 
 „ working diagram of 
 4-stroke marine... ... /o/aceGM 
 
 Diesel engines, general data of 
 
 marine ... 
 Diesel engines, horse-power of 
 
 petroleum for 
 Dimensions and types of riveted 
 
 joints 
 
 Dimensions of boilers 
 
 ,, of connecting rod 
 
 Disadvantage of patent valve gears 
 
 629 
 032 
 
 027 
 
 033 
 
 041 
 029 
 
 03.-) 
 032 
 627 
 027 
 
 041 
 627 
 629 
 027 
 027 
 029 
 639 
 
 639 
 040 
 639 
 
 ■9-1 
 165 
 195 
 222 
 Disadvantages of superheated steam 137 
 Disc area (propellers) ... ... 519 
 
 dismantling engines ... ... .50 
 
 )isplacement type air pump ... 186 
 
 distance run, Speed, Consumption, 
 
 and I.H.P 396 
 
 )istribution bo.xes ... ... ... 455 
 
 )onkey boiler, Cochran type ... 168 
 
 ,, repairs 167 
 
 „ Vertical type to face 167 
 
 )ouble-acting circulating pump ... 293 
 
 )ouble-beat valve to face \^^ 
 
 >ouble-drum steering gear ... 341 
 
 b 
 
 Double-ported valve 201 
 
 „ valves ... ... 2(i3 
 
 " Doubling plate" 141 
 
 " Drag " surface of propeller lilades 520 
 
 Draught, forced ... 122 
 
 „ natural 121 
 
 Drawing out propeller shaft ... 303 
 
 Dry-air machines (pressures and 
 
 temperatures) ... ... ... 570 
 
 Dryness fraction of steam ... ... 372 
 
 Dynamo, action of, described ... 445 
 
 Dynamos, four-pole 437 
 
 „ hints on running ... 474 
 
 ,, test for polarity of ... 473 
 
 Earth lamp test 472 
 
 Earth leakage test 473 
 
 Eccentric and rods 41 
 
 „ gear in ahead and astern 
 
 positions ... ... ... 212 
 
 Eccentric keyseat templates ... 231 
 
 „ keyseats, cutting off ... 323 
 
 „ keyseats, how cut ... 25 
 
 puHey 14 
 
 „ pulleys, how locked ... 26 
 
 „ rod length 328 
 
 „ rods "crossed" and "open" 2.50 
 
 „ rods, open and crossed ... 211 
 
 „ (single type) 332 
 
 ,, strap ... 15 
 
 Eccentrics ... ... ... ... 15 
 
 Economical speed 401 
 
 „ working 70 
 
 Edwards air pump 292 
 
 „ type air pump ... 186, 191 
 
 Effect on steering due to propellers 533 
 Effects of connecting rod angle on 
 
 cut-off 230 
 
 Effects of link adjustment on I.H.P. 263 
 
 „ linking up 230 
 
 Effective pressure, definition of ... 369 
 
 „ „ (mean) definition of 369 
 
 Efficiency 368, 398 
 
 „ (combined) 399 
 
 „ (mechanical) 399 
 
 of boiler 163,399 
 
 „ of H.P. and L.P. steam 
 
 compared 399 
 
 „ of propulsion ... ... 534 
 
 „ (propeller) 399 
 
 (thermal) 381 
 
 Ejector (See's) for ashes 149 
 
 "Elastic limit" of plates, &c. ... 71 
 
 Electric glow radiator 489 
 
 punkah (G.E.C. type) ... 488 
 
 Electrical H.P. and I. H.P. compared 491 
 
 „ motors 121 
 
XVlll 
 
 Index 
 
 Electrical notes 
 
 Electricity, definition of 
 Electro-ma^^nets 
 Elevator heating system 
 
 End-plate seams 
 
 stays ... ... 
 
 Energy, conservation of 
 „ definition of 
 „ kinetic 
 „ potential 
 Engine room appliances 
 
 „ gauges 
 
 Engine and boiler data 
 
 „ Bellis and Morcom type 
 
 „ for turning 
 
 ,, testing 
 
 Engines, balanced ... 
 
 ,, breakdown of ... 
 
 „ dia>;onal 
 
 „ dismantling of 
 „ oscillating type 
 
 PAGES 
 
 490 
 
 492 
 
 431 
 
 490 
 
 89 
 
 91-8 
 
 370 
 
 367 
 
 373 
 
 373 
 
 303 
 
 192 
 
 318 
 
 260 
 
 180 
 
 ... 290^ 
 
 4 
 
 ... 290 
 
 3 
 
 ... 50 
 
 ... 296 
 
 to face 298 
 
 1 
 
 ... 299 
 
 7 
 
 „ paddle 
 
 „ paddle cranks 
 
 „ quadruple 
 
 J, „ expansion, S.S. 
 
 " Oosterdyk" and " Westerdyk" 
 
 Frontispiece 
 
 „ screw 
 
 „ stopping 
 
 „ trunk type 
 
 Entropy, definition of 
 "Equivalent evaporation" ... 
 „ I.H.P. .. ... 
 
 Erecting machmery m ship 
 
 „ of columns 
 
 Evaporation per pound coal 
 
 Evaporator scale 
 
 „ Weir type 
 
 Examples of boiler corrosion 
 „ of lead adjustment 
 Excessive piston clearance... 
 Exhaust lap gauges ... 
 Expanded diagrams (cold air) 
 Expander for tubes ... 
 Expansion, lioyle's Law of 
 „ curve (Adiabatic) 
 
 „ (Hyperbolic) 
 curves of steam 
 
 1 
 
 ... 290 
 ... 299 
 ... 309 
 ... 163 
 ... 372 
 ... 59 
 ... 26 
 ... 164 
 ... 423 
 ... 305 
 129-31 
 217-8 
 ... 328 
 to face 200 
 ... 571 
 ... 1.00 
 ... 370 
 ... 368 
 368 
 375 
 
 „ joint to face 186 
 
 „ joint of steam pipe ... 140 
 
 „ of steam and heat ... 386 
 
 „ of water by heat ... 386 
 
 „ slot of reversing gear ... 213 
 
 valve 208a, 2083 
 
 Expansions by pressures and 
 
 volumes ... ... ... ■■• 380 
 
 External heat of steam 373 
 
 " Extra " link gear 242 
 
 PAGES 
 
 Fairness of paddle cranks 300 
 
 „ of shaft and cylinders ... 187 
 False face of cylinder, how fixed ... 34 
 Fan and motor ... ... ••• 486 
 
 Feathering paddle wheel 301 
 
 Feed heater. Weir s 303 
 
 „ heating, advantages of ... 306 
 
 ,, pump connections ... to face 198 
 
 „ „ Weirt\pe 308 
 
 „ „ Worthington type ... 314 
 
 „ water filter ... 313 
 
 Ferric oxide ... .■• ••• •■• 412 
 Ferrules of condenser tubes ... 181 
 
 Field magnets, description of ... 436 
 Fire-bars, dimensions of ... ...118-9 
 
 Fitting of running gear 36 
 
 Flat surfaces ... ... ... ••• 95 
 
 Flaws in shafts ... •■• ••• 326 
 
 „ L.P. crank-pins ... 332 
 
 „ on shafting, how repaired ...285-9 
 
 Following edge oi propeller blade 520 
 
 Foot pound, definition of 366 
 
 Force, centrifugal, „ 367 
 
 367 
 
 Forced draught 122-6 
 
 „ lubrication system ... ... 641 
 
 Four-cycle oil motors ... ... 579 
 
 Four-pole dynamos .■• 437 
 
 Free nitrogen 411 
 
 Fresh water, composition of ... 418 
 
 Friction brake ... ... ■•• 599 
 
 „ laws of 367 
 
 Funnel gases, weight of 164 
 
 Furnace, Adamson ring type ... 110 
 ,, bowling-hoop „ ... Ill 
 
 „ corrugations, types of ... 117 
 
 „ Fox tvpe tofaceWZ 
 
 „ front riveting 114 
 
 „ Gourley-Stephen type ... 106 
 
 „ manufacture 116 
 
 „ method of strengthening 115 
 
 „ suspension bulb type ... 112 
 
 „ temperatures, &c. ... 118 
 
 Furnaces, causes of collapse ... 117 
 
 Fuses 450 
 
 Galvanic action, definition of ... 430 
 
 cells 432 
 
 Gases, retention of 127 
 
 „ velocity of 164 
 
 Gauge for water level 146 
 
 „ for wear-down tests 62-3 
 
 „ indications ... 318 
 
 „ pressure, definition of ... 309 
 
I ndex 
 
 XIX 
 
 fAGES 
 
 ... 192 
 ... 223 
 ... 227 
 ... 227 
 179, 213 
 ... 22G 
 
 Gauges for pressures 
 Gear, Bremme's patent 
 Brock's 
 
 Bryce-Douglas 
 „ for reversing ... 
 „ Hackworth's ... 
 ,, in "ahead"' and "astern" 
 
 positions... ... ... ... 212 
 
 (Jear, Joy's 225 
 
 „ Marshall's patent 223 
 
 „ Morton's 225 
 
 General definitions 366 
 
 ,, electricalnotesandsketches, 
 with diagrams ... ... 494 509 
 
 General notes and descriptions ... 264 
 Gourley-Stephen furnace ... to face 106 
 
 Governor, Aspinall's ... ... 314 
 
 Graphic method of proving boiler 
 
 shell stresses ... ... ... 72-3 
 
 Grate surface and heating surface 127 
 
 Gravity, definition of ... ... 369 
 
 Grooving in boilers ... ... ... 426 
 
 Gross or absolute pressure, defini- 
 tion of 369 
 
 Guide bracket, for valve spindle ... 40 
 
 Guides, single type ... ... ... 15 
 
 Gumminess of oils ... ... ... 428 
 
 Gun-metal ... ... ... ... 274 
 
 G.E.C. type arc lamps 462 
 
 ,, projector ... ... 463 
 
 H 
 
 Hackworth's valve gear ... ... 226 
 
 Hall system of CO.j refrigeration 547-60 
 
 Hand-riveting ... ... ... 90 
 
 Hard steel 274 
 
 Hardness (permanent) of water ... 420 
 
 „ (temporary) „ ... 420 
 Haslam system of ammonia re- 
 frigeration ... ... 544-47 
 
 Haslam system of COo refrigeration 560-62 
 „ of cold air refrigera- 
 tion 565-71 
 
 Hastie type steering gear ... ... 349 
 
 Haystack boiler 169 
 
 Heat absorbed in natural draught 121 
 
 and e.xpansion of steam ... .386 
 
 definition of .366 
 
 efficiency ,381 
 
 in carbon ... ... ... 418 
 
 in one pound coal 409 
 
 latent, definition of ... ... 367 
 
 sensible, „ 367 
 
 . total, „ 367 
 
 ,j unit, „ 366 
 
 .ieater for feed water (Weir's) ... 303 
 
 ■f eating, eftect of scale ... .,. 427 
 
 PAGES 
 
 Halting surface and grate surface 127 
 High-pressure steam, advantage of 384 
 Hints on running dynamos... ... 474 
 
 Horse-power (brake or shaft > ... 372 
 
 Horse-power, definition of 366 
 
 ,, equivalent 372 
 
 ,, of Diesel engines ... 640 
 
 Hot-well temperature and condenser 
 
 pressure ... ... ... ... 366 
 
 Howden's forced draught ... 122-26 
 
 H.P. cut-off and consumption ... ,398 
 
 ,, cylinder broken beyond repair 290(f 
 
 ,, piston valve broken beyond 
 
 repair 
 H.P., I. P., or L.P. piston broken 
 
 beyond repair ... 
 Hydraulic accumulator 
 
 „ „ advantages of 
 
 ,. and steam reversing gear 
 
 214, 337 
 
 ,, crane 
 
 ,, piston packing ... 
 
 Hydrochloric acid ... 
 Hydrogen 
 
 Hydrokineter (Weir's) 
 Hydrometer described 
 Hyperbolic expansion curve 
 
 290/- 
 
 290/- 
 335 
 3.35 
 
 337 
 
 ... 215 
 412, 422 
 ... 415 
 ... 141 
 ... 427 
 ... 368 
 
 I.H. P. and consumption 395 
 
 „ and E.H.P. (electrical) com- 
 pared ... 491 
 
 I. H.P. and link adjustment ... 263 
 
 „ „ speed curve ... ... 401 
 
 ,, (equivalent) ... ... ... 372 
 
 Improvement in propeller, effect of 533 
 
 Incandescent lamps ... 457 
 
 Increasing pitch (propeller) ... 517 
 
 Incrustation, composition of ... 419 
 
 Indications of gauges ... ... 318 
 
 Induction, definition of ... ... 492 
 
 Inertia, definition of 367 
 
 Initial condensation ... ... 383 
 
 ,, pressure, definition of ... 369 
 
 Injection, main and bilge 329 
 
 Instructions for working Brown's 
 
 Telemotor ... ... ... 356 
 
 Instructions for working CO^machine 553 
 
 Insulating of joints 479 
 
 Interference (propeller blade) ... ."»31 
 
 Internal combustion engines — 
 
 Advantages of ... ... ... 574 
 
 and steam engine... ... ... 580 
 
 B.H.P. of 599 
 
 Carburetter 584 
 
 Colour of e.xhaust gases 590 
 
 Crank arrangements ,,. ... 591 
 
XX 
 
 Index 
 
 I'AGES 
 
 Internal Combustion Engines — contd. 
 Cranking ... ... ... ... 585 
 
 Diagrams from ... ... 595-98 
 
 Diesel type 613-19 
 
 Disadvantages of 574 
 
 Explosion systems ... ... 577 
 
 Firing plug ... 584 
 
 Four-cycle... ... ... ... 579 
 
 Ignition 586 
 
 l.H.F. of 598 
 
 Magneto 586 
 
 ,, setting of 589 
 
 Mean pressure ... ... ... 598 
 
 Number of cylinders ,.. ... 583 
 
 Paraffin and petroleum ... ... 578 
 
 Petrol 578 
 
 Pistons 583 
 
 Pressures and temperatures ... 584 
 
 Reversing 591 
 
 Revolutions 583 
 
 Speed control 592 
 
 Starting of 592 
 
 Troubles classified ... 592-94 
 
 „ of 589-90 
 
 Two-cycle 579 
 
 Types of 599-G07 
 
 Valves 584 
 
 Water jacket 583 
 
 Internal heat of steam 373 
 
 I. P. cylinder cover broken beyond 
 
 repair 290/^ 
 
 Iron and steel manufacture ... 204 
 
 ,, malleable 267 
 
 „ oxide 423 
 
 „ tubes and stavs 313 
 
 Joint, insulating of ... 
 
 .. 479 
 
 „ (scarfed) 
 
 .. 479 
 
 Joints and riveting ... 
 
 .. 78 
 
 Joints, bayonet pattern 
 
 .. 459 
 
 „ (scarfed) 
 
 .. 142 
 
 „ (types of I, with dimensions 
 
 78-91 
 
 Jointing of branch wires 
 
 .. 480 
 
 „ main cables 
 
 .. 479 
 
 „ wires 
 
 .. 478 
 
 Joy's assistant cylinder 
 
 .. 209 
 
 „ „ „ diagrams 
 
 .. 210 
 
 „ valve gear 
 
 .. 225 
 
 Jump-spark ... 
 
 .. 586 
 
 K 
 
 Keeping a watch 
 
 Keyseats for eccentrics, cutting of 
 „ „ how cut . . 
 
 323 
 
 Keyseats 'or eccentrics, position of 231 
 
 Kilowatt 492 
 
 Kinetic energy 373 
 
 Klinger type water gauge ... ... 153 
 
 Lap, exhaust ... 2(X) 
 
 „ joint, double riveting 78 
 
 „ „ single , 78 
 
 „ „ treble , 78 
 
 ,, minus exhaust ... 200 
 
 „ steam 20<J 
 
 Lamont pump ... ... ... 316 
 
 Lamp (pilot) ... ... ... ... 477 
 
 „ switches 456 
 
 Lampholders 459 
 
 Lamps, incandescent type ... ... 457 
 
 ,, Osram type 458 
 
 Latent heat, definition of .367 
 
 of XH.. and CO, ... 564 
 
 „ of steam ... ... 373 
 
 Law of Expansion (Boyle's) ... 376 
 
 „ „ calculations ... 37.S 
 
 „ „ (Charles') ... 380 
 
 Lead 20(( 
 
 „ adjustments 216-9 
 
 ,, of piston valve, how measured 215 
 
 Leading edge of propeller blade ... 520 
 
 " Leads" of bottom end ... ... 37 
 
 ,, of main bearings, how 
 
 taken 24 
 
 Leakage in magnet coils 468 
 
 Leaky pistons (oil motors) 590 
 
 „ tubes 133 
 
 ,, ,, causes of 424 
 
 Leather packing of hydraulic 
 
 piston ... 215 
 
 Length of connecting rod, how 
 
 found ..." 327 
 
 „ eccentric ., ,, 328 
 
 ,, propeller ... 518 
 
 „ „ blade 518 
 
 „ valve spindle, how found... 327 
 
 Lift of pumps ... .. ... .387 
 
 Lignum vita' strips ... 181 
 
 Lime 426 
 
 „ in boilers, action of 427 
 
 Limit of elasticity ... 71 
 
 Liners for cylinders ... ... 31-2 
 
 „ for piston valves ... ... 29 
 
 ,, of tale-end shafts ... ... .55 
 
 Lining-off of colunms ... ... 28 
 
 ,, the soleplate ... ... 20. 
 
 Lining up crank-shaft 388 
 
 ,, of shafting ... ... 352 
 
 Link adjustment and I.H.I'. ... 263 
 
 „ brasses and pump clearance 327 
 
Ind 
 
 ex 
 
 XXI 
 
 Link motion 229 
 
 Linking up, effects of 230 
 
 ,, gear diagrams... ... 258 
 
 Litmus paper tests 429 
 
 Liverpool Refrigeration Co., am- 
 monia system ... ... 512-44 
 
 Liveri)ool Refrigeration Co, COo 
 
 system ... ... ... 562-64 
 
 Loose eccentric ... ... ... 332 
 
 Loss of power in oil motor... ... 5S9 
 
 „ of vacuum, cau-es of ... ... 294 
 
 Losses of power ... ... ... 535 
 
 L.P. crank-pin flaws ... ... 332 
 
 „ cylinder cover, broken ... 333 
 
 „ piston (naval typet ... ... 184 
 
 Lubricating oils ,.. ... ... 428 
 
 Lubrication of crank-pin ... ... 178 
 
 Lubricator ... ... ... .... 334 
 
 M 
 
 .Machine ri\eting 88-90 
 
 Machinery, erection in ship ... 59 
 
 „ upkeep 67 
 
 Magnesium chloride ... ... 423 
 
 Magneto 587 
 
 „ setting of 589 
 
 Main and bilge injection 326 
 
 „ bearing bolt ... ... ... 18 
 
 „ „ bush ... ... ... -li 
 
 „ ,, bushes, boring out ... 21 
 
 „ „ complete 19 
 
 „ bearings 16 
 
 , „ cables, jointing of 479 
 
 „ switches 449 
 
 ,, wires, short circuit in ... 473 
 
 Make-and-break spark 586 
 
 Malleable iron 267 
 
 .Manholes 119 
 
 Manufacture of furnaces ... ... 116 
 
 I „ of iron and steel ... 264 
 
 iMarine Diesel engines, general data 639 
 
 „ electric lighting 432 
 
 „ engineering chemistry ... 408 
 
 Marking off ship for boring out ... 56 
 Marsh gas (Methane) ... 411,413 
 
 Marshall's valve gear ... ... 223 
 
 Martin-Andrews balanced valve ... 205 
 
 VI aterial for shafting ;i87 
 
 Materials, crushing strength of ... 277 
 
 „ ^ tensile strength of ... 277 
 
 ;Iean effective pressure, definition of 369 
 
 Measurement of piston clearance... 328 
 
 |! )j „ valve head 215 
 
 [rleasuring pitch of propeller ... 322 
 
 [ „ the cut-off .. ... 49 
 
 'lechanical efficiency 399 
 
 ,, equivalent of heat ... 366 
 
 I'AtiliS 
 
 Megohm, value of ... 493 
 
 Mercurial barometer ... ... 320 
 
 Metallic packing 1] 
 
 „ . (U.S.) 359 
 
 Methodofchargingmachine with COo 563 
 „ locating centre of piston- 
 rod 290c 
 
 „ locking eccentric pulleys 26 
 
 ,, patching boiler plates ... 12S 
 „ securing false face of 
 
 cylinder ... ... 34 
 
 „ setting valves 47 
 
 ,, supporting combustion 
 
 chambers ... ... 9!J 
 
 „ testing if guides parallel 
 to shaft centre line 
 
 foface ^md 
 „ testing if guides parallel 
 
 to piston rod ... to face 290f 
 
 Mild steel 274 
 
 Milton, J. T., Esq., description of 
 
 Diesel engine 614 
 
 Mineral oils 428 
 
 Minus exhaust lap ... ... ... 200 
 
 Moment of l:)ending... 281 
 
 „ twist 281 
 
 Momentum, definition of ... ... 369 
 
 Morcom and Belliss engine ... 260 
 Morison type corrugated furnace ... 114<? 
 
 Morton's valve gear ... 225 
 
 Motor and cabin fan 486 
 
 „ and capstan 487 
 
 „ and centrifugal pumps ... 486 
 
 „ launch propellers ... ... 531 
 
 „ ship " Fionia," description of 
 
 engines 633 
 
 ,, starter connections ... ... 484 
 
 „ starting resistance 510 
 
 „ troubles 589 
 
 Motors, electrical 481 
 
 ,, starting switches ... ... 483 
 
 types of 599-607 
 
 Mountings of boilers ... to face \^'^ 
 
 Muntz metal 274 
 
 N 
 
 Natural draught ... 121 
 
 ,, ,, heat absorbed in... 121 
 
 Naval brass 274 
 
 „ type L.P. piston 184 
 
 „ „ piston rod 196 
 
 Negative slip (propellors) 521 
 
 „ wires, how marked ... 492 
 
 Neutral a.xis of beam .390 
 
 NH3 (ammonia) pressures and tem- 
 peratures ... .565 
 
 Nickel steel 274 
 
XXll 
 
 Inde: 
 
 Nitrate of silver test 
 Nitrogen 
 
 for density 
 
 Non-freezing fluid for telemolors 
 Notes and sketches of various details 
 
 ,, (electrical 
 
 „ on boiler upkeep and repair 
 
 ., on density and scale 
 Number of cylinders in oil motors 
 Nuts, proportions of 
 
 PAt.KS 
 
 ... 427 
 ... 42G 
 411,415 
 ... .3.-)9 
 
 178 
 490 
 114/' 
 124 
 r.8.3 
 1!H) 
 
 o 
 
 Ohm, definition of ... ... ... Wl 
 
 Oil deposit 420 
 
 „ engine, Diesel type ... G13-19 
 
 Oil-feed box ... \ 197 
 
 Oil fuel fi07 
 
 advantages of ... ... 608 
 
 „ air cone ... 612 
 
 „ ., vessel ... ... ... 612 
 
 ,, and coal compared ... 608 
 
 ,, black smoke ... ... 612 
 
 „ burners ... ... ... 609 
 
 „ colour of gases ... ... 611 
 
 ,, composition of oil ... ... 609 
 
 „ control ... 611 
 
 „ disadvantages of ... ... 608 
 
 „ evaporation of oil ... ... 613 
 
 flash point, iS:c. ... ... 612 
 
 „ leakage test... ... ... 611 
 
 ,, methods of working ... 609 
 
 „ oil spray ... ... ... 609 
 
 „ sand ... ... 612 
 
 „ settling tanks 612 
 
 „ shale oil 610 
 
 „ starting up 611 
 
 „ ventilation pipes ... ... 612 
 
 „ water in oil 613 
 
 „ white smoke ... ... 612 
 
 „ ,, vapour ... ... 613 
 
 ,, working 611 
 
 Oil motor and steam engine compared 582 
 
 Oil motors ... 582 
 
 „ carburetter of 584 
 
 „ diagrams from ... 595-98 
 
 „ fly-wheel of 584 
 
 „ number of cylinders 
 
 employed ... ... '^K\ 
 
 ,, pressures and tempera- 
 tures ... ... ... 584 
 
 ,, "sleeve" valve 584 
 
 „ sparking plug of ... 584 
 
 „ speed regulation of ... 592 
 
 „ starting of 592 
 
 „ troubles of ... 592-94 
 
 „ valves of ... ... 584 
 
 428 
 
 Oils 
 
 i'AOES 
 
 Oils, classes of ... .. ... 428 
 
 „ emulsion of ... ... ... 428 
 
 ,, gumminess of ... ... ... 428 
 
 „ saponification of ... ... 428 
 
 ,, to test acidity of 429 
 
 ,, viscosity of ... 428 
 
 "()pen" and "crossed" eccentric 
 
 rods 211,2.56 
 
 <Dscillating cylinder and trunnions 297 
 
 „ engines 296 
 
 Osrani lamps ... ... ... 458 
 
 Overhanging ammonia compressor 573 
 
 0.\ide of iron ... ... ... 423 
 
 0.\ygen jet 'cutting by) 162 
 
 Packing, metallic ... 11 
 
 „ of hydraulic piston ... 215 
 
 ,, rings ("restricted") type 204 
 
 U.S. metallic 3.59 
 
 Paddle engine cranks 299 
 
 „ ,, to test fairness 
 
 of 30(» 
 
 Paddle engines ... ... ... 1 
 
 ,, shaft flexible coupling ... 301 
 
 „ wheel (feathering) ... ... 301 
 
 Paraffin and petroleum 578 
 
 „ oil, use in boilers ... ... 426 
 
 Parson's white metal ... ... 274 
 
 Patch, chain type ... ... ... 127 
 
 Patent shaft coupling (Thomson's) 289 
 
 Patent valve gears ... 222 
 
 ,, ,, advantage of ... 222 
 
 „ „ disadvantage of 222 
 
 ^, „ Marshall's ... 223 
 
 „ ,, Bremme's ... 223 
 
 „ Morton's ... 225 
 
 ,, ,, Joy's 225 
 
 „ ., Hack worth's ... 226 
 
 Permanent hardness of water ... 420 
 
 Pet valves 295 
 
 Petrol 578 
 
 Petroleum vapour ... ... ... 411 
 
 „ for Diesel engines ... 389 
 
 Phosphor bronze ... .. ... 274 
 
 Pig-iron 266 
 
 Pilot lamp 477 
 
 Pipe connections ... ... ... 60-1 
 
 Pipes, steam ... ... 139 
 
 Piston and crank-pin travel ... 331 
 
 „ cast-iron type 10 
 
 „ clearance ... ... ... 328 
 
 „ „ excessive 32h 
 
 „ „ how measured ... 328 
 
 „ (L.P.), naval type 184 
 
 „ pumps 293 
 
 „ rings, Buckley type 54 
 
Index 
 
 will 
 
 PAGES 
 
 Piston rod and ciosshead ... 193, 194 
 
 „ „ naval type 196 
 
 „ ,, to test fairness of ... 327 
 
 Piston valve (Admiralty type) ... 202 
 
 „ and piston positions ... 237 
 
 „ lead, how measured ... 215 
 
 ,, liner ports and bars ... 29 
 
 ,, liners 29 
 
 „ ring 201 
 
 Piston valves 206 
 
 „ with restrained rings 208 
 
 Pistons 9,388 
 
 „ cast steel r)3 
 
 „ leaky (oil motors) ... ... .599 
 
 „ of oil motors ... ... .'183 
 
 Pitch and diameter of rivets ... 79 
 
 „ (diagonal) of rivets ... ... 91 
 
 „ of rivets for equal strength for 
 
 steam and rivet section ... 78 
 
 Pitting and corrosion 126 
 
 „ remedies for ... ... 430 
 
 Plates flanged out ... 142 
 
 „ tensile strength of ... ... 71 
 
 „ zinc .. 143 
 
 Plugs (wall) 459 
 
 „ watertight 460 
 
 Position of eccentric keyseats ... 231 
 
 Positions of piston and valve ... 236 
 
 „ of valve and piston to face 238 
 
 Positive wires, how marked ... 492 
 
 Potential (electrical), definition of 490 
 
 „ energy 373 
 
 Power and revolutions 279 
 
 „ and speed curve ... ... 402 
 
 ,, definition of 366 
 
 ,, (horse), definition of ... 366 
 
 „ loss in oil motor 589 
 
 ,, losses ... ... ... ... 535 
 
 ,, utilisation of ... ... ... 535 
 
 Pressure, atmospheric ... ... 369 
 
 „ effective 369 
 
 „ gauge 369 
 
 „ ,, indications ... 318 
 
 „ gauges 192 
 
 ,, gross or absolute ... 369 
 
 „ initial 369 
 
 „ mean effective 369 
 
 ,, terminal 369 
 
 Pressures and cut off 385 
 
 „ and temperatures of NH.-, 
 
 and CO2 .565 
 
 Pressures and temperatures of three- 
 stage compression ... ... 641 
 
 Pressures and volumes 382 
 
 Prevention of ridge in cylinder ... 328 
 
 Priming of boilers and circulation 140 
 
 Producer system action 576 
 
 „ „ consumption of ... 577 
 
 ,, ,, cooler and scrubber 576 
 
 I'AGB.S 
 
 Producer system, efficiency of ... 577 
 
 „ „ (gas) 576 
 
 „ „ heat value of ... 577 
 
 „ ,, steam generator 576 
 
 ,, „ test burner ... 577 
 
 Projector arch lamp ... ... ... 463 
 
 Propeller blade interference .. 531 
 
 „ „ to fit on 529 
 
 „ blades (bronze) 533 
 
 „ design 522-29 
 
 „ efficiency ... ... ... .399 
 
 „ (Gaine's reversible) ... 591 
 
 ,, improved, effect of ... 533 
 
 „ pitch, how measured ... 322 
 
 „ „ to find ... ... 531 
 
 „ shaft, drawing out of ... 363 
 
 ,, „ liners, how secured 55 
 „ turbine type ... to face bZO 
 
 Propellers 514 
 
 „ area, ratio of ... ... 519 
 
 ,, cavitation ... ... 520 
 
 „ circumference of ... 516 
 
 „ cone 522 
 
 „ developed area of .. 519 
 
 ,, diameter of 518 
 
 „ disc, area of ... ... 519 
 
 „ drag surface ... ... 520 
 
 „ following edge ... ... 520 
 
 „ for motor launches ... 531 
 
 „ increasing pitch 517 
 
 „ leading edge 520 
 
 „ length of 518 
 
 „ „ blade 518 
 
 „ moulding of blades ... 518 
 
 „ negative slip 521 
 
 ,, pitch ... ... ... 515 
 
 „ ,, ratio 518 
 
 „ projected area 519 
 
 „ racing 522 
 
 „ right and left hand ... 516 
 
 ,, set back ... ... ... 522 
 
 „ slip 519 
 
 „ thread 516 
 
 „ thrust ... ... ... 515 
 
 ,, „ surface 520 
 
 ,, true screw surface ... 518 
 
 „ wake speed 519 
 
 Proportions of connecting rod ... 195 
 „ „ „ bolts, 
 
 &c 190 
 
 Propulsive efficiency ... ... 534 
 
 Puddling furnace ... ... ... 268 
 
 Pulley and strap 14 
 
 Pulleys, how locked ... ... ... 26 
 
 Pulsometer type pump ... ... 364 
 
 Pump (air), naval type ... ... 185 
 
 ,, centrifugal type ... ... 293 
 
 „ clearance and link brasses ... 327 
 
 „ clearances ... ... ... 52 
 
XXIV 
 
 lUlCX 
 
 I'AOES 
 
 ruini) connection diaj^iam to face 198 
 
 „ (feed), connections of „ 198 
 
 „ lifts ;W7 
 
 „ link?, how trammelled ... 'il 
 
 Pumps 1^91 
 
 „ breakdown of 294 
 
 „ Edwards' patent 29:i 
 
 ,, Lament's ... ... ... 3H! 
 
 „ Weir's 30H 
 
 ,, Worth ington's 314 
 
 I'unkah (electric). (;E.C. type ... 4S8 
 
 Ouadrant and block 229 
 
 Quadruple engines ... 7 
 
 „ „ S.S. "Oosterdyk"' 
 
 and " Westerdyk " ... Frontispiece 
 
 R 
 
 Racing of propeller 522 
 
 Radiators (electrical) " 489 
 
 Ranibbottom rings 53 
 
 Ratio of cylinders and expansions 385 
 „ pitch to diameter ... ... .")18 
 
 Reduced pressure steam, superheat- 
 ing of ... ... ... ... 157 
 
 Reducing valve (Auld's) ... ... 155 
 
 Refrigeration ... 539 
 
 ,, ammonia system 539-47 
 
 „ CO.^ 547-64 
 
 ., cold air ... 5fj5-71 
 
 „ general notes on ... 571 
 
 „ compression systems 
 
 to face 540 
 joint testing ... ... 573 
 
 ,, leaky compressor ... .562 
 
 ,, pressures and tem- 
 
 peratures employed ... ... 572 
 
 Relief ring 203 
 
 ,, frame ... 204 
 
 Remedies for pitting ... ... 43J 
 
 Repair for broken H.P. cylinder 
 
 ioj^ce 290<r 
 „ „ leaky telescope furnace 
 
 joint 114 
 
 Repair for weak fire bo.\ ... ... 167 
 
 Repair of shafting 285-89 
 
 Repairs for boilers ... ... ... 127 
 
 Resistance and arc lamp ... ... 466 
 
 „ coil ... 465 
 
 „ (hull) .535 
 
 ,, regulator 485 
 
 Restricted type packing ring 204, 208 
 Retention of gases and furnace 
 
 collapse ... ... ... ... 127 
 
 Reversing bell crank ... 43,198 
 
 Reversing gear 179 
 
 „ " gear " and " expansion " 
 
 slot 21.3 
 
 Reversing gear (Brooke) 007 
 
 ,, „ steam and hydraulic 214 
 
 ,, of oil motors 591 
 
 „ quadrant and block ... 229 
 
 shaft 42 
 
 Revolution and speed curve ... 403 
 
 Revolutions and power ... ... 279 
 
 Revolutions of oil motors 583 
 
 Ridge in cylinder, pre\ention of ... 328 
 
 Right and left hand propellers ... 516 
 
 Rings, Buckley type 54 
 
 Rivet and seam, combined strength 86 
 
 „ section... ... ... ... 77 
 
 Rivets, diagonal pitch of ... ... 91 
 
 Riveting hand ... ... ... 90 
 
 „ machine 88-90 
 
 ,, of combustion chamber top 88 
 
 „ of furnace from ... ... 114 
 
 „ single ... 79 
 
 Rocking shaft, how tested ... ... 326 
 
 Running gear, fitting of 36 
 
 „ hints (dynamos) 474 
 
 Rusting • 426, 430 
 
 Safety valves 
 
 Salinometer and density ... 
 
 133-6 
 ... 147 
 
 „ (bottle type) ... 
 Saponification of oils 
 
 ... 148 
 ... 428 
 
 Saturation-point of water ... 
 
 ... 424 
 
 Scale, composition of 
 
 ... 419 
 
 „ density and corrosion 
 
 ... 418 
 
 „ from evaporators 
 Scarfed joint 
 
 ... 423 
 
 ... 479 
 
 ,, joints 
 
 ... 142 
 
 Schmidt type superheater ... 
 
 177, \"a 
 
 Screw engines ... ... ... 1 
 
 „ (twin or triple) stern brackets 189 
 
 Screws (twin) 
 
 ... 5.33 
 
 Seam section 
 
 77 
 
 Sea water, composition of ... 
 
 ... 419 
 
 Securing of boilers in position 
 
 ... 156 
 
 See's ash ejector 
 
 Sensible heat, definition of... 
 
 ... 149 
 ... .367 
 
 Series arrangement of arc lamps ... 466 
 Serve type of tube ... ... ... 108 
 
 Set back of propeller blades 
 
 ... 522 
 
 Setting of valves 
 
 47, 219 
 
 „ of valve, tables of ... 
 
 2.39-48 
 
 „ valve to mid travel ... 
 
 ... 323 
 
 Shaft and cylinder alignment 
 
 to face 35 
 
 „ corrosion of 
 
 ... .321 
 
 „ diameter, how calculated 
 
 ... 281 
 
 „ flaws 
 
 ... .326 
 
Inde: 
 
 XXV 
 
 .Shaft hoibC-power, dertnilion of ... 372 
 
 Shafting, B. of T. rules for 282 
 
 „ built 278 
 
 „ flaws on ... ... ... 284 
 
 ,, how repaired 28.")-9 
 
 „ lining up of ... ... 324 
 
 „ Lloyd's rules for 282 
 
 „ material 387 
 
 „ strength of ... ... 278 
 
 Short circuit tests ... ... ... 467 
 
 Shortness i)f water in boiler ... 1G4 
 
 Shrinking-on of shaft liners ... 55 
 
 Sight-feed lubricator 334 
 
 Sighting of shaft 325 
 
 Simni's magneto ... ... ... 587 
 
 Single eccentric ... ... ... 332 
 
 „ riveting ... ... ... 79 
 
 Single-type guide ... ... ... 15 
 
 Single-wire system ... ... ... 451 
 
 Siphon, action of ... ... ... 370 
 
 Siphon-feed oil bo.x ... ... ... 197 
 
 Sketches of boilers ... ... /(> /'dec }G'i 
 
 Slide valve and piston positions ... 236 
 
 „ to find depth of ... 220 
 Slip, description of, by T. Sidney 
 
 Cockrill, Esq. ... ... ... 536 
 
 [ Slip (negative) 521 
 
 I „ (propeller) 519 
 
 Soda, use of ... ... ... ... 425 
 
 ' Sodium chloride ... ... ... 412 
 
 j Soleplate 16 
 
 I „ lining off 20 
 
 Solids in sea water ... ... 425 
 
 Sparking plug ... ... ... 584 
 
 Speed and consumption 395 
 
 ,, „ curve ... 400 
 
 „ and power ,, ... 402 
 
 ,, and slip ,, ... 404 
 
 „ of wake ... ... ... 519 
 
 „ regulation of oil motors ... 592 
 
 Specific gravity, definition of ... 368 
 
 „ heat, „ „ ... .368 
 
 Spelter for brazing 274 
 
 ji Spontaneous combustion 413 
 
 f; „ ,, causes of 414 
 ,, ,, prevention 
 
 of 414 
 
 Spontaneous combustion, treatment 
 
 • of 414 
 
 Spindle eye bush of valve 186 
 
 Spindles of valves 13 
 
 1 Squared paper diagrams 400 
 
 I Starters for motors 483 
 
 „ „ connections of 484 
 
 Starting of oil motors 592 
 
 „ valve (I. P. cylinder) ... 183 
 
 Stay tubes and ordinary tubes ... 107 
 
 Stays for end plates 91-8 
 
 for tube plates 
 
 to face 115 
 
 Steam and hydraulir rever^mg 
 
 engine ... ... ... ... 337 
 
 Steam consumption per revolution 383 
 
 ,, definition of ... ... ... 367 
 
 „ density ... ... ... 371 
 
 ,, dryness, fraction of ... ... 372 
 
 „ efficiency 398 
 
 „ expansionsandcylinderratios .385 
 ,, „ by pressures and 
 
 volumes ... ... ... 380 
 
 „ external, heat of ... ... 373 
 
 ,, in cylinder, action of ... 238 
 
 ,, internal „ ... ... 373 
 
 „ lap 200 
 
 „ latent „ 373 
 
 „ (main) connections ... /o face 180 
 
 ,, pipe expansion joint ... 140 
 
 „ pipes ... ... .. ... 139 
 
 „ „ water hammer in ... 139 
 
 ,, pressures and volumes ... 382 
 
 „ saturated definition of ... 375 
 
 ,, space stays ... ... ... 91-4 
 
 ,, superheated by reducing 
 
 valve ... ... ... 157 
 
 ,, superheated, definition of ... 376 
 
 ,, tiller (Brown's) ... ... 351 
 
 „ total heat of 373 
 
 „ wet, definition of ... ... 376 
 
 Steel, B. of T. test for ... ... 275 
 
 ,, manufacture, Bessemer process 271 
 „ ,, basic „ 272 
 „ ,, cementation pro- 
 cess 269 
 
 Steel manufacture, Siemens- Martin 
 
 process ... ... .. ... 272 
 
 Steel, production of 269 
 
 „ strength and composition of 274 
 
 ,, tempered ... ... ... 271 
 
 „ tempering of ... ... ... 276 
 
 Steering gear action of valves ... 343 
 Steering gear, by Messrs Alley &. 
 
 M'Lellan 348 
 
 Steering gear, by Messrs Bow, 
 
 M'Lachlan&Co 345 
 
 I .Steering gear, by Messrs Caldwell 
 
 I & Co 345 
 
 Steering gear by Messrs Davis & Co. 346 
 
 „ „ by Messrs Hastie & Co. 349 
 
 „ „ control valve ... 342 
 ,, „ transmission system 
 
 to face 341 
 
 ,, gears ... ... ... 340 
 
 Steering, how affected by propellers 533 
 
 Stern post, boring out ... ... 56 
 
 „ tube after bearing bush ... 181 
 
 „ ,, and shaft ... ... 361 
 
 „ „ Cedervall's Patent ... 362 
 Stopper for boiler tubes (Bagguley 
 
 Patent) foface 133 
 
XXVI 
 
 nclex 
 
 PAGES 
 
 Stopping of engines 290 
 
 Straightening action of gauge tube 329 
 
 Strain, definition of 368 
 
 Strength and composition of alloys 274 
 
 „ (tensile) of steel ... ... 71 
 
 Strengthening of weak furnace ... 116 
 
 Stress, bending 279 
 
 „ cin umferential ... ... 72 
 
 „ definition of ... ... ... 367 
 
 ,, longitudinal ... ... ... 73 
 
 „ of thrust l)lock 182 
 
 „ torsion .. ... ... 279 
 
 Stresses on boiler shell 71 
 
 „ on shafting... ... ... 388 
 
 „ on various parts ... ... 278 
 
 Suction lift of pumps ... ... 387 
 
 Superheat data 177 
 
 Superheated steam ... ... ...137-9 
 
 Superheater valve test ... ... 177/^ 
 
 Suspension bulb furnace corrugation 1 1 2 
 
 Switchboard, description of ... 446 
 
 Switches for lamps system 456 
 
 „ (main) 449 
 
 Table of valve setting 219 
 
 Tables „ „ ... 239-48 
 
 Tail's patent water circulator 148^, 148(^ 
 
 Taking "leads" off bottom ends ... 37 
 
 Telemotor, Brown's 353 
 
 „ fluid for 359 
 
 „ instructions for working, 
 
 &c 356 
 
 Temperature difference (refrigeration) 572 
 
 „ of furnaces ... ... 118 
 
 „ of hot-well and con- 
 denser pressures 366 
 
 Temperatures and pressures of NH^ 
 
 and CU2 systems 565 
 
 Temperatures (critical) of NHo and 
 
 CO2 systems 565 
 
 Tempered steel 271 
 
 Tempering steel 276 
 
 Temporary hardness of water ... 427 
 
 Tensile strength of materials ... 270 
 
 Terminal pressure, definition of ... 369 
 
 Test for acid in water ... ... 427 
 
 „ alkali 429 
 
 „ animal or vegetable oils ... 429 
 
 „ break in mains ... ... 467 
 
 „ broken armature coils ... 473 
 
 „ broken wire ... ... 470 
 
 „ carbonic acid ... ... 423 
 
 ,, earth leakage ... ... 471 
 
 „ polarity 473 
 
 „ short circuit between mag- 
 net and coils ... 469 
 
 Test for short circuit between arma- 
 ture coils ... ... ... 469 
 
 Test for short circuit between arma- 
 ture coils and drum ... ... 469 
 
 Test for short circut in brush holders 470 
 
 ,, ,, „ magnet coils 468 
 
 „ „ „ mains ... 473 
 
 ,, „ circuits, &c. ... ... 467 
 
 ,, steel ... ... ... ... 275 
 
 ,, viscosity of oils ... ... 429 
 
 Test with "earth " lamps ... ... 472 
 
 Testing fairness of paddle cranks... 300 
 
 „ „ piston rod ... 327 
 
 „ „ rocking shaft ... 326 
 
 ,, „ shafting ... 320 
 
 ,, joints in ammonia system... 573 
 
 Thermal efficiency ... ... ... 381 
 
 Thermometer ... ... ... 320 
 
 Thickness of butt-straps ... ... 87 
 
 Thomson patent coupling 289 
 
 Thornycroft type carburetter ... 601 
 
 "Thread" of propeller blade ... 516 
 
 Three-wire system ... 454 
 
 Thrust 330 
 
 „ block (part section) 182 
 
 „ „ stress ... ... ... 182 
 
 „ of propeller ... 515 
 
 „ surface of propeller blades... 520 
 
 Tiller (steam \ Brown's ... ... 351 
 
 "T"joints 481 
 
 To adjust stroke of Weir pump ... 312 
 „ valves of Worthington 
 
 pump ... ... 316 
 
 To find cut-off 323 
 
 To fit on a new propeller blade ... 529 
 To mark off eccentric keyseat 
 
 positions... ... ... ... 2(iZa 
 
 To set valve in mid-travel .... ... 323 
 
 To test for wear of crosshead shoes 290c/ 
 To test if cylinder line is at right 
 
 angles to shaft centre line ... 263(^ 
 To test if guides are parallel to 
 
 piston rod line ... ... ... 290c 
 
 To test if guides are parallel to shaft 
 
 centreline ... ... ... 290</ 
 
 Torque ... ... ... ... 374 
 
 Torsion stress ... ... ... 279 
 
 Total heat, definition of 367 
 
 „ of steam... ... ... 373 
 
 Training of connecting rods ... 36 
 
 „ valve gear ... ... 39 
 
 Tramelling pump Imks ... ... 51 
 
 Transformers, function of ... ... 492 
 
 Transmission gearof steering engine 
 
 fo/oce 341 
 
 Travel of crank-pin and piston ... 331 
 
 „ valve, how found... ... 260 
 
 Trial trips ... ... ... ... 65 
 
 " Trick ' type^of slide valve. . . to face 200 
 
Index 
 
 xxvii 
 
 Troubles of oil motors ... .")92-94 
 
 True screw surface (propellers) ... r)18 
 Trunk types of engines ... ... 29!) 
 
 Trunnions of oscillating engines ... 297 
 Tube corrosion ... ... ... 123 
 
 expander ... ... ... 1.50 
 
 plate stays ... ... /oJaceW'^ 
 
 stopper ... ... 1.32 
 
 ., „ Bagguley l\itenl type 
 
 to face 133 
 
 Tubes i condenser) and packing ... 181 
 
 of condenser corroding ... 431 
 
 Tunnel shafting ... ... ... 282 
 
 Turbine propeller to face h^^.) 
 
 Turning engine and gear ... ... 180 
 
 Tweedy system of balanced engines 8 
 Twin screws ... ... ... ... .")33 
 
 Twine-wire system ... ... ... -l.'il 
 
 Twisting moments ... 281 
 
 Two-cycle Diesel engine, general 
 
 description of ... 635 
 
 Two-cycle oil motors ... ... .379 
 
 Types of columns iofaccXQ, 
 
 „ furnace corrugations (di- 
 mensioned) ... ... ... 117 
 
 Types of joints, with dimensions ...78-91 
 „ motors .')99-607 
 
 u 
 
 Unit of heat, definition of ... ... 366 
 
 United States packing 3.")9 
 
 Upkeep of machinery ... ... 67 
 
 Utilisation of power ... ... ... .535 
 
 V 
 
 \ acuum, and air pump valves ... 365 
 
 ,, loss of 294 
 
 I Valve and piston positions 236 
 
 „ and eccentric 263(^r 
 
 ,, and piston positions ... /o face 238 
 „ Andrews-Martin type 205, 207 
 
 ., diagrams ... ... ... 248 
 
 ,, „ linked up 258 
 
 double-beat type ... /o face 186 
 double-ported type ... ... 201 
 
 „ exhaust lap 200 
 
 „ face, to find depth of ... 220 
 
 „ gear, Bremme's 223 
 
 „ „ Brock's 227 
 
 „ ., Bryce-Douglas ... 227 
 
 „ ., details of ... ... 14 
 
 „ „ Hackworth's 226 
 
 „ „ Joy's 225 
 
 „ „ Marshall's 223 
 
 „ , Morton's 225 
 
 \'alve gear training of ... ... 39 
 
 gears, patent types 222 
 
 lead of 200 
 
 minus, exhaust lap ... ... 200 
 
 placed in mid-travel ... ... 323 
 
 setting 47 
 
 ,, of Worthington pump 316 
 
 „ table 219 
 
 „ tables 239-48 
 
 (slide) duties of 199 
 
 „ travel of 199 
 
 spindle eye bush ... ... 186 
 
 spindle-length ... ... 327 
 
 spindles, type of ... ... 13 
 
 steam lap ... ... ... 200 
 
 sticks for lead measurement 215 
 
 throttle to face 186 
 
 travel, how determined ... 260 
 
 trick -type to face 200 
 
 \alves, double-ported type 203 
 
 ,, ofairpump... ... ... 188 
 
 „ of Weir pump ... ... 309 
 
 „ (pet) 295 
 
 „ piston type ... ... ... 206 
 
 ,, piston type with restrained 
 
 rings 208 
 
 Valves (safety) 133 
 
 ,, „ lever type 134 
 
 „ ,, spring type 135 
 
 ., „ „ compression 135 
 
 „ „ to find diameter of 136 
 
 ,, types of ... ... ... 9 
 
 Vapour of petroleum ... ... '411 
 
 Vegetable oils ... ... ... 428 
 
 Velocity of gases ... ... ... 164 
 
 Vertical type donkey boiler to face 167 
 
 Viscosity of oils 428 
 
 „ test for oils 429 
 
 Volt, definition of 490 
 
 Volt-meter ... 448 
 
 Voltage, calculations for 493 
 
 w 
 
 Wake speed ... 519 
 
 Wall plugs 459 
 
 Watch, keeping 68 
 
 Water, chemical composition of ... 410 
 ,, circulation, Tait's patent 
 
 148a, 148/' 
 „ expansion by heat ... .. 886 
 ,, formed by initial condensa- 
 tion 383 
 
 ,, gauge 145 
 
 „ „ Klinger type 153 
 
 „ shortness of, in Jjoiler ... 164 
 
 Water-gauge cock 163 
 
xxvni 
 
 Index 
 
 " Water hammer " ... 
 
 . 139 
 
 Water-tight wall plugs 
 
 . mo 
 
 Water tube boilers ... 
 
 . 170 
 
 ,, „ ,, Habcock type . 
 
 . IT! 
 
 „ „ „ Belville type . 
 
 . 1 73 
 
 „ „ „ \'arro\v type . 
 
 . 1 70 
 
 " Wear-down " gauge 
 
 . f;:i-3 
 
 \\'car-down of pump links ... 
 
 51 
 
 Weight of funnel gases 
 
 . 104 
 
 \\'cir hydrukineter ... 
 
 . 141 
 
 ,, pump stroke, how adjusted . 
 
 . 312 
 
 „ type evaporator 
 
 . 30.3 
 
 „ „ feed heater 
 
 . 303 
 
 „ „ feed pump valves 
 
 . 309 
 
 „ " Uniflu.x" condenser 
 
 . 2mn 
 
 Welding 
 
 . 277 
 
 „ (autogenous process) 
 
 ir)7-62 
 
 " Wet" steam, definition of 
 
 . 376 
 
 Winding of armature 
 
 . 443 
 
 Wing furnace flanging 
 
 . 115 
 
 Wires, jointing of 
 
 . 478 
 
 Wiring 
 
 . 4.30 
 
 ,, single system 
 
 . 451 
 
 „ twin-wire system 
 
 . 451 
 
 " Witness" marks 
 
 . 28 
 
 Wolseley type carburetter ... ... (50(1 
 
 Work done during adiabatic expan- 
 sion 383 
 
 Working data of Diesel engine ... 639 
 ,, of Hair.s CO.j machine, 
 instructions ... ... 553-00 
 
 Working economically ... ... 70 
 
 Workshop practice ... ... ... 1 
 
 Worthington type feed pump ... 314 
 
 „ pump valves, h(jw set 310 
 
 Wrought iron ... ... ... 274 
 
 "Wyper" shaft 42 
 
 Yarrow-Schlick-Tweedy system ... 8 
 ,, type water tube boiler ... 170 
 
 Zeuner valve diagrams 248 
 
 Zinc block and stud ... ... 144 
 
 „ plate in box ... 144 
 
 „ plates 143 
 
INDEX TO APPENDIX. 
 
 Action of steam in turbine ... ... 654 
 
 Advantage of impulse blading ... G67 
 
 Ahead dummy 654 
 
 Air pump (Weir " Dual" type) ... 685 
 Arrangement of combined turbines 
 
 and reciprocating engines ... 655 
 
 Arrangement of geared-dovvn turbines 659 
 
 of turbines ... ... 647 
 
 Benefits of combination arrangement 655 
 
 Blade tip clearance ... 652 
 
 Blading list 651 
 
 Boiler data I vertical type) ... ... 701 
 
 „ efficiency ... 691 
 
 Brown-Curtis type dovetail impulse 
 
 blading ... ... ... ... 665 
 
 Brown-Curtis type dovetail reaction 
 
 blading ..'. 664 
 
 Calorific (heat) value of coal ... 692 
 
 Channel steamer turbine blades ... 651 
 Circumferences and areas of circles, 
 
 table of 710-15 
 
 Circumferential shell riveting ... 703 
 
 ,, „ steam stress... 704 
 
 ,, ,, seams ... 702 
 
 Clearance of blades 652 
 
 Coal and water consumption ... 693 
 Combined impulse and reaction 
 
 blading ... ... ... ... 666 
 
 Combined reciprocating engines and 
 
 turbines ... ... ... ... 655 
 
 Compensating ring for manhole ... 704 
 
 Composition and heat value of fuel 692 
 
 Consumption and slip ... ... 697 
 
 Control valve box of impulse turbine 663 
 Curtis turbines — 
 
 Balances, pistons, and equalising 
 
 pipes 680 
 
 Best bucket speed 669 
 
 Blades and caulking groove ... 679 
 
 jl Compound and combined impulse 673 
 
 Construction ... ... ... 673 
 
 Expansion of steam 677 
 
 Impulse turbine 1 668 
 
 Pressure stages 671 
 
 I'AGKS 
 
 Principle of impulse turbine ... 669 
 Provision for decreased velocity 
 
 of steam ... ... ... ... 676 
 
 Relation of fixed and moving 
 
 buckets in ... ... ... 676 
 
 Some advantages of B.T.H. ... 675 
 
 Suitability of the turbine for low 
 
 steam pressures... ... ... 678 
 
 Unsuitability of reciprocating 
 
 engine for low pressures . . . 678 
 
 Velocity stages 670 
 
 Data of main engines 689 
 
 De- Laval turbine 642 
 
 Description of geared-down turbines 
 
 of SS. " Vespasian" 659 
 
 Description of propelling machinery 
 
 of SS. "King Orry" ... ..'. 660 
 Description of propelling machinery 
 
 O.SS."Reina Victoria Eugenia" 656 
 
 Donkey boiler (vertical type) ... 701 
 
 Door (manhole) ... 704 
 
 Dummies ... ... ... ... 650 
 
 Dummy (ahead type) ... ... 654 
 
 ,, clearance 652 
 
 Economy of feed water heating ... 691 
 
 Engine and boiler data ... ... 694 
 
 „ data 689 
 
 ,, knocking ... 688 
 
 Equivalent evaporation 693 
 
 Facial rings ... ... ... ... 650 
 
 Flow of steam in turbine ... ... 644 
 
 „ „ through blades ... 646 
 
 Geared-down turbines ... ... 658 
 
 „ „ SS. "Vespasian" 659 
 
 Height of turbine blades 652 
 
 H. P. turbine data 652 
 
 Hyperbolic logarithms 716 
 
XXX 
 
 Index to Appendix 
 
 I' AGES 
 
 " King Orry,'' macliiiieiy of ... 660 
 
 Knocking in engines . . ... 688 
 
 Length of turbine blades 651 
 
 Logarithms, hyperbolic ... ... 716 
 
 Longitudinal seams ... ... 701 
 
 Low pressure turbine ... ... 656 
 
 L. P. turbine data 653 
 
 Machinery of Q.SS. " Reina Victoria 
 
 Eugenia" 656 
 
 Machinery of SS. '^ King Orry " ... 660 
 
 „ of SS. "Vespasian^' ... 659 
 
 Manhole compensation ring ... 70-4 
 
 Manoeuvring valves ... ... ... 681 
 
 Marine turbines ... ... ... 642 
 
 Nozzle box 667 
 
 Number of blade rows ... ... 651 
 
 of turbines fitted 647 
 
 " Orry, SS. King," turbines of ... 660 
 
 Parallel flow 644 
 
 Parsons' turbine ... ... ... 644 
 
 type combined impulse and 
 
 '680 
 645 
 695 
 653 
 
 680 
 
 682 
 691 
 667 
 696 
 642 
 695 
 
 to face 
 
 reaction turbines 
 Path traced by steam 
 Piston clearances 
 Plan of turbine room 
 Port turbines and geai 
 
 T.S.S. "Tuscania" 
 Practical operation of 
 
 machinery 
 Pressure on bearing surfaces 
 Pressures 
 
 „ revolutions, power, speed 
 Principle of turbine ... 
 Pump clearances 
 
 wheels, 
 . to face 
 turbine 
 
 " Reina Victoria Eugenia," SS. 
 Results of trials, " Reina X'icloria 
 
 Eugenia" 
 Results of trials, " Vespasian " 
 Ring (compensating) 
 Riveting of vertical donkey boiler 
 Rotor drum dimensions 
 Rows of blades, number of . . . 
 
 Standard arrangement of turbines 
 ,, specification for cargo- 
 
 l',\CES 
 
 656 
 
 658 
 660 
 704 
 701 
 652 
 651 
 
 641 
 
 steamer engmes 
 Steam, action of 
 
 „ flow 
 
 „ properties of saturated 
 
 „ speed data ... 
 
 „ turbines 
 
 „ volumes 
 Steamer (twin screw) data ... 
 Stop valve data 
 Stresses on seams ... 
 Superheated steam ... 
 
 697-7U0 
 644 
 645 
 05-9 
 691 
 642 
 649 
 689 
 691 
 704 
 693 
 
 Table of circumferences and areas 
 of circles ... ... ... 710-15 
 
 Thickness of boiler shell ... ... 701 
 
 Three-wire system of lighting ... 687 
 
 To obtain " equivalent evaporation ' 691 
 
 Turbine arrangements ... ... 646 
 
 „ combination arrangements 655 
 
 (De-Laval) 642 
 
 ,, (geared down ... ... 658 
 
 „ (Parsons) 644 
 
 Twin screw steamer data ... ... 689 
 
 \'alve settings ... ... ... 696 
 
 Vertical donkey boiler data ... 701 
 
 "V^espasian" 659 
 
 \'olume of steam ... ... ... 649 
 
 Weir " Dual"' air pumps ... ... 685 
 
 Wire (three) system ... ... ... 687 
 
DESIGN DRAWINGS AND CALCULATIONS. 
 
 FIRST CLASS. 
 
 Sheets i and 2 show proportions of Nuts, Bolts, and Screws. 
 
 Boilers — 
 
 1. Single-Ended Combustion Chamber 
 
 2. Double-Ended Combust ionChamber. 
 
 3. Furnace and Fire Bars. 
 
 4. Water Gauge Column. 
 
 5. Vertical Donkey Boiler. 
 
 6. Fire Bars and Bearers for Vertical 
 
 Boiler. 
 
 Valves— 
 
 7. Dead Weight Safety Valve. 
 
 8. Spring-Loaded Safety Valve. 
 
 9. Boiler Stop Valve. 
 
 10. Engine Room Stop Valve. 
 
 11. Feed Check \'alve. 
 
 12. Bilge Suction Valve Chest. 
 \2.\. Bilge Injection \'alve. 
 
 13. Side Discharge Valve. 
 
 14. Cylinder Relief \'alve. 
 
 15. Slide Valve and Spindle. 
 
 16. Inside Steam Piston Valve. 
 
 17. Double Ported Slide Valve. 
 
 Pumps — 
 
 18. Air Pump. 
 
 19. Feed Pump Complete. 
 
 l9.-\. Feed Relief Air Vessel and Pump 
 Valves. 
 
 Pistons — 
 
 20. H.P. Piston and Rod. 
 
 21. L.P. Piston and Rod. 
 
 22. L.P. Cylinder Cover. 
 
 23. Donkey Pump Cylinder and Valve. 
 
 Eccentric, etc. — 
 
 24. Eccentric and Rod Complete. 
 
 25. Quadrant Bars, etc. 
 
 26. Reversing Bell Crank. 
 
 Shafting— 
 
 27. Crank Shafting. 
 
 28. Thrust Shaft and Shoe. 
 
 29. Thrust Block. 
 
 30. Stern Tube and Shaft. 
 
 31. Propeller Boss. 
 
 Various — 
 
 32. Bottom Blow-Off Cock. 
 
 33. Three-Way Change Cock. 
 
 34. Main Bearing. 
 
 34A. Tunnel Bearing Block. 
 
 .35. Steam Pipe Expansion Joint. 
 
 36. Pump Levers. 
 
 37. Connecting Rod. 
 
 38. Pump Crosshead and Links. 
 
DESIGN DRAWINGS AND CALCULATIONS. 
 
 SECOND CLASS. 
 
 1. 
 
 Main Bearing Bolt, complete. 
 
 21. 
 
 ^_ 
 
 Bottom End Bolt, complete. 
 
 22. 
 
 3. 
 
 Tapered Coupling Bolt, complete. 
 
 23. 
 
 4. 
 
 Distance Piece for Bottom End 
 
 24. 
 
 
 Brass. 
 
 2rj. 
 
 ."). 
 
 Main Bearing " Brass." 
 
 26. 
 
 fi. 
 
 Bottom End Brass. 
 
 27. 
 
 7. 
 
 Steam Stop Valve and Seat. 
 
 28. 
 
 8. 
 
 Safety Valve, Seat, and Spindle. 
 
 29. 
 
 9. 
 
 Winch Slide Valve. 
 
 30. 
 
 10. 
 
 Slide Valve Spindle. 
 
 31. 
 
 11. 
 
 Eccentric Pulley. 
 
 32. 
 
 12. 
 
 Eccenric Strap. 
 
 33. 
 
 13. 
 
 Crank Shaft and Webs. 
 
 34. 
 
 14. 
 
 Thrust Shaft. 
 
 3."). 
 
 15. 
 
 Tail End Shaft. 
 
 36. 
 
 10. 
 
 Piston Rod and Crosshead. 
 
 37 
 
 17. 
 
 Guide Shoe. 
 
 
 18. 
 
 Gland and Stuffing Box. 
 
 38. 
 
 1!). 
 
 Winch Cylinder Piston. 
 
 39 
 
 20. 
 
 Air Pump Valve. 
 
 -10. 
 
 Feed Pump Plunger. 
 
 Tee Piece for Steam Pipe. 
 
 Link and Lever for Indicator Gear. 
 
 Bo.\ Spanner. 
 
 Spanner. 
 
 Boiler Manhole. 
 
 Fire Bar. 
 
 Fire Bar Bearer. 
 
 Stay Tube and Common Tube. 
 
 Tube Stopper. 
 
 Combustion Chamber (lirder. 
 
 Double Butt Strap Joint. 
 
 Main Stay. 
 
 Combustion Chamber stay. 
 
 Double Riveted Lap Joint. 
 
 Crank Pin Disc for Winch. 
 
 Check \'alve Chest Cover and 
 
 Spindle. 
 Hand Wheel for Sleam Stop Valve. 
 Air \"essels. 
 Water Gauge Column Bracket. 
 
 NOTE. -It is of the utmost importance that each drawing be fully dimensioned 
 before being handed in to the Examiner. 
 
u 
 
 VERBAL" NOTES AND SKETCHES 
 
 SKCTION I. 
 
 WORKSHOP PRACTICE. 
 
 The reciprocating engine as at present constructed and perfected 
 by the numerous auxiliary specialities now in general use un- 
 doubtedly represents vast improvement on the engine of ten or 
 fifteen years ago, and part of this improvement is certainly due to 
 the superior class and make of the machine tools now in general 
 use, and to the ever increasing use of cast steel and mild steel, which 
 materials serve to combine strength with lightness of parts. A brief 
 description of the various types of reciprocating engines found in 
 ordinary marine practice will now be given. 
 
 Types of Engines. 
 
 Paddle Engines. — For steamers of the paddle type the general 
 practice is to fit an engine of the diagonal pattern (the oscillating 
 type being now nearly obsolete) arranged either single, compound, 
 triple, or quadruple expansion, and generally with two cranks, 
 although three cranks are occasionally arranged for. The Sketches 
 Nos. I, 2, 3, 4 illustrate the various cylinder and crank arrange- 
 ments referred to. Piston valves are often fitted to the H.P. and I.P, 
 of triple expansion paddle engines, and flat double-ported slide valves 
 to the L.P. cylinders. 
 
 Screw Engines. — In screw steamers the engines are of the inverted 
 type, being cither compound, triple, or quadruple expansion, but in 
 Naval practice the turbine has now completely superseded the 
 reciprocating engine for all classes of vessels, and the success of this 
 type of engine, where high power and speeds are required, is beyond 
 dispute. Many cross-channel steamers and deep sea passenger 
 steamers are also fitted with turbine machinery of the Parsons design, 
 I 
 
Verbal " Notes and Sketches 
 
 No. I. — Compound Type 
 Paddle Engines. 
 
 n n 
 
 a 
 
 1 
 
 LP. 
 
 3 E 
 
 
 Lb 
 
 IP 
 
 HP 
 
 3 E 
 
 y 
 
 No. 2. — Triple Expansion Type 
 Paddle Engines. 
 
 ] E 
 
 3 E 
 
 izr 
 
 HP. 
 
 No. 3. — Triple Expansion Type 
 
 Paddle Engines 
 
 (Two L.P. Cylinders). 
 
 No. 4. — Quadruple Type 
 Paddle Engines. 
 
Workshop Practice 3 
 
 and the combination arrangement, in which reciprocating engines 
 and turbines are arranged to work conjointly in the same engine- 
 room, is rapidly coming forward into more general practice, (For 
 further information on this subject see author's " Marine Steam 
 Turbine.") 
 
 The Sketches numbered 6, 7, 8, 9 illustrate the various cylinder 
 
 No. 5.— Diagonal Type Paddle Engine. 
 
 and crank arrangements mentioned above, and the flow of the steam 
 through each is as follows : — 
 
 Compound, — Steam flows from boilers through H.P. then L,P. to 
 condenser. 
 
 Triple. — Steam flows from boilers through H.P., LP., and L,P. 
 to condenser. 
 
4 "Verbal" Notes and Sketches 
 
 Triple (with 2 L.P. cylinders and four cranks).— Steam flows from 
 the boilers through H.P., I. P., and then divides into^wo steam pipes, 
 one led to each L.P. cylinder. 
 
 Quadruple.— Steam flows from the boilers through H.P., ist I.P., 
 2nd I. P., and L.P. to condenser. 
 
 In many designs of large power engines the steam is conveyed 
 from one cylinder to another by means of large pipes, known as 
 "receiver pipes," but in ordinary engines of moderate power the 
 steam flows from one receiver to another through large ports cast 
 in the cylinders themselves. In Sketch No. 9 the cylinders are 
 shown arranged, from forward aft, as H.P., 1st LP., L.P., and 2nd I. P., 
 which allows of better balancing of the working parts, the crank 
 angles being a few degrees less or more than 90° to each other. 
 
 LP. 
 
 HP 
 
 No. 6.— Triple Expansion Engine (Three Cylinders). 
 
 Cranks at 120°. 
 
 Balanced Engines. — The constantly varying pressures on the crank- 
 pin result in corresponding variations in the twisting stresses exerted 
 by the engine, the range of torsional stresses varying with the type of 
 engine, number and position of cylinders, and the steam distribution 
 in each cylinder. 
 
 These unequal stresses continued for long periods often result in 
 the development of flaws on the shaft, and may finally lead to total 
 breakage. 
 
 It is therefore desirable to so balance up the moving parts that an 
 even turning movement on the shafting may be obtained, and vibra- 
 tion damped down to a minimum. 
 
Workshop Practice 
 
 ALP 
 
 FLP 
 
 +-M 
 
 M.P 
 
 H 
 
 FLP 
 
 No. 7. — Crank and Cylinder Arrangement, Four-Cylinder 
 Triple Engine. 
 
" Verbal ' Notes and Sketches 
 
 ALP 
 
 MP 
 
 ^ 1 
 
 H P 
 
 FL.P 
 
 No. 8.— Crank and Cylinder Arrangement (Yarrow, Schlick, & 
 Tweedy Balanced System). 
 
Workshop Practice ' 7 
 
 Regarding this subject Professor \V. E. Dalby, M.A., B.Sc, in a 
 paper read at the forty-second meeting of the Institution of Naval 
 Architects, says : — 
 
 "The only way of balancing a three-crank marine engine of the usual 
 type is by the addition of balance weights, or bob weights, to the moving 
 parts. In this case, therefore, balancing necessarily means the actual addition 
 of considerable masses of material to the machinery which have no other 
 duty but that of producing forces equal and opposite to the unbalanced 
 forces caused by the motion of the moving parts which are concerned in 
 doing the proper work of the engine. It is well known that Messrs Yarrow, 
 
 1 c 
 
 L.R 
 
 
 
 
 ■ 
 
 
 Itr i.R 
 
 H 
 
 R 
 
 
 
 -^ 
 
 L 
 
 
 J 
 
 L 
 
 
 (6) ® 
 
 No. 9.— Quadruple Expansion Type Engine (Large Power;. 
 
 1, H.P. piston valve. 5, Second LP. slide valve. 
 
 2, H.P. cylinder. 6, Second I. P. cylinder. 
 
 3, First I. P. piston valve. 7, L.P. D.P. slide valve. 
 
 4, First I. P. cylinder. 8, L.P. cylinder. 
 
 E, E, E, Exhaust pipes. 
 
 Schlick, & Tweedy made a departure from existing practice when they began 
 to build engines in which the moving parts concerned in doing the proper 
 work of the engine were so arranged that they were in balance amongst 
 themselves. In engines of this kind no part of the machinery merely turns 
 round or reciprocates for the sake of the forces its motion causes on the 
 frame. No such arrangement is possible, however, unless the engine has, 
 at least, four cranks. This condition and the progressive increase in the 
 power of marine engines have together determined the gradual introduction 
 
8 " Verbal " Notes and Sketches 
 
 during the last ten years of the four-crank engine into tlic Navy and the 
 Mercantile Marine. Yet that the possibilities of balancing the four crank 
 engine have not been generally recognised is shown by the fact that many 
 engines of that ty[)e have been and are still being built with their cranks at 
 right angles, even when absence of vibration is imperative. Four cranks 
 at right angles is just the one particular arrangement of a four-crank engine 
 which makes it impossil)le to effect balance without the addition of balance 
 weights. A change in the crank angles, however, and a small change in the 
 mass of the moving parts is all that is necessary to obtain an engine in which 
 the moving parts are balanced amongst themselves ; to change, in fact, a 
 four-crank unbalanced engine into a four-crank balanced engine of the 
 Yarrow, Schlick, & Tweedy type. These changes cannot be made in any 
 arbitrary manner. The masses, crank angles, and centres of cylinders must 
 be mutually adjusted to satisfy certain conditions." 
 
 The necessary calculations required in accurately determining the 
 above arran<Tement of cranks, balance weights, &c., are worked out 
 from the indicator diagrams, crank effort diagrams, and the carefully 
 calculated weights of the various moving parts, and involve a 
 considerable amount of labour. 
 
 Balance weights are sometimes fitted to the crank webs of the 
 H.P. and I. P. engines, which are lighter, while the crank-pins of 
 the two L.P. or heavy engines are bored out hollow, so that the 
 weights of the parts may be correctly adjusted. 
 
 In the Yarrow-Schlick-Tweedy system of engine balancing, the 
 calculations are usually so carefully determined that the addition of 
 balance weights is not always required, the necessary balance being 
 found by the relative crank angles and crank sequence, or order of 
 rotation. 
 
 In an ordinary three-cylinder triple-expansion engine the sequence 
 is either H.P.. I. P., and L.P., or L.P., I. P., and H.P., but when four 
 cylinders are fitted (two L.P,) the sequence is usually as shown in the 
 sketches on page 5. 
 
 Observe that the H.P. and LP. cranks are directly opposite, also 
 that the F.L.P. and A. L.P. are opposite each other, but at right angles 
 to the other two. 
 
 It will be thus seen that the crank angles and crank sequence are 
 quite different when the Yarrow-Schlick-Tweedy system is adopted 
 as in the example illustrated on page 6, the H.P. and I. P. cylinders 
 being inside, and the two L.P. placed one forward and one aft. 
 Observe that the heavy engines are placed at the ends to balance 
 up the weight of the moving parts. 
 
 The crank sequence is then (i) H.P., (2) F.L.P., (3) LP., and 
 (4) A. L.P. This arrangement has the effect of reducing the vibration, 
 and also allows of quick and easy handling of the engines. 
 
 It should be understood that the relative crank angles vary with 
 the size of engine, power, and weight of moving parts. 
 
Workshop Practice 9 
 
 Valves. — The cylinder valves are either piston valves, single-ported 
 valves, or double-ported valves, a common arrangement being as 
 follows . — 
 
 II. P. cylinder 
 LP. cylinder 
 L.P. cylinder 
 
 Piston valve (inside steam). 
 
 Piston valve, single-ported or 
 double-ported slide valve. 
 
 Double-ported slide valve. 
 
 Certain builders fit piston valves to all the cylinders of large engines, 
 and in many cases patent valves of the " Trick " double-ported type 
 (see page 200) or of the " Andrews-Martin " type (see page 205) are 
 fitted, the latter giving particularly satisfactory results owing to the 
 good balance obtained. 
 
 Pistons. — Pistons are now being constructed in many cases of cast 
 steel, and are fitted with patent rings and springs of approved make, 
 
 * No. 10.— Cast-Steel Piston (with Dimensions). 
 
 The dotted lines show the LP. and L.P. pistons equal in 
 depth to the L.P. piston. 
 
 NOTE.— The radius of each piston is given. 
 
 which, together with the improved design and construction of piston 
 rod metallic packings at present on the market, have assisted to 
 
 * Reprinted by perniissioii fioin "Marine Engine Design." Prof. Edward M. Bragg. 
 D. Van Nostrand Co., New York, 1910. 
 
 « li 
 
10 
 
 Verbal " Notes and Sketches 
 
 bring up the efficiency of the marine engine to its present high 
 standard. The introduction of the metallic packings referred to 
 (notably that known as the U.S. packing) (see page 360) has met with 
 
 * No. II.— Cast-Iron Piston. 
 
 NOTE. — Depth of packing ring g-Z^ t. 
 
 the hearty approval of the marine engineering profession as a body, 
 and the form of combination packing supplied by engineering firms 
 in general, if, perhaps, not so effective as the patent types, is yet a 
 great advance on the asbestos and similar packings formerly used 
 for piston rods. 
 
 * Reprinted by permission from "Marine Engine Design." Prof. Edward M. Hragg. 
 D. Van Nostrand Co., New York, 1910. 
 
Workshop Practice 
 
 II 
 
 No. 12.— Patent Metallic Packing. 
 
 (The Combination Metallic Packing Co., Ltd.) 
 
 N, White metal bearing rings. U, White metal bearing blocks 
 
 L, Springs. C, Gun-metal case. 
 
 E, Extension piece for secondary T, Springholder. 
 
 packing. H, Floatmg rings. 
 
12 
 
 " Verbal " Notes and Sketches 
 
 Connecting Rods. — The two types of connecting rod in common 
 use are known as the single and double top end patterns. The single 
 top end rod is more compact, but the double top end is simpler to 
 manufacture, and is also much easier to overhaul when of large size. 
 In the double type the crosshead is secured to the piston rod by 
 means of a taper and nut, and in the single type the crosshead pin is 
 
 * No. 13.— Double Top End Type Connecting Rod. 
 
 t/= Piston rod diameter. 
 
 D = dxi.2. 
 L — Length of crank -pin. 
 
 ^ No. 14.— Single Top End Type Connecting Rod. 
 
 shrunk into the connecting rod jaws, and sometimes further secured 
 by small locking pins as shown. This pattern of rod costs more to 
 produce than the other type, and is also more difficult to take adrift 
 when overhauling. 
 
 The bearing parts of the double top end rod are sometimes made; 
 of cast steel with white metal bearing surfaces, but often brass is em- 
 
 * Kepriiited by permission from "Marine Engine Design." 
 D. Van Nostrand Co., New York, 1910. 
 
 Prof. Edward M. 
 
 Bragg. 
 
Workshop Practice 
 
 13 
 
 SQUARE. 
 
 ROUND. 
 
 No. 15.— Types of Valve Spindles. 
 
 In the square section type shown with the taper and cotter 
 the rod may be drawn out by the top, but with the round 
 section (sohd) the rod must be drawn out from below. 
 
 ployed for the top ends, and cast steel and white metal for the bottom 
 ends only. In the cheaper class of engines, cast-iron bushes lined 
 with white metal are employed, and this is now the general practice 
 for merchant steamers. 
 
H 
 
 " Verbal " Notes and Sketches 
 
 Valve Gear. — Valve gear is generally uf the Stephenson link 
 motion type with double bar quadrant ; valve spindles are either 
 solid or made in two parts which are connected by a cotter, the upper 
 part fitting by a taper into the lower part. That part of the spindle 
 passing through the guide bracket is sometimes of round section and 
 sometimes of square section. The rod diameter is reduced at the 
 position of the valve, and the washers or cotter under the valve rest 
 on a tapered portion of the spindle. Above the valve a washer is 
 fitted with double nuts (one lock nut), and to further prevent slackening 
 back of these nuts a large split pin or a cotter is run through 
 the rod. 
 
 JSL 
 
 
 ^- 
 
 I r 
 
 CS 
 
 frp 
 
 * No. i6. — Link Block Pin and Liners. 
 NOTE.— Thickness b-dx^. 
 
 The bushes in the valve spindle end are usually of brass, and of' 
 large bearing surface to reduce wear to a minimum. The saddle or 
 quadrant blocks are of steel fitted with brass liners which bear on the 
 quadrant bars. 
 
 *No. 17. — Eccentric Pulley. 
 The pulley is divided into two portions 
 at the shaft centre and these are bolted 
 together as shown, the bolts being ar- 
 ranged with taper heads. 
 
 * No. 18.— Eccentric Strap. 
 
 The strap is recessed out to receivi 
 the pulley and is lined with whit( 
 metal, dovetailed in place as shown. 
 
 * Reprinted by permission from "Marine Engine Design." Prof. Edward M. Pragg. 
 D, Van Nostrand Co., New York, 1910. 
 
Workshop Practice 15 
 
 Eccentrics, &c.— Eccentric rods are generally made of steel with 
 brass bushes at the top ends, and the eccentric straps are generally 
 constructed of cast steel lined with white metal as bearing surfaces ; 
 the pulleys themselves are of cast iron or cast steel. 
 
 ASTERil 
 CUIOE 
 
 imr 
 
 c 
 c 
 c 
 c 
 
 
 3 
 
 3 
 
 (••-BOLTS, 
 
 /\ )( )( ]( K^ 
 
 ASTERM 
 GUIDE- 
 
 PLAN. 
 
 ;.'. . s , .'..,'. :' . • J t; 
 
 No. 19.— "Single" Type Guide showing Ahead and 
 Astern Surfaces. 
 
 The plan shows the bolted-on knees, which constitute the 
 astern guides, the bearing surface of which is less than for the 
 ahead guides (about 80 per cent). 
 
i6 "Verbal" Notes and Sketches 
 
 Main Bearings. — Main bearing bushes are generally of cast iron 
 lined with white metal, and the bottom half is often made round to 
 facilitate withdrawal. Suitable gutters or oil ways are cut in the 
 white metal surfaces to allow of efficient lubrication, and often the 
 sides are cut away clear altogether, leaving only the top and bottom 
 surfaces effective. 
 
 NOTE.— From the foregoing it will be obvious that the term "brasses" is 
 now hardly correct, brass for bearings being generally superseded by cast steel 
 lined with white metal. 
 
 Crank-shafts. — The crank-shafts of mild steel are usually of the 
 built pattern with the pins and shaft lengths shrunk into the webs 
 and secured by dowel pins. Sometimes that part of the shaft fitting 
 into the webs is about h inch greater in diameter. 
 
 Columns. — Columns vary in design, but- the usual types fitted are 
 that known as the " box " pattern, and that of the Y type, which is 
 fitted for engines of large power. In some engines of the "open- 
 fronted " type round steel columns are fitted at the front, and the 
 back columns are then arranged with astern guides which overlap the 
 guide shoes, and are held in place by large bolts. 
 
 NOTE. — This arrangement of columns was often fitted in the engines of 
 Government torpedo destroyers before the advent of the marine steam turbine. 
 
 Description of Construction. 
 
 In the construction of the reciprocating engine we will now 
 proceed to deal with the various operations which are performed 
 from the time the castings, forgings, &c., are delivered at the works 
 until the engine is completed in the fitting department and ready 
 for erection in the ship. 
 
 Soleplate. — This is generally of box pattern and is made up of 
 several parts, usually three in number, bolted together, one piece 
 forming the forward part, one the centre (Sketch No 21), and one the 
 after part. In large engines, however, the soleplate sometimes con- 
 sists of four parts, which are, of course, bolted together. After delivery 
 of the castings the first operation is that of gauging to ascertain if 
 the thickness of metal as required by drawing has been maintained. 
 
 This having been found correct, the soleplate is now marked off 
 preparatory to machining the base for columns connecting flanges, 
 and gaps for main bearing bushes. In good practice the bottom of 
 the soleplate is machined, as this ensures good fitting chocks in 
 the ship, and also facilitates the fitting of same. The soleplate is 
 now taken to slotting machine, and has the base for columns and 
 
^ 
 
 ^the bolt. "" ' ° ' ""'" " 
 
 The main bearing bolts being now fitted in all parts of the sole- 
 
 vli^vP"?^^'^. ^^ permission from "Marine Engine Design." Prof. Edward M. Brag?. 
 Van Nostrand Co., New York, igio. 
 
mnr 
 
 H i( If 
 
 B, Double type colu 
 
 C, Y type column, 
 
 A, Double type column. 
 
 D, Singlejtype column with open front. 
 
 * Reprinted by permission from " Marii 
 
 F, Plan of single type column showing 
 ahead and astern guides with shoe in 
 position. 
 
 E. Round column for 
 open front. 
 
 iteam Design." Trof. Edward M. Bragg. U 
 
 No. ao.^Types of Columns. 
 
 1 N.i&lrand Cu.. New Vork, 191 
 
 in;a.cpasei6. 
 
Workshop Practice 
 
 17 
 
 COnnectinc^ flanges machined : this operation is carried out on the 
 other parts which form the complete soleplate, and the main bearing 
 <Taps are also machined while the soleplate is in this stage. The 
 soleplate being now finished machining, the holes for main bearing 
 bolts, holding-down bolts, and connecting flanges are bored, also the 
 holes for bolting columns to soleplates. The main bearing bolts 
 are now fitted ; these bolts are, in ordinary merchant work, a large 
 double-ended stud having a nut at the bottom end which draws the 
 bolt tight up on a collar at the top end (Sketch No. 22). The bolt 
 
 * No. 21.— Part of Soleplate showing Base for Columns. 
 
 s usually reduced to the diameter at the bottom of the thread in 
 he middle, and is a fit in the parallel parts, where it passes through 
 he hole in the soleplate at either end. A feather on stop pin is fitted 
 nder the collar, and this prevents the bolt from turning round when 
 he bolt is being screwed up or slackened. The bottom nut is locked 
 ither by a large split pin through the thimble point at the end of 
 ie bolt or by a set pin through the nut, and pointed into the screw 
 fthe bolt. 
 
 The main bearing bolts being now fitted in all parts of the sole- 
 Reprinted by permission from '' Marine Engine Design." Prof. Edward M. Bragg. 
 . Van Nostrand Co., New York, 1910. 
 
and gaps tor main bearmg Dusnes. in gooa practice tne ootiom oi 
 the soleplate is machined, as this ensures good fitting chocks in 
 the ship, and also facilitates the fitting of same. The soleplate is 
 now taken to slotting machine, and has the base for columns and 
 
Workshop Practice 
 
 ^1 
 
 connecting flanges machined : this operation is carried out on the 
 other parts which form the complete soleplate, and the main bearing 
 gaps are also machined while the soleplate is in this stage. The 
 soleplate being now finished machining, the holes for main bearing 
 bolts, holding-down bolts, and connecting flanges are bored, also the 
 holes for bolting columns to soleplates. The main bearing bolts 
 are now fitted ; these bolts are, in ordinary merchant work, a large 
 double-ended stud having a nut at the bottom end which draws the 
 bolt tight up on a collar at the top end (Sketch No. 22). The bolt 
 
 * No. 21.— Part of Soleplate showing Base for Columns. 
 
 is usually reduced to the diameter at the bottom of the thread in 
 the middle, and is a fit in the parallel parts, where it passes through 
 the hole in the soleplate at either end. A feather on stop pin is fitted 
 under the collar, and this prevents the bolt from turning round when 
 the bolt is being screwed up or slackened. The bottom nut is locked 
 either by a large split pin through the thimble point at the end of 
 the bolt or by a set pin through the nut, and pointed into the screw 
 Df the bolt. 
 
 The main bearing bolts being now fitted in all parts of the sole- 
 
 * Reprinted by permission from " Marine Engine Design." Prof. Edward M. Bragg. 
 D. Van Nostrand Co., New York, 1910. 
 
iS 
 
 "Verbal" Notes and Sketches 
 
 No. 22.— Main Bearing Bolt. 
 I, Set pin. 2, Feather. 3, Set pin. 4, Split pin. 
 
Workshop Practice 
 
 19 
 
 plate, the next operation is that of scttiiii; up or Hning ofif the soleplate. 
 This operation is usually performed on the blocks on which the engine 
 is to be erected. The foundation for the engine usually consists of 
 long logs laid fore and aft, two on each side of soleplate. The sole- 
 plate is laid on the logs and levelled up, and the intervening space is 
 filled up with wooden wedges (Sketch No. 24), the three parts of the 
 soleplate being laid on the logs and as near in line as possible by the 
 eye : the different sections are next brought into line. Through the 
 two gaps of the centre portion a straight-edge is laid resting upon 
 
 • 
 
 n 
 
 
 1 
 1 
 
 1 
 1 
 
 
 
 
 
 No. 23.— Main Bearing Complete. 
 
 •ooden centres fitted into the gaps, about 3 inches from the top (Sketch 
 »o. 25), The straight-edge is kept bearing hard on the side of the 
 ap ; the end of the straight-edge extends into the inside gap of the 
 )rward portion of soleplate ; this part of soleplate is now moved 
 deways (by means of screw jacks) until side of gap bears on straight- 
 dge. The same operation is performed on aft section, and the edge of 
 le straight-edge is tested by means of feelers until all three parts are 
 , ose up to straight-edge. The straight-edge is now put through bottom 
 if gap and all three parts brought up to line in a similar manner, 
 
20 
 
 "Verbal" Notes and Sketches 
 
 It will be readily understood that after this operation it is necessary 
 to go over the preceding work, so as to ensure that the sides of gaps 
 are still in line. The soleplate is also levelled fore and aft and 
 
 t 
 
 )l II 
 
 © 
 
 
 ^ 
 
 1( 11 
 
 r 
 
 
 11 11 
 
 © 
 
 
 ^ 
 
 © 
 
 1^- 
 
 I 
 
 1 
 
 
 o<=> J^ 
 
 
 Xi 
 
 o 
 
 ho 
 
 6 
 2 
 
 athwart-ships by applying the straight-edge on the base for columns. 
 The soleplate being now set up, the holes in adjoining or connecting 
 flanges are widened and bolts fitted. The space between soleplate 
 and logs is also filled up with wooden wedges, care being exercised 
 
Workshop Practice 
 
 21 
 
 while drivinc^ up same that tlie level of soleplate is not altered. The 
 main bearini,^ bushes are now fitted into the gaps, the main bearing 
 covers put on and screwed up. The next operation is that of marking 
 
 25 —Lining off the Soleplate. 
 
 LINERS 
 
 I, 
 
 No. 26. — Boring out of Main Bearing Bushes. 
 
 Proof"' lines. 2, Boring out line — diameter of shaft. 
 
 off the main bearing bushes: there are several different methods of 
 I : doing this work. In some works the bushes are not filled with white 
 I metal until after being fitted, and the cast iron or steel is bored out 
 
22 
 
 "Verbal Notes and Sketches 
 
 to the diameter of the shaft pkis the reh'efs, and the bush is then 
 filled with white metal and reset up on the machine to the previous 
 machined parts, and bored out to the diameter of the shaft. The 
 general practice, however, is to have the white metal in bush when 
 fitted, and with all bushes in place a fine piano wire is stretched 
 through all the bushes, being carried on supports at each end. This 
 wire is set up athwart ships to the centre of the main bearing gap, 
 which is projected on to the end of the bush at the forward and aft 
 
 No. 27.— Main Bearing Bush. 
 
 L, Liners. D, Shaft diameter. 
 
 E, Tapped hole for hfting gear. O, Oil service. 
 
 end. The height is taken from drawing and is measured from base 
 for columns. The wire now being set to these points four lines or 
 chords are drawn on each side of each bush with a pair of Jennys 
 (Sketch No, 26). The wire is now withdrawn and in each bush a 
 wooden centre is fitted faced with tin, and the centre is picked up 
 from these four lines or chords and the boring out diameter is drawn 
 in on each side of the bush, also a short proof line at four points. 
 This proof line is usually about f inch to i inch larger in diameter 
 than the boring out size, and is used to test the boring bar when the 
 
Workshop Practice 23 
 
 bush is about bored out to the final size. The bushes are now bored 
 out, and reliefs or gutters cut. The bushes are now put back in 
 place in the soleplatc, and are now ready for the bedding down of the 
 crank-shaft. 
 
 Crank-shafts and Columns. 
 
 The majority of engineering firms buy in the crank-shafts 
 required for the various engines which they are constructing. This 
 part of the engine is usually delivered in a finished condition, as it 
 is found the steel works which specialise in this work can turn out 
 the finished article much cheaper than it can be constructed in a 
 general engineering concern. The type of crank-shaft now manu- 
 factured is that of the built-up type, with the crank pins and shafts 
 
 SCREWED 
 PIN 
 
 r 
 
 -c:.-.. 
 
 
 
 ^ 
 
 No. 28.— Balanced Crank. 
 
 shrunk into the webs, and is usually in three parts having two 
 couplings. This arrangement admits of interchangeability and 
 necessitates one part only for spare. The method of constructing 
 the shaft is as follows : — The webs are machined to shape and the 
 holes bored and turned out for the pins and shafts. The web is laid 
 flat down on a table, over a pit which is of sufficient depth to receive 
 the shaft, when the web is turned upside down to receive the pin. 
 The web is then heated up by means of a bunsen burner sufficiently 
 to allow a gauge, 7.^^ inch larger than the diameter of the part which 
 is to be shrunk, to pass through, and this expansion having taken 
 place the pin or shaft is lowered into the web and the whole part 
 cooled out. The web is next turned upside down and the same 
 operation takes place ; that is, the pin being shrunk in first and 
 
24 
 
 " Verbal " Notes and Sketches 
 
 then the shaft. The other half of the crank is similarly assembled, 
 and then the part consisting of the shaft and pin is suspended above 
 the other part, and the pin is shrunk into the web, thus forming the 
 complete crank. During the operation of joining the two webs by 
 means of the pin care is taken to ensure that the centre lines through 
 the webs are exactly in line. The crank pins and shafts, besides 
 being shrunk into web, arc also prevented from turning by round 
 dowel pins being fitted half into the shaft and half into the web 
 (Sketch No. 28). 
 
 After the complete shaft is built the coupling holes are bored, 
 and the three parts brought together, the cranks being set to the 
 sequence required. The coupling bolt holes are widened, and bolts 
 
 C 
 
 L 
 
 All II A 
 
 J 
 
 <D 
 
 QKr- 
 
 zHS) 
 
 No. 29.— Taking "Leads" off Top Main Bearing Bush. 
 
 1, Lead wire (18 B.W.G.)- 
 
 2, Gutters or reliefs. 
 
 3, Oil hole. 
 
 4, Dowel pins to hold liners in place. 
 
 fitted. The shaft is now put into lathe, and the body of the shaft 
 is turned over, also the flanges of the couplings : it is next centred 
 for the turning of the crank-pins, each pin having a separate centre. 
 In large engines and in fast running engines the crank-shafts are 
 usually balanced so as to ensure steady running. This is done 
 theoretically to suit the power of the engines in relation to the 
 power developed in the various cylinders. To attain this balance, 
 balance weights are fitted on the webs of the crank (Sketch No. 28). 
 The crank-shaft is now ready for bedding down in the main bearing 
 bushes. This operation is done by red leading the part which runs 
 in the bearings, the shaft is lowered and turned round, and then 
 lifted, and the parts which show bearings are eased with a scraper, 
 and shaft again tried until it is bearing throughout all the bearings 
 
Workshop Practice 25 
 
 During the operation of bedding down the shaft, care is taken to 
 ensure that it is thoroughly level when resting in the bearings. 
 After this the top bushes are " leaded," which means that they are 
 fitted down to rest on the liners and give a clearance between the 
 shaft and the bush, usually -020 inch — this is to ensure passage for 
 oil, and also to allow for expansion of shaft when it acquires what 
 is generally termed a running heat. The clearance of the bush is 
 found by means of lead wire, hence the name " leading." The wire is 
 usually 16 or 18 B.W.G., and is put across the shaft, one part in the 
 middle of the bearings and one at either end (Sketch No. 29). The 
 main bearing cover is put on, and nuts screwed up and hammered. 
 The cover is then slackened back, and bush taken out, and the lead 
 wire is gauged by micrometer. When the leads show an even 
 thickness of the required amount at all parts then the bush is 
 finished " leading." The eccentric pulleys for operating the valve gear 
 are fitted on the crank-shaft, usually after the shaft has been bedded 
 in bearings. The pulleys are bolted on shaft, and set to the required 
 position as shown on drawing, for the marking off of keyseats in 
 the following manner. The H.P. crank-shaft is turned with crank 
 up, and the lines for setting the pulleys are put on the shaft in the 
 following manner. 
 
 Cutting of Eccentric Keyseats. 
 
 A diagram is prepared in the drawing office, showing the position 
 of pulleys with the crank down. This diagram (see page 233) is 
 mounted on a board, having a half circle, equal to the diameter of the 
 shaft cut out. The vertical line is set as near the crown of the shaft 
 as possible, and a spirit level is applied to the top of the board, and 
 the board brought level. The vertical line is now transferred to the 
 shaft, and by applying a box square, the line is produced along the 
 shaft, a little longer than the distance which will be occupied by 
 the ahead and astern pulleys. From the diagram the distance from 
 the centre to centre of keyseat in ahead pulley is taken b)' means of 
 dividers, and this distance is marked off on shaft, applying one end 
 of the dividers to the line along the top of the shaft. An arc is 
 drawn at two points, and a straight-edge set to these marks and a 
 line drawn. This line represents the centre of keyseat for the 
 ahead pulley, and the same operation is carried out for the astern. 
 The pulleys are now put on shaft and set with the keyseats exactly 
 central to the mark, and the distance from centre of crank to centre 
 of pulleys is arrived at by means of a length stick marked off from 
 the drawing. In the case of an H.P. engine having an inside lead 
 piston valve, then the ahead pulley will be 90° minus lap and lead 
 behind the crank. An outside lead valve will have the pulleys set as 
 follows (Sketch No. 44) : — Ahead pulley 90° plus lap and lead in 
 advance of the crank. The keyseats for the pulleys are generally cut 
 out by hand, and feathers fitted into same. The pulleys are also 
 
26 
 
 " Verbal " Notes and Sketches 
 
 secured by having bolts passing through both pulleys or having set 
 pins thimble pointed into the shaft (Sketch No. 30). 
 
 No. 30.— Method of Locking Eccentric Pulleys. 
 
 Erecting of Columns. 
 
 In the tramp type of engine the back or ahead columns are usually 
 part of the condenser, but in larger engines the condenser is usually 
 separate, being supported on brackets at the back of the engines, and 
 all the columns are fastened direct to the soleplate. 
 
 [ 
 
 t 
 
 ^ 
 
 J 
 
 No. 31.— Length Stick for Lining off Columns. 
 
 In the first place, we will deal with the erection of a set of engines 
 having the condenser and back columns in one. In this case the 
 bottom of the condenser has flanged faces which adjoin similar faces 
 
 1 
 
Workshop Practice 
 
 27 
 
 on the soleplate ; these faces are bolted toc^ethcr. In lining off the 
 columns the first operation is to fit centres into the i^ap for the main 
 bearing bush ; along those centres a straight-edge is laid, one edge of 
 which is set to the line representing the centre of crank-shaft. ]'Vom 
 the top of tlie columns plumb lines are dropped down. Parallel to 
 the straight-edge and about { inch clear of it, a length rod is laid, 
 having marked on it lines corresponding to the centres of the three 
 cranks (Sketch No. 31). The plumb line is now set so that it just 
 grazes the straight-edge, and is directly in line with the line repre- 
 senting the centre of the crank. This being so, the column opposite 
 the one from which the line is suspended is brought into line by 
 
 ^ 
 
 TELESCOPE 
 GAUGE. 
 
 V 
 
 No. 32.— Gauging between Columns. 
 
 means of a square applied from a centre line on the face of the 
 column, and by means of a telescope gauge set to half the distance 
 between columns, as shown on drawing. This operation is carried 
 out on all columns, and a plumb rule is applied to the face of each 
 individual column to ensure it being plumb. If it is not plumb, then 
 the column is taken down, and the base on which it rests is either 
 scraped or filed if the amount is not great, but should it be too much 
 for hand labour, then the column itself is machined to suit. The 
 condenser and back columns being one, it is necessary to set this part 
 first, after which the three front columns are brought into position. 
 The distance between the column faces is gauged by means of a 
 telescope gauge (Sketch No. 32). A straight-edge is also passed along 
 
28 
 
 "Verbal" Notes and Sketches 
 
 ^ 
 
 CZHl fCZD 
 
 STRAIGHT EUGL 
 
 CENTRE LINE 
 
 STRAIGHT - EDGE. 
 
 LJ 
 
 LZJ 
 
 l^ 
 
 No. 33.— Lining off Columns. 
 
 the face of the columns, taking two columns together (Sketch No. 33), 
 and the edge of the straight-edge is tested by means of feelers to 
 ensure all columns being dead in line to each other. It is also 
 advisable to try the straight-edge along the top of the columns to 
 test the height of each, and to ensure the condenser being set up to 
 the height of the front columns. In large engines it is found to be 
 more accurate to work with fine piano wire instead of the plumb 
 line, but in general work the process is similar to that described, but 
 every firm has a system of their own, the result being the same. 
 The columns now being set, the holes in the feet are marked off from 
 the holes on the soleplate flange, witness marks, i.e., at two or four 
 points on each flange a small part is chipped and scraped up and 
 a line put across, either with a drawpoint or with a fine chisel (Sketch 
 No. 34). These points serve to ensure the columns being put 
 back to the position the)' were in after the\- are bored, although it 
 
 No. 34.— Witness Marks. 
 
Workshop Practice 
 
 29 
 
 is advisable to retest the setting before widening holes. All being 
 right, the holes on the feet of columns and on the flanges connecting 
 the condenser to soleplate are widened and bolts fitted, and the 
 engine is now ready to receive the cylinders. 
 
 Cylinders and Valve Chests. 
 
 The cylinders in a triple expansion engine are termed the 
 High Pressure, Intermediate, and Low Pressure, the usual form 
 
 No. 35.— Piston Valve Casing Liner (Brass) (Half in Section). 
 
 Showing ports and diagonally cut bars. 
 
 of contraction being H.P., I. P. (or M.P.), and L.P. The valve on 
 the H.P. cylinder is usually of the piston type, and in the valve casing 
 liners are fitted (Sketches Nos. 35 and 36). The reason for fitting 
 
 No. 36— Piston Valve Casing Ports and Bars. 
 
 The bars are cast as shown to provide a continuous bearing 
 surface for the rings. 
 
 liners instead of boring out the cylinder to the size of the valve is to 
 allow of renewal and also to simplify the cutting of the steam ports. 
 The liners are usually of hard-grained cast iron, and being separate 
 
!l 
 
 ;o 
 
 *' Verbal " Notes and Sketches 
 
 and of small size, it is possible to ensure a close-grained and homogene- 
 ous casting. The liners are turned up on the outside and the inside 
 bored out to I inch smaller than the finished diameter. The ports are 
 
 No. 37.— Cylinder and Valve Chest (Naval Type). 
 
 The cylinder is fitted with a liner and the valve casing with 
 a balance cylinder. 
 
 cut out, and after the cylinder is bored out, the liners are fitted into place. 
 The cylinder is put back into machine and the liners are bored out to 
 the finished diameter, thus ensuring a true job in relation to the bore 
 
Workshop Practice 31 
 
 of the cylinder proper. In ijcncral \vf)rk liners arc also fitted in the 
 cylinder, this also, as in the case of the valve liners, giving a hard and 
 close-grained casting, and also facilitates renewal. The liners (Sketch 
 No. 38) are secured to the cylinder in various ways, but usually 
 have a flange on the bottom which is bolted to the cylinder and 
 bearing strips at the top and bottom. On the top of the liner a 
 recess is formed into which asbestos packing or similar jointing 
 material is put, and on the top of the packing a piece of steel wire of 
 
 ■ 
 
 m-^ 
 
 §-^ 
 
 k 
 
 I 
 
 No. 38.— Cylinder Liner (Half in Section). 
 
 I, 2, Fitting strips. 
 3, Screwed pins. 
 
 the required diameter is put in, having the end scarfed. Above this 
 a flat steel ring is fitted on to studs in the flange of the liner. The 
 studs are square necked, and nuts and split pins are fitted, thus ensur- 
 ing that no part will slacken back. The space between the liner and 
 the cylinder body is termed a jacket, and to this space a steam con- 
 nection is sometimes made from the stop valve, and also a drain valve 
 on the bottom. These connections are fitted, to be used when heating 
 up the engines, and to ensure an equal expansion of the cylinder body 
 taking place while the engines are being heated up. The cylinder 
 
32 
 
 " Verbal " Notes and Sketches 
 
 liner and valve liners being fitted, and other parts of the cylinder 
 machined, the cylinder is now ready for water testing. This opera- 
 
 No. 39.— Method of securing No. 40,— Method of keeping Joint 
 Cylinder Liners. of Liner Tight. 
 
 E, Packing space. i, Copper ring. 2, Cylinder liner. 
 
 3, Cylinder wall. 
 
 tion usually takes place on a set of cylinders which are connected 
 together at the valve casings, when all three cylinders are at the 
 same stage of construction. The LP. cylinder and L.P. cylinder are 
 
 * No. 41. — " Box " Type of Cylinder Cover. 
 
 * Reprinted by permission from "Marine Engine Design." Prof. Edward M. 
 D. Van Nostrand Co., New York, 1910. 
 
Workshop Practice 
 
 33 
 
 sometimes fitted with a cylinder Hner, but this is only in high-class 
 work. The I. P. cylinder having a slide valve is fitted with a valve 
 face. This face is fastened to the face of the cylinder by brass cheese- 
 headed pins (Sketch No. 45), and is of hard close-grained cast iron, 
 
 No. 42.— Bottom of Cylinder ("Box" Pattern). 
 
 *No. 43.— Cylinder Bottom with Liner in Position. 
 
 44.— Cylinder Cover and Liner. 
 
 Notice how the cover is shaped exactly to fit the piston and 
 so reduce the clearance losses. 
 
 and, in some cases, of special metal adapted to resist wear. The 
 intermediate face is usually in one, and the low pressure face in two, 
 one part forming the top half to the centre of the exhaust port, and 
 the other half from same point to the bottom. After the cylinders 
 have been erected on top of the engine columns, and plumbed to that 
 
 * Repiinted by permission from "Marine Engine Design." 
 D. Van Nostrand Co., New York, 1910. 
 
 Prof. Edward M. Bragg. 
 
34 
 
 Verbal " Notes and Sketches 
 
 position, the cylinders are taken down and the valve faces machined 
 over, so as to ensure the face of the valve being parallel to the bore 
 of the cylinder. The cylinders being now all the same distance 
 forward in the course of construction, they are brought together and 
 the HP. cylinder jointed to the I. P. cylinder at the casing or receiver, 
 
 No. 45.— Method of securing Cylinder False Face. 
 
 and the L.P. cylinder is jointed in a similar manner to the other side 
 of the I. P. cylinder. This joint is usually made of mastic cement or 
 red lead putty, and in some cases a groove is cut down each side and 
 along the bottom of the joint flange ; this serves to retain the jointing 
 
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 No. 46 —Method of securing False Face. 
 
 composition and to ensure a good joint. The cylinders are now 
 water tested to the required pressure, usually twice the working steam 
 pressure, and are now ready for erecting on the top of the columns. 
 In the stuffing boxes and in the valve spindle stuffing boxes, centres 
 are fitted from which plumb lines are suspended, and if the crank- 
 
T 
 
 OI*. 
 
 col 
 
 col 
 wh 
 
 -^ — - 'icdu^, ana tne holes tor bolting the cylinders to" "the 
 umns are marked off. The cylinders are taken down and also the 
 umns, which are bored on the top flanges, and any machining 
 icli IS required to bring the cylinders plumb is done 
 The columns are re-erected, cylinders put up and set to witness 
 
SLOT (3" BY li" 
 
 Method of Lining up Cylinders, &c. 
 
 No. 48— Alignment of Cylinders and Shafting. 
 
 means of the small bar as required until it is brouglit dead central. Repeat this at 
 
 To either set up the cylinders or to test if the cylinders and shaft centre lines 
 arc at right angles to each other (engine dismantled) proceed as follows ;— 
 
 1. Take a piece of board with a slot cut as shown (about 3 inches by ^V i"ch will 
 do), and secure this by two studs to the cylinder across the centre to bring the hole 
 in wood bridge fair. 
 
 2. Fix another slotted board in the centre of the crank-pit fore and aft with the 
 hole dead centred as shown. 
 
 3. Tie a bolt or small bar of any kind (a file will do) to the end of a line 
 pass-.d down through the cylinder bridge slot, and secure the other end of this line 
 10 the crank-pit bridge slot : the bolts or bars to which the line is attached laid 
 crosswise on the slot will allow of adjir-rnent at top or bottom. 
 
 4. Now caliper the line at the top from the cylinder bore, and adjust it by 
 
 the bottom of the line, adjusting at the crank-pit bridge slot. 
 
 5. Next caliper round the line from stuffing box bore and adjust cylinder to suit if 
 necessary ; also test distance betwcjen line and crank web at top and bottom centre 
 as shown. 
 
 6. With crank on top mark crank-pin where line touches, then turn crank to 
 bottom and again mark pin; now test, by calipering, if both maiks are the same 
 distance from the web. 
 
 7. To test the alignment of the guide caliper between the line and guides at 
 top and bottom as shown in the end view. 
 
 8. To test if the guides are in line fore and aft, use a surface gauge and adjust it 
 to touch the line when laid up against the guide forward; now try it aft, and if the 
 point again touches the line, the guides are in line, fore and aft, if not, they are out 
 of line and recjuire to be canted round to square up. 
 
 ITo fatt f<^c 35. 
 
Workshop Practice 
 
 35 
 
 shaft is in place centres are fitted between the webs, with one edge 
 central to the centre of the shaft, and with a line on each centre equal 
 distance from each web. The cylinders arc moved until the three 
 lines hanging from the piston rod stuffing boxes are exactly in line 
 with the marks on the shaft centre sticks and also in line with the 
 centre of the shaft. The bores of the cylinders are also tested with a 
 plumb rule, and it may be necessary to line up the feet of the cylinders 
 to bring them plumb. If this be the case then it will entail machining 
 or filing the head of the columns which show high, but if care has 
 been exercised in setting up the columns it will only be a small 
 
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 JOINT. 
 
 No. 47.— Method of securing False Face. 
 
 imount that will be required to be eased from the high point. The 
 |ines suspended from the valve spindle stuffing boxes are tested from 
 straight-edge, bearing on the column face, and this will show if the 
 Cylinder centres are parallel to the column faces, but it is mostly in 
 engines having the cylinders separate that this operation is required, 
 ""he cylinders being set, witness marks as before explained are chipped 
 "on the column heads, and the holes for bolting the cylinders to the 
 columns are marked off. The cylinders are taken down and also the 
 columns, which are bored on the top flanges, and any machining 
 which is required to bring the cylinders plumb is done. 
 
 The columns are re-erected, cylinders put up and set to witness 
 
SLOT (3" BY 
 WOOD <^l 
 
 ^roj ^■;; r 
 
 *v. 
 
 D\V 
 
 water tested to the required pressure, usually twice the working sieam 
 pressure, and are now ready for erecting on the top of the columns. 
 In the stuffing boxes and in the valve spindle stuffing boxes, centres 
 are fitted from which plumb lines are suspended, and if the crank- 
 
Workshop Practice 
 
 35 
 
 shaft is in place centres are fitted between the webs, with one edge 
 central to the centre of the shaft, and with a line on each centre equal 
 distance from each web. The cylinders are moved until the three 
 lines hanging from the piston rod stuffing boxes are exactly in line 
 with the marks on the shaft centre sticks and also in line with the 
 centre of the shaft. The bores of the cylinders are also tested with a 
 plumb rule, and it may be necessary to line up the feet of the cylinders 
 to bring them plumb. If this be the case then it will entail machining 
 or filing the head of the columns which show high, but if care has 
 been exercised in setting up the columns it will only be a small 
 
 JOINT 
 
 JOINT 
 
 No. 47.— Method of securing False Face. 
 
 amount that will be required to be eased from the high point. The 
 lines suspended from the valve spindle stuffing boxes are tested from 
 a straight-edge, bearing on the column face, and this will show if the 
 cylinder centres are parallel to the column faces, but it is mostly in 
 engines having the cylinders separate that this operation is required. 
 The cylinders being set, witness marks as before explained are chipped 
 on the column heads, and the holes for bolting the cylinders to the 
 columns are marked off. The cylinders are taken down and also the 
 columns, which are bored on the top flanges, and any machining 
 which is required to bring the cylinders plumb is done. 
 
 The columns are re-erected, cylinders put up and set to witness 
 
J 
 
 6 "Verbal" Notes and Sketches 
 
 marks, and centres retested. All being right, the holes in column 
 heads are widened, bolts fitted. There are usually four fitted bolts 
 in each column head, the rest being an easy fit. It is again prefer- 
 able as before explained to use a fine piano wire instead of the 
 plumb line, and also to extend the centring line up to the top of 
 the cylinder, into which a centre is fitted, and the line set truly to 
 this, and also to the bore of the stuffing box. As before explained 
 every firm has its own method of carrying out these various opera- 
 tions, but the foregoing is a general description of the method 
 employed in setting up the cylinders for a modern tramp steamer's 
 engines. In many shops the cylinder feet are bedded down on the 
 column heads, thus ensuring perfect work, but with the accurate 
 machine work and the use of length sticks and length gauges, it is 
 possible to get all the different parts of the machinery to come 
 together with the minimum of hand work. 
 
 Training Connecting Rods and Fitting Running Gear. 
 
 The engines are now ready for the fitting of the gear, and the 
 first operation is that of putting in the piston rods and pistons. The 
 pistons are usually tried into cylinder and allowed to rest on 
 the bottom of same. A length rod is applied from the centre of 
 the crank-shaft up to the top of the piston and to the top of the 
 cylinder. These points are marked off and the piston rods cut to 
 length, allowance being made for the clearance required at each end 
 of the stroke. The same operation is also carried out on the valve 
 spindles. After piston rods are cut to length they are fitted into the 
 pistons, that is the tapered part on which the piston rests is fitted 
 up to a bearing. This operation being finished and the piston rod 
 having been fitted into the crosshead, if the type of connecting rod is 
 that of the double top end, the piston and rod are lifted and 
 lowered into place in the cylinder. If the connecting rod is that 
 of the single top end, the crosshead bearings being on the piston 
 rod, then the piston rod requires to be lifted up through the stuffing 
 box and through the piston, the piston rod not being passed on to 
 the sling. The crosshead is put on to piston rod and set parallel 
 to the column faces. Gauges are then lifted from the face of cross- 
 head to column face and guide shoes machined and fitted. The 
 connecting rods are now put into place, and trained. This operation 
 is usually performed in the following manner : — The top end liners 
 are taken out and the nuts screwed up, thus binding the top end. 
 The piston should be lined up also so as to ensure its remaining 
 central. The whole part, piston, piston rod, and connecting rod are 
 now lifted up until the connecting rod butt is up clear of the crank- 
 pin, and the distance between flange of bottom end bush and web is 
 o-auged at the four points to ascertain if the rod is hanging fair. At 
 the same time a plumb rule is applied to the side of piston rod or 
 crosshead and the rod brought into a true position. It is necessary 
 
Workshop Practice 
 
 Z7 
 
 while this operation is being- carried out to be sure that the piston 
 rod is exactly central in the stuffing box, and to ensure this 
 temporary glands of wood or brass should be fitted. If the four 
 points at the butt of the rods do not coincide, then it is necessary 
 to ease the top end bush in such a manner that will bring butt of 
 rod exactly fair. This being so, the bottom end of rod is now bound 
 on, the crank-pin, crank being on bottom centre, and the piston rod 
 and crosshead are lifted up until clear of top end bushes. If the 
 rod is true, then the crosshead will lower into place with equal 
 clearance on each side of the top end brasses ; if not, then the bottom 
 end bush will require to be eased so as to bring rod central. In 
 binding bottom end of rod on to crank-pin care should be taken 
 
 rr 
 
 LA 
 
 T 
 
 (2) O 
 
 No. 49.— Taking "Leads" off Bottom End Bearing Bush. 
 
 1, Lead wire. 3, White metal. 
 
 2, Oil gutters or "reliefs." 4, Dowel pins to hold liners in position. 
 
 to have equal clearance on each side of bottom end bush and web. 
 The crosshead is now bedded into top end bushes and top bushes 
 leaded. After this operation the top end is again bound and the 
 bottom end bush bedded on crank-pin. The crank is now turned 
 to top centre and the crank-pin bearings leaded. The same operation 
 takes place on the three connecting rods. 
 
 In carrying out this work on connecting rods of the single top end 
 type, a good deal of extra work is entailed, as this type of rod is not 
 so easy to overhaul. The crank-pin bush is bound on the crank-pin 
 in a similar manner as before, and the piston, rod, and crosshead are 
 lifted up ; care is taken to ensure the connecting rod being central 
 between the columns. The piston rod is lowered until the top bush 
 is just clear of rod, and by applying a straight-edge to the inside cheek 
 
^8 " Verbal " Notes and Sketches 
 
 of the connecting rod, it can be seen if the connecting rod is fair to 
 the piston rod ; if this is not so, then the bottom end bush will require 
 to be lined up and a corresponding amount either taken off the sole 
 of the top bottom end bush, or the bore of the bush scraped out until 
 the rod is brought fair with the piston rod. The top end bush is 
 bound in a similar manner as before described, and the crank-pin 
 bush bedded upon the crank-pin. In some works it is usual to test 
 the rods by swinging them, that is, after the top end bush has been 
 bedded and leaded, the piston rod and connecting rod are lifted up, 
 and the rod is swung from side to side so as to ensure that it falls 
 back with its own weight and is in no way bound. 
 
 The crank-pin bushes are " leaded " in a similar manner as the top 
 end, the crank is turned to the top centre, and the bottom half of 
 the bush is lowered, lead wire, usually -ly or -16 B.W.G., is put in 
 (Sketch No. 49), crossing the circumference of the bush in three places. 
 The bush is pulled up against the crank-pin and nuts put on the 
 bearing bolts. Usually the amount of liners required are given on 
 the connecting rod drawing, and generally consist of one cast-iron 
 liner from i^ to 2 inches thick, one i-inch brass liner, and three ^V-inch 
 
 T 
 
 No. 50.— Lead Wire as taken from Bottom End Bearings. 
 
 I, Lead wire -02 thick at crown of bearing. 
 2, Lead wire heavier at sides. 
 
 brass liners, and in some cases tin liners are fitted, but it is more 
 general to fit all brass liners and to have the same amount of liners 
 in all crank-pin bearings. The liners are in place while the operation 
 of leading the bearings is being carried out, and the nuts on the bolts 
 are hammered up, a mark being put on thimble point of bolt and on 
 nut, care being taken to ensure both nuts being brought to an equal 
 degree of tightness. The nuts are slackened back, and the bush 
 lowered and lead examined. If they are not parallel and of the 
 required thickness throughout, usually -020 inch, then the white metal 
 in the bush is scraped out and the operation repeated until the lead 
 wire is of the required thickness. It is usual practice to ease the 
 sides of the bush, so as to give a slightly heavier lead at this part, 
 usually from -003 to -004 inch heavier than the lead taken from the 
 crown of the bush. This result allows for expansion of the crank-pin 
 when heated to a running heat, and also allows of a passage of oil 
 (Sketch No. 50). It is not advisable to increase this clearance at the 
 sides to too great an extent, as it takes away from the surface of 
 the bush. The nuts on the bottom end and top end bearings arc 
 usually fitted with a lock-pin for binding the nuts, and split pins arc 
 also fitted to prevent the nuts slackening back. Oil tubes are led 
 
Workshop Practice 
 
 39 
 
 down the connecting rods to the crank-pin bush, with an oil cup on 
 the fork of the rod. This oil cup is supplied with oil from a siphon 
 box fastened to the side of the cylinders. The top end is supplied 
 with oil in a similar manner. 
 
 The guide shoes in general practice are of cast iron faced with 
 white metal, but in some designs only the ahead guide shoe is faced 
 with white metal, the astern shoe being of cast iron throughout. 
 
 Reliefs are cut across the shoes (Sketch A, No. 20) and oil is 
 supplied to the top of the column guide faces from the oil box which 
 supplies the connecting rod bearings. 
 
 Training Valve Gear. 
 
 The valve gear is trained in a similar manner to the connecting 
 rods, this is to ensure the gear being in line. The first operation is 
 that of setting the valve spindle guide bracket. This bracket is 
 
 No. 51.— Valve Gear Complete (Naval Type). 
 
40 
 
 "Verbal" Notes and Sketches 
 
 fastened to the bottom of the cyUnder, and has a brass guide bush 
 either of square or round bore, through which the valve spindle 
 passes. The spindle is put up into place and the gland put in, and 
 the spindle supported inside the valve casing. The bracket is put in 
 position, and bound on to the valve spindle. The spindle is set 
 parallel to the valve face, or to the bore of the valve liner if it is an 
 H.P., and a plumb rule tied on the body of the spindle. This being 
 found plumb, the holes for bolting the bracket to cylinder are marked 
 off and bracket bored. Usually the holes are widened and fitted bolts 
 put in. The bore of the gland is tested by means of feelers to ensure 
 
 * No. 52.— Guide Bracket and Valve Spindle. 
 
 the spindle being central to the gland. The bracket being fixed, the 
 quadrant is put into place and the eccentric rods and drag links. 
 
 All gear being assembled, the ahead eccentric rod is first dealt 
 with. The bearings on the top end of the rod are bound to the pins 
 of the quadrant, and the end of the quadrant lifted until the butt of 
 the rod is clear of the studs on the eccentric strap. It is now lowered 
 and the holes are tested to see that they are fair to the studs. This 
 being so, the astern eccentric rod is dealt with in a similar manner. 
 The eccentric straps are now bound on the pulleys by taking out the 
 liners and screwing up the bolts, and the quadrant is lifted up out of 
 the bearings at the top of the rod. If this is fair then the rod is true, 
 but if it is found that the bush is not in line with the sides of the 
 quadrant, then the butt of the rod is lined up until it is fair, and the 
 amount of the lining is machined or filed off according to the amount. 
 
 *Reprinlcd by permission from "Marine Engine Dasign." Prof. Edward M. Bragg. 
 D Van Nostrand Co. , N«w York, 1910. 
 
Workshop Practice 
 
 41 
 
 Both eccentric rods now being fair, the drag h'nks are dealt with. 
 These are first disconnected, and the distance from the quadrant pins 
 
 No. 53.— Eccentrics and Rods. 
 
 The rod in direct line with the valve spindle is usually the 
 "ahead" and the one out of line the "astern." 
 
 to the pins on the wyper shaft is tested, so as to ensure the quadrant 
 being square and parallel to the wyper shaft. The drag links are now 
 
42 
 
 "Verbal" Notes and Sketches 
 
 bound on the pins of the lever, and tlic end which couples to the 
 quadrant pins tested for bcincj fair. If not true, then the base of the 
 brass is filed or machined until the link is brought in line. The same 
 method is carried out with the other end, the quadrant end of the 
 link being bound and the end which couples to the wyper shaft lever 
 being brought fair. The eccentric straps are bedded on the pulleys 
 and are usually left -025 inch easy for same. In most of engines 
 the eccentric straps are usually of steel lined with white metal, and 
 are of broad surface. The wyper shaft (Sketch No. 54) is supported 
 on brackets bolted to the columns and the bearings are usually cast 
 iron, but in the better class of engine brass bushes are fitted. On the 
 wyper shaft are four levers, three connecting to each of the valve 
 gears, and the other one being connected to the reversing engines. 
 
 The three levers connecting the valve gear are fitted with 
 adjustable bearing pins, to which the drag links are coupled. The 
 use of these pins is for the purpose of what is usually termed " linking 
 
 REVERSING ENGINE 
 LINK PIN. 
 
 No. 54.— Wyper (or Reversing) Shaft. 
 
 up," or altering the cut-off of the valve (Sketch No. 55). If the valve 
 is arranged to cut-off at three-quarters of the stroke, then when the 
 pins are full out, and the eccentric rod exactly in line with the valve 
 spindle, this point of cut-off will be got. By screwing in the block in 
 the wyper shaft lever the cut-off of the valve will be altered, as the 
 eccentric rod is not in line with the valve spindle, and so the travel of 
 the valve will be decreased. The link lever is usually graded to 
 represent the different positions of cut-off as shown in Sketch No. 55. 
 The levers on the wyper shaft are keyed on, and have also a lock pin 
 which passes through the lever and into the body of the shaft, thus 
 ensuring that no movement of the lever will take place. The lever 
 to which is connected the reversing engine is usually fixed in a 
 similar manner, and if the reversing gear is that of makers who 
 specialise in this gear, then two levers may be fitted connected by two 
 links to the piston rod of the reversing engine. The position of 
 the main reversing lever is determined from the drawing, and is so 
 
Workshop Practice 
 
 43 
 
 fixed to give the movement of the valve i^ear from ahead to astern 
 position. If the reversing gear is that of the all-round type, it is 
 general to have the link on the top centre of the reversing wheel when 
 gear is full ahead, that is with drag links and levers in a level position 
 (Sketch No. 55). In some ships, tell-tale gear is fitted : this is a 
 
 MID- POSITION. DRAG LINK 
 
 PIN. 
 
 No. 55.— Reversing Gear Bell Crank. 
 
 Showing expansion link slot and block for linking up. The 
 adjustment of the drag link pin block in the slot (by means of 
 the screw and nut) controls the cut-off as indicated by the 
 cut-off grades marked. The block as shown is " full out " giving 
 a cut-off of -70 stroke or 70 per cent. ; if the block is placed 
 in "full in" position the cut-off is then -40 or 40 per cent. 
 The linking up referred to is only possible when the gear is in 
 ahead position, as when set for "astern" the slot is nearly 
 vertical and the linking up effect then becomes inoperative. 
 
 small quadrant fixed on the wyper shaft, and from this gear is led to 
 an index plate on the front of the forward column, and indicates 
 which way the valve gear has been moved, and in some cases this 
 gear is also connected to the bridge, thus showing to the officer in 
 charge if his order transmitted by the engine-room telegraph has been 
 properly carried out (Sketch No. 57). 
 
44 
 
 "Verbal" Notes and Sketches 
 
 Cylinder Clearances and Setting of Valves. 
 
 There are sevenil methods of takinj^ cylinder clearances, but the 
 method now described is most generally employed. In taking the 
 top clearance the crank is turned on top centre, and in this position 
 strips of clay or putty are laid on the body of the piston and also 
 on the top of the piston rod, and on the piston rod nut. The cover 
 is now put on, and a few nuts screwed up to ensure that the cover 
 is close down on the joint. The cover is now taken off, and the 
 thickness of the clay at the various points measured, thus giving the 
 
 verse Shaft Levor rf- 
 
 / |.-Vq1v 
 
 vc Stem 
 
 j/p.ods 
 
 *No. 56.— Valve Gear in "Astern" Position. 
 
 Notice that the expansion slot is in a vertical position and 
 therefore practically non-operative as regards linking up. 
 
 clearance between the cover and piston at top of stroke. While crank 
 is in this position a mark is chipped on the guide shoe column face 
 plate, and a fine chisel cut put across both parts (Sketch No. 58), 
 thus showing when crank is on top centre. This position has been 
 found previously either by plumbing the crank web, or by using a 
 trammel from the side of the column. In finding the centre or top 
 of stroke in this manner the method used is to turn crank up until it 
 is nearly at top, and in this position a trammel is applied from a 
 
 * Reprinted by permission from "Marine Engine Design." 
 D. Van Nostrand Co., New York, 19 to. 
 
 Prof. Edward M. Bragg. 
 
Workshop Practice 
 
 45 
 
 point on the column, and an arc drawn on the top of the web. At 
 the same time a mark is drawn across the edges of guide shoe and 
 column face. The crank is now turned over the centre, until the 
 mark on the guide shoe and column face is again in line. In this 
 position the crank is again marked with the trammel from the same 
 point as before, and by bisecting the two marks a point is found, 
 and upon turning the crank back until the trammel fits between 
 this mark and the point on the column, the crank is on the top centre. 
 
 W=ff 
 
 POINTER 
 
 No. 57.— "Tell-Tale" Gear. 
 
 D, Engine running ahead. C, Engine running astern. 
 
 B, Gear in mid-position. 
 
 A mark is now put across the guide shoe and column, and the 
 amount of clearance which has been ascertained by means of the 
 clay or putty is marked above this mark, thus showing the amount 
 of clearance originally allowed for. The bottom clearance is found 
 by turning the crank to the bottom centre, and either plumbing the 
 crank or acting as before described ; the mark is also put on edge 
 of guide shoe and column face. The top end is now disconnected. 
 
46 
 
 "Verbal" Notes and Sketches 
 
 and the piston and piston rod lifted up, the bottom top end bush is 
 taken out, and the piston and rod lowered until it rests upon the 
 bottom of the cylinder. Another mark is now put on the column 
 in line with the mark previously put on the guide shoe, and the 
 difference between the two marks represents the clearance when 
 the crank is on bottom centre. In engines of good design small 
 brass plates arc fitted on which these marks are installed, as it has 
 
 TOP CENTRE 
 
 BOT. CENTRE 
 
 No. 58.— Method of Testing Piston Clearance. 
 
 B, Piston on top centre. 1 Top 
 
 C, Piston touching- cover. / clearance. 
 
 D, Piston on bottom centre. ^ Bottom 
 
 E, Piston touching cylinder bottom, /clearance. 
 
 been found that the marks on the cast iron become filled up with 
 paint, and in some cases where there was a slight leakage of the 
 circulating water in the column guide plate, the marks were badly 
 corroded, making it impossible to determine the actual clearance 
 without proving same. If it is found that the required clearance as 
 in drawing has not been attained, it will be necessary to machine 
 some of the parts, until this requirement is met. If the top clearance 
 
Workshop Practice 47 
 
 is small, and the bottom clearance lari^c, then the piston can be 
 let up on the taper of the piston rod, which means that the length 
 of the piston rod will be reduced. If the clearance should be the 
 other way, small at bottom and large at top, then the bottom of 
 the cylinder will be examined to ensure there being no lumps on 
 same — if so, these lumps will be chipped off; but should this not 
 be sufficient, it will be necessary to fit a heavier or thicker bush 
 either in the top end or bottom end of connecting rod. It may be 
 the case that the piston would stand machining, and if so, then it 
 can be dealt with. The clearances in reciprocating engines are 
 usually as follows : — 
 
 H.P. top - - - - ^ to § inch. 
 
 H.P. bottom - - - - I to ^ ,, 
 
 LP. top - - - . -| to I „ 
 
 I. P. bottom - - - - I to I „ 
 
 L.P. top - - - - I to f „ 
 
 L.P. bottom - - - - # to I ,, 
 
 The above clearances allow for wear down of the connecting rod 
 bearings. 
 
 The operation of adjusting or setting the slide valves is carried 
 out in the following manner : — The valve gear is put in ahead 
 position, that is, the ahead eccentric rod is brought in line with the 
 valve spindle. It is first required to find the valve travel : this 
 amount is given on the drawing, and to ascertain if it is correct, 
 the engine is turned round until the eccentric pulley is at full throw 
 on the top. This is found by having a centre line through the pulley, 
 and also a centre line on the eccentric strap, both centre lines being 
 vertical. The engine is then turned round until the centre line on the 
 large part or throw of the eccentric pulley is in line with the centre 
 line on the eccentric strap; and when in this position a line is put on 
 valve spindle, either by using a trammel from a fixed point on the 
 bottom of the cylinder or valve spindle bracket, or by simply drawing 
 a line across the spindle under the gland. The engine is again 
 turned until the centre line on the small part of the eccentric pulley 
 is in line with the centre line on eccentric strap (Sketch No. 59). 
 Another line is put on valve spindle as before, and the distance 
 between is measured, representing the travel of the valve : if the 
 distance as measured does not correspond to drawing, then the link 
 block is moved until the required travel is arrived at, which means 
 that the eccentric rod is exactly in line with the valve spindle 
 usually termed " Link in line." As before explained, the moving of 
 the link block in or out decreases or increases the travel of the valve. 
 After travel is adjusted, the next operation is to find the leads of 
 the valves. The H.P. engine (piston valve) is turned on to the top 
 centre, and the space between the top inside edge of the valve and the 
 bottom of the port in the valve liner is measured by means of a small 
 wedge-shaped piece of wood. The engine is now turned to bottom 
 
48 
 
 "Verbal" Mores and Sketches 
 
 centre, and tlie space between the bottom inside edge of the valve 
 and the top edge of the bottom port is measured, and the amount 
 obtained represents the lead of the valve, with crank on bottom. If 
 these figures do not coincide with drawing figures, that is, if lead on 
 top is too much and too Httle on bottom, then the washer on which 
 the valves sit will require to be reduced, or if the leads were vice 
 
 No. 59.— Valve Setting. 
 
 1, Trammel. 3, Mark for valve at "mid-travel. 
 
 2, Mark for valve at "bottom." 4, Mark for valve at "top." 
 
 5, Mark for valve at "top lead." 
 
 versa, then a thicker washer would be required, or the eccentric rod 
 lined up. The same operation is carried out on the three engines. 
 
 Points of cut-off and port opening, and in some special cases the 
 points of admission and compression and release, are also taken. 
 The point of cut-off is obtained by starting with the engine on top 
 centre, and turning in an ahead direction. The valve is watched as it 
 goes down and opens the port to full port opening, then starts to 
 return, and at the point where it is edge and edge with the port 
 on the valve face the engine is stopped, and the distance it has 
 
Workshop Practice 49 
 
 travelled is measured from the mark on the column face to the mark 
 on the guide shoe. That distance is the point of cut-off, and may- 
 be -70 of the stroke, or as designed. Another and more exact method 
 
 <D 
 
 No. 6o.-^To Measure the Cut-off. 
 
 1, Wood baton. 
 
 2, Mark for "bottom centre." 
 
 Mark for 
 Mark for 
 
 "cut off."' 
 •'top centre." 
 
 by the use of batons. These batons are marked off, one for the 
 jalve face and one for the valve (Sketch No. 60), showing the ports 
 in the valve face and the edges of the valve. To set these sticks 
 
50 " Verbal " Notes and Sketches 
 
 the engine is put on top centre, and one baton is fixed to the top 
 of the valve spindle, the other to the top of the valve casing. By 
 setting the batons to correspond with the top lead which was found 
 by actual measurement, then all other points will be found to be 
 exactly correct, providing the marking-off of the batons was care- 
 fully done. A baton is also fixed on to the end of the piston 
 rod and a line put on with the crank on top centre, and the 
 engine turned until by observing the valve closing the port, as 
 shown on the batons, the engine is stopped and another line put 
 on the stick which is fastened to the piston rod, and the distance 
 between these marks represents the point of cut-off. The other 
 points are arrived at in the same manner, the explanation of the 
 terms being as follows : — 
 
 Admission. — Valve just edge to edge with port in valve face or 
 liner. 
 
 Lead. — Amount valve is open for steam with crank on centre. 
 
 Port Opening. — Greatest amount that valve opens port to steam. 
 
 Compression. — When exhaust edge of valve is in line with edge 
 of port closing same to exhaust. 
 
 Release. — When exhaust edge of valve is just edge to edge wilIi 
 port opening to exhaust. 
 
 The valve gear is now brought to astern position, that is, with 
 the astern eccentric rod in line with the valve spindle. The usual 
 points which are taken with astern gear are that of lead and travel, 
 which are found in the same manner as before described. The link 
 blocks, as before explained, are graded, and this is done by putting 
 the eccentric rod out of line with the valve spindle and particulars 
 taken of the valve settings, which gives decreased travel, earlier 
 cut-off, and increased lead. These points are for the guidance of the 
 engineer in charge, and through judicious use of this gear the most 
 economical working of the engines may be arrived at. 
 
 Connections on Cylinders, Pumps, &c., and Dismantling 
 Engines and Closing up Cylinders. 
 
 On each of the cylinders drain cocks are fitted, one on the 
 cylinder and one on the valve casing, and pipes are connected to these 
 cocks leading to the bilges, the cocks being operated by gear led 
 down to the bottom platform in the engine-room. Indicator cocks, 
 one on top and one on bottom of cylinder, are also fitted as well as 
 escape valves to allow of any excessive pressure in cylinder or casing 
 being liberated. A balance cylinder and piston is usually fitted on 
 the L.P. valve, so as to take the weight as far as possible ofif the 
 valve gear (see page 202). The bottom of the piston is open to 
 tlie steam in the valve casing and the top side is in a vacuum, 
 
Workshop Practice 
 
 51 
 
 being: connected by pipinj; to the condenser. There are several 
 patent balance cylinders on the market, such as Joy's, but the 
 principle is similar to that described. On the H.P. valve casing 
 the stop valve for admitting steam to the engine is usually fitted. 
 
 5) (^ {7) [^ 
 
 No. 61.— Trammelling Pump Links for Wear Down. 
 
 1, Lever pin. 
 
 2, Pump crosshead blocked up on 
 
 cover with glands fair and free. 
 
 3, Trammel distance. 
 
 4, Guide rod of crosshead. 
 
 5, Feed pumps. 
 
 6, Circulating pump. 
 
 7, Air pump. 
 
52 " Verbal " Notes and Sketches 
 
 and connections arc also led from this valve to the II.T. jacket 
 and to the I. P. valve casing through a valve, termed an impulse 
 valve (see page 183). This valve is used while heating up cylinders, 
 and also for assisting in smartly moving the engines while man- 
 oeuvring. The gland on the H.P. engine is usually packed with 
 patent packing or with metallic combination packing, the LP. gland 
 is sometimes packed in a similar manner, and the L.P. gland with 
 soft asbestos packing. The valve spindle glands, in the case of 
 H.P. and LP., are also fitted with metallic packing and the L.P. with 
 soft packing. In the majority of engines now constructed separate 
 pumps are fitted, but the type of engine for cargo steamers usually 
 has the pumps worked off the main engine. These pumps consist of 
 air pump, circulating pump, two feed pumps, and two bilge pumps. 
 These are operated by means of levers connected to the LP. engine 
 by means of drag links. The levers are supported on a double bear- 
 ing at the back of the LP. column, and are usually of two steel plates 
 with bosses between, and riveted together. The pins to which the 
 drag links are connected are riveted into the boss on the levers. At 
 the other end the drag links which connect to the pump crosshead are 
 fixed. The levers are bedded down in their bearings and the covers 
 leaded in a similar manner to that of the other bearings on the engine. 
 The drag links are trained and bedded on to their respective pins, and 
 the clearance of the air and circulating pumps are taken : to get the 
 clearance, the main engines are turned to position with crank on top 
 centre and mark put on air pump and circulating pump rod, or by 
 applying a gauge between crosshead and pump covers. The engine 
 is again turned to bottom centre, and another mark put on — the 
 distance between represents the travel of the levers ; and by discon- 
 necting the drag links and lowering the pump bucket until it rests 
 on the bottom, and putting a mark on, the difference between the 
 travel mark and this mark will represent the bottom clearance. 
 The pump bucket is then lifted up to the top and pulled by means 
 of tackle until it touches the head valve, and a mark put on, and by 
 comparing the two marks the clearance at top is arrived at. The feed 
 and bilge pumps are tested for clearance when the pumps are at 
 bottom stroke. The nuts on the spindles through the crosshead are 
 slackened and the plunger lowered until it rests on the bottom, a 
 mark put on, or gauged by callipers between the shoulder on spindle 
 and crosshead ; the distance representing the clearance will be found 
 by putting on a mark from the same point as before when the 
 plunger spindle is screwed up in crosshead. The usual clearance for 
 air pumps, feed and bilge pumps is as follows : — 
 
 Air pump - - - top, I inch, bottom, f inch. 
 
 Bilge pump- - - bottom, i to i^, inches. 
 
 Feed pump - - - bottom, | to i| inches. 
 
 It will be noticed that the air pump clearance is most on top; 
 this is explained by the distance between lever pins and crosshead 
 
Workshop Pnictice 
 
 53 
 
 being decreased as wear on the drag links is taken up. The engines 
 are now ready for dismantHng, and the cylinders are taken down, also 
 columns. Crank-shaft is lifted and cleaned and oiled and put bad 
 into place in the soleplate bearings. All hard bits or heavy bearing: 
 
 No. 62.— Cast-Steel Piston. 
 
 With Ramsbottom rings fitted into junk ring to allow of removal. 
 
 in crank-pin bushes and top end bearings are eased, and all gear 
 prepared for transfer to the ship. The cylinders are thoroughly 
 examined to ensure that there is no sand or dirt in any of the ports, 
 and this being so, they are ready for closing up. The piston rods 
 
 *No. 63.— Cast-Steel Piston. 
 
 Fitted with Ramsbottom rings. 
 
 For a cylinder 20 inches diameter the proportions are :- 
 b = ii inches. d = i inch. 
 
 e=ii^,; inches. 
 2 or 3 rings to be fitted. 
 
 c = | inch. 
 
 are put into the pistons and hard hammered up, locking cutters or 
 split pins fitted, and the whole is lifted and lowered into the cylinder. 
 The interior of cylinder has been beforehand rubbed over with 
 cylinder oil to prevent rusting during the time that machinery is 
 stationary. The H,P. piston is usually packed with Ramsbottom 
 
 * Reprinted by permission from "Marine Engine Design." 
 D. Van Nostrand Co., New York, 1910. 
 
 Prof. Edward M. Bragg 
 
54 
 
 "Verbal" Notes and Sketches 
 
 * No. 64.— Buckley Type Piston Ring. 
 
 For a piston 24 inches diameter the proportions are as follows : — 
 
 b = 2j inches. c-\l inch. d-i}J inches. e-i,'o inches. 
 
 f=ij inches. g=2.i inches. h = iinch. 
 
 No. 65.— Cylinder Valve Face. 
 
 Gutters and holes drilled to reduce wear. 
 NOTE.— The holes, i inch diameter, -^\, inch deep, are bored out 
 with a flat nosed drill. 
 
 * Reprinted by permission from "Marine Engine Design." Prof. Edward .M. Bragg. 
 D. Van Nostrand Co., New York, 1910. 
 
LINER EXPANDED BY HEAT ~^ \ Q | 
 
 ffi 
 
 No. 66. — Method of Shrinking on Propeller Shaft Liners 
 
 BRASS8 THICK 
 
 HOLE 
 
 FOR 
 
 PUTTY PUMP 
 
 i 
 
 TMitK poR brass! thick 
 
 AIR ESCAPE I 
 
 ^ BEARING 
 
 SPACE FILLED 
 
 ; BEARING 
 
 UP WITH LEAD PUTTY 
 
 No. 67. — Propeller Shaft Continuous Liner. 
 
 With Thickness Variation). 
 
 BRASS 4 THICK 
 
 No. 68. — Propeller Shaft Continuous Liuer. 
 
 •Stepped" and farced on by Hydraulic Pressure ilio tonsi. 
 
 [yo/a,r/>ai,'es5- 
 
Workshop Practice 55 
 
 rings and segment packing rings (Sketch No. 63), and these arc 
 assembled and junk ring put on and nuts screwed up. The nuts 
 on the junk ring are prevented from slackening back by means of 
 either split pin above the nuts if square-necked studs arc fitted, or 
 by means of a guard ring which bears against nuts or pins, and is 
 itself kept in place by being fitted on square-necked studs having 
 split pins through the nuts. The other two cylinders are closed up 
 in a similar manner, the LP. piston packing rings being same as 
 H.P., and the L.P. being either one of the patent packing rings or the 
 packing ring with coach springs or spiral springs pressing it out 
 against the cylinder wall. The valves are dealt with in a similar 
 manner, the H.P. being a piston valve, LP. a single-ported slide valve, 
 and L.P. double-ported slide valve. Previous to putting the valves 
 in place, oil gutters are cut on the face (Sketch No. 65) ; this assists to 
 reduce friction, and in the case of the LLP. grooves are turned on 
 the rings which join the valves. The cylinder and casing covers 
 are jointed w^ith asbestos joints, and in some cases asbestos tape, 
 glands are packed, and all openings to interior of cylinders or casings 
 closed up. The pistons and rods are supported, so that when lifting 
 cylinders the rods will not lower to the bottom of the cylinder ; the 
 valve spindles and valves are also supported, and the whole three 
 cylinders are now ready for transport to the ship. 
 
 Propeller Shaft Liners. 
 
 Propeller shafts are brass lined from end to end to prevent galvanic 
 action taking place between the brass liner and steel of the shaft. 
 The liners are fitted in two styles — 
 
 1. Shrunk on hot. 
 
 2. L'orced on cold by hydraulic ram pressure. 
 
 1. Shrinking on (Sketch No. 66). — The shaft is supported by bolting 
 up to one of the tunnel lengths, which leaves the whole length free to 
 receive the liner. The liner is then heated either by gas burners or by 
 a fire built underneath, and after sufficient expansion has taken place 
 the liner is drawn over the shaft by means of blocks and chain tackle. 
 When the liner cools down the contraction resulting is sufficient to 
 lock the liner to the shaft, screwed pins being seldom used in present 
 practice, as in quite a number of cases the pins have been found to 
 slacken back and come out of place. Before shrinking on, the hner 
 is bored out about 5^0 less in diameter than the shaft, therefore 
 for a 12-inch shaft the inside diameter of the liner will be 12 inches 
 ~?D?) inch= 11-976 inches, say ii{}j inches full. 
 
 NOTE. — If the liner sticks when being drawn on it may be forced on by 
 pressure at the end, or expanded again by building a fire underneath. 
 
 2. Forced on Cold (Sketch No. 68). — In this method the liner is 
 stepped to three diameters, the difference at each length being -jV inch. 
 The forward and after diameters should be a bearing fit, but the centre 
 
m 
 
 LINER EXPANDED BY HEAT^_g 
 
 T 
 
 V BLOCK 
 
 ^T= 
 
 V BLOCK 
 
Workshop Practice 55 
 
 rings and segment packing rings (Sketch No. 63), and these arc 
 assembled and junk ring put on and nuts screwed up. The nuts 
 on the junk ring are prevented from slackening back by means of 
 either split pin above the nuts if square-necked studs are fitted, or 
 by means of a guard ring which bears against nuts or pins, and is 
 itself kept in place by being fitted on square-necked studs having 
 split pins through the nuts. The other two cylinders are closed up 
 in a similar manner, the LP. piston packing rings being same as 
 H.P., and the L.P. being either one of the patent packing rings or the 
 packing ring with coach springs or spiral springs pressing it out 
 against the cylinder wall. The valves are dealt with in a similar 
 manner, the H.P. being a piston valve, LP. a single-ported slide valve, 
 and L.P. double-ported slide valve. Previous to putting the valves 
 in place, oil gutters are cut on the face (Sketch No. 65) ; this assists to 
 reduce friction, and in the case of the H.P. grooves are turned on 
 the rings which join the valves. The cylinder and casing covers 
 are jointed with asbestos joints, and in some cases asbestos tape, 
 glands are packed, and all openings to interior of cylinders or casings 
 closed up. The pistons and rods are supported, so that when lifting 
 cylinders the rods will not lower to the bottom of the cylinder ; the 
 valve spindles and valves are also supported, and the whole three 
 cylinders are now ready for transport to the ship. 
 
 Propeller Shaft Liners. 
 
 Propeller shafts are brass lined from end to end to prevent galvanic 
 action taking place between the brass liner and steel of the shaft. 
 The liners are fitted in two styles — 
 
 1. Shrunk on hot. 
 
 2. Forced on cold by hydraulic ram pressure. 
 
 1. Shrinking on (Sketch No. 66). — The shaft is supported by bolting 
 up to one of the tunnel lengths, which leaves the whole length free to 
 receive the liner. The liner is then heated either by gas burners or by 
 a fire built underneath, and after sufficient expansion has taken place 
 the liner is drawn over the shaft by means of blocks and chain tackle. 
 When the liner cools down the contraction resulting is sufificient to 
 lock the liner to the shaft, screwed pins being seldom used in present 
 practice, as in quite a number of cases the pins have been found to 
 slacken back and come out of place. Before shrinking on, the liner 
 is bored out about 5^0 less in diameter than the shaft, therefore 
 for a 1 2-inch shaft the inside diameter of the liner will be 12 inches 
 ~rVo inch= 11-976 inches, say lij}x inches full. 
 
 NOTE. — If the liner sticks ■when being drawn on it may be forced on by 
 pressure at the end, or expanded again by building a fire underneath. 
 
 2. Forced on Cold (Sketch No. 68). — In this method the liner is 
 stepped to three diameters, the difference at each length being ^V inch. 
 The forward and after diameters should be a bearing fit, but the centre 
 
56 "Verbal" Notes and Sketches 
 
 length need not be so ; as in the " shrinking on " method the Hner 
 is bored out a trifle less in diameter than the shaft at each " step " 
 and the liner is then forced on over the end of the shaft, by a 
 hydraulic ram exerting a pressure of about i lO tons. Notice that 
 the ram pressure only requires to be exerted for one of the stepped 
 lengths, as the three fit simultaneously. 
 
 Variation in Liner Thickness (Sketch No. 6']). 
 
 Occasionally the liner is cast in three thicknesses as shown in 
 the sketch, being thickest at the position of the forward bearing, 
 next at the after bearing, and least of all at the centre where the 
 shaft does not bear at all. Two holes are bored in the liner at the 
 centre length and putty is forced in by means of a pump through 
 one of the holes to fill up the clearance space inside, the other 
 allowing for the escape of air : these holes are afterwards filled up 
 by means of screwed pins riveted over. 
 
 Marking off Ship for Boring out — Propeller Shafting and 
 Thrust Block (Sketch No. 69). 
 
 The part of the ship's hull through which the stern tube passes 
 is bored out to a size so as to ensure the stern tube being a good fit 
 in same, and absolutely watertight. The method of marking off the 
 stern post and bulkheads for boring out is as follows : — In the centre 
 of the hole which passes through the stern bracket a wooden disc is 
 fitted completely filling the hole. Upon this piece of wood the centre 
 of the shaft from keel as given in drawing is marked, and the centre of 
 the present bore of the stern frame or bracket is taken. A small hole 
 ^V or iV inch in diameter is bored through the wood at these points 
 (Sketch No. 69). In the engine-room at the forward bulkhead, the 
 height of centre of shaft from keel is marked off, and also the centre of 
 the ship athwart-ships is marked. A small hole is also drilled here. 
 At the back of this hole a lighted candle or electric lamp is fixed and 
 the operator if by looking through from the stern to the engine-room 
 through the small hole in the wooden disc can see the light, then 
 that point will give the centre for boring out. If the light is not 
 seen, then it will be necessary to shift centres, and to facilitate this, 
 a sliding or movable centre is used, so that it can be moved about 
 until light is visible, the light now being seen from aft end of tube 
 bearing to engine-room. Another centre is fitted in engine-room 
 bulkhead, and the light picked up. A similar centre is fitted in the 
 after bulkhead in the tunnel, and light sighted. The whole is again 
 sighted from the aft end, and light being seen, a centre is put in holes 
 in discs and circles drawn around equal to the boring out size ; proof 
 marks are also put on so as to test boring bar. The bulkhead in 
 forward end of tunnel is marked off in a similar manner, and is 
 bored out for a bulkhead gland. At various distances throughout 
 

 kV ■ 
 
 /.r-' . ' ■ 1, 
 
 
 i 
 
 
 1 
 
 Ul<-'«-I\. LV^CilVl 
 
 -J 
 
 required height (Sketch No. 70). At the forward end of the tunnel 
 the thrust block is situated (see page 182) : this block is made up of a 
 number of shoes, as the design may require. The shoes are of cast 
 iron, lined with white metal, having gutters cut on each side, oil being 
 supplied from an oil box cast on each shoe. Water service connec- 
 tions are also made so that a water circulation takes place throughout 
 the interior of the shoe. The block itself is of cast iron, and is 
 rigidly bolted to the ship's frame, this part of the ship being specially 
 
FORWARD 
 BULKHEAD. 
 
 ENGINE ROOM. 
 
 CENTRE 01^ CRANK SHAFT 
 FROM DRAWING 
 
 No. 69.- 
 
 1. At distance up marked on drawing as "shaft centre" and at centre athwart-ships, cut a hole 
 (say I inch diameter) in the engine-room forward bulkhead, and to this fix a piece of tin ; punch a hole 
 ■^ inch diameter at centre and place a small electric lamp in a box in the position shown. 
 
 2. Block up the stern post hole (previously bored out to /ess than the required diameter) with a 
 wooden disc, in which cut out a i-inch hole ; on this pin a sheet of tin with a ■pf-inch hole at the dead 
 centre (see Sketch), and from the centre scribe in the proof circle for boring out. 
 
 3. Prepare two straightedges, say 36 inches in length by 3 inches in width, and recessed at the 
 middle, say 6 inches by j'j inch, so that when placed together the slot so formed will be 3 inches 
 by ^ inch. 
 
 4. Have, say, a a-inch hole punched in after peak bulkhead and place the sticks with slot horizontal 
 
 Method of Sighting for Line of Shafting and Boring Stern Post. 
 
 across the hole : now move the straight edges up and down until the light is seen when looking through from 
 outside the stern post, then with a suitable radius measure upwards and downwards on the bulkhead, and 
 make centre punch marks. Repeat the foregoing with the sticks and slot in a vertical position, and when 
 the light is again picked up make centre punch marks on the bulkhead port and starboard at same radius 
 
 5. Fill up the hole with wood and from the marks so obtained find the dead centre from which a proof 
 circle can be set off for boring out. j -u j j 
 
 6. Intermediate bulkheads are treated in the same manner as just described, and as a hnal test tin 
 sheets, with ,Vinch holes in each, are pinned on to all the bulkhe.id openings, and the light, placed 
 forward, should then be visible thiougli the lot when viewed from the outside of the ship through the hole 
 in stern post. 
 
 NOTE.— Ooe man is placed to look through the holes and another moves the sUding sticks to find the light 
 
Workshop Practice 57 
 
 the shaft tunnel sighting sticks are erected, and from these the 
 height of the various stools for the tunnel bearings are derived 
 The centre on the forward end of the engine-room is used when the 
 holding-down holes are templated and bored previous to the engines 
 being installed. In this operation the template is laid down on the 
 engine-room floor, and the centre line on the template is set in line 
 to a centre line on the forward bulkhead in line with the sighting 
 centre. If the shafting is in place then from the centre of the thrust 
 shaft the template is set, or if shaft is not in place, then the template 
 is set to the centre of the hole in which the bulkhead gland is fitted. 
 The stern frame and bulkheads are bored out usually by power 
 derived from an electric motor, or if no electric power is available 
 then a small donkey boiler and steam-engine are erected connecting 
 with belt to the boring bar. After boring out, the stern tube is put 
 in place from the inside, and drawn hard up into position by means 
 of the nut on the after end. The inner end is bolted to the bulkhead 
 and wood liner fitted at back of same. At the outer end of stern tube 
 a brass bush is fitted, termed the stern bush. This bush is lined with 
 lignum vitzE, the bottom layers having the grain end on, so as to reduce 
 the wear as much as possible. The lignum vitae is fitted into channels 
 in the brass bush, and is prevented from working out by a collar at 
 the forward end of the bush, and at the aft end by means of a brass 
 gland bolted to the flange of the bush itself (see illustration facing 
 page 361), The space into which the wood is fitted is tapered 
 in a fore and aft direction, and the wood is driven up into same, thus 
 ensuring a good fit. The tail shaft is shipped into stern tube from 
 the interior of the tunnel, and on the inside flange of the stern tube 
 a gland is fitted, which prevents any leakage taking place into the 
 tunnel. This gland is packed with soft rope-yarn packing soaked in 
 tallow, and a water connection is led from the top of the stern tube 
 to this gland, so that in the event of getting hot the gland and shaft 
 can be cooled out. The propeller is held on shaft by means of a 
 feather and nut. This nut is hard hammered up, and a stopper 
 fitted. In the recess in front of the boss a rubber ring is fitted to 
 prevent water getting in or eating away the part of the shaft which 
 is not covered by the brass liner, and in some cases short glands are 
 fitted on the forward side of the boss, being packed with a rubber ring 
 (Sketch No. 69). The tunnel bearings are of cast iron lined with 
 white metal, and are supported on built-up stool, between which and 
 bearing block teakwood liners are fitted, bringing bearings up to 
 required height (Sketch No. 70). At the forward end of the tunnel 
 the thrust block is situated (see page 182) : this block is made up of a 
 number of shoes, as the design may require. The shoes are of cast 
 iron, lined with white metal, having gutters cut on each side, oil being 
 supplied from an oil box cast on each shoe. Water service connec- 
 tions are also made so that a water circulation takes place throughout 
 the interior of the shoe. The block itself is of cast iron, and is 
 rigidly bolted to the ship's frame, this part of the ship being specially 
 
q 9UV 
 
 ciu^ic 
 
 } lu ((I or, ! 
 
 (iFi 111 ;f. in 
 
 )X. 
 
 I.IFM 
 
 '^ c 
 
 )OU 
 
 I 
 
 until lignt IS visiDie, tne iigni nuw ucuig seen num ttiu 
 bearing to engine-room. Another centre is fitted in engine-room 
 bulkhead, and the hght picked up. A similar centre is fitted in the 
 after bulkhead in the tunnel, and light sighted. The whole is again 
 sighted from the aft end, and light being seen, a centre is put in holes 
 in discs and circles drawn around equal to the boring out size ; proof 
 marks are also put on so as to test boring bar. The bulkhead in 
 forward end of tunnel is marked off in a similar manner, and is 
 bored out for a bulkhead gland. At various distances throughout 
 
Workshop Practice 57 
 
 the shaft tunnel sighting sticks are erected, and from these the 
 height of the various stools for the tunnel bearings are derived 
 The centre on the forward end of the engine-room is used when the 
 holding-down holes are templated and bored previous to the engines 
 being installed. In this operation the template is laid down on the 
 engine-room floor, and the centre line on the template is set in line 
 to a centre line on the forward bulkhead in line with the sighting 
 centre. If the shafting is in place then from the centre of the thrust 
 shaft the template is set, or if shaft is not in place, then the template 
 is set to the centre of the hole in which the bulkhead gland is fitted. 
 The stern frame and bulkheads are bored out usually by power 
 derived from an electric motor, or if no electric power is available 
 then a small donkey boiler and steam-engine are erected connecting 
 with belt to the boring bar. After boring out, the stern tube is put 
 in place from the inside, and drawn hard up into position by means 
 of the nut on the after end. The inner end is bolted to the bulkhead 
 and wood liner fitted at back of same. At the outer end of stern tube 
 a brass bush is fitted, termed the stern bush. This bush is lined with 
 lignum vita;, the bottom layers having the grain end on, so as to reduce 
 the wear as much as possible. The lignum vitae is fitted into channels 
 in the brass bush, and is prevented from working out by a collar at 
 the forward end of the bush, and at the aft end by means of a brass 
 gland bolted to the flange of the bush itself (see illustration facing 
 page 361). The space into which the wood is fitted is tapered 
 in a fore and aft direction, and the wood is driven up into same, thus 
 ensuring a good fit. The tail shaft is shipped into stern tube from 
 the interior of the tunnel, and on the inside flange of the stern tube 
 a gland is fitted, which prevents any leakage taking place into the 
 tunnel. This gland is packed with soft rope-yarn packing soaked in 
 tallow, and a water connection is led from the top of the stern tube 
 to this gland, so that in the event of getting hot the gland and shaft 
 can be cooled out. The propeller is held on shaft by means of a 
 feather and nut. This nut is hard hammered up, and a stopper 
 fitted. In the recess in front of the boss a rubber ring is fitted to 
 prevent water getting in or eating away the part of the shaft which 
 is not covered by the brass liner, and in some cases short glands are 
 fitted on the forward side of the boss, being packed with a rubber ring 
 (Sketch No. 69). The tunnel bearings are of cast iron lined with 
 white metal, and are supported on built-up stool, between which and 
 bearing block teakwood liners are fitted, bringing bearings up to 
 required height (Sketch No. 70). At the forward end of the tunnel 
 the thrust block is situated (see page 182) : this block is made up of a 
 number of shoes, as the design may require. The shoes are of cast 
 iron, lined with white metal, having gutters cut on each side, oil being 
 supplied from an oil box cast on each shoe. Water service connec- 
 tions are also made so that a water circulation takes place throughout 
 the interior of the shoe. The block itself is of cast iron, and is 
 rigidly bolted to the ship's frame, this part of the ship being specially 
 
58 
 
 Verbal " Notes and Sketches 
 
 strengthened. The interior of the block is used as a lubricating 
 bath, being filled with fresh water and oil, through which the collars 
 of the thrust shaft revolve, thus lubricating each face of the shoes. 
 
 ho 
 
 a ^ 
 
 o 
 
 o ^ 
 
 QQ 
 c 
 
 I ^ 
 
 R5 
 
 o 
 
Workshop Practice 
 
 59 
 
 Erecting Machinery in Ship. 
 
 The tail shaft being shipped into place, and stern tube gland fitted 
 and packed, the intermediate lengths of shafting are now put in and 
 
 No. 71.— Cast-iron Chocks. 
 
 I, Teakwood wedges. 2, Chock. 3, Joint. 
 
 NOTE. — The size of chock varies, but average proportions are: 
 tfvidth 6 to 8 inches, depth i to li- inches, fitting strips 5 to i inch. 
 
 set Up in line. The shaft is blocked up and tunnel bearing block put 
 on shaft, being bound on same by means of canvas between cover of 
 bearings and shaft. The aft coupling of the shaft is brought fair to 
 the coupling of the propeller shaft by means of feelers, that is, the face 
 of the two couplings are tested to ensure that a feeler of say -oio can 
 be inserted at all four points,- and the rim of the flange of the coupling 
 tested also by means of a straight-edge, to ensure that shafts are in 
 line sideways, and also for height. The space between the bottom 
 of the bearing block and the stool is now filled up with teakwood 
 liner. During the filling and on completion the shaft couplings are 
 tested to ensure that they remain fair. The next length of shafting 
 is set up in a similar manner, and so on until the complete length of 
 shafting has been set up. At the forward end of the tunnel where 
 the shaft passes through the bulkhead, another gland is fitted, so 
 that in event of the tunnel being flooded, by shutting the watertight 
 door at the entrance to the tunnel, no water would pass into the 
 
6o 
 
 " Verbal " Notes and Sketches 
 
 engine-room. This gland is also packed with soft rope-yarn packing. 
 The thrust shaft is set up to the coupling of the intermediate shaft and 
 set, and the holes for fixing block to seating are bored, ?iW^ fitted bolts 
 put in. The engine soleplate with crank-shaft in place is brought 
 
 ^TANK TOP. 
 
 No. 72.— Types of Cast-iron Chockj 
 
 4, Bolt screwed through tank top. 
 
 into line with coupling of thrust shaft and set up in a similar manner 
 as that previously described, flange of couplings set fair face to face 
 and on the rim of flanges. To arrive at this result the soleplate is 
 made up at suitable points on iron wedges and plates, and these 
 wedges are driven as required to bring crank-shaft coupling up to 
 height of thrust shaft coupling. The soleplate and crank-shaft are 
 moved bodily as required by means of screw jacks. The couplings 
 being fair the space between the engine-room seating and the sole- 
 plate is made up by means of cast-iron chocks. These chocks are 
 usually fitted at each bolt which binds soleplate to ship, and are 
 chipped and filed until they are a good fit. The holes for bolts or 
 studs are bored through the engine seating, if not previously marked 
 off by template. In the case of there being a tank under the engine- 
 room, screwed studs will be fitted as holding-down bolts having a nut 
 inside the tank, jointed with washer and grummet. The soleplate 
 being now made up and set, the columns and cylinders are lowered 
 into position, and gear erected on engine. The pipes connecting the 
 various parts of the engines and boilers are now fitted and jointed, 
 the main connections on the engine being as follows : — 
 
 Main Steam Pipe. — From boilers to engine stop valve. 
 
 Main Injection Pipe. — From valve on ship's side to bottom of 
 circulating pump. 
 
 Main Discharge Pipe. — From top of condenser to ship's side. 
 
 Feed Pump Suction. — From hot-well to suction valves on feed 
 pump. 
 
/ 
 
 Workshop Prtictice 6i 
 
 Feed Pump Discharge. — From fectl pump discharge valves to 
 boiler. 
 
 Bilge Pump Suction. — Led to distribution box in engine-room, 
 Irom which various holds and wells are connected. 
 
 Bilge Pump Discharge. — From bilge pumps to discharge valve 
 on ship's side. 
 
 The boilers are erected on stools in the boiler hold, chocks being 
 fitted between the boiler shell and the stools (see page 156). Chocks 
 are also fitted between the boilers, and stays are also fitted from the 
 ship's side to the boiler, to prevent movement of the boilers in bad 
 weather. Knees are also fitted at both ends of the boiler riveted 
 to the tank top, and being close up to the front of the boiler at 
 the centre; these knees are usually left from ^t to Jl- inch clear, to 
 allow for expansion of boiler (see page 156). The usual mountings 
 on the boilers are as follows : — 
 
 Main stop valve - - 'v 
 
 Auxiliary stop valve - tt h ^ n -i 
 
 r.. J u • ^1 r Usually on top of boiler. 
 
 Steam to whistle - - / •' ^ 
 
 Safety valves 
 
 Gauge glass connections 
 Scum cock - 
 Auxiliary feed check 
 Main feed check - 
 Test cocks - 
 Salinometer cock - 
 
 Blow-down cock - - \ r^ \ ^^ r u -i 
 
 T^ • 1 - On bottom of boiler. 
 
 Dram cock - - - ) 
 
 After boilers have been installed and all connections raised steam 
 is got up and the boiler covering put on. This is usually one or 
 other of the specialities on the market. It is put on in the form of 
 wet pulp and dried by the heat of the boiler. Outside, a sheet-iron 
 casing is fitted extending to the bottom quarter of the boiler, and in 
 some ships asbestos mats are fitted round the bottom of the sheet 
 covered with wire netting. After boilers are covered, steam is raised 
 and safety valves set. This means that the washers between the 
 safety valve nuts and the standards are taken out and the nuts 
 adjusted so that the valves will lift and release the pressure on the 
 boiler when it has reached the designed pressure. In a boiler having 
 forced draught, an accumulation test is necessary. This means that 
 with forced draught being maintained to the pressure required, 
 usually f inch air pressure in the ashpits, the pressure on the boiler 
 must not rise more than 5 lbs. on the figure required, thus showing 
 that the safety valves are of ample area to release any pressure over 
 that which it is designed for the boiler to carry. After valves have 
 been set, the space between the nuts and collar is gauged, and the 
 
 On end of boiler. 
 
62 
 
 *' Verbal " Notes and Sketches 
 
 washers fitted accurately to same. If the engines are in an advanced 
 state of construction at this time, it is usual to have what is termed a 
 basin trial on the same day as the safety valves are set. During a 
 basin trial the engines are revolved at a slow speed, it not being possible 
 to exceed this, owing to the risk of carrying away the mooring ropes. 
 
 No. 73 —Wear Down Gauge. 
 
 1, Steel pin touching' shaft. 
 
 2, Collar touching gauge when pin is touching shaft. 
 
 3, Holes for dowel pins. 
 
 The gauges shown in Nos. 75 and 76 are employed in 
 testing the wear down of shafting, as when the bearings work 
 down a clearance will be shown at the point of the bolt in 
 No. 75 or between the projection on the gauge plate of No. 76. 
 These clearances should be carefully noted for each bearing, 
 and a record kept for future reference and subsequent wear 
 down. 
 
 Auxiliary Machinery. 
 
 In describing the auxiliar\' machinery it will be understood that 
 we are dealing with an installation suitable for a set of engines the 
 construction of which has been previously described. As before 
 explained, the feed pumps are connected and operated by the main 
 
Workshop Practice 6^ 
 
 engines. These pumps discharge the feed water to a feed heater, 
 which is situated on the upper platform of the engine-room. The 
 feed water passes through this heater, and becomes heated by contact 
 with steam which is admitted into the interior. A heater of this type 
 is termed a direct contact heater. The water falls to the bottom o{ 
 the heater, and falls by gravitation to a feed pump, which is situated 
 on the bottom platform of the engine-room. This pump delivers the 
 water through the filter, which is one or other of the various makes 
 described elsewhere, and then through the feed check or valve into 
 
 No. 74.— Wear Down Gauge. 
 
 1, Gauge. 
 
 2, Small part filed on top of housing to allow gauge to touch shaft. 
 
 the boiler. This pump is usually controlled by automatic gear in the 
 feed heater, which regulates the speed of the pump to the amount of 
 water passing through the heater. The next auxiliary is that usually 
 termed the " General Service Donkey Pump." This pump has con- 
 nections suitable to draw from the sea, hot-well, tanks, and bilges 
 and can discharge to the boilers (through the auxiliary feed checks), 
 tanks, and overboard. 
 
 The ballast pump is used for pumping the various ballast tanks in 
 the ship, and has connection to all parts of the ship, also sea and bilge 
 
64 "Verbal" Notes and Sketches 
 
 suction, and can discharge overboard and into the tanks (see illustra- 
 tion facing page 198). An evaporator is fitted, one of the various types 
 described elsewhere, the principles of which are as follows : — Steam is 
 passed through copper pipes of various shapes ; outside of these pipes 
 is sea water, which becomes heated, and gives off a steam vapour ; 
 this vapour is collected and led off either to the condenser or L.P, 
 engine casing, thus adding to the amount of feed water which is 
 pumped into the boilers. A small pump is fitted, usually operated 
 by the main engine pump levers. This pump has a sea suction and 
 discharge into the evaporator, and the amount of water being pumped 
 in is adjusted so as to make up for the amount being evaporated. 
 There are various types of feed water filters on the market, the 
 principle of which is to extract the grease and impurities from the 
 feed water. The filter medium usually consists of cloths of the nature 
 of towelling held between metal perforated grids, and in some filters 
 furnace slag is used, proving a cheap and efficient filtering material. 
 In large ships a sanitary pump operated by the main engine levers is 
 fitted, but in cargo steamers it is usual to have a tank on the top of 
 the engine-room skylights ; this tank is filled up every morning, 
 supplying the necessary water for the sanitary system throughout 
 the day. In ships having forced draught a fan engine is fitted ; this 
 engine operates the fan which supplies the air to the boiler furnaces. 
 In Howden's system the air is carried through a trunk, and then 
 passes around tubes situated in the boiler uptake. The air is heated 
 by this means before passing into the furnaces. The usual pressure 
 to carry on the air gauge or fan is from i i to 2 inches ; this gives a 
 pressure in the ashpits of f to | inch. It will be understood that this 
 air pressure may be altered according to conditions, such as nature 
 of coal being used, and also as regards weather conditions. In the 
 stokehold an ash hoist is fitted. This may be one of the specialities, 
 such as Alley & M'Lellan's, Crompton's, or See's ash ejector. But it 
 is more common to have a small steam winch fitted up on the top of 
 the fiddley, with a steel wire rope led through pulleys into the venti- 
 lators, and thence to the stokehold floor. If the ship is fitted with 
 electric light the electric engine is usually in the engine-room, steam 
 being supplied either from the auxiliary steam pipe or direct from 
 the boiler. This engine is generally fitted with a governor so as to 
 ensure steady running. On deck the machinery usually consists 
 of eight or twelve winches, steam being supplied from the main or 
 donkey boiler, and the exhaust from these winches is led back to 
 an auxiliary condenser situated in the engine-room. The auxiliar\- 
 condenser is generally arranged so that the condensed steam flows 
 into a tank underneath ; the feed pump is connected to same, and 
 supplies the donkey boiler with feed water from this source. The 
 circulating water for the condenser is usually supplied by a small 
 pump fitted for this purpose, and in up-to-date installations the 
 condenser is supplied with circulating water from an engine which 
 works an air circulating and feed pump together, a very compact 
 
Workshop Practice 65 
 
 arrangement. A steam windlass is fitted on the forecastle head, and 
 in some cases a warping capstan is fitted on the poop or aft end of 
 the ship. On the top platform of the engine-room the steering 
 engine is situated : this engine has exhaust connections to the main 
 and auxiliary condensers and also to the atmosphere. The control 
 gear for this engine is led from the bridge, and is operated by means 
 of the steering wheel. There are various types of steering engines 
 on the market, but the main principles of each are similar. In some 
 ships the steering engine is housed aft, being directly connected to 
 the rudder head, and the connecting shafts are led along inside a 
 casing or deck to the engine, there operating the valve on the steering 
 engine ; this valve is termed the control valve. A sketch is given 
 showing the arrangement of shafting operating the control valve 
 and a description of the various types of steering gears is given 
 elsewhere. (See page 340.) 
 
 Trial Trips. 
 
 On completion of the installation of the machinery on board ship, 
 and previous to handing the ship over to the owner's representatives, 
 a trial trip is run. This usually consists of a series of runs over a 
 measured course, posts or sighting points being erected on the shore, 
 the distance between being exactly one nautical mile. After ship 
 leaves the harbour, the compasses are adjusted, that is, the ship is 
 slowly steamed in a circle, the compass adjusters during this time 
 finding out and adjusting the reading of the compasses supplied to 
 the ship. In the engine-room an engineer is told off to attend to a 
 special part of the machinery, one attending to the boilers, regu- 
 lating the water supply and seeing that the steam pressure is main- 
 tained. One man looks after an individual engine, overlooking the 
 running of the main bearings, eccentric straps, and crank-pins. On 
 the middle platform men are also stationed, who observe the running 
 of the top end bearings, guide shoes and piston rods, and valve gear. 
 The piston rods are swabbed with cylinder oil, and the other bearings 
 on connecting rod and guide shoes are supplied with oil from siphon 
 boxes (see page 197) on the top platform, but it is usual on trial 
 trips to augment this supply by hand feeding. A man attends to 
 the pumps and connections on same, overlooking the pumping of 
 bilges, supply of circulating water, and working of feed pumps. An 
 engineer is also in attendance in the tunnel, whose duty it is to 
 attend to the lubrication of the tunnel bearings and thrust block. 
 On the top platform a man is also stationed attending to the supply 
 of oil in the siphon boxes and the working of the feed heater and 
 steering gear, if same gear is situated in the engine-room. It is 
 usual to proceed slowly to the measured mile so as to gradually work 
 the bearings into good running condition. All being well and ready 
 for the first run, draughtsmen are told off for taking indication cards 
 fi and counters, and observing pressures on the various gauges connected 
 
 ! 5 
 
66 "Verbal" Notes and Sketches 
 
 with the machinery. It will be understood that all operations have 
 to be smartly carried out as the time which elapses between going 
 on the mile and coming off, even in a slow cargo tramp, is not of long 
 duration. Immediately before coming in line with the post on the 
 shore a warning bell is rung, "get ready," and then when in line 
 the telegraph is rung hard signifying that the ship is " now on the 
 mile." When the mile has been run and the ship in line with 
 the other post or point on shore the telegraph is again rung, and 
 the engines are slowed down, while preparations are made in the 
 stokehold for the next run. The ship is brought round again and 
 all ready for the return run. This is carried out five or six times, 
 and then the course is laid for a run of three to six hours at a steady 
 speed, thus proving that machinery is in good working order. During 
 the running on the mile, coal is measured in the stokehold, and after 
 indicators, cards, and particulars taken have been worked out a 
 statement is prepared showing the result of the various runs on the 
 mile. In large passenger ships and Admiralty ships runs of thirty 
 hours' duration are made, the trial trips in these cases usually 
 extending to four or five days. In Admiralty trials the feed water 
 is measured, and the firing is carried out on a system of time firing, 
 that is, arrangements are made to burn a certain amount of coal per 
 square foot of fire grate per hour. The coal is measured out, and on 
 the ringing of a gong or similar signal the firing in each stokehold 
 takes place. 
 
 Care and Upkeep of Machinery. 
 
 In considering the care required to keep a set of triple expansion 
 engines in good condition, we will deal with a set of new engines 
 and consider what means are required to maintain the machinery in 
 an efficient condition. It should be borne in mind that a loose 
 bearing has as much chance of heating up as one that is too finely 
 adjusted, especially when it is a connecting rod bearing that is in a 
 slack condition. The bearing will knock on the centres ; this knock- 
 ing tends to spread the white metal, with the result that ridges are 
 formed on the side of the bearings, and also the knocking has the 
 tendency to press out the oil which is between the bush and the pin. 
 To ensure a bearing being in proper adjustment, after leads have 
 been taken off and found correct, the bearings should be put together 
 and nuts hammered up until they are at the marks which were put 
 on when leads were in bush. By inserting a slice bar or other 
 suitable bar between the web and the bush and testing the bush to 
 see that it moves from side to side, this will prove that bush is not 
 too tight, and should give good running results. The same operaton 
 should be carried out on the top end bearing also. After ship has 
 done outward voyage, the top main bearings should be lifted and wear 
 down gauge applied. There are various forms of wear down gauges 
 supplied by various builders. Sketches, Nos. 73 and 74, are given 
 
Workshop Practice 67 
 
 showinj^ two forms of this gauge which are generally supplied. If 
 wear has taken place, notes of same should be taken, and after the 
 next run this reading should be again verified, as if the wear continues 
 it is possible that the chocking and lining up of the soleplate has not 
 been properly carried out. The eccentric straps are also lialjJe to 
 wear, especially when coming to a bearing, and to avoid the trouble 
 of opening up valve casings and testing setting of valves, a simple 
 method of proving same is as follows, when engines are new, and 
 this should be done in the works if possible : — With the valve standing 
 at full travel upwards, a mark is put on valve spindle, and from this 
 mark a small trammel is made, touching a point either on the 
 cylinder or valve spindle guide bracket (Sketch No. 59). By turning 
 engine into similar position and trj'ing trammel, any wear down that 
 has taken place can be seen at once, the wear down having taken 
 place either in saddle block bearings or eccentric straps. Another 
 method is to put valve to top lead and put a trammel mark on with 
 spindle in this position ; this is easier, as it only entails turning crank 
 CO top centre, and having gear full ahead, care being taken that link 
 block is in same position as when trammel marks were applied. 
 Piston rods should be carefully watched to see that engines have 
 been carefully lined off, and that glands are true to bore of 
 cylinder, a defect which will show up very early if such should be 
 the case (Sketch No. 48). The working of the various pumps 
 should be noted, and wear of pump links tested in the usual manner, 
 that is, by disconnecting same and testing distance from pump cross- 
 head to pins on lever by means of gauge, which should be made and 
 kept for this purpose (Sketch No. 61). A hint may not be out of 
 place as regards circulating pump, and that is to use as little 
 circulating water as is necessary to ensure good vacuum. By care- 
 fully observing vacuum gauge and gradually closing down circulating 
 inlet it will be found possible to ease the load on pump to a con- 
 siderable extent. The H.P. piston valve should be kept in as tight 
 a condition as possible, and it is not conducive to a good working 
 piston valve to keep on lining out the rings on same. This lining 
 only tends to wear the valve liners into an oval shape, with the 
 result that reboring out is necessary. If the valve liners are plain, 
 then the turning of two or three small grooves round the circumfer- 
 ence of rings will assist to keep valve tight, as condensed steam gets 
 into grooves and forms a film between liner and ring (see page 207). 
 The H.P. piston, being fitted with Ramsbottom rings, should give 
 good results if the rings have been properly manufactured, but if 
 they show signs of having lost their elasticity, then new ones should 
 be fitted. Another point regarding these rings is to have them as 
 near a fit in the grooves in piston as possible, for if slack, then the 
 constant change from one side to the other will not only wear out 
 the rings but will inflict considerable damage on the bonnet or 
 packing ring. The I. P. slide valve usually gives trouble, and the face 
 of valve and valve face on cylinder should be carefully tested by 
 
68 "Verbal" Notes and Sketches 
 
 means of straight-edge and feelers to ascertain that wear is taking 
 place equally all over. Should the valve show wear round the out- 
 side, that is, the inside ports or bars show high, then it will help to 
 equal the wear if a few short gutters are cut on the part that is wear- 
 ing. Another good plan is to bore a series of holes with a flat-nosed 
 drill (Sketch No, 65). These holes should only be about rh to yV inch 
 deep. It is the practice now to bore out the cylinders with a bell 
 mouth at either end, the piston travels the extreme length of the 
 bore, with the result that no ridges are formed at top and bottom of 
 cylinders. Condensers in new ships are sometimes a source of trouble, 
 leaking taking place, with the result that boiler density is increased. 
 A good test for feed water is by means of nitrate of silver, and the test 
 consists of drawing off a small quantity of feed water in a tumbler or 
 other transparent vessel and adding a drop of nitrate of silver; should 
 the water become milky then salt is present, and the amount can be 
 gauged by the resultant whiteness of the water. The use of water 
 service on engine bearings has greatly decreased, as engineers find 
 that a bearing will run just as well without water, always allowing 
 that it is in line and properly adjusted. Once water is used it is not 
 possible to run a bearing without it, so that the use of water, even in 
 small quantities, should be avoided. 
 
 How to keep a Watch. 
 
 The engineer's life at sea is not exactly a bed of roses and the 
 following description of his duties during the time he is on watch will 
 emphasise this statement. The engineer whose turn it is to relieve 
 will be called at a quarter before the hour on which he takes up duty, 
 and promptness in relieving is most important. On entering the 
 engine-room the first inspection should be the steering gear, bearings 
 examined, and moving parts inspected to ensure all being in good 
 order. The feed heater is next visited and pressure on steam gauge 
 noted. Descending to the middle platform L.P. piston rod is felt by 
 hand, also top end and face of columns and guide shoes. The valve 
 gear or L.P. engine is next looked over, and the I. P. and H.P. engines 
 dealt with in the same manner. The rocking shaft bearing is felt by 
 hand, and the crosshead links and top end of the pump links. All 
 being well, the bottom platform is next visited, and the bottom ends 
 and eccentric straps and main bearings felt by hand. During the 
 passage from one bearing to another, the L.P. and LP. pressure gauges 
 are glanced at, to ensure that pressure is being maintained, also the 
 vacuum gauge. The boilers are next visited, and height of water in 
 gauge glasses and steam pressure noted, also that the firemen are 
 at their duties, preparing to clean fires. The pumps are next ex- 
 amined, care being taken to ascertain that bilge pumps are working, 
 and also the connections examined to see what part of the ship the 
 bilge pumps are drawing from. Port and starboard engine-room 
 bilges are examined to ascertain the depth of water in same. The 
 
\Vorkshop Practice 69 
 
 thrust block is next felt over by hand, and the interior of block- 
 examined to see that collars on shaft are immersed in the oil and 
 water bath. The tunnel is next inspected, and each individual bear- 
 ing felt by hand, also the stern tube gland. The tuiniel well is 
 examined to see that water is not excessive ; then back to engine- 
 room, and the word passed, " All right," to engineer who is going 
 off duty. 
 
 The foregoing inspection is usually carried out in from seven to 
 ten minutes. By this time the firemen will be well on the way 
 cleaning fires, and the engineer will know in which boiler fires are 
 being cleaned; this being so, the feed checks should be regulated, as 
 the boiler on which fires are being cleaned will be at slightly lower 
 pressure than those which are steaming full. As soon as the fires on 
 this boiler are well away and the next fire started cleaning, it will be 
 necessary to again regulate checks, and by the half hour after going 
 on watch, steam should be at full working pressure and checks can 
 then be set, so that with but little alteration the rest of the watch 
 can be run. Should there be no greasers carried, then it will be part 
 of the engineer's duty to attend to the oiling of the machinery. Oil 
 is usually a precious liquid on board ship, and the engineer will only 
 be allowed a certain amount on which to run his watch. The top 
 cups on the side of the cylinder will first claim his attention, and 
 should be filled up to | or h inch below top of tube, siphons taken 
 out and dipped into oil and then put back. At the half hour after 
 going on watch the first oiling round should take place. When 
 filling up top cups on engine, the steering gear should be visited and 
 oiled if it is situated in the engine-room, as many gears are. The 
 main bearing cups will require filling up, and siphons redipped as 
 was done on top, eccentric straps oiled, and it may be mentioned 
 that very little oil, properly applied, is as much good as a canful 
 poured on, which only runs out of the bearings and does not lubricate. 
 It is generally the rule to supplement the siphon feed to connecting 
 rod bearings by hand feed ; usually the rule is to insert oil can into 
 oil cup, and give what can be supplied in two or three revolutions, but 
 this amount varies according to how the machinery runs. The valve 
 gear is usually oiled after being on watch one hour, and then again 
 one hour before being relieved. The pump links and rocking shaft 
 bearings are dealt with along with the connecting rods and eccentric 
 straps, that is every half hour. In some engines siphon fed oil cups 
 are fitted to rocking shaft bearings and pump links, so that in this 
 case it is only necessary to refill cups. 
 
 The usual rule for evaporators is two hours each watch, so that 
 one hour after coming on it will be requisite to get same under weigh. 
 Steam is turned on, and feed pump set, and vapour valve opened, and 
 height of water maintained in gauge glass on evaporator, and steam 
 gauge set to working pressure. On completion of two hours' 
 evaporating, if the level of the water in the boilers is at the required 
 height, the engineer will blow down evaporator, that is, the vapour 
 
70 '* Verbal *' Notes and Sketches 
 
 valve and feed pump will be shut off, and a pressure raised on 
 evaporator, the blow-down cock opened and evaporator blown out. 
 This operation is necessary to reduce the density of the water. After 
 blowing down, the evaporator is refilled to the required height with 
 water, and left ready for the next watch. The thermometer on the 
 feed pump, which is drawing from the feed heater, should be examined 
 to see that temperature is being maintained, and that feed heater is 
 working efficiently. Visits should be made to the stokehold and 
 fires examined, also to the bunkers to see that trimmers are working 
 the bunkers as directed. The tunnel should also be visited at least 
 twice each watch, if not every hour, and the solidified oil in 
 bearings renewed or pressed down on shaft. Attention should be 
 given to the pumping of the bilges in the engine-room and tunnel, 
 and mud box on bilge pump cleaned out during the watch. Tem- 
 peratures of the sea water passing to circulating pump and discharge 
 from condenser overboard should be taken and entered in the log, 
 also temperature of feed water, and engine-room temperature, steam 
 pressure on boilers, H.P. cylinder, LP. cylinder, L.P. cylinder, and 
 vacuum should be entered in log, length of times evaporator was 
 working, and height of water in main boilers. At one bell, that is, 
 quarter before the hour of being relieved, the engineer calls the next 
 watch, and is again below ready to take the counter when his four 
 hours are up. The counter is taken as eight bells strikes, and worked 
 out from the counter of the preceding watch, and average revolutions 
 entered in log book. The relief having gone round and passed the 
 word," All right," the engineer is free. 
 
 1 
 
 Economical Working:. 
 
 To obtain the best results from the engines and boilers the fol- 
 lowing points should be attended to : — 
 
 1. Keep grate surface as short as possible. 
 
 2. Work with stop and throttle valves well open, and expand by 
 link gear only. 
 
 3. See that the indicator cards show good compression curves. 
 
 4. If possible, balance up the power in each cylinder (allowing 
 extra power for engine driving pumps) by the link gear adjustment. 
 
 5. Keep pistons and valve faces tight. 
 
 I 
 
VIEW OF HOILER FRONT I'LATF, FURNACE, AND COMBUSTION. 
 (Under Cnn^tI•uctinn.) 
 
 \ erlial "' N<>les ami Sketches. 
 
 \To J\v-e page "i. 
 
SECTION II. 
 
 BOILERS. 
 
 Tensile Strength of Plates. — The tensile strength of steel shell 
 plates ranges from 28 tons to 32 tons per square inch ; if of higher 
 strength the metal is less ductile, and therefore less suitable for 
 flanging or for expansion under heat. The tensile strength of 
 combustion chamber and furnace plates ranges from 26 tons to 30 
 tons per square incii ; if over 30 tons the plates are too brittle. The 
 tensile strength is also known as the ultimate strength or breaking 
 stress of the material. 
 
 Elastic Limit and Safety Factor. — If a tensile stress of so many 
 tons is put on a test strip of steel the strip will become elongated, 
 and if the load is then taken off the metal will return to its original 
 length if the stress has been within the elastic limit ; if, however, 
 the stress has exceeded the elastic limit the metal remains elongated, 
 as " permanent set " or fracture has then taken place. 
 
 If, therefore, the elastic limit is found by testing a number of 
 strips the safe stress may be taken as equal to about half of this 
 limit, and from this the Factor of Safety may be determined. Steel 
 plates have an elastic limit ranging from 12 tons to about 14 tons 
 oer square inch. 
 
 Example. — If \2% tons per square inch is found to be within 
 ihe elastic limit of a steel plate, and assuming half of this as the 
 "afe working stress, determine the Factor of Safety, the tensile 
 strength being 28 tons per square inch. 
 
 Then, l2-S-r2 = 6-2S tons safe stress. 
 
 And, Factor of Safety = 28-^6-25 -4-4. 
 
 NOTE. — The Factor of Safety for boiler shells varies from 4-4 to 4*6 according; 
 to conditions of construction. 
 
 Stresses on Shell Seams. 
 
 In cylindrical boiler shells the stress set up by the pressure on 
 the longitudinal joints is equal to twice the stress on the circum- 
 
72 
 
 '' Verbal " Notes and Sketches 
 
 ferential joints : this is due to the difference in the end sectional area 
 and side sectional area of the shell acted on by the pressure. 
 
 Circumferential Stress. 
 
 Rule — 
 
 Boiler end area x Pressure 
 
 Boiler circumference x Thickness 
 
 Longitudinal Stress. 
 
 : Stress per square inch. 
 
 Rule — 
 
 Diameter X Pressure ^gtress per square inch. 
 Thickness x 2 
 
 Graphic Method of Proof for Shell Stresses. 
 
 1 -^ 
 
 • ill > 
 
 No. I.— Circumferential Shell Stress. 
 
 The pressure per square inch exerts a force acting from the centre 
 on opposite sides of the diameter, and therefore on two thicknesses 
 of the plate : this produces the stress per square inch longitudinally. 
 The pressure per square inch also exerts a force on the boiler end area, 
 throwing a tensile stress on the shell plate circumferentially, which 
 
Boilers 
 
 7Z 
 
 produces the stress in that direction ; if, then, the end area is calcu- 
 lated and multiplied by the pressure the result will be the total load 
 blovvint:^ out the boiler end, and therefore resisted by the strength of 
 the shell plate thickness circumferentially 
 
 Example. — Determine the stress per square inch longitudinally 
 and circumferentially on the shell of a boiler 15' diameter, i^" 
 thick, pressure 200 lbs. per square inch. 
 
 Longitudinal stress - 
 
 Diameter x Pressure 
 
 Circumferential\ 
 stress / 
 
 Thiclcness x 2 
 Boiler area x Pressure 
 
 180 X 200 .. 
 
 : = 12000 lbs. per sq. in. 
 
 1.5x2 
 
 180- X -7854 X 200 _ 
 
 Boiler circum. x Thickness 180 x 3-1416 x 1-5 
 
 6000 lbs. per sq. in 
 
 NOTE.-isft.-i8oin.; also observe that, 'f°^^^t''^°°=-°-''^-=6ooo lbs. 
 
 180 x 3-1416 X 1-5 4x1-5 
 So that the circumferential stress may be expressed thus— 
 
 Circumferential stress =;5!55^t?L^iPl?55HI?:. lbs. per sq. in. 
 4 X Thickness 
 
 Graphic Method of Proof for Shell Stresses. 
 
 -S 
 
 wwwwwv^^ 
 
 ^ 
 
 ESS^SS^SS 
 
 vN\\\V\\\\\\^ 
 
 -xvvvv 
 
 ^ 
 
 No. 2.— Longitudinal Shell Stress. 
 
74 *' Verbal " Notes and Sketches 
 
 It should be carefully noted that the longitudinal pressure exerts 
 a stress on the metal ciraDiifcrcntially, also that the radial pressure 
 exerts a stress on the metal longitudinally. 
 
 Observe that on two thicknesses of the shell metal circumferentially 
 (Sketches Nos. i and 2) (each i inch wide) the pressure acts on the 
 two areas B 1^ to produce stress, whereas on two thicknesses of shell 
 metal longitudinally (each i inch wide) the pressure acts on the two 
 areas C C ; these latter areas are therefore equal to twice B B, so 
 that the stress longitudinally is twice that circumferentially, as pre- 
 viously stated. The dotted lines on C C show areas B B which are 
 exactly half 
 
 NOTE. — The Board of Trade require the centre circumferential shell seams to be 
 equal to 65 per cent. , and the end circumferential shell seams to be equal to 50 per cent, 
 of the solid plate, which allows of ample strength in this direction where the smaller 
 stress is exerted. 
 
 Strength of Shell. 
 
 The strength of a boiler shell depends, therefore, on the Diametev 
 and Thickness, and is independent of the Length. 
 
 Boiler shells do not require stays, as circles are self-supporting: 
 the reason for this is that the forces set up by the pressure are 
 balanced at all positions of the circumference, or are in equilibrium. 
 
 Boiler Shell Pressure, &c. — The general equation connecting the 
 Pressure, Diameter, and Thickness, &c., of boiler shells is as follows : — 
 
 28 X 2240 X T X 2 X Joint- Diameter x Factor of Safety x Safe pressure. 
 
 Where 28 tons =- tensile strength of steel plates. 
 ,, T — shell Thickness. 
 
 ,, Joint = smaller result of rivet and seam section strengths. 
 
 The Factor of Safety in modern boilers varies from about 44 to 
 46, and represents the fraction of safe working stress as compared to 
 breaking stress. The number 2 in the rule stands for two thicknesses 
 of shell in one diameter — one at either side. 
 
 To apply the above it should be remembered that if all of the 
 terms on one side are multiplied together and divided by all of the terms 
 except one of other side then the unknown term will be brought out. 
 
 Example i. — Determine the required Thickness of boiler shell 
 plate for a Pressure of 200 lbs., the Diameter being 15 feet, the 
 Factor of safety 4-4, and the Joint strength 86 per cent. 
 
 Then, 28 x 2240 x T x 2 x -86= 180 in. x 4-4 x 200. 
 
 Therefore, T=-„^^°''4i4^200 ^ ^ -^^ ^^ ^,, .^^ ^j^.^j^ 
 
 28 x 2240 X 2 x .86 -^ ■> - 
 
 NOTE.— iVs = -86, also 15 ft. = 180 in. Diameter. 
 
Df 
 Df 
 
 d 
 
 t. 
 Df 
 
 n 
 g 
 
 d. 
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 id 
 le 
 It 
 
 le 
 
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 ts 
 m 
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 J^lB ,(zsd 
 
No. 3.— Joining of Shell Plates and End Plates. 
 
 (With Dimensions.) 
 
 A. End View showing Scarfed Joints of End Plates riveted to Shell. 
 
 B. Longitudinal View showing Shell lapping over End Plate Joints (half 
 in section). 
 
 C. Plan showing Shell lapping over centre and top End Plates, which 
 are bevelled away to form only a single thickness. 
 
 NOTE.— Where two end plates overlap one is thinned down to form an unbroken 
 line with the other, so that the shell plate may overlap both and form a steam and 
 water tight joint. Without this arrangement a space would be left open where the 
 shell plate covers both end plates, and caulking up of the joint would not be possible. 
 
Boilers 75 
 
 Example 2. — Find the Safe Pressure suitable for a boiler shell 
 14 feet 6 inches Diameter, and i| inches thick ; Joint strength 85 per 
 cent., and Safety Factor 4-5. 
 
 Then, 28 x 2240 x 1-375 x 2 x -85 = 174 in. x 45 x Safe Pressure. 
 
 Therefore, Pressure^ ^ "^ 224 x 1.37 5 x 2 x -8 5 ^ ^3 ^^^ ^.^ j^^^j^ 
 
 174 M-5 ^ 
 
 NOTE. — In tlie foregoing- case the actual working pressure would probably be 
 taken as 185 lbs. per square inch. 
 
 Strength of Joints. 
 
 In modern cylindrical marine boilers the average strengths of 
 the various riveted joints are as follows : — 
 
 1. Longitudinal shell seams (D.B. straps, five rivets per pitch) = 85 per 
 
 cent, of solid plate. 
 
 2. Centre circumferential shell seams (treble riveted) = 65 per cent, of 
 
 solid plate. 
 
 3. End circumferential shell seams (double riveted) = 52 per cent, of 
 
 solid plate. 
 
 4. End plate horizontal seams (double riveted) = 54 per cent, of solid 
 
 plate. 
 
 5. Furnace and combustion chambers (double riveted) = 68 per cent. 
 
 of solid plate. 
 
 6. Furnace and combustion chambers (single riveted) = 54 per cent, of 
 
 solid plate. 
 
 Observe that with thin plates (furnaces and combustion chambers) 
 the joint strength for the same type of riveting is much higher than 
 with heavier plates, the strength of joint for similar riveting decreasing 
 with increase of plate thickness. 
 
 Riveting. 
 
 Internal parts of boilers are usually single riveted. 
 
 Circumferential seams and end plates are usually double riveted. 
 In long boilers the ^tv^/;'^ circumferential seams are treble riveted to 
 allow of the e.xtra stress caused by barrelling when under pressure. 
 
 Longitudinal shell seams are fitted with double butt straps, and 
 have three lines of rivets, every second rivet being omitted in the 
 outer row (five rivets in a pitch) : this is the strongest type of joint 
 made. 
 
 In boiler joints the distance from the edge of the rivet-hole to the 
 edge of the plate should be equal to one diameter of the rivet. There- 
 fore the width of lap for a single riveted joint would equal three 
 diameters of the rivet. 
 
 A joint with a great number of rivets gives a high rivet section 
 strength, but a low plate strength ; and a joint with very few rivets 
 gives a high plate section strength, but a low rivet strength. From 
 the above it follows that the best joint is that in which the rivet 
 
T^^-De&ii of Stay 
 ' ^kietJween. Centre A 
 
 F(^-93. 
 
 No. 4.— End View of Double Ended Boiler, half section. 
 
 (Messrs John Brown & Co. Ltd., Clydebank.) 
 The difference in the diameter of the furnace mouth and back will be noticed, the left half 
 view showing the front of the furnaces and the right half view of the back. , , • u v 1 
 
 Notice the small clearance space allowed between the combustion chambers (si inches), also 
 the bevelled joint of the combustion chamber bottom plates to the wrapper or side plates. 1 he 
 ^arious dimensions should be carefully studied by the reader. 
 
 [To/ict J-ase Ti. 
 
Boilers 75 
 
 Example 2. — Find the Safe Pressure suitable for a boiler shell 
 14 feet 6 inches Diameter, and ig inches thick ; Joint strength 85 per 
 cent., and Safety Factor 4-5. 
 
 Then, 28 x 2240 x 1-375 ^ 2 x -85 = 174 in. x 45 x Safe Pressure. 
 
 Therefore, Pressure- ^-i??4? ^ I-37 5 >: 2 x -8 5 ^ ^g j^^^ square inch. 
 
 NOTE.— In the foregoing case the actual working pressure would probably be 
 taken as 185 lbs. per square inch. 
 
 Strength of Joints. 
 
 In modern cylindrical marine boilers the average strengths of 
 the various riveted joints are as follows : — 
 
 1. Longitudinal shell seams (D.B. straps, five rivets per pitch) = 85 per 
 
 cent, of solid plate. 
 
 2. Centre circumferential shell seams (treble riveted) = 65 per cent, of 
 
 solid plate. 
 
 3. End circumferential shell seams (double riveted) ==52 per cent, of 
 
 solid plate. 
 
 4. End plate horizontal seams (double riveted) = 54 per cent, of solid 
 
 plate. 
 
 5. Furnace and combustion chambers (double riveted) = 6S per cent. 
 
 of solid plate. 
 
 6. Furnace and combustion chambers (single riveted) = 54 per cent, of 
 
 solid plate. 
 
 Observe that with thin plates (furnaces and combustion chambers) 
 the joint strength for the same type of riveting is much higher than 
 with heavier plates, the strength of joint for similar riveting decreasing 
 with increase of plate thickness. 
 
 Riveting. 
 
 Internal parts of boilers are usually single riveted. 
 
 Circumferential seams and end plates are usually double riveted. 
 In long boilers the centre circumferential seams are treble riveted to 
 allow of the extra stress caused by barrelling when under pressure. 
 
 Longitudinal shell seams are fitted with double butt straps, and 
 have three lines of rivets, every second rivet being omitted in the 
 outer row (five rivets in a pitch) : this is the strongest type of joint 
 made. 
 
 In boiler joints the distance from the edge of the rivet-hole to the 
 edge of the plate should be equal to one diameter of the rivet. There- 
 fore the width of lap for a single riveted joint would equal three 
 diameters of the rivet. 
 
 A joint with a great number of rivets gives a high rivet section 
 strength, but a low plate strength ; and a joint with very {q\y rivets 
 gives a liigh plate section strength, but a low rivet strength. F>om 
 the above it follows that the best joint is that in which the rivet 
 
1^ 
 
 "Verbal" Notes and Sketches 
 
 section and plate section strengths are about equal, hence the reason 
 for omitting every alternate rivet in the outer row in the usual type 
 of D.B. strap joint riveting. 
 
 In a lap joint and a single butt strap joint the rivets are in single 
 shear (see sketches). 
 
 Lq^) jomt. 
 
 Sin(^\e slva"|3 
 
 sm^U 
 
 
 Double hlrap 
 
 ^ ^ 
 
 .doubk( 
 alitor 
 
 No. 5. 
 
 A double butt strap joint has the rivets in double shear, which 
 increases the strength of the rivet section 1-875 times (see sketch). 
 
 To count the Number of rivets in a pitch (N) of a joint, take the 
 greatest pitch and count the complete number of rivets enclosed within 
 it. The result is taken as the Number of rivets in a pitch (see sketch). 
 
 No. 6.— Double Butt Strap Joint Type of Riveting (Five Rivets 
 
 in a Pitch). 
 
 Plate I fa inches thick; Straps | inch thick; Rivets lij inches diameter. Joint 
 
 strength, 84 per cent. 
 
 Observe that the shaded rivets and parts of rivets give the number 
 enclosed within the greatest pitch. 
 
 NOTE. — This type of joint and riveting is only employed on longitudinal shell 
 seams. 
 
 Seam Section Strength. 
 
 A piece of solid plate represents absolute strength, or 100 per 
 cent. ; if then rivet holes are drilled out, the metal is now less in 
 
Boilers 
 
 11 
 
 area and the strengtli will be under lOO per cent. To find the 
 strentjth, then, of the plate after the holes are made, and which is 
 called the " plate at seam strength." 
 
 :^ -Y- 
 
 p 
 
 Solid Plate. 
 
 >id^ 
 
 w - 
 
 ;id 
 
 - -P-d - > 
 
 P - - 
 
 Plate cut for Holes. 
 No. 7. 
 
 Solid Plate Per 
 
 plate left cent. 
 
 Then, as PxT : (P— <f)xT : : 100 : Seam strength compared with solid plate. 
 
 The thickness T appearing on both sides can be omitted altogether. 
 Therefore, (P=^><-^><i^=(Pzi^^><I00^Seam strength. 
 
 Notice that we have now one half rivet hole taken away at either end of the 
 pitch distance, or one rivet diameter in all, so that the solid metal section is 
 reduced by one rivet diameter in each pitch distance. Also notice that the 
 plate thickness T cancels out top and bottom. 
 
 Rivet Section Strength. 
 
 Rivets are fitted into the holes and closed up tight either by hydraulic or 
 hand riveting (depending on the position of the seam). The rivets thus placed 
 in position are intended to act as a substitute for the metal taken away. To 
 find the strength, then, of the rivet section as compared with the solid plate. 
 
 Solid Rivet section P- 
 Then, as PXT : tf-X.7854XNo. : : 100 : { ^^^'soHd^prate^*'""^^^ compared with 
 
 Or, 
 
 ri^X-78MXNo.Xioo^Ri^et section strength. 
 PxT ^ 
 
 Observe that the solid plate section for one pitch is equal to " pitch x 
 thickness," and that the rivet area section for one pitch is equal to " rivet 
 area x number of rivets in one pitch." 
 
 NOTE.— The foregoing assumes that the plate section and rivet section are of 
 equal strength, but in the case of steel plates and steel rivets the shearing strength 
 of the rivet section is to be taken as only 23 tons per square inch, and the tensile 
 streng^ of the plate 28 tons per square inch. Therefore the formula would then 
 read — 
 
 d^7A^No. X i00X23^R-^^t section strength. 
 P X T X 28 
 
 Again, if double butt straps are fitted, as in longitudinal shell joints, the 
 
 rivet section strength is doubled, as the rivets are now in " double shear," but 
 
78 ''Verbal" Notes and Sketches 
 
 as a margin of safety, 6| per cent, of this is deducted and the increase of 
 strength taken as only i"875 times that of single shear. 
 
 Joints and Riveting. 
 
 Single Riveted lap joints are employed in furnaces and combustion 
 chambers, the strength of joint varying from 50 to 55 per cent, of the solid plate. 
 Double Riveted lap joints are employed in boiler end plates and cir- 
 cumferential shell seams, the strength of joint varying from 50 to 54 per cent, 
 of the solid plate. 
 
 Treble Riveted lap joints are employed in the centre circumferential shell 
 seams of long boilers (double-ended type), the strength of joint varying from 
 60 to 65 per cent, of the solid plate. 
 
 Double Butt strap joints with five rivets in the greatest pitch are only 
 employed on the longitudinal shell seams, the strength of joint varying from 
 8^ to 86 per cent, of the solid plate. 
 
 NOTE. — The "joint" strength is always taken as the smaller of the "rivet 
 section," and the "plate section at seam" strength results, as the weaker section 
 limits the strength. This is shown in the various worked out examples winch 
 follow. 
 
 Types of Joints with Dimensions (suitable for Patches). 
 
 No. I (Sketch No. 8). Plate §" thick, single riveted lap joint to be apphed. 
 Then, Rivet diam.=i-2X\/T=i-2X\/-375=-734". say 75" diam. of rivet. 
 
 A • n- i. n-i. u loox Rivet diam. iooX-7S , «" ^^^ »ii" ^xt-r-u 
 
 Agam, Rivet Pitch= — ^-. = — '•'=i-oo , say iH pitch. 
 
 ^ 100— joint 100—55 J 1" t- 
 
 NOTE.— T=Plate thickness ; joint=55 per cent, for single riveting. The width 
 
 of lap=:-75X 3=2-25". 
 
 Required Pitch of Rivets for Equal Strength in Seam Section 
 and in Rivet Section. 
 
 For equal strength — 
 
 (1) P-:-^^ is to be equal to Rivet area XN^XC_>^23^ 
 ^ ' P ^ P X ^ X 28 
 
 (2) Cancel out P under the line on each side. 
 
 ^. ^ D ^ Rivet area X No. X C X 23 
 Then, P-d= -^ ^ -^g . 
 
 (3) Transpose and change over signs, minus to plus. 
 
 So that, P = ^^^tareay^No^^X23 _^ ^ 
 
 Example. — Find required pitch of rivets to give equal strength for seam 
 and rivet section in a double-riveted lap joint, the diameter of rivets being 
 i", and the plate thickness |". 
 
 NOTE.— C = I for lap joint. 
 
 C = 1-875 for D.B.S. joints. 
 
 Then P-I _ ILX 7854 X 2J<^3 
 
 ' p p X -625 X 28 ■ 
 
 Cancel out P on bottom line of each side. 
 
 Therefore, P - I = ^iX^^SJ X 2X^3 = 3.06". 
 
 -625 X 28 
 Transpose and change signs. 
 
 So that. P = '1^^ -7854 X 2 X^3 4. I" = 3.06, say 3". 
 
 -625 X 28 
 NOTE.— As the value of C is i for lap joints it may be omitted altogether 
 in the present calculation. 
 
Boilers 
 
 79 
 
 No. 8— Single Riveting. 
 
 (Furnace or Combustion Chamber.) 
 
 Diameter and Pitch of Rivets, &c. 
 
 Rule — 
 
 Rivet diameter = 1-2 X VT. 
 Therefore, Rivet diameter=i.2x \/-37S = i-2x •612=734 in., say f in. rivet 
 NOTE.— T = plate thickness. 
 
 Rule — 
 
 Rivet Pitch ='-?^^i5^^:?L^i?^!i?^. 
 
 100 -joint 
 
 Therefore, Pitch = ^-?^^i:75= 1.65 in., say lU in. 
 100-54 J ' .^ Iff 
 
 Rule — Distance from edge of plate to Rivet centre = Rivet 
 diameter X 1-5. 
 
 Therefore, -75 x 1-5 = 1^ in. 
 
 The width of lap is in this case equal to 
 
 1 1 in. x2 = 2j in. (single riveting). 
 
 NOTE.— The joint strength for single riveting with thin plates is taken as 
 about 54 per cent, of the solid plate. 
 
 To prove joint strength. 
 
 c«.o^ (p-</)xioo (1-6875 -•75)x 100 — - 
 
 Seam = 't^ — ^ = 1^6875 "" ^^'^ P®"" *^^"^ 
 
 Pivets -^ ^^ "7^54 ^ No. x 23 x 100 _ -75^ x -7854 x1x23 x100. 
 
 PxTx28 
 
 1. 6875 x. 375x28 
 
 57-3- 
 
 The joint strength is therefore equal to 55-5 per cent, of the 
 solid plate. 
 
8o ' ''Verbal" Notes and Sketches 
 
 No. 2 (Sketch No. 9). Plate ^ inch thick, single riveted lap joint. 
 
 Rivet diameter=i'2xVT = i-2x \/.5 = -848 in., say U in. Diameter of rivet. 
 
 Rivet Pitch = '°° ^ ^^^^^^ diameter ^ igo_^9375 ^ ^.Qg in., say 2,'« in. pitch, 
 loo-jomt 100-55 
 
 Width of Lap= •9375x3=2-8125 in. =212 in. 
 
 No. 9. — Single Riveting. 
 
 (Furnace or Combustion Chamber.) 
 
 Strength of Joint. 
 
 Seam=(Pi:^)^iigg = (^°^^5-;9375) x ^00^54.5 per cent. 
 
 tr 2* 002s 
 
 Rivetc - *^ ^ -7^54 x No. x 23 x 100 _ .9375^ x - 7854 x i x 23 x 100 _ ^^^^ 
 
 P X T X 28 ^^625 X .5 X 28 ^^^ ^ 
 
 Joint strength (smaller) -54-5 per cent, of solid plate. 
 Width of lap = •9375x3 = 2-8125 in., or 2]l in. 
 
 No. 3 (Sketch No. 10). Plate -^ inch thick, double riveted lap joint 
 (zig-zag). 
 
 Rivet diameter = i«2x VT = i-2x \/-5 = -848, say [f in. diameter of rivet. 
 
 Rivet Pitch = ^^ ^ ^^^^^ diameter ^ 100 X .9375^ .^^^ . 
 
 lOO-jomt 100-70 
 
 To prove strength of joint. 
 
 Plate at Seam^^l^?^ — ^tPx 100 = 70 per cent. 
 3125 
 
 Rivet Section = "9375^^ " 7854 ^ 100 x 2 x 23 ^ ^^^^^ 
 
 3-125 X 5x28 
 
Diameter an 
 
 NOTE.— In 
 Jg in. is fixed c 
 
 Cen^ 
 
 Distance be 
 
 Rule— ^ 
 
 NOTE.— T 
 
No. 10.— Double Riveting (Zig zag). 
 
 (Furnace or Combustion Diameter.) 
 
 Diameter and Pitch of Rivets, &c. 
 
 Diameter of Rivets-l-2x \/-5 = l'2 x '707 = -848 in., say J in., or |H in. 
 NOTE. — In certain cases it is advisable to make the rivet fully the size found by the rule. In this case 
 
 I the diameter. 
 
 Pitch ='°°'^"'^'* diameter^ ioo . n ls^^.^^c in., or 3J 
 
 lOO-JOUlt 100-70 J 3 ' J» 
 
 Centre of Rivet to edge of plate = Rivet diameter ;< i-5=9375i< i.s=i-4o625 in., or if, in. 
 Distance between rivet rows (V) (Zig-zag Riveting). 
 Rule — 
 
 y ^ \/(iixp + 4xd)x(p + 4xrf) _ \/(iix 3.125 + 4 X -9375) X (3-125 + 4 x-9375) _ 
 10 10 
 
 1. 61 in., say 1% in., between rivet rows. 
 NOTE.— The average strength of double riveted joints for thin plates=70 per cent, of solid plate. 
 
 \To/m-e page 8a 
 
Boilers 8i 
 
 The joint strength is therefore equal to 70 per cent, of the soHd 
 plate. 
 
 It should be remembered that the shearing strength of steel 
 rivets is only to be taken as 23 tons per square inch, whereas the 
 tensile strength of the steel plate is taken as 28 tons per square inch. 
 
 The distance between the rows of rivets can be calculated as 
 
 follows : — 
 
 ^. , . T^ .L n / u • • i- \ 4 X diameter of rivet + 1 
 Distance between Rivet Rows (chain riveting) = ^1 — = 
 
 4Ji:9375±i^ 3-7500+ 1 ^2-375 in- (^ i"-)- 
 2 2 
 
 Distance between Rivet Rows (zig-zag riveting) = 
 
 V(ii X pitch + 4 X Rivet diameter) x (pitch + 4 > Rivet diameter) _ 
 
 10 
 
 V(ii X 3-125+4 X .9375) X (3-125 + 4 X -9375) _ 
 10 
 
 V(34-375 + 37-5) ^ (3- 125 +375) - 
 10 
 
 \/38-i25x 6-875 - 
 10 
 
 \/262- 1 09375 _ 
 10 
 
 ^^^=i'6ig in., say li in. 
 10 
 
 No. II.— Double Riveting (Chain). 
 
 (Furnace or Combustion Chamber.) 
 
 In all cases the distance from edge of plate to centre of rivet = 
 Rivet diameter X 1-5. 
 
 Therefore, \t in. x 1-5=1-406 in., say i^V in. 
 6 
 
Boilers 8 1 
 
 The joint strength is therefore equal to 70 per cent, of the soHd 
 plate. 
 
 It should be remembered that the shearing strength of steel 
 rivets is only to be taken as 23 tons per square inch, whereas the 
 tensile strength of the steel plate is taken as 28 tons per square inch. 
 
 The distance between the rows of rivets can be calculated as 
 
 follows : — 
 
 ^. , , T^- i T-i , u ■ ■ L- \ 4 X diameter of rivet + i 
 Distance between Rivet Rows (chain nveting)^^ = 
 
 4j^375±i^3-7500+ 1^2.3^5 in. (2i in.). 
 2 2 
 
 Distance between Rivet Rows (zigzag riveting) = 
 
 \^(ii X pitch + 4 < Rivet diameter) x (pitch + 4 x Rivet diameter) _ 
 10 
 
 Vdi X 3-125 + 4 X .9375) X (3-125 + 4 X -9375) . 
 10 
 
 V(34~375 + 37-5) >= (3- 125 + 375) _ 
 
 \/38-i25x 6-875 - 
 10 
 
 \/262- 109375 _ 
 ID 
 
 ^^^=v6iQ in., say if in. 
 10 
 
 No. II.— Double Riveting (Chain). 
 
 (Furnace or Combustion Chamber.) 
 
 In all cases the distance from edge of plate to centre of rivet = 
 Rivet diameter X 1-5. 
 
 Therefore, 1^ in. x 1-5 -1-406 in., say i^g in. 
 6 
 
82 
 
 *' Verbal " Notes and Sketches 
 
 Joint strength (Sketch No. ii). 
 
 P 3125 ' ^ 
 
 Rivets = '^^ " 7854 xNo^xgjj^joo^ -9375^ x -7854 x 2 x 23 x loo^y^ ^,„t 
 
 PxTx28 3125 X -5x28 
 
 Joint strength =70 per cent, of solid plate. 
 
 Distance between Rivet Rows (V) (chain riveting). 
 Rule — 
 
 V^4xd+i^4x9375 + i^2-375 in., or 2^ in. 
 
 No. 4 (Sketch No. 12). Plate f inch thick, double riveted lap joint 
 (zig-zag). 
 
 Rive diameter = 1-2 X v'T — i'2x \/-625 — -948 in., say i in., diameter. 
 
 Rivet Pitch ^ 
 
 100 X Rivet diameter 100 x i 
 
 = 3-03 in., say 3yV in. pitch. 
 
 100 -joint 100-67 
 
 NOTE. — Take 67 per cent, as average strength of double riveted joints. 
 
 No. i± — Double Riveting (Zig-zag). 
 
 (Furnace or Combustion Chamber.) 
 Joint strength. 
 
 Seam---(g^^)^iigg = (3:g625,- I) x loo^^ ^^„^ 
 
 P 30625 ' ^ ^ 
 
 Rivets^^' ^ -7854 x 2 x 23 x 100^ i^ x .7854 x 2 x 23 ^100^67-4 per cent. 
 P X T X 28 3-0625 X -625 X 28 
 
 Joint strength (smaller) = 67-3 per cent, of solid plate. 
 
 NOTE.— As the plate thickness increases the joint strength of single and 
 double riveting decreases. 
 
i s 
 
 g ^ 5 
 
 i- Set 
 
 II .s > 
 
 o O 
 
 to a> 
 
 n 1) 
 
 5 S 
 
 Z ii 
 
 Q 
 
 ^>: 
 
 
 + 
 
 s J 
 
 0.1 W 
 
 
 
 
 
 a + 
 
 ■o 
 
 •c ? 
 
 
 
 
 
 X a 
 
 C X 
 
 
 "* + 
 
 ■^ ^ 
 
 c * 
 
 > 
 
 £ - 
 
 
 5 - 
 
 > 
 
 « 1 ', 
 
 §^ 
 
 & s 
 
 i^'=.§ 
 
 S 2 
 
 if 
 
 £5 
 
Boilers 83 
 
 Distance between Rivet Rows (V) (Zig-zag Riveting). 
 Rule— 
 
 y^ \/(iix p + 4x d)x(p + 4xc/") _ 
 
 10 
 
 \ (11 X 3-0625 + 4 X I) X (3.0625 + 4 X I) , ^„ • ,, ■ , , 
 
 — ^ ^ 5 — 5 i — !2 2 — 5 -' = i-63 in., say j\}, in. between 
 
 10 
 
 Rivet centre to edge of plate = 1 x i-5=:ii in. 
 
 To prove strength of joint. 
 
 Plate at Seam-?^ — ?5J:Li x loo = 67 per cent. 
 30625 
 
 Rivet Section^^'Jiig54x 100x23x2^ ^^^^^ 
 
 3-0625 X .625 X 28 
 
 The width of lap can, if required, be calculated by the method 
 shown in example No. 3. 
 
 Distance from centre of rivet to edge of plate = 1 inch x 1-5 = 1-5 inches. 
 
 No. 5. Double Butt Strap Joints (Sketch No. 13). — As before 
 stated, this type of joint is only fitted in the longitudinal shell seams 
 of boilers. 
 
 Shell plate ij inches thick, joint strength to be taken as 85 per 
 cent. 
 
 Then, 
 
 Rivet diameter = I -2 x \/T = 1-2 x s/i-25 = i'32 in., say i§ in. diameter. 
 
 Rivet Pitch=^°°" ^^^^^.^^'"^^^'•^^""^ ^-375^9.16 in., say pi in. pitch. 
 100 -joint 100-85 ^ ' J ^* r 
 
 To prove strength of joint. ♦ 
 
 Plate at Seam = ^'^5~ ^'375x 100 = 85 per cent 
 925 
 
 Rivet Section = i:3752l78S4il23x5iii:875iLioo^ g ^^^^ 
 925 X 1-25 X 28 
 
 Referring to Sketch No. 13, the joint strength or smaller result is 
 therefore equal to 85 per cent, of the solid plate. 
 
 It will be noticed that in this type of joint the rivets are unequally 
 distributed, the outer row having every second rivet omitted. The 
 
*.<•'/ 
 M',' 
 
Boilers 
 
 Distance between Rivet Rows (V) (Zig-zag Riveting). 
 Rule— 
 
 y_ V(iixp + 4xc/)x(p + 4xd) _ 
 
 10 
 
 n'(ii X3-0625 + 4X i)x(3.o62S + 4x I) , ^„ ■ ,, . , . 
 
 — ! ^ 2 — 1 '. — ^2 2 — 3 -' = 103 in., say i{,\ in. between 
 
 10 ~> J I 
 
 Rivet centre to edge of plate — i x i-5==ii^ in. 
 
 To prove strength of joint. 
 
 Plate at Seam-?^ — ?pSllx 100 =67 per cent. 
 30625 
 
 Rivet Section ^ ^!^7f 54 =< 100 x 23 x 2 ^ ^^^^^ 
 
 3-0625 X -625 x 28 
 
 The width of lap can, if required, be calculated by the method 
 shown in example No. 3. 
 
 Distance from centre of rivet to edge of plate = 1 inch x 1-5 = 1-5 inches. 
 
 No. 5. Double Butt Strap Joints (Sketch No. 13).— As before 
 stated, this type of joint is only fitted in the longitudinal shell seams 
 of boilers. 
 
 Shell plate ij inches thick, joint strength to be taken as 85 per 
 cent. 
 
 Then, 
 
 Rivet diameter = 1-2 X \/T=^ 1-2 X v''i-25=i-32 in., say if in. diameter. 
 
 Rivet Pitch^ ^°° " ^^^\ diameter^ 100 X2:37g^g.x6 i„., say 9^ in. pitch, 
 loo-jomt 100-85 ' ■' ^ ^ 
 
 To prove strength of joint. ♦ 
 
 Plate at Seam = ^'^5~ ^'STS y 100 = 85 P^r cent 
 925 
 
 Rivet Section^^-375''" •7854x23x5x1-875x100^ 6 per cent. 
 9-25x1-25x28 
 
 Referring to Sketch No. 13, the joint strength or smaller result is 
 therefore equal to 85 per cent, of the solid plate. 
 
 It will be noticed that in this type of joint the rivets are unequally 
 distributed, the outer row having every .second rivet omitted. The 
 
84 "Verbal" Notes and Sketches 
 
 omission of these rivets has the efTfect of raisinc^ up the joint strength, 
 for, were the rivet included, we should then have a very strong rivet 
 section strength, but a very weak plate section strength, and, as the 
 smaller section strength must in all cases be taken as \\\(t joint strength, 
 the joint would be weak. By omitting every second rivet in the outer 
 row the rivet section strength is decreased, and the plate section 
 increased ; therefore the smaller result being now higher than before, 
 the joint strength is proportionally greater. 
 
 There is no benefit to be got by having a high rivet section 
 strength, and a low plate section strength, as the smaller or joint 
 strength governs the safe working pressure to be allowed on the 
 plates. 
 
 The result on the joint strength by giving equal rivets in each row 
 will now be shown. 
 
 Observe that the greatest (only) pitch is now 4§ inches, and that 
 the number of rivets included in one pitch is tJirce instead of five as 
 previously. 
 
 Therefore, Plate at seam= ^^ ^^7 ^'^^^ x ioo=70'2 per cent. 
 
 4-625 
 
 o- J. I.- i-'i7>;^x •78'^x2'?x 'sx I-87SX 100 o i. 
 
 Rivet section = -^?^^ '-^ — J — ^ — ^lA — rr = ii8 per cent. 
 
 4-625 XI.2SX 28 
 
 1. As shown above, the joint strength has dropped from 85 per 
 cent, to 70-2 per cent., which proves that the omission of every 
 alternate rivet in the outer row as actually carried out in practice has 
 the effect of raising up the joint strength to a maximum. 
 
 2. The rivet section strength is increased from 97-6 per cent, 
 to 118 per cent., but, as the smaller result only must always be 
 taken, this simply represents rivet section strength wasted. The re- 
 adjustment of rivet section with every second rivet omitted in the 
 outer row takes away from the rivet section and gives to the plate 
 section, or, what the rivet section loses the plate section gains, and the 
 joint strength is proportionately increased. 
 
 Circumferential Riveting (Sketch No. 14). 
 
 Seam strength :^ <P - '^^^ ^°o^ (3-5 - i -375^1100 ^60 7 per cent. 
 
 Rivet strength^*^ " '^Sg x No. < 23 x 100^ 1-375^ x .7854 > 2 23 x 100^ 
 
 ^ PxTx28 35x1.25x28 ^^ I V 
 
 NOTE. — The shell plates are i\ in. thick. 
 
 Joint strength =^557 per cent, of solid plate. 
 
I 
 
 Boilers 
 
 85 
 
 This is sufficient for the end seams, which according to Board of Trade 
 requirements must not be less in strength than half that of the longitudinal 
 seams, which in this case is exceeded by a fair margin. 
 
 Distance between Rivet Rows (V). 
 
 y_ V(ii x p + 4xd)x(p-j-4^d)_ 
 
 10 
 
 "^(ii X 3-5 + 4 X 1-375) X (3.5 + 4 X I- wi:) 
 
 — 5^ .J^J_5 j/o^ — \^ jT^t — * ■3/3^ = 1.99 in» say 2 m. 
 
 Distance from rivet centre to edge of plate- 1-5 xi'375 = 2-o625 in., or 2jV in. 
 
 SHELL PLATE 
 
 i 
 
 000 Q)---Qy-- 
 
 0000 Q)--<y 
 
 BUTT. STRAP 
 
 A 
 
 ^.^^k^lB RIVETS ^^ 
 (JT (FINISHED)-^ 
 
 -9i"-— H 
 
 No. 14,— End Circumferential and Longitudinal Shell Riveting. 
 
 Observe that there are five rivets in a pitch (sectioned black) longitudin- 
 ally, and two rivets in a pitch circumferentially. 
 
 For working out of longitudinal shell riveting see Sketch No. 13. 
 
86 "Verbal" Notes and Sketches 
 
 Combined Strength of Seam and Rivets. 
 
 In double butt strap joints the combined strength of seam and 
 rivets exceeds that of either the seam strength or rivet section 
 strength, as can easily be proved by the following rule. It should 
 be noted that at the outer rivet rows one rivet section is taken out 
 of the plate metal at the large pitch (see No. 13), whereas at the 
 inner rivet rows two rivet sections are cut out of the same pitch 
 length : the seam section is therefore weakest at the inner rows, 
 
 as the formula would then be, - — >-^ ^instead of-^— - — as for the 
 
 outer row : but as a counterbalance to this it should be noted that 
 before the plate between the inner rivet rows would fracture, one rivet 
 section of the outer row would also require to be sheared, so that we 
 have the shearing strength of one rivet added to the plate strength 
 at seam. To obtain the strength of one single rivet, merely divide 
 the rivet section strength as found in the usual way by the number 
 of rivets in a pitch, which, as in the case of double butt strap joints, 
 is five. 
 
 Therefore, Combined strength^P " <g^ ^^ x 100+ g^^^^ ^^'^^^°" ^^'•^"g^\ 
 
 As this result is in every case in excess of either rivet or seam 
 section strengths, it follows that it is correct to take the smaller 
 of the latter two as the joint strength, which is always done in actual j 
 practice. 
 
 Example. — Work out the combined strength of rivet and seam 
 section for the riveting shown in Sketch No. 13. 
 
 Combined strength = 9'^5 - (i - JlSjlj) x 100+ SHA.^ 
 925 5 
 
 925 - 2-75 ^ 100 4.20.5 = 89-8 per cent. 
 925 
 
 So that the results come out as follows : — 
 
 r Seam Section = 85-1 per cent, of solid plate (joint). 
 
 Strengths \ Rivet ,, = 97-6 „ „ 
 
 ( Combined ,, = 898 ,, „ 
 
 Notice that the joint is equal to the smallest result of the three. 
 
c 
 
 '<^//////////ff 
 
I8RIVETS 
 
 (finished) 
 
 o 
 o 
 
 «- - - 
 
 o 
 
 O* 1 8 BIVET^CJ 
 FINISHED 
 
 d^-O ooooooooooo 
 
 .tOOOOOOJOOOOOOO 
 
 ^<J^ >! 
 
 r^ooooo?'oooo(i« 
 
 .:^--o O O O O (p O O (D ,„0 i • J 
 
 iO O O ; O O d * ^ 
 
 No. 15.— Longitudinal, End Circumferential, and Centre Circumferential Riveting. 
 
 NOTE.— The limit rivet pitch allowed by the Board of Trade is loi inches. The darkened rivets indicate the number 
 in a pitch for each joint shown. 
 
 Joint Strengths, &c. Longitudinal Shell Seams (plate ij inches thick). 
 Seam strength = l£:J')H°? = ii°:37Sri:feSllioo_ ^^^ 
 
 • ^ P 1037s 
 
 Rivet strength 
 
 . iPx-7 854 xNo. X 23x1.875x100 ^ 1-625- X - 7854 >< 5 ■< 23 X 1-8 7 5 >■ '"o ^ 
 ■ PxTx28 10-375 >; 1-625 X 28 
 
 Joint strength (smaller) = 84.3 per cent, of solid plate. 
 
 It will be obvious that the joint strength would be improved by reducing the rivet section strength, as this would result 
 in raising the seam section strength and therefore the joint strength. 
 
 NOTE. — In this example the rivet diameter and plate thickness are of the same size. • 
 
 Distance between Outer Rivet Rows (V). 
 
 Distance between Inner Rivet Rows (V,). 
 
 y_ V(iixp + 8xd)x(p + 8xd) _ N/(iix 10-375 + 8x1.625) X (10-375 + 8 xi.6 25)._^,y m., say zH in. 
 
 Rivet centre to edge of plate = 
 
 Circumferential End Shell Seams. 
 
 [-5 1.625=2.4375 in., or 2,'i in. 
 
 Seam section^'^ - ''^^ "" = '3-875 - 1-625) -^=^8 per cent. 
 P 3-875 ' ^ 
 
 Rivet section ^gl-:734>' No. X 23 V 
 
 P X T X 28 
 
 [ 625- X .7854 X 2 X 23 X 100 ^ 
 
 3.875x1.625x28 
 
 = 54'i per cent. 
 Joint strength (smaller) =54-1 per cent, of solid strength. 
 
 Circumferential Centre Shell Seams. — The Board of Trade limit strength for this joint is 65 per cent., which 
 
 usually necessitates three rivets in a pitch ; this additional strength is required to meet the barrelling tendency of 
 
 the boiler under pressure, as the centre seams, unlike the end seams, are unsupported, whereas the end seams are stayed 
 by the boiler end plates. 
 
 Seam section = 'i^-IH? = UiMl-I^li?? . 65 per cent, (nearly). 
 
 Rivet section = "' " •7S 54.lNo^_ 23 x 100 i;625^7854 ■< 3 x 23-< i°o ^ ^8 per cent, (nearly). 
 PxTx28 4.625x1-625x28 '^ " 
 
 Distance between Rivet Rows (V). 
 
 y_ v'(iixp74:^ri)"x(7i + 4xd| _ V(iIx4-62S + 4xi-62S)x.(4.625 + 4xi.625) _y^ I 
 
 ITofaci fasi 86. 
 
Boilers 
 
 87 
 
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88 
 
 "Verbal" Notes and Sketches 
 
 CAULKED 
 
 No. 17.— Machine Riveting. 
 
 (With Dimensions.) 
 
 The dimensions should be carefully studied 
 and compared. 
 
 CAULKED 
 
 No. 18. — Riveting and Caulking of Combustion Chamber Top. 
 
 (With Dimensions.) 
 
 Hand riveting is usually as shown, that is, the rivet is counter- 
 sunk on one side, and snap or flat headed on the other side. 
 Compare the plate thickness and rivet diameter, &:c. 
 
Boilers 
 JOINT r-l'sTRAP 
 
 89 
 
 It" 
 rli PLATE 
 
 No. 19.— Shell Plates and Butt Straps. 
 
 This view, a fore and aft section, of the shell shows clearly 
 how the butt straps sit in position. 
 
 To find Butt Strap Thickness. — Rivets i§ inches diameter, pitch 
 9 inches. 
 
 Rule — 
 
 Thickness^ I ^ J-^j^^l = g ^ ^'^^ x (9 - i-375)^ ^ inch thick. 
 8x(p-(c/x2)) 8 X (9 -(1.375x2)) 
 
 No. 20.— View of Boiler End near Top. 
 
 (Showing Riveting of Tube Plate and Top End Plate.) 
 
 Joint strength. 
 
 Seam Section=''^— -x 100= ^' ^~ ^ x 100 = 60-2 per cent. 
 P 3-25 
 
 Rivet Section^-^J^ 1,^°° I ^3^ i^ x -7854 x 2 x 100 x 23^ g per cent. 
 
 P X T X 28 325 X .78 X 28 ^ f 
 
 The joint strength is, therefore, 50-8 per cent, of the solid plate 
 
 7 
 
90 
 
 " Verbal " Notes and Sketches 
 
 Distance between Rivet Rows. 
 
 Rule — 
 
 \/(ii X p + 4xd)x(p + 4x"ri) _ \/(iix 3-25 + 4 X I) X (3-25 + 4 xi) _^ in., say if 
 
 10 
 
 10 
 
 Distance between edge of hole and edge of plate- 
 
 RULE — 
 
 </x 1-5-1 X i-5 = i'5 in. 
 
 r 132^ 132 r l32 ^ 
 
 No. 21.— Shell Plate Machine Riveting. 
 
 This sketch shows the shell plate and the two butt straps 
 in section with the rivet in position ; the dimensions are marked, 
 and should be noted. 
 
 No. 22.— Hand Riveting. 
 
 (Countersunk.) 
 
 The dimensions indicate the proportions of countersink, &c. 
 adopted in hand riveting as employed in patching. 
 
Boilers 
 
 91 
 
 No. 23.— Caulking Tool for Boiler Plates. 
 
 The tool is shown in position for caulking a thick plate. 
 
 No. 24— Diagonal Pitch of Rivets. 
 
 For the type of joint shown above the diagonal pitch of the 
 rivets should not be less than that found by the following rule. 
 
 Rule — 
 
 Diagonal Pitch^3x Pitch + 4 x diameter 
 10 
 
 Therefore, Diagonal Pitch = ?^i?l-5 — 4iLL375_ 2.326 in., or say 3^^ in. 
 
 Steam Space Stays. 
 
 These steel stays range in diameter from 2| to 3J inches diameter, 
 with a normal pitch of 16 inches for pressures of from 160 to 210 lbs. 
 per square inch. The stays are secured to the plates by one of the 
 following methods. 
 
 1. Holes cut in both plates and stays held in place by nuts and 
 washers both inside and outside the plate at either end. 
 
 2. Stays screwed through both end plates and fitted with single 
 nuts and washers on outside of plates only. 
 
 3. Holes cut in both end plates and stays held in place by means 
 of a thin nut inside and a thick nut outside. 
 
 Occasionally the nuts are bevelled off as shown in the sketch, and 
 
92 
 
 " Verbal " Notes and Sketches 
 
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Boilers 
 
 93 
 
 a layer of mastic cement filled in as a joint : in addition to this a 
 servinj^ of mastic cement is placed between the nut and washer, and 
 between the washer and plate for tiie same purpose. 
 
 In the case of No. i arrangement, the outside washers are some- 
 times riveted to the plates and are then made of a diameter equal 
 to three times that of the stay at thread. The stays are during 
 manufacture staved up | or h inch at the ends (the stay being after- 
 wards annealed) to allow of the cutting of the screw, which at bottom 
 of thread should not be less in diameter than the body of the stay. 
 Under working conditions these stays are subjected to a tensile stress, 
 and should therefore be made out of the solid, as, if welded, the 
 stress conditions mentioned would tend to open up the welded portion 
 of the stay. The usual number of screw threads cut in the stay ends 
 is from 6 to 8 per inch. These stays occasionally show signs of 
 corrosion at or near the ends, the cause of which is most likely mag- 
 nesium chloride gas contained in sea water feed and set free by the 
 effects of heat. 
 
 When the stays are screwed into the plates, the plates are 
 afterwards caulked round the stays to ensure tightness of joint. 
 
 ' -1" ' 
 
 ^25^ 
 
 <■ 
 
 3$" SCREW. 3" SCREW. 
 
 8 THREADS PER INCH. 
 
 1/N 
 
 Then, 
 
 No. 26. — Steam Space Stay. 
 
 (Pressure, 200 lbs. Pitch, 16 inches.) 
 
 Stay diameter at smallest part = 2| inches. 
 
 275 - 7 54 • 9000 -208 lbs. safe pressure. 
 16x16 
 
 Observe that the stay being screwed into the plates is larger 
 in diameter at one end than the other, the screwed portions 
 being 3^ inches diameter and 3 inches diameter. 
 
 The plates are carefully caulked round the stay at both ends 
 and a touch of lead putty put on the nuts before screwing up 
 tight. 
 
 NOTE.— The depth of nut plus plate thickness is equal to the diameter of stay 
 over threads, or 2| inches + 1 inch-3i inches. 
 
94 
 
 *' Verbal " Notes and Sketches 
 
 16 SPACE 
 UP WITH JOINTING 
 MATERIAL 
 
 8 THREADS PER INCH 
 3ir" D"^ OVER THREADS. 
 3 g^' DIA BOTTOM OF THREAD 
 
 CO 
 
 NUT RECESSED 
 FOR JOINTING 
 MATERIAL 
 
 No. 27.— Steam Space Stay. 
 
 (With Dimensions.) 
 (Pressure, 220 lbs. Pitch, 17 inches. 
 
 In this type of stay, the holes in the end plates are cut clear, 
 and nuts are screwed on the stay ends inside and outside, the 
 ends being staved up for the cutting of the screws (plus thread) 
 Mastic cement or lead putty is filled into the clearance (^V inch). 
 
 NOTE.— If no washers are fitted on the nuts the depth of the outside nut must 
 be increased to make up. 
 
Boilers 95 
 
 I 
 
 Flat Surfaces and Stays. 
 
 The flat (or nearly flat) surfaces of boilers are stayed as follows : — 
 
 1. Boiler end plates, by large stays in steam and water spaces. 
 
 2. C^ombustion chamber sides and backs, by small screwed stays. 
 
 3. „ „ tops, by girders and stays. 
 
 4. ,, „ bottoms are self-staying, being semicircular. 
 
 5. End plates between tube nests, by doubling plates riveted on. 
 
 The strength of flat surfaces vary as the Surface supported (pitch 
 of stays squared) and the Thickness of plate squared : this can be 
 seen by examining the Rule, which is as follows : — 
 
 Rule— • 
 
 C X (T + 1)- = (S - 6) X Safe Pressure. 
 
 C = ioo to 168, depending on conditions of construction. 
 
 T = Plate Thickness in sixteenths. 
 
 S = Surface supported (usually Pitch squared). 
 
 NOTE.— In ordinary practice C may be taken as 100 for combustion chamber 
 plates, and 150 for boiler end plates. 
 
 If, then, the constants C,6 and i are deleted, we have left T- and 
 S, therefore the strength varies as these two terms. 
 
 To Transpose the Rule— 
 
 The following shows how the rule may be transposed to find either 
 the Safe Pressure, the plate Thickness, or the Pitch of stays. 
 
 I. Safe Pressure = ?iilTi:il'= lbs. 
 S -0 
 
 2. Surface supported = ^— ^ —V, ^ + 6 ^ S . 
 Safe Pressure 
 
 Then, Pitch ^VS^ 
 
 Notice that the square root of the surface supported is equal to the 
 pitch of stays required. 
 
 3. Thickness of Plate= /'II?5^5£?f?H^=(T + i). 
 
 Then, (T + i)-i-T (in sixteenths). 
 
 Observe that the result brought out by the square root is T+ i, that 
 is one more than T, therefore i requires to be subtracted to obtain T 
 (in sixteenths of an inch). 
 
96 " Verbal " Notes and Sketches 
 
 Data for End Plates and Stays (Sketch No. 27). — The safe 
 working pressure is 220 lbs. per square inch, and the pitch of stays 
 17 inches; find the required thickness of end plate if the Constant 
 is 168 : also find the required diameter of stay. 
 
 Plate Thickness. 
 
 Rule — 
 
 Cx(T + i)-=(S-6)xSafe Pressure. 
 Where, C = Constant, T = i6th in plate, S- Surface supported or Pitch-. 
 Then, i68x(T+i)"=(i7--6) x22o. 
 
 Therefore, T.^/&^r^-^ = ^^^^-^^.^■^6. 
 
 So that, I^^ic\' in. thick. 
 
 16 
 
 Observe that the result comes out in sixteeyitJis of an inch, therefore 
 18-26 sixteenths is equal to i/y inch. 
 
 Stay Diameter. 
 
 Rule — 
 
 Surface X Safe Pressure = Stay area x 9000. 
 Then, 17- x 220= Stay area x 9000. 
 
 Therefore, 
 
 17- X 220 ^**^ J"^ J /stay area 
 
 -i- -7-064, and. / 7.064 • - T^- i. r i. 
 
 9000 Sj — -Q— '- = 2-99 in., say 3 in., Diameter of stay. 
 
 Water Space Stays. 
 
 The combustion chamber stays usually range in diameter from 
 about i^ to if inches, with a pitch of from 7^ to 8i inches. These 
 stays are screwed through the plates to be supported, and are 
 secured by means of two nuts in all, one outside the boiler and the 
 other inside the combustion chamber, the stay ends being riveted 
 over the nuts. The plate is usually caulked round the stay to keep 
 the joint tight. Occasionally the outside end of the stay is riveted 
 over only, and the plate caulked round the stays (see sketch). These 
 stays are, under ordinary conditions, subject to a tensile stress, 
 but this is usually augmented by a bending stress produced by the 
 floating tendency of the combustion chamber, which, it will be 
 observed, is a hollow chamber immersed in water. This lifting 
 tendency strains the stays often to the point of fracture, and in 
 consequence permitting corrosion to take place at a more rapid rate. 
 
Boilers 
 
 97 
 
 No. 28. — Combustion Chamber Stays- 
 
 These stays are of steel, and are allowed a working tensile 
 stress of 9000 lbs. per square inch. The plates are tapped 
 and the stays screwed in. Occasionally the outer end is merely 
 riveted over, the nut being omitted. 
 
 To Find Pitch of Stays (assume pressure as 200 lbs.). 
 Rule— 
 
 Pitch- X Pressure = Stay area x 9000. 
 
 Then, Stay area x 9000 p. 1-375- x 7854 ^ 90oo - ^.^ 
 Pressure 200 
 
 Therefore, \/66 = 8-i in., say 8 in., pitch. 
 
r CAULKED 
 
 No. 29.— Caulking of Stays. 
 
 When the stays are screwed into the plates the latter are 
 caulked round the stays, to ensure tightness, a touch of mastic 
 cement or red lead putty being placed on the face of the nut 
 before screwing up. 
 
 . ,11 . ,11 I ,". 
 
 No. 30.— Steam Space Stay. 
 
 (With Double Nuts and Riveted Washers.) 
 The space 4 (about ^V inch) is filled up with lead putty or mastic cement 
 In this type of stay the outside washers, which are riveted 
 to the end plates, require to be of the same thickness as the 
 plates, and of a diameter equal to two-thirds of the stay pitch. 
 The Constant allowed in this case is 168 for iron and 210 
 
 for steel. 
 
 98 
 
m. 
 n. 
 
 It in. 
 
 as - Double riveted. 
 
 Double riveted. 
 
 ams - Treble riveted. 
 
 - • D. B. strap with five rivets in a pitch, 
 mbers - Single riveted. 
 ]ers (front to back) = 4 ft. 6 in. 
 ^ chambers = 10 ft. 6 in. 
 
 = 1^ in. each. 
 
 ix stay bolts = each i| in. diameter. 
 
 jspension stays of any kind are fitted in this D.-E. 
 bered that in many boilers of this type such stays 
 ilso that the four separate combustion chambers are 
 me supported, by means of angle-plate stools riveted 
 chambers. 
 
 [7b face fiaqe 98. 
 
Pressure = 215 '^s. (gauge). 
 Diameter = i6 ft. 6 in. 
 
 Length :::: 20 ft. 2j ill. 
 
 Rates of heating surface to grate surface = 45 : i. 
 Tensile strength of steel = From 30 to 32 tons per square i 
 Pitch of rivets = 10 in. 
 
 Strength of plate=82-8 per cent (joint strength). 
 Strength of rivets = 90-5 per cent. 
 
 Factor of Safety. 
 
 thus :— 
 
 -Given the above data the Factor of Safety can be calculated 
 
 Then, 
 So that, 
 
 Tons X 2240 X T in 
 30x2240x15^ i 
 
 ■: Joint = Diameter x Pressure x Factor. 
 I X -828 = 198 in. y 215 X Factor. 
 
 Factor = 3^2ii?40x£ 
 
 198 i 
 35 tons is taken, being the minimum tensile strength of the plates. 
 16 ft. 6 in. = 198 in. 
 828 per cent --=-828. 
 
 pitch. 
 
 No. 30A.— Double-Ended Boiler. 
 
 Shell plate thickness = xj| in. 
 Butt strap thickness = i^V ^■ 
 Diameter of rivet holes = i II in- 
 
 Riveting— 
 
 End circumferential shell seams 
 End plate seams 
 
 Centre circumferential shell seams 
 Longitudinal shell seams 
 Furnaces and combustion chambers 
 
 Depth of combustion chambers (front to back) ^4 ft. 6 in. 
 Height of centre combustion chambers = 10 ft. 6 in. 
 Depth of girders = 13 in. 
 Thickness of girder plates = ii in. each. 
 
 Each girder is fitted with six stay bolts = each ij in. diameter. 
 It will be noticed that no suspension stays of any kind are fitted in this D.-E. 
 boiler, but it should be remembered that in many boilers of this type such stays 
 are fitted (see p. 99). Observe also that tlie four separate combustion chambers are 
 held in place, and at the same time supported, by means of angle-plate stools riveted 
 on to the adjoining combustion chambers. 
 
 Double riveted. 
 
 Double riveted. 
 
 Treble riveted. 
 
 D.B. strap with five rivets i 
 
 Single riveted. 
 
 [n i 
 
Boilers 
 
 99 
 
 BOILER SHELL. 
 
 4 THICK 
 
 6 by6 bys" 
 
 2 4 DIAM. 
 
 Is DIAM. 
 
 ^ 
 
 M 
 
 ilij Hi " "iLu 11^ iiu 
 
 ^ 
 
 No. 31.— Method of supporting Combustion Chambers in Double 
 
 Ended Boilers. 
 
 In modern high pressure double-ended boilers, the combustion 
 chambers are often supported as shown above. Observe that the 
 girders do not rest or bear on the combustion chamber plates as 
 ordinarily, but are quite clear, or " floating," the necessary support 
 being supplied by the two large suspension stays, which are secured 
 by pins to double angle irons riveted to the shell. The pins are 
 of turned steel. The combustion chamber bottoms are usually held 
 rigidly in place by angle or plate stays to the boiler shell. 
 
Boile 
 
 rs 
 
 99 
 
 BOILER SHELL. 
 
 i 
 
 rjs— 2"diam. 
 
 Jl, 7" 
 
 6 by6 bys^ 
 
 2i-' 
 
 DIAM. 
 
 No. 31.— Method of supporting Combustion Chambers in Double 
 
 Ended Boilers. 
 
 In modern high pressure double-ended boilers, the combustion 
 chambers are often supported as shown above. Observe that the 
 girders do not rest or bear on the combustion chamber plates as 
 ordinarily, but are quite clear, or "floating," the necessary support 
 being supplied by the two large suspension stays, which are secured 
 by pins to double angle irons riveted to the shell. The pins are 
 of turned steel. The combustion chamber bottoms are usually held 
 rigidly in place by angle or plate stays to the boiler shell. 
 
lOO 
 
 "Verbal" Notes and Sketches 
 
 YZZZZZi 
 
 No. 32. 
 
 -Method of Connecting Wing and Centre Combustion 
 Chamber Plates. 
 
 In modern high pressure boilers the wing and centre combustion 
 chambers are stayed together as shown in the sketch. A plate form 
 of stay is employed, and is connected by means of pins through 
 the plate and through angle irons, riveted to the combustion chamber 
 plates. This type of stay is fitted at the bottom of the combustion 
 chambers, forming a segment round the lower parts. 
 
 I 
 
 I 
 
 No. 34. — View of Wing Combustion Chambers and Furnaces. 
 
 Note the method of connecting the furnace Flange to the Combustion 
 Chamber, also the absence of a Flange at the Furnace Mouth. 
 
 Combustion Chambers. 
 
 The bottoms of combustion chambers are often stiffened by 
 means of angle or T steel segments, which are riveted on, and extend 
 from the bottom for some distance up the sides. Certain makers 
 also fit plate stays, as described above, between these angle segments 
 of adjacent combustion chambers to keep them in position. 
 
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Boilers loi 
 
 Combustion Chamber Stays. 
 
 It will c^cnerally be found that the marginal si;ay.s of combustion 
 chambers are first affected by wear, and particularly, tire top .row. 
 Often the stays in this row develop miniite -cracUs wKich 'may, 
 however, on testing, be found to extend right into the body of the 
 stay metal. The floating tendency of the combustion chamber 
 (which, it should be observed, is simply a hollow vessel immersed 
 in water) throws severe stresses on the stays, and generally, througii 
 time, results in straining the metal of the stays as described, due to the 
 bending stresses set up. The marginal stays having to support more 
 surface than the inner stays are of larger section (often il to 1 4 inches 
 diameter). 
 
 Combustion Chamber Bottoms. — The following rule brings out 
 the safe working pressure for combustion chamber bottom plates, 
 which, it should be observed, form semicircular surfaces of plain 
 section. 
 
 Rule — 
 
 ??ooxT ^ r_L+^\ Safe Pressure. 
 3xD V^ 40 xT/ 
 Where T = Plate Thickness. 
 
 „ L = Length between furnace back end and back of combustion chamber. 
 „ D = Radius of combustion chamber bottom x 2. 
 
 Example. — Find the safe working pressure for the bottom plate 
 of a combustion chamber | inch thick : length of chamber from front 
 to back 32 inches, and outside radius of bottom 23 inches. 
 
 Then, Safe Pressure = ("9900^5 )x(,._ 32+ll\ = 
 \3x(23x2)/ V^ 6ox.7sy 
 
 ~^x (5- -977) = 53-8x4 = 215-2 lbs. per sq. in. 
 130 
 
 Combustion Chamber Girders. 
 
 The combustion chamber top of single ended, and in some cases 
 double ended, boilers is supported against collapse as shown in 
 the sketch. 
 
 The girders are formed of two vertical steel plates each about 
 I or I inch thick, and between these plates stays are passed down 
 and screwed into the top plate ; nuts and overlapping washers are 
 fitted above. The plates forming the girders are held together by 
 rivets fitting through thimbles. 
 
 The girder plates are often made overlapping on to the top 
 plate at the sides, but some firms have the plates cut clear altogether 
 (see No. 39). Under working conditions the girder plates are 
 subjected to a compressive and bending stress, the compression 
 being at the ends where the load is taken up by the back tube plate 
 and combustion chamber plate, and the tensile stress acts at and 
 near the centre of the sfirder. 
 
No- 35— Boiler under Construction. 
 
 \'ie\v showing >:ombu:^tit)n chamber boxes, girders, stays, ^ind front end plate. The close 
 staying of the combustion chamber back plates should be carefully noted. 
 
 NOTE. -The girders shoiwn are all of the single plate type, bossed out where the stays pass throug'h. 
 The bevelled joints of the combustion chamber bottom plate and side plates should also be noted. 
 
Boilers loi 
 
 Combustion Chamber Stays. 
 
 It will f^cncially be found that the marginal Stays of combustion 
 chambers are first affected by wear, and particularly Lhr: cop ,rovv. 
 Often the stays in this row develop miniite -cracks ^Ki'ch 'may, 
 however, on testing, be found to extend right into the body of the 
 stay metal. The floating tendency of the combustion chamber 
 (which, it should be observed, is simply a hollow vessel immersed 
 in water) throws severe stresses on the stays, and generally, through 
 time, results in straining the metal of the stays as described, due to the 
 bending stresses set up. The marginal stays having to support more 
 surface than the inner stays are of larger section (often il to if inches 
 diameter). 
 
 Combustion Chamber Bottoms.— The following rule brings out 
 the safe working pressure for combustion chamber bottom plates, 
 which, it should be observed, form semicircular surfaces of plain 
 section. 
 
 RULE- 
 
 9?ooxT ^ fL+i^Vsafe Pressure. 
 3 X D \^ 40 X T/ 
 
 Where T= Plate Thickness. 
 
 „ L = Length between furnace back end and back of combustion chamber. 
 „ D = Radius of combustion chamber bottom x 2. 
 
 Example. — Find the safe working pressure for the bottom plate 
 of a combustion chamber | inch thick : length of chamber from front 
 to back 32 inches, and outside radius of bottom 23 inches. 
 
 Then, Safe Pressure = (^9 900x75 \x(r- 32+i2\ ^ 
 V3x(23x2)/ V^ 60X.7S/ 
 
 ^^x (5- -977) = 53-8x4= 215-2 lbs. per sq. in. 
 
 Combustion Chamber Girders. 
 
 The combustion chamber top of single ended, and in some cases 
 double ended, boilers is supported against collapse as shown in 
 the sketch. 
 
 The girders are formed of two vertical steel plates each about 
 I or I inch thick, and between these plates stays are passed down 
 and screwed into the top plate ; nuts and overlapping washers are 
 fitted above. The plates forming the girders are held together by 
 rivets fitting through thimbles. 
 
 The girder plates are often made overlapping on to the top 
 plate at the sides, but some firms have the plates cut clear altogether 
 (see No. 39). Under working conditions the girder plates are 
 subjected to a compressive and bending stress, the compression 
 being at the ends where the load is taken up by the back tube plate 
 and combustion chamber plate, and the tensile stress acts at and 
 near the centre of the eirder. 
 
lid 
 
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Boilers 
 
 105 
 
 |"rivets-\C^''' 
 
 CO 
 
 No. 39.— Combustion Chamber Top and Girder. 
 
 Some firms arrange the girders cut clear of the top plate as 
 shown. Attention should be given to the dimensions of the plates, 
 rivets, and stays. 
 
io6 " Verbal " Notes and Sketches 
 
 The strength of girders varies (as in the case of a beam) directly 
 as the Depth'^ and the Thickness, and inversely as the Length. 
 
 RULE- 
 
 Or, Strength varies as, — ^^. 
 
 Working Pressure = Cxd^xT _^^ 
 
 Where, C-990 for three stays, and iioo for four stays. 
 <f= Depth (inches). 
 
 T = Combined thickness of girder plates. 
 W = Width of combustion chamber (inches). 
 P = Pitch of stays (inches). 
 D = Distance between girder centres (inches). 
 L= Length of girders (feet). 
 
 Application. — To apply the rule to the case above (Sketch 36). 
 
 Then, Working Pressure = ^-^ ° "" ^'5^. ^"- ""^'p ^"- -207 lbs. per sq. in. 
 
 (31 m. -7-5 m.)x8 m. X27S 
 
 NOTE. — The width of combustion chamber is about 31 inches, and assume 
 the distance between the girders as 8 inches. Again notice that 33 inches - 
 275 feet. 
 
 Depth of Girders (Sketch 39). 
 
 C-990 for three stays through girders. 
 */= Depth of girder. 
 
 T«: Thickness of girder plates (combined) =:ii inches. 
 W = Combustion chamber width -31 inches 
 P= Pitch of stays -Si inches. 
 D = Distance between girders = 8 inches. 
 L= Length of girders in feet = 2-75 feet. 
 Pressure =190 lbs. per square inch. 
 
 Rule — 
 
 Cxd xT = (W-P)xDxLx Pressure. 
 
 Therefore, fl.- (W-P)x Dx Lx Pressure . 
 CxT 
 
 (31 - 8-5) x 8 x 275 X 190 _. 
 990x1.5 
 
 And, V63-3 = 7-9 in., say 8 in., depth of girders. 
 
 Tubes. 
 
 The smoke tubes are generally made 3 or 3^ inches outside 
 diameter with natural draught and 2h inches outside diameter with 
 forced draught, the thickness ranging from |^ or y\ inch in the case 
 of ordinary tubes, to j% or i inch in the case of stay tubes. The 
 
o o o o o op o o 
 
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 « 
 
 SCARFED 
 JOINT 
 
 No. 40. — Front View of Goose-Neck Type (Gourley-Stephen) Furnace. 
 
 (Front Tube Plate removed.) 
 
 This sketch shows clearly the difference in the section of the furnace at back and front, the back being constricted to 
 an oval section (30 inches diameter). The flange at the back is also much higher in position than the circular portion of 
 the furnace and is riveted all round to the back tube plate. 
 
 Also observe the scarfed joint of the combustion chamber plating at the sides. 
 
 The side wrapper plates are f inch thick, but the bottom is heavier, being \^ inch thick. 
 
 Thickness of Combustion Chamber Bottom Plate. 
 
 Rule — 
 
 (^1^)'<(s-e^>Wo..in, Pr, 
 
 Where T=Thickiiess = }; = .8i25. 
 
 ,, D = Diameter outside =46 inches. 
 
 „ L = Length (front to back)=33 inches. 
 
 Then, Safe Pressure = (m?JlJ}?5\ x ('3 - ^^*" ) = 232-8 lbs. 
 V 3-46 } V 6ox.8i2s; ^ 
 
 This proves that the bottom plate is of ample strength, as less thickness would be sufficient, but the extra thickness given 
 to the plate allows a margin for conosion. 
 
 [Ta fan page 106. 
 
diameter with natural draught and ^4 '"^f ""'J' ""^.h "iTihe c^se 
 
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Boilers 107 
 
 front end of all the tubes is slightly larger in diameter than the back 
 end to allow of easy insertion or extraction. In the case of the tubes 
 the ends are expanded out to the holes in the plate by an appliance 
 known as a "tube expander" (see sketch), which operation is considered 
 sufficient to ensure tightness. The stay tubes represent solid bar stays 
 and are required to support the flat surfaces formed by both tube 
 plates. The sectional area of the stay tube inetal should therefore be 
 equal to that of a solid stay. The required thickness can be found 
 as follows : — 
 
 Example. — Determine the required thickness of steel stay tubes 
 2?/ inches outside diameter to be equal in strength to a solid sta}', the 
 maximum pitch of the stay tubes being 10^- inches and the pressure 
 180 lbs. per square inch. 
 
 Then, Diameter of solid stay = /^°'^75" J< i8o^ ^.^ js {„ (jjameter. 
 
 ' V 9CX)ox.7854 /'t' •" * 
 
 The cross sectional area of metal of the stay tubes must also 
 be equal to the solid stay area. 
 
 Therefore, (2-5--<f-) = i-75" = (6-25-<f-) = 3o625. 
 Therefore, 6-25- 30625 = </2=: 3. 1875. 
 
 Therefore, Inner diameter of tube = V3- 1875 = 178 in., say if, in. 
 And Tube thickness = ^'5 ~ ^ '75 - .^yg in. (| jn.). 
 
 The ends of the tubes are staved up to slightly increase the 
 diameter and so allow for the cutting of the screw, and it should 
 be noted that the external diameter at the front end exceeds that 
 of the back end by about | inch. The ordinary tubes are subject to a 
 compressive stress and the stay tubes to an additional tensile stress. 
 
 In general practice about one-third or more of the total tubes are 
 arranged as stay tubes, and these tubes are usually fixed by one of the 
 following methods : — 
 
 1. Both plates tapped and tubes screwed in, then expanded into 
 the plates. 
 
 2. Both plates tapped and tubes screwed in, expanded into the 
 plates, and a nut | inch thick fitted outside the front tube plate only. 
 
 The plates are caulked round the tubes and the back end of the 
 tubes are also beaded over as shown in sketch. 
 
 It is now the common practice to fit nuts only on the marginal or 
 bounding stay tubes, the others being merely screwed into the plates, 
 expanded in the screws, caulked and beaded over. The sketch on 
 page 108 illustrates the foregoing. 
 
 Often three thicknesses of stay tubes are employed in one boiler to 
 meet the requirements of the differently supported areas of the tube 
 plates, the heaviest type | inch thick being used for the marginal stay 
 tubes, and the others, varying in thickness from | to y'V inch, are 
 fitted inside the marginal area of the plates. 
 
Boilers 107 
 
 front end of all the tubes is slightly larger in diameter than the back 
 end to allow of easy insertion or extractitjn. In the case of the tubes 
 the ends are expanded out to the holes in the plate by an appliance 
 known as a "tube expander" (see sketch), which operation is considered 
 sufficient to ensure tightness. The stay tubes represent solid bar stays 
 and are required to support the flat surfaces formed by both tube 
 plates. The sectional area of the stay tube metal should therefore be 
 equal to that of a solid stay. The required thickness can be found 
 as follows : — 
 
 Example. — Determine the required thickness of steel stay tubes 
 2h inches outside diameter to be equal in strength to a solid stay, the 
 maximum pitch of the stay tubes being 10^ inches and the pressure 
 180 lbs. per square inch. 
 
 Then, Diameter of solid stay= /^^'^"^^'^ 1^^1-74, say i| in., diameter. 
 
 ■^ V 9000x7854 
 
 The cross sectional area of metal of the stay tubes must also 
 be equal to the solid stay area. 
 
 Therefore, (2-5- - cf ) = 1 75- = (6-25 - </-) = 3-0625. 
 Therefore, 625- 30625 = </2= 3- 1875. 
 
 Therefore, Inner diameter of tube = V3- 1875 = 178 in., say if, in. 
 
 And Tube thickness ^?l5j:i^= -375 in. (f in.). 
 
 The ends of the tubes are staved up to slightly increase the 
 diameter and so allow for the cutting of the screw, and it should 
 be noted that the external diameter at the front end exceeds that 
 of the back end by about |- inch. The ordinary tubes are subject to a 
 compressive stress and the stay tubes to an additional tensile stress. 
 
 In general practice about one-third or more of the total tubes are 
 arranged as stay tubes, and these tubes are usually fixed by one of the 
 following methods : — 
 
 1. Both plates tapped and tubes screwed in, then expanded into 
 the plates. 
 
 2. Both plates tapped and tubes screwed in, expanded into the 
 plates, and a nut | inch thick fitted outside the front tube plate only. 
 
 The plates are caulked round the tubes and the back end of the 
 tubes are also beaded over as shown in sketch. 
 
 It is now the common practice to fit nuts only on the marginal or 
 bounding stay tubes, the others being merely screwed into the plates, 
 expanded in the screws, caulked and beaded over. The sketch on 
 page 108 illustrates the foregoing. 
 
 Often three thicknesses of stay tubes are employed in one boiler to 
 meet the requirements of the differently supported areas of the tube 
 plates, the heaviest type I inch thick being used for the marginal stay 
 tubes, and the others, varying in thickness from | to yV inch, are 
 fitted inside the marginal area of the plates. 
 
io8 
 
 "Verbal" Notes and Sketches 
 
 ^ — - 
 
 FRONT 
 
 8'0" 
 
 - — ^--_ _ ___ ' >H 5 \f 
 
 I" THICK 
 
 /-|0 THREADS PER INCH r- 
 
 Hi 
 
 BACK ^H 
 
 J, 
 
 '>v_v-^'^'^'-v^^'-'-^'^'''-'^'*^v'^'-^^^^v'-^'-^v^^'<^ >^^^^\^^^^^'v^^^'^^^^^^■v^^^ ^^ ■ v^^^ ■ .^^^^^^^^.^ 
 
 i 
 
 No. 42.— Boiler Tubes. 
 
 The stay tubes are f inch thick, and are screwed into both 
 plates and caulked in place ; in addition, a flat nut is screwed 
 over the front end. This type of stay tube is used round the 
 boundary of a tube nest. Notice the difference in diameter at 
 either end, the front being the larger. About one-third of the 
 total tubes are fitted as stay tubes, the thickness ranging from 
 ^ inch for the inner stay tubes to f inch for the outer or 
 marginal stay tubes, which are nutted. 
 
 The ordinary tube shown is i\ inch in thickness, and like 
 the stay tube is swelled out at the front end. These tubes are 
 expanded in place by an ordinary three-roller tube expander. 
 
 Stay Tubes. — The light pattern stay tubes (internal) are expanded 
 into both tube plates, and beaded over ; the heavy pattern of stay 
 tubes (marginal) are caulked in position both inside and outside at 
 the front, and inside at the back end, also beaded over, as is usual 
 with all tubes. 
 
 NOTE. — The ratio of tube heating surface to grate surface is as 25 is to i in 
 most cases. 
 
 " Serve " Tubes. — The ribs inside this type of tube increases the 
 effective area of the tube, and thus extracts more heat from the waste 
 gases as they pass through. This results in increased evaporation 
 and economy. 
 
Boilers 
 
 FRONT 
 
 TUBE 
 
 PLATE 
 
 109 
 
 -KM 
 
 8 THICK 
 
 No. 43. — Heavy Pattern Stay Tube. 
 
 (With Flat Nut in Front Tube Plate. ) 
 
 These tubes being too heavy for expanding, the plates are 
 caulked round the tube instead. Tubes of this type are 
 placed on the margins of a tube nest. 
 
 BEADED 
 OVER 
 
 BACK _ 
 TUBE PLATE 
 
 No. 44.— Back End of Stay Tube. 
 
 (Showing Screwing in, Caulking, and Beading over.) 
 
I lO 
 
 "Verbal" Notes and Sketches 
 
 I" SOFT IRON CAULKING RING 
 
 ^^^ 
 
 ^x^^v^mw^^m w^\m.v\mm?^m^^m^ 
 
 ... 27 
 
 ->■; 
 
 ADAM^ON RING 
 FURNACE 
 
 ^V\\\\VV\\V\V\\VV\V\\\\\\\V\V\VV\\\\VV\V\\V\V 
 
 No. 45.— Adamson Ring Furnace. 
 
 ^^^^^^^ 
 
 As with the Bowling Hoop furnace the different lengths are riveted 
 together through the flanges and soft iron caulking rings. The 
 flanges stiffen the furnace and allow for expansion, while tightness of 
 joint is obtained by close caulking up of the soft metal rings. 
 
 Safe Pressure. — For a plain steel furnace the rule is as follows : — 
 
 09000 xT^ 
 Working pressure^^ ^^^^^^ ^ p - 
 
 Where T = Thickness. 
 ,, L = Length in feet 
 „ D = Diameter in inches. 
 
Boilers 
 
 1 1 1 
 
 If, however, the furnace is fitted with stiffening rings as shown 
 above, then \^ — Lc)igth bctivccn the rings subject to a limit pressure 
 found as follows : — 
 
 Limit pressure=?^°° "■ — . 
 
 So that the actual working pressure is to be tiie smaller of the two 
 results obtained. 
 
 Example, — Determine the safe working pressure for the furnace 
 shown in Sketch No. 45, which is \ inch thick and 42 inches diameter. 
 
 Working Pressure 99000 <• 75" —^/-^ ik 
 
 (If less than limit pressure)" (2^25 + iyx'42lrr~^ ' 
 NOTE.— 27 inches ^225 feet. 
 
 Limit Pressure^ ^°° '75 ^ 176 lbs. 
 42 
 
 The safe pressure to be carried is therefore 176 lbs. 
 
 NOTE. —The strength of a plain furnace depends on the Length, Diameter, 
 and Thickness squared. 
 
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 No. 46— Bowling Hoop Furnace. 
 
 c;>^ 
 
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112 
 
 Verbal " Notes and Sketches 
 
 The flanged rings shown are known as " Bowling Hoops," and 
 when fitted to a plain furnace increase the strength and at the same 
 time allow for expansion. As will be understood the furnace length 
 is divided up into two or three sections, and these are joined by the 
 hoops. 
 
 8" 
 
 fVJ 
 
 No. 48. — Suspension Bulb Furnace Corrugation. 
 
 No. 49.— Suspension Bulb Furnace. ' 
 
 The lengths marked A B at front and C D at back are required 
 by Board of Trade not to exceed 9 inches. 
 
 No. 50.— Morison Type Furnace. 
 
 The lengths marked A B and C D are required by Board of Trade 
 not to exceed 9 inches. 
 
I- 
 
 5^ 
 
 .-,mii^'^'^rim<' 
 
No. 47.— Fox Corrugated Furnace (ordinary type). 
 
 (With Details and Dimensions.) 
 
 1, Thinned edge of back tube plate. 
 
 2, Thinned edge of furnace. 
 
 3, Wrapper plate of combustion chamber. 
 
 4, Position of three plate overlap (two plates of which are thinned 
 
 away as described). 
 
 5, Scarfed joint of wrapper plate and bottom plate. 
 
 In this type of furnace, three plates overlap at the area marked 4, the plates being furnace flange, back tube plate, and 
 combustion chamber side or wrapper plate. Two of these plates are, however, thinned away to form only one thickness as 
 shown in the end view at i and 2. Owing to unequal expansion and difficulty in accurate fitting, this part of the furnace 
 (known as the "saddle") frequently causes trouble by leakage and corrosion. 
 
 \To face page III. 
 
Boilers 113 
 
 No. 51— Morison Type Corrugation. 
 
 No. 52.— Morison Suspension Bulb Type Furnace. 
 
 Rule — 
 
 iS000xT = Dx W.P. 
 Therefore, 15000 xT^^p 
 
 Or, = T. 
 
 15000 
 
 And i5000xT _p 
 
 ' W.P. — 
 
 Where, T = Thickness. 
 
 ,, D = Least outside diameter in inches. 
 
 ,, W. P. = Working Pressure per square inch. 
 
 This type of furnace is allowed a higher Constant than any other type. 
 
 Pitch of bulbs = 8 inches. 
 Depth of bulbs = 2| inches (from top to least outside diameter). 
 
 9 
 
Boilers 
 
 113 
 
 No. 51.— Morison Type Corrugation. 
 
 No. 52.— Morison Suspension Bulb Type Furnace. 
 
 RULE- 
 
 Therefore, 
 Or, 
 
 And, 
 
 i5000xT = Dx W.P. 
 
 15000 xT _.^ p 
 D 
 
 DxW.P. ^ 
 
 15000 
 
 15000 X T _ p 
 W.P. 
 
 Where, T = Thickness. 
 
 ,, D = Least outside diameter in inches. 
 
 ,, W.P. = Working Pressure per square inch. 
 
 This type of furnace is allowed a higher Constant than any other type. 
 
 Pitch of bulbs = 8 inches. 
 Depth of bulbs = 2| inches (from top to least outside diameter). 
 
 9 
 
114 
 
 " Verbal " Notes and Sketches 
 
 Repair for Leaky Telescope Furnace Joint. 
 
 Occasionally part of a corroded furnace is cut out circumferentially, 
 and removed, a new length is then telescoped into the part remaining, 
 and double riveting (zig-zag) employed on the joint. If, after the 
 heat is applied, the joint proves leak}-, the following remedies may be 
 tried : — 
 
 1. Caulk the edges of the plates at joint. 
 
 2. Set up each rivet when cold with a hammer. 
 
 3. Build up an arch of fire brick on bars at position of joint to shield it from 
 
 the heat. 
 
 4. Bore out, say, i" diameter holes between rivets, and near edge of joint 
 
 landing, tap, and screw in pins, which afterwards rivet over cold. 
 NOTE.— To form a driving fit, the telescope length should be i^" less in 
 circumference than the part it fits into. 
 
 RIVETS-O 
 
 No. 53.— Furnace Front Riveting. 
 
 When double riveting is employed on the furnace front, the 
 proportions of the joint are as shown, and the strength works out 
 as follows : — 
 
 Seam Section = ^=r— x 100=-^^ — ^-^x 100 = 65 per cent. 
 P 2-5 
 
 Rivet Section = -^ ^J^ ^^3 x 100^ -875^ x -7 854 x 2 x 23 x loo^^ ^^^^ 
 
 P X T X 28 2-5 X -625 X 28 
 
 The joint strength = 63 per cent. 
 
B 
 
 oilers 
 
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114(5 "Verbal" Notes and Sketches 
 
 NOTES ON BOILER UPKEEP AND REPAIR, ETC. 
 
 Boilers Laid Up. 
 
 Boilers not in use should be filled up full with fresh water from 
 which the air has been expelled by boiling, the water to be kept 
 slightly alkaline in condition by the addition of soda or lime. 
 
 If not convenient to fill up with fresh water, then dry the boilers 
 with airing stoves, and place inside, on perforated trays, burning 
 charcoal or coke, afterwards closing up the boilers air tight. The 
 coke absorbs the oxygen and thus prevents oxidation. 
 
 Zinc Plate Allowance. 
 
 Allow about 3 square inches of zinc, i" thick, per square foot of 
 tube surface. 
 
 Lime and Soda. 
 
 If lime is used in boilers, allow about ih lbs. to 2 lbs. per 1000 
 I.H.P. per 24 hours. The same proportion holds good for soda. 
 
 The lime to be dissolved in buckets, strained, and poured into the 
 lime tanks or feed tanks. 
 
 Emptying Boilers. 
 
 Whenever possible, boilers should not be blown down, but ought 
 to be allowed to cool down before emptying. 
 
 Hydrogen Gas in Boilers. 
 
 Hydrogen gas may be present in boilers newly emptied, and, if 
 mixed with certain proportions of air, will produce an explosive 
 mixture. Boilers should, therefore, be ventilated after blowing down 
 or pumping out. 
 
 Leakage in Boilers. 
 
 In the event of serious leakage the ash-pit and furnace doors should 
 be kept closed, and the steam pressure at once reduced by driving the 
 main engines at maximum speed, by blowing steam into the condenser 
 (silent blow-off), and by increasing the feed supply. The safety valves 
 should be eased, and the fires quenched as soon as possible. 
 
 Buckled Plates. 
 
 For slight bulges in combustion chamber plates, clean the surfaces 
 and leave them as they are, as if forced back by hydraulic jack 
 pressure the treatment tends to weaken the plates. 
 
 It is also necessary to renew the surrounding stays, making them, 
 say, I" or {" larger in diameter. 
 
 Parts buckled and exposed to heat may be protected by means 
 of a firebrick shield, or by covering over with fireclay. 
 
 The bulging referred to is, in most cases, caused by oil or scale 
 deposits, which result in overheating of the plate. 
 
 Corrosion. 
 
 For parts showing symptoms of corrosion, clean and scrape care- 
 fully, then apply lime wash, or black lead polished up into the surfaces. 
 A mixture of paraffin and zinc is often used for the same purpose. 
 
svV^ 
 
 S 
 
 
 -X. 
 
 '''?^rs'*»q» 
 
 ■if'jBniu'^ tKi-fl 
 
No. 56.— Furnace and Tube Plate Solid Plates. 
 
 These stays are fitted to support the front and back tube plates on either side of the furnaces (Sketch No. 41). 
 
^ 
 
 
YA YJ *■ 
 
 /Ur~ 
 
 -ai? 
 
No. 57. — Method of Repair for a Weak or Collapsed Furnace. 
 
 Ai will be seen from the sketch, the repair cotisists of two angle irons riveted togf,'ther through thimbles, and forming 
 two half rings which are bolted together as shown. Pins J inch diameter are tapped into the furnace and are riveted over 
 inside, with nuts and washers outside, the pitch of these being about 12 inches. This arrangement stiffens the furnace, 
 and is equally suitable for either plain or corrugated. 
 
 NOTE.— The ring is kept 3 inches clear of the fnmace metal to allow of free drculation of the water. 
 
 [7i/a« page I1&. 
 
Boilers 
 
 115 
 
 No. 54. — Wing Furnace Flanging. 
 
 Notice that the flange is extended out to fit the shape of the 
 combustion chamber. 
 
 To find Thickness of Furnace (Diameter, D = 44 inches, Pressure = 
 200 lbs.). 
 
 Rule — 
 
 14000 X T in. = D in. x Pressure. 
 Therefore. T jn.^D 'n. x Pressure ^44iL2oo^.^^ ^ 
 14000 14000 
 
These stays are fit 
 
 [7i'Mv/rt;'<' 115. 
 
Boilers 
 
 115 
 
 I'rivets, 2 "pitch 
 
 No. 54. — Wing Furnace Flanging. 
 
 Notice that the flange is extended out to fit the shape of the 
 combustion chamber. 
 
 To find Thickness of Furnace (Diameter, D = 44 inches, Pressure = 
 200 lbs.). 
 
 Rule — 
 
 14000 X T in. = D in. x Pressure. 
 
 Therefore, T in. ^D in. x Pressure ^44x200^ .^2 g ^ 
 14000 14000 
 
ii6 "Verbal" Notes and Sketches 
 
 Furnaces. 
 
 Furnaces are usually made from | to f inch in thickness. 
 The strength of a plain furnace depends on the Length, Diameter, 
 and Thickness squared. 
 
 Method of Strengthening a Weak or Collapsed Furnace (with 
 Dimensions). 
 
 The Sketch No. 57 ilkistrates the best method of repair for a weak 
 furnace, or for a collapsed furnace which cannot be set up. 
 
 Observe that the |-inch studs are screwed into the furnace metal 
 and riveted over, also that thin thimbles or distance pieces are fitted 
 between the half-round strengthening ring and the furnace, to allow of 
 free circulation of the water. The pitch of the studs varies from 10 to 
 13 inches. 
 
 As in a plain furnace the strength depends upon the length, 
 diameter, and thickness squared, if we reduce the length by one-half 
 we double the strength ; therefore the ring round the centre practically 
 shortens the length, and correspondingly increases the strength (always 
 subject to Limit Pressure Rule result). 
 
 NOTE. — Thimbles must be fitted between the furnace and the ring to allow of 
 water circulation between. 
 
 Types of Furnaces. 
 
 The Sketches No. 58 illustrate the corrugations of the three mosi 
 important types of furnaces in use at the present time. 
 
 Corrugated Furnace Manufacture. 
 
 The process of manufacture of furnaces is as follows : — The plate 
 is rolled with one edge thicker than the rest of the plate, so as to 
 allow for the thinning which takes place in flanging. The plate is 
 then sheared to size, and bent to a cylindrical shape in the bending 
 rolls. It is then passed to the electrical welding apparatus, where 
 it is welded up, after which the furnace is taken to the corrugating 
 mill to be corrugated, and to the various hydraulic machines for 
 flanging. The furnace is then machined to correct sizes, and set 
 true to template. Finally, each furnace is carefully annealed before 
 despatch. 
 
 Advantages of Corrugated Furnaces over Plain Furnaces. 
 
 1. Stronger than a plain furnace of the same dimensions. 
 
 2. Better expansion allowance by means of the corrugations 
 or ribs, 
 
 3. More surface for the same length, and therefore better evapora- 
 tion is obtained. 
 
 NOTE. — For a plain furnace the limit pressure is equal to ^^^^ — 
 
.^at*^' 
 
No. 6i— Boiler Shell Manhole (l6 inches by 12 inches). 
 I, Compensation Ring. 2, Joint of Door. 3, Boiler Shell. 
 
 NOTE. The upper view (section) is taken in the longitudinal direction, and shows the 
 short diameter of the manhole (12 inches). 
 
 The compensation ring is of the same thickness as the shell plate. 
 
117 
 
 MORISON 
 
 DEIGHTON 
 
 No. 58. — Types of Furnaces. 
 
 (With Pitch and Depth of Corrugations. ) 
 
 A corrugated furnace of the same dimensions is about half as 
 strong again as a plain furnace of average proportions. 
 
 The strength of a corrugated furnace depends upon the Diameter 
 and Thickness. 
 
 Collapse of Furnaces. 
 
 Furnaces may be collapsed by any of the following causes : — 
 I. Excessive scale. The scale keeps the water from being in 
 direct contact with the plate, and overheating takes place (about 600" 
 Fahn), with the result that as the plate is weakened part of the furnace 
 bulges in. 
 
117 
 
 MORISON 
 
 DEIGHTON 
 
 No. 58. — Types of Furnaces. 
 
 (With Pitch and Depth of Corrugations. ) 
 
 A corrugated furnace of the same dimensions is about half as 
 strong again as a plain furnace of average proportions. 
 
 The strength of a corrugated furnace depends upon the Diameter 
 and Thickness. 
 
 Collapse of Furnaces. 
 
 Furnaces may be collapsed by any of the following causes : — 
 I. Excessive scale. The scale keeps the water from being in 
 direct contact with the plate, and overheating takes place (about 600'' 
 Fahr.), with the result that as the plate is weakened part of the furnace 
 bulges in. 
 
ii8 
 
 Verbal " Notes and Sketches 
 
 2. Oil deposits adhering to the furnace. Oil deposited on the 
 furnace top or sides, for a given thickness, is more serious than 
 ordinary scale, as greater overheating of the furnace plates will ensue. 
 
 3. Saturation or salt deposits. The bc^ler density rising above /vr, 
 the surplus salt in the water deposits, and the water not being in 
 contact with the metal, overheating of the plates takes place and 
 collapse follows. 
 
 Cases have been observed where furnaces have come down when 
 lying under banked fires. One of the most reasonable theories put 
 forward to account for this is the lack of circulation existing (especially 
 with a high density), causing a layer of steam to form between the 
 water and the metal of the furnace, with consequent overheating 
 and collapse ; but opinion is somewhat divided on this point, and the 
 true cause is not definitely known. 
 
 Furnace Temperatures, &c. (approximate). 
 
 Furnace temperature - - - - 
 
 Combustion chamber temperature - 
 
 Uptake temperature - - - - 
 
 Funnel temperature - - - - ,, 
 
 NOTE. — The above temperatures (measured by a pyrometer) vary under different 
 conditions, but these may be taken as average. 
 
 about 2600° Fahr. 
 ,j 1500° » 
 ,. 750° » 
 600° 
 
 A" 
 
 No. 59.— Fire Bar. 
 
 (With Dimensions.) 
 
 The air spaces are formed by small projections cast on the sides 
 of the bars, which ensures the required air clearance. 
 
 When the bars are fitted in two lengths, the dimensions are 
 usually as marked. Notice that one end of the bar is bevelled away 
 to allow for expansion under heat, and the other end is " hooked ' to 
 grip the edge of the centre bearer. 
 

 -er IS 
 
 side 
 
 2vved 
 
 earer 
 
 , but 
 s are 
 
 ;ially 
 .te is 
 
 and 
 
 f the 
 
 also 
 
 \y as 
 f the 
 
 ihole 
 .t air 
 wing 
 light 
 k. 
 
 plates flanged in to give strength, instead of fitting a compensation 
 plate ; in addition to this three large stays are passed through from 
 end to end of the boiler, and secured to the end plates by nuts,^ as 
 shown in the sketch. These stays support the plate round the portion 
 weakened by the cutting of the holes. 
 
ii8 
 
 2, 
 
 furna( 
 ordin; 
 
 3- 
 the SI 
 contai 
 collap 
 
 Cc 
 
 lying 
 forwai 
 with ; 
 water 
 and C( 
 true c • 
 
 Furn; 
 
 F 
 C 
 U 
 F 
 
 NO' 
 
 conditi( 
 
 C: 
 
 of the bars, which ensures the required air clearance. 
 
 When the bars are fitted in two lengths, the dimensions are 
 usually as marked. Notice that one end of the bar is bevelled away 
 to allow for expansion under heat, and the other end is "hooked ' to 
 grip the edge of the centre bearer. 
 
Boilers 
 
 jnL 
 
 3'-!" 
 
 © 
 
 © 
 
 © 
 
 -4 
 
 JUL 
 
 rm 
 
 \<r 
 
 mr 
 
 I 4 BOLTS I- Ig THIMBLES 
 
 No. 6o— Centre Bearer for Fire Bars. 
 
 inr' 
 
 UJT 
 
 When the bars are arranged in two lengths, the centre bearer is 
 fitted as shown ; the bearer sits on an angle knee plate at either side 
 of the furnace, the knees being held in position by studs screwed 
 through the furnace, and the bars hook on to the edge of the bearer 
 plates. 
 
 Manholes. 
 
 The standard size for manholes is i6 inches by I2 inches, but 
 sometimes those on the end plates between the furnace openings are 
 less, being 1 5 inches by 1 1 inches, or thereabout. 
 
 Shell manholes are cut with the long diameter circumferentially 
 and the short diameter longitudinally, as the strength of the plate is 
 least in this direction. 
 
 Shell manholes have compensation rings riveted to the shell and 
 of equal thickness, the area of ring to be not less than that of the 
 metal cut out plus the rivet hole areas. The compensation ring also 
 forms the joint for the door (Sketch No. 6i). 
 
 The clearance round the door and opening should be as nearly as 
 possible iV iiich a side, as excessive clearance is often the cause of the 
 doors blowing out. 
 
 After blowing down the boilers, and before taking off the manhole 
 doors, the drain cock of the water gauge should be opened so that air 
 may enter the boiler and destroy the possible vacuum left by blowing 
 down. Neglect of this may lead to an accident, as the doors might 
 be blown in by atmospheric pressure when the nuts are eased back. 
 
 The manholes in the boiler ends are often arranged with the end 
 plates flanged in to give strength, instead of fitting a compensation 
 plate ; in addition to this three large stays are passed through from 
 end to end of the boiler, and secured to the end plates by nuts,^ as 
 shown in the sketch. These stays support the plate round the portion 
 weakened by the cutting of the holes. 
 
I20 
 
 "Verbal" Notes and Sketches 
 
 Compensating Ring of Manhole. 
 
 As the stress on the boiler shell longitudinally is twice that 
 circumferentially, it is sufficient to calculate the width of ring for the 
 longitudinal direction only. 
 
 Suppose manhole opening to be i6" by 12", then the 12" cut 
 is longitudinally, and if the shell is, say, i{" thick, the section 
 removed is equal to 12 X 1-25 = 15 0. 
 
 The compensating ring section must be at least equal to this, 
 and assuming equal thickness of shell and ring, and neglecting rivets, 
 the rule becomes : — 
 
 12" X 1-25" = W" X 1-25" X 2 
 
 W = width of ring. 
 2 = two widths (one on 
 either side). 
 
 Then, W = 1?^^:1B = 6" width of ring (rivets neglected). 
 
 1*25 X 2 
 
 Boiler Sne.1 
 
 y//y/////A 
 
 vw^ 
 
 Rin(j._. 
 
 S-— ^ 
 
 . _Y- - 
 
 h-- 6 --^ 
 
 Boiler Shell 
 
 
 .• A 
 
 V////A M 
 
 ^^r^^^ 
 
 4. 
 
 f<-- n 
 
 •'-> 
 
 •^--7i"—^, 
 
 If, say, the rivets are ij" diameter, then W is found as 
 follows : — 
 
 12 X 1-25 = (W— 1-25) X 1-25 X 2. 
 Then, W = " ^ ^'^5 ^ 1.35 = 7^" ^idth of ring (rivets allowed for). 
 
 As the rivet holes weaken the ring, the width of it must be in- 
 creased in proportion to keep up the strength. 
 
No. 62.— Boiler End Plate Manhole (15 inches by 11 inches). 
 
 I, Joint of door. 2, Stays. 3, End plate flanged in. 
 
 [7(? face page 120. 
 
^satei?.; 
 
 \^^^ 
 
 '•\ \ 
 
 \ \ 
 
 ^. 
 
 u 
 
 Vr 
 
 .Z3d0ni II vn P-.rl r-\ 3T, 
 
 ^— •s:d .o'A 
 
Boilers 121 
 
 A doubling plate is also riveted to the back of the boiler opposite 
 to the manhole in the front (Sketch No. 33), and covering a similar 
 area. 
 
 Natural Draught. 
 
 Natural draught is caused by the difference of weight in the 
 heated air of the uptake and the cold air entering the furnace. 
 
 To obtain a good draught the funnel and uptake temperatures 
 must be between 600" and 700°, this temperature being necessary to 
 bring about the required difference of weight. 
 
 The draught can often be improved by increasing the length of 
 the funnel, as by this means the column of heated, and therefore 
 lighter, air is made less in weight, against the same weight of cold 
 and heavy air. 
 
 The production of natural draught is an example of heat con- 
 vection, as the cold air at, say, 60° temperature, passing down the 
 ventilators, enters the furnace and becoming heated expands and 
 therefore rises, passing off by way of the tubes, uptake, and funnel. 
 The weight of the heated air is less than that of the cold air, and the 
 difference in weight can be found by taking the absolute temperature 
 as shown below. 
 
 Example. — A cubic foot of air at 62° temperature weighs -076 
 of a lb. ; determine the weight if the air is heated to 600° temperature. 
 
 Then, 62 + 461^=523, and 600 + 461-1,061. 
 Therefore, As 1061 : 523 : : -076 = -0374 of a pound. 
 
 The difference of weight as shown produces a current or draught. 
 
 Heat Absorbed in Creating Natural Draught. — The specific 
 heat of the funnel gases is about -23, which means that to raise i lb. 
 of the gases i^ in temperature -23 of a heat unit is necessary. To 
 show then the loss incurred by the generation of natural draught: — 
 
 Example. — Cold air temperature 62", uptake temperature 700°, 
 and allowing 24 lbs. of air per lb. coal, calculate the heat units per 
 lb. coal used in producing the draught. 
 
 Then, 700° - 62' - 638' increase of air temperature, 
 
 and B.T.U. required = 638 x 25 x •23 = 36685. 
 
 NOTE.— 24 lbs. of air + i lb. coal = 25 lbs. gases in all (neglecting ash and 
 clinker). 
 
 As a Percentage. — Assuming that i lb. coal contains 14,500 
 Heat Units, 
 
 Then, As 14500 : 3668 5 : : 100 : 25 per cent. 
 
 I 
 
122 
 
 " Verbal " Notes and Sketches 
 
 So that 25 per cent, of the heat units in each lb. of coal are used up 
 in producing the necessary difference in temperature of the funnel 
 gases required to form a draught by difference of weight. 
 
 Howden's Forced Draught. 
 
 In this well-known system of artificial draught, a large fan 
 driven by means of a small engine, usually placed in the engine- 
 room, forces the air along the air trunk into the air heating box 
 
 Front View. 
 
 Inside View. 
 
 No. 64. — Howden's Forced Draught Furnace Mountings. 
 
 a, Top Valve Handle. 
 
 b, Back Catch. 
 
 c, Front Catch. 
 
 d, Hinge Flat. 
 
 e, Hinge Centre. 
 
 fc, Ashpit Door Handle for Centre 
 
 Front, 
 fs, Ashpit Door Handle for Side 
 
 Front, 
 g, Catch for Ashpit Door. 
 
 h, Hanger for Ashpit Door, 
 k, Side Valve Handle. 
 1, Left-hand Baffle Plate (or Air 
 
 Box), 
 m, Mica Plate, 
 r, Right-hand Baffle Plate (or Air 
 
 Box), 
 s, Door Baffle Plate (or Air Box), 
 t, Top Baffle Plate (or Air Box), 
 u, Furnace Door. 
 X, Ashpit Door. 
 
 situated in the uptake, and consisting of two tube plates with a 
 series of short vertical tubes between. The hot gases from the 
 smoke tubes pass up through the sets of short tubes in the box, and 
 the air, being outside of these, is heated by the otherwise waste gases, 
 and passes by openings in the sides through a casing on the boiler 
 end down to the hot air receiver above the furnaces (see sketch). 
 
 The fronts of the furnaces are closed, and have three metal 
 valves fitted, by which the air supply can be regulated to the furnaces, 
 both above and below the fire-bars, one valve admitting the air 
 
STAVED UP TO 
 SCREWED 6 THREADS 
 
 2n 
 
 DIA 
 PER INCH 
 
 ^? 
 
 )4>! 
 
 i(tS.-,vf-isi.*^ti5S> 
 
 '^i-h^: :^::-<'S>:,i^: ^sss 
 
 a^ 
 
 i.. 
 
 C t'-^i' 
 
? 
 
 2" -27-66-AIB POESSURE IN LBS PIR B =072 I 
 
 No. 63. — Sectional View of Boiler with Howden's Forced Draught. 
 
 _The draught n een=™Ied by the tui shown, uid the cold aip (slj u 6o*) it delijtied, by way of the air casLng, into the air healing bo« which is situated in the uptake. The air circulates eulMi the healing tubes, and becomes raised in temperature by the waste gases to 
 k-i™ ,h. h xt" Mmperature it eotera the funiaces, being admitted by one valve above the lire bars, and by two valves (both operated by one handle) to below the bats. A suitable air pressure at the furnace is J inch pressure above the bars and | inch pressure 
 below the bars. This nressure can only be measured bv a ooriab e U tube similar ,:■■•■ 1___ . .1. , ". ' 1 i- 1 1 r J i- 
 
 shown in the drawing. 
 
 atmosphere, as the pressure of the draDgbl is slightly 
 
Boilers 
 
 123 
 
 HOT AIR RECEIVER 
 AIR VALVE 
 
 DOUBLE DOOP. 
 
 No. 65. — Howden's Forced Draught 
 
 The air is heated by the otherwise waste gases to about 220° 
 temperature before entering the furnaces. 
 
^A ^ 
 
Boilers 
 
 123 
 
 K 
 
 AIR 
 
 ,„,., 
 
 FAM 
 
 \ 
 
 HOT AIR RECEIVER 
 
 DOUBLE DOOR 
 
 No. 65. — Howden's Forced Draught. 
 
 The air is heated by the otherwise waste gases to about 220° 
 temperature before entering the furnaces. 
 
124 
 
 " Verbal " Notes and Sketches 
 
 above the bars, and the other two admitting it below. The furnace 
 doors are made double, the outer half being airtight, and the inner 
 half being perforated with small holes for the jets of air to pass 
 through. It should be mentioned that with forced draught the 
 smoke tubes are made smaller than usual, generally from 2J to 2i 
 inches in diameter outside, and that strips of twisted metal, called 
 " retarders," are often fitted inside of them to increase their heating 
 power by retarding or keeping back the hot gases, so that as mucli 
 of the heat as possible is given up to the water before the gases 
 leave the tubes. 
 
 The force or intensity of the draught is measured by a U-shaped 
 glass tube containing water, one end of the tube being connected 
 
 TO FAN CASIMC. 
 
 WATER. 
 
 No. 66. 
 
 to the air trunk and the other end left open to the atmosphere. 
 The air pressure in the trunk forces the water higher in the leg 
 of the tube which is open to the atmosphere and lower in the 
 leg open to the air casing, and the difference of the two water levels 
 is called the air pressure, and is expressed in inches of water. 
 
 In practice from i| to 3 inches of water is the amount carried. 
 
 If the water gauge shows, say, 3 inches of water, to find th 
 pressure of the draught divide this by 27-66 inches. 
 
 NOTE. — A column of water 27-66 inches in height weighs i lb. per square inch.j 
 
 Thus, —3^ = .108 lb. per sq. in. 
 
 2766 
 
 NOTE. — If the water gauge for the draught indicates about 2?. or 3 inches at 
 the fan, the pressure under the fire-bars will only be equal to about j inch or 
 thereabout. 
 
Boilers 125 
 
 Gains of Forced Draught. 
 
 1. Smaller boilers for the same power, as the consumption is more 
 per square foot of grate. 
 
 2. Hot air enters the furnace in place of cold air. 
 , 3. Better steaming of power boilers, 
 
 4. Better control of fires, as the draught is independent of weather 
 conditions. 
 
 With forced draught the air is partly heated by the waste gases 
 before entering the furnaces, which means that less heat requires to 
 be taken from the coal to heat it, and, as the consuinption per square 
 foot of grate surface is more than with natural draught, more evapora- 
 tion will be the result, and therefore a smaller boiler will supply the 
 same amount of steam : in addition to this the boilers generally steam 
 much easier with forced draught. 
 
 NOTE.— As part of the heat of the wasLe gases is absorbed by the air in 
 the heating box, the temperature of the funnel gases is less, being somewhat 
 between 450° and 550' in general practice. The safety valves are made larger 
 when forced draught is fitted, to allow for the increased evaporation per square 
 foot of heating surface and resultant increase of steam generation. 
 
 Notes on Forced Draught. 
 
 About 20 lbs. of air per pound of coal are required for combustion, 
 instead of 24 lbs. as with natural draught. The air being heated to 
 about 210^ by the waste products of combustion, requires less heat 
 from the coal to effect combustion. 
 
 The consumption of coal may range from 25 to 40 lbs. per 
 square foot of grate per hour according to the force of the draught 
 carried. This results in reduced size of boilers being sufficient for a 
 given power. 
 
 The air being forced into the furnaces is better distributed and 
 more effective, which results in higher furnace temperatures. 
 
 With a water pressure of 2J inches at the fan, the pressure under the 
 bars should be equal to about I inch water, and above the bars equal 
 to about I inch water. 
 
 The chief disadvantages of forced draught are : — 
 
 1. Greater risk of collapsed furnaces if coated with scale or oil 
 deposit, owing to higher temperature of furnace. 
 
 2. Greater tendency to leaky tubes and seams, owing to higher 
 temperature of gases. 
 
 3. Trouble with tubes choking up with soot, if not cleaned often 
 and regularly. 
 
 Heat Saved. 
 
 The approximate number of heat units saved by forced draught 
 per pound of coal may be calculated as follows : — 
 
T26 ''Verbal" Notes and Sketches 
 
 Natural Draught. — Assume 24 lbs, of air per pound coal, cold 
 air temperature 62°, funnel gases temperature 650°, specific heat of 
 gases -23. 
 
 Then, 650° -62° = 588° rise of air temperature. 
 
 And, 588 X 25 X •23=3,381 Heat units required per pound of coal. 
 
 NOTE.— 24 lbs. of air + i lb. of coal = 25 lbs. weight of gases in all. 
 
 Forced Draught. — Assume 20 lbs. of air per pound coal, heated 
 air temperature 200°, funnel gases temperature 550'. 
 
 Then, 550° - 200° - 350° rise of air temperature. 
 
 And, 350 X 21 X •23 = 1690-5 Heat units required per pound of coal. 
 
 NOTE.— 20 lbs. of air + i lb. of coal = 21 lbs. of gases in all. 
 So that 3381 - 1690-5 = i690'5 Heat units saved per pound of coal burnt. 
 
 Howden's Forced Draught. — As a general rule the best results 
 are obtained when the air pressure below the bars is equal to i inch 
 water, and above the bars f inch water, giving a difference of f inch, 
 and to obtain this it may be found necessary to build up the bridge 
 by, say, two brick thickness more than that arranged for originally by 
 the makers. If this alteration is made, the results will, in most cases, 
 be found to be the best possible, both as regards combustion and the 
 life of the boilers. 
 
 Pitting and Corrosion. — In boilers the general causes of corrosion 
 are : — 
 
 I. Fatty acids from animal or vegetable oils, which are set free 
 when the oil is decomposed by the heat. 2. Oxygen and CO2 from 
 air brought in with the feed water, and set free by the heat. 
 3. Galvanic action, due to the difference in composition of the metals 
 used in the construction of the boiler, such as iron and steel, and to 
 other similar causes. 
 
 The best oil for internal lubrication, or for rods, is mineral oil, 
 which is a pure hydrocarbon, and free from acids. 
 
 Most of the oil used for internal lubrication of the engines finds 
 its way to the boilers, by being brought with the steam into the 
 condenser, and afterwards pumped into the boilers by the feed pumps. 
 
 Places Pitted. — The parts of a boiler where pitting occurs vary 
 a great deal in different boilers, but the most common places are — 
 (i) About the line of the fire-bars on the water side of the furnaces ; 
 
 (2) at the sides, bottom, and back of the combustion chamber ; 
 
 (3) at the back ends of the tubes, and at the combustion chamber 
 end of the small stays, which are exposed to the high temperature 
 sases. 
 
Boilers 127 
 
 Furnace Collapse by Retention of Gases. 
 
 In some cases the collapse of furnaces may be brought about as 
 follows : — 
 
 If with forced draught the tubes become badly choked up with 
 soot the outlets for the products of combustion are correspondingly 
 reduced, and the gases being thus retained, may rise in temperature 
 to a serious degree, and overheat the furnace metal; if the tempera- 
 ture of the plates exceeds 600°, collapse of the crown will likely take 
 place. Retarders placed in the tubes unfortunately tend to produce 
 the choking up referred to, as also do the " Serve " type of boiler 
 tube. 
 
 Collapse of Furnaces. — When a furnace crown is brought down 
 by oil deposits, it often happens that after the boiler has been blown 
 down and the furnace examined inside, no trace whatever can be 
 discovered of the cause of collapse. This is accounted for by the 
 fact that when overheating of the plate takes place, and consequent 
 buckling, the intense heat resulting burns completely away the layer 
 of oil, thus leaving no trace. The only clue to the true cause of the 
 collapse lies in the fact that generally the metal is cleaner at the 
 place where the oil had formerly lain than on other parts of the 
 furnace metal. 
 
 Heating Surface and Grate Surface. 
 
 In cylindrical marine boilers the ratio of Heating to Grate surface 
 is about 30 or 35 to i, and in water-tube boilers from 40 to i 
 upwards. 
 
 Boiler Repairs, Parts Corroded, &c. 
 
 Chain Patch. — Cracks in furnaces and combustion chambers are often 
 repaired by means of a chain patch, consisting of a series of pins 
 tapped into the crack and into each other, the ends being riveted over 
 as shown in the sketch, this method of repair being handy and 
 suitable for small cracks. 
 
 Patches. — For a badly corroded section of a furnace or combustion 
 chamber a riveted patch may be found necessary and should be 
 arranged as follows : — 
 
 1. First cut out the defective piece of plate. 
 
 2. Shape the patch to template, and of a thickness about yV inch 
 less than the furnace or combustion chamber it is to be fitted on to. 
 
 3. Employ rivets of a diameter determined as follows : — 
 
 Rule— 
 
 1-2 X v^plate Thickness = rivet diameter. 
 
128 
 
 ''Verbal" Notes and Sketches 
 
 8 RIVETS (countersunk; 
 
 No. 67. — Method of Repair for a Crack. 
 
 The repair consists of a series of rivets countersunk on one 
 side, and just touching each other as shown. This method 
 of repair for a longitudinal crack in a furnace or combustion 
 chamber will be found, in most cases, to stand better than the 
 chain patch obtained by screwed pins tapped half into each 
 other and riveted over. 
 
 And of a pitch found as follows : — 
 
 Rule— 
 
 looxrivet^iameter^pij^j^ of rivets. 
 100 -joint 
 
 It must be remembered that the joint strength referred to is equal to 
 about 53 per cent, if single riveting is employed, and 68 to 70 per 
 cent, if double riveting. 
 
 4. Rivet the patch on to the fire side of j^late so that the effect of 
 the heat will take place on the edges of the patch in place of the 
 
Boilers 129 
 
 edges of the furnace or combustion chamber metal. This will also 
 be found more convenient for caulking. 
 
 5. The patch should form a metal to metal joint without any 
 other jointing material. 
 
 6. The distance from edge of rivet hole to edge, of plate must be 
 equal to one rivet diameter, and the width of lap for single riveting 
 will therefore be equal to three rivet diameters. 
 
 General Repairs. 
 
 If a combustion chamber shows a buckle between some of the 
 stays, it is probably due to defective circulation, oil or scale deposits 
 adhering to the plate and causing overheating. If the buckle is bad, 
 tap a stay through it and the boiler plate between the other stays. 
 
 If a furnace or combustion chamber plate develops a blister, it is 
 usually caused by the plate being laminated, which means that some 
 dirt or sand has been rolled up with the metal during manufacture ; 
 the plate, not being solid throughout, blisters when heated. 
 
 If a piece of a furnace requires to be patched, first cut out the 
 defective piece of the plate and then rivet on the patch (metal to 
 metal) on the fire side of the plate. The thickness of patch should 
 be from f inch to | inch, and the diameter of rivets about | inch. 
 
 If a combustion chamber stay leaks badly, and cannot be kept 
 tight, take out the stay and tap the holes to a larger diameter, then 
 screw in a new stay. 
 
 NOTE.— If the plates cannot be tapped, a distance piece or thimble is neces- 
 sary to form a joint, when a bolt is used instead of a screwed stay. 
 
 Stay Repair. — The following method of repair for a leaky com- 
 bustion chamber riveted stay may be applied when a new stay of a 
 slightly larger size cannot be obtained. Chip off the riveted head 
 flush with the plate, bore a hole in the stay, say f inch diameter, then 
 drift out the hole to tighten up the threads in the plate, next tap the 
 hole I inch diameter and screw in a pin of that size, fitting a |-inch 
 thick washer, with a joint of asbestos and red lead. 
 
 NOTE. — As the ^-inch pin now takes the place of the stay, theoretically, the 
 pressure should be reduced by rule to this size. In the proportion of the respec- 
 tive stay areas assume original stay to be i^ inches diameter and boiler pressure 
 180 lbs., then, 
 
 As, i'2S- X '7854 : -875- X 7854 : : 180 lbs. 
 
 Or, as, 1.25'^ : •875- : : 180 lbs. 
 
 Therefore, jTS'x 180^33 ^^^ ^^^^ pressure. 
 
 1-25'^ 
 
 This of course neglects the holding power of the stay obtained by 
 the expanding out of the metal, which may more or less make up for 
 the loss of area, and permit of the original pressure being carried. 
 
I30 
 
 "Verbal" Notes and Sketches 
 
 -SLiOhTT PirriAr(f inSiQC 
 THIS L I '^c 
 
 a c^^oi o o 
 (o o/o o o o o o 
 
 Plan Showing the Defect 
 
 ■ A.^V^.v^mmx-.V^^W\V;i^^ 
 
 No. 68.— Pitting of Boiler Shell Plate. 
 
 The above sketch shows the effects produced by pitting on a 
 boiler shell plate §i inch thick, and which resulted in an explosion. 
 
 The pitting appears to have originated in local galvanic action on 
 a small area of the plate, due to impurity in manufacture, and this 
 afterwards extended as shown above and blew out. 
 
 BACK TUBE 
 PLATE 
 
 No. 69.— Tube Plate Corrosion. 
 
 If a boiler tube leaks and the leakage is not checked at once by 
 re-expanding, the tube plate is in danger of corroding as shown in 
 the sketch. 
 
 This corrosion is caused by small quantities of water leaking 
 through, which, becoming decomposed by the heat, sets free oxygen 
 gas : the oxygen gas combines chemically with the tube metal to 
 form iron oxide, which results in wasting of the metal. 
 
No. 71— Furnace Corrosion. 
 
 1, Corrosion due to heat setting free oxygen gas. 
 
 2, Corrosion due to moisture such as from wet ashes, &c. The heat sets free 
 
 oxygen and CO as, which in combination are highly corrosive. 
 
V/////////////////////////////^^^^^ W/A ;, 
 
 No. 72— Corrosion on Furnaces. &c 
 X, Corrosion above line of bars due to high temperature and 
 liberation of free oxygen gas. 
 
 2, Corrosion due to moisture, such as from wet ashes. 
 
 3, Corrosion due to expansion and leakage, also repeated 
 
 caulkmg of the plate edges. 
 
 4, Corrosion due to unequal expansion, straining, and leakage. 
 
 5, Corrosion due to straining of plates and faulty 
 circulation. 
 
 6, Corrosion due to straining of plates, intense heat, 
 and leakage. 
 
 7, Corrosion due to grease, and other deposits. 
 
Boilers 
 
 131 
 
 COMBUSTION 
 
 CHAMBER 
 
 BACK 
 
 No. 70.— Combustion Chamber Plate Corrosion 
 
 If a stay leaks at the back end, corrosion may follow by the 
 oxygen gas set free by the heat. This is shown at 2 in the sketch, 
 and the repair would be to take out the stay and re-tap the holes to 
 a larger size, screwing in a heavier stay. 
 
 Furnace Corrosion. 
 
 1, Corrosion due to heat setting free oxygen gas. 
 
 2, Corrosion due to moisture such as from \wet ashes, &c. The heat sets free 
 
 oxygen and CO as, which in combination are highly corrosive. 
 
^1 
 
 i^^^^^^ 
 
 gas: the oxygen gas combines cnemicaiiy witn tne tuoe metai to i 
 form iron oxide, which results in wasting of the metal. \ 
 
Boilers 
 
 131 
 
 COMBUSTION 
 
 CHAMBER 
 
 BACK 
 
 No. 70.— Combustion Chamber Plate Corrosion 
 
 If a stay leaks at the back end, corrosion may follow by the 
 oxygen gas set free by the heat. This is shown at 2 in the sketch, 
 and the repair would be to take out the stay and re-tap the holes to 
 a larger size, screwing in a heavier stay. 
 
 I 
 
 No. 71.— Furnace Corrosion. 
 
 1, Corrosion due to heat setting free oxygen gas. 
 
 2, Corrosion due to moisture such as from wet ashes, &c. The heat sets free 
 
 oxygen and CO as, which in combination are highly corrosive. 
 
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 No. 74.— The Bagguley Patent "AH Metal" Tube Stopper. 
 
 I, I, Soft metal sleeves. 2, 2, Copper washers. 
 B, Diameter of cones is equal to outside diameter of sleeves 
 
 When the nut is tightened up the cones press out the ends of the sleeves, thus forming four melal-tometal joints. 
 
 The patent stopper shown above makes four metal-to-metal joints in the faulty tube, two at each end, and the whole operailon 
 is performed by means of screwing up a single nut at the front end of the tube, the stopper being placed in position from the front end. 
 
 The patent stopper consists of a long bolt which passes right through the boiler tube to be stopped ; this bolt has a tapered 
 head on the back end which exactly fits the tube. Three conical sleeves slip on to this bolt, making a tight fit externally on 
 the bolt, and internally on the boiler tube. The front end of the bolt is screwed and fitted with a feather-way. and on this end 
 a hexagon washer or nut is fitted with a feather to fit the above-mentioned feather-way. A screwed nut is then fitted to the bolt, 
 and a malleable-iron tube is passed over the bolt, which keeps the cone pieces in position, and enables them to be tightened up 
 simultaneously. Two soft metal sleeves, i, i, complete the arrangement. 
 
 In stopping a faulty tube the whole apparatus is passed through from the smoke-box end as one piece, and by holding the 
 hexagon washer by means of a spanner and screwing up the nut the four taper pieces are screwed up simultatieously, expanding the 
 soft metal sleeves and thus effectively stopping up the faulty tube, and cutting it out of action for any length of time. 
 
Boilers 133 
 
 Iron Tubes and Stays. * 
 
 In steel boilers the tubes and small stays are often made of iron, 
 for the reason that iron corrodes less than steel under corrosive 
 influences. 
 
 Leaky Tubes. 
 
 Owing to the tubes and tube plate expanding at different rates, 
 the back ends of the tubes often leak. This is remedied by re- 
 expanding, or by fitting into the tube at the back end a capped 
 ferrule as used in the Navy, to keep the heat off the tube end and 
 the plate (Sketch No. 75). Scale and soot on the tubes and plates 
 tend to increase the leakage, and with f(jrced draught, as the heat 
 is more intense, the leakage is still further increased. 
 
 No. 75.— Capped Ferrule for Leaky Back Ends. 
 
 Collapsed Tubes. 
 
 For a collapsed tube the best repair is a permanent stopper (Sketch 
 No. 73), formed of a long rod screwed at the ends, and cap washers 
 fitting over the ends of the tube and screwed up tight with a joint 
 between the tube and the washers. Patent stoppers are also employed 
 to close up a cracked tube, the " Bagguley " type being shown in Sketch 
 No. 74. 
 
 Safety Valves. 
 
 To find the Load on any valve, multiply the valve Area by the 
 Pressure per square inch. 
 
 To find the Pressure per square inch, divide the Load on the 
 valve by the valve Area. 
 
 Example. — The Pressure is to be 40 lbs. per square inch and the 
 valve is 5 inches diameter, find the Load. 
 
 5- X -7854 X 40-785-4 lbs. load. 
 
 Example. — The Load on a dead-weight valve is 1000 lbs., and 
 
 the valve is 3 inches diameter ; find the blowing-off Pressure per 
 
 square inch. 
 
 1000 1. 
 
 -r, ^^—=141-4 lbs. pressure per sq. in. 
 
 3- X 7854 
 
Boilers 133 
 
 Iron Tubes and Stays. ** 
 
 In steel boilers the tubes and small stays are often made of iron, 
 for the reason that iron corrodes less than steel under corrosive 
 influences. 
 
 Leaky Tubes. 
 
 Owing to the tubes and tube plate expanding at different rates, 
 the back ends of the tubes often leak. This is remedied by re- 
 expanding, or by fitting into the tube at the back end a capped 
 ferrule as used in the Navy, to keep the heat off the tube end and 
 the plate (Sketch No. 75). Scale and soot on the tubes and plates 
 tend to increase the leakage, and with forced draught, as the heat 
 is more intense, the leakage is still further increased. 
 
 , [ovule 
 
 No. 75.— Capped Ferrule for Leaky Back Ends. 
 
 Collapsed Tubes. 
 
 For a collapsed tube the best repair is a permanent stopper (Sketch 
 No. 73), formed of a long rod screwed at the ends, and cap washers 
 fitting over the ends of the tube and screwed up tight with a joint 
 between the tube and the washers. Patent stoppers are also employed 
 to close up a cracked tube, the " Bagguley " type being shown in Sketch 
 No. 74. 
 
 Safety Valves. 
 
 To find the Load on any valve, multiply the valve Area by the 
 Pressure per square inch. 
 
 To find the Pressure per square inch, divide the Load on the 
 valve by the valve Area. 
 
 Example. — The Pressure is to be 40 lbs. per square inch and the 
 valve is 5 inches diameter, find the Load. 
 
 5- X .7854x40 = 785-4 lbs. load. 
 
 Example. — The Load on a dead-weight valve is 1000 lbs., and 
 
 the valve is 3 inches diameter ; find the blowing-off Pressure per 
 
 square inch. 
 
 1000 i. 
 = — =141-4 lbs. pressure per sq. in. 
 
 3- X -7854 
 
134 ■ "Verbal" Notes and Sketches 
 
 Lever Safety Valve. 
 
 ^ L ■ 
 
 ../ .. 
 
 ^C^ 
 
 No. 76. 
 
 NOTE. — A = valve Area, load = A x boiler pressure. 
 Then, LxW = /xload. 
 
 Therefore, =-^p!^ = load, and, -^ = pressure per sq. in. 
 
 . . / X load TTT / X load , 
 
 Again, ___ = W; or, _^__ =L. 
 
 \6 
 
 4'- 
 
 ^^V uvea. '^ 
 
 Example i. — 
 Rule — 
 
 Then, 
 
 No. 77. 
 
 16 in. X 100 lbs. =4 in. X Load. 
 16 in. X 100 lbs. 
 
 4 in. 
 
 = 400 lbs. Load, 
 
 and Pressure per sq. in = Load -^ Valve Area = 400 4- 10=40 lbs. per sq. in. 
 
 NOTE.— Valve area=io square inches. 
 
 In the foregoing case, the weight of the lever, and of the valve and 
 spindle, are neglected. If they are to be allowed for, the following 
 data must be given : — 
 
 1. Centre of gravity of the lever. 
 
 2. Weight of the lever. 
 
 3. Weight of the valve and spindle. 
 
 Example 2. — In the previous case the lever weighs 7 lbs., its 
 centre of gravity is 12 inches from the fulcrum, and the valve and 
 spindle weigh 5 lbs. ; find the load on the valve, and the pressure per 
 square inch, allowing for the lever and the valve and spindle. 
 
 12 in. X 7 lbs. lu J 1. t 
 
 ^'- =21 lbs. more due to lever. 
 
 4 in. 
 
 Then, 400 + 21 + 5 = 426 lbs. load, 
 
 and, -'L-- =42.6 lbs. pressure per sq. in. 
 
 10 in. 
 
 NOTE. — The centre of gravity is the point at which the lever balances if placed 
 on a knife edge. As the weight of the valve and spindle is direct weight, it is simply 
 added to the other two loads. 
 
Boilers 135 
 
 Example 3. — Fulcrum to Weight 30 inclics, fulcrum to Valve 
 5 inches, Load on valve 300 lbs. ; find Weight. 
 
 Then, Lx W = /x load = 3ox W = 5 X300. 
 
 Therefore, W = 4^ 300 ^ jj^^ ^ ^ 
 
 30 
 
 Examplf: 4. — Fulcrum to valve 6 inches, Weight 20 lbs., boiler 
 pressure 30 lbs. per square inch, valve area 4 square inches ; find the 
 Length from fulcrum to Weight. 
 
 Then, L xW = /x load = L x 20 = 6 x 120. 
 
 NOTE.— 4 X 30=120 lbs. load on valve. 
 
 Therefore, L = ^iii^=36 in. 
 
 20 ^ 
 
 Example 5. — Fulcrum to valve 6 inches, fulcrum to Weight 
 32 inches, Weight 25 lbs. ; find the boiler pressure per square inch 
 if the valve is 3 inches diameter. 
 
 Then, L xW = /x load = 32x25 = 6 x load. 
 
 Therefore, load = ?—^— 5=133.3 lbs. 
 
 Then, Pressure = load -f valve area = 133-3^ 3- x ■7854 = 18-8 lbs. per sq. in. 
 
 Spring Safety Valves. 
 
 At 60 lbs. gauge pressure, the Board of Trade allowance of safety 
 valve area is i square inch per square foot of fire-grate surface. 
 
 At higher pressures the valve area required is less, because high- 
 pressure steam has less volume than low-pressure steam, and at lower 
 pressures the valve area required is more. 
 
 To find the valve area per square foot of grate for, say, 160 lbs. 
 gauge pressure, 60 -f 15 =75 lbs, gross, and i6o-|- 15 = 175 lbs. gross. 
 
 Then, as 175 lbs. : 75 lbs. : : -5 in. = -214 of a square inch. 
 
 NOTE.— In working out valve areas, the gross pressure must be taken. 
 
 The lip cast round the safety valve face is to give an increase of 
 valve surface when the valve lifts, so that the extra compression of the 
 spring, due to the lift, may be neutralised. Without this fitting, the 
 boiler pressure would increase with the valve lift. 
 
 To find the Compression. 
 
 Rule — 
 
 Load on valve x Sp rin g mean diameter^ x Number of coils _ r omoression 
 2000000 X steel 
 
136 "Verbal" Notes and Sketches 
 
 Example. — Find the compression required for a 4-inch safety 
 valve, pressure 160 lbs., and mean diameter of spring 3^ inches : there 
 are thirteen coils of square steel of f inch side. 
 
 4l^7854 xi6ox3.5x3.5x3.5xi3 ^^.yyi„ compression. 
 2000000 X 75 X 75 X 75 X 75 
 
 The pressure per square inch varies as the compression of the 
 spring. 
 
 Example. — The pressure is 160 lbs. per square inch, and the 
 compression is 2 inches ; find the compression and thickness of the 
 washer required to be put in to have the valve blowing off at 1 50 lbs 
 per square inch. 
 
 As 160 : 2 in. : : 150= 1-875 in. compression. 
 Then, 2 in. - 1'875 in, = '125 of an inch thickness of washer to go in under th< 
 compression nut. 
 
 NOTE.— The compression varies directly as the pressure. 
 
 To find the Diameter of Safety Valve. 
 
 / 
 
 Square feet of grate x 37.5^^.^^^^^^ ^^ ^^j^^ 
 gross pressure x 7854 
 
 NOTE. — If for forced draught allow about 25 per cent, more area of valve. 
 
 The Constant 37-5 is obtained by multiplying the valve area allowed 
 at 60 lbs. gauge pressure by the gross pressure corresponding to it. 
 
 Thus, 60 + 15 = 75, and 75 X .5 = 37.5. 
 
 Superheated Steam. 
 
 Of late years a decided reaction has set in among marine engineers 
 in favour of superheated steam, which, as proved conclusively by 
 recent exhaustive experiments, possesses undoubted advantages, and 
 the use of which results in considerable economy. It has been found 
 that with superheating to the extent of 50" the gain is about 8 per 
 cent., and if the superheat is increased to 200° above the natural 
 pressure temperature of the steam, then the resulting economy is 
 about 30 per cent. 
 
 It should be noted that if saturated steam — that is, steam drawn 
 from a boiler — is raised in temperature and the pressinr kept constant, 
 the volume increases ; this means a larger volume of steam produced 
 for the same amount of water evaporated, and therefore less boiler 
 space required. Again, by superheating steam which originally 
 contains water, the water is evaporated, thus giving drier steam, which 
 results in less cylinder condensation losses, and less transfer of heat 
 
 I 
 
Boilers 137 
 
 to the cylinder walls. It will thus be seen that the advantages of 
 superheated steam are undoubted. 
 
 NOTE. — The volume varies with the absohite temperature if the pressure is 
 kept constant. 
 
 Example. — Boiler steam (saturated) at a pressure of 180 lbs. 
 gauge pressure, temperature of 380", and specific volume 2-31 cubic 
 feet ; find the volume if the steam is superheated 100" Fahr. 
 
 Then, 380° + 100 = 480" steam temperature when superheated. 
 And, 461=^ absolute temperature constant. 
 
 Therefore, as, (380° + 461°) : (480° + 461°) : : 2-31 = 2-58 cubic feet volume. 
 
 So that the volume of the steam per pound is now increased by 2-58 -2-31 = 
 •27 of a cubic foot. 
 
 In addition to this it must be remembered that the temperature is 
 higher, and the steam of a drier condition. 
 
 Advantages of Superheated Steam. 
 
 (i.) Increase of steam volume. 
 
 (2.) Dry steam enters the cylinders, and less condensation losses 
 result. 
 
 (3.) Less leakage of steam past valves and pistons. 
 
 (4.) Less danger from water hammer in main steam pipes or chests. 
 
 Against these gains there are, however, certain disadvantages, 
 which also require to be taken into account. 
 
 Disadvantages of Superheated Steam. 
 
 (i.) Difficulty of lubrication. 
 (2.) Piston nngs more easily broken. 
 
 (3.) Trouble experienced in keeping superheater coils or tubes 
 tight and in good working order. 
 
 Methods of Superheating. — In marine practice the ordinary 
 method has been to utilise the funnel gases in superheating the steam, 
 although the independently fired type as devised by Professor 
 Watkinson has also been fitted in some steamers. 
 
 The Watkinson superheater (Sketch No. 78) consists of a series of 
 U-shaped mild steel tubes, expanded into large headers similar to those 
 employed in water-tube boilers. This nest of tubes is fitted in tiie 
 uptake, and the steam from the boiler enters one of the headers, and 
 passing through the U-shaped tubes becomes superheated by the 
 furnace gases which are flowing over the tubes. The steam then 
 enters the other header and flows along the steam pipe to the engine. 
 
138 
 
 " Verbal " Notes and Sketches 
 
 Suitable drainage arrangements are fitted to keep the drums and 
 tubes clear of water, and by suitable bye-pass valves and pipes thej 
 steam may, if required, pass direct from the boilers to the engine 
 without entering the superheater coils. 
 
 When it is stated that the average loss due to initial cylinder con- 
 densation is about 15 per cent, with saturated steam, the advantage ol 
 superheated or dry steam will be apparent, as less water being present 
 
 No. 78. — "Watkinson" Type Marine Superheater. 
 
 in the steam the condensation losses are greatly reduced, and may be 
 practically eliminated. 
 
 To overcome the lubrication difficulty, special high temperature 
 mineral oils are now manufactured by the various oil companies, 
 which are said to resist the disintegrating effects of the superheated 
 steam, and allow of suitable lubrication of rods, pistons, and valves. 
 
 Regarding the resulting increase of volume due to superheating 
 Professor Watkinson says : " During superheating, although the 
 
Boilers 139 
 
 pressure of the steam remains constant, its volume is greatly in- 
 creased. The amount of heat required to superheat i lb. of steam 
 by 150° Fahr. is 72 British heat units, which is only about 6 per cent, 
 of the heat required to generate I lb. of dry saturated steam. The 
 increase in volume due to this additional 6 per cent, of heat averages 
 about 30 per cent." 
 
 Steam Pipes. 
 
 Steam pipes are made of the following materials : — 
 
 1. Copper, seamless or brazed. 
 
 2. Wrought iron, generally lap welded. 
 
 3. Steel, also lap welded. 
 
 Sometimes in steel pipes a riveted butt strap is fitted covering the 
 weld, and copper pipes are further strengthened by being covered 
 with wrappings of wire rope, or by iron bands secured at short 
 distances along the pipe. Cast iron also, in a few cases, has been 
 used for steam pipes. 
 
 The three principal causes of recent accidents to steam pipes were — 
 (l) Insufficient allowance for expansion ; (2) defective drainage 
 arrangements; and (3) vibration. 
 
 Before opening the main stop-valves the drains on the pipes 
 or chests should be opened to clear away all water which may have 
 collected in them. 
 
 When steam pressure strikes a body of water it imparts to the 
 water a velocity nearly equal to its own, and the resulting force 
 acquired is so great that the chest or pipe may be burst : this is known 
 as " water hammer," and accounts for many of the accidents to steam 
 pipes and stop-valve chests ; hence the necessity for drain cocks being 
 fitted and used. 
 
 Water Hammer in Steam Pipes. — Whenever possible water lodging 
 in steam pipes should be drained out when the steam pressure is off, 
 otherwise the draining out of the water may result in the setting up 
 of water hammer action with danger of bursting the pipe or valve 
 chest. 
 
 According to Mr C. E. Stromeyer of the Manchester Steam Users 
 Association, the conditions favourable to water hammer are as 
 follows : — ■ 
 
 1. Water in contact with steam. 
 
 2. Rapid condensation in pipes or chests. 
 
 3. Agitated water surfaces. 
 
 4. Steam pressure at one part of a pipe and vacuum at another 
 part. 
 
 Under ordinary practical conditions the pressure per square inch 
 on a pipe produced by water hammer may range from 250 lbs. to 
 300 lbs., or even more. 
 
I40 
 
 " Verbal ' Notes and Sketches 
 
 i^ 'm^" 
 
 « 
 
 No. 79. — Steam Pipe Expansion Joint. 
 
 NOTE. — When no expansion joints are fitted on steam pipes, bends are formed on 
 the pipes to allow for expansion. 
 
 Circulation and Priming. 
 
 Circulation in a boiler is the rising of the heated and expanded 
 water, and the sinking of the colder and heavier water to take its 
 place, resulting in a continuous current passing from the bottom 
 upwards, and from the top downwards. 
 
 Wiien water is heated it becomes lighter, and expanding, rises 
 to the top in the form of small steam bubbles, which, on reaching the 
 surface, burst and give off a small amount of steam, and, if the boiler 
 is properly designed, the colder water being heavy falls, and in its 
 turn becomes heated. 
 
 Should insufficient allowance be made for the circulation, or 
 anything occur to check it, priming will most likely begin, as priming 
 is caused by bad circulation. 
 
 Defective circulation may be caused by : — 
 
 1. Close arrangement of tube nests, 
 
 2. Small steam space, 
 
 3. Dirty water, 
 
 4. Bad firing. 
 
 Observe that any of the foregoing causes bring about bad circula- 
 tion, and consequently priming. 
 
 The bottom seams of the boiler sometimes leak owing to the 
 difference of temperature existing between the top and bottom caused 
 by defective circulation. The top plates being hotter, and expanding 
 more in proportion, tend to drag open the bottom seams, and leakage 
 is the result. 
 
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 \ TUBE PLATE 
 
 No. 8i. -"Doubling" Plate. 
 
 No. 82. — End View of Boiler Half in Section. 
 
Boilers 
 
 141 
 
 No. 80.— Weir's Patent Hydrokineter. 
 
 In getting up steam, circulation is assisted by means of a 
 hydrokineter (Sketch No. 80), or by the donkey connection for 
 pumping the water from one part of the boiler to another (see 
 page 151). 
 
 Doubling Plates. 
 
 Doubling plates, as shown in Sketch No. 81, are sometimes fitted 
 to boilers to increase the strength of flat surfaces in places where 
 ordinary stays or stay tubes cannot be fitted. The plate shown is 
 about 1^ inch thick, and is riveted to the boiler end plates in the spaces 
 between the tubes. Stays are not admissible at this part of the 
 boiler owing to the necessity for keeping clear the spaces between the 
 tubes to allow of the furnaces being examined, cleaned, or repaired, 
 so that the only alternative method of support is by means of 
 doubling plates. 
 
 End View (Sketch No. 82). 
 
 The sketch shows the general construction of a modern high- 
 pressure boiler, as seen half in section from the end. Observe how the 
 combustion chamber tops are supported by the "dogs," or girders, 
 and stays passing through which are tapped into the top plates. 
 
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 'I'o face page 141. 
 
Boilers 
 
 141 
 
 No. 80. — Weir's Patent Hydrokineter. 
 
 In getting up steam, circulation is assisted by means of a 
 hydrokineter (Sketch No. 80), or by the donkey connection for 
 pumping the water from one part of the boiler to another (see 
 page 151). 
 
 Doubling Plates. 
 
 Doubling plates, as shown in Sketch No. 81, are sometimes fitted 
 to boilers to increase the strength of flat surfaces in places where 
 ordinary stays or stay tubes cannot be fitted. The plate shown is 
 about l inch thick, and is riveted to the boiler end plates in the spaces 
 between the tubes. Stays are not admissible at this part of the 
 boiler owing to the necessity for keeping clear the spaces between the 
 tubes to allow of the furnaces being examined, cleaned, or repaired, 
 so that the only alternative method of support is by means of 
 doubling plates. 
 
 End View (Sketch No. 82). 
 
 The sketch shows the general construction of a modern high- 
 pressure boiler, as seen half in section from the end. Observe how the 
 combustion chamber tops are supported by the "dogs," or girders, 
 and stays passing through which are tapped into the top plates. 
 
142 
 
 "Verbal" Notes and Sketches 
 
 The following are the principal dimensions to be carefully noted : — 
 
 Pitch of girders, about 8 inches. 
 Depth „ „ 9 inches. 
 
 Distance between combustion chamber plates, about 7 inches. 
 
 „ ,, combustion chamber and boiler shell, about 7 inches. 
 
 „ ,, furnace and bottom of boiler, about 7 inches. 
 
 „ „ bottom row of tubes and furnace top, about io| inches. 
 
 „ ,, each nest of tubes, about 11 inches. 
 
 Observe how the plate at the sludge hole openings is strengthened 
 by means of the stays shown, which pass from end to end of the 
 boiler, the top one being heavier than the lower two. 
 
 These stays are usually about if inches or 2 inches diameter. 
 
 Also note the arrangement of the stay tubes, which are indicated 
 by dark circles. 
 
 NOTE. — The manhole opening in the shell (about 16 inches x 12 inches) is 
 strengthened by means of a doubling or "compensating" ring riveted to the plate 
 round the hole. The effective surface area of this ring should not be less than the 
 area of the metal cut away to form the opening. 
 
 Scarfed Joints. — This type of joint is used in boilers where three 
 plates overlap each other, as for example when two end plates and the 
 shell overlap. Two of the plates are scarfed or thinned down, as 
 shown in the sketch, and the third plate covers both ; this reduces the 
 thickness to that of only two plates. Extra heavy caulking is 
 required to keep the joint tight. 
 
 CAULKE 
 SHELL PLATE M 
 
 END PLATE 
 SCARPED 
 
 END PLATE 
 
 No. 83.— Scarfed Joint. 
 
 SINGLE _ 
 CAULKING 
 
 SINGLE^ 
 CAULKING 
 
 No. 84.— Flanged-out Plates. 
 
 I 
 
Boilers 
 
 143 
 
 Flanged-out Plates. — Sometimes one end of the boiler is flanged 
 outwards, as shown, to allow of the convenience of the hydraulic 
 riveting machine. The disadvantage of this arrangement lies in the 
 fact that only single caulking is possible, whereas with the plates 
 flanged inwards double caulking can be employed. 
 
 Zinc Plates. 
 
 The sketches show the usual methods of connecting the zinc slabs 
 to the boiler metal, and it is important that the following points be 
 attended to : — 
 
 (i) Proper metallic contact between the zinc and the boiler, and 
 to ensure this the surfaces in contact should be filed up bright. 
 
 IX 
 
 No. 85. 
 
144 
 
 " Verbal " Notes and Sketches 
 ^^^ - — ^r 
 
 ZINC 
 
 - -> — 
 
 "7 -^J 
 -y — 
 
 (D 
 
 -^ 
 
 No. 86.— Zinc Block and Stud. 
 
 The zinc plates fitted into boilers to set up galvanic action 
 and reduce corrosion are usually fixed to the furnaces, com- 
 bustion chambers, and end plates as shown, the stud being 
 screwed in to form effective metallic contact. 
 
 ZINC 
 
 ?>f7 77r7r7777mi. 
 
 No. 87.— Zinc Plate in Box. 
 
 In water-tube boilers the zinc plates are often carried in 
 perforated boxes, the idea being to prevent the oxide of zinc 
 (produced by the galvanic action) from being distributed over 
 the boiler. The oxide drops to the bottom of the box, and is 
 thus kept by itself. 
 
Boilers 145 
 
 (2) When convenient the removal of scale or oily deposits from 
 the zinc plate connections, as these substances insulate the parts and 
 interrupt the flow of the current. 
 
 (3) The renewal of the zinc slabs whenever they are found to have 
 become spongy, as the galvanic action is then practically exhausted. 
 
 When the zinc is suitably connected as above described, the 
 chemical action which occurs results in the formation of Oxide of 
 Zinc and the liberation of bubbles of Hydrogen Gas. At the zinc 
 plate Oxygen is set free and combines with the zinc, and at the boiler 
 metal Hydrogen Gas is set free. 
 
 NOTE. — As the proportion of zinc used is very small compared with the 
 amount of boiler metal to be protected, the corrosion is merely reduced in extent, 
 and is not prevented altogether. 
 
 The usual allowance of zinc is about one square foot, inch thick 
 per each 80 I.H.P. 
 
 Water Gauge. 
 
 In Fig. I the column shown is hollow cast, so that the water or the 
 steam could pass through it : the test cocks show this. 
 
 NOTE.— Open the drain and blow through, then close the drain and see if the 
 water rises to the working level ; if so, the connections are all clear ; if, however, no 
 water shows, then either C or D is choked or the water is too low ; if, on the other 
 hand, the glass shows full, then either A or B is choked or the water is too high. 
 
 To test if the steam connections are clear, shut cocks C and D, and 
 have open cocks A, B, and the drain cock E. If steam blows through 
 the cocks are clear. 
 
 To test if the water connections are clear, shut cocks A and B, and 
 have open cocks D, C, and the drain cock E. If water blows through, 
 the cocks are clear. 
 
 If cock A or cock B is choked, the glass will show full up. It will 
 show the same if the pipe between A and B is choked. 
 
 If cock C or cock D is choked, the glass will continue to show 
 what the water level was at the time the cocks stuck, as the water will 
 be shut off from the boiler altogether. If the drain is opened and 
 shut, the glass will show empty as long as the cocks remain choked. 
 The same thing will happen if the pipe between C and D is choked. 
 
 If the glass is showing full water, due to the cock A, or the cock 
 B, having got choked, to test if it is A, shut D and B and blow through 
 A, C, and E ; if steam blows out A is clear, if not, A is stuck. To 
 test B, shut A and C and blow through D, B, and E ; if water blows 
 out, B is clear, if not, B is choked. 
 
 If one of the two cocks C and D is choked, to find which it is, shut 
 A and C and blow through D B and the drain E ; if water blows out. 
 
146 
 
 "Verbal" Notes and Sketches 
 
 I. Fig. 2. 
 
 No. 88. 
 
 D is clear, if not, D is choked. To test C, shut D and B and blow 
 through A, C, and E ; if steam blows out, C is clear, if not, C is choked. 
 
 NOTE. — In testing, before closing any of the cocks A, B, C, or D, it is advisable 
 to 6rst open the drain cock E, so that shocks on the pipes and glass may be avoided. 
 
 If cocks A and B are closed and the others left open and the glass 
 blown through, if water comes, the water connections are clear : if, next, 
 cocks C and D are closed and the glass blown through with cocks A 
 and B open so that steam comes, the steam connections are clear ; but 
 if, on shutting the drain cock, no water shows in the glass, this proves 
 that the water level in the boiler is too low, as it must be lower than 
 the bottom nut of the gauge glass, otherwise the glass would show 
 water. 
 
 If the gauge column is cast solid as shown in Fig. 2, then the 
 water or steam could not pass through it, and to test the water and 
 the steam, single shutting off on the column is sufficient. 
 
 To test the steam side, shut cock C, and leave cocks A, B, and the 
 drain cock E open ; if steam blows out, the connection is clear. To 
 test the water side, shut cock B and blow through cocks D, C, and the 
 drain cock E ; if water blows out, the connection is clear. 
 
 The glass usually shows from ih inches to 2 inches less than the 
 boiler level, the reason for this being that the water in the glass is 
 colder than the water in the boiler, and, as water contracts in cooling, 
 the level is lower in proportion. 
 
Boilers 
 
 146a 
 
 No. 88a. 
 
 No. 88b. 
 
 Tait's Patent \Vater Circulator, showing its Application 
 to Marine Boilers. 
 
1463 " Verbal " Notes and Sketches 
 
 Tait's Patent Water Circulator. 
 
 The inner side of each plate is constructed with projections which 
 fit closely into the corrugations of the furnace, so as to be as nearly 
 as possible water-tight, and thus secure the maximum of rapid 
 heating. 
 
 The lower part of the circulator projects beyond the body of 
 the boiler as low as practicable, in order to reach the water at its 
 coldest temperature in the bottom. 
 
 Over the top of the furnace the two sides of the circulator 
 
 are held in position by a plate which is raised some 3" above, 
 
 and serves to break the rise of the superheated water, throwing 
 it out on both sides. 
 
 The use of this invention secures a steady and continuous cir- 
 culation of the water from the bottom of boilers when under fire. 
 The result is attained by controlling the rapid convection currents 
 which are created by the superheated water, so that a continuous 
 inflow is being drawn up from the coldest level of the water, below 
 the furnace, instead of being allowed to flow in from the nearest 
 point. 
 
 The circulator really forms a saddle boiler, which is placed over 
 the boiler at the hottest part of the furnace. 
 
 Its width is limited by the size of the manhole, generally running 
 from 11" to 15" over all, according to circumstances and the type 
 of furnace. 
 
6o 
 
 lbs. 
 
 gauge 
 
 So 
 
 
 
 lOO 
 
 
 
 150 
 
 
 
 160 
 
 
 
 180 
 
 
 
 200 
 
 
 
 250 
 
 
 
 Boilers 147 
 
 Boiling Points and Steam Temperatures. 
 
 Fresh water boils at a temperature of 212" under the atmospheric 
 pressure. 
 
 In a good vacuum water will boil at a temperature of 90^ while 
 under a pressure of 160 lbs. gross, the boiling point of fresh water 
 would be 370". Therefore the boiling point depends on the pressure 
 on the surface of the water and varies accordingly, being high for 
 high pressures, and low for low pressures. 
 
 At 15 lbs. atmospheric pressure the temperature is 212° Fahr. 
 
 » ). .. 307] 
 
 >> )) )) 3^4 
 
 » 5> )> 338 
 
 » )> „ 366° 
 
 » » „ 370° 
 
 » 5» )) 380° 
 
 »> J> )) 388 
 
 >> )> )> 405 
 
 NOTE.— The temperature of the water is the same as that of the steam. 
 
 Salinometer, Density, &c. 
 
 The salinometer measures the density of the boiler water. 
 
 The salinometer does not in all cases measure the amount of salt 
 in the water. 
 
 If we take 32 lbs. of sea water and boil off all the water, about 
 I lb. of solid matter will be left behind, hence the figure ^^-i. 
 
 A gallon of water weighs about 10 lbs., and 10 lbs. x 16 oz.= 160 
 oz., therefore i6o-r 32 = 5 oz. of solid matter per gallon. 
 
 Of the 5 oz. of solid matter in i gal. of sea water, fully 4 oz. 
 are salt and the rest lime, &c. 
 
 The temperature marked on the salinometer is 200" Fahr., and 
 if the water cools down below this, the salinometer will show more 
 density in proportion to the drop of temperature, because water 
 contracts in volume when cooling down to 39° Fahr. 
 
 For every lo"" less temperature, allow the salinometer to be 
 showing f oz. more than the actual density. 
 
 Thus, suppose the water cools to 160", that is 40" lower than it 
 should be, then the salinometer would indicate about 3 oz. in excess 
 of the real density, which amount would require to be subtracted from 
 that shown by the salinometer to obtain the correct density. 
 
 Water is at its least volume at 39", and expands if heated above 
 this temperature, or if cooled below it. 
 
 Ordinary sea water at a temperature of 50^ will show on the 
 salinometer as fully 13 oz. density. 
 
 NOTE. — Salt and sugar will show on the salinometer as density, as these 
 substances enter into solution. 
 
 To make a rough salinometer, take a long, narrow bottle, weight 
 it and cork it ; take a gallon of fresh water and heat it to 200° ; put 
 in the bottle and mark where it floats o, or fresh water : next take 
 
148 
 
 Verbal " Notes and Sketches 
 
 a gallon of sea water, heat it to 200 , and mark where the bottle 
 floats TjV, boil down the water to half a gallon, and when it cools down 
 to 200'' put in the bottle a third time, and mark where it floats ^"2, 
 or 10 oz. ; other densities may be set off by evaporating the water 
 away to one-third and one-fourth the original quantity. 
 
 To test the density without a salinometer, draw off some of the 
 boiler water and boil it over a fire ; when boiling, put in the thermo- 
 meter and observe the temperature ; the density may then be roughly 
 found by means of the following table : — 
 
 Fresh water boils at 
 
 5 oz. density 
 
 15 .. 
 
 20 ,, ,, 
 
 212 
 213-2° 
 214-4° 
 215-6° 
 217-8° 
 
 Allow 216° as the limit temperature, corresponding to about 15 oz. 
 density : should the boiling point exceed this, surface the boiler to 
 keep down the density. * 
 
 NOTE.— The above boiling points correspond to a barometer height of 30 inches. 
 The boiling point varies with the barometer, up and down ; for every inch difference 
 in the barometer, the boiling point varies 1-5° in temperature. 
 
 If the boiler retains a density of 35 oz. (saturation point) and more feed water 
 containing salt is supplied, then when the water fed in is evaporated, the salt contained 
 in it deposits. 
 
 MAIN STAY 
 
 IRON CLIPS 
 
 9" 3" 
 
 internal 
 feed pipe 
 (iron) 
 
 No. 89.— Method of Supporting Internal Feed Pipes. 
 
 See's Ash Ejector. 
 
 See's ash ejector consists of a cast-iron hopper with a grating for 
 limiting the size of the ash or clinker put in, a water nozzle and pipe 
 led up to the ship's side above the water level, and a cock to regulate 
 the flow. A high-pressure donkey pump connection is also required 
 
 * NOTE. — For accuracy, it is advisable to first boil fresh water and note the 
 boiling point, then allow 1-2 degrees per 5 oz. for the boiler water boiling point 
 excess. 
 
Boilers 
 
 149 
 
 No. 90.— See's Ash Ejector. 
 
 W, Hopper. 
 
 P, Combined ejector cock, nozzle, 
 
 and escape valve. 
 M, Pressure gauge. 
 
 T, Air inlet valve. 
 
 S, Removable cover. 
 
 V, Discharge pipe. 
 
 Z, Ship's side valve. 
 
 to obtain the necessary force of water pressure. Before opening the 
 ejection cock it is necessary that the water pressure of the pump be 
 not less than 200 lbs. per square inch, as shown by the gauge, also 
 that the valve on the ship's side is full open. When the cock is 
 opened the rush of water at high pressure past the grating carries 
 with it the ashes shovelled through, and discharges them overboard. 
 A small air valve is fitted on the pipe, and this must be kept open 
 when working the ejector. 
 
 Tube Expander (Sketch No. 91). 
 
 The expander consists of a built-up case containing three rollers 
 which project through corresponding openings cut in the shell of the 
 
z 
 o 
 
 to 
 a 
 
 t 
 
 "^ 
 
 
 -,f 
 
 lit ' 
 
 1 
 
 
 1 
 
 1 
 
 N|«0 
 
 V 
 
 
 
 CM 
 
 1 
 
 
 
 "IT 
 
 
 
 
 -|CJ 
 
 
 
 
 :»_ 
 
 
 
 
 1 
 
 f- 
 
 ^ 1 
 
 
 -|CM 
 
 .__i 
 
 Ui 
 CTS 
 
 a 
 
 X 
 
 Ul 
 
 a; 
 
 H 
 
 6 
 
 :z; 
 
Boilers 
 
 151 
 
 case. A taper mandril fits into the centre space of the rollers, and, on 
 being knocked in witii a hammer and revolved by a bar at the end, 
 forces out the rollers against the tube and tube plate, thus forming 
 a steam and water tight joint. In adjusting the position of the 
 expander care should be taken that the rollers are in line with the 
 tube plate, as otherwise the tube may leak, and, in addition, fracture 
 may result owing to the tube being unduly stressed by the rollers 
 acting at the wrong position. 
 
 All boiler tubes are expanded as described, with the exception of 
 the heaviest pattern of stay tubes, which are caulked in, the expander 
 being in this case too light for the work. 
 
 No. 92.— Blow-off and Circulating Connections. 
 
 1, Bottom blow-off valve. 3, Bottom blow-off pipe. 
 
 2, Ship's side blow-off cock (two-way). 4, Surface blow-off pipe. 
 
 S, Donkey suction pipe for circulating. 
 
 The above is a common arrangement of surface and bottom 
 blow-off combined with the donkey circulating connection. 
 Pipe 5 leads to the donkey pump suction valve, and the colder 
 water lying at the bottom of the boiler can thus be pumped out, 
 and discharged back into the boiler through the check valve. 
 
152 
 
 " Verbal " Notes and Sketches 
 
 To Cut out a Boiler Tube. 
 
 The usual method of removing a defective tube is illustrated in 
 the sketch, and may be described as follows :— The beading at the 
 
 1$^ 
 
 < 
 oo 
 
 H 
 
 u 
 
 o 
 CQ 
 
 bo 
 
 a 
 
Boilers 
 
 153 
 
 back end of the tube is first cut off flush with the plate, and the 
 tube end cut or ripped in three or four places. The end tlius cut 
 up is then hammered inwards, and the bar or rod passed throut^h 
 the tube, with a strong washer fitted in position over the tube end, 
 the washer diameter being of course less than the diameter of the 
 hole. At the front end a dog is fitted as shown and a screwing-up 
 nut ; if the bar is then held by the square on the end, and the nut 
 tightened up, the tube will, in most cases, be started and finally 
 drawn out. 
 
 I 
 
 No. 94.— Klinger " Reflex " Water Gauge. 
 
 Klinger Patent Water Gauge. 
 
 In this admirable form of water gauge the chief improvement 
 consists in the water and steam being shown in striking contrast to 
 
154 "Verbal" Notes and Sketches 
 
 each, the water in the glass appearing dark and the steam light ; the 
 water level can thus be read at some distance away from the gauge. 
 
 In the " Klinger " water gauge a metal casing connects the top and 
 bottom cocks, and a window of thick and strong glass inserted in the 
 casing allows of the reading of the water level. This window takes 
 the place of the fragile glass tube commonly fitted. 
 
 The observation glass or window being corrugated vertically at the 
 back, reflects the light in that part of the gauge which contains the 
 steam, whereby this part of the glass becomes opaque and of a bright 
 lustre. 
 
 In that part of the gauge containing the water the light is not 
 reflected, but passes in a slight deflection to the rear of the gauge. 
 
 The glass being thus transparent in this part of the gauge, the 
 water will appear of the dark colour of the background of the casing, 
 in other words the water appears black, while the steam shines with 
 a silvery lustre. This, it must be admitted, is a vast improvement 
 over the ordinary glass, in which if any distance away it is often very 
 difficult to determine whether full of water or empty altogether. 
 
 A further advantage of the " Klinger " type of water gauge is the 
 elimination of stuffing boxes at the top and bottom of the glass, which 
 is in itself a consideration of some importance to practical men. 
 
 Auld's Patent Steam Reducing Valve. 
 
 The inflowing steam is admitted between the valve and a piston, 
 covered by an elastic disc. 
 
 The piston and the valve are in equilibrium on the high-pressure 
 side. 
 
 The reduced pressure on the outlet side is obtained by compressing 
 or relaxing the spring by the adjusting screw until the pointer or 
 spring cap is opposite the figure on index plate representing pressure 
 wanted. The valve being thus opened, the steam flows through valve 
 to low-pressure side of same, until the pressure on reduced 
 side balances the load on the spring by pressing on top side 
 of valve, and so regulating the reduced pressure to the point desired. 
 
 A column of water of condensation, shown by dotted lines, is 
 interposed between the steam and the elastic disc. 
 
 Should it be desired to obtain steam (the reverse way through 
 reducing valve) from donkey boiler for deck or engine-room 
 
Bolle 
 
 rs 
 
 155 
 
 machinery, when there is .no steam in main boilers, open up the 
 reducing valve by compressing the spring by means of tlie adjusting 
 
 JAM NUT 
 
 WASHER 
 INDIA RUBBU DISC 
 
 PISTON SEAT 
 
 BOSS NUT 
 
 I -4-4-ADJUSTING SCREW 
 
 No. 95.— Au Id's Patent Steam Reducing Valve. 
 
 screw till the reducing valve opens ; of course, reset the reducing valve 
 to its usual working pressure on reduced side before getting up steam 
 in the main boilers. 
 
 NOTE. — A reducing valve will pass steam of lower pressure than it is set for, 
 but will not pass steam of higher pressure. 
 
156 
 
 "Verbal" Notes and Sketches 
 
 • 
 
 Jl 
 
 • 
 
 _li ' 
 
 r -\\ 
 
 ^ 
 
 • 
 
 r i\ 
 
 r 
 
 • 
 
Boilers 
 
 157 
 
 Boilers Secured in Position (Sketch No. 96). 
 
 The boilers rest on stools (which, if required, are wedged as 
 shown at C, C), and are prevented from moving longitudinally by 
 knees K, which are riveted or bolted to the ship's frames, clearance 
 being left (about } inch) between the boiler ends and the knees for 
 fore and aft expansion. 
 
 Side stays B are fixed by eyes and pins to brackets riveted to the 
 boiler shell, and block stays S are often fitted in between the boilers 
 at the centre. The pins and eyes of the side stays B allow for 
 expansion under heat. 
 
 Table giving Results of a few Experiments with Auld's Patent 
 Steam Reducing Valve, showing how much the Reduced 
 Pressure Steam is Superheated in passing through the 
 Valve. 
 
 Gauge 
 Pressure. 
 
 Temperature. 
 
 Reduced 
 Pressure. 
 
 Temperature. 
 
 Superheat. 
 
 160 lbs. 
 160 ,. 
 
 200 ,, 
 200 ,, 
 200 ,, 
 
 370° 
 370° 
 384° 
 384° 
 384° 
 
 100 lbs. 
 
 40 V 
 
 120 ,, 
 
 40 „ 
 10 „ 
 
 349° 
 338° 
 369° 
 354° 
 341° 
 
 12° 
 
 20° 
 
 68° 
 128° 
 
 Autogenous Welding. 
 
 The writer is indebted to the British Autogenous Welding Com- 
 pan\', Ltd., for the following description of their system of welding : — 
 
 The main application of this new method of repair, known under 
 the name of Autogenous Welding, by means of the oxy-acetylene 
 blowpipe, is in repairing cracks and corrosions in marine boilers, 
 doing away with the old and unsatisfactory patching, and, in a great 
 many cases, saving the whole boiler from being scrapped ; as, if the 
 boilers are systematically kept in rejiair by this process, they will 
 remain in good condition for a number of years longer than would be 
 the case otherwise : stems, stern posts, rudder posts, and rudders can 
 be repaired by the same method. 
 
 The plant employed to carry out these repairs, known as a high 
 pressure plant, consists of a cylinder of acetylene and one of oxygen, 
 a regulator and length of tubing for each of the gases, and an oxy- 
 acetylene blowpipe as shown in Sketch No. (^y. 
 
 12 
 
158 
 
 "Verbal" Notes and Sketches 
 
 No. 97.— Autogenous Welding Apparatus. 
 
 For this class of work this plant has great advantages over any- 
 other plant, which would, of necessity, have to be of the low pressure 
 type in which an acetylene generator is used, when there would be 
 risk of leakage caused through too fast generation or upsetting. 
 
 The high pressure plant, when work is being done inside a 
 furnace, is taken into that furnace, thus, being out of the way of any 
 one working in the stokehold, this is a decided advantage when a 
 ship is in port for a short time only and a lot of work has to be got 
 through. 
 
 Besides the above-mentioned advantage over the low pressure 
 system there are several others, such as safety, high efficiency caused 
 through having both gases under about the same pressure, thus getting 
 
Boilers 
 
 159 
 
 a very intimate mixture and the gas being better purified, easy adjust- 
 ment of tlie flame, and the simple construction of the blowjjipe, there 
 being nothing to go wrong inside it, and the h'ghtness and balance of 
 the same, which is very important when it is considered that a man 
 has frequently to work in a very strained position, the work being done 
 on the horizontal, vertical, or overhead, it being immaterial, provided 
 he can get his blowpipe flame to play on the correct place ; in some 
 cases, in fact, a man cannot see directly what he is doing but has to 
 work more or less by feel, and makes as good a job as if it was 
 perfectly easy to get at. 
 
 For this process of repair the men employed must, when not 
 actually at work on board ship, be kept practising in the shops on an 
 old boiler, and no new man should be put to work on a ship before 
 he has had some months' tuition and practice in the shops ; practice 
 on lighter work is of no use whatever, in fact, if anything, it is detri- 
 mental to good work on heavy work, and all ship work comes under 
 this class. 
 
 As mentioned earlier, the main faults in boilers are found in 
 cracks and corrosions : we will discuss the former first, giving a few 
 sketches and showing the method of repair. 
 
 Cracks are usually found in the furnaces on a belt of from 4 to 
 8 inches wide, a short distance above the fire-bars, and running the 
 whole length of the furnace. 
 
 If there are only one or two, each one is cut out, as shown in 
 No. 98, to a V shape, new metal is then added from a rod of Swedish 
 
 No. 98. 
 
 iron by the welder, who holds his blowpipe in one hand and this iron 
 in the other, adding it drop by drop to the molten mass at the tip of 
 the flame ; if he does not get the original plate properly molten before 
 adding new metal he will not make a weld, and the crack will open 
 on cooling. Other positions in which cracks are to be frequently 
 found are in the landing edges of the furnaces and combustion 
 chamber plates running inwards from the edge of the plate into the 
 
i6o 
 
 " Verbal " Notes and Sketches 
 
 rivet holes and sometimes beyond ; these cracks are repaired in the 
 same way as furnace cracks, only great care must be taken not to 
 weld the top plate to the one underneath, if this is done endless 
 trouble will be caused. 
 
 In some cases there are a number of cracks within a small area ; 
 it is then advisable to cut out the whole of the affected part and 
 weld in an entirely new piece of plate. In case of a furnace with 
 thickened ribs it is an easy matter to build up the new plate to the 
 correct shape as shown in No. 99, the new metal being shown by 
 
 No. 99. 
 
 the dotted lines and shaded portions. Corrosion usually takes place 
 in the same region in a furnace as cracks, that is, in a belt 4 or 
 8 inches wide, a short distance above the fire-bars, extending the 
 whole length of the furnace ; to repair this all scale and dirt has to 
 be carefully removed from the corrosion which is then built up to 
 the original thickness of the furnace ; the method employed is exactly 
 the same as that for cracks, new metal being added little by little 
 as the plate is brought to a molten state. 
 
 Corrosions very frequently occur at the landing edges of the 
 furnaces and combustion chamber plates ; when this is so it is usually 
 found that the back plate is also corroded as shown in No. 100. 
 
 No. 100. 
 
Boilers 
 
 i6i 
 
 To repair, the corroded places are first thorouprhly cleaned, the 
 corrosion C is then first made good, the landing of the front plate 
 is then built up to the required amount, the same care being taken 
 in this case not to weld the front to the back plate as in the case of 
 landing edge cracks. 
 
 Besides cracks and corrosions in furnaces and combustion 
 chambers, the same defects sometimes arise in the tube plates : cracks 
 extend from one tube hole to another, and are very difficult to repair ; 
 as this is the least section of the metal (see No. loi), and is subject to 
 great strain, fortunately these cracks do not often occur. To repair, 
 the crack is cut out as previously explained, and welded ; a sheet of 
 iron should be put over the further end of the tubes to prevent a 
 draught being set up. 
 
 No. loi. 
 
 Corrosion in the tube plates occurs when there is a leak between 
 a tube and the plate ; this can be easily repaired by cleaning and 
 adding the necessary new metal. 
 
 Another frequent defect in a boiler is corrosion round the mud 
 hole flanges ; this can be repaired, if not too far gone, by building up 
 as previously explained. If, however, a flange is too far gone to be 
 repaired by this means, a new flange can be welded in as shown in 
 No. I02, and the joint of the cover can be made at the surface. 
 
 No. 102. 
 
t62 "Verbal" Notes and Sketches 
 
 With regard to repairs to hulls of vessels these are far more 
 limited than those of boilers ; this is to a great extent due to the 
 inferior metal used in their construction as compared to that used in 
 boilers, thus it is impossible to weld a piece into the rniddle of a 
 ship's side plate. 
 
 Welding of frames docs not always succeed unless they are set free 
 over a great length. 
 
 No difficulty is met with in repairing stems as they are of com- 
 paratively small thickness. The repair is carried out as follows : — 
 The crack is cut to a V both sides, the bottoms of the two incisions 
 meeting in the centre, the welding is then done from both sides 
 simultaneously. 
 
 Stern posts and rudder posts are much more difficult to repair 
 owing to their thickness. Before repairing, the work must be brought 
 to a red heat by means of a forge or some other method, the blow- 
 pipes are then brought into use and the work proceeds in the usual 
 way, only, when once started, the job must not be left till finished. 
 
 Besides the above-mentioned repairs, cutting away of furnaces, 
 ship's plates, rivets, &c., can be done with a specially-constructed blow- 
 pipe in which an oxy-acetylene flame is used to heat the part to be 
 cut, and an oxygen jet is used to do the cutting ; with this blowpipe 
 a great deal of time can be saved, for example, a stem can be cut in 
 four minutes, and the largest stern post in ten minutes, or a furnace 
 can be cut out in about one and a half hours if it is desired to 
 replace it. 
 
 Autogenous welding is the uniting of metals by means of heat 
 i-lone, without the intervention of any different metal. 
 
 The heat is obtained by the combustion of acetylene with pure 
 oxygen, which gives a temperature of about 6500° Fahr. 
 
 Cutting by Oxygen Jet. — In cutting plates a small surface spot 
 is first heated up by the acetylene flame, and a jet of oxygen is pro- 
 jected on to this hot plate from a separate orifice, the metal being 
 burnt or oxidised away where the jet strikes, with the result that a 
 cut is made similar to that produced by a saw. 
 
 General. 
 
 Acetylene (C2H2) is a gas of nearly the same weight as atmo- 
 spheric air. 
 
 Each cubic foot of gas generates about 1450 B.T.U. 
 
 During combustion of C.^Ho carbonic acid gas is formed (CO.,), also 
 water vapour (H^O). 
 
 The flame formed by the blowpipe consists for the most part of 
 CO gas, but at the point of CO.^. 
 
 The welding flame is surrounded by a film of Hydrogen gas which 
 prevents oxidation from taking place, and thus allows of an efficient 
 weld being formed without the use of a flux. 
 
r^ 
 
 !.n 
 
 i 
 
 J 
 
 t 
 
 r<.3\'KiZ 
 
No. 103— Water Gauge Cock on Boiler. 
 
 This type of cock has the plug taper reversed, thus reducing risk of the plug blowing out. In removi 
 tile plug from the sheil, it must first be knocked down into the boiler. 
 
 A small set pin screwed through the shell of the cock prevents the plug from dropping out of pla 
 when in use. • 
 
 The objection to this type of plug is the tendency for the hole in the plug to become choked up w) 
 grease and dirt, and thus reduce the opening of the port. 
 
iCv 
 
 ;«- 
 
 "I I 
 
 L-^^ 
 
 .-)*»' 
 
er. 
 
 plug blowing out. In removing 
 )lug from dropping out of place 
 plug to become choked up with 
 
 [To ''ace f^aj^e 1 63. 
 
/Tv. 
 
 TWAIQ f I 
 
 •'/ 
 
I II 
 
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 il^Si 
 
 •S5 
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MOXE— MOffce f- 
 
 'din tiocjr 
 
 1.0 arquiTf gnq <. 
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 X' 
 
 
 5| DfVW '__... ^__„',^ .. 
 
IT 
 
 
 '^3.5 
 
 «E 
 
 i 
 
 "■'.V 
 
|3" 
 
 STEEL STAY 
 
 LA DIAM. AT QOT. OF THREAD 
 STEEL STAY 
 
 STEEL STAY 
 
 COMMON TUE 
 
 8 TUBE PLATE SOLID STAY 6 
 
 CNI 
 
 MORISON FURNACE 
 
 m 
 
 t:;^' 
 
 No. 105.— Sketch of Marine Boiler with Principal Dimensions (Longitudinal section). 
 
 Students preparing for the Fii 
 ting carefully the dii 
 
 Notice that the furnace shown is of the Ciourley-Stephei 
 position of the flange at the back allows of the furnace being 
 opai.ng. 
 
 Shell Thickness. — To find the required shell thickne 
 inch, joint 84 per cent., and Factor of Safety 4-6. 
 
 Rule — 
 
 28 ■; 2240 >: T X 2 >: joint- Factor x D ii 
 
 Therefore, T = ^'?L:lP_ i"- < Sa fePresstire ^ 4^ > I74 i 
 
 28 X 2240 X 2 X joint 28 X 2240 > 
 
 : Class Examination should practise drawing the above sketch from 
 nd tlie flanging of the plates, &c. 
 
 able type, as the slightly elevated 
 nted up and withdrawn from the ficiit end 
 
 if the pressure is to be 180 lbs. per square 
 
 < Safe Pressure. 
 ?^°-36m',say\ii 
 
e 
 
 JTAJS 
 
 3VfiT J^qT 
 
 m 
 
 Hs)fn U| 
 
 3TAJ^ 38UT 
 
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 3TAJS 30AM5^U-i 
 
 
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 'i^MQs^t^f-: 
 
h 
 
 
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 ^v Af I 5qT > 
 
 HOfi*^ Qi ^ 
 
No. 106— Sketch of Marine Boiler, with Principal Dimensions (half section). 
 
 Students preparing for the First Class Examination should practise drawing the above sketch from memory, 
 noting carefully the dimensions and the flanging of the plate, &c. 
 
 Safe Pressure.— To find the required Safe Pressure, if the Diameter is 14 feet 6 inches. Factor of Safety 46, 
 and the joint strength 84 per cent. 
 Rule — 
 
 28 X 2240 X T X 2 X joint = Factor x D in. x Safe Pressure. 
 Therefore, Press„re = ^i^^^T^|^t, 28x2240x.3;.^xax .84 ^.3. ..^^ ^^ ,3^ „, 
 
 NOTE.-1I inches = 1.375; '4 feet 6 inches=i74 inches; ^=84. 
 
 in/artf<Jgi 163. 
 
Boilers i6 
 
 o 
 
 The pressure of oxygen supply to the blowpipe varies (with 
 different sizes) from lo lbs. to 25 lbs. 
 
 In cutting plates by means of an oxygen jet the oxygen ignites 
 the plate, which burns away as oxide of iron (similar to rust). 
 
 Bottom Blow-off — In the opinion of the writer the boiler bottom 
 blow-off cock to the ship's side might well be dispensed with alto- 
 gether, as, unless carefully handled, it undoubtedly constitutes a 
 danger, owing to the possibility of lowering the water level below 
 the combustion chamber tops, which may result in : — 
 
 1. Collapse of combustion chamber tops. 
 
 2. Deposit of greasy scum matter on top of combustion chambers. 
 
 Many engineers are now in favour of discarding the bottom blow- 
 off as commonly fitted, and connecting the bottom pipe as a donkey 
 pump suction, which arrangement allows of either pumping out the 
 boiler, or of circulating when getting up steam by drawing out the 
 colder water at the bottom and pumping it back into the boiler through 
 the donkey feed check higher up. 
 
 The surface blow-off (Sketch No. 104), if properly fitted as shown, 
 when opened, only allows the water to be lowered down to the scum 
 pan level, and by its use the oily scum floating on the surface can be 
 blown out, whereas, if the bottom cock is employed, the scum referred 
 to is apt to settle down on the combustion chamber tops, and once 
 deposited will be found extremely difficult to remove except by 
 thorough washing out of the boiler. 
 
 Efficiency of Boiler. — The average heating value of i lb. of coal 
 is 14500 heat units, and with a feed temperature of, say, 140", and 
 steam temperature of 380^ (180 lbs. gauge pressure), the evaporation 
 would be as follows if no loss of heat occurred : — 
 
 Heat Units of Evaporation = 11 15 + -3 x 380' - 140^ = 1089 Heat Units. 
 And, 14500^ 1089 = 13-3 lbs. of water evaporated into steam per pound of coal. 
 
 If, however, the actual evaporation as measured is only gh lbs. of 
 water per pound of coal, 
 
 Then, Boiler Efficiency = 9-5 -M3-3 = -714 or 71-4 per cent. 
 
 Equivalent Evaporation. — As a standard of comparison the evapo- 
 ration obtained by a fuel "from and at" 212" is usually taken, that 
 is, the feed is assumed as being at 212'' temperature, and the steam 
 at 212° temperature. 
 
 Example. — Feed temperature 140', steam pressure 180 lbs., and 
 temperature 380" ; if the actual evaporation per pound of coal as 
 tested is 10 lbs, of water, find the equivalent evaporation. 
 
 Then, Heat Units for evaporation = 1115 + -3 x T°- <' = 1115 + '3x380- 140 
 = 1089 Heat Units per pound water. 
 
 Therefore. '°^9 x 10 ^ „ ^^s. 
 
 966 
 
h.GfX 
 
 iX' 
 
Boilers i6 
 
 o 
 
 The pressure of oxygen supply to the blowpipe varies (with 
 different sizes) from lo lbs. to 25 lbs. 
 
 In cutting plates by means of an oxygen jet the oxygen ignites 
 tiie plate, which burns away as oxide of iron (similar to rust). 
 
 Bottom Blow-off. — In the opinion of the writer the boiler bottom 
 blow-off cock to the ship's side might well be dispensed with alto- 
 gether, as, unless carefully handled, it undoubtedly constitutes a 
 danger, owing to the pc^ssibility of lowering the water level below 
 the combustion chamber tops, which may result in : — 
 
 1. Collapse of combustion chamber tops. 
 
 2. Deposit of greasy scum matter on top of combustion chambers. 
 
 Many engineers are now in favour of discarding the bottom blow- 
 off as commonly fitted, and connecting the bottom pipe as a donkey 
 pump suction, which arrangement allows of either pumping out the 
 boiler, or of circulating when getting up steam by drawing out the 
 colder water at the bottom and pumping it back into the boiler through 
 the donkey feed check higher up. 
 
 The surface blow-off (Sketch No. 104), if properly fitted as shown, 
 when opened, only allows the water to be lowered down to the scum 
 pan level, and by its use the oily scum floating on the surface can be 
 blown out, whereas, if the bottom cock is employed, the scum referred 
 to is apt to settle down on the combustion chamber tops, and once 
 deposited will be found extremely difficult to remove except by 
 thorough washing out of the boiler. 
 
 Efficiency of Boiler. — The average heating value of i lb. of coal 
 is 14500 heat units, and with a feed temperature of, say, 140", and 
 steam temperature of 380" (180 lbs. gauge pressure), the evaporation 
 would be as follows if no loss of heat occurred : — 
 
 Heat Units of Evaporation = 11 15 + -3 x 380' - 140' = 1089 Heat Units. 
 And, 14500 -^ 1089 = 13-3 lbs. of water evaporated into steam per pound of coal. 
 
 If, however, the actual evaporation as measured is only 9I lbs. of 
 water per pound of coal. 
 
 Then, Boiler Efficiency - 9-5 -M3'3= -714 or 71-4 per cent. 
 
 Equivalent Evaporation. — As a standard of comparison the evapo- 
 ration obtained by a fuel "from and at" 212° is usually taken, that 
 is, the feed is assumed as being at 212" temperature, and the steam 
 at 212° temperature. 
 
 Example. — Feed temperature 140", steam pressure 180 lbs., and 
 temperature 380" ; if the actual evaporation per pound of coal as 
 tested is 10 lbs. of water, find the equivalent evaporation. 
 
 Then, Heat Units for evaporation = iii5 + '3xT°- ^'' = iiiS + «3x38o- 140 
 = 1089 Heat Units per pound water. 
 
 Therefore, i2?^LiO = 11.27 lbs. 
 
 966 
 
164 "Verbal" Notes and Sketches 
 
 One pound of the coal referred to can therefore evaporate 11-27 
 lbs. of water into steam " from and at" a temperature of 212". 
 
 Weight of Gases passing up Funnel. — The weight of the waste 
 gases which pass up the funnel can be estimated as follows : — 
 
 Example. — If the consumption is 25 tons of coal per twenty-four 
 hours, determine the total weight of the products of combustion 
 passing up the funnel during that period. 
 
 NOTE. — Each pound of coal requires about 24 lbs. of air for complete combustion. 
 
 Therefore, Weight of air required = 25 x 24 = 600 tons. 
 
 But (neglecting ash and clinker) the 25 tons of coal also pass off 
 in the form of gas. 
 
 So that, total weight of gases = 600 + 25 = 625 tons per twenty-four hours. 
 
 The actual weight of the gases would be perhaps about 10 per 
 cent, less than the above, if the residue of ash and clinker were 
 deducted. 
 
 Shortness of Water. — If a boiler runs short of water through faulty 
 check valve, or other causes, the first thing to do is to pump in more 
 feed water, either hot or cold, preferably hot of course, but even cold 
 water will in most cases result in no serious injury or danger if the 
 water is not actually below the crowns. The seams or tubes may 
 afterwards leak slightly, but nothing more is likely to happen. 
 
 If, then, one boiler out of, say, a set of four boilers shows a low water 
 level, the engineer on watch should at once open up the check valve 
 of that boiler, and reduce the lift of the check valves on the other three 
 boilers : in addition to this it may become necessary to put on an 
 extra feed pump (if one is available) to the boiler which shows no 
 water in the glass. The point to be remembered is to get water into 
 the boiler as soon as possible, and, as before stated, even cold feed 
 water may be pumped in without risk of accident if the boiler is 
 merely short of water. 
 
 Velocity of Gases. 
 
 The mean velocity of the gases passing through the uptake and 
 funnel is about 1 3 feet per second ; the mean velocity of the gases 
 passing over the furnace bridge is about 75 feet per second ; the mean 
 velocity of the gases passing through the tubes is about 60 feet per 
 second. 
 
 Evaporation per Pound of Coal. 
 
 One pound of average coal gives out about 9000 units of 
 htat (B.T.U.). 
 
4-t 
 
 wk,/V^^MWrMVJ7W^/^V/W//VA 
 
 Stoyy Tuitps Screwed 
 
 -k. 
 
 '■^///^////v/////My//////^.'///////^^ pg7;77^^^y.7^^--y/?-^^z.y/r7^^ 
 
 
 
 ■Totoji S60 Txvbes. 
 
 a-ywui_»iw--i-'«.* 
 
 Rivet diameter - - - - 
 
 Maximum Pitch of Rivets (five rivets 
 per pitch) - - - * 
 
 Distance between inner rows 
 
 outer ,, ^ - 
 Rivet section strength - 
 Plate „ „ - 
 
 \\ inches (holes ifV mcnes). 
 
 '16 »' 
 
 ■16 >> 
 
 3t^ 
 
 93-2 per cent. 
 83-7 » 
 

 2? I/kan L -nijOv 
 
 Double Ended Boiler of White Star Liner "Britannic' 
 (Reproduced by permission from " Engineering." Feb. iy, 1914. 
 
 White Star Liner "Britann 
 
 (By Messrs Harland & Wolff Ltd.) 
 
 GENERAL DATA^ 
 Length over aU 
 Breadth • 
 
 Deptb, moulded 
 
 Height from keel to bridge 
 
 age . 
 
 Load draught 
 
 Displacement at load draught 
 
 Combined i H P. of wmg reciprocating engines (ahead and 
 
 Shaft horse power of centre turbine (ahead onlyj 
 
 Sea speed • . , . 
 
 64 .. 3 in- 
 104 ,, 6 ,, 
 50000 tons. 
 34 ft 7 'n 
 53000 tons. 
 32000 ., 
 
 BOILER DATA- 
 
 
 Number of double ended boilers .... 
 
 
 .. single ,, ., - . . . 
 
 5 
 
 Diameter of all boiler^ .... 
 
 15 ft, 9 a 
 
 Length of double ended boilers 
 
 
 ,. single ., ,. .... 
 
 II -. 9 .. 
 
 Number of furnaces on each double ended boiler 
 
 6. 1 
 
 single ., 
 
 3 i 
 
 Total heating surface per double ended boiler 
 
 5702 sq. ft. ; 
 
 .. grate .. . . 
 
 ISO'S .. ., ; 
 
 .. heatmg ,, .. single ended ,, 
 
 2822 ., ,, 1 
 
 .. grate 
 
 654 .. .. 1 
 
 Ratio of heating surface to grate surface ■ 
 
 As 43 is to 1 j 
 
 Inside diameter of furnace corrugations 
 
 3 ft t> ill. 
 
 Type of corrugation 
 
 Morison. 
 
 Total number of furnaces 
 
 "59 
 
 Working boiler pressure . . . . . 
 
 215 lbs. (gauge). 
 
 Test pressure ....... 
 
 430 .. 
 
 It will be noted that each combustion chamber is suspended from the shell by 
 ■ a large central stay, secured top and bottom by eyes and pins to angle irons above 
 and to the girder below. The large scale drawing on right shows clearly the 
 details and dimensions of the suspension stay. It should also be carefully noted that 
 when suspension stays are fitted the combustion chambers are also anchored to the 
 shell at the bottom, either by screwed stays icenire furnace) or by plate stays (wini; 
 furnaces). 
 
Boilers 
 
 165 
 
 To find the units of heat required to evaporate i lb. of water into 
 steam, the rule is as follows : — 
 
 iii5+-3xT- <- Units of heat. 
 T — Steam temperature, t - Feed temperature. 
 
 Example. — The steam pressure is 160 lbs. or 370^^^ temperature, 
 and the feed water temperature is 140° ; find the units of heat required 
 to evaporate i lb. of water into steam, and the number of pounds of 
 water evaporated by i lb. of coal. 
 
 Then, 1 115 + -3 x 370°- 140° =^1086 units of heat required per pound of coal. 
 
 Therefore, ^°^ = 8-28 lbs. of water evaporated per pound of coal. 
 1080 
 
 NOTE.— To evaporate i lb. of water at 212" temperature into a pound of steam 
 at atmospheric pressure requires 966 units of latent heat. 
 
 Boiler Dimensions. 
 
 The following data refer to a modern type double-ended boiler 
 carrying a pressure of 170 lbs. per square inch, and the various plate 
 thicknesses and details of riveting should be carefully noted. 
 
 Boiler Data. 
 Pressure .... 
 
 Diameter .... 
 
 Length (double ended) - 
 Number of furnaces 
 
 „ combustion chambers 
 
 Grate length - . . - 
 
 ,, width . . - - 
 
 Total grate area - . - - 
 
 Heating surface of tubes 
 
 „ ,, furnaces 
 
 ,, ,, combustion chambers 
 
 Total heating surface 
 Heating surface to grate 
 Area over bridge - - - 
 
 170 lbs. per square inch. 
 
 13 feet 10 inches. 
 
 20 „ i| „ 
 
 6. 
 
 6. 
 
 6 feet 10 inches. 
 
 3 j> 42 >» 
 138 square feet. 
 2840 „ 
 
 242 
 
 444 „ 
 
 3664 „ 
 
 26-5 is to I. 
 3-11 square feet. 
 
 Shell consists of three courses of plates, each course having three 
 plates ; the centre course is outside of the end courses. 
 Shell thickness - - - - ^\ inches. 
 
 Longitudinal Shell Seams. 
 
 Double-butt strap thickness 
 Rivet diameter - - - - 
 
 Maximum Pitch of Rivets (five rivets 
 per pitch) . - . . 
 
 Distance between inner rows 
 
 „ „ outer „ 
 
 Rivet section strength - 
 Plate „ „ - 
 
 I inch. 
 
 i\ inches (holes i/?- inches). 
 
 5 
 3t^ 
 
 
 
 93-2 
 
 per 
 
 cent. 
 
 83-7 
 
 
 II 
 
v£ ^ _ _, ^^^^...^ iiiiwugii uic Luucb IS aoout Oo teet per 
 
 second. 
 
 Evaporation per Pound of Coal. 
 
 One pound of average coal gives out about 9000 units of 
 h^at (B.T.U.). 
 
Boilers 
 
 i6' 
 
 To find the units of heat required to evaporate i lb. of water into 
 steam, the rule is as follows : — 
 
 iii5 + -3xT-^- Units of heat. 
 T = Steam temperature. ^-Feed temperature. 
 
 Example. — The steam pressure is i6o lbs. or 370 temperature, 
 and the feed water temperature is 140° ; find the units of heat required 
 to evaporate i lb. of water into steam, and the number of pounds of 
 water evaporated by i lb. of coal. 
 
 Then, 11 15+ -3x370°- 140°= 1086 units of heat required per pound of coal. 
 
 Therefore, ^„, = 8-28 lbs. of water evaporated per pound of coal. 
 1086 
 
 NOTE. — To evaporate i lb. of water at 212" temperature into a pound of steam 
 at atmospheric pressure requires 966 units of latent neat. 
 
 Boiler Dimensions. 
 
 The following data refer to a modern type double-ended boiler 
 carrying a pressure of 170 lbs. per square inch, and the various plate 
 thicknesses and details of riveting should be carefully noted. 
 
 Boiler Data. 
 
 Pressure .... 
 
 Diameter .... 
 
 Length (double ended) - 
 Number of furnaces 
 
 „ combustion chambers 
 
 Grate length .... 
 ,, width .... 
 Total grate area - . - - 
 
 Heating surface of tubes 
 
 „ ,, furnaces 
 
 ,, „ combustion chambers 
 
 Total heating surface 
 Heating surface to grate 
 Area over bridge 
 
 170 lbs. per square inch. 
 
 13 feet 10 inches. 
 
 20 ,, i| ,, 
 
 6. 
 
 6. 
 
 6 feet 10 inches. 
 
 3 >> 42 »' 
 138 square feet. 
 2840 „ 
 
 242 „ 
 
 444 „ 
 
 3664, 
 
 26-5 is to I. 
 3-11 square feet. 
 
 Shell consists of three courses of plates, each course having three 
 plates ; the centre course is outside of the end courses. 
 Shell thickness - - - * ^i inches- 
 
 Longitudinal Shell Seams. 
 
 Double-butt strap thickness 
 
 Rivet diameter - - - - 
 
 Maximum Pitch of Rivets (five rivets 
 
 per pitch) . - . - 
 
 Distance between inner rows 
 
 „ „ outer „ 
 
 Rivet section strength - 
 Plate „ „ - 
 
 1 inch. 
 
 I J inches (holes ij^^ inches). 
 
 3tt 
 
 >> 
 
 93-2 
 
 per cent. 
 
 83-7 
 
 >i 
 
i66 
 
 " Verbal " Notes and Sketches 
 
 Centre Circumferential Shell Seams. 
 
 Rivet diameter - 
 
 ,, pitch (three rivets per pitch) 
 
 „ section strength - 
 Plate „ „ - 
 
 End Circumferential Seams. 
 
 Rivet diameter - 
 
 „ pitch (two rivets per pitch) 
 
 ,, section strength - 
 Plate „ ,, - 
 
 lyV inches (holes if inches). 
 
 68-6 per cent. 
 66-6 „ 
 
 i;^ inches (holes ij^ inches). 
 
 70-15 per cent. 
 62-5 
 
 End Plates. 
 
 Top end plate thickness 
 Centre ,, „ (front tube plate) 
 
 Bottom ,, „ (furnace plate) - 
 
 Furnace length - - - - 
 
 „ diameter 
 
 „ thickness 
 Combustion chamber width 
 Back tube plate thickness 
 Thickness of combustion chamber plates 
 Diameter of combustion chamber stays - 
 Pitch „ „ „ 
 
 Length of combustion chamber girders - 
 Depth „ „ „ 
 
 Thickness ,, „ „ 
 
 (two plates each) 
 
 Each girder fitted with three i|-inch diameter bolts. 
 
 1 1 inches. 
 I inch. 
 i^ inches. 
 7 feet 8 inches. 
 
 3 5> 7 »j 
 
 1 inch. 
 
 2 feet 6 inches. 
 
 f inch. 
 ji 
 iF _'> 
 
 i| inches (bottom of thread), 
 from 6^ to 8i inches. 
 2 feet 6| inches. 
 7f inches. 
 
 f inch. 
 
 Tubes. 
 
 Diameter of tubes 
 
 Length „ 
 
 Pitch of tubes - - - 
 
 >> >> " 
 
 Number of plain tubes per boiler 
 
 M stay „ 
 
 Diameter of main stays (steel) - 
 Manhole 
 Mudholes (five in number) 
 
 3 inches outside. 
 7 feet 4I inches. 
 
 4^ inches horizontally. 
 
 4 „ vertically. 
 324 (No. 8 B.W.G.). 
 180 ( „ 6 „ ). 
 2 1 inches. 
 
 16 X 12 inches. 
 15x11 » 
 
 NOTE.— The grate surface for each furnace is equal to the length of bars 
 multiplied by diameter of furnace. 
 
 6' 10" 3' 4J" 
 
 12 12 
 
 Therefore, 405 ^23 sq. ft., and 23 x six furnaces =138 sq. ft. (total). 
 144 
 
 And, Total Heating Surface -f Grate Surface = Ratio. * 
 
 Then, 3664^138 = 265 to i. 
 
;oi .o<^; 
 
Vertical Donkey Boiler 
 
 /ifk.':k 
 
 No. 107. — Vertical Type Donkey Boiler. 
 
 Pressure, 80 lbs. (gauge). 
 
 ' Verbal " Notes and Sketches. 
 
 [7<5 fair page 167. 
 
Boilers 
 
 167 
 
 Referring to the joint strengths of each seam, it must be remembered that 
 the smaller per cent, of rivet section and plate section at seam is the joint 
 strength, therefore, 
 
 Joint strength for longitudinal shell scams =837 per cent. 
 
 ,, ,, centre circumferential shell seams —66 '6 ,, 
 
 ). )» end ,, ,, ,, =62'5 ,, 
 
 The screwed portions of the stay tubes and combustion chamber 3, ays 
 have twelve threads per inch. 
 
 Repair for Broken Cross-Water Tube in Vertical 
 Donkey Boiler. 
 
 i 
 
 PLATE 
 
 No. io6a.— Donkey Boiler Repairs. 
 
 Cut out the broken tube, and fit blind flanges over the openings 
 of the fire box (inside) which either rivet or bolt as shown in sketch. 
 
 Remove small dogs and inspection doors on shell and pin on 
 small plates, then screw in stays as shown to support fire box. Stays 
 of about if" diameter would be found sufficient. 
 
 Repair for Weak (Corroded) Fire Box. 
 
 Tap in a ring of stays through shell and fire box, and either rivet 
 over or fit on nuts. The stays will give additional strength to the 
 fire box. 
 
1 68 
 
 Verbal " Notes and Sketches 
 
 Sketch 107 shows clearly the construction of this kind of boiler. The 
 cross water tubes are for improving the circulation and increasing the heating 
 surface, and it is to be noted that a handhole is fitted opposite each tube for 
 cleaning purposes. 
 
 There are usually from four to six stays of about 2 inches diameter for 
 supporting the fire-box. 
 
 This boiler has a wet uptake, and corrosion takes place at the water level ; 
 corrosion also goes on at the bottom, between the shell and the fire-box, 
 and is caused by what is called "grooving," that is, the upper part of fire-box 
 expands by the heat, but the lower part at the bottom being riveted to the 
 shell is kept rigid; therefore the skin of the metal cracks slightly at the 
 bend, and allows of corrosion taking place. The corrosion is also increased 
 by the want of circulation at this part of the boiler. 
 
 As the fire-bars are low down, and the ash-pit immediately underneath, 
 the boiler is a dry bottomed one. For ordinary proportions, the shell ir 
 about f inch thick and the fire-box | inch thick. 
 
 The average dimensions for this type of boiler are as follows : — 
 
 10 inches diameter. 
 
 15 M 
 
 6 inches to 3 inches. 
 2 inches diameter 
 
 Pressure 
 Diameter 
 Height 
 Shell plates - 
 Fire-box plates 
 
 80 lbs. gauge. 
 5 feet. 
 10 „ 
 
 g to i inch thick, 
 to " 
 
 Cross tubes 
 
 Uptake . . - - 
 Water space round tire-box 
 Vertical stays • 
 
 (six in number). 
 
 FIREHOLE. 
 
 OCCE RINO. 
 
 SPECIALLY THICK 
 
 TO (Mve MaROiN 
 
 FOR CORROSION ETC. 
 
 No. 108.— Cochran Patent Vertical Type Multitubular Boiler. 
 
 For Marine Use. 
 
Boilers 
 
 169 
 
 The chief advantafres of this type of donkey boiler as compared 
 with the ordinary type are : — 
 
 1. Greater steaming capacity, with same space occupied. 
 
 2. Increase of heating surface as compared with grate surface. 
 
 3. Improved construction of parts, including new patent seamless 
 furnace, having neither riveted nor welded seam exposed to flame, 
 which is a matter of considerable practical importance. 
 
 Haystack Boiler. 
 
 This type of water tube boiler is fitted with four furnaces, and two 
 circulation pockets, as shown. The water circulates down the pockets, 
 and enters the pan by means of large pipes, and after evaporating 
 rises up through the tubes into the steam space. 
 
 The Haystack boiler is of large capacity, and Is a fairly quick 
 steam raiser, but in a number of cases a serious disadvantage exists 
 in the difficulty experienced in locating the true water level, as the 
 glass often indicates incorrectly. In a number of boilers, which have 
 come under the writer's observation, the water in the gauge glass 
 
 No. 109.— Haystack Boiler. 
 
170 "Verbal" Notes and Sketches 
 
 behaved in a most erratic manner, when under weigh and when 
 stopped, indicating falsely under both conditions, as sometimes the 
 glass would show full when the engines were running, and empty 
 when stopped. This is evidently due to the position of the tubes and 
 the shell, and the peculiar effect of the rising circulation currents. 
 This boiler has a dry bottom, and a wet uptake. 
 
 Water Tube Boilers. 
 
 This class of boiler has not as yet been adopted to any considerable 
 extent in the Merchant Service, comparatively few steamers having 
 been fitted with them ; from this it would appear that shipowners are 
 awaiting the thorough testing, in the Navy, of this type of steam 
 generator before seriously considering the advisability of having it 
 included in the specifications of new steamers. It should, however, 
 be borne in mind that a certain class of boiler may suit Naval practice, 
 but not be so well adapted for the Merchant Service, owing to the 
 different requirements existing in each particular case. 
 
 The cylindrical, or, as it is usually termed, " Scotch " boiler which 
 has for so long a period done its duty satisfactorily as an effective 
 steam generator, is still the favourite boiler in use for passenger and 
 cargo steamers ; but should the demand for a still further increase 
 of pressure become general, as seems probable, it is almost certain that 
 engineers will require to turn towards water tube boilers of one type 
 or another to obtain the requisite pressure, compatible with safety and 
 convenience of manufacture, as, for a pressure of, say, 300 lbs. per 
 square inch, the diameter of a cylindrical boiler would require to be 
 very small, or the shell thickness very great, to allow of this being 
 safely carried. 
 
 Yarrow Boiler. 
 
 Perhaps the two best known types of water tube boilers in general 
 marine practice are the Yarrow and the Babcock & Wilcox. The 
 Yarrow boiler is of simple construction, consisting of two bottom 
 water and mud drums, and one top steam drum with straight tubes 
 connecting the top drum to the bottom drums. The top drum is 
 circular and the bottom drums of oval shape. The tubes are 
 expanded into the drums, and also bell-mouthed (an extra pre- 
 caution) to prevent drawing out of tubes. The tubes are easily 
 cleaned and do not silt up so easily as the curved tubes in other 
 types of boilers. Two large tubes are led from the top drum to 
 the bottom drums at each side ; these tubes are termed downcast 
 tubes, and serve as a return connection from the top to the bottom 
 drums when circulation is going on. These tubes, it may be mentioned, 
 are outside of the boiler casing and are not in contact with heat. 
 A large casing, built up of asbestos lined plates, is fitted outside the 
 tubes, and doors are fitted to allow of easv cleaning out of soot which 
 
Boilers 171 
 
 gathers at the bottom of the casing (Sketch of Boiler, No. no). 
 A large grate and combustion chamber is one of the features of the 
 Yarrow boiler. Zinc plates are fitted, as in Scotch boilers, in the 
 upper or steam drum, and also in each of the bottom drums. Yarrow 
 boilers are usually installed in close stokeholds, fans being driven to 
 give air pressure required. It is found that water tube boilers give 
 the best results with an even fire of 6 to 7 inches thick, and 
 level firing. In the upkeep of Yarrow boilers it is necessary to clean 
 out soot chambers at least every second day, and the space between 
 tubes also requires cleaning as often as is possible, but the soot 
 chambers can be cleaned while boiler is steaming. Furnace doors 
 and ashpit doors are so arranged that, in event of boiler tube bursting, 
 all doors will close, thus confining escaping steam as much as 
 possible. The tubes var)' in diameter from i^ to i^ inches. 
 
 Babcock Boiler. 
 
 The Babcock & Wilcox boiler is of different construction, the 
 tubes being expanded into boxes usually termed headers. These 
 headers are fitted with small doors in line with the tubes to allow of 
 cleaning same. The headers or sections are again connected to the 
 top or steam drum. This boiler has also a large grate surface, and 
 is best fired on the same principle as the Yarrow, that is, a level fire 
 of 6 or 7 inches thick. This boiler has the advantage of working on 
 natural draught, and is a good steaming boiler under those conditions. 
 As in the Yarrow boiler the circulation takes place in a similar 
 manner, downcast tubes being fitted leading back to the mud drum 
 or bottom header. Blow-off cocks are fitted on this header for 
 cleaning out header. The furnace in water tube boilers is lined 
 with fire-brick throughout, and the ashpits are kept supplied with 
 water so as to avoid damage to the fire-bars. Superheaters are being 
 fitted in the Babcock & Wilcox boiler, superheating the steam to 
 100" to 150°. The superheater is fitted athwart-ships, and consists 
 of a series of U-shaped tubes connected to headers in a similar 
 manner to the main boiler tubes. After steam is generated in the 
 main boiler it is passed through the superheater before passing to 
 the machinery. Steam connections for cleaning tubes of soot are 
 fitted, access being obtained by doors on each end of boiler. Zinc 
 plates in perforated holders are fitted in the steam and water drum, 
 and also in the bottom or mud drum. These boilers are possessed of 
 several advantages, steam being quickly raised, but to maintain this 
 efficiency it is necessary to keep boiler in a clean condition, which 
 necessitates the cleaning of the outside of the tubes as often as 
 required. This operation can be carried out while boiler is steaming, 
 as in the Yarrow boiler. 
 
 Water tube boilers require to be kept as clean as possible owing 
 to the possibility of the tubes silting up, and require constant 
 attention as regards treatment with lime, &c. 
 
172 "Verbal" Notes and Sketches 
 
 The lower two rows of tubes are about 4 inches diameter, and the 
 others 2 J inches diameter ; the larger size of the lower rows reduces 
 the tendency to upward bending, due to the intense heat, a fault 
 common to the lower tube rows in all water tube boilers, the severe 
 expansion produced by the high temperature acting to bend the 
 tubes rnvaf from the heat. 
 
 The larger sized lower tubes also allow better for the scale deposit, 
 which, if the feed is of any appreciable density, quickly forms on 
 these tubes. 
 
 Both of the above described boilers are specially suited for the 
 burning of oil fuel, which is now in general practice in the Navy 
 (see page 609). 
 
 The special advantages of water tube boilers as compared with the 
 ordinar)' cylindrical type are as follows : — 
 
 Advantages. 
 
 1. Suitability for high pressures (often 300 lbs. per square inch). 
 
 2. Less weight for the same power. 
 
 3. Greater safety in event of accident owing to the smaller amount 
 of water carried. 
 
 4. Quicker raising of steam (about one hour is the time usually 
 required). 
 
 As a set-off against the above stated advantages it should be 
 mentioned that the water tube boiler requires more skilful firing than 
 ordinary, also careful attention to the feeding is necessary, the amount 
 of water carried being so smitll that should anything temporarily check 
 the feed supply the water might all evaporate in a very short time and 
 the boiler become empty, with the consequent danger of explosion. 
 In some of the types of water tube boilers in use, the lower sets of 
 tubes are liable to become overheated and damaged by oil or scale 
 deposits, and for this reason the feed water has to be kept as pure 
 as possible, and the boilers run at a very low density. 
 
 Disadvantages. 
 
 1. More skilful firing required. 
 
 2. Regular feeding, 
 
 3. Pure feed water necessary. 
 
 4. Large number of joints to be kept tight (in certain types). 
 
 5. Small amount of water carried, which would quickly evaporate 
 if feed supply is temporarily checked. 
 
 6. Difficulty in cleaning the tubes of scale deposit. 
 
 General Construction. 
 
 The construction of a water tube boiler consists, in general, of a 
 steam drum at the top, connected by means of straight or curved tubes 
 
Boilers 173 
 
 to the water and mud drums at the bottom ; in some cases tlic upper 
 ends of the tubes open into the steam space of tlie drum, and in 
 others into the water space. 
 
 The feed check valve is placed on the top or steam drum, and as 
 the water enters the drum it falls through the down-take pipes to the 
 sediment collector at the bottom, where the dirt is deposited and after- 
 wards blown off. The cold water becoming heated and evaporating 
 rises up through the sets of tubes or " elements " as they are termed, 
 and passes into the drum at the top in the form of steam. The 
 mountings of water tube boilers are similar to those of the 
 cylindrical type, and it should be stated that all the various parts 
 forming the boiler are covered in by an iron casing. In some types, 
 such as the "Bellvillc," feed water heaters or "economisers" are fitted 
 in the uptake, and usually consist of a series of tubes through which 
 the feed water passes before entering the steam drum, and is conse- 
 quently raised in temperature by the otherwise waste gases of 
 combustion. This heating of the feed water increases the steaming 
 power of the boiler and reduces the consumption. 
 
 ' Bellville " Boiler. 
 
 In the " Bellville" type of water tube boiler the tubes are straight, 
 but lie at a slight angle, the ends being connected, and so form an 
 " element." Each " element " consists of a set of tubes forming a zig- 
 zag from the water drum below to the steam drum above. The front 
 ends of the tubes are fixed into " headers," and the back ends, as 
 before stated, are connected to form the spiral arrangement. Doors 
 are fitted at the ends of the tubes for purposes of examination and 
 cleaning. 
 
 The tubes, which are made of good iron or mild steel, vary in 
 thickness according to the position they occupy, the lower sets being 
 made thicker than the upper ones, to withstand the intense heat to 
 which they are subjected, and which has the effect, in some cases, 
 of causing them to become bent; this is most likely to happen when 
 deposits of oil or scale form in the tubes. 
 
 The mountings, as before stated, are similar to those of the 
 ordinary marine type of boiler, with the exception perhaps of the 
 reducing valve which is fitted to the " Bellville " type, as the boiler 
 pressure carried is usually in excess of that required in the engines — 
 often 250 lbs. pressure in the boiler, which is reduced to 200 or 180 
 for the H.P. valve chest. The "Bellville" boiler is supplied with 
 a special feed regulator, consisting of a chamber containing a float 
 in connection with the water level in the boiler ; the float connects 
 with a system of levers, which in turn are in connection with the feed 
 regulation valve, and as the float rises and falls with the amount of 
 water contained in the upper drum, the levers open or shut the feed 
 valve, and so regulate the water supply to the requirements of the 
 boiler. 
 
 13 
 
1 74 
 
 " Verbal " Notes and Sketches 
 
 tcrAouitCR 
 
 OUTLET 
 
 FEED INLE' TO BOilt' f- 
 
 No. III.— Bellville Boiler and Economiser. 
 
 As mentioned previously, careful feed regulation is one of the 
 most important points to be attended to for the successful working 
 of this class of boiler. 
 
 "Babcock & Wilcox" Boiler. 
 
 A general idea of the construction of the " Babcock & Wilcox " 
 water tube marine boiler will be obtained by referring to the illustra- 
 tions, which clearly show the various parts. 
 
 The boiler is constructed entirely of wrought steel, and consists 
 
 / 
 
Boilers 
 
 175 
 
 of a series of straight water tubes placed in an inclined position, under 
 which the furnace is situated ; the tubes are expanded at each end 
 into boxes of sinuous shape called "headers." Opposite each tube 
 there is a separate handhole in the "headers" for inspection and 
 cleaning of the tube, and it is peculiar to note that no stay tubes are 
 fitted. The upward and downward headers are in communication 
 at the top end with the steam and water drum, the downward headers 
 being connected with a mud drum at the bottom end, which is fitted 
 with blow-off cocks for clearing out the sediment which collects there. 
 
 Lo[^lGlTUDl[^l/^L SECTIOH 
 
 No. 112. 
 
176 
 
 "Verbal" Notes and Sketches 
 
 At the sides the boiler has sets of inclined tubes arranged slightly 
 different from the centre series, but forming with them the effective 
 heating surfaces of the boiler. The furnace sides are lined with fire- 
 bricks, and the boiler itself is covered in by a light wrought-iron casing 
 
 No. 113. 
 
 which can be removed when it is necessary to obtain access to the 
 tubes, &c., for repair or cleaning. In this type of boiler the circulation 
 is particularly well provided for, the water rising up through the 
 inclined tubes, past the uptake headers, and into the steam and water 
 drum, and returning by means of the downward headers. The mud 
 
Boilers 
 
 177 
 
 drum at the bottom traps the impurities, such as sediment, &c., and these 
 are blown out of the collector by the cocks fitted for that purpose. 
 
 The joints are all metal to metal, and in the case of the tubes the 
 ends are simply expanded into the plates, no screwed joints being used. 
 
 Expansion of the boiler under heat is allowed for by the manner 
 in which the mud drum is held down to the foundations. 
 
 Schmidt Type Superheater. 
 
 For marine practice this type of smokebox superheater has 
 proved fairly satisfactory, and has recently been fitted in the boilers 
 of quite a large number of new vessels, including many supplied with 
 gearcd-down turbines, in which a moderate degree of superheat (say 
 from 100" to 150^) is found sufficient. 
 
 The following data of superheat working is taken from a large 
 quadruple expansion engine set, and the results obtained in this case 
 were very satisfactory indeed ; the economy of superheated steam 
 over saturated steam showing clearly on the coal consumption. 
 
 Superheat Data. 
 
 Type of engines 
 
 I.H.P. 
 
 Boilers 
 
 Diameter of smoke tubes - 
 
 
 Quadruple expansion 
 4200 
 
 4 single-ended. 
 - 3" 
 
 Boiler pressure 
 
 Diameter of superheater tubes 
 
 Draught - 
 
 
 220 lbs. gauge. 
 
 - 1" 
 
 Howden forced. 
 
 Air pressure at fan 
 
 „ under bars 
 „ above „ 
 
 Revolutions of fan 
 
 
 - r 
 
 - 1" 
 
 260 p.m. 
 
 Data of Pressures and Temperatures with Superheat. 
 
 
 Gauge Pressure 
 
 Temperature 
 
 Temperature 
 
 Degree 
 
 Position. 
 
 in Lbs. per 
 
 for 
 
 as 
 
 ot 
 
 
 Sq. In. 
 
 Pressure. 
 
 Tested. 
 
 Superheat. 
 
 Boiler steam - 
 
 220 
 
 396° 
 
 590° 
 
 194° 
 
 H.P. steam - 
 
 210 
 
 392° 
 
 580° 
 
 188° 
 
 I St LP. steam 
 
 no 
 
 344 
 
 440 
 
 96° 
 
 2nd LP. steam 
 
 47 
 
 295 
 
 295 
 
 
 
 L.P. steam 
 
 9-5 
 
 236° 
 
 230 
 
 -6° 
 
 Smoke box temperature - - 385° 
 
 Uptake temperature - - - 370° 
 
 Funnel „ ... 355° 
 
 It should be noted that the superheating of the steam by the waste 
 gases extracts the heat of the latter, and lowers the gas temperature, 
 as shown by the recorded results ; this again has the effect of reducing 
 the amount of heat available for the air heating tubes of the forced 
 draught system. 
 
No. 113a.— Schmidt Marine Type Superheater. 
 
 The U-tubes extend to within less than a foot of the back end, then 
 round and return again, again bend round and enter another tube, &c. 
 
 One complete element is shown in black section, the other element is left 
 As the tubes incline to block up with soot, "diamond " blowers or other 
 clearing appliances are employed at regular intervals to keep them clear. 
 
 177a 
 
 open, 
 tube 
 
Boilers 
 
 177^ 
 
 No. 113b.— Schmidt Superheater Valve Chest. 
 (Fitted on Top of Boilers.) 
 
 (1) Main stop valve giving steam from boilers either to superheater header box, 
 
 or to engines direct through bye-pass valve (3). 
 
 (2) Superheater steam stop valve to engines. 
 
 (3) Bye-pass valve, for direct boiler steam to engines, through (i), (3), (2), 
 
 and (5). 
 
 (4) Mixing valve for giving a mixture of boiler steam and superheated steam as 
 
 may be found necessary. 
 
 (5) Main steam pipe to engines (either boiler steam or superheated steam). 
 
 (6) Auxiliary boiler steam stop valve. 
 
 (7) ,, superheated ,, ,, ,. 
 
 (8) Boiler steam header (before superheat). 
 
 (9) Superheat ,, ,, (after ,, ). 
 
 (10) Safety valve (single) which may be required if valve (2) is shut and steam is 
 being passed through valve (i) and bye-pass (3), that is, the superheater 
 shut off from boilers. 
 Fitting for connecting up pyrometer (high temperature indicator). 
 
 (") 
 
 NOTE. — With superheater off when working bye-pass, it is advisable to have 
 main stop valve (i) eased off seat to allow a little moisture to be present in the 
 U -tubes of the superheater, otherwise damage to the tubes, &c., by dry steam at 
 high temperature is likely to take place. 
 
SECTION III. 
 
 NOTES AND SKETCHES OF VARIOUS DETAILS. 
 
 No. I.— Crank-Pin Centrifugal Lubrication System 
 (Naval Practice). 
 
 Oil is fed into the container L, and by the action of centri- 
 fugal force is delivered to the crank-pin bearing surfaces H, H 
 through the pipes P, P shown. Radial holes are cut through 
 from the inside of the crank-pin. 
 
 178 
 
No. I A. — Triple Expansion Engines. 
 
 View from H.P. end, looking Aft. 
 
 Observe that the expansion slot of the reversing crank arm is in a slightly 
 inclined position for "ahead," but when run over to "astern" position (as shown 
 by the dotted arc) the slot will be vertical, thus ensuring that full-gear conditions are 
 obtained when going astern, no matter how much the gear was shut in when running 
 ahead. 
 
 {To /ace paj^f. 178. 
 
Notes and Sketches of Various Details 
 
 179 
 
 No. 2.— Reversing Gear Complete (Cruiser Type). 
 
 This gear is known as the " all round " type, as if the gear 
 is " missed," the wheel continues moving round without damage 
 or shock to the link motion. 
 
 For an engine of 1200 I.H.P. the reversing engine cylinders 
 (two) will be about 4^ inches diameter by 4-inches stroke, and 
 from 20 to 25 revolutions of the reversing engine will be required 
 to reverse the gear. The engine is usually made reversible by 
 means of a hand operated piston valve, similar in design to the 
 control valves of steering gear engines, which admits steam 
 either to the centre or to the ends of the cylinder valves as 
 required. 
 
 The reversing engine shown on left drives a worm shaft 
 geared into a large worm-wheel, to which is attached the link 
 from the bell crank. Hand-wheel gear is also shown, and a 
 brake strap connection to the worm-wheel, to increase the 
 control. 
 
i8o 
 
 " Verbal " Notes and Sketches 
 
 No. 3. — Twin Cylinder Turning Engine with 
 Double Worm Gear. 
 
 The lower end of the main worm can be drawn out of gear 
 by means of the wheel shown on right. The turning engine 
 runs at about 300 revolutions per minute, and travels about 
 2000 revolutions for one revolution of the main engine, thus 
 requiring 6| minutes to turn the main engines once round, as 
 2000-=- 300 = 6-6 minutes. For engines of, say, 1500 I.H.P. 
 the turning engine cylinders will be about 3J inches diameter 
 and 4 inches stroke. 
 
 i 
 
8i 
 
 n 
 
 )S. 
 
I i I I' 
 
 a >. -is 
 
 S I •; si 
 
 2 is III Vl 
 
 2 ,3 " s a tij " 
 
 a B § " S- He 
 
 Sj E - i 2 " 
 
Notes and Sketches of Various Details 
 
 i8i 
 
 No. 5.— Section of Stern Tube showing Lignum Vitse Strips. 
 
 K, Check plate to keep strips in position aft. L, Lignum vitse strip. 
 
 The shaft (hollow) is shown in section. The clearance 
 spaces between the strips is to allow of the admission of water 
 for lubrication inside the tube. Lignum vitge wears better than 
 brass when grit or sand is present in the water. 
 
 No. 6. — Condenser Tubes and Ferrules (with dimensions). 
 
 The tubes are about ttV inch in thickness and are composed 
 of 70 per cent, copper and 30 per cent, zinc; sometimes a small 
 per cent, of tin is also added. Lamp wick soaked in oil is used 
 as packing in Naval practice. 
 
i8o 
 
Notes and Sketches of Various Details 
 
 i8i 
 
 No. 5.— Section of Stern Tube showing Lignum Vitse Strips. 
 
 K, Check plate to keep strips in position aft. L, Lignum vitae strip. 
 
 The shaft (hollow) is shown in section. The clearance 
 spaces between the strips is to allow of the admission of water 
 for lubrication inside the tube. Lignum vitae wears better than 
 brass when grit or sand is present in the water. 
 
 No. 6. — Condenser Tubes and Ferrules (with dimensions) 
 
 The tubes are about -^^ inch in thickness and are composed 
 of 70 per cent, copper and 30 per cent, zinc; sometimes a small 
 per cent, of tin is also added. Lamp wick soaked in oil is used 
 as packing in Naval practice. 
 
l82 
 
 Verbal " Notes and Sketches 
 
 No. 7.— End View of Thrust Block Shoe. 
 
 The right half shows the white metal bearing surface of the shoe, and the 
 left half the hollow cast interior with cooling water connection. The seating 
 of the block for bolting down is also shown on the right. 
 
 The pressure on the shoes is usually about 50 lbs. per square inch, and the 
 total pressure on the thrust is estimated as follows: — 
 
 \"P-^33000x§^total lbs. on thrust. 
 ship knots X 6080 
 
 60 
 
 NOTE. — Two-thirds of the total I.H.P. is assumed as the effective power applied 
 
 to the thrust block. 
 
 No. 8.— Thrust Block (Part Section) with End Bearing:, 
 
 The thrust seating is clearly shown, and the check angle plates fitted at 
 the ends to secure the block in position. The oil service to the white metal 
 surfaces of the shoes is also shown. Each shoe has separate adjustment by 
 means of the two horizontal studs and double nuts shown. 
 
 NOTE.— With engines running ahead the pressure is on the after surface of the 
 thrust rings for either a right or left hand propeller. 
 
 I 
 
Notes and Sketches of Various Details 
 
 i8 
 
 No. 9.— I. P. Cylinder Starting Valve. 
 
 S, Steam to valve. C, Steam to I. P. receiver. 
 
 E, Steam to L.P. receiver. 
 
 By means of the valve shown, the live steam can be given to 
 either the I. P. or L.P. receiver to assist the starting of the engines. 
 The LP. cyhnder illustrated is fitted with a piston valve (outside 
 steam), the liner for the top end only being shown in the sketch. 
 
i84 
 
 " Verbal " Notes and Sketches 
 
 No. 10.— L. P. Piston (Naval Type). 
 
 P, Ring plate, to hold piston rod nut in place against screwing back. 
 
 The piston ring is forced outwards by a number of small 
 spiral springs fitted in recesses in the piston body, the pressure 
 exerted being about 2 lbs. per square inch. The junk ring and 
 piston flange are checked to prevent the piston ring from 
 coming in. 
 
 The junk ring J is secured to the piston by steel collar studs 
 with gun-metal nuts, which are held in place by a steel guard 
 ring G. The guard ring G is again secured by square-necked 
 studs with nuts and split pins. 
 
 For an L.P. piston 81^ inches diameter, the piston thickness 
 T— 2y inches, and S= i^ inches. 
 
Notes and Sketches of Various Details 
 
 ■85 
 
 [No. II.— Air Pump Driven by Separate Lever (Naval Type). 
 
 D, Inspection Door. 
 
 On up stroke, foot valves and head valves open. 
 On down stroke, bucket valves open. 
 
 The air and vapour together with the condensed water is 
 removed by the air pump, thus reducing the pressure in the 
 condenser below that of the atmosphere, the result of which is 
 to increase the M.E. pressure on the L.P. piston and the work 
 done by the engine. 
 
i86 
 
 " Verbal " Notes and Sketches 
 
 f>^='^ 
 
 No. 12. — Displacement Type Air Pump ("Edwards" Type) 
 Bucket with Water Packing Grooves. 
 
 Air pump buckets are often packed as shown, in place of 
 the usual rope packing. 
 
 No. 13.— Valve Spindle Eye Bush. 
 
 The bolts shown are reduced in diameter between the 
 bearing parts similar to those fitted in connecting rod bottom 
 ends. 
 
No. 14 
 
 1, Dou'i^lc-beat or > 
 
 2, Throttle or butt 
 
 3, Drain. 
 
 The valve si 
 the steam enteri 
 arrangement allc 
 at the top valvi 
 the valve. 
 
 The expans 
 long studs nutte 
 check collar, stu 
 steam on, say, a 
 
 The drain i 
 accident when s 
 
No. 14.— Double-Beat Valve, Throttle Valve, and Expansion Joint. 
 
 Doul^le-beat or eqmlibrium valve. 
 Throttle or butterfly valve. 
 , Drain. 
 
 4, Brass internal pipe. 
 
 5, Cast iron. 
 
 6, Copper or steel pipe. 
 
 7, Nut. 
 
 8, Spindle dow 
 g, H.P. chest. 
 
 The valve shown is commonly fitted as an engine-ioom stop-valve, and is ol the balanced tj pc. 
 the steam entering from the centre and flowing out by means of the lower and upper valves ; this 
 arrangement allowing of easy manipulation. The chief drawback is the tendency to leakage 
 at the top valve, due to unequal expansion of the brass spindle and the cast-iron chest ot 
 
 ^ The expansion joint consists of a small stuffing-box gland and safety collar with at least two 
 long studs nutted as shown ; the internal portion of the steam pipe is separate and of brass, ine 
 check collar, studs, and nuts shown prevent the pipe from being blown out by the action ot tne 
 steam on, say, a bend of the pipe. j „,„„» 
 
 The drain is an important fitting, as by neglect of its use water may accumulate and cause 
 sccident when steam is turned od by the action known as "water hammer. 
 
 yro/a. 
 
 1S6. 
 
Notes and Sketches of Various Details 
 
 187 
 
 fo. 15*— Column, Pump Lever, Air 
 and Feed Pumps. 
 
 The sketch shows the usual arrangements of the pumps when driven 
 by levers, the circulating pump being independent and of the centrifugal 
 type. Observe the guide for the pump crosshead, also the heavy links from 
 pump lever to crosshead. The average sizes of pumps for an engine of 
 1200 I.H.P. would work out as follows : — 
 
 Cylinders, 24", 40", 66" ; stroke, 42". 
 Pump strokes = 21". 
 Then, Air pump volume = ^^ of L. P. cylinder volume. 
 
 And, Feed pump volume (each) =7^^ ,, „ 
 
 /66^ 
 
 1, Diameter of air ipump = / —. 
 
 2. Diameter of each feed pump = . / ^^^ 
 
 V 700X21 
 
 * Reprinted by kind permission from T^ Mechanical World, 
 
 14 
 
 ^^ = 24" (nearly). 
 
 3-5" 
 
i,< 
 
 I 
 
Notes and Sketches of Various Details 
 
 187 
 
 fo. 15*— Column, Pump Lever, Air 
 and Feed Pumps. 
 
 The sketch shows the usual arrangements of the pumps when driven 
 by levers, the circulating pump being independent and of the centrifugal 
 type. Observe the guide for the pump crosshead, also the heavy links from 
 pump lever to crosshead. The average sizes of pumps for an engine of 
 1200 I.H.P. would work out as follows : — 
 
 Cylinders, 24", 40", 66" ; stroke, 42". 
 Pump strokes = 21". 
 Then, Air pump volume = ^^ of L.P. cylinder volume. 
 
 And, Feed pump volume (each) =j^^ ,, „ 
 
 1. Diameter of air (pump = a / ^ ^ ^- = 24" (nearly). 
 
 2. Diameter of each feed pump = /^rU^ 4^ _ -.c" 
 
 V 700x21 ^^ 
 
 * Reprinted by kind permission from TAe Mechanical World. 
 14 
 
1 88 
 
 "Verbal" Notes and Sketches 
 
 ■cs-m^ 
 
 No. i6.— Air Pump Valve 
 (Indiarubber Type). 
 
 The plan shows the holes formed 
 in the valve guard (left half) through 
 which the air pressure forces the 
 valves back on to their seats. The 
 right half of the plan shows the 
 holes in the grating through which 
 the vapour and water passes. 
 
 No. 17. — Air Pump Valves. 
 
 The upper valve is of rubber, 
 the lower one is metallic ("King- 
 horn "), the lift of the latter being 
 about |- or -/^ inch and the lift of 
 the former about | inch at outer 
 circumference of valve. 
 
 No. 18.— Air Pump Valves (Metallic Type). 
 
 The lower valve shown is filled with a light spring. 
 
^otes and Sketches of Various Details 
 
 189 
 
 ui 
 
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 bCT3 
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 to meet the 
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I90 
 
 Verbal " Notes and Sketches 
 
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 3 
 
 
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Notes and Sketches of Various Details 
 
 191 
 
 -fe-<(S< 
 
 # 
 
 No. 21.— Edwards Type Air Pump (with Displacement 
 
 Bucket). 
 
 Observe the air inlet ports near the bottom, also that head 
 valves only are fitted. The pump as shown is independent and 
 is driven by a separate engine (Naval practice). 
 
192 
 
 "Verbal" Notes and Sketches 
 
 > (J " 
 
 - ^ o 
 
 \n\o ** 
 
 bo 
 
 I 
 
 
 b 
 
 OJ' 
 
 
 (U 
 
 fi(l 
 
 
 c 
 
 s 
 
 
 3 
 
 
 U 
 
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 rC 
 
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 U 
 
 2^ ^0 
 
 
 Oj 
 
 >» K^ 
 
 
 rt 
 
 
 
 ^ W 1— « 
 
 1) 
 
 > 
 
 o 
 rt 1 
 
NOTE. — The astern guide surface =80 per cent, of ahead guide surface. 
 
AIR VESSEL--^ 
 
 FROM FEEDPUMP 
 
 AIR VESSEL uHIhoTWELL 
 
 FEEDPUMP SUCTION 
 DONKEY PUMP SUCTION 
 FEED PUMP SUCTION 
 
 SUCTION FROM CONDENSER 
 
 No. 23.— Condenser and Air Pump Connections. 
 
 After the exlnust steam from the L.P. cylinder is condensed, the water of condensation falls to the bottom of the 
 condenser, and together with the air and yapoar present is drawn out by the air pump, passing successively through ibe 
 foot valves, bucket valves, and bead valves into the hot-well, some of rlie air and vapour escaping through the bot-wcll 
 overflow pipe ; the water is drawn off hy the feed pumps, and passing through the suction valve and delivery valve, is 
 forced into the feed lieaier. In case of accident to the main feed pumps the general service donkey is usually arranged 
 to draw from the hot-well, if required, as shown in tlie sketch. 
 
 Pet Valve— The pet valve is placed just under the head valve so as to draw in air for cushioning pur])oses in the 
 tUwn itroke orilv, thus leaving the condenser vacuum unaffected. 
 
 Tail Valve. —This valve opens outwardly and is intended to relieve the pump from over pressure of water. 
 
 NOTE.- Occasionally the general service donkey is also arranged to draw from tbc bottom of the condenser in case of 
 breakdown of the air pump : this is a standard connection when Weir pumps are 6tted. 
 
 ilo/aiepage 19J. 
 
Notes and Sketches of Various Details 
 
 19: 
 
 
 No. 24.— Piston Rod Crosshead and Shoe 
 ("Single" Guide Type). 
 
 D= Crank pin diameter x 'SS, 
 L=Dxi.2. 
 
 NOTE. — The astern guide surface =80 per cent, of ahead guide surface. 
 
: ■„. .-;»& 5J»b-- .■■.'-.« 
 
 ■;0 
 
 ol 
 
 <U 
 
Notes and Sketches of Various Details 
 
 19: 
 
 No. 24.— Piston Rod Crosshead and Shoe 
 ("Single" Guide Type). 
 
 D = Crank pin diameter x 'SJ. 
 L=Dxi-2. 
 
 NOTE.— The astern guide surface =80 per cent, of ahead guide surface. 
 
194 
 
 "Verbal" Notes and Sketches 
 
 
 C^p-TTt^ 
 
 tnr 
 
 f=p 
 
 1 i I I 
 
 \£J 
 
 * No. 26.— Single Guide Type Solid Crosshead. 
 
 In this pattern the Crosshead Pin is shrunk into the 
 connecting Rod Jaws. 
 
 No. 27.— Balance Weight for Crank. 
 
 B, Riveted bolt. 
 
 C, Dowel pins fitted half into web and half into weight (a driving fit). 
 
 * Reprinted by permission from "Marine Engine Design." Prof. Edward M. 
 D. Van Nostrand Co., New York, 1910. 
 
No. 25.— Condenser and Circulating Water Connections. 
 
 A, Main injection valve. 
 
 B, Bilge injection valve. 
 
 C, Bilge strum. 
 
 D, Injection pipe leading to pump suction. 
 
 E, Ballast pump circulating pipe to condenser. 
 
 F, Centrifugal circulating pump. 
 
 G, Centrifugal pump delivery to condenser. 
 H, Condenser division plate. 
 J, Circulating discharge pipe. 
 K, Side discharge valve. 
 NOTE.— In the condenser about 60 per cent, of the heat in the steam is rejected, representing 
 
 L, Exhaust (or eduction) pipe from L.P. cylinder to condenser. 
 
 M, Air pump suction pipe from condenser bottom. 
 
 N, Auxiliary sea water feed. 
 
 O, Auxiliary fresh water feed from tanks 
 
 P, Vacuum gauge pipe. 
 
 R, Soda cock. 
 
 S, Cock to allow escape of air. 
 
 T, Cock to allow escape of air. 
 
 W, Cooling water to guides. 
 
 V, Evaporator feed. 
 
 oidable loss : this is due to the transfer of the 
 
 'atent h&t units of the steam to the circulating v/ater, which transfer is necessary for condensation to take place. If the injection water enters at, say, a 
 temperature of 65* Fahr., the discharge tempiirature would be somewhere about 110" Fahr., so that the discharge water is thus raised in temperature 
 by absorbing the latent heat (approximately 1000 B T.U. per pound of steaml of the exhaust steam. 
 
 NOTE. — The evaporator is fed witli the condenser discharge water, at a temperature of, say llo°, as less heat is then required for evaporation. 
 
 [Tc/actfagt 194. 
 
Notes and Sketches of Various Details 
 
 195 
 
 
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a. Riveted bolt. 
 
 C, Dowel pins fitted half into web and half into weight (a driving fit). 
 
 * Reprinted by permission from "Marine Engine Design." Prof. Edward M. Bragg. 
 D. Van Nostrand Co., New York, 1910. 
 
Notes and Sketches of Various Details 
 
 195 
 
 
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 w 
 
 
 
 
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196 
 
 "Verbal" Notes and Sketches 
 
 No. 29— Piston Rod (Naval Type) showing Method of 
 Removing Piston. 
 
 F, Dog by means of which the double clamp E draws the piston off the rod. 
 
 NOTE. — When the nuts of the hinged bolts are tightened up the 
 clamp E acts to draw the piston off the rod. 
 
Notes and Sketches of Various Details 
 
 197 
 
 c 
 
 OIL BOX. 
 
 p 
 
 Y\ 
 
 'i\ 
 
 fT*^ 
 
 9 ^ 
 
 
 
 
 
 1 
 
 
 
 
 
 
 <• 1 
 
 n 
 
 
 
 ^ 
 
 V 
 
 *\ 
 
 s -J 
 
 ^ 
 
 
 
 
 
 No. 30.— Syphon Feed Oil Box (on Cylinders). 
 
 1, To ahead guide. 
 
 2, To astern guide. 
 
 3, To crosshead. 
 
 4, To crank pin. 
 
 5, To crank pin. 
 
* No. 33— Crosshead Block with Dimensions for a 
 5|-inch Piston Rod. 
 
 
 No. 34.— Reversing Bell Crank with Expansion Slot. 
 
 F, Ahead position. S, Astern position. 
 
 Notice that linking up is only possible when in ahead gear, as when in 
 astern gear the expansion slot is in a vertical position, so that any change of 
 position of the block has little or no effect on the drag link. 
 
 I 
 
 r 
 
 
 _^ r 
 
 -0 
 
 < — ■ — 
 
 x:-" 
 
 ^J 
 
 No. 35.— Diagram Sketch of Double-Beat Valve. 
 
 Steam enters from the boilers by the right hand branch, and is admitted 
 to the engine through both valve openings ; the upper valve having the 
 larger area allows of easy manipulation owing to the equilibrium obtained. 
 
 * Reprinted bj' permission from "Marine Engine Design." Prof. Edward M. Bragg. 
 D. Van Nostrand Co., New York, 1910. 
 
Name 
 
 OF 
 
 Auxiliary. 
 
 
 < 
 
 
 
 <I1J 
 
 > 
 
 < 
 
 -J 
 
 Z(0 
 
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 if 
 
 
 
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 4 
 
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 < 
 
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 (39 
 ZD 
 
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 1- z 
 
 CiRCULATINa 
 
 Pump. 
 
 sue, 9 
 
 OIS. 
 
 o 
 
 
 
 
 
 • 
 
 
 
 o 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Ballast Pump 
 
 sue, 
 
 015 
 
 o 
 
 o 
 
 
 
 
 • 
 
 • 
 
 # 
 
 o 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 FeED Pumps. 
 
 sue, 
 
 DIS 
 
 • 
 
 
 o 
 
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 General 
 SERVICE Donkey. 
 
 sue, 
 DIS 
 
 • 
 
 
 
 
 o 
 
 • 
 
 
 • 
 
 • 
 
 o 
 
 
 
 
 O 
 
 
 o 
 
 o 
 
 
 
 
 
 
 
 
 
 
 auxiliary 
 Feed Pump. 
 
 sue, 
 
 DIS, 
 
 • 
 
 
 
 
 o 
 
 
 
 
 
 
 
 
 • 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Fresh 
 Water Pump 
 
 sue. 
 
 DIS. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 • 
 
 
 
 
 
 
 
 
 
 
 
 
 Hot Water Pump 
 
 sue. 
 DIS, 
 
 • 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 • 
 
 
 
 
 
 
 
 Refrigerator 
 Pump 
 
 sue, 
 
 DIS, 
 
 • 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 o 
 
 
 
 
 
 
 
 Sanitary Pumps 
 ON M. Engines. 
 
 sue 
 DIS, 
 
 • 
 
 
 
 
 
 
 
 
 
 
 
 
 
 o 
 
 
 
 o 
 
 
 
 
 
 
 
 
 
 
 Evaporator Pump 
 
 sue 
 DIS, 
 
 • 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 O 
 
 
 • 
 
 
 
 
 
 
 Injector 
 
 sue, 
 
 OIS, 
 
 • 
 
 
 
 
 o 
 
 
 
 
 
 
 
 
 • 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Bilge Pumps 
 ON M. Engines. 
 
 sue 
 
 DIS. 
 
 A^ 
 
 ford 
 
 PUM 
 
 P ONL' 
 
 < 
 
 
 
 • 
 
 
 o 
 
 
 
 
 
 
 0^-F0R3. PU 
 
 MP CNLY, 
 
 
 
 
 
 
 
 Feed Pumps 
 ON M Engines. 
 
 sue. 
 
 OIS 
 
 
 
 
 o 
 
 
 • 
 
 
 
 
 
 o 
 
 o 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ^^Al^l Condenser 
 
 sue 
 
 DIS 
 
 • 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 • 
 
 
 
 
 
 
 
 
 
 
 
 Air Pumps, 
 
 sue. 
 
 DIS. 
 
 
 • 
 
 
 
 
 o 
 
 
 o 
 
 — Ht 
 
 ITWE 
 
 L OV 
 
 ERFL 
 
 )W. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 note #= suction from'.' 
 0= "discharge to" 
 
 clearly 
 
 No. 31.— Pump Connection Diagram. 
 
 ''j"k*'"'™ '*'"'* ^'"""^ '""' "" rarious pump suction and discharge connections can be laid o£f in diagram form, so that any can be at 
 located by reference. All the suction connections are shown as dark circles, and the discharge connections as open circles. 
 
 If the pumping arrangements are in any way complicated, a diagram made out similarly to the one shown above will be found of great benefit. 
 
 Referring above to the "General Service Donkey" connections it will be seen that this pump is arranged to draw from either the Sea, Hot-well, Main 
 Bilge, or Ballast Tanks, and to discharge to Auxiliary Feed, Overboard, Sanitary Tank, Deck, or to the Distiller. The other pump connections can be traced 
 out 10 the same way. 
 

1, Main feed pump suction from hot-well. 
 
 2, Main feed pump suction pipe. 
 
 3, Suction valve of main feed pump. 
 
 4, Delivery valve of main feed pump, 
 
 5, Relief valve of main feed pump. 
 
 6, Pet (air) valve. 
 
 No. 32.— Feed Pump Connections. 
 
 7, Pressure balance connection betv^een feed pump and hot-well. 
 
 8, Test cock (for temperature of water). 
 
 9, Regulating valve. 
 
 10, Main feed pump discharge to filter and heater. 
 
 11, Heating steam from I. P. or L.P. receiver. 
 
 12, Donkey feed pump suction from heater. 
 
 13, Donkey feed pump delivery to boilers. 
 
 14, Boiler feed check valve. 
 
 15, Cord for quick opening of heater to atmosphere when stopping engices- 
 
 16, Air pipe connection to condenser. 
 
 17, Steam to donkey feed pumps. 
 
 18, Pressure gauge. 
 
 Description.— The mam feed pumps deliver the feed water at a temperature of, say, 140" into the 
 filter; after passmg through the filtermg cloths it enters the feed heater at the same temperature, but is 
 c^ed tn the^h^elteT^'^^''^^ '^"^'"^ ^'*^"* '^^° *^ *^^"' "''°' ^^^ ^^^^P^'^^^^^ depending on the pressure 
 
 As is well known the heating is effected by live steam placed in direct contact with the water, and 
 this result* m the condensation of the steam, the latent heat of which is thus given up to the feed water 
 
 nd re-enters the boilers, 
 vould have been rejected i 
 
 Had the steam gone to the condenser instead of the heater the latent heat 
 in the form of heated sea water (condenser discharge). This saving of tlie latent 
 heat units more than counterbalances for the loss of work by the steam havmg been drawn from, say, the 
 L.P. chest, and not having- expanded and done work in the L.P. cylinder in the usual way. The heater 
 is therefore similar in action to a jet condenser as the steam is condensed direct by a spray of colder water. 
 
SKCTION IV. 
 
 SLIDE VALVES, PISTON VALVES, VALVE 
 
 DATA. ETC. 
 
 Duties of Valve. 
 
 The slide valve (or piston valve) has the following duties to 
 perform : — 
 
 1. To admit the steam to the cylinder. 
 
 2. To cut ofif the supply of steam. 
 
 3. To open the port to exhaust (Release). 
 
 4. To close the port to exhaust (Compression), and so retain some 
 of the steam for cushioning. 
 
 Valve Travel. 
 
 The travel of a valve is equal to (Steam Lap + Port Opening) x 2. 
 Suppose lap to be 2 in. and port opening i^ in., then 2+ii = 3^- in., 
 and 3A X 2 = 7 in. travel of a valve. 
 
 No. I. 
 
 The narrow part of the eccentric subtracted from the broad part 
 equals the travel (Sketch No. i ). 
 
 Therefore, 7-2 = 5 in. Travel. 
 
 Or, take the distance from the centre of shaft to centre of eccentric 
 and multiply by 2 ; this also gives the travel of valve. 
 
 Thus, 2-5 X 2 = S in. Travel. 
 
I 
 
 ^^1 
 
 h\ 
 
 dHMi^ 
 
SECTION IV. 
 
 SLIDE VALVES, PISTON VALVES, VALVE 
 
 DATA, ETC. 
 
 Duties of Valve. 
 
 The slide valve (or piston valve) has the following duties to 
 perform : — 
 
 1. To admit the steam to the cylinder. 
 
 2. To cut ofif the supply of steam. 
 
 3. To open the port to exhaust (Release). 
 
 4. To close the port to exhaust (Compression), and so retain some 
 of the steam for cushioning. 
 
 Valve Travel. 
 
 The travel of a valve is equal to (Steam Lap -f Port Opening) x 2. 
 Suppose lap to be 2 in. and port opening i| in., then 2+ii = 3| in., 
 and 3^X2 = 7 in. travel of a valve. 
 
 No. I. 
 
 The narrow part of the eccentric subtracted from the broad part 
 equals the travel (Sketch No. i). 
 
 Therefore, 7-2 = 5 in. Travel. 
 
 Or, take the distance from the centre of shaft to centre of eccentric 
 and multiply by 2 ; this also gives the travel of valve. 
 
 ' Thus* 2'SX2=S in. Travel. 
 
 199 
 
200 
 
 " Verbal " Notes and Sketches 
 
 Steam Lap is the amount the valve face covers the steam port when 
 the valve is at half stroke, and is for cutting off" the steam to cause 
 expansion, therefore the more lap the valve has, the sooner on the 
 stroke will the cut-off" take place, and vice versa. The bottom steam 
 lap is less than the top. 
 
 Exhaust Lap (usually at bottom end of valve) is the amount the 
 exhaust edge of the valve covers the bar when the valve is at half 
 stroke, and is for causing compression and cushioning. 
 
 No. 2.— Slide Valve. 
 
 S, Steam Lap. £, Exhaust Lap. 
 
 Minus Exhaust Lap (usually at top end of valve) is the amount 
 the exhaust edge of the valve is short of the bar when the valve is 
 at mid stroke : it causes the exhaust to open early and close late, 
 and thus reduces the cushioning. 
 
 Lead is the amount the port is open for steam when the crank is on 
 the top or bottom centre, and is for giving the engine a turning 
 movement over the centre. 
 
 The bottom lead is always more than the top, to allow for the 
 weight of the moving parts to be lifted up against gravity. 
 
 To cut off sooner with the main valve, steam lap must be put on and 
 the eccentric advanced an equal amount to keep the lead the same. 
 
Slide Valves, Piston Valves, Valve Data, &c. 201 
 
 / 
 
 1 
 
 f 
 
 ^ 
 
 Fitted with double tongue piece. 
 
-Trick Double Ported 
 Valve. 
 
 At Position of Mid Travel. 
 
 For the valve shown the width 
 of steam port = half travel of valve. 
 The advantages of this type of 
 valve are : — 
 
 1. Reduced travel. 
 
 2. Reduced face friction. 
 
 No. 4.- Trick Double Ported 
 Valve. 
 
 At Position of Maximum Steam Opening 
 at Top. 
 
 Notice that half the steam 
 supply is admitted over the top 
 edge of the valve, and the other 
 half from the bottom by means of 
 the internal port, as shown clearly 
 by the arrows. 
 
 Pulley Position for above. 
 
 Pulley Position for above. 
 
 \To/atr fa/;e 200. 
 
Slide Valves, Piston Valves, Valve Data, &c. 201 
 
 No. 5— Common Double 
 Ported Valve. 
 
 No. 6.— "Trick" Double 
 Ported Valve. 
 
 S, Steam Lap. E, Exhaust Lap. Valve Opening to Steam at Top, 
 
 /- 
 
 
 
 ^ 
 
 
 L_ 
 
 < 
 
 r 
 
 
 
 
 ■ '^ 
 
 
 
 J 
 
 ^ 
 
 r 
 
 No. 7.— Piston Valve Ring. 
 
 Fitted with double tongue piece. 
 
200 " Verbal " Notes and Sketches 
 
 Ste; 
 
 the 
 exp. 
 stro 
 lap : 
 
 Ext 
 
 exhj 
 strol 
 
 Mini 
 the e: 
 at mi 
 and t 
 
 Lead 
 
 the t( 
 
 move 
 
 Tl 
 
 weigh 
 
 To Cl ^ ...^... ,^.,^, oi.v.«ixi lap must be put on and 
 
 the eccentric advanced an equal amount to keep the lead the same. 
 
Slide Valves, Piston Valves, Valve Data, &c. 201 
 
 No. 5— Common Double No. 6.— "Trick" Double 
 Ported Valve. Ported Valve. 
 
 S, Steam Lap. E, Exhaust Lap. Valve Opening to Steam at Top, 
 
 ^ 
 
 
 ^ 
 
 
 / 
 
 
 ^ 
 
 ■ V 
 
 
 _y 
 
 ^ 
 
 No. 7.— Piston Valve Ring. 
 
 Fitted with double tongue piece. 
 
202 
 
 "Verbal" Notes and Sketches 
 
 To cut off later with the main valve, steam lap must be taken off and 
 the eccentric put back an equal amount to keep the lead the same 
 
 No. 8. — Piston Valve and Balance Piston (Admiralty Type). 
 
 NOTE.— The packing rings are, in this case, of the solid pattern, the cut ends 
 being bolted together by lugs shown in the upper section view. 
 
 This valve takes steam from the ends and exhausts to the 
 centre ; the eccentric keyseat position is therefore similar to that 
 of a slide valve : at 90° + mean steam lap and lead in advance 
 of the crank. The balance piston has the chest steam pressure 
 on the under side, and the condenser pressure on the upper side, 
 a pipe connection from the top of the balance cylinder leading 
 to the condenser. 
 
Slide Valves, Piston Valves, Valve Data, &c. 203 
 
 Double Ported Valves. 
 
 A double ported slide valve has only half the travel of a single 
 ported valve, and the face friction is less, owing to the steam pressure 
 in the inner ports tending to case the valve off the cylinder face. In 
 the common valve the inner ports receive steam from the sides, but 
 in the Trick valve the steam passes either from bottom to top or from 
 top to bottom. 
 
 No. 9.— Double Ported Slide Valve and Relief Ring. 
 
 T, Steam port width (about •*] of which = steam opening). 
 L, Minus exhaust lap (sometimes called "internal lead"). 
 
 E, Exhaust port of cylinder. 
 N, Depth of valve inside. 
 
 F, Packing of ring. 
 
 C, Connection to condenser (to relieve friction). 
 
 NOTE. — In the case of L.P. valves it is sometimes found of 
 benefit to bore, say, ten or twelve |-inch holes through the back metal 
 of the valve, thus opening up additional connections to the condenser. 
 This alteration has resulted in an improved vacuum on the back of 
 the valve, the usual vacuum carried ranging from i8 in. to 22 in. 
 
204 
 
 Verbal " Notes and Sketches 
 
 No. 10.— Slide Valve Relief Frame. 
 
 L, Faced brass ring. 
 
 T, Springs to keep ring up to back of valve. 
 
 C, Space in connection with condenser, 
 
 NOTE.— The studs (six or eight in number) can be screwed up to gvv& additional 
 compression to the springs. 
 
 The small black sections shown in the brass ring represent soft packing. 
 
 No. II.— "Restricted" Type Packing Rings. 
 
 The ring expansion is limited by the small projections formed 
 on them which fit into corresponding recesses in the carriers. 
 The tongue piece is shown in the small views on the top. 
 
 Depth of Rings W=: Lineal piston clearance x 2. 
 
Slide Valves, Piston Valves, Valve Data, &c. 205 
 
 No. 12.— Andrews and Martin 
 Balanced Slide Valve. 
 
 This valve is of the balanced or 
 equilibrium type, steam being ad- 
 mitted from back and front through 
 the ports shown ; the face friction 
 is thus considerably reduced. 
 
 No. 13.— Piston Valve fitted with 
 Two Solid Packing Rings. 
 
 The rings are turned larger than the 
 bore of valve chest liners, cut, bolted 
 together as shown in the plan, and fin- 
 ished to fit liner diameter. A tongue 
 pieceof usual construction is also fitted. 
 
 The Andrews-Martin valve is shown in the position of steam " admission " 
 at top, and exhaust at bottom. This valve is known among engineers as 
 the "Matchbox" valve. The wear of the valve faces can be taken up by 
 means of liners fitted in behind the spring on the back casing, which is 
 adjustable. 
 
206 
 
 Verbal " Notes and Sketches 
 
 No. 14- — Solid Type Piston 
 Valve (Inside Steam). 
 
 In this type of piston valve 
 (steam inside) the eccentric keyseat 
 position = 90° - mean steam lap and 
 lead, following the crank. 
 
 No. 15.— Hollow Type Piston 
 Valve with Rings (Outside 
 Steam). 
 
 In this type of piston valve (steam 
 outside) the keyseats are cut at an 
 angle of 90° + mean steam lap and 
 lead, in advance of the crank. 
 
 NOTE.— Piston valves are usually arranged with steam inside and exhaust 
 over ends for H.P. cylinders, and with steam over ends and exhaust in centre 
 for I. P. or L.P. cylinders. 
 
Slide Valves, Piston Valves, Valve Data, &c. 
 
 207 
 
 
 
 Be 
 
 
 
 a a 
 
 
 
 ^^ 
 
 
 
 Cu 
 
 
 hn 
 
 § 
 
 > 
 
 > 
 
 1 
 
 0. 
 
 »:; 
 
 
 
 
 c 
 
 
 4) 
 
 c . 
 
 r* 
 
 *-• OJ d, 
 
 
 IS 
 
 13 q! ^ 
 
 a. 
 
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 IV x: 
 
 
 
 rt'O y 
 
 0. 
 
 ho 
 
 t: !3-:= 
 
 1 
 
 .fci 
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 M 
 
 to "^ „b 
 
 M 
 
 > 
 
 <u »- "h 
 
 
 
 
 > rt 
 
 
 
 1-1 
 
 ^•-3 
 
 iz 
 
 
 
 2 E 
 
 
 
 bfi-55Ti 
 
 
 M 
 
 The 
 packing ( 
 are turne 
 
 J3 
 
 (^ 
 
208 
 
 "Verbal" Notes and Sketches 
 
 5 
 
 No. i8.— Piston Valve Packing: "Restrained" Type 
 (Admiralty Type). 
 
 The split ring is allowed only a limited expansion and contraction as shown 
 by the pin in oval hole, and by the small clearance at F. A tongue piece of 
 ordinary pattern is fitted as shown for steam tightness. 
 
 No. 19. — Inside Steam Piston Valve with 
 "Restrained" Type Packing Rings. 
 
 NOTE.— The clearance allowed at C C regulates the amount the 
 ring may expand or contract ; if the clearance is increased by scraping 
 up, the ring will then expand more in proportion. 
 
Slide Valves, Piston Valves, Valve Data, &c. 208^ 
 
 > 
 
 > 
 
 c 
 
 .2 
 '55 
 
 c 
 
 cx 
 
 M V 
 
 o 
 
 c5 n 
 > o 
 
 i .2 >» 
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 •a u 
 
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 ci 
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 CIS 
 
 ^^ 
 
 Q aj r> 
 
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 o, 9 
 
 • 4) 
 
 ° js 
 
 c ha « 
 
 4> ri 
 
 V u 3 
 
 C O 
 
 U 3 u 
 
 2 ^ ^ 
 
 0.2 
 
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 o 
 
 O wi 
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 ji s 
 
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 ^ 
 
 Vi u) 
 
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 S 0) 
 
 J3 4) «j 
 
 -w £ 4) 
 
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 CQ ^ li« E ft* H 
 
 M N CO 'd- mvo 
 
20U 
 
 "Verbal" Notes and Sketches 
 
 
 J ' 
 
 
 
 
 1 
 
 > 
 
 c 
 
 '55 
 
 c 
 
 a 
 
 1 
 
 Si 
 
 M 
 
 6 
 
 c 
 o 
 
 •43 
 1 
 
 o 
 
 3 
 
 o 
 
 n 
 
 > 
 
 o 
 
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 >-i 
 o 
 
 4-> 
 
 o5 
 
 c 
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 2i 
 ■'5 
 
 m 
 
 s 
 
 1/2 
 
 O 
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 _c 
 
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 o 
 
 (D 
 
 2 
 
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 -g 
 
 «*, 
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 t/3 
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 c 
 
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 nsion valve, the 
 3, in line with it. 
 3 out of gear to 
 
 
 
 
 5S the expa 
 rank, that i. 
 insioa plate; 
 
 
 
 /^ 
 
 
 \ r '• 
 
 r-^^T//// 1/ / 
 
 e eccentric driv 
 ^ opposite the c 
 to run the expa 
 
 
 \ 
 
 
 / 
 / 
 
 i 
 
 ^^ 
 
 
 
 ^ 
 
 
 
 irections. 
 
 the slide valve, and on 
 r being, as a rule, directb 
 in reversing it is advisable 
 ndling of the engines. 
 
 
 ij 
 
 
 ^ 
 
 $ 
 
 m' 
 
 ^I-I^ 
 
 nr J 1 1 
 
 /C^ Si- >l l/x 
 
 r 
 
 
 — p 
 
 v,^ 
 
 es travel in opposite d 
 ro pulleys are fitted t 
 position for the latte 
 itted to main engines, 
 " full steam for easy ha 
 
 
 • I — I 
 
 
 1^ S g ^ 
 
 C ) 
 
 
 ^ 
 
 
 (1) >^X O 
 
 •s ^^=i 
 
Slide Valves, Piston Valves, Valve Data, &c. 209 
 
 No. 20. — Joy's Patent Assistant Cylinder. 
 
 S, Steam admission port. N, Reduced diameter of rod. 
 
 C, Full diameter of rod which acts to cut off the steam supply. 
 
 U, Outlet port of piston to top of cylinder. «? 
 
 Note. — The inlet ports are shown at the bottom of the piston. 
 H, Recess for steam flow from under side of piston to inside of piston. 
 L, Recess for steam flow from inside of piston to upper side of piston. 
 E, Exhaust from cylinder. 
 
 Action. — Steam enters by port S, is cut off by rod shoulder C on up stroke, 
 and expands in lifting up the piston ; when expansion is completed, the steam 
 exhausts into the recess H, and from there flows into the cavity of the piston, 
 where it is retained until the small piston port U comes in line with the port L, 
 the steam then enters the top of the cylinder and cushions the piston on top 
 centre, afterwards assisting the piston on down stroke, and finally exhausting 
 .away (at greatly reduced pressure) by means of port E. 
 
 j Notice that the same supply of steam is used both for bottom and top, also 
 [that the piston cavity acts as a receiver. The piston is double acting, but the 
 : driving pressure for the top is obtained from the exhaust steam of the bottom. 
 
210 
 
 "Verbal" Notes and Sketches 
 
 No. 21. — Diagrams from Joy Assistant Cylinder. 
 
 The lower diagram is from the bottom and the upper one from the 
 top of the cylinder. 
 
 T, Admission at bottom. 
 
 C, Cut-off at bottom. 
 
 P, Exhaust at bottom to top. 
 
 O, Admission at top. 
 F, Compression at top. 
 £, Exhaust at top. 
 
blide Valves, Piston Valves, Valve Data, &c. 2 1 1 
 
 No. 22.— "Open" and "Crossed" Eccentric Rods (in 
 "Ahead" Gear). 
 
 With crank on bottom centre, the full lines show the eccentric 
 rods as "open" and the dotted lines as "crossed," the ahead 
 pulley being A. " Open rods " is the usual arrangement as it 
 allows of better link expansion when the gear is shut in (see 
 page 257) and gives full lead in any position of link. 
 
212 
 
 "Verbal" Notes and Sketches 
 
 No. 23.— Eccentrics in "Ahead" and "Astern" Positions. 
 
 D = Valve travel x 3. 
 
 E = Distance between ahead and astern pulley. 
 
 Full lines show gear "ahead." Dotted lines show gear astern. 
 
 The difference in the link position in the two cases shows 
 how the valve operates in reversing the engine, as the top port 
 may be open for steam in one position, and the bottom port 
 open for steam in the other. 
 
Slide Valves, Piston Valves, Valve Data, &c. 213 
 
 No. 24.— Reversing Gear and Link Expansion Slot. 
 
 In this arrangement the reversing engine is fulcrumed on 
 the bed-plate, the piston rod of the gear then acting direct on a 
 forked arm keyed to the reversing (wyper) shaft. As usually 
 arranged, the hydraulic cylindei; is above and the steam 
 cylinder below. 
 
214 
 
 "Verbal" Notes and Sketches 
 
 No. 25.— Combined Steam and Hydraulic Reversing Gear 
 (Brown's Patent). 
 
 This type of reversing gear consists of a steam cylinder 
 below and a controlling oil cylinder above, the piston rod being 
 common to both. The piston rod connects by a crosshead and 
 pair of links to the reversing shaft bell crank. 
 
 Action. — The steam cylinder valve has no lap, and a bye- 
 pass valve on the oil cylinder is worked by a continuation of 
 the steam cylinder valve spindle. The two valves mentioned 
 are actuated by a lever (shown in sketch), also by a secondary 
 gear connected with the reverse motion, so that a " hunting " 
 arrangement is obtained which causes the gear when moving to 
 bring the valves back to mid position (shut). For hand reversing 
 a stop-cock is fitted in the bye-pass pipe of the oil cylinder and a 
 small pump connected up to it. The oil cylinder piston is packed 
 by means of two cup leathers (Sketch No. 26). For an engine 
 with cylinders, 35J inches, 53 inches, and 63 inches (two), stroke 
 48 inches, the reversing engine dimensions are : — 
 
 Steam cylinder diameter 
 Oil cylinder diameter - 
 Stroke 
 
 16 inches 
 
 2o| » 
 
H.P. 
 
 CASING 
 
 TOP 
 
 HP. 
 
 VALVE 
 
 TOP 
 
 CASING 
 STICK 
 
 m 
 
 14" 
 
 Sz- 
 
 I3i" 
 
 
 I 
 
 1 
 
 VALVE 
 STICK 
 
 Marking-off of Sticks. 
 
 S2 
 
 Sticks in position for "Steam 
 Lap" and ''Exhaust Lap." 
 
 No 27. 
 
 Sticks in position for "Top Lead,' 
 
 S,, Top steam lap. 
 S. . Bottom steam lap. 
 E, Bottom exhaust lap. 
 
 B, Distance top piston is from top of casing, and 
 
 sticks have to be placed to same distance. 
 P, Bottom exhaust opening; at top lead position. 
 
Slide Valves, Piston Valves, Valve Data, &c. 215 
 
 No. 
 
 26. — Leather Packing for Hydraulic Piston of 
 Reversing Gear. 
 
 Notice the grooves cut in the piston to allow of the fluid 
 pressure finding its way to the back of the cup leathers and 
 thus forcing them out against the cylinder walls. 
 
 To Measure Lead of Piston Valve (Sketch No. 27). 
 
 To measure the lead or the lap of a piston valve with steam 
 inside and exhaust at the ends, two long sticks must be cut. Having 
 drawn the piston valve out from the chest, place one of the sticks 
 alongside of it and mark the depth of the pistons, &c., on the stick 
 in the exact positions they are on the valve, as shown in the sketch 
 marked " valve stick." On the other stick, which must be equal in 
 length to the depth of the valve casing, mark the various spaces 
 corresponding to the bars and ports in the cylinder, shown on 
 "casing stick." If the valve is then placed in mid travel, and the 
 sticks put together in the same relative position, the amount of steam 
 lap and exhaust lap will be shown, and can be measured. Tc 
 measure the lead, top or bottom, have the valve chest cover off, and, 
 turning the crank to the top or bottom centre as the case may be, 
 and with the valve gear in the required position, measure how far 
 the top piston is from the top of the casing ; then, placing the two 
 sticks together in a similar position, the amount of the lead will be 
 shown, and can be measured on the sticks. The sketch shows a 
 valve with steam lap top and bottom (S^ and S,,), with exhaust lap 
 on the bottom E, but having no exhaust lap on the top. Notice that 
 the top piston is larger than the bottom one ; this allows better for 
 
 1 
 

 f^: 
 
 
Slide Valves, Piston Valves, Valve Data, &c. 215 
 
 No. 26.— Leather Packing for Hydraulic Piston of 
 Reversing Gear. 
 
 Notice the grooves cut in the piston to allow of the fluid 
 pressure finding its way to the back of the cup leathers and 
 thus forcing them out against the cyhnder walls. 
 
 To Measure Lead of Piston Valve (Sketch No. 27). 
 
 To measure the lead or the lap of a piston valve with steam 
 inside and exhaust at the ends, two long sticks must be cut. Having 
 drawn the piston valve out from the chest, place one of the sticks 
 alongside of it and mark the depth of the pistons, &c., on the stick 
 in the exact positions they are on the valve, as shown in the sketch 
 marked " valve stick." On the other stick, which must be equal in 
 length to the depth of the valve casing, mark the various spaces 
 corresponding to the bars and ports in the cylinder, shown on 
 "casing stick." If the valve is then placed in mid travel, and the 
 sticks put together in the same relative position, the amount of steam 
 lap and exhaust lap will be shown, and can be measured. Tc 
 measure the lead, top or bottom, have the valve chest cover off, and, 
 turning the crank to the top or bottom centre as the case may be, 
 and with the valve gear in the required position, measure how far 
 the top piston is from the top of the casing ; then, placing the two 
 sticks together in a similar position, the amount of the lead will be 
 shown, and can be measured on the sticks. The sketch shows a 
 valve with steam lap top and bottom (S^ and S2), with exhaust lap 
 on the bottom E, but having no exhaust lap on the top. Notice that 
 the top piston is larger than the bottom one ; this allows better for 
 
2l6 
 
 Verbal " Notes and Sketches 
 
 the withdrawing or fitting in of the valve, and also gives it a floating 
 tendency, the difference of area and of pressure lifting up the valve 
 and reducing the weight on the pulleys. 
 
 NOTE. — Sticks for ordinary slide valves (single or double ported) are 
 made and used in the same way as above. 
 
 Lead. 
 
 Slide Valves and Piston Valves. — Advancing the eccentric increases 
 the lead top and bottom equally. 
 
 Putting back the eccentric decreases the lead top and bottom 
 equally. 
 
 u — >»- 
 
 No. 28.— Piston Valve. 
 
 S, Steam Lap. E, Exhaust Lap. 
 
 Slide Valves or Outside Steam Piston Valves. — Taking out a 
 liner increases the top lead and decreases the bottom lead. 
 
 Putting in a liner increases the bottom lead and decreases the 
 top lead. 
 
 To give lead to the top only, advance the eccentric for half the 
 amount and take out a liner for half the amount. 
 
 To give lead to the bottom only, advance the eccentric for half 
 the amount and put in a liner for half the amount. 
 
 To reduce the top lead, put back the eccentric for half the 
 amount and line up for half the amount. 
 
Slide Valves, Piston Valves, Valve Data, &c. 217 
 
 To reduce the bottom lead, put back the eccentric for half the 
 amount and take out a liner for half the amount. 
 
 NOTE.— With double ported valves advancing the pulley for, say, Jt in. gives 
 i in. lead in all, as the lead is duplicated by the double ports top and bottom. 
 
 Piston Valves (Inside Steam). — Taking out a liner decrea.se.s the 
 top lead and increase.s the bottom lead. 
 
 Putting in a liner decreases the bottom lead and increases the 
 top lead. 
 
 To give lead to the top only, advance the eccentric for half the 
 amount and put in a liner for half the amount. 
 
 To give lead to the bottom only, advance the eccentric for half 
 the amount and take out a liner for half the amount. 
 
 To reduce the top lead, put back the eccentric for half the 
 amount and take out a liner for half the amount. 
 
 To reduce the bottom lead, put back the eccentric for half the 
 amount and put in a liner for half the amount. 
 
 NOTE. —The upper piston is usually slightly larger in diameter than the lower one, 
 say 14 in. diameter at top and 13 in. diameter at bottom. This is more convenient for 
 entering or drawing the valve, it also allows of balance, the top piston "floating" 
 and relieving the pulleys of the weight. 
 
 A piston valve (getting steam in the inside) has the following 
 advantages over a common slide valve : — 
 
 1. Less friction, and is better balanced. 
 
 2. Only exhaust steam pressure on the valve spindle gland 
 packing, instead of high pressure steam. 
 
 3. Reduced travel, the ports being circular and therefore longer. 
 
 Examples of Lead Adjustments. 
 
 Slide Valves. 
 
 Present Lead. 
 
 Required Lead. 
 
 No. 
 
 Top. 
 
 BoUom. 
 
 Top. 
 
 Bottom. 
 
 I 
 
 s in. 
 
 iin. 
 
 3 
 
 Te 
 
 A »n- 
 
 2 
 
 i in. 
 
 iin. 
 
 1 
 
 Ttt 
 
 i\ in- 
 
 3 
 
 1 in. 
 
 iin. 
 
 3 
 10 
 
 i\ in. 
 
 4 
 
 i in. 
 
 iin. 
 
 1 
 
 T5 in- 
 
 5 
 
 i in. 
 
 lin. 
 
 3 
 Te 
 
 'i in. 
 
 6 
 
 1 in. 
 
 iin. 
 
 1 
 TB" 
 
 } in. 
 
 16 
 
21 
 
 "Verbal" Notes and Sketches 
 
 Answers. 
 
 I. Advance pulley j^ in. 
 
 2. Put back pulley yg- in. 
 
 3. Take out yg- in. liner. 
 
 4. Put in j^g- in. liner. 
 
 a 
 
 ends. 
 
 £>. 
 steam 
 
 E. 
 steam 
 
 J^. 
 
 G. 
 travel. 
 
 f 5. Advance pulley ^\r in. and put in ^V in. liner. 
 
 1 6. Put back pulley for ^'V in. and take out tjV in. liner. 
 
 The sum of the steam lap + lead is the same for top and bottom. 
 What is gained in lead at the bottom is lost in lap, or vice-versa. 
 Advancing the pulley increases the sum of the lap + lead at both 
 
 Lining up increases the top steam lap and decreases the bottom 
 lap. 
 
 Lining out decreases the top steam lap and increases the bottom 
 lap. 
 Advancing or putting back the pulley does not alter the valve travel. 
 
 Increasing or decreasing the steam lap does not alter the valve 
 
 Inside Steam Piston Valves. 
 
 
 Present Lead. 
 
 Required Lead. 
 
 No. 
 
 Top. 
 
 Bottom. 
 
 Top. 
 
 Bottom. 
 
 I 
 
 iin. 
 
 iin. 
 
 A in- 
 
 TO in. 
 
 2 
 
 i in. 
 
 iin. 
 
 tV in- 
 
 A in. 
 
 3 
 
 i in. 
 
 iin. 
 
 T6 in. 
 
 A in. 
 
 4 
 
 I in- 
 
 iin. 
 
 tV in- 
 
 A in- 
 
 5 
 
 i in. 
 
 iin. 
 
 A in- 
 
 1 in- 
 
 6 
 
 i in. 
 
 iin. 
 
 tV in- 
 
 iin. 
 
 Answers. 
 
 1. Advance pulley ^g in. 
 
 2. Put back pulley ^g- in. 
 
 3. Put in yg- in. liner. 
 
 4. Take out y^ in. liner. 
 
 5. Advance pulley /j in- and take out ^V in. liner. 
 
 6. Put back pulley for /o in. and put in ./j in. liner. 
 
Slide Valves, Piston Valves, Valve Data, &c. 218a; 
 
 Steam Lap and Lead. 
 
 Rule 1. — 
 
 Top steam lap + Lead = Bottom steam lap + Lead. Therefore, Top steam 
 lap + Lead — Bottom lead = ]5ottom steam lap. 
 
 Rule 2. — 
 
 For unequal increase or decrease of lead top and bottom. 
 
 A. Alter pulley for half si^m of lead increase or decrease. 
 
 B. Alter liners for half dijference of lead increase or decrease. 
 
 NOTE.— If bottom lead is to be the greater, line up, but if top is to be the 
 greater, line out. 
 
 Rule 3. — 
 
 For unequal lead increase and decrease, top and bottom. 
 
 A. Alter liners for half sum of lead increase and decrease. 
 
 B. Alter pulley for half difference of lead increase and decrease. 
 
 NOTE. — The nature of the question will decide whether lines have to be 
 inserted or taken out, also whether the pulley has to be advanced or put back. 
 
 Example i. — 
 
 Top steam lap 2 niches and lead \ inch ; find bottom steam lap if the 
 lead at that end is to be \ inch. 
 
 Then, 2 + ^ = Bottom steam lap + \ inch. 
 
 Therefore, 7.\-\ = \\ inches steam lap at bottom. Answer. 
 
 So that, (Top) 2 inches + ^ inch = (Bot.) ig inches + ^ inch — 2^ inches (in both cases). 
 
 » Example 2. — 
 Present Lead, Top \ inch, Bottom \ inch. 
 Required „ „ J „ „ 4 „ 
 
 The sum of the lead increase = i + i = |. 
 
 Then, Pulley advance = § v 2 = /^ inch. 
 
 And, Liner to go in = (:i inch - ^ inch) -f 2 = yV inch thick. 
 
 NOTE. — Advancing pulley t'o inch increases lead at both ends by ^ inch, but 
 by lining up for the odd tV inch, the top is now reduced by -^ and the bottom 
 still further increased by A, giving finally \ inch at top and \ inch at bottom, 
 as required by the question. 
 
 Example 3. — 
 
 Present Lead, Top \ inch, Bottom \ inch. 
 
 Required „ „ \ ,, „ | „ 
 
 Sum of Lead difference=| + J=2 inch. 
 Then, Liner to go in, ^ inch-r2=y'8 inch. 
 
 And, Pulley advance = *iB<=hj^ii'l£h^i_ in^h. 
 
 NOTE. — The i\-inch liner put in increases bottom lead to r\ inch, and reduces 
 top lead to i^c inch, but the pulley advanced j'^ inch again corrects this by giving 
 i^c inch more at both ends, thus obtaining \ inch at top and f inch at bottom, as 
 required by the question. 
 
2 1 8^ "Verbal" Notes and Sketches 
 
 NOTE. — If minus lead is given, treat this as so much additional or plus lead 
 required, then proceed as explained above. 
 
 Example 4. — 
 
 The top lead is - i inch and the bottom lead is i inch. The lead required is 
 I inch on top and g inch on bottom. 
 
 Then, +k + l = s inch more lead required on top. 
 
 And, i-f=s „ less ,, ,, ,, bottom. 
 
 Therefore by Rule 3, «/L8_,^ inch Hner out. 
 
 And, -— -* = g inch pulley forward. 
 
 An«iJi7Pr /i-inch liner to be taken out. 
 Answer.— I ^ ^^^^ p^^^y ^^^ forward. 
 
 Example 5. — 
 
 The original lead was, top | in., bottom | in., the present lead, on testing, 
 is found to be, top - f in., bottom — i|- in. Find how much the pulley has 
 worked back on sliaft, and the thickness of liner which has dropped out from 
 under foot of rod. 
 
 Then, Total lead decrease = (r + D + (il" + h") = i"+ if ^2f . 
 
 Pulley has gone back - -^ = i ^%". Answer. 
 
 tS' _ t" 
 
 Liner thickness (out) = -5- -t^c"- Answer. 
 
 2 
 
 This question will be much easier understood if the student takes it 
 backwards, that is, assume that the present lead is top — | in., and bottom 
 - li in., and that the lead required is, top ^ in., and bottom | in. 
 
 Then by rule previously enunciated — 
 
 Total lead increase - 1" + 1" + 1 J" + V' = 21". 
 
 Advance pulley half sum = -»- = i j\". Answer. 
 
 I ^" — i" 
 Line up rod half difference = -^^ = i^a". Answer. 
 
 These answers reversed give the solution to the question as originally stated. 
 
 Lead of Double Ported Slide Valves. — For this type of valve the 
 examples given for the single ported valve also hold good, but it must be 
 remembered that the pulley or liner alterations only refer to one of the two 
 top leads or one of the two bottom leads, as advancing the pulley, say, j^ in., 
 will give i in. extra lead in all top and bottom. In the same way, lining up 
 for say y\- in. gives ^ in. more lead at bottom and ^ in. less lead at top, and 
 taking out a ^\ in. liner gives ^ in. more lead at top and i in. less lead at 
 bottom. This is owing to the duplicating of the leads at both top and 
 bottom due to the double ports. 
 
 * NOTE.— In slide valve example No. 5 observe that the pulley requires to be 
 advanced half the sum of the two lead increases top and bottom, which is equal to 
 
Slide Valves, Piston Valves, Valve Data, &c. 219 
 
 ,'g in. + k in. or i V in- in all ; the pulley is therefore advanced half of this, or ^^ in. 
 and a .'j in. liner put in to make up the difference top and bottom. 
 
 In example No. 6, as the leads have to be decreased top and bottom, the pulley 
 is put back ,■, in. and a -'j in. liner taken out. 
 
 * For the inside steam piston valve notice that liners are taken out instead of 
 being put in, and and put in instead of being taken out, to give similar lead results 
 top and bottom. 
 
 Valve Setting. — The following example of valve setting' from an 
 engine of 2500 I.I LP., will give a fair idea as to the varying pro- 
 portions of lap, lead, and port opening usually arranged for. 
 
 Valve Setting. 
 
 Cylinders, 27 in., 43 in., and 72 in.; stroke, 51 in.; pressure, 180 lbs. 
 
 
 H.P. 
 
 Valve Travel 7 in. 
 (Piston Valve). 
 
 M.P. 
 
 Valve Travel 7 in. 
 
 (Slide Valve). 
 
 L.P. 
 Valve Travel 7 in. 
 (D.P. Slide Valve). 
 
 
 Top. 
 
 Bottom. 
 
 Top. 
 
 Bottom. 
 
 Top. 
 
 Bottom. 
 
 Steam lap 
 
 2j\ in. 
 
 i]| in. 
 
 i|- in. 
 
 if in. 
 
 ijirin- 
 
 i|^ in. 
 
 Port opening 
 
 iiV in- 
 
 lA in- 
 
 if in. 
 
 if in. 
 
 ill in 
 
 iljMn. 
 
 Lead 
 
 iin. 
 
 ^in. 
 
 |in. 
 
 ^in. 
 
 Un. 
 
 fin. 
 
 Cut-off - 
 
 33i in. 
 
 29f in. 
 
 35i in- 
 
 34 in- 
 
 35-4- in- 
 
 312 in. 
 
 Per cent, of stroke 
 
 •62 
 
 (mean) 
 
 •66 
 
 (mean) 
 
 •66 
 
 (mean) 
 
 Exhaust lap 
 
 tV in- 
 
 If in- 
 
 fin. 
 
 4 in- 
 
 tV in- 
 
 I A in- 
 
 Release 
 
 4| in. 
 
 3i in. 
 
 3iin. 
 
 2i in. 
 
 3l in- 
 
 2h in. 
 
 Compression 
 
 8 in. 
 
 8|in. 
 
 9i in- 
 
 10 in. 
 
 io| in. 
 
 1 1 in. 
 
 Referring to the above table of valve setting it is important to 
 note the following : — 
 
 1. The top steam lap is more than the bottom steam lap. 
 
 2. The bottom port opening is more than the top port opening 
 in proportion to the difference of lap and lead. 
 
 3. The sum of any lap and port opening top or bottom is just 
 equal to half the valve travel. 
 
 Referring to the H.P. valve : — 
 
 Top steam lap = 2y\ in. Bottom steam lap =ij|-in. 
 
 Top port opening = iy~ in. Bottom port opening = i /^ in. 
 
 Half travel = 3I in. 
 The same holds good for each valve. 
 
 Half travel = 3I in. 
 
220 
 
 "Verbal" Notes and Sketches 
 
 4. The cut-off is earlier on the up stroke in all three engines ; 
 this is due to the angularity of the crank and connecting rod when 
 link motion valve gear is fitted. 
 
 The reverse should be the case, were it possible, as on the up 
 stroke the weight of the working parts have to be raised against the 
 force of gravity. 
 
 With patent valve gear such as Brock's, Morton's, Joy's, &c., the 
 cut-off can generally be arranged to be later on the up stroke, or 
 equal on both strokes, 
 
 5. As less compression is required at top than bottom, it will be 
 seen that the top exhaust lap is always less than the bottom, and 
 is generally " minus " exhaust lap. 
 
 To Find (approximately) the Depth of a Slide Valve. 
 
 If the valve is broken up or not to be got, proceed as follows : — 
 Obtain a flat board, and draw out on it, full size, the shaft diameter, 
 the valve travel, and two centre lines. 
 
 NOTE.— The valve travel can easily be found by taking the difference of the 
 narrow side and the broad side of the eccentric pulley. 
 
 Next, calliper on the shaft the exact distance between the 
 eccentric keyseat centres, as shown at A, B of the shaft sketch, and 
 transfer this distance to the shaft circle on the flat board, also marked 
 
 \ 
 
 No. 29. 
 
 A, B. Now, from any one of these two points run in a line to the 
 shaft centre, and where this line cuts the travel circle draw a horizontal 
 line giving the distance C. 
 
 The distance C is equal to the steam lap and lead added together 
 
Slide Valves, Piston Valves, Valve Data, &c. 221 
 
 so that if a certain lead is determined on, say g^ in., and subtracted 
 from distance C, the amount left will then be the steam lap. Finally, 
 measure the distance from the top of the top steam port to the bottom 
 of the bottom steam port, as shown at D, and add to it tivice the 
 steam lap, to allow for the top and bottom ; the result will then be 
 approximately the required depth of valve. 
 
 Or, D + ( C - lead) x 2 = valve depth. 
 
 NOTE.— The most accurate method is by that of the valve diagram (see 
 page 249), but as the cut-ofif is not given in the question as stated above, this 
 method cannot be applied. 
 
 Connecting Rod Angle, &c. 
 
 When the piston is at half stroke, as at B on the sketch, the crank 
 is lying at the angle B above the horizontal. Again, if the crank is 
 placed exactly horizontal, as at C, the piston will be a little lower than 
 half stroke, as C on the sketch. The cause, in both cases, is the angle 
 of the connecting rod, and the shorter the rod is made the greater 
 
 No. 30 
 
22 2 "Verbal" Notes and Sketches 
 
 will be the difference between the piston and crank positions at half 
 stroke. 
 
 If the slide valve has the same amount of steam lap and lead top 
 and bottom, and the valve gear is of the ordinary link motion type, 
 the effect of the connecting rod angle is to cut off the steam sooner 
 on the up stroke than on the down stroke. 
 
 In practice this difference of cut-off is partly corrected by lining 
 up the slide valve, so that the top lap is more and the bottom lap less, 
 and the bottom lead more and top lead less. 
 
 Patent Valve Gears. 
 
 Patent valve gears are fitted with the object of correcting the 
 defects peculiar to the ordinary Stephenson link motion, and which 
 are as follows : — 
 
 1. Wire drawing of steam owing to slow motion of gear at 
 moment of cut-off. 
 
 2. Variation in lead and compression when linked up (usually 
 increased). 
 
 3. Difference in cut-off on up and down stroke, with equal steam 
 lap top and bottom, due to effect of connecting rod angle with crank, 
 the cut-off being much earlier on the up stroke. 
 
 4. Space saved in fore and aft direction, as the valves can (in 
 certain cases) be placed on the sides of the cylinders. 
 
 5. Eccentrics are done away altogether in certain gears (Joy, 
 Morton), while in others (Hackworth, Brock, Bryce-Douglas, Bremme- 
 Marshall) one eccentric only is required. 
 
 Advantages of Patent Gears. — i. Most of the patent gears arrange 
 for a quick travel of valve at the instant of cut-off, and thus reduce 
 the wire drawing losses by giving a much sharper cut-off. 
 
 2. In the majority of patent gears the lead remains constant for 
 all positions of the link, whether " full out " or " shut in." 
 
 3. Certain gears are arranged with compensating rods or links 
 which give equal cut-off on both strokes, or allow for a later cut-off 
 on the up stroke, which is better still. 
 
 Disadvantage of Patent Gears. — The chief disadvantage of patent 
 gears lies in the number of joints, required, the slight wear of which 
 (in the majority of gears) upsets the valve adjustment to a more or 
 less serious degree, as the wear of, say, ^^ in. in a brass may become 
 magnified to three or four times that amount at the valve by means 
 of the lever or link connected to it. 
 
 In some gears as many as sixteen small pins and brasses are 
 fitted, all of which require to be kept in practically perfect adjustment, 
 if the correct setting of the slide valves or piston valves is to be 
 maintained. 
 

 ^ 
 
 r. Eccentric rod. 
 
 2, Swinging link centre or 
 
 3, Astern position of swin< 
 
 4, Swinging link (Radius 
 
No. 31.— Marshall Valve Gear. 
 
 1, Eccentric rod. 
 
 2, Swinging link centre on reversing btit crank. 
 
 3, Astern position of swinging link centre. 
 
 4, Swinging link (Radius Rod). 
 
 5, Link travel for "ahead." 
 
 6, Link travel for "astern.'* 
 
 7, Reversing engine. 
 
 8, Slide valve spindle. 
 
 [_T0 face pi\^* 27%. 
 
Slide Valves, Piston Valves, Valve Data, Sec. 223 
 
 The general experience of engineers is that the disadvantages 
 
 if patent gear more than balance the advantages, with the result that 
 
 the ordinary Stephenson link motion will be found fitted in even the 
 
 most modern and up-to-date marine engines, as being simpler and 
 
 more reliable than patent valve gears of any type. 
 
 Marshall- Bremme Gear (one Eccentric) (Sketch No. 31). 
 
 Marshall's and Bremme's gear are similar, the chief difference 
 being that the valve link is connected to the ejid of the eccentric rod 
 in Bremme's gear, and the swinging link to the middle, whereas in 
 Marshall's the valve link is connected to the eccentric rod about the 
 middle of its length, and the swinging link at the end. 
 
 Marshall Gear (Sketch No. 31). 
 
 Type of Valve fitted. — Slide valve or piston valve with steam 
 over ends 
 
 Position of Eccentric. — Opposite crank (180°). 
 
 Action.' — The eccentric rod i is connected to the swinging link 4, 
 which is hung on a pin 2 from the bell crank. The gear is shown in 
 "ahead" position, and the travel of the link is shown at 5. The 
 
 i 
 
 No. 32.— Link Travel of Marshall Valve Gear. 
 
 astern " position of the gear is shown at 3 and 6, as then the 
 bell crank is moved over to the right by the rod 7 from the reversing 
 engine. When the swing link is at position 3, the free end travels 
 the arc 6, and thus changes the direction of the valve travel. 
 
 The small Sketch, No. 32, shows the travel of the swinging link 
 produced by the eccentric when in ahead position. 
 
 Bremme Gear (Sketch No. 33). 
 
 As before described, in this gear the valve link is placed at the 
 end of the eccentric rod, which thus reverses the motion of the valve, 
 
Slide Valves, Piston Valves, Valve Data, Sec. 223 
 
 The general experience of engineers is that the disadvantages 
 of patent gear more than balance the advantages, with the result that 
 the ordinary Stephenson link motion will be found fitted in even the 
 most modern and up-to-date marine engines, as being simpler and 
 more reliable than patent valve gears of any type. 
 
 Marshall-Bremme Gear (one Eccentric) (Sketch No. 31). 
 
 Marshall's and Bremme's gear are similar, the chief difference 
 being that the valve link is connected to the end of the eccentric rod 
 in Bremme's gear, and the swinging link to the middle, whereas in 
 Marshall's the valve link is connected to the eccentric rod about the 
 middle of its length, and the swinging link at the end. 
 
 Marshall Gear (Sketch No. 31). 
 
 Type of Valve fitted. — Slide valve or piston valve with steam 
 over ends 
 
 Position of Eccentric. — Opposite crank (iSo°). 
 
 Action.' — The eccentric rod i is connected to the swinging link 4, 
 which is hung on a pin 2 from the bell crank. The gear is shown in 
 "ahead" position, and the travel of the link is shown at 5. The 
 
 No. 32.— Link Travel of Marshall Valve Gear. 
 
 "astern" position of the gear is shown at 3 and 6, as then the 
 bell crank is moved over to the right by the rod 7 from the reversing 
 engine. When the swing link is at position 3, the free end travels 
 the arc 6, and thus changes the direction of the valve travel. 
 
 The small Sketch, No. 32, shows the travel of the swinging link 
 produced by the eccentric when in ahead position. 
 
 Bremme Gear (Sketch No. 33). 
 
 As before described, in this gear the valve link is placed at the 
 end of the eccentric rod, which thus reverses the motion of the valve, 
 
224 
 
 *' Verbal " Notes and Sketches 
 
 so that the pulley position is now with the crank in place of being 
 opposite to it as in Marshall's gear, otherwise the gear is similar. 
 
 1, "Ahead" position of link, 
 
 2, " Astern " position of link 
 
 No. 33. — Bremme Valve Gear. 
 
 3, Valve rod link. 
 
 4, Reversing engine rod. 
 
 Type of Valve fitted. — Slide valve or piston valve with steam over 
 ends. 
 
 Position of Eccentric. — With the crank. 
 
 Action. — The action of the swing link 2 is as before described for 
 Marshall's gear, but it should be noticed that the angle of the link 
 is reversed in this case, position i being for "ahead" and ;2 for 
 "astern." The distance between the swinging link pin on the 
 eccentric rod and the valve link allows for the required lead, and it 
 should be noted that the end of the eccentric rod and valve link 
 describe an irregular ellipse when in motion, the long sides of which 
 incline to the vertical and produce the quick travel of valve at the 
 cut-off positions. 
 
 It may also be stated that with equal steam lap top and bottom 
 the cut-off and release can be arranged to take place earlier on the 
 down stroke than on the up stroke, this result being obtained by the 
 
:^i 
 
 'V:\ 
 
 # 
 
No. 34— Morton Valve Gear. 
 
 1, Link suspended froin crosshead. 
 
 2, Lever connecting to quadrant rod 5 through small 
 
 lever 3. 
 
 3, Compensating lever. 
 
 8. Reversing eng^e rod 
 
 4, Suspension links from guide bracket. 
 
 5, Quadrant rod. 
 
 6, Crosshead of valve spindle, solid with quadrant 
 
 7, Wyper shaft. 
 
 \To face page 225. 
 
•-4 
 
 icket 
 
 . with quadrant 
 
 ( To face page 225. 
 
No- 35 — Joy Valve Gear. 
 
 1, Suspended link. 
 
 2, Compensating link. 
 
 3, Lever connecting- compensating link 
 
 and valve rod through quadrant 
 block 4. 
 
 4, Quadrant block (travelling). 
 
 5, Angle of quadrant for "ahead." 
 
 6, Angle of quadrant for "astern." 
 
 7, Slide valve spindle. 
 
 8, Reversing engine rod. 
 
 [ To face page 22 %. 
 
 " Verbal " Notes and Sketches. 
 
Slide Valves, Piston Valves, Valve Data, &c. 225 
 
 length given to the swinging link, the oscillations of which produce 
 the difference in cut-off mentioned. It should also be noted that the 
 lead remains constant for all grades of expansion. 
 
 Morton Valve Gear (Sketch No. 34). 
 
 This valve gear consists of a series of levers and links, connected 
 to a vertically moving quadrant which is in one with the valve spindle, 
 no eccentric being required, as the valve motion is obtained from the 
 connecting rod. 
 
 Type of Valve fitted. — Slide valve or piston valve with steam 
 over ends. 
 
 Action. — The valve lever 2 is suspended from the crosshead by the 
 link I, from the connecting rod by the pivoted arm 3, and from the 
 guide bracket by the heavy links 4, at a point near the outer end, 
 the end of the lever being connected direct to the valve link 5, which 
 gives vertical motion to the quadrant and thus to the valve : the small 
 compensating arm 3 corrects the unequal effect of the connecting rod. 
 Notice that the centres of the suspension link 4 are not in line with 
 the valve spindle, and when the crank is centred the links 4 are 
 parallel to the centre line of the engine, and in this position the valve 
 link 5 may be moved over the quadrant from one side to the other 
 without moving the valve. When linked up, the lead remains the 
 same as in full gear, and equal steam lap gives equal cut-off top and 
 bottom. 
 
 >oy Valve Gear (Sketch No. 35). 
 
 This gear is similar to Morton's in the fact that links and a 
 quadrant take the place of eccentrics, the connecting rod supplying 
 the necessary motion to the valve. 
 
 Type of Valve fitted. — Slide valve or piston valve with steam 
 over ends. 
 
 Action. — The suspended link i on the column connects to a vibrating 
 link 2 on the connecting rod, and the valve lever 3 is fixed to a pin 
 on this link at an intermediate position. Near the other end of the 
 valve lever is a fulcrum point which slides back and forward on the 
 quadrant bar by means of a block 4, the actual end of the lever being 
 connected direct to the valve link and spindle 7. The angle given 
 to the quadrant by the reversing engine 8 determines the direction of 
 rotation, 5 being for "ahead" and 6 for "astern," the block 4 sliding 
 back and forward in the dotted arc shown. 
 
 When the quadrant is in a horizontal position (as shown in Sketch 
 No. 35) the gear is in the neutral position. It should be noted that 
 
226 
 
 ** Verbal " Notes and Sketches 
 
 the quadrant bar is hinged at the centre to a supporting bracket 
 bearing on the left column. 
 
 The leverage given by the distance from the fulcrum point on the 
 lever to the end allows for the " steam lap + lead " trAvel of the 
 valve, while the to-and-fro travel of the block 4 on the quadrant 
 bar allows for the additional port opening travel required. 
 
 Hackworth Gear (Single Eccentric) (Sketch No. 36). 
 
 This gear works on the same principle as the Bremme-Marshall 
 Gears, but instead of the swinging link an inclined bar is employed, 
 on which a bearing block connected to the end of the eccentric rod 
 slides up and down with the motion of the pulley. 
 
 Type of Valve fitted. 
 
 over ends. 
 
 -Slide valve or piston valve with steam 
 
 Position of Eccentric. — At 90° leading the crank. 
 
 Action. — The bracket i supports the pair of slide bars 2 by a pin and 
 brass as shown, and the angle given to the slide bar by the reversing 
 engine rod 9 determines the position of the gear whether "ahead " or 
 " astern." The motion of the eccentric rod is carried to the valve 
 link 7 through the bell crank 6 by means of the double link 5 con- 
 nected to the eccentric rod by a large pin joint ; adjustable slippers 
 3 are fitted to the end of the eccentric, and the dotted lines show the 
 angle of the bars for ahead or astern running. 
 
 In the Sketch the gear is shown in mid position, the valve travel 
 being then equal to the steam lap + lead for either end, the side 
 way slide motion of the eccentric rod in the bars allowing for the 
 additional port opening required. The slide bars angle is changed by 
 means of the usual drag link 8 from the reversing engine, and an 
 expansion slot of the usual type is fitted for working " linked-up." 
 
 No. 37.— Eccentric Rod at Limit of upper travel on Slide Bar. 
 
No. 36 Hackworth Valve Gear. 
 
 6, Valve bell crank working on 
 fixed bearing. 
 
 7, Valve link. 
 
 8, Drag link. 
 
 9, Reversing engine rod. 
 
 1, Supporting bracket for slide bars. 
 
 2, Slide bars for slippers 3. 
 
 3, Slippers on end of eccentric rod. 
 1. Eccentric rod. 
 '. Links connecting eccntric lod and 
 
 valve bell crank 
 
 [ To fate pagi 226. 
 
No. 37.— Eccentric Rod at Limit of upper travel on Slide Bar. 
 
1, Eccentric rod. 
 
 2, Rocking quadrant 
 
 3, Valve link. * 
 
 4, Lever connected at one end to valve link, and 
 
 at the other end to ciosshead link 7, also 
 connected to the valve spindle near the end. 
 
 No. 38.~Brock Valve Gear. 
 
 5, * ' Ahead " position of valve link. 
 
 6, " Astern " position of valve link. 
 
 7, Crosshead link 
 
 8, Crosshead slioper. 
 
 9, Valve spindle. 
 
 10, Drag link. 
 
 11, Reversing engine rod. 
 
 12, Guide on column. 
 
 [7-^>-./-V^227. 
 
flaamjYO 
 
fe27. 
 
 No. 37.— Eccentric Rod at Limit of upper travel o 
 
 
'/laaHijvo 
 
No. 39— Bryce-Douglas Valve Gear. 
 
 1, Link suspended from crosshead. 4, Quadrant rod. 
 
 2, Lever connecting crosshead with valve rod 5 5, Valve rod. 
 
 through a fulcrum on bell crank 3. 6, "Ahead" position of quadrant 
 
 3, Bell crank working on fixed bearing. 7, "Astern" position of quadrant. 
 
 8, Reversing engine rod. 
 
• 
 
 Slide Valves, Piston Valves, Valve Data, &c. 227 
 
 The .small Sketch, No. 37, shows the gear in " ahead " position, with 
 the sHpper at the upper limit of its travel on the inclined bars. In 
 this gear the bearing of the bell crank (6) shaft is subject to the most 
 wear, and requires the most frequent overhaul, as the setting of the 
 valve is affected by wear down of this bearing. 
 
 Brock Gear (Single Eccentric) (Sketch No. 38). 
 
 In this gear a rocking quadrant actuated by the eccentric is 
 employed to convey the motion to the valv-e. 
 
 Type of Valve fitted. — Piston valve with steam inside. 
 
 Position of Eccentric. — Following the crank at an angle of 90" less 
 steam lap and lead. 
 
 NOTE. — As in the case of other single eccentric gears (such as Hackworth's 
 [and Bremme's) the travel of the pulley exceeds the actual travel of the valve, as 
 [the motion is reduced down from the extended end of the quadrant in the 
 [present case. 
 
 Action, — The eccentric rod i gives motion to the rocking quadrant 
 2, which is hinged on a bracket cast on the engine framing, and this 
 transmitted to the valve by means of the link 3 and travelling 
 ver 4. This lever is held at the other end to a bracket cast on the 
 rosshead, and travels to and fro with the piston rod stroke. The 
 valve spindle is connected to lever 4 at a point near the end, thus 
 giving a small leverage which allows for the " lap + lead " travel of the 
 valve, the remainder of the travel required to give port opening being 
 obtained by the rocking motion of the quadrant produced by the 
 eccentric 5 being the " ahead " position, and 6 the " astern " position 
 of the link, as shown by the dotted lines. The drag link 10, moved 
 by the reversing engine links 11, changes over the link block to the 
 "ahead" or "astern" position as required, and the gear can be linked 
 up by means of the expansion slot shown in the reversing bell crank. 
 In all positions of gear the lead remains constant, and is unaffected 
 by linking up. 
 
 NOTE. — The Sketch shows the gear as applied to a diagonal type paddle 
 engine, but if the reader turns the page round so that the gear assumes a vertical 
 position with the shaft below, the position of the gear as applied to an ordinary 
 triple expansion marine engine will be obtained, and can be studied. 
 
 Bryce-Douglas Gear (Single Eccentric) (Sketch No. 39). 
 
 In this gear a fixed quadrant and travelling block, actuated by a 
 single pulley, is employed, together with a link, lever, and bell crank. 
 
 Type of Valve fitted. — Slide valve or piston valve with steam 
 over ends. 
 
) K 1 
 
 rirr 
 
 Nc 
 
 iTo face page 227. 
 
Slide Valves, Piston Valves, Valve Data, &c. 227 
 
 The small Sketch, No. 37, shows tiic c^ear in " ahead " position, with 
 the sHjiper at the upper limit of its travel on the inclined bars. In 
 this gear the bearing of the bell crank (6) shaft is subject to the most 
 wear, and requires the most frequent overhaul, as the setting of the 
 valve is affected by wear down of this bearing. 
 
 Brock Gear (Single Eccentric) (Sketch No. 38). 
 
 In this gear a rocking quadrant actuated by the eccentric is 
 employed to convey the motion to the valve. 
 
 Type of Valve fitted. — Piston valve with steam inside. 
 
 Position of Eccentric. — Following the crank at an angle of 90" less 
 steam lap and lead. 
 
 NOTE. — As in the case of other single eccentric gears (such as Hackworth's 
 and Bremme's) the travel of the pulley exceeds the actual travel of the valve, as 
 the motion is reduced down from the extended end of the quadrant in the 
 present case. 
 
 Action. — The eccentric rod i gives motion to the rocking quadrant 
 2, which is hinged on a bracket cast on the engine framing, and this 
 'is transmitted to the valve by means of the link 3 and travelling 
 Hever 4. This lever is held at the other end to a bracket cast on the 
 'crosshead, and travels to and fro with the piston rod stroke. The 
 valve spindle is connected to lever 4 at a point neaj' the end, thus 
 giving a small leverage which allows for the " lap + lead" travel of the 
 valve, the remainder of the travel required to give port opening being 
 obtained by the rocking motion of the quadrant produced by the 
 eccentric 5 being the " ahead " position, and 6 the " astern " position 
 of the link, as shown by the dotted lines. The drag link 10, moved 
 by the reversing engine links 11, changes over the link block to the 
 "ahead" or "astern" position as required, and the gear can be linked 
 up by means of the expansion slot shown in the reversing bell crank. 
 In all positions of gear the lead remains constant, and is unaffected 
 by linking up. 
 
 NOTE.— The Sketch shows the gear as applied to a diagonal type paddle 
 engine, but if the reader turns the page round so that the gear assumes a vertical 
 position with the shaft below, the position of the gear as applied to an ordinary 
 triple expansion marine engine will be obtained, and can be studied. 
 
 Bryce- Douglas Gear (Single Eccentric) (Sketch No. 39). 
 
 In this gear a fixed quadrant and travelling block, actuated by a 
 single pulley, is employed, together with a link, lever, and bell crank. 
 
 Type of Valve fitted. — Slide valve or piston valve with steam 
 over ends. 
 
228 
 
 " Verbal " Notes and Sketches 
 
 Position of Eccentric. — At an angle of 90° plus lap and lead in 
 advance of the crank. 
 
 Action. — The eccentric rod block travels back and forward in the 
 slot of the quadrant, which is hinged on a bracket bearing as shown, 
 the angle given to the quadrant by the reversing engine 8 determining 
 the direction of rotation whether "ahead" or "astern," 6 being ahead 
 and 7 astern : from the quadrant the motion is carried to a fixed 
 
 SHAf 
 
 yALVfeTRAVEL 
 PULLBY CENTRE 
 
 No. 40. 
 
Slide Valves, Piston Valves, Valve Data, &c. 229 
 
 bell crank 3 by a link 4, the other arm of the bell crank finally 
 giving the motion to the valve link 5, through the lever 2, suspended 
 from the engine crosshcad by the small link i. Observe that the 
 lever 2 is fulcrummed near the end by a pin to the bell crank, and the 
 leverage to the valve spindle obtained in this way allows for the " steam 
 lap + lcad" travel of the valve, the additional travel necessary to give 
 the required port opening being obtained by the travel of the block of 
 link 4 in the quadrant ; the lead is therefore constant for all positions 
 of the gear, whether " full out " or " shut In." 
 
 As before stated, the quadrant is hinged by the centre, and is 
 canted over to the required ahead or astern angle by the drag link of 
 the reversing engine, and remains in that position, the block travelling 
 back and forward by the action of the eccentric. 
 
 Link Motion. — In the most modern types of reciprocating engines, 
 the " Stephenson " link motion gear is generally fitted, patent valve 
 gears having been not altogether satisfactory in many respects, 
 experience proving the superiority of the old type of gear. 
 
 Observe that the link radius is equal to the distance from the pin 
 centre B to the pulley centre, and the centre of curvature is found 
 by describing an arc from the pulley centre to the shaft centre line, 
 as shown by the small cross. 
 
 S = valve travel x 3. 
 
 T = throw or eccentricity. 
 
 E = steam lap plus lead. 
 
 No. 41. — Reversing Quadrant and Block. 
 
 NOTE.— Distance D should be equal to three times the valve travel. 
 
230 
 
 •• Verbal " Notes and Sketches 
 
 Linking Up. — Assuming pin A to be in line for " full gear," in 
 linking up, the pin B is moved over towards the valve spindle block 
 C, so that the effect is to reduce the valve travel. 
 
 The general results of linking up are as follows : — 
 
 (i) Travel reduced. 
 
 (2) Port opening reduced (producing wire-drawing of the steam). 
 
 (3) Cut-off sooner. 
 
 (4) Lead increased (with rods " open," crank on bottom). 
 
 (5) Compression increased. 
 
 Generally speaking, all points occur earlier. 
 
 NOTE. — With the gear in mid position as shown, if the engine is turned one 
 revolution with the turning gear, the valve will travel a distance equal to twice the 
 steam lap and lead. 
 
 Example. — To prove by a valve diagram that with equal laps on 
 the valve, top and bottom and ordinary link motion valve gear, the 
 steam is cut off sooner on the up stroke. 
 
 NOTE, 
 angle. 
 
 -This difference in cut-off is caused by the connecting rod and crank 
 I 
 
 I 
 
 ADMISSION 
 
 No. 42. 
 
 Referring to No. 42, set oft' top and bottom of the valve travel 
 circle, small circles equal in radius to the lead ; also from the centre 
 of the travel circle set off with the compasses the amount of steam 
 lap on the valve ; now draw tangents to both the lead circles and the 
 lap arcs, and the crank angles at " Admission " and " Cut-off" will be 
 obtained, 
 
Slide Valves, Piston Valves, Valve Data, &c. 231 
 
 Next, take with the compasses the lenj^th of the connecting rod 
 as radius, and putting the pencil on the crank position at "Cut-off," 
 and the needle on the centre hne, draw arcs inivards to the centre 
 Hne to obtain the distance the steam is carried on the down and up 
 strokes respectively. It will then be found, on measuring, that the 
 distance U is less than the distance D, that is, the cut-off occurs earlier 
 on the up stroke than on the down stroke, owing to the angle formed 
 by the connecting rod and the crank, 
 
 t NOTE.— For complete explanation of Valve Diagram, see page 248. 
 
 Eccentric Keyseat Templates. 
 
 Without Steam Lap and Lead. — If a valve has no steam lap 
 lead, as, for example, a stearing gear engine valve, the keyseat 
 position is at right angles, or 90' to the crank leading it (Sketch 
 No. 43). In this case the steam is carried the full length of stroke, 
 and, with the crank on the centre, the valve is exactly at mid position, 
 ready to open for steam. The valve travel will then be equal to 
 twice the port opening. 
 
 With Steam Lap and Lead. — When a slide valve has steam lap and 
 lead the sum of the uieaii steam lap and lead must be measured down 
 from the centre, and a horizontal line drawn through the travel circle, 
 then lines drawn out to the shaft circle through the points of inter- 
 section from the centre, will give the correct keyway positions ahead 
 and astern (Sketch No. 44). The valve travel circle diameter is 
 equal to tivice the steam lap and' steam port opening. The key- 
 seat position is therefore 90 , plus lap and lead, in advance of the 
 crank, as when the crank is centred the valve is lower than mid 
 position by a distance equal to the steam lap and lead. 
 
 Piston Valves. — For a piston valve of the inside steam type as 
 commonly constructed, the valve travel motion is reversed* from that 
 of a slide valve, as, instead of moving down to give lead and steam 
 to the top port the valve requires to move up. This necessitates the 
 position of the keyways being changed to scarcely the opposite side 
 of the shaft (Sketch No. 46), the position being therefore 90' behind 
 the crank less mean steam lap and lead. In setting off the keyseat 
 template the mean steam lap and lead have to be measured up from 
 the shaft centre. 
 
 To sum up, for a common slide valve or a double ported slide 
 valve the keyway is cut at an angle greater than 90" leading the 
 crank, but for a piston valve the keyway is cut at an angle less than 
 90" following the crank. 
 
 NOTE.— After the kejrways are cut and the pulley secured to the shaft, a liner 
 may require to be fitted under the rod if a slide valve, or a liner taken out if a piston 
 valve, to give more lead at bottom than top. 
 
232 
 
 " Verbal " Notes and Sketches 
 
 Eccentric Keyseats. 
 Crank on Top Centre. 
 
 LEVELLED 
 
 No. 43. — Valve without Steam Lap and Lead 
 (Steering Gear Engine Valve). 
 
 Keyseat at right angles to crank, if a slide valve leading the 
 crank, if a piston valve following the crank. 
 
Slide Valves, Piston Valves, Valve Data, &c. 233 
 
 Crank on Centre. 
 
 LEVELLED 
 
 Na 44.— Slide Valve with Steam Lap and Lead. 
 
 Shaft, 12 in. diameter. 
 
 Mean steam lap, 2 in. 
 
 Mean port opening, i| in. 
 
 Mean lead, | in. 
 
 Then, (2+ 1-5) x 2 = 7 in. valve travel. 
 
 And, B = steam lap + lead = 2 + | = 2^ in. 
 
234 
 
 "Verbal" Notes and Sketches 
 
 Crank on Centre. 
 
 \2 SHAFT 
 
 VALVE TRAVE 
 
 LEVELLED 
 
 No. 45.— Double Ported Slide Valve. 
 
 Shaft, 1 2 in. diameter. 
 
 Mean steam lap (each of two, top or bottom), 2 in. 
 
 Mean port opening „ „ „ i| in. 
 
 Mean lead, ^ in. 
 
 Then, (2 + i -5) x 2 = 7 in. valve travel. 
 
 And, B = steam lap + lead = 24-^==2| in. 
 
 NOTE.— Only one of the two top or bottom laps and port openings are taken, 
 and not the combined or total lap and port opening at either end. 
 
Slide Valves, Piston Valves, Valve Data, &c. 235 
 Crank on Centre. 
 
 LEVELLED 
 
 No. 46.- Inside Steam Piston Valve. 
 
 Shaft, 12 in. diameter. 
 
 Mean steam lap, 2 in. 
 
 Mean port opening, i| in. 
 
 Mean lead, | in. 
 
 Then, (2+ 1-5) x 2 = 7 in. valve travel. 
 
 And, B = steam lap + lead = 2 + ^ = 2^ in. 
 
 NOTE.— As the valve motion is reversed from that of a slide valve, the mean 
 steam lap and lead are measured up from the centre with crank on top. 
 
236 
 
 "Verbal" Notes and Sketches 
 
 LEAD 
 
 CUT-OFF 
 
 ^ 
 
 "^1 
 
 ^^^^'^^H 
 
 
 
 ; 
 
 ' 
 
 
 
 
 ' 
 
 
 EXHAUST OPENING 
 
 EXHAUST CLOSING 
 
 No. 47. — Slide Valve and Piston Positions. 
 
Slide Valves, Piston Valves, Valve Data, &c. 237 
 
 EXHAUST OPENING. 
 
 EXHAUST CLOSING. 
 
 No. 48— Piston Valve and Piston Positions. 
 
238 "Verbal" Notes and Sketches 
 
 Action of Steam in a Cylinder. 
 
 During one revolution the action of the steam on one side of the 
 piston is as follows : — With the crank on the top centre the top steam 
 port is open for the amount of lead ; the valve then moves down 
 and opens the port further, and the piston moves down to, say, half 
 stroke, when the valve moving up again cuts off the supply of steam. 
 The steam in the cylinder expands and forces the piston down towards 
 the end of the stroke, and when near the bottom centre the port opens 
 to the exhaust ; the piston then completes the stroke and travels 
 up again, and when near the top centre the port is closed to exhaust. 
 The steam thus retained in the cylinder is compressed by the return- 
 ing piston to an increased pressure, and cushioning is effected ; the 
 piston next reaches the top centre, and the port again opening for 
 lead, the same cycle of operations is repeated. 
 
 Notice that "exhaust opening" occurs when the piston is near 
 the end of one stroke, and " exhaust closing " when the piston is near 
 the end of the other stroke. 
 
 NOTE. — A piston valve travels in the reverse direction to that of a slide valve in 
 the above cycle of operations, as will be seen by comparing the sketches of each. 
 
 Observe that in " lead " and in " cut-off" the valve is in the same 
 position, but going down for " lead " and going up for " cut-off." 
 Also that for " exhaust opening " and " exhaust closing " the valve 
 is also in the same position, but going up for "exhaust opening" and 
 going down for " exhaust closing," Again notice that the piston 
 is near the bottom for " exhaust opening," and near (not at) the top 
 for " exhaust closing." 
 
 Observe that as steam is entering from between the pistons, the 
 valve requires to travel in the reverse direction to that of a slide valve 
 to give similar results. 
 
 In "lead" and in "cut-off" the valve is in the same position, but 
 is going np {ox "lead" and going dow7i for "cut-off" In "exhaust 
 opening" and in "exhaust closing" the valve is in the same position, 
 but is going dozvn for "exhaust opening" and ?//> for "exhaust 
 closing." 
 
 NOTE. — Between the positions of "Cut-off" and "Exhaust Opening" 
 ("Release") the steam in the cylinder expands in approximate accordance with 
 Boyle's Law of Expansion ; that is, the volume is increasing and the pressure 
 decreasing proportionally: between the positions "Exhaust Closing" ("Com- 
 pression") and " Lead" the steam is also following out this law but reversed in 
 action, as in this case the volume is decreasing and the pressure increasing 
 proportionally. 
 
cranK. 
 
 ern - - 8. 
 
 s To" 
 
 1 c 
 
 I^ 2; 
 
 i« "^ iV 24 J 
 
 23f 
 
 2|- 2^ 
 
 3i\ 
 
 7~y 
 61^ 
 
VALVE DATA. | 
 
 hove 1 - 8 
 
 Top 
 
 BoK 
 
 Ltad. 
 
 \ 
 
 s 
 
 Sheom Up. 
 
 Si 
 
 2l 
 
 PotI- Opening 
 
 li 
 
 ll 
 
 E.W lop. 
 
 +1 
 
 + 1 
 
 A Lei 
 
 B- Cut off. 
 
 No. 48a.— Valve and Piston Positions. 
 
 For one revolution, top side of piston. 
 (Angle of connecting rod and crank neglected ) 
 Release (exhaust opening). D. Compression lexha 
 
 The above diagram illusirales the comparative ])Ositions of piston and valve referred 
 to the valve diagram, cylinder stroke, and indicator card : the relative positions of crank 
 and ecrenlric are also shown throughout. Observe that the valve data tabic given 
 corresponds with the keyseat template, but it should be carefully noted, that after cutting 
 the keyseats and bolting on the pulleys a liner is required to go in under the foot of the 
 rod to give the required difference in steam laji and lead top and bottom, in this case a 
 
 er ,V in. thick, or equal in thickness to half the lead difference, as ** ' = ,'„ in. liner 
 
 |uired. Ky "admission" is mciint the position of the crank when steam liegins to enter 
 
 the cylinder, " lead ' beini; the ai 
 dead centre, in the present cast- j 
 Tlie following points should 1 
 I. Top Steam Lap 1 Lead 
 
 E, Adir 
 
 rlually opt 
 
 lount the | 
 11. Notice where this shuws .m 
 c caicfully noted. 
 - Bottom Steaui Lap . Lead. 
 
 2. .. „ t-Port opening- 
 
 lierefore Top 24 1 1=2}. Also, Top 
 
 •Bot, 2,' h'^ = 2.J. ,, Bot 2;; ( i;i-4 ,, 
 
 NOTE, -The reader is advised to study carefully the 
 . shown above. 
 
 I Pott opeiiii 
 .1=4 in. (half travel). 
 
 ihe crank is."/ ihe 
 valve dingmi.i. 
 
 r^half valve travel. 
 
 i positions of valve and piston 
 
 NOTE. — For detailed description of valve diagram construction sec page 248. 
 
 /•<) Ar.r /vyv ajli. 
 
jk Slide Valves, Piston Valves, Valve Data, Sec. 239 
 
 Valve Setting Tables. 
 
 The following- table.s of valve settings, showing lead, steam lap, 
 exhaust lap, cut-off, Sic, for both up and down strokes, are from a set 
 of engines of a modern fast passenger steamer, and should be care- 
 fully studied. The differences in lead, steam lap, port opening, cut- 
 off, &c., occurring on the up and down strokes, and chiefl}^ due to 
 the effect of the angle of the connecting rod and crank, when link 
 motion is fitted, are of great importance to the student, and the 
 writer strongly advises special attention to this subject, as being one 
 of particular interest and benefit to the marine engineer. 
 
 No. I — Type; — Fast Passenger Steamer. — I. H. P., 4500; Speed, 21 
 knots ; Cylinders, 27, 44, 70 inches ; Stroke, 2 feet 9 inches ; 
 Boiler pressure, 185 lbs.; Revolutions, iSo; H.P. cylinder 
 M.E.P. = 65 lbs. ; LP. cylinder M.E.P. - 32-2 lbs. ; L.P. 
 cylinder M.E.P. = 16 lbs. ; Link motion valve gear. 
 
 H.P. Piston Valve. 
 
 I'xpansion 
 Grade. 
 
 > 
 
 Lead. Steatr 
 
 Lap. 
 
 Port 
 Opening. 
 
 Exhaust 
 Lap. 
 
 Cut-off. 
 
 Exhaust 
 
 Opening 
 
 (from end 
 
 of stroke). 
 
 Exhaust 
 
 Closing 
 
 (from end 
 
 of stroke). 
 
 Top 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 i 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 5 (full out) 
 
 8 
 
 •5 
 
 iV 
 
 T 1 -^ 
 
 if 
 
 2J% 
 
 2i 
 
 :5 
 
 1 (5 
 
 -1- 5 
 
 + T6 
 
 26J 
 
 23^2 
 
 4 
 
 2i 
 
 ^16 
 
 2A 
 
 S (shut in) 
 
 6| 
 
 1 1 
 
 2 1 
 
 a 2 
 
 
 If 
 
 lA 
 
 •1 
 
 •■5 
 
 ~1Z 
 
 -4- S 
 + 1B- 
 
 2li 
 
 i6tV 
 
 Sie" 
 
 5f 6^ 
 
 6 
 
 5h 
 
 Uern - - 
 
 8tV 
 
 1 a 
 
 1 1 
 
 ill 
 * lb 
 
 If 
 
 4 
 
 41 
 
 10 
 
 + T0 
 
 27i 
 
 2 2| 
 
 2i 
 
 2| 
 
 3 
 
 2i ir 
 
 
 
 I.P. Piston Valve. 
 
 
 
 ) (full) - 
 
 8 
 
 :5 
 
 8 
 
 TB 
 
 2 
 
 ^n 
 
 2 
 
 2tV 
 
 :} 
 16 
 
 + tV 
 
 24|; 2i| 
 
 2;^ 
 
 2| 
 
 3L- 
 
 3.^ 
 
 5 (shut in) 
 
 6i 
 
 1 1 
 
 •2.1 
 32 
 
 2 
 
 41 
 
 ItV 
 
 I '2 
 
 .3 
 10 
 
 + T0 
 
 i9i 
 
 i5t 
 
 5f 
 
 5^ 
 
 61 
 
 6^^ 
 
 tern - - 
 
 8A 
 
 •■5 
 
 8 
 
 7 
 
 2 
 
 41 
 
 4 
 
 2? 
 
 3 
 ~ Iff 
 
 + tV 
 
 24I 
 
 23I 
 
 2| 
 
 2h 
 
 3t6 
 
 Stbt 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
F 
 
 F 
 
 a 
 
 s 
 
 1 
 
 t 
 
 t 
 
 u- 
 
 1 
 
 fi 
 
 P 
 
 k 
 
 tl 
 tl 
 
 th 
 
 P' 
 A 
 is 
 
 g< 
 is 
 fo 
 
 va 
 to 
 
 IS 
 
 op 
 bu 
 
 Cl( 
 
 (" 
 Bo 
 det 
 pre 
 act 
 pro 
 
Slide Valves, Piston Valves, Valve Data, S:c. 239 
 
 Valve Setting Tables 
 
 
 
 
 
 
 
 
 
 
 
 
 The following- tables of valve settings, showing lead, steam lap, 
 
 exhaust lap, cut-off, &c., for both up and down strokes, are from a set 
 
 of engines of a modern fast passenger steamer, and should be care- 
 
 fully studied. The differences in lead, steam lap, port opening, cut- 
 
 off, &c., occurring on the up and down strokes, and chiefly due to 
 
 the effect of the angle of the connecting rod and crank, when link 
 
 motion is fitted, are of great importance to the student, and the 
 
 writer strongly advises special attention to this subject, as being one 
 
 of particular interest and benefit to the marine engineer. 
 
 No. I— Type; — Fast Passenger Steamer.— I. H. P., 4500 ; Speed, 21 
 
 ^ knots ; Cylinders, 27, 44, 70 inches ; Stroke, 2 feet Q inches ; 
 
 B Boiler pressure, 185 lbs.; Revolutions, 180; H.P. cvlinder 
 
 ■ M.E.P. = 65 lbs. ; I. P. cylinder M.E.P. - 32-2 lbs. ; L.P. 
 
 H cylinder M.E.P. = 16 lbs. ; Link motion valve gear. 
 
 H.P. Piston Valve. 
 
 Expansion 
 Grade. 
 
 
 Lead. 
 
 Steam Lap. 
 
 Port 
 Opening. 
 
 Exhaust 
 Lap. 
 
 Cut-off. 
 
 Exhaust 
 
 Opening 
 
 (from end 
 
 of stroke). 
 
 Exhaust 
 
 Closing 
 
 (from end 
 
 of stroke). 
 
 Top 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 5 (full out) 
 
 8 
 
 ••5 
 
 tV 
 
 ,1 .-! 
 
 li 
 
 2i'. 
 
 H 
 
 :5 
 16 
 
 -1- 5 
 
 + T8 
 
 26J 
 
 23i 
 
 4 
 
 4 
 
 2r6 
 
 -A 
 
 3 (shut in) 
 
 6| 
 
 1 1 
 T6 
 
 21 
 
 ,1.3 
 
 if 
 
 lA 
 
 4 
 
 ~1^ 
 
 4- 5 
 + 16 
 
 2l| 
 
 16^^ 
 
 St6 
 
 1 t; 
 
 6 
 
 5i 
 
 item - - 
 
 8tV 
 
 13 
 
 5? 
 
 11 
 
 :i-2 
 
 ^Ib 
 
 If 
 
 2i 
 
 III 
 
 3 
 IB 
 
 + T6 
 
 27I 
 
 22f 
 
 4 
 
 2| 
 
 3 
 
 -iV 
 
 LP. Piston Valve. 
 
 . (full) - 
 
 8 
 
 8 
 
 TB 
 
 2 
 
 lil 
 
 2 
 
 2A 
 
 .•5 
 
 16 
 
 + t\ 
 
 24I 2l| 
 
 2 1 
 
 2l 
 
 3i 
 
 3^ 
 
 ; (shut in) 
 
 ^k 
 
 11 
 
 2 5 
 72 
 
 2 
 
 iH 
 
 ItV 
 
 i'^ 
 
 3 
 
 16 
 
 + A 
 
 i9i 
 
 I5I 
 
 5l 
 
 5f 
 
 61 
 
 6| 
 
 tern - - 
 
 8tV 
 
 » 
 
 7 
 
 2 
 
 41 
 
 4 
 
 H 
 
 3 
 "16 
 
 + tV 
 
 24I 
 
 23I 
 
 -1 
 
 4 
 
 3t6 
 
 3tV 
 

 
 
 
 
 
 
 
 
 
 
 
 
 • 
 
 • 
 
 \ 
 
 240 
 
 " Verbal " Notes and Sketches 
 
 , 1 
 
 
 L.P. Double Ported Slide Valve. 
 
 i 1 
 
 i 
 
 
 
 
 
 
 
 
 Exhaust 
 
 Exhau 
 
 Expansion 
 Clrade. 
 
 jj 
 
 Lead. 
 
 Steam 
 Lap. 
 
 Port 
 Opening. 
 
 Exhaust 
 Lap. 
 
 Cut-off. 
 
 Opening 
 (from end 
 
 Closin 
 (from el 
 
 0) 
 
 
 
 
 
 
 of stroke). 
 
 of strok , 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 > 
 
 Top 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot, 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Hot. 
 
 Top. 
 
 Bot. 
 
 Top. B, 
 
 1 1 
 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 I: 
 
 •60 (full) - 
 
 8 
 
 Ttf 
 
 h 
 
 2A 
 
 2I 
 
 lU 
 
 If 
 
 -h 
 
 + i 
 
 2lf 
 
 i8i 
 
 4f 
 
 5l 
 
 l\ 
 
 3;' 
 
 •44 (shut in) 
 
 7i 
 
 1 1 
 
 To 
 
 1 p. 
 
 T6 
 
 2tV 
 
 -i 
 
 li 
 
 l| 
 
 -\ 
 
 + i 
 
 i5t6 
 
 14 
 
 8| 
 
 8| 
 
 •7 5 
 
 7t^ 
 
 6ij 
 
 Astern - - 
 
 7lf 
 
 tV 
 
 i 
 
 ^A 
 
 -i 
 
 T* 
 
 4 
 
 -\ 
 
 + 1 
 
 21 A 
 
 i9t« 
 
 4i 
 
 4f 
 
 "hTE 
 
 4 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Piston Clearances. 
 
 
 Top. 
 
 Bot. 
 
 H.P. - . - - 
 LP. - - - - 
 LP. - - - 
 
 In. 
 
 8 
 
 1 
 4 
 
 1 :3 
 
 In. 
 
 1 
 
 3 
 4 
 
 Referring to the foregoing tables, the following points should be 
 carefully noted : — 
 
 I. Half valve travel = Steam Lap + Port Opening. 
 
 Example i. — H.P. valve at -75 cut-off grade, valve travel = 
 8 inches. 
 
 Then, 
 
 / Steam lap —'^\% iiiches 
 Top ) ^"""^ opening = 2 ,=V » 
 
 4 inches = half valve travel, 
 
 / Steam lap = if inches 
 and, Bottom ) ^^^^ openings a^^^^ 
 
 4 inches = half valve travel. 
 
Slide Valves, Piston Valves, Valve Data, &c. 241 
 
 Example 2. — H.P. valve at -58 cut-off grade, valve travel = 
 inches. 
 
 len, Top 
 
 Steam lap = i|f inches 
 Port opening = I -j",v „ 
 
 3f inches = half valve travel. 
 
 /Steam lap = i| inches 
 id, Bottom < P°^' openings, I- ,. 
 
 V. 3 1 inches - half valve travel. 
 
 i'his holds goods in nearly all cases, the exceptions being those due to 
 eccentric rod angles at linked up positions, which result in a very- 
 small difference in the sum of the steam lap and port opening as 
 compared with half the valve travel. 
 
 2. In "gear full out" positions, the difference of the lead top and 
 bottom is just equal to the difference in the steam lap top and bottom, 
 or in other words, what is lost in steam lap is gained in lead, or the 
 reverse. 
 
 Example i. — H.P. valve at 75 cut-off grade. 
 /Steam lap= lyf inches 
 
 Top.^^^^^ =_f '^ 
 
 V 2y\ inches, 
 
 /Steam lap= i| inches 
 
 Bottom -| ^^""^ ^11 ::_ 
 
 \ ■ 2ys inches. 
 
 Therefore the sum of the top steam lap and lead is equal to the sum 
 of the bottom steam lap and lead. 
 
 NOTE. — This necessary difference in lap and lead is obtained by means of liner 
 adjustment under the valve rod, liners having to go in if a slide valve, but to come 
 out if for a piston valve with ins'de steam. 
 
 3. With the link shut in, the following effects are produced : — 
 
 A. Reduced valve travel (with open rods, crank on bottom). 
 
 B. Reduced port opening (exactly equal to difference in valve 
 
 travel). 
 
 C. Increased lead. 
 
 D. Earlier cut-off, exhaust opening (" Release "), and exhaust 
 closing (" Compression "). 
 
 NOTE— The steam lap and exhaust lap remain constant throughout as shown 
 in the tables, as these are part of the valve dimensions, and are therefore unaffected 
 
242 " Verbal " Notes and Sketches 
 
 by link alteration. The amount of steam or exhaust lap can only be varied by 
 either pinning on a brass strip to give an increase, or by chipping off a piece of the 
 valve to give a decrease. By linking up all points occur sooner, and the port 
 opening is decreased in proportion to the decrease in valve travel. 
 
 E. Owing to the angle of the connecting rod and crank, when h'nk 
 motion is fitted, the cut-off on the up stroke (bottom) is invariably 
 sooner than on the down stroke, and this cannot be avoided, although 
 the reverse order of things would be much more suitable if it could be 
 arranged for. Although the valve is lined up as far as possible to 
 give less steam lap, and therefore more port opening on the bottom 
 than the top, even this fails to equalise the cut-off, as reference to the 
 tables of valve settings reproduced will show. 
 
 F. In astern gear the link is often designed to give an increased 
 valve travel, and consequently port opening, to allow of rapid 
 reversing of the engines, and it should be observed that the gear 
 cannot be " shut in " in this position as the expansion slot in the 
 reversing bell crank is generally arranged so as to He in a liorizontnl 
 position when in "ahead" gear and in a vertical position for "astern " 
 gear (see page 43), thus making the position of the block in the slot 
 non-effective as regards linking up when vertical. 
 
 G. The exhaust lap on the top of each valve is negative, and thac 
 0.1 die bottom positive, much more compression being required on 
 the bottom than on the top, but as this difference of exhaust lap 
 is neutralised by the angle of the connecting rod, the actual position 
 of exhaust opening and closing is not much different for either the up 
 or the clown stroke, and is often at the wrong end (see table). 
 
 " Extra " Gear. — Occasionally the link radius bar is extended, so 
 that a small additional travel can, if desired, be given to the valve, 
 known as extra gear, which gives a still later cut-off than full gear by 
 the port opening being thus increased. In the "extra gear" position 
 of the link the lead is slightly decreased, the travel of valve increased, 
 and the port opening increased, with a correspondingly later cut-off, 
 say from -60 at " full gear" to -67 at " extra gear." The extra gear is 
 generally brought into action for a special spurt on trial trip runs, 
 but of course can be used at any time if it is required to increase the 
 power and speed. 
 
 In engines of well-balanced power the cut-off is generally latest 
 in the H.P., earlier in the LP., and earliest of all in the L.P. cylinder. 
 
 No. 2 — Type; — Cargo Steamer. — Speed, 11-2 knots; I.H.P., 2360; 
 Cjdinders, 27, 46, yd inches ; Stroke, 48 inches ; Receiver 
 pressures, H.P., 180 lbs., LP., 55 lbs., L.P., 16 lbs.; Vacuum, 
 27 inches ; Revolutions, 6^. 
 
Slide Valves, Piston Valves, Valve Data, &c. 24^ 
 Valve Settings. 
 
 
 
 H.P. Piston Valve. 
 
 
 
 
 
 Expansion Grade 
 
 (mean of lop and 
 
 botloni). 
 
 ^•alvc 
 Travel. 
 
 Lead. Steam Lap. 
 
 I'orl Openinj;. 
 
 1 
 
 Ciu-olT. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Hot. 
 
 Top. 
 
 Bo(. 
 
 Top. 
 
 ]5ot. 
 
 •72 (full gear) - 
 ■50 (shut in) - 
 
 In. In. 
 
 58 ' Sli 
 
 i 
 
 In. 
 .■J 
 
 8 
 
 '.) 
 IB' 
 
 In. 
 
 In. 
 
 In. 
 , 1 
 
 In. 
 
 2 
 
 In. 
 
 35i 
 25I 
 
 In. 
 2 2lV 
 
 LP. Double Ported Slide Valve. 
 
 ■65 (full gear) - 
 •44 (shut in) - 
 
 6 
 
 4| 
 
 .•J 
 
 8 
 1 
 
 8l- 
 h 
 
 4 
 4 
 
 4 
 4 
 
 if 
 
 1 3 
 16 
 
 4 
 
 1 
 
 16^ 
 
 33i 
 
 23i 
 
 29 1 
 
 L.P. Double Ported Slide Valve. 
 
 •53 (full gear) - 
 •31 (shut in) - 
 
 8 
 6| 
 
 1 
 
 2 
 
 tV 
 
 8 
 
 4 
 4 
 
 2/0- 
 
 2t6F 
 
 I* 
 
 15 
 16 
 
 T '-' 
 
 I 16 
 
 28^ 
 
 22| 
 I2| 
 
 NOTE.— The small letter B signifies "bare" and the letter F "full." 
 
 Observe that /la// thQ valve travel is equal to steam lap and port 
 opening, and that if the travel is decreased by shutting in the link 
 the port opening (not the steam lap) is decreased in exact proportion. 
 Also notice that at all grades of expansion the up stroke cut-off is 
 sooner than the down stroke, the cause as previously explained being 
 the angle of the connecting rod and crank when link motion valve 
 gear is fitted. 
 
 " Linked-up" Effects. 
 
 1. Valve travel reduced. 
 
 2. Lead increased. 
 
 3. Steam lap unaltered. 
 
 4. Port opening reduced. 
 
 5. Cut-off, exhaust opening, and exhaust closing all occur 
 
 earlier on the stroke. 
 
 If H.P. link is the one shut in then less steam is admitted to the 
 engine as a whole, which means less revolutions, I.H.P., and speed. 
 If the LP. or L.P. links are shut in, no appreciable difference in total 
 power results, but the pressures in the I. P. or L.P. receivers are varied, 
 which produces a change in the distribution of the power developed in 
 
244 
 
 "Verbal" Notes and Sketches 
 
 each cylinder of the engine, the adjustment of which depends greatly 
 on the setting of the links of each valve. 
 
 No. 3 — Type ; — Cargo Steamer. — Cylinders, 27, 43, 72 inches ; Stroke 
 51 inches; Boiler pressure, 180 lbs.; I.H.P., 2550; Link 
 motion gear. 
 
 Valve Settings. 
 
 H.P. Piston Valve. 
 
 Expansion 
 
 Grade 
 (mean of 
 top and 
 bottom). 
 
 11 
 > 
 
 ri 
 
 H 
 
 Lead. 
 
 Steam Lap. 
 
 Port 
 Opening. 
 
 Cut-off. 
 
 Exhaust 
 Lap. 
 
 Com- 
 pression 
 (from end). 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. Bot. 
 
 •62 
 
 In. 
 7 
 
 In. 
 
 In. 
 
 ••} 
 
 8 
 
 In. 
 2tV 
 
 In. In. 
 
 I 1 5 T '■ 
 
 In. 
 
 T « 
 
 In. 
 
 33i- 
 
 In. 
 
 In. 
 
 1 
 
 In. 
 
 •J 5 
 112 
 
 In. In. 
 
 8 8i 
 
 LP. Double Ported Valve. 
 
 
 •66 
 
 7 
 
 .•! 
 
 1 
 
 H 
 
 If 
 
 If 
 
 If 
 
 35-1 
 
 34 
 
 8 
 
 4 
 
 10 
 
 loi 
 
 L.P. Double Ported Valve. 
 
 •66 
 
 7 
 
 h 
 
 5 . 1 •; ! , 1 1 ,11 
 8 ^TTV ^T^ ^Te 
 
 ! 
 
 Itf 354 
 
 3t^ 
 
 tV 
 
 liV 
 
 io| 
 
 1 1 
 
 Example i. — Referring to the foregoing: — 
 
 Half travel --7-^2=; 3^5- Steam lap-fport opening. 
 H.P. valve, top steam lap —2^\ inches. 
 „ ,, port openings I tV 
 
 Then, 2yV + iTiT = 3j inches half travel. 
 
 L.P. valve, bottom steam lap ^ly^ inches. 
 
 Then, 
 
 port openmg — 1|| 
 m + ^H-Sh inches half travel. 
 
 Example 2. — 
 Rule— 
 
 Then, 
 Again, 
 
 Then, 
 
 Top steam lap + lead = Bottom steam lap + lead. 
 
 H.P. valve, top steam lap = 2iV inches. 
 
 ,, ,, lead — I inch. 
 
 2f'n + .i-~2i'*,T inches. 
 
 H.P. valve, bottom steam lap=;i^§ inches. 
 
 „ ,, lead : 
 
 ii:l + 1=2/5 inches. 
 
 Hi 
 
Slide Valves, Piston Valves, Valve Data, &c. 245 
 
 I 
 
 Example 3. — 
 
 Then, 
 
 Then, 
 Again, 
 
 Then, 
 
 L. P. valve, top steam lap =iH inches. 
 „ „ port opening = ifi 
 
 irc + ii5-3^ inches half travel. 
 
 L. P. valve, top steam lap = i } ;■ inches. 
 ,, ,, lead = i inch. 
 
 iH + i^Zr'c inches. 
 
 L. P. valve, bottom steam lap = i\h inches. 
 ,, ,, lead — s inch. 
 
 ifi + 5 = 2/s inches. 
 
 Again observe that in each cylinder the cut-off takes place earlier 
 on the up stroke. 
 
 No. 4 — Type ; — Fast Cargo Steamer. — I.H.P., 2200 ; Cylinders, 
 26, 44, 70 inches ; Stroke, 48 inches. 
 
 Valve Settings. 
 
 H.P. Piston Valve. 
 
 Expansion 
 
 Grade 
 (mean of 
 top and 
 bottom). 
 
 
 > 
 
 > 
 
 Lead. 
 
 Steam Lap. 
 
 Port Opening. 
 
 Exhaust 
 Lap. 
 
 Exhaust 
 Opening. 
 
 Exhaust 
 Closing. 
 
 Top 
 
 Bot. 
 
 Top 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 i 
 •66 ■ 
 
 In. 
 
 6f 
 
 In. In. 
 
 3 ' .-, 
 le 1 15^ 
 
 1 
 
 In. 
 
 In. 
 1 1 •" 
 
 In. 
 
 In. 
 
 In. 
 
 In. 
 
 4- " 
 
 In. 
 
 In. 
 02 
 
 In. 
 
 6| 
 
 In. 
 6 
 
 LP. Double Ported Slide Valve. 
 
 •66 
 
 7 fV 
 
 tv 
 
 3 
 
 IM 
 
 T « 
 
 1 
 ! 
 
 + U 
 
 4f 
 
 4 
 
 5f 
 
 4f 
 
 
 L.P. Double Ported Slide Valve. 
 
 
 •66 
 
 7 
 
 .3 
 
 \r 
 
 2 
 
 t1 '■'' 
 
 ^10 
 
 irVf ijB 
 
 
 
 + 1 
 
 l\ 
 
 3f 
 
 6 
 
 5? 
 
 NOTE.— In the above example the sum of the steam lap and port opening shows 
 a slight difference from half the valve travel in the case of the I. P. and L.P. valves, 
 this being accounted for by the angle and crossing over action of the eccentric rods. 
 
 The mean cut-off in each cylinder =33 inches. 
 
 Therefore, 32 inches -r 48 = -66 Expansion Grade. 
 
246 
 
 " Verbal " Notes and Sketches 
 
 No. 5 — Type ; — Large Cargo Passenger Steamer. — Speed, 14 knots ; I.H.P, 
 6000; Quadruple expansion cylinders, 3U, 45, 64, 92 inches; Stroke, 
 60 inches ; Boiler pressure, 200 lbs. 
 
 VALVE SETTINGS. 
 H.P. Piston Valve (20 inches diameter). 
 
 Expansio n 
 
 Grade 
 (mean of 
 lop and 
 bottom). 
 
 Full gear 
 Shut in - 
 
 
 
 
 Lead. 
 
 H 
 
 
 1; 
 
 
 
 Top 
 
 Bot. 
 
 In. 
 
 In. 
 
 In. 
 
 9h 
 
 1 
 
 8 
 
 1 
 
 7|| 
 
 11 
 U2^ 
 
 7 
 
 T6 
 
 Steam Lap. 
 
 Top. 
 
 In. 
 
 ^ 1 « 
 
 Bot. 
 
 In. 
 
 Port 
 Opening. 
 
 Top. 
 
 In. 
 
 T 5 
 
 Bot. 
 
 In. 
 
 Cut-off. 
 
 Top. 
 
 In. 
 
 Bot. 
 
 In. 
 
 25-1 
 
 E.xhaust 
 
 Lap. 
 
 Top 
 
 Bot. 
 
 In. 
 
 In. 
 
 1 
 
 8 
 
 1 r. 
 
 16 
 
 1 
 
 8 
 
 1 n 
 16 
 
 Release. 
 
 Top. 
 
 Bot. 
 
 In. 
 
 7 
 
 Com- 
 pres.sion. 
 
 Top Bot. 
 In. I In. 
 
 7! 7l 
 14I14 
 
 Pistod 
 
 ClearJ 
 ance. 
 
 Top 
 
 In. 
 
 1st LP. Martin and Andrews' Patent Valve (seepage 207). 
 
 Full gear iio| 
 Shut in - 8t% 
 
 2ff 
 
 43 
 24? 
 
 38I 
 26J 
 
 ■J 2 5 4 
 JL III 
 
 32 I ^^8 
 
 Si 
 
 10^ 
 
 6 6| 
 
 II^Il2j 
 
 2nd IP. Martin and Andrews' Valve. 
 
 Full gear 
 Shut in - 
 
 105 
 8i 
 
 2| 
 2| 
 
 ,13 
 2^2 
 
 2i- 
 
 44t 
 
 3II 
 
 40 
 
 Sf 
 
 54j IB" 
 IOf T6 
 
 Shut in - 
 
 
 
 
 L.P. Double Ported Slide Valve. 
 
 
 
 
 
 
 9h 
 
 fV 
 
 1 
 
 2^^ 
 
 ^16 
 
 2j 
 
 H 
 
 2H 
 
 39i 
 
 35t 
 
 tV 
 
 2 9 
 
 4f 
 
 5^ 
 
 1 4 
 
 9i 
 
 .5 
 
 TF 
 
 1 3 
 TV 
 
 7U 
 
 17 
 
 13 
 16 
 
 ,13 
 
 2i 
 
 ^A 
 
 lA 
 
 27 
 
 24^ 
 
 5 
 
 16 
 
 2 9 
 3^2 
 
 9 
 
 9^ 
 
 18 
 
 i6f 
 
 5 
 T6 
 
 1 3 
 
 lis- 
 
 NOTE.— By "release" is meant the position of the piston from end of stroke at moment of 
 exhaust opening^. 
 
 By "compression'" is meant the position of the piston from end of stroke at moment of 
 exhaust closing. 
 
Slide Valves, Piston Valves, Valve Data, &c. 247 
 
 Mean Cut-off and Expansion Grade. — These are determined as 
 follows : — 
 
 H.P. Cylinder, Full Gear — 
 
 Top cut-off =44i inches, 
 Bottom cut-off =39^ ,, 
 
 Then, 44l25 + 39"5— ^j.g^e inches mean cut-off. 
 
 2 
 
 Expansion Grade = 41 -875 inches -=-60 inches (stroke) =: 69 of stroke. 
 
 ist LP. Cylinder, Full Gear- 
 Top cut-off —43 inches, 
 Bottom cut-off =39| „ 
 
 Then, ~ — ■^^'^^^ = 41-18 inches mean cut-off. * 
 
 2 
 
 Expansion Grades 41- 18 inches -r 60 inches = -68 of stroke. 
 
 2nd LP. Cylinder, Full Gear — 
 
 Top cut-off =44i inches, 
 Bottom cut-off =40 ,, 
 Then, 44-025 + 40 _^^^ inches mean cut-off. 
 
 Expansion Grade =42-31 inches -f 60 inches = -70 of stroke. 
 
 L.P. Cylinder, Full Gear- 
 Top cut-off =39i inches. 
 Bottom cut-off =35 J ,, 
 
 Then, 39'5 + 35'25 .-gy.gy inches mean cut-off. 
 
 Expansion Grade = 37-37 inches -^ 60 inches = -62 of stroke. 
 
 l3 
 
248 
 
 "Verbal" Notes and Sketches 
 
 No. 6 — Type; — Cargo Steamer. — I.H.P., 1630; Speed, ii-6 knots; 
 Cylinders, 26, 42, 70 inches ; Stroke, 48 inches ; Boiler 
 pressure, 180 lbs.; H.P. receiver, 175 lbs.; LP., 56 lbs.; 
 L.P., 9 lbs. ; Vacuum, 24 inches ; Revolutions, 60-5. 
 
 VALVE SETTINGS. 
 H.P. Piston Valve. 
 
 Expansion 
 Grade 
 (mean). 
 
 > 
 
 9 
 
 > 
 
 Lead. 
 
 Steam Lap. 
 
 Port Opening. 
 
 Cut-off. 
 
 Exhaust 
 Lap. 
 
 Release. 
 
 Com- 
 pression. 
 
 Top 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 Top. 
 
 Bot, 
 
 Top. 
 
 Bot. 
 
 Top 
 
 Bot. 
 
 Top 
 
 Bot. 
 
 Top. 
 
 Bot. 
 
 •52 
 
 In. 
 7 
 
 In. 
 
 In. 
 
 3 
 
 ■5" 
 
 In. 
 
 In. 
 2-?- 
 
 In. 
 
 T 3 
 
 In. 
 T 5 
 
 In. 
 
 27J 
 
 In. 
 22f 
 
 In. 
 
 1 
 Ttr 
 
 In. 
 
 13 
 IS" 
 
 In. 
 
 5f 
 
 In. 
 5* 
 
 In. 
 9f 
 
 In. 
 9f 
 
 LP. D.P. Valve. 
 
 •62 
 
 7 
 
 3 
 
 i 
 
 2 
 
 4 
 
 A 
 
 
 32I 
 
 28i 
 
 T6 li 
 
 3f 
 
 2\ lof 
 
 lof 
 
 L.P. D.P. Valve. 
 
 •56 
 
 7 
 
 1 
 
 11 
 
 16 
 
 2-1- 
 
 ill 
 
 Ifp 
 
 
 29J 
 
 2Si 
 
 5 
 
 li 
 
 4| 
 
 3l 
 
 12I 
 
 I2| 
 
 NOTE. — The above is a very fair example of valve setting for a set of engines 
 of the power given, and the results as tabulated represent good practice. It will 
 be noticed that the " compression " or exhaust closing position occurs earlier in the 
 I. P. than the H.P., and earlier still in the L.P. This is to allow for the heavier 
 weight of the moving parts in these cylinders, the inertia of which has to be 
 overcome at the end of each stroke. 
 
 Observe, then, that — 
 
 1. The amount of lead opening increases with each cylinder. 
 
 2. „ „ exhaust lap 
 
 3. The moment of compression (exhaust closing) is earlier in each 
 cylinder from H.P. to L.P. 
 
 Valve Diagrams. 
 
 By means of the well-known " valve diagrams " devised by Zeuner 
 the eminent Swiss engineer and scientist, the required steam lap, 
 port opening, exhaust lap, &c., may be calculated for a valve, and the 
 following example from actual practice should be carefully studied. 
 
Slide Valves, Piston Valves, Valve Data, &c. 249 
 
 Example. — Engine stroke, 42 inches ; connecting rod, 7 feet 
 6 inches in length ; valve travel to be yl inches; top lead, ^ inch; 
 bottom lead, I inch; bottom exhaust lap 4-i inch; top exhaust 
 lap — 1 inch. 
 
 (A.) Find the required steam lap and port opening for a maximum 
 down stroke cut-off of •/. (B.) Also find the cut-off on the up stroke 
 due to the necessary difference in steam lap and lead at the bottom 
 as compared with the top. 
 
 NOTE.— The sum of the steam lap and lead is the same top and bottom, there- 
 fore what is gained in lead at the bottom end is lost in steam lap ; this also propor- 
 tionally alters the maximum port opening. 
 
 Application. — Stroke, 42 inches x 7 = 29-4 inches cut-off on down 
 stroke. 
 
 (A.) First set off to a small scale (say i inch to i foot) the small 
 diagram of crank-pin circle and crosshead or piston travel as shown 
 in No. 49, proceeding as follows : — 
 
 1. Set off vertically 42 inches by scale, then measure down from 
 the centre of this, or half stroke the connecting rod length of 7 feet 
 6 inches which gives the centre of shaft ; next with a radius of 
 21 inches (half stroke) set off the crank-pin travel circle. Now 
 measure down from the top of stroke 29-4 inches (shown by the inch 
 divisions from the 24-inch distance) and with the connecting rod 
 length of 7 feet 6 inches in the compasses set the needle point on the 
 crosshead centre and make a mark, F, on the crank-pin circle : this 
 mark F is the position of crank-pin centre at cut-off. Connect the 
 shaft centre and F, the crank-pin centre, which gives the crank angle 
 at the "cut-off" position. 
 
 2. To a scale of full size, or at least half size, set off the valve 
 travel circle of 7 J inches diameter, and with the lead radius of ;^ inch 
 also set off an arc from the top diameter of the circle marked as L ; 
 now transfer the angle of the crank at cut-off from the small diagram 
 to the larger one, by describing a radius as at B, which is again 
 repeated on the large diagram at B, and the -length between taken 
 in the compasses from the small diagram and measured off on the 
 large one as shown : this gives the exact angle of the crank at cut-off, 
 which is carried out as shown to point 2 on the valve travel circle. 
 
 3. Draw a line from point 2 tangentially to the lead arc L, and 
 where it cuts the valve circle put in by hand a small locating circle, 
 also one at point 2 ; now bisect the line extending between points 
 I and 2, by either describing arcs as shown, or by trial with the 
 dividers, and draw out a line from the centre. We then find the 
 required steam lap and maximum port opening as measured, the 
 steam lap being 2fV inches, and the port opening ly^ inches, the sum of 
 the two (2ji'g + iYV inches) being, of course, equal to half the valve 
 
250 
 
 "Verbal" Notes and Sketches 
 
 travel, or 3I inches; finally describe a circle on the line as shown, 
 called the primary valve circle. 
 
 00 CUT-OFF. 
 
 "T 
 
 No. 49. 
 
 4. Set off a small semicircle, E, I inch radius on the line last 
 mentioned, which semicircle represents the minus exhaust lap of the 
 
No 
 L = Le 
 
 I, Crank Angle at 
 
VALVE 
 
 TRAVEL 
 
 Iz 
 
 No. 50.— Valve Diagram for Top. 
 . = Lead g inch. £=-j inch Exhaust Lap. 
 
 3, Crank Angle at Release. 
 
 4, 5, .. Compresstoo. 
 
 in/art pagi 25<X 
 
Slide Valves, Piston Valves, Valve Data, &c. 251 
 
 top, and run out lines from the centre through the points intersected 
 on the primary valve circle ; the lines thus drawn give the crank 
 angle at exhaust opening, or "Release" (3), and exhaust closing, or 
 " Compression " (4). 
 
 NOTE.— If the valve had neither plus nor minus exhaust lap, the dotted line 
 shown (drawn parallel to the line i. 2) would then give the crank angles at 
 exhaust opening and closing. 
 
 Points of Importance. — i. Notice that, "Port opening" + " Steam lap" 
 = Half travel. 
 
 2. The exhaust openings 3| + | = 4 inches, but as the actual port 
 width is less than this the opening is necessarily limited to the 
 port width. 
 
 3. No. I crank angle at lead opening (" Admission "). 
 
 „ 2 „ „ Cut-off. 
 
 „ 3 „ „ exhaust opening (" Release "). 
 
 „ 4 „ „ „ closing (" Compression "). 
 
 { From I to 2 steam is being admitted, 
 
 Therefore, \ - ^ „ 3 „ „ expanded 
 
 J „ 3 ,, 4 „ » exhausted, 
 
 ' „ 4 „ I „ „ compressed. 
 
 Observe that in the vertical centre line the lead L is shown measured 
 between the steam lap curve and the primary valve circle, and this (if 
 the drawing is accurately done) will be exactly equal to the small 
 arc L at the top, in this case = ^ inch. 
 
 Release and Compression. — To find how far the piston is from the 
 end of the stroke at " release" and "compression," transfer the angles 
 of the crank at positions 3 and 4 dack to the small diagram from the 
 large one as shown in Sketch No. 51 (as described for B), then set off 
 the connecting rod length 7 feet 6 inches on the small diagram 
 upwards from point 3 and from point 4 to the centre line, at which 
 positions draw horizontal lines for the crosshead centres ; now set off 
 a few inches by scale from either end, and measure how many inches 
 are included from the crosshead centre line and end of stroke, which 
 will be the positions of release and compression required. Notice 
 that release occurs 5 inches from the bottom end of stroke, and 
 compression 4^ inches from the top end of stroke. 
 
 (^.) Referring to the data already given we find that the top steam 
 lap and lead = 2fV + F — ^A inches, so that if the bottom lead is to 
 be \ inch, then '2,x^ — \ — 2^^ inches steam lap at bottom, as the sum of 
 the two must be the same. 
 
25 
 
 tra 
 cal 
 
» 
 
 Slide Valves, Piston Valves, Valve Data, &c. 251 
 
 top, and run out lines from the centre through the points intersected 
 on the primary valve circle ; the lines thus drawn give the crank 
 angle at exhaust opening, or "Release" (3), and exhaust closing, or 
 " Compression " (4). 
 
 NOTE.— If the valve had neither plus nor minus exhaust lap, the dotted line 
 shown (drawn parallel to the Hne i. 2) would then give the crank angles at 
 exhaust opening and closing. 
 
 Points of Importance. — i. Notice that, "Port opening" + " Steam lap" 
 = Half travel. 
 
 2. The exhaust opening=3| + 1 =4 inches, but as the actual port 
 width is less than this the opening is necessarily limited to the 
 port width. 
 
 3. No. I crank angle at lead opening (" Admission "). 
 
 „ 2 „ „ Cut-off. 
 
 „ 3 „ „ exhaust opening (" Release "). 
 
 „ 4 „ „ „ closing (" Compression "). 
 
 From I to 2 steam is being admitted, 
 
 Therefore, i - ^ " 3 ,. „ expanded 
 
 ) „ 3 „ 4 „ „ exhausted, 
 
 „ 4 „ I „ „ compressed. 
 
 Observe that in the vertical centre line the lead L is shown measured 
 between the steam lap curve and the primary valve circle, and this (if 
 the drawing is accurately done) will be exactly equal to the small 
 arc L at the top, in this case = ^ inch. 
 
 Release and Compression. — To find how far the piston is from the 
 end of the stroke at "release" and "compression," transfer the angles 
 of the crank at positions 3 and 4 dack to the small diagram from the 
 large one as shown in Sketch No. 51 (as described for />), then set off 
 the connecting rod length 7 feet 6 inches on the small diagram 
 upwards from point 3 and from point 4 to the centre line, at which 
 positions draw horizontal lines for the crosshead centres ; now set off 
 a few inches by scale from either end, and measure how many inches 
 are included from the crosshead centre line and end of stroke, which 
 will be the positions of release and compression required. Notice 
 that release occurs 5 inches from the bottom end of stroke, and 
 compression 4f inches from the top end of stroke. 
 
 (v5.) Referring to the data already given we find that the top steam 
 lap and lead=:2YJ5 +F = 2y^ inches, so that if the bottom lead is to 
 be \ inch, then 2yV — | = 2jV inches steam lap at bottom, as the sum of 
 the two must be the same. 
 
252 
 
 "Verbal" Notes and Sketches 
 
 "«^ CLOSING 
 
 OPENING 
 
 No. 51. 
 
 Application (Sketch No. 54). 
 
 I. As before, set off the valve travel circle 7^ inches diameter 
 either full size or half size, and set off the lead arc at the bottom 
 centre with | inch radius in the compasses. Now take in a radius 
 of 2iV inches representing the steam lap at bottom, and describe an 
 
Slide Valves, Piston Valves, Valve Data, &c. 253 
 
 42 
 36 
 
 24 
 
 12 
 
 
 
 II 
 
 — 
 
 
 1 
 
 1 
 1 
 
 II '- '-'- 
 
 -H 
 
 >--.-- 
 
 
 
 UJ 
 
 
 
 / 
 
 ic: 
 
 
 
 • / 
 
 
 
 
 
 / 
 
 en 
 
 II 
 
 
 '^ 
 
 1- 
 
 
 
 tO / 
 
 
 
 
 CO / 
 
 
 CUT-OFF. 
 
 No. 52. 
 
 arc from the centre of the circle as shown ; next draw a line tangential 
 to both lead and lap arcs, and where this cuts the valve travel circle in 
 points I and 2 it gives the crank angles at " lead " and " cut-off." 
 
 2. Transfer the angle B of crank at "cut-off" (position 2) from the 
 valve travel diagram back to the small diagram at F (Sketch 52), and 
 
•54 
 
 "Verbal" Notes and Sketches 
 
 ^ "^ OPENING 
 
 No. 53. 
 
 with the connecting rod length 7 feet 6 inches in the compasses, and 
 the needle point on position F, mark the centre Hne for the crosshead 
 centre as shown ; finally measure by the scale of the small diagram 
 how many inches are included between the bottom end of stroke and 
 the crosshead, which will give the up stroke cut-off, in this case 
 25.5 inches. The positions of " Release " and " Compression " can be 
 
 I 
 
13VAH i 
 
 55 
 
 en 
 nd 
 
 / 
 
 311 
 )W 
 
 •.le 
 n- 
 :e, 
 n- 
 i" 
 
^<>''>^ 
 
 .^^^.v^r 
 
 ,v: 
 
 L 
 
 No. 54.— Valve Diagram for Bottom. 
 L = Lead i inch. E=+i inch Exhaust Lap. 
 
 : Release. 
 Comptes! 
 
Slide Valves, Piston Valves, Valve Data, &c. 255 
 
 located by the method described for the down stroke, and when 
 applied give a release of 4i| inches from top end of stroke and 
 compression of 5 inches from bottom end of stroke (Sketch 53), 
 
 3. Set off the bottom exhaust lap | inch on circle described on 
 the ;7^/// An// of the valve travel diameter and shown as E. Now 
 draw out crank lines at the intersection of this arc on the circle 
 mentioned, and the positions of crank angle at release 3, and com- 
 pression 4 will be found. As before described for the down stroke, 
 set off these angles back on the small diagram, measure up the con- 
 necting rod lengths, and the positions of" Release" and "Compression" 
 from the end of stroke can be measured as shown (Sketch 53). 
 
 I 
 
 f&"'"'-- 
 
 CM 
 
 .'it- 
 
 No. 55.— Slide Valve. 
 
 For Valve Diagram. Showing the required steam lap and exhaust lap top 
 and bottom as determined by the valve diagram. 
 
 NOTE. — Lining up a slide valve decreases the bottom steam lap and increases 
 the top steam lap ; but, if a piston valve, the reverse effects are obtained, the 
 bottom steam lap being increased and the top decreased. The total steam lap 
 remains constant in both cases. ~~~ 
 
2 54 
 
 %%^ 
 
 
 / a^ \, 
 
 
 with 
 
 the r 
 
 centi 
 
 how 
 
 the 
 
 25.S 
 
 sV— .ii^ .oM 
 
Slide Valves, Piston Valves, Valve Data, &c. 255 
 
 located by the method described for the down stroke, and when 
 applied give a release of 4'^ inches from top end of stroke and 
 compression of 5 inches from bottom end of stroke (Sketch 53). 
 
 3. Set off the bottom exhaust lap \ inch on circle described on 
 the ;/>/// half o{ the valve travel diameter and shown as E. Now 
 draw out crank lines at the intersection of this arc on the circle 
 mentioned, and the positions of crank angle at release 3, and com- 
 pression 4 will be found. As before described for the down stroke, 
 set off these angles back on the small diagram, measure up the con- 
 necting rod lengths, and the positions of" Release" and "Compression" 
 from the end of stroke can be measured as shown (Sketch 53). 
 
 
 CVJ 
 
 L ^. 
 
 No. 55.— Slide Valve. 
 
 For Valve Diagram. Showing the required steam lap and exhaust lap top 
 and bottom as determined by the valve diagram. 
 
 NOTE. — Lining up a slide valve decreases the bottom steam lap and increases 
 the top steam lap ; but, if a piston valve, the reverse effects are obtained, the 
 bottom steam lap being increased and the top decreased. The total steam lap 
 remains constant in both cases. 
 
256 
 
 " Verbal " Notes and Sketches 
 
 As before stated, release occurs 4^ inches from end of stroke, and 
 compression 5 inches from end of stroke. 
 
 General. — The general valve data now work out as tabulated 
 below : — 
 
 Valve Travel, 
 
 Lead. 
 
 Steam 
 Lap. 
 
 Port 
 Opening. 
 
 Cut-off. 
 
 Release. 
 
 Compression. 
 
 Top 
 Bottom - 
 
 Inch. 
 1 
 
 1" 
 
 i 
 
 Inches. 
 2tV 
 
 Inches. 
 T ^ 
 
 T 1 1 
 
 Inches. 
 29-4 
 
 25-5 
 
 Inches. 
 
 5 
 
 4l 
 
 Inches. 
 4| 
 5 
 
 NOTE.— Half travel 3I inches - Bottom Steam lap 2i\ inches=iH inches 
 Bottom Port opening. 
 
 Observe that even with /ess steam lap on the bottom end of valve 
 than on the top the bottom or up stroke cut-ofF is earlier than the 
 down stroke. This is due to the angle formed by the connecting rod 
 and crank, and occurs in most cases in practice. 
 
 No, 56.— Keyseat Template. 
 For Valve Diagram. 
 
 "Open" and "Crossed" Eccentric Rods. 
 
 By this is understood the position of the eccentric rods w/ten the 
 crank is on tlie bottom centre, as in running the rods open and cross 
 each other alternately all the time. For slide valves or outside steam 
 piston valves the rods are usually arranged as "open," but with inside 
 steam piston valves the rods are fitted " crossed " when the crank is 
 on the bottom centre. This is to obtain the full benefit of link expan- 
 
 \ 
 
Slide Valves, Piston Valves, Valve Data, &c. 
 
 ■57 
 
 sion, as if the rods were arranged the reverse way the lead would be 
 diminished when linked up, and the range of expansion more limited, 
 as shown on diagram No. 58. To obtain similar effects with piston 
 valve gear of the inside steam type, as the motion of valve is reversed, 
 the fitting of the rods must be also reversed, so that crossed rods take 
 the place of open rods for the latter type of valve. The general effects 
 may be summarised as follows (see also page 211). 
 
 Effects of Linking-up (Slide Valves). 
 
 Arrangement 
 of Eccentric Rods. 
 
 Valve 
 Travel. 
 
 Lead. 
 
 Cut-off. 
 
 Release. 
 
 Com- 
 pression. 
 
 " Open " Rods 1 
 1 (crank on bottom). / 
 
 Reduced. 
 
 Increased. 
 
 Earlier. 
 
 Earlier. 
 
 Earlier. 
 
 "Crossed" Rods \ 
 (crank on bottom), j 
 
 Reduced. 
 
 Decreased. 
 
 Earlier. 
 
 Earlier. 
 
 Earlier. 
 
 NOTE. — The amount of steam lap and exhaust lap of the valve remains 
 unchanged, but the port opening is less, in exact proportion to the reduced valve 
 travel. 
 
 The special disadvantages of linking up are : — 
 
 1. Excess wire drawing of steam, due to reduced port opening. 
 
 2. Rapid increase of compression, which reduces effective area 
 of indicator diagram. As before stated, it should be noted that to 
 obtain the above effects with inside steam valves the rods require to 
 be crossed instead of open, with crank centred on bottom : this is 
 due to the fact that with slide valves and open rods, when the link 
 is shut in the valve is slightly lowered by the angle described by the 
 rod in moving over if crank is on the top centre, and slightly 
 raised if crank is on the bottom centre, thus increasing the lead ; 
 but with inside steam valves the lead would be diminished in like 
 [proportion ; therefore, to obtain equal effects, the rods must be 
 
 arranged as crossed with crank on bottom, when the valve is of the 
 [inside steam type. 
 
 Taking, then, a three-cylinder triple-expansion engine of the 
 
 usual type, the eccentric rod and crank positions are therefore 
 [arranged as follows: — 
 
 Cranks and Eccentric Rods. 
 
 Eccentric Rods crossed (crank 
 
 on bottom). 
 Eccentric Rods open (crank on 
 
 bottom). 
 Eccentric Rods open (crank on 
 
 bottom). 
 
 This arrangement allows of equal linking-up effects in all three engines. 
 
 H.P. inside steam piston valve, 
 LP. common slide valve, 
 L.P. double ported slide valve, 
 
258 "Verbal" Notes and Sketches 
 
 Diagram for Gear Linked up. 
 
 To construct an approximate valve diagram showing the various 
 effects produced by shutting in the gear, proceed as follows : — 
 
 Method. 
 
 1. Measure the length of the eccentric rods from centre of pin on 
 quadrant to coitrc of pulley. Measure the distance between the 
 eccentric pulley centres and between the eccentric rod pins on link 
 bar (usually equal to three times valve travel). 
 
 2. Find a radius for the equivalent valve travel circle arc, by the 
 method devised by the late Mr Macfarlane Gray, and which reads 
 as follows : — 
 
 A r H ufi - Eccentric rod length x distance between pulleys 
 2 X distance between quadrant pins 
 
 Assuming, then, that for the case already described, the eccentric 
 rod length centre to centre is 96 inches, the distance between the 
 quadrant bar pins 22|- inches, the distance between the pulley centres 
 can be measured on the previous " full gear " diagram, or can be 
 measured direct on the new " linked up " diagram. 
 
 In sketch No. 58 it will be seen that the previous top diagram is 
 shown complete, but in dotted lines. On this the linked up diagram 
 can be filled in, and the points of difference, in " Lead," " Cut-off," 
 " Release," and " Compression " can then be easily compared. 
 
 3. First draw a horizontal line across from E to C, and this 
 measured will be the required distance between the pulleys, which 
 in this case is 5f inches. 
 
 Now apply the rule given to find the radius of the arc shown 
 connecting C and E. 
 
 Thus, Radius= 96i"-x5-875 jn.^ i„^hes. 
 
 2 X 22-5 in. 
 
 With a radius of I2| inches in the compasses describe the arc as 
 shown. 
 
 4. Now suppose that the link expansion gear is shut in so that 
 the cut-off is -40 (40 per cent.) of the stroke, and that in this grade 
 the quadrant block occupies the position shown, that is, 5^ inches 
 from the pin on quadrant ; or exactly one-fourth of the total distance, 
 as 22-5 ^5-625 =4. 
 
 Now mark on point D on the diagram arc in the same relative 
 position, that is, DE = one-fourth of CE, and from the point D draw in 
 a centre line on which construct the " steam " circle shown in full lines, 
 then continue this line to the other side, and describe the " exhaust " 
 circle. The sum of the two circle diameters is equal to the linked-up 
 valve travel which in the present case measures 6 inches. To complete 
 the other points notice whe*-e the steam lap arc, and small minus 
 
Slide Valves. Piston Valves, Valve Data, &c. 
 
 259 
 
 !- - - Zti >! 
 
 No. 57.— Quadrant and Eccentrics. 
 
 exhaust lap arc, intersect the circles described, and project radial 
 lines out to the valve travel circle for the crank angles to correspond 
 
 If this ,s done carefully it will be found that afi pointsToTocct 
 sooner, and that the jead is increased from \ in to J in 
 
26o 
 
 " Verbal " Notes and Sketches 
 
 1. Crank at lead - - - Full gear. 
 IB. „ „ . . - Linked up. 
 
 2. Crank at cut-off - - - Full gear. 
 2B. ,, » ... Linked np. 
 
 3. Crank at release - - - Full gear. 
 3B. ,, „ ... Linked up. 
 
 4. Crank at compression - - Full gear. 
 4B. „ J, ... Linked up. 
 
 If the various crank angles are now transferred back to the small 
 scale engine stroke diagram, as described previously, the new positions 
 of release, compression, &c., can be determined. 
 
 In the example shown the linked-up data work out as follows : — 
 
 Valve Data (Linked up). 
 
 Valve Travel, 
 6 in. 
 
 Lead. 
 
 Steam 
 Lap. 
 
 Port 
 Opening. 
 
 Cut-off. 
 
 Exhaust 
 Lap. 
 
 Release. 
 
 Com- 
 pression. 
 
 Top - 
 
 In. 
 
 tV 
 
 In. 
 
 2t6 
 
 In. 
 
 1 .3 
 
 In. 
 
 In. 
 
 In. 
 lol 
 
 In. 
 1 1 
 
 NOTE.— It should be carefully noted that the gear is of the open rods type, that 
 is, with the crank on bottom centre the rods are open as shown in the Sketch No. 22. 
 If with a slide valve the rods are arranged " crossed " the lead would be less, and the 
 expansion range much more limited, as the arc C,E, would then require to be taken 
 from a centre above the shaft in place of below, and this would result in the arc being 
 convex to the shaft centre line instead of concave as at present. 
 
 To find Valve Travel. (No. 59.) 
 
 In a case where the steam port opening is decided upon first of 
 all, the required valve travel (and therefore steam laps) may be deter- 
 mined by the following construction. First set off, to a suitable scale, 
 ACB, the crank pin travel circle, OB being the angle of crank at 
 cut-off. Join AB, and bisect it at point C, now join AC, and set off 
 at D, DE, the port opening determined oii, less half the lead ; next 
 draw a line at E parallel to AD, and where the line so drawn cuts 
 AC at F, draw a short line parallel to OC into the centre line at G ; 
 then FG is equal to half the valve travel, so that twice FG will give 
 full travel of valve required. 
 
 Bellis and Morcom Engine. 
 
 This type of engine is compound with the valve chest common to 
 both cylinders placed between them, the valves of the piston type 
 being arranged tandem fashion, and on the same valve spindle. 
 
 Action. — The engine cranks are opposite each other, or are at an 
 angle of 180°. The H.P. piston valve receives steam in the centre 
 
VAI\/F 
 
 Q 
 
 ^$ ^ 
 
 
 No. 60. — Bellis and Morcom High Speed Compound Engine. 
 
No. 58. — Valve Diagram showing Effects of Linking Up. 
 
 Crank angle at " lead," full gear. 
 B. ,. ,. .. linked up. 
 
 , Crank angle at "cut-off," full gear. 
 B, „ „ „ linked up. 
 
 3, Crank angle at " release," full gear. 
 3B, „ ,, ., linked up. 
 
 4, Crank angle at " compression," full gear, 
 48, „ ,t ti linked up. 
 
 m 
 
Slide Valves, Piston Valves, Valve Data, &c. 261 
 
 No. 59.— Construction to find Valve Travel. 
 
 k 
 
 No. 60. — Bellis and Morcom High Speed Compound Engine. 
 
26o 
 
 \r v,„i " T\.T_._- 1 oi . 1 
 
 scal( 
 of n 
 
 Val ,>,a^ 
 
 To 
 
 N 
 is, w 
 Ifwi 
 
 from *<r ti , ( _ 
 
 conyi S \ ' 
 
 To 
 
 all.i 
 min 
 AC 
 cut- 
 at I 
 dra\ 
 AC 
 thei 
 full 
 
 Bel 
 
 botl 
 beii 
 
 Action. — The engine cranks are opposite each other, or are at an 
 angle of i8o°. The H.P. piston valve receives steam in the gentre 
 
Slide Valves, Piston Valves, Valve Data, &c. 261 
 
 No. 59.— Construction to find Valve Travel. 
 
 I 
 
 No. 60. — Bellis and Morcom High Speed Compound Engine. 
 
262 
 
 " Verbal ' Notes and Sketches 
 
 or inside edges, and the L.P. "valve receives steam at the ends or 
 outside edges, so that the exhaust of the ILP. valve being over the 
 ends serves as the admission steam for the L.P. valve, the exhaust 
 of the L.P. valve opens up to the exhaust casing and exhaust pipe 
 to the condenser. Notice that the valves are hollow cast to allow of 
 steam flow from end to end. 
 
 The sketch and following data of valve setting for this type of 
 engine are taken from the Mechanical J F(3r/<^ of September 1910. 
 
 Data for Bellis and Morcom Engine. 
 
 Cylinders, 10 inches diameter and 17 inches diameter; stroke, 9 inches; 
 piston valves, 6i inches diameter ; revolutions, 400. 
 
 Valve Travel, 2| Inches. 
 
 H.P. Cylinder. 
 
 L.P. Cylinder. 
 
 Top. 
 
 Bottom. 
 
 Top. 
 
 Bottom. 
 
 Steam Lap 
 
 Lead - - - - 
 
 Cut-off (Mean) - 
 
 Inch. 
 
 sir 
 
 1 
 
 Inch. 
 1 3 
 
 16 
 
 1 
 
 Inch. 
 
 f 
 1 
 
 "8 
 
 Inch. 
 
 1 1 
 
 To 
 
 .•5 
 TF 
 
 •64 
 
 •66 
 
 NOTE.— Observe that the sum of the top or bottom steam lap and lead is the 
 same, or, in other words, what is gained in lead at the bottom end is lost in steam 
 lap, the sum of the two remaining the same. 
 
 Referring to table- 
 
 "•'^- 1 Bottom, if + tV 
 
 27 1 1 _ 28 _ 14 _ 7 j„pl, 
 
 i* — 1 
 
 1(3 8 " 
 
 3 4. 
 
 •( Bottom, ii + 3?e=iA= t » 
 
 As the same pulley drives both valves, the sum of the steam lap 
 and lead requires to be the same for each cylinder, as shown above. 
 
 Port Opening. 
 
 Half travel = Steam Lap + Port Opening. 
 2| inches -=- 2 = i| inches ^ Half travel. 
 
 Therefore, 
 
 TT D f And, if inches - \1t inch = ^^ inch Port opening at top, 
 "•*^- \Also, 
 
 (Again, 
 
 L.P. 
 
 \And, 
 
 1 3 
 
 1 6 
 
 j> 
 
 _ 9 
 
 \ 
 
 1 1 
 
 Tir 
 
 
 _ 1 
 8 
 _ 1 1 
 
 bottom. 
 
 top. 
 bottom. 
 
 i 
 
Slide Valves, Piston Valves, Valve Data, &c. 263 
 Effects of Link Adjustments on LH.P. 
 
 No. 
 
 Link Alteration. 
 
 Effect on I. H.P. 
 
 I 
 2 
 
 3 
 4 
 5 
 6 
 
 H.P. shut in - 
 H.P. opened out 
 
 LP. shut in 
 LP. opened out 
 L.P. shut in 
 L.P. opened out 
 
 (H.P. power practically unaltered. 
 'lP. and L.P. power decreased. 
 (Total power reduced. 
 (H.P power practically unaltered. 
 '. I. P. and L.P. power increased. 
 [Total power increased. 
 
 / H.P. power decreased. 
 ) LP. power increased, 
 j L.P. power unaltered. 
 (. Total power unaltered. 
 
 / H.P, power increased. 
 ) LP. power decreased. 
 j L.P. power unaltered. 
 V Total power unaltered. 
 
 / H.P. power unaltered. 
 J LP. power decreased. 
 J L.P. power increased. 
 ( Total power unaltered. 
 
 /H.P. power unaltered. 
 1 LP. power increased. 
 1 L.P. power decreased. 
 \ Total power unaltered. 
 
 From the foregoing it will be evident that the back pressure of 
 one engine varies with the cut-off in the next engine, so that if, say, 
 the LP. link is shut in the H.P. back pressure will rise, but if the LP. 
 link is opened out the H.P. back pressure will fall ; the same holding 
 good for the L.P. cut-off in relation to the LP. back pressure. 
 
 The back pressure on a piston depends then on the following : — 
 I. On the point of cut-off, which gives a proportional terminal pres- 
 sure and back pressure for a receiver of given capacity. 2. On the 
 cut-off of the next engine, which, if early, increases the back pressure 
 of the preceding engine piston, and which, if late, lowers that back 
 pressure as before described. 
 
 As quite a number of readers do not appear to understand how in 
 link alterations Nos. i and 2 the H.P. power remains practically 
 unaltered, the following explanation is given by the writer (who is 
 often referred to on this point), with the hope of clearing up the 
 matter, 
 19 
 
263^ 
 
 "Verbal" Notes and Sketches 
 
 When the H.P. is shut in the cut off is earHer on the same initial 
 pressure line, giving a lower expansion curve pressure and a lower 
 back pressure line, the one practically making up for the other, so 
 that the actual area of the diagram is almost unaltered. 
 
 In the same way, when the H.P. link is opened out the cut-ofif is 
 later on the same initial pressure line, giving a higher expansion curve 
 pressure, and correspondingly a higher back pressure line, the one 
 practically balancing the other, so that, as before, the card area is only 
 very slightly affected. Any difference in H.P. power is principally 
 due to difference in revs., as with H.P. shut in the revs, are less, and 
 with H.P. opened out the revs, are more. 
 
 To further assist in making this point clear a set of cards are given on 
 page 263^ (taken from the author's " Marine Engine Indicator Cards ") 
 showing the actual effects produced when the H.P. link is shut in. 
 
 To any readers who may have the chance of experimenting, the 
 writer would advise an actual test with link adjustments, when the 
 results will be found to be as here stated. 
 
 
 Effects of Various Link A 
 
 djustmentj 
 
 »• 
 
 
 Link 
 Adjustment. 
 
 Effect on I. H.P. Distrit 
 Each Cylinder. 
 
 ution in 
 
 Effect 
 
 on 
 
 Total LH.P. 
 
 H.P. 
 
 I. P. 
 
 L.P. 
 
 I. 
 
 LP. shut in 
 
 and L.P. 
 
 opened out. 
 
 Power 
 reduced 
 
 Power 
 increased 
 
 Power 
 reduced 
 
 Unaltered 
 
 2. 
 
 LP. opened 
 
 out and 
 L.P. shut in 
 
 Power 
 increased 
 
 Power 
 reduced 
 
 Power 
 increased 
 
 Unaltered 
 
 3- 
 
 LP. and 
 
 L.P. 
 
 both shut in 
 
 Power 
 reduced 
 
 Power about 
 the same 
 as before 
 
 Power 
 
 increased 
 
 Unaltered 
 
 4- 
 
 LP. and L.P. 
 
 both 
 
 opened out 
 
 Power 
 increased 
 
 Power about 
 the same 
 as before 
 
 Power 
 reduced 
 
 Unaltered 
 
 5- 
 
 H.P. link 
 
 and 
 
 L.P. link 
 
 shut in 
 
 Power 
 
 only 
 slightly 
 reduced 
 
 Power 
 
 much 
 
 reduced 
 
 Power 
 
 slightly 
 reduced 
 
 Reduced 
 
 6. 
 
 All engines 
 
 linked up by 
 
 means of 
 
 reversing wheel 
 
 Power 
 reduced 
 
 Power 
 reduced 
 
 Power 
 reduced 
 
 Reduced 
 
 Note. — When the reversing wheel is employed to link up, the LH.P. of each cylinder 
 is reduced by about the same amount. 
 
 Note. — If the links cannot be altered, similar effects can be obtained by valve and 
 eccentric adjustments as follows : — 
 
 In place of shutting in the links, piece valve (increase steam lap) top and bottom, and 
 advance pulley. 
 
 In place of opening out the links, chip valve (reduce steam lap) top and bottom, and 
 put pulley back an equal amount. 
 
Slide Valves, Piston Valves, Valve Data, &c. 263^5 
 
 A.L. 
 
 A.L. 
 
 No. 60a.— Set of Cards. 
 
 Dotted lines show effects produced by — 
 
 A, Shutting in H.P. link ; or 
 
 B, Increasing steam lap of H.P. Valve and advancing the eccentric. 
 
 /HP. power only sHghtly less. 
 Effects I J p po^er reduced. 
 „ ^ i L. P. power reduced. 
 
 Horsepower ( Total power reduced. 
 
263^ 
 
 "Verbal" Notes and Sketches 
 
 To Mark off Eccentric Keyseat Positions on Shaft, the Valve 
 having been Removed from the Casing and no Valve Data 
 Available for Reference. 
 
 4-4 
 
 p^ 
 
 40' 
 
 .-\t- 
 
 No. 60b.— V^ve and Eccentric 
 
 The sketches show the cylinder face, say, 40" in depth from 
 upper edge of top steam port to lower edge of bottom steam port ; 
 the valve face, say, 44" in depth ; and the eccentric 10" in width on 
 one side, and 2" on the other side. 
 
Slide Valves, Piston Valves, Valve Data, &c. 263^^^ 
 
 Proceed as follows : — 
 
 Mean steam lap = ^ ~ ^ -- = 2" mean steam lap for both 
 ^ top and bottom. 
 
 Assume lead, say, ^" top. ^" bottom. 
 
 Then, Mean lead = L'JLi ' = " " 
 
 2 
 
 So that mean steam lap and lead = 2" + ^V = 2^". 
 
 Valve Travel = 10" — 2" = 8". 
 
 Next proceed to set out keyseat diagram (shown on right) by 
 Irawing the outer circle of shaft 14" diameter, also inner circle of 
 ^alve travel 8" diameter, then measure down from centre the mean 
 keam lap and lead = 2yV, project out the lines, and mark off key- 
 ;at positions in the usual manner. After bolting on the pulleys 
 'the valve will have the sauie amount of lap and lead at both ends, 
 and to correct this, line up the rod for /la/f the lead difference, that is, 
 .1" _ 1" 
 :* = iV liner under rod. The setting will now become top lead J", 
 
 bottom lead j", top steam lap 2yV', bottom steam lap ijf". The valve 
 will then be correctly set. 
 
 To Determine the Required Difference in a Slide Valve Steam 
 Lap to obtain a Given Alteration in Cut-Off. 
 
 In place of the valve diagram method as described on page 249, 
 le following practical method may be applied : — 
 
 1. With mark on guide and shoe at top centre position, measure 
 lown on guide the distance the steam has to be carried on the stroke 
 
 ifore cut-off, then set the shoe to this mark by turning gear. 
 
 2. Remove the valve casing cover and measure the amount the 
 top edge of valve shows either below the port top edge or above it. 
 
 3. If valve top edge is short of port top edge, pin on a brass strip 
 (increase the steam lap top and bottom) equal to Jialf oi this amount, 
 and put the pulley forward the same amount as pinned on, 
 
 4. If, however, the valve top edge is over the port top edge, then 
 chip off (reduce the steam lap) for Jialf o{ this amount top and bottom, 
 and put the pulley back the same amount as chipped off. 
 
 Observe that when the steam lap is increased the pulley requires 
 to be advanced to keep the lead constant ; also, when the steam lap is 
 reduced the pulley requires to he put back to keep the lead constant. 
 
 N'ote. — For an inside steam piston valve the edges to be altered 
 would be reversed inside for outside, &c. 
 
SECTION V. 
 
 GENERAL NOTES AND DESCRIPTIONS. 
 
 The Author is indebted to the Editor of the Scottish Bankers' 
 Magazine for permission to reproduce the following article on the 
 Manufacture of Metals from the pages of that journal. 
 
 Manufacture of Iron and Steel. 
 
 Sources. — Native iron, as it is called, possessing similar properties to 
 that extracted from ores, has been found in Greenland and elsewhere 
 in small quantities, but for practical purposes it is from the ores we 
 derive our iron supply. These are widely distributed throughout the 
 earth, and vary considerably in their characteristics and purity. The 
 chief kinds in use are (i) the Magnetic (loadstone or black oxide), 
 which is the richest of all, containing as much as up to over 70 per 
 cent, of iron. A high class iron is made from this ore in conjunction 
 with charcoal in Sweden. (2) Red Hcematite, which contains up to 
 60 per cent, of iron. This ore is plentiful in the district of West 
 Cumberland and North Lancashire, and also in the north of Spain. 
 (3) Broivn HcEinatite, which is similar to the red, and from which the 
 bulk of the French and German iron is made. And (4) the carbonates 
 of iron, called spathic when comparatively pure, and also blackband 
 and clayband ironstone. This ore contains from 37 to 48 per cent, 
 of iron. It has the advantage of being found usually along with 
 coal measures ; and it has been the staple ore of Scotland. Great 
 deposits also exist in the Cleveland district, but not of equal quality. 
 
 The Blast Furnace. — The reducing or extraction of the ore is 
 effected by smelting in a blast furnace. In the case of the poorer ores 
 where more impurities are present, calcining or roasting may be a 
 preliminary operation. The effect of this is to get rid of carbonic 
 acid, water, and such other undesirable ingredients which are volatile, 
 and so render the material more suitable for treatment in the blast 
 furnace. 
 
 Blast furnaces, fairly familiar objects, are large, circular, tower-like 
 
 264 
 
 I 
 
General Notes and Descriptions 265 
 
 erections. The interior, which is not straight in form but contracts 
 towards top and bottom, is Hned with refractory fire-brick and ganister 
 (a very refractory siliceous rock) ; around this is an annular space or 
 ring filled with loose material to allow of expansion, and the outer 
 wall of masonry is enclosed in iron sheathing strongly bound together. 
 The furnaces range from 40 feet or so to 100 feet, and even more, in 
 height, with internal capacity of 500 to 25,000 cubic feet or over. The 
 modern furnaces are the highest, but it has been found that practical 
 difficulties in working counterbalance the advantages of greater height 
 when carried beyond a certain point. One advantage of the higher 
 furnace is to render previous calcining of the ore less necessary, the 
 same effect being accomplished in the upper part of the furnace. At 
 the top of the furnace is a gallery or platform from whence the charge 
 is admitted. The mouth of the furnace is closed by means of a large 
 cone, which can be lowered by a chain when charge is being admitted, 
 and then closed again. The closed top is a modern advance. 
 Formerly the mouth was open and the great, lurid flames belching 
 out made the blast furnace a picturesque feature of the district where 
 it was erected. Many will remember the time when " Dixon's 
 blazes," as they were familiarly called, formed a landmark in 
 Glasgow ; and when shipmasters on the Ayrshire coast could shape 
 their course by the glare of the Ardeer furnaces. But the old order 
 changes, and the picturesque has to give way to the practical. 
 
 The closed tops came into being when the gases generated in the 
 blast furnace were utilised with resulting efficiency and economy. 
 By-products have also become a feature of present-day practice. 
 With the utilising of the gases and slag, recovery of ammonia, and 
 so on, a combination of iron and chemical work is now common. 
 
 The Charge. — The charge consists of fuel, ore, and flux. The 
 first is commonly coke, but may also be coal or a combination of 
 both ; and charcoal is mostly used in Sweden, where coal does not 
 abound. The ores, as has been said, vary considerably. The flux is 
 commonly limestone, although other agents are also used. It is 
 introduced in consequence of the impurities remaining in the ore. It 
 combines with the silica and other prejudicial matter, and forms a slag 
 or cinder separated from the iron. A strong blast of air is introduced 
 through piping surrounded by water tuyeres (outer casings). Power- 
 ful blowing engines force the blast into furnace and through the 
 charge therein. The water circulating through the tuyeres serves to 
 cool the inlet where the heat becomes intense, and might cause 
 trouble by fusing the parts. At one time a cold blast was used, and 
 another of the most important modern improvements was the inven- 
 tion and use of the hot blast by Neilson of Dundyvan. By heating 
 the air before its admission into the furnace great efficiency and 
 economy of working were attained. Various forms of heating stoves 
 have been devised, and these are now usually fired by the escaping 
 blast furnace gases. 
 
266 "Verbal" Notes and Sketches 
 
 Pig-iron. 
 
 The proportions of fuel and flux are so far determined by the 
 nature of the ore used, and there are modifications of appliances and 
 methods according to varying circumstances and requirements. The 
 close tops and greater height of the furnaces have led to thinner walls 
 and iron casings. As the charge becomes affected by the intense 
 heat, chemical and other changes take place, impurities being taken 
 up by the flux, though some others partially remain, as sulphur, 
 phosphorus, and carbon. After these changes fusion speedily ensues, 
 and the molten iron falls to the bottom, the slag floating on the top, 
 while other waste elements escape in the form of gases. Once started, 
 a blast furnace may be kept in operation for years. At the bottom 
 of the furnace is an aperture called a tapping-hole, kept closed until 
 the melting of the iron is completed. A large bed of sand is formed 
 in front of the furnaces in which channels are made with smaller 
 furrows branching off from them. These are called sows and pigs 
 respectively, whence the term pig-iron. The tap-hole being opened, 
 the melted iron runs out like a stream of liquid fire, flows down the 
 large furrows into the smaller ones, where, on cooling, it assumes the 
 familiar form of the oblong bars called pig-iron. The cinder or slag 
 is drawn off over a dam at a higher level, independent of the iron. 
 
 The pig-iron thus produced is of different grades, the fracture dis- 
 closing divergencies of character and quality. The colour varies, 
 ranging from grey to white, and the degree of hardness varies corre- 
 spondingly. Grey is the softest, running through the mottled to the 
 whitest, which is also the hardest. The quality is distinguished by 
 numbers, beginning with No. i, and these numbers also indicate the 
 suitability of the iron for further uses, all not being alike adapted for 
 the same purposes. The grey iron is most suitable for foundry 
 purposes, the white for forging. 
 
 Castings. — We now arrive at the parting of the ways, so to speak 
 The pig (or cast) iron may be applied, broadly speaking, in two ways. 
 It may be employed for the producing of castings, or it may be con- 
 verted into malleable iron or steel. Although jarge and rough 
 castings might be made direct from the blast furnace, and malleable 
 iron direct from the ore, these methods have been discarded, as it is 
 more advantageous to make both indirectly from the pig-iron. 
 
 The grey or softer pig-iron, as has been said, is most suitable for 
 castings. But as there is great variety in the size, shape, intricacy, 
 and purpose of castings, ranging from, say, a boot protector to a large 
 steam-engine cylinder, mixture and manipulation of the different 
 brands of iron are often required. For example, the bottom of a pan 
 mill subject to constant grinding and heavy pressure, naturally 
 requires to be of very hard metal ; whereas, an ornamental article 
 showing design will require fluid and easily running metal. Again, 
 castings which have to be machined — that is, turned, planed, drilled. 
 
General Notes and Descriptions 
 
 267 
 
 k&c, cannot be cconon:iically treated if too hard, and yet generally 
 f-equire toughness and strength. 
 
 'he Foundry. — The castings are produced in the foundry, to which 
 the pig-iron is conveyed ; and there it first undergoes a process some- 
 what analogous to that already described. The iron, along with the 
 fuel and flux, is remelted in a furnace called a cupola, and drawn off 
 it a tap-hole, the slag being afterwards thrown down through an 
 iperture at bottom. Frequently scrap iron (old castings broken up) 
 IS used along with the pig-iron. Obviously the additional refining 
 jives purer and better metal, but all is regulated very much by the 
 )urpose for which the castings are required. The metal runs from 
 Pthe tap-hole into a large iron ladle lined internally with fire-clay, and 
 [for pouring the metal into the lesser moulds small hand ladles are used. 
 The castings may be made in sand or loam moulds. Patterns or 
 [models of the articles required have, mostly, to be made in the first 
 [instance, and may be of stucco, wood, or iron, but generally the last 
 [when many articles are required, as it stands tear and wear better, 
 [and lasts longer. The sand is enclosed in an iron frame or box, 
 made in halves and hinged ; and the patterns of the article required, 
 which may be simple or complicated and in one or more pieces, are 
 embedded in the sand so as to form an exact mould. The patterns 
 are then withdrawn and the box closed, an aperture being left for 
 pouring in the metal, and small holes pierced to allow the escape of 
 air and gases. When sufficiently cool the castings are removed from 
 the boxes and dressed — that is, cleaned and filed. 
 
 Loam is a mixture, such as sand, clay, and horse manure, faced 
 with blacking or coal dust, and built in a pit or brick-work. 
 Appliances called loam boards are used in forming the moulds, and 
 [the skill of the moulder is called into requisition in building these 
 together. For water and gas pipes, iron moulds coated with plumbago 
 [are now sometimes used. More expensive to begin with, they save 
 afterwards, seeing they are not destroyed at each casting like sand 
 [or loam moulds. 
 
 What are called chilled (hardened) castings are made in metal 
 ,or mixed metal and sand moulds, in which the melted iron cools 
 rapidly and becomes extremely hard. This does for shot, &c. Cast 
 iron is distinguished by its granular formation, which can be seen 
 on fracture, its brittleness, and its hardness. It cannot be welded or 
 riveted, and is not pliable. So-called malleable castings are of the 
 opposite kind from the chilled, and are soft and to a certain extent 
 pliable. For this process the articles are placed in powdered ha^-matite 
 ore or similar preparation, packed in chests, heated in a furnace for 
 several days, and allowed slowly to cool until annealed. 
 
 Malleable Iron. 
 
 For the manufacture of malleable or wrought iron a different 
 process is employed. Malleable iron, as the name implies, is ductile 
 
268 "Verbal" Notes and Sketches 
 
 and fibrous. It is softer than cast iron and can be bent, twisted, 
 welded, and riveted. The difference between it and cast iron is 
 principally due to the larger proportion of carbon in the latter. It 
 has been described as free from carbon, but this is hardly correct, 
 as usually it contains a very small percentage of that element. 
 
 Puddling Furnace. — The first step is to treat the pig-iron in a 
 puddling furnace. This is of the reverberatory type — that is, one 
 where the fuel and the iron do not come into contact as in the open 
 and closed hearth furnaces. As usual, the inner lining of the furnace 
 is of a refractory material encased in strong iron outer sheathing. 
 The bed or hearth is divided into two parts by a low wall or bridge, 
 the fuel being placed in one and the charge of pig-iron in the other. 
 The flame passes over the bridge against the roof, which is so shaped 
 as to reverberate or throw it down in a fierce heat upon the iron and 
 then pass on to the flue. The furnace may hold a charge of about 
 4 cwt. of metal, and is worked by two men, a fore and an under 
 hand. When partially heated the furnace is fettled — that is, plastered 
 with composition embodying oxide of iron in the form of haematite 
 made into paste with water, or else of slag from previous meltings, 
 which comes in cheaper. Lumps of metal are thrown in, the fire 
 is then raised, and by means of long iron bars (changed as required) 
 the puddlers, in turn, keep working or stirring and distributing the 
 metal. During melting the iron is decarbonised (divested of the 
 carbon remaining in the pig-iron) and various other impurities 
 removed. Before complete fusion the mass becomes of a pasty 
 consistency, and is well " rabbled " or distributed by the puddlers. 
 When melted it seethes and bubbles, and shortly afterwards begins 
 to thicken, the iron separating from the impurities unites in solid 
 pieces which gradually become welded together, while the waste 
 or slag is run off in liquid form. It will be obvious that the process 
 of puddling is a very exhausting one to the men engaged in it, and 
 means of accomplishing the required work by mechanical action have 
 been devised. These need not be described, as the object is the 
 same whether manual labour or machinery be the method employed. 
 Besides the mechanical contrivances for puddling, experiments have 
 been made in the opposite direction by constructing rotary furnaces 
 actuated by machinery. These have not, however, displaced the 
 stationary furnaces. 
 
 The mass of iron having combined, is now removed from the 
 furnace, and for convenience of handling is divided into parts or 
 balls, and at once taken to a steam hammer to be beaten. Thereafter 
 the balls can again be united and hammered into shape. During 
 these operations the waste or slag is being further pressed out. The 
 next stage is to convey the iron to the roughing or cogging mills 
 with rolls of large diameter through which it is passed, the openings 
 between the rolls being gradually reduced. The iron is thus con- 
 verted into slabs, while it is also being additionally cleansed. By 
 
General Notes and Descriptions 269 
 
 reheating and rcrolling the quality can be improved up to a certain 
 point, but beyond that harm results from burning, &c. The final 
 step is the passing of the wrought iron through the rolling-mills 
 with rollers having sections of the different forms required. These 
 mills are massive in construction, and driven by powerful steam- 
 engines. The billets are passed backwards and forwards through 
 the rolls — the mills being reversible — and the rollers brought closer 
 until the desired sizes and shapes are obtained. These are principally 
 sheets, plates, round, square, and flat bars, angles, and other sections. 
 
 The quality of the iron is denoted (after the puddled bars) as 
 common, best, best best, and treble, — the superior quality being the 
 result of the reheating and rolling of the previous grade. The 
 qualities of different works, however, vary. There are some special 
 brands — such as Lowmoor and the products of other Yorkshire 
 works — of a high class, where the results are dependent on special 
 methods and local advantages as regards fuel and ore. 
 
 Steel. 
 
 Steel is a material of valuable and unique properties. It may be 
 extremely hard, or soft enough to be bent, twisted, hammered, or 
 drawn out to the thinnest sheet or finest wire. It can be so hard 
 as to cut any other metal or material and to scratch glass, or it may 
 be elastic to a degree. 
 
 It has been described as a metal intermediate between cast and 
 wrought iron as to the carbon it contains. But this, correct enough 
 as far as it goes, is somewhat misleading, as it does not take all 
 considerations into account. According to the amount of carbon 
 it contains, steel is harder or softer. According, also, to the propor- 
 tion of carbon it contains, the tensile breaking strain and the limit 
 of elongation var}-. The tensile breaking strain will range from 
 20 to as much as 80 tons per square inch, or more if the steel be 
 wire-drawn. 
 
 Cementation Process. — The highest quality of steel is made 
 by what is termed the cementation process. The best puddled 
 wrought-iron bars, preferably Swedish charcoal iron, are used. The 
 cementing furnace is of fire-brick, circular or rectangular in form, 
 having a wide, conical top and dome-like chimney. The fireplace 
 is in the centre at the bottom, with door at each end for firing. 
 On each side, supported above it, are pots or chests, so arranged 
 that the flames pass underneath and all around, rising against the 
 arched top, which, as it becomes heated, radiates down on the pots. 
 These are perhaps 1 5 feet long or more, and 3 feet deep or thereby, 
 A manhole at each end permits of charging the pots or converters, 
 but these are closed during the working. A layer of charcoal is first 
 deposited on the bottom of the pots, then a layer of bars with spaces 
 between also filled with charcoal, and so on in alternate layers. 
 
270 "Verbal" Notes and Sketches 
 
 The charcoal is partly fresh and partly previously used. Then a 
 plaster of cement (used charcoal and ground waste) is applied to 
 the top, and the whole is sealed with clay to exclude air. The 
 charge will range from 12 to 18 tons, according to size of furnace, 1 
 and may even reach 30 tons. One or two of the bars are longer \ 
 than the others and project outside for testing purposes. The 
 furnace is heated for eight or ten days, when a testing-bar is with- 
 drawn and examined to see if the material has been sufficiently 
 carbonised. Afterwards the furnace is left for a day or two to cool 
 down gradually. It will be found that the carbon is not uniformly 
 distributed through the bars, but is greatest at the surface, decreasing 
 as the centre is reached. The skin is raised in blisters (blister steel). 
 If not intended to go through the further crucible process, the bars 
 are then sheared into short lengths, bound together in bundles, 
 powdered with mixture of clay or sand, heated to welding-point, 
 and then subjected, while in a plastic state, to rapid action of a ' 
 tilting-hammer or rolling-mill till welded. This gives what is called 
 single shear steel. By repeating the process double shear steel is 
 obtained, and so on. This shear steel is of cheaper description 
 than the crucible steel, and serves for shear blades, certain kinds 
 of knives, &c. 
 
 Crucibles. — For a finer steel under same process, to attain uni- 
 formity, the bars after being withdrawn from the furnace are remelted 
 and mixed. This is done in crucibles. What is called the melting- 
 house varies somewhat in arrangement, as light or heavy ingots are 
 to be produced. The melting furnaces form a series of rectangular 
 chambers, separated by thin brick partitions, the tops being level 
 with floor of house, while the fireplace and ashpit are at bottom, 
 accessible from underground passages running in front of them. 
 Each hole or chamber is lined with ground ganister (a refractory 
 siliceous rock), leaving an opening sufficient to hold two pots or 
 crucibles resting on stands placed over the fire-bars. Crucibles differ 
 in dimensions, but a common size is 18 inches high by 9 inches 
 diameter. They are made of a mixture principally of fire-clay, with 
 added coke dust, old ground pots, and for some purposes plumbago. 
 They have to be very carefully made, and are dried, annealed, and 
 fitted with lids before use. The first melting will take four or five 
 hours for complete fusion, but subsequent meltings about half that 
 time in consequence of the previous heat being maintained. The 
 molten steel is poured from the crucibles into ladles with tap-holes 
 for discharging into the ingot moulds, or for small moulds with hand 
 ladles. The crucibles in good condition are at once replaced in the 
 furnace for a second heat. Great care has to be exercised throughout 
 in order to secure sound ingots. It will be obvious that the specially 
 high class of iron used and the slow method makes this description 
 of steel costly, but on the other hand there is nothing that can take 
 its place. 
 
I 
 
 General Notes and Descriptions 271 
 
 Tempered Steel. — From the high class steel are made the various 
 tools for hand and machine use to operate on metal, wood, and stone, 
 also cutlery, surgical instruments, swords, springs of various kinds, 
 saws, &c. To render it suitable for these varied uses it has to be 
 tempered — a distinctive feature of steel. When heated and then 
 .suddenly cooled, and afterwards reheated to the given temperature 
 required, it becomes available for the particular service to which it 
 has to be applied. The cooling is usually effected by plunging in 
 water. But if hardened and tempered in oil a somewhat greater 
 toughness, more elastic limit, and tensile strength are the result. 
 Workmen have a simple means of ascertaining the temperature by 
 the colours which the steel assumes at the different stages of heating. 
 These may be described as follows : pale straw, straw, yellow, brown, 
 purple, bright blue, deep blue, according as the temperature increases. 
 
 Bessemer Process. — There were many purposes where a class of 
 steel, not necessarily possessing the properties of the crucible product, 
 would be of immense advantage, and this led to research and experi- 
 ment. On the assumption that steel was a material containing a 
 proportion of carbon intermediate between cast and wrought iron, the 
 inference followed that a mixture of these would give steel, and this 
 method was tried but without success. The fact overlooked was that 
 cast iron contained impurities (in particular sulphur and phosphorus) 
 in a degree sufficient to render it useless for steel making. There 
 was also a practical difficulty in regulating the exact proportion of 
 carbon necessary. The Bessemer process, however, accomplished 
 the purpose, supplanting in great measure the use of malleable iron 
 for many purposes, particularly rails and other railway material, 
 forgings, plates, and various sections for structural work. The first 
 step in success was by using selected pig-iron, containing very little 
 of the objectionable elements, and the addition of spiegeleisen also 
 exercised a purifying effect. It was found that by first eliminating 
 all the carbon and then adding the spiegeleisen (a particular pig- 
 iron containing a considerable and known amount of carbon) or 
 ferro-manganese in proper proportion, the difficulties were overcome. 
 Finally, Thomas and Gilchrist devised their method of lining the 
 converter with a refractory basic material containing lime and 
 magnesia. These agents having an affinity for phosphorus absorbed 
 this impurity, and thus the bulk of the impurities being removed, 
 ordinary pig-iron could be utilised. 
 
 The essential feature of the process is the forcing of a current 
 of air through melted pig-iron in a special vessel named the con- 
 verter. The original Bessemer method is called the acid process, 
 because of the converter being lined with siliceous (ganistcr) material. 
 
 The Bessemer converter is an iron vessel, and may contain from 
 5 to 15 tons, lined as usual with refractory material, the bottom 
 being perforated with holes through which a blast of air is conveyed. 
 It is mounted on axles which allow of its being swivelled round ; one 
 
272 - "Verbal" Notes and Sketches 
 
 of these being hollow is utih'sed to admit the blast. The converter 
 after being heated is brought to a horizontal position, giving access 
 to the mouth. Melted pig-iron is poured in, the blast turned on, and 
 the converter raised to its vertical position. The blast is sufficiently 
 strong to counteract the weight of the charge, so that the metal does 
 not run down through the perforations. The air is forced through 
 the molten metal, burning up the carbon, and a kind of fairy fountain 
 effect is set up by the flames, spray, and colour which ensue, while, 
 to paraphrase Tennyson, " The blast is roaring and blowing." The 
 near exhaustion of the carbon is indicated by the waning of the 
 flames. The converter is once more brought to the horizontal 
 position, while the melted spiegeleisen is added in the proportion 
 required to give the necessary amount of carbon, and then reversed. 
 The mixing of the metals causes at first a violent agitation. Alto- 
 gether about twenty minutes is occupied in converting, say, 10 tons 
 of haematite pig-iron into steel. The temperature at the close of the 
 blast is said to reach 3250'' Fahr. 
 
 It will be readily understood that the intense heat generated in 
 all these smelting operations, together with the corrosive action of 
 the slags, necessitates the use of materials for lining the different 
 furnaces capable of withstanding as far as possible the destructive 
 effect of these agents — hence the frequent allusions to refractory 
 linings. For the most part special deposits of fire-clay and of siliceous 
 or flinty rock ground to form ganister have been found best adapted 
 for the purpose. 
 
 Basic Process. — The distinctive feature of what is called the basic 
 process of producing the steel — as distinguished from the original 
 acid Bessemer process — is the substitution of a basic lining of 
 magnesian lime for the coating of the converter instead of the acid 
 ganister. As already noted, the basic material extracts the phosphorus 
 from the iron, which cannot be done by the ordinary process, and so 
 renders it possible to use Cleveland and other lower class iron in 
 the making of steel. With some modifications the processes and 
 appliances are, in general, similar to those already described. 
 
 The amount of slag produced in the basic process is much larger 
 than in the other, but is of a different character, and as it contains a 
 considerable proportion of calcium phosphates useful for fertilising 
 land, it is employed after suitable treatment for this purpose. Apart 
 from the capability of using the inferior iron by the basic method, 
 the large quantity of material which can be handled at a time, the 
 rapidity of the conversion, and the comparative absence of manual 
 labour combine to render the Bessemer process of steel making one 
 of the most important of the present day, and great quantities of 
 material are turned out for the purposes already named. 
 
 Siemens-Martin Process. — Another successful method largely in 
 use is the Siemens-Martin, by which a mild steel with a low percent- 
 
General Notes -and Descriptions 273 
 
 age of carbon, approximating to wrought iron, is obtained. A bath 
 of melted pig-iron of high quality is first made, and to this there is 
 gradually added wrought iron and steel scrap in small quantities at 
 a time. Impurities are removed during the melting, and the presence 
 of the scrap already refined by the previous puddling gives very good 
 results. Spiegeleisen is added to supply the desired amount of 
 carbon, as in the Bessemer process. The furnace employed is 
 generally a Siemens Regenerative Gas Furnace. 
 
 The roof and sides are of refractory silica or brickwork, and the 
 bed (of considerable depth) of sand of a like nature. There are 
 doors for introducing the charge and also for stirring and mixing. 
 Externally it is encased in iron plates. The regenerative chambers 
 are built underneath the furnace, with spaces between. The gas is 
 produced in separate furnaces, of which there are several patterns. 
 The gas and air necessary for combustion, ascending through one set 
 of regenerators, are admitted by separate valves through portholes 
 into the furnace hearth. The furnace having been already heated, 
 an intense heat and volume of flames soon ensue. The hot air and 
 gas enter at one end of furnace, and the flames and waste gas 
 pass out through ports at the other end down to the other set of 
 regenerators, and thence to chimney. There are means for reversing 
 this cycle, so that a constant heat is maintained. Different kinds of 
 gases are used, and in America natural gas is sometimes employed. 
 As much as 50 tons of metal can be treated at one operation, or 
 it may be only a few tons, according to the size of furnace. The 
 proportions of pig-iron and scrap vary according to conditions and 
 requirements ; and the melting of a lo-ton charge will occupy three 
 and a half to four hours. A small sample is ladled out to see if the 
 desired degree of decarbonisation (removal of the carbon) is reached, 
 then the spiegeleisen or ferro-manganese is added, and these quickly 
 melting, the tap-hole can be opened, and the steel flows out into a 
 large ladle with a stopper in bottom, and thence is discharged into 
 the moulds. In order to ensure soundness in the ingots several 
 devices are used, principal among these being the addition of some 
 alloy at the end of the melting and the compression of the steel whib 
 in the fluid state. 
 
 Siemens Process. — In the Siemens process, besides the pig-iron 
 and scrap used in the Siemens-Martin method, rich haematite ores 
 are introduced, and somewhat different chemical reactions take place, 
 but the working arrangements do not differ much, though longer 
 time is required for fusion. If pig-iron of a lower class with many 
 impurities be used, then the sand-bed of the furnace must be replaced 
 by a basic material, as in the Bessemer converter. 
 
 There are also some important alloys used in the manufacture 
 of steel. For instance, nickel alloyed with steel intensifies its hard- 
 ness, while it can be rolled or hammered to advantage. Harveyised 
 nickel steel is much used for armour-plates. Chromium is also used 
 
274 
 
 Verbal " Notes and Sketches 
 
 as an alloy. It imparts greater strength, toughness, and ductility. 
 It is employed in the production of armour-plates, and also of 
 projectiles, conferring on the latter the property of keeping intact 
 when striking steel plates at the highest velocity. In the making 
 of large and heavy forgings, whether in wrought iron or steel, besides 
 the steam hammers already alluded to, very powerful hydraulic 
 presses have been devised and come into use for shaping and 
 compressing. 
 
 It may be said that the great development of the machinery 
 and appliances for dealing with iron and steel in recent years, and 
 the developments in the treatment of these materials themselves, 
 together with the reciprocal interaction of these two factors, have 
 made possible advances unthought of even at the beginning of the 
 present generation. It is difficult to forecast what further progress 
 may be in store in the future. 
 
 Strength and Composition. — The following table gives the average 
 tensile and crushing strengths of Cast Iron, Wrought Iron, Mild Steel, 
 Nickel Steel, and Hard Steel, also the per cent, proportion of Carbon, 
 &c., in each. 
 
 
 
 
 
 Manganese, 
 
 
 Metal 
 
 Tensile 
 
 Crushing 
 
 Carbon. 
 
 Silicon, 
 
 Nickel. 
 
 
 Strength. 
 
 Strength. 
 
 
 Phosphorus, 
 Sulphur, «S:c. 
 
 
 
 Tons per Sq. In. 
 
 Tons per Sq. In. 
 
 Per cent. 
 
 Per cent. 
 
 Percent. 
 
 Cast Iron - 
 
 7 
 
 45 
 
 3-5 
 
 2-8 
 
 
 Wrought Iron 
 
 20 
 
 16 
 
 
 •3 
 
 
 Mild Steel - 
 
 28 to 30 
 
 22 
 
 •16 
 
 •6 
 
 
 Nickel Steel 
 
 40 
 
 
 •3 
 
 ■6 
 
 3-5 
 
 Hard Tool Steel 
 
 50 
 
 100 
 
 i-i 
 
 
 
 Alloys. 
 
 Alloy. 
 
 Tensile Strength. 
 
 Copper. 
 
 Zinc. 
 
 Tin. 
 
 Antimony. 
 
 
 Tons per Sq. In. 
 
 Per cent. 
 
 Per cent. 
 
 Per cent. 
 
 Per cent. 
 
 Brass 
 
 12 
 
 66 
 
 33 
 
 
 
 Naval Brass 
 
 27 
 
 62 
 
 36 
 
 I 
 
 
 Muntz Metal 
 
 22 
 
 60 
 
 40 
 
 
 
 Gun-metal 
 
 16 
 
 91 
 
 
 9 
 
 Phosphor. 
 
 Phosphor Bronze 
 
 16 
 
 92 
 
 
 7 
 
 •5 
 
 Antimony. 
 
 Babbit's White Metal 
 
 
 8-3 
 
 
 83-3 
 
 8-3 
 
 Lead. 
 
 Parson's White Metal 
 
 
 I 
 
 30-5 
 
 68 
 
 •5 
 
 Spelter for Brazing 
 
 
 50 
 
 50 
 
 
 
General Notes and Descriptions 
 
 275 
 
 Properties 
 
 Cast Iron 
 Wrought Iron 
 Mild Steel 
 Nickel Steel 
 Hard Steel 
 Brass 
 
 Naval Brass 
 Muntz Metal 
 Gun-metal 
 Phosphor Bronze 
 Babbit's White Metal 
 Parson's White Metal 
 
 of Metals and Alloys. 
 
 - Can be cast. 
 
 forged, welded. 
 
 forged, welded. 
 
 forged, tempered, cast. 
 
 forged, tempered, cast. 
 
 cast. 
 
 cast, rolled, forged (hot). 
 
 cast, rolled, forged (hot). 
 
 cast, rolled. 
 
 cast, rolled. 
 
 cast. 
 
 cast. 
 
 Composition of Steel. 
 
 The following extract from Greenwood's work on steel and iron 
 gives the average composition of various steels : — 
 
 
 Analyses 
 
 of Steel. 
 
 
 
 
 Soft 
 
 Siemens 
 
 Crucible 
 
 Hard 
 
 In 100 parts of 
 
 Siemens- 
 
 Steel 
 
 Steel for 
 
 Tool 
 
 
 Martin Steel. 
 
 Plates. 
 
 Forgings. 
 
 Steel. 
 
 Carbon - - - - 
 
 ■167 
 
 •21 
 
 •36 
 
 I-I44 
 
 Manganese - 
 
 •044 
 
 •36 
 
 •30 
 
 •104 
 
 Silicon - - - - 
 
 •023 
 
 ■047 
 
 •02 
 
 •166 
 
 Sulphur 
 
 ■013 
 
 •052 
 
 •02 
 
 
 Phosphorus - 
 
 •062 
 
 •035 
 
 •03 
 
 
 Copper - - - - 
 
 •076 
 
 
 trace 
 
 
 Mild steel can be forged and welded, but cannot be tempered. 
 Hard steel only can be tempered. 
 
 Composition of Manganese Bronze. 
 
 
 Per cent. 
 
 Copper 
 
 - 
 
 52 
 
 Zinc - . - - 
 
 - 
 
 46 
 
 Tin - - - - 
 
 - 
 
 I 
 
 Iron - - - - 
 
 - 
 
 - about 0-5 
 
 Aluminium 
 
 - 
 
 „ 0-5 
 
 Manganese 
 
 - 
 
 trace 
 
 Test for Steel. 
 
 The Board of Trade test for a piece of steel plate to be used for a 
 furnace or combustion chamber is as follows : — Strips of the metal 
 8 by 2 inches are heated to a cherry red, and afterwards plunged into 
 water of 80° temperature : the strips must then be able to stand being 
 bent over without fracture until the sides are parallel at a distance 
 equal to three thicknesses of the plate. 
 
276 
 
 Verbal " Notes and Sketches 
 
 Tempering Steel. 
 
 In tempering a piece of steel, as for example, a chisel, the tool is 
 first heated to a cherry red and the point of it dipped into water ; if 
 the metal be then rubbed with a piece of stone, the various colours 
 will appear as the heat travels along to the point. When the required 
 tint shows, the tool must be plunged into cold water and kept there 
 until cold, and the temper will be fixed. 
 
 The following are the colours and corresponding temperatures 
 required in tempering different articles : — 
 
 Article. 
 
 Colour, 
 
 Temperature. 
 
 Turning tools 
 Chipping chisels 
 Springs 
 
 Straw 
 Purple 
 Blue - 
 
 450° 
 530° 
 570° 
 
 Annealing. 
 
 In working or flanging a steel plate the smaller number of heats 
 the plate has to undergo the better, as the effect of repeated heating 
 of part of a plate is to strain the metal ; the necessary flanging should 
 therefore be done in one heat if at all possible. After the flanging is 
 done the plate should be annealed, that is, heated uniformly through- 
 out and allowed to cool down slowly, as this has the effect of taking 
 out the strain and bringing back most of the strength lost previously 
 by local heating. 
 
 Case-Hardening. 
 
 Case-hardening consists of putting a thin skin of steel on parts 
 made of iron by the addition of carbon, so that the surface of the 
 metal is hardened. 
 
 This is usually done by enclosing the iron parts to be case- 
 hardened in an air-tight box together with substances rich in carbon, 
 such as bones and horns of animals, or prussiate of potash, and the 
 box is then left in a furnace for a number of hours. 
 
 The heat causes carbon to deposit on the surface of the iron, and 
 thus changes it into steel. 
 
 After being withdrawn from the furnace the articles require to be 
 plunged into water. 
 
 Gear which only requires to be lightly case-hardened is usually 
 packed in finely ground bone, and heated for a few hours ; if a deeper 
 case-hardening effect is required, then the articles are packed up in 
 the boxes with coarser bone powder, and heated for ten hours or 
 more, but if a greater depth still of hardening is required, it is then 
 necessary to repack and again heat up, finally dipping in the cooling 
 water bath. For certain classes of work, wood charcoal is employed 
 instead of bone. 
 
General Notes and Descriptions 277 
 
 Brazing. 
 
 Brazing is hard soldering, and consists of the joining together of 
 parts made of copper or brass, such as, for example, a brass flange 
 to a copper pipe. 
 
 The pieces to be joined are first carefully cleaned, then fitted in 
 place and clamped together in the required position, and, after they 
 have been covered over with spelter (composed of one part copper 
 and one part zinc), heat is applied by means of a charcoal fire, and 
 the spelter runs into the spaces of the joint. Borax is sprinkled over 
 the parts as a flux to make the spelter run easil)-. After cooling, the 
 spelter sets hard and the parts are then firmly soldered together. 
 
 NOTE.-— Soft solder is made up of equal parts of tin and lead, resin or spirits 
 of salts being employed as a flux. 
 
 Welding. 
 
 In welding, two pieces of metal are joined by being first heated to 
 about 1600" P^ahr. (white heat) and then hammered together. 
 
 The ends to be joined require to be scarfed or tapered away at an 
 angle, and before putting the two surfaces together sand (if iron) or 
 borax (if steel) is sprinkled over them as a flux, and the hammering 
 proceeded with. It is important that the two pieces be heated to as 
 nearly the same temperature as possible before joining. 
 
 NOTE. — The flux (sand or borax) acts to clean the surfaces of the magnetic 
 oxide which forms on the heated surfaces, and which would otherwise prevent 
 perfect adhesion. 
 
 Strength of Materials. 
 
 Tensile strength of nickel steel, 34 tons per square inch. 
 
 I„ ,, boiler steel, 28 
 
 U „ ,, wrought iron, 20 
 
 '' „ ,, Muntz metal, 20 
 
 „ ,, brass, 12 
 
 i „ ,, copper, 12 
 
 f „ ,, cast iron, 7 
 
 NOTE.— Nickel steel is mild steel with about 3-2 per cent, of nickel added. 
 i 
 A 
 
 [Crushing Strengths. 
 
 Crushing strength of hard steel, 100 tons per square inch. 
 „ „ cast iron, 40 „ „ 
 
 „ „ wrought iron, 16 „ „ 
 
 Hoys. 
 
 An alloy is a combination of two or more metals. 
 
 Brass consists of about 2 parts of copper and i part of zinc, 
 
 Muntz Metal consists of about 3 parts of copper and 2 parts 
 of zinc. 
 
 White Metal consists of about 84 per cent, of tin, and the 
 remainder of copper and antimony. 
 
 NOTE.— White metal melts at about 600° Fahr. 
 
278 "Verbal" Notes and Sketches 
 
 Stresses on Various Parts. 
 
 Boilers. 
 
 On the stays the stress is tensile. On the shell plates the stress is 
 tensile. On the furnace the stress is compression. On the tubes the 
 stress is compression. On the stay tubes the stress is comp7-ession and 
 tensile. On the back tube plates the stress is compression. On the 
 combustion chamber dogs the stress is compression on top edge and 
 tensile on bottom edge. On the rivets the stress is shearing. 
 
 Engines. 
 
 On the shafting the stress is torsion, but the tail end shaft has also 
 a bending stress due to the propeller weight outside of the stern tube. 
 
 On the shafting from the thrust shaft aft there is an end com- 
 pressive stress going ahead, and a tensile stress going astern. 
 
 On the crank-shaft there are also bending and crushing stresses 
 combined with torsion. 
 
 For these reasons the tail shaft and shaft crank are usually made 
 a little larger in diameter than the tunnel shafting (about I inch). 
 
 Coupling bolts have a shearing stress. Crank webs and pump 
 levers have a bending stress. 
 
 Built Shafting. — Instead of shrinking the webs on to the shaft, some 
 engineering firms force them on by hydraulic pressure, the ram 
 exerting a load of anything from 100 to 125 tons. The holes in the 
 webs are bored out a few thousandths less in diameter than the pin 
 or shaft, and for a shaft of, sa)% 14 inches diameter, the difference 
 would amount to ^\^-^ inch, which is just under ^^ inch. 
 
 Strength of Shafting. 
 
 The strength of a solid shaft varies as the cube of its diameter, 
 therefore, the comparative strength of two shafts of, say, 8 inches 
 diameter and 10 inches diameter will be — 
 
 Diameter^ _ 10^ —,,. , 
 
 Diameter- ' y = Ratio of strengths = as i : 1-95. 
 
 A hollow shaft is stronger than a solid one of the same 
 sectional area, as, the diameter being greater, the leverage of the 
 power acting to twist it is less in proportion. 
 
 In addition to this, the removal of the central core of metal 
 reduces the risks of flaws, which often develop at the centre and then 
 extend outwards. Internal inspection for flaws is also to some 
 degree possible. 
 
 NOTE. — The torsional stress is o at the centre of a shaft, and increases from that 
 point out to the circumference ; the mean stress may therefore be taken as acting at a, 
 leverage of half of the shaft radius, or one-fourth of the shaft diameter. 
 
 The strength of a hollow shaft varies as 
 
 D = outer die 
 
 c/= inner diameter. 
 
 D^-d^ D = outer diameter. 
 
General Notes and Descriptions 279 
 
 A shaft will stand twice as much torsion stress as bending stress, 
 the Constant lor torsion being 5-1, and for bending io-3. 
 
 Rule (Torsion). — 
 
 5-1 X Load X Crank Length = Torsional Stress per square inch x Shafts 
 Therefore, 
 
 7 
 
 S-i X Load X Crank Lenci;h ^. , «, „ 
 
 ^T^ion^l-Stress = Diameter of Shaft, 
 
 S-I X Load X Crank Length ^ . . _, 
 °'' "Shaft DiameT^r^' = Torsional Stress. 
 
 NOTE.— For Torsional Stress the maximum Load may be taken as approxi- 
 mately equal to that on the piston, or, 
 
 Piston area x Pressure = Load. 
 
 Rule (Bending). — 
 
 10-2 X Load X Length = Bending Stress x Shaft'. 
 Twisting Moment (T.M.) = Crank Length x pounds load on pin. 
 Bending Moment (B.M.) = Length x pounds Load. 
 
 Example. — Calculate the bending stress per square inch on a 
 tail end shaft 12 inches diameter, distance from stern post to centre of 
 propeller boss 30 inches, weight of propeller 10 tons. Also express 
 the Bending Moment in inch-pounds. 
 
 Then, io-2x B.M. = tf3 x stress, 
 
 ^Q-^^,f-^=stress, 
 B.M. =30 inches x lo x 2240 = 672000 inch-pounds. 
 Stress = ^°'^ ^ 07200 __ ^^^ jijg pgj. gquare inch. 
 
 Power and Revolutions. 
 
 For a given power the higher the revolution speed the less the 
 diameter of shaft required, as the stress decreases with the speed. 
 
 To find the diameter of shaft necessary for a certain length of 
 crank and piston load (allowing 7000 lbs. as the safe torsional stress). 
 
 Rule. — 
 
 7 5.1 X Load X Crank Length ^ ^.^^^^^^ ^^ ^^^^^ 
 
 'x 7000 
 
 NOTE.— The above rule requires the extraction of the cube root, as shown by 
 the sign. 
 
 Torsional Stress on Shafts and Constant, 51. — To prove that the 
 strength of solid shafting depends on the cube of the diameter, and 
 to determine the origin of the Constant 5-1. 
 
 Explanation. — The shaft area is the shearing area resisting 
 
28o " Verbal " Notes and Sketches 
 
 torsion, and the mean leverage is equal to one-half of the shaft radius, 
 or one-fourth of the shaft diameter, as the stress is o at shaft centre and 
 
 ,. , c o -}- Radius , 
 
 maj^imum at the radius, therefore, — ^ = mean leverage, or, 
 
 which is the same thing, _i^^^^^-H£ = mean leverage. If, then, we find 
 
 4 
 the shaft area, and multiply by the stress (8000 lbs. per square inch 
 for steel) and by the mean leverage, we obtain the resistance to torsion 
 offered by the shaft metal. 
 
 Thus, Diameter^ x -7854 x Stress x ^^^^ ^_ Shearing Moment, 
 
 4 
 
 Diameter^x3lMl6^StressxD!^E?tir^ ^^ 
 
 4 4 
 
 Diameter- x 3-1416 x Stress x Diameter _ 
 4x4 
 
 Diameter^ x 3-1416 x Stress x Diameter _ 
 16 
 
 or, 
 or, 
 or, 
 
 Diameter^ x 3-i4i6 x Stress 
 16 
 
 Notice that Diameter- x Diameter = Diameter^, also that instead of 
 
 •7854 we may say ^iML^ which is equal to 7854; it will thus be seen 
 
 4 
 that the strength varies as the " Diameter cubed." 
 
 , , D'^x 3-1416 X Stress. 
 Agam, Load X crank leverage = ^^ ' 
 
 or, Load X crank leverage^ Diameter^ x Stress ; 
 
 16 
 
 LoadxcrankJeveragexi6^ Diameter^ x Stress ; 
 31416 
 or. Load x crank leverage x 5-1 = Diameter^ x Stress ; 
 
 so that in dividing by ^— ^ — , we invert it, and obtain -, which 
 
 16 3'i4io 
 
 gives 5-1 Constant for torsion, and as the resistance to bending stress 
 
 is only half of this, then 5-1x2= io-2 = Constant for bending stress. 
 
 Twisting Stresses and Tunnel Shaft Diameter. — The ratio of 
 piston travel to crank-pin travel per revolution is in the ratio of 
 2:3-1416, as during one revolution the piston travels through tzvo 
 strokes and the crank-pin through a circle equal in diameter to the 
 stroke. The crank-pin has therefore more travel than the piston, and, 
 by the principle of work, what is gained in travel is lost in pressure, 
 so that the average pressure on the crank-pin is less than the average 
 pressure on the piston in the ratio of 3-1416 : 2. 
 
General Notes and Descriptions 281 
 
 I Example. — The stroke is 4 feet and the total mean pressure on 
 
 the piston 36000 lbs. Find the mean pressure on the crank-pin. 
 
 Then, 4 x2x 36000=4 x 3-1416 xp, 
 
 and, p:=4 ^1^29^=22918 lbs. 
 
 4x3.1416 
 
 Mean Twisting Moment. 
 
 The mean twisting moment (T.M.) = Crank Length x Pounds 
 (LxP). 
 
 Therefore, T. M. - 24 inches x 22918 = 550072 inch -pounds. 
 
 For one minute the equation will read as follows : — 
 
 I. H. P. X 33000 X 12 inches = Crank Length x 2 x 3- 1416 x Pounds x Revs. 
 
 Therefore, IH.P. X33000X 12 ^ ^^^.^^j^ Length x Pounds (T. M. ). 
 
 2x3.i4i6x Revs. 
 
 Example. — I.H.P. 1,400, stroke 4 feet, and revolutions 62. Find 
 the mean T.M. 
 
 Then, 1400 x 33000 x 12=24 inches x 2 x 3'i4i6 x 62 x Pounds. 
 
 Therefore, T. M. = ^400x33000x12^3^ inch-pounds, 
 
 2x3.1416x62 ^"^ ^ 
 
 and, Pounds = 1423180 -r 24 inches = 59298 lbs. 
 
 Notice that the Twisting Moment in inch-pounds divided by the 
 crank length in inches brings out the pounds applied at end of crank. 
 
 Maximum T.M. 
 
 The foregoing only takes into account the mean or average T.M., 
 and to allow for the usual cut-off and the varying effects of the crank 
 angle a constant of about i-2 is usually employed, so that 
 
 Maximum T.M. = Mean T.M. x 1.2. 
 
 Shaft Diameter. 
 
 From the foregoing principles the required diameter of tunnel 
 shaft for a three-crank engine can be calculated as follows : — 
 
 C. 
 
 I.H.P. X 33000 X 12x5.1 X i.2=<f X2x3.i4i6x Revs, x Stress. 
 
 C 
 
 Therefore, d= 3 /l.H.P. x 33000 x 12 x 5.1 x 1.2 
 
 \' 2x3. 1416 X Revs. X Stress 
 
 Allowing a stress of 7,000 lbs. per square inch the shaft diameter 
 will be equal to 
 
 'V 
 
 1400 X 33000 X 12 X 5.1 X i-2 -io.y inches Diameter. 
 2x3-1416x62x7000 
 
2S2 " Verbal " Notes and Sketches 
 
 Board of Trade Rule for Tunnel Shafts.— 
 
 Shaft Diam - 3 / Crank Length x Absolute boiler pressure x L. P. ^ 
 
 cr 
 
 1295 X 
 
 (-feliO 
 
 The boiler pressure- 160 lbs. (gauge) and the cylinders 22 inches, 38 inches, 
 64 inches diameter. 
 
 Therefore, Shaft Diam. = y_i42ii75^i64!_ = ii inches (nearly). 
 
 V 1201; X / 2 + '*" \ 
 
 1295 X (^2 + ^^.^ 
 
 It will be noticed that the Board of Trade Rule brings out a 
 slightly larger shaft than that previously calculated, which, of course, 
 allows for a larger margin of safety. 
 
 Combined Twisting- and Bending Stresses. — As the crank-shaft is 
 subjected to a combined twisting and bending stress, both of which 
 require to be allowed for in estimating the size, the Board of Trade 
 Constant is mo in place of 1295: for tunnel shafts this gives a 
 larger diameter of shaft, which also holds good for the thrust length ; 
 but the propeller shaft requires to be still larger, as the Constant for 
 this length is 943. 
 
 Board of Trade Shaft Constants. 
 
 (For Engines with Three Cranks at 120°.) 
 
 Tunnel Shaft. 
 
 Crank and 
 Thrust Shafts. 
 
 Propeller 
 Shafts. 
 
 1295 
 
 IIIO 
 
 943 
 
 Constant 
 
 Lloyd's Rules for Shafting. 
 
 Triple Expansion Engines with Cranks at 120°. 
 
 (I. ) Diameter of tunnel shaftings (-038 x A + -009 x B + -002 x C + •0165 x S) x VP. 
 
 Where A=H.P. cylinder diameter. 
 
 B = M.P. cylinder diameter. 
 C=L. P. cylinder diameter. 
 S = Stroke in inches. 
 P= Boiler pressure (gauge). 
 
 (2.) Diameter of crank-shaft and of thrust shaft = diameter of tunnel shaftx — . 
 
 20 
 
 (3.) Diameter of propeller shaft = 
 
 diameter of tunnel shaft x f -63 + igg^jameterjofjpr^peller in inches \ 
 V diameter of tunnel shaft / 
 
 (with liner from end to end). 
 
 (4.) Diameter of propeller shaft = 
 
 diameter of tunnel shaft x (with two separate liners). 
 20 
 
 Example i. — Determine the required diameter of tunnel shaft, 
 thrust shaft, crank-shaft, and tail shaft (with continuous liner) 
 
General Notes and Descriptions 283 
 
 according to Lloyd's Rules for an engine with cylinders, 24, 40, 
 and 66 inches diameter. The stroke is 42 inches, and the boiler 
 pressure 190 lbs. The propeller diameter is 14 feet. 
 
 Tunnel shaft diameter = (-038 x 24 + -009x40 (-•002x66 (--0165 x 42) x Vi90 = 
 (•912 + -360 + -132 + -6930) X 5-74 = 2-0970 X 5-74 =12-03 inches. 
 Say, 12 J inches diameter. 
 Crank-shaft and thrust shaft diameter^ 12.125 x ^= { ^^•73jnches.^^Say^^^^^ 
 
 Propeller shaft diameter = 12-125 x | -63 + ^5^-^^-^ = 
 
 12-125 X ( '63+ ^^^^^ = 12-125 X (-63 + -4156) = 12-125 X 1-0456 = 12-68 inches. 
 Say, I2| inches diameter. 
 NOTE.— Vp means extract cube root of boiler pressure. 
 14 feet diameter = 168 inches. 
 
 Example 2. — Calculate the required diameter of tunnel shaft, 
 thrust shaft, crank-shaft, and propeller shaft for an engine with 
 cylinders of 27, 42, and y^ inches diameter, the stroke being 48 inches, 
 and the boiler pressure 180 lbs. per square inch. The diameter of 
 the propeller is 1 5 feet 6 inches, and the tail shaft is brass-lined from 
 end to end. 
 
 Then tunnel shaft diameter = (-038 x 27 + -009 x 42 + -002 x 73 + -0165 x 48) x Vi8o= 
 (1-026 + -378 + -1464- -792) x 5-64 = 2-342 X 5-64 = 13-2 inches. 
 Say, i3i inches diameter. 
 Crank-shaft and thrust shaft diameter = 13-25 x ?^= { ^3-9i^2 inches- ^.3^7-^^^ 
 
 Propeller shaft diameter = 
 
 Topc^f 6-24- -03 ^ i86 \ _ / 13-25 X (-63 + -421) = 13-25 X 1-051 = 13-92 inches, 
 ij ^5 X I 03 -t- J2-25 / ~ I Say, 14 mches diameter. 
 
 NOTE.— 15 feet 6 inches = i86 inches diameter of propeller. 
 
 Crank Angles. 
 
 Suppose we take five different engines, each to develop the same 
 I.H.P. No. I has one crank. No. 2 has two cranks at 90", No. 3 has 
 three cranks at 120", No. 4 has four cranks at 90°, and No. 5 has two 
 
 500 IHP 5001 HP 500I.HP SOO.IH.P 500 IMP 
 
 CONSTANT. CONSTANT CONSTAriT CONSTANT COCSTANT 
 
 T^O »04T mo lO^T 1^0 
 
 No. I.— Board of Trade Constants for Shafting. 
 
284 
 
 " Verbal " Notes and Sketches 
 
 cranks opposite each other ; then the accompanying sketch shows the 
 comparative diameter of shafts required in each case, and the 
 corresponding Board of Trade constants. 
 
 Observe that one crank and two cranks at 180^ require the same 
 diameter of shaft, the constant being the same. Also the two cranks 
 at right angles and the four cranks at right angles require the same 
 diameter of shaft. 
 
 The three-crank engine requires the smallest diameter of shaft, as 
 in this shaft arrangement of cranks the twisting stress on the shaft 
 is more evenly divided, and gives less variation than in any of the 
 other arrangements. 
 
 Flaws on Shafting. 
 
 Suppose that in a triple-expansion engine each cylinder develops 
 about 300 I.H.P. ; then between the H.P. crank-pin and the M.P. 
 crank-pin we have 300 horse-power on the shaft ; between the 
 M.P. crank-pin and the L.P. crank-pin we have 600 horse-power on 
 the shaft ; and between the L.P, crank-pin and the propeller we have 
 
 M P 
 
 LP 
 
 \C 
 
 VB 
 
 \A 
 
 HP 
 
 No. 2.— Flaws on Crank Shafting. 
 
 900 horse-power on the shaft, as all the power effectively developed 
 travels along the shafting aft to the propeller, each engine successively 
 adding its share. 
 
 If the M.P. shaft shows a flaw at A, link up the M.P. gear, and 
 this will reduce the stress on the weak part, as less horse-power will 
 now be developed in the H.P. engine, and more in proportion in the 
 M.P. ; therefore less will be transmitted through the weak part of 
 the shaft. 
 
 If a flaw shows at B on the M.P. shaft, if possible turn that shaft 
 end for end, as this will give only half the stress on the weak part. 
 Shutting in the M.P. gear would still further reduce the stress, as 
 more power will now be developed in the M.P. and less in the H.P. 
 
 For a flaw at C on the L.P. shaft, as before, turn the shaft end 
 for end, and link up the L.P. gear, on the same principle as before. 
 
 If the H.P. shaft is a duplicate of the other two, in the event of 
 flaws appearing in either the M.P. or L.P. shafts, change the H.P. 
 shaft for either one which has the flaw, instead of doing as above 
 

 General Notes and Descriptions 
 
 285 
 
 described, as the further forward the weak shaft is placed, the less 
 stress will there be on it. 
 
 Crank-Shaft Repairs. 
 
 The following description of crank-shaft repairs, supplied by John 
 M'Callum, Esq., are reprinted from the pages of Internatioiial Mat-inc 
 Engineering. 
 
 (i.) Loose Web. — The crank-shaft had been kept under observa- 
 tion, as a certain amount of slackness had been noticed between the 
 shaft and the web. Later on, when at sea, knocking was heard, and 
 it was located in the loose web. The repair was effected by drilling 
 a number of holes round the end of the shaft, as shown in Fig. i, and 
 fitting taper screw pins, if inches diameter, in each hole, and screwing 
 them up as tightly as a key with a good leverage would accomplish. 
 1 1 inches was the size of the largest screw tap on board. 
 
 Holes were drilled in the end of the shaft for about one-third of 
 its circumference, as shown in the figure ; the line of the holes being 
 arranged to leave |- inch of metal between them and the edge of the 
 shaft. The holes were drilled 6 inches deep, and screwed with taper 
 tap only. Each hole and pin was finished, and the pin screwed up as 
 
 No. 3.— Repair for Loose Crank Web, &c. 
 
 far as it would go before commencing the next. The line of screwed 
 pins swelled the shaft in the neighbourhood of the holes, and tightened 
 the shaft in its web sufficiently to carry the ship to her home port 
 without further trouble. When arrived in port a new shaft end was 
 fitted to the existing web. The possibility of this being done, and so 
 avoiding the expense of new shaft and web, had been foreseen when 
 
286 "Verbal" Notes and Sketches 
 
 the method described above was adopted. If plugs had been fitted 
 interlocking the shaft and web, apart from the fact of their HabiUty 
 to slack back when at work, a new shaft and a new web would have 
 been required on arrival home. 
 
 (2.) Flaw in Fillet. — When at sea, a flaw was noticed in the fillet 
 of the low-pressure crank-pin, which though slight at first developed 
 very rapidly, necessitating a very careful repair, or stoppage of the 
 ship would have been necessary. The flaw extended over about one- 
 third of the circumference of the after fillet and underneath the pin, 
 "crank on top," as shown at B in Fig. 3. In the writer's experience, 
 defects in crank-shafts, whether solid or built up, usually occur at this 
 point, and are mainly attributable to the faulty position of the thrust 
 block. Instead of the thrust being taken up by the shaft bearing, the 
 thrust block has to be adjusted, and a nip is thrown on the crank-pin 
 at the point B in Fig. 3, which usually results in a loose pin in 
 a built-uf) crank-shaft, or a flaw, as in this case, in a solid one. As 
 the runs between the ports were not long the engines were kept 
 running, but were well watched, while the engineers thought out 
 the difficult problem of repair and got the necessary appliances 
 ready. 
 
 The repair was effected by fitting a pin through the crank, as 
 shown at A in Fig. 3, a spare main-bearing bolt with collar and nut, 
 shown in Fig. 2, being employed for the purpose. Drills and ratchets 
 were got all ready before the engine was stopped, and drilling was 
 commenced from each end, a i|-inch hole being drilled through 
 both webs and crank-pin, the holes meeting in the centre. Coloured 
 labour being plentiful on the coast, the holes were got out in good 
 time. 
 
 After the holes were drilled the complete hole was bored by means 
 of the arrangement shown in Fig. 4. A boring bar E was fitted with 
 a pilot end H screwed into the boring bar, to save forging down and 
 to keep the bar true. The slot for the cutting tool was arranged, as 
 shown in F in Fig. 5, so that the body of the bar E took up the weight 
 of the cutting. Another slot was cut at G in the boring bar, and a 
 larger cutting tool was placed in it, which came into operation after 
 the cutter F. 
 
 Fig. 4 shows the arrangement of the boring bar. The plates D D 
 were used to support it, with the distance pieces C C, long bolts, as 
 shown, holding the whole thing together, and keeping the bar and the 
 boring central with the pin. The hole was recessed at each end to 
 receive the collar and nut, as shown in Fig. 3, and the nut was cut 
 down for the recess. 
 
 When the boring was finished the crank was well warmed by 
 means of a wood fire, the bolt tapped in with an anvil slung in ropes 
 for the purpose, the bolt end outside of the collar being left on until 
 the bolt was right in its place. The nut was then put on, hardened 
 up, and the bolt end riveted over it. The ship completed her charter, 
 
General Notes and Descriptions 
 
 287 
 
 and ran home with the repaired shaft. A new shaft had been sent 
 out, but it was not necessary to use it. 
 
 Repairs for Flawed or Broken Shafts. 
 
 Flaw on Crank Web. — Two iron or steel straps, say about 2 inches 
 
 thick, heated and shrunk on, then bolted as shown. 
 
 stra]> 
 
 No. 4.— Repair for Flaw in Crank Web. 
 
 The bolts should be as large as possible, for ordinary size of 
 shafting about 2J inches diameter, but larger than this if they can 
 be obtained. Coupling bolts would do very well in most cases. 
 
 Broken Crank-Pin. — Bore out the crank-pin to about one-third of 
 its diameter, and put in a repair-pin, a driving fit. A small locking- 
 
 El 
 
 Repair 
 
 No. 5.— Repair for Broken Crank Pin. 
 
 pin screwed half into crank-pin and half into repair-pin will keep it 
 in place. 
 
 Repair for Thrust Shaft — The collars to be bored or slotted out, 
 and bolts with thimbles fitted between the collars where the flaw or 
 
288 
 
 " Verbal " Notes and Sketches 
 
 ^ 
 
 3- 
 7i_r 
 
 Ikiifihles 
 
 No. 6.— Repair for Broken Thrust Shaft 
 
 break is situated. The thrust block rings next the broken part will 
 have to be removed. 
 
 Repair for Tunnel Shaft. — The shaft to be cut for keys of the 
 shape shown, the number of keys depending on the extent of the 
 
 clavw^ 
 
 No. 7.— Repair for Broken Tunnel Shaft. 
 
 flaw or crack, and the shaft clamped round over the keys and 
 securely bolted. 
 
 NOTE. — In the foregoing cases the revolutions will require to be reduced. 
 
 Notable Shaft Repair, — The following is a brief description of the 
 method adopted in repairing the broken tail end shaft of the steamer 
 " Fazilka," of the British India Steam Navigation Company, in the 
 Indian Ocean. 
 
 The binding of the shaft together by means of a set of bottom 
 end brasses applied as a clamp, and the further locking of the clamp 
 by steel pins driven in through the brass into the shaft, constitute 
 the most noteworthy and original points of this repair. 
 
 The tail end shaft gave way in the stern tube at two places, so 
 that a piece fully 3 feet 6 inches in length was detached, and in 
 breaking also broke through the stern tube. The engines were 
 promptly stopped and the stern of the ship afterwards tipped to 
 prevent the entrance of water to the tunnel while the work of repair 
 was being carried on. 
 
 A number of holes were first bored into the tube and the metal 
 broken away, so that a hole was made large enough to allow of 
 
General Notes and Descriptions 
 
 289 
 
 access to the shaft inside. The broken piece was removed and the 
 propeller shaft disconnected from the last tunnel length, and pushed 
 out aft until the broken ends touched. Two sets of bottom end 
 brasses were then taken and used as clamps to bind together the 
 two parts of the shaft, and to obtain one of these sets the H.P. engine 
 had to be disconnected. Plates of ^ inch thickness were fitted across 
 the two brasses top and bottom, and the bolts passed through to 
 more effectually support the broken parts, and, to allow of going 
 astern, holes, two of 2 inches diameter and two of 2^ inches diameter, 
 were bored into the shaft through the brasses, and steel pins driven 
 in. It will be noticed that a gap was left between the last tunnel 
 length of shafting and the tail end, owing to the bringing together 
 of the broken ends of the latter. To join these the after length of 
 the tunnel shaft (13^ inches diameter) was a^i ihrougJi, by first boring 
 round it twenty-two holes of about i inch diameter and cutting 
 between them. The flange was then brought aft and coupled to the 
 propeller shaft, and the cut parts of the tunnel shaft connected by 
 means of a " Thomson " patent coupling. To complete the job and 
 make the whole, as far as possible, one solid mass, molten metal was 
 run in to fill up the various spaces left by the ragged ends of the 
 broken shaft inside of the clamps, and when the engines were turned 
 round the parts were found to hold together satisfactorily enough to 
 allow of a reduced speed being easily maintained. 
 
 The work spent on repairing the shaft occupied about three 
 weeks' time, but this was mainly due to temporary failure of one 
 or two of the methods tried, which are not given here in detail. It 
 is sufficient to add that the "Fazilka" steamed safely, and without 
 assistance, into Colombo Harbour by the use of her M.P. and L.P. 
 engines, w^orking at a reduced boiler pressure. 
 
 "Thomson" Patent Coupling. 
 
 This coupling is specially designed for clamping up a broken 
 shaft, and forms the best means of repair. It consists of three 
 
 ©<§) 
 
 ' — - -i 
 
 ; U : L r : 
 
 • 1 ' i-ZI 
 
 #© 
 
 
 
 rmrm 
 
 I '"1 '1 1- - -' *• 
 
 rmrm 
 
 
 
 
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 LUJLUJ 
 
 UJJIUJ 
 
 
 N i K; 
 
 
 W0) 
 
 (Qm 
 
 No. 8— "Thomson" Patent Coupling. 
 
290 " Verbal " Notes and Sketches 
 
 pieces bolted together, and is so arranged that it may extend between 
 two lengths of shafting if required, an enlarged part of the coupling 
 allowing for the flanges. 
 
 Stopping of Engines. 
 
 Sudden stopping of the engines may be caused by the following : — 
 
 1. Slide valve loose on spindle, or spindle broken. 
 
 2. Stop valve seat lifted with valve. 
 
 3. Go-ahead eccentric broken, or loose on shaft. 
 
 4. Throttle valve turned round on its spindle. 
 
 If any steam connection on the H.P. is opened and steam blows 
 out, this proves that the stop valve and throttle valve are clear. 
 
 If the slide valve is loose on the spindle, the piston of that engine 
 will most likely stop on the top centre, as the valve will stick on the top, 
 and the bottom port remain full open to steam. If the steam be shut off 
 quickly, the noise of the valve dropping down would locate the trouble. 
 
 In the case of a valve slack on the spindle the following generally 
 holds good : — 
 
 1. If H.P. inside steam piston valve is slack on spindle, H.P, 
 
 engine will stop with piston on bottom centre. 
 
 2. If LP. or L.P. slide valve (or outside steam piston valve) is slack 
 
 on spindle, the corresponding engine will stop with piston 
 on top centre. 
 
 Failing the foregoing, testing, by means of the indicator cock con- 
 nections top and bottom, will usually locate the valve which has 
 slackened back. 
 
 GENERAL ENGINE BREAKDOWNS. 
 
 If the H.P. engine breaks down, take out the valve and disconnect 
 the engine, and work with the LP. and L.P. The pressure should be 
 reduced to about 100 lbs,, as the LP. cylinder is of larger diameter 
 the H.P., and therefore weaker. 
 
 If the LP. engine breaks down, take out the valve and disconnect 
 the engine (if the pumps are not worked off it). The steam will then 
 pass direct from the H.P. exhaust to the L.P. chest. The boiler 
 pressure may require to be reduced in this case, owing to the fact 
 that the steam in expanding down to the L.P. pressure does not drop 
 in temperature, as no work is done during this expansion, and to 
 obtain the same condenser vacuum the boiler pressure may, as stated, 
 require to be reduced. To develop the same I.H.P. the consumption 
 will be more, owing to the great difference of temperature existing 
 between admission and exhaust in the H.P. cylinder, and the con- 
 sequent excessive condensation of steam causing loss of heat. 
 
 NOTE.— In the foregoing cases it is advisable to leave in the valve spindle 
 to close up the gland. 
 
igoa 
 
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 S.S. 
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 I 
 
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 gear, eccentric straps, &c., leaving in the valve rod to close up the 
 gland, by lashing it to guide bracket. Then reduce the pressure 
 until the I. P. and L.P. gauges show, say, 4 or 5 lbs. higher than 
 formerly, and go on again. The H.P. piston, having steam in both 
 sides, will be balanced by the pressure. 
 
 It will be found that the pressure will drop considerably by the 
 free expansion of the steam in the H.P. cylinder. 
 
 21 
 
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 Osisuinptic 
 
 er breakdc 
 1,52, 
 
 
 k lashin 
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 Clear for 
 
 
 No. 8a,— Repair for Broken HP. Cylinder. 
 
General Notes and Descriptions 
 
 290^ 
 
 The following methods of repair in cases of breakdown require 
 the least time to carry out under conditions of urgency, and where 
 economy is of secondary importance. 
 
 I. H.P. Cylinder Broken Beyond Repair. 
 
 The sketch (No. Sa) illustrates the best method of repair which 
 requires the least time in getting under way again. 
 
 Remove broken parts of cylinder, also piston, and gear as required, 
 then draw H.P. piston valve and remove rings of same. Next expand 
 out the rings by inserting liners at the cut portion, and drive them 
 into the casing opposite the ports, taking care that the cut in the 
 rings is in line with the bridge metal of the ports. To prevent 
 the rings from being blown out of position, fit plates on a long 
 screwed bar as shown, with nuts top and bottom of the rings, 
 securing the bar by washers, plates, and nuts at top and bottom 
 of the valve casing. 
 
 The pressure should be reduced from, say, 180 lbs. to iio or 
 120 lbs. 
 
 This method of repair was carried out very successfully by Chief 
 Engineer D. M'Culloch and the engine room staff of the S.S. 
 "Numidian" of the Allan Line in August 191 1, the time occupied 
 on the work being 26\ hours. 
 
 The consumption, speed, and pressures before and after the 
 breakdown in the case of the " Numidian " were as follows : — 
 
 
 Before Breakdown. 
 
 After Breakdown. 
 
 Boiler steam 
 
 Consumption 
 
 Speed - - - - 
 
 160 lbs. 
 
 56 tons. 
 
 i3"5 knots. 
 
 100 lbs. 
 
 48 tons. 
 
 10-5 to II knots 
 
 After breakdown the LP. steam was 45 lbs., L.P. steam 7 lbs., 
 and the revs. 52. The vessel afterwards steamed over 3300 miles 
 as repaired without trouble of any kind developing. 
 
 2. H.P. Piston Valve Broken Beyond Repair. 
 
 In this case merely draw the valve, and disconnect the valve 
 gear, eccentric straps, &c., leaving in the valve rod to close up the 
 gland, by lashing it to guide bracket. Then reduce the pressure 
 until the LP. and L.P. gauges show, say, 4 or 5 lbs. higher than 
 formerly, and go on again. The H.P. piston, having steam in both 
 sides, will be balanced by the pressure. 
 
 It will be found that the pressure will drop considerably by the 
 free expansion of the steam in the H,P, cylinder. 
 
290 
 
 pieces 
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 Stopp 
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 I. 
 
 2. 
 
 3- 
 4- 
 
 If 
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 If 
 
 will m 
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 Fa 
 
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 po6t 
 
 ^ 
 
 If 
 
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 pass 
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 require LU UC 1C<JLH_<-V4. aw ^■^ , ^.^^ tm- oa.in<^ i.ii.j. . mv^ «„wnouiinJi.i\-<ir 
 
 will be more, owing to the great difference of temperature existing 
 between admission and exhaust in the H.P. cylinder, and the con- 
 sequent excessive condensation of steam causing loss of heat. 
 
 NOTE.— In the foregoing cases it is advisable to leave in the valve spindle 
 to close up the gland. 
 
General Notes and Descriptions 
 
 290^ 
 
 The following methods of repair in cases of breakdown require 
 the least time to carry out under conditions of urgency, and where 
 economy is of secondary importance. 
 
 I. H.P. Cylinder Broken Beyond Repair. 
 
 The sketch (No. Sa) illustrates the best method of repair which 
 requires the least time in getting under way again. 
 
 Remove broken parts of cylinder, also piston, and gear as required, 
 then draw H.P. piston valve and remove rings of same. Next expand 
 out the rings by inserting liners at the cut portion, and drive them 
 into the casing opposite the ports, taking care that the cut in the 
 rings is in line with the bridge metal of the ports. To prevent 
 the rings from being blown out of position, fit plates on a long 
 screwed bar as shown, with nuts top and bottom of the rings, 
 securing the bar by washers, plates, and nuts at top and bottom 
 of the valve casing. 
 
 The pressure should be reduced from, say, 180 lbs. to no or 
 120 lbs. 
 
 This method of repair was carried out very successfully by Chief 
 Engineer D. M'Culloch and the engine room staff of the S.S. 
 "Numidian" of the Allan Line in August 191 1, the time occupied 
 on the work being 26h hours. 
 
 The consumption, speed, and pressures before and after the 
 breakdown in the case of the " Numidian " were as follows : — 
 
 
 Before Breakdown. 
 
 After Breakdown. 
 
 Boiler steam 
 
 Consumption 
 
 Speed - - - - 
 
 160 lbs. 
 
 56 tons. 
 
 1 3*5 knots. 
 
 100 lbs. 
 
 48 tons. 
 
 10-5 to II knots 
 
 After breakdown the LP. steam was 45 lbs., L.P. steam 7 lbs., 
 and the revs. 52. The vessel afterwards steamed over 3300 miles 
 as repaired without trouble of any kind developing. 
 
 2. H.P. Piston Valve Broken Beyond Repair. 
 
 In this case merely draw the valve, and disconnect the valve 
 gear, eccentric straps, &c., leaving in the valve rod to close up the 
 gland, by lashing it to guide bracket. Then reduce the pressure 
 until the LP. and L.P. gauges show, say, 4 or 5 lbs. higher than 
 formerly, and go on again. The H.P. piston, having steam in both 
 sides, will be balanced by the pressure. 
 
 It will be found that the pressure will drop considerably by the 
 free expansion of the steam in the H.P. cylinder. 
 
2(^Qb "Verbal" Notes and Sketches 
 
 3. LP. Cylinder Cover Broken Beyond Repair. 
 
 Remove broken parts of cover, draw valve, and disconnect valve 
 gear, then close up ports by means of wooden plugs and cement. Also 
 remove piston rings to eliminate pull on piston due to vacuum 
 formed on under side during up stroke. 
 
 Reduce boiler pressure if found necessary and go on again. 
 
 4. H.P., I. P., or L.P. Piston Broken Beyond Repair. 
 
 Take off cylinder cover and remove piston, then screw down 
 cover again and go on, leaving the valve working as before. Reduce 
 the boiler pressure as the case requires. 
 
 Note. — The steam will enter the cylinder and exhaust out of it 
 again as previously. 
 
 ^ Remarks. — In most of the foregoing examples it would be found 
 that after repair the speed, power, and consumption would be reduced, 
 but that the consumption per I.H.P. per hour would be increased, 
 although in many cases the total consumption also rises. In the case 
 of the H.P. cylinder being cut out it would be advisable to open out 
 the LP. link to gain power by carrying steam later on the stroke of 
 that engine which is now virtually the H.P. It miay also be found 
 necessary to line up the slide valves to improve handling of the 
 engines by increasing the bottom lead. 
 
 In all cases, when steam is allowed to enter a cylinder freely as 
 described in No. 4, a certain amount of loss by condensation must 
 be expected. This loss is, of course, much reduced if the ports are 
 blanked off and the cylinder cut out altogether, which should be done 
 if the circumstances allow. 
 
 ENGINE TESTING. 
 I. To Test if Guides are Parallel to Piston Rod Line. 
 
 {With all Gear in Position^ 
 
 First draw out gland and remove packing, then place engine on top 
 centre, and see by caliper or gauge measurements that rod is exactly 
 fair in stuffing box, also test rod for fairness by means of a steel 
 straight-edge. Next, by a surface gauge or a stiff wire shaped into a 
 gauge take distance from guide face surface at top to a mark made on 
 piston rod (see sketch). Place engine on bottom and again test rod 
 for fairness in stuffing box by caliper measurements, and with gauge 
 measure distance from guide face surface at bottom to same mark on 
 piston rod : if the two measurements agree the rod is proved to be 
 working fair in the cylinder, and the guides proved to be parallel to 
 the rod. 
 

No. 8b.— Method of Testing if Guides are Parallel to Piston Rod. 
 
General Notes and Descriptions 
 
 290^ 
 
 Note. — As the guides are closer together at top than at bottom 
 when cold (about yoSir" or so) it is advisable to make the test before 
 the engines are cooled down )therwise due allowance requires to be 
 made for the difference mentioned. If on testing the rod in stuffing 
 box it is found not to be in dead centre, then the rod and piston will 
 not be working truly in the cylinder bore, and of course the other 
 test will then be unnecessary. 
 
 No. 8c.— Method of Locating Centre of Piston Rod 
 between Guides. 
 
 The sketch (No. 8^) shows another method of finding a centre from 
 which to test the fairness of the guides to the piston rod line. By 
 means of the squares shown the centre of the piston rod can be 
 exactly located as indicated by the mark. If now a wire is fixed to, 
 say, a small plate bolted on the gland flange, and is then led down 
 to the shaft centre, this line can be used as a test for the guide face 
 setting, or piston rod trueness of line. 
 
 2. To Test if Guides are Parallel to Shaft Centre Line. 
 
 Turn the crank up to near the top centre and place a long steel 
 straight-edge diagonally across the guide face (sketch No. Sd), with the 
 lower end lying forward, and with a gauge measure the distance from 
 the straignt-edge to the crank pin centre forward : next slope the 
 straight-edge at the opposite angle on the guide face with the lower 
 end lying aft, and with the gauge measure the distance between 
 straight-edge and the crank pin centre aft : if the two measurements 
 agree the shaft line (assuming, of course, that the crank pin centre is 
 exactly parallel to the shaft centre) and guides are fair to each other ; 
 if not, the guides will require to be lined up to correspond. 
 
 3. To Test for Wear of Crosshead Shoes. 
 
 This can g-^nerally be done by means of feelers placed between 
 the crosshead shoe and the guide face at top and bottom positions of 
 
'i^(V page 2901 . 
 
 I 
 
General Notes and Descriptions 
 
 290^ 
 
 Note. — As the guides are closer together at top than at bottom 
 when cold (about j'^^rs" or so) it is advisable to make the test before 
 the engines are cooled down )therwise due allowance requires to be 
 made for the difference mentioned. If on testing the rod in stuffing 
 box it is found not to be in dead centre, then the rod and piston will 
 not be working truly in the cylinder bore, and of course the other 
 test will then be unnecessary. 
 
 No. 8c.— Method of Locating Centre of Piston Rod 
 between Guides. 
 
 The sketch (No. 8^) shows another method of finding a centre from 
 which to test the fairness of the guides to the piston rod line. By 
 means of the squares shown the centre of the piston rod can be 
 exactly located as indicated by the mark. If now a wire is fixed to, 
 say, a small plate bolted on the gland flange, and is then led down 
 to the shaft centre, this line can be used as a test for the guide face 
 setting, or piston rod trueness of line. 
 
 2. To Test if Guides are Parallel to Shaft Centre Line. 
 
 Turn the crank up to near the top centre and place a long steel 
 straight-edge diagonally across the guide face (sketch No. S(f), with the 
 lower end lying forward, and with a gauge measure the distance from 
 the straignt-edge to the crank pin centre forward : next slope the 
 straight-edge at the opposite angle on the guide face with the lower 
 end lying aft, and wiih the gauge measure the distance between 
 straight-edge and the crank pin centre aft : if the two measurements 
 agree the shaft line (assuming, of course, that the crank pin centre is 
 exactly parallel to the shaft centre) and guides are fair to each other ; 
 if not, the guides will require to be lined up to correspond. 
 
 3. To Test for Wear of Crosshead Shoes. 
 
 This can generally be done by means of feelers placed between 
 the crosshead shoe and the guide face at top and bottom positions of 
 
2^od 
 
 Verbal " Notes and Sketches 
 
 crosshead travel. Due allowance must be made for the difference in 
 distance between the guide faces top and bottom if the engines are 
 cooled down when testing, and it is also necessary to be sure that to 
 begin with the guides are parallel to the rod as described in test No. i. 
 The shoes can then be lined up as required. 
 
 4. To Test if Cylinder Line is at Right Angles to Shaft 
 Centre Line 
 
 No. 8e.— Method of Testing Setting of Shaft Line and 
 Cylinder Line. 
 
 To test if the centre line of the cylinders is exactly at right angles 
 to the centre line of the shaft, slacken back bottom ends, place crank 
 on top, and measure the distance between the butt of the connecting 
 rod and the crank cheek, as shown at B ; now place crank on bottom 
 centre and again measure between butt of rod and crank ; and the 
 two distances will be the same, if the cylinders and shaft centre lines 
 are set fair (at 90° to each other). 
 
--^ 
 
 ''i.OUK' t 
 
 2 3LG WJU-'/'T- iO 
 
 J 
 
 R^j^jiu^ A--.vity.-.ia;(^5-/- v'i«>!"as^«?r(!''- ■''vv»:ys»W'* 
 
 No. 9. — Bucket Air Pump. 
 
No. 8d.— Method of Testing if Guides are Parallel to 
 Shaft Centre Line. 
 
 I 7;. /,«.■ piigr 2<P'<- 
 
General Notes and Descriptions 
 
 291 
 
 Pumps. 
 
 The suction valve of a feed pump should be placed low down on 
 
 the barrel, and the delivery valve as high u}) as possible. This 
 
 arrangement allows of better working when tiie feed-water tempera- 
 
 [ ture increases, as the air or vapour will rise clear of the pump suction, 
 
 I and allow of a better vacuum being formed. 
 
 I Most patent feed donkey pumps are not fitted with relief valves, 
 the reason being that should anything occur to choke the delivery 
 l^alves, the pump would stop working by over-pressure on the water 
 isjde. 
 
 With feed pumps worked off the main engines the case is different 
 "or if, say, the delivery valve seat rises up with the valve, the pumps 
 would of course still go on working, and unless a relief valve is fitted, 
 the chest or connections would be damaged. 
 
 The feed relief valve should be placed on the pump chest between 
 the suction and delivery valves, so that, should the delivery valve 
 seat lift up with the valve, the relief will act and prevent damage to 
 the chest. If the check valve on the boiler stuck or was left shut, 
 the relief valve would also act and save the feed pipe from bursting. 
 
 In an ordinary feed pump, it should be noted that, with the chest 
 cover off, the top of the suction valve is alwaj'S open to the pump 
 plunger, and the bottom of the delivery valve is open to the plunger. 
 
 A Plunger pump has suction and delivery valves, and is a single- 
 acting force pump. 
 
 No. 9.— Bucket Air Pump. 
 

 
 --; ■"» v,..v,v,i^, do oiivjuii at u , iiuw piace crank on bottom 
 
 centre and again measure between butt of rod and crank ; and the 
 two distances will be the same, if the cylinders and shaft centre lines 
 are set fair (at 90° to each other). 
 
General Notes and Descriptions 
 
 291 
 
 Pumps. 
 
 The suction valve of a feed pump should be placed low down on 
 the barrel, and the delivery valve as high u[) as possible. This 
 arrangement allows of better working when the feed-water tempera- 
 ture increases, as the air or vapour will rise clear of the pump suction, 
 and allow of a better vacuum being formed. 
 
 Most patent feed donkey pumps are not fitted with relief valves, 
 the reason being that should anything occur to choke the delivery 
 valves, the pump would stop working by over-pressure on the water 
 side. 
 
 With feed pumps worked off the main engines the case is different 
 for if, say, the delivery valve seat rises up with the valve, the pumps 
 would of course still go on working, and unless a relief valve is fitted, 
 the chest or connections would be damaged. 
 
 The feed relief valve should be placed on the pump chest between 
 the suction and delivery valves, so that, should the delivery valve 
 seat lift up with the valve, the relief will act and prevent damage to 
 the chest. If the check valve on the boiler stuck or was left shut, 
 the relief valve would also act and save the feed pipe from bursting. 
 
 In an ordinary feed pump, it should be noted that, with the chest 
 cover off, the top of the suction valve is always open to the pump 
 plunger, and the bottom of the delivery valve is open to the plunger. 
 
 A Plunger pump has suction and delivery valves, and is a single- 
 acting force pump. 
 
 No. 9.— Bucket Air Pump. 
 
292 
 
 *' Verbal " Notes and Sketches 
 
 A Bucket pump has foot, bucket and head valves, and is a single-acting 
 lift pump. 
 
 Broken or leaky foot valves do not, in most cases, affect the vacuum, as 
 the pump is placed much lower down in position than the bottom of the 
 condenser, but the foot valves act to control the action of the pump and 
 induce more re<^ular flow. Broken or leaky bucket valves affect the vacuum 
 most, and broken or leaky head valves next. 
 
 The Edwards Patent Air Pump. 
 
 In the Edwards air pump, as will be seen in the sectional illustration, 
 foot and bucket valves are dispensed with ; the water flows continuously 
 
 by gravity into the base of the 
 pump, and being dealt with 
 mechanically by the conical 
 bucket working in connection 
 with a base of similar shape, 
 is projected silently and without 
 shock at a high velocity through 
 the ports into the barrel. 
 
 No. 10. — Edwards Air Pump. 
 
 Packing for Gland of Edwards Air Pump. 
 
 1. At bottom of gland place two rings of 
 soft packing of, say, hemp or cotton, which 
 should be occasionally soaked in hot tallow 
 with graphite. 
 
 2. Above this fit in a solid white metal 
 ring with grooves turned in the bore for water 
 packing. 
 
 3. Above this ring finally place a flat ring 
 of rather stiff soft packing. 
 
 When running see that a supply of fresh 
 water is kept on top of gland to fill up the 
 grooves of the middle packing ring. 
 
 As soon as the ports open, 
 there are clear inlets for the 
 admission of the air, and the 
 water is immediately afterwards 
 injected, thereby tending to 
 compress the air in the barrel 
 and carry in more air with it. 
 
 Another important feature of 
 the Edwards pump is that the 
 top clearance is reduced to a 
 minimum. Before any air pump 
 can discharge, the pressure in 
 the pump must exceed that of 
 the atmosphere, and thus all air 
 remaining in the pump is com- 
 pressed. As soon, however, as 
 the bucket descends, and the 
 pressure is reduced, the air in 
 the clearance water is given off, 
 and expanding, occupies space 
 
General Notes and Descriptions 
 
 293 
 
 in the pump which should be available for a fresh supply from the 
 condenser, consequently the smaller the top clearance the more 
 efficient is the pump. 
 
 The practical advantages of the Edwards pump are numerous ; 
 there being no foot and bucket valves, the risk of breakdown and 
 stoppage through the failure of valves, which cannot be .examined 
 while the pump is at work, is eliminated, and there being only one 
 set of valves instead of three sets, the cost of maintenance anc-l the 
 time necessary for overhauling are reduced to a minimum. 
 
 By means of the door at the top of the pump the only valves used 
 can be readily examined, and if necessary can, in some cases, be 
 renewed while the engines are running, without loss of water or 
 vacuum. 
 
 DEUVERV 
 
 SUCTION 
 
 DELIVERY 
 
 SUCTION 
 
 INJECTION 
 
 No. II.— Double-acting Circulating Pump. 
 
 A Piston pump has suction and delivery valves at either end, and 
 is a double-acting pump. On the up stroke the bottom suction and top 
 delivery valves are open, and on the down stroke the top suction and 
 bottom delivery valves are open. Air-valves are usually fitted to 
 either end of the pump to admit air to allow of cushioning of the 
 water. 
 
 A Centrifugal pump, as the name implies, works from the centre, 
 and consists of a cast-iron chamber containing hollow vanes keyed to 
 a spindle ; a small engine coupled direct to the spindle rotates the 
 vanes, and the water entering, by suitable passages, the pump casing 
 at the centre, where the vacuum is created by the rapid vane rotation, 
 travels through the hollow vanes and is delivered tangentially at the 
 circumference of the vane circle: thus peripheral force is converted 
 into pressure head. This type of pump has no valves. 
 
 The usual driving speed of the pump is from 180 to 220 revolu- 
 
294 " Verbal " Notes and Sketches 
 
 tions per minute. If by mistake the engine is started to run in the 
 wrong direction, the water will merely be churned by the impeller, 
 and no effective discharge will take place. Sometimes a steam pipe 
 and cock is fitted on the pump chamber to assist in starting by blowing 
 through a jet of steam, which, on condensing, produces a partial 
 vacuum. In place of this, the pump may require to be first " primed," 
 that is, filled up with water ; the air escaping meantime by a small 
 air-cock on the top. In ordinary practice, however, neither of the 
 above aids to starting are required, as the position of the pump being 
 lower than the sea level, the water flows by the force of gravity into 
 the pump chamber, the air being allowed to escape by the small cock 
 fitted on top of the pump casing. This type of pump is of low dis- 
 charge pressure and would not be suitable for, say, boiler feeding, 
 unless two or more pumps of the same type were coupled up " in 
 series " (as in coal mine practice), which arrangement would result in 
 increase of water pressure. 
 
 Breakdown of Pumps. 
 
 If the air pump breaks down, feed the boilers by " Weir's " pump, 
 which usually has a suction direct from the condenser. 
 
 If no such connection is fitted, remove the air pump bucket and 
 valves, leave on the cover and rod, close the hot-well overflow pipe, 
 and allow the water in the condenser to drain into the hot-well. Draw 
 the feed from there by the main feed pumps or the donkey pump. 
 The vacuum will of course go back in this case, and most likely 
 disappear altogether. 
 
 If the circulating pump breaks down, put on the ballast donkey 
 to the condenser for circulating ; if it is not suitable for this, then the 
 engines must be worked jet condensing. 
 
 To effect this draw a number of the condenser tubes, and open 
 up the air pump discharge valve ; also when under weigh again take 
 the boiler density oftener, as the feed will be chiefly salt water. 
 
 To find number of tubes to draw : — 
 
 Injection pipe diameter'^ .t v r a. i. 
 
 f\ ' . ~r — -T-. r—o= Number of tubes. 
 
 Condenser tube diameter^ 
 
 Loss of Vacuum. 
 
 Vacuum may be lost through the following causes : — 
 
 1. Head or bucket valves of air pump broken. 
 
 2. Valves of circulating pump broken, or injection choked. 
 
 3. Division plate in condenser door carried away. 
 
 4. Leaky L.P. gland. 
 
 To find the probable cause of the vacuum going back, feel the 
 temperature of both ends of the condenser. If both ends are cold, 
 broken air pump valves are the cause, or leaky L.P. gland. If both 
 
No. 13.— Closed Type Air 
 Vessel. 
 
 No. 14.— Open Type 
 Air Vessel. 
 
No. 12.— Centrifugal Type Circulating: Pump. 
 
 t, lulet from main injection. 
 
 2, Water Sow to each side of pump. 
 
 3, Water inlet to pump at centre. 
 
 DATA. __ 
 
 I inches of suction or delivery pipe= / I-H.P . 
 V 78 
 
 4, Vacuum position. 
 
 5, Delivery at periphery of pump. 
 
 6, Driving shaft of engine. 
 
 Diameter i 
 
 i:04S 
 
 •7854 
 
 NOTE.— Allow -045 square inch of pipe area per l.H.P. 
 Diameter of impeller = Diameter of pipe x 2-5. 
 Diameter of inlet opening at centre= Diameter of pipexi-l. 
 Example. — Determine the diameter of circulating pump suction and delivery pipe, the diameter of the impeller, and the diameiei 
 oi inlet opening at pump centre for an engine of 1800 l.H.P. 
 
 Then, Diameter of circulating pipe= f^l 
 
 and, Diameter of impeller =i( 
 
 1800 X -045 -- JO 
 
 ■7854 
 2-5=25 inches, 
 Diameter of inlet at centre=ioxM = ii inches. 
 
 
 ( To fme pa^e 294. 
 
General Notes and Descriptions 
 
 295 
 
 ends are warm, either broken circulating pump valves or choked injec- 
 tion valve is the cause. If one end is cold and the other end warm, 
 the division plate in the condenser is most likely carried awa)-. 
 
 NOTE. — 24 inches of vacuum means that the air pump has drawn 12 lbs. of 
 air pressure out of the condenser, leaving 3 lbs. absolute back pressure on the 
 L. P. piston. 
 
 Pet Valves. 
 
 On feed or bilge pumps the pet valve is usually placed between 
 the suction and delivery valves. 
 
 On double-acting circulating pumps a pet valve is placed on the 
 suction side of the pump at both ends. 
 
 On air pumps the pet valve is placed high up on the pump 
 chamber, just under the head valve, so that the air drawn in for 
 cushioning the water will not affect the vacuum under the bucket. 
 Many air pumps have no pet valves fitted. 
 
 On horizontal double-acting piston air pumps no pet valves are 
 fitted, as, no matter where they might be placed, the air drawn in 
 would affect the vacuum more or less seriously, since suction valves 
 are fitted at both ends of the pump. 
 
 Air Vessels. 
 
 Air vessels are usually fitted on single-acting pumps, to give a 
 continuous flow of water similar to that of a double-acting pump. 
 
 ^ 
 
 ^ 
 
 ^^NilLm 
 
 FB3M Pump 
 
 No, 13. — Closed Type Air 
 Vessel. 
 
 No. 14— Open Type 
 Air Vessel. 
 
\ 
 
 1^ „ 
 
 To find the probable cause of the vacuum going back feel the 
 temperature of both ends of the condenser. If l^oth ends a e cold 
 broken air pump valves are the cause, or leaky L.P. gland. If both 
 
General Notes and Descriptions 
 
 295 
 
 ends are warm, either broken circulating pump valves or choked injec- 
 tion valve is the cause. If one end is cold and the other end warm, 
 the division plate in the condenser is most likely carried away. 
 
 NOTE. ^24 inches of vacuum means that the air pump has drawn 12 lbs. of 
 air pressure out of the condenser, leaving 3 lbs. absolute back pressure on the 
 L. P. piston. 
 
 Pet Valves. 
 
 On feed or bilge pumps the pet valve is usually placed between 
 the suction and delivery valves. 
 
 On double-acting circulating pumps a pet valve is placed on the 
 suction side of the pump at both ends. 
 
 On air pumps the pet valve is placed high up on the pump 
 chamber, just under the head valve, so that the air drawn in for 
 cushioning the water will not affect the vacuum under the bucket. 
 Many air pumps have no pet valves fitted. 
 
 On horizontal double-acting piston air pumps no pet valves are 
 fitted, as, no matter where they might be placed, the air drawn in 
 would affect the vacuum more or less seriously, since suction valves 
 are fitted at both ends of the pump. 
 
 Air Vessels. 
 
 Air vessels are usually fitted on single-acting pumps, to give a 
 continuous flow of water similar to that of a double-acting pump. 
 
 Tolf)on.ERs 
 
 SA 
 
 No. 13. — Closed Type Air 
 Vessel. 
 
 No. 14. — Open Type 
 Air Vessel. 
 
296 " Verbal " Notes and Sketches 
 
 They are made in two ways — (i) A plain dome with the air for 
 compression in the top, the water entering and leaving by the same 
 branch. (2) A dome open at the top, with a pipe extending down 
 about three-quarters of the length of the vessel ; the pipe is to allow 
 of an air space round it, and the water in this case passes up through 
 the pipe and top of vessel into the main feed pipe. 
 
 On the down stroke of the pump plunger the water pressure 
 compresses the air in the top of the vessel, and on the up stroke, 
 the pressure being released, the air reacts on the water, and forces 
 it out of the chamber and along the feed pipe, thus giving a continu- 
 ous flow, similar to that obtained by a double-acting pump. 
 
 NOTE.— The Board of Trade appear to object to cocks or connections of any 
 kind being fitted to air vessels. 
 
 The Condenser and Air Pump. 
 
 The function of the air pump is to draw out the air and water from 
 the condenser, and, by the vacuum formed, to reduce the back pressure 
 on the L.P. piston. 
 
 As all water contains a certain proportion of air, the feed pumps 
 deliver air into the boilers along with the feed water, and most of the 
 air so brought in is carried back with the steam to the condenser, 
 where it remains in the form of back pressure. Air cannot be con- 
 densed in the same manner as steam, and for this reason the air pump 
 is required to take out the air and reduce the back pressure by the 
 formation of a vacuum in the condenser. 
 
 The valves most necessary in the air pump to maintain the vacuum 
 are the bucket and head valves ; foot valves are not absolutely neces- 
 sary when the pump is placed lower down than the bottom of the 
 condenser, as the water will then flow by gravity into the pump 
 chamber. 
 
 The air pump only delivers about i inch depth of water over the 
 valves each stroke, the remainder of the pump being filled with air 
 and vapour. 
 
 On the up stroke of the air pump the foot valves and head valves 
 are open, and on the down stroke the bucket valves only are open. 
 
 If the vacuum gauge indicates 24 inches, it means that the air 
 pump has taken 12 lbs. of air pressure out of the condenser, which 
 leaves a back pressure of 3 lbs. gross, as 15 — 12 = 3 lbs. 
 
 Oscillating Engines. 
 
 The steam enters the valve chest through one of the trunnions 
 (usually the outer), and after doing its work in the cylinder exhausts 
 through the other trunnion. 
 
 The trunnions allow the steam to pass to and from the valves, and 
 also allow for the oscillation of the cylinder. 
 
 k 
 
uaiaiiceu uy a. sh^iil iin-icdsc m luc i^uauLiLy oi ciicuiaLiiig vvatci 
 
 passing through the tubes, which ensures a more rapid flow. The 
 steam flow through the condenser is also more direct and more con- 
 vergent from top to bottom than in the usual pattern of condenser 
 as fitted. 
 
No. 15.— Surface Condenser (Two Flow Independent Type). 
 
 X, Exhaust or eduction pipe from L.P. cylinder to condenser. 
 
 2, Air pump soction. 
 
 3, Delivery from circulating pumps to condenser. 
 
 4, Circulating discharge from condenser to ship's side. 
 
 5, Stays. ' 
 
 6, Division platb 
 
 DATA. 
 
 Oooling Surface. 
 
 I.H.P. = i8oo. 
 
 Allow 1.4 square feet cooling surface per I.H.P. 
 
 Tubes, 10 feet by J inch external diameter. 
 
 7, Hand hole. 
 
 8, Baffle plate for steam. 
 
 9, Supplementary feed. 
 
 10, Tube plate. 
 
 11, Screwed ferrule. 
 
 12, Packing space. 
 
 1800 X 
 
 Then. 
 
 number of tubes= 
 
 ID X '15 X 31416 
 
 =1283 tubes. 
 
 NOTE.— The cooling surface of a tube in square feet= length in feet < circumference in feet 
 
 hot-well temperature 130°, sea 60', and di5x:harge ] 
 
 Circulating Water. 
 
 Assume exhaust steam pressure =5 lbs. absolute and temperatu 
 
 then, 1II5 + -3X 162 = 1163-6 total heat of steam, 
 
 and, li63'6- I30=i033'6 units to be extracted. 
 
 Again, io2-6o'=42 units absorbed by each pound of cooling water, 
 
 then, i033-6-i-42=24-6 lbs. cooling water required per lb. steam. 
 
 Assuming 15 lbs. steam per I.H.P. per hour, 
 
 then, 1800x15x24-6 = 664200 lbs. of circulating water required per hour. 
 
 Air Pump Water. 
 
 Exclusive altogether of expanded vapour and neglecting losses, the i 
 discharge it into the hot-well, as iSoo x 15 = 37000 lbs. 
 
 r pump will lift per hour 270 
 
 i lbs. of feed water and 
 
 [T>/ace /^i-r 296 
 
General Notes and Descriptions 
 Condenser Data. 
 
 296^ 
 
 Position. 
 
 Temperature Degs. Fahr. 
 
 Sea (outside) .... 
 
 65° 
 
 Circulating water 
 
 67° 
 
 Condenser (ist stage circulation) - 
 
 92- 
 
 Discharge (2nd stage circulation) - 
 
 122° 
 
 Exhaust 
 
 152° 
 
 
 Top. Bottom. 
 
 Hotwell 
 
 143° 140° 
 
 Filter 
 
 154° 
 
 Heater 
 
 220° (pressure, 10 lbs.) 
 
 NOTE.— The heater coil drain to hotwell accounts for the rise in temperature 
 shown at filter. Heater of the closed type with steam heating coils. After first 
 passage through the tubes the circulating water temperature rose from 67" to 92°, 
 and after second passage through tubes from 92° to 122° (discharge). 
 
 The Weir " Uniflux " Condenser. 
 
 A characteristic of the " Uniflux " condenser is its special contour, 
 whereby the entering steam is caused to traverse the cooling surface 
 at practically uniform velocity throughout its passage. 
 
 Provision is also made in the bottom of the condenser for ensuring^ 
 equality of distribution, so that no short circuiting of any portion 
 of the surface can take place. There are no baffle plates or partitions 
 to interfere with the steam flow in the body of the condenser. The 
 flow is therefore direct towards the bottom of the condenser from the 
 exhaust inlet to the draft plate. As a result of the maintenance of 
 the steam velocity the heat transmission value of the condensing 
 surface becomes greatly increased, while by the directness of the flow 
 the whole of the surface is uniformly operated, and no ineffective 
 zones can exist. 
 
 As compared to the ordinary type condenser, the Weir " Uniflux" 
 condenser has less cooling surface per H.P., but this is counter- 
 balanced by a slight increase in the quantity of circulating water 
 passing through the tubes, which ensures a more rapid flow. The 
 steam flow through the condenser is also more direct and more con- 
 vergent from top to bottom than in the usual pattern of condenser 
 as fitted. 
 
 i 
 
I 
 
 (a 
 
 thro^g^; Z ZZ\ZT" '°'"' ■■'= ^™^^ '" "^^ ■^y-'-'i- exhausts 
 
General Notes and Descriptions 
 Condenser Data. 
 
 296*^ 
 
 Position. 
 
 Temperature Degs. Fahr. 
 
 Sea (outside) .... 
 
 65" 
 
 Circulating water 
 
 6f 
 
 Condenser (ist stage circulation) - 
 
 92° 
 
 Discharge (2nd stage circulation) - 
 
 122° 
 
 Exhaust 
 
 152° 
 
 
 Top. Bottom. 
 
 Hotwell 
 
 143° 140° 
 
 Filter 
 
 154° 
 
 Heater 
 
 220° (pressure, 10 lbs.) 
 
 NOTE.— The heater coil drain to hotwell accounts for the rise in temperature 
 shown at filter. Heater of the closed type with steam heating coils. After first 
 passage through the tubes the circulating water temperature rose from 67° to 92°, 
 and after second passage through tubes from 92° to 122° (discharge). 
 
 The Weir " Uniflux " Condenser. 
 
 A characteristic of the " Uniflux " condenser is its special contour, 
 whereby the entering steam is caused to traverse the cooling surface 
 at practically uniform velocity throughout its passage. 
 
 Provision is also made in the bottom of the condenser for ensuring^ 
 equality of distribution, so that no short circuiting of any portion 
 of the surface can take place. There are no baffle plates or partitions 
 to interfere with the steam flow in the body of the condenser. The 
 flow is therefore direct towards the bottom of the condenser from the 
 exhaust inlet to the draft plate. As a result of the maintenance of 
 the steam velocity the heat transmission value of the condensing 
 surface becomes greatly increased, while by the directness of the flow 
 the whole of the surface is uniformly operated, and no ineffective 
 zones can exist. 
 
 As compared to the ordinary type condenser, the Weir " Uniflux" 
 condenser has less cooling surface per H.P., but this is counter- 
 balanced by a slight increase in the quantity of circulating water 
 passing through the tubes, which ensures a more rapid flow. The 
 steam flow through the condenser is also more direct and more con- 
 vergent from top to bottom than in the usual pattern of condenser 
 as fitted. 
 
t-l 
 
 c 
 
 G 
 O 
 (J 
 
 
 4J 
 
 
 o 
 
 :2: 
 
 296$ 
 
General Notes and Descriptions 
 
 297 
 
 An expansion joint is formed between that part of the steam pipe 
 which enters the trunnion and the trunnion itself. 
 
 The flanges of the steam pipe are bolted to a bracket on the 
 engine framing, as will be seen by referring to the sketch, and this 
 does away with the necessity of having a collar on the pipe and long 
 tuds, as are usually fitted to expansion joints of steam pipes. 
 
 No. 16— Oscillating Cylinder and Trunnions. 
 
 To test if one or other of the trunnion bearing brasses have worn 
 down, slacken back the piston rod head bolts and measure the 
 clearance between the crank web and piston rod brass at the top 
 centre and the bottom centre ; if the sizes do not agree one of the 
 trunnions has worn down. 
 
 In oscillating engines the feed and bilge pumps are worked by 
 large eccentrics, fixed either on the shaft or on the trunnions, and the 
 air pump by an extra crank on the main shaft : to allow of this the 
 pumps are usually of the trunk pattern (see sketches). 
 
 The valve gear of the oscillating engine (see sketch) consists of 
 two vertical pillars, connecting the top and bottom framing, with a 
 slotted quadrant working between them on brass shoes. The reversing 
 link from the eccentrics connects to a block on the quadrant. The 
 radius of the slot in the main quadrant is taken from the centre of 
 the trunnion with the gear at half position, the radius of the reversing 
 link slot is taken from near the shaft centre. Usually two valves are 
 fitted, one on either side, each supplying steam simultaneously to 
 the cylinder or exhausting simultaneously from the cylinder. The 
 block on which the reversing link slides is a fixture, it should be 
 
I 
 
 298 
 
 " Verbal " Notes and Sketches 
 
 I 
 
 PUMP 
 tCCENTRIC 
 
 No. 18. — Method of working Pumps in Oscillating Engines. 
 
 noted, to the main quadrant, and the drag link changes the position 
 of the link and rods from ahead to astern as required. A rocking 
 lever works on a pin fixed on the side of the cylinder, and one end of 
 the lever moves in the slot of the quadrant as the cylinder oscillates ; 
 the other end is connected to the valve spindle, and so gives the 
 necessary travel to the valve, but in the opposite direction. 
 
 NOTE. — For a slide valve, the eccentric key centre is placed behind the crank 
 at an angle of 90°, minus lap and lead, because the rocking lever reverses the 
 motion, but if a piston valve (inside steam), the key is cut at an angle of 90° plus 
 lap and lead before the crank, as the one position corrects the other. 
 
 Diagonal Engines. 
 
 No. 19.— Diagonal Engine and Air Pumps. 
 
wii:^ 
 

 o « Z 
 
 O iS ! 
 
 I a- 
 
 ■II s 
 
 Mil 3l!p{i I . 
 
General Notes and Descriptions 
 
 299 
 
 In diagonal engines the pumps are often worked by bell crank 
 levers connected to the piston rod crosshead (see sketch), and the 
 pumps are usually made of the trunk type. 
 
 Trunk Engines. 
 
 A trunk engine has no piston rod, but simply a connecting rod 
 extending between the crank-pin and the piston. The trunk passes 
 
 BEPU 
 
 No. 20.— Trunk Engine and Double-Acting Air Pump. 
 
 through both ends of the cylinder, and is bolted by a flange to the 
 piston. For a right-handed propeller this type of engine is placed on 
 the starboard side of the engine-room, so that when going ahead the 
 stress will be thrown on the top side of the trunk and piston ; for a 
 lleft-handed propeller the engine would be placed on the port side to 
 obtain the same result. 
 
 The air pump shown on the sketch is of the double-acting type, 
 and has foot and head valves at either end, and a solid piston ; the 
 condenser suction is below, and the hot-well above. When the engines 
 are of the inverted type, the pump is worked from the main shaft by 
 an eccentric, or by a pin on the crank web. 
 
 Paddle Engine Cranks. 
 
 In nearly all paddle engine crank-shafts, the crank-pin is only 
 fixed to one web, and is an easy fit in a brass bush in the other web 
 (see sketch). This is to allow for the extra wear which takes place 
 at the outside bearing due to the weight of the paddle wheels. The 
 crank-pin is fitted into one web by a taper and nut, and in the other 
 web it is simply a loose fit in a brass bush as previously stated. 
 
 This arrangement allows for the shaft wearing down outside, and 
 prevents undue stresses being thrown on the web and on the pin. 
 
 In ordinary paddle engines with double cranks the crank-pin is 
 fixed to the inner web and is loose in the outer web, but in discon- 
 necting paddle engines the reverse is the case, that is, the pin is 
 fixed to the outer web, and is loose in the inner one. This is to allow 
 
i 
 
 1 
 
General Notes and Descriptions 
 
 299 
 
 In diagonal engines the pumps are often worked by bell crank 
 levers connected to the piston ro<:l crosshead (see sketch), and the 
 pumps are usually made of the trunk type. 
 
 Trunk Engines. 
 
 A trunk engine has no piston rod, but simply a connecting rod 
 extending between the crank-pin and the piston. The trunk passes 
 
 No. 20.— Trunk Engine and Double-Acting Air Pump. 
 
 through both ends of the cylinder, and is bolted by a flange to the 
 piston. For a right-handed propeller this type of engine is placed on 
 the starboard side of the engine-room, so that when going ahead the 
 stress will be thrown on the top side of the trunk and piston ; for a 
 left-handed propeller the engine would be placed on the port side to 
 obtain the same result. 
 
 The air pump shown on the sketch is of the double-acting type, 
 and has foot and head valves at either end, and a solid piston ; the 
 condenser suction is below, and the hot-well above. When the engines 
 are of the inverted type, the pump is worked from the main shaft by 
 an eccentric, or by a pin on the crank web. 
 
 Paddle Engine Cranks. 
 
 In nearly all paddle engine crank-shafts, the crank-pin is only 
 fixed to one web, and is an easy fit in a brass bush in the other web 
 (see sketch). This is to allow for the extra wear which takes place 
 at the outside bearing due to the weight of the paddle wheels. The 
 crank-pin is fitted into one web by a taper and nut, and in the other 
 web it is simply a loose fit in a brass bush as previously stated. 
 
 This arrangement allows for the shaft wearing down outside, and 
 prevents undue stresses being thrown on the web and on the pin. 
 
 In ordinary paddle engines with double cranks the crank-pin is 
 fixed to the inner web and is loose in the outer web, but in discon- 
 necting paddle engines the reverse is the case, that is, the pin is 
 fixed to the outer web, and is loose in the inner one. This is to allow 
 
;oo 
 
 " Verbal " Notes and Sketches 
 
 No. 21.— Method of Testing Fairness of Paddle Shaft. 
 
 of the inside crank being drawn away from the pin when the engines 
 have to be disconnected. 
 
 From the above it will easily be understood that to test if the 
 outer bearing is wearing down, the cranks must be placed on the top 
 centre, and the distance between the webs at the top taken by a 
 length stick ; then the cranks put on the bottom centre, and the same 
 distance again measured ; if it is found that the top width is greater 
 than the bottom, the outer bearing will be down. 
 
 To find Thickness of Liner for Outer Bearing. 
 
 Referring to the sketch, suppose that the distance between the 
 webs is 1 inch more at the top than at the bottom, and the distance 
 from the top of the web to the centre of the shaft is A, and from the 
 centre of the outer bearing to the inside of the web is B, then by 
 proportion as follows : — 
 
 As A: B : : ^ inch = thickness of liner required. 
 
 NOTE.— Observe that it is only half the amount that the webs are open at 
 top more than at bottom, which is taken for the third term. 
 
General Notes and Descriptions 
 
 301 
 
 Paddle Shaft Flexible Coupling. 
 
 If the crank-shaft of a paddle engine is made similarly to that of 
 a screw steamer, that is, with the webs and pins forged solid, or built 
 up, allowance for wear down is arranged for by a flexible coupling 
 fitted between the paddle shaft and the crank-shaft (see page 325). 
 
 The coupling consists of a hard rubber ring fitted between the 
 two flanges with the coupling bolts an easy fit in one side, the holes 
 being made larger for that purpose. This allows for the outside 
 bearing wearing down, and prevents the pin and webs from being 
 subjected to heavy stresses in consequence. 
 
 Feathering Paddle Wheel. 
 
 In a feathering paddle wheel the floats are hung by pins to 
 brackets on the circumference of the wheel, the brackets being bolted 
 to the rim and forming continuations of the paddle arms. 
 
 No. 22. — Feathering Paddle Wheel. 
 
 The floats have small feathering levers (see sketch) fitted on the 
 back, to which the eccentric rods are connected by pins in brass 
 bushes, the other end of the rods being fitted in a similar manner to 
 the feathering strap. 
 22 
 
302 
 
 "Verbal" Notes and Sketches 
 
 The feathering pin is fixed to a bracket bolted to the outer paddle 
 box, and its centre is placed forward of the shaft centre and higher 
 up so that the pin position is " eccentric " to that of the shaft ; the 
 feathering strap revolves round the pin which is stationary. One rod, 
 called the *' driver," is made of greater strength than the others, and, 
 
 No. 23. — Feathering Paddle Wheel. 
 
 instead of being secured to the strap by an eye and pin, is fitted in to 
 a specially arranged recess and firmly bolted there ; the other end of 
 this rod is connected to the float in the same manner as the other 
 rods : the driving rod gives the motion to the feathering strap, and 
 therefore to the other rods. The feathering pin being eccentric to the 
 shaft, the floats are feathered as the wheel turns round, that is, they 
 alter their angle so as to enter the water in a vertical position, and 
 thus obtain a good thrust, and leave it at an inclined position, which 
 prevents loss of power by water being lifted up. 
 
 The various pins mentioned are brass bushed, and lubricated 
 with water. 
 
General Notes and Descriptions 
 Engine-Room Appliances. 
 
 ^^ To condenser 
 
 Feed Pumps 
 
 bo Puppa 
 
 No. 24— "Weir" Feed Heater 
 
 In this well-known type of feed- water heater, the heating steam 
 is taken from the low-pressure receiver of the main engines and 
 exhaust of the auxiliary engines, and enters the heater through 
 a non-return valve on the side ; the feed water is forced up 
 into the top of the heater by the main feed pumps on the engine, and, 
 the pressure of the water overcoming the tension of the spring, forces 
 open the internal valve and allows the water to enter the body of the 
 chamber, through a perforated ring in the form of a fine spray, which, 
 
304 
 
 "Verbal" Notes and Sketches 
 
 No. 25. — Weir Vertical Type Evaporator. 
 
General Notes and Descriptions 
 
 305 
 
 No. 26.— Weir Vertical Type Evaporator. 
 
3o6 " Verbal " Notes and Sketches 
 
 meeting the heating steam entering by another set of perforations 
 becomes raised in temperature to that of the steam : the air present 
 in the water is set free by the heat, and rising, escapes from the heater 
 by a cock on the top to either the condenser or the atmosphere. The 
 float shf>vvn near the bottom of the heater is connected by a system of 
 levers to the steam stop valve of " Weir's" pumps, which take away 
 the hot feed water and deliver it into the boilers, and as the water 
 level in the chamber falls, the float sinking shuts off the steam supply 
 to the pumps, so that they work slower, and, on the other hand, when 
 the water level is high, the float rising correspondingly opens the 
 steam valve, and the pumps work faster in proportion. 
 
 Two pressure gauges are fitted on the top of the heater, one to 
 indicate the water pressure entering, and the other to indicate the 
 pressure in the body of the chamber, upon which latter depends the 
 temperature of the hot feed water. 
 
 NOTE.— With a pressure of S lbs. in the L.P. receiver, the feed temperature 
 in the heater will be about 220°. 
 
 Advantages of Feed Heating. 
 
 The practical advantages of feed heating are as follows : — 
 
 1. Less straining of the plates in high-pressure boilers. 
 
 2. Less air enters the boilers, and consequently the corrosion due 
 to oxygen is reduced. 
 
 3. The boilers steam better with hot feed water, as circulation is 
 checked when cold water enters a boiler. 
 
 4. The heat of condensation of the steam is given up to the feed 
 water instead of being given to the circulating water and lost over the 
 side, as would be the case if the steam condensed in the condenser. 
 
 "Weir" Evaporator. 
 
 The Weir Vertical Type Evaporator is a single casting of close- 
 grained cast iron. The heating surface is formed of heavy solid 
 drawn copper tubes attached by hollow conical couplings, at one 
 end to the steam inlet chamber cast on the side of the evaporator, 
 and at the other end to the corresponding outlet chamber cast 
 alongside it. 
 
 The tube space is separated from the steam space by a deflector. 
 The arrangement of this deflector allows the steam to rise, but 
 throws down the water so that it is returned again to the water 
 space. With this arrangement it is almost impossible to make the 
 evaporator prime under anything like reasonable limits. 
 
 The usual mountings consist of steam inlet valve, steam outlet 
 valve, feed check valve, brine valve, drain valve and coupling to 
 hot-well, blow-off cock, safety valve, gauge glass fittings, pressure 
 gauge, compound gauge, salinometer valve, also gun-metal feed 
 pump to work off main engines. 
 
General Notes and Descriptions 
 
 307 
 
 1, Steam Slide Valve Chest. 
 
 2, Double Joint. 
 
 3, Front Stay. 
 
 4, Bottom Spindle. 
 
 5, Valve Gear Levers. 
 
 6, Front Stay Bush. 
 
 7, Ball Crosshead. 
 
 8, Main Crosshead. 
 
 9, Crosshead Pin. 
 
 10, Piston Rod. 
 
 11, Piston Body. 
 
 12, Piston Rings. 
 
 13, Cylinder Cover. 
 
 14, Discharge Valve Seat. 
 
 15, Discharge Valve Seat Ring. 
 
 16, Suction Valve Seat. 
 
 17, Suction Valve Guard. 
 
 18, Discharge Valve Guard. 
 
 19, Water Valves. 
 
 20, Bucket. 
 
 22, Pump Cover. 
 
 23, Valve Chest Covers. 
 
 24, Steam Stop Valve. 
 
 25, Exhaust Stop Valve. 
 
 No. 27.- Sectional View, Weir Standard Feed Pump. 
 
\oS 
 
 Verbal " Notes and Sketches 
 
 List of Parts of Evaporator. 
 
 1. Shell of Evaporator. 
 
 2. Main door of Evaporator (i) for 
 
 withdrawing tube coils (6). 
 
 3. Hand cleaning door. 
 
 4. Baffle plate, or deflector. 
 
 5. Shelves for supporting tube coils (6). 
 
 6. Evaporating tube coils. 
 
 7. Inlet steam couplings for coils (6). 
 
 8. Drain outlet couplings for coils (6). 
 
 9. Coupling nuts for 7 and 8. 
 
 10. Inlet steam header. 
 
 1 1. Drain header. 
 
 12. Drain collecting pocket. 
 
 13. Inlet valve for steam coils (6). 
 
 14. Valve for drain from coils (6) to hot- 
 
 well. 
 
 1 5. Feed check valve. 
 
 16. Brine valve. 
 
 17- 
 18. 
 19. 
 20. 
 21. 
 22 
 
 24. 
 25. 
 
 26. 
 
 27. 
 
 Salinometer cock. 
 
 Cock for blowing off to sea. 
 
 Top cock for water gauge. 
 
 Bottom cock for water gauge. 
 
 Safety valve. 
 
 Outlet valve for generated steam. 
 
 Compound gauge for generated 
 
 steam in shell (i). 
 Cock for compound gauge (23). 
 Pressure gauge for inlet steam to 
 
 coils (6). 
 Cock for pressure gauge (25). 
 Swing crane bar for door (2). 
 Eye bolt for supporting door (2) on 
 
 crane bar (27). 
 Connection from top of water gauge 
 
 (19) to steam space in Evaporator 
 
 shell (I). 
 
 Weir's Patent Direct Acting Feed Pumps. 
 
 (To work in connection with Main Feed Pumps and Heater.) 
 
 The Weir pump is of the direct-acting type, and has suction and 
 delivery valves for top and bottom independently. 
 
 The pump is vertical, single cylinder, and is usually supplied in 
 pairs. 
 
 The steam piston is fitted to the top end of the rod, and the 
 water piston to the bottom end, the latter being smaller in area than 
 the former. 
 
 Weir's feed pump is a slow-speed, high-pressure, full-stroke pump. 
 
 Group Valves. — These are milled out of the solid metal, and are 
 arranged to give a large area with a small lift. Each seat contains 
 a number of small valves, and in all cases these are duplicate, with a 
 lift of ^ inch. The delivery valves have light springs fitted. The 
 suction seat contains a larger number of small valves than the delivery 
 seat ; it will therefore be noted that the delivery valves have less area 
 than the suction valves, and in addition have small springs fitted to 
 keep them down. 
 
 The screwed pin in the centre of the valve box covers is for 
 keeping the valve guards in position, and is not for regulating the lift 
 of the valves. 
 
 The Weir Steam Valves. — The steam valves of W^eir's pumps are 
 simple in action, and the main valve face (known as the " shuttle " 
 valve) is half round instead of flat, and instead of travelling up and 
 down is moved by steam horizontally from side to side. The ports 
 
General Notes and Descriptions 
 
 509 
 
 End View. Cylinder Face (Half Round). 
 
 A, Steam Port to Cylinder Bottom. C, Steam Port to Cylinder Top. 
 B, Exhaust Port. 
 
 No. 28.— Weir Pump Cylinder Ports. 
 
 are therefore arranged to allow of this, and are cast side by side in 
 place of one above the other. The result is, of course, the same, as 
 the left-hand port leads to the bottom of the cylinder, and the right- 
 hand port to the top (see sketch). 
 
 Main Valve. — As before stated, this valve is moved by steam hori- 
 zontally in the chest, and in this way opens up the cylinder ports from 
 steam to exhaust at the end of each stroke. It must be remembered, 
 however, that previous to this the steam passing through the main 
 valve into the cylinder ports has already been cut off by the expansion 
 valve at three-quarters stroke. The ends of the main valve are round, 
 and work in extended cylindrical casings at each side of the chest, 
 the valve being moved across by steam alternately admitted and 
 exhausted from the ends which act as pistons. 
 
 The main valve has two faces. That on the front contains four 
 ports, two steam and two exhaust. The face on the back contains 
 five ports (see sketch). 
 
 The port E leads from back to front and admits steam to the 
 cylinder bottom by port A. 
 
 The port D leads from back to front and admits steam to the 
 cylinder top by port C. 
 
 The port G admits steam to, or allows of exhaust from, the left 
 side of the chest in which the round end of the main valve works 
 steamtight. 
 
 The port H admits steam to, or allows of exhaust from, the right- 
 hand side of the chest in which the round end of the main valve works 
 steamtight. 
 
 The centre exhaust port F is common to all the ports. Observe 
 that port G leads to the left-hand end, where a small hole allows the 
 steam to pass out and act on the piston end of the main valve to 
 
3IO 
 
 " Verbal " Notes and Sketches 
 
 No. 29.— Main (Shuttle) Valve Front Face (Half Round). 
 
 No. 30.— End View (Left). 
 
 No. 31.— Shuttle Valve Back Face (Flat). 
 
 force it across ; it also allows of exhaust to take place from that end 
 to the exhaust port F by means of the small auxiliary or expansion 
 valve. 
 
 Auxiliary Valve.— This small valve works vertically on the back of 
 the main valve, and admits steam to the ports E D and G H alternately, 
 or allows of exhaust from H and G to port F. 
 
 The auxiliary valve is moved up and down by the levers from the 
 
General Notes and Descriptions 
 
 311 
 
 pump rod striking a pair of adjustable nuts fitted in the valve spindle, 
 the distance between the nuts allowing of a certain amount of lost 
 motion. 
 
 The auxiliary valve has two separate functions : — 
 
 1. To work the main slide valve by admitting steam and exhaust- 
 ing it from the valve ends ; and 
 
 2. To cut off steam at a definite part of stroke. 
 
 No. 32.— Expansion (Auxiliary) Valve Face. 
 
 No. 33.— End View of Main and Auxiliary Valves in Position. 
 
 Action of Valves (Up Stroke). — When the cylinder piston is on the 
 bottom centre, the main valve is at the right-hand side of the chest, 
 and the auxiliary valve at its lowest position. Steam is then entering 
 through the main valve port E into the bottom port A of the cylinder, 
 and to the left-hand end of the main valve by port G : this continues 
 as the piston moves upward until about half stroke, when the lever 
 strikes the nut on the auxiliary valve spindle, and the valve coming 
 up cuts off the steam entering port E at about three-quarters stroke ; 
 the steam in the main valve and cylinder then expands and completes 
 the stroke. When the piston reaches the end of the stroke the 
 auxiliary valve opens up the exhaust port G from the left-hand end 
 of the main valve, and the steam acting on the other end, forces the 
 valve across, thus opening the bottom cylinder port A to the exhaust 
 
312 
 
 "Verbal" Notes and Sketches 
 
 No. 34.— Plan of Main and Auxiliary Valves in Position for 
 Steam to Bottom of Cylinder. 
 
 and at the same time opening the top cylinder port C to steam for 
 the down stroke. 
 
 For the down stroke the same process is gone through with the 
 other ports, the main valve moving in the opposite direction, that is, 
 from left to right. It is important to note that the main valve does 
 not move until one end is opened to exhaust : it is then forced across 
 by the steam pressure on the opposite end. 
 
 The auxiHary valve after opening the end to exhaust by port G 
 or H, is arranged to close again, so that steam is retained to act as 
 a cushion to the main valve when it flies over, and thus prevent 
 hammering on the chest end covers. It will be seen from the fore- 
 going that the valve gear is positive in action, the main valve being 
 always open to steam for one end of the cylinder, and to exhaust for 
 the other end, with the piston on the corresponding centre. It is 
 therefore impossible for the pump to stick on the centre points. 
 
 Bye-Passes. — Small bye-passes are fitted at each end of the cylinder 
 to admit steam full stroke when required. This may be necessary 
 when starting the pumps, as the cylinder may then contain a quantity 
 of water. " Knocking " can also be reduced by suitable adjustment of 
 the bye-passes. 
 
 The bye-passes are formed either by notches cut in the edges of 
 the cylindrical caps, which may be opened or shut by turning round 
 the caps, or by parallel plug cocks, one at each side, which can be 
 adjusted to admit as much steam as required for the occasion. 
 
 To Adjust the Length of Stroke of a Weir Feed Pump. 
 
 This is done by screwing the valve spindle up into the joint until 
 the piston comes to rest against the cylinder cover, without having 
 raised the auxiliary valve sufficient to throw the main valve. By 
 noting the distance of the crosshead from the gland when the piston 
 is against the cylinder cover, the spindle can be brought down until 
 the valve throws and the piston clearance is \ inch. The lock nut 
 
General Notes and Descriptions 
 
 o' J 
 
 should now be carefully fixed to prevent the spindle from shaking 
 loose. The bottom stroke adjustment is done by slacking the nuts 
 on the bottom end of the spindle. These should be screwed down 
 until the piston rests against the bottom of the cylinder, and by again 
 noting the distance of the crosshcad from the pump gland you can 
 again adjust it for the valve to throw when the pump has ^ inch of 
 clearance. Always run the pump slowly when adjusting the stroke. 
 It is most important that anyone having the working of a "Weir" 
 Pump should become familiar with the method of adjusting the stroke. 
 
 Feed- Water Filters. 
 
 A feed-water filter is employed to prevent oil and grease from 
 entering the boilers with the feed water. It is usually placed between 
 the feed pumps and the feed check valve, and consists of a cast-iron 
 
 No. 35.— Feed Water Filter. 
 
 (American Steam Gauge and Valve Manufacturing Co.) 
 
 chamber containing a series of perforated brass plates with filter 
 cloths fitted between them, or brass grids arranged in a similar 
 manner. 
 
 The feed water is forced through the perforations and cloths, and 
 leaves behind the greasy matter, which is blown out at intervals. 
 
 The fittings on the filter are : — Bye-pass valve (used when cleaning 
 out or changing the cloths), safety valve, pressure gange, soda cock, 
 and drain cock. 
 
 Sometimes, instead of cloths, ashes or charcoal are used as the 
 filtering medium. 
 
;i4 
 
 "Verbal" Notes and Sketches 
 
 Aspinall's Patent Governor. 
 
 Aspinall's patent governor is usually bolted to the side of the 
 pump levers, and consists of a frame containing a hinged weight W, 
 which operates on two pawls P, P ; the pawls when in action striking 
 a lever connected to the throttle valve and so regulating the steam 
 supply to the engines. 
 
 No. 36.— Aspinall Governor. 
 
 When the revolutions increase by about 5 per cent, above the normal 
 speed, the weight W is left behind by the increase of momentum, 
 and this reverses the position of the pawls, causing the bottom one to 
 fall out and strike the lever H, and lift it on the upward stroke ; the 
 throttle valve is by this means closed : on the downward stroke the 
 detent D is lifted, and this again sets free the weight W, and, if 
 the racing is over, the top pawl P strikes the lever H and brings it 
 back again to its original position, which has the effect of reopening 
 the throttle valve. An emergency gear is also fitted, which locks 
 the weight W in the shut-off position, in the event of a serious 
 accident happening, such as, for example, the shaft breaking or the 
 propeller coming off. This type of governor is fitted to the turbine 
 steamer " Carmania." 
 
 i/orthington Vertical Type Feed Pumps (Sketch No. 37). 
 
 These pumps are supplied in pairs, the crosshead of one pump 
 actuating the steam valve of the other pump. The steam valve is 
 generally of the piston type and is allowed about \ inch or f inch 
 " lost motion " to allow of full steam admission each stroke ; double 
 ports are arranged for at top and bottom, the outer one being for 
 steam admission only and the inner one for exhaust only, compres- 
 sion and cushioning being provided for by the piston travelHug over 
 and closing the inner or exhaust ports, and so retaining the required 
 amount of compression steam. 
 
 The water valves are spring loaded, and are, of course, four in 
 number, one suction and one delivery for either end of pump. By the 
 momentary pause which occurs at the end of each stroke, the suction 
 valve of one end and the delivery valve of the other end get time to 
 seat themselves quietly and without shock. 
 
General Notes and Descriptions 315 
 
 No. 37.— Worthington Patent Feed Pump. 
 
3i6 "Verbal" Notes and Sketches 
 
 To Set the Valves of a Worthington Type Pump. 
 
 The steam valve of a Worthington pump has no outside lap, 
 consequently, when in its central position, it just covers the steam 
 ports leading to opposite ends of cylinder. 
 
 By lost motion is meant the distance a valve rod travels before 
 moving the valve ; or, if the steam chest cover is off, the amount of 
 lost motion is shown by the distance the valve can be moved back 
 and forth before coming in contact with the valve rod nut. 
 
 To set the piston in the middle of its stroke, open the drip cocks 
 and move piston by prying on the crosshead (not on lever), until it 
 comes in contact with the cylinder head ; make a mark on piston rod 
 at face of steam end stuffing box follower ; move piston back to 
 contact stroke at opposite end. Make second mark on piston rod 
 half-way between first mark and the aforesaid follower. Then if 
 piston is again moved until second mark coincides with the face of 
 same follower, it will be exactly at the middle of its stroke. 
 
 Bear in mind that the piston on one side moves the valve on 
 opposite side. 
 
 {a) When the steam valve is moved by a single valve rod nut. 
 
 Place one piston in the middle of its stroke ; disconnect link from 
 head of valve rod on opposite side. Then set the valve in its central 
 position ; place valve nut evenly between jaws on back of valve, screw 
 valve rod in or out until eye on valve rod head comes in line with eye 
 of valve rod link ; then reconnect. Repeat the operation on opposite 
 side and the valves will be properly set. 
 
 ib) When the valve rod has more than one lock nut. 
 
 Place one piston in the middle of its stroke and the opposite slide 
 valve in central position ; adjust lock nuts so as to allow about yV hich 
 lost motion on each side of jaw, and valve is set. Do not disconnect 
 the valve motion. Repeat operation on other side. 
 
 The best way to divide the lost motion equally is to move the 
 valve each way until it strikes the nut or nuts, and see if the port 
 openings are equal. 
 
 It is advisable to place both pistons at the middle of their strokes 
 before touching either slide valve. 
 
 Too much lost motion will tend to lengthen the stroke, and may 
 cause the piston to strike the cylinder heads ; vice "Oersd, when there 
 is not enough lost motion the stroke will be perceptibly shortened. 
 
 Lamont Pump (Sketch No. 38). 
 
 Action. — P is the auxiliary piston, which, with both slide valves 
 S and T, is moved by the main piston B before coming to rest, by 
 means of the links and levers to a little over the central position, 
 and this puts one end of the auxiliary cylinder R in communication 
 with pressure and the other end with the exhaust, whereby the 
 auxiliary piston and valves S and T are moved by the steam pressure 
 on P to the extent necessary to give full port openings to the main 
 
General Notes and Descriptions 
 
 M 
 
 cylinder, and at the same time the auxiliary piston P covers the 
 supplementary port V to the end of the main cylinder, which is open 
 to the exhaust and uncovers the one at the end open to steam 
 pressure. The opening and closing of the supplementary ports 
 VS V by the piston P takes place simultaneously with the opening of 
 steam or exhaust to the ends of the auxiliary cylinder R, so that 
 as soon as either supplementary port V^ or V is uncovered by P, 
 steam is admitted to that end of the auxiliary cylinder by the slide 
 
 No. 38.— Lament's Patent Pump. 
 
 valve T, and conversely as soon as the slide valv^e T opens either 
 end of the auxiliary cylinder to exhaust the supplementary port in 
 that end V^ or V is covered by P. The drawing shows the piston P 
 and the auxiliary valve T in the central position, but the main valve S 
 is still open, and will cause the main piston B to move in the direction 
 of the arrow until it passes the port W, which is open to the exhaust, 
 when it will gradually be brought to rest by the imprisoned steam 
 forming a cushion between the piston and the end of the cylinder, as 
 23 
 
3i8 
 
 " Verbal " Notes and Sketches 
 
 this space is now completely closed. The stop nuts N N are fixed on 
 the valve spindle M in such a position as just to move P a little over 
 the central position before the main piston B comes to rest. The 
 auxiliary valve T will then admit steam by the auxiliary port Z to the 
 end of the auxiliary cylinder R, and at the same time the other end of 
 the auxiliary cylinder will be opened to the exhaust through the port 
 Z^ The pressure of the steam will thus cause the auxiliary piston, 
 with both slide valves S and T, to move to the other end, and so 
 reverse the steam and exhaust passages to the main cylinder, but 
 as the main piston B still covers the port \V in the cylinder, the steam 
 will only be admitted through the supplementary port V until the 
 piston B has moved so as to uncover the port W and allow the full 
 flow of steam. The compression and slow reversal of motion is the 
 same for both ends of the stroke. 
 
 Engine and Boiler Data. 
 
 A good idea of the general proportions and dimensions for a 
 steamer of given speed and power will be obtained from the following 
 data taken from a modern fast ocean-going steamer : — 
 
 Boilers, Number 
 
 2 single-end; 2 double-end 
 
 Pressure 
 
 - 185 lbs. 
 
 Diameter 
 
 15 ft. 6 in. 
 
 Length - 10 ft. 
 
 6 in.; 18 ft. 
 
 Number of furnaces 
 
 18 
 
 H.S. total - 
 
 14840 sq. ft. 
 
 G.S. „ - - 
 
 465 >, 
 
 LH.P. on trial - 
 
 6500 
 
 Speed ,, 
 
 - 17 knots 
 
 H.S.--LH.P. - 
 
 2-28 
 
 LH.P. -f G.S. - 
 
 - 13-98 
 
 H.S. -^ G.S. 
 
 31-91 
 
 Length over -all - - 434 ft. 
 
 „ between perps. - 420 ,, 
 Breadth, moulded - - 50 „ 
 Depth, ,, - 30 ft. 6 in. 
 
 Height between decks, 7 „ 1 1 ,, 
 Gross tonnage - - 5600 tons 
 
 Engines - - - single, triple 
 
 Diameter cylinders 
 
 31, 51, and 85 in. 
 
 Stroke - - - 54 ,. 
 
 Valves, piston on H.P., slide 
 on LP. and L.P. 
 
 Pressure Gauge Indications. 
 
 The boiler pressure gauge indicates the pressure in the boiler above 
 the atmosphere, and therefore the initial pressure in the H.P. cylinder 
 (less a few pounds drop of the pressure). 
 
 The M.P. gauge indicates roughly the back pressure on the H.P. 
 piston, and the initial pressure in the M.P. cylinder. 
 
 The L.P. gauge indicates roughly the back pressure on the M.P. 
 piston, and the initial pressure in the L.P. cylinder. 
 
 The vacuum gauge indicates how many pounds of pressure the 
 air pump has taken out of the condenser, and if this be subtracted 
 from the atmospheric pressure of 15 lbs., it will give the pressure 
 still left in the condenser, and therefore acting on the L.P. piston as 
 back pressure (approximately). 
 
 Example. — The boiler pressure gauge indicates 160 lbs., the 
 M.P. gauge 53 lbs., the L.P. gauge 8 lbs., and the vacuum gauge 
 
General Notes and Descriptions 319 
 
 24 inches. Allow a drop of pressure between boilers and engines 
 
 of, say, 5 lbs. 
 
 Then, Boiler pressure - - - - 1 60 lbs. gauge. 
 
 Initial pressure in H.P. cylinder - 155 lbs. „ 
 
 Back pressure in H.P. - - - 55 lbs. gauge. 
 
 Initial pressure in M.P. - - - 53 lbs. „ 
 
 Back pressure in M.P. - - - 10 lbs. gauge. 
 
 Initial pressure in L.P. - - - 8 lbs. „ 
 
 Back pressure in L.P. - - - 4 lbs. gross. 
 
 Pressure in condenser - - " 3 lbs. „ 
 
 Notice that the gross back pressure on the L.P. piston is obtained by- 
 taking the vacuum in pounds from the atmospheric pressure. Thus : 
 24 inches -i- 2= 12 lbs., and 15 — 12 = 3 lbs. pressure in the condenser, 
 which is, within a pound or so, the back pressure on the L.P. piston. 
 
 NOTE. — Allow a difference of about 2 lbs. between the back pressure of the 
 one engine and the initial pressure in the next engine, as naturally a fall of 
 pressure must take place between the two. 
 
 The Barometer. 
 
 The barometer is an instrument used in measuring the pressure 
 or weight of the atmosphere. 
 
 The mercurial type of barometer consists of a glass tube fully 31 
 inches in length, closed at the top, and open at the bottom to a cup 
 containing mercury. Between the mercury and the top of the tube there 
 is a vacuum practically perfect, and the pressure of the atmosphere 
 acting on the surface of the mercury in the cup forces it up the tube 
 against the vacuum in the top, and so indicates the air pressure. 
 
 When the weight of the atmosphere is 1 5 lbs. per square inch, the 
 difference in level of the mercury in the cup and tube will be 30 
 inches, and this is termed the height of the barometer. 
 
 It will thus be seen that every pound of atmospheric pressure 
 raises the mercury 2 inches up the tube, and the atmosphere being 
 15 lbs., then 15x2 inches = 30 inches of mercury. If the atmo- 
 spheric pressure fell to 14 lbs. the barometer would show 28 inches, 
 and if the atmosphere increased to 15^- lbs. the barometer would 
 indicate 31 inches, and so on, every pound causing a difference of 
 2 inches, and every | lb. i inch in the mercury level. 
 
 High up, as, for example, on a mountain top, the barometer will show 
 less than 30 inches, because the air pressure will be less than 15 lbs. ; 
 and low down, as at the bottom of a mine, the barometer height will be 
 more than 30 inches, as the atmospheric pressure will exceed 15 lbs. 
 
 If water were used instead of mercury, then the height of the 
 barometer would be 34^7 feet, because 15 lbs. x 2-305 = 34-5 feet: this 
 is, at the same time, the theoretical limit that a pump can draw up 
 water. In practice the limit is 26 feet, as it is impossible to obtain 
 a perfect vacuum, even with the best pump fittings, &c. 
 
 NOTE.— One pound of pressure per square inch is equal to a column of water 
 2-305 feet in height. 
 
320 
 
 " Verbal " Notes and Sketches 
 
 If the pump has to draw water at a high temperature, then the 
 limit of hft becomes less, as tlie temperature rises, and at, say, 
 200" Fahr. the pump would hardly draw up the water any height, 
 owing to the vapour formed destroying the vacuum. This is the 
 reason that " Weir's " feed-heater is placed high up in the engine- 
 room, so that the water may fall by gravity to the pump suction. 
 
 The barometer can be made to act as a vacuum gauge by opening 
 up the closed end, and connecting it by a pipe to the condenser, the 
 
 30 
 
 _ _v 
 
 •VACUUM 
 
 MERCURY 
 
 OPEN 
 
 No. 39.— Mercurial Barometer. 
 
 other end being still left open to the atmosphere. Every pound of 
 pressure taken out of the condenser by the air pump will cause the 
 mercury to rise 2 inches in the tube; therefore if, say, I2i lbs. are 
 drawn out by the air pump, the difference of level in the cup and 
 the tube will be 25 inches. If there be no vacuum in the condenser, 
 the level of the mercury will be the same in the cup and in the tube, 
 that is, there will be no difference of level. 
 
 Aneroid Barometer. — The barometer in general use at the present 
 day is of the " aneroid " type, consisting of a vacuiun box at the back. 
 
General Notes and Descriptions 321 
 
 and a set of very sensitive levers connecting to the indicating pointer 
 on the dial face. 
 
 The variations in the atmospheric pressure act on the back of the 
 vacuum box, and either slightly force it in, or allow it to ease back, 
 and this setting in motion the set of finely adjusted levers and gear, 
 causes the pointer to move round the dial and indicate correspond- 
 ingly the pressure of the atmosphere. 
 
 The Thermometer. 
 
 The thermometer is ' an instrument used in measuring the 
 temperature of bodies. It consists of a glass tube of fine bore, partly 
 filled with mercury or spirits, and having a bulb at the bottom end, 
 and the top end sealed. 
 
 In graduating the instrument, the tube is placed in a closed 
 vessel with the steam from boiling water surrounding it, and the 
 heat causes the mercury to expand and rise in the tube ; when the 
 mercury stops rising a mark is made at the level and fixed as 212°, 
 representing the boiling point of fresh water in the atmosphere. The 
 tube is next placed in a dish containing pieces of broken ice, and the 
 cold causes the mercury to contract and fall in the tube, the point 
 when the liquid falls being marked as 32°, which is the melting point 
 of ice, or the freezing point of water. 
 
 Between the 212^ and the 32° marks, the scale is divided into 180 
 equal parts, each part representing i" of temperature. 
 w NOTE.— Mercury solidifies at -385° and boils at 725° Fahr. 
 
 Tail Shaft Corrosion. 
 
 On propeller shafts fitted with two separate liners corrosion occurs 
 at the places marked A, that is, at the end of the brass liners. This 
 is caused by galvanic action between the iron or steel of the shaft 
 and the brass of the liners in sea water, and the effect is intensified 
 by the heavy stresses thrown on the shaft when the stern rises and 
 
 
 
 
 
 
 
 
 ^ 
 
 
 fcvass 
 
 lintr 
 
 brass 
 
 llVltT 
 
 ^-l 
 
 l-A 
 
 a4 
 
 
 
 
 
 "< 
 
 
 
 
 
 
 No. 40.— Corrosion on Tail End Shaft. 
 
 falls in a heavy seaway, and the propeller and shaft strike the water. 
 When a tail shaft breaks it usually gives way at one of the places 
 marked A. 
 
 The bending stresses are concentrated at the end of the liners, 
 owing to the difference in diameter of the liners and the shaft, and 
 it will be noticed that the wasting away of the latter is due to a 
 combined mechanical and chemical action, one leading up to and 
 assisting the other. 
 
322 "Verbal" Notes and Sketches 
 
 If the sea water is prevented from coming in contact with the 
 shaft, galvanic action cannot take place, and the shaft is preserved. 
 
 Therefore all remedies for the preservation of the tail shaft consist 
 of arrangements for keeping the sea water from the shaft. The three 
 most important methods are : — 
 
 1. The brass liners carried the whole length of the shaft. 
 
 2. A rubber sleeve extending between the two brass liners, and 
 made watertight at the ends. 
 
 3. A packed gland at the stern post (outside) between the boss 
 and the stern tube, and oil let into the stern tube for the shaft to 
 run in instead of sea water, the shaft being without brass liners, and 
 running on white metal instead of lignum vitse strips (see Cedarvall's 
 patent stern tube). 
 
 Iron Shafts. — Many makers prefer good iron for tail end shafts 
 instead of steel, for the reason that under conditions of galvanic action 
 iron does not corrode so fast as steel. 
 
 Propeller Pitch. 
 
 The pitch of a propeller means the distance the propeller would 
 travel in one revolution if working in a solid nut. 
 
 As the propeller works in water, the actual advance is less, owing 
 to slip. The usual amount of slip is from 5 to 1 5 per cent. 
 
 The hollowed after surface of the blades is called the "thrust 
 surface," and the rounded forward surface the "drag surface." In 
 running ahead the after surface of the blades thrusts back the water 
 and the resultant reaction thrusts forward the steamer. 
 
 In running astern, the drag surface thrusts the water forward, and 
 the reaction resulting sends the steamer aft. 
 
 To Measure the Pitch. — With the ship in dry dock, and shaft 
 horizontal, turn the engine so that one of the blades is horizontal, 
 take a string with a weight tied to each end of it, and hang the string 
 over the blade, about two-thirds out from the boss. Now take a 
 straight-edge and fix it parallel to the shaft, and just touching the 
 bottom end of the blade where the string hangs. 
 
 The distance between the string is piece of pitch =/, and' the 
 length of string from the top of the blade to the straight-edge is 
 piece of circumference = r. Next measure from the string to the 
 centre of the boss, and multiply by 2 and by 3-1416. This will give 
 the full circumference = C, at the position of the string and straight- 
 edge ; then by proportion as follows : — 
 
 As piece of circumference : Full Circumference jj^ piece of 
 pitch : Full Pitch. 
 
 Or, as ^ : C : : / : Full Pitch. 
 
 NOTE.— If the pitch varies radially, take the pitch as described at three 
 different radii, and the mean of the three may then be taken as the average pitch. 
 
V. 
 
OF SMAFT- _. 
 
 No. 41a. -To Measure Pitch when Shaft is not Horizontal. 
 
 t dead hoiizonlal, bul is slightly inclined as in sketch, the plumb lin 
 , not apply, and steel or wood squares or straight edges should be ar: 
 shown tu obtain part pitch and part circumference, after which the full pitch can be determined 
 manner as shown in Nu. 41. 
 
 When shaft 
 of pitch measurement d' 
 
 ■ method 
 anged as 
 n exactly 
 
 No. 41. 
 
 -To Measure Pitch of Propeller. 
 
 (With Shaft Horizontal. I 
 
 / — Piece of pitch. 
 . — Piece of circumferenc 
 C%^=Full circumference at 
 R = Radius, and Radius ? 
 Then, as . : C : : 
 
 position of we 
 2X3i4i6=C. 
 ,rt ; Full pitch. 
 
 ; taken off and put on again reversed (assuming the shaft parallel at boss), then the propelle 
 ;w. but the efficiency will be reduced for ahead running, and increased for astern running. 
 
 »<- WEIGHT 
 
 ■ will still remain 
 
,,W«i»» 
 
n 
 
 t 
 
 ^ 
 
/ ,u, ii tn :*iaM>» *»««w- w.:-- V^W^Wk 
 
 9»Sa^ >' 
 
4ia.— Crank on Centre. 
 
 A. First Mark. B Second Mark. C. Centre Mark. D, Position of Guide and Shoe at each Crank Angle. 
 
General Notes and Descriptions 323 
 
 To Find the Cut-off. 
 
 To measure the distance the steam is carried on the down stroke, 
 put the crank on the top centre and mark the crosshead and c^uide, 
 take off the valve casing cover, and turn the engine round with the 
 turning gear until the valve comes up and closes the port ; when it 
 does so, or cuts off, stop the turning gear, and the distance measured 
 down from the mark on top centre to where the crosshead stops will 
 be the cut-off or distance the steam is carried. 
 
 NOTE. — The exact time of closing- the port is best determined by inserting a 
 sHp of paper into the steam port, so that the edge of the valve "nips" the 
 paper on the instant of closing the port. 
 
 Crank on Centre. 
 
 To put the crank on the top centre, first turn the engine up to near 
 the top, and mark the guide and shoe at D ; then with a trammel 
 fixed on the column, and long enough to reach the crank, mark the 
 top of the crank at A. Now turn the engine over the centre until 
 the marks on the guide and shoe come together again at D, and again 
 mark the crank top with the trammel at B. Find the centre between 
 the two marks on the top of the crank, and make a mark C, and 
 turn the engine until the mark C comes in line with the trammel 
 point. The engine will then be on the top centre. 
 
 The crank is put on the bottom centre by the same method, the 
 trammel being applied to the bottom end of the crank instead of the 
 top. 
 
 Cutting of Key Seats (see also page 232). 
 
 To mark the position of the eccentric key seats on the shaft, first 
 put the crank on the top centre, and with the eccentric gear connected 
 up, turn round the pulley until the valve is open for the required 
 top lead, and mark the shaft. Having fixed the pulley by a set pin, 
 turn the engine to the bottom centre, and easing back the set pin, 
 shift the pulley further round the shaft until the valve is open for the 
 required lead at the bottom, and again mark the shaft. Find the 
 centre between the marks on the shaft, and this will be the position 
 of the key seat. Cut the key seat, bolt on the pulley, and put a liner 
 under the rod to make up the difference of leads top and bottom. 
 
 NOTE.— If the lead is to be I inch at the top, and i inch at the bottom, the 
 liner will require to be i\ inch thick. 
 
 To Set Valve in Mid Travel. 
 
 Turn round the engine until the valve comes to its top position, 
 and mark the valve rod at the gland ; then turn the engine until 
 
r 
 
 A 
 
 JLiLL, "1 — r X^ 
 
 LX: 
 
 ^ 
 
 K li "LI 
 
 A. First Jo 
 
 '^o face page 323. 
 
General Notes and Descriptions 323 
 
 To Find the Cut-off. 
 
 To measure the distance the steam is carried on the down stroke, 
 put the crank on the top centre and mark the crosshead and t^uide, 
 take off the valve casing cover, and turn the engine round with the 
 turning gear until the valve comes up and closes the port ; when it 
 does so, or cuts off, stop the turning gear, and the distance measured 
 down from the mark on top centre to where the crosshead stops will 
 be the cut-off or distance the steam is carried. 
 
 NOTE.— The exact time of closing- the port is best determined by inserting a 
 slip of paper into the steam port, so that the edge of the valve "nips" the 
 paper on the instant of closing the port. 
 
 Crank on Centre. 
 
 To put the crank on the top centre, first turn the engine up to near 
 the top, and mark the guide and shoe at D ; then with a trammel 
 fixed on the column, and long enough to reach the crank, mark the 
 top of the crank at A. Now turn the engine over the centre until 
 the marks on the guide and shoe come together again at D, and again 
 mark the crank top with the trammel at B, Find the centre between 
 the two marks on the top of the crank, and make a mark C, and 
 turn the engine until the mark C comes in line with the trammel 
 point. The engine will then be on the top centre. 
 
 The crank is put on the bottom centre by the same method, the 
 trammel being applied to the bottom end of the crank instead of the 
 top. 
 
 Cutting of Key Seats (see also page 232). 
 
 To mark the position of the eccentric key seats on the shaft, first 
 put the crank on the top centre, and with the eccentric gear connected 
 up, turn round the pulley until the valve is open for the required 
 top lead, and mark the shaft. Having fixed the pulley by a set pin, 
 turn the engine to the bottom centre, and easing back the set pin, 
 shift the pulley further round the shaft until the valve is open for the 
 required lead at the bottom, and again mark the shaft. Find the 
 centre between the marks on the shaft, and this will be the position 
 of the key seat. Cut the key seat, bolt on the pulley, and put a liner 
 under the rod to make up the difference of leads top and bottom. 
 
 NOTE.— If the lead is to be | inch at the top, and ^ inch at the bottom, the 
 liner will require to be -^a inch thick. 
 
 To Set Valve in Mid Travel. 
 
 Turn round the engine until the valve comes to its top position, 
 and mark the valve rod at the gland ; then turn the engine until 
 
324 
 
 ** Verbal" Notes and Sketches 
 
 the valve comes to its bottom position, and again mark the rod at the 
 gland ; next divide the two marks, and set the valve to the centre 
 mark so found, which will be the exact mid position of the valve. By 
 marking the cylinder face, top or bottom, at the position of the steam 
 edge of the valve, the steam lap can be found by simply taking the 
 distance between the marks and the edge of the steam ports of 
 the cylinder. 
 
 Shaft Sighting. 
 
 To test the fairness of a line of shafting by "sighting," obtain 
 three strips of iron all the same length, and with a small hole in two 
 of them, say ^ inch in diameter, cut in each at the same distance up, 
 
 t— "bit t C. 
 
 No. 42.— Method of " Sighting " a Shaft, 
 
 and in the third one have cut a vertical slot ; now fix one strip on the 
 thrust shaft coupling, another on the tail end shaft coupling, and 
 place the other one with the vertical slot on the intermediate shaft 
 couplings turn about, and with a light behind the hole of the strip 
 on the propeller shaft coupling sight the shaft from the strip on the 
 thrust shaft. 
 
 If the light is visible at the same level through all the strips the 
 shaft is fair, but if the light is sighted higher up on the portable 
 strip the corresponding length of shaft has worn down (see sketch). 
 
 Lining Up Shafting. 
 
 A y\-inch hole is drilled through forward engine-room bulkhead ; 
 hole in stern post bridged and a yV-inch hole drilled through bridge, 
 both drilled holes to correspond with shaft centre. A light is then 
 placed forward of engine-room bulkhead hole, and it can easily be 
 
General Notes and Descriptions 
 
 325 
 
 seen through these two jV-inch holes. After-tank bulkhead hole is 
 then bridged, a ^V-inch hole drilled through bridge, and bridge 
 adjusted so that the light can be seen through these three ^V-inch holes. 
 Circles can now be described around these holes in the stern post and 
 after-tank bulkhead with the jV-inch holes for centres, bridges 
 removed, and boring bar set by circles. Of course any number of 
 intermediates may be erected before bridges are taken out, to get 
 height of seatings, &c. All errors of a sagging line are thus avoided. 
 
 To line from tail-shaft coupling, the tunnel-shaft bearings, of 
 which there is often only one for each section of shafting, are not 
 
 CRANK SHAFT 
 COUPLtNG 
 
 PADDLE SHAFT 
 COUPLING 
 
 No. 43.— Flexible Coupling. 
 
 used. Each length of shafting is blocked on two blocks in such a 
 way that the overhanging ends balance the portion between blocks, 
 otherwise the shaft will sag, throwing couplings out. Faces of 
 couplings are left a little apart for lining up, so that a very keen 
 taper wedge can be used between them. If now the after coupling of 
 after line shaft section is central with forward coupling of tail shaft, 
 and the taper wedge enters the same distance all around between their 
 faces, tail shaft and after section of line shaft are surely in line, and 
 the next length forward may be proceeded with. When all the 
 shafting is in, engine bed with crank-shaft in place is set in the same 
 way, and forward crank-shaft centre will correspond with the yV-ir>ch 
 hole drilled in forward engine-room bulkhead. Before blocks are 
 removed from under line shaft, the tunnel shaft bearings are put 
 in place. 
 
326 
 
 Verbal " Notes and Sketches 
 
 Paddle Shaft Flexible Coupling (Sketch No. 43). 
 
 Sometimes in paddle steamers allowance for the outside bearing 
 wearing down is arranged for as shown, but in this case the crank- 
 shaft, crank-pin, and webs are solid. 
 
 A hard rubber washer is fitted in between the coupling faces, and 
 the bolts fit into brass bushes in the outer or paddle shaft coupling. 
 These bushes are made large enough in diameter to give a slight 
 clearance to the bolts as shown, which thus gives flexibility to the 
 shaft. 
 
 Flaws in Shafts. 
 
 In the sketches below two flaws, A and B, are shown on the shaft, 
 one (B) running longitudinally, and the other (A) extending circum- 
 ferentially. Notice that the circumferential flaw A seriously affects 
 the strength of the shaft by decreasing the sectional area available to 
 
 B 
 
 No. 44.— Shaft Flaws. 
 
 resist torsion, whereas the flaw B, which extends along the shaft, pro- 
 duces very little difference in the area or strength. It should be 
 remembered that the strength of a solid shaft to resist torsion varies 
 as the diameter cubed. 
 
 NOTE. — The depth of a flaw can be found by either boring a hole into it or by 
 chipping out. 
 
 To Test the Fairness of Shafting. 
 
 To test if the main shafting is down, slacken back the coupling 
 bolts, and with a feeler, test the distance between the two flanges all 
 round. 
 
 To Test the Fairness of the Rocking Shaft. 
 
 To test if the pump lever rocking shaft is down at one end or the 
 other, place the levers at half stroke and disconnect the crosshead 
 links, then measure the distance between the engine crosshead pin and 
 the pin on the end of the lever on the after side and on the forward 
 
General Notes and Descriptions 327 
 
 side ; if the two measurements do not agree, one of the two brasses 
 has worn down. 
 
 Link Brasses and Pump Clearance. 
 
 If the engine crosshead h"nk brasses are tightened up, the pump 
 clearance will be increased on the top and decreased on the bottom. 
 
 If the pump crosshead link brasses are tightened up, the pump 
 clearance will be decreased on the top and increased on the bottom. 
 
 NOTE.— The foregoing assumes that the links are suspended from the engine 
 crosshead : if overhung the clearance will be reversed. 
 
 To Test the Fairness of the Piston Rod. 
 
 To test if the piston rod is working fair between the guides, ease 
 back the gland and take the distance between the guide and piston 
 rod at the top and bottom centres. 
 
 Air Pump Clearance. 
 
 To measure the air pump clearance top and bottom, put the crank 
 on the top centre ; this will place the pump on the bottom centre ; 
 then mark the rod, say at the gland. Next put the crank on the 
 bottom centre ; this will place the pump on the top centre, and again 
 mark the rod. If the pump links are then disconnected, and the pump 
 lifted against the cover and the rod marked, we will have the top 
 clearance ; and if the pump is lowered to the bottom and the rod 
 marked, it will give us the bottom clearance. 
 
 To find Length of Valve Spindle. 
 
 If the valve rod is broken and the length for a new rod required, 
 this can be found as follows : — 
 
 Turn the engine up to the top centre (see page 323) and shore up 
 the valve to the lead determined upon ; also suspend the links in line 
 with the valve spindle for the required ahead position. Now pass up 
 through the gland and valve a long length stick or rod, and mark on 
 it the distance from the under side of the valve to the centre of the 
 link block, which will therefore be equal to the required length of 
 valve spindle between these points. The position of the washer or 
 collar under the valve, and the position of the nuts above the valve, 
 can also be marked on the stick, and the necessary extra length of 
 rod allowed for accordingly. 
 
 To find the Connecting Rod Length. 
 
 To find the length of the connecting rod, put the engine at half- 
 stroke, and measure from the centre of the crosshead pin to the centre 
 of the shaft. 
 
328 "Verbal" Notes and Sketches 
 
 To find the Eccentric Rod Length. 
 
 To find the length of the eccentric rod (the pulleys being on the 
 shaft), put the crank on the top centre, and set the valve to the required 
 lead, then measure from the centre of the link block to the top of the 
 eccentric strap ; this gives the exact length of the eccentric rod. 
 
 Another method is as follows : — Place the valve at mid-stroke, and 
 measure the distance between the centre of the link block to the centre 
 of the shaft ; then subtract from this half of the pulley diameter and 
 the thickness of the eccentric strap at the place where the rod joins 
 it : this will leave the length of the rod. 
 
 Piston Clearance. 
 
 The piston and cylinder cover clearance at top is usually about 
 f inch, and at bottom about | or § inch. 
 
 The bottom clearance requires to be more than the top, to allow 
 for the wear down of the top end and bottom end " brasses " or " white 
 metals." 
 
 To Measure the Piston Clearance. 
 
 It is measured by turning the crank to the top centre and marking 
 the shoe and guide, then disconnecting the crosshead brasses and lift- 
 ing or wedging up the piston until it touches the cover ; then again 
 mark the guide, and the distance between the marks will be the top 
 clearance. 
 
 The bottom clearance is measured in a similar manner. 
 
 Excessive Clearance. 
 
 Excessive clearance means a distinct loss of heat, because the 
 steam must first fill up the clearance spaces before it can do work on 
 the piston, and, when the exhaust opens, this steam is exhausted out 
 of the cylinder. 
 
 Prevention of Ridge in Cylinder. 
 
 Cylinders are usually made bell-mouthed at the bottom to prevent 
 the piston wearing a ridge on the cylinder or liner. 
 
 Defective Check Valve. 
 
 With two boilers, if the check valve of one gets so damaged that it 
 cannot be shut and the boiler is getting too much feed, regulate the 
 feeding by the stop valves, partly shutting down the one on the boiler 
 which is getting too much water and opening up the one on the 
 boiler that is not getting enough of feed water. The difference of 
 evaporation will then keep the water from entering the one boiler and 
 allow it to enter the other. The same result can be obtained by firing 
 one boiler more than the other. 
 
General Notes and Descriptions 329 
 
 \J Tube in Pressure and Vacuum Gauges. 
 
 The gauge tube is of flattened section, as shown in the sketch, 
 and when acted on by increase of pressure, the tube section tends 
 to become more circular, but when acted on by decrease of pressure 
 the tube section tends to become more flattened. This difference in 
 section produces a reaction, the effect of which is to straighten out 
 the tube when the tube becomes more circular in section, and to curl 
 up the tube when the section becomes flatter. For pressure, the tube 
 loses diameter in one direction and gains diameter in the other, being 
 forced more into a circular shape by the action of the steam pressure, 
 whereas in a vacuum gauge, for example, the reverse effect takes place, 
 that is, the tube becomes less circular in section, and takes its length 
 on a more curved line in consequence. 
 
 It will easily be understood that with the tube quite flat in section 
 the curvature of its length would be at a maximum, and with the 
 tube fully circular in section its line would naturally be straight. 
 
 Therefore (ij under pressure the long diameter of the tube 
 decreases, and the short diameter increases, and this results in the 
 tube length straightening out and indicating (by means of the small 
 quadrant and toothed gearing) increase of pressure. 
 
 (2) Under decrease of pressure the long diameter increases and 
 the short diameter decreases, and this results in the tube length 
 forming a smaller curve, and indicating decrease of pressure, or 
 
 vacuum. 
 
 o 
 
 SECTION 
 No. 45.— Pressure Gauge Tube. 
 
 I NOTE.— If the pressures are equal inside and outside of the U tube, the gauge 
 will register o : therefore when the atmospheric pressure increases, the gauge 
 will register less pressure in like proportion, although the actual pressure in the 
 tube is exactly the same as before : similarly, if the atmospheric pressure decreases, 
 the gauge will register more, although the actual pressure in the tube will be the 
 same. 
 
 Main and Bilge Injection (Sketch No. 46). 
 
 The^ illustration shows the usual arrangement of the main and 
 bilge injection connections. 
 
 Observe that the bilge injection pipe leading from the bilge strum 
 is connected to the main injection pipe by means of a non-return 
 valve, which is peculiar in the fact that the valve and spindle are 
 separate. The valve can be shut down but not lifted up by the 
 screwed spindle, as only the pressure of the water below acts to lift 
 the valve. 
 
Verbal" Notes and Sketches 
 
 MAIN 
 INJECTION 
 
 _.ffi- 
 
 BILGE 
 INJECTION 
 (NON-RETURN VALVE)- 
 
 "TO CIRCULATI NG # ^ 
 PUMP """^ ^ 
 
 STRUM 
 
 No. 46— Injection Connections. 
 
 This type of valve is advisable, as it prevents the return of water 
 back to the bilges. 
 
 NOTE.— If, when using the bilge injection, the strum becomes choked up, cut 
 the pipe above the strum, and fix a basket over the end of the pipe, or close up 
 the pipe end and pierce a number of holes through the pipe. 
 
 Thrust. 
 
 With a right or left hand propeller and the engines going ahead, 
 the thrust is on the after side of the thrust block rings, and on the 
 forivard side of the shaft collars. 
 
 With a right or left hand propeller and the engines going astern 
 the thrust is on the forward side of the thrust block rings, and on the 
 after side of the shaft collars. 
 
General Notes and Descriptions 331 
 
 The total or combined effective horse-power of the engines come 
 on the thrust block and is transmitted to the ship's hull through the 
 holding down bolts. 
 
 The following are the points in connection with the thrust block 
 demanding the most careful attention : — 
 
 1. Proper lubrication, 
 
 2. Proper adjustment of the rings. 
 
 3. Secure bolting down to the ship. 
 
 No. 47.— Thrust Block (Horse-Shoe Type), with bearing at each end 
 
 No. 48.— End View of Thrust, showing Oil and Water 
 Service, &c. 
 
 Crank- Pin and Piston Travel. 
 
 The travel of the crank-pin is about one-half more than that 
 of the piston, for while the piston travels two strokes (up and 
 
3^^ 
 
 " Verbal " Notes and Sketches 
 
 down), the crank-pin travels round a circle, the diameter of which is 
 equal to the stroke. 
 
 The speed of the crank-pin is about one-half more than that of 
 the piston, or in exact proportion to the extra distance it has to travel. 
 
 Flaws in LP. Crank-Pin. 
 
 The after end of the L.P. crank-pin often develops flaws, usually 
 due to the wearing down of the after lengths of shafting throwing 
 heavy stresses on the L.P. shaft. 
 
 A built shaft is not so liable to flaws as a solid shaft, owing to 
 the webs and pins being separate pieces ; also with a built shaft, if 
 flaws develop on the pin a new one can be fitted without entailing 
 the condemnation of the whole shaft. 
 
 Loose Eccentric. 
 
 This type of single eccentric is not keyed on the shaft, but is 
 loose circumferentially, and is driven round by a stop on the shaft, 
 striking a corresponding stop on the pulley. 
 
 Rod 
 
 No. 49.— Single Eccentric. 
 
 The position of the centre of the pulley stop is found by tne same 
 used in finding the key seat for ordinary eccentrics 
 
 as IS 
 
 method 
 
 (see page 232), 
 
 the same 
 
General Notes and Descriptions 
 
 333 
 
 The balance weight is to counterbalance the weight of the broad 
 side of the pulley, and is fitted on the narrow side. 
 
 The top of the eccentric rod has a gab or clutch, which, when in 
 gear, fits on a pin in the end of the valve spindle, and gives the 
 motion to the valve. In reversing, this gab is thrown off the pin by 
 a hand lever, and the valve is put in the reverse position by another 
 hand lever, and when the shaft travels round, and the shaft stop 
 strikes the pulley stop on the other side, the gab is again put in gear 
 with the valve spindle, and the engine continues to run in that 
 direction. A spring is often fitted on the rod to force the gab on to 
 the pin. 
 
 wood"^ 
 
 X 
 
 WOOD 
 
 No. 50.— L. P. Cylinder with Top Ports Closed Up. 
 
 Broken L.P. Cylinder Cover. 
 
 If the L.P. cover breaks and cannot be repaired, the L.P. engine 
 can be run on the atmospheric principle, that is, with atmospheric 
 pressure on the top side, and steam on the under side. 
 
 To arrange for this, take off the L.P. valve chest cover, draw the 
 valve, and drive wooden plugs into the two top steam ports, taking 
 care that the plugs are clear of the face : then replace valve and cover 
 and go ahead. 
 
 The atmospheric pressure will now assist the down stroke of the 
 piston, and the steam pressure, as before, will act on the up stroke. 
 24 
 
334 
 
 "Verbal" Notes and Sketches 
 
 As the pressure carried in the L.P. chest is often only a few 
 pounds above the atmosphere, the difference in pressure on each 
 side of the piston will not, in most cases, be excessive. 
 
 No. 51— LP. Card with Top Ports Closed Up. 
 
 With the top steam ports closed up the bottom ports will receive 
 steam of a higher pressure than before, as shown by the dotted line, 
 and the back pressure on the M.P. piston will be more in proportion. 
 Observe that the atmospheric line now represents the top diagram. 
 
 Sight Feed Lubricator. 
 
 The principle of construction is that of displacement. Oil being 
 lighter than water rises to the surface of the water, and is forced 
 down the internal tube to the sight glass and steam chest. 
 
 NOTE.— The specific gravity of oil is -9, and of water i. 
 
 No. 52. — Improved Sight Feed Lubricator. 
 (By Messrs Schaffer & Budenberg Limited.) 
 
 Action. — Steam from the steam pipe condenses in the small con- 
 denser shown on the left of the sketches, and the water of condensa- 
 tion entering the bottom of oil chamber displaces the oil, which rises 
 and flows down the small internal tube. 
 
 1 
 
General Notes and Descriptions 335 
 
 The oil then enters the sight tube by the nozzle shown, and passes 
 up the sight feed tube in drops, from the top of which it is forced into 
 the steam chest. Sometimes the condenser is formed of a copper coil 
 placed a good height above the lubricator. 
 
 Instructions for Using. — The oil chamber is charged by unscrewing 
 the plug (7. The sight feed glass should then be filled up with water 
 or a solution of salt and water (concentrated). To start the lubricator 
 first open the valve <^, then gradually open the valve c, and the drops 
 of oil will be seen ascending through the water in the glass. Valve c 
 regulates the amount of lubrication desired. When the engine is 
 stopped, the two valves d and c must be closed. 
 
 Hydraulic Accumulator. 
 
 As will be seen from the sectional drawing, the accumulator piston 
 is steam loaded by a reduced pressure of 80 lbs. per square inch. 
 The pumping engine first of all pumps up the ram against the steam 
 pressure, and when the piston reaches the top the pumps are auto- 
 matically stopped by a rod and lever connected to the ram. The 
 water is then stored up at a pressure of 800 lbs. per square inch and 
 ready for use in the cranes, hoists, &c. The relative area of ram and 
 piston being as i is to 10, a pressure of 80 lbs. per square inch on 
 the one gives a pressure of approximately 800 lbs. per square inch on 
 the other. As the water pressure is used in the cranes the ram and 
 piston descend, until at a certain position the automatic gear in 
 connection acts and starts the pumping engine : the ram is then 
 raised back again to its former position. 
 
 NOTE.— The ram is packed by a leather ring which constitutes the best hydraulic 
 packing yet discovered. The water pressure inside the ring forces it out against the 
 ram and against the chamber. 
 
 The crane consists of three rams, one large central lifting ram and 
 two smaller side rams for slewing round the crane post. 
 
 The water is admitted by a hand valve to each ram as required, 
 and after doing the work of lifting or slewing exhausts by return 
 pipes back to the supply tank of the pumping engine (see sketch 
 of accumulator). 
 
 When the water is admitted by the hand valve the ram is raised, 
 and when exhausted the ram is lowered, but if the valve is put in 
 mid position the ram is locked and therefore maintains the position 
 it may be in at the time. 
 
 Advantages. 
 
 Among other advantages possessed by the hydraulic syjtem, the 
 following may be specially mentioned : — 
 
TO CRANES 
 
 No. 53.— Hydraulic Accumulator. 
 
 (Brown Bros,, Edinburgh.) 
 
 336 
 
General Notes and Descriptions 
 
 ZZ7 
 
 (i.) Great smoothness of working. 
 (2.) Quickness of handling. 
 
 (3.) Absence of noise in working cargo ; a consideration in 
 passenger steamers. 
 
 LfFTINC 
 
 No. 54. — Hydraulic Crane. 
 
 (Brown Bros., Edinburgh.) 
 
 Brown's Patent Combined Steam and Hydraulic Reversing 
 Engine. 
 
 The engine as shown is attached to the bedplate or column of the 
 main engine by the oscillating joint A formed on the end of the 
 
338 "Verbal" Notes and Sketches 
 
 steam cylinder. In this cylinder is fitted a piston B with rod C, upon 
 which is cottered a block piston D, working in the hydraulic cylinder 
 E, the fluid being allowed to pass from one end to the other of the 
 cylinder E by means of a small hole bored in the piston D. The 
 rod C passes through stuffing boxes on the steam and hydraulic 
 cylinders, terminating in a joint F, which lays hold of the weight shaft 
 lever G. The lever is carried out to the joint H, upon which works 
 the rod and rack I geared into the pinion J, both being shrouded to 
 the pitch line. Upon the pinion shaft is keyed a worm-wheel K, 
 which is actuated by the bronze worm L, this being revolved by the 
 hand-wheel M. The worm and hand-wheel shaft are thrown out of 
 gear with the worm-wheel K by the eccentric N, which is turned by 
 the handle O, and held in position by the checkpin shown in dotted 
 lines. When the hand-wheel and worm are disengaged, the rack and 
 worm-wheel are free to revolve on the engine, making a stroke either 
 way. This hand gear, therefore, forms no integral part of the starting 
 engine, and is unaffected by any derangement of either hydraulic or 
 steam cylinder or the steam valve. 
 
 A locking arrangement on the hand gear is provided, so that the 
 main valve gear can be linked up in any position of the ahead stroke. 
 This consists of a pawl P, which is made to engage the teeth of the 
 rack, and the engine is held up against the pawl by means of the slide 
 valve being left slightly open to steam. The pawl is provided with a 
 balance weight Q, so that, on the engine being reversed for the astern 
 position, immediately pulls the pawl out of gear. 
 
 The hydraulic cylinder is kept charged by means of the condensed 
 steam in the bottom of the valve casing being driven by the steam 
 through the non-return valve R, and led by a small copper pipe, as 
 shown, into the lower end of the cylinder. 
 
 The engine is handled by a simple reversing lever S, which is 
 connected by two links to the fulcrum of a lever at T. This lever has 
 its end extended to U, which is connected direct by a link to the 
 valve spindle V. A curved link W is securely attached to the lever 
 T U, and on this there slides a block X, which is carried from 
 the piston rod. 
 
 The action of this valve gear is as follows : — When the lever S is 
 pulled into the ahead position, the lever T U, which is attached to the 
 curved link W sliding in the block X, is depressed. The valve spindle 
 is also moved down, opening the top end of the cylinder to steam. 
 The piston rod now begins to move down, and carries with it the 
 guide block X, which forces the end of curved link to move into the 
 centre line of the block, thus moving the point U of the lever T U in 
 an upward direction, the fulcrum at T by means of the reversing 
 handle S being held stationary. In this way the valve spindle V is 
 brought back into its original position, thus bringing the engine to 
 rest. The same operation is performed for the astern or any 
 intermediate position. 
 
t 
 
 General Notes and Descriptions 
 
 No. 55.— Brown's Patent Combined Steam and Hydraulic 
 Reversing Engine. 
 
340 "Verbal" Notes and Sketches 
 
 Steering Gears. 
 
 "2 >» 
 
 O i) 
 
 (fi O 
 
 r- 00 
 
 t-i 
 
 a 
 O 
 
 bo 
 
 (U 
 
 6 
 IS 
 
 ^ ^ 
 
 •s 
 
 Ui 
 
 
 3 
 
 a 
 
 
 fe 
 
 J3 
 
 a 
 
 •n 
 
 
 •H 
 
 •o 
 
 F 
 
 3 
 
 iJ 
 
 o. 
 
 Ui 
 
 w 
 
 (/} 
 
 S 1) o 
 2 :i2 •ij 
 
 J5 =• 
 
 M 
 
 .3^1 
 
 JG 3 3 
 
 U O K 
 " ef to 
 
 C 4) O 
 
 4> > -M 
 
 t> (a (L> 
 
 ao g 
 
 S fe b< 
 
 *j ^ 4) 
 
 4J l-i "^ 
 
 ^- "* 
 
 G P c 
 
 (U 
 
 
 •a 
 o 
 
 u 
 
 O 
 
 rt u '2 
 o o « 
 <u "S « 
 
 J3 . -"^ 
 
 o c 
 
 tJ a lU 
 
 (A 0) 
 
 «1 -O 
 
 (C 
 
 4id 
 
 P o c 
 
 ho 
 
 l2 ^ 
 
 J3 (U o 
 
 H . 
 O "O 
 
 5? 2i 
 

T^ 
 
 No. 58.— Steering Engine Transmission Gear. 
 
 f, Horizontal shaft connecting steering- wheel and engine. 
 
 2, Vertical shaft connecting (by bevel wheels) to control valve lever. 
 
 3, Hunting or return gear from engine worm to control valve. 
 
 4, Control valve. 
 
 5, Engine worm. 
 
 6, Worm wheel of chain drum. 
 
 NOTE.— The small spindle connected to the control valve lever gears into wheel 3 by a screw. 
 
 iTo fa<e page 341 
 
General Notes and Descriptions 
 
 341 
 
General Notes and Descriptions 
 
 341 
 
342 
 
 Verbal " Notes and Sketches 
 
 Steering Gear Engines. 
 
 The majority of patent steering gear engines are fitted with three 
 valves — a central control valve and two piston valves or slide valves, 
 one for each cylinder of the engine. The control valve distributes the 
 steam to the engine valves so that the gear may run either to port or 
 starboard as required, and this being the case it will be observed that 
 each piston valve or slide valve requires only one eccentric, the control 
 valve acting as the reversing gear. The piston valves or slide valves 
 have little or no steam lap, so that the steam is carried for the full 
 length of the stroke, and to allow of this the eccentric keyseats are 
 cut at right angles to the cranks. 
 
 Control Valve. — This valve is sometimes a flat valve, but more 
 generally a round or piston valve. It is operated directly (i) by hand 
 from the steering wheel on the bridge, and (2) automatically by a 
 counteracting return gear from the chain drum or crank-shaft of the 
 steering engine. 
 
 No. 59.— Steering Gear Engine Valves. 
 
 When the engine is stationary, if the hand-wheel is turned, the 
 control valve opens and starts the engine ; this again has the effect of 
 bringing into play the return gear in connection with the crank-shaft, 
 so that as the hand gear (if still moving) tends to open the control 
 valve the return gear tends to close it : if both gears, hand and auto- 
 matic, run at the same speed the control valve remains open, but if the 
 hand gear is stopped the automatic gear shortly afterwards brings the 
 engine to a stop by closing the control valve. From this it will be 
 seen that to keep the steering gear running the hand-wheel must 
 be kept in motion, otherwise the automatic gear will bring the control 
 
jH 1o no; 
 
 -,^ - iii ii i ii . . -. Wi<i. 
 
STEAM 
 
 STEAM SHEWN THUS , ^ 
 
 EXHAUST .. '• . > 
 
 E. EXHAUST PORT. 
 No 59a.— Steering Gear Valves. 
 
 Steam is being admitted to the cylinder from the centre of piston valves, and is exhausting to ends of same, 
 back to exhaust port E, and the direction of engine rotation is as shown. 
 
 NOTE. -In this type of gear the steam is admitted from the ends of the control valve for both directions 
 of running, as clearly shown in the sketches. 
 
 [TV/a^/Of j4S- 
 
1 
 
 f 
 
 //y^ 
 
 
 
 ■\'. / 
 
 .^■«v:iiV' -i..2U ^fin333<i 
 
otation. 
 
 yV' ''''•'.■.'«"' 
 
 34?- 
 
r— - •-f-'-v 
 
 ^ 
 
 f 
 
 2UHT J 
 
 I* 
 
STEAM 
 
 
 - ..r^-rrrf^—rr .r x B; 
 
 /'^VVVKvXNXXXXXXXNNXVxXXWAv 
 
 STEAM SHEWN THUS, > 
 
 EXHAUST •• " , -> 
 
 E. EXHAUST PORT. 
 
 No. 59b —Steering Gear Valves. 
 
 SteBm is being admitted to the cylinder from the ends of the piston vaives, and is exhausting to centre ol 
 •anie back to exhaust port E ; the direction of engine rotation is as shown, and is now reversed. 
 
 I To face poEc 343. 
 
General Notes and Descriptions 343 
 
 valve back to mid-position and thus stop the gear. As before stated, 
 the control valve does away with the necessity of having two eccentrics 
 for each valve, one only being required, as the reversal of rotation is 
 obtained by the action of the control valve. 
 
 Engine Valves. — The valves of the engine are generally of the hollow 
 piston type, although in some cases special flat valves are used, as in 
 the gear of Messrs Alley & M'Lellan. 
 
 The hollow piston valves are arranged so as to receive steam at 
 the ends and exhaust in the centre, or, to receive steam at the centre 
 and exhaust at the ends, the ports being suitably cast to admit of this 
 (see sketch of control valve). 
 
 Action of Valves. — If the steam is admitted to the ends of the piston 
 valves by the control valve C being moved in the direction of A, the 
 cylinders obtain the steam from the ends and the exhaust takes place 
 in the centre of the piston valves, the engine running so that the 
 rudder is brought over to, say, the port side ; but if the steam is 
 admitted to the ce^itre of the piston valves, by the control valve C 
 being moved in the direction B, then the cylinders receive steam from 
 the centres of the valves and exhaust at the ends : the direction of 
 motion being thus reversed, the rudder is brought over to the centre 
 again and so to the starboard side. 
 
 Types of Gear. — The following five types of steam steering gear 
 engines in general use will give a very good idea of the principle of 
 working and of the mechanism employed by some of the best 
 makers of this important piece of auxiliary machinery. 
 
 It will be noticed that, with the exception of Messrs Hastie's 
 gear, the control valve is moved laterally to open and close the ports, 
 but in the gear produced by Messrs Hastie & Co. the control valve 
 moves round somewhat after the manner of a Corliss valve ; the 
 spindle therefore of this gear does not move laterally, but simply 
 revolves for part of a ircle, as will be seen by examining the 
 sketch. 
 
 Steering Gear by Messrs Caldwell & Co. 
 
 In this gear the control valve is opened or closed by a cam in 
 connection with the "sun and planet" motion contained in the brass 
 casing. The toothed wheel A is in connection with the hand-wheel 
 on the bridge, and the toothed planet wheel B is in one with the 
 cam, while the toothed casing C is in connection by bevel wheels 
 with the chain drum. 
 
»MMiT2 
 
 -* 
 
 
 
 
 
 ^^^^^^ 
 
 .f -- 
 
 jIIII 
 
 _j 
 
 \ 
 
 of Rotation, i 
 
 1W3Ha MA 318 
 
 rauAHxa 
 
 
 Jut /tri^-.-urf-M Oj *?ft<J S.fK-*"' 
 
 tojpr 343. 
 
 I 
 
General Notes and Descriptions 343 
 
 valve back to mid-position and thus stop the gear. As before stated, 
 the control valve does away with the necessity of having two eccentrics 
 for each valve, one only being required, as the reversal of rotation is 
 obtained by the action of the control valve. 
 
 Engine Valves. — The valves of the engine are generally of the hollow 
 piston type, although in some cases special flat valves are used, as in 
 the gear of Messrs Alley & M'Lellan. 
 
 The hollow piston valves are arranged so as to receive steam at 
 the ends and exhaust in the centre, or, to receive steam at the centre 
 and exhaust at the ends, the ports being suitably cast to admit of this 
 (see sketch of control valve). 
 
 Action of Valves. — If the steam is admitted to the ends of the piston 
 valves by the control valve C being moved in the direction of A, the 
 ^ cylinders obtain the steam from the ends and the exhaust takes place 
 in the centre of the piston valves, the engine running so that the 
 rudder is brought over to, say, the port side ; but if the steam is 
 admitted to the centre of the piston valves, by the control valve C 
 being moved in the direction B, then the cylinders receive steam from 
 the centres of the valves and exhaust at the ends : the direction of 
 motion being thus reversed, the rudder is brought over to the centre 
 again and so to the starboard side. 
 
 \ 
 
 Types of Gear. — The following five types of steam steering gear 
 engines in general use will give a very good idea of the principle of 
 working and of the mechanism employed by some of the best 
 makers of this important piece of auxiliary machinery. 
 
 It will be noticed that, with the exception of Messrs Hastie's 
 gear, the control valve is moved laterally to open and close the ports, 
 but in the gear produced by Messrs Hastie & Co. the control valve 
 N moves romid somewhat after the manner of a Corliss valve ; the 
 spindle therefore of this gear does not move laterally, but simply 
 revolves for part of a ircle, as will be seen by examining the 
 sketch. 
 
 Steering Gear by Messrs Caldwell & Co. 
 
 In this gear the control valve is opened or closed by a cam in 
 connection with the "sun and planet" motion contained in the brass 
 casing. The toothed wheel A is in connection with the hand-wheel 
 on the bridge, and the toothed planet wheel B is in one with the 
 cam, while the toothed casing C is in connection by bevel wheels 
 with the chain drum. 
 
344 
 
 "Verbal" Notes and Sketches 
 
 FROM 
 STEERING— H 
 WHEEL 
 
 CONTROL 
 VALVE £^ 
 
 ^ 
 
 GUIDE 
 CAB 
 
 Sun and Planet Motion. 
 
 No. 60.— Steering Gear by Messrs Caldwell & Co. 
 
General Notes and Descriptions 
 
 345 
 
 Action. — (i.) If wheel A is moved round by the steering wheel with 
 C stationary^ B moves round the casing and opens the control valve, 
 thus starting the engine and setting C in motion. 
 
 (2.) If A is stopped, C moves round in the reverse direction, carry- 
 ing B and the cam back again until the control valve is brought to 
 mid-position and the engine stopped. 
 
 (3.) If A and C move at the same relativ'e speed the control valve 
 u'ill remain open and the engine keep running, but if the speed of C 
 exceeds that of A the control valve will close and the engine stop. 
 
 In the same way, to open the control valve further the speed of 
 A must exceed that of C. 
 
 FROM 
 STEERING wheel: 
 
 TO CONTROL 
 VALVE 
 
 No. 61.— Steering Gear by Messrs Bow, M'Lachlan, & Co. 
 
 steering Gear by Messrs Bow, M'Lachlan, & Co. 
 
 In this gear the control valve is moved horizontally by the spindle 
 i turning in the nut wheel C and so acting on the lever in connection 
 nth the control valve spindle to move it from mid-position to the 
 ght or to the left as required. The bevel wheel actuated from 
 le steering wheel turns the spindle B, which being screwed into the 
 
346 "Verbal" Notes and Sketches 
 
 nut C causes a lateral movement. The feather shown on the spindle 
 allows the spindle to move horizontally without turning, if actuated 
 by the nut wheel C travelling round. 
 
 Action. — (i.) If wheel A is moved round by the steering wheel with 
 C stationary, the spindle B turns and moves either in or out of the 
 nut wheel C and opens the control valve, thus starting the engine 
 and setting wheel C in motion. 
 
 (2.) If A is stopped, C moves round and causes the spindle to 
 travel (without turning) back again to mid- position of the control 
 valve, thus stopping the engine. The feather and slot referred to 
 allow of this taking place. 
 
 (3.) If A and C move round at the same relative speed the control 
 valve will remain open and the engine keep running, but if the speed 
 of C exceeds that of A the control valve will close and the engine 
 stop. 
 
 In the same way, to open the control valve further the speed of 
 A must exceed that of C. 
 
 Steering Gear by Messrs Davis & Co. 
 
 In this gear an expansion or regulating steam vah'e is fitted in 
 addition to the control valve. The expansion valve is operated by 
 a nut, which travels up or down the vertical shaft connecting the 
 steering wheel and control valve spindle and opens the expansion 
 valve a certain amount on either side, admitting the steam to the 
 control valve in proportion to the amount of work to be done. 
 
 The spindle B of the control valve works in or out of the nut 
 wheel C as required, and admits the steam to the main valves of the 
 engine. The wheel A is connected to the spindle B by a slot and 
 feather which allows of a lateral movement of the spindle B when it 
 is not turning. 
 
 Action. — (i.) If wheel A is moved round by the steering wheel the 
 spindle B moves either in or out of the nut wheel C and opens 
 the control valve, thus starting the engine and setting wheel C in 
 motion. 
 
 (2.) If A is stopped C moves round and causes the spindle B to 
 travel (without turning) back again to mid-position of the control 
 valve, thus stopping the engine. The feather and slot referred to 
 allow of this taking place. 
 
 (3.) If A and C move round at the same relative speed the control 
 valve will remain open and the engine keep running, but if the speed 
 of C exceeds that of A the control valve will close and the engine 
 stop. 
 
 In the same way, to open the control valve further the speed of 
 A must exceed that of C. The expansion valve is arranged to open 
 when full steam is required in the engine. 
 
General Notes and Descriptions 
 
 347 
 
 o 
 U 
 
 to 
 ■> 
 
 Q 
 
 w 
 u. 
 
 Vi 
 
 o 
 
 ho 
 c 
 
 *n 
 
 6 
 
34^ 
 
 "Verbal" Notes and Sketches 
 
 Steering Gear by Messrs Alley & M'Lellan. 
 
 In this gear the spindle B moves horizontally for a small distance 
 in or out of the teeth of the bevel wheels, which are cut specially deep 
 to allow of this, a"nd, acting on the lever in connection with the 
 control valve spindle, moves the valve to right or left as required. 
 The small travel of the spindle B is increased at the control valve 
 
 FROM 
 STEERING^ 
 WHEEL 
 
 CONTROL 
 VALVE 
 
 DEEP 
 TEETH 
 PINION WHEEU, 
 >. FORMING NUT 
 
 B 
 
 THE SHAFT 
 
 TRAVELS LATERALLY 
 
 < *■ 
 
 . FIXED C 
 TO SHAFT 
 
 CONNECTS 
 TO PINION 
 
 No. 63.— Steering Gear by Messrs Alley & M'Lellan. 
 
 by the leverage obtained. The pinion wheel C, which gears with the 
 chain drum wheel, forms the nut in which the spindle travels. 
 
 Action. — (i.) If wheel A is moved round by the steering wheel with 
 C stationary, the spindle B moves horizontally to right or left and 
 opens the control valve, thus starting the engine and setting C in 
 motion. 
 
 (2.) If A is stopped C moves round, causing B to move back 
 again until the control valve is brought to mid-position and the 
 engine is stopped. 
 
 (3) If A and C move round at the same relative speed the control 
 valve will remain open and the engine keep running, but if the speed 
 
General Notes and Descriptions 349 
 
 of C exceeds that of A the control valve will close and the engine 
 stop. 
 
 In the same way, to open the control valve further the speed of 
 A must exceed that of C. 
 
 Steering Gear by Messrs Hastie & Co. 
 
 B In this gear the control valve moves round on its axis instead of 
 
 ■ravelling laterally as in the others, and so opens the ports to the 
 
 Bcentre or to the ends of the engine valves. The control valve 
 
 mechanism consists of three bevel wheels, one of which travels 
 
 round the other two and operates the rolling quadrant connected 
 
 to the control valve. The left-hand bevel wheel of the three is 
 
 keyed to the rotating spindle actuated by the steering wheel, and 
 
 the right-hand bevel wheel is keyed to the worm-wheel, which, 
 
 observe, is clear of the spindle. The top bevel wheel B is free, and 
 
 is one with the rolling or " tumbling " quadrant which connects by 
 
 : teeth to the control valve spindle to move it round to right or left 
 
 as required. 
 
 It will thus be seen that the top wheel B travels round between 
 I the teeth of the other two bevel wheels. With B at top the control 
 i valve is in mid-position and therefore closed, but if it travels down 
 ! on either side the control valve is opened. 
 
 Action. — (i.) If A is moved round by the steering wheel with C 
 stationary, wheel B travels round and down between the other two 
 bevel wheels and opens the control valve, thus starting the engine 
 and setting C in motion. 
 
 (2.) If A is stopped C moves round in the reverse direction, causing 
 B to travel back and up again to the top position, so that the control 
 valve is closed and the engine stopped. 
 
 (3.) If A and C move round at the same speed one counterbalances 
 the other, and the control valve will remain open and the engine 
 ■ keep running, but if the speed of C exceeds that of A the control 
 valve will close and the engine stop. 
 
 In the same way, to open the control valve further the speed of 
 i A must exceed that of C. 
 
 NOTE. — In all of the foregoing types of steering gear engines a limit is fixed 
 to the running of the engine by means of "stop" arrangements, which prevent 
 damage to the steering gear in general. The "stops" check the travel of the 
 rudder chains beyond a fixed point. 
 
 It should be noted that when the steamer is going ahead, say at 
 full speed, with the rudder hard over to either port or starboard, the 
 friction of the steering gear prevents the chain barrel from revolving, 
 and so allowing the rudder to slip back again to mid-position. This 
 ■will perhaps be understood when it is remembered that though the 
 worm may cause the worm-wheel to revolve, it is almost a mechanical 
 
 2^ 
 
350 
 
 "Verbal" Notes and Sketches 
 
 '^ m\ \\ \ i ////^i^ 
 
 o 
 U 
 
 (^ 
 
 '■Xj 
 (0 
 
 X 
 
 VI 
 Ui 
 
 w 
 (/) 
 
 O 
 
 bo 
 
 C 
 •«^ 
 
 u 
 
 4) 
 C/} 
 
 d 
 
 2: 
 
a. gicaiei diii^ic ui i uuuci Laii uc cuidiij^cu lui, ii iici.c.is,d.iy. ± lus 
 j[ does away with any need for disconnecting the control gear when 
 I using the hand or other gear for moving the rudder. 
 
General Notes and Descriptions 351 
 
 impossibility for the worm-wheel to cause rotation of the worm, in 
 
 fact, the teeth would give way first. 
 
 Supposing, however, that the worm-wheel and barrel did revolve 
 
 and cause the worm to go round, the effect would be to set in operation 
 
 the control valve, which, opening, would then start the steering engine 
 
 to run in the opposite direction, and thus prevent further movement 
 
 of the chain barrel. 
 
 t 
 
 NOTE. — By having two cylinders and the valves for each without steam lap, 
 
 certainty of action is ensured, as one or other of the cylinder ports will always be 
 
 open to receive steam, and so effect instant starting of the gear. Also, the key seats 
 
 being at right angles to the crank, this allows the engine to run either way as 
 
 required. 
 
 Description of Brown's Patent Steam Tiller. 
 
 (Direct-Geared Type.) 
 
 This type of gear, which contains many improvements over the 
 older designs of direct gears, has been introduced specially for ships 
 that require a smaller power of gear than the 1905 design with 
 countershaft. The general arrangement is similar to the old direct 
 gear, except that the worm-wheel has been considerably increased 
 in diameter, and the worm is now double-threaded. The oil pumps 
 are worked direct from the eccentrics, and placed in a well at the 
 bottom of the engine pan. The friction clutch is increased in size, 
 so as to make it more powerful. Brown's patent economic valve, 
 which absolutely shuts off steam every time the engine comes to 
 rest, is also fitted. The great advantage possessed by this valve is 
 that, should dirt or any foreign matter get in so as to obstruct its 
 working, it can only remain in the open position, so that the gear 
 does not become disabled, and would work under the same conditions 
 as an ordinary steering gear without this attachment. The cut-off 
 gear Q embodies the 1907 patents, with which no stops on the valves 
 are ever reached, thus preventing any strain or damage to the gear 
 by forcing over the telemotor when no steam is on the engine. This 
 gear gives a very quick opening at the commencement of the move- 
 ment of the control gear, and the motion of the valve is gradually 
 reduced to practically nil, though the control gear moves uniformly. 
 The same thing occurs in closing — that is, it commences to close 
 very slowly, and just at closing the motion is very quick and decided. 
 This gives a very fine and delicate control of the gear without any 
 danger of reaching the stops on the control valve or its gear. With 
 the standard design and a rudder angle of 40'', it is possible, when 
 there is no steam on the gear, for the tiller to be hard over in one 
 direction while the telemotor is pulled hard over to the other ; and 
 a greater angle of rudder can be arranged for, if necessary. This 
 does away with any need for disconnecting the control gear when 
 using the hand or other gear for moving the rudder. 
 
^ 
 
General Notes and Descriptions 351 
 
 impossibility for tlie worm-wheel to cause rotation of the worm, in 
 fact, the teeth would give way first. 
 
 Supposing, however, that the worm-wheel and barrel did revolve 
 and cause the worm to go round, the effect would be to set in operation 
 the control valve, which, opening, would then start the steering engine 
 to run in the opposite direction, and thus prevent further movement 
 of the chain barrel. 
 
 NOTE. — By having two cylinders and the valves for each without steam lap, 
 certainty of action is ensured, as one or other of the cylinder ports will always be 
 open to receive steam, and so effect instant starting of the gear. Also, the key seats 
 being at right angles to the crank, this allows the engine to run either way as 
 required. 
 
 Description of Brown's Patent Steam Tiller. 
 
 (Direct- Geared Type.) 
 
 This type of gear, which contains many improvements over the 
 older designs of direct gears, has been introduced specially for ships 
 that require a smaller power of gear than the 1905 design with 
 countershaft. The general arrangement is similar to the old direct 
 gear, except that the worm-wheel has been considerably increased 
 in diameter, and the worm is now double-threaded. The oil pumps 
 are worked direct from the eccentrics, and placed in a well at the 
 bottom of the engine pan. The friction clutch is increased in size, 
 so as to make it more powerful. Brown's patent economic valve, 
 which absolutely shuts off steam every time the engine comes to 
 rest, is also fitted. The great advantage possessed by this valve is 
 that, should dirt or any foreign matter get in so as to obstruct its 
 working, it can only remain in the open position, so that the gear 
 does not become disabled, and would work under the same conditions 
 as an ordinary steering gear without this attachment. The cut-off 
 gear Q embodies the 1907 patents, with which no stops on the valves 
 are ever reached, thus preventing any strain or damage to the gear 
 } by forcing over the telemotor when no steam is on the engine. This 
 ' gear gives a very quick opening at the commencement of the move- 
 ment of the control gear, and the motion of the valve is gradually 
 reduced to practically nil, though the control gear moves uniformly. 
 The same thing occurs in closing — that is, it commences to close 
 I very slowly, and just at closing the motion is very quick and decided. 
 i This gives a very fine and delicate control of the gear without any 
 i danger of reaching the stops on the control valve or its gear. With 
 i the standard design and a rudder angle of 40"^, it is possible, when 
 I there is no steam on the gear, for the tiller to be hard over in one 
 direction while the telemotor is pulled hard over to the other ; and 
 ' a greater angle of rudder can be arranged for, if necessary. This 
 does away with any need for disconnecting the control gear when 
 using the hand or other gear for moving the rudder. 
 
352 "Verbal" Notes and Sketches 
 
 The crank-shaft A is forged from high-tensile steel ; and the 
 worm B is cast on to it from a special hard and tough bronze. The 
 valvelessoil pumps C are placed in a well, and discharge up into the 
 tank D, from whence the oil is carried by small brass pipes to the 
 various bearings, guides, &c. The main pinion E is machine cut 
 from a forging of high-tensile steel, and is solid with its shaft. The 
 rack F, having machine-moulded knuckle teeth of special design, is 
 made in halves, which are interchangeable, bolted together, so that, 
 should the teeth in the middle get worn through long usage, the 
 two ends can be turned in to the centre, the worn portions going of 
 course to the outside. The slipper G slides on the top of the rack, 
 and helps to carry the weight of the tiller, engine, &c. The slipper 
 or friction block H is made of cast steel. The slides on inclined 
 planes for about lo' each side of midships, being tightest at the 
 centre ; and it has been found to hold the tiller quite steady, and act 
 perfectly. The stops I attached to the ends of the rack fit into the 
 teeth, and are secured by through bolts, so that they can be moved 
 when the rack is changed. The form of control valve J, fitted with 
 this gear, is of the well-known piston type, having one of Brown's 
 patent economic valves K fitted on top. The worm-wheel M forms 
 part of the friction clutch casing, and has its teeth cut in a special 
 machine, so that great accuracy is obtained. The distance piece 
 between the cylinders N has been increased in length, so that no part 
 of the piston rod that goes into the engine pan passes into the steam 
 cylinders or the packing in the stuffing boxes. This prevents oil being 
 taken over from the engine pan into the cylinders, and thus into the 
 feed water. 
 
 The hand gear has been redesigned and brought up to date. Both 
 the steam and hand gears are connected and disconnected by the large 
 friction brakes L, which give every satisfaction, and quite take the 
 place of the separate brakes frequently fitted. As the "cut-off" is of 
 the floating type, the steam and hand gear can be put in and taken 
 out in any position of the rudder, it not being necessary to connect 
 them in the position in which they were disconnected, or bring the 
 gear to the rudder. 
 
 The mechanical standard O has also been considerably modified 
 in design and brought up to date. This is, of course, for use in lieu 
 of the telemotor, or when it is desired to control the steering gear aft. 
 When changing from the telemotor to this standard, or vice versa, the 
 connection can be made in a second or two, as all that is necessary is 
 to take out a pin from one hole (marked P) and put it in the other, 
 according to which change is being made. These pins are of brass, 
 and have a large eye at the top, with a tapered point for easy entrance, 
 so that they can be easily unshipped and put in. 
 
 R is the receiving cylinder of the telemotor installation, and is of 
 the latest design, with patent single spring. 
 
 This gear can, of course, be arranged to work with control shafting 
 in place of the telemotor, if desired ; but as the type of telemotor is 
 
■ '■%■ 
 
FiG.7 
 
 FlG.4 
 
 No. 66.— Browns Patent Hydraulic Steering Telemotor. 
 
 [7, fa,: pai^' 352. 
 
General Notes and Descriptions 
 
 v)JO 
 
 thoroughly reliable, its adoption can be recommended in every case 
 where the distance from the steering gear to the steering position is 
 of any considerable length. 
 
 Description of Brown's Patent Hydraulic Steering Telemotor 
 
 (Sketch No. 66). 
 
 When the distance between the steering engine and the position of 
 the steering wheel is considerable, as in most modern ships, and it 
 is desired to have as frictionless as possible a connection between 
 the steering wheel and the steering engine, the telemotor shows to 
 the greatest advantage over shafting and its equivalents. One of the 
 advantages is that the small copper pipes can be led almost anywhere, 
 provided they are protected from heat and damage ; in fact, through 
 places where it would be very undesirable to have shafting, such as 
 saloons, berths, &c., as there is no noise, or oiling required, and no 
 motion, except, of course, the fluid through the pipes, so that there 
 is no danger of anything getting foul of bevel wheels, &c., and dis- 
 abling the gear. The telemotor described and illustrated herein is the 
 outcome of the original inventor's and makers' experience up to this 
 date. 
 
 Fig. I shows the vertical section of the transmitting cylinder A, 
 fitted with the piston B attached to the rack C, into which gears a 
 pinion D, the shaft E of which is made to revolve by the hand-wheel 
 through pinion and spur wheels F and G, by which a suitable number 
 of turns of the hand-wheel are obtained. 
 
 Pipes H and I from the top and bottom of the cylinder respectively 
 are led to the gear aft, and are joined up to either end of the cylinder 
 K by means of the pipes L and M, the connection being made accord- 
 ing to which way the after cylinder is required to move in relation to 
 the forward one. 
 
 (Fig. 3.) This cylinder is fitted with a piston N with the usual 
 piston rod, and connecting links O which are attached by a lever to 
 the controlling valve of the steering engine. The piston rod is fitted 
 with two crossheads P P, between which lies a spiral spring O, under 
 initial compression, and which is compressed further by any motion 
 of the piston, the object being to always cause the piston to return to 
 mid-position — the steering engine control valve, of course, moving 
 with it — when the pressure on both sides is equal, or tending to 
 become so. 
 
 When the apparatus is fully charged with fluid, any movement of 
 the steering wheel will bring about a corresponding movement of the 
 piston in the receivii;ig cylinder K, and consequently the valve gear of 
 the steering engine. 
 
 In pulling the wheel round, it will be found to become sensibly 
 stiffer until it is hard over, so that the steersman feels the amount of 
 helm he is giving the ship, much in the same way as in steering by 
 hand with the antiquated winding drum and chains ; and, on "letting 
 
^ 
 
 \ 
 
General Notes and Descriptions 35 
 
 ^DO 
 
 thoroughly reHable, its adoption can be recommended in every case 
 where the distance from the steering gear to the steering position is 
 of any considerable length. 
 
 Description of Brown's Patent Hydraulic Steering Telemotor 
 
 (Sketch No. 66). 
 
 When the distance between the steering engine and the position of 
 the steering wheel is considerable, as in most modern ships, and it 
 is desired to have as frictionless as possible a connection between 
 the steering wheel and the steering engine, the telemotor shows to 
 the greatest advantage over shafting and its equivalents. One of the 
 advantages is that the small copper pipes can be led almost anywhere, 
 provided they are protected from heat and damage ; in fact, through 
 places where it would be very undesirable to have shafting, such as 
 saloons, berths, &c., as there is no noise, or oiling required, and no 
 motion, except, of course, the fluid through the pipes, so that there 
 is no danger of anything getting foul of bevel wheels, &c., and dis- 
 abling the gear. The telemotor described and illustrated herein is the 
 outcome of the original inventor's and makers' experience up to this 
 date. 
 
 Fig. I shows the vertical section of the transmitting cylinder A, 
 fitted with the piston B attached to the rack C, into which gears a 
 pinion D, the shaft E of which is made to revolve by the hand-wheel 
 through pinion and spur wheels F and G, by which a suitable number 
 of turns of the hand-wheel are obtained. 
 
 Pipes H and I from the top and bottom of the cylinder respectively 
 are led to the gear aft, and are joined up to either end of the cylinder 
 K by means of the pipes L and M, the connection being made accord- 
 ing to which way the after cylinder is required to move in relation to 
 the forward one. 
 
 (Fig. 3.) This cylinder is fitted with a piston N with the usual 
 piston rod, and connecting links O which are attached by a lever to 
 the controlling valve of the steering engine. The piston rod is fitted 
 with two crossheads P P, between which lies a spiral spring Q, under 
 initial compression, and which is compressed further by any motion 
 of the piston, the object being to always cause the piston to return to 
 mid-position — the steering engine control valve, of course, moving 
 with it — when the pressure on both sides is equal, or tending to 
 become so. 
 
 When the apparatus is fully charged with fluid, any movement of 
 the steering wheel will bring about a corresponding movement of the 
 piston in the receiving cylinder K, and consequently the valve gear of 
 the steering engine. 
 
 In pulling the wheel round, it will be found to become sensibly 
 stiffer until it is hard over, so that the steersman feels the amount of 
 helm he is giving the ship, much in the same way as in steering by 
 hand with the antiquated winding drum and chains ; and, on " letting 
 
354 "Verbal" Notes and Sketches 
 
 go," the steering wheel will run back to midships together with the 
 steering gear aft. 
 
 The increase of resistance of one large spring is very much less 
 than with the old design with two springs of small diameter, and as 
 the minimum power required here is fixed by the amount required to 
 move the control valve of the steering engine and bring the steering 
 wheel back to its central position, it follows that with the single 
 spring considerably less power is required to put the wheel hard 
 over. Further advantages are that a much better design of spring is 
 possible, with a larger factor of safety, and being co-axial with the 
 cylinder it is more efficient, as, with the two springs, one on each side, 
 there is generally a cross-winding action, or tendency of the cross- 
 heads to bear hard on the guide rods, due to it being practically 
 impossible to get two springs to exert equal resistance, or give out 
 equal power, through equal ranges of motion. 
 
 The telemotor on the bridge is fitted with an indicator R, as shown 
 in Fig. 2, which, when everything is in order, shows the actual position 
 of the helm. It is possible, however, that the piston packing leathers 
 may in time become worn, so as to admit of considerable leakage, and 
 it may happen that the piston B may be working altogether in the 
 top or bottom of the cylinder A, with the piston aft in the mid- 
 position, and the ship steered on a straight course with the indicator 
 pointing at, say, 20^, and this may go on until the indicator pointer is 
 almost past the degrees marked on the quadrant, still without dis- 
 abling the gear, as the capacity of the cylinder A is considerably more 
 than that of the cylinder K aft. 
 
 To readjust the indicator and position of the helm, it is only 
 necessary to turn the steering wheel until the indicator is brought to 
 zero, and the piston enters the bye-pass or central position, allowing 
 a free communication of liquid between both sides of the system, when 
 the compressed spring aft will immediately bring everything into 
 correspondence. As, however, the piston B in steering a ship is 
 always more or less passing the centre position in " porting " or 
 " starboarding " even to the smallest extent, the tendency is for the 
 piston N in the cylinder K always to return to the mid-position every 
 time the forward piston B is in that position. 
 
 The bye-pass is now greatly improved, being formed by drilling 
 two rows of very small holes, which are the correct distance apart 
 longitudinally, so that the two leather packings of the piston B are 
 between them, thus allowing a free passage for the fluid through the 
 holes and so round the piston. This, of course, allows the pressure 
 between the two sides of the system to come into equilibrium should 
 there be any difference, and the spring on the cylinder K then brings 
 the piston N and the control valve of the steering engine to their 
 central position. The small holes are not liable to catch the leathers 
 and turn the edges over, as frequently happened with the old style of 
 bye-pass where the opening extends right round. This is quite 
 obvious when it is explained that the holes are only just over ^s ^^^^ 
 
General Notes and Descriptions 355 
 
 diameter and nearly | inch apart, the leathers being thus supported 
 by the metal between the holes. Another advantage is that the 
 cylinder is all in one piece and can be bored right through at one 
 operation, which prevents any possibility of getting out of line at this 
 part, such as was always liable to take place with the old arrange- 
 ment, through the joints not being properly nipped up, or any defect 
 in machining, &c. 
 
 It is sometimes necessary to set the gear so that the central 
 position does not actually represent the rudder as true fore and aft, 
 but a certain amount of permanent helm is required to counteract the 
 action of the propeller, &c., when the ship is under weigh. This is 
 done by making the connecting links longer or shorter, as the case 
 may require, by means of the adjusting nuts provided, thus altering 
 the central or shut position of the steam control valve. 
 
 In some exceptional cases, where it might be inconvenient to 
 adjust the gear by running the indicator into its midship position, 
 should the two pistons have got out of correspondence, there is 
 provided the hand-wheel S which opens the stop valve T, giving a 
 free communication between the top and bottom parts of the cylinder, 
 taking the place of the automatic adjustment by bye-pass at the 
 central position, and so allowing the indicator to be brought to zero 
 without moving the rudder aft. This valve must be shut and 
 kept so when working. It should only be used in cases where 
 there is very little room to manoeuvre the ship, as in narrow waters. 
 The reason for this precaution is that it may be opened when 
 unnecessary and left open or slightly open. In port it may be left 
 open with advantage, as should any one move the wheel, nothing is 
 moved aft, and so no damage can result. 
 
 A small tank U is provided with gauge glass, as shown. This 
 is usually charged with a mixture of glycerine and water, one part 
 of the former to two or three of the latter. The cock V is provided 
 for shutting the tank off from the system when charging up, &c., but 
 it must always be kept open when the telemotor is being used 
 for steering. 
 
 As it is very important that the whole system of pipes and 
 cylinders should be fully charged, and no air should be present, it 
 is necessary to provide for the expansion and contraction of the 
 fluid, due to changes of temperature, &c., and for this purpose a 
 valve box is fitted on the bye-pass, a section of which is shown on 
 Fig. 4. It contains a small inlet and outlet valve, the latter being 
 simply an ordinary safety valve loaded above the working pressure, 
 which is about 200 lbs. per square inch. As the temperature rises, 
 a portion of the fluid passes into the tank U, and as the pressure 
 falls the fluid returns through the inlet valve. 
 
 The entire telemotor on the bridge is constructed of gun-metal, 
 so as not to affect the compass. The motor cylinder aft is of the 
 same material, and the pipes arc of solid drawn copper of diameters 
 varying from f to f inch internal diameter, according to the length 
 
356 "Verbal" Notes and Sketches 
 
 fitted. These are easily run, and may be bent into any number of 
 corners without adding materially to the friction of the gear. 
 
 A hand pump Y with tank Z is provided for charging up the 
 system, and suitable pipes for connecting are supplied according to 
 the arrangement of the gear on the ship. The cock on the tank is 
 for shutting off the fluid from the pump when not in use. Screw- 
 down valves J^ and J^ are provided for shutting off the pump and its 
 connections when the system is charged, the discharge pipe from the 
 pump being connected to J- and the return pipe to JK Two similar 
 valves, J^ and J*, are provided so that they can be closed when it is 
 desired to open out the cylinder K, and so prevent loss of fluid from 
 the system. When working, these latter valves must be kept 
 open, as also when charging up. A spring-loaded valve J^ is 
 provided, as shown, so that when charging up a system where the 
 forward cylinder is a great height above the cylinder K, the fluid is 
 retained in the pipes instead of coming down and leaving a vacuum 
 or empty space at the highest point. 
 
 Instructions for Charging, Adjusting, and Working. 
 
 It is of the utmost importance that all joints be watertight, as 
 any leakage will empty the small tank. After all the pipes are 
 coupled and the connections made to cylinders and to tank in 
 wheel-house, close the cock underneath the tank and fill to about 
 one-third full with fresh water. For cold climates, add 30 per cent, 
 glycerine, which keeps the parts lubricated, and will resist frost to 
 about zero Fahrenheit (see table of freezing temperatures of 
 various mixtures of water and glycerine on page 359 ). Put the 
 hand-wheel in mid gear, which will be seen by the pointer coming 
 between the two zero marks on indicator. This opens the bye-pass 
 between the top and bottom ends of the cylinder, and allows the 
 whole system to be charged by one operation from the after part of 
 the ship. 
 
 Open the cocks on the side of the cylinder K or motor cylinder, 
 and see the cocks J^ and J* are open. When pumping, great care 
 should be taken that the liquid in tank Z never gets so low as to 
 allow the pump to draw air, as the good working of the gear depends 
 upon the air being expelled. The liquid will shortly be seen to run 
 from the small pipe back into the tank Z, but the pumping must be 
 continued for some time, say three times as long as it took to come 
 back. By this time the air should nearly all have been driven out, 
 and each stroke of the pump should show a corresponding rush, 
 and not a continuous flow back through the return pipe to the 
 tank. 
 
 Being satisfied as to this, the air cock J^ on the top of the 
 cylinder should be closed, and a slight but continuous strain kept on 
 the pump. Now, go forward to the wheel-house, and on the \alve 
 casing cover on the transmitting cylinder A will be seen a brass plug 
 
General Notes and Descriptions 357 
 
 VV^ ; remove it, and press down the spindle of the inlet valve, which 
 is immediately underneath, when the liquid will rush up owing to 
 the pressure being kept on by the pump from aft. When the casing 
 is quite full, and no more air bubbles up, screw in the plug W^ ; also 
 the plug A^ on the top of the transmitting cylinder should be 
 slacked back to allow any air imprisoned in the cylinder to escape, 
 afterwards tighten up the plug, close the cock J- on the under side 
 of the motor cylinder K, when the installation will be fully charged; 
 open the cock V underneath the tank U, and all is ready for use. 
 The tank U in the wheel-house should be kept half full. 
 
 The gear may now be tried by putting the wheel over to port and 
 starboard, and noticing aft if a corresponding movement takes place 
 in the piston of the motor cylinder. Should it not respond on one 
 side or the other, then an internal leakage may be suspected ; in 
 which case, examine the leathers in the telemotor and motor 
 cylinder. 
 
 To take out for examination or renewal the leathers on the piston 
 B (a section of this piston with its leathers, springs, nuts, Sec, is 
 shown to a larger scale in Fig. 7), it is only necessary to remove the 
 cylinder cover and turn the wheel so as to bring the piston up. The 
 rack is sufficiently long to enable the piston to be run up right out 
 of the cylinder and so be easily got at. If the bye-pass valve T is 
 opened, and the cover left on until the piston comes against it, this 
 can be done with little, if any, loss of fluid. To get at the leathers 
 in the after cylinder K (Fig. 8 shows the piston with its leathers, 
 springs, nuts, &c., to a larger scale), it is necessary to shut valve ]*, 
 remove the cylinder cover, slack off and remove the two large nuts 
 that bear on the top yoke P, when the piston rod, &c., can be drawn 
 sufficiently far out to examine or renew the leathers. As soon as the 
 piston comes out of the cylinder, valve J^ should be shut, so that no 
 more fluid may be lost. It should not be closed before the piston 
 is out, or difficulty may be experienced in getting it so. All the 
 leathers used for the two pistons (four in all) are exactly alike, which 
 is a great advantage, as only one size of leather has to be carried as 
 spare instead of two sizes as in the older designs. Care should be 
 taken that any new leathers obtained are the proper depth, as the 
 action of the automatic bye-pass on the cylinder A may be rendered 
 inoperative, if they are too deep and cover the holes. The leathers 
 in the pistons themselves will not cause any trouble until actually 
 worn out, and even when in a leaky condition will work quite well 
 and keep in correspondence with the gear aft, in virtue of the spring 
 always putting the rudder in a fore and aft central position when the 
 piston enters the bye-pass portion of the cylinder. 
 
 The inlet and relief valves in the valve box VV are not working 
 but automatic valves ; they merely open and shut as occasion requires, 
 to allow for expansion and contraction of the fluid in the pipes due 
 to change of temperature. 
 
 After having made any repairs that may have been necessary, 
 
358 "Verbal" Notes and Sketches 
 
 and before recharging, it is advisable to clean out the pocket under- 
 neath these valves, the purpose of which is to collect any dirt or 
 sediment that may have been in the liquid. This is done by 
 removing the brass plug in the bottom, when the small quantity of 
 liquid that flows out of the pocket will carry anything with it. 
 
 When first charging up after erection, or after any repairs or 
 alterations to pipes, &c., it is advisable to disconnect the pipes from 
 both cylinders and force clean water through them, so as to wash 
 out any dirt or other foreign matter that may be in the pipes, and so 
 prevent it getting into the cylinders and valve boxes. 
 
 In addition to the stuffing box of the valve T, there are only 
 three more — one on the cylinder on the bridge and two aft — and as 
 the water pressure need never exceed 250 lbs. per square inch, there 
 is no reason for any serious loss of the fluid in the tank. Keep the 
 stuffing boxes full of greasy cotton packing, and screw up as lightly 
 as is necessary to secure tightness, but not stiffness. It is advisable 
 to occasionally examine the leathers in the telemotor and motor 
 cylinder aft when the ship is in port. The necessity for this can 
 be ascertained by pulling the steering wheel hard over to port and 
 securing it there. The motor cylinder will be found to have responded 
 to same extent. If the gear is now left, say for half an hour, the 
 spring in the motor cylinder will have moved the piston towards 
 midship position if there is any leakage in the port leather. A 
 similar trial may be made to starboard, which will test these 
 leathers. 
 
 It need not be expected that these leathers should be quite tight, 
 but the motor piston should remain over for say ten minutes without 
 any serious movement towards midship position, that being, about the 
 maximum time that, in practice, a helm would be held hard over ; 
 and so any little deviation due to leaky leathers would be at once 
 adjusted when the steering wheel is let go, the motor springs running 
 it back to zero, and the bye-pass allowing the free circulation of the 
 fluid. 
 
 Fig. 5 is a section of the telemotor through the centre of the shaft, 
 and shows a screwed plug X. When it is desired to take out the 
 shaft E (the indicator being at zero), this plug is withdrawn and the 
 other end screwed into the cylinder until its point enters a recess in 
 the rack C. The rack is thus kept in its central position until the 
 shaft and the pinion are replaced. 
 
 Care should be taken to lubricate with good oil the various 
 working parts of the gear. 
 
 A glycerometer and thermometer are supplied with each installa- 
 tion, so that it is possible to test the actual proportion of glycerine in 
 the fluid at any time when the gear is not in use, by drawing some 
 of the fluid out of the circuit and testing in a similar manner to that 
 adopted for ascertaining the density of the water in boiJers, the 
 glycerometer reading right off the percentage of glycerine. 
 
General Notes and Descriptions 359 
 
 Non-Freezing Fluid for Telemotors. 
 
 Water containing Refined c r . ixr i . r u u v 
 
 .., • " Safe to Work to Fahrenheit. 
 
 Glycerine. 
 
 25 per cent. - - +18" 
 
 33 ,y - • ■ +10° 
 
 50 „ - - - - 20° 
 
 60 ,, - - - - 30°, getting thick 
 
 70 „ - - - Too thick to work at - 25. 
 
 Metallic Packing (Sketches Nos. 67 and 68). 
 
 The United States type of packing is entirely metallic, and is thus 
 specially suitable for high pressure steam or gas. Consisting as it does 
 of various members or sections carefully fitted into each other, any 
 side play of the rod is compensated for, the accommodating nature of 
 the springs, cones, rings, and blocks forming the packing, and which 
 constitutes perhaps the most valuable point of this well-known system 
 of packing; the regulation of the packing block pressure is automatic, 
 constant, and reliable, and is regulated to suit equally well the out 
 and in stroke of the rod. 
 
 To exert a minimum packing pressure against a rod, a packing 
 must be of the floating type, and this important result is attained in 
 the U.S. packing, which is automatic and floating, exerting a minimum 
 but effective pressure against the rod, and thus preventing the escape 
 of steam in the case of high pressures and intermediate cylinder 
 rod glands, and the admission of air in the case of the L.P. cylinder 
 rod gland. The packing is free to " follow the rod," and this being so, 
 the pressure of the packing against the rod is reduced to a minimum. 
 
 Description. 
 
 Duplex Packing is designed for use with high pressures. It consists 
 of a block packing as described above used in conjunction with a cone 
 packing which includes a set of white metal rings (ii) placed in a 
 vibrating cup (10), the interior of which is partly conical. The duplex 
 follower ring (12) holds the cone rings in position, and transmits to 
 the latter the pressure from the duplex follower springs, which are 
 held in the. ring (14) and protected by the spring cover (13). In this 
 arrangement the inner cone packing checks the steam pressure, and 
 the outer block packing is thus assisted, and the escape of steam 
 absolutely prevented. 
 
 Atmospheric Duplex Packing. — For use on low-pressure condensing 
 cylinders. It consists, like the Duplex Packing, of two parts, but with 
 this difference : in the Duplex Packing both parts are steam setting, 
 and operate in the same direction to prevent the escape of steam : in 
 the Atmospheric Packing the parts are placed face to face and act in 
 
36o 
 
 Verbal" Notes and Sketches 
 
 United States Marine Type Packings. 
 
 No. 67.— Duplex Packing. 
 
 No. 68.— Atmospheric Duplex Packing. 
 
DI 
 
 id 
 
 he 
 id 
 he 
 
 r'->>- '^'••- 'er. 
 
 der 
 
 Dn, 
 is 
 
 "^SS 
 
 or 
 ter 
 ed 
 a 
 lel, 
 ird 
 ter 
 
 3VV 
 
 ire 
 
 ;rn 
 
 ap 
 
 in 
 
 ig- 
 aft 
 )er 
 he 
 lie 
 he 
 ;es 
 he 
 
 are pinned on to nui at uacK ui uus. lu picvcnt ^""■■"^' ;';Y,/^^„'f^^ 
 faro-e nut screwed on to the tube aft of the stern post for the same 
 
 ^e foot) afea'the'ror key being also sunk on the jhaft and sec^^^^^^^^^ 
 
 by pins as shown. The boss should have a bearing fit on the leather 
 
 at the sides, but should be clear at the top o/f^a her. , ^^.^and 
 
 For a right-hand propeller the boss nut should have a lett nana 
 
I iol; for : , N , 
 
 SPANNER ?\H^. - .74J! . .>4 '^ 
 
 r--24- -f 4 
 
 Check Ring- and After Bush. 
 
 Section through Tube. 
 
 No. 69. Stern Tube and Propeller Shaft. 
 (With dimensions for a 12 inch shaft. 1 
 
 Gland and Flange of Tube. 
 
General Notes and Descriptions 
 
 361 
 
 opposite directions. The inner packing only is steam setting and 
 prevents the escape of steam. The outer part is open to and set by 
 the atmosphere. When there is a vacuum in the cyh'nder, the 
 atmospheric pressure is actually used to tighten the outer packing and 
 automatically prevent the passage of air, which would impair the 
 vacuum. 
 
 DESCRIPTION OF COMPONENT PARTS. 
 
 A, 
 
 Stuffing Box. 
 
 5A 
 
 Guide Blocks. 
 
 10, 
 
 Duplex Vibrating 
 
 B, 
 
 Piston Rod. 
 
 6, 
 
 Horn Rings. 
 
 
 Cup. 
 
 I, 
 
 Packing- Case. 
 
 7^ 
 
 Block Springs. 
 
 II, 
 
 Duplex Cone Rings. 
 
 2, 
 
 Stud Bolts. 
 
 8, 
 
 Spring Cover 
 
 12, 
 
 Duplex Follower. 
 
 3. 
 
 Ball Joints. 
 
 
 Plate. 
 
 13. 
 
 Duplex Spring Cover. 
 
 4. 
 
 Sliding Plates. 
 
 9, 
 
 Follower Bush and 
 
 14. 
 
 Duplex Spring Holder 
 
 5. 
 
 Packing Blocks. 
 
 
 Springs. 
 
 
 and Springs. 
 
 Stern Tube and Shaft (Sketch No. 69). 
 
 Description. — The stern tube is generally constructed of cast iron, 
 the thickness varying from about i^ to 2h inches. The tube is 
 larger in diameter at the forward end (24 inches) and slightly less 
 (23I inches) at the stern-post end for convenience in fitting in or 
 in taking out. The forward end is flanged and bolted to the after 
 bulkhead, a "make-up" liner of lead or wood being inserted 
 between the two as shown. The forward end is supplied with a 
 stuffing box packing and gland to keep water out of the tunnel, 
 and the after end runs on a bearing composed of lignum vitae (hard 
 wood), the wood strips being fitted dovetail fashion into the after 
 brass bush. Waterways are left at four or more positions to allow 
 access of water to the shaft after bearing. The wood strips are 
 kept in place forward by a collar or lip on the bush, or on the stern 
 tube, and aft by a " check ring," which is secured by means of tap 
 bolts to the flange of the brass bush. The bush itself is pinned in 
 turn to the stern tube by countersunk screws, as shown in the drawing. 
 A rubber " stop " ring is fitted hard up between the end of shaft 
 liner and the propeller boss, which is recessed out to allow the rubber 
 ring to be fitted, the object of the rubber ring being to prevent the 
 access of water to the metal of the shaft, and thus prevent galvanic 
 action taking place between the shaft metal and the brass of the 
 liner, which would result in corrosion of the shaft. "Keeper" plates 
 are pinned on to nut at back of boss to prevent turning, and to the 
 large nut screwed on to the tube aft of the stern post for the same 
 object. The propeller boss is fitted to the shaft on a taper (| inch 
 per foot), a feather or key being also sunk on the shaft, and secured 
 by pins as shown. The boss should have a bearing fit on the feather 
 at the sides, but should be clear at the top of feather. 
 
 For a right-hand propeller the boss nut should have a left-hand 
 
36o 
 
 [ 
 
 No. 68.— Atmospheric Duplex Packing. 
 
General Notes and Descriptions 
 
 361 
 
 opposite directions. The inner packing only is steam setting and 
 prevents the escape of steam. The outer part is open to and set by 
 the atmosphere. When there is a vacuum in the cylinder, the 
 atmospheric pressure is actually used to tighten the outer packing and 
 automatically prevent the passage of air, which would impair the 
 vacuum. 
 
 DESCRIPTION OF COMPONENT PARTS. 
 
 A, 
 
 Stuffing Box. 
 
 5A 
 
 Guide Blocks. 
 
 10, 
 
 Duplex Vibrating 
 
 B, 
 
 Piston Rod. 
 
 6, 
 
 Horn Rings. 
 
 
 Cup. 
 
 I, 
 
 Packing Case. 
 
 7' 
 
 Block Springs. 
 
 II, 
 
 Duplex Cone Rings. 
 
 2, 
 
 Stud Bolts. 
 
 8, 
 
 Spring Cover 
 
 12, 
 
 Duplex Follower. 
 
 3. 
 
 Ball Joints. 
 
 
 Plate. 
 
 13. 
 
 Duplex Spring Cover. 
 
 4. 
 
 Sliding Plates. 
 
 9, 
 
 Follower Bush and 
 
 14. 
 
 Duplex Spring Holder 
 
 5> 
 
 Packing Blocks. 
 
 
 Springs. 
 
 
 and Springs. 
 
 Stern Tube and Shaft (Sketch No. 69). 
 
 Description. — The stern tube is generally constructed of cast iron, 
 the thickness varying from about i| to 2h inches. The tube is 
 larger in diameter at the forward end (24 inches) and slightly less 
 (23I inches) at the stern-post end for convenience in fitting in or 
 in taking out. The forward end is flanged and bolted to the after 
 bulkhead, a "make-up" liner of lead or wood being inserted 
 between the two as shown. The forward end is supplied with a 
 stuffing box packing and gland to keep water out of the tunnel, 
 and the after end runs on a bearing composed of lignum vitae (hard 
 wood), the wood strips being fitted dovetail fashion into the after 
 brass bush. Waterways are left at four or more positions to allow 
 access of water to the shaft after bearing. The wood strips are 
 kept in place forward by a collar or lip on the bush, or on the stern 
 tube, and aft by a " check ring," which is secured by means of tap 
 bolts to the flange of the brass bush. The bush itself is pinned in 
 turn to the stern tube by countersunk screws, as shown in the drawing. 
 A rubber " stop " ring is fitted hard up between the end of shaft 
 liner and the propeller boss, which is recessed out to allow the rubber 
 ring to be fitted, the object of the rubber ring being to prevent the 
 access of water to the metal of the shaft, and thus prevent galvanic 
 action taking place between the shaft metal and the brass of the 
 liner, which would result in corrosion of the shaft. "Keeper" plates 
 are pinned on to nut at back of boss to prevent turning, and to the 
 large nut screwed on to the tube aft of the stern post for the same 
 object. The propeller boss is fitted to the shaft on a taper (f inch 
 per foot), a feather or key being also sunk on the shaft, and secured 
 by pins as shown. The boss should have a bearing fit on the feather 
 at the sides, but should be clear at the top of feather. 
 
 For a right-hand propeller the boss nut should have a left-hand 
 
362 "Verbal" Notes and Sketches 
 
 screw, so as to be self-locking when revolving. Needless to say the 
 stern tube is put in place from the inside of the ship. 
 
 Observe that a small check collar is cast on the tube forward of 
 the stern post for tightening up the nut. In the drawing shown the 
 diameter of the shaft liner is 13! inches forward and 13I inches aft : 
 this is for convenience in fitting in or drawing out the shaft. 
 
 In running, it is better that a small drip of water should show at 
 the gland, as otherwise the gland brass bushes and packing may heat 
 up, and possibly tear up the shaft liner. 
 
 A water service is fitted, leading from the tube to the bulkhead just 
 over the gland, the temperature of which will indicate if the shaft 
 inside the tube is running cool or otherwise. To allow for partial 
 repacking at sea, the gland is often fitted in halves, with long studs, 
 so that the gland need not be taken off altogether when inserting 
 the turn of packing required. 
 
 Cedervall's Patent Stern Tube (Sketch No. 70). — The lubrication of 
 propeller shaft bearings within the stern tube has hitherto been chiefly 
 effected by the eakage of a certain amount of water into the bearings, 
 and its combination there with the oily surfaces of lignum-vita; strips ; 
 or by forcing a mixture of oil and tallow between the plain unprotected 
 bearing surfaces. In the one case the shaft, although partially 
 protected by a sleeve of brass, has certain parts constantly exposed 
 to the corrosive action of sea water ; while the other method, under 
 usual conditions, does not afford a satisfactory means of lubrication, 
 as the water washes away the lubricant from the parts where it is 
 most required, and the resultant corrosion and wear of shaft and 
 bearings are most excessive. 
 
 To overcome imperfections, and to reduce first cost, " Cedervall's 
 Patent Protective Lubricating Box " has been invented. The principal 
 objects of this invention are to absolutely prevent the access of any 
 external water to the stern tube, and to provide a reservoir of oil 
 capable of supplying a steady and continuous lubrication to the 
 whole bearing surface. The invention consists, essentially, of an 
 annular box of brass or gun-metal, containing an inner packing ring, 
 which is pressed outwards by a series of small spiral springs. The 
 box fits over the shaft, and is fixed to the forward face of the propeller 
 boss by means of screws, thus turning with the propeller, and the 
 inner movable ring presses against the prepared face of the stern 
 tube bush. The springs, while of ample strength, are of such 
 elasticity that, irrespective of any play which the shaft may have 
 in revolving or reversing, the ring maintains a watertight joint 
 with the end of the tube. As the ring is faced with antifriction 
 metal and well lubricated by oil from the inside, it revolves with 
 the minimum amount of friction. 
 
 The method of applying the protective lubricating box, and the 
 arrangement for supplying the lubricant, are shown in the drawing. 
 Three or more grooves are cut in the stern tube bush. 
 
n^«^.-^i M^«.. 
 
 QvtrJIovi Cock, 
 
 {To face page 362. 
 
 4. ouore on coupling ui lau snair solidly irom stern tube end bv 
 means of the wooden blocks mentioned before, and remove gland 
 and packing. ^ 
 
 5. Remove nut at back of boss, by means of blows from a hammer 
 turni ^'^^ ^Pa""^'"' having previously secured the propeller from 
 
QverHo* Cock. 
 
 ^OBnm Co<A . 
 
 No. 70. Cedervell's Patent Stern Tube. 
 
 [To /act page 162. 
 
General Notes and Descriptions 363 
 
 The top one is for the escape of air, and the others are for leading 
 the oil to the inside of the movable ring of the protective box. From 
 the stern tube three pipes are carried through the aft bulkhead, or 
 to any other convenient place, and fitted with cocks. The oil is 
 forced in by means of a small hand pump, and when all the spaces 
 are filled, the oil shows at the overflow cock. 
 
 From the foregoing description it will be obvious that the 
 protective lubricating box has several highly important advantages. 
 Its adoption does away with the necessity for expensive liners and 
 metal bearings, the plain cast-iron stern tube bush being all that is 
 required, and as a consequence of the efficient and uniform lubrication, 
 coupled with the exclusion of all dirt and gritty substances from the 
 bearings, the wear and tear on the propeller shaft is reduced to a 
 minimum, and the usual vibration at the after part of most steamers 
 is practically eliminated. Experience with vessels already fitted 
 with the patent lubricating box amply proves its efficiency, as after 
 several years' constant working the shafts on examination exhibit 
 bearing surfaces quite as good as any smoothly working bearing 
 connected with the engine proper. 
 
 The safeguard which this immunity from corrosion and absolute 
 wear affords against breakdowns of the shafting must be obvious 
 to, and appreciated by, all having experience with the present 
 expensive and not very efficient mode of fitting and lubricating 
 propeller shaft bearings. Although heating of the stern tube 
 bearings is most unlikely to happen with the arrangements shown, 
 should it occur, the oil may be discharged at the drain cock, and 
 water forced through the bearing by means of a hose attached to 
 the filling cock. To obviate the possibility of the box being fouled 
 by ropes, ice, or other floating bodies, a strong guard ring, made 
 in halves, is fitted ov^er the box, as shown. 
 
 Drawing the Propeller Shaft. — The usual method of drawing out 
 the tail end shaft for examination or repair is as follows : — 
 
 With steamer in dry dock, have all necessary working gear at 
 hand, such as : chain and wire rope tackle, strong wooden blocks, 
 screw or hydraulic jacks, light ram for coupling bolts, &c. 
 
 1. Fit up suitable staging round propeller. 
 
 2. Disconnect tunnel shafting and remove to one side two 
 lengths of same. 
 
 3. Place tackle in position for drawing out tail end shaft (usually 
 consisting of rope and chain blocks). 
 
 4. Shore off coupling of tail shaft solidly from stern tube end by 
 means of the wooden blocks mentioned before, and remove gland 
 and packing. 
 
 5. Remove nut at back of boss, by means of blows from a hammer 
 on the large spanner, having previously secured the propeller from 
 turning. 
 
scr 
 ste 
 
 th( 
 d\i 
 thi 
 
 th( 
 up 
 
 ov 
 
 in; 
 
 rej 
 so 
 th 
 
 Cc 
 
 pr 
 eff 
 an 
 or 
 be 
 
 pr 
 to 
 
 us 
 
 as 
 
 mi 
 
 be 
 
 F'c 
 
 ot 
 
 e> 
 
 ca 
 
 wl 
 
 ar 
 
 wl 
 
 be 
 
 be 
 
 in 
 
 tu 
 
 el 
 
 in 
 
 with the end ot the tube. J\s the ring is lacea wiih antitnction 
 
 metal and well lubricated by oil from the inside, it revolves with 
 
 the minimum amount of friction. 
 
 The method of applying the protective lubricating box, and the 
 arrangement for supplying the lubricant, are shown in the drawing. 
 Three or more grooves are cut in the stern tube bush. 
 
General Notes and Descriptions 363 
 
 The top one is for the escape of air, and the others are for leading 
 the oil to the inside of the movable ring of the protective box. From 
 the stern tube three pipes are carried through the aft bulkhead, or 
 to any other convenient place, and fitted with cocks. The oil is 
 forced in by means of a small hand pump, and when all the spaces 
 are filled, the oil shows at the overflow cock. 
 
 From the foregoing description it will be obvious that the 
 protective lubricating box has several highly important advantages. 
 Its adoption does away with the necessity for expensive liners and 
 metal bearings, the plain cast-iron stern tube bush being all that is 
 required, and as a consequence of the efficient and uniform lubrication, 
 coupled with the exclusion of all dirt and gritty substances from the 
 bearings, the wear and tear on the propeller shaft is reduced to a 
 minimum, and the usual vibration at the after part of most steamers 
 is practically eliminated. Experience with vessels already fitted 
 with the patent lubricating box amply proves its efficiency, as after 
 several years' constant working the shafts on examination exhibit 
 bearing surfaces quite as good as any smoothly working bearing 
 connected with the engine proper. 
 
 The safeguard which this immunity from corrosion and absolute 
 wear affords against breakdowns of the shafting must be obvious 
 to, and appreciated by, all having experience with the present 
 expensive and not very efficient mode of fitting and lubricating 
 propeller shaft bearings. Although heating of the stern tube 
 bearings is most unlikely to happen with the arrangements shown, 
 should it occur, the oil may be discharged at the drain cock, and 
 water forced through the bearing by means of a hose attached to 
 the filling cock. To obviate the possibility of the box being fouled 
 by ropes, ice, or other floating bodies, a strong guard ring, made 
 in halves, is fitted over the box, as shown. 
 
 Drawing the Propeller Shaft. — The usual method of drawing out 
 the tail end shaft for examination or repair is as follows : — 
 
 With steamer in dry dock, have all necessary working gear at 
 hand, such as : chain and wire rope tackle, strong wooden blocks, 
 screw or hydraulic jacks, light ram for coupling bolts, &c. 
 
 1. Fit up suitable staging round propeller. 
 
 2. Disconnect tunnel shafting and remove to one side two 
 lengths of same. 
 
 3. Place tackle in position for drawing out tail end shaft (usually 
 consisting of rope and chain blocks). 
 
 4. Shore off coupling of tail shaft solidly from stern tube end by 
 means of the wooden blocks mentioned before, and remove gland 
 and packing. 
 
 5. Remove nut at back of boss, by means of blows from a hammer 
 on the large spanner, having previously secured the propeller from 
 turning. 
 
'M 
 
 " Verbal " Notes and Sketches 
 
 6. Drive in steel wedges hard up between boss and stern post, 
 and by means of a ram (hydraulic) force boss off the taper. 
 
 7. Connect up propeller to tackle, and draw tail shaft gradually 
 into tunnel, supporting it by blocks as it emerges. 
 
 NOTE.— Very often the boss is found difficult to start, and when this is found to 
 be the case one of the following methods may be tried : — 
 
 1. Build a fire below the boss, and when heated up apply blows from a large 
 hammer on the end of the shaft, or the pressure of a ram on the steel wedges. 
 
 2. Bore a number of holes into the metal of the boss, then try the heating up, &c., 
 as before. The holes are to allow of easier expansion of the boss when heating up. 
 
 No. 71.— Pulsometer Pump. 
 
 Description of the Pulsometer Type Pump. 
 
 The body casting comprises the two working chambers A A, the 
 air vessel B, and the discharge box, which is shown by the dotted lines 
 in the illustration. Valves G G are fitted between the suction branch 
 
 I 
 
General Notes and Descriptions 365 
 
 C and the working chambers, and a second set of similar valves F F 
 is arranged in the passages connecting the discharge box with the 
 working chambers. Hand-holes L L are provided to give access to 
 the suction valves, whilst the discharge valves are reached by removing 
 the cover of the discharge box. Surmounting the body there is the 
 " neck " casting J, which contains the gun-metal ball I, and is fitted 
 with the steam pipe K. The air vessel B communicates with the 
 suction branch C, by means of a prolongation running down in front 
 of and between the two chambers A A. 
 
 The action of the pump consists of the alternate filling and empty- 
 ing of each working chamber, as the condensation and pressure of the 
 steam respectively exert an upward and downward force on the 
 surface of the water. The alternation of these operations is effected 
 by means of the ball valve I in the following manner : — Assuming one 
 of the chambers A be open to steam and full of water, the steam 
 entering by the steam pipe K, and past the ball I, passes into the 
 chamber and presses upon the small surface of water exposed. This 
 depresses it and drives it through the discharge valves F F into the 
 rising main D. The moment, however, the water in the chamber falls 
 to the level of the opening in the branch leading to the discharge box, 
 the steam blows through, and the consequent disturbance of the water 
 surface causes the instantaneous condensation of the steam. The 
 vacuum thus formed in the emptied chamber immediately pulls the 
 control ball I over on to the corresponding seat and cuts off further 
 admission of steam, allowing the vacuum to be completed. Water 
 immediately enters through the suction pipe C, and lifting the inlet 
 valve G, rapidly fills the chamber again. A similar operation has been 
 taking place in the opposite chamber, the period occupied by filling 
 one chamber corresponding with that of emptying the other, and these 
 operations continue alternately in the two chambers so long as the 
 pump is supplied with steam and water. The alternations follow so 
 rapidly and with such regularity that the stream of water is practically 
 continuous. A small "snifting " valve is fixed in the upper part of 
 each of the working chambers. Their function is to introduce a small 
 quantity of air at each pulsation for the purpose of cushioning the ball 
 as it changes its position and to separate the steam from the water by 
 a non-conducting film, thus preventing loss of steam by condensation 
 during the forcing part of the stroke. 
 
 Air Pump Valves and Vacuum. 
 
 The condenser vacuum is affected most of all by broken or leaky 
 bucket valves, next by broken or leaky head valves, and least of all by 
 defective foot valves, particularly so in the case of the newer type of 
 independent condenser which is placed much higher than the bottom 
 of the air pump and allows of complete drainage of the water. Foot 
 valves, although not much required for the maintenance of the vacuum, 
 allow the pump to work steadier and more regularly than would be 
 the case if these valves were omitted or were broken. 
 20 
 
 % 
 
^66 ''Verbal" Notes and Sketches 
 
 Hot-well Temperature and Condenser Back Pressure. 
 
 Neglecting air leakage, the pressure in the condenser can be 
 determined from the hot-well temperature as follows : — Note the 
 hot-well temperature and look up the " Table of Saturated Steam," 
 page 622, for the corresponding pressure. 
 
 Example. — The temperature of the water in the hot-well is 141°. 
 Find the corresponding vapour pressure. 
 
 Answer. — On looking up the Table, page 622, we find that 
 the vapour pressure for this temperature is 3 lbs. absolute, which is, 
 of course, the back pressure in the condenser. 
 
 In actual practice air leakage reduces the hot-well temperature 
 for a given degree of vacuum. 
 
 NOTE.— The actual back pressure on the L.P. piston is usually from i to 2 lbs. 
 in excess of this, as a slight difference of pressure must of necessity exist between 
 the two positions of steam flow. 
 
 From the foregoing it will be evident that it is impossible to 
 have both a high vacuum and high hot-well temperature as the two 
 vary in inverse ratio. With a high temperature of hot-well water 
 the vapour corresponding to the temperature is also high, with, of 
 course, a proportionally reduced vacuum in the condenser. 
 
 General Definitions. 
 
 Heat. — Heat is a form of energy. When the molecules of a body 
 are set in rapid motion or vibration, heat results, and the more rapid 
 the vibration the more intense is the heat generated. The amount of 
 heat given to a body produces a difference in its temperature. Heat 
 may, then, be expressed as molecular energy, and the value of one 
 unit — generally known as one British Thermal Unit, or simply 
 one B.T.U. — is equal to 778 foot-pounds of work. It should always 
 be borne in mind that Heat and Work are mutually interchangeable, 
 Heat giving out Work, and Work done producing Heat. 
 
 Foot-Pound. — I foot-pound of work is equal to a weight of i lb. 
 raised i foot. 
 
 Power. — Power is the amount of work done in a given time (as, for 
 example, per minute). 
 
 Horse-Power. — i Horse-Power (Indicated) is equal to a weight 
 of 33000 lbs. raised i foot in one minute or to a weight of i lb. 
 raised 33000 feet in one minute. 
 
 Unit of Heat. — To raise the temperature of i lb. of water one degree 
 requires the expenditure of 778 foot-pounds of work. This is known 
 as the Mechanical Value of one Heat Unit. 
 
• 
 
 General Notes and Descriptions 367 
 
 Sensible Heat. — Sensible Heat raises the temperature of a body, and 
 ' is measured by the thermometer. 
 
 Latent Heat. — Latent Heat changes the condition of a body (as, for 
 example, ice to water, or water to steam) without adding to its 
 temperature. To change or evaporate into steam i lb. of water at 
 212' temperature requires 966 units of Latent Heat. 
 
 Total Heat. — Total Heat is the sum of the Sensible and Latent 
 Heats. 
 
 Energy. — Energy is the capacity to do work. All energy really 
 originates from the heat of the sun. 
 
 Potential Energy is stored tip energy, as, for example, a raised 
 weight, a coiled spring, gunpowder, and steam in a boiler. 
 
 Kinetic Energy is the energy of motion, as, for example, a moving 
 piston rod, or pump plunger, a revolving shaft, and machines in 
 general. 
 
 NOTE.— Potential Energy when set free changes to Kinetic Energy. 
 
 Force. — F'orce is that which moves or tends to move a body, as, for 
 example, the force of steam, the force of water, the force of gravity, &c. 
 
 Inertia. — Inertia is the natural property possessed by bodies at rest 
 to remain at rest unless acted on by some force, or, if set in motion 
 to continue in motion unless acted on by other forces, such as 
 friction, &c. 
 
 Centrifugal Force. — Centrifugal Force means a force acting outwards 
 from the centre. An example of this is the centrifugal circulating 
 pump where the water enters at the centre and is forced outwards to 
 the circumference or periphery of the vanes. 
 
 Friction. — Friction depends on the pressure exerted and nature of the 
 surfaces in contact, and is independent of surface area. For example, 
 if a small guide shoe is changed for a larger one the total friction is 
 still the same, but the pressure per square inch on the shoe is less 
 The coefficient of friction for lubricated metals is -08, which means 
 that -08 of the pressure exerted is absorbed in overcoming friction. 
 
 Steam. — Steam is an invisible gas obtained by the evaporation of 
 water. It may be expanded to a lower pressure, or compressed to a 
 higher pressure : it can also be condensed back again to water. 
 
 Stress. — Stress means the forces set up in a material to resist strain 
 or fracture, as, for example, a pressure of, say, 100 lbs. acting on a 
 surface of 10 square inches will produce a tensile stress of 1000 lbs. 
 on a stay of i square inch area. 
 
J 
 
 68 "Verbal" Notes and Sketches 
 
 Strain. — Strain means ciiange of form in a structure due to stress, as 
 for example, when a rod is lengthened by tensile stress, or shortened 
 by compressive stress. 
 
 Specific Gravity. — Specific Gravity means the weight of a body com- 
 pared with water and of the same volume. The specific gravity of 
 Wrought Iron is 77, of Mercury 13-5, and of Oil -9. 
 NOTE.— Water is taken as representing the figure i. 
 
 Efficiency. — The efficiency of an engine is lowered by (i) Boiler 
 losses, (2) Engine losses, (3) Mechanical losses, and (4) Propeller 
 losses. The average combined efficiency of a marine boiler, engine, 
 and propeller is only about 6 per cent, of the total, or is represented 
 by the fraction y^. 
 
 Specific Heat (Capacity for Heat). — Is the heat required to raise 
 I lb. of anything 1° in temperature compared with the heat required 
 to raise i lb. of water 1°. 
 
 Specific Heats. 
 
 Water (at 39°) - - - - - i-oo 
 
 Steam (at 212°) - - - - - -48 
 
 Ice ------ -5 
 
 Wrought Iron - - - - •113 
 
 Mercury - - - - - .033 
 
 From the above it will be seen that the amount of heat required to 
 raise i lb. of water 1° in temperature would be sufficient to raise i lb. 
 of wrought iron nearly 9° in temperature, as i -^•113 = 8-8^ 
 
 Hyperbolic Expansion Curve. — This is known as the " Isothermal " 
 or even temperature curve of a gas, and is obtained from the law of 
 Boyle which states that : Pressure x Volume = Constant. 
 
 From this it follows that if the volume of a gas be doubled the 
 pressure falls to half, or if, as shown in the diagram, the original 
 volume of the gas is increased three times, the pressure falls to one- 
 third. Observe that the steam is cut ofif at one-third stroke, and at 
 the end of the stroke the final pressure is only one-third of the initial 
 pressure. 
 
 Adiabatic Expansion Curve. — If heat is neither given to nor taken 
 away from the gas the curve follows out that shown and is then 
 called the "adiabatic" or varying temperature curve. Notice that 
 during expansion the adiabatic line falls below the " isothermal " and 
 during compression rises above it. 
 
General Notes and Descriptions 369 
 
 Entropy. — An " Entropy " diagram represents heat and work, the 
 area rei)resenting heat units per pound, and the depth of the diagram 
 the absohite temperature of the gas. The length of the diagram, or 
 parts of the length, represent the " entropy." This diagram is of 
 great value in estimating the expenditure of cnerg)^ in steam or gas 
 engines. 
 
 Gravity. — The attraction of the earth, known as gravity, causes an 
 accelerating effect in falling bodies of 32 feet per second. This 
 number is commonly expressed as ^=32. 
 
 Momentum. — Momentum means the force or energy acquired by a 
 moving bod)', and is equal to the quantity of Matter multiplied by 
 its \'elocit)' ; or, Mass x Velocity = Momentum. 
 
 Atmospheric Pressure. — At the sea level the Atmospheric Pressure 
 varies between 14^ lbs. (average, 14-7 lbs.) and 15 lbs. per square inch. 
 This pressure is measured by the barometer. 
 
 Gauge Pressure. — "Gauge" Pressure is pressure above that of the 
 atmosphere. Ordinary steam gauges indicate pressures above the 
 atmosphere only. 
 
 Gross, or Absolute, Pressure. — The gauge pressure added to the 
 atmospheric pressure is equal to the " Gross " or " Absolute " Pressure. 
 
 Initial Pressure. — The pressure at the commencement of the stroke 
 is called the " Initial " Pressure. 
 
 Final, or Terminal, Pressure. — " Terminal " Pressure is the pressure 
 at the end of the stroke. 
 
 Effective Pressure. — The " Effective " Pressure is the difference 
 between the steam pressure on one side of the piston and the exhaust 
 pressure on the other side. If the steam pressure is, say, 80 lbs., and 
 the exhaust pressure 10 lbs., then, 80— 10 = 70 lbs. Effective Pressure 
 (not mean effective). 
 
 Mean Effective Pressure is the average effective pressure exerted 
 on the piston throughout the stroke, or during one revolution. This 
 is the pressure required in calculating the Indicated Horse-Power of 
 an engine. 
 
 Combustion is a chemical process, and consists of the combining 
 (chemically) of Carbon of coal with Oxygen of the air, producing COg 
 and heat. 
 
 Complete combustion produces CO^ and water. 
 
 Incomplete „ „ CO and smoke. 
 
 NOTE. — The small percentage of water formed in combustion is due to the 
 combination of the Hydrogen of the Coal and the Oxygen of the air, giving HoO. 
 
370 
 
 " Verbal " Notes and Sketches 
 
 Conservation of Energy. 
 
 By this is meant that energy, Hke matter, is indestructible, and can 
 only be transformed from one state to another. Energy is said 
 to be wasted or lost in overcoming friction, for example, and this 
 reduces the useful energy of a machine, but the total energy remains 
 the same as originally supplied. A dynamo engine of a certain horse- 
 power transforms mechanical energy into electrical energy, but the 
 amount of electrical energy given out by the dynamo is less than 
 the amount of mechanical energy supplied by the engine, as part of 
 the energy is wasted in overcoming friction, weight, &c. Neverthe- 
 less the sum of the energy wasted and the useful energy given out 
 by the dynamo is equal to the energy originally supplied by the 
 engine, and can be all accounted for 
 
 Capillary Attraction. 
 
 The force which causes the oil in an oil cup to creep up the 
 worsted, and so flow down the pipe, is known as " capillary 
 attraction," and is due to the attraction of the molecules of the 
 oil to those of the cotton strands. The absorption of water in 
 a sponge is due to the same force, and the difference in level of a 
 liquid outside and inside of a tube of very fine bore, as shown by 
 the sketches, is another example of the same. 
 
 If in tube A the liquid moistens the tube, the level rises as shown 
 above the normal and is concave. If in tube C the liquid does not 
 moisten the tube, then the level is below the normal and is convex. 
 
 
 ABC 
 No. 72.— Examples of Capillary Attraction. 
 
 Vessel B shows the normal level of the liquid when free from the 
 influence of capillary attraction. 
 
 Siphon. 
 
 By means of a bent pipe with a long and a short leg known as 
 a siphon, water may be caused to flow from one tank to another one 
 lower down in position. 
 
 For the efficient working of a siphon the following requirements 
 are necessary : — 
 
I 
 
 # 
 
 General Notes and Descriptions 
 
 371 
 
 (i.) The height H (sketch) must not exceed 26 feet, which is 
 the practical Hft of a pump by the atmospheric pressure effect. 
 
 (2.) The bent pipe must first be filled with water to start the flow, 
 and this is usually done by drawing out the air in the pipe and so 
 forming a vacuum. 
 
 NOTE. — The siphon will work equally well with cold or hot water, in which, 
 it will be noted, it differs from a pump. The weight of the water in the length 
 D of the pipe is the cause of the flow of water from the one tank to the other, 
 and the longer this is made the faster will the upper tank be emptied of its contents. 
 
 TANK 
 
 No. 73.— Action of Siphon. 
 
 Density of Steam. 
 
 By density of steam is meant the weight per cubic foot volume. 
 The density increases with the pressure, as will be seen on referring 
 to the Steam Table, page 622. 
 
 If the specific volume of the steam be giv'en, the density can be 
 determined as follows : — 
 
372 "Verbal" Notes and Sketches 
 
 Rule. — Density = i -=- specific volume in cubic feet. 
 
 Example. — At i8o lbs. pressure absolute, the specific volume of 
 the steam is 2-49 cubic feet per lb. ; express the density. 
 
 Then density = I -^ 2-49 = -401 lb. nearly ; therefore the dens'ty or 
 weight of each cubic foot of steam at the pressure given is -401 of 
 a pound. 
 
 Shaft or Brake Horse-Power. 
 
 It is now well known that so far no method has been devised, or, 
 in fact, is likely to be devised, for the indicating of the horse-power 
 as done in the case of reciprocating engines, but the actual power 
 transmitted along the shafting to the propeller may be determined 
 by means of the " torsion meter," an instrument which measures the 
 twist or torque put on the shaft by a given power. For accuracy of 
 results it is advisable to have the shafting calibrated beforehand, as 
 different builds of shafts and materials give slightly varying results. 
 
 It should be noted that the shaft horse-power or brake horse-power, 
 as measured by the torsion meter, is the useful horse-power, and that 
 the I.H.P. by comparison is a matter of indifference, the effective 
 horse-power being actually transmitted along the shafting to the 
 propeller being of chief importance. 
 
 Equivalent I.H.P. 
 
 Repeated trials have proved that the ratio of shaft horse-power by 
 torsion meter as compared to indicated horse-power is usually in the 
 ratio of 90 to 100, or -9 to i. 
 
 Therefore, Equivalent LH.P.= Shaft Horse-Power 4- -9. 
 
 Example. — The collective shaft horse-power by torsion meter is 
 found to be 8100; calculate the equivalent I.H.P. 
 
 Then, Equivalent LH. P. =8100-=- -9 = 9000. 
 
 Dryness Fraction (or Factor). — In considering the actual work 
 done by steam, it is important that the dryness fraction be taken into 
 account, as the result greatly depends on this quantity. After work 
 is done by adiabatic expansion, the steam contains a certain amount 
 of water, which proportionally reduces the internal heat still left in 
 the steam. The dryness fraction is the ratio between the weight of 
 dry steam per pound and the weight of the dry steam and water 
 added together ; 
 
 Or. -_Weightofdry steam ^Dryness Fraction. 
 
 \A/eight of dry steam + weight of water 
 
 Suppose the water to be 25 per cent, of each pound weight of 
 mixture. 
 
 Then, — ^^ = 75 = _5 _ 3 = Dryness Fraction. 
 
 100 100 20 
 
General Notes and Descriptions 2>73 
 
 So that after expansion and work done by the steam the actual units 
 or foot-pounds of energy left are, in this case, equal to the internal 
 heat units multipHed by the fraction ^. 
 
 Total Heat of Steam. — By the total heat of saturated, or boiler 
 steam, is meant the number of heat units required to produce i lb. 
 of steam from a temperature of 32' Fahr. to any given temperature 
 and pressure. The total heat includes the latent heat of steam 
 formation and the sensible or thermometer heat. 
 
 Rule.— 1083 + -3 xT° = Total Heat (above 32° Fahr.). 
 
 Where, T" = Temperature of the steam (Fahr.). 
 
 Internal Heat of Steam. — By this is meant the heat or energy 
 required to change i lb. of water into steam at any given pressure. 
 
 External Heat of Steam. — By this is meant the heat required to 
 produce increase of volume (water to steam) against an external 
 resistance or pressure. 
 
 Latent Heat of Steam. — The sum of the Internal heat and External 
 
 heat is equal to the latent heat. 
 
 The Latent Heat can be calculated as follows : — 
 
 Rule.— iii4-7xT° = Latent Heat. 
 
 Where, T° = Temperature of the steam (Fahr.). 
 
 Example. — Calculate the Total Heat, Latent Heat, and Sensible 
 Heat of I lb. of steam at 160 lbs. pressure by gauge. 
 
 160+15=175 lbs. Absolute pressure and 371° Temperature (from Table, page 622). 
 Then, 1083+ -3x371 = 1194-3 Total Heat, 
 
 and 1114- -7x371= 854-3 Latent Heat. 
 
 Therefore, 371° -32°= 333-9 Sensible Heat. 
 
 NOTE.— The above are all calculated from a temperature of 32° Fahr. 
 
 Potential Energy is the energy contained or stored up in steam of 
 a given pressure and temperature, the amount of energy contained 
 increasing with the pressure and the temperature. 
 
 Kinetic Energy is the result of setting free the potential or stored- 
 up energy of the steam, which then shows as active energy in the 
 performance of work. In a steam-engine the steam acts on the 
 pistons, and by causing motion to take place work is done, and, as 
 a result, the steam falls in pressure and in temperature. In a turbine, 
 the steam at a given pressure and velocity leaves the first row of 
 guide blades, and striking the first row of moving blades gives up 
 
374 " Verbal " Notes and Sketches 
 
 part of its kinetic energy, which results in a decrease in pressure and 
 in heat. 
 
 Adiabatic Expansion. — If steam expands in a cylinder or turbine 
 casing, and neither receives heat from any external source nor gives 
 out any heat externally, then the expansion is said to be " adiabatic," 
 and all work done in the cylinder or turbine is obtained at the 
 expense of the internal heat of the steam, which in falling in pressure 
 and temperature conforms to this condition, and part of which 
 condenses. In the cylinders of a marine engine of the reciprocating 
 type, the expansion is approximately hyperbolic or isothermal, and 
 in a turbine the expansion is approximately " adiabatic." 
 
 Hyperbolic or Isothermal Expansion. — This is founded on the 
 well-known law of Boyle and Marriot that the pressure of a gas varies 
 inversely as the volume ; or, as it is expressed — 
 
 Rule. — Pi X Vj = Po X V2 = Constant. 
 
 Where, Pi = Initial pressure. Where, P2= Final pressure. 
 
 ,, Vi = Initial volume. „ Vg^ Final volume. 
 
 Therefore, ?iAYi = Vg ; 
 
 "2 
 
 and, PjiZ) = p,; 
 
 and, P^V2=Pj, 
 
 Pi 
 
 2X_\ 
 
 Vi 
 
 Foot- Pound. — A foot-pound is the work done in raising a weight 
 of I lb. up through a distance of i foot. 
 
 Torque. — Torque is the turning movement to which a shaft is sub- 
 jected when a force is exerted to rotate the shaft against a resist- 
 ance such as that of the screw propeller in water. In ordinary 
 engines the turning effort or torque is applied by means of the crank, 
 and in turbines by the direct energy of the steam acting on the 
 periphery of the blade circle of the rotor. 
 
 Heat. — Heat is merely a form of energy, and as such exists in two 
 states — (i) in that of Potential or stored-up energy, and (2) in that 
 of Kinetic or active energy. When the molecules of a body or gas 
 are set in rapid motion or vibration, heat is developed and work 
 done. Consequently in the case of a steam-engine, either of the 
 reciprocating type or turbine type, the energy which produces 
 rotation of the shaft is obtained by means of the transformation of 
 heat energy into mechanical work. 
 
General Notes and Descriptions 
 
 375 
 
 150 1 
 
 bs. 
 
 
 
 
 
 
 (I) 
 
 » 
 
 Isothermal or Hyperbolic Curve, PxV = Constant (Perfect Gas). 
 
 
 
 \ (2) 
 
 Saturation Curve, P xV^^' = Constant (Reciprocating Engine, ap- 
 proximately). 
 
 
 
 U ^^^ 
 
 Adiabatic Curve, P x V^** = Constant (Turbine Engine, approxi- 
 mately). 
 
 » 
 
 r — ® 
 
 
 
 
 vvX. „. .. /^ 
 
 
 \\\ 
 
 
 
 
 ^^-(D 
 
 A.L. 
 >V.L. 
 
 
 
 ^^^^^:^___ 
 
 
 
 
 
 
 No 
 
 74.— Expansion Curves of Steam. 
 
 
 British Thermal Unit (B.Th.U.). — This is taken as being equal to 
 778 foot-pounds of work or energy, and signifies that one heat unit, 
 when transformed into mechanical energy, gives out 778 foot-pounds 
 of work. 
 
 Saturated Steam. — Steam taken direct from the boilers is known 
 as " saturated steam," as the density, or weight of water per cubic 
 foot, is constant for any given pressure, as also is the temperature 
 and volume. The steam supplied to all marine engines (without 
 superheaters) is therefore of this quality, and calculations as to expan- 
 sion, work done, and fall of pressure, are usually made on this 
 assumption. The steam supplied to the H,?, turbine of a turbine 
 
'ii'jd "Verbal" Notes and Sketches 
 
 engine is therefore saturated steam. Sometimes the term "dry- 
 saturated steam " is used to distinguish this quality of steam from 
 wet steam, or steam containing water from priming. 
 
 "Wet" Steam. — If water is carried off with the steam due to 
 priming taking place in the boilers, the steam contains more water 
 per cubic foot than is natural to the " saturation " pressure, volume, 
 and temperature, and it is then known as " wet steam," or " wet 
 saturated steam." 
 
 Superheated Steam. — If saturated steam from the boilers is passed 
 through the tubes of a superheater, the water contained in the steam 
 is evaporated out of it, with the following results : — 
 
 1. Rise of temperature. 
 
 2. Increase of volume if pressure is kept constant ; or, 
 
 3. Increase of pressure if volume is kept constant. 
 
 The chief advantage of superheated steam lies in the fact that 
 cylinder condensation is practically eliminated, as the steam does 
 not then readily condense when exposed to cooled surfaces : leakage 
 is also reduced. 
 
 Another point of importance is that the specific heat of this 
 steam being only -48 (some authorities give -5), one B.T.U. of 
 heat supplied to the steam has the effect of raising its temperature 
 fully two degrees, as i -^ -48 = 2-08. 
 
 Boyle's Law of Expansion. 
 
 Boyle's Law of expansion states that "The pressure of a gas 
 varies inversely as the volume if kept at constant temperature." 
 Or, PxV=C; therefore, C 4- V = P, or, C-rP = V, 
 
 where P = Absolute pressure, 
 ,, V = Volume in cubic feet, 
 ,, C = Constant. 
 
 This means that the pressure multiplied by the volume is always 
 equal to a constant number, or in other words what is lost in pressure 
 is made up in volume or vice versa, so that the result of the multi- 
 plication is always the same. 
 
 Example i. — The H.P. initial pressure is 185 lbs. gauge pressure, 
 and the cut-off -6 ; find the pressure at the end of the stroke. 
 
 Rule— 
 
 PxV=C; therefore, (185 + 15) x -6 = 120= C. 
 
 c v., 
 
 Again, 120 4- 1 = 120 lbs. absolute = Po, 
 and, 120-15 = 105 lbs. gauge pressure. 
 
 It should be noted that the initial pressure is 185+15, or 200 lbs. 
 absolute, and the volume -6, also that at the end of the stroke (release) 
 the volume will be equal to i. 
 
General Notes and Descriptions '^']'] 
 
 Example 2. — Initial pressure, 160 lbs. gauge, and volume, 2-56 
 cubic feet ; find the volume when the pressure drops down to 80 lbs. 
 gauge. 
 
 Then, 160+ iS=i7S = P„ 8o + iS=9S=P2. 
 
 Pi V, 
 Therefore, 175 x 256 = 448 = C, 
 
 C Po 
 
 and, 448 V 95 = 4-71 cubic feet^Vj. 
 
 NOTE.— On referring- to the Steam Table, page 622, it will be seen that the 
 actual volume of saturated steam at 95 lbs. pressure absolute is 4-54 cubic feet in 
 place of 471 cubic feet as brought out by Boyle's Law, which difference is prin- 
 cipally due to the fact that, under practical conditions, fall of pressure is accompanied 
 by fall of temperature. 
 
 Example 3. — The L.P. initial pressure is 1 1 lbs. by gauge, and 
 the cut-off -5 stroke ; find the terminal pressure at end of stroke. 
 
 Then, 11 + 15 = 26 lbs. = Pi, and •5 = Vi, 
 
 so that, 26 X -5 = 13 lbs. absolute = C, 
 then, I3-M = I3 = P2 absolute. 
 
 Notice that Vo= i, that is, the whole volume of the cylinder. 
 
 Cylinder Clearance Allowance. — For even approximate results it 
 is necessary that the clearance volume of the cylinder should be 
 allowed for, so that the rule corrected for this reads thus : — 
 
 (Cut-off + clearance) x Initial pressure = (Release + clearance) x Terminal pressure. 
 
 Example 4. — H.P. initial pressure, 165 lbs. gauge ; cut-off, -6 ; 
 clearance volume, 10 per cent, that of cylinder; find gauge pressure 
 at end of stroke (release). 
 
 Then, Clearance= — — = -i (assuming cylinder as unit i). 
 100 
 
 Therefore, (•6 + -i)x i8o = (i + -i) x P, 
 
 so that, P = :7jil8o^j e lbs. absolute, 
 i-i 
 
 and, ii4-S-iS = 99-5 lbs. gauge terminal pressure. 
 
 NOTE.— If the LP. receiver is, say, 1-4 times the capacity of the H.P. cylinder, 
 then, 1 14-5 -M -4 =81 -7 lbs. absolute, and 817 -15 = 66-7 lbs. on LP. receiver gauge. 
 
 Example 5. — Apply Boyle's Law and find the H.P., LP., and 
 L.P. terminal gauge pressures, also the I. P. and L.P. receiver 
 pressures; given H.P. initial, 155 lbs. gauge; H.P. cut-off, -6; 
 I. P. cut-off, '5 ; L.P. cut-off, -4 ; clearance volume, 10 per cent, in each 
 case. LP. receiver=i-4 times H.P. cylinder volume, and L.P. 
 receiver = 1-5 times LP. cylinder volume. 
 
^yS "Verbal" Notes and Sketches 
 
 H,P. Cylinder. 
 
 15s + 15 = 170 absolute, 
 
 I X 10 
 
 = •1 clearance. 
 
 100 
 
 Tnen, (•6 + -i)xi7o=(i + -i)x P. 
 Therefore, 
 
 P= ~~-= 108 lbs. absolute, and 108 - 15-93 lbs. gauge terminal pressure 
 
 LP. Receiver. 
 
 H.P. terminal pressure = 108 lbs. absolute, 
 Therefore, Receiver^ 108^ 1-4 = 77 lbs. absolute, 
 and, 77- 15=62 lbs. gauge. 
 
 LP. Cylinder. 
 
 (•5 + .i)x77 = (i + .i)xP. 
 
 Therefore, p= ' - ^'i =il2 lbs. absolute, 
 i-i 
 
 and, 42-15=27 lbs. gauge terminal pressure. 
 L.P. Receiver. 
 
 I. p. terminal pressure = 42 lbs. absolute. 
 Therefore, Receiver = 42 -fi -5=; 28 lbs. absolute, 
 and, 28-15 = 13 lbs. gauge. 
 NOTE— The foregoing is only approximate, as the cut-off in following cylinder 
 affects the pressure in previous receiver. 
 
 L.P. Cylinder. 
 
 (•4-f .i)x28 = (i + -i)xP. 
 
 Therefore, P = '^^^= 127 lbs. absolute, 
 i-i 
 
 Observe that the last pressure found is equal to about 2\ lbs. below 
 that of the atmosphere. 
 
 Boyle's law of expansion may, as before stated, be expressed as ^ 
 follows : — 
 
 Pj X Vj = Po X V.,, or, Pi X Vi = Constant. 
 Therefore. ?i^ = P.,, or,?i^' = v„. 
 
 A^«;« PoxVo ,, ^, PoxV., D 
 
 Again, -p ^ =Vi, or, _^ -=Pi. 
 
 Where Pi = Initial absolute pressure, 
 ,, Vi = Initial volume, 
 ,, Po = Terminal absolute pressure, 
 ,, V._, = Terminal volume. 
 
 At constant temperature the initial pressure absolute multiplied by 
 the volume is equal to the terminal pressure absolute multiplied 
 by the volume, which simply means that as the pressure decreases 
 the volume increases proportionally, or vice versa. What is lost in 
 
 « 
 
 
■ General Notes and Descriptions 379 
 
 pressure is gained in volume, or what is gained in pressure is lost 
 in volume. After the cut-off takes place we have an example of 
 decrease in pressure and increase in volume, and when the exhaust 
 closes we have an example of decrease of volume and increase of 
 pressure (compression). 
 
 Example i. — H.P. initial pressure, 165 lbs. gauge ; cut-off, '6 ; find 
 the pressure at end of stroke. 
 
 (I.) Then, P, x Vj^P.x V,= i8ox .6=PoX i. 
 
 Therefore, i8ox -e ^p^^^^g j^^ absolute, 
 
 and, 108-15=93 lbs. by gauge. Answer. 
 
 Observe that the volume at cut-off is -6 of stroke, and at the end 
 of stroke the volume is i or the full stroke, also 1654- 15 = 180 lbs. 
 absolute pressure. At the end of the stroke the pressure is therefore 
 93 lbs. gauge, but when the steam flows into the M.P. chest the 
 pressure drops still further owing to the receiver capacity being 
 greater than that of the preceding cylinder, assuming that the 
 M.P. receiver is 1-4 times the capacity of the H.P. cylinder. 
 
 Then, 108^1-4 = 77 lbs. absolute, 
 
 and, 77—15 = 62 lbs. gauge in M.P. chest. 
 
 NOTE. — It must be remembered that in all steam expansion problems the 
 pressures must be expressed as absolute or gross. 
 
 Example 2. — H.P. initial pressure, 170 lbs. gauge; cut-off, -6; 
 M.P. receiver capacity, 1-4 times that of H.P. cylinder ; cut-off in M.P 
 cylinder, -5 ; L.P. receiver capacity, 1-5 times that of M.P. cylinder; 
 cut-off in L.P. cylinder, -5. Determine (i) the H.P. terminal gauge 
 pressure, (2) the M.P. receiver gauge pressure, (3) the M.P. terminal 
 gauge pressure, (4) the L.P. receiver gauge pressure, and (5) the 
 L.P. terminal absolute pressure. 
 
 Then, 170+15=185 lbs. absolute H.P. initial pressure, 
 and, PixVi = PoX Vo = i85x.6=P.,xi. 
 
 Therefore, 
 - ^^ =111 lbs. absolute, and 111-15 = 96 lbs. gauge terminal pressure H.P. 
 
 Again, 
 
 iii-ri-4=79'2 lbs. absolute, and 79-2- 15 = 64-2 lbs. gauge M.P. receiver pressure. 
 
 (2.) PixVi = P.2xVo = 79-2x.5=PjXi. 
 
 Therefore, 
 
 79-2 X -5 -^^.5 lbs absolute, and 39-6-15 = 24-6 lbs. gauge terminal pressure M.P. 
 
 Again, 39-6+1-5 = 26-4 lbs. absolute in L.P. receiver, 
 
 or, 26-4 - 15= 1 1-4 lbs. gauge in L. P. receiver. 
 
380 "Verbal" Notes and Sketches 
 
 (3.) PjX Vi = PoX Vo = 26-4X.S = P2XI. 
 
 Therefore, gP'4^ '5 - 12-2 lbs. absolute terminal L.P. pressure. 
 
 Observe that the L.P. terminal pressure is belozv that of the atmosphere. 
 
 It should be noted that the foregoing rule assumes the steam 
 to act as a perfect gas, whereas in actual practice the conditions 
 are somewhat different as shown below. 
 
 (i.) Difference due to initial cylinder condensation and re- 
 evaporation. 
 
 (2.) Difference due to the steam being of the condition known 
 as " saturated " (see page 622). 
 
 (3.) Difference due to work done by the steam on the piston. 
 
 These differences produce a drop in the pressure for any given 
 expansion below that as determined by the rule given. The saturated 
 steam expansion curve drawn out on page 375 illustrates clearly the 
 difference referred to and should be compared with the isothermal 
 curve. 
 
 Steam Expansions by Pressures and by Volumes. — The differences 
 in the action of the steam under practical conditions, as compared 
 with Boyle's Law, naturally results in a difference in the number 
 of expansions obtained throughout the cylinders. 
 
 Example i. — Find the total number of expansions by pressures if 
 the H.P. initial pressure is 165 lbs. gauge, and the L.P. terminal 
 pressure 12 lbs. absolute ; also by volumes if the cylinder ratio is 
 as I : 27 : 7-2 and the H.P. cut-off -6. 
 
 Rule. — H.P. initial pressure (absolute)^ L.P. terminal pressure 
 (absolute) = No. of Expansions by Pressures. 
 
 165+15 = 180 lbs. absolute. 
 Therefore, i8o-f 12— 15 Expansions by pressures. 
 
 Rule. — L.P. ratio -f H.P. cut-off = No. of Expansions by Volumes. 
 Therefore, 7-2+ -6=12 Expansions by volumes. -M 
 
 In practice the pressure at the end of L.P. stroke, being less than 
 that found by Boyle's Law, gives a correspondingly increased number 
 of expansions as compared with the number of expansions obtained 
 by the volumes. 
 
 Charles' Law. 
 
 A. The pressure of a gas at constant volume varies with its 
 absolute temperature. 
 

LBS 
 175 
 
 No. 74a. Pressure and I.H.P. for Heat Efficiency Calculatii 
 
 {Ti fa,c page 38 1, 
 
General Notes and Descriptions 381 
 
 B. The volume of a gas at constant pressure varies with its 
 absolute temperature. 
 
 Example i. — A superheater contains 200 cubic feet of steam 
 at a constant pressure of 165 lbs. gauge ; find the volume when the 
 temperature is raised to 450° Fahr. 
 
 NOTE.— Absolute temperature = Fahr. Temp. +461°. 
 
 Therefore, 165 + 15= 180 lbs. Absolute and Temperature of 373° Fahr. 
 
 and, 373 + 461 = 834° Absolute Temp. , 
 
 again, 450 + 461 = 911° ,, ,, 
 
 then. As 834 : 911 :: 200 : 218-4 cubic feet. Answer. 
 
 Example 2. — If the pressure of a gas is 150 lbs. absolute, and 
 the temperature 366° Fahr., find the pressure if the gas is heated up 
 to 400° Fahr. 
 
 Then, 366 + 461=827, and 400 + 461=861. 
 Therefore, As 827 : 861 : : 150 : 1574 lbs. Absolute. Answer 
 
 Heat or Thermal Efficiency. 
 
 Data — 
 
 Cylinders — 24, 40, 65 inches. 
 
 Stroke — 3 feet 6 inches. 
 
 Revolutions — 72. 
 
 H.P. steam — 175 lbs. gauge. 
 
 LP. steam — 60 „ 
 
 L.P. steam — 10 „ 
 
 Vacuum — 24 inches. 
 
 I.H.P. of H.P. cylinder - - 472 
 
 I.H.P. of LP. cylinder - - 566 
 
 I.H.P. of L.P. cylinder - - 540 
 
 LH.P. collective - - - 1,578 
 
 Coal per twenty-four hours — 28 tons. 
 Coal per LH.P. hour — 1-65 lbs. 
 
 Rule. — 
 
 Work done + Heat supplied = Efficiency, 
 
 and. Heat supplied - Work done=Heat rejected. 
 
 Again, Heat supplied (per pound water or steam) = 1115+ -3 xT°-/°. 
 
 Where, T° = H.P. Initial steam temperature. 
 
 /° = L.P. Exhaust steam temperature. 
 
 Work done in heat units per I.H.P. =3300°^ ^ = 2545 Heat Units per hour. 
 
 778 
 
 NOTE.— 778 foot-pounds of work = i Heat unit value. 
 Heat supplied per I.H.P. hour = pounds feed water per I.H.P. x Heat per pound, 
 
 27 
 

 » 
 
 l.ER 
 AM. 
 
 381. 
 
General Notes and Descriptions 381 
 
 B. The volume of a gas at constant pressure varies with its 
 absolute temperature. 
 
 Example i. — A superheater contains 200 cubic feet of steam 
 at a constant pressure of 165 lbs. gauge; find the volume when the 
 temperature is raised to 450" Fahr. 
 
 NOTE.— Absolute temperature = Fahr. Temp. +461°. 
 
 Therefore, 165 + 15= 180 lbs. Absolute and Temperature of 373° Fahr. 
 
 and, 373 + 461 = 834° Absolute Temp. , 
 
 again, 450 + 461=911° ,, ,, 
 
 then. As 834 : 911 : : 200 : 218-4 cubic feet. Answer. 
 
 Example 2. — If the pressure of a gas is 150 lbs. absolute, and 
 the temperature 366° Fahr., find the pressure if the gas is heated up 
 to 400° Fahr. 
 
 Then, 366 + 461=827, and 400 + 461=861. 
 Therefore, As 827 : 861 : : 150 : 157-4 ll's. Absolute. Answer 
 
 Heat or Thermal Efficiency. 
 Data — 
 
 Cylinders — 24, 40, 65 inches. 
 
 Stroke — 3 feet 6 inches. 
 
 Revolutions — 72. 
 
 H.P. steam — 175 lbs. gauge. 
 
 LP. steam — 60 „ 
 
 L.P. steam — 10 „ 
 
 Vacuum — 24 inches. 
 
 I.H.P. of H.P. cylinder - - 472 
 
 I.H.P. of LP. cylinder - - 566 
 
 LH.P. of L.P. cylinder - - 540 
 
 LH.P. collective - - - 1,578 
 
 Coal per twenty-four hours — 28 tons. 
 Coal per LH.P. hour — 1-65 lbs. 
 
 Rule. — 
 
 Work done + Heat supplied = Efficiency, 
 and, Heat supplied - Work done = Heat rejected. 
 
 Again, Heat supplied (per pound water or steam) = 1 1 15 + -3 x T° - A 
 'Where, T° = H.P. Initial steam temperature. 
 
 /° = L.P. Exhaust steam temperature. 
 
 Work done in heat units per I.H.P. = 33000 >< 6O -2545 Heat Units per hour. 
 
 778 
 
 NOTE.— 778 foot-pounds of work = i Heat unit value. 
 Heat supplied per I.H.P. hour = pounds feed water per I.H.P. x Heat per pound, 
 
382 "Verbal" Notes and Sketches 
 
 Application. — To apply the above rules to the case shown in the 
 sketch facing page 381 : — 
 
 Heat supplied = 1,115 + -3x377.5 -160= 1068-25 Heat Units per pound steam. 
 
 NOTE.— 175 + 15-190 lbs. absolute, and temperature (from Table, page 622) 377.5. 
 Heat given up as work per I.H.P. hour = 2545 units. 
 
 Pounds water (or steam) per I.H.P. hour 1 _ 28 x 2240 x 8.8 _ ^ ^ j^^ nearly 
 (Evaporation assumed as 8-8 lbs.) / 1578 x 24 
 
 NOTE.— The evaporation of water per pound coal is the most troublesome item 
 to obtain with any degree of accuracy ; it can, of course, be determined by actual 
 evaporative tests, but the most satisfactory method is that adopted in Admiralty 
 trials w^here measuring tanks are employed which record the actual amount of 
 feed water entering the boilers during a given period. It should be noted that 
 the steam (or water) used per I.H.P. is the true test of economy as the quality 
 of coal varies greatly, and therefore does not constitute a reliable standard of 
 comparison. 
 
 Then, 14-6 x 1068.25 = 15489-625 Heat Units supplied per hour 
 
 Therefore, Efficiency = 2545 + 15489-625 = - 164, 
 
 and •164x100=16-4 per cent. Thermal Efficiency. 
 
 It will thus be seen that of 15489-625 Heat Units supplied only 
 2545 Heat Units appear as actual work done in the engine. 
 
 Pressures, Volumes (Sketch facing page 381). 
 
 The following data of pressures, volumes, and temperatures 
 throughout the range of cylinders and receivers should be carefully 
 studied by the student. 
 
 ( Pressure =175 lbs. gauge. 
 H.P. valve chest < Specific Volume = 2-43 cubic feet per pound, 
 ( Temperature = 377-5° Fahr. 
 
 ( Pressure = 60 lbs, gauge. 
 LP. valve chest < Specific Volume = 5-68 cubic feet per pound. 
 ( Temperature = 307 -5° Fahr. 
 
 { Pressure = 10 lbs. gauge. 
 Specific Volume = 15-97 cubic feet per pound. 
 Temperature = 240° Fahr. , 
 
 I" Pressure = 2-8 lbs. absolute. 
 Condenser - - < Specific Volume =117 cubic feet per pound. 
 ( Temperature = 140° Fahr. 
 
 NOTE.— The above figures assume saturated steam at all stages of expansion, 
 but this is not strictly the case in practice, as the steam expands to a certain 
 
General Notes and Descriptions 
 
 383 
 
 amount adiabatically, which results in reduced steam volume per pound at the 
 latter stages of expansion, part of the steam condensing in the performance of 
 work. The "dryness fractions" of the steam produced in this way may therefore 
 show somewhat like the following :^ 
 
 
 H.P. Valve 
 Chest. 
 
 II. P. 
 Cylinder. 
 
 LP. 
 
 Cylinder. 
 
 L.P. 
 Cylinder. 
 
 Dryness Fraction of Steam - 
 
 I (dry) 
 
 •9 
 
 •8 
 
 .78 
 
 of water 
 pproximated 
 
 As a set-back against the above it should, however, be noted that 
 the steam in the receivers is more or less superheated, owing to 
 simple expansion into the receivers from the preceding cylinders, 
 without actual work being done during such expansion. 
 
 Taking the I. P. chest the pressure is 75 lbs. absolute, and the 
 specific volume 5-68, then 5-68 x •8 = 4-524 cubic feet, as the actual 
 volume when the dryness is -8, the remainder of the steam having 
 condensed in the performance of work. 
 
 Steam Consumption per Revolution. — For methods of calculating 
 the steam (or feed water) consumption of an engine see author's 
 "Marine Indicator Cards." 
 
 Water formed by Initial Condensation. — The weight 
 produced by cylinder initial condensation may be closely app 
 by the following rule, assuming that the H.P. initial steam is ui ury 
 saturated quality and free from priming water. 
 
 Steam condensed = Pounds steam in H.P. per rev. - (pounds steam in L.P. per rev, 
 + steam condensed by work done in engine). 
 
 Example. — The weight of steam used per revolution in the H.P. 
 cylinder from the H.P. cards is 6-2 lbs., and the steam used in the 
 L.P. cylinder from the L.P. cards is 4-25 lbs. If the weight of steam 
 condensed by work done is 1-3 lbs., find the amount of water formed 
 by initial condensation in the cylinders. 
 
 Then, weight = 6-2- (4-25 + 1 -3) = '65 of a lb. per revolution. 
 
 Work done during Adiabatic Expansion. — To calculate the work 
 done, or, which is the same thing, the units of heat given up or con- 
 verted into work during the adiabatic expansion of steam in a 
 turbine, the following data are required : — 
 
 The absolute temperature of the steam before and after expansion. 
 
 The latent heat of the steam before and after expansion. 
 
 The dryness factor of the steam before and after expansion. 
 
384 "Verbal" Notes and Sketches 
 
 Let, Ti° = Absolute temperature before expansion. 
 
 T2° = Absolute temperature after expansion. 
 Hi = Latent heat before expansion. 
 Ho = Latent heat after expansion. 
 /i = Dryness factor before expansion. 
 /, = Dryness factor after expansion. 
 The heat energy given out in British Thermal Units = 
 /ixH,-/!xH2 + Ti°-T2° = B.T.U. 
 
 Example. — Find the work done per pound of steam in expanding 
 adiabatically from an H.P. initial pressure of 180 lbs. gauge, to a 
 terminal L.P. pressure of 10 lbs. absolute, the dryness fractions 
 being 'gg and 76 respectively. 
 
 Then, 180+15 = 195 lbs. absolute = 3797 temperature from Table, page 622. 
 
 Latent heat = 8465 B.T.U. from Table. 
 And, 10 lbs. absolute = 193-3 temperature. 
 
 Latent heat =1140-3 B.T.U. 
 Therefore, 379-7 + 461 = 840-7 absolute temperature, 
 
 and, 193-3 + 461=654-3 absolute temperature. 1 
 
 f. Hi /., U, Tj T, 
 Then, -99 x 846-5 - -76 x 1 140-3 + 840-7 - 654-3 = 
 
 838-035 - 866628 + 840-7 - 654-3 = 1678-735 - 1520-928 = 157-807 B. T. U. 
 Foot-pounds = 157-807 x 778 = 122768-4 foot-pounds. 
 
 Advantages of High Pressure Steam. 
 
 To prove the economy of high pressure steam as compared with low 
 pressure steam. 
 
 Compound 80 lbs. pressure = 324° temperature. 
 Triple 180 ,, ,, = 380° „ 
 
 1115 + .3 x 324 = 1212-4 units of heat required. 
 1115 + .3 x 380 = 1229 units ,, ,, 
 
 Then 1229- 1212-4= 16-6 additional units of heat required to give more 
 than double the pressure. 
 
 High pressure steam is stronger and more expansive than low pressure 
 steam, therefore a lesser quantity of it will do the same work. 
 
 So that, per cent, extra fuel = =1-36 per cent 
 
 ^ I2I2-4 -* *^ 
 
 It can be proved by calculation that the higher pressure steam gives out 
 fully 20 per cent, more power than the lower pressure steam, owing to the j 
 greater range of expansion obtained : therefore the clear gain in economy i 
 resulting from the higher pressure = 20 - 1-36 - 18-64 P^r cent, (see also pages 
 398-399)- j 
 
 Advantages of Using a Number of Cylinders. 
 
 Neglecting the advantage of two or more cranks in regard to the stresses 
 on the crank shafting, the principal gain by having, say, three cylinders is 
 that the pressure is lowered a certain amount in each cylinder, and the drop 
 of temperature does not take place all at once, but is divided into three 
 stages; the re-evaporation of the H.P. doing work in the ALP. cylinder, 
 and the re-evaporation of the M.P. doing work in the L.P. cylinder, only the 
 L.P. re-evaporation of the L.P. being lost in the condenser; therefore the 
 condensation losses, due to the cyhnder cooling down during exhaust, are , 
 much reduced. I 
 
General Notes and Descriptions 385 
 
 If we were to use steam of 200 lbs. pressure in one cylinder, 
 instead of in three cylinders, the great difference of temperature 
 occurring between admission and exhaust would cause excessive 
 condensation to take place owing to the cooling of the cylinder during 
 exhaust, but, by dividing this drop of temperature into a number 
 of cylinders the condensation losses are proportionally decreased 
 owing to the counterbalance by re-evaporation. 
 
 In a single cylinder engine the re-evaporation creates back pres- 
 sure, which reduces the power, and thus represents a loss. 
 
 Cylinder Ratios and Steam Expansions. 
 
 In compound engines the ratio of H.P. to L.P. cylinder is 
 usually about i to 4, and in triple expansion engines about i to 7, 
 or I to 7-25. 
 
 I 
 
 To find cylinder ratios — L.P. dia."-fH.P. dia.2= Ratio, 
 or L.P. dia.2-i- LP. dia.-2 = Ratio. 
 
 If the steam is cut off at half stroke in the H.P. cylinder, this 
 equals two expansions in the H.P. ; then 2x4 = 8 expansions 
 altogether in compound engines. 
 
 For triple, 2 x 7= 14 expansions, or 7-fi= 14 expansions. 
 Or, L.P. Ratio -^ H.P. cut-off = total Expansions. 
 
 Example. — Cylinder Ratios are as i : 2-7 and 7-2 H.P. cut- 
 off -6 ; find No. of expansions by volumes. 
 
 Then, 7-2 -^ -6 =12 Expansions (Volumes). 
 
 NOTE. — To find number of expansions by pressures, divide initial absolute 
 pressure by final absolute pressure. 
 
 If we take the cut-off at one- third stroke, the 3x4=12 expan- 
 sions in compound engines, and 3x7 = 21 expansions in triple 
 engines. 
 
 In working out the number of steam expansions the size of the 
 H.P. cylinder and L.P. cylinder only are required, as the LP. makes 
 no difference in the result, the reason being that the initial zx\6. final 
 volumes of the steam limit the expansion range. 
 
 Cut-off and Pressures. 
 
 The final pressure, or pressure at the end of the stroke, is exactly 
 proportional to the cut-off. 
 
 If the cut-off is at half stroke, the final pressure will be half of 
 the initial pressure, and so on. 
 
 Example. — Initial pressure, lOO lbs. gross; cut-off, 15 in.; 
 and stroke, 30 in. ; find the pressure at 20 in. of the stroke, at 
 25 in., and at the end of the stroke. 
 
 \ 
 
386 "Verbal" Notes and Sketches 
 
 lO^ibs^.^JSi"- =75 lbs. at 20 in. of stroke. 
 20 in. 
 
 100 lbs. X 15m. ^ gQ jjjg ^^ j^ ^f g^^^jj^g 
 
 25 in. 
 100 lbs. X 15 in. ^ i^g ^^ g^^ ^f ^^^^^^ 
 
 30 in. 
 
 NOTE.— The above are all gross pressures; therefore if the answer is required 
 to be expressed as gauge pressure, 15 lbs. must be subtracted from the result in 
 each case. 
 
 Expansion of Steam and Heat. — Steam expanding in a cylinder, 
 and doing work on the piston, falls in pressure and in temperature^ 
 the fall in heat ("heat drop") corresponding to i B.T.U. for each 
 778 foot-pounds of work done. 
 
 Steam expanding withoiit doing work, as for example from 
 the exhausting position of one cylinder to the receiver of the next 
 engine, falls in pressure by expansion, but only slightly in tempera- 
 ture ; in a word, the steam becomes superheated. Steam therefore 
 in the LP. or L.P. receivers, at a given pressure, is usually at a 
 higher temperature than that corresponding to the pressure shown 
 on the gauge. 
 
 A similar result is obtained with reduced steam from a reducing 
 valve, as the steam having only to do a small amount of work in 
 compressing the spring, falls in pressure, but not nearly so much, 
 proportionally, in temperature ; the reduced steam ' is thus, to a 
 certain degree, superheated. 
 
 Expansion of Water by Heat. 
 
 The following table shows the relative volume of water at various 
 pressures and temperatures, and the gradual expansion with rise of 
 temperature should be noted. 
 
 Temperature and Relative Volume of Water. 
 
 Pressure 
 (Gauge). 
 
 Temperature. 
 
 Volume. 
 
 
 60 
 160 
 180 
 200 
 220 
 
 212' 
 
 307-5° 
 370-8' 
 
 379-7° 
 381-7° 
 389-9° 
 
 I 043 
 1093 
 1-136 
 I-142 
 I-148 
 1-154 
 
 From the above it will be seen that for a given weight of water 
 (say I lb.) the level will be higher with a higher temperature. An 
 example of this may be found in the case of the water gauge glass, 
 
General Notes and Descriptions 387 
 
 which in many cases shows a lower level than the actual water level 
 in the boiler, the difference being due to the colder water in the glass 
 occupying a lower level. 
 
 Suction Lift of Pumps. 
 
 Tiic suction lift of a pump depends on the vacuum obtained and 
 on the atmospheric pressure, so that when the barometer indicates, 
 say, 28 inches, the pump lift will be less than when the barometer 
 indicates, say, 30 inches, the difference of i lb. accounting for nearly 
 2 feet of difference in lift. Strictly speaking, no such force as suction 
 exists, only difference in pressure, but the word suction is still in use 
 with reference to valves, &c. 
 
 At a higher level than the sea the atmospheric pressure is less, 
 therefore a pump will have less lift in due proportion. It should also 
 be remembered that the vacuum will show less when the atmospheric 
 pressure is lessened, as the pressure on the outside of the U tube 
 tending to bend it is reduced with the same pressure inside the tube ; 
 this will naturally give the tube less curvature. 
 
 Vertical Suction Lift of Pumps at Different Atmospheric 
 
 
 Pressures. 
 
 
 
 Barometer 
 
 
 
 Practical Vertical 
 
 Reading. 
 
 
 
 Lift (approx.). 
 
 29-4 inches 
 
 - 
 
 -^ 
 
 25 feet. 
 
 28 
 
 - 
 
 
 24 „ 
 
 266 „ 
 
 - 
 
 - 
 
 23 „ 
 
 22-8 „ 
 
 - 
 
 - 
 
 19 ,, 
 
 19-7 » 
 
 - 
 
 - 
 
 17 „ 
 
 Material or Shafting. — Shafting is now generally constructed of 
 ingot steel, that is, large masses of steel known as ingots, which after 
 casting are afterwards turned down by machine to the required 
 diameter, the ingots being originally much in excess of the size 
 wanted to ensure soundness of material. Good scrap iron forged 
 is also employed for shafting, propeller lengths particularly, many 
 builders preferring this to steel, owing to its less corrosive action in 
 sea water. 
 
 Stresses on Shafting. — All lengths of shafting are subjected to a 
 torsional stress due to the twisting moment set up by the cranks ; 
 in addition to this the crank shafting has to withstand a bending stress, 
 produced by the bending moment of half the piston load multiplied 
 by the distance from centre of crank-pin to centre of main bearing. 
 
 The propeller shaft is also subjected to a bending stress, set up 
 by the bending moment of the propeller weight multiplied by the 
 distance from centre of boss to stern post. To allow for these excess 
 stresses it is necessary to increase the diameter of these shafts over 
 that of the tunnel lengths. 
 
 The general stresses on shafting may therefore be classed as 
 follows : — 
 
^S,S ' "Verbal" Notes and Sketches 
 
 r* 1 <^u ri.- r Torsional. 
 
 Crank Shafting - JBending. 
 
 {Torsional. 
 End compression (ahead). 
 End tensile (astern). 
 
 'Torsional. 
 Bending. 
 
 End compression (ahead). 
 End tensile (astern). 
 
 Propeller Shafting 
 
 It will be obvious that if the propeller rises out of the water 
 during racing the bending moment and stress will be much 
 increased. 
 
 To Line up Crank Shaft. 
 
 1. Disconnect bottom ends and hang up connecting rods and 
 eccentric rods. 
 
 2. Take out keeps and top half bearings. 
 
 3. Jack up the shaft until coupling faces all fair, or test with 
 bridge gauge for level. 
 
 4. Take out bottom half bearings, refill with W.M. and bore out 
 true. 
 
 5. Replace bearings, lower shaft into place, and test again before 
 finally connecting up the engine. 
 
 NOTE.— If the wear- down is slight and the engine not of large power, liners 
 may be fitted in below the bottom half bearings instead of rebushing the same. 
 
 Pistons. — For highest efficiency the piston rings require to join 
 steam-tight joints at three places. 
 
 1. Between rings and cylinder walls. 
 
 2. Between rings (top edge) and junk ring. J 
 
 3. Between rings (bottom edge) and piston flange. 
 
 At the same time the rings require to be a floating fit, otherwise 
 the springs or compression of the rings would be ineffective in pre- 
 venting steam leakage from one side of the piston to the other. 
 
 All patent types of piston rings aim at forming the threefold joint 
 referred to, which, however, is not easily attained in practice. The 
 Buckley, Lancaster, and other rings fitted with coiled springs are 
 designed so that the spring pressure exerts a force outwardly and at 
 the same time presses the two half rings away from each other, thus 
 forming a steam-tight joint between the upper ring and the junk ring, 
 and between the lower ring and the piston flange, the idea being to 
 prevent steam leakage to the back of the rings, which, if taking place, 
 results in excessive friction and wear of the rings and cylinder barrel. 
 This will perhaps be understood when it is stated that a pressure of 
 
General Notes and Descriptions 389 
 
 about 4 lbs. per square inch on the rings is sufficient to prevent piston 
 leakage in ordinary cases. 
 
 On the down stroke the friction between the rings and cylinder 
 barrel will naturally produce contact between the upper edge of the 
 top ring and the junk ring and so form a steam-tight joint, but for the 
 same reason the lower ring is apt to come away from the piston flange 
 unless held firmly in position by the piston springs, if not, the exhaust 
 pressure (about 60 lbs. in the case of H.P. cylinders) will be admitted 
 to the back of the rings and results in the serious frictional effects 
 referred to. On the up stroke the positions of the rings are reversed, 
 the lower edge of the bottom ring bearing hard against the piston 
 flange and so preventing the admission of steam to the back of the 
 rings, but the upper ring will now be loose, unless kept in place by 
 the springs, and will allow the admission of exhaust pressure steam 
 to the back of the rings. 
 
 No. 75. — Lancaster Piston Ring and Spring. 
 
 The rings are made from a special mixture of cast iron, 
 containing principally cold blast iron and hematite, giving a 
 tensile strength of 20 tons per square inch, making them ex- 
 ceedingly strong, close-grained, hard, and capable of taking a 
 high polish. 
 
 To alter the length and tension of the spring (if necessary) 
 the ends are screwed into each other, and by varying the 
 distance which one end screws into the other, the diameter of 
 the spring can be altered so as to put more or less pressure on 
 the rings, thus furnishing compensation for increased steam 
 pressure or wear. The spring has ample bearing inside the 
 rings so that it cannot wear away. 
 
 In the case of patent feed pumps the water pistons require even 
 more careful adjustment, as if leakage to the back of the rings occurs 
 the water pressure is much in excess of the steam piston leakage 
 pressure. The side of the water piston where the rings would be 
 loose may have a pressure of 220 lbs. or more in the case of boiler 
 feeding, and if leakage occurred would result in enormous friction 
 between the rings and pump barrel. 
 
 Beams. 
 
 Many examples of beam construction occur in marine engineering 
 practice, such as, for example, in main-bearing keeps, escape-valve 
 bridges, pump levers, crank webs, tail-end shafts, &c., and a few 
 
390 
 
 "Verbal" Notes and Sketches 
 
 simple examples of the general principles involved should be found of 
 service. 
 
 Neutral Axis.— A beam or lever fixed at one end (cantilever) and 
 loaded at the other end (Sketch No. i) is subjected to a tensile stress 
 
 NEUTRAL _ _AXJS_ 
 
 No. 76. — Neutral Axis of a Beam. 
 
 at the upper edge and a compressive stress at the lower edge (Sketch 
 No. 2) ; but at the neutral axis, situated midway between the two, 
 there is neither tension nor compression stress. 
 
 This will perhaps be understood when it is noticed that the upper 
 edge is lengthened (Sketch No. 2) by the effect of the load producing 
 
 TENSILE 
 
 - _ UNALTERED 
 COMPRESSIVE SfR£ 
 
 SS 
 
 No. 77.— Stresses on Loaded Beam. 
 
 a bending tendency, and the lower edge proportionally shortened, but 
 at the neutral axis the length remains unchanged, and the beam is 
 therefore subject to neither tension nor compression at this position. 
 From the neutral axis upwards the tensile stress increases from o to a 
 maximum, and from tlie neutral axis downwards the compressive 
 stress increases from o to a maximum, and allowing for a mean 
 position of stress and for the beam cross-sectional area, the constant 
 number 6 is obtained, which is employed in the equation connecting 
 the bending moment, load, and stress per square inch. 
 
 C 
 
 w 
 
 L - 
 
 No. 78. 
 
 ^T^, 
 
|| General Notes and Descriptions 
 
 No. I (Sketch No. 78). 
 
 Rule.— 
 
 Therefore, 
 
 6xWxL = D''^xTx Stress. 
 Bending Moment = L x W. 
 
 6xWxL 
 
 D2 
 
 — -Stress, or ^ /Xs — Zr — - = D 
 xT V Tx Stress ^' 
 
 L = 
 T= 
 
 D- X T X Stress 
 6xL 
 
 D^ X T X Stress 
 6xW ' 
 
 6 xWxL 
 D- X Stress" 
 
 391 
 
 NOTE.— The strength of a beam varies directly as the Depth^ and Thickness 
 
 and inversely as the Leng^, or as 
 
 D2xT 
 
 No. 2 (Sketch No. 79). 
 Rule. — 
 
 6xWxL = D-xTx Stress x 2. 
 
 Therefore, 
 
 S- 
 
 Bending Moment = 
 
 6 xWxL 
 b^xTxa' 
 
 LxW 
 
 
 
 
 • * 
 P 
 
 < - - - 
 
 L > 
 
 
 
 No. 79. 
 
 
 
 
 NOTE.— If Length is in feet and Weight in pounds, then B.M. (Bending 
 Moment) is expressed in Foot-Pounds. 
 
 W 
 
 - - -- L 
 
 P 
 
 kT->| 
 
 No. 80. 
 
392 
 
 "Verbal" Notes and Sketches 
 
 No. 3 (Sketch No. 80). 
 Rule. — 
 
 Therefore, 
 
 6xWxL=D2xTx Stress x 4. 
 6xWxL 
 
 Stress = 
 Bending Moment = 
 
 D^ X T X 4' 
 LxW 
 
 NOTE.— If Length is in feet and Weight in tons, then B.M. is expressed in 
 Foot-Tons. 
 
 -,W 
 
 (YfTxrrrrr) 
 
 No. 81. 
 
 No. 4 (Sketch No. 81). 
 
 Rule. — 
 
 Therefore, 
 
 6xWxL=D-xTx Stress x 8. 
 6xWxL 
 
 Stress = 
 
 Bending Moment (B.M.) = 
 
 D^xTxS' 
 LxW 
 
 kT-> 
 
 w 
 
 No. 5 (Sketch No. 82). 
 Rule. — 
 
 No. 82. 
 
 )*-T-*i 
 
 Therefore, 
 
 6xWxL=D2xTx Stress x 8. (Same as last example. ) 
 
 Stress=$^^^L 
 D2 X T X 8 
 
 D=v^ 
 
 B.M.= 
 
 6xWxL 
 T X Stress x 8 
 
 LxW 
 8 * 
 
General Notes and Descriptions 
 
 393 
 
 No. 83. 
 
 No. 6 (Sketch No. 83). 
 Rule. — 
 
 Therefore, 
 
 6xWxL=D2xTx Stress x 12. 
 6xWxL 
 
 Stress = 
 
 T= 
 
 D2 X T X 12' 
 
 6xWxL 
 T X Stress x 12' 
 
 ■sf-. 
 
 6xWxL 
 
 B.M.= 
 
 T X Stress x 12 
 
 LxW 
 12 
 
 Example No. i, — Find the bending stress per square inch on a 
 beam fixed at one end and loaded at the other end by a weight of 5 
 tons. The beam is 6 feet long, 10 inches deep, and 3 inches thick. 
 
 Then, 6 x 72 inches x 5 x 2240 = 10^ x 3 x Stress. 
 
 Therefore, Stress = ^ 7^ ^5 ^ 2240 _ ^5^3. 5 j^jg pg^ square inch. 
 10^ X 3 '^ ^ 
 
 Example No. 2. — Calculate the required depth of lever for a lever 
 safety valve. Length from valve to weight 25 inches, weight 20 lbs., 
 thickness of lever \ inch, and the stress on lever metal 3000 lbs. per 
 square inch. 
 
 Then, 6 x 25 inches x 20 = D- x -5 inch x 3000. 
 
 Therefore, 
 
 Depth 
 
 V 
 
 6 X 25 X 20 
 
 •5 X 3000 
 
 = i'4 inches (say i^ inches). 
 
 Example No. 3. — Piston 24 inches diameter, pressure 120 lbs. 
 per square inch, distance between centres of connecting rod bottom 
 end bolts 18 inches. Find the required thickness of the cap if the 
 width is 9 inches and the stress not to exceed 6000 lbs. per square 
 inch. 
 
 NOTE.— Assume the construction to be as that of a beam supported at both 
 ends and loaded throughout. (Sketch No. 81.) 
 
 Load = 24- X .7854 X 120 = 54360 lbs. 
 
 Then, 6 x 54360 x 18 inches = D- x 9 inches x 8 x 6000. 
 
 _ ^ /6 X 54360 x 18 . , , o • 1. . 
 
 Therefore, D-y^ 9x8x6000 "^7 mches (say 3I inches). 
 
394 "Verbal" Notes and Sketches 
 
 Example No. 4. — A condenser door weighs 1000 lbs., and when 
 taken off is hung on a bar li inches thick and 18 inches in length. 
 Find the required depth of the bar if the stress on the metal is not to 
 exceed 4000 lbs. per square inch. 
 
 NOTE.— This case is similar to Sketch No. 78. 
 
 Then, 6 x 18 inches x 1000= D- x i-s inches x 4000. 
 
 ^L r T^ /6 X 18 X 1000 . , , , . , « 
 
 Therefore, ^~\J — i x4ooo ~ ~^'^ inches (say 4^ inches). 
 
 Example No. 5, — Find the required depth of the bridge bar of a 
 feed-pump spring-loaded relief valve if the distance between the pillar 
 studs is 5 inches and the width of bridge 3 inches, valve 2\ inches 
 diameter, and loaded to 50 lbs. per square inch ; stress yyx> lbs. 
 
 NOTE.— This case may be assumed as being similar to Sketch No. 82. 
 
 Load = 2-5- x .7854 X 170 = 833 lbs. 
 Then, 6x5 inches x 833 = D^ x 3 inches x 8 x 2250. 
 
 / 6 X n X 8*?^ 
 iherefore, °^\/ 3x8x225 0='^^ ^""^^ ^^^^ ^* ^"*^*^^- 
 
 Consumption and Speed. 
 
 At ordinary speeds the consumption or I.H.P. varies as the cube 
 of the speed. 
 
 Example. — The consumption per day is 14 tons and the speed 
 II knots ; find the consumption if the speed is increased to 12 knots. 
 
 As 11^ : \2? : : 14 = 1817 tons per day. 
 
 From this it will be seen that to increase the speed by i knot per 
 hour the consumption increases 4-17 tons per day. 
 
 ' Example. — A twin screw steamer develops 2000 I.H.P. in each 
 set of engines, or 4000 I.H.P. in all, and runs at a speed of 14 knots ; 
 find the speed when running with one set of engines only, and 
 developing 2000 I.H.P. 
 
 As V4OOO : 2000 : : 14^ : : II knots, 
 
 so that with 4000 I.H.P. the speed will be 14 knots, and with 
 2,000 I.H.P. 1 1 knots. 
 
 NOTE. — The cube root requires to be extracted. 
 
 Speed and Slip. 
 
 The engine speed in knots per hour is worked out as follows : — 
 
 Px Rx6o . J 1. 
 
 — ^— = engine speed per hour. 
 
 P = propeller pitch. 60= minutes per hour. 
 
 R= revolutions per minute. 6080 = feet per knot, 
 
General Notes and Descriptions 395 
 
 If the ship's speed per hour be subtracted from the engine speed, 
 the difference is the apparent sHp. To express the slip as a per- 
 centage proceed as follows : — 
 
 As Engine knots : Slip knots : : 100 per cent. = per cent, of slip 
 (apparent). 
 
 Example. — The pitch is 20 feet, the revolutions per minute 70, 
 and the speed of the ship 12 knots ; find the per cent, of slip. 
 
 20x70x60 _ » 
 
 6080 -^ ■ 
 
 And, 13-81- 12= i-8i knots slip. 
 
 Then, as 13-81 : i-8i :: 100 :: 13-1 per cent, of slip. 
 
 To find the percentage of slip if the distance run by the ship per 
 day is known, and the revolutions for the same time as indicated by 
 the counter. 
 
 Example. — The distance gone by the ship in twenty-four hours 
 is 360 knots, and the counter indicates 135 112 revolutions for the 
 same period ; find the per cent, of slip if the propeller pitch is 18 feet. 
 
 I35II2 X 18 1 i. w 
 
 ''•' , = 400 knots by engine. 
 
 0080 
 
 400-360=40 knots slip. 
 Then, as 400 : 40 : : loo : : 10 per cent. slip. 
 
 Indicated Horse-Power and Consumption. 
 
 After finding the mean pressure from a pair of diagrams, the I.H.P. 
 is obtained as follows : — 
 
 D' X .7854 xSxzxRxM.P. _T Tj p 
 33000 
 
 D = diameter of piston in inches. R = revolutions per minute. 
 
 S = stroke in feet. 2 = two strokes per revolution. 
 
 M.P. =mean pressure. 33000 = foot-lbs. per I.H.P. per minute. 
 
 The I.H.P. of each cylinder must be worked out separately, and 
 the results added together to obtain the total I.H.P. of the engine. 
 
 To find the consumption of coal per I.H.P. per hour divide the 
 coal used per day in lbs. by the I.H.P. and twenty-four hours. 
 
 Example. — The total I.H.P. of the three cylinders amounts to 
 1,100, and the consumption per day is 18 tons; find the pounds of 
 coal burnt per I.H.P. per hour. 
 
 18x2240^^ lbs. of coal per I.H.P. per hour, 
 Iioo x 24 
 
# 
 
 396 " Verbal " Notes and Sketches 
 
 Example. — The H.P. cylinder of a compound engine develops 
 420 I.H.P., and the L.P. 460 I. H.P. ; if the consumption is 20 tons 
 per day, find the coal used per I. H.P. per hour. 
 
 420 + 460=880 total I. H.P. 
 Then, 20x2240^^^^ j^^ ^^ ^^^^j i.h.P. per hour. 
 
 880 X 24 
 
 The cylinders of a triple expansion engine are 24, 40, and 65 inches 
 in diameter, stroke 3 feet 6 inches, and revolutions 70 per minute. 
 The mean pressures obtained from the indicator cards are — H.P. 
 556 lbs., M.P. 24-8 lbs,, and L.P. 8-9 lbs. The consumption per day 
 is 22-5 tons. 
 
 Find (i) the I.H.P. of each engine ; (2) the total I.H.P. developed; 
 and (3) the consumption per I.H.P. per hour. 
 
 24^ X 7854 X3-5X 2x70x55-6^ 84-1 I.H.P. in H.P. cylinder. 
 33000 
 
 40' X -TSgixj-S X 2 X 70 X 24-8^ I HP j„ ^p cylinder. 
 
 33000 ^'^ ^ ' 
 
 IS'^x -7854 X3-5X2X 70x8-9^ g^ I H.r in L.P. cylinder. 
 33000 
 
 Then, 384'i + 475-9 + 45i =^1,311 total LH.P. developed. 
 
 Tons. 
 ^°*^' 22-5 X 2240 ^^.^ j^jg qJ. j,^j^j I.H.P. per hour. 
 
 1311x24 
 
 NOTE. — For average cases the consumption should be somewhere betv?een 
 I '3 and 1-6 lbs. per hour per LH.P. 
 
 Coal Consumption, I.H.P., Speed, and Distance Run. 
 
 In comparing coal consumption, speed, and distance run, it should 
 be remembered that within moderate speeds the coal consumption 
 (or I.H.P.) varies as the speed- x distance, which means that the coal 
 burnt per knot varies as the speedy This amounts to the same 
 thing as stating that the consumption varies as the cube of the speed. 
 Therefore we have the following laws which apply to moderate speeds 
 for any given steamer : — 
 
 1. The consumption (coal or water) (or I.H.P.) varies as the 
 speed^. 
 
 2. The consumption per knot varies as the speed^. 
 
 3. The consumption over a voyage varies as the speed^ x distance. 
 
 NOTE.— Above a certain speed limit the LH.P. may vary as the 4th, 5th, or 
 6th power of the speed. From the foregoing it will be seen that if a steamer 
 runs short of coal, port may be reached if the speed is reduced, for although the 
 time taken is much longer, this is more than balanced by the reduced daily con- 
 sumption which, under the reduced speed conditions, may be found sufficient to last 
 the voyage. 
 
General Notes and Descriptions 397 
 
 Examples. — 
 
 (i.) The consumption per day is 14 tons and the speed 11 knots; 
 find the consumption if the speed is increased to 12 knots. 
 
 As 11' : 12^ : : 14-18-17 tons per day. 
 
 From this it will be seen that to increase the speed by i knot per 
 hour the consumption increases 4-17 tons per day. 
 
 (2.) A twin screw steamer develops 2000 I.H.P. in each set of 
 engines, or 4000 I.H.P. in all, and runs at a speed of 14 knots ; find 
 the speed when running with one set of engines only, and developing 
 ' 2000 I.H.P. 
 
 As V40OO : 2000 : : 14-' : : II knots, 
 
 so that with 4000 I.H.P. the speed will be 14 knots, and with 2000 
 I.H.P. II knots. 
 
 (3.) The speed is 14 knots and the coal consumption 40 tons per 
 day ; find the reduced consumption if the H.P. is linked in to give a 
 speed of only 12 knots. 
 
 Tons 
 As 14^ : 12^ : : 40 = 25-2 tons (nearly). 
 
 Therefore the consumption falls from 40 tons to 25-2 tons, a 
 difference of 14-8 tons per day. 
 
 (4.) A steamer after having run 1000 nautical miles at a speed of 
 10 knots and consumed 72 tons of coal, has yet to run 1200 miles, 
 but the coal has run short, as the bunkers only contain 65 tons ; find 
 the economical speed required so that port may be made. 
 
 Then, 65X looox io-=72x 1200X K-. 
 
 Therefore, 65x^000 x 10^^ K^=^S^^Z, 
 
 72x1200 
 
 iand, \/7S-23=8-7 knots (nearly). 
 
 Therefore by reducing the speed from 10 knots to ^-y knots 
 (say 8| knots), the coal will last the voyage, although a longer time 
 is taken to complete the distance. 
 
 (5.) Distance run, 2880 miles; speed, 12 knots; coal consumed, 
 300 tons ; time taken, ten days ; find the required speed to make port, 
 and the time taken, distance yet to go 1500 miles, and coal supply 
 only 100 tons. 
 
 Then 100 x 2880 x 12^^=300 x isooxK^ 
 
 Therefore. loox 2880X i2^^k'^92-i6. 
 
 300 X 1500 
 
 and, \/92i6=9-6 Knots. 
 
 Time taken = 1500 -r 9-6x24 = 6-5 Days. 
 
 28 
 
398 " Verbal " Notes and Sketches 
 
 Therefore the coal will last 6-5 days at a reduced speed of 96 knots, the 
 steamer covering a distance of 1500 miles, as 1500-^9-6 x 24 = 65 days, but 
 would only last 333 days at 12 knots, and cover a distance of only 959 miles, 
 as 3-33 X 12 X 24 = 959. 
 
 The proof can be shown as follows : — 
 
 300 Tons -r 10 Days = 30 Tons per day at 12 Knots. 
 Then, As 12* : 9-63 : : 30 : 15-36 Tons at 96 Knots, 
 
 so that 30x333 = 99-9 Tons, 
 
 and, 15-36 x6-S =998 Tons. 
 
 H.P. Cut-off and Consumption. 
 
 The consumption (either coal or steam), and therefore the Horse-Power 
 developed, vary as the cube of the speed (at moderate speeds). As the H.P. 
 valve cut-off is the approximate measure or rate of the steam consumption, 
 and therefore the coal consumption, then the variation in cut-off required 
 for a given speed may be approximated as follows : — 
 
 Example.— Speed, 12 knots, with H.P. cut-off at -6; find the H.P. cut- 
 off required to reduce the speed to 1 1 knots. 
 Then, As iz* : 11^ : : -6 : -46 cut-off. Answer. 
 
 Therefore the H.P. link must be run in to cut-off at -46 (or 46 per cent.) 
 to reduce the speed from 1 2 knots to 1 1 knots. 
 
 NOTE. — In actual practice the consumption is found to vary more often as the 
 4th power of the speed in place of the cube of the speed. 
 
 Efficiency. 
 
 The general average efficiency of the boilers, engines, working parts, 
 and propellers are as follows : — 
 
 No. I. — Boiler Efficiency = — or -66, or 66 per cent. 
 
 NOTE.— I lb. g'ood coal contains about 14500 heat units, and to change i lb. 
 water into steam, if the steam temperature is 212°, and the feed water temperature 
 212* (see p. 622), requires 966 heat units. 
 
 Therefore, Theoretical evaporation -14500 ^966 = 15 lbs. water. 
 In practice, however, i lb. evaporates only 9 or 10 lbs. water. 
 
 Therefore, Boiler efficiency^ — . 
 
 No. 2. — Steam Efficiency. — The heat efficiency of the steam acting on 
 the piston to develop horse-power varies from 10 to 15 per cent, in actual 
 practice. 
 
 NOTE.— Maximum Theoretical Efficiency of an engine==i — ^-j. 
 
 Where, T° = Steam temperature. 
 
 ^' = Exhaust ,, 
 461° = Absolute temperature Constant. 
 Example. — The initial pressure is 180 lbs., and temperature 380° 
 Fahr., the exhaust temperature is 200° Fahr. ; express the maximum 
 heat efficiency of the engine. 
 
 Then, Efficiency = 3.5?JL?°?=. 21, or 21 per cent. 
 
 380 + 461 
 
 In practice only about 56 per cent, of this efficiency can be obtained. 
 Therefore, Actual efficiency = ^^ •'5~ = ii7 per cent, efficiency. 
 
General Notes and Descriptions 399 
 
 Combined Boiler and Engine Efficiency.— Suppose that r6 lbs. of 
 coal are burnt per I.H.P. per hour. 
 
 Then, Combined efEciency= ^ 33000 — ^ = .ii6, or ii-6 per cent. 
 
 1-6x14500x778 
 
 NOTE I.— Heat Value per lb. coaUiASOO B.T.U. 
 
 ,, 2.— Mechanical Value of each B.T.U. ==778 foot-lbs. of work. 
 ,, 3. — 60 minutes per hour. 
 This result, it should be noted, corresponds with the last. 
 Mechanical Efficiency. — The power lost in driving the air pump, feed 
 and bilge pumps, together with that required to overcome the friction and 
 weight of the moving parts, amounts to about 10 or 12 per cent, of the total 
 power. 
 Therefore, Mechanical efficiency = 100 - 10 = 90 per cent. 
 
 Combined efficiency of Boilers, Engines, Shafting, &c. = ^^ '^= I0'44 per cent. 
 
 100 
 
 Propeller Efficiency. — The actual power utilised in driving the ship 
 
 through the water is only about 60 or 65 per cent, of that delivered to the 
 
 propeller, as blade friction, slip, useless effort of rotation, «S:c., waste the 
 
 remainder of the power. 
 
 Therefore, Propulsive efficiency --60, or 60 per cent. 
 
 Combined Efficiency of Boilers, Engines, Shafting, and 
 Propeller. 
 
 Total efficiency = ^°'^ ^ °° = 6-264 per cent. 
 100 
 
 Therefore, of 100 per cent, coal, or power supplied at the boiler end of the 
 
 plant, only 6-26 per cent, of this is utilised by the propeller to drive the 
 
 steamer, or the combined total loss is equal to 100 - 6-26 = 93-74 per cent. 
 
 Efficiency of High-Pressure Steam and Low-Pressure Steam 
 Compared. 
 
 Heat Efficiency = -= — ^- (see p. 398). 
 T -1-461 
 
 Where, T° = temperature of steam. 
 
 ,, t°= ,, ,, exhaust. 
 
 ,, 461 = absolute temperature constant. 
 
 Take steam of, say, 80 lbs. gauge pressure, or 95 lbs. absolute ; also 
 steam of, say, 180 lbs. gauge pressure-, or 195 lbs. absolute, with exhaust 
 steam temperature of 160° in each case. 
 Then, 95 lbs. -324° Fahr. (from table). 
 
 And, 19s „ =380' „ ( „ „ ). 
 
 Exhaust temperature = 160°. 
 Low Pressure — 
 
 High Pressure- 
 
 Efficiency = ^ — ^|^=«200 (nearly). 
 324 -t- 461 
 
 Efficiency=J^;:-l$l=26i. 
 380 -f 461 
 
 Per cent, economy = ^'^^ ~ '^°^^ x too ^ 24-8 per cent. 
 •209 
 
 So that the theoretical economy of the higher pressure is 24'8 per cent. 
 
 over that of the lower pressure. In actual practice the gain is about 15 
 
 per cent, (see p. 384). 
 
400 
 
 "Verbal" Notes and Sketches 
 
 Squared Paper Diagrams or Curves. 
 
 By means of paper ruled off into squares (which can be easily 
 made by ruling off a series of vertical and horizontal lines, say | inch 
 apart), useful diagrams known as " speed power " curves can be con- 
 structed which will be found of immense service to the chief engineer 
 of a steamer. The writer is quite aware that the majority of marine 
 engineers do not trouble themselves much with so-called "theoretical" 
 diagrams, but he would direct the special attention of readers to the 
 use of the curves here referred to, which are of a strictly practical 
 nature, and if once grasped will be found both interesting and 
 instructive. The curves can be applied as a comparison or check on 
 speed, consumption slip, horse-power, revolutions, &c., and a few 
 examples are given by way of application. 
 
 Speed and Consumption Curve. 
 
 Example i. — From observation, notes are made of the con- 
 sumption of coal at various ship speeds, which are as follows : — 
 
 At 2-5 knots the consumption was 6 tons. 
 
 4 
 
 6-2 
 
 7 
 
 lO 
 
 15 
 20 
 
 10 „ „ „ 34 „ 
 
 From the above plot out a curve of " speed and consumption." 
 
 TOWS 
 40 
 
 35 
 30 
 20 
 15 
 10 
 
 < 
 o 
 o 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 .1- 
 
 
 
 ^' 
 
 '" 
 
 ... 
 
 ... 
 
 ... 
 
 .._. 
 
 7 
 
 { 
 
 
 
 
 
 
 
 
 
 d 
 
 / 
 
 
 
 
 
 
 
 
 
 
 A 
 
 
 
 
 
 
 
 
 
 ^ 
 
 A 
 
 
 
 
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 1 :_:: 
 
 ■^ 
 
 ^-^ 
 
 ^ 
 
 1 
 
 *v 
 
 
 
 
 
 &-'' 
 
 ,,- 
 
 , J- 
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 1 
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 1 1 1 1 
 
 III! 
 
 ij i i 
 
 ' ' ' ! 
 
 I'll 
 ' ' 1 1 
 
 I ! i ' 
 
 1 
 
 
 I 2 34 5~67 8 
 SCALE OF SPEED IN KNOTS. 
 
 No. 84.— Speed and Consumption Curve. 
 
 10 II 
 
General Notes and Descriptions 401 
 
 Method. — Draw out on a sheet of paper a number of, say, i-inch 
 squares, and let each horizontal space represent i knot, and each 
 vertical space or division 5 tons. Where required each horizontal 
 division can be divided into five smaller divisions, each representing 
 j-jj or -2 of a knot, and each vertical division into five smaller divisions, 
 each representing i ton. Number the spaces as shown, up to, say, 
 1 1 knots and 40 tons. 
 
 Now, at the first noted speed of 2-5 knots erect a vertical line, and 
 draw out a horizontal line from the corresponding consumption of 
 6 tons to meet it ; at the intersection describe a small circle or large 
 dot. At the next observed speed of 4 knots draw out a horizontal 
 line from the corresponding consumption of 7 tons, and again describe 
 a small ring at the intersection. Repeat this successively for each 
 noted speed and consumption, describing small circles at each point 
 of intersection as shown. Notice that at the speed of 6-2 knots the 
 vertical line is run up at the first subdivision between the spaces of 
 
 6 and 7 knots, this representing 6-2 knots ; also that at 78 knots the 
 vertical line is run up at the fourth small division between spaces 
 
 7 and 8, this being equal to 78 knots, and so on for each decimal of a 
 knot. Last of all, draw either by hand or wooden curves a line 
 running through all the small rings so found, and the result will be a 
 speed consumption curve which shows at a glance the relation 
 existing between speed and coal consumed at various speeds. 
 
 NOTE. — The value of the spaces may be changed to any convenient measure 
 without in any way affecting the result. That is, each vertical space may be 
 made to represent 2 tons in place of 5 tons, or each horizontal space made to 
 I epresent half a knot, or if found more suitable 2 knots, in place of i knot. 
 
 Sconomical Speed. 
 
 By this is meant the speed which will give the greatest distance 
 run for a given coal bunker supply, or in other words the greatest 
 distance which can be run per ton of coal burnt. 
 
 This can be closely approximated on the diagram by simply 
 drawing a tangential line from the left-hand bottom corner to the 
 curve as shown, and the point of contact gives the speed and con- 
 sumption for greatest economy of steaming. If, then, on a voyage 
 the coal supply runs short, this speed would be the best to adopt 
 under the circumstances (see page 400) to make the coal last out 
 the voyage. The economical speed is at position B, which corre- 
 sponds to about 5-5 knots, 
 
 il I.H.P. and Speed Curve. 
 
 Example 2. — This curve is constructed in a similar manner to 
 the last, and is of very nearly the same value, as generally speaking 
 the consumption and power are practically equivalent terms, and 
 vary in the same relative proportion to the speed. 
 
402 
 
 "Verbal" Notes and Sketches 
 
 Method. — Set off horizontal spaces of h or I inch as found 
 most suitable, representing knots and vertical spaces of similar size, 
 each representing, say, lOO I.H.P. Therefore if each space be divided 
 into five smaller divisions each will be equal to 20 I.H.P. 
 
 Suppose that the following observations were made of I.H.P. at 
 different speeds during progressive trials : — 
 
 At 
 
 2 knots the I.H.P. was 
 
 40 
 
 At 8 kn 
 
 ots the I.H.P. 
 
 was 
 
 360 
 
 3 
 
 60 
 
 » 9 
 
 
 
 520 
 
 4 
 
 80 
 
 „ 9-4 
 
 
 
 600 
 
 4-5 
 
 100 
 
 „ 9-8 
 
 
 
 700 
 
 5 
 
 120 
 
 „ 10 
 
 
 
 760 
 
 6 
 
 180 
 
 „ IO-4 
 
 
 
 900 
 
 7 
 
 260 
 
 „ IO-8 
 
 
 
 1080 
 
 At each speed noted, where required, run up vertical lines, and 
 connect these with horizontal lines run out from the left at the 
 corresponding I.H.P., and at the points of intersection describe little 
 
 if) 
 
 ll\AJ- 
 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 irww 
 
 
 
 
 
 
 
 
 
 
 
 I 
 
 900 
 800 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ■■ 
 
 
 
 
 ■ - - 
 
 - - - 
 
 — 
 
 — 
 
 
 
 - --fi 
 
 (; ; 
 
 cnrx 
 
 
 
 
 
 
 
 
 
 
 
 
 V)r\- 
 
 
 
 
 
 
 
 
 
 ' '1 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 { 
 
 
 
 xno- 
 
 
 
 
 
 
 
 
 
 200 
 
 : .- 
 
 ■ - - - 
 
 
 
 - - ■ - 
 
 -- ■ - - 
 
 
 
 
 
 
 
 
 
 
 :^cr^ 
 
 -^ 
 
 / 
 
 
 
 
 1 ' 
 
 100 
 
 ■ - ' ■ — 
 
 . . . _ 
 
 r r . .-r 
 
 Zz^ 
 
 ^ 
 
 -^^ 
 
 rT 
 
 
 
 
 
 1 1 1 1 
 
 ! ill 
 i 1 i ' 
 
 1 i 1 1 
 
 12 3 4 5 6 7 
 
 SCALE OF SPEED IN KNOTS. 
 
 iO il 
 
 No. 85.— Power and Speed Curve. 
 
General Notes and Descriptions 
 
 403 
 
 circles ; finally, connect these circles by a curve, which is then the 
 "speed and I.H.P." curve required. 
 
 NOTE.— Observe that each vertical space -^ 100 I.H.P., therefore each fifth 
 of each space -20 I.H.P. Also that each horizontal space = 1 knot, therefore the 
 fifth of each division = -2 of a knot. 
 
 SCALE OF 
 SPEED IN KNOTS. 
 
 
 ro 
 
 P 0> OD ro -P Cn 
 
 01 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 c/> 
 
 
 r- _ 
 
 
 
 
 
 
 
 
 
 
 5 20 25 
 
 E OF RE 
 
 '-'■■'.}} 
 
 N 
 
 V 
 
 
 
 
 
 
 
 
 
 \ 
 
 
 
 
 
 
 
 
 
 - - _Jl 
 
 \ 
 
 
 
 
 
 
 < 
 
 
 j: 0. 
 
 :.:::: 
 
 
 ^ 
 
 
 
 4* 
 
 
 
 
 
 -\ 
 
 V 
 
 
 
 
 
 
 
 
 
 \ 
 
 
 
 
 
 
 
 
 
 N 
 
 \ 
 
 
 
 
 3 ^ 
 
 z 
 
 
 
 
 
 
 \ 
 
 ^ 
 
 
 
 • y; 
 
 
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 01 
 
 
 
 
 
 
 
 \ 
 
 
 
 V 
 
 ■".i":: 
 
 — 
 
 
 
 
 
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 at 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 \ 
 
 
 en 
 
 
 
 
 
 
 
 
 
 
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 u 
 
 c: 
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 > 
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 CO 
 
 00 
 
 d 
 
 2; 
 
 Speed and Revolution Speed. 
 
 Example 3. — This curve is useful in showing the relation between 
 the ship speed and engine revolutions. Set off the vertical spaces 
 on the left as knots and the horizontal spaces as revolutions. Then 
 
404 
 
 " Verbal " Notes and Sketches 
 
 at any observed or noted speed and revolutions connect the points 
 and describe small circles as shown ; repeat this for as many speeds 
 and revolutions as may be known or noted, and draw a curve through 
 the points so marked, which gives the speed and revolution curve. 
 
 Speed and Slip Curve. 
 
 Example 4. — This curve shows the relation between speed and 
 slip, which, owing to cavitation, generally shows as increase of slip 
 with increase of speed. 
 
 Method. — Set off as before, horizontal spaces (^ inch or h inch) 
 as knots, and vertical divisions as per cent., each space representing, 
 say, 5 per cent, of slip. Now from the log or other data connect 
 
 
 \ 
 
 - - - 
 
 
 :7-\ 
 
 
 
 \ 
 
 
 
 
 
 \ 
 
 \ 
 
 
 
 
 
 \ 
 
 
 
 
 
 ;\ 
 
 
 
 
 
 
 I 
 
 
 
 
 1 
 
 I 
 
 
 
 
 
 1 
 
 
 
 
 
 'i 
 
 
 
 
 
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 :'m 
 
 
 
 
 
 
 
 
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 ; \\\ i 
 
 , 1 1 1 1 
 ' 11' 1 
 
 
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 1 1 1 1 
 
 0> 
 
 ou 
 
 <n 
 
 
 
 1- 
 
 
 
 
 
 
 r- 
 
 r 
 z 
 
 00 
 
 u> 
 
 ~~ 
 
 
 
 
 Q 
 
 'Z 
 
 
 UJ 
 
 
 m 
 
 Ul 
 
 a. 
 in 
 
 
 «t 
 
 
 
 UJ 
 
 
 ro 
 
 -1 
 < 
 
 
 CNJ 
 
 
 o 
 
 dns do anvDS 
 
General Notes and Descriptions 405 
 
 the corresponding positions of speed and per cent, slip (see page 404), 
 and describe little circles as shown. Suppose the data to be as 
 follows : — 
 
 At 4 knots the slip is 7 per cent. 
 6 „ ,. 8 
 
 7 
 
 
 9 
 
 8 
 
 
 10 
 
 10 , 
 
 
 12-5 
 
 12-6 , 
 
 
 16 
 
 Observe that 12-6 knots is equal to twelve spaces horizontally 
 and three-fifths of a space or -6, the vertical is then run up to join 
 the horizontal line, projected over at the 16 per cent, level. As before 
 explained, draw a line through all the points of intersection, and the 
 result will be the " speed and slip curve." 
 
 Points to be Observed. 
 
 Example i. — As previously explained (page 402) at intermediate 
 speeds the consumption or power varies approximately as the cube 
 of the speed. This can be seen in the "speed consumption curve" 
 which shows the consumption to be 15-5 tons at 8 knots and 34 tons 
 at 10 knots. Beyond this speed the consumption may vary as the 
 4th power in place of the cube, which brings out a still greater 
 consumption ratio, but which nevertheless reduces the consumption 
 per I.H.P. per hour, so that at low speeds the coal per I.H.P. per hour 
 is more than at high speeds. 
 
 Example 2. — This curve is very similar to the last, and in some 
 cases is practically equivalent, but generally it is found that the 
 power varies as the cube or as the 4th power of the speed. 
 
 Example 3. — Roughly speaking the revolutions vary directly as 
 the speed, and this is borne out by the curve shown, where it will be 
 seen that at nearly 6 knots the revolutions are twenty-five per minute, 
 and at 12 knots nearly fifty revolutions per minute. 
 
 Example 4. — An ordinary reciprocating engine propeller de- 
 velops greatest efficiency at low revolution speed, therefore as the 
 revolutions increase the efficiency falls off, and the slip ratio increases ; 
 this is shown by the curve, in which the slip ranges from about 6 per 
 cent, at 6 knots to 16 per cent, at 12-5 knots. 
 
 Combined Curves. 
 
 In modern trial trip practice it is usually found more convenient 
 to combine the various curves previously described instead of having 
 them drawn out separately, as the various results can then be com- 
 pared simultaneously, and a more comprehensive idea obtained of the 
 general efficiency. The following is a combined curve diagram of a 
 
4o6 
 
 " Verbal " Notes and Sketches 
 
 modern high speed passenger steamer, and the I.H.P., Speed, Slip, and 
 Revolution curves are all shown together, thus allowing of a general 
 comparison to be made. 
 
 SCALE OF INDICATED HORSE POWER. 
 
 '^ 
 
 
 o 
 
 
 CX) 
 
 
 00 
 
 'i 
 
 
 1 
 O 
 
 
 o 
 
 
 3 
 
 
 cr 
 
 
 t3 
 
 
 n 
 
 (/> 
 
 i-i. 
 
 O 
 
 n 
 
 > 
 
 c 
 
 1" 
 
 5 
 
 m 
 
 ro 
 
 
 w 
 
 
 
 o 
 
 
 -n 
 
 ^ 
 
 
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 5; 
 
 
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 '-1 
 
 o 
 
 
 H 
 
 03 
 
 ►n 
 
 t/) 
 
 
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 o 
 
 — — ro ro ivi 
 
 00 rv> cr> o .p* oo 
 
 o o o o o o 
 
 O O O O C3 C3 
 
 Ol 
 
 04 
 
 ** 
 
 ^ 
 
 ■Pn 
 
 ro 
 
 <T> 
 
 o 
 
 *» 
 
 03 
 
 o 
 
 O 
 
 o 
 
 o 
 
 O 
 
 o 
 
 O 
 
 o 
 
 C3 
 
 O 
 
 Ol 
 
 CP 
 
 ■* 
 
 ^3 
 
 f^ 
 
 o 
 
 13 
 
 
 a 
 
 
 
 |V» 
 
 ?a 
 
 
 ro 
 
 
 < 
 
 
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 rj 
 
 
 ?s> 
 
 c 
 
 
 rl- 
 
 
 
 
 O 
 
 ro 
 
 SCALE 
 
 SCALE 
 
 OF iREVa fEl!; MiN. 
 
 CO 
 
 OF $LIP PER CENT 
 
 ti 
 
 In the above diagram of ship performance the spaces representing 
 knots are divided up into tenths or fifths where required to allow of 
 
General Notes and Descriptions 
 
 40: 
 
 projecting the necessary points on to the I.H.r., rcvokitions, or sh'p 
 curves. In the same way the I.H.P. divisions are divided up into four 
 parts, each being equal to 100 I.H.T. ; the sh'p spaces are also divided 
 into tenths for decimals of per cent, and the revolution spaces are 
 divided into ten divisions, each being equal to a revolution. Dotted 
 lines are shown to illustrate as clearly as possible how the small rings 
 which form the connecting points of the curves are located. 
 
 The three curves shown on the diagram were developed from the 
 following trial trip data, and it should be noted that the rnean results 
 of a series are taken in each case. 
 
 Data for Curves. 
 
 Mean Speed 
 in Knots. 
 
 Mean I.H.P. 
 
 Mean Slip 
 per Cent. 
 
 Mean Revs, 
 per Minute. 
 
 IO-5 
 
 400 
 
 17-5 
 
 82 
 
 14-8 
 
 1270 
 
 20-6 
 
 120 
 
 172 
 
 2000 
 
 211 
 
 140 
 
 20-2 
 
 3325 
 
 21-2 
 
 165 
 
 21-2 
 
 3790 
 
 21 
 
 172 
 
 21-7 
 
 4393 
 
 21-2 
 
 177 
 
 22-1 
 
 4650 
 
 21-8 
 
 182 
 
 With reference to the curves, the following points should be 
 carefully studied : — 
 
 1. Between 11 knots to 21 knots the I.H.P. varies approximately 
 as the knots cubed, which can be proved as follows : At 1 1 knots the 
 I.H.P. is 500; to find the I.H.P. at 16 knots, 
 
 Then, As 11' : 16^ : : 500=1600 I.H.P. (nearly), 
 
 which is exactly the figure shown on the curve at this speed. After 
 this speed the ratio is still higher. 
 
 2. The revolutions vary almost directly as the speed, for at 10-5 
 knots the revolutions are 82, and at double that speed or 2 1 knots the 
 revolutions are 170. 
 
 3. The propeller slip is high owing to the high engine revolution 
 speed reducing the propeller efficiency, but at 21-2 knots the slip is 
 less than at 19 knots, which is somewhat unusual. From 21-2 knots 
 to the maximum speed of 22-1 knots, the slip increases rapidly, as 
 shown by the upward tendency of the slip curve at this position. 
 
SECTION VI. 
 
 MARINE ENGINEERING CHEMISTRY NOTES. 
 
 It need hardly be pointed out that a slight knowledge of chemistry, 
 or at least of chemical processes, is a necessity for the modern 
 engineer, surrounded as he is by numerous active examples of 
 chemical action and reaction, which have, in many cases, to be 
 resisted or neutralised by means of other chemical actions or 
 reactions. Unfortunately, however, many of the effects referred 
 to, instead of being eliminated altogether, can only be minimised. 
 
 Examples. — The following are a few ordinary examples of 
 chemical action and reaction : — 
 
 Combustion of coal or oil in a furnace. 
 
 Rusting (combustion). 
 
 Explosion of gases (combustion). 
 
 Corrosion in boilers, Feed Heaters, &c. 
 
 Corrosion in tank tops, condenser tubes, tail-end shafts, rudder 
 
 posts, propellers, &c. 
 Scale deposits in boilers. Evaporators, &c. 
 Formation of Marsh Gas in bunkers, oil tanks. 
 Formation of COg gas and Free Nitrogen in ballast tanks, &c. 
 
 From the foregoing it will be admitted that, to cope more or less 
 successfully with the destructive effects produced by the processes 
 referred to, a knowledge of chemistry is really necessary, as by it 
 the engineer may know how to obtain good combustion in the 
 furnaces, how to correct the action of acid or oxygen in boiler water, 
 the best methods of preventing explosion of Marsh Gas in bunkers, 
 methods of protecting the boilers against corrosion and pitting, how 
 to keep down scale deposit in boilers, &c. &c., all of which come 
 under the general heading of chemistry. 
 
 Composition of Coal. 
 
 Average Coal 
 
 Carbon 
 
 80 per cent. 
 
 Hydrogen - 
 
 5 
 
 Oxygen 
 
 8 
 
 Nitrogen 
 
 li „ 
 
 Sulphur 
 
 1* 
 
 Ash. &c. - 
 
 4 
 
 408 
 
 1 00 per cent. 
 
Marine Engineering- Chemistry Notes 409 
 
 Heat Values. 
 
 Carbon = 14500 Heat Units per lb. 
 Hydrogen — 62000 ,, „ 
 
 Sulphur = 42 „ „ 
 
 Heat in i lb. Coal. 
 
 I lb. good coal contains about 14700 Heat Units, made up as 
 follows : — 
 
 -45 '^ — = 11600 Heat Units from Carbon. 
 100 
 
 62000 x5 _ 3100 Heat Units from Hydrogen. 
 100 14700 Heat Units, total. 
 
 NOTE.— The heat of the other elements may be neglected. 
 
 Chemistry of Gases, &c. 
 
 In chemical formulse the various elements are represented by the 
 following symbols : — 
 
 C = Carbon. CI = Chlorine. 
 
 H = Hydrogen. Na = Sodium. 
 
 N = Nitrogen. Fe = Iron. 
 
 O = Oxygen. Ca = Calcium 
 S = Sulphur. 
 
 Small numbers affixed to any of the above symbols indicate the 
 atoms or volumes of that element which go to make up the chemical 
 compound expressed. For example, water is composed of two atoms 
 of hydrogen and one atom of oxygen ; it is therefore expressed 
 chemically as H^O. Again, dry Ammonia is composed of one atom 
 of nitrogen and three atoms of Hydrogen, and is expressed as NH3. 
 The prefix " Mon " means one atom, and " Di " two atoms. 
 
 The following are the most important chemical compounds to be 
 studied and committed to memory : — 
 
 Atmospheric Air. 
 
 Composition. 
 
 By Volume. By Weigh:, 
 Nitrogen- .... 79-04 77 
 
 Oxygen ----- 20-96 23 
 
 Ordinary atmospheric air contains water vapour and a very small 
 percentage of carbonic acid gas — about -04 per cent. It also contains 
 small proportions of Ammonia, Argon, also Aqueous Vapour and 
 Nitric Acid. 
 
 One pound of air at ordinary atmospheric temperatures occupies 
 about 13 cubic feet, and consists of Oxygen 23 parts. Nitrogen yy 
 parts by weight. 
 
4IO "Verbal" Notes and Sketches 
 
 I lb air-/ ^^ys^" '^3 of I lb. 
 
 I ID. air-^jj.^j.^ggj^ ,^^ Qf J jj^ (nearly). 
 
 NOTE. — Atmospheric air also contains a very small proportion of CO. gas — 
 about -04 per cent. 
 
 Air Required per Pound Coal. — (i.) Assuming that each pound of 
 coal requires in forced draught 20 lbs. of air for perfect combustion, 
 
 Then, 20 x 13 = 260 cubic feet of air per pound coal. 
 
 (2.) If natural draught, 24 lbs. are required, 
 
 Then, 24x13=312 cubic feet of air per pound coal. 
 
 Water = H20. 
 
 Carbon Monoxide, or CO = Carbonic Oxide. — This gas is obtained 
 by incomplete combustion, due to an insufficient supply of air 
 or oxygen. CO will change into COo if sufficient oxygen be supplied 
 to it. An example of this is flame sometimes seen at the funnel 
 top. CO burns with a pale bluish flame. The specific gravity of 
 CO = -96. 
 
 Carbon Dioxide, or COo = Carbonic Acid Gas. — This gas is obtained 
 (one way) by perfect combustion in the furnace. It supports neither 
 combustion nor animal life. It is used in the form of ''carbonic 
 anhydride " (that is, " without water ") for refrigerating machines, as 
 when reduced to a liquid under pressure and cold, it quickly evaporates 
 again at a low temperature if the pressure is withdrawn, and expansion 
 allowed to take place. 
 
 It can be prepared in large quantities by the action of Hydrochloric 
 acid on Limestone. 
 
 CO2 (together with Free Nitrogen) is also found in empty ballast 
 tanks and boilers under the name of " foul air," and the COo gas 
 being fully one and a half times heavier than the atmosphere, 
 accumulates at the lowest parts of the tanks, &c. 
 
 It has been recently found by careful experimental tests that " foul 
 air" is made up of fully 85 per cent. Free Nitrogen, and only about 
 15 per cent. CO.,, instead of being, as was at one time supposed, 
 entirely made up of CO., gas. 
 
 The presence of CO.^ and Free Nitrogen can be detected by 
 lowering a lighted taper (or open lamp) into the suspected place, 
 which, if extinguished, denotes these ga.ses present in quantity. The 
 atmosphere contains about 0-4 per cent, of COo, and this is under- 
 stood to be one of the causes of corrosion in boilers, as the air admitted 
 with the feed water contains Oxygen and CO.,, both of which in 
 combination are conducive to corrosion when set free by heat in a moist 
 atmosphere. 
 
 In testing for the presence of " foul air," a light, if lowered into 
 the tank or boiler to be tested, will either burn smoky and black or go 
 
Marine Engineering Chemistry Notes 411 
 
 out altogether, according to the percentage of "foul air" present. If 
 the light is extinguished, CO., is present in dangerous quantity. 
 
 Free Nitrogen. — When oxidation goes on in a ballast tank or boiler, 
 Free Nitrogen is produced by the rapid combination of the Oxygen, 
 which is therefore used up, and leaves behind the Nitrogen gas, 
 Nitrogen liberated in this manner is similar in its effects on life and 
 combustion to CO2, in that it neither supports life nor combustion, 
 and thus constitutes " foul air." 
 
 Light Carburetted Hydrogen, Methane, or CH4 = Marsh Gas.— 
 
 This gas is usually found in coal bunkers, and is generated by the 
 gradual evaporation of the coal and its absorption of oxygen from the 
 air especially if damp. As the gas slowly forms by chemical action, 
 heat is generated, and the temperature rises, it may be, to the ignition 
 point, thus causing what is known as spontaneous combustion. It 
 should be noted that this gas will explode on the introduction of a 
 naked light into the bunker. Small or wet coal is most liable to 
 produce spontaneous combustion. Danger of explosion from a light 
 exists when the proportion of CH^ to air is in the ratio of i to 10; 
 that is, I cubic foot of CH4 to 10 cubic feet of air. Coal shipped 
 direct from the mine contains more CH^ than coal which has lain 
 for some time previous to shipping, as in the latter case most of the 
 Marsh Gas has passed off. Air containing 5 to 6 per cent. CH^ 
 will explode sharply, and when 10 per cent, is present it explodes 
 with greatest violence, complete combustion taking place. When 
 CH^ is suspected in a coal bunker, the only sure way of detecting it 
 is b}^ means of a miner's Davy lamp, its presence being shown by a 
 pale blue "cap" or halo on the top of the flame. When an explosion 
 of CHj takes place in a bunker great caution should be exercised in 
 entering it as the resultant gases (CO and CO.) are highly poisonous. 
 CH^ itself in a pure state is also poisonous. 
 
 Marsh Gas (specific gravity = -55) is lighter than the atmosphere, 
 and therefore occupies the highest parts of bunkers and tanks. 
 Marsh Gas supports neither life nor combustion. 
 
 Petroleum Vapour, or Light Carburetted Hydrogen, is also found 
 in empty oil tanks, and is formed by the evaporation of the layer or 
 skin of oil left adhering to the bottom and sides of tanks after they 
 have been pumped out. Oil gas is of nearly the same composition as 
 coal gas, with the difference that it contains less carbon and more 
 hydrogen. This will be understood when it is stated that average 
 mineral oil as used in furnaces for fuel is made up as follows : — ' 
 Carbon, 84 per cent.; Hydrogen, 14-5 per cent.; and Oxygen, 1-5 
 per cent. Carburetted Hydrogen, if mixed with air, is highly explo- 
 sive ; it is also fatal to life. For this reason oil tank steamers are 
 fitted with special fans for exhausting the foul gases from the tanks 
 after the oil is pumped out. Petroleum vapour from heavy mineral 
 
412 "Verbal" Notes and Sketches 
 
 oils is much heavier than the atmosphere (two and a half times), and 
 occupies the lowest level of a tank. 
 
 .'ammonia = NHg. — This alkali (the opposite of an acid) is peculiar in 
 the fact of its having what is usually the property of an acid, that is, 
 a corrosive action on brass and copper. Ammonia being an alkaline 
 substance, changes red litmus paper to blue ; whereas an acid changes 
 blue litmus paper to red. Litmus paper is the ordinary chemical 
 test for acid or alkali. 
 
 NOTE.— Acids and alkalies combine to form salts, and in combining the one 
 counteracts or destroys the effects of the other. 
 
 Ferric Oxide = Fe203. — This is obtained by the chemical combina- 
 tion of iron and oxygen in a damp atmosphere. When two atoms 
 of iron combine with three of oxygen we obtain five atoms forming 
 Fe^Og. 
 
 Hydrochloric Acid = HCl. — This is composed of hydrogen and 
 chlorine, and is often found in empty boilers. The chlorine is 
 obtained from Magnesium Chloride, a constituent of sea water. 
 
 iSodium Chloride, or Common Salt = NaCl2. 
 
 NOTE. — Na is the chemical symbol for Sodium (Natrium). 
 
 .Calcium Chloride = CaCU. — This compound is used as a brine 
 former in refrigerating machines, where the brine pipe system is 
 used for cooling. This salt is very much more intense in its effect, 
 and is better in every way than common salt. 
 
 In making up the brine with calcium chloride fresh water only 
 should be used, as sea water sets up corrosion in the brine pipes and 
 brine pump. Common salt has the same injurious effect. 
 
 Acids. — An acid is a chemical compound possessing the following 
 characteristic properties : — 
 
 (i.) Is sour to the taste. 
 
 (2.) Changes blue litmus paper to red. 
 
 (3.) Neutralises alkalies, and with them forms chemical salts. 
 
 (4.) Contains hydrogen. 
 
 Alkalies. — An alkali is a chemical compound possessing the following 
 characteristic properties : — 
 
 (i.) Is soapy to the taste, 
 
 (2.) Changes red litmus paper to blue. 
 
 (3,) Absorbs CO.3 gas. 
 
 (4.) Easily combines with acids to neutralise them and form 
 chemical salts (is then known as a " base "). 
 
Marine Engineering Chemistry Notes 413 
 
 Spontaneous Combustion in Coal Bunkers. 
 
 Tliis is likely to occur in bunkers exposed to the effects of fairly 
 hii;"h temi)cratures, such as may exist when the bunkers are placed 
 \cry near the boilers of a steamer. 
 
 By the oxidation of coal the carbon is set free, and combines with 
 the oxygen of the air and forms CO.2 and CO. 
 
 The gas produced by the gradual oxidation of the coal is CH^ or 
 Marsh Gas, and it should be noted that this gas of itself is not 
 explosive, but only when mixed with certain proportions of atmo- 
 spheric air. A lighted taper plunged into a jar of pure Marsh Gas 
 will not produce an explosion, but if the Marsh Gas were mixed with, 
 say, 10 cubic feet of air to i cubic foot of gas, a violent explosion 
 would result. 
 
 If the air supply is reduced to one-half of the above proportion, 
 the resulting mixture will not produce an explosion, or if the air 
 supply is increased to twice the above proportion, the resulting mixture 
 will not be explosive. The most violent explosion occurs when the 
 proportion of air to CH^ is as 10 is to i, a weaker explosion, however, 
 taking place when the proportion is as 8 is to i. 
 
 Marsh Gas can be detected by means of a safety lamp similar to 
 that used by miners, for if the flame of the lamp is turned down low^ 
 a blue " cap " or top will form and burn above the flame, thus indicating 
 the presence of Marsh Gas. 
 
 Marsh Gas can only be got rid of by means of ample ventilation 
 of bunkers or tanks, or, in the case of the latter, by means of special 
 exhausting fans, as employed in oil-carrying steamers. 
 
 NOTE.— The gases obtained after explosion of Marsh Gas (CH4) and air 
 are:— COo, H,0, and N. 
 Or, Carbonic Acid Gas, Steam, and Free Nitrogen. 
 
 Marsh Gas (CHJ. 
 
 The following points regarding the explosive properties of Marsh 
 Gas when mixed with air are of importance : — 
 
 1. Ignition point, 1200° Fahr. 
 
 2. If atmosphere contains 5^ per cent, of Marsh Gas ignition only 
 will take place if a light such as a match, candle, lamp, or fat electric 
 spark is applied. 
 
 3. If atmosphere contains 10 per cent, of Marsh Gas a violent 
 explosion will take place if a light is applied. 
 
 4. If atmosphere contains 18 per cent, of Marsh Gas ignition only 
 ^ill take place if a light is applied ; and if the percentage of 
 Marsh Gas is more than this the combustible nature of the mixture 
 decreases. 
 
 Briefly, if the oxygen (or air) supply is low (5i per cent.) the 
 
 mixture is not favourable to combustion, and if the oxygen (or air) 
 
 supply is high or excessive (20 per cent.), the same holds good ; the 
 
 most suitable mixture for explosion being 10 per cent, of Marsh Gas 
 
 -'9 
 
414 ** Verbal" Notes and Sketches 
 
 in the atmosphere, as with this proportion the chemical combination 
 is most favourable for instantaneous combustion. 
 
 Causes of Spontaneous Combustion. — Fires in coal bunkers or in 
 coal cargoes are due to the rapid absorption of oxygen by the coal, and 
 the most favourable conditions for this occurrence are as follows : — 
 
 1. With freshly worked coal. 
 
 2. With small coal, slack, or dross. 
 
 3. With moist coal. 
 
 4. By heat in surrounding atmosphere. 
 
 The first signs of spontaneous combustion in a coal cargo are a 
 peculiar smell like burning oil, and the appearance of a mist-like vapour 
 in the air currents, also a rise in temperature of the surrounding 
 atmosphere. Inferior coal is more likely to ignite spontaneously 
 than good coal ; and coal of small size than lump or thick coal. 
 With small coal there are more spaces containing air, as for a given 
 cubic mass the weight will be less than for large coal. The oxygen of 
 the contained air is greedily absorbed by the coal under the con- 
 ditions mentioned, and this results in a rise of temperature, as when- 
 ever chemical combination takes place heat is developed. The heat 
 may in time rise to the ignition point of Marsh Gas (CH^), which 
 is 1200° Fahr., and fire will then break out. This firing of coal 
 generally originates in the centre or heart of a pile of coal and well 
 down in the mass, as on the surface the heat generated is carried off 
 by the ventilating atmosphere, and the temperature is thus kept 
 down below ignition point. 
 
 Prevention. — With coal cargoes, as usually stowed loose in the 
 holds, it is practically impossible to adopt really effective preventive 
 measures against the generation of Marsh Gas and danger of spon- 
 taneous combustion, but the following suggestions may be of use — 
 
 1. Liberal ventilation. 
 
 2. In handling coal ashore, the coal is divided up into 
 
 sectional lots, with divisions between, 
 
 3. Great care as regards ventilation is necessary with small 
 
 coal for the reasons given previously. 
 
 4. Coal to be kept as cool as possible. 
 
 Treatment of Fires. — When a coal cargo or bunker takes fire the 
 following methods of dealing with the outbreak may be employed — 
 
 1. For small fires the use of sand thrown on the flame will 
 
 be found sufficient for the purpose. 
 
 2. For more serious outbreaks " digging out " may in some 
 
 cases be successfully resorted to ; that is, the mass of 
 coal which is burning is (if possible, and safe to do so) 
 dug out altogether. 
 
Marine Engineering Chemistry Notes 415 
 
 "Sealing Off." — In other cases of fire it is advisable to close down 
 or "seal off" the hold altogether, so that the fire may be starved of 
 oxygen. This method is only effective, however, if the closing 
 down is really effective, and all ingress of air actually prevented. 
 If leaks of air, however small, take place, the fire will be intensified 
 instead of diminished. 
 
 Water, — Water played on the flame may in some cases be 
 effective if the supply is ample and directed on the coal actually 
 burning, but if otherwise, the water applied may generate "water gas" 
 and only make the state of matters worse. 
 
 CO,,. — This gas may be effectively employed to put out a fire if 
 applied in the initial stages, but if the coal once becomes incandescent 
 the use of CO., as an extinguisher may be totally ineffective. 
 
 Carbon. — In the solid state carbon exists as charcoal, coke, soot, 
 graphite, and the diamond, the latter being carbon in the hard and 
 purest cr}'stalline form. 
 
 Solid carbon may be obtained b}' heating coal without allowing 
 actual combustion to take place ; this expels the volatile gases, and 
 carbon in the form of coke is left as the residue. The average heat 
 ralue is 14500 B.T. units per pound. 
 
 Nitrogen. — This gas does not assist combustion, as it is a quite 
 inert gas, and is termed a " non-supporter " of combustion. It reduces 
 the activity of the oxygen, and thus moderates oxidation and com- 
 bustion. During combustion it passes off unchanged in condition, but 
 raised in temperature. 
 
 Hydrogen. — This gas is the lightest substance known. It exists in 
 water as H,0. It is also combined with Carbon, Nitrogen, and 
 Oxygen in coal, and other substances. All acids contain Hydrogen. 
 
 When Hydrogen burns in air or Oxygen, water is produced, the 
 water consisting of two volumes of Hydrogen and one volume of 
 Oxygen, or H^O. The action takes place in the furnaces, and water 
 vapour or steam is evolved by the liberation of Hydrogen from the 
 coal, and the combination of the same with atmospheric Oxygen. 
 
 Combustion. — Allowing 24 lbs. of air per pound of coal — 
 
 Then, •77x24=18-48 lbs. Nitrogen, 
 
 And, -23x24= 5-52 lbs. Oxygen. 
 
 24-00 lbs. Air. 
 
 From this it will be seen that for each pound of coal 18-48 lbs. of 
 Nitrogen require to be heated up from say 62 degrees to 650 degrees 
 (Funnel Temperature), or 588 degrees. This illustrates the unavoid- 
 able waste of heat due to the heating of the Nitrogen of the air. 
 
4i6 "Verbal" Notes and Sketches 
 
 Coal Gases. — Moist or damp coal in the bunkers generates the 
 following gases by steady absorption of Oxygen — 
 
 j- Light Carburetted Hydrogen -j 
 (I.)] Marsh Gas l = CH4. 
 
 I Methane J 
 
 The gas CH^ (which, it will be observed, has three different names) 
 is colourless, tasteless, and inodorous. It burns with a yellow coloured 
 flame, and can be detected by the use of a safety Davy type lamp, 
 which burns with a " blue cap " at the top of the flame if this gas is 
 present. 
 
 (2.) CO gas, or Carbonic Oxide. 
 
 This gas is also colourless, tasteless, and inodorous. It is poisonous 
 and burns with a bluish coloured flame. The Davy test lamp has 
 the flame surrounded by a mantle of gauze, the cooling effect of which 
 is to reduce the temperature of the flame below the ignition point of 
 Marsh gas. In testing for the presence of explosive gases the lamp 
 requires to be turned down to a mere peep, and if Marsh gas is present 
 the blue cap will then show at the top. CO can only be detected by 
 a flame when 12 per cent, is present, whereas -| per cent, is dangerous 
 to life. The only sure test is by means of a small, warm blooded 
 animal, such as a mouse or canary, which are now used in coal mines 
 when this gas is suspected. 
 
 General Notes. 
 
 Combustion is the chemical combination of the Carbon and 
 riydrogen of the coal with the Oxygen gas of the air, producing heat. 
 
 Weight for weight with Carbon, Hydrogen gives out the most 
 heat, as i lb. of Hydrogen contains about 62,000 units of heat, and 
 I lb. of Carbon about 14,500 units of heat, but in actual combustion 
 the amount of Hydrogen in coal is so small (about 5 per cent.) that 
 its heating power may be neglected altogether, and all the effective 
 heat assumed to come from the Carbon, which constitutes four-fifths 
 of the coal. 
 
 If twelve parts of Carbon (by weight) combine with thirty-two 
 parts of Oxygen (by weight), Carbonic Acid gas, CO.,, is obtained, 
 giving complete combustion. 
 
 If twelve parts of Carbon combine with less that thirty-two parts 
 of Oxygen, Carbonic Oxide gas, CO, is obtained, giving incomplete 
 ombustion, with a corresponding loss of heat. 
 
 The funnel gases consist chiefly of Carbonic Acid gas. Carbonic 
 Oxide gas, Oxygen and Nitrogen, or of CO.,, CO, O, and Free N. 
 
 NOTE. — Under conditions of good combustion the funnel gases are made up 
 as follows : — 
 
 Nitrogen = 80 per cent. COo = 10 per cent. 
 
 (CO, Oxygen, and H.jO) = 10 per cent. 
 
Marine Engineering Chemistry Notes 417 
 
 If CO is present in waste or funnel gases, combustion of the fuel 
 is incomplete and a loss of heat is taking place. 
 
 Black smoke is chiefly composed of uncombined particles of 
 Carbon. 
 
 In combustion the Sulphur of the coal combines with Oxygen 
 and produces SOo (Sulphur Dioxide), or more correctly Sulphurous 
 Anh}xlride. This is a colourless gas, possessing a strong, pungent smell. 
 
 Black smoke may be caused by excess of air as well as by want of 
 air, as excess of air lowers the temperature of combustion and prevents 
 the formation of COo. The surplus air absorbs heat in passing through 
 the funiaces. 
 
 If coal is placed in a closed chamber, technically known as a 
 retort, and subjected to destructive distillation, gases are given off, 
 leaving behind carbon in the form of coke. 
 
 Therefore, — 
 
 I. In complete combustion the Carbon of the coal combines 
 chemically with Oxygen of the air to produce COo gas. 
 
 3. In incomplete combustion part of the Carbon of the coal 
 combines chemically with the Oxygen of the air to produce CO gas, 
 and part combines mechanically with the air to produce black smoke. 
 
 3. In combustion the Hydrogen of the coal combines with 
 Oxygen of the air to produce water vapour, HoO. 
 
 4. In combustion the Nitrogen of the air remains chemically un- 
 combined, but passes up the funnel raised in temperature, thus carrying 
 off heat and representing the principal loss occurring in combustion. 
 
 Burning of CO. 
 
 A light bluish coloured flame noticed burning at the back of 
 the furnace indicates the presence of CO gas (Carbonic Oxide, or 
 Carbon Monoxide). 
 
 During combustion the Hydrogen in the coal, set free by the 
 heat, combines chemically with Oxygen of the air and produces 
 water vapour, the proportions being Hydrogen two volumes, and 
 Oxygen one volume, or HoO (water). 
 
 Carbon particles which have not been supplied with sufficient 
 Ox)-gen become mixed mechanically with the water vapour and 
 produce black smoke, the intensity of colour depending on the 
 proportion of solid Carbon held in suspension. 
 
 If COo gas combines with an additional amount of Carbon the 
 result is the formation of Carbonic Oxide (Carbon Monoxide), 
 
 Thus, C + C0o^2C0. 
 
4i8 
 
 "Verbal" Notes and Sketches 
 
 Heat in Carbon. 
 
 With perfect combustion each pound of Carbon converted into 
 COo gas (Carbon Dioxide) gives out about 14500 Heat Units. 
 
 With imperfect combustion each pound of Carbon converted into 
 CO gas (Carbon Monoxide) only gives out 4450 Heat Units: the 
 serious loss of heat resulting from incomplete combustion will thus 
 be obvious. 
 
 Scale, Density, and Corrosion. 
 
 The generation of steam being a continuous process the supply 
 of feed water must also be continuous, and this naturally results in 
 the concentration of the impurities introduced with the feed water ; 
 these impurities develop as scale, increase of density, corrosion, or by 
 suspended matter (oil). 
 
 Scale Deposit is due to the more or less combined effects of heat, 
 pressure, and concentration of impurities. 
 
 Corrosion is due chiefly to the introduction of gases and acids into 
 the boiler with the feed, but may also be caused by galvanic action. 
 
 Scale in forming may also indirectly produce corrosion, as, by the 
 effects of the heat when the scale matter conce^itrates and deposits, 
 acids (such as Hydrochloric) are set free which cause corrosion. 
 
 Composition of Fresh Water and Sea Water. 
 
 Fresh Water. 
 
 Name. 
 
 Grains 
 per Gallon. 
 
 Effect in Boiler. 
 
 Calcium Bicarbonate (or 
 
 Carbonate of Lime) 
 Calcium Sulphate (or 
 
 Sulphate of Lime) 
 Magnesium Sulphate - 
 Carbonate ofMagnesium 
 Chloride of Sodium 
 
 (common salt) 
 Silica, Iron Oxide, 
 
 Organic Matter 
 
 Total Grains per gallon 
 
 IO-8 
 
 •3 
 
 0-25 
 
 1-25 
 1-8 
 
 321 
 
 17-61 
 
 Forms lime carbonate scale at low pres- 
 sure and temperature (200° to 2 12°). 
 
 Forms hard scale at 40 lbs. absolute 
 pressure or 267" Temperature. 
 
 Remains soluble in the water. 
 
 Remains soluble in the water. 
 
 Begins to deposit at 35 oz. density and 
 \vaterisfullysaturatedat6ooz. density. 
 
 Form muddy deposits. 
 
 ;- 
 
Marine Engineering Chemistry Notes 
 
 419 
 
 Sea Water. 
 
 Name. 
 
 Grains 
 per Gallon. 
 
 Effect in Boiler. 
 
 Calcium Carbonate, or 
 
 3-9 
 
 Forms scale at low pressures and at 
 
 Carbonate of Lime 
 Calcium Sulphate, or 
 
 93-1 
 
 temperatures of from 200° to 212°. 
 Forms hard scale at about 40 lbs. abso- 
 
 Sulphate of Lime 
 Magnesium Sulphate - 
 
 1248 
 
 lute pressure and 267° Temperature. 
 Remains soluble in the water. 
 
 Magnesium Chloride - 
 
 220-5 
 
 Decomposes at 360° Temperature, and 
 liberates Hydrochloric Acid, the 
 Chlorine gas of which produces 
 severe corrosion. 
 
 Chloride of Sodium 
 (common salt) 
 
 1850- 
 
 Begins to deposit at 35 oz. density, 
 and water is fully saturated at 60 oz. 
 
 Silica, &c. - 
 
 8-4 
 
 density. 
 Form muddy deposits. 
 
 Total Grains per gallon 
 
 2300-7 
 
 
 NOTE. — At densities over 15 oz. per gallon the lime sulphate deposits at 
 lower temperatures than 267°. 
 
 NOTE.— Per cent, of Salt (Sodium Chloride) = ^ if,n»°° =8o per cent., or 4, 
 
 Incrustation (Scale). 
 
 A sample of boiler scale formed from Thames water was com- 
 posed of the following : — 
 
 Per cent. 
 
 Sulphate of Lime (CaS04) . . . - 20-41 
 
 Sodium Chloride (NaCl) - . . . 68-25 
 
 Magnesic Hydrate (MgHjOo) - - - - 2-81 
 
 Magnesic Chloride (MgCU) - - - - 3*14 
 
 Oxide of Iron (FcgOg) - - - - '02 
 
 Silica (SiOo) - - - - - -ii 
 
 Organic Matter . . . - . .10 
 
 Moisture (H^) - - - - - 5-16 
 
 Total 
 
 lOO-OO 
 
420 
 
 " Verbal " Notes and Sketches 
 Chemical Composition of Boiler Scale. 
 
 
 
 
 Sea Water 
 
 Fresh Water 
 
 
 
 
 Scale. 
 
 Scale. 
 
 Sulphate of Lime 
 
 (parts in 
 
 loo) - 
 
 85-53 
 
 3-68 
 
 Carbonate of Lime 
 
 
 ,, 
 
 •97 
 
 75-85 
 
 Hydrate of Magnesia 
 
 
 „ 
 
 3-39 
 
 2-56 
 
 Chloride of Sodium (salt) 
 
 
 „ 
 
 2-79 
 
 •45 
 
 Silica 
 
 
 „ 
 
 II 
 
 7-66 
 
 Oxide of Iron 
 
 
 „ 
 
 •32 
 
 2-96 
 
 Organic Matter 
 
 
 „ 
 
 
 3-64 
 
 Moisture 
 
 Total 
 
 - 
 
 - 
 
 5^9° 
 
 3-20 
 
 lOO-OO 
 
 lOO-OO 
 
 Scale and Oil Deposit Compared. — An oily deposit, yV inch thick, 
 on the furnaces will result in more overheating of the plates than that 
 produced by h inch thickness of lime scale. Oily matter deposits 
 more readily with a low boiler density, as with a higher density the 
 oily mass tends to float on the surface, whereas if the water is nearly 
 fresh the weight of the mass may cause it to sink down and deposit 
 on the combustion chamber tops, smoke tubes, or furnaces. 
 
 Temporary Hardness. — When water is boiled at 212° temperature 
 the CO.2 gas is driven off, and the carbonate of lime then becoming 
 insoluble is deposited ; thus the " temporary hardness " is got out of 
 the water. 
 
 Permanent Hardness. — Lime Sulphate, Lime Chloride, and Magnesia 
 Chloride form the permanent hardness of water, as these substances 
 are not deposited until a temperature of 267° is reached, when the 
 Lime Sulphate becomes insoluble and deposits in the form of Gypsum, 
 or hard close-grained scale. The Magnesium Chloride does not 
 deposit until a temperature of 360" is attained. 
 
 The scale formed from Lime Carbonate is more open in the pore 
 than that from Lime Sulphate, is lighter in colour, does not adhere so 
 closely, and is more easily removed. Lime Sulphate scale is often 
 combined with Lime Carbonate, and thus shows as a series of layers 
 of varying shade. 
 
 Corrosion of Boilers. 
 
 Parts Affected. — Damage to boilers is caused by internal or ex- 
 ternal corrosion, wearing away of the rusted edges by repeated 
 caulking of same, and by cracks due to unequal expansion or con- 
 
Marine Engineering Chemistry Notes 42 1 
 
 traction, which finally produce " fatigue " of the metal. The latter 
 condition is particularly applicable to the "saddle" of the furnace 
 where the combustion chamber is riveted to the furnace flange, and 
 which in so many boilers gives trouble by cracking or by leakage. 
 Leakage, if not taken up at once, will produce corrosion, as the 
 decomposition of the water or steam passing the leak liberates 
 Oxygen, which combining chemically with the metal produces oxide 
 of iron. On the furnace sides above the fire-bar level the intense heat 
 sets free ox}'gen bubbles, which adhere to the plate and produce 
 corrosion by chemical action. Again, the tendency to unequal ex- 
 pansion in the upper and lower half of the. furnace is apt to strain 
 the metal at this position and slightly fracture the surface skin, which 
 is thus placed in a condition most favourable to corrosion. 
 
 NOTE.— The upper half of the furnace is exposed to a temperature of about 
 2500^ and the lower half to a temperature of about 1000°. This is due to the fact 
 that the upper half receives the heat of convection, whereas the lower half onlw 
 receives the heat of radiation. 
 
 To sum up, the following positions are most often affected by 
 corrosion, &c. : — 
 
 1. On water sides of furnaces above line of fire-bars (see sketch). 
 
 2. Bottom of furnace near the back end, and bottom of combustion 
 chamber. 
 
 3. Cracks round corrugations of furnaces (expansion and con- 
 traction of metal). 
 
 4. Cracks near back ends of furnaces at combustion chamber 
 (more often in plain furnaces). 
 
 5. Corrosion at tube plates due to leaky tubes, or at combustion 
 chamber back and side plates due to leaky stays. 
 
 6. Corrosion at ends of furnaces due to straining set up by 
 expansion and contraction. 
 
 7. Corrosion at bottom of boiler and combustion chambers due 
 to deposits and to weak circulation at these parts. 
 
 8. External corrosion caused by damp (CO2 gas) from the bilges, 
 from wet ashes, and other similar causes. If manhole or sludge-hole 
 doors are not tight the leakage will in time produce corrosion, as 
 explained previously. 
 
 Furnace corrosion, cracks, combustion chamber and tube leakage 
 are all intensified in the case of forced draught owing to the higher 
 temperature of combustion obtained. 
 
 Causes of Corrosion. 
 
 1. Oxygen and CO, gas brought in with the air in the feed water 
 and set free by heat. 
 
 2. Chlorine gas set free by heat at high pressures from the 
 Magnesium Chloride contained in Sea water feed. 
 
 3. Galvanic action due to dissimilar metals, such as brass and 
 
422 "Verbal" Notes and Sketches 
 
 steel, &c., connected metallically in a solution of sea water or acid 
 water, such as is found in boilers. 
 
 4. Fatty acids set free by heat from oil taken into the boilers 
 with the feed water. 
 
 Stearic and Oleic acids are contained in vegetable and animal 
 oils, but not in mineral oil, which is of so-called pure " Hydrocarbon " 
 composition and free from acid of any kind. Cylinder or valve oil 
 should always be of this class. 
 
 It should be noted, however, that any class of oil if deposited on 
 the furnace crowns may bring about collapse. 
 
 Prevention of Corrosion. 
 
 Taking the case of new boilers, corrosion can be hindered to a 
 great extent by working as follows : — 
 
 1. By using some sea water feed and frequent surfacing, or by 
 the direct addition of lime, first obtain a light protective lime scale 
 of -^^ inch thick on the heating surfaces. 
 
 2. Use fresh feed water at all times if possible, and avoid alto- 
 gether the use of sea water as feed. For this a large evaporator is 
 necessary. 
 
 3. Employ a feed heater which, in addition to heating up the feed 
 water, extracts most of the air and other gases from the water gases, 
 which (in the case of Weir's heater) pass away to the condenser. 
 
 4. Employ a feed water filter which, fitted between the hot-well 
 and boiler check valves, traps most of the oil or grease which may be 
 present in the feed water when it leaves the condenser. 
 
 5. Fit inside of the boiler and in clean metallic contact with the 
 plates or stays, slabs of zinc to set up galvanic action between the 
 zinc and steel, which action results in the wasting away of the positive 
 element zinc and the proportionate protection of the boiler plates. 
 
 6. If necessary, use soda in moderation. 
 
 Hydrochloric Acid. — This corrosive acid is formed as a result of 
 the decomposition at high temperature of certain chlorides present 
 in sea water and reactions between such substances as Magnesium 
 Sulphate and Sodium Chloride. Hydrochloric Acid giving off 
 Chlorine produces corrosion in the steam space of boilers ; as, 
 however, it is both volatile and soluble, it may produce pitting 
 below the water line as well as above it. 
 
 Scale Deposit and Plate Temperature. — The overheating effects 
 produced on the furnace metal by various thicknesses of lime scale 
 deposit are shown below : — 
 
 A scale thickness of j\- inch requires an expenditure of 15 percent, more fuel. 
 >» )j 4 )» )) )> 00 ,, ,, 
 
 At a scale thickness of \ inch or less the plates may reach the 
 
Marine Engineering Chemistry Notes 423 
 
 critical temperature of over 600", and collapse of the furnaces take 
 place. This will easily be understood when it is stated that a 
 temperature of 700" produces a low red heat on the plate. 
 
 A scale thickness of -g^ inch is quite sufficient to protect the plates 
 from corrosion. 
 
 Magnesium Chloride. — This sea water chemical decomposes at a 
 temperature of 360", and the Chlorine set free combines with iron to 
 produce corrosion. During decomposition of Magnesium Chloride, 
 Magnesia is produced and deposits as a form of mud or slime. 
 
 A gallon of ordinary sea water contains about 220 grains of 
 Magnesium Chloride, and under conditions of heat and concentra- 
 tion this substance splits up into Hydrochloric Acid and Magnesia: 
 the acid mentioned combines with the iron of the boiler to form iron 
 salts, and therefore produces corrosion. 
 
 Corrosion of Tubes in Boilers. — May be due to (i) fatty acids 
 obtained from the decomposition of animal or vegetable oils ; (2) 
 H}drochloric Acid produced by the decomposition, at a high 
 temperature, of a magnesium and chlorine compound in the sea 
 water ; (3) galvanic action ; (4) the presence of Carbonic Acid and 
 air in the water. 
 
 Red and Black Iron Oxides. — Red oxide of iron (FegOg) is formed 
 when excessive air is entering the boilers with the feed water, and 
 Black Oxide of Iron (FcgOJ when the air admission is not excessive. 
 Air should therefore be kept out of the boilers as much as possible, 
 as the amount of corrosion will then be reduced in proportion. 
 
 Test for Carbonic Acid. — To test for the presence of CO2 gas in 
 boiler water : make up equal volumes of boiler water and lime water, 
 and if CO^ is present, the mixture will turn cloudy or milky in 
 appearance. 
 
 Evaporator Scale. — The scale in evaporators is chiefly Lime Car- 
 bonate, as the pressure and temperature carried is not high enough 
 to produce deposit of much Lime Sulphate. The Lime Sulphate 
 therefore remains in solution in the water, and is blown out by way 
 of the blow-down cock. 
 
 Boiler Deposits. — The impurities in boiler water are deposited in the 
 following order : — 
 
 1. Carbonate of Lime (at atmospheric pressure and 212° tem- 
 
 perature). 
 
 2. Sulphate of Lime (at 267° temperature, 40 lbs. absolute pressure). 
 
 3. Oxide of Iron. 
 
 4. Silica, Alumina, Magnesia Hydrate. 
 
 5. Common Salt (at 35 oz. density deposit begins, and the water 
 is fully saturated at 60 oz. density). 
 
424 " Verbal " Notes and Sketches 
 
 Leaky Tubes. — If cold air is admitted to the tubes by opening the 
 smoke-box doors the tubes arc apt to contract and leak at the ends. 
 Leaky tubes may therefore be caused by (i) unequal expansion, or 
 by (2) unequal contraction of the tubes and plates. Severe vibration, 
 due to blowing down, may also produce leaky tubes. It should also 
 be noted that leakage ultimately sets up corrosion on the plate round 
 the tube necks and on the tubes themselves. 
 
 Density and Scale. — The following points should be carefully noted : — 
 
 1. Scale deposit is due to heat, and is quite independent of evapora- 
 tion, as, even though no evaporation is going on in a boiler (under 
 banked fires), if sea water feed is admitted scale will be deposited 
 shortly afterwards. 
 
 2. Increase of density (over 5 oz. per gallon) is entirely due to 
 evaporation, as, if no evaporation takes place, the boiler density cannot 
 rise above that of sea water feed. 
 
 Therefore, the limit of density (saturation point) being 35 oz., 
 should the boiler reach this density, and still more sea water feed 
 be pumped in, when the water so fed in evaporates, the salt contained 
 in it will be deposited. 
 
 NOTE.— It must be clearly understood that the salt forming the 35-oz. density 
 does not deposit, but only the salt contained in feed water put in after the 35-oz. 
 density has been reached. 
 
 General Notes on Scale and Salting. 
 
 Salting or saturation of the boiler water means that the density 
 has reached /o, or 35 oz. per gallon. If at this density more sea water 
 feed is admitted the salt in it begins to deposit after the w^ater 
 evaporates. 
 
 Scale consists chiefly of sulphate of lime and carbonate of lime. 
 
 Scale is caused by the action of heat on sea water feed. The 
 heat concentrates the sulphate and carbonate of lime, and as a result 
 these substances deposit on the tubes, furnaces, &c. This occurs 
 when the air and CO.^ gases are expelled by heat. 
 
 To sum up, scale is due to heat, and is quite independent of 
 evaporation, as although no evaporation takes place scale may yet 
 deposit. Increase of density above 5 oz. (sea density) is entirely 
 due to evaporation, and cannot take place unless evaporation 
 goes on. 
 
 All waters contain lime, so that even with fresh water feed scale 
 will form (chiefly carbonate of lime), but the hardest and most 
 troublesome scale is that deposited by sea water feed, as it is largely 
 composed of sulphate of lime. 
 
 Sulphate of lime scale forms from a pressure of 40 lbs. absolute 
 and a temperature of 267°. 
 
 Scale increases with the pressure, because the temperature is 
 higher in proportion. 
 
Marine Engineering Chemistry Notes 425 
 
 The scale thickness depends upon the amount of sea water put 
 into the boiler as feed, and does not depend upon the density of the 
 boiler. 
 
 Surfacing a boiler (having no evaporator fitted) reduces the density 
 but increases the amount of scale, because every time the boiler is 
 surfaced extra feed water has to be pumped in, therefore more 
 sulphate of lime will deposit. The scale formed from fresh water 
 feed is composed chiefly of carbonate of lime. 
 
 To form a scale on a new boiler, keep the density low by surfacing 
 and feed up with sea water. This will cause rapid deposit of sulphate 
 and carbonate of lime, and the formation of a protective scale on the 
 heating surfaces. 
 
 As oil in boilers causes pitting, and may also bring down the 
 furnaces by depositing on them, it is best kept out altogether, and 
 this is done by having a feed filter fitted between the feed pump 
 and the boiler check valve. 
 
 A feed heater is used for raising the temperature of the feed 
 water, and partly clearing i1» of air before entering the boiler. 
 
 Solids in Sea Water. — The solid matter in sea water (forming gV of 
 the weight) is chiefly made up (approximately) as follows : — 
 
 Sodium Chloride (common salt) - - 80 per cent. 
 
 Magnesia Chloride - - - - 10 ,, 
 
 Magnesia Sulphate - - - - 6 ,, 
 
 Calcium Sulphate (gypsum) - - - 4 „ 
 
 In addition to the above. Calcium Carbonate exists in combination 
 with COo, forming Calcium Bicarbonate in solution. The heat drives 
 off the COo and the Calcium Carbonate is left, which, depositing, forms 
 a scale. 
 
 Calcium Sulphate. — This forms the hardest scale found in boilers, 
 and is deposited largely from sea water feed. It is similar to plaster 
 of Paris and marble (gypsum). 
 
 Calcium Carbonate. — This composition gives a softer scale than 
 Calcium Sulphate unless combined with the latter, and is similar to 
 common chalk. 
 
 It is deposited chiefly from fresh water feed when the CO2, 
 previously in combination with it, is set free by heat. 
 
 NOTE. — The scale found in evaporators is principally made up of Calcium 
 Carbonate. 
 
 A piece of Calcium Carbonate scale, when broken across, is coarser in the grain 
 than Calcium Sulphate scale. 
 
 Soda. — The addition of an alkali such as soda into the boiler feed 
 water has the effect pf tending to convert the Calcium Sulphate into 
 
426 "Verbal" Notes and Sketches 
 
 Calcium Carbonate, and thus make the scale less objectionable 
 and less insoluble. Soda being an alkali also tends to combine with 
 acids present in the water, and, forming chemical salts, destroys the 
 corrosive effects of the acids. 
 
 The addition of soda into a boiler often causes the density to rise 
 shortly afterwards, as the soda softens the hard scale, and, making it 
 soluble, the water becomes denser in proportion. 
 
 Lime. — When lime is used in boilers, the proportion to allow is about 
 i^ lbs. of lime per day per each icxx) I.H.P., dissolved in i gallon of 
 water, and forming what is known as " milk of lime." 
 
 This mixture is very useful in forming a scale on a new boiler, and 
 should be used when the boiler water shows of a red (rust) colour. 
 
 Rusting. — Iron immersed in pure water free from air will not rust, 
 but with air present rusting takes place owing to the fact that 
 air contains a small percentage of carbonic acid, which in contact with 
 iron decomposes the water and sets free Hydrogen, which thus allows 
 the Oxygen to combine chemically with the iron and form oxide of 
 iron, Fe203 (or Ferric Oxide). 
 
 Grooving. — By this is meant corrosion produced by mechanical 
 causes, such as unequal expansion. An example can be found in the 
 case of vertical donkey boilers, at the bottom of the fire-box, where 
 the expansion at the top end being much more than at the bottom 
 (the latter being rigidly riveted to the shell), the resultant stresses set 
 up crack the skin of the metal circumferentially, and the skin thus 
 broken, allows of corrosion taking place to a serious extent. 
 
 Paraffin Oil. — Paraffin oil is sometimes used in boilers with the 
 object of softening the scale, which is then found to be easily 
 removable. The heating surfaces are treated by being rubbed over 
 with the oil and allowed to stand for a few hours before filling up. 
 
 Carbonate of Soda. — The moderate use of soda is to be recom- 
 mended, as the Soda has the effect of converting the Lime Sulphate 
 into Lime Carbonate. 
 
 . Nitrate of Silver Test for Saltness. — As boilers are now often 
 worked at an extremely low density (i oz. or 2 oz.), it becomes 
 necessary to employ a more sensitive method of testing for the 
 density than by the salinometer, and this can be carried out by a 
 Nitrate of Silver test. A supply of this chemical having been obtained 
 a few drops added to a glass of the boiler water will quickly discover 
 the presence of salt by the water instantly becoming cloudy. This 
 method is also the most suitable for testing the tightness of the 
 condenser, as the smallest leakage will be indicated. 
 
Marine Engineering Chemistry Notes 427 
 
 Nitrate of Silver Test. 
 
 This test only proves the presence of salt — not -the quantity per 
 gallon. 
 
 Solution =4 per cent, nitrate, the remainder being water, and when 
 made up appears as a colourless liquid (like water). 
 
 The presence of salt is indicated by the water becoming cloudy 
 when the nitrate solution is dropped into the sample. 
 
 Caustic Soda. — Caustic soda added to boiler water has the effect of 
 converting the Hydrochloric Acid into common salt, thus destroying 
 the corrosive properties of the acid. The usual allowance of soda is 
 about li lbs. to 2h lbs. per 1000 I.H.P. per 24 hours. 
 
 When pitting or corrosion is located in patches or small areas, 
 the plates affected should be scraped clean, and washed with soda 
 solution. A final coating of weak solution of Portland cement will 
 reduce the danger of the corrosion spreading. 
 
 Corrosion in the form of oxide of iron formation is apt to occur 
 in those positions of a boiler where the circulation is weak, such as 
 the lower parts of the furnaces and combustion chambers, and if 
 once started may extend to other parts higher up. 
 
 Heating Effect of Scale. — A scale of gV inch is sufficient to protect 
 the plates from corrosion, and any increase over this may lead to 
 serious overheating, especially in the case of forced draught boilers 
 carrying a high water gauge air pressure. 
 
 New Boilers. — Messrs Babcock & Wilcox recommend that 10 lbs. 
 of lime per each 1000 I.H.P. be put into the boiler when new, and 
 from 4 to 6 lbs. per day per 1000 I.H.P. for six days afterwards : the 
 object of this is to form a light protective scale on the heating 
 surfaces. 
 
 In the first case the lime should be dissolved in water, and poured 
 in through the manhole, and in the second case the mixture (made up 
 as milk of lime) should be put into the hot-well. 
 
 Test for Acid. — Draw off some of the boiler water and put into it a 
 few drops Methyl-Orange (obtainable at the chemist). If the water 
 remains yellow then it indicates an alkaline condition, but if the 
 water turns into a pink colour it indicates the presence of acid. 
 
 Action of Lime. — Lime added to the boiler water has the effect of 
 converting the Magnesium Chloride into Magnesia and Calcium 
 Chloride, the former being corrosive and the latter non-corrosive. 
 
 Hydrometer. 
 
 This instrument, which is simply a type of salinometer, is employed 
 in Naval practice, and is generally graded for use at a temperature of 
 80° instead of 200°. The divisions or degrees represent half ounces, 
 so that 20 indicates a density of 10 oz., 15, 7| oz., and so on. The 
 hydrometer thus allows of finer density readings than those obtained 
 by the ordinary salinometer. 
 
428 " Verbal " Notes and Sketches 
 
 Oils. 
 
 Lubricating Oils. 
 
 For cylinder lubrication, mineral oil only should be used, as this 
 class of oil is composed of Hydrogen and Carbon and is free of acids. 
 The flash point should not be less than 400° Fahr. 
 
 The Viscosity of an oil or cohesive nature of the fluid should be such 
 that the lubricant is not so thick as to produce friction, nor yet so thin 
 as to be squeezed out from between the surfaces in contact. Viscosity 
 may be said to be the consistency of the oil, and should be high for 
 heavy bearings and low for lighter wearing parts. The viscosity of 
 all oils becomes reduced with increase of temperature. 
 
 Gumminess. — If an oil evaporates easily it will naturally become 
 gummy and lose proportionally its lubricating properties. A rough 
 test for gumminess can be made by painting over an earthenware dish 
 with the oil and placing it in a warm position, where it can be tested 
 by hand at intervals for stickiness. 
 
 Classes of Oil. 
 
 [ I. Extracted from Shale, and Cannel coal. 
 
 Mineral Oils. \ 2. Found in Russia and America in oil springs. Paraffin, 
 ( Petroleum, Kerosene, Benzine, Naphtha, &c. 
 
 VpD-pfflhI 0'1<5 / C°^^^> Linseed, Rape, Castor, Olive, Cottonseed, &c. 
 vegetaoie UUS. ^ Manufactured from the seeds of the plants named. 
 
 Animal Oils. — Sperm (whale). Seal, Neatsfoot. 
 
 At moderate temperatures vegetable oils decompose into Oleic 
 acid, and animal oils into Stearic acid, both of which act corrosively 
 on the cylinders, valve faces, and on the boilers if admitted with the 
 feed water. 
 
 Oil Emulsion. — Although feed water filters collect most of the grease 
 or oil in the water often a certain amount passes the filter cloths in 
 the condition known as " emulsion," and the small atoms of oil 
 in this state combine easily with the Magnesia present in the boiler 
 water, resulting in the formation of a slimy deposit, which forms a 
 bad non-conductor of heat, and which may bring about buckled 
 plates or collapsed furnaces. 
 
 "Saponification." — If animal or vegetable oils enter the boilers with 
 the feed water, and soda is present, then the fatty acids of the oil 
 (set free by the heat) combine with the soda to form a soapy substance 
 which is a particularly bad conductor of heat, and which if deposited 
 on the furnace crowns is likely to bring about buckling or collapse 
 of the same. The combination of the acids and soda is called 
 "saponification." 
 
 Care of Boilers. — Regarding oil the following points should be 
 attended to : — 
 
 1. Use minimum quantity of cyhnder oil. ~ 
 
 2. Work at a density which will " float " any oil which may enter boilers. 
 
 3. Clean filter cloths weekly. 
 
Marine Engineering Chemistry Notes 429 
 
 To Test Acidity of Oil. 
 
 A. Make up a solution of Sodium Chloride with an equal weight of 
 water, take a measured quantity of the solution and an equal quantity 
 of the oil, which place together in a bottle. Shake up the bottle and 
 allow it to stand, after which, if acid is present, it will show by settling 
 to the bottom of the bottle. If no deposit takes place the oil is free 
 from acid. 
 
 B. Chemically prepared papers of a pale bluish tint and known 
 by the name of "litmus papers," can be obtained in little books at 
 a very small cost from any chemist, and these can be applied to test 
 the acidity of an oil. To make the test, boil some of the oil and 
 dip one of the litmus papers into it, and if, on withdrawing, the colour 
 has become a deeper shade only, the oil is clear of acid ; but if 
 the paper changes to a pink or red colour, it denotes with 
 certainty the presence of acid in the oil, which should therefore 
 be rejected for purposes of internal lubrication. The redder the 
 paper becomes, the greater is the quantity of acid present in the oil. 
 
 Boiler water can be tested for acid in the same way. 
 
 NOTE. — A clean copper -wrire if immersed in oil for a few hours will show 
 discoloration if acid is present. 
 
 '/iscosity Test for Oil. — The viscosity of an oil is tested in the 
 following manner. The apparatus consists of a small cup-shaped 
 vessel fitted with an internal pan, in the bottom of which a small 
 round hole is truly bored, and a thermometer dips into the oil ; 
 the oil is then heated up to a fixed temperature, say 180°, and the 
 time taken for a measured quantity of oil to drip out through the 
 small hole in the bottom is noted. Oil of high viscosity will take 
 a longer period to escape than oil of low viscosity. 
 
 To Test for Animal or Vegetable Oils. — To test whether an oil 
 is of vegetable or animal nature add a small portion of chlorine to 
 the oil, and note the change of colour ; if to brown the oil is animal, 
 and if to white the oil is vegetable. 
 
 Alkali Test. — To test for alkalinity use red-coloured litmus paper, 
 which will change to blue if the water is strongly alkaline. 
 
 Most of the oil used for internal lubrication of the engines finds its 
 way to the boilers, (unless extracted by means of a filter), by being 
 brought with the steam into the condenser, and afterwards pumped 
 into the boilers by the feed pumps. 
 
 "Alkala" Boiler Composition. 
 
 Lambie's patent boiler composition, known as " Alkala," has 
 proved, after severe and exhaustive tests, to be most effective in 
 
430 "Verbal" Notes and Sketches 
 
 the prevention of scale deposit and corrosion; used in conjunction 
 with the usual zinc plates, boilers working under the highest pressures 
 are found to be in excellent condition after months of hard steaming, 
 the scale being of a light, easily removable nature, and the pitting or 
 corrosion checked to a remarkable degree. Alkala is a paint and 
 is applied by brush to the parts requiring protection, such as furnaces, 
 plates, stays, and tubes. The compositian referred to is rapidly 
 becoming known as the most efficient boiler preservative in the 
 market. 
 
 Remedies for Pitting. 
 
 Zinc plates (see page 143) are used internall)' to check the wasting 
 of the plates, and are fitted so as to form with the boiler plates a 
 galvanic couple, of which the zinc is the positive element. The zinc 
 plates are connected metallically to the boiler by the following 
 methods : — (i) Studs screwed into the furnace sides ; (2) metal hangers 
 suspended from the stays. Sometimes zinc balls with a copper wire 
 passed through them and connected to the boiler are used instead. 
 These are called " Electrogens." Externally, feed heaters (such as 
 Weir's) assist in keeping out the air, and feed filters assist in keeping 
 out the grease or oil. 
 
 Galvanic Action. 
 
 If two dissimilar metals are placed in a bath of sulphuric acid, 
 both will in time show signs of corrosion ; but, if the two metals 
 are connected by a copper wire soldered to each, then only one of 
 them will corrode, as a galvanic couple is then formed, and the 
 corrosive effects take place on the most electro-positive metal only. 
 (See page 432.) 
 
 By connecting the two metals a weak electrical current is set 
 up between them, through the liquid and wire, resulting in the 
 wasting away of the one element which is electro-positive to the 
 other. 
 
 Examples of the foregoing are to be found in the boilers by the 
 zinc plates fixed inside, and on the tail end shaft at the end of 
 the brass liners, the brass and iron or steel of the shaft being 
 dissimilar metals and connected in a bath of sea water. Sea water, 
 as it contains salt, acts in a like manner to sulphuric acid, but in 
 a milder form. 
 
 NOTE, — The current flow is produced by the difference in electrical potential 
 obtained. 
 
 Rusting. 
 
 Rusting of a metal is an example of combustion at a low 
 temperature, and is due to the Oxygen of the air combining with 
 iron (or steel) to form Oxide of Iron, 
 
Marine Engineering Chemistry Notes 431 
 
 The chemical name for red iron rust is Ferric Oxide, or, by 
 symbols (FcoOg). 
 
 Rusting- is in reality the burning of the metal, but at a low 
 temperature (the atmospheric temperature). 
 
 Rusting can only take place when Carbonic Acid gas (CO.^) is 
 present in quantit)-, as in a clamp atmosphere. 
 
 Rusting cannot occur in a dry atmosphere. 
 
 A good example of rusting, or the formation of oxide of iron, 
 is to be seen at the water line on the wet uptake of vertical boilers. 
 The action that takes place is as follows : — The intense heat on one 
 side of the plate sets free the Oxygen of the water adhering to the 
 plate on the other side, and the Ox)'gen being present with Carbonic 
 Acid gas combines with iron to form Oxide of Iron, or rust (Ferric 
 Oxide). 
 
 If a rivet or stay in the combustion chamber leaks, and the 
 leakage is not at once checked, the plate and stay will soon begin 
 to waste awa)', owing to the formation of Oxide of Iron. 
 
 Oxide of Iron formation also accounts for the wasting away of 
 boiler bottoms, just above the bilges, furnaces at the ashpits, and on 
 the tops of tanks. 
 
 Condenser Tube Corrosion. 
 
 In most cases the corrosion of condenser tubes is due to one of the 
 following causes : — 
 
 (i.) Galvanic action produced between the condenser metal and 
 tubes in sea water, resulting in the loss of the zinc, of which the tubes 
 are partly composed. This produces small holes in the tubes at 
 various positions throughout the length, but usuall}' near the ends, 
 and is known as " de-zincification." 
 
 (2.) Acids from animal or vegetable oils producing corrosion on 
 outer surface of the tubes by chemical action. 
 
 (3.) General thinning of the tube by wear, and caused by the long- 
 continued mechanical attrition action of the water inside the tubes. 
 
 In the great majority of cases the corrosion is caused b)' decom- 
 position of the zinc, as stated in No. i cause. 
 
SECTION VII, 
 
 MARINE ELECTRIC LIGHTING. 
 
 General Description. 
 
 The following elementary description of electric lighting is intended 
 by the author for marine engineers who have had no experience with 
 dynamos, and who may have had no opportunity to study electricity — 
 in other words, for beginners. 
 
 Galvanic Cells or Batteries. — An electric current may be produced 
 either by chemical or mechanical means. If chemically, by a galvanic 
 battery or cell ; and if mechanically, by a dynamo. 
 
 WIRE 
 
 i 7/ ACID 
 
 /A SOLUTION 
 
 No. I.— Simple Cell. 
 
 The sketch shows a simple cell, or galvanic couple, consisting of 
 two plates, one of Copper and one of Zinc, placed in a bath of 
 sulphuric acid, and connected together at the top by a wire. A 
 current flows from the Copper plate through the wire to the Zinc 
 plate, and back again from the Zinc through the liquid to the Copper. 
 The Copper is called the " positive pole " but the 7iegative element, 
 
 432 
 
Marine Electric Liohtine 
 
 433 
 
 and the Zinc the negative pole and the positive element. The dotted 
 lines in the sketch show how the current may be led to an external 
 circuit so as to do work, such as, for example, to operate an electric 
 bell, instead of passing direct from one plate to the other, as shown 
 by the full lines. 
 
 It should be noted that the current flowing in the direction 
 described results in the dissolving of the zinc plate, and the formation 
 of sulphate of zinc. 
 
 NOTE.— The current flow is produced by the difference of electrical potential 
 obtained. 
 
 Daniell Cell. — One form of this well-known t)-pe of galvanic cell is 
 shown in the sketch, in which the outer vessel is of Copper and 
 constitutes the positive pole. The inner vessel is of porous construc- 
 tion to allow of the liquid to pass through gradually, and the negative 
 pole is formed by a rod of Zinc placed inside. Two liquids are em- 
 
 ZINC 
 
 VES6EL"P^ 
 
 r;^ OF COPPER 
 // SOLUTlOrS 
 
 Z^. SULPHURIC 
 7/ ACID 
 22 SOLUTION 
 
 No. 2.—" Daniell " Cell. 
 
 ployed — sulphate of copper solution in the outer vessel, and, as in 
 the simple cell, sulphuric acid in the inner vessel. The current flows 
 from the Copper to the Zinc as described previously in the case of 
 the simple cell. 
 
 The electro-motive force of the Daniell cell is fully one volt. 
 Dotted lines are shown in the sketch to illustrate the manner in 
 which the current may be applied to an external circuit, instead of 
 passing directly from one pole to the other. 
 
 Electro-Magnets. — If a bar of Iron is enclosed within a coiled wire, 
 and a current from either a galvanic battery or a dynamo passed 
 through the wire, the bar becomes magnetised for so long as the 
 current is passing. 
 
434 
 
 " Verbal " Notes and Sketches 
 
 IRON 
 
 WIRE 
 
 No. 3.— Electro-Magnet. 
 
 TO SWITCHBOARD 
 
 TERMINAL 
 
 FROM 
 SWITCHBOARD 
 
 BASE PLATE 
 
 No. 4.— Dynamo. 
 
Marine Electric Lightin 
 
 435 
 
 The bar is then known as an electro-magnet. If the bar is bent 
 into a horse-shoe shape so as to form two legs, when a current is 
 
 iiriDilO NlVW Oi 
 
 j.mDyo wiu 01 * 1 
 
 
 
 ^ — 
 
 ttA.i 
 
 
 
 
 / 
 
 n 
 
 L 
 
 
 ^ 
 
 
 r 
 
 
 V"' 
 
 k^5i 
 
 UJ O 
 
 
 in 
 6 
 
 passed through the wire both legs of the bar become magnetised, 
 and form a pair of electro-magnets. The space between the legs is 
 called the " magnetic field," and if an armature be made to revolve in 
 
43^ 
 
 " Verbal " Notes and Sketches 
 
 the magnetic field so as to cut the lines of force or magnetism passing 
 across, currents are generated in the coils or conductors of the 
 armature. The two legs constitute north and south poles. 
 
 The field magnets of a dynamo are of the type just described, the 
 poles receiving their magnetism from the dynamo itself, as the winding 
 of the magnets consists of wires led direct from the brushes, the wires 
 obtaining their current direct from the armature. 
 
 A dynamo is a machine which, by the application of mechanical 
 power, generates electro-motive force. This electrical force or power 
 can be utilised either for lighting or for the running of motors, or for 
 both purposes combined. 
 
 The four principal parts of a dynamo are — (i) Field magnets; 
 (2) armature ; (3) commutator ; (4) brushes. 
 
 Field Magnets. — The field magnets consist (in a two-pole dynamo) 
 of two masses of cast steel connected at the top by a " yoke piece " 
 
 No. 
 
 6.—" Belliss " Engine direct coupled to GE.C Witton 
 Generator used for lighting and power on board Steam 
 ships, Shipyards, Dockyards, Factories, &c. 
 
 which gives to them the well-known horse-shoe shape. Each magnet 
 is wound with coils of insulated copper wire which are in connection 
 with the armature by one of three ways — (i) In series ; (2) in shunt ; 
 or (3) compound, which is a combination or compound of the first two. 
 In series winding the ivkole of the current generated in the armature 
 passes from the brushes round the field magnets, and then to the 
 lamps and back again. 
 
Marine Electric Lighting 437 
 
 In shutit winding only part of the current passes round the field 
 magnets, as the shunt wire to the magnets is smaller and finer than 
 the series wire, and in this way offers more resistance to the current. 
 
 In coinpoiDui winding the field magnets are wound with two sets 
 of wire, and the whole of the current generated in the armature passes 
 round them, but by two distinct and separate paths ; first by the 
 thick or series coils, and next by the thin or finer " shunt " coils. The 
 object of this method of winding may be described as follows : — As 
 lamps are switched on and more current is required, the extra current, 
 on its way to and from the lamps, passes through the series coils of 
 the magnets, and therefore strengthens the magnetic field in pro- 
 portion. Again, if a certain number of lamps are switched off, less 
 current passes through the series coils as less is now passing through 
 the main wires, but more current will pass through the shunt coils, 
 and thus tend to maintain the same strength as before in the magnetic 
 field, and keep the voltage constant. 
 
 It will thus be seen that a compound wound dynamo is, to a great 
 extent, self-regulating, and retains practically the same voltage, no 
 matter how many lamps are on or off. This is of great importance 
 in ship-lighting, and for this reason nearly all dynamos used for 
 marine purposes are of the compound wound type. 
 
 It should be noted that the exciting current for the magnets comes 
 from the armature itself, and though small at first, increases as more 
 current is developed, so that the one, in a sense, supplies the other in 
 proportion to the demand. 
 
 On examining a dynamo of the compound wound type, it will be 
 noticed that the wires from the brushes are connected to terminals or 
 studs fixed on an insulated plate which is placed on the side of the 
 field magnets, and from these terminals the main leads or wires to the 
 lamp circuits are branched off, and' the series coils and shunt coils to 
 the magnets. 
 
 The fine shunt wire will generally be seen to connect across the 
 two magnets and to the main terminals, as shown in the sketch. 
 
 Four-Pole Dynamos are now being supplied for ship-lighting, and 
 it is evident that this type is rapidly coming to the front and taking 
 the place of the older-fashioned two-pole machine. In some cases 
 six-pole machines are supplied. 
 
 The four-pole dynamo is supplied with four sets of brushes, each 
 alternate set being in connection, so that there are two sets of positive 
 and two sets of negative brushes in use. The other parts of the 
 machine are similar to those of the ordinary two-pole dynamo, but 
 the four-pole type is of more compact form, and can be made of high 
 magnetic strength. On examining a dynamo of this type, the thick 
 wires of the series and the fine wire of the shunt will be noticed 
 extending from one magnet to the other, and connecting them with 
 the brushes and lamp cables. 
 
43^ 
 
 Verbal " Notes and Sketches 
 
 Armature. — The two types of armature in general use for ship- 
 lighting dynamos are those known as the " Ring " and " Drum " type, 
 the latter being usually preferred and supplied asbeing the best suited 
 for the work. It will therefore be sufficient to describe this type of 
 armature in detail. 
 
 The "Drum" pattern of armature is formed of sheets of soft iron 
 or steel discs insulated from each other and clamped together on a 
 sleeve keyed to the spindle or driving shaft. The sleeve is cast with 
 recesses and webs so that air may pass freely from end to end, and 
 by the ventilation so afforded prevent excessive rise of temperature 
 when the armature is revolving at a high speed. The iron or steel 
 discs are slotted longitudinally for the reception of the insulated 
 copper conductors or wires, and each slot is also carefully insulated 
 
 Copper 
 
 STRIP 
 
 COMMUTATOR 
 
 COIL 
 
 No. 7.— Drum Armature, showing one Conductor Connected. 
 
 and the copper wire embedded in it. The complete armature consists 
 of a number of these conductors wound on the surface of the com- 
 pressed iron sheets or discs, and each conductor passes from the 
 commutator end back to the other end, and then forward again to 
 the commutator end, where the extremities of each conductor are 
 connected (usually soldered) to the copper strips or bars of the 
 commutator. 
 
 Each conductor has one end connected to one copper bar of the 
 commutator and the other end connected to the adjacent bar, so that 
 when all the conductors are fixed and bound in place they form an 
 enclosed ring right round the armature and commutator, and thus 
 allow of the passage of the currents generated from the one end to 
 the other, and so to and from the brushes and main wires. 
 
 Calling the commutator end of the armature the front, and the 
 other end the back, it should be noted that when the armature is 
 revolving, currents are passing from the front end to the back in one 
 ha/f oi \\\Q. armature circle, and from back to front in the other half 
 of the armature circle. The currents passing from front to back are 
 negative, and those from back to front positive, and the corresponding 
 
Marine Electric Liohtincr 
 
 439 
 
 brushes are placed in contact with the commutator to transmit the 
 current flow in the directions indicated. 
 
 It will be seen then, that current is constantly passing from the 
 back end of the armature to the front and into the commutator strips, 
 and from there to the positive brushes ; also, that current is constantly 
 passing from the negative brushes into the commutator and along the 
 armature from front to back. It therefore follow s that if we were to 
 connect the brushes, positive and negative, the circuit would be com- 
 plete, but if we first extend the connection before joining the positive 
 and negative we will still have the circuit complete. This is done in 
 practice by joining cables to the brushes and carrying the wires or 
 cables to different parts of the ship, where they are connected at 
 
 No. 8.— Diagram showing Magnetic Field and " Lines of Force." 
 
 various points by the lamp wires through which the current must first 
 pass on its way back to the negative brushes of the d\-namo. 
 
 NOTE. — Field magnets are generally composed of hard steel, as when once 
 magnetised the magnetic influence is retained for some time, and thus allows of the 
 "building up" of current when the dynamo is first started, otherwise the machine 
 would refuse to generate. 
 
 The armature core is made up of soft or charcoal iron discs, as 
 this material allows of rapid magnetic saturation and of as rapid 
 demagnetisation, which is a necessary requirement in an armature. 
 
 The above diagram illustrates, in an imaginary way, the field space 
 
440 
 
 "Verbal" Notes and Sketches 
 
 of a two-pole dynamo, and shows how the Hnes of magnetic force are 
 supposed to extend from the N pole to the S pole, the space between 
 the poles being filled up with these invisible lines of force. 
 
 It can easily be imagined, then, that if the field space be filled up 
 with an armature composed of soft iron, the lines of force will meet 
 with less resistance in passing across from pole to pole. 
 
 No. 9.— Diagram of Magnetic Field. 
 
 From A to B negative currents are increasing in intensity. 
 From B to C negative currents are decreasing in intensity. 
 From C to D positive currents are increasing in intensity. 
 From D to A positive currents are decreasing in intensity. 
 
 At positions D and B the armature conductors are cutting through 
 the greatest possible number of "lines of force," hence the intensity of 
 the current strength at these positions. 
 
 On the left-hand side the currents are passing from back to front, 
 and are positive, while on the right-hand side the currents are passing 
 from front to back, and are negative. A and C are the zero positions 
 of current change from positive to negative, and from negative to 
 positive. 
 
Marine Electric Li<Thting 
 
 441 
 
 Sketch No. 10 shows the direction taken by the current in each half 
 of the armature circle. Notice that on the " positive " side the currents 
 are travelling in the armature conductors from back to front (calling 
 the commutator end the front), and so into the positive brush and on 
 to the lamp circuits ; while on the "negative" or "return" side, the 
 currents are passing from the negative brush back into the com- 
 mutator bars, and so into the armature conductors. 
 
 No. 10.— Plan of Armature and Field Magnets. 
 
 Sketch No. 1 1 is self-explanatory, and shows diagrammatically the 
 positive and negative current flow in an armature conductor at different 
 parts of the circle. The plus sign indicates positive connections, and 
 the minus sign the negative connections. Observe that at the top 
 " zero " line the current changes from positive to negative, and at the 
 bottom "zero" line the current changes from negative to positive. 
 
 NOTE.— A volt is the E.M.F. required to product one ampere of current when 
 opposed by one ohm resistance. 
 
442 
 
 "Verbal" Notes and Sketches 
 
 Diagram No. 12 shows one method of armature winding for a 
 two-pole dynamo. Observe that, when arranged in a circle, the 
 commutator bar No. i is adjacent to bar No, 10, and that the corre- 
 sponding conductor extends between the two, being soldered to each. 
 
 A CURRENT 
 
 No. II.— Diagram showing Flow of Current in Single Conductor 
 
 of Armature. 
 
 The arrow shows the run of the conductor referred to, and also shows 
 the direction of the current flow. Each armature conductor is 
 similarly connected. 
 
 NOTE. — In the above diagram the complete conductor connections for No. 6 bar 
 only are shown. From this it will be seen that two ends of two different conductors 
 are connected to each commutator bar. 
 
Marine Electric Liofhtino- 
 
 443 
 
 3 
 
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 V 
 
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 6 
 
 2 
 
444 " Verbal " Notes and Sketches 
 
 Commutator. — All dynamos are originally what is called alternating 
 — that is, the currents passing in the armature coils are always 
 passing alternately in opposite directions, from back to front and from 
 front to back ; but by means of a commutator these alternations of 
 current can be made to flow always in one direction, and the dynamo 
 is then known as of the "continuous current" type. For ordinary 
 lighting purposes this type is always employed, but for large power 
 stations (such as for electric tramways) the alternating type is used, 
 as being better suited for high tensions or voltages. As mentioned 
 before, currents are constantl)' passing from one end to the other in 
 one half of the armature circle, and in the reverse directions in the 
 other half, so that if the brushes are placed at the neutral points where 
 the direction of the currents is reversed, the flow will then be "com- 
 muted " or continuous in the one direction. From this it will be 
 
 No. 13. — Armature and Commutator Complete. 
 
 apparent that to make a dynamo of the continuous current or direct 
 type a commutator is necessary. 
 
 The commutator consists of hydraulic pressed solid copper bars 
 arranged in a circle on a sleeve keyed to the driving shaft at the end 
 of the armature, each bar being insulated from the one adjoining 
 by mica insulation. As before described, the ends of the copper 
 conductors of the armature are connected metallicall}' to the commu- 
 tator bars, one end of two separate wires being so connected to one 
 copper bar. The current after passing from the armature into the 
 commutator is absorbed or collected by the positive brushes, and 
 after going through the lamp circuits' is again delivered back to 
 the commutator and armature by the negative brushes. Observe 
 that a complete circuit must be described before any current can 
 possibly pass. 
 
 Brushes. — The brushes are composed either of copper gauze or of 
 carbon blocks, and are held up against the commutator at an angle 
 by a holder fixed to the brush-rocker. The angle of brush adjustment 
 can be regulated by means of a pair of handles on the rocker, and 
 the brushes moved round the commutator circle more or less according 
 
♦ 
 
 Marine Electric Lighting 445 
 
 to what may be required to prevent sparking, &c. In some dynamos 
 the position of the brushes has to be altered according to the load on 
 the machine in order to get sparl<less collection of the current, but in 
 modern machines fitted with carbon brushes this is not necessary. 
 
 Small springs of low tension are often fitted to the brush-holders 
 to keep the brushes pressed gently against the surface of the com- 
 mutator. If the brushes press too tightly, they are apt to cause 
 uneven wear of the commutator, and consequent sparking. 
 
 The positive brush (or set of brushes) takes the current from the 
 dynamo and gives it to the main wires, and the negative brush (or set 
 of brushes) returns the current back into the dynamo after it has 
 travelled round the lamp circuits. 
 
 Armature Shaft. — One end of the armature shaft is coupled direct to 
 the driving engine shaft, and the other, or commutator end, runs in a 
 bearing cast on the bed-plate of the machine. This bearing is 
 generally of the enclosed type, and supplied with revolving oil rings 
 and oil bath which allow of constant lubrication. As the dynamo 
 usually runs at from 250 to 500 revolutions per minute, it is of the 
 greatest importance to have regular and reliable lubrication of the 
 end bearing, as will easily be understood from the foregoing. 
 
 Action of Dynamo. — The principle of action of a dynamo may be 
 described as follows : — As the armature, containing the copper con- 
 ductors or coils, revolves between the two poles of the magnets, it 
 cuts through the lines of force or magnetism which pass across from 
 one pole to the other, and as a result, currents travelling from end to 
 end are induced in the armature coils. The space in which the 
 armature revolves is called the magnetic field, and this field is 
 strengthened or excited by the magnets themselves, which are wound 
 with insulated copper wire through which current is passing, so that, 
 as more or less current passes round the magnets", more or less strength 
 is obtained in the "field," and consequently in the armature coils. In 
 a "shunt" dynamo, as lamps are switched in and more current is 
 taken from the armature, the E.M.F. falls, hence to get the same 
 voltage at full load as at no load it becomes necessary either to 
 increase the speed or the " field " strength. The latter is more con- 
 venient, and is accomplished by the addition of series coils, thus 
 " compounding " the machine. If more current is now taken from the 
 armature more passes through the series coils, thus increasing the field 
 strength, hence the voltage remains the same. On the other hand, 
 when lamps are switched off, the E.M.F. of the dynamo would in- 
 crease ; but this is prevented by the decrease in the strength of the 
 field due to less current passing through the series coils, the amount 
 passing through the shunt coils remaining the same in both cases. 
 For ship-lighting "over compound" dynamos are used, which give, 
 say, 100 volts at no load, and 105 volts at full load, the speed being 
 
446 
 
 Verbal " Notes and Sketches 
 
 the same in both cases. From this will be seen the reason why a 
 compound wound type of dynamo is best suited for ship-lighting 
 where a constant voltage is required. 
 
 Switchboard. — After the current is generated in the dynamo it 
 passes from the positive brushes and leads or cables to the switch- 
 
 TO DISTRIBUTION BOXES 
 
 •+- 
 
 ^ — FROM DISTRIBUTION 
 
 FUSE 
 
 two: POLE 
 SWITCH 
 
 _FROM 
 QYNAMO 
 
 + 
 
 FUSE 
 
 _T0 „ 
 DYNAMO 
 
 No. 14. — Diagram of Switchboard. 
 
 board, and from there i.s led away by smaller branch wires to the 
 distribution boxes and the various lamp circuits in connection. 
 
 The switchboard contains the switches or "circuit-breakers," fuses 
 or cut-outs, volt meter and ampere meter. 
 
 After the current has travelled from the switchboard through 
 the lamp circuits, it returns to the switchboard by the "negative" 
 cables or wires, and is returned again to the dynamo by the negative 
 brushes. 
 
No. 15 — G.E.C. Main Distribution Switchboard 
 
 mm, 
 
 
 % ^ 
 
 No. 16. — G.E.C. Main Switchboard 
 
 -117 
 
448 
 
 "Verbal" Notes and Sketches 
 
 Volt Meter. — The volt meter is an instrument for measuring the 
 electrical "tension" or pressure. It is connected between the positive 
 
 No. 17— G.E.C. Volt Meter. 
 
 No. 18. — "Stanley" Aperiodic Ammeter. 
 
 and negative wires, and therefore indicates the difference of 
 " potential " or pressure existing between them. A volt then, is the 
 unit of electrical pressure, or electro-motive force, as it is called. 
 
Marine Electric Liohtino; 
 
 449 
 
 Ampere Meter. — This instrument measures the amount or quantity 
 of current passing through the wires, and is generally connected 
 to the positive lead only. 
 
 If each lamp requires, sa)-, i ampere of current, and 65 lamps are 
 switched on, the ampere meter would then indicate 65 amperes fully, 
 allowing for the extra voltage required to overcome the resistance of 
 the wire. 
 
 From the foregoing it will be understood that if, say, 20 lamps 
 are switched on, and the volt meter is showing 70 volts, and the 
 ampere meter 22 amperes, if then 60 lamps are switched on, the 
 
 No. 19.— G.E.C "Witton" Main 
 Switch shown in "Off" 
 Position. 
 
 No. 20.— G.E.C. New Pattern 
 Flat Type Switch. A very 
 neat switch for use on 
 board ship. 
 
 ampere meter will now show a corresponding increase, but the volt 
 meter will remain the same as before, as, although the amount of 
 current required is now more, the pressure of the current is still the 
 same. 
 
 NOTE.— It should be noted that this only holds good when lamps are run on the 
 "parallel system," as is common in ship-lighting. 
 
 Main Switches. — Switches are employed to break the flow of the 
 current when opened, and to allow the current to flow when closed. 
 They are sometimes called " circuit-breakers." Switches may be of 
 the following types : — 
 
 1. Single pole, single break. 
 
 2. Single pole, double break. 
 
 3. Double pole, single break. 
 
 4. Double pole, double break. 
 
450 
 
 "Verbal" Notes and Sketches 
 
 A single-pole switch breaks the current at one pole or wire 
 (positive or negative), and if single break at one place only, if double 
 break at two places. 
 
 A double-pole switch breaks the current at both poles or wires, 
 positive and negative, at once, and if single break the current 
 is broken at one place only, but if double break the current is broken 
 at two places on each wire. The requirements of a good switch are 
 — (i) When "on" the contact is complete with ample surface; 
 (2) When " off" the circuit is absolutely broken, without any 
 possibility of a short circuit; (3) A sharp or quick "break" so that 
 sparking may be avoided. 
 
 Fuses or Cut-outs. — A cut-out or fuse may perhaps be described 
 as an automatic circuit-breaker. It consists, in most cases, of a strip 
 
 No. 22. — Fuse. 
 
 No. 21— G.E.C. " Ironclad " 
 Cut-out. 
 
 No. 23. — Cut out in Case. 
 
 of lead or tin, placed in line with the main wire, which is cut to allow 
 of the fuse being fitted in its place. The ends of the fuse are con- 
 nected to small terminals or screws. 
 
 Cut-outs are arranged so that should an excess of current (caused 
 by some defect or breakdown) attempt to pass, the strip of tin or lead 
 would melt and break the circuit automatically, thus preventing 
 further damage by burning out to the rest of the circuit beyond where 
 the cut-out is placed. Fuses are fitted on switchboards, distribution 
 boxes, and for general safety at various other places on the lamp 
 circuits. 
 
 Wiring. — The main wires divide on the back of the switchboard, and 
 branch pairs of wires, positive and negative, of smaller size, are led 
 off to the "distribution boxes" situated at different parts of the ship. 
 
Marine Electric Lio^hting 
 
 451 
 
 Each pair of wires is connected to a couple of brass bars in the 
 chstribution box, and from each bar a number of wires of still smaller 
 size are led away to supply the various lamp circuits in connection. 
 
 The incandescent lamps are placed betivcen each pair of wires, 
 positive and negative, so that every single pair of wires supply a 
 number of lamps, the current crossing from one wire (the positive) 
 through the lamps to the negative wire. This arrangement is what 
 is known as the " parallel system," the requirements of which are that 
 
 ..= NEGATIVE WIRE 
 
 DYNAMO 
 
 No. 24.—" Parallel " System of Lighting. 
 
 the voltage remains constant, but the number of amperes varies 
 according to the number of lamps switched into the circuit. 
 
 NOTE. — When the quantity of current passing through a conductor is one 
 coulcombe per second the strength of the current is said to be one ampere. This 
 then is taken as the current strength. 
 
 Single Wire System. 
 
 In this system of wiring the positive current is carried by a single 
 cable or wire to the lamps, and the return from the lamps is effected 
 by means of the metal of the ship, or, as it is called by electricians, 
 the return is " earthed." 
 
 The sketch shows clearly how the lamp connections are made, 
 the return wire being metallically connected to a stud screwed into 
 
452 
 
 "Verbal" Notes and Sketches 
 
Marine Electric Lighting 
 
 453 
 
454 " Verbal " Notes and Sketches 
 
 some part of the metal of the steamer. Observe that the dynamo 
 negative cable is secured by a large stud to the bulkhead plate, the 
 positive wire only going to the switchboard. 
 
 The advantages claimed for this arrangement are — 
 
 (i) Lower cost of installation. 
 
 (2) Less complication of wiring. 
 
 (3) Less trouble in locating faults in the circuit. 
 
 The disadvantages are — 
 
 (i) Greater danger of short circuits between lead and return. 
 
 (2) System only possesses half the insulation of the twin wire 
 installation. 
 
 (3) Supposed cause of corrosion in condensers or other places 
 due to galvanic action. 
 
 (4) More danger of lights going out suddenly in case of vessel 
 grounding or in collision. 
 
 (5) Troubles experienced by rusting going on at the ship 
 return lamp connections, owing to damp due to "sweating" of the 
 plates, &c. 
 
 It may be stated that the majority of new installations are of 
 the twin wire system, this being now considered the most reliable 
 method. 
 
 NOTE. — Sea water acts very injuriously on the insulation of wires and cables, 
 unless they are protected by metal piping or are "armoured." 
 
 Three- Wire System (see also page 649). — In some steamers 
 two dynamos are run together on what is called the three-wire 
 system. In this arrangement the positive wires of one dynamo are 
 connected to the negative wires of the other dynamo, and the central 
 or neutral wire acts as a common conductor for both. 
 
 The voltage is usually 220, but as this is divided between the two, 
 the working voltage for the circuits is only no volts. 
 
 The lamps are arranged so that the number of them is equally 
 divided between the two outside wires and the central one, to balance 
 each other and divide the current. If the same number of lamps are 
 run on each side, the middle wire will carry no current, but should 
 more lamps be switched in on one side than on the other, the 
 difference of current resulting will then be carried by the central 
 wire. 
 
 It should be noted that as the central wire has only to carry the 
 excess or difference between the two outside wires, it can be made 
 of less section, and is therefore of smaller size than the others. 
 
 In the three-wire system the main switches and cut-outs are 
 necessarily of the " three- pole " type. 
 
Marine Electric Lighting 
 
 455 
 
 Distribution Boxes. — The distribution boxes contain two brass bars, 
 positive and negative (called " omnibus bars "), to which each wire, 
 
 TERMINAL 
 
 OMNIBUS 
 BAR 
 
 DISTRIBUTION 
 BOX 
 LFUSE. 
 
 TERMINALS 
 
 TWO POLE 
 SWITCH 
 FROM 
 rNAMO ^ 
 
 TO DYNAMO 
 
 TO 
 LAMP CIRCUITS 
 
 FROM 
 
 LAMP ciRcunrs 
 
 No. 27.— Distribution Box and Connections. 
 
 positive and negative, from the switchboard is connected by screws 
 or terminals. From the two bars fuses are led to connect to a 
 
 No. 28 —Distribution Board in Cast- 
 iron Case for Motor Circuits. 
 
 number of smaller wires, each intended to lit^ht a certain section of 
 the steamer. These fuses are held in earthenware holders with 
 
456 
 
 Verbal " Notes and Sketches 
 
 copper contact pieces, and as tliey can be withdrawn at will by hand, 
 may therefore be made to act as "circuit-breakers" if required. 
 Suppose the main supply wire from the switchboard to the distribu- 
 tion box to carry, say, 15 amperes of current, then if the box has 
 three smaller wires led away to as many lamp circuits, each circuit 
 wire will have about 5 amperes of current to carry. In certain cases 
 pairs of wires from one box are led to other smaller boxes, where still 
 
 Copper 
 No. 29.— Distribution Box Fuse. 
 
 smaller wires, carrying less current in proportion, are connected up 
 to the lamp circuits. 
 
 A hand switch is usually fitted to the wires at the distribution 
 box, so that all current can be shut off from the set of wires leading 
 from it (Sketch No. 27). 
 
 Lamp Switches. — The variety of design in lamp switches is infinite, 
 and it will be sufficient to describe one or two of those most in use. 
 
 All switches, be it noted, whether large or small, fulfil the same 
 object, that is, to break the current or circuit when "off" and to 
 connect the circuit when " on." 
 
 No. 30.— Tumler or " Link " Switch. 
 
 The switch most commonly met with is undoubtedly that known 
 as the " tumler " or link type, and will be found in nearly all cabin and 
 state-room fittings. When the small round knob of the "tumler" 
 switch is pushed over, two small copper contact pieces are pressed 
 against the two corresponding wire terminals, and the current flows 
 across the bridge so formed to the lamp. A small spring acts on the 
 lever and keeps the contact strips in position. 
 
 Sometimes a small cut-out is also fitted inside the switch box, and 
 

 Marine Electric Liohting 
 
 457 
 
 fits in between two screw terminals on tlie main wire leading to the 
 switch. Should an excess of current come on the wire, the fuse would 
 burn out or melt before the excess of current reached the lamp in 
 connection with the switch. 
 
 Incandescent Lamps. 
 
 Incandescent carbon filament lamps are made of any candle- 
 power from 8 to 500. They are usually marked as so many candle- 
 power, as, for example, 16 c.p. or 32 c.p., &c. 
 
 The lamp consists of a brass neck piece or collar filled with 
 cement, into which are sealed two platinum wires. The wires connect 
 
 BAYONET 
 JOINT 
 
 PLATINUM 
 WIRE 
 
 CARBONIZED 
 THREAD 
 
 PIN 
 
 platinum 
 wire: 
 
 VACUUM 
 
 No. 31.— Incandescent Lamp. 
 
 by contact pieces to the lamp wires on the outside, and to a 
 carbonised cotton thread or filament inside the glass globe The 
 carbonised cotton thread is made in the form of a single or double 
 loop, so that the lighting effect may be intensified. In some cases 
 double filaments are fitted with the same object. The glass globe 
 is exhausted of air during manufacture, and the carbonised thread being 
 thus in a vacuum, does not burn away when heated to a white heat. 
 It should be noted that should air get into the globe, the thread would 
 burn away in a few seconds, owing to the supply of oxygen allowing 
 combustion to take place. The current in passing through the 
 carbonised thread raises it to a white heat by the resistance offered 
 to the current flow, and the " incandescence " resulting constitutes the 
 light. 
 
458 
 
 "Verbal" Notes and Sketches 
 
 The " life " of an incandescent lamp varies a great deal. Some last 
 looo hours, others less than this, and others again for indefinite 
 periods. 
 
 NOTE. —The "filament "or "thread" referred to is carbonised by being heated 
 in a vessel filled with the carbon gas of coal, the effect of which is to cause minute 
 particles of pure carbon to deposit on the thread until it is completely covered with a 
 fine skin of carbon. 
 
 NOTE 2. — Platinum is the only metal suitable for connecting the filament, owing to 
 the fact that it expands at the same rate as glass when heated, and thus keeps the 
 vacuum good. 
 
 Metallic filament lamps, however, are marked with number of 
 watts, in Osram lamps about i watt= i c.p. 
 
 W^OBertSOIL;^' 
 
 No. 32. 
 
 Osram metallic filament lamps are now rapidly becomirjg adopted 
 by the leading steamship lines. These lamps have hitherto been very 
 largely used for the lighting of buildings, offices, &c., but they were 
 not used for ship lighting when they were first brought out, owing to 
 the fact that they were rather fragile. They have now, however, been 
 considerably strengthened, and are eminently adapted for ship work. 
 
 The great advantage of using Osram metallic filament lamps is 
 that with an Osram lamp of 50/130 volts, it is possible to obtain 
 16 c.p. with a consumpt of 17 watts, compared with a 16 c.p. 
 carbon filament lamp which consumes 64 watts. This readily shows 
 the fact that there is a clear saving of 73 per cent, by using the 
 
Marine Electric Liohtino- 
 
 459 
 
 Osram lamps. This, of course, means that in many cases where 
 more hght is required in a vessel, it can be obtained by taking out 
 the carbon filament lamps and installing Osram metallic filament 
 lamps of a greater candle-power without increasing the size of the 
 plant (which in all probabilitx' is fully loaded with carbon filament 
 
 No. 34— Bayonet Joint. 
 
 No. 35- Section through Lamp- 
 holder, showing Spring 
 Contact. 
 
 lamps), and which would have to be increased if more carbon 
 filament lamps were added. 
 
 Again, with the Osram metallic filament lamp, it is possible to 
 obtain double the candle-power of the carbon filament lamp and still 
 effect a saving of 50 per cent, in current. 
 
 There is no doubt whatever that in the near future metallic 
 filament lamps will be universally adopted for ship lighting, which 
 
 No. 36.— Wall Plug for use in Cabins, &c., 
 for Fans, Cable Lamps, &c. 
 
 will mean that the installation can be put in at a considerably 
 decreased cost, as the plant would be considerably smaller and the 
 wiring throughout the vessel in proportion would be of a smaller size. 
 We illustrate a Robertson carbon filament and an Osram metallic 
 filament lamp. 
 
 Lampholder.— The neck of the lamp connects to the lampholdcr by 
 a bayonet j<3int. Two small brass contacts in the holder press down 
 
460 
 
 "Verbal" Notes and Sketches 
 
 against the contact strips or plates of the lamp to which the platinum 
 wires from the thread are attached. 
 
 The lamp wires are connected to the spring contacts of the 
 
 Contact 
 
 TER^MNAL 
 
 No. 37. — G.E.C Water-tight No. 38.— Lampholder Terminals 
 \A/"alI Plug, for use with and Spring Contacts. 
 
 Handlamps, Portables, &c. 
 
 lampholder by small screw terminals carefully insulated from each 
 other. Sometimes a switch is supplied inside the lampholder. 
 
 No. 39.— G.E.C. "Angold" Arc Lamp, for 
 Lighting of Decks and Holds. 
 
 Arc Lamps. — If a single wire carrying a current be cut and two 
 carbon pencils (one to each end of the cut wire) inserted in the gap, 
 the current will pass across from one carbon to the other, provided 
 the space or " arc " between them is not too great. In crossing over 
 
Marine Electric Liohtini 
 
 461 
 
 the space, Uglit is given out by the particles of carbon which pass 
 from one carbon (the positive) to the other (the negative) becoming 
 heated to a white heat. This is, roughl}', tiie principle of the well- 
 known arc lamp. It is important to note that before light can be 
 obtained the two carbon pencils must first touch, and then be drawn 
 
 POSITIVE- 
 
 -^ ^ 
 
 REGULATING 
 
 SERIES AND 
 
 SHUNT C0IL5 
 
 FOR CONTROLING 
 
 ARC 
 
 RETURN 
 
 FIXED J 
 GUIDE B/<!^~*i 
 
 NEGATIVE. 
 
 0~V-GUIDE BAR 
 
 ARC 
 
 No. 40.— Arc Lamp with Case and Globe removed. 
 
 away to the required distance from each other : this is termed 
 "striking the arc." The space between the carbons is usually from 
 I in. to |- in., depending on the amount of current supplying the 
 lamp. The upper carbon is the positive one, from which the current 
 passes to the lower or negative one. The mechanism of an arc lamp 
 has to perform the following functions : — 
 3^ 
 
462 
 
 "Verbal" Notes and Sketches 
 
 I On the current beinc^ switched on, to " strike the arc." 
 
 2. After the arc is struck, to maintain the carbons at the proper 
 
 distance apart. , . ,, / .1 • n 
 
 ■z If two or more lamps are run m "series' (on the same wire), 
 to allow the current to pass to the other lamps if anything goes 
 wrong. 
 
 SHUNT COIL 
 
 SERIES COIL 
 
 REGULATING GEAR 
 
 RESISTANCE 
 
 TOP CARBON 
 -BOTTOM CARBON 
 
 No. 41.— G.EC. Type Arc Lamp. 
 
 The gear for regulating the arc varies a great deal in design, 
 different makers having different methods. The general principle, 
 however, is as follows : — . 
 
 Two small bobbins wound with wire, one being of coarser (seriesj 
 wire than the other (shunt), are arranged so as to form electro- 
 magnets. When a current flows through the shunt wires, the 
 magnetism resulting attracts a piece of metal or lever placed in 
 
Marine Electric Lighting 463 
 
 connection with the small wheel and chain attached to the carbon- 
 holders. The chain and wheel act so that as one carbon is raised 
 the other is lowered, thus keeping the focus or arc always in the 
 same place. 
 
 When the current is flowing from the positive carbon down to 
 the negative one, and the space between them is properly adjusted, 
 the coarse or scries wire carries the current ; but if the space becomes 
 too great, then as the resistance to the current passing across is now 
 increased, less passes through the series wire and more through the 
 fine or shunt wire, and the magnetism resulting attracts the lever in 
 connection with the chain gear, which being set in motion, draws the 
 carbons together until the balance is restored. When the lamp is 
 first switched on, the current momentarily passes through the shunt 
 wires, and the effect of this is to draw quickly together the two 
 carbons, thus striking the arc. After the connection is made in this 
 way, most of the current then passes through the series coils and 
 the carbons, weakening the shunt in proportion, so that the arc 
 is correctly set. Nearly all patent arc lamps are worked on this 
 system, called the "differential," owing to the difference in the series 
 and shunt bobbins. Put briefly, then, when the carbon pencils are 
 at the proper "arc," most of the current passes through the series 
 coils; but if the arc lengthens owing to the consumption of the 
 carbons, less current passes through the series coils and more through 
 the shunt coils, and the shunt coils attracting a magnet, set in motion 
 the clockwork gear which draws the carbons together again until the 
 proper arc is established. 
 
 An automatic cut-out and substitutional resistance is usually 
 provided in case the lamp fails to act. 
 
 The upper or positive carbon burns away about twice as fast as 
 the negative one, and becomes slightly hollowed at the lower end, 
 whereas the negative carbon assumes in time a pointed or conical 
 shape. The carbon pencils only last from six to ten hours, after 
 which they require to be renewed, unless in the case of enclosed arc 
 lamps, the carbons of which last for a much longer period. 
 
 Arc lamps are generally run at about 50 volts, and require from 
 8 to 10 amperes of current per lamp. 
 
 Projector. — The Suez Canal Regulations require each steamer 
 passing through in the night time to be supplied with a strong 
 projector or searchlight. The projector consists of a cylindrical 
 casing hung on movable trunnions, and containing inside the 
 necessarry mirror, lenses, carbons, and adjusting gear. 
 
 The regulation of the arc is in most cases obtained by the hand- 
 feed arrangement, the carbon pencils being held in two brackets 
 screwed on to a right and left hand threaded spindle. By means of 
 small handwheels the arc can be focussed and adjusted as required. 
 As in the case of other single arc lamps, a " resistance " is also 
 employed to reduce the voltage, and obtain a steady light. The 
 
464 
 
 Verbal " Notes and Sketches 
 
 amount of current required for the projector is very high, as much as 
 from 100 to 150 amperes being sometimes necessary, although the 
 voltage may only be from 50 to 60. 
 
 The wire from the dynamo runs to a terminal box near the 
 position required for the projector, and from the box the wire is led 
 direct to the lamp. The positive terminal is marked with a + sign, 
 and the negative with a — sign. 
 
 No. 42.— G.E.C. Projector. 
 
 A fuse and switch are often fitted in the terminal box for greater 
 
 safety. 
 
 Description of G.E.C. Projector. 
 
 The case and pedestal is made of light sheet steel with copper 
 protection guards and sight holes fitted with blue glass for examining 
 the arc. The side standards, trunnions, lamp box, and back frame 
 door, and frame in front working head, and all exposed parts are made 
 of gun metal highly finished, polished, and lacquered. The vertical 
 and horizontal movements are obtained by gearing worked by hand- 
 wheels, but arranged so that, if desired, the gear can be thrown out and 
 the projector left free to be moved by the handles fitted on the frame 
 at the back. The hand feed lamp is of special construction and fitted 
 
I 
 
 Marine Electric Lighting 
 
 465 
 
 with vertical focusing gear. The feed motion is worked by bevel 
 wheels from the outside of the lamp box, the carbons being moved 
 together by a left and right hand screw. The horizontal focusing gear 
 
 No. 43— G.EC. Type Projector. 
 
 is worked by a screw passing through the lamp box fitted with hand- 
 wheel at side and end of box. The projector can also be fitted with 
 automatic feeding- gear if required. A resistance is placed in the 
 circuit to reduce the voltage to suit arc voltage, and this also ensures 
 steadier working. 
 
 
 % 'j'*tyt«tyt«t*tytit»t't't 't'*' 
 
 ^1 
 
 No. 44.— Resistance Coil. 
 
 Resistance Coils. — Single arc lamps are often fitted forward and aft, 
 and for these the current is led from the switchboard by separate wires 
 
466 
 
 Verbal " Notes and Sketches 
 
 to a " resistance coil," where the voltage is reduced to suit that 
 required by the lamp. After passing through the resistance coil the 
 current enters the carbons of the lamp at the reduced voltage. 
 
 FROW DYNAMO 
 70 VOLTS ~ 
 
 TO LAMP 
 55 VOLTS 
 
 J 
 
 RESISTANCE COILS 
 
 5INGLE ARC LAMP 
 
 No. 45.— Arc Lamp and Resistance. 
 
 The resistance coil for single arc lamps consists of a metal box 
 or case containing coils of fine platinoid wire, arranged either in 
 vertical rows or wound on a cylinder. If two or more coils are fitted, 
 they are connected "in series," that is, the end of one coil is joined 
 to the end of the next, and so on. The current in passing through 
 the coils is lowered in voltage, as the resistance of the platinoid wire 
 is much more than that of copper wire. 
 
 ^ NEGATIVE ^ 
 
 100 VOLTS -^ 
 FROM DYNAMO 
 
 50 VOLTS 
 
 ^oT 
 
 50 VOLTS 
 
 No. 46.— Two Arc Lamps "in Series." 
 
 As work is done by the wire resistance referred to, heating up 
 of the coils and box ensues, and to allow for this the case should 
 be made of fireproof material to prevent damage from overheating. 
 As before stated, arc lamps are usually run at about 50 volts, and this 
 being so, if the dynamo runs at 100 volts, as is sometimes the case, 
 then two arc lamps can be run " in series," that is, on the same wire, 
 
i 
 
 Marine Electric Lii^hting 
 
 467 
 
 each one receiving 50 volts. If the dynamo, however, only runs 
 at, say, 70 volts, then the arc lamps must be run singly, and a 
 resistance em[)loyed to dissipate about 15 volts, so that the lamps 
 may each receive no more tlian 55 volts. This tends towards 
 steadiness in the light. 
 
 Testing for Faults. — Testing can be done by means of a 
 "detector" formed of a magnetic needle and galvanic battery, or 
 by a small portable hand lamp with a length of wire connected 
 to each of its terminals. When using the hand lamp the ends of 
 the copper wires must be carefully stripped of insulation so that 
 the copper is bared. 
 
 The detector can be used in most cases when the dynamo is 
 stopped, but the lamp can only be used when the dynamo is running. 
 
 No. 47. — Detector. 
 
 The detector is supplied with a battery, so that a current will flow 
 through it and deflect the needle whenever the positive and negative 
 poles of the dynamo or wires to be tested are connected up to the 
 terminals of the detector. 
 
 In the case of the portable lamp, a current must first be sent 
 through the wires, &c., when the ends of the lamp wires are put m 
 contact with the positive and negative connections under test, before 
 the light will show in the lamp. 
 
 NOTE. — A " short circuit " is a connection (usually metallic) between any positive 
 and negative part of the dynamo connections, or between any two of the wires. An 
 " earth " is a metallic connection between one of the poles of the dynamo or wires to 
 the metal of the ship's plates. 
 
 Break in Main Wires. — To discover the position of a break in a 
 pair of wires, begin from the source of the current in question or 
 distribution box from which the wires branch off, and baring the two 
 wires at short distances, touch them both with the free ends of the 
 wires connected to the detector. If the needle deflects, a current is 
 passing at the point tested ; but if after repeating this a few times the 
 
468 
 
 " Verbal " Notes and Sketches 
 
 needle does not deflect at a point further on, it indicates that a break 
 is situated somewhere between this point and the last place where the 
 needle deflected. 
 
 No. 48.— Broken Wire Test by Detector. 
 
 The wires will therefore require to be carefully examined between 
 the two places referred to for the location of the break. 
 
 The portable lamp will do equally well as the detector, only in 
 
 MAIN WIRE 
 
 No. 49.— Broken Wire Test by Lamp. 
 
 this case the dynamo must be run to obtain a light in the lamp when 
 the bared ends of the lamp wires are put in contact with the wires 
 under test. If at a certain point no light shows in the lamp, it 
 indicates a break in the current or circuit. 
 
 NOTE. — The switches of the circuit in question must be "on" when testing with 
 the detector. 
 
 Leak in Magnet Coils. — To test if leakage is occurring between the 
 magnet coils and magnet, connect one of the detector wires to the 
 end of the coil to be tested, and after carefully cleaning and polishing 
 up a small part of the metal work of the magnet, put the end of the 
 other detector wire in close contact with it. If the needle deflects, it 
 
Marine Electric Liohtino- 
 
 469 
 
 indicates a leak between that particular coil and the core of the 
 magnet : if no deflection of the needle takes place, it proves the 
 insulation to be intact. Each coil will require to be tested in turn. 
 
 No. 50.— Test for Leakage between Coils and Magnet. 
 
 Leak between Armature Coils or Commutator and Armature 
 Drum. — Take out the armature and support it on a pair of trestles, 
 place one detector wire on the armature shaft or drum (either will do) 
 
 B_S^, 
 
 
 f — 
 
 1 
 
 X; 
 
 
 
 
 
 
 
 No. 51 —Test for Leakage between Armature Coils and Drum. 
 
 and with the other wire touch the commutator bars as the armature 
 is slowly turned round. If the needle deflects it indicates a short 
 circuit between the armature coils or commutator bars and the drum. 
 
470 
 
 " Verbal " Notes and Sketches 
 
 Short Circuit in Brush-holders. — Lift the brushes from the com- 
 mutator and disconnect them from the cables leading to the dynamo 
 terminals, then place one detector wire on one brush-holder, and the 
 
 No. 52.— Test for Short Circuit between Brush-holders. 
 
 other detector wire on the other brush-holder. If the needle deflects, 
 a current is passing indicating a short circuit. Each part of the brush 
 connections can be tested in the same manner. 
 
 No. 53. — Test for Broken Wire (Continuity Test). 
 
Marine Electric Liebtine 
 
 471 
 
 Test for Broken Wire. — Disconnect the wire to be tested so that 
 the ends are free, and place one detector wire to each end. If the 
 needle deflects, a current is passing, and the wire is not broken ; but 
 if the detector needle remains stationary, it indicates that the wire in 
 question is broken, as the circuit is not complete. 
 
 Test for "Earth" Leakage. — With the main and lamp switches 
 " on," connect one detector wire to the positive and negative wire of 
 the dynamo in turn, and put the other detector wire in contact with 
 the floor plates or ship's skin as the case may be. If a deflection of 
 the needle occurs, it indicates that leakage to " earth " is taking place, 
 that is, at some part of the circuit one of the wires is in bs.re contact 
 with the metal of the ship, and the current is returning to the dynamo 
 by that path. 
 
 To locate the part of the circuit affected, switch off the main 
 switches one by one till the needle comes back to its zero position, 
 
 No. 54.— Test for "Earth" Leakage. 
 
 and the last switch opened will be that of the circuit affected. Now 
 connect one of the detector wires to one of the " bus " bars or terminals 
 of the distribution box of the circuit, and, as before, connect the other 
 detector wire to the ship's metal. If the positive and negative fuse 
 bridges in the box are now pulled out one by one, the needle will 
 only move back to zero when the fuse bridge of the " earthed " wire 
 is disconnected, and in this way the exact " earthed " wire can be 
 located. 
 
 Another method of carrying out this test, should a galvanometer 
 not be available, is to connect up a lamp, the lamp being of the same 
 voltage as the dynamo. In this case it is necessary to have the 
 dynamo running and to test both negative and positive sides of the 
 leads, as the lamp only lights up when there is a fault on the opposite 
 pole to that to which it is connected. For instance, should there be 
 a fault on the positive lead to a lamp, when the test lamp is con- 
 
472 
 
 "Verbal' Notes and Sketches 
 
 nected to the negative wire it will light up, but if connected to the 
 positive it would remain black. 
 
 5HIP (EARTH) 
 
 No. 55. — Earth Lamp Test. 
 
 " Earth " Lamp Test. — To test for an earth leakage arrange a pair 
 of lamps as shown in the sketch, one connected to the positive lead, 
 
 No. 56 —Short Circuit Test. 
 
 the other to the negative lead, and both connected to the ship metal 
 by a cross wire. 
 
M 
 
 iriiic 
 
 Kl 
 
 'JtTtnc 
 
 'htiin 
 
 473 
 
 With the dynamo runiiiiij:^' one of the lamps will burn brighter 
 than the other if there is a leakage to earth, and the leak will be on 
 the opposite wire to that of the bright lamp. For example, if lamp 
 A burns brightest the leakage will be on the positive wire, but if 
 lamp B burns brightest then the fault is on the negative or return wire. 
 
 To Test for Short Circuit in Main Wires. — Disconnect one of 
 the main wires from the dynamo terminal, and insert between the wire 
 .md terminal the detector, as shown. Now switch off the lamps (not 
 the main switches), and run the dynamo. If a deflection of the needle 
 takes place it indicates a short circuit between the main wires, as with 
 the lamp switched off no current should then be passing. 
 
 To Test for Broken Armature Coil. — This can only be accurately 
 determined by the following method : — Disconnect both ends of each 
 
 I 
 
 l=Lt 
 
 [NO OF COIL 
 
 i 
 
 No. 57. — Test for Broken Armature Coil. 
 
 armature conductor from the commutator bars, and place one wire of 
 the detector to each end ; then if no deflection of the needle takes 
 place it indicates a broken wire : a deflection proves the wire to 
 be continuous or unbroken. Each armature coil must be tested 
 separately. 
 
 To Test for Polarity of Dynamo. — It is often very convenient to 
 know which is the positive and which the negative connections or 
 wires of a dynamo, and these can be located as follows : — 
 
 Obtain a piece of "pole-finding" paper (procurable at any Electrical 
 Supply Stores), and after moistening the paper place it on a piece of 
 dry wood ; now lead a suitable length of wire from each dynamo 
 terminal, as shown in the sketch, and with the free ends of the wires 
 touch the wetted "pole-finding" paper. A red coloured blot will then 
 
474 
 
 " Verbal " Notes and Sketches 
 
 TEST^ 
 WIRES 
 
 
 
 
 -1 
 
 POLE FINDING 
 
 
 1 1 
 
 PAPER 
 
 
 WOOD 
 
 No. 58.— Polarity Test. 
 
 appear on the paper at the wire connected to the negative terminal ; 
 the other will of course be the positive connection. 
 
 Hints on Running. — In the case of a new dynamo it is advisable 
 to run the machine for a couple of hours or so with the brushes 
 lifted from the commutator, as a test of the mechanical balance, 
 lubrication, &c. 
 
 The armature, commutator, and field magnets should be kept 
 absolutely free of dust, grit, oil, or moisture, as these allow of the 
 formation of short circuits. 
 
 The commutator should be supplied with the least avioiint of 
 lubrication possible, and that only of vaseline or mineral oil. 
 
 A commutator in good working condition presents a surface 
 covered with an even bronze glaze or skin, and this should be main- 
 tained if at all possible. 
 
 The brushes should be placed at exactly opposite positions on the 
 commutator circle (mathematically opposite). 
 
 It is safest to first get the speed up on the dynamo, and the 
 proper voltage showing on the voltmeter, before switching in the 
 lights. 
 
 Examine the armature conductors to see that the commutator 
 
Marine Electric Lighting 475 
 
 ends of the wires are not bent and in contact with each other, as this 
 will produce a short circuit. 
 
 Keep all small tools away from the dynamo, as the mat^netic 
 attraction may draw them into the field space and result in serious 
 damage. 
 
 Brass or copper oil cans only should be used. 
 
 To test the armature balance, lift it out and place the shaft on t\Vo 
 fine levelled knife edges ; if the armature is then gently rolled from 
 side to side it will come to rest with the heavy side down ; this side 
 should therefore be reduced in weight, or the other side increased 
 in weight. 
 
 Short circuits in the armature coils show either by burning of the 
 insulating material resulting in a strong smell, or merely by heating 
 up of certain coils when felt by hand immediately after stopping 
 the dynamo. 
 
 If a commutator develops an untrue surface or "flats," it should 
 be turned up with a diamond-nosed tool, as this type of tool prevents 
 the burring of the copper edges over the insulation. 
 
 Make sure that the binding terminals are screwed up and in 
 metallic contact. 
 
 If the dynamo has become demagnetised it will refuse to generate 
 current when the speed is up. To remedy this, either tap the field 
 magnets with a light hammer, or, if this fails, reverse the brushes, that 
 is, turn them round 180 degrees of the commutator circle (if a two-pole 
 machine), so that they change places with each other, and run the 
 machine for a short period with reversed current ; this tends to restore 
 the magnetic conditions : afterwards replace the brushes to their 
 original positions. 
 
 Excessive rise of temperature in fields or armature Indicates a short 
 circuit between some of the wires. 
 
 A short circuit or earth leak may result in overloading the dynamo 
 and produce sparking at the brushes. 
 
 In place of the ordinary galvanometer or detector a small bell and 
 dry battery may be used for testing. When the circuit is completed 
 by the wires from the bell terminals the bell will ring. 
 
 Whenever possible slow down and stop the dynamo before switch- 
 ing off the lights, as this prolongs the life of the incandescent lamps. 
 
 Before starting up the dynamo be sure that the lubrication is 
 reliable and the oil cups filled up ; also that the armature shaft is clear. 
 
476 " Verbal " Notes and Sketches 
 
 The brushes should not be lifted from the commutator while the 
 dynamo is running, as this produces destructive sparking. 
 
 Sand-paper only should be used to polish up the commutator 
 surface, and it should be applied by means of a board on which the 
 sand-paper is pasted, the width of the board to be cut to the length 
 of the commutator bars. 
 
 Hold the sand-paper board against the commutator, and have the 
 armature shaft revolved by hand. This is best done with the 
 armature lifted out and laid on a pair of wood trestles. 
 
 At intervals feel by hand the temperature of the magnet coils. 
 
 It is important to see that the engine is not started to run in the 
 wrong direction, that is, against the brushes, as damage would result. 
 
 The brush position, when the machine is running without load, will 
 not be suitable when the load is on, and the brushes must then be 
 rocked forward to obtain a sparkless contact. 
 
 NOTE. — " Forward" means in the direction of rotation. 
 
 In polishing up the commutator in position, take care to lift Uf 
 the brushes clear of the commutator surface. 
 
 The voltage of the dynamo varies in proportion to the speed 
 of the machine. 
 
 If a fuse blows or burns out it should be replaced by one of the 
 same size, and not by a larger one as is sometimes done. 
 
 Copper gauze brushes should be kept well trimmed up and free 
 of ragged edges. 
 
 Violent sparking at the commutator may be caused by a broken 
 armature coil, or broken armature and commutator connection. 
 
 The " pilot " lamp serves as a guide to the voltage of the dynamo, 
 as, being connected direct to the dynamo terminals, it indicates 
 whether the machine is generating the required E.M.F. or not. If 
 therefore a fault appears on a section of the lighting circuit and the 
 pilot lamp of the dynamo is still burning brightly, it proves that the 
 fault is not in the machine, but must be in the wiring or lamps. If 
 the speed is too high this may show in the pilot lamp by possible 
 burning out, and if too low, by the lamp only glowing instead of being 
 at a white heat. 
 
 Engine-room " waste " should never be used on a dynamo, as the 
 loose fibres are apt to detach and lodge between the commutator bars 
 or armature coils, and ultimately bring about short circuits. A linen 
 cloth is much to be preferred. 
 
 I 
 
Marine Electric Lightijig 
 
 477 
 
 No. 59.— Pilot Lamp. 
 
 Become acquainted with the usual temperatures of the machine at 
 different parts when running, so that any abnormal rise of temperature 
 may be noticed at once, and the cause located. 
 
 When lifted out of the bearings the armature should be laid on a 
 pair of wood trestles as mentioned elsewhere, or if laid on the floor 
 should rest on sacking or some such soft material, as, being a delicate 
 piece of work, it easily becomes damaged. 
 
 B}' careful adjustment of the brush rocker the best position of the 
 brushes can be found, and this should give a practically sparkless 
 contact. 
 
 See that the brushes have no side-play in the holders. 
 
 The point or toe of copper gauze brushes should be cut to an angle 
 of about 40°. 
 
 Apply the necessary lubrication to the commutator either by the 
 palm of the hand or by means of a piece of linen rag, arud remember 
 that a very small amount of mineral oil is sufficient. 
 
 If the armature is much out of balance it will probably injure both 
 the commutator and the brushes. 
 
478 " Verbal " Notes and Sketches 
 
 The disadvantage of carbon brushes is a tendency to heat up if not 
 accurately adjusted, as, for example, by excessive compression on the 
 holder springs. 
 
 If tlie dynamo is situated in a part of the steamer where the tem- 
 perature is high (say 100°), sparking will ensue at the brushes and 
 commutator, owing to the increased resistance due to heating. 
 
 If the d)'namo is placed near the condenser corrosion of the tubes 
 may result, due, it may be supposed, to galvanic action. This has 
 occurred in several cases which have come under the writer's 
 observation. 
 
 When the brushes become ragged at the bearing edges, they can 
 be quickly repaired by cutting off the rough parts with a knife run 
 along a straight-edge, a cut also being taken off the corners at an 
 angle. 
 
 Jointing of Wires. — In joint making the following materials are 
 required, all of which are obtainable at Electrical Supply Stores : — 
 
 1. Solder sticks. 
 
 2. Resin. 
 
 3. Pure rubber strip or tape. 
 
 4. Rubber solution (Challerton's compound is one of the best). 
 
 5. Prepared tape. 
 
 6. Shellac varnish. 
 
 7. Emery cloth. 
 
 8. Fine copper wire (for binding). 
 
 The number of separate layers of rubber tape and solution depend 
 on the thickness of the insulation originally on the wire, the heavier 
 the insulation the greater the number of layers, and vice versa, 
 
 COPPER 
 RUBBER 
 SOLUTION 
 
 RUBBER 
 
 SOLUTION 
 
 OUTER COVERING 
 VARNISH 
 
 No. 60.— Section through Main Wire- 
 In lapping the rubber tape over the soldered part of the joint, only 
 
 carry it up to the ends of the rubber on the wires, and not beyond this 
 
 point. 
 
 Before applying the first lapping of rubber strip, file up all rough 
 
 edges of solder or of wire so that a smooth-jointed surface is 
 
 obtained. 
 
Marine Electric Lighting- 
 
 479 
 
 In cutting tiie ends of wires previous to jointing, it is advisable to 
 take off each layer of insulation in steps, as shown in the sketches. 
 This allows of the covering of the jointed part fitting in better with 
 the original layers of insulation. 
 
 Before applying the insulation layers, the rubber ends should be 
 cut down to form a taper to the bare wire, as shown in the sketch. 
 The lapping of the rubber strip over this ensures closeness of joint. 
 
 RUBBER 
 TAPERED 
 
 No. 6i. — Tapering of Insulation. 
 
 To cause adhesion the solution must be applied between each 
 layer of rubber strip, and last of all a good coating of shellac varnish. 
 
 The following instructions as to jointing of wires are issued by 
 Messrs Scott & Mountain, Electrical Engineers, Newcastle-on-Tyne : — 
 
 Main Cables. 
 
 Preparing Ends.— Remove the two outside tapes for about 5 in. 
 from each of the ends intended to be jointed. Bare the conductor 
 of its covering of indiarubber and inside lapping of tape for about 
 i^ in., and clean the wires with emery cloth. 
 
 Metal Joint. — Solder together the wires composing the strand for 
 about I in., and scarf two ends with a fine file. Bring the two scarfed 
 ends together and solder them. If this is carefully done, the conductor 
 will be of uniform size. Over the joint bind spirally a fine copper 
 wire, and solder the whole together. Resin, and not acid, must always 
 be used for soldering. 
 
 BINDING I WIRE 
 
 No. 62.— Scarfed Joint. 
 
 Insulating Joint. — Taper each end of insulation with a sharp jointer's 
 knife for ih in. from the conductor to the outside of the indiarubber. 
 Cover the metal joint with one lap of i-in. broad indiarubber, coated 
 with cotton tape. Over the cotton tape lap spirally pure indiarubber 
 strip (i in. broad), stretching it at the same time, and building up the 
 joint, by a series of coverings in alternate directions, to the same size 
 as the indiarubber coating of the wire, or slightly larger, to allow for 
 the thickness of binding wire. A very small portion of indiarubber 
 
480 "Verbal" Notes and Sketches 
 
 solution should be applied over each coat, and sufficient time allowed 
 for the spirit to evaporate before putting on another coat ; this will 
 cause the indiarubber strips to unite together. 
 
 BINDING 1 WIRE 
 
 No. 63.— Joints for Heavy Wires. 
 
 Outer Protection. — Two coverings of prepared tapes (i| in. broad) 
 are to be laid on in opposite directions, with strong shellac varnish 
 between them, and then, outside, another covering of waterproof tape, 
 and finally varnished over all. 
 
 Branch Wires. 
 
 Preparing Ends. — Remove the braiding tape and indiarubber for 
 about 4 in. from each end intended to be jointed. Unlap the cotton 
 serving next the conductor for about i| in. (do not cut it ofQ. 
 
 Metal Joint. — Thoroughly clean the ends of the wire with fine emery 
 cloth, and scarf them with a fine file. Bring the two scarfed ends 
 together and solder them. If this is carefully done the conductor will 
 be of uniform size. Over the joint bind spirally a fine copper wire, 
 and solder the whole together. Resin, and not acid, must always 
 be used for soldering. 
 
 Insulating Joint. — Cover the metal joint evenly and as thinly as 
 possible with the cotton which had been previously unwound from 
 the ends. Over the cotton covering lap spirally pure indiarubber 
 tape (i in. broad), stretching it at the same time, and building up the 
 joint by a series of coverings in alternate directions, to the same size 
 as the indiarubber covering of the wire, or slightly larger, to allow 
 for the thickness of binding wire. A very small portion of indiarubber 
 
 /~l]j^^^g^:^^^g^^^s^=<~17 
 
 No. 64.— Joint for Small Lamp Wires. 
 
 solution should be applied over each coat, and sufficient time allowed 
 for the spirit to evaporate before putting on another coat ; this will 
 cause the indiarubber to unite together. 
 
 Outer Protection. — Two coverings of felt tape (J- in. broad) are to be 
 laid on, in opposite directions, with strong shellac varnish between 
 them, and finally varnished over all. 
 
Marine Electric Lighting 
 
 481 
 
 " T " Joints. 
 
 Preparing Ends. — Remove the two outside tapes for about 5 in. from 
 the main lead. Bare the conductor of its covering of indiarubber and 
 
 LIJi 
 
 m 
 
 d J 
 
 \r 
 
 No. 65— Small "T" Joint. 
 
 . No. 66.— "T" Joint 
 
 inside lapping of tape i| in. Remove the braiding and tape for 6 in. 
 from the end of the wire intended to be jointed to the main lead. 
 The two rubber coverings and cotton serving are then to be unlapped 
 for 3 in. and the rubber cut off. Thoroughly clean the strand, and 
 also the solid wire with fine emery cloth. 
 
 Metal Joint. — Solder the wires composing the strand together, take 
 two or three turns of the solid wire round the main conductor, and 
 back round itself for three or more turns, and solder only at the top 
 of the T. Resin, and not acid, must always be used for soldering. 
 
 NOTE.— In joint making care must be taken to keep the hands, tools, and 
 materials clean and dry. 
 
 Electric Motors. 
 
 The construction of a motor is similar to that of a dynamo — all 
 the various parts, such as armature, magnets, commutator, brushes, 
 &c., corresponding to the latter ; but in the case of shunt motors 
 a difference exists in the wire connections, which will be explained 
 later. 
 
 As will readily be understood, a motor receives current from a 
 
482 
 
 " Verbal " Notes and Sketches 
 
 dynamo, and the action is reversed, that is, in place of mechanical 
 power generating electro-motive force, electro-motive force generates 
 
 c 
 o 
 
 u 
 
 0) 
 
 c 
 c 
 o 
 U 
 
 a 
 o 
 S 
 
 a 
 Q 
 
 o 
 6 
 
 mechanical power. Put simply, a motor is a dynamo reversed in 
 its action. Sketch No. 6y illustrates the principle of a dynamo with 
 motors in connection. 
 
Marine Electric Lighting 483 
 
 In numbers of motors in use at present, tlie various parts are so 
 fitted as to occupy very little space and to allow of the working parts 
 of the motor being covered in or enclosed. This protects the delicate 
 parts of the motor such as commutator, brushes, &c., from dirt and 
 grit, and reduces the chances of breakdown occasioned by short 
 circuits formed possibly by the dirt and grit in question. In this 
 type of enclosed motor, four poles are often used instead of two, 
 as being more suitable, as the four-pole arrangement lends itself better 
 to the circular shape of the motor. 
 
 As stated before, in shunt motors an extra wire is fitted. The 
 wire referred to is employed in the starting and stopping of the motor, 
 and is connected between the field magnets and the supply wire 
 through a " starting resistance " or switch. 
 
 On switching on the current at the starter it first enters the field 
 magnet coils, and after freely exciting them, is then admitted 
 gradually to the brushes and armature coils. The object of this is to 
 prevent what may be called " racing " of the motor when the current 
 is first turned on, as by first passing the current into the magnet coils 
 the magnetic field is strengthened, and the tendency of the armature 
 to run off at a high speed is checked by the magnetism developed 
 opposing its too rapid rotation. This prevents mechanical shock, and 
 possible damage to the working parts ; it also checks undue variation 
 in the current passing through the wires and supplying other motors 
 or lamps in connection, and which might otherwise be affected. 
 
 In a series wound motor the whole of the current entering the 
 armature first passes through the field magnets, and gives the necessary 
 strength to the field. 
 
 In a shunt wound motor only part of the current passes through 
 the magnet coils by the fine shunt wires which are branched off from 
 the main or supply wire. 
 
 This being the case, it will be obvious that with a shunt motor the 
 starting resistance must first freely excite the field magnets before the 
 current enters the armature, otherwise by suddenly switching on the 
 current the machine may be seriously damaged. It is also important 
 that the current be only admitted to the armature by small degrees, 
 and this is arranged for by fitting a " starting resistance " between the 
 motor and supply wire. 
 
 Motor Starters. — A "starting resistance" consists of a box con- 
 taining a number of platinoid wire coils connected together in series 
 and to insulated earthenware bases. 
 
 Each coil has a brass or copper contact piece, and the hand lever, 
 which is in connection at one end with the supply wire and to the 
 contact stops at the other, can be moved over the coils in succession, 
 so that at first all the coils arc in series ; but as the handle moves 
 over each stop in rotation, one less coil is included in the circuit, and 
 the resistance decreased in proportion. When the handle passes the 
 last contact stojD, all the resistances are cut out, and the full current 
 
484 
 
 "Verbal" Notes and Sketches 
 
 FROM ARMATURE AND FIELD 
 
 MOTOR 
 STARTER 
 
 ENCLOSED MOTOR 
 No. 68.— Motor Starter Connections ("Series Wound") 
 
 TWO POLE 
 "SWITCH 
 
 FROM ARMATURE 
 
 
 
 
 4 
 
 1 
 
 1 
 
 ' - 
 
 ••••• ; 
 
 t 
 
 V--,.^^^ 
 
 •• 
 
 1 
 
 1 
 
 ^f) 
 
 ^ ^ 
 
 L. 
 
 * *< -- - 
 
 ■N-'r 
 
 . 
 
 ~ ^. 
 
 : 
 
 X 
 
 TO ARr^ATURE 
 
 -TO FIELD 
 MAGNETS 
 
 MOTOR 
 STARTER 
 
 TO FIELD 
 n AG NETS 
 
 ENCLOSED MOTOR 
 No. 69.— Motor Starter Connections ("Shunt Wound"). 
 
\ 
 
 Marine Electric Lighting 
 
 485 
 
 is then passing direct from the supply wire to the armature. The 
 starting handle should be moved slowly over the contacts, and allowed 
 
 No. 70. — "Resistance" Regulator. 
 
 to press on each for a few seconds, as the speed of the motor gradually 
 increases. 
 
 In stopping a motor the same precautions must be used, that 
 is, the current must be switched off gradually by moving the 
 resistance handle from stop to stop with an interval for each, so 
 that each coil is inserted in rotation until the lever is in the " off" 
 position. 
 
 The speed of the motor can also be regulated by the insertion of 
 more or less of the resistance coils into the supply circuit by means of 
 the handle and contact stops. 
 
 Some motor starters have small electro-magnets or bobbins 
 arranged so that the lever is held in the " on " position so long as the 
 proper amount of current is passing, but should anything happen to 
 destroy the balance by excess or loss of current, the lever automatically 
 flies over to the " off" position and cuts off the current altogether. 
 
 Small fan motors, as used for state-rooms, &c., are usually of the 
 series wound type ; and larger f^ins, for ventilation or induced draught 
 purposes, of the shunt wound type. 
 
486 
 
 Verbal " Notes and Sketches 
 
 No. 71.— Type ofG.E.C "Freezor" Cabin Fan for Table 
 or as Bracket Fan. These Fans are fitted with 
 Three-speed Regulators in Base. 
 
 G.E.C. "Witton" Motor Driving Capstan. 
 
 One of the latest electrically driven appliances is the capstan 
 A motor direct coupled gives complete and instantaneous control by 
 
 No. 72.— •' Witton " Motor direct coupled to 
 Centrifugal Pump. 
 
Marine Electric Lighting 
 
 487 
 
 o 
 
488 
 
 "Verbal" Notes and Sketches 
 
 means of a starting switch placed in a convenient position, and 
 operated by foot only. 
 
 Pull, 4480 lbs. ; speed, 100 ft. per minute ; motor, series wound. 
 
 Largely used on board steamships, shipbuilding yards, and 
 dockyards. 
 
 Circulating water for condensing, or washing down decks, and fire 
 purposes. 
 
 No. 74.— Electric Punkah, G.E.C. " Bandy." 
 
 For Saloons, Cabins, &c. Installed on board many of the large 
 liners on the Eastern Routes. 
 
 The only electrically operated punkah giving the "flick" — the 
 distinctive feature of punkahs as compared with other cooling devices. 
 The G.E.C. Bandy punkah effects a saving of 50 to 70 per cent, in 
 current, when compared with an ordinary ceiling fan. The con- 
 sumpt per one hour is approximately : — 
 
 Of the 2 ft. 6 in. size - 
 „ 3 ft. 6 in. „ - 
 „ 4 ft. 6 in. „ - 
 
 An ordinary ceiling fan 
 
 27 watts. 
 
 34 ., 
 
 38 „ 
 
 100 „ 
 
Marine Electric Lighting 
 
 489 
 
 No. 75.— Extension Box. 
 
 No. 76— Luminous Electric Glow Radiators. 
 
 For Heating State Rooms, Music Rooms, &c. 
 
 This horizontal type of glow lamp Radiator is a great improve- 
 ment over the vertical type, specially for ships* use where vibration 
 and jarring occur. The lamps are made with the poles at opposite 
 ends, and one zig-zag filament runs through the lamp supported in 
 the middle. Each lamp is rated at 250 watts. 
 
490 
 
 " Verbal " Notes and Sketches 
 
 Advantages of Zig-Zig Type Radiators. 
 
 Lamps firmly held by clip at each end. 
 
 Opposite poles at opposite ends of lamp. 
 
 Increased contact surface. 
 
 Longer life of lamps. 
 
 The " Zig-Zag " filament increases radiation of heat. 
 
 Horizontal arrangement of lamps gives more pleasing effect. 
 
 No. 77.— Elevector. 
 
 "Archer" System of Heating by Convection, 
 for State Rooms, Dining Saloons, &c. 
 
 The Elevector is an air warmer. The cases are supplied in various 
 metals and finishes, and all types have interchangeable heaters or 
 elements of 500 watts each, i watt for each cubic foot of space to 
 be heated should be allowed for. 
 
 Electrical Notes. 
 
 By " Potential " is meant the difference of electrical tension 
 existing between the positive and negative leads. 
 
 A Volt is the measure of electrical pressure or E.M.F. (Electro- 
 Motive Force). 
 
 NOTE.— A Volt is the E.M.F. required to give one Ampere of current ag&inst 
 one Ohm resistance. 
 
Marine Electric Lighting 491 
 
 An Ampere is the measure of electrical current, and is taken as 
 the standard flow of electricit)- in a wire per second. 
 
 An Ohm is the measure of electrical resistance, and is about equal 
 to that of one mile of copper wire ^ in. in diameter. 
 
 Volts X Amperes = Watts. 
 
 746 watts are equal to i Electrical Horse-Power. 
 
 Therefore, Yg ltsx Amperes ^^.H. P. 
 746 
 
 E.H.P. compared to I.H.P. 
 
 It should be noted that the Electrical Horse-Power refers to one 
 second o'i \\\'\-\Q as the ampere flow is measured for that period, whereas 
 the I.H.P. of steam refers to one minute of time. 
 
 Therefore, 33000 -=- 60 = 550 foot-pounds per second, 
 and, 746 watts = 550 foot-pounds. 
 
 So that, 746 -=- 550 =1-35 watts per foot-pound. 
 
 As work and heat are equivalent, then it can be proved that to 
 produce the same heating effect (energy), r35 watts are equal to i 
 foot-pound. 
 
 E.H.P. per minute = 746x60=^44760 watts per min. 
 
 The size of a wire depends on the amount of current it has to 
 carry ; in other words, on the number of amperes. 
 
 The insulation of a wire depends more on the number of volts 
 carried by the wire. 
 
 The Board of Trade limit is 1000 amperes per square inch of 
 wire section. 
 
 Fuses or cut-outs are constructed to melt when the current 
 becomes double the working current. 
 
 Insulating materials are composed of indiarubber, tape, varnish, 
 vulcanised fibre, glass, cotton, earthenware, &c. 
 
 Arc lamps are usually run at from 45 to 55 volts. 
 
 Arc lamps require from 8 to 12 amperes of current. 
 
 Projector arc lamps require from 80 to 150 amperes of current. 
 
 A 16 candle-power incandescent carbon filament lamp requires 
 about 60 watts. 
 
 A 16 candle-power incandescent lamp run at 75 volts requires -8 
 of an ampere, because 60 watts -^ 7 5 volts = -8 of an ampere. 
 
 An " Osram " 16 candle-power incandescent metallic filament lamp 
 only requires about 20 watts, as the resistance of the filament is higher 
 and requires less current to produce the same heat. 
 
492 "Verbal" Notes and Sketches 
 
 1000 watts are equal to I kilowatt. 
 
 The positive wire or terminal is often marked thus +, and 
 painted red. 
 
 The negative wire or terminal is often marked thus — , and 
 painted black. 
 
 Fuses in earthenware cases are placed at different parts of the wire 
 circuits to act, if required, as automatic circuit-breakers. 
 
 Dynamos for ship-lighting usuall)' develop from 65 volts to 
 100 volts. 
 
 " In series " means in continuation. 
 
 " In shunt " means branched off. 
 
 Continuous current dynamos are generally employed for lighting 
 purposes, and alternating current dynamos for power stations. 
 
 Transformers are used in power stations to reduce the current 
 from a high to a low voltage without serious loss. 
 
 100 amperes at 2000 volts will give 400 amperes at 500 volts if a 
 transformer is used, because 
 
 Amperes. Volts. 
 100x2000 
 
 500 
 volts 
 
 =400 amperes. 
 
 NOTE. — This neglects loss of efficiency in transformer. 
 
 Accumulators are used for the storage of electricity, and consist 
 of a number of galvanic cells joined in series. The cells are charged 
 by the current from a dynamo, which decomposes the acid bath of 
 the cells and reverses the chemical conditions. After charging, the 
 electricity so stored up may be released and employed to act on an 
 external circuit if suitable wiring is arranged, as the chemical relation 
 of the plates causes a return to their original condition. Accumulators 
 are often employed on yachts, where a small number of lamps may be 
 required during the night, and in cases where the dynamo is not kept 
 running constantly. 
 
 The quantity of current flowing past a one ampere section of wire 
 in one second is called a " coulomb." 
 
 Electricity is one form of " energy " or " force." 
 
 Induction is the magnetic or electrical effect produced on surround- 
 ing bodies or substances by an electric current. 
 
f 
 
 Marine Electric Licrhtincr 493 
 
 The principle of induction is employed in transformers, where a 
 current of high voltage in a set of fine wires is made to induce currents 
 of a lower voltage in a set of coarser wires. 
 
 One " megohm " is equal to 1,000,000 ohms. 
 
 All substances offer more or less resistance to the flow of an 
 electric current : those having least resistance are employed as 
 " conductors," and those having most resistance are employed as 
 " insulators." 
 
 Rules — , 
 
 To find the Current strength in Amperes passing through an 
 electrical circuit. 
 
 Rule— 
 
 ^, Y,^^l = Amperes. 
 
 Ohms Resistance 
 
 and, Volts_^Qj^^g^ 
 
 Amperes 
 
 or. Amperes x Ohms = Volts. 
 
 Ex.\MPLE I. — The voltage is 100, and the resistance of a 16 candle- 
 power lamp 220 ohms. Find the required current in amperes. 
 
 Then, Amperes - Y^l^ - — = -45 Ampere ' 
 ^ Ohms 220 ^^ ^ 
 
 Example 2. — Find the resistance in ohms if the voltage is lOO 
 and the amperes 300. 
 
 Then, Ohms :^ .XS^ = ^-9°= .33 Ohm. 
 Amperes 300 
 
 Example 3. — The output in amperes is 250, and the resistance 
 •4 ohm. Find the required voltage. 
 
 Then, Volts - Amperes x Ohms = 250 x -4 = 100 Volts. 
 
 Example 4. — Find the number of watts required for a lamp 
 taking -6 of an ampere at 100 volts. 
 
 Then, Watts = Volts x Amperes = 100 x -6 = 60 Watts. 
 
 34 
 
494 
 
 "Verbal" Notes and Sketches 
 
 GENERAL ELECTRICAL NOTES AND SKETCHES. 
 
 
 ^■s 
 
 - * - 
 
 ^ 
 
 ' I ^ 
 
 No. 78.— Lines of Force in a Bar Magnet 
 
 Lines of force fiow from N. to S. poles as shown by the arrows 
 and dotted lines. 
 
 No. 79.— Lines of Force Between Two Bar Magnets. 
 
 Notice that when the N. pole of one magnet and the S. pole of 
 another are brought together lines of force pass out from the N. 
 pole to that of the other S. pole, that is, " unlike poles attract." 
 
 No. 80.— Horse Shoe Magnet. 
 
 As in the case of the bar magnet, lines of force pass over from 
 the N. pole to the S. pole, the gap between being known as the 
 "field space," or "magnetic field." A two-pole dynamo is similar 
 to the above, the armature revolving in the space between the two 
 magnet poles. 
 
Marine Electric Lighting 
 
 495 
 
 
 
 No. 8i. — Opposed Magnetism. 
 
 Two bar magnets placed as shown, with like .poles to like, pro- 
 duce repulsion of the lines of force, as, "like poles repel" and 
 "unl ke poles attract." 
 
 
 
 No. 82. — Lines of Force Surrounding 
 a Conductor, 
 
 A live wire is encircled by lines of force as indicated 
 by the dotted circles. From these are obtained the induc- 
 tion effects, which develop between adjacent coils under 
 certain electrical conditions. 
 
 No. 83. — Electro-Magnet. 
 
 By coiling a wire round a bar of iron as shown, and passmg a 
 current through the wire, the bar becomes magnetised. The flow 
 of current in the wire, polarity, and the lines of force produced in 
 the bar are clearly shown by the arrows. 
 
496 
 
 Verbal " Notes and Sketches 
 
 No. 84. 
 
 Diagram showing lines of force across field space, when un- 
 undisturbed by armature magnetism. The position of the brushes 
 would in this case be exactly at the top and bottom of the com- 
 mutator circle. 
 
 The dots on the conductor ends represent positive E.M.F. 
 ,, crosses „ „ „ negative „ 
 
 No. 85. 
 
 Diagram showing lines of force across field space as affected 
 by armature magnetism. It will here be seen that the lines of force 
 
Marine Electric Liq^hting 497 
 
 are now distorted by the effect of the armature acting as a magnet, 
 thus pulling round the field lines in the direction of rotation, so 
 that to strike the neutral point or sparkless position for the brushes 
 when the load is increased, the latter require to be rocked round 
 slightly in the direction of rotation (advanced). For an electric 
 motor, as the E.M.F. action is reversed, the brushes require to be 
 moved back in place of forward. 
 
 To correct this distortion of the field, dynamos are now usually 
 fitted with "commutator poles" (see sketch 96), which neutralise 
 the effect of the armature magnetism, and eliminate the necessity 
 for altering the position of the brushes when the load or speed is 
 increased. 
 
 No. 86. — Lines of Force in 4-Pole Dynamo. 
 
 The arrows show the direction of thejines of force between the 
 poles of a 4-pole machine, the armature running clockwise. The 
 armature conductors cut through these lines of force and generate 
 currents by induction. 
 
498 
 
 "Verbal" Notes and Sketches 
 
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 through the lamps and back again. At present position the shaded com- 
 mutator bar is negative and the light one (left) positive. 
 
r C'Dnduct'oi 
 
 No. 87.— Simple 2- Pole AC- Dynamo. 
 
 The arrows, together with the plus and minus sighs, show clearly the reversal of E.M.F. at each 
 half of the revolution, and it should be noted that in the left hand view the current is flowing 
 through the lamp filaments from the brush on the slip ring nearest the armature, whereas in the 
 right hand view the current is flowing through the lamps from the brush on the other slip rmg and 
 is thus reversed in direction. This is due to the fact that the conductor has turned half round, and 
 the portion previously under the influence of positive current now comes under the influence of 
 negative currents. 
 
 In place of a commutator two slip rings are fitted, and the brushes bear on these rings, taking up 
 and giving back the current in the usual way. The conductor ends are connected to the two 
 slip rings. 
 
 \To fate page ^^%. 
 
Marine Electric Lighting 
 
 499 
 
 No. 89. — Simple D.C. Armature Conductor 
 (with one conductor and two commutator bars). 
 
 The conductor, it will be noticed, is wound back on itself, and this 
 is done to intensify the E.M.F. effect by increasing the number of turns 
 or loops formed by the conductors, the effect being cumulative. The 
 arrows show that the current flow is in one direction, from left to right 
 through the lamps and back again. At present position the shaded com- 
 mutator bar is negative and the light one (left) positive. 
 
498 
 
Marine Electric Lighting 
 
 499 
 
 No. 89. — Simple D.C. Armature Conductor 
 (with one conductor and two commutator bars). 
 
 The conductor, it will be noticed, is wound back on itself, and this 
 is done to intensify the E.M.F. effect by increasing the number of turns 
 or loops formed by the conductors, the effect being cumulative. The 
 arrows show that the current flow is in one direction, from left to right 
 through the lamps and back again. At present position the shaded com- 
 mutator bar is negative and the light one (left) positive. 
 
500 
 
 "Verbal" Notes and Sketches 
 
 No. 90.— Simple D.C. Armature Conductor. 
 
 After making a half revolution it will be noticed that the current is 
 still flowing in the same direction, as the dark commutator bar is now 
 under the positive brush, and thus counteracts the reversal of current 
 flow in the conductor. By this means the current is "commuted "to 
 flow in one direction all the time. 
 
Marine Electric Lighting 
 
 501 
 
 No. 91. — Soft Iron Disc of Armature Body. 
 
 The armature is built up with a number of these plates formed 
 of soft charcoal iron, insulated from each other by thick varnishing, 
 and clamped on endways to ''he driving spindle, spider, and key. 
 The sloes shown are for the insulated conductors, which are held in 
 place by check pieces and by binding straps. 
 
No. 92.— Sectional View of Armature. 
 
 I, Driving shaft. 2, Feather or key. 3, Collar. 
 
 4, Nut. 5, Locking plate. 
 
 6, Plates of soft iron insulated from each other by varnish, and which form 
 the "armature core." The insulating of each plate from the next prevents the 
 formation of eddy currents in the armature body, without in any way interfering 
 with the flow of lines of force across the poles. 
 
 7, Conductor lying in longitudinal slotway, and connected up to the commu- 
 tator bars by either the "wave" or "lap" wound system of winding. 
 
 8, Ventilation openings to prevent rise of temperature. 
 
 © © 
 
 No. 93.— -Sectional View of Commutator. 
 
 I, 
 
 Driving shaft. 
 
 5, Insulation. 
 
 2, 
 
 Feather or key. 
 
 6, Connector for conductor and 
 
 3. 
 
 Bolt for clamping copper blocks 
 
 copper block. 
 
 
 in position. 
 
 7. Armature conductor. 
 
 4- 
 
 Copper bar. 
 
 8, Locking clamp. 
 
Marine Electric Lighting 
 
 50: 
 
 No. 94- — Slot in Armature with 
 Conductor in Position. 
 
 1, Wooden key or locking piece. 
 
 2, Copper conductor. 
 
 3, Insulation of conductor. 
 
 No. 95.— Box Type Brush Holder (Carbon Brushes.) 
 
 1, Carbon brush. 
 
 2, Conductor connection to brush. 
 
 3, Spring for pressure of brush. 
 
 4, Screw for spring adjustment. 
 

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Marine Electric Lighting 
 
 505 
 
 t 
 
 No. 98 —Lap Winding. 
 
 Observe that the conductor starts at A end on block i, and 
 after looping round finishes on block 2 at B end. 
 
 The loop is arranged to intensify the electrical effect produced 
 in the coil. 
 
 (Copper 
 No. 99. — Example of Lap Winding of Armatures. 
 
 Conductor A begins on commutator bar i and finishes on 2. 
 C ,, ,, ,, 2 ,, ,, 3. 
 
 That is, each conductor is led off from one bar and completes its 
 path on the adjoining bar, after first passing from front to back of the 
 axmature, across the back, then back to the front again. 
 
Verbal " Notes and Sketches 
 
 No. 100.— Diagram of 4-Pole D.C. Armature Lap Winding. 
 
 Note. — By D.C. is meant "direct current," and A.C "alternating current." 
 
 The above sketch shows an expanded view of the armature windings, 
 magnet poles, commutator, and brushes ; the lamp circuits are also indicated, 
 and the current flow (or E.M.F. induced) represented by the direction of 
 the arrows. Observe that the conductor (j) starts on commutator block A, 
 and finishes on block B ; each conductor is coupled up similarly, and by 
 suitably arranging the conductor groupings the combined flow of the current 
 from each conductor enters at those blocks of the commutator where the 
 positive brushes are placed (marked +). In the same way at other two 
 neutral positions the current from each conductor flows away from the 
 commutator blocks, and these are the positions for the negative brushes. 
 
■1 
 
 \ i 
 
 i 
 
 v\ 
 
 \r 
 
 \ ■ 
 
 Vv. 
 
 7 
 
 
 
 ti.io a\ft-' 
 
 atici\.o »ji v,^ 
 
 off at the same angle back and front, owing to the fact that the con- 
 ductors connect to different commutator bars than those of the 
 lap winding. 
 
No. 101.— Diagram of 2 Pole Armature Lap Winding. 
 
 Black dots shown thus • represent positive flow E. M.F. currents. 
 Crosses ,, -|- ,, negative 
 
 Observe that each conductor starts out from one commutator block, passes out radially to the drum surface, runs 
 back to the end of the armature, crosses the back, is led forward again, and finally connects up to the adjacent com- 
 mutator bar. 
 
 Referring to "the sketch, the coil beginning on block C completes its path on block D after being led round as 
 described, and in the same way the conductor starting from block B finishes on block C, and so on. Tracing out 
 the flow of E.M.F. it will be evident that the resultant current flow of each conductor connected to the copper block 
 on which the positive brush is shown in contact is in the same direction, that is, into the block, and the same holds 
 good at the negative brush position as the combined current flow is then outwards or negative. This action is 
 successive, as each block comes into position under the positive or. negative brush. 
 
 t7b/u,.-/tii/<-sob. 
 
Marine Electric Lighting 
 
 507 
 
 ARMATURE DRUM 
 
 No. 102. —Lap Wound Armature Winding. 
 
 ARMATURE DRUM 
 
 No. 103.— Wave Wound Armature Winding. 
 
 Observe the difference in the two methods of winding as seen 
 on the drum surface, the lap method forming equal and opposite 
 angles of connection back and front, whereas the wave winding runs 
 off at the same angle back and front, owing to the fact that the con- 
 ductors connect to different commutator bars than those of the 
 lap winding. 
 
5o6 
 
 jnirtitrs:- 
 
 N< 
 
 Noh 
 
 T 
 magn 
 and 1 
 the a 
 
 finCl Iimaiica <- 
 
 suitably arranging the conductor groupings the combined flow of the current 
 from each conductor enters at those blocks of the commutator where the 
 positive brushes are placed (marked +). In the same way at other two 
 neutral positions the current from each conductor flows away from the 
 commutator blocks, and these are the positions for the negative brushes. 
 
 
 I 
 
Marine Electric Lighting 
 
 507 
 
 ARMATURE DRUM 
 
 No. 102.— Lap Wound Armature Winding. 
 
 ARMATURE DRUM 
 
 No. 103.— Wave Wound Armature Winding. 
 
 Observe the difference in the two methods of winding as seen 
 on the drum surface, the lap method forming equal and opposite 
 angles of connection back and front, whereas the wave winding runs 
 off at the same angle back and front, owing to the fact that the con- 
 ductors connect to different commutator bars than those of the 
 lap winding. 
 
5o8 
 
 "Verbal" Notes and Sketches 
 
 No. 104.— End View of 4-Pole Shunt Wound DC. Dynamo. 
 
 With the armature turning clockwise the brushes opposite the S. poles 
 are positive, and those opposite the N. poles are negative. The two positive 
 sets are coupled together by the ring shown, and the two negative sets are 
 arranged similarly. 
 
 The objection to this type of dynamo for parallel lighting purposes is 
 that when lamps are switched off the remaining lights would burn brighter 
 unless the armature speed was reduced to correspond : the reverse also holds 
 good if lamps are switched into circuit, the reason being that the current 
 has two paths open to it, and if the resistance in one of two is increased 
 the other will receive an increase of current, assuming that the armature 
 speed were to remain constant. 
 
Marine Electric Liohtiui/ 
 
 509 
 
 No. 105. — End View of 4-Pole Compound Wound D.C. 
 
 Dynamo. 
 
 With the armature revolving clockwise, the two brushes opposite the S. 
 poles are positive, and it should be noted that they are connected together 
 by a ring-piece to which is fixed the positive series winding wire. 
 
 The negative brushes are opposite the N. poles, and the two sets of brushes 
 are also connected to each other and to the negative series winding wire. 
 
 Observe that the shunt winding starts from one brush connection, is led 
 round the four magnet poles, and returns to the other brush connection, 
 thus completing its path. Again it should be noted that only a few series 
 turns are employed, whereas a great number of the fine shunt windings are 
 necessary. 
 
 35 ^ . . 
 
5IO "Verbal" Notes and Sketches 
 
 MOTOR STARTING RESISTANCE, &c. 
 
 The reader is advised to carefully study the following extract 
 from an article entitled " Some Notes on Elementary Electrical 
 Engineering," by W. Benison Hird, B.A., M.I.E.E., and which appeared 
 recently in The M. ajid C. Apprentices' Magazine, as the section 
 dealing with the principle of motor starting switch resistances is of 
 peculiar value to the marine engineer. 
 
 The author has to thank W. B. Hird, Esq., for kind permission to 
 use the article as here reprinted. 
 
 " In these notes an attempt is made to put the reader in the way 
 of solving for himself such of these questions as relate to elementary 
 electricity and magnetism and the simpler facts concerning dynamos 
 and motors. 
 
 " There are two elementary laws or principles which, properly 
 understood and applied, will carry him very far towards the solution 
 of many at first sight puzzling facts in elementary electrical 
 engineering. 
 
 " First. The current flowing in any circuit is equal to the sum of 
 the electromotive forces in that circuit divided by the resistance. 
 
 "That is to say that a given E.M.F. being applied to the terminals 
 of any circuit, a perfectly definite current will flow through it, and 
 that current will be proportional to the E.M.F. divided by the 
 resistance. If the E.M.F. is measured in volts and the resistance 
 
 F M F 
 
 in ohms, the ratio — ^^^: — '- — '- — will represent the current in amperes. 
 Resistance 
 
 In symbols if E represent the E.M.F. in volts, R the resistance 
 
 E 
 
 in ohms, and C the current in amperes, then C =:^. 
 
 R 
 
 " Second. The second principle to remember is the observed fact 
 that if any conductor is moved in a magnetic field so as to cut the 
 lines of magnetic force, an E.M.F. will be generated in the conductor. 
 
 " A magnetic field is any portion of space under the influence of 
 a magnet. Every magnet has two poles, a north pole and a south 
 pole, and we can imagine the whole of the space near the magnet 
 as filled with imaginary lines running from the north pole to the 
 south pole, and along which the force of attraction of the magnet 
 acts. Such lines are known as lines of magnetic force, and the 
 number of such lines in a given area depends upon the strength of 
 the magnet and the distance they have to pass in getting from the 
 north pole to the south pole ; in fact, it is proportional to the strength 
 of the magnetic field. . 
 
 " To take a concrete example, take a two-pole dynamo or motor : 
 the magnet consists of a horse-shoe shaped piece of cast steel, and is 
 converted by the current circulating in the field coils into an electro- 
 magnet with a north pole at one end and a south pole at the other ; 
 when the armature is put into this magnet a narrow air gap is left 
 
Marine Electric Lighting 511 
 
 between the steel of the magnet and the iron of the armature core: 
 tliis narrow gap must be imagined as filled by a large number 
 of lines of magnetic force running from the north pole of the magnet 
 into the armature iron and out of this into the south pole of the 
 magnet. For the most part these lines will run radially and straight 
 across the gap, but at the edges of the magnet they will spread out 
 and form a fringe extending into the armature iron at some little 
 distance from the magnets. Forming a mental picture of such a 
 magnetic field, it is evident that any conductors laid on the armature 
 parallel to the shaft will, when the armature rotates, cut the lines of 
 force, and will therefore have an E.M.F. generated on them. 
 
 " Note that it is only an E.M.F. that is generated, and that there 
 is not necessarily any current flowing in the conductors. In order 
 that current may fiow, another condition is necessary besides the 
 cutting of lines of force, and that is that the conductors should form 
 part of a closed circuit to carry this current, and if such is the case 
 the current will then follow our first law, and the amount of current 
 flowing will be equal to the E.M.F. generated divided by the total 
 resistance of the circuit. 
 
 " Further, a conductor placed in a magnetic field and carrying a 
 current will tend to move in such a way as to cut the lines of 
 magnetic force, the direction of motion being such as to generate 
 an E.M.F. opposing the current. 
 
 " In illustration of the above apply these principles to some of the 
 simplest and most elementary questions which are likely to occur to 
 any one just coming into contact with dynamos and motors. For 
 instance — 
 
 Why is a Resistance put in Series with a D.C. Motor 
 on Starting it Up? 
 
 "The resistance of a motor armature is necessarily very small : 
 high resistance in the armature winding would mean large losses, 
 which would be injurious in two ways. First, as all losses appear 
 ultimately as heat, they would cause too high a temperature rise to 
 the detriment of the insulating materials, which would rapidly perish ; 
 secondly, they would mean an unnecessarily low efficiency, for 
 evidently these losses must be supplied from some source, and must 
 mean that an increased power is taken from the mains to give out 
 the same power at the pulley. This being the case, the armature 
 resistance is kept as low as possible, and if the motor were put 
 directly on to the mains, it would momentarily take a very large 
 current. Take a numerical example. A 10 H.P. motor designed to 
 run at 500 volts will have an armature resistance of about -5 ohm. 
 If such an armature were switched directly on to the mains at 
 500 volts, it is readily seen from our first principle that the current 
 
 would amount to ^ — = 1000 amperes, but the normal current of the 
 
 ■5 
 
512 " Verbal " Notes and Sketches 
 
 motor when giving lo H.P. is only about 20 amperes ; the mains 
 and armature conductors are only designed to carry 20 amperes, 
 and such a large current as 1000, even if only for a moment, is very 
 excessive, and evidently out of the question. Even apart from any 
 electrical consideration, the mechanical effect of such an excessive 
 current would be damaging in the extreme to the mechanical parts 
 of the motor, and of the machines it might be driving; to put 
 suddenly on to any machine a force 50 times in excess of what it is 
 intended to carry is evidently courting disaster. For this reason a 
 resistance is inserted to check the momentary flow of current. Say 
 a resistance of 19-5 ohms is inserted in circuit with the motor, then 
 
 the current flowing through the circuit will be - — =25 amperes. 
 
 The armature conductors are now in a magnetic field, and they are 
 carrying a current of 25 amperes. They will tend to move in such 
 a way as to cut the lines of magnetic force, and the armature will 
 start to rotate. As soon as rotation begins an E.M.F. will be 
 generated in the armature opposing the E.M.F. applied to the 
 terminals, and this back E.M.F. will increase as the speed increases, 
 because the E.M.F. generated by the cutting of lines is proportioned 
 to the rate of cutting. After the armature has attained a certain 
 speed, the back E.M.F. will be, say, 200 volts. Then the effective 
 electromotive force in the circuit will be 500-200 volts = 300 volts, 
 500 volts at the mains and an E.M.F. of 200 volts generated in the 
 motor armature, and acting in the opposite direction. Again, divdde 
 E.M.F. by resistance, and we will find that the current will now 
 
 be ^ — =15 amperes. Will the armature increase in speed and the 
 20 
 
 current be further cut down ? This depends entirely on what work 
 
 the motor is put to. Say it is driving shafting; if 15 amperes is 
 
 just sufficient to drive the shaft, the speed will not increase, and the 
 
 motor will go on running steadily at the same speed. If, however, 
 
 a smaller power is sufficient to drive the shaft at this speed, the motor 
 
 armature will go on accelerating, the E.M.F. generated will also 
 
 increase, and further reduction of the current will take place. 
 
 Assume that 15 amperes is just sufficient to drive the shaft, the 
 
 motor will then continue running at the speed it has now reached. 
 
 Now is the time to cut out some of the resistance introduced in the 
 
 circuit. Say this is reduced by moving the starting switch on to 
 
 the next contact to 11-5 ohms, the total resistance in circuit will be 
 
 12 ohms, and we have seen the effective E.M.F. to be 300 volts ; the 
 
 '^00 
 current will therefore rise to - — = 2K amperes. This is more than 
 
 12 ^ 
 
 what is required to keep the shafting in motion, and the armature 
 
 will therefore increase in speed : the back electro-motive force will 
 
 also increase and the current be cut down in value until it again 
 
 reaches the value of 15 amperes. The process is then repeated until 
 
 all the resistance is cut out and the motor is running at normal speed. 
 
Marine Electric Lighting 513 
 
 Why does the Introduction of Resistance in the Shunt 
 Circuit of a Motor cause an Increase in the Speed? 
 
 "To many beginners in the subject it appears that one would 
 more naturally expect the reverse to be the case, and that putting 
 in resistance would lower the speed, taking it out would increase the 
 speed. On consideration, it is easily seen that this view is erroneous. 
 The shunt circuit of a motor is a separate circuit, having a definite 
 resistance and connected across the mains, so that it has a definite 
 E.M.F. on its terminals ; it will therefore carry a definite current 
 
 C = -j where C is the shunt current, R the resistance of the 
 
 R 
 shunt circuit, and E the E.M.F. at the mains. Now, any increase 
 in the resistance evidently decreases the current and weakens the 
 magnetic field. There will be fewer lines of magnetic force flowing 
 across the air gap of the motor, but in order to give the same back 
 E.M.F. the conductors must cut the lines of force at the same rate. 
 Since there are fewer lines to cut, the conductors must cut what there 
 are quicker, that is, the armature will speed up. Why must the 
 armature keep up the same back E.M.F. ? Because if it does not, 
 the effective E.M.F. in circuit is greater ; the current being equal to 
 the effective E.M.F. divided by the resistance of the armature circuit 
 is also increased, and the armature taking a current greater than that 
 required to overcome the load will accelerate. 
 
SECTION VIII. 
 
 PROPELLERS. 
 
 As the majority of marine engineers are unfamiliar with the 
 various definitions connected with the screw propeller, the author 
 has deemed it advisable to endeavour to give clear and, if possible 
 concise explanations of each, accompanied by suitable illustrations. 
 
 General. — The marine propeller, simply considered, is merely a 
 common screw working in a nut. 
 
 If a screwed bolt be turned one complete revolution in a corre- 
 sponding nut, the bolt will advance or travel along the nut a distance 
 equal to that between two adjacent threads, or, as it is usually 
 expressed, equal to one pitch, P (see sketch), so that if a bolt has, 
 say, eight threads to the inch, in one turn of the bolt or nut the 
 advance will be | inch. 
 
 No. I. — Common Screw. 
 P = Pitch. 
 
 The diameter of the propeller boss represents the bolt at the 
 bottom of the thread, and the propeller blades the actual threads, or, 
 more correctly , pieces of thread (see sketch). 
 
Propellers 
 
 515 
 
 No. 2. — Actual Propeller compared with Actual Screw. 
 
 A three-bladed propeller consists of three pieces of thread set on 
 the boss, and a four-bladed propeller consists of four pieces of thread 
 set on the boss. 
 
 The water in which the propeller is immersed, and in which it 
 works, represents the nut, so that when the bolt or propeller shaft 
 is revolved the screw or propeller advances in the nut, which, as 
 before stated, is represented by the water in which the propeller 
 works. 
 
 As, however, the water constitutes a yielding nut and gives way 
 a certain amount to the blades, the actual advance of the propeller 
 and ship is less than one pitch of the screw for one complete revolu- 
 tion of the shaft ; this difference of advance is known as the slip. 
 
 Thrust. — The effect of the propeller thrust is, generally speaking, 
 twofold — (i) to drive the water aft, (2) to drive the ship forward. 
 The reaction of driving the water aft results in the steamer being 
 driven or propelled forward. 
 
 Pitch. — As stated above, the pitch is the longitudinal advance of a 
 screw during one revolution, if working in a solid nut. 
 
 A screw or helix, if unrolled, forms with the pitch and circumference 
 a triangle, of which the thread represents the hypothenuse or diagonal. 
 
 If, therefore, a sheet of paper is taken, and a line A B drawn from 
 corner to corner, and the sheet rolled up into a cylinder, the ruled 
 line A B will represent the edge of a screw or thread, and the length 
 of the roll the pitch (Sketches Nos. 3 and 4). 
 
5i6 
 
 Verbal " Notes and Sketches 
 
 \ 
 
 \^ 
 
 
 \>^ 
 
 
 \-0 
 
 
 \o 
 
 
 \^ 
 
 
 \^ 
 
 
 \^ 
 
 
 \^ 
 
 Ul 
 
 \<^ 
 
 o 
 
 \^ 
 
 z 
 
 V^ 
 
 Ul 
 
 \ 
 
 oc 
 
 
 Ul 
 
 
 u. 
 
 X'^ 
 
 s 
 
 V 
 
 3 
 
 V 
 
 u 
 
 i \<<^ 
 
 e£ 
 
 VL 
 
 (J 
 
 \ 
 
 
 
 B 
 
 B 
 
 •PITCH 
 
 *• PITCH > 
 
 No. 3.— Flat Sheet of Paper. No. 4.— Paper rolled up. 
 
 Triangle described by Screw. 
 
 It will thus be seen that the pitch Is the length between the two 
 ends of the thread taken for one complete turn of the screw, or the 
 advance made by any point or piece of the thread during one 
 revolution. 
 
 In an actual propeller the breadth of blade represents the piece of 
 thread or the hypothenuse of the triangle, the distance between the 
 leading and after edges the piece of pitch, and the distance, measured 
 vertically, between the lower and upper edges the piece of circum- 
 ference : these all correspond, it will be noted, with the screw 
 representation on the sheet of paper as shown above. 
 
 Right- and Left-hand Screw. — Tlie blades of a right-handed 
 propeller revolve from port to starboard (upper half of blade circle), 
 and the blades of a left-handed propeller revolve from starboard to 
 port. 
 
 Circumference. — As will readily be understood from the foregoing, 
 the circumference is the distance round the cylinder forming the screw 
 surface at right angle to the shaft, which, when unrolled, forms one 
 of the shorter sides of the triangle. The diameter of the propeller 
 multiplied by 3-1416 is equal to the complete circumference. 
 
 Thread. — As before stated, the thread is the complete length of the 
 
Propellers 5 1 7 
 
 unrolled helix, and each propeller blade is equal in width to a piece 
 
 I 
 
 _^ 
 
 No. 5.— Right-hand Propeller Blade. 
 
 T, Piece of Thread, or Hypothenuse. P, Piece of Pitch. C, Piece of Circumference. 
 
 of the thread only. The thread forms the diagonal or hypothenuse of 
 the pitch triangle, and therefore its longest side. 
 
 Increasing Pitch. — Propellers are sometimes designed with a varying 
 pitch — (i) the pitch increasing radially, that is, the pitch at or near 
 the tip of the blades is more than the pitch near the boss ; or (2) the 
 pitch may increase axially, or from forward aft, that is, the pitch near 
 the after edge of the blade may be slightly more than the pitch near 
 the forward edge. In the sketch shown below the pitch at B is more 
 than the pitch at A. 
 
 THRUS • 
 SURFACf 
 (FACE) 
 
 LEADING 
 
 EDGE 
 
 No. 6. — Thrust and Drag Surfaces. 
 
5i8 
 
 Verbal " Notes and Sketches 
 
 True Screw. — When the blades have no variation in pitch, either 
 radially or axially, the blade surface is said to be that of a " true 
 screw." Some of the most efficient propellers of present day practice, 
 including those of turbine steamers, are of this type. 
 
 Pitch Ratio. — The propeller pitch, divided by the propeller diameter, 
 is equal to the " pitch ratio." The pitch ratio may vary from about 
 •9 in small propellers to 1-4 in large propellers, in steamers with 
 reciprocating engines. 
 
 Diameter of Propeller. — The diameter of a propeller is the diameter 
 of the circle described by the tips of the blades. 
 
 Length of Propeller. — The length of a propeller is measured longi- 
 tudinally on the shaft, and is usually about equal to the length of 
 the boss. 
 
 Length of Blade. — The length of a blade is measured from the root 
 at the boss to the tip of the blade. 
 
 Moulding of Blades. — In moulding the propeller blades a horizontal 
 arm is rotated round a vertical spindle, and at the same time moved 
 up or down the spindle, thus generating the screw surface or helix. 
 To guide the travel of the moving arm one or more curved vertical 
 guide templates are placed in position, and the moving arm travelling 
 over the upper edges of the templates shapes out the blade surface 
 for the required pitch, &c. The vertical templates referred to are 
 triangular in shape, and are cut to the correct pitch angle for various 
 points of radius on the blade. 
 
 PITCH 
 TEMPLATE 
 
 No. 7— Method of producing the Screw Surface. 
 
Propellers 519 
 
 Slip. — Slip is of three kinds — (i) apparent slip, (2) real or actual slip 
 and (3) negative slip. The "log" slip found by taking the difference 
 ol the propeller speed and the ship speed is only apparent slip, the 
 real slip being (in nearly every case) in excess of this. The real slip 
 is found by adding together the apparent slip and the " wake speed " 
 (if known). 
 
 Wake Speed. — Wake speed is the name given to the velocity of the 
 stream or column of water which fo/Zozas at the stern of a vessel. 
 
 The wake speed will be more with a bluff-lined steamer than one 
 with fine lines, as the more square shape of the stern tends to pull the 
 water along with the vessel, and thus give a higher wake speed. 
 
 From the foregoing it will perhaps be seen that the speed of the 
 ; vessel is less relatively to the wake speed than to still water. This, 
 ' therefore, has the effect of taking away, as it were, part of the 
 actual slip. 
 
 As before stated, to calculate the real slip the wake speed must be 
 added to the apparent slip. 
 
 j Disc Area. — By disc area is meant the area of the circle described 
 and enclosed by the tips of the propeller blades. 
 
 Developed Area. — By developed or expanded blade area is meant 
 the full area of all the blades if flattened out and taken as approxi- 
 mate plane surfaces. 
 
 No. 8.— Expanded Blade Area. 
 
 Area Ratio. — By area ratio is meant the relative total expanded 
 area of the blades compared with the " disc area." The area ratio 
 varies from -3 to -6 of the disc area. 
 
 Projected Area. — This means the actual area of blades as projected 
 at right angles to the line of shafting, and constitutes the effective 
 thrusting area of the blades. 
 
 NOTE. — The blade area as seen when looking forward from behind the 
 propeller is the "projected area." 
 
520 " Verbal " Notes and Sketches 
 
 No. 9. — Projected, or Effective Thrusting Area of Blades. 
 
 Thrust Surface or Driving Face. — The after surface of the blades 
 is the thrusting surface, which acts on the water to drive forward 
 the vessel. 
 
 Drag Surface or Back of Blade. — The forward (usually the rounded) 
 surface of the blades is known as the drag surface. 
 
 Leading Edge. — With the blade in a horizontal position (see sketch), 
 the " leading edge " is that edge lowest down, and which for a right- 
 hand propeller lies on the starboard side ; for a left-hand screw the 
 leading edge will be on the port side. 
 
 Following Edge. — With the blade in a horizontal position, the after 
 edge and that highest up is called the " following edge." 
 
 Cavitation. — By cavitation is meant the failure of water supply or 
 " feed " to the propeller, due generally to excessive blade velocity ; in 
 other words, the blade speed exceeds the water flow speed to the 
 blades, therefore the effective thrust falls off in proportion, as cavities 
 form at the forward side of the blades. Cavitation is therefore caused 
 by the ineffectiveness of the atmospheric pressure to press up the 
 water at the back of the blades (forward side) fast enough to allow 
 of effective thrust ; this usually occurs at high revolution speeds and 
 high blade pressures per square inch. 
 
 The phenomenon of cavitation has been very exhaustively investi- 
 gated in a series of elaborate experiments carried out by the Hon. 
 
Propellers 521 
 
 C. A. Parsons, in connection with trials of turbine-engine propellers 
 -^ce " The Marine Steam Turbine," by J. W. Sothern). 
 
 It should be noted that slip is an absolute necessity for the effective 
 I ffort of a screw propeller, and if a propeller shows a very low slip 
 l)crcentag-e it indicates that the propeller fitted is evidently unsuitable 
 for the steamer in question, as it is not delivering an effective thrust 
 on the water. In most cases the slip should average from 5 to 
 1 5 per cent., and in some cases even more. 
 
 Apparent Negative Slip. — If without strong current speed a pro- 
 peller shows negative slip, it may be taken for granted that (as in the 
 case of low positive slip) the propeller is not suited for the work it has 
 to do, and indicates the necessity for another propeller of different 
 design being substituted, probably one of greater pitch and diameter. 
 Negative slip is most likely to show in steamers having very bluff 
 ^tern lines, and therefore giving a resultant high wake speed. 
 
 NOTE. —Apparent negative slip may occur with a strong current going with the 
 steamer. 
 
 It is generally admitted now by authorities on the propeller that 
 negative slip can only be apparent, and an example may be given 
 as follows : — 
 
 Example. — Pitch 15 feet, Revolutions 62, ship's speed 14 Knots, 
 speed o^ following current 4 Knots, find slip. 
 
 Then, Engine Knots = i8 x 62 x 60 ^ ^ ^ yi^^^^^ 
 
 ^ 6080 
 
 and, 14 - II = 3 Knots apparent negative slip. 
 
 But, Actual Propeller advance through water = 14 - 4 = 10 Knots. 
 Therefore, Real Slip = 11-10 = 1 Knot. 
 
 So that instead of an apparent negative slip of 3 Knots we have 
 a positive and real slip of i Knot. 
 
 No. 10.— Blade "Set Back,' 
 
522 "Verbal" Notes and Sketches 
 
 Set Back. — Sometimes the blades of a propeller are set with an 
 inclination aft instead of being arranged at right angles to the shaft : 
 this is known as " set back " or " skew." 
 
 Racing. — Racing is produced by the blades or parts of the blades 
 rising out of the water when the stern lifts in pitching. The effect of 
 this is to carry down into the water a quantity of air, and as the 
 resulting mixture of a.ir and water is less solid or dense than water 
 alone, the blades meet with less resistance, and the engines " race " in 
 consequence. It will be noted that the whole propeller does not 
 require to come out of the water to produce racing, as part only of a 
 blade coming above the surface may be sufficient to produce it. Less 
 racing will occur when small propellers are fitted low down, as in the 
 case of turbine steamers. 
 
 Cone. — In well-finished propellers the nut aft of the boss is covered 
 with a thin metal cover, conical in shape, which continues aft the 
 round of the boss, and prevents interruption of the " flow " or " run " of 
 the water past the blades. 
 
 CONE 
 
 No. II.— Nut and Cone. 
 Propeller Design. 
 
 The majority of the following rules for*' propeller design are taken 
 from Seaton's " Manual of Marine Engineering," also Seaton and 
 Rounthwaite's " Pocket-Book of Marine Engineering Rules and Tables," 
 and the author would take this opportunity of recommending a copy 
 of either of these standard works to all readers anxious to investigate 
 more fully into the various problems of marine engineering design. 
 The following descriptions are therefore intended to be applied in 
 conjunction with the above-named books, a copy of which, as before 
 stated, should be obtained for reference. 
 
 NOTE.— It must be clearly understood that no absolutely correct hard and fast 
 rules suitable for the successful designing of propellers can be laid down on paper, 
 as in actual drawing-office practice comparative records of previous performances, 
 tables of "slip" factors, "area factors," Admiralty coefficients, results of tank 
 
Propellers 523 
 
 experiments, and other data, are largely employed in arriving at the best pattern 
 of propeller suitable for a steamer of given type, dimensions, and speed. A vast 
 amount of investigation is yet open to experimenters in propeller efficiency and 
 design, as at present, in a number of cases, the most suitable propeller is often 
 only found after repeated trials of other propellers of different pitch, diameter, and 
 area. In support of this the writer remembers once seeing nineteen propellers 
 which had all been tried successively on a torpedo destroyer before the one giving 
 the best results was discovered. 
 
 I. To Design and Draw a Propeller for the following: — 
 
 Given - 
 
 /I.H.P. - - 600. 
 Knots - - 10. 
 Revolutions - 76. 
 Tail shaft - - 11 inches diameter. 
 Typ)e of steamer Cargo boat. 
 
 Propeller to be of the four-bladed, cast-iron, solid type. 
 
 NOTE. — It should be stated that it is not usual in drawing-office practice to 
 show as many different views of the blades, &c., as here drawn in the examples 
 given, but as this description is specially written for the use of marine engineers 
 with little or no experience of geometrical projection drawing, it has been considered 
 advisable, for the sake of clearness, to show each separate stage of the construction, 
 hence the necessity for repeating some of the views which might otherwise, as will 
 easily be seen, have been combined in one. 
 
 To find Propeller Pitch. — Allow 10 per cent, for apparent slip, and 
 proceed as follows : — 
 
 Rule. — 
 
 Knots X 6080 X 100 
 
 Rev. X 60 X effective per cent. 
 
 Pitch. 
 
 Therefore, 10x6080x100^ ^^^^ p.^^j^ 
 
 76 X 60 X 90 
 NOTE.— <5o8o feet= i knot. 
 
 60 min. = I hour. 
 
 100 - 10 = 90 per cent, effective advance. 
 
 Rule. 
 
 To find Propeller Diameter. 
 
 Constant K x ^ —Ij^L^—,, = Diameter. 
 
 V 100 / 
 
 Therefore, K 18 x ^ 7Tk7j6\^~^^'^^ ^^®*' °'" ^^^ "^ ^^^' Diameter. 
 V 100 / 
 
 NOTE.— K = Constant 18 in present case (see Seaton and Rounthwaite's 
 " Pocket-Book" for table of Constants). 
 6oo = I.H.P. 
 15 = pitch. 
 76 = revolutions. 
 
524 "Verbal" Notes and Sketches 
 
 To find Total Expanded Blade Area. — The total expanded blade 
 area is found as follows : — 
 
 Rule. — 
 
 C X /LlLf • = total Surface. 
 Sj rev. 
 
 Therefore, Constant 16 x /^^=^.g, or say 45 square feet. 
 
 NOTE. — C = Constant 16 in present case (see Seatonand Rounthwaite's " Pocket- 
 Book" for table of Constants). 
 600-I.H.P. 
 76 = revolutions. 
 
 To find Diameter and Length of Boss. — For a cast-iron propeller 
 with blades and boss solid, the diameter and length of tne boss are 
 found as follows : — 
 
 Rule. — Constant 2-7 x shaft diameter = boss diameter and boss 
 length, therefore 27x11= 29-7 inches, or say 30 inches diameter and 
 length of boss. 
 
 NOTE.— II inches = tail shaft diameter. 
 
 The boss diameter varies from J to ^ of propeller diameter. 
 The curve of boss radius is taken with a radius equal to boss 
 diameter x -8, therefore 30 inches x -8 = 24 inches radius for curve. 
 
 To find Blade Thickness. — The blade thickness, if continued to 
 the shaft centre line or axis, is found as follows : — 
 
 Rule. — 
 
 /^ 
 
 Shaft diameter^ ^ Constant 4 + -5 = Thickness. 
 
 Number of blades x boss length 
 
 Therefore, / ^— , — x4 + -5 = 6-5 inches thickness at shaft axis 
 
 \/ 4 X 30 inches 
 
 NOTE. — II inches = shaft diameter. 
 
 4 ,, = number of blades. 
 30 ,, = breadth of blade at boss (roughly). 
 
 The blade thickness near the tip is found as follows : — 
 Rule. — 
 
 Constant -04 x propeller diameter in feet + "4 = thickness. 
 Therefore, -04 x 11-5 + -4 = -86 inch, or say | inch thick near tip. 
 
 NOTE.— ii-5 = propeller diameter in feet. 
 
 To find Boss Thickni -The boss thickness at position of the 
 blades is found as followb 
 
 Rule. — 
 
 Constant -65 x blade thickness at shaft axis = thickness. 
 Therefore, -65 x 6-5 — 422 inches, or say 4^ inches thi<:k. 
 
 NOTE.— 65 inches = blade thickness at shaft axis. 
 
D BLAOED CAST IRON PROPELLER 
 
 SCALE i" PER FOOT 
 
 /5-^ 
 
 ETER //-6" 
 
 NDED BLADE AREA 4S SQUARE FEET 
 
 I RATIO = /5 ^//•5 = /'3 
 
 k RATIO = 45 ^ 1/5^ X 7854 =-43 
 
 >hape of Blade. — The standard shape o jlade takes the form of an 
 IHpse, but in practice various modifications of this are adopted, with 
 aore or less satisfactory results. Experience proves that difference in 
 ilade contour affects the efficiency but slightly, provided that the area 
 Iff blade is kept constant. 
 
SOLID BLADED CAST IRON PROPELLER 
 
 SCALE i" PER FOOT 
 
 PITCH /S-0 
 
 DIAMETER Z/'-s" 
 
 EXPANDED BLADE AREA 4S SQUARE FEET 
 
 PITCH RATIO = 15^11-5 = 1-3 
 
 AREA RATIO = 4-5 ^ l/-5^ X 7854 =45 
 
 6 BLADE PROJECTION 
 
 7. BLADE PROJECTION 
 
 8. PROJECTED BLADE AREA 
 (ACTUAL rHBUST AOEA) 
 
Propellers 525 
 
 To find Taper in Boss. — Allow the taper of shaft hole in boss to 
 be not less than f inch per foot of length. 
 
 Therefore, 25 feet x -75 inch = 1-875 inches taper, 
 and II inches 1875 inches = 9-i2S inches diameter at small end, or say 9 inches. 
 
 NOTE.— 30 inches = 2-5 feet = length of boss. 
 
 To find Dimensions of Key. — ^The width and thickness of the key 
 which secures the boss to the shaft are found as follows : — 
 
 Rule.— Shaft diameter ^.^^^-^^^^ ^^ ^^^ 
 6 
 
 Therefore, "+-6 = 2-4 inches, or say 2.\ inches in width. 
 6 
 
 Rule. — 
 
 Width of key X -5=: thickness of key. 
 Therefore, 25 x -5— 1-2 inches, or say i^ inches in thickness. 
 
 To find Dimensions of Nut. — The diameter and thickness of the 
 nut at back of boss are found as follows : — 
 
 Rule.— 
 
 Shaft diameter at screw x 1-5 = diameter of nut, therefore 8-5xi-5=i2f in. diam. 
 Shaft diameter at screw x -75 = thickness of nut, therefore 8-5 x -75=6^ in. thick. 
 NOTE.— 8-5 inches=shaft diameter at screw. 
 
 To find Single Blade Expanded Area. — As there are four blades, 
 the area of one blade is found as follows : — 
 
 Total blade area^4 = one blade area. 
 Therefore, 45-^4=11-25 square feet surface for one blade. 
 NOTE.— 45 square feet = total blade area. 
 
 To find Blade Length. — Half of the boss diameter subtracted from 
 half of the propeller diameter will give the blade length : — 
 Therefore, 11-5-^2 = 5-75 feet, and 2-5 ^2 = 1-25; 
 then 5-75-i"25 = 4-S feet length of blade. 
 
 NOTE.— 11-5 feet = propeller diameter. 
 2-5 ,, =boss diameter. 
 
 To find Width of Blade Area Rectangle. — The single blade area 
 divided by the blade length will give the mean width of the blade area 
 rectangle. 
 
 Therefore, 11-25-^4-5 = 2-5 feet width. 
 NOTE. —11-25 square feet = single blade area. 
 4-5 feet = blade length. 
 
 Shape of Blade. — The standard shape of blade takes the form of an 
 ellipse, but in practice various modifications of this are adf)ptcd, with 
 more or less satisfactory results. Experience proves that difference in 
 blade contour affects the efficiency but slightly, provided that the area 
 of blade is kept constant. 
 
52^ 
 
 To 
 
 are; 
 
 The 
 
 To 
 
 with 
 four 
 
 leng 
 leng 
 
 To 
 
 the 
 
 Ther 
 
 Tl 
 N 
 
 To 
 
 Rule. — 
 
 Constant -65 x blade thickness at shaft axis = thickness. 
 Therefore, •65x6-5 = 422 inches, or say 4^ inches thi<:k. 
 
 NOTE.— 65 inches = blade thickness at shaft axis. 
 
 3 n_»ujn.i a.T njin->vvo 
 
Propellers 525 
 
 To find Taper in Boss. — Allow the taper of shaft hole in boss to 
 be not less than f inch per foot of length. 
 
 Therefore, 25 feet x 75 inch=^i-875 inches taper, 
 and II inches 1875 inches = 9'i25 inches diameter at small end, or say 9 inches. 
 
 NOTE.— 30 inches = 2-5 feet = length of boss. 
 
 To find Dimensions of Key. — The width and thickness of the key 
 which secures the boss to the shaft are found as follows : — 
 
 j^ULE.— Shaft diameter^.g^^.^^;^ ^^ ^^^ 
 6 
 
 Therefore, y + '6=2-4 inches, or say 2\ inches in width. 
 6 
 
 Rule. — 
 
 Width of key X -5 = thickness of key. 
 Therefore, 25 x -5 = 1-2 inches, or say \\ inches in thickness. 
 
 To find Dimensions of Nut. — The diameter and thickness of the 
 nut at back of boss are found as follows : — 
 
 Rule. — 
 
 Shaft diameter at screw x 1-5 = diameter of nut, therefore 8-5xi-5 = i2| in. diam. 
 Shaft diameter at screw x -75 =^ thickness of nut, therefore 8-5 x -75=: 6^ in. thick. 
 NOTE.— 85 inches = shaft diameter at screw. 
 
 To find Single Blade Expanded Area. — As there are four blades, 
 the area of one blade is found as follows : — 
 
 Total blade area -^ 4 = one blade area. 
 Therefore, 45 -f4 = 11-25 square feet surface for one blade. 
 NOTE. — 45 square feet = total blade area. 
 
 To find Blade Length. — Half of the boss diameter subtracted from 
 half of the propeller diameter will give the blade length : — 
 
 (Therefore, ii-5^2 = 5-7S feet, and 2-5-^2 = 1-25; 
 then 575-i'25 = 4-S feet length of blade. 
 
 NOTE. — 1 1-5 feet = propeller diameter. 
 2-5 ,, =boss diameter. 
 
 To find Width of Blade Area Rectangle. — The single blade area 
 divided by the blade length will give the mean width of the blade area 
 rectangle. 
 
 Therefore, 11-25 -^4-5 -25 ^^^^t width. 
 NOTE. —11-25 square feet = single blade area. 
 4-5 feet = blade length. 
 
 Shape of Blade. — The standard .shape of blade takes the form of an 
 ellipse, but in practice various modifications of this are adopted, with 
 more or less satisfactory results. Experience proves that difference in 
 ' blade contour affects the efficiency but slightly, provided that the area 
 of blade is kept constant. 
 36 
 
526 "Verbal" Notes and Sketches 
 
 Set Back. — Allow a " set back " of blade equal to about i inch per 
 foot of propeller diameter, or say 12 inches in all, at tip. 
 
 Radial Pitch Angles and Thickness Templates. — In a working 
 drawing the pitch angles and thickness templates at various radial 
 distances on the blade require to be shown for the fitting up of the 
 shop moulding templates, and as the length of blade from centre of 
 boss to tip is equal to the radius of the circumference circle, the 
 corresponding reduced pitch distance will be equal to the full pitch 
 divided by 2 x 3-1416 ; hence, 
 
 15 -=-2x3-1416 = 2-38 feet, or 2 feet 4^ inches. 
 
 NOTE. — This distance of 2 feet 4^ inches requires to be measured horizontally 
 from the boss centre, and all lines from radial points on the blade drawn to it. 
 
 Summary of Results. 
 
 The principal dimensions as found by the foregoing rules are then 
 as follows : — 
 
 Propeller pitch . . . - - 
 
 „ diameter ----- 
 Expanded blade area - - . . 
 
 Single blade area ----- 
 Boss diameter ----- 
 
 „ length - - - . . 
 
 ,, taper ------ 
 
 Breadth of key - - - 
 
 Thickness of key ----- 
 
 Nut diameter . . - . - 
 
 „ f'hickness ----- 
 
 Pitch angle distance - . - - 
 
 Length of blade area rectangle 
 Width of ,, „ 
 
 Set back of blade . - - - - 
 
 Blade thickness at shaft axis . . - 
 
 „ „ near tip - - - - - | „ 
 
 Boss thickness - - - - - 4:^ ,, 
 
 To Draw the Propeller (Sketch No. 12), 
 
 The following method, it should be noted, is not mathematically 
 correct (particularly in the case of the " projected area " view), but is 
 quite near enough for practical purposes as required in a working 
 drawing. For the shop moulding of a propeller the projected ares 
 view is not required. 
 
 - 
 
 15 
 
 ft. 
 
 II 
 
 ft. 6 
 
 in. 
 
 - 
 
 45 sq. 
 
 ft. 
 
 r I 
 
 25 „ 
 
 2 
 
 ft. 6 
 
 in. 
 
 r, 
 
 6 
 
 
 " 
 
 )> ^ 
 
 ») 
 
 in 
 
 . to 9 
 
 )> 
 
 - 
 
 2I 
 
 )) 
 
 - 
 
 4 
 
 >) 
 
 - 
 
 I2| 
 
 5t 
 
 - 
 
 6i 
 
 )) 
 
 2 
 
 ft. 4I 
 
 !5 
 
 4 
 
 „ 6 
 
 „ 
 
 2 
 
 „ 6 
 
 )) 
 
 - 
 
 12 
 
 ., 
 
 - 
 
 6.^ 
 
 ,, 
 
 I. Blade Area Rectangle. — Set off the horizontal shaft centre line 
 and the vertical centre line of the boss, then from the centre of boss 
 with a 1 5-inch radius, describe the circle of the boss diameter, 30 inches 
 also measure up from the shaft centre line half of the propellei 
 
 i 
 

 Propellers ' 527 
 
 diameter, or 5 feet 9 inches. Next measure on each side of the boss 
 centre h'ne half of tlie blade rectani^de width, i foot 3 inches, and 
 complete the rectangle as shown. Now proceed to sketch in by hand 
 the approximate shape of the blade, taking care that the actual 
 surface of blade when drawn in is at least equal to the original 
 rectangular area, A good plan is to divide off the blade area 
 rectangle into a number of divisions, horizontally and vertically, 
 counting up the total number, and after the blade is shaped out as 
 desired, arrange that the actual area of blade contains the same 
 number of division':, 
 
 2. Blade and Boss Thickness. — Set off the length of the boss, 
 30 inches, and the diameter of the boss, also 30 inches, then complete 
 the boss outside curve with a 24-inch radius. Next draw in the taper 
 of the hole in the boss 1 1 inches to 9 inches. Then set off aft at the 
 propeller tip the " set back "of 12 inches, and draw a line for the face 
 of the blade through the boss curve at the vertical centre line, and 
 from where this inclined line cuts the shaft centre line measure forward 
 the thickness of blade at shaft axis (6i inches). At the blade tip also 
 measure forward the thickness at that position, that is | inch, and 
 draw a line /'^rnr/Zs?/ to the face of blade line. To complete the blade 
 section, draw another line from the thickness at shaft axis (6| inches) 
 to the tip of propeller, then run the two thickness lines into each other 
 by a suitable curve as shown in the drawing, and join the blade at the 
 root to the boss at the forward side by a large fillet of, say, 6 inches 
 radius. The hollow cast part of the boss is shown as 14 inches in 
 length, as this leaves sufficient strength of metal fore and aft. 
 
 3. Pitch Angles and Thickness Templates. — Begin this view 
 by again drawing in the complete boss and blade as in .view i, and 
 set off any convenient number of divisions from the beginning of the 
 blade radius at root. The first is at 18 inches from the centre, and 
 the others, Nos, 2, 3, 4, 5, are at equal distances of 12 inches. Draw 
 horizontal lines, and where these lines cut through view 2, the thick- 
 ness of blade at each division will be found. Transfer the various 
 thicknesses to view 3, and complete the thickness sections by drawing 
 in radial curves for the back of the blade or forward surface. Observe 
 that near the root the after edges are slightly rounded away to allow 
 a free flow of water past the blade. Next measure to the right the 
 pitch angle distance of 2 feet 4^ inches, and from each radial point 
 draw lines to it as shown ; this gives the required pitch angles at the 
 differentradial positions marked. 
 
 4. Boss, Key, and Nut. — This view will be easily drawn, as the 
 dimensions are simply taken from the " Summary of Results," and 
 measured off. Observe that the screw for the nut is left-handed for 
 a right-hand propeller, to keep the propeller hard up when the shaft 
 is revolvintr. 
 
528 " Verbal " Notes and Sketches 
 
 5. Nut. — The nut shown has four small projections 3 inches wide, to 
 allow of the luit being screwed on or off. 
 
 6. Blade Projection. — As usual set off the propeller radius of 5 feet 
 9 inches, and the various divisions, i, 2, 3, 4, 5, from view 3, and draw 
 long horizontal lines. Now complete the external view of the boss 
 and the blade angle centre line at the set back of 12 inches from tip. 
 At each of the divisions marked, Nos. i, 2, 3, 4, 5, drop down vertical 
 lines from each intersection of the blade angle line with the horizontal 
 division lines, and where these vertical lines cut the shaft centre, set 
 off the corresponding blade angle at that position, which requires to 
 be transferred from view 3, so that at position i on shaft centre the 
 angle is that marked i on view 3 ; at position 2 the angle is that 
 marked 2 on view 3, and so on for each of the five radial points, which 
 gives the projected lines of the horizontal blade as seen looking from 
 the starboard side. On each of these angle lines set off the half width 
 of blade, measured from view 3, and, taking No. 2 as an example, note 
 that the width across B in view 3 is the same as B in view 6. Repeat 
 this blade width measurement at each of the radial positions i, 2, 3, 
 4, 5, and then through the points so found draw in, first by hand and 
 afterwards with a " French curve," the blade contour. 
 
 NOTE. — " French curves " are wooden shapes used in drawing when the contour 
 required does not readily allow of the use of radial curves, and are very convenient 
 for use in propeller design. " French curves " are obtainable at shops where drawing- 
 instruments are sold, and the purchase of one or two is recommended. 
 
 7. Blade Projection. — In this view transfer the previous view of the 
 boss and blade complete, and run up lines from the various blade 
 widths at the radial points i, 2, 3, 4, 5, and observe where the vertical 
 lines so drawn cut the corresponding radial horizontal lines ; mark 
 these points with a dot or a small cross, and if this is done for each 
 of the varying widths of blade, the curve can then be drawn in by 
 hand, and afterwards (as before) completed more carefully with thei 
 " French curves." Notice that the width of blade at B (No. 5 radial 
 line) in the vertical view of the blade is run up from the horizontal 
 view of the blade also marked B, and each width is similarly treated. 
 
 8. Projected Blade Area. — This view is fairly simple in construction 
 and requires very little explanation. Set off the various circles of the 
 tip of blade, radial points of blade and boss, then project over, by 
 lines from view 7, the various widths of the blade at the same radial 
 points I, 2, 3, 4, 5, and where these lines cut the radial curves of 
 view 8, mark small dots or small crosses ; if these points be then 
 connected by hand curves, the approximate shape and width of the 
 blade, looking from aft forward, will be shown. After completing 
 the horizontal blade, merely transfer the widths, &c., to the vertical 
 blade and complete it also. As before mentioned, in speaking of 
 other views, the blade contour can be better finished by the use of 
 '• French curves." Observe that width B on radial line 5 of view 7 
 corresponds to width B on radial curve 5 of view 8. 
 
Propellers 529 
 
 To Fit on a New Propeller Blade. — If, in a loose bladcd propeller, 
 a blade is knocked off at sea, the spare blade can be placed at the 
 correct pitcii angle by the follo\vin<^ method : — With the steamer in 
 dry dock turn the entwines until one of the remaining blades is in 
 an upright or vertical position. Then with a straight-edge placed 
 against the stern post, and at a convenient radius, R, mark the blade 
 at the leading edge A ; shift the straight-edge to the other side of the 
 blade, and mark the following edge B. Now turn the shaft round 
 until the surface of the boss to receive the spare blade is in position, 
 and when the new blade is placed on the boss turn round the 
 flange until the leading and following edges coincide with the 
 marks on the straight-edge, which in the meantime must be held 
 or fixed up against the stern post at the same radius R, The new 
 blade will tiicn have the correct pitch angle, and the studs may be 
 sciewed up. 
 
 NOTE. — The foreg-oing method is necessary when the stud holes in the flange 
 are cut oval to allow of pitch variation. 
 
 To find the Pitch when the Propeller is in the position shown 
 
 I (on the surface table or shop floor). — Fit up two set-squares and 
 
 i, a horizontal piece of wood as shown, at a suitable radius R (say 
 
 ' about two-thirds out from boss to give average pitch) ; then the 
 
 piece of pitch P will be obtained by the vertical measurement, and 
 
 the piece of circumference C by the horizontal or floor measure- 
 
 ent. 
 
 f 
 
 And Rx 2 X 3-14 16 = full circumference at radius R. 
 
 To find corresponding pitch — 
 
 As C : full circumference : : P : full pitch. 
 
 NOTE. — If the blades have a varying pitch, repeat the above at two or three 
 radial positions, and take the mean of the two or three pitches so found as the 
 average pitch. 
 
530 
 
 " Verbal " Notes and Sketches 
 
 No. 13. — Fitting on a New Blade. 
 
handle. It will thus be seen that the engines always run in the 
 same direction. 
 
 Blade Interference. — B>' this is meant the effect produced by one 
 blade on another blade acting on the water in such a manner as to 
 break up the surface, and thus cut out or rob the next blade of its 
 
TURBINE TYPE PROPELLER 
 
 SCALE i" PER FOOT 
 
 PITCH ■_ S'-O" 
 
 DIAMETER b'-7" 
 
 EXPANDED BLADE AREA..JI-8 SQUARE FEET 
 
 PITCH RATIO -89 
 
 AREA RATIO -48 
 
 No. 15 19. 
 
 {r,</„., f,ix' 530- 
 
Propellers 
 
 531 
 
 Motor Launch Propellers. — In oil motor launches the two-bladed 
 propellers usually fitted arc often of the reversible kind, that is, the 
 blades are so arran<Ted that their angles can be changed as desired, to 
 "stop" or "astern " or "ahead." In the "stop" position the blades 
 lie at right angles to the centre line of the ship, and for "ahead" the 
 blades are moved round with the leading edge forward, while for 
 "astern" t\\c blades are turned round with the leading edge aft. These 
 
 No. 14.— Pitch with Propeller Horizontal 
 
 changes in blade position are obtained by means of a rod passing 
 through the hollow tail-end shaft, the rod being operated by a suitable 
 handle. It will thus be seen that the engines ahvays run in the 
 same direction. 
 
 Blade Interference.^ — B)' this is meant the effect produced by one 
 blade on another blade acting on the water in such a manner as to 
 break up the surface, and thus cut out or rob the next blade of its 
 
Propellers 
 
 531 
 
 JMotor Launch Propellers. — In oil motor launclies the two-bladed 
 Ipropellers usually fitted arc often of the reversible kind, that is, the 
 Iblades arc so arrant^cd that their angles can be changed as desired, to 
 "stop" or "astern " or "ahead." In the "stop" position the blades 
 lie at right angles to the centre line of the ship, and for " ahead " the 
 blades are moved round with the leading edge forward, while for 
 ''astern" tlie blades are turned round with the leading edge aft. These 
 
 No. 14. — Pitch with Propeller Horizontal 
 
 changes in blade position are obtained by means of a rod passing 
 through the hollow tail-end shaft, the rod being operated by a suitable 
 handle. It will thus be seen that the engines always run in the 
 same direction. 
 
 Blade Interference. — B}' this is meant the effect produced by one 
 blade on another blade acting on the water in such a manner as to 
 break up the surface, and thus cut out or rob the next blade of its 
 
^'itiMtf - 
 
 K- 
 
 'V. ! 
 ■ 1 1 
 
 Improved Propeller. — A case which came under tlic writer's notice 
 gave the following data, and clearly indicates the fact that propeller 
 design, in many cases, is more or less a matter of " trial and error," 
 
Pitch of Propeller 
 
 To measure the pitch of a propeller lying on the floor as shown, proceed as follows :- 
 
 4. Shift the long straightedge through one 
 division of the boss marks (or ^), as shown at 
 position c, and again measure down to the blade 
 
 S- Subtract the two measurements in inches, 
 and the difference is the mean pitch infect. 
 
 1. Mark off the face of the boss into twelve 
 equal divisions. . . 
 
 2. Take a long straightedge, and place it m 
 line with two oppositely placed divisions, as at 
 position B. 1 ,• \ 
 
 3. Take another straightedge (or plumb Ime) 
 and measure the distance down from the long 
 straightedge to the blade surface at a radius R, 
 taken at, say, | out from the boss centre. 
 
 In the sketch shown the first measurement is 4 in. and the second measurement .8 in. 
 
 Therefore, 18 inches -4 inches =14 fe«t pitch. 
 
 It will easily be seen that the difference of the measurements is equal to A of the pitch only. 
 
 Therefore, 14 inches x 12 inchea=i«8 inches pitch, and ^ inches=i4 feet 
 
 The .2 above the line and the .2 below the line cancel out in all cases, thus leaving the difference 
 in inchts exactly equal to the pitch in feet. 
 
 NOTE.-The above method c«. also be applied with the propeller in the usual position on the shaft. 
 
 \Tc fact page 532- 
 
ProDellers 
 
 >oo 
 
 effective thrust. For this reason an improvement is sometimes effected 
 by chan_L;"in^i^ a four-blarlcd pro[)eiler for one of three blades, and, it 
 ma)' be noted, that this ciian^Lje has been made in the case of the 
 turbine steamer " Victorian." 
 
 Blade interference has not, as )'et, been fully investigated by 
 experiment, and is therefore at present largely a matter of speculation. 
 
 Twin Screws. — In twin-screw steamers it has been observed that in 
 most cases the starboard engine runs at a higher revolution speed than 
 the port engine, and this ma)- be due to some effect of blade inter- 
 ference reducing the efficienc)' of one of the propellers. 
 
 Effect on Steering. — The steering is found to be improved if in 
 twin-screw steamers the propellers revolve outwards from each other, 
 instead of inwards, that is, the port engine propeller to be a left-hand 
 screw, and the starboard engine a right-hand screw. The propellers 
 also develop a more effective thrust, as the blades work in unbroken 
 u'ater. 
 
 Surface of Blade. — It has recently been proved be)'ond doubt that 
 a polished blade surface increases the efficiency of the propeller. 
 This is fully recognised in turbine propulsion, as nearl)' all propellers 
 htted to turbine steamers have highl)^ polished surfaces. 
 
 In a case which came under the writer's notice, an increase of one 
 knot was obtained, for the same power and consumption, b)- changing 
 a cast-iron propeller for one of polished bronze. 
 
 NOTE. — If the propeller pitch is increased by, say, i or 2 feet, the mean 
 pressure of the indicator diagrams will be more if the engine develops the same 
 power with reduced revolutions, and the ship runs at the same speed. 
 
 Bronze Propeller Blades and Corrosion. 
 
 With bronze propeller blades the chemical conditions are much 
 like those of an electric batter)', the steel stern posts and hull forming 
 one electrode, the bronze propeller blades the other, and the salt 
 water the solution of the battery. As the propeller is the positive 
 terminal and the ship the negative terminal, the current flows 
 from the ship to the propeller, causing pitting of the steel hull. 
 In order to overcome this galvanic action, zinc plates are fitted, in 
 single-screw ships to the after face of the stern posts, and in twin- 
 screw ships fitted round the after propeller bracket. This arrange- 
 ment does not prevent galvanic action, but such action takes place 
 between the propeller blades and the zinc plates instead of between 
 the propeller blades and the steel plates of the steamer. 
 
 Improved Propeller. — A case which came under the writer's notice 
 gave the following data, and clearly indicates the fact that propeller 
 design, in many cases, is more or less a matter of " trial and error," 
 

 ^ Q I- 
 
 O ^ 
 
 OH 
 
 GO 
 
Propellers 533 
 
 (effective thrust. For tliis reason an improvement is sometimes effected 
 b)' chancjini^ a four-bladed propeller for one of three blades, and, it 
 may be noted, that this chan<;e has been made in the case of the 
 turbine steamer " Victorian." 
 
 ]31ade interference has not, as }'et, been full)' investigated by 
 experiment, and is therefore at present largely a matter of speculation. 
 
 Twin Screws. — In twin-screw steamers it has been observed that in 
 most cases the starboard engine runs at a higher revolution speed than 
 the port engine, and this may be due to some effect of blade inter- 
 ference reducing the efficienc}' of one of the propellers. 
 
 Effect on Steering. — The steering is found to be improved if in 
 twin-screw steamers the propellers revolve outwards from each other, 
 instead of inwards, that is, the port engine propeller to be a left-hand 
 screw, and the starboard engine a right-hand screw. The propellers 
 also develop a more effective thrust, as the blades work in unbroken 
 uater. 
 
 Surface of Blade. — It has recently been proved beyond doubt that 
 a polished blade surface increases the efficiency of the propeller. 
 This is fully recognised in turbine propulsion, as nearly all propellers 
 fitted to turbine steamers have highly polished surfaces. 
 
 In a case which came under the writer's notice, an increase of one 
 knot was obtained, for the same power and consumption, b\- changing 
 a cast-iron propeller for one of polished bronze. 
 
 NOTE. — If the propeller pitch is increased by, say, i or 2 feet, the mean 
 pressure of the indicator diagrams will be more if the engine develops the same 
 power with reduced revolutions, and the ship runs at the same speed. 
 
 Bronze Propeller Blades and Corrosion. 
 
 With bronze propeller blades the chemical conditions are much 
 like those of an electric batter}', the steel stern posts and hull forming 
 one electrode, the bronze propeller blades the other, and the salt 
 water the solution of the battery. As the propeller is the positive 
 terminal and the ship the negative terminal, the current flows 
 from the ship to the propeller, causing pitting of the steel hull. 
 In order to overcome this galvanic action, zinc plates are fitted, in 
 single-screw ships to the after face of the stern posts, and in twin- 
 screw ships fitted round the after propeller bracket. This arrange- 
 ment does not prevent galvanic action, but such action takes place 
 between the propeller blades and the zinc plates instead of between 
 the propeller blades and the steel plates of the steamer. 
 
 Improved Propeller. — A case which came under the writer's notice 
 gave the following data, and clearly indicates the fact that propeller 
 design, in many cases, is more or less a matter of " trial and error/' 
 
534 "Verbal" Notes and Sketches 
 
 as notice the great improvement effected by the increase of blade 
 area and of pitch, and the alteration in blade material, shown as 
 follows : — 
 
 With Original Propeller. 
 
 Diameter, i8 feet 6 inches. ^ 
 
 Pitch, 1 8 feet 6 inches. 
 
 Expanded blade area, 98 square feet. 
 
 Revolutions, 72 to 75. 
 
 Cast steel blades. 
 
 Consumption, 52 to 55 tons per day. 
 
 Speed, about 11-5 to 11-75 knots. 
 
 Slip per cent., 15 to 30 per cent. 
 
 I.H.P., about 3300. 
 
 With New Propeller. 
 
 Diameter, 18 feet 6 inches. 
 
 Pitch, 20 feet. 
 
 Expanded blade area, 104 square feet. 
 
 Revolutions, 64 to 66. 
 
 Bronze blades (polished). 
 
 Consumption, about 40 to 45 tons per day. 
 
 Speed, 12 knots. 
 
 Slip per cent., 5 to 10 per cent. 
 
 I.H.P., about 2800. 
 
 From the foregoing it is evident that the original propeller was 
 not absorbing the full power of the engines, and the alteration made 
 in increased pitch and surface utilised more effectively in propulsive 
 effort the I.H.P. developed. Notice that the consumption, and there- 
 fore the I.H.P., developed is less in the second case, and the speed 
 rather more. 
 
 The above rather striking results were therefore obtained b)' — 
 
 (i.) Increasing the pitch, with slight pitch variation. 
 
 (2.) Increasing the expanded blade area. 
 
 (3.) Changing the material of the blades from steel to that of 
 polisJied bronze, which allows of thinner blades. The 
 polishing of the blade surface and thinning down of the 
 thickness both contribute to increased propeller efficienc}-. 
 
 ' It is, of course, difficult to accurately estimate how much each of 
 the foregoing alterations contributed individually to the resulting 
 general improvement in propulsive efficienc)-. 
 
 Propulsive Efficiency. 
 
 Of the total I.H.P. developed by the engines only about 50 per 
 cent, or thereabout is applied in the effective advance of the steamer 
 
Propellers 535 
 
 when the various losses are eliminated — that is, the actual iiull 
 resistance in lbs. at any given speed, multiplied by the advance of 
 the hull per minute and divided by the constant 33,000 foot-pounds, 
 will give the effective horse-power, or, as usually expressed, the E.H.P. 
 Therefore, E.H.P. -=- I.M.P. = Propulsive efficienc}'. This efficienc)- can 
 only be accurately determined by model tank experiments of re- 
 sistance, after which the data so obtained is converted into terms of 
 the actual hull by a series of calculations known as the " law of 
 comparison," and devised by the late Dr Froude. The tank experi- 
 ments with the reduced scale hull models obtain progressive " tow 
 rope " resistances which are the actual resistances at various speeds of 
 the model hull (the propeller being omitted). These are made up 
 as follows : — 
 
 Resistance. — i. Skin frictional resistance of the hull surface. 2. 
 Wave making resistance of the hull body. 3. Eddy making resistance 
 of the hull bod}'. 
 
 The foregoing constitute what may perhaps be termed the true 
 resistances, and to overcome these the effective horse - power is 
 required. 
 
 Power Losses. — The losses of engine power are made up as 
 follows : — 
 
 1. Friction (initial and load). 
 
 2. Propeller inefficiency. 
 
 3. Hull inefficiency. 
 
 The frictional losses are those occasioned b}' the working parts and 
 the power absorbed by the thrust block. The propeller losses are 
 due to excessive slip, blades friction, and other causes, and the hull 
 efficiency is a result w^hich may either be under or above unity, 
 according to the difference between what is called "augmentation of 
 resistance," due to the propeller blades at the stern, and " wake speed 
 gain." Generally, however, the " wake speed gain " balances the 
 augment of resistance to within a ver}' few per cent., although an 
 allowance of about 95 per cent, is often taken as the " hull 
 efficiency." 
 
 The " wake speed " is produced by the water closing in on the 
 stern as the hull advances, and this body of water acquires a forward 
 motion or speed varying in degree with the lines of the hull body. 
 
 Utilisation of Power. — The total I.H.P. developed by the engines is 
 therefore used up somewhat as follows, although it must be understood 
 that the values given var)' in different cases and under different 
 conditions in the same case : — 
 
 Taking the total I.H.P. as 100 per cent. 
 
536 "Verbal" Notes and Sketches 
 
 Reciprocating Engines. 
 
 Indicated horse-power 
 
 - 
 
 
 100 per 
 
 cent. 
 
 Engine friction loss 
 
 - 
 
 
 10 
 
 )) 
 
 Horse-power at propeller - 
 
 - 
 
 
 90 
 
 )) 
 
 Propeller efficiency, 62 per cent. 
 
 
 
 
 Then, 90 x ■62 = 55-8 ,, 
 
 
 
 
 
 Horse-power by propeller - 
 
 - 
 
 
 55-8 
 
 j> 
 
 Hull efficiency, 95 per cent. 
 
 
 
 
 
 Then, 55-8 x -95 = 53 » 
 
 
 
 
 
 Effective horse-power 
 
 - 
 
 
 53 
 
 >/ 
 
 Therefore, propulsive 
 
 efficiency = 
 
 _53 
 100' 
 
 or -SS- 
 
 
 Turbine 
 
 Engines 
 
 
 
 
 Shaft horse-power - 
 
 - 
 
 
 100 per 
 
 cent, 
 
 Propeller efficiency, 60 per cent. 
 
 Then, 100x60 = 60 ,, 
 
 Horse-power by propeller - - - - 60 „ 
 
 Hull efficiency, 95 per cent. 
 
 Then, 60x95 = 57 
 Effective horse-power - - - - 57 n 
 
 Therefore, propulsive efficiency = ^^, or -57. 
 
 The following explanations of propeller slip are taken from a 
 paper on " Screw Propellers," read by T. Sidney Cockrill, Esq. 
 M.I.Mech.E., before the Liverpool Engineering Society in April 1907 
 and are well worthy the attention of students. 
 
 "Slip. — The slip is the difference between the speed of advance of 
 the propeller (supposing it to be working in an unyielding substance) 
 and the actual speed of the ship. In other words, it is equal to the 
 pitch multiplied by the revolutions, less the distance traversed by the 
 ship. If the water did not yield to the propeller and flow sternward, 
 the speed of the ship would be the same as the speed of the propeller, 
 and there would be no such thing as slip ; but water, being a fluid, is 
 driven astern by the action of the propeller as the ship moves ahead. 
 The rate at which the water is driven astern relatively to the 
 surrounding water is usually said to be equal to the slip ; but this is 
 only true provided the pitch multiplied by the revolutions is equal to 
 the speed of the race relatively to the ship, or, in other words, provided 
 the propeller itself does not slip in the race. As far as the author can 
 see, we have no means of ascertaining the truth of this. 
 
 " The above, however, only relates to apparent slip, for it does not 
 take account of the fact that the propeller is not working in still 
 water, but in water in motion in a forward direction owing to the 
 influence of the ship in passing through it ; and, as it is the propeller 
 that is under consideration, the speed of the propeller and not the 
 
Propellers 537 
 
 speed of ship through the water should be the basis in calculating 
 the slip. 
 
 " F'or example, if the pitch were 15 feet, the revolutions Si per 
 minute, and the speed of ship 11 knots: — 
 
 Then, Speed of propeller = ^^^= '5 ;8i x 60^ ^^ ^^^^^ 
 
 '^ ^ 6080 6080 
 
 Speed of ship - - - - =11 ,, 
 
 Apparent slip of propeller - — i knot. 
 
 But supposing the wake to have a speed of two knots, 
 
 Then, Speed of propeller, as before= — ^-/— =12 knots. 
 
 '^ 6080 
 
 Advance of propeller through the water 
 
 in which it works — V-7w = ii -2 - =9 ,, 
 
 ' Real slip ' of propeller - - - - 3 knots. 
 
 "It is sometimes found that a propeller seems to have negative 
 slip, that is to say that the speed of the ship is (apparently) greater 
 than the speed of the propeller which drives it. This negative slip is 
 only found when the speed of the ship is taken instead of the speed 
 of the propeller through the water ; it is the apparent slip, not the 
 real slip of the propeller. 
 
 " The phenomenon of negative slip is the cause of a vast amount 
 of ingenious, if not always scientific, hypotheses to account for its 
 existence. Everyone agrees that negative real slip is a physical 
 impossibility. In the author's humble opinion negative apparent 
 slip is also a physical impossibility, and, therefore, there is no need to 
 account for a thing which does not exist. This is on the under- 
 
 P X R 
 standing that ' apparent slip ' means — ^ — - — V while ' real slip ' means 
 
 Px R 
 
 — 5^— — (V — zty); these are the usual definitions of the terms, and 
 60 
 
 they are given here to prevent misunderstanding arising from the 
 mere meaning of words. The explanation is simple enough, for, in 
 order to calculate the slip, the pitch P must first be known ; it is one 
 of the factors in the calculation, and, in the author's opinion, no one 
 knows what the true effective pitch of a propeller is. What is usually 
 taken as the pitch of a propeller is the pitch of the after face of the 
 blade, or, rather, the mean of the various pitches found at different 
 parts of the after faces of the blades. This is certainly not the 
 effective pitch of the propeller with respect to its action on the water, 
 one reason at least for this being that it takes no account of the 
 curved back of the blade, and it is certain that this increases the true 
 effective pitch, although no one knows exactly, or even ap[jroximately, 
 what value is to be assigned to it. There are also other reasons for 
 
538 "Verbal" Notes and Sketches 
 
 supposing that vvc do not know what the effective pitch of a 
 propeller is. 
 
 " The cause of negative slip often given is that the propeller is 
 working in the wake of the ship, and, therefore, working in water 
 which has a forward motion. 
 
 " For example of this reasoning we may take the previous example, 
 supposing the speed of the ship to be 13 knots, and the speed of the 
 wake 4 knots. 
 
 Then, Speed of propeller, as before - 12 knots. 
 
 Speed of ship- - - - 13 >. 
 
 Apparent slip of propeller - - - i knot. 
 
 And Speed of propeller, as before 12 knots. 
 
 Advance of propeller through the water = i3-4 = 9 ,, 
 
 • Real slip ' of propeller - - 3 knots." 
 
SECTION IX. 
 
 REFRIGERATION. 
 
 The Ammonia Compression System. 
 
 Anh}drous ammonia has found great favour as a refrigerating 
 medium on account of its high latent heat of vaporisation and the 
 comparatively low pressure at which it can be liquefied. The idea 
 involved in an ammonia refrigerating plant may be explained as 
 follows : the same, however, holds good for machines using carbonic 
 acid, sulphurous acid, ether, &c. : — Anhydrous ammonia, i.e., ammonia 
 free from all water or moisture, is naturally a gas. Under pressure 
 and cooling by water it may easily be condensed to liquid form. It 
 is almost colourless, and in appearance just like water, and weighs 
 at ordinary temperatures about 'i^J lbs. per cubic foot. In this form 
 it may be purchased in steel cylinders or drums containing from 
 50 to 100 lbs. in weight. If the pressure be relieved from the 
 liquid ammonia it will quickly revaporisc, producing as it does so 
 intense cold. 
 
 An ammonia refrigerating machine consists of the following 
 principal parts : — 
 
 («.) A vaporiser, evaporator, or refrigerator — a vessel in which 
 the ammonia is allowed to vaporise, producing a low temperature 
 and surrounded either by the air or brine to be cooled. 
 
 ib?) A gas pump or ammonia compressor which draws the 
 ammonia gas from the refrigerator and compresses it into the 
 condenser. 
 
 (r.) The ammonia condenser in which the gas discharged from 
 the compressor is condensed to liquid form ready for vaporisation 
 jn the refrigerator. The diagram (No. i) will further explain this 
 paragraph. 
 
 It should here be explained that the ammonia in vaporising under 
 low pressure in the refrigerator, changing its form from liquid to gas, 
 must absorb into itself the latent heat of vaporisation. This is taken 
 from the brine surrounding the coils — or in the case of direct expansion, 
 from the air itself — and in condensing to liquid form again this heat 
 is given up to the condensing water. The pressure necessary to 
 
 539 
 
540 
 
 "Verbal" Notes and Sketches 
 
 condensation is automatically regulated by the temperature of the 
 condensing water, and will vary from lOO to 200 lbs. pressure per 
 square inch. The pressure in the refrigerator is controlled by the 
 
 I 
 I 
 
 i 
 1 
 
 I 
 
 o 
 F: 
 
 1 
 
 O 
 
 regulating valve, which is adjusted according to the temperature 
 required, and varying from 70 lbs. absolute per square inch for a 
 vaporising temperature of 40' Fahr. to 20 lbs. absolute per square inch 
 
[ 
 
•CONDENSER 
 
 No. lA Compressic 
 
 lAmmoni 
 
 CO. System. 
 
 Caibonic anhydride {(JU^), iiiUurally ;i gas, and obtained fiuni the following 
 
 1. Natural springs. 
 
 2. Combustion of carbon. 
 
 3. Action or sulphuric acid on calcium carbonatL-. 
 
 4. Fermentation of wort in brewing processes. 
 
 Tlie gas collected from these sources is first purified and dried, then com- 
 pressed in stages, next cooled to the liquid state, and finally forced into steel 
 bottles for supply purposes. As the COo is under pressure in the bottles, it 
 remains in the liquid condition until the pressure is reduced. 
 
 When charging up the machine it evaporates back into gas by L-xpansion, 
 and enters the evaporation coils in that condition. 
 
 Latent heat value per lb. <at average evaporator pressures) = 125 B,T. U. 
 
 Boiling point at atmospheric pressure = — 120 F 
 
 Critical temperature = 88-4 F 1 Latent heat falls off in value from this 
 temperature up 1 
 
 LO, is heavier than air. 
 
 Ammonia (NH,) System. 
 
 Ammonia, an alkali, and naturally a gas, is obtained by ihe healing of 
 sal ammoniac and cjuicklimc mixtures, or by the forced decomposition of 
 animal substances. 
 
 The gas is collected and treated similarly to CO^ gas as regards com- 
 pression, cooling, and storing in steel bottles. 
 
 Ammonia changes red litmus paper blue, and being alkaline in nature 
 destroys copper, brass, and leather. 
 
 Ammonia is soluble in water, oul- part of the latter absorbing about 
 
 Latent heat value per lb (at average evaporator pressures 1 = 580 B T U 
 Boiling point at atmospheric pressure = — 37 F. 
 
 Critical temperature = 256 F. , Latent heat falls off in value rrom this 
 temperature np.i 
 
 Ammonia is lighter than air, , 
 
 Average Pressures and Temperatures. 
 
 The fitllowuig represent average marine refrigerating pr 
 temperature of 70" and brine outlet of 4° I'". 
 
 By the combined effects of compression and cooling, an 
 CO2 gas can be reduced to the liquid condition. 
 
 .\i»ol«l. 
 
 TeniiKTalurc 
 
 
 Pk&suic. 
 
 Ammonia (NH,)— 
 
 I'ahrenheit, 
 
 
 
 
 Brine cooler - - 35 
 
 -6* 
 
 
 Condenser ■ 170 
 Brine out • ., 
 
 8s; 
 
 j^:t 
 
 Brine returns 
 
 lo* 
 
 ii-° 
 
 
 
 
 Discharge - ■ 
 
 78* 
 
 i^g 
 
 00,.- 
 
 
 «sS 
 
 Brine cooler - 280 
 
 -6- 
 
 
 Condenser - 1050 
 
 8S' 
 
 Brine out 
 
 
 
 Urine returns . 
 
 
 
 Sea - 
 Discharge • 
 
 7"' 
 78- 
 
 ps. 
 
 1 Systems of Refrigeration. 
 
 and CO. i 
 
 falls back it indicate.s insuHictent gas, .is the machine should hold up to the 
 pressure if the supply is sufficient. Insufficient gas also shows by jumping 
 of the gauge pointers, and by rise of brine temperature, loss of temperature 
 difference, etc, If delivery pipe from compressor heats up, and still remains 
 heated after further opening of the regulator valve, it indicates shortage of 
 gas ; the condenser gauge falling in pressure is also an indication of insufficient 
 charging. 
 
 Temperature Differences.— The following examples of difference in 
 temperatures represent good refrigerating practice, and should be kept to a;, 
 nearly as possible. 
 
 Brine pressure about lo or 15 lbs. by gauge. 
 „ density about 40 oz. per gallon. 
 „ composed of fresh water and calcium fliloride (calcium salt). 
 
 Tests, Etc. 
 
 1. To Test Compressor or Regulator.— Stop machine and shut 
 
 ri^gulator ; if pressure rises in evaporator gauge and falls in condenser 
 gauge, the compressor rings are leaky, or regulator is passing gos. 
 
 2. To Test for Shortage of Gas,— Close down regulator, and run 
 nia<:hirie for, say, 15 revs.; if, during this period, the evaporator gauge pointer 
 
 r leaky evaporator coil 
 
 TcmpecAturc. 
 
 Teiiipciatuie. 
 
 6' 
 4" 
 
 »; 
 
 -4' 
 -6" 
 
 Al)out 10" 
 
 difference, i 
 
 Condenser. 
 
 
 Sen Wuer 
 
 (in 
 
 
 Temperature 
 
 t Temperature, 
 
 6o" 
 
 75 
 
 
 65" 
 
 80 
 
 
 70' 
 
 86 
 
 
 75 
 
 90 
 
 
 So' 
 
 95 
 
 
 85' 
 
 98- 
 
 .About 15 
 
 difference. 
 
 To Clear System of Air when Machine is Charged. 
 
 Ammonia Machine. —After running for some lime when charged, 
 stO|) machine, but k'c\i circulating, then connect a rubber tube either 10 
 condenser gauge i ock fitting, previously mentioned, or tn the air escape cock 
 sometimes placed on 1 ondenser delivery valve chest, and immerse lower end 
 of tube into a bucket of water ; gently open the cock, and close same when 
 smell of ammonia is nnticed coming from the water. 
 
 NOTE —The =ame method holds good for the CO. system, only the rubber 
 tube connection to the water bucket is not required, as the air and gas may t>e 
 safely discharged to the atmosphere 
 
 Overcharging. - If ihc machine is overcharged it will show by a rise 
 of the condenser gauge pressure. Air present in the .system also produces 
 
 thes 
 
 ;sult. 
 
 the 
 
 To Work Rectifier System.— At intervals of, say, 30 minutes or 
 more, open cock D, and blow out separator into rectifier cliamber, then 
 shut cock D, and open cock E, which allows the machine to draw off any 
 ammonia which has passed into reclifier ; next shut cock K, and drain off oil 
 from rectifier into a bucket by the cock fitted for that purpose. 
 
 Air in Brine System.— Air in the brim- system can be got rid of by 
 opening the air escape eoik fittL'd im iii|) of the evaporator ehamber {shown 
 in the sketch). 
 
 Rise of Sea Temperature.— If the sea water temperature 
 machine requires more gas, as the pressure and temperature of the refrigerant 
 must be proportionally increased to obtain the same temperaiurc difference 
 and cooling effect as previously. 
 
 Oil in System. - rhis shows by erratic movement of eraporaior gauge 
 pointer, and \ariation i" temperature of delivery pipe. 
 
 Air in System.— The presence of air is indicated by the machine falling 
 off in efliciency, and by jumping of condenser gauge pointer. 
 
 To Clear System of Air before Charging Machine. 
 
 CO.. Machine-— Break joint between condenser liquid pipe and 
 
 Ammonia Machine.— Close stop cock B and disconnwi gnuge from 
 delivery pi|)e lilting, then run machine slowly, and air will be dischiwged 
 through this opening. The evaporator and condenser gituges will indicate » 
 vacuum when the air is exhausted out of the system. 
 
 Testing of Gauges.- .After stopping machine, leave regulator full 
 open and the two t^augei should show identiati readings, with the temperature 
 shown conespoiiding to that of the liquid brine. 
 
Refrigeration 541 
 
 for a vaporising temperature of minus 15" Fahr., or hii^her or lower 
 as required. 
 
 Passing on now to a description of t}'pical plants. The one described 
 below is manufactured by the Liverpool Refrigeration Company 
 Limited, Liverpool, and is largel)' used in the North Atlantic chilled 
 beef trade. It is also equally applicable to the carriage of frozen 
 goods, mutton, &c. As a rule, plants are fitted in duplicate. The 
 diagram (No. 2) shows the essential parts and arrangement of this plant. 
 We ma)' here mention that, with few exceptions, the cold chambers on 
 shipboard are entirely chilled by means of wrought-iron piping 
 arranged on the ceilings, sides and ends, and through w hich the brine 
 cooled in the refrigerator is circulated. The plant before us is one of 
 [this type. 
 
 Description of Plant. 
 
 The ammonia compressor (No. 2) arranged in single, and in the 
 duplex form, is direct steam driven, and is of the horizontal double- 
 acting type. For convenience and for saving of space, the box bed 
 vn which the engine and compressors are mounted, contains the 
 ammonia condenser, which consists of a series of coils of wrought-iron 
 tubing in which the ammonia is condensed, the water circulating 
 round the outside of the tubes. After passing the condenser, the 
 liquefied ammonia collects in the reservoir AR from whence it passes 
 through the regulating valve RV into the refrigerator, which is of 
 the vertical type, and contains several circular concentric coils of pipe 
 placed in a steel shell with covers top and bottom. The ammejnia 
 vaporises inside the coils, the brine circulating round the outside. 
 After passing through the refrigerator, the ammonia is drawn back to 
 the pump as shown, to be compressed and discharged at the higher 
 pressure into the ammonia condenser for recondensation. The reader 
 will please note that the ammonia circuit is complete, and there is 
 no loss whatever of ammonia, which goes through the cycle of 
 vaporisation, of compression, and condensation time after time 
 indefinitely. The condensing water is supplied either by a separate 
 pump, or from one of the ship's donkeys, is drawn from the sea, 
 pumped through the condenser, and overboard. The cold brine is 
 drawn from the refrigerator by the brine pump, which is preferably 
 one of the " Worthington " duplex or similar type, and is discharged 
 to the distributing headers from whence, in several independent 
 circuits, it passes through the pipes in the cold chambers, returning 
 again to the return headers. Both distributing and return headers 
 are fitted with controlling valves so that each brine circuit may be 
 regulated as desired ; each circuit controlling a separate portion 
 of the cold chamber. The temperatures may thus be regulated by 
 allowing more or less brine to pass through any particular section 
 of piping. The thermometers index the return temperature and are 
 useful adjuncts in the regulating of the brine. After passing through 
 37 
 
Refrigeration 541 
 
 for a vaporising temperature of minus 15° Falir., or higher or lower 
 ris required. 
 
 Passing on now to a description of t}'pical plants. The one described 
 below is manufactured by the Liverpool Refrigeration Company 
 Limited, Liverpool, and is largely used in the North Atlantic chilled 
 href trade. It is also equally applicable to the carriage of frozen 
 goods, mutton, &c. As a rule, plants are fitted in duplicate. The 
 diagram (No. 2) shows the essential parts and arrangement of this plant. 
 We ma)' here mention that, with few exceptions, the cold chambers on 
 shipboard are entirely chilled b)' means of wrought-iron piping 
 arranged on the ceilings, sides and ends, and through which the brine 
 cooled in the refrigerator is circulated. The plant before us is one of 
 this t}'pe. 
 
 Description of Plant. 
 
 The ammonia compressor (No. 2) arranged in single, and in the 
 duplex form, is direct steam driven, and is of the horizontal double- 
 acting type. For convenience and for saving of space, the box bed 
 on which the engine and compressors are mounted, contains the 
 ammonia condenser, which consists of a series of coils of wrought-iron 
 , tubing in which the ammonia is condensed, the water circulating 
 round the outside of the tubes. After passing the condenser, the 
 liquefied ammonia collects in the reservoir AR from whence it passes 
 through the regulating valve RV into the refrigerator, which is of 
 the vertical type, and contains several circular concentric coils of pipe 
 placed in a steel shell with covers top and bottom. The ammonia 
 vaporises inside the coils, the brine circulating round the outside. 
 After passing through the refrigerator, the ammonia is drawn back to 
 the pump as shown, to be compressed and discharged at the higher 
 pressure into the ammonia condenser for recondensation. The reader 
 will please note that the ammonia circuit is complete, and there is 
 no loss whatever of ammonia, which goes through the cycle of 
 vaporisation, of compression, and condensation time after time 
 indefinitely. The condensing water is supplied either by a separate 
 pump, or from one of the ship's donkeys, is drawn from the sea, 
 pumped through the condenser, and overboard. The cold brine is 
 drawn from the refrigerator by the brine pump, which is preferably 
 one of the " Worthington " duplex or similar type, and is discharged 
 to the distributing headers from whence, in several independent 
 circuits, it passes through the pipes in the cold chambers, returning 
 again to the return headers. Both distributing and return headers 
 are fitted with controlling valves so that each brine circuit may be 
 regulated as desired ; each circuit controlling a separate portion 
 of the cold chamber. The temperatures may thus be regulated by 
 allowing more or less brine to pass through any particular section 
 of piping. The thermometers index the return temperature and are 
 useful adjuncts in the regulating of the brine. After passing through 
 37 
 
542 ''Verbal" Notes and Sketches 
 
 the return header it goes back to the refrigerator for recooling, after- 
 wards to go tlirough the same cycle again and again continuously. 
 Pressure gauges are fitted recording the ammonia pressures both on 
 condenser and refrigerator — high and low pressure — side, and also 
 the brine pressure. A small brine tank is fitted for mixing brine, 
 and is connected as shown, so that fresh brine may be introduced 
 into the system to make up any loss from leakage, &c. 
 
 The following extracts from the Liverpool Refrigefation Com- 
 pany's Book of Instructions may be of use : — 
 
 Pressures. — All ammonia pressures are absolute. The pressure on 
 the ammonia condenser gauge will vary with the temperature and 
 quantity of water passing through the condenser, and should generall)' 
 vary from 120 to 180 lbs. per square inch. The warmer the con- 
 densing water, the higher the pressure. The pressure on the 
 refrigerator gauge may be regulated as desired by means of the 
 regulating valve RV (see diagram), which should be adjusted to 
 the brine temperature ; the higher the temperature, the higher 
 the pressure. 
 
 Evaporator Pressures. — The following table gives the approximate 
 evaporator pressures and temperatures which should be kept to 
 secure the best effects : — 
 
 For brine temperatures of zero Fahr. - - - 24 lbs. 
 
 „ „ 5° » - - - 28 
 
 » „ 10° „ - - - 32 
 
 „ „ 15° » - - - 36 
 
 » „ 20° „ - - - 40 
 
 „ „ 25° „ - . - 45 
 
 >j J) 35 )) " " " 55 
 
 „ „ 50° » - - - 70 
 
 The refrigerator pressure should, while approximating to these 
 figures, be such that the discharge pipe from the ammonia compres- 
 sion pump should not be warmer than can be easily borne b)' the 
 hand, say roughly at a temperature not higher than 120" Fahr.; if 
 warmer than this, open the regulating valve slightl}- ; if colder, close 
 same slightly. The discharge pipe of the compression pump should 
 never be allowed to get cold or very hot, but should always be kept 
 as stated above. 
 
 Compressor Gland. — Sufficient oil should always be kept in 
 this for the lubrication of the cylinder, and to keep the gland 
 ammonia tight. The packing in the gland should always be very 
 carefully fitted ; if slack and badly fitted, the oil will leak past the 
 packing into the compressor in considerable quantities, which is 
 undesirable. The least possible quantity of oil to keep the rods 
 

 
 01 
 
 U ' ii ii ^ 
 
 ftVnVNMnMftaiWUBKr^ ' 
 
 ■"f^ 
 
 ^ 
 
H/AGBAM OF MARINB 7YPB MACJ//MS SMBWMG C OJ\^J\f£Cr/ONS. 
 The kivERPOOb Refp,(geration 6® W- . 
 
 aff/Nf ree B/?//vf ret 
 
 O.C. D/sc/rar i ^e Coc/r on Compressor 
 
 S.C. St/e//o/> Coc/r on Compressor. 
 
 O. T D/rf Tnp on Sucr/on Brsne^. 
 
 AC. A ir Coetr on Compressor ^/scAsr ^s 
 
 S.G . Ammonia Sue// on or /fefri^irsfor Smpe 
 
 D.G . Ammon/a 0/scAerqe or Conc/enscr Gau ^e . 
 
 I.e . Ammonia Lfuit/ CoeA 
 
 PC Oi/ CoeA: for Crawinf offOi/ 
 
 fi.l''. Ammonia fi e fu/g/i n f /a/t'e 
 
 C C. CAa r gmf Coet 
 
 S.G Brine A-essure Geu ^e 
 
 G./i G/anei Pe/ie/ fi/ pe 
 
 No. 2. 
 
 Vlo .fa,c f.,.!:,- 542 
 
Refrigeration 543 
 
 lubricated and the gland tight should be used ; sufficient will always 
 -ct through into the compressor to keep this in thorough order. 
 
 Oil Extraction. — The oil extraction cock OC (diagram No. 2) 
 is placed on the ammonia reservoir ; any oil passing through the 
 machine will collect here. Attach a short piece of pipe with the 
 end carried to a bucket, open the cock ver)- gently ; the cock has 
 an internal pipe leading to the bottom of the reservoir, and the oil 
 will be driven off by way of this pipe through the cock and into the 
 bucket. When the machine is new and probably more oil is used, 
 this oil should be withdrawn from the reservoir once every few days, 
 but afterwards the intervals ma}- be greatl}' lengthened. Do not 
 open the cock carelessl}'. 
 
 To Charge the Machine with Ammonia. — The ammonia drum 
 should ha\e the end remote from the cock slightly raised ; it should 
 be connected to the charging cock CC. After this is done, close the 
 regulating valve RV and start the compressor, water, and brine 
 pumps. When the pressure in the refrigerator is reduced, the charging 
 cock first, and afterwards the cock on the ammonia drum, may be 
 opened a little, and some of the ammonia from the drum allowed to 
 flow into the refrigerator to be pumped through into the condenser. 
 When it is thought that sufficient has been put in, first the cock on 
 the drum, and afterwards the charging cock, should be closed, and 
 then if necessary the drum can be disconnected and weighed, the 
 difference in weight before and after charging being the amount of 
 ammonia put into the machine. 
 
 To Overhaul the Compressor. — Before overhauling the com- 
 pressor, shut the suction cock SC. Run the machine a few turns 
 to exhaust the ammonia in the pump, then stop and close discharge 
 cock DC. The pump being now free from ammonia, may be opened 
 and examined. After examination is complete, and before letting 
 back the ammonia, take out the small screwed plug in the discharge 
 valve cover, and run the machine a few turns to discharge the air 
 from the compressor ; then when no more is discharged, screw in 
 plug and open the suction and discharge cocks. 
 
 To Make Brine. — The Calcium Chloride should be broken up 
 into small pieces and put into the brine tank. The brine should be 
 circulated through the brine tank by means of the pipes and valves 
 provided. First close the suction cock on the refrigerator ; the 
 water can be added as required into the brine tank. The small air 
 cock on the refrigerator top should be opened very frequently or 
 left open altogether. 
 
 Density of Brine. — The densit}- of the brine should be measured by 
 Twaddle's hj-drometer, and should be kept at from 40° to 48' to that 
 
:i 3 
 
 A^L\<:^. 
 
Refrigeration 543 
 
 lubricated and the gland tight should be used ; sufficient will always 
 get through into the compressor to kee}) this in thorough order. 
 
 Oil Extraction. — The oil extraction cock OC (diagram No, 2) 
 is placed on the aminonia reservoir ; any oil passing through the 
 machine will collect here. Attach a short piece of pipe with the 
 end carried to a bucket, open the cock very gently ; the cock has 
 an internal pipe leading to the bottom of the reservoir, and the oil 
 will be driven off b)' wa)' of this pipe through the cock and into the 
 bucket. When the machine is new and probably more oil is used, 
 this oil should be withdrawn from the reservoir once every few days, 
 but afterwards the intervals ma)' be greatly lengthened. Do not 
 open the cock carelessl)'. 
 
 To Charge the Machine with Ammonia. — The ammonia drum 
 should have the end remote from the cock slightly raised ; it should 
 be connected to the charging cock CC. After this is done, close the 
 regulating valve RV and start the compressor, water, and brine 
 pumps. When the pressure in the refrigerator is reduced, the charging 
 cock first, and afterwards the cock on the ammonia drum, may be 
 opened a little, and some of the ammonia from the drum allowed to 
 flow into the refrigerator to be pumped through into the condenser. 
 When it is thought that sufficient has been put in, first the cock on 
 the drum, and afterwards the charging cock, should be closed, and 
 then if necessary the drum can be disconnected and weighed, the 
 difference in weight before and after charging being the amount of 
 ammonia put into the machine. 
 
 To Overhaul the Compressor. — Before overhauling the com- 
 pressor, shut the suction cock SC. Run the machine a few turns 
 to exhaust the ammonia in the pump, then stop and close discharge 
 cock DC. The pump being now free from ammonia, may be opened 
 and examined. After examination is complete, and before letting 
 back the ammonia, take out the small screwed plug in the discharge 
 valve cover, and run the machine a few turns to discharge the air 
 from the compressor ; then when no more is discharged, screw in 
 plug and open the suction and discharge cocks. 
 
 To Make Brine. — The Calcium Chloride should be broken up 
 into small pieces and put into the brine tank. The brine should be 
 circulated through the brine tank by means of the pipes and valves 
 provided. First close the suction cock on the refrigerator ; the 
 water can be added as required into the brine tank. The small air 
 cock on the refrigerator top should be opened very frequently or 
 left open altogether. 
 
 Density of Brine. — The density of the brine should be measured by 
 Twaddle's h)-drometer, and should be kept at from 40° to 48' to that 
 
544 "Verbal" Notes and Sketches 
 
 scale, the latter figure being for lower brine temperatures, the former 
 for brine temperatures above 15". 
 
 Circulation of Brine. — Each section of brine pipe should after ever)' 
 voyage be circulated by itself, the others being shut off. This circula- 
 tion should take place through the brine tank, the refrigerator being 
 shut off for the time being. The brine pump must be worked ver)' 
 slowly, and the brine pressure gauge watched during this operation 
 Any air collected in the pipes will be got rid of b)' this means. 
 
 Regulation of Chamber Temperatures. — The temperature of the 
 chamber must be regulated exactly as desired by closing or opening 
 the gland cocks on the return tees. The engineer should make him- 
 self acquainted with the particular section of piping, and therefore of 
 the chamber governed by each cock. The inlet cocks should be left 
 fully open, the regulation being effected b}' the returns. The pressure 
 on the brine gauge should not exceed 10 lbs. per square inch. 
 
 Air in System. — The presence of air or other gas than ammonia in 
 the gas circuit, reduces the efficiency of the machine, and this may be 
 detected by the machine working irregularly and by having a con- 
 denser pressure higher than that due to the temperature of condensing 
 water. To purge of air ; pump all ammonia into condenser and 
 reservoir, stop machine, keep circulating pump going, and after stand- 
 ing", say, half-an-hour, remove gauge from cock on top of condenser 
 tee and couple up small pipe provided for the purpose, the remote 
 end of the pipe being put in a bucket of water, gently open cock and 
 let it blow until the water begins to crackle and rise in temperature. 
 This shows that ammonia is passing and that the air has been got 
 rid of. If necessary, repeat the process after running the machine a 
 few hours. 
 
 Generally. — Always take care before starting the machine that both 
 brine and water pumps are started and working proper!}' and all 
 necessary cocks in ammonia circuit are open. Keep a careful eye on 
 the pressure gauges ; never let the compressor work too hot or too 
 cold, remembering that by the regulating valve you may regulate this , 
 exactly as you wish. It is better for the cargo when thoroughly 
 chilled down to run the machine continuously at a slow speed rather ■ 
 than running full speed for a short time and stopping the remainder. 
 
 i 
 Haslam Type. ■ 
 
 We illustrate on next page a marine type machine work-j 
 ing on the Haslam ammonia compression system as made by the 
 Haslam Foundry and Engineering Company Limited, of Derby. 
 This machine has compound compressors to give greater economy 
 when working in hot climates. These are driven by a compound 
 steam-engine placed in front of the compressors. The lower part 
 
Refrigeration 
 
 545 
 
 of the bed is a substantial \vrou>^fht-iron tank, which contains the 
 ammonia condensers — coils of galvanised \vi'out;ht-iion pipes, the 
 ends of which are fitted with cocks so that any coil can be isolated 
 
 
 b 
 
 
 Q 
 
 
 ^ 
 
 
 •o 
 
 
 o 
 
 
 
 
 
 oi 
 
 B 
 
 c 
 
 J 
 
 
 
 J3 
 
 >. 
 
 u 
 
 a 
 
 nJ 
 
 a 
 
 bo w 
 
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 bti 
 
 
 
 
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 c 
 
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 (I] 
 
 Cti 
 
 •a 
 
 OJ 
 
 Rt 
 
 
 
 C 
 
 C 
 
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 3 
 
 S 
 
 O 
 
 < 
 
 
 1 
 
 h 
 
 1 
 
 frt 
 
 
 
 CO 
 
 rt 
 
 d 
 
 ffi 
 
 2: 
 
 (U 
 
 in case of leakage. The method of cooling the meat chambers is 
 either by brine pipes, as has already been described, or by blowing 
 air by means of fans over nests of coils in which the liquefied 
 
546 
 
 "Verbal" Notes and Sketches 
 
 u 
 o 
 
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 (fi 
 <u 
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 O 
 U 
 
 6 
 
 c 
 
 (Ti 
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 tuQ 
 
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 rt 
 
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 h 
 
Refrigeration 547 
 
 ammonia is evaporated ; the cooled and dried air is then distributed 
 throughout the meat chambers through wooden ducts or trunks. 
 
 Haslam's machinery, working on the brine pipe system, is at the 
 present time bringing chilled beef from the River Plate, a voyage 
 lasting thirty days, with a variation of temperature of within half a 
 degree on each side of a fixed point, the cargo being invariably landed 
 in perfect condition. 
 
 Haslam's double-acting ammonia compressor, of which we show a 
 section, is fitted with suction and delivery valves in the end covers, 
 which are made concave to give room for the valves ; the piston is 
 turned an accurate fit for the covers so that the clearance is reduced 
 to a minimum, being in fact considerably less than if the valves were 
 placed in the cylinder body, as is sometimes done. The special form 
 of gland with two separate packings allows of either packing being 
 adjusted independently of the other. The annular space between the 
 packings is kept full of oil, and there is also a lubricator on the outer 
 gland. 
 
 The method of working these machines is generally as has been 
 before described. 
 
 The Carbonic Anhydride System. 
 
 The general principle of this system is similar to that of the 
 ammonia compression machine, in regard to the cycle through which 
 ;the refrigerating agent passes. This is made clear by the diagram 
 given below, which consists of the following parts : — 
 
 1. The compressor (the only moving part), in which the gas drawn 
 from the evaporator is compressed, 
 
 2. The condenser, consisting of coils, in which the compressed 
 warm gas is cooled and liquefied by the action of cooling water. 
 
 3. The evaporator, consisting of coils, in which the liquid carbonic 
 anh}-dride evaporates, producing any degree of temperature that may 
 be required, down to 80' below freezing point. 
 
 We are indebted to Messrs J. & E. Hall Limited, Dartford, for 
 the following description of their refrigerating machinery : — 
 
 The difference between the Hall carbonic anhydride machine and 
 the ammonia machines lies chiefly in the employment of another 
 refrigerating agent. Carbonic acid is gas which liquefies under a 
 pressure of about 50 atmospheres under temperate conditions and 
 about 75 atmospheres in the tropics, and the parts of the machine 
 are constructed of sufficient strength to stand these pressures, and 
 moreover are tested to 3-4 times the working pressure, as will be 
 mentioned below. The efficiency of the refrigerating agent is found 
 in these machines to be very high, and the reduction of cooling effect 
 due to higher temperatures of condensing water is found to be, in 
 practice, about the same as that which occurs with other types of 
 refrigerating machines. 
 
548 
 
 Verbal " Notes and Sketches 
 
 The charge of carbonic anhydride originally put into the machine 
 is used over and over again, going progressively through the processes 
 of compression, condensation, and evaporation, passing through a 
 closed cycle. Thus a small quantity only is required to be added from 
 time to time to replace any small losses, and for this purpose carbonic 
 acid is sent in steel cylinders to any part of the world. The cost of 
 
 
 Intel 
 
 No. 5.— Diagram of Messrs J. & E. Hall's Carbonic 
 Refrigerating Machine. 
 
 the material is only a {q\w pence per pound. The quantity required 
 for a complete charge is very small, the cost of a charge for a 24-ton 
 ice plant being only about £7. 
 
 Properties of C02- — Carbonic anhydride is a non-poisonous gas, and 
 a constituent of atmospheric air. To give an idea of the freedom 
 from danger of J. & E. Hall's patent refrigerating machines, it may 
 be stated that the entire contents of the machine might be allowed 
 to escape into an ordinary engine-room without any disastrous results 
 or, in most cases, even inconvenience. 
 
 Though it is not contended that an atmosphere containing only 
 carbonic acid will support life, on the other hand, it has been found 
 by careful experiments made by well-known scientists, that men can 
 breathe fairly comfortably in air containing as much as 15 per cent. 
 of carbonic acid, in which atmosphere one of the investigators remained 
 for three quarters of an hour. Now the entire charge in the machines 
 usually fitted on board ship by Messrs J. & E, Hall Limited is such 
 that the atmosphere would not contain so large a proportion of 
 
Refrigeration 
 
 549 
 
 I carbonic acid even if the whole charge escaped instantaneously from 
 the machine into the main engine-room. 
 
 The details of the machines arc as follows : — 
 
 Description of Hall Plant. 
 
 Compressor. — The compressors for tlie large machines are bored 
 out of solid steel forgings, partly to secure strength, but principally on 
 
 (Condenser 
 Co/1 
 
 Brine return 
 
 Condenser Guaye 
 
 Ri/ien/ 5ak\y Valve 
 
 Cylinder^ 
 
 ComprzsiQu -^ 
 Separator 
 
 ftiffenf hollow I— r^^ 
 0\l Gland ^^^ 
 
 Connechn 
 Rod 
 
 nsulorion 
 round 
 fvaporo tew 
 
 Crank 
 Shan 
 
 Vlahj f~ 
 
 CircuiQhnfl Pump "^ Condenser Cas/no 
 
 No. 6.— Section of Hall Vertical Marine Type Machine. 
 
 [account of greater certainty of soundness of the matcial, and to 
 provide a perfect bore in which may work the cup leathers with which 
 the pistons are provided. 
 
 Compressors of smaller m.achines are cast in a special bronze, 
 which secures the two essentials of soundness and hardness. The 
 suction and delivery valves are identical for facilities of interchange. 
 
 Gland. — The gland is made gas-tight by means of two cupped 
 leathers on the compressor rod. A special lubricating oil is forced 
 into the space between these leathers at a pressure superior to the 
 
550 "Verbal" Notes and Sketches 
 
 greatest pressure in the compressor, so that whatever leakage takes 
 place at the gland is a leakage of the oil either into the compressor 
 or out into the atmosphere, and not a leakage of gas. What little 
 leakage of the oil takes place into the compressor is advantageous, 
 inasmuch as it in the first place lubricates the compressor, and in the 
 second place it fills up all clearances, thereby increasing the efficiency 
 of the compressor. 
 
 In order to replace the special oil which leaks out of the pressure 
 lubricator, there is a small hand hydraulic pump, a few strokes of 
 which are required to be made every two or three hours, as may be 
 indicated by the position of the pressure lubricator piston rod. This 
 form of gland is now in constant use on nearly 2000 machines 
 supplied by J. & E. Hall Limited. 
 
 Separator. — Any oil which passes into the compressor, beyond what 
 is necessary to fill the clearance spaces, is discharged with the gas 
 through the delivery valves. In order to prevent this passing into 
 the condenser coils, all the gas is delivered into a patent separator. 
 The oil drains to the bottom of this vessel, whence it is drawn off 
 from time to time ; meanwhile the compressed gas passes off by an 
 opening at the top on its way to the condenser. 
 
 It may here be remarked that the oil has no affinity for carbonic 
 anhydride, hence it undergoes no change in the machine, and there 
 is, therefore, no fear of the coils becoming clogged by any small 
 amount of oil which might be carried over in spite of the separator. 
 
 Condenser. — This consists of coils of copper tube, which are placed 
 in a tank and surrounded by water, similar to the condenser of a 
 steam-engine, with, however, the gas inside the tubes and the cooling 
 water outside. These coils are welded together into such length as 
 to avoid altogether any joints inside the tank, where they would be 
 inaccessible. The welding of these pipes is all done at J. & E. Hall's 
 works by the electrical method, which gives very good and reliable 
 results. 
 
 In connection with the condenser, one very important advantage 
 of carbonic acid machines is apparent, for as carbonic acid has no 
 chemical action on copper, in the numerous cases where sea water 
 only is available for condensing purposes, that metal is used in the 
 construction of the coils. 
 
 Evaporator. — This also consists of nests of wrought-iron hydraulic 
 pipes electrically welded up into long lengths, inside of which the 
 carbonic anhydride evaporates. The heat required for evaporation 
 is usually obtained either from brine surrounding the pipes, as in 
 cases where brine is used as the cooling medium, or else from air 
 surrounding the pipes, as in cases where air is required to be cooled 
 direct. 
 
 Between the condenser and evaporator there is a regulating valve 
 
VERTICAL MARINE TYPE CO^ MACHINE. 
 By Messrs J. & E. Hai.l, Limited. 
 
 Verbal " Notes and Skelchi. 
 
 I'l'o face pa;^,' 55c. 
 
Refrigeration 551 
 
 for adjusting the quantity of the Hquid carbonic anhydride passing 
 from the condenser. 
 
 J. & E. Hall's Patent Safety Valve. — In order to enable the 
 compressor to be o[)ened up for examination of valves and piston 
 without loss of carbonic anhydride, it is necessary to fit a stop-valve 
 on the suction and delivery sides, so as to confine the carbonic 
 anhydride to the condenser and evaporator. It is, of course, possible 
 for a careless attendant to start the machine again without opening 
 the delivery valve, and in such case an excessive pressure would be 
 created in the delivery pipe, from which there would be ik) outlet. 
 To provide against this danger a patented safety device is adopted, 
 consisting of an ordinary spring safety valve, at the base of which is 
 a thin copper disc, which is designed to burst at a pressure consider- 
 ably below that to which the machines are tested. This disc is made 
 perfectly gas-tight, an object which could not be attained by the 
 spring safety valve alone, and the latter only comes into play when 
 the disc is ruptured. Great care is necessarily exercised in making 
 the discs to provide against variation in strength, due to any variation 
 either in the thickness or hardness of the copper sheets out of which 
 the discs are made. 
 
 Joints. — With regard to the joints to withstand the pressures, those 
 which are not subject to a high temperature can be made absolutely 
 tight with any suitable material, such as leather, but for the hot joints, 
 special rings are supplied which withstand the heat and still have 
 the necessary elasticity to ensure the joint being perfectly tight when 
 either hot or cold. The absolute tightness of all joints is effectually 
 tested by brushing them over with soap and water, the slightest leak 
 being thereby detected. 
 
 Testing Parts. — Very careful tests are carried out in J. & E. Hall's 
 works to ensure perfect soundness of all parts subject to the gas 
 pressure. The working pressure varies from about 750 lbs. per 
 square inch in temperate climates, with water at 50" Fahr., to about 
 1 125 lbs. with water at 84" to 90^, as is usual in the tropics. 
 Owing to the very small diameter of all parts, even in large machines, 
 there is no difficulty in securing a very ample margin of strength. 
 All parts of machines subject to the pressure of the carbonic 
 anhydride are, in the first place, tested for strength by hydraulic 
 pressure to 3000 lbs. per square inch, and they are then again tested 
 while immersed in warm water by air to 1350 lbs. per square inch, 
 whereby the slightest porosity which might exist in any of the 
 materials is at once detected by air bubbles ascending through the 
 water.* 
 
 * Extract from Paper read before the British Association by Mr E. Ilesketh, 
 M.Inst.C.E., M.I.Mech.E., Managing Director of J. & E. Hall Limited. 14th 
 September 1895. 
 
ci^2 "Verbal" Notes and Sketches 
 
 Refrigeration. — As a refrigerating agent, liquefied carbonic acid is 
 second to none. Under atmospheric pressure it evaporates from the 
 Hquid state at the particularly low temperature of 120° Vahr. 
 below zero, or 152° below the freezing point of water. In J. & E. 
 Hall's refrigerating machine, however, it is caused to evaporate at 
 only a few degrees below the temperature of the material which it 
 is desired to cool, the principle of the machine being exactly the 
 same as that of machines using anhydrous ammonia on the com- 
 pression system — viz., as water boils at 212^ Fahr. under atmospheric 
 pressure, and about 250° Fahr. at 15 lbs. pressure, fire being usually 
 the source of heat, so liquid carbonic acid boils or vaporises at 
 30° Fahr. at 35 atmospheres' pressure, and thus permits cold water 
 or colder brine to be the source from which the necessary heat to 
 boil it is absorbed, exactly in the same manner as the heat of the 
 fire is absorbed in boiling water. 
 
 The compressor draws the gas or vapour from the evaporator and 
 compresses it to the liquefying pressure, which is controlled within 
 certain limits by the temperature of the cooling water. The heat 
 due to compression is absorbed by the cooling water in the condenser, 
 the gas circulating within the condenser coils and becoming liquefied 
 by the time it reaches the lower extremity of these coils. 
 
 We are able, by regulating the pressure in the evaporator, to cause 
 the liquid to boil throughout the coils of the evaporator, which act 
 in the same manner as the heating surface in a steam boiler, and 
 the temperature or boiling point of the liquid carbonic acid adjusts 
 itself to that of the source of heat which is causing it to boil, whether 
 it be water at 70" to be reduced to 40", or brine to be maintained 
 at + 10" Fahr. or — 10" Fahr. 
 
 The surfaces of the evaporator coils are so proportioned that all 
 the liquid which enters at the lower end of the coil is evaporated 
 by the time it reaches the top end, and thus the maximum efficiency 
 is obtained. The compressor then draws in only gas, and compresses 
 it up again to the pressure necessary to liquefy it, and delivers it 
 warm to the condensing coils to continue the cycle of operation.* 
 
 The vertical marine type machine, illustrated on the preceding 
 pages, consists of a single vertical steam cylinder, with the compressor 
 arranged alongside of it, both secured to a casting containing the 
 condenser coils, which are made of copper, and behind this casting 
 is another secured to it containing the evaporator coils, the whole 
 making a very compact and accessible design. 
 
 These small machines are perfectly simple, work quite noiselessly, 
 and can easily be worked by a person of ordinary intelligence from 
 the printed instructions supplied with each machine. They need very 
 little attention, and the wear and tear and consequent need of repairs 
 is almost ftil. No increase in the staff of engineers is necessitated, as 
 
 * Extract from Paper read before the Institute of Brewing, by Mr Alex. Marcet, 
 A.M.Inst.C.E., Managing Director, J. & E. Hall Limited. May 1894. 
 

 o £ 
 
 H . 
 
 •^ 
 
Refrieeration 
 
 55. 
 
 they can be placed in any available corner of the ent;ine-room, where 
 they come under the e)'e of the engineer on watch. 
 
 The complete charge of carbonic anhydride in the machine is so 
 small that it may be allowed to escape into the engine-room without 
 the slightest inconvenience. A patent safet}' valve is fitted so that no 
 
 No. 7— Patent Safety Valve, Hall Machine. 
 
 mistake or neglect on the part of the attendant can cause anything 
 like an accident. 
 
 Instructions for Charging and Working. 
 
 Before Charging. 
 
 Pressure Lubricator. — Fill receptacle above hand pump with 
 \^acuum Dartford Refrigerating Oil, and pump this into the pressure 
 lubricator by means of hand pump till piston is at inner end of stroke. 
 
 Compressor. — In a vertical machine put piston at bottom end of 
 stroke, take off cover and about one-fourth fill compressor with 
 Vacuum Dartford Refrigerating Oil. Replace cover. In a horizontal 
 machine, take out one of the delivery valves and put piston at the 
 other end of the compressor. Then about one-fourth fill compressor with 
 Vacuum Dartford Refrigerating Oil. Replace the valve. Pull machine 
 round twice, then run machine for a quarter of an hour, all screws-down 
 valves being open. After this commence charging. 
 
 Charging. — The CO2 is supplied in steel flasks of various sizes 
 containing from 22 lbs. to 40 lbs. each, as stamped on flask. About 
 * lbs. constitutes a charge. 
 
 Suspend the flask, valve upwards, on the spring balance, and 
 connect b)' copper pipe provided to small screw-down valve at end of 
 evaporator coil. Note the weight. Open valve on flask and on 
 
 * Varies according to size of machine. 
 
2 
 
 lb 
 
 5 
 
 J5 
 
 lO 
 
 5> 
 
 20 
 
 1) 
 
 554 "Verbal" Notes and Sketches 
 
 machine. See that the connecting joints, which are made with leather 
 washers, are tight. After the CO.^ has passed into the system, note 
 weight again, and the difference is the weight of CO2 passed into the 
 machine. 
 
 When flasks have had 10 lbs. taken out (not before) they may be 
 warmed by pouring on hot water to assist in driving out further gas. 
 While this proceeds the lower end of flask will remain cold so long as 
 liquid CO2 remains, but when the whole flask has become heated, no 
 more liquid CO., remains, and valve should be closed while flask 
 is still warm. To get the utmost out of the flask before closing its 
 valve the evaporator should be pumped down to sa}- 15 atmospheres 
 (on outer circle of gauge) by running the compressor for a few 
 minutes with closed regulator. 
 
 When first charging, blow the air out of the system by breaking 
 the joint between the regulator and pipe leading to it from condenser, 
 the regulator being closed, and all other valves open, and blow some 
 CO., to waste according to size of machine, thus : — 
 
 Up to No. 9 Machine ■ - ; " 
 
 As the pressure, while charging, rises, carefully examine all 
 joints. The slightest leaks become visible when painted with soap 
 and water lather. 
 
 Gauges. — The CO., gauges on condenser and evaporator show 
 on outer circle the pressure in atmospheres, and on inner circle the 
 corresponding temperature of CO.,. (When logging, the inner circle 
 only should be recorded, figures in red on the gauge being entered 
 in log with a minus sign thus : 
 
 -Id- 
 
 denoting 15° below zero.) 
 
 Working Conditions. — Having fully charged, start the machine, 
 and adjust the regulator (i.e., inlet valve of evaporator coil) so that 
 the evaporator gauge indicates on inner circle 10° to 15" Fahr. 
 (6° to g° Cent.) below the temperature of the brine leaving the 
 evaporator. If the machine be sufficiently charged, the condenser 
 gauge will indicate usually some 15" Fahr. (8° Cent.)* above the 
 temperature of the water entering the condenser. 
 
 * (Note. — This varies with the quantity of water passing condenser, and is 
 correct if the water outlet is 10° Fahr. higher than the inlet. If the rise in 
 temperature of water is only 5° Fahr. the gauge should stand about 12" above 
 water inlet. If the rise in temperature of water is 20° Fahr., the gauge should 
 stand about 20' above water inlet.) 
 
Refrigeration 5^5 
 
 An excessive charge is indicated b)' the .i^auge standing hi^dier, 
 and a ver)^ excessive charge b)' a considerable fluctuation of the 
 j)ointer. 
 
 Under ordinary working conditions, the compressor should be 
 cold or partly covered with snow, and the delivery pipe from it 
 should be rather warmer than the hand can comfortably bear. If 
 the deliver)' pipe is not hot enough, slightly close the regulator, when 
 the teni[)erature will quickly rise. If compressor becomes warm, it 
 points to regulator being insufficiently open. 
 
 If unable to obtain the indications given above on condenser 
 gauge, then the system is short of gas.* As a further test of this 
 close the regulator : if sufficient gas is present, the evaporator gauge 
 should hardh' fall for some fifteen or more revolutions of machine. If 
 the gauge falls immediately, without any pause, it indicates shortness 
 of CO... 
 
 If in doubt as to sufficiency of charge add more ; some extra gas in 
 the s}'stem, up to one-fourth of a charge, will be far more beneficial than 
 a slight undercharge. If machine is short of gas, the refrigerat- 
 ing work done will be but a fraction of its proper duty. 
 
 A rise of several degrees of temperature of inlet cooling water 
 ,will necessitate the addition of CO.-, in order to keep machine fully 
 charged, and similarl}^ a fall in temperature may cause indications 
 I of overcharge. 
 
 Brine. — The density should be regulated by the addition of 
 calcium chloride till the densimeter supplied floats at central mark, 
 which is 40° on Twaddell's Densimeter, or till one gallon weighs 
 about I2i lbs., that is, a specific gravity of about 1-25. The brine 
 should be made in a separate vessel, and lumps of calcium should 
 not be thrown into the evaporator tank for fear of choking the pipes. 
 It is important that sea water should not be used. Common 
 salt (sodium chloride) may be used instead of calcium chloride, but 
 to prevent corrosion, for every 100 lbs. of salt used i lb. of caustic 
 soda is to be added. 
 
 In machines fitted with open evaporators there should be sufficient 
 brine in the system to ensure the evaporator coils being entirely 
 covered by about 6 inches when machine is running. In machines 
 fitted with closed evaporators the cock on air pipe must be kept 
 slightly open to prevent air collecting in evaporator. 
 
 Compressor Piston and Rod. — The machine is fitted with a double 
 or single acting compressor. Whenever replacing piston observe the 
 following instructions : — 
 
 * (Note. — In above instructions as to working conditions it is assumed that 
 the valves and piston leathers are in good order. If doubt exists as to this, 
 proceed as explained under heading "Test.") 
 
556 "Verbal" Notes and Sketches 
 
 For Double-Acting Compressor. — As the clearances hetiveen the 
 piston and the ends of compressor are very small they must be maintained 
 equal at both ends. 
 
 Always bar round before starting after replacing piston. 
 
 The piston is packed with h}xlraulic leathers which will require 
 examination and renewal occasionally. The compressor rod must 
 be kept in a highly polished state and free from any marks, and if 
 machine is lying idle, the rod should be removed and kept well 
 greased in a dry place. 
 
 It is very necessary that the nut securing the piston leathers 
 should be well screwed up and locked ; when new leathers are put 
 in, it is advisable, a few hours after starting, to tighten the nut up 
 again. (See instructions under " To Examine COMPRESSOR.") 
 
 Compressor Valves. — The suction and delivery valves will require 
 occasional examination and cleaning. A set of spare ones should be 
 kept ready for use. 
 
 * The valve seats are separate from the compressor and make double 
 joints : see that both copper rings are equally crushed by the valve casing. 
 Leakage at the outside joint will indicate itself outside, but at the inner 
 joint will not be perceptible except in reducing the work done by the 
 machine. 
 
 Test. — To test the working of the compressor, close the regulator, 
 when evaporator gauge should be pumped down from say 25 atmo- 
 spheres to 5 atmospheres in about 200 revolutions. If slower, either 
 the valves or the piston leathers are faulty, or the regulator may be 
 leaking. 
 
 Compressor Gland. — This is packed with two hydraulic leathers 
 and compressible rings, between which a pressure of Vacuum Dart- 
 ford Refrigerating Oil is maintained by the patent automatic pressure 
 lubricator provided. The gland should be screwed up hard enough 
 to compress the rings, and will require tightening up occasionally, but 
 this should not be done while running. The pressure lubricator 
 will require pumping back when its piston has moved 4 inches, but 
 this should not occur at least under three hours if the gland leathers 
 and compressor rod are in good order. The pressure lubricator 
 valves must be full open, otherwise, though not easily observable, 
 the gland cannot be gas-tight. The oil which leaks from the gland 
 should be caught, and after filtering and separating any water from 
 it, used over again. 
 
 Separator. — Any oil passing into the compressor will be caught in 
 the separator and must be drawn off every second time of pumping 
 
 * For steel block compressors only. 
 
Refri'o-eration 557 
 
 t ap pressure lubricator, or oftener if much oil is passing^ in, by 
 slackeninj^ drain pluf^, and after filtering it ma}' be used over 
 atrain. 
 
 COo. — This must be pure and free from water and air. If the 
 gas cannot be obtained dry, a CO.^ dryer should be fitted to the 
 machine. 
 
 As a precaution against moisture each flask should be suspended 
 valve down for some twenty-four hours before using, and then by 
 very slightly opening valve any water present will escape. 
 
 Gland Oil. — As an improper oil may cause trouble, it is strongly 
 recommended that only Vacuum Dartford Refrigerating Oil should 
 be used. This is obtainable from the Vacuum Oil Co., York tfouse, 
 Norfolk Street, London, W.C., and its branches. 
 
 Strainer. — On suction side of compressor is a strainer, which should, 
 with a new machine, be taken out and cleaned after the second day's 
 working, and afterwards occasionall}' if required. 
 
 Stopping and Starting. — When stopped for some days, the screw- 
 down valves on suction and delivery of compressor should be closed, 
 but no other valves. For shorter stoppages, no valves need be 
 closed. The gauges will then equalise, standing at temperature 
 of brine in evaporator. Before starting, care should be taken that 
 any valves closed are reopened, but should this be neglected a safety 
 valve is provided to relieve the pressure. If machine is run at 
 constant speed the regulator should require very little alteration after 
 being once adjusted. 
 
 Speed. — The machine should run* revolutions per minute. 
 
 Leakages. — It is very necessary that all pipe joints and glands of 
 valve spindles should be carefully examined with soap lather and 
 kept tight. For the first few days especially they should be examined 
 daily and all bolts and gland nuts screwed hard up. The most 
 minute leak must instantly be stopped. 
 
 To Examine Compressor. — Close the suction and delivery screw- 
 down valves, also the valve between pressure lubricator and gland, 
 and slack off a joint to let the gas escape. Make sure all pressure 
 is gone before opening up. 
 
 38 
 
 * According to size and type of machine. 
 
558 "Verbal" Notes and Sketches 
 
 Stores and Spares. — It is recommended that a supply of the 
 following be kept on hand : — 
 
 Flasks of C0.>. 
 
 Vacuum Dartford Refrigerating Oil. 
 
 Calcium Chloride. 
 
 Compressor Piston Leathers. 
 
 Compressor Gland Leathers. 
 
 Pressure Lubricator Leathers (two sizes). 
 
 Compressible Rings for Gland. 
 
 Set of Delivery Valves. 
 
 Set of Suction Valves. 
 
 Set of Bronze Joint Rings for Compressor. 
 
 Compressor Piston Rod, highly polished. 
 
 Safety Valve Discs. 
 
 Possible Causes of Trouble. 
 
 1. Owing to leakage, or to a rise in temperature of condensing 
 water, the machine may become insufficiently charged. Remedy :- 
 Add more gas until CO., gauges show indications under heading 
 " Working Conditions." 
 
 2. Gland leathers may be worn out. This will be indicated by 
 pressure lubricator piston working out to its full stroke in one hour 
 or less. Remedy : — Renew gland leathers, carefull}' examining piston 
 rod for roughness ; if necessary u.se spare rod, and repolish rod 
 taken out, 
 
 NOTE. — This may also rarely be caused by a defective piston leather in the 
 pressure lubricator itself. 
 
 3. Piston leathers may be slack at nut or worn out. This will be 
 indicated by compressor failing to pump out evaporator as indicated 
 under heading "Test." Remed}' : — Tighten piston nut, or, if 
 necessary, change piston leathers. 
 
 NOTE. — The same indications may be caused by the valves being worn or 
 stuck up, in which case they must be examined, cleaned, and, if necessary, 
 repaired. 
 
 4. Irregular action of evaporator gauge and also the delivery pipe 
 from compressor changing from hot to cold frequently without apparent 
 reason, indicates that there is some foreign liquid present in the system, 
 probably oil from pressure lubricator which has not been drained from 
 separator. Remedy : — Slack joint between liquid pipe and condenser 
 outlet coil box, and allow foreign matter to escape. Also open the 
 valve on evaporator coil used for charging machine and blow out any 
 oil, &c., present. Also drain separator frequentl}' till trouble ceases, 
 and then drain it according to the instructions. 
 
 As an alternative remedy when brine is not at a low temperature, 
 run the machine with regulator full open for ten minutes, then close 
 
Refrio-eration 559 
 
 rej^ulator to working position, and, as soon as compressor delivery is 
 warm, drain separator. 
 
 5. Evaporator gauge may register a much lower temperature than 
 stated under " WORKlKd CONDITIONS" in spite of further opening of 
 regulator. This may be due either to the evaporator casing being 
 partly empty or to the formation of ice on the outside of the coils 
 owing to the brine density being insufficient. 
 
 6. Gauges sometimes give false indications — To test this, both 
 gauges should indicate alike when the machine is stopped, regulator 
 remaining open. They should then both indicate the temperature of 
 the brine surrounding the evaporator coils. 
 
 7. Condensing water pump may be out of order, or the supply of 
 water may be insufficient. This will be indicated by unusually high 
 condenser pressure, and high temperature of overflow water. Remedy : 
 — Examine water pump or increase water supply. 
 
 8. Do not run machine faster than these instructions state. If not 
 effecting usual refrigerating work, ascertain fault and apply remed)-. 
 
 ! 9. Hand pump on pressure lubricator may refuse to work. 
 Remed)' :— Examine and clean the valves of hand pump and small 
 strainer covering suction. In case CO^ has got in between the gland 
 leathers, slack joint of guard round pressure lubricator piston rod, 
 allowing gas to escape. 
 
 I 10. When cooling chambers, loss of efficiency is sometimes due to 
 the chamber doors (i) being open too often, or (2) being left open, 
 or (3) shrinking and becoming a bad fit. The cold air will then flow 
 out and necessitate machine running many more hours than necessary. 
 Doors can be tested for tightness' by closing them on slips of paper 
 which will then be nipped if door fits tightly. 
 
 Log- — It is advisable to keep a log, recording especially speed, 
 indication of gauges, temperature of condensing water, in and out, 
 and brine, in and out. Compare present log with past logs, and if 
 any falling off is indicated, ascertain the cause and apply remedy. 
 As a guide, a form of log is appended. 
 
 Assistance.— J. & E. Hall Ltd. gladly give advice to users of their 
 machines, but letters explaining any difficulty experienced should 
 alwa>-3 be accompanied by a log of actual working in the form 
 appended. 
 
 Important. — Whenever consulting makers as to any point in workino- 
 of machine, scud t/ievi a log giving the following particulars so far as 
 they apply, and always give number cast on machine. 
 
;6o 
 
 "Verbal" Notes and Sketches 
 
 Time. 
 
 Hours 
 
 run per 
 
 Day. 
 
 Revolu- 
 tions. 
 
 Ste.im. 
 
 Vacuum 
 
 Brine. 
 
 Gauges 
 Inner Circle 
 
 Coolinj; 
 Water". 
 
 Return 
 
 to 
 Evap. 
 
 Outlet 
 from 
 Evap. 
 
 Evap- 
 orator. 
 
 Con- 
 denser. 
 
 Inlet. 
 
 Outlet. 
 
 
 
 
 
 
 
 
 
 
 
 Readi 
 
 ngof G 
 
 auges f 
 
 ifteen r 
 
 ninutes 
 
 after st 
 
 opping 
 
 
 
 
 
 Haslam COo Machines. 
 
 The Haslam Foundry Company Ltd., of Derby, are also large 
 makers of CO., machines, so that the following description of this 
 firm's machines will be of interest: — 
 
 The arrangement and general construction is practically similar to 
 that already described, the smaller machines being made vertical and 
 self-contained, and either steam or belt driven. The condenser for 
 use on land is a coil of heavy wrought-iron pipe, but on board ship, 
 copper pipe is used. The larger machines are made horizontal, and 
 the marine type duplex, as shown b}' illustration on page 551. 
 
 The condenser is here contained in the bed, but in the large 
 machines it is in a separate casing ; the evaporator is also in a separate 
 casing. Messrs Haslam fit a safety valve to all their machines. 
 
 These machines work either with the brine pipe or air circulation 
 system. 
 
 NOTE.— See page 554 for notes on CO2 and Ammonia, and method of charging 
 machine with gas. 
 
 Arrangement of " Haslam " Plant on the CO2 System. 
 
 The plate opposite represents a cross section through a ship, 
 showing the arrangement of a Haslam refrigerating plant on the 
 CO3 system. The ships are so arranged that they are capable of 
 
COo SYSTEM ON SHIPBOARD. 
 Ey Messrs The Haslam Foundry and En<;in-eekivg C'>., I.imited, Deki;v. 
 
 Verlial " Notes and Skeiche?. 
 
 [ To face pai^c 560. 
 
Refrio-eration 
 
 ;6i 
 
 carrying a mixed cargo, such as frozen meat in the holds and fruit 
 in the 'tween decks, or a general cargo, such as butter, eggs, cheese, 
 poultry, fish, &c. The holds are fitted with brine pipes, under the 
 
 deck and on the sides, for maintaining a low temperature. The 
 'tween decks are fitted with collapsible air trunks, through which 
 the cold dry air is circulated at a suitable temperature for preserving 
 
562 " Verbal " Notes and Sketches 
 
 fruit. The air is drawn through the suction trunks by means of 
 a steam-driven fan ; it is then passed through the air cooler, consisting 
 of nests of pipes through which the cold brine is circulated. The air 
 is thus cooled to any desired temperature, all moisture being deposited 
 on the pipes in the form of snow. The trunks are so designed that 
 the foul air can be discharged into the atmosphere and fresh air 
 supplied as required. The 'tween decks can also be fitted with brine 
 pipes. When they are not in use the collapsible air trunks are hinged 
 up out of the way. The two small chambers which are intended for 
 holding passengers' provisions are fitted with brine pipes, the larger 
 one being maintained at a temperature of 20" Fahr. for meat, and 
 the other at a temperature of 35° Fahr. for vegetables. A small ice 
 tank for producing about 3 to 4 cwt. of ice for table use and water 
 and wine coolers is supplied when required. 
 
 The CO2 refrigerating machine can either be fitted in the tunnel 
 (when a twin-screw ship), in a corner of the main engine-room, or on 
 one of the upper decks, thus taking up little or no valuable space. 
 
 Liverpool Refrigeration Co. Ltd. CO^ Machines. 
 
 The machine generally consists of a steam cylinder and gas 
 compressor, arranged side by side, and coupled to a double throw 
 crank-shaft which runs in three bearings. The shaft has a heavy 
 fly-wheel at one end with safety barring lever. 
 
 The steam cylinder is fitted with a piston valve. Crossheads are 
 of the open type, and all bearings are adjustable. 
 
 The compressor embodies a number of patented improvements. 
 It consists of an outer steel casing enclosing an easily withdrawable 
 liner of special metal, forming the bore of the cylinder. At either 
 end are heads of forged steel which carry the valves, and back and 
 front covers. 
 
 The usual leather cups for packing the piston and glands are 
 entirely absent, and there is no forced lubrication. 
 
 The piston is a metallic packed piston of considerable length, and 
 having a number of special cast-iron packing rings held in carriers 
 of hard bronze, the whole being kept in place by a special split collar, 
 so arranged that it is impossible for the piston head to come slack 
 so long as the piston is within the cylinder ; there are no screws or 
 pins whatever. 
 
 The compressor valves work vertically, and are of very large area 
 and small lift. 
 
 The gland consists of an inner and outer stuffing box, the former 
 being packed with a special form of metallic packing. This stuffing 
 box and gland does most of the work, and, in addition, a couple of 
 woodite washer rings are fitted to the outer gland to stop any small 
 leakage past the inner packing. 
 
 The whole is arranged for long continuous runs, and avoids 
 

 
 S5 
 
Refrigreration 
 
 563 
 
 altogether the difficulties experienced with leather cups. In the 
 box-bed underneath the machine are arranged both the condenser 
 and evaporator coils. The bed is divided into two portions by a 
 
 No. 9. — Method of Charging Machine with COo Gas. 
 
 watertight bulkhead, the condenser coils being placed in one portion, 
 and a cast or wrought iron cartridge or case heavily lagged, and 
 containing the evaporator coils, is placed in the other portion. The 
 evaporator casing is hermetically sealed inside the box-bed so that 
 
564 "Verbal" Notes and Sketches 
 
 there can be no condensation of moisture, and the lagging is always 
 kept perfectly dry and highly efficient. The coils, however, can be 
 readily withdrawn by removing the covers and without disturbing ^e 
 insulated cartridge case. 
 
 There are no internal joints whatever, and the headers, regulating 
 and control valves are all easily accessible, and are neatly and handily 
 arranged. 
 
 All connections subject to COo pressure are of steel. 
 
 The brine and water pumps are independent of the machine, and 
 in one form consist of a duplex, double-ended pump having the brine 
 cylinders at one end, the water cylinders at the other end, and the 
 steam cylinders in the middle. 
 
 Charging Refrigerator with Gas. — The balance overhead indicates 
 the amount entering the evaporator by showing a difference of weight, 
 and as the flask becomes emptied of its contents, slightly heating it 
 with warm water will quicken evaporation and thus produce complete 
 (or nearly so) evacuation. 
 
 NOTE.— The steel flask contains liquid COo (or Ammonia) under pressure, but 
 when the pressure is decreased as described, evaporation instantly commences, and 
 the CO. then passes off as a gas. 
 
 When the connection is opened between the flask and the 
 evaporator, evaporation begins owing to decrease of pressure, and 
 COo gas passes from the flask into the machine. 
 
 Latent Heat of NH3 and COo. — At atmospheric pressure the boiling 
 point of Ammonia (NH^) is — 37-5° Fahr., and of Carbonic Acid (CO.,) 
 — 125° Fahr, Notice that both of these are below zero. 
 
 The Latent Heat of Evaporation of Ammonia (NH,), at a pressure 
 of 30 lbs. and temperature of 0° Fahr., is 555 units of heat. The 
 Latent Heat of Evaporation of COo, at a pressure of 310 lbs. and 
 temperature of 0° Fahr., is 124 units of heat. This means that i lb. 
 of Ammonia, in evaporating in the evaporator coils, absorbs 555 units 
 of heat from the surrounding brine, which is therefore lowered in 
 temperature correspondingly ; and that i lb. of COo, in evaporating 
 in the evaporator coils, absorbs 124 units of heat from the brine, 
 which is therefore lowered in temperature correspondingly. 
 
 NOTE.— Water absorbs Ammonia in the proportion of 600 volumes of Ammonia 
 gas to I volume of water. From this it will be evident that the best means of getting 
 rid of Ammonia gas, should a serious escape occur in the engine-room, would be to 
 play a jet of steam into the Ammonia fumes. 
 
 NOTE.— COo, being a non-supporter of combustion, can be employed to put out 
 fire in a steamer's hold, if allowed to escape into it. 
 
 I 
 
Verbal " Notes and Sketches. 
 
 [7(9 face page 564. 
 
Refrigeration 
 CO., and NH„ Pressures and Temperatures, &c. 
 
 S^: 
 
 Chemical. 
 
 Teiiipcralurc. 
 
 rressurt'. 
 
 Latent Heat of 
 Vaporisation. 
 
 Anhydrous ammonia (NHg) - 
 
 -6^ 
 
 20 lbs. 
 
 580 B.T.U. 
 
 Carbonic acid (COo) 
 
 -6' 
 
 280 „ 
 
 125 „ 
 
 Anhydrous ammonia (NH3) - 
 
 85^ 
 
 170 >. 
 
 530 » 
 
 Carbonic acid (CO. ) 
 
 85° 
 
 1050 „ 
 
 25 » 
 
 From the foregoing table it will be noticed that for equal tempera- 
 tures the CO, system requires much higher pressures than the NH3 
 system, but it should be remembered that the working medium is safer 
 in case of escape, and the size of compressor required is much less. 
 On the other hand the latent heat of vaporisation is higher for the 
 ammonia, which means that less gas will be required to produce a 
 given amount of cooling. 
 
 Critical Temperature of CO.. and NH3.— By this is meant the 
 temperature beyond which the gas cannot be reduced to liquid form. 
 
 For Ammonia (NHg) the critical temperature = 256° Fahr. 
 For Carbonic Acid (CO.^) ,, ,, = 88° ,, 
 
 If, therefore, in a CO.^ machine the water circulation temperature 
 rises above go", the efficiency of the machine will fall off, owing to 
 the disappearance of the latent heat. 
 
 The Compressed Air' System. 
 
 One of the simplest forms of refrigerating machine is that commonly 
 known as the dry air machine, which works by the compression, 
 cooling, and expansion of atmospheric air. These machines have 
 found great favour for use on shipboard, owing to the low temperature 
 which can be obtained, the dryness of the cooled air, the low pressure 
 at which they work, and the absence of any chemicals — the working 
 medium, air, being always available. Their chief disadvantage as 
 compared with the chemical machines is that no use can be made 
 of the latent heat of the refrigerating medium ; therefore a much 
 larger quantity has to be dealt with, necessitating larger compressors 
 and increased power to drive them. Had it not been, however, for 
 the compressed air machine, our meat trade with the colonies could 
 not have assumed the dimensions it has at present, and the fact that 
 some of the leading steamship companies are still fitting their ships 
 with this class of machine speaks well for its reliability and usefulness. 
 
 Referring to the diagram showing the working of a compressed air 
 machine. The air compressor is driven by any independent means, 
 
566 
 
 "Verbal" Notes and Sketches 
 
 such as an engine and crank-shaft, and the suction pipe, being connected 
 to the cold chamber, draws in the warmest air from the top of the 
 
 No. 10.— Vertical Type Haslam Dry Air Machine. 
 
 room. This air is compressed to 50 lbs. pressure, thus increasing its 
 temperature to about 280°, and it is then delivered into the air cooler, 
 consisting of a number of tubes surrounded by water, which is circu- 
 
" Verbal " Notes and Sketches. 
 
 [ To face pa^e 566. 
 
Cooling Water Inlet 
 
 Press. 
 50 Lbs. 
 
 No. II. Diagram of Compressed Air System." 
 
 [ro/,u./>>x-->66- 
 
VERTICAL F.LKCTKICALLV-I)KI\i;.\ CAKIJOMC ANHYDRIDE 
 REFRIGKRATIXG MACIIINK. ADMIRALTY lAI'K. 
 
 Verbal " Notes and Sketches. 
 
 {To fate fa^t- 56O. 
 
-*"r^- 
 
 consisting of a number or lui 
 
VERTICAL ELi:CTRICALLY-DRI\i:X CAi;H()\IC ANHYDRIDE 
 REFRIGERATING MACHINE, ADMIRALTY TYPE. 
 
 Verbal " Notes and Sketches 
 
 [ To face fa:^v 566. 
 
Refrigeration z^S'/ 
 
 lated by a separate pump. Here the air is cooled down to a few 
 degrees above the circulating water temperature and delivered to the 
 
 No. 12.— Vertical Type Haslam Dry Air Machine. 
 
 i . 
 
 ■; air expander, where it is allowed to expand behind the piston, doing 
 mechanical work by assisting to drive the air compressor. The 
 expanding air thus gives up heat in the form of work, and is thereby 
 
568 "Verbal" Notes and Sketches 
 
 reduced in temperature to about —90' Fahr. The air is then delivered 
 into the cold chamber at one side near the top, and, circulating 
 through the room to the return trunk, is drawn again to the com- 
 pressor, the cycle thus being complete. 
 
 In most cases patent drying pipes are fitted in connection with the 
 above apparatus, their function being to dry the compressed air before 
 it is expanded. This is done by passing it through tubes round 
 which is circulated the returning air from the cold rooms. By this 
 method the compressed air is cooled, and any moisture is deposited in 
 the " dryer " and discharged through cocks or valves at the bottom. 
 
 Sir A. Scale Haslam has developed the compressed air machine 
 from its experimental stage, and machines built by his firm were the 
 first to carry successfully large cargoes of frozen meat from the colonies. 
 We now give illustrations and descriptions of machines as built by 
 the Haslam Foundry and Engineering Company Ltd., of Derby. 
 
 The machine here illustrated is of the vertical type, and is capable 
 of circulating 8000 cubic feet of air per hour. It is driven by a com- 
 pound steam-engine, the steam cylinders being arranged tandem ; 
 the steam supply is controlled by a piston valve in each cylinder, 
 actuated by a single eccentric. The compressor, arranged alongside 
 the steam cylinders, is double acting and water jacketed, and has 
 hollow covers of brass in which are the suction and delivery valves of 
 phosphor bronze. The air expander, placed alongside the compressor, 
 is also double acting and has main and cut-off valves, the latter being 
 adjustable. The ports of this cylinder are made as short and direct 
 as possible to avoid choking with snow, which in small machines not 
 fitted with drying pipes would otherwise give trouble. 
 
 Across the back of the machine is arranged the air cooler, similar 
 in construction to an ordinary steam surface condenser, in which the 
 compressed air on its way to the expansion cylinder is cooled by the 
 sea water surrounding the tubes. A water-circulating pump is fixed 
 to bed and driven from crank-shaft. 
 
 The next illustration shows Haslam's duplex compressed air 
 refrigerator, capable of circulating 180,000 cubic feet of air per hour 
 at 90° below zero (Fahr.). It is specially arranged to work in the 
 'tween decks of a ship, and is duplicated so that either side of the 
 machine, consisting of one steam cylinder, one compressor, and one 
 expansion cylinder, can be worked separately in case of accident 
 to the other side, thus giving greater security to the cargo. The 
 machine is fitted with steam surface condenser, air, circulating, and 
 feed pumps, contained within the soleplate, the pumps being driven 
 by a rocking shaft worked from either crosshead pin. When worked 
 as one machine the steam cylinders work compound. 
 
 The drying pipes are separate nests of tubes, and are not shown 
 in the illustration. 
 
 The plate illustration opposite shows the usual arrangement of the 
 refrigerating machine, drying pipes, and air trunks as fitted on board a 
 steamer, and is a good type of a large cargo installation. The holds 
 
^ 
 
Refrigeration 
 
 569 
 
 c 
 
 IS 
 u 
 
 < 1 
 
 Q e 
 
 o 
 U 
 
 H 
 
 .S 
 
 a 
 o 
 
 N 
 
 *u 
 O 
 
 X 
 
 X 
 
 Q 
 
 'So 
 
 c 
 UJ 
 
 •o 
 
 c 
 
 (4 
 > 
 
 c 
 a 
 o 
 
 X 
 
 '^ in 
 
 M 0) 
 
 6 S 
 2 
 
570 
 
 Verbal " Notes and Sketches 
 
 and upper and lower 'tween decks are insulated. The air trunks are 
 made collapsible when not in use, and are arranged on both sides of the 
 ship so that a perfect circulation is obtained, and by an arrangement 
 of doors the direction of the air current may be reversed at will. The 
 'tween decks may be used for carrying cheese or other produce not 
 requiring so low a temperature as the meat, and are then cooled by 
 the air returning from the holds to the machine. The vertical trunks 
 on each side of bulkhead connect to the longitudinal trunks at sides 
 of ship ; the connection is made separately on each side of bulkheads 
 to obviate the necessity of cutting the bulkhead and fitting watertight 
 doors. Two duplex machines are fitted side by side, and on the 
 upper deck, so as to be directly above their work. 
 
 Haslam Dry Air Machines. 
 
 Pressures and Temperatures. 
 
 Air entering Compressor 
 
 „ leaving 
 
 ,, entering Cooler - - - 
 
 „ leaving „ - . . 
 
 ,, entering Dryers 
 
 „ leaving „ . - . 
 
 „ entering Expander - 
 
 „ leaving „ ... 
 
 Cut-off in Expander, | stroke. 
 Sea water, 64° Fahr. 
 
 Air leaving chamber at 20° is raised to 32" to 36° on entering 
 compressor usually, but if the return pipe in engine-room is not 
 sufficientl}- lagged, the temperature rises, as shown in the above 
 log, to 40' or 45 ^ 
 
 Compressor and Expander Cylinder Diagrams. — Observe that the 
 pressure entering the compressor is rather less than that of the 
 atmosphere, as the initial pressure line is just below the atmospheric 
 
 TEMR 280" 
 
 Gauge Pressure 
 
 Temperature. 
 
 in lbs. 
 
 Degrees Fahr. 
 
 
 
 40° to 45° 
 
 50 
 
 280" 
 
 50 
 
 280° 
 
 50 
 
 67° 
 
 50 
 
 67° 
 
 49 
 
 32° to 36' 
 
 49 
 
 32° to 36° 
 
 - I to 2 
 
 - 90° to - IC 
 
 No. 14. — Diagram from Compressor, 
 
Refrigeration 
 
 571 
 
 line ; also that the pressure rises to 50 lbs. (gauge) and the tempera- 
 ture to 2S0' r\'ihr. 
 
 The air at 50 lbs. pressure and 280° temperature is discharged into 
 the cooler, where most of the heat (work) is carried off by the circu- 
 lating water passing through the cooler overboard, so that the air, 
 still at 50 lbs. pressure, is now reduced to a temperature of dy'' Fahr. 
 
 TEMP 36° 
 
 TEMP -90'' 
 No. 15. — Diagram from Expander. 
 
 This necessary loss of heat in the cooler accounts for the difference 
 in area in the compressor and expander diagrams, and means that 
 work at least equal to the loss must be given out by the steam 
 cylinders of the machine. 
 
 In the expander diagram, which is of less area than the com- 
 pressor diagram, notice that the compressed air enters the expansion 
 cylinder at a pressure of 49 lbs. and a temperature of only 36° Fahr., so 
 that when the air is cut off at three-eighths stroke it expands and falls 
 in pressure to about i or 2 lbs. above the atmosphere ; but the fall in 
 temperature is very much more in proportion, as work is being done 
 by the air in assisting to dri\e the expander piston. Briefly, by the 
 combined effects of low initial temperature, expansion, and work 
 done, the exhaust temperature is reduced to —90" Fahr. or to —100° 
 Fahr. 
 
 NOTE. — If the air merely expanded without doing work the pressure would 
 drop, but the temperature would remain constant ; as, however, work is done on 
 the expander piston by the air, heat is lost and the temperature lowered. One 
 B.T.U. disappears for every 778 footpounds of work done. 
 
 General Notes on Refrigeration. 
 
 Pressures and Temperatures. 
 
 For a sea temperature of about 70° the following are the average 
 pressures and temperatures required for the three systems of refrigera- 
 tion obtaining in ordinary marine practice — cold air, ammonia, 
 and CO.,:— 
 
5/2 
 
 Verbal " Notes and Sketches 
 
 Medium Employed. 
 
 Cold Air . . - 
 
 Ammonia (NH.J 
 
 " " . ' 
 
 Carbonic Anhydride (CO^,) 
 
 Absolute Pressure. 
 
 Temperature Fahr. 
 
 1 7 lbs. (Expander exhaust) 
 
 65 
 
 25 
 
 170 
 
 280 
 
 1050 
 
 (Compressor) 
 (Evaporator) 
 (Compressor) 
 (Evaporator) 
 (Compressor) 
 
 -90 . 
 280°. 
 - 6° (Brine - 4°). 
 
 (Sea 70°). 
 
 (Brine - 4°). 
 
 (Sea 70°). 
 
 -6 
 
 85 
 
 NOTE. — In the Ammonia and CO., systems with brine circulation the brine 
 temperature would be somewhere about - 4° Fahr. for the pressure and temperature 
 of the gas as given in the Table. Notice that the brine temperature is above that 
 of the Ammonia or CO.^ in the evaporator coils, and that the sea water tempera- 
 ture is below that of the Ammonia or COo in the condenser coils (from 12' to 18° 
 difference in each). 
 
 Temperature Difference. — For the cooling effect required, it is 
 necessary that a difference of temperature should exist between the 
 gas in the condenser coils and the circulating sea water, the latter 
 being the lower temperature of the two, so that the excess heat picked 
 up by the refrigerant from the brine in the evaporator may be trans- 
 ferred to the circulating water and so carried over the side. 
 
 It will thus be obvious that if the sea water rises to a temperature 
 of, say, 80^ Fahr,, then the temperature of the Ammonia or CO,, must 
 be in excess of this by 8° or 10^ to allow of heat transfer, and to obtain 
 this difference of temperature the pressure of the gas must be increased 
 in due proportion. 
 
 For a gas temperature of 90" the ammonia pressure would require 
 to be 180 lbs., and the CO^ pressure 1 140 lbs., and if the .sea tempera- 
 ture rose to 85" and the gas temperature is to be, say, 93 ', the ammonia 
 pressure would require to be 200 lbs., and the CO., pressure 1 180 lbs. 
 per square inch ; so that the higher the sea temperature the higher 
 the pressure required in the compressor to still maintain the necessary 
 temperature difference. 
 
 Ammonia (NH3) evaporates at a temperature of —37° when the 
 pressure is 14-7 lbs. (atmospheric) and has a latent heat of evaporation 
 of 555 B.T.U. 
 
 Leaky Compressor Piston and Valves. — i. Leak)' suction valves 
 show by a rise on the evaporator gauge. 
 
 2. Leaky delivery valves show by a rise on the evaporator gauge, 
 and a variation in pressure on the condenser gauge. 
 
 3. Leaky compressor pistons show by a rise on the evaporator 
 gauge and a fall on the condenser gauge. 
 
 To Test if Brine is Corrosive. — Immerse a piece of bright iron in 
 
Refrigeration 573 
 
 the brine for a period of, say, two days, and the iron will remain 
 unchanged if the brine is non-corrosive. 
 
 Air Extraction (Ammonia System). — In extracting air from the 
 system by means of tiie air cock on top of condenser coils, for safety 
 it is advisable to connect up a flexible length of tubing from the 
 cock, the other end of the tube being immersed in a bucket of water. 
 When the air has all passed out any ammonia which follows will 
 be absorbed by the water, and the smell of which will indicate when 
 to shut off the cock. Previous to repacking the gland or piston the 
 ammonia contained in the compressor can be got rid of by the same 
 method, first closing the hand suction and delivery valves. 
 
 Overhauling Compressor (Ammonia System). — In opening up 
 the compressor or any other working part of an ammonia machine 
 the gas should first be got rid of by thorough ventilation, otherwise 
 a light brought near may produce an explosion. 
 
 Brine Temperature Difference. — The difference in temperature 
 between the outgoing and return brine should be from 3" to 5^ Fahr. 
 
 COo evaporates at a temperature of — 120^ at an atmospheric pressure 
 of 14-7 lbs., and has a latent heat of evaporation of 130 B.T.U. 
 
 Cold Air System. — For good efficiency the following points require 
 attention : — 
 
 1. Tightness of pistons, valves, of compressor and expander, also 
 Cooler and Dryer tubes. 
 
 2. When starting up machine after standing idle for some time, 
 all relief cocks should be kept open, and the machine run for some 
 time before drawing the air direct from the cold chambers. 
 
 3. The following temperatures should be regularly taken : — 
 
 A. Air temperature before entering compressor. 
 
 B. ,, ,, after leaving compressor. 
 
 C. ,, ,, before entering expander. 
 
 D. ,, ,, after leaving expander. 
 
 E. Cooling water temperature. 
 
 4. Drains on Cooler and Dryer to be opened at regular intervals. 
 
 Joint Testing". — To test for gas leakage at joints or connection soap 
 lather is employed, and bubbles form if leakage exists. 
 
 Brine Temperature. — The brine temperature kept is about 8' or 10" 
 lower than the tcinperature of the cold chamber, so that if, saj-, fruit 
 is to be maintained at a temperature of 16" Fahr., then the brine 
 temperature should be 8' Fahr. 
 39 
 
SECTION X 
 
 INTERNAL COMBUSTION ENGINES. 
 
 General. 
 
 The gas engine is now rapidly coming to the front in marine 
 practice, and (on the Continent particularly) is being effectively 
 developed for use at high powers. The chief difficulty, so far, is that 
 of reversing, but this has been overcome to some extent by the 
 use of compressed air, which, forced into the cylinder, changes the 
 direction of piston travel and thus reverses the engine. The four- 
 stroke engine is still more in evidence than the two-stroke type, but 
 the latter system has been much improved and perfected of recent 
 years. Some foreign makers build gas engines of the double-acting 
 type, but the reliability and efficiency of this system has yet to 
 be proved. 
 
 Advantages. 
 
 1. Boilers deleted. 
 
 2. Smaller bunker space (petrol or petroleum tank) required. 
 
 3. Instant starting (with petrolj. 
 
 4. Ease of manipulation. 
 
 5. Cleanliness. 
 
 6. Economy. 
 
 7. Reduced staff. 
 
 Disadvantages. 
 
 I. Ignition and other troubles. 
 
 3. Danger from petrol and petroleum vapour. 
 
 6. Difficulty of reversing; 
 
 7. Complication of machinery with engines of large power. 
 
 8. Deposits of carbon in cylinder heads. 
 
 9. Difficulty of revolution speed control. 
 
 Producer Gas. 
 
 In land installations, gas obtained by the "Producer" system^ is 
 used, and this has also been experimented with in marine practice. 
 It is the opinion of many eminent engineers that this is the best method 
 of running internal combustion engines. In the producer system the 
 
Internal Combustion Engines 
 
 575 
 
 gas instead of being obtained from oil, is produced direct from coal 
 by heatint^^ the appliance being known as a " producer." This, of 
 course, necessitates the carrying of coal and the use of furnaces, &c., 
 whereas in the case of oil, the oil only is carried in the tanks, and is 
 
 No. I.— Dowson Suction Gas Producer. 
 
 1, Coal hopper. 
 
 2, Incandescent coal. 
 
 3, Coke scrubber. 
 
 4, Water supply to scrubber. 
 
 5, "Water seal." 
 
 6, Gas outlet to engine. 
 
 7, Funnel. 
 
 8, Water inlet to boiler. 
 
 9, Boiler (low pressure). 
 
 10, Ashpit. 
 
 11, Hand fan for starting 
 
 12, Funnel shut-off valve. 
 
 13, Water overflow pit. 
 
 up. 
 
The gas is 
 through a mass 
 
 576 "Verbal" Notes and Sketches 
 
 supplied direct to the cyh"nders, after heating by means of a heating 
 lamp to produce vaporisation. 
 
 Producer System. 
 
 obtained by passing a jet of low pressure steam and air 
 ,ss of incandescent fuel. The principal parts of the 
 appliance are : — 
 
 1. Producer. 
 
 2. Cooler and scrubber. 
 
 3. Small steam generator. 
 
 4. Hand-driven fan for starting up fire. 
 
 Producer. — This is a vertical cylinder chamber with a coal feed 
 hopper at the top, into which the coal (usually Anthracite) is tipped: 
 at the bottom is a fire-box with the ordinary fire-bars and 
 furnace door. 
 
 Cooler and Scrubber. — The scrubber is filled up with water (" water 
 seal ") for a short distance from the bottom, and the gas entering 
 from the producer enters below the water level, thus forcing the gas 
 through the liquid for cleaning purposes ; the upper part of this 
 chamber contains lump coke, and has a water drip from the top ; the 
 gas passing up and through the coke is purified or scrubbed of the 
 tarry substances which would otherwise cause trouble in the engine 
 by depositing in the valves, cylinders, &c. 
 
 Steam Generator. — This is a smaller boiler fitted on the producer to 
 obtain steam for admission to the incandescent fuel, so that the gas 
 may be produced by the chemical action resulting. 
 
 Action. — The general action of the producer is as follows : — After 
 lighting the fires and using the hand fan to create a draught, when the 
 heat is sufficiently strong, the funnel outlet valve is closed and the 
 coal gases pass into the water of the cooler, thence to the scrubber, 
 and from there by suction to the oil engine cylinders, to be com- 
 pressed and fired in the usual way. The steam generated in the small 
 boiler together with air passes down a pipe and enters the producer 
 among the fuel ; in doing so the steam (HoO) is decomposed by the 
 heat of the coal, and Hydrogen and Oxygen are set free. These gases 
 combine with the carbon of the coal to give CO or Carbonic Oxide, 
 and this, together with the Hydrogen, passes to the top of the producer 
 chamber, then to the cooler and scrubber as previously described. 
 
 Therefore, producer gas is obtained by passing air and steam 
 through the heated fuel, and the chemical reactions which take place 
 are as follows : — 
 
 2C + 0.,=:2C0. 
 
 In other words, Oxygen of the air combines chemically with Carbon 
 
Internal Combustion Engines ^'jj 
 
 of the fuel to produce CO (Carbonic Oxide), and the water (steam) is 
 decomposed and forms more C:0, also free Hydrogen. CH^ (Marsh 
 Gas) and CO., are also formed during the heating process, so that we 
 
 have as a result — 
 
 Combustible gases -CO, H,, CH4. 
 Incombustible ,, =COo, No. 
 
 The average chemical composition of producer gas is as follows : — 
 
 CO (Carbon Monoxide) ... - about 30 per cent. 
 
 H (Hydrogen) - - - - ,, 15 >> 
 
 CH, (Marsh Gas) - - - • - ,, i „ 
 
 CO.. (Carbonic Acid) - - - - - ,. 6 ,, 
 
 N (Nitrogen) • - - - - - 1. 48 >. 
 
 Efficiency. — The efficienc}- of producer plant is about 80 per cent. 
 
 Consumption. — The coal consumption per I.H.P. per hour varies 
 from about -9 lb. coal at low powers to about i^ lbs. coal at high 
 powers. 
 
 Heat Value. — The heat value of producer gas varies from 140 to 
 180 B.T.U. per cubic foot of gas. 
 
 Test Burner. — A testing burner is fitted on the pipe leading from 
 the producer to the cooler, and this when lighted indicates the quality 
 of the gas which, if satisfactory, is allowed to enter the cooler, but 
 which, if not satisfactory, is allowed to pass up the waste gas funnel. 
 
 NOTE.— It should be observed that when the engine is running, the regular 
 suction of the cylinders acts like a draught to keep the producer working, so that 
 the supply is equal to the demand, and this being so, the hand fan is stopped as 
 soon as the engine is started running. 
 
 It should also be noted that the producer is worked at a pressure 
 slightly under that of the atmosphere, owing to the suctional action 
 of the engine in drawing off the gas generated. This also explains 
 how the atmospheric air pressure enters the producer. 
 
 After the gas passes from the producer to the engine it*is mixed 
 with the required amount of air in the carburetter or vaporiser to 
 form a more highly explosive mixture for rapid combustion (explosion) 
 in the cylinders. 
 
 Explosion Systems. — The oil motor is an explosive engine, the 
 cylinder head constituting the explosion or combustion chamber, 
 and to allow of this the clearance space is equal to about 30 per cent. 
 of the c)'linder volume. When the explosion is produced by a spark, 
 or, as in the case of paraffin motors, by a hot tube or lamp, the engine 
 is then really of the " e.xplosive " type ; but if, as in some cases, the 
 explosion is produced by the gases being compressed sufficiently to 
 ignite spontaneously by the heat left in the cylinder head, the motor 
 
578 "Verbal" Notes and Sketches 
 
 is then of the " internal combustion " type, although the term internal 
 combustion is generally applied in both cases. 
 
 In the typical modern motor boat using petrol, the energy is 
 stored in the petrol ; this is transformed into gas and mixed with 
 air in the carburetter, while the energy is liberated as heat in the 
 engine cylinder, and then directly transformed into mechanical work 
 by the piston, and into propulsive work by the propeller. 
 
 The oil or explosive engine is of course a heat engine, and as 
 such develops concentrated energy at the moment of ignition of 
 the gases, whereas with steam the energy is distributed more over 
 a longer period. The gas entering the cylinder represents potential 
 energ}', which on ignition changes almost instantly into kinetic or 
 active energy, the fly-wheel receiving and storing up some of this 
 power or energy, which is afterwards employed in completing the 
 three other powerless strokes. In one of these, the compression 
 stroke, a large proportion of the power previously developed is 
 absorbed or used up in compressing the gases to the necessary 
 pressure required for effective ignition and explosion. This work, 
 then, is done by the piston on the gas, and may be called negative 
 work. 
 
 As heat and work are equivalent, the intense heat obtained by 
 the explosion of the charge produces work, each unit of heat being 
 equal to, or giving out, 778 foot-pounds of work. 
 
 Paraffin and Petroleum. — The paraffin or petroleum motor is 
 certainly the most convenient in many ways, as being usually ignited 
 by a heating lamp less trouble is experienced than with electrical 
 connections, magneto, &c., all of which require careful attention and 
 regular overhaul. 
 
 Paraffin can always be obtained, and is fairly cheap ; it is also safe, 
 as vaporisation does not readily take place, hence the necessity for 
 the heating lamp previously referred to. This at the same time, 
 however, constitutes a disadvantage, as time is required to heat up 
 the vaporiser before the engine can be started. After once starting, 
 however, the heating lamp is usually turned off, as the carburetter is 
 then kept hot by the exhaust gases. The flash point of paraffin, 
 which is known as a " heavy " oil, is about 84° Fahr. 
 
 Petrol or Gasoline. — Petrol is the spirit obtained from the crude 
 petroleum, and is chiefly composed of carbon and hydrogen, about 
 85 per cent, carbon and 14 per cent. h}'drogen. The flash point is 
 low, about 35° Fahr., so that evaporation takes place very easily under 
 atmospheric pressure, which is an advantage in the matter of instant 
 starting, but which at the same time constitutes a danger, as if 
 leakage of petrol takes place explosion readily occurs when the 
 vapour formed becomes mixed with atmospheric air. The heat units 
 in I lb. of oil fuel are usuall)' about 20,000 units, or roughly about 
 one-half more than that in i lb. of ordinary coal, so that for the 
 
Internal Combustion Rnc^ines 579 
 
 same power about two-thirds the amount of petrol or paraffin is 
 sufficient. As the fuel is in liquid form it also occupies less bunker 
 space, and, as before stated, for the same weight contains half as 
 much attain power or energy, which still further reduces the fuel space 
 required for a given distance to be run. 
 
 Two-Cycle. — In small single-cylinder motor sets up to about 7 Brake 
 Horse-rower, and two-cylinder 10 B.H.P., the two-cycle system is 
 usually adopted, and is carried out as follows : — 
 
 The crank case is air-tight, and is fitted with a small port, which 
 is opened and closed by the piston as it travels up and down. 
 Through the opening or port referred to, the charge of oil vapour and 
 air is drawn in from the carburetter on the up-stroke, and compressed 
 on the down-stroke, until released by the piston uncovering a con- 
 nection between the crank case and the top of the cylinder : the 
 charge then rushes into the cylinder, and at the same time drives 
 out the exhaust or burnt gases through the exhaust port which 
 has just opened : when the piston comes up to the top the spark 
 occurs and ignites the compressed mixture of oil vapour and air, 
 and explosion follows, driving the piston down, and, as before stated, 
 when near the bottom the exhaust port is uncovered, and shortly 
 afterwards the connection between the crank case and cylinder. 
 Observe that the exhaust port is opened just prei'ious to the inrush 
 of the fresh charge, which being at a slight pressure assists in forcing 
 out the burnt gases left from the previous stroke. 
 
 The two-cycle motor, it will be noticed, gives one impulse or 
 power stroke to each revolution. A disadvantage exists in the 
 confusion of the intake gases with those of the exhaust, which to 
 a certain extent reduces the effective energy developed, and which 
 increases with the number of revolutions per minute. This type of 
 motor, however, requires no valves or cams of any kind, as ports 
 only are required to admit and exhaust the gas and air. If two 
 cylinders are employed, the cranks are placed opposite to give good 
 balance and an even turning moment on the shaft. Both two-cycle 
 and four-c)'cle motors are single acting — that is, the power stroke 
 only occurs on one side (top) of the piston. 
 
 Four or " Otto " Cycle. — The action of a " four-cycle " oil motor 
 is as follows: — (i) On the down-stroke of the piston the air and oil 
 vapour are drawn into the cylinder through the inlet valves ; and 
 (2) on the following up-stroke the gas is compressed ; then (3) fired 
 by an electric spark, or a hot tube, set to act when the piston is near 
 or at the top centre ; the explosion which follows drives the piston 
 down, and on the next up-stroke (4) the burnt gases are expelled 
 through the exhaust valves, and out into the atmosphere b>' wa}' 
 of the "silencer." The inlet valves are sometimes worked by the 
 j piston suction and springs, and sometimes mechanically by a cam 
 fixed on a special shaft. The exhaust valves are opened b}' cams 
 
58o 
 
 " Verbal " Notes and Sketches 
 
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Internal Combustion Engines 
 
 581 
 
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5^2 " Verbal " Notes and Sketches 
 
 on the shaft referred to, and are kept shut by strong springs as 
 shown in the sketches. 
 
 Steam -Engine and Oil Motor compared. 
 
 Steam-Engine. — Coal stored in bunkers and containing heat energy 
 is supph'ed to the furnaces, and, combustion more or less complete 
 being effected, the heat obtained is transmitted through the furnace 
 metal, and evaporation of the water in the boiler results. The 
 imperfect steam gas thus produced passes along the steam pipe and 
 enters the cylinder, where the heat energy is emplo^^ed to drive the 
 pistons up and down, and so produce rotation of the shaft. After 
 doing work in the various cylinders, the steam finally exhausts to the 
 condenser, where condensation takes place, and the water thus ob- 
 tained is put back into the boilers as feed. During the process of 
 condensation most of the heat in the steam is absorbed by the 
 circulating water, and is thus lost overboard. 
 
 Oil Motor. — In the oil motor the boilers are deleted and the fuel 
 contained in the oil tank or bunker is supplied direct to the c}'linder 
 head, which also forms the combustion chamber. Combustion is 
 effected by a spark, and the energy thus developed is applied direct 
 to the piston, and acts on the down-stroke onl}-. The waste gases 
 produced by the rapid combustion are then exhausted out to the ' 
 atmosphere, and the whole of the heat contained is thus rejected. 
 Notice that a condenser cannot be fitted, so that no return of heat 
 is possible. 
 
 Again, it will be seen that to obtain the same impulse effect on 
 the crank-shaft four c}'linders are required if the motor is of the 
 '• four-cycle " type, and two cylinders if of the " two-cycle " t}'pe, to 
 be equal in effect to one double-acting steam cylinder. The chief 
 difference then exists in the fact that with steam as the motive power 
 ordinary combustion takes place in the furnaces of the boilers, whereas 
 with oil rapid combustion takes place direct in the cylinders, and the 
 heat energy developed during explosion does the work of turning the 
 shaft and propelling the boat. 
 
 In the steam-engine steam gas generated in the boilers is admitted 
 to the H.P. cylinder, and is cut off at say one-third stroke. This gas 
 expands, and after doing work in the H.P. is admitted to the larger 
 M.P. cylinder, where more work is done and further expansion takes 
 place ; the gas then expands into the still larger L.P. c)'linder, where 
 the last stage of work and expansion is completed, the gas then 
 passing into the condenser where condensation is effected. The 
 steam gas charge, be it noted, is only supplied to the H.P. cylinder, 
 and by expanding about twenty-two times or so altogether in the 
 other two larger cylinders, most of the effective energy is extracted 
 and useful work done. 
 
 The oil-gas engine, on the other hand, is a single-acting, and, of 
 
Internal Combustion EnQ^ines 5S3 
 
 course, non-condensing engine, each c}'linder requiring its own inde- 
 pendent charge of gas, and, as before stated, combustion is effected in 
 the cyHnder liead. The cyHnders are therefore all of equal diameter, 
 and the gas only expands in one cylinder. No condenser is possible, 
 so that after driving the piston down the expanded gases at a high 
 temperature are exhausted direct into the atmosjjhere through the 
 "silencer." The back pressure is therefore somewhere about 18 lbs. 
 per square inch absolute, whereas in the steam-engine the back 
 pressure is usually only about 2^ lbs. absolute, owing to the condenser 
 vacuum. 
 
 Number of Cylinders, &c. — Any number of cylinders may be 
 emplo)ed in an oil motor, but for small launches two or four is the 
 usual number. The number of c}'Hnders, in fact, depends on the 
 power required, and as man}' as six, eight, twelve, and eighteen 
 cylinders are occasionally fitted, according to the H.P. to be developed 
 by the motor. 
 
 The c}'linders are of cast iron, and are occasionally fitted with 
 liners, which allow better for the expansion of the upper end of the 
 c\iinder due to the intense heat of explosion. One or two cases 
 have come under the writer's notice of cylinder heads cracking, due to 
 the unequal expansion of the upper and lower portions. 
 
 Pistons. — The pistons, of cast iron, are kept tight by means of four or 
 six light Ramsbottom cast-iron rings, which are cut as usual. 
 
 The pistons are of the trunk t)'pe, being very deep in section, and 
 open at the bottom to the crank case, which is often arranged to form 
 an oil bath, thus suppl}'ing lubrication to the working parts by the 
 " splash " s}'stem. 
 
 Revolutions. — Developing full power, the revolutions vary in oil 
 motors from 700 to 1000 per minute, and therefore, neglecting miss- 
 fires and premature explosions, the average number of power strokes 
 in a " four-CNxle "' motor will be equal to one-half of the revolutions. 
 
 Water-Jacket. — Steam cylinders are sometimes fitted with steam- 
 jackets to keep up the temperature, whereas in oil motor c}'linders 
 cooling water-jackets are required to extract the intense heat pro- 
 duced by explosion, and thus keep down the temperature. The water- 
 jacket is a very important detail, and is indispensable. The tempera- 
 ture of the waste gases may be an)thing from 1000° to 1500° Fahr., 
 which fact in itself indicates the great waste of energy which goes on, 
 and which is evidently unavoidable. Sometimes the valve pockets 
 are also water-jacketed, and occasionally the exhaust gases are 
 arranged to pass round the carburetter to raise the temperature and 
 allow of quick vaporisation of the oil inside. 
 
584 "Verbal" Notes and Sketches 
 
 Pressures and Temperatures. — The pressure of compression just 
 previous to explosion varies from 50 lbs. to 70 lbs. or 80 lbs. per 
 square inch, and the pressure of explosion from 150 lbs. to 300 lbs. 
 per square inch. 
 
 Tiie temperature of the j^ases at explosion is estimated as being 
 somewhere ab(jut 1 500" Fahr. and upwards. 
 
 Carburetter. — The carburetter is a small chamber emplo}'ed to 
 vaporise the petrol and at the same time mix with it the proper 
 proportion of air. The openings are arranged to give from five to 
 ten parts of air to one of petrol vapour, but of course this varies 
 greatly with running conditions. Throttle valves are also fitted on 
 the carburetter to regulate both the amount of air supplied and the 
 amount of vapour admitted. A float and needle valve regulates the 
 oil supply to the mixing chamber of the carburetter. 
 
 A single carburetter is sufficient for any number of C}'linders, as 
 by suitable pipe connections the vapour can flow into each as 
 required. 
 
 Valves. — The valves are usually of the cam and poppet type, and are 
 opened and shut by means of a " half-time " shaft. This shaft is 
 connected up by gear wheels with the engine shaft so as to only give 
 one revolution for every two revolutions of the engine. It will be 
 noticed that the valves employed are similar to those of the historic 
 Smeaton and Watt engine, and were in use before the slide valve was 
 introduced. Recently, however, the " sleeve " type of valve has come 
 into more general use. 
 
 "Sleeve" Valve. — The "sleeve" valve consists of two cylindrical 
 casings fitted round the cylinder with ports cut in each ; the outer 
 sleeve is actuated by a link from the connecting rod, and when the 
 ports coincide the gas is admitted to, or exhausted from, the cylinder. 
 This type of valve is particularly silent in running, and gives very 
 little wear. 
 
 Fly- Wheel. — A fairly heavy fly-wheel is fitted to motors of both the 
 two-cycle and four-cycle types, the latter requiring the heavier wheel. 
 The fly-wheel makes for steady running balance, and also stores up 
 energy, which is released when the power strokes become irregular or 
 intermittent. The wheel is also convenient for use in starting up by 
 hand. 
 
 Firing or Sparking Plug. — This appliance is screwed into the 
 cylinder head, and, when possible, is placed direct in the path of 
 the incoming charge of vapour. One wire from the contact maker, 
 induction coil, and battery (or from the magneto contact brush of 
 this system) passes through the centre, and forms a point from which 
 
 I 
 
Internal Combustion Engines 585 
 
 the spark passes to the other point, whicli makes metallic contact 
 with the bod)' of the plug, and so to the cylinder, engine frame, 
 and battery, &c. The current, therefore, is "earthed," and after 
 sparking returns to the battery, &c., or magneto, by means of the 
 engine metal (Single Wire System). 
 
 Half Compression. — This is fitted in the larger engines for con- 
 venience in starting, and consists of a lip on exhaust cam extending 
 half its width. The whole cam is capable of sliding on its axis when 
 the half-compression lever is moved. Thereby, in one extreme 
 position the lip lifts the exhaust valve during the compression stroke 
 and releases the compressed air, making it much easier to pull the 
 engine over the centre ; in the other extreme position it clears the 
 valve tappet rod, and the exhaust valve is only opened on the exhaust 
 stroke. 
 
 " Cranking." — A petrol motor is started by having the engine dis- 
 connected from the propeller, and the handle connected to the shaft 
 or fly-wheel turned smartly round, with the half-compression valve 
 open to reduce the opposing back pressure. After a few revolutions 
 the spark acting at the right time catches up the running, and the 
 motor runs up to the ordinary revolution speed. The spark gear is 
 also "retarded," that is, set to fire when the piston has just passed 
 over the centre. The half-compression valves are, of course, shut 
 down once the motor takes up the speed, and the spark " advanced " 
 or set so as to fire just before the piston reaches the top centre. 
 
 In starting, care has to be taken in "cranking up" not to set the 
 motor running in the wrong direction, as this is very easily done, and 
 in some cases may be, to put it mildly, awkward. In one motor boat 
 in which the writer had an experimental run, the engine unfortunately 
 went off in the reverse direction, and as a counterbalance, rather than 
 stop (the motor being of the paraffin type and slow to heat up), the 
 angles of the propeller blades were simply reversed to suit the direc- 
 tion of rotation of the engine, and the run completed under these 
 conditions, which were certainly not the best. 
 
 During another run the motor stopped dead owing to wrong 
 adjustment of the oil or choking up of the supply pipe, and as before, 
 being a paraffin motor, the boat had to be allowed to drift about or the 
 oars employed for about ten minutes, until the pressure heating lamp 
 was set away and the carburetter heated up sufficiently to allow of 
 the motor starting again. This little exijericnce indicates very clearly 
 one of the drawbacks to paraffin, as, being what is known as a 
 "heavy" oil, it requires some considerable heating up before vaporisa- 
 tion takes place. At the same time, it should be stated that quite 
 recently a patent paraffin carburetter has been devised which is said 
 to "start from cold." Given a reliable ignition gear, the petrol motor 
 of the four-cycle t\'pe is certainly the sweetest-running motor of any ; 
 this, at least, is the writer's experience after many trials of other 
 
586 "Verbal" Notes and Sketches 
 
 types. At the same time, it is only right to state that paraffin-type 
 motor launches give every possible satisfaction, being steady and cool 
 in running, also easily and quietly stopped and reversed. 
 
 Ignition. — In petrol motors the greatest difficulty is experienced 
 in obtaining a reliable ignition gear, and the most frequent cause of j 
 stoppage is undoubtedly that due to defective ignition. The bestj 
 method of firing is at present a matter of much discussion and] 
 difference of opinion. 
 
 Some makers prefer the battery and "jump spark" system, others' 
 the magneto or " make-and-break " method of producing the firing] 
 spark. 
 
 The "jump spark " system offers the greatest complication of parts 
 with correspondingly increased risks of breakdown ; it also necessitates 
 the charging of chemical batteries, and some knowledge of electrical 
 science, while the magneto, on the "low tension" system, has fewer 
 working parts, and being a mechanical device, driven by the shaft, 
 presents less danger of breakdown. 
 
 Jump Spark. — In this ignition system the sparking points are both 
 fixed, and a current of high intensity being produced in the circuit, a 
 spark is generated between the two points referred to, and is therefore 
 called a "jump spark." 
 
 The ignition gear is made up of four separate and independent 
 parts. 
 
 1. Chemical cells or battery. 
 
 2. Induction coil or " intensifier." 
 
 3. Contact maker. 
 
 4. Firing plug. 
 
 All of the foregoing parts are, of course, liable to derangement and 
 breakdown, as they are affected seriously by damp and sea water. 
 
 Make-and- Break. — In the " make-and-break " system a small lever 
 rests against a pin and at the required time is drawn away from the 
 pin, thus leaving a small gap of about yV inch. The current endeavours 
 to follow up the moving lever, and as before, a spark results. In both 
 systems, then, the explosion is produced by means of an electric spark 
 arranged to flash out at the correct instant, so that in the case of a 
 four-cycle motor running at 800 R.P.M., about 400 sparks are pro- 
 duced per minute in each cylinder head. This means, then, a 
 constant shower of sparks require to be produced when the motor is 
 running. 
 
 Magneto and Spark Plug Ignition. 
 
 This system of firing is the best, being, as a rule, more reliable than 
 the " make-and-break " or coil and battery, and lasting longer without 
 

 I 
 
No. 4.— Simms Magneto (four-cylinder type). 
 
 2, Slip Ring. 
 
 6, Disrnbuter. 
 
 7, Collectoi Carbon Holder. 
 
 8, Distributer Caibon Holder. 
 
 10, Half-Speed Wheel and Spindle. 
 
 11, Timing Lever. 
 
 13, Scg;ment. 
 15, Milled Nut. 
 
 17, Ball Bearing. 
 
 18, Dust Cap. 
 
 21, Long Contact Breaker Screw. 
 
 22, Terminal. 
 
 25, Collector Brush and Spring. 
 
 26, Distributer Brush and Spring. 
 
 27, Central Connection. 
 
 30, Contact Breaker Lever. 
 
 31, Contact Piece. 
 
 NOTE.— The dimensions on the diagram are expressed in millimetres, 25 of wrhich are about equal to i inch, therefort 
 
 so millimetres = 2 inches (approx.). | fi,. 
 
 [7"«/fl« Mff 587. 
 
 I 
 
Internal Combustion Engines 5S7 
 
 requiring attention or repair. The magneto wiring is connected 
 direct to the sparking plug, and the spark passes across the platinum 
 points of the latter as in the coil and battery system. While the 
 engine is running the magneto is generating the current for the spark, 
 and, of course, when the engine is sto{)pcd the current ceases to flow, 
 no loss of current taking place. The magneto is usual!)' driven by 
 gear wheels off the main shaft, and the current is taken from the 
 small carbon brushes of the commutator by the positive wire direct 
 to the plug, the return or negative being made by means of the engine 
 metal back to the magneto, on the "single wire" system. The 
 magneto spark is much stronger than that of the' coil and battery 
 system, and jiroduces a much more powerful explosion of gas in 
 the cylinder, giving greater power. 
 
 The Simms Magneto (Four-Cylinder Type). 
 General Description. 
 
 The armature carries two windings, viz., the low-tension winding 
 (formed of a comparatively small number of turns of thick wire) 
 and the high-tension winding (composed of a very large number of 
 turns of a very fine wire). This arrangement entirely dispenses with 
 the necessity for the ordinary high-tension coil, such as is used in 
 connection with accumulators, owing to the fact that both the high 
 and low tension windings form an integral part of the magneto itself 
 
 The low-tension circuit is interrupted by the contact breaker twice 
 per revolution, thus giving two sparks per revolution, and the high- 
 tension current is led from the carbon holders or the distributer to 
 ordinary high-tension sparking plugs on the engine by means of the 
 usual insulated cable. 
 
 The diagram shows the connections of the " four-cylinder " type. 
 
 One end of the low-tension armature winding is connected to the 
 armature core, and thus to the frame of the magneto, and the other 
 end is led through the hollow spindle of the armature to the contact 
 breaker, the fixed portion of which, 31, is insulated, and carries a 
 platinum pointed screw, and the bell crank lever, which carries a 
 second platinum pointed screw, is connected to the frame of the 
 magneto. Both the bell crank lever 30 and the contact piece 31, 
 together with the contact breaker disc, revolve solid with the armature, 
 and as the fibre heel of the bell crank lever comes into contact with 
 the segments 13 the two platinum points are caused to break, owing 
 to the bell crank lever rocking about its pivot. This sudden inter- 
 ruption of the primary or low-tension circuit induces a current of very 
 high potential in the secondary or high-tension circuit, and gives a 
 flaming spark of great heat at the points of each of the sparking plugs 
 in turn. On the timing lever 1 1 is a milled nut and terminal for 
 making connection to the insulated terminal of a single pole switch. 
 One terminal of the switch should be connected to the frame of the 
 car. Connected to the terminal is a spring I3, which makes contact 
 
and Spring, 
 h and Spring, 
 ion. 
 Lever. 
 
 I 
 
 to I inch, therefort 
 
 [To face fa^c 587. 
 
Internal Combustion Engines 5S7 
 
 requiring attention or repair. The magneto wiring is connected 
 direct to the sparking phig, and the spark passes across the platinum 
 points of the latter as in the coil and battery system. While the 
 engine is running the magneto is generating the current for the spark, 
 and, of course, when the engine is stopped the current ceases to flow, 
 no loss of current taking place. The magneto is usually driven by 
 gear wheels off the main shaft, and the current is taken from the 
 small carbon brushes of the commutator by the positive wire direct 
 to the plug, the return or negative being made by means of the engine 
 metal back to the magneto, on the "single wire" system. The 
 magneto spark is much stronger than that of the* coil and battery 
 system, and produces a much more powerful explosion of gas in 
 the cylinder, giving greater power. 
 
 The Simms Magneto (Four-CyHnder Type). 
 General Description. 
 
 The armature carries two windings, viz., the low-tension winding 
 (formed of a comparatively small number of turns of thick wire) 
 and the high-tension winding (composed of a very large number of 
 turns of a very fine wire). This arrangement entirely dispenses with 
 the necessity for the ordinary high-tension coil, such as is used in 
 connection with accumulators, owing to the fact that both the high 
 and low tension windings form an integral part of the magneto itself. 
 
 The low-tension circuit is interrupted by the contact breaker twice 
 per revolution, thus giving two sparks per revolution, and the high- 
 tension current is led from the carbon holders or the distributer to 
 ordinary high-tension sparking plugs on the engine by means of the 
 usual insulated cable. 
 
 The diagram shows the connections of the " four-cylinder " type. 
 
 One end of the low-tension armature winding is connected to the 
 armature core, and thus to the frame of the magneto, and the other 
 end is led through the hollow spindle of the armature to the contact 
 breaker, the fixed portion of which, 31, is insulated, and carries a 
 platinum pointed screw, and the bell crank lever, which carries a 
 second platinum pointed screw, is connected to the frame of the 
 magneto. Both the bell crank lever 30 and the contact piece 31, 
 together with the contact breaker disc, revolve solid with the armature, 
 and as the fibre heel of the bell crank lever comes into contact with 
 the segments 13 the two platinum points are caused to break, owing 
 to the bell crank lever rocking about its pivot. This sudden inter- 
 ruption of the primary or low-tension circuit induces a current of very 
 high potential in the secondary or high-tension circuit, and gives a 
 flaming spark of great heat at the points of each of the sparking plugs 
 in turn. On the timing lever 11 is a milled nut and terminal for 
 making connection to the insulated terminal of a single pole switch. 
 One terminal of the switch should be connected to the frame of the 
 car. Connected to the terminal is a spring 12, which makes contact 
 
588 
 
 "Verbal" Notes and Sketches 
 
 with screw 2i. It will thus be seen that for one position of the 
 switch the terminal (which represents one end of the primary winding, 
 the other being permanently connected to the frame of the magneto) 
 is still insulated, but in the other position is joined to the frame of 
 the car, thus earthing both ends of the primary armature winding, 
 and causing the magneto to become inoperative, and consequently 
 stopping the engine. 
 
 The high-tension winding of the armature has one end connected 
 with the primary, or low-tension winding, and through this winding 
 to earth, the other end of the secondary, or high-tension winding, 
 being connected to the slip ring 2, from which the current is collected 
 by the carbon brush 25. In the "four-cylinder" type, as shown, the 
 
 No. 5. 
 
 current leaves the carbon holder and passes along the central con- 
 nection 27 to the distributer. A safety spark gap is formed between 
 the hollow spindle surrounding it, the central rod passing through a j 
 glass disc 40. The central connection is held in contact with the 
 central disc of the distributer by a spring. Connection is made 
 between the central disc and the distributer segments by a carbon 
 brush, which rotates with, and is insulated from, the half-speed wheel. 
 
 The safety gap is made sufficiently long to prevent the sp^i'k 
 passing here in preference to jumping the plug gap inside a high 
 compression cylinder. 
 
 To ensure satisfactory working, care must be taken that clean 
 contact is made between the slip ring 2 and the carbon brush, and 
 also between the distributer carbon 26 and the central contact piece 
 and segments in the distributer. \ 
 
Internal Combustion Engines 589 
 
 Setting the Magneto. — The four segments of the distributer 6 are 
 connected to the four terminals on the front of the distributer. The 
 terminals are numbered i, 2, 3, 4, in the order in which they fire. 
 The distributer carbon holder runs in the opposite direction to that 
 of the armature. 
 
 When viewed from the distributer end, the distributer carbon 
 holder rotates clockwise in a right-hand machine, and anti-clockwise 
 in a left-hand machine. 
 
 1. Set the piston of No. i cylinder of the motor exactly at the 
 top of the firing stroke. 
 
 2. Fully retard timing lever, which is done by moving the lever 
 as far as possible in the same direction as the armature rotates. 
 
 3. Rotate the armature in its proper direction until the distributer 
 carbon rests on No i. segment, and continue rotating slowly until 
 the distance A (see diagram on page 578) measures 7 millimetres, then 
 tighten all up. 
 
 4. Connect the magneto to the motor when both are in the above- 
 described positions, taking care there is no movement. It will be 
 found that the motor can be started more easily if the timing lever 
 is advanced as far as possible (usually about two-thirds) without 
 causing back-firing. 
 
 Motor Troubles. — Overfeeding with oil or petrol is a common 
 source of trouble, as this produces a mixture too heavy for the 
 digestion of the motor, resulting in miss-fires, premature explosions, 
 and slowing down or actual stoppage of the engine. The majority 
 of the owners of private motor launches have the fixed idea that if 
 the machine is not running satisfactorily it needs more fuel, with the 
 result above mentioned. It should also be noted that when the 
 charge is too heavy some of the oil or petrol is not vaporised at 
 all, and remains in the cylinder to perhaps form sooty deposits which, 
 remaining red-hot, may afterwards produce premature explosions, 
 or may form a carbon bridge across the points of the sparking plug 
 and thus do away with the spark altogether. The same remark holds 
 good if oil from the crank-case or " splash " lubrication system is 
 carried up into the cylinder head, as similar troubles may result. 
 
 Loss of Power in Engine. — Should there be a loss of power in the 
 I engine, the following points should be examined for the cause: — 
 
 . . Leakage at either the exhaust or inlet valve, sparking plug, or 
 ! piston rings. 
 
 Weak accumulators. 
 , Dirty sparking plugs (or contact breakers with low tension). 
 
 (Imperfect contact at the contact breaker, caused by weak spring 
 at contact hammer, or imperfect connection of high-tension wire to 
 plug screw, clue to screw being slack. 
 
 Carbonised oil on the fibre disc and contact pieces. 
 40 
 
590 "Verbal" Notes and Sketches 
 
 Fusing or burning of tiie platinum on the trembler of the 
 induction coil. 
 
 The formula very commonly quoted with reference to the economy 
 of internal combustion motors using gasoline is, " one pint per horse- 
 power hour." This is better than two-cycle engines can be depended 
 on to give, and small four-cycle engines will not give any such 
 figures except with care and under the best conditions. One pint per 
 horse-power hour means good conditions with the four-cycle engine of 
 moderate large size. Economy with an internal combustion engine 
 depends chiefly on the following conditions : — 
 
 (l.) Correct proportion of air to petrol vapour. 
 
 (2.) Correct degree of compression. 
 
 (3.) Prompt ignition and complete combustion. 
 
 The first step is combustion, or union with oxygen, and as the 
 gas itself will not burn, it must therefore first be mixed with a suitable 
 amount of oxygen. This is accomplished most cheaply and con- 
 veniently by using air, but even then such gases, when mixed with a 
 suitable amount of air, will not burn readily at ordinary pressures, 
 and it is not until they are compressed to a high degree that com- 
 bustion once started will act with sufficient vigour and rapidity to 
 produce the action desired. 
 
 Leaky Pistons. — It is of the utmost importance that the piston is 
 kept absolutely gas-tight, as should leakage occur, as will easily be 
 seen, the motor will not develop the full power. With a leaky piston, 
 compression will be less on the up-stroke, and the resultant explosion 
 on the down-stroke weakened in due proportion. 
 
 Colour of Exhaust Gases. — The colour of the exhaust gases leaving 
 the silencer affords a fair indication of the completeness of combustion 
 in the cylinders, as if the colour is strong it indicates incomplete 
 combustion. The more colourless, therefore, the waste gases appear, 
 the more complete is the combustion, and only a very faint tinge of 
 grey colour should be visible if the motor is working satisfactorily. 
 If any of the lubricating oil passes into the c}'linder it becomes burnt 
 and gives out a disagreeable smell, and also colours the waste gases; 
 a similar result may be produced by overfeeding with petrol or paraffin, 
 as incomplete combustion of the gas may take place in the cylinder head. 
 
 Composition of Exhaust Gases. — The following analysis of the 
 exhaust gases of an oil engine, using Russian Petroleum, is of 
 interest : — ; 
 
 { COo = 9-2 per cent. ' 
 
 Composition of E.xhaust Gases '' ^, ~ ^'^ " ' 
 
 )0 = 1-3 „ 
 
 ( N, &C. = 84 „ ; 
 
Internal Combustion Engines 591 
 
 Reversing:. — Reversing is usually effected b)' one of two methods. 
 
 {I.) Rexersible propeller, the blades of which can be rotated to 
 any angle by means of suitable gear contained in the hollow boss, 
 and actuated by a lever and rod, the rod passing through the hollow 
 tail shaft. This method is very much in favour at present, although 
 it is not the best as regards propeller efficiency. 
 
 (2.) By a reversing clutch, which is commonly arranged to give a 
 } direct drive from engine shaft to propeller when in the " ahead " 
 position, but which, by means of a gear box, reverses the propeller 
 shaft rotation when in the " astern " position, the gear box in that 
 case also revolving. It should be noted that in this case the propeller 
 speed for astern is only about half that for ahead. When in the 
 
 No. 6. — Gaines' Reversible Type Propeller. 
 
 intermediate position, both engine and propeller shafts are dis- 
 connected, and the engine thus running free, and with the load off, 
 requires a governor to check the speed. There are many types of 
 patent reversing gear now in the market, all claiming, of course, 
 certain advantages ov^er the others. 
 
 In cases where the engine is connected to the propeller shaft 
 through a reversing clutch, and where in consequence the engine may 
 be running without load, the throttle, in the best designs, is placed 
 under the control of an automatic governor of the centrifugal type, 
 thus placing the speed under limitation with any and all conditions. 
 
 Crank Arrangements. — It should be noted that to obtain the same 
 power, other conditions being the same, a. /bur-c}'/in(/er '' (our-cyc\c" 
 motor would be necessary to give the same power per revolution as 
 that of a single double-acting steam-engine cylinder. 
 
 NOTE. — When four cylinders are employed in the four-cycle system, the cranks 
 are generally arranged as follows, to produce two impulses per revolution :— 
 No. I cylinder, crank on top explosion taking place. 
 No. 2 cylinder, crank on bottom compression taking place. 
 No. 3 cylinder, crank on top admission taking place. 
 No. 4 cylinder, crank on bottom exhaust taking place. 
 
592 
 
 "Verbal" Notes and Sketches 
 
 Starting, &c. — Before starting a paraffin or petroleum motor, the 
 lamp burner is set away to heat up the oil vapour, and the oil supply 
 seen to be free to flow to the carburetter from the tank. The exhaust 
 valves are also eased back, and the engine turned round by hand to 
 force out any gas left behind in the cylinders. After the vaporiser 
 is sufficiently heated up, the supply cock to carburetter is opened and 
 the engine turned quickly by hand to start. If starting prove difficult, 
 it might be caused by insufficient heating up of the vaporiser or by 
 dirty or defective sparking gear. The oil supply should also be 
 examined in case the petrol is not flowing into the carburetter. 
 Piston speed is varied by means of the governor, which regulates the 
 petrol supply and sometimes the time of ignition. The fewer the 
 number of ignitions per minute, the slower the piston speed, and vice 
 versa, the speed of the vessel varying in proportion. A petrol motor 
 can be started at once by merely "cranking" and adjusting the spark, 
 as the petrol spirit vaporises instantly on passing the spra)' nozzle of 
 the carburetter. 
 
 Speed Regulation. — The speed of the engine is varied by one of the 
 following methods : — 
 
 (i.) Advancing or retarding the period of sparking, as advancing 
 the spark increases the speed, and retarding the spark decreases the 
 speed. 
 
 (2.) Shutting down the petrol supply to the carburetter. 
 
 (3.) Throttling the amount of the charge passing into the C}'linder. 
 
 (4.) Increasing the proportion of air to oil vapour, and thus 
 weakening the charge. 
 
 (5.) Easing the compression, and thus reducing the force of the 
 explosion. 
 
 Sometimes a combination of two of the above systems is employed, 
 and the governor is often arranged to both reduce the petrol supply 
 and retard the spark simultaneously. 
 
 Internal Combustion Engine 
 
 Troubles. 
 
 Symptom. 
 
 Cause. 
 
 Remedy. 
 
 Engine refuses 
 to start. 
 
 I. Faulty ignition. 2. Weak 
 compression. 3. Want of 
 petrol or water in petrol. 
 
 4. S[)ark plug broken. 
 
 5. Weak mixture. 6. 
 Spark plugs screwed into 
 wrong cylinders. 
 
 Examine wiring, lest plugs, 
 test for compression, jiut 
 petrol into cylinder 
 through compression 
 cock, take out plugs and 
 lest for spark in each 
 cylinder. 
 
Internal Combustion Eno-ines 593 
 
 Internal Combustion Engine Troubles — continued. 
 
 Symptom. 
 
 Cause. 
 
 Remedy. 
 
 Engine stops 
 suddenly. 
 
 T. No spark. 2. No petrol. 
 
 3. Choked carburetter jet. 
 
 4. Fault in coil or in 
 magneto. 5. Wiring short 
 circuited to metal of 
 engine. 
 
 Test spark plugs, test for 
 petrol supply, clear car- 
 buretter jet, examine and 
 test battery, coil, and 
 wiring for short circuit 
 or broken wire, &c. 
 
 I'vngine stops 
 gradually 
 and miss- 
 fires. 
 
 I. Weak spark. 2. Want of 
 petrol. 3. Carburetter 
 partly choked. 4. Spark 
 plugs fouled up with oil. 
 5. Wrong mixture. 
 
 Test spark plugs and ex- 
 amine coil contacts, 
 examine carburetter, ex- 
 amine petrol lank to see 
 if air-l)ound, &c. 
 
 Overheating. 
 
 I. Faulty circulation. 2. Pump 
 broken down. 3. Steam 
 lock in pipes. 4. Mix- 
 ture too rich in petrol. 
 5. Spark retarded. 6. 
 Exhaust throttled. 7. 
 Valve timing wrong. 8. 
 Silencer choked up with 
 carbon. 
 
 Test pumps and pipes for 
 water circulation, in- 
 crease air supply to 
 carburetter, test timing 
 of valves, examine 
 silencer. 
 
 Engine knock- 
 ing. 
 
 I. Faulty lubrication. 2. Igni- 
 tion advanced too far. 3. 
 Premature ignition. 4. 
 Worn bottom, end,ormain 
 bearings. 5. Cylinders 
 loose on bed plate. 
 
 Examine and test lubrication 
 system, put back igni- 
 tion lever, overhaul 
 engine for worn bearings, 
 &c. 
 
 Hissing noise 
 from engine. 
 
 I. Spark plug broken, joint 
 blown out between engine 
 and exhaust or between 
 engine and carburetter. 2. 
 Compression cock partly 
 open. 
 
 Test spark plugs, examine 
 joints mentioned, &c. 
 
 Loss of engine 
 power. 
 
 I. Loss of compression due to 
 leaky piston rings. 2. Too 
 much petrol. 3. Want of 
 lubrication. 4. Throttled 
 exhaust. 5. Wrong ad- 
 justment of valves. 6. 
 Faulty wiring, coil, bat- 
 tery or magneto. 
 
 Test pistons for compres- 
 sion, reduce petrol flow, 
 examine luliricator, test 
 timing of valves, examine 
 and test battery, C(m1, 
 wiring, and magneto. 
 
594 
 
 "Verbal" Notes and Sketches 
 Internal Combustion Engine Troubles— contimied. 
 
 Symptom. 
 
 Cause. 
 
 — 1 
 
 Remedy. 
 
 Hot crank-case. 
 
 I. Leaky pistons allowing gas 
 to enter crank-case. 2. 
 Cracks in cylinder. 
 
 Test for compression, ex- 
 amine for cracks. 
 
 Explosions in 
 silencer. 
 
 Mixture too weak to fill in 
 cylinder, one cylinder miss- 
 ing and charge afterwards 
 exploding in silencer. 
 
 Increase petrol supply, test 
 plugs for spark and for 
 timing of sjiark. 
 
 Red-hot 
 
 silt^ncer. 
 
 I. Using excessive gas. 2. 
 Spark too far retarded. 
 
 3. Exhaust throttled. 
 
 4. Faulty adjustment of 
 valves. 5. Choked up 
 silencer. 
 
 Give more air, advance 
 spark, test for timing of 
 valves, examine silencer. 
 
 Engine refuses 
 to stop. 
 
 I. Short circuit of wiring. 2. 
 Carbon deposit in cylinder 
 head or on plug spark 
 points (red hot). 
 
 Test wiring, examine plugs 
 and cylinder heads for 
 carbon deposits. 
 
 Engine refuses 
 to start. 
 
 Cylinders full of water owing 
 to leaky silencer or cracked 
 cylinder. 
 
 Examine silencer and cylin- 
 der heads, &c. 
 
 Blue smoke 
 from silencer. 
 
 Overheating due to faulty lubri- 
 cation or defective water 
 circulation. 
 
 Examine and test lubrication 
 system, and water cir- 
 culation. 
 
 Engine stops 
 when re- 
 versed. 
 
 Clutch jammed owing to dirt, 
 grinding of metal, or want of 
 lubrication. 
 
 Clean clutch and lubricate. 
 
 Engine refuses 
 to take up 
 drive. 
 
 Clutch slipping. 
 
 Examine clutch for wear, 
 clean clutch if over lubri- 
 cated, fit new collar if 
 required. 
 
Internal Comluistion Engines 595 
 
 Carburetter. — The carburetter needle valve should be f^^nnmd in 
 regularly, as if not the mixture will become too rich, and in some 
 cases the carburetter ma)' become flooded, resultini^ in loss of power 
 and probable stoppage of the engines. 
 
 Tests. 
 
 Spark Plugs. — Screw out the plug to be tested, and lay it on the 
 c\iinder top with the wire connected up; now turn engine round by 
 hand w ith s\\ itch on, and if there is no fault a s[)ark will show across 
 the points. 
 
 NOTE.- With the spark retarded the spark should show just as the piston 
 is passing the top centre, but if the spark appears when the piston is at half 
 stroke or thereabout, it indicates that the plugs have not been put into the right 
 cylinders, or that the timing of the spark is wrong. This fault shows when 
 starting up by back firing out of the air inlet. 
 
 Valves. — To test the timing of the valves, open compression cock on 
 cylinder top, and fit in a straight copper wire, now move engine b)' 
 hand and see if the inlet valve lifts just as the piston comes to the 
 top, and if the exhaust valve lifts just before the piston comes to 
 the bottom (every second stroke for a four-cycle motor) ; if not, alter 
 the washers o*n ends of valve lifting rods to either increase or 
 decrease the clearance as required. The exhaust valves should be set 
 to close down just before the piston commences the down (inlet) 
 stroke. 
 
 Battery. — For batter}- testing a small pocket voltmeter is required, 
 and when connected up with the positive and negative terminals of 
 the cell, the voltage indicated should not be less than 4-2. The cells 
 should be recharged ever)' four or six weeks. 
 
 Diagrams from Oil Motors. 
 
 Diagrams Nos. 7 and 8 show clearly what goes on above and below 
 the piston in this type of motor, as on the down-stroke simultaneous 
 expansion of gas after explosion above the piston and compression of 
 the next charge below the piston is taking place, and on the up-stroke 
 simultaneous admission of oil vapour below the piston and compression 
 of the previous charge above the piston. Observe that line I in A 
 and line i in B are described at the same time, also line 2 in A and 
 line 2 in B at the same time. As the bottom card represents work 
 done on the air and oil vapour by the piston, the actual work done is 
 equal to the difference in area of the two diagrams, A and B, and the 
 mean effective pressure is found b)' making this allowance. 
 
:^96 "Verbal" Notes and Sketches 
 
 Diagram No. 9, taken with a hght spring, shows clearly the 
 four operations which constitute the " Otto" cycle, so named from Dr 
 Otto, who first applied this principle to gas engines, (i.) The lowest 
 line shows the admission of air and oil vapour at a pressure rather 
 
 TOP 
 CENTRE 
 
 A.L 
 
 No. 7. — Diagram from Cylinder of Two-Cycle Motor. 
 
 below that of the atmosphere, the indicator pencil travelling from left 
 to right. (2.) The line rising and going from right to left shows the 
 compression of the gas on the up-stroke, the pressure increasing 
 to about So lbs. per square inch or so. (3.) At, or just before, the top 
 
 CD 
 TOP_. rnMPRESSION i 
 CENTRE 
 
 __A.L 
 
 < — ^ RELEAST 
 
 No. 8.— Diagram from Crank-Case of Two-Cycle Motor. 
 
 centre, the charge of air and oil vapour is fired and explosion follows, 
 as shown by the sudden rise of pressure to about 240 lbs. or more ; 
 the effect of the explosion is to drive the piston clown, the pressure 
 falling at the same time by expansion and loss of heat. (4.) On the 
 next up-stroke the exhaust valves open and the burnt gases are 
 expelled at a pressure just above that of the atmosphere, which is 
 seen by the sloping line crossing that of the compression curve. After 
 this the cycle begins again and repeats itself The arrows show the 
 direction of indicator pencil travel. 
 
Intcrn.'il Combustion Engines 
 
 597 
 
 The small numbers shown in the sketch indicate the successive 
 stroke in the same rotation as follows : — 
 
 TOP 
 
 CENTRE 
 
 No. 9. —Diagram from Cylinder of Four-Cycle Motor. 
 
 I, Admission. 2, Compression. 3, Explosion and Expansion. 4, Exhaust. 
 
 (i.) Down-stroke, air and oil vapour admission to cylinder. 
 (2.) Up-stroke, air and oil vapour compression in cylinder. 
 (3.) Down-stroke, air and oil vapour explosion in cylinder. 
 (4.) Up-stroke, burnt gases (CO., and N) expelled from c>'linder. 
 
 No. 10.— Typical Four-Cycle Diagram. 
 
 No. 3 stroke is the only working stroke of the four, and is kno\vn 
 as the "impulse" stroke, so that there is only owq poivcr stroke in 
 every four strokes, or in two revolutions. So that 800 revolutions per 
 minute require 400 sparks in each c}'linder of the motor. 
 
^98 "Verbal" Notes and Sketches 
 
 Diagram No. 10 shows the average pressures obtained in 
 ordinary petrol motors, and the dotted lines show the effect of retard- 
 ing the spark or ignition, which, it should be noted, has the effect of 
 slowing down the engine. 
 
 The loop shown in both the foregoing diagrams, and caused by 
 the crossing of the admission and compression lines, represents 
 negative work, and must be deducted from the diagram area to 
 obtain the effective work done, and to measure the mean effective 
 pressure in calculating the I.H.P. 
 
 No. II.— Heavy Spring- Diagram. 
 
 NOTE.— The scale of the diagram being small, the difference between the 
 admission line, atmospheric line, and exhaust line is imperceptible, as the three 
 lines merge more or less into one. 
 
 Mean Pressure. — As an oil engine is single acting, the mean 
 effective pressure is calculated from a single diagram, the method 
 adopted being similar to that for a steam-engine. The card is divided 
 into, say, ten divisions, or nine whole divisions and two half divisions, 
 and the pressures measured b}' the scale of the diagram on each line. 
 The ten pressures are then added together, and the result divided b}' 
 ten gives the mean effective pressure. 
 
 Indicated Horse-Power. — The I.H.P. is found b}- the following 
 formula, viz. : — 
 
 AxS'xN^xP_j TT p 
 33000^ 
 
 Where A - piston area in square inches. 
 S' — stroke in feet. 
 
 N ^ number of explosion strokes per minute. 
 P — mean effective pressure (from card). 
 33000 = foot-pounds per minute per I.H.P. 
 
 Brake Horse-Power. — In high-speed engines the I.H.P. as found by 
 calculation cannot always be relied upon ; it is therefore more satis- 
 factor)' to state the B.H.P., or actual power transmitted to the 
 propeller. The friction brake required to obtain this consists of a 
 double rope passed once round the fl)'-wheel, one end being secured to 
 
Internal Combustion Kneines 
 
 599 
 
 a spring balance hung overhead, and the other end sii|:)porting the 
 required amount of weights to balance the spring, when the engine is 
 running the average number of revolutions. 
 
 FLY WHEEL 
 
 No. 12.— Friction Brake. 
 
 S, Spring Balance. W, Weights. R, Rope Radius in feet, 
 NOTE.— The shaft is revolving from left to right. 
 
 The B.H.P. is found as follows : — 
 
 (W - S) X R X 2 X 3-1416 X Revolutions „ „ „ 
 
 — ■ = D.ri.tr. 
 
 33000 
 
 NOTE.— The difference in pounds of the weights and spring is the actual pull. 
 
 W = Pounds weight on rope. 
 S = Pounds shown by spring balance. 
 R = Radius of rope from shaft centre. 
 2 = Twice radius for diameter. 
 
 Types of Motors, &c. 
 
 The following descriptions of modern marine motors and motor 
 details are reprinted from various issues of " The Motor Boat," to the 
 proprietors of which journal the author's thanks are due for permis- 
 sion to reproduce both text and illustrations. 
 
 The Wolseley Carburetter. 
 
 This carburetter is of the float feed automatic t}-pe, fitted with an 
 auxiliar}- hand-controlled extra air inlet ; the float chamber and float 
 (A) are of the usual construction, and serve the customar)' purpose of 
 
6oo "Verbal" Notes and Sketches 
 
 maintaining a constant level of the jjetrol, which is supplied through 
 the pipe (B) in the spraying nozzle (C). Surrounding this nozzle is 
 a choke tube (D), supported by arms (E) fixed to a disc, the section 
 of which may be seen in the illustration, the whole being capable of 
 a vertical movement against the action of the helical spring (F). The 
 passage of the air when the engine is running is clearly shown by the 
 arrows, entering through the pipe (I), which leads from the neighbour- 
 hood of the exhaust system in order that warm air may be obtained ; 
 it passes up through the choke tube, and drawing the petrol from the 
 nozzle (C) in the form of a spray forms the explosive mixture which 
 issues from the top of the tube and reaches the motor through the 
 throttle (H) and the induction pipe. When the speed, and thus the 
 suction of the engine, increases, the disc attached to E is raised from 
 its seating, lifting with it the choke tube to the position shown by 
 the dotted lines, and air is allowed to travel through the ports 
 normally covered by it to the chamber (G) without passing over the 
 spraying jet, thus automatically adjusting the proportion of vapour 
 and air which is su]:)plied to the motor. The pressure of the spring 
 (F) tending to keep the disc on its seating may readily be varied by 
 altering the position of the screw cap which may be seen in the 
 illustration, thus enabling very accurate adjustment to be made. J is 
 an extra air inlet which may be moved by hand when desired. 
 
 This carburetter has proved itself to be thoroughly satisfactory in 
 use, the moving parts are very accessible, and, as has been mentioned 
 above, accurate adjustment can be made without dismantling any 
 part of the ajiparatus. 
 
 Thornycroft Type Carburetter. 
 
 It will be seen upon reference to the figure that the carburetter 
 consists of a float chamber and a vaporising chamber located in very 
 close proximity to one another. When the float (A) sinks, the needle 
 valve (B) is lifted by the balance levers (C), and petrol is allowed to 
 enter the chamber through the inlet (D). The top of the spindle (B) 
 is protected by a cap (E), which may be removed and the valve (B) 
 lifted when it is desired to flood the carburetter. Leaving the float 
 chamber by the port (F), the petrol gains access to the spray nozzle 
 (G) through the ducts (H and J). K is an adjustable spindle, 
 enabling the spray at L to be regulated by the movement of the 
 screw (M), a lock nut (N) maintaining the correct position of this 
 screw when the adjustment has been made. Should the duct (J) 
 
Internal Combustion Engines 
 
 60 1 
 
 ^^e X T R/=l n I R INLET 
 
 No. 13.— Wolseley Petrol Carburetter. 
 
6o2 
 
 "Verbal" Notes and Sketches 
 
 become obstructed it may be readily cleared upon removing the 
 screw (O), whilst the duct (II) is continued to the top of the float 
 chamber for the same purpose. The vaporising chamber is warmed 
 by a hot-water jacket (P), which is connected with the engine-cooling 
 system. This carburetter is of the hand-controlled type, no auto- 
 matic air valve of any kind being relied upon. The main air supply 
 is drawn in through the pipe (O), which has its intake in proximity 
 to the exhaust piping in order that warm air may be obtained, and, 
 
 =:Ss^ 
 
 No. 14. — Thornycroft Carburetter. 
 
 passing over the jet (L), forms the explosive mixture which is carried 
 to the engine through the induction pipe (R). The throttle valve (S) 
 is of the ordinary disc type, pivoted in the induction pipe at T. The 
 auxiliary air supply is controlled by a revolving collar (U), having 
 four holes bored in it, which may be made to coincide with four holes 
 — three of which may be seen at VV, bored in the pipe Q ; thus, by 
 moving the collar, the amount of air drawn in through the ports (W) 
 may be regulated. 
 
 The chief feature of this carburetter is its simplicity, whilst its 
 substantial construction should enable it to withstand a considerable 
 amount of rough usage. 
 
Intcrn.il Cuiiibuslion iMi^ines 603 
 
 18 H.P. Brooke Motor. 
 
 The 45 H.P. foiir-cxliiKlcr engine has all c)'lincler.s separately cast, 
 and in one piece with their combustion heads, the bore being 5 A inches 
 and the stroke 6 inches, with a normal running speed of 900 revolu- 
 tions per minute. Water-jacketing of the valve pockets has been 
 very well carried out, as ma\' be seen from the cross section, and they 
 are provided with extra large screw-in valve caps to simplify the 
 operation of removing the v^alve stem guides should this be necessary. 
 Except that the ends of the valve springs are hooked through the 
 valve stems instead of the more complicated collar and cotter arrange- 
 ment, there arc no special points in the valve and tappet gear, the 
 tappets being of the ordinary roller type. 
 
 Both cam-shafts are cai'ried by ordinary end bearings bolted to 
 the ends of the crank-case, and by split intermediate bearings sup- 
 ported b\' the cross-webs and held in position by set-screws. For 
 lightness the crank-shaft is hollow, as also are the crank-pins, one 
 end of the shaft carr\-ing the pinion of the two-to-one gear, the pinion 
 and both spur wheels being of phosphor-bronze, as the firm find that 
 quieter running is possible than with steel, while the bad wearing 
 ciualities of fibre wheels are avoided. On the other end of the crank- 
 shaft is the combined fly-wheel and clutch, which is of a special t}-pe, 
 very ingeniousl)' arranged, so that the thrust due to the clutch is 
 entirely self-contained. 
 
 The entering member of the clutch is free to slide on the squared 
 end of the tail shaft, and is normally kept in engagement by a spiral 
 spring bearing at its after end on a collar of the tail shaft. The 
 extreme forward end of the tail shaft is enlarged to form a flange (or 
 there ma}' be a disc bolted to the end face of the shaft), and this 
 flange is inside a flanged ring bolted to the after face of the engine 
 fly-wheel. Between these two flanges is a row of ball bearings, and 
 from the illustration it will be evident that these balls take the whole 
 thrust due to the clutch spring, which is tending to pull the tail shaft 
 aft, and also tending, with an equal force, to push the entering member 
 of the clutch forward. This thrust is transmitted to the other clutch 
 member, and then falls on the ball bearing between the two flanges 
 already described, so that the two stresses exactly neutralise each 
 other. 
 
 Returning to the crank-shaft. There is a main bearing between 
 each pair of cylinders, and these bearings, together with the big end 
 and cam-shaft bearings, are white metal lined, it being considered 
 that a really badly-heated bearing causes less damage by running out 
 
6o4 
 
 "Verbal" Notes and Sketches 
 
IntcM-nnl Combustion Eneines 
 
 605 
 
 the metal and starting a knock that makes it instantly necessary to 
 stop the engine, than would be done by the constant scoring that is 
 liable to occur with phosphor-bronze, which will continue to run until 
 it seizes up. With a view to reducing vibration as far as possible, the 
 pistons are made very light, with thin strengthening webs ; they each 
 have onl}' two grooves for piston rings, but there are two rings in each 
 groove, the idea being, of course, that gas getting through the slot in 
 one ring does not have an annular space (caused by the comparatively 
 I00S6 fit of the piston in the cylinder) by which to reach the slot in 
 
 No. 16.— Brooke Engine with Control Board. 
 
 the next ring, but is stopped at once by the second ring in the slot ; 
 it is for this reason that only two grooves are necessary. With 
 mention of the fact that the connecting rods are of H sectioned steel 
 stampings, the description of the engine proper is concluded. 
 
 Water circulation is maintained by a rotary pump of the eccentric 
 type driven off the cam-shaft, and the direction of the flow of water 
 in the jackets is, to a certain extent, guided by a web inside the 
 jackets, serving the double purpose of a baffle plate and of giving 
 extra strength to the c}'linders. 
 
 Splash lubrication is relied upon entirely, oil being fed in at the 
 41 
 
6o6 
 
 *' Verbal " Notes and Sketches 
 
 forward end of the crank-case from a sight-feed kibricator. There 
 is no separate feed to the pistons, as Messrs Brooke & Co. consider 
 that this system leads to sooting-up of the cylinder and a dirty 
 exhaust ; the piston truck, however, gets a good dose of oil at the 
 bottom of the stroke, since it projects a little below the cylinder, and 
 there is a point on the bottom of the internal web of the pistons 
 which catches oil and allows it to drip in a little pocket on the top 
 of the connecting rod to feed the gudgeon-pin bearing. 
 
 Little need be said about the Brooke carburetter, as it was recently 
 described in this journal, but it may be repeated that the throttle 
 governor attached to the carburetter is one of the special features 
 
 No. 17.— 18 H.P. Brooke Engine. 
 
 with which the Brooke engine is fitted. As regards ignition, there 
 is a tendency to abandon the low-tension magneto, which was at 
 one time much favoured by this firm, in favour of the latest Simms 
 high-tension pattern, which gives an extremely hot spark of very 
 high frequency, and is not therefore nearly so mucli affected by wet 
 as the ordinary high-tension electric circuit. Another point in favour 
 of this magneto is that starting is as easy as with coil and battery, so 
 low is the speed at which a spark is obtained. 
 
 The Meissner reversible propeller is supplied with a considerable 
 number of Brooke engines, but to those who prefer reversing gear a 
 very neat t)'pe has been evolved from the Adrian works. It is of the 
 sliding gear type, giving a direct drive ahead through a dog clutch 
 
Internal Combustion Enolnes 
 
 607 
 
 no wheels bcinf^ in motion except those which are out of mesh. On 
 the reverse the drive is, of course, throu^di two countershafts. The 
 rear is very compact and efficient, in addition to which it can be 
 
 No. 18.— Brooke Reverse Gear. 
 
 got very close to the bottom of the boat, is perfectly silent going 
 ahead, and far quieter astern than is usually the case. 
 
 OIL FUEL. 
 
 This method of firing has recently come very much to the front, 
 
 t i particularly in naval practice, and a brief description of the system 
 
 i will not be out of place The chief drawbacks to the use of oil fuel at 
 
 S present are those of supply and of cost ; oil supply ports being few in 
 
6o8 
 
 "Verbal" Notes and Sketches 
 
 number, although in time this matter will be remedied. The cost is 
 also a 'consideration, but this will also be adjusted to meet the 
 requirements of the demand. It may safely be stated that as fuel, 
 oil has a great future before it in marine practice. 
 
 Advantages of Oil Fuel over Coal. 
 
 1. Less bunker space required (about 36 cubic feet against 44 cubic 
 feet per ton), 
 
 2. Greater heat per pound (20,000 B.T.U. for oil against 14,500 
 B.T.U. for coal). 
 
 3. Cleanliness both in working and bunkering. 
 
 4. Reduced stoke-hole staff. 
 
 5. Greater control of fires. 
 
 6. More complete combustion obtained. 
 
 Disadvantages. 
 
 1. Difficulty of obtaining oil supplies. 
 
 2. Cost. 
 
 3. Danger from inflammable vapour caused b)' leakage into 
 bilges, &c. 
 
 4. Danger of oil leaking into steam side of heater and finally 
 entering boilers. 
 
 Oil and Coal Compared. 
 
 Fuel. 
 
 Heat units 
 per pound. 
 
 liunker space 
 per ton. 
 
 Coal - 
 
 Oil - - - 
 
 14,500 
 19,000 
 
 44 cub. ft. 
 3" ') )) 
 
 NOTE. — Taking into account both heating value and bunker space, one ton of 
 oil is equivalent to i-6 tons of coal. 
 
 The U.S. Naval Department Committee report on the advantages 
 of oil fuel as follows : — 
 
 1. A greater evaporativ^e efficiency in ratio of about 14 to 9. 
 
 2. A reduction in the fire-room force. 
 
 3. Elimination of ashes and dirty fires. 
 
 4. Convenience of storage. Oil tanks may be located in double 
 bottoms, in spaces now useless. 
 
 5. Rapidity and ease of taking aboard and handling. The manual 
 labour in this connection is eliminated. 
 
 6. Easy control of fires, permitting sudden variations in power 
 developed by boilers. 
 
Internal Combustion Enofines 
 
 609 
 
 7. Facility of controlling proportions of the air and fuel, thus 
 ensuring good combustion. There is no opening or shutting of 
 furnace doors o( var\ing thicknesses as ie the case with coal. 
 
 8. Elimination of cinders and of smoke, except at full power. 
 
 9. The reduction of fire room, there being no space required to 
 permit working of the fires. 
 
 10. As there is still a much better distribution of coal among the 
 seaports of the world than oil, this is said to be one of the principal 
 disadvantares of oil. 
 
 Composition of Oil. 
 
 as fuel are as follows 
 
 -The average composition, &c., of the oils used 
 
 Class. 
 
 Flash 
 Point. 
 
 Specific 
 Gravity. 
 
 Carbon 
 (C). 
 
 Hydrogen 
 (H). 
 
 Oxygen 
 (O). 
 
 Heat Units 
 per Lb. 
 
 
 
 
 Per Cent. 
 
 Per Cent. 
 
 
 
 Burmah 
 
 200° 
 
 •92 
 
 86 
 
 12 
 
 1-5 
 
 18,800 
 
 Shale - 
 
 125° 
 
 •81 
 
 86 
 
 13 
 
 I 
 
 19,000 
 
 Russian Petroleum 
 
 120' 
 
 •822 
 
 86 
 
 14 
 
 
 
 20,000 
 
 Methods of Working. — Oil is pumped into the tanks which act 
 as bunkers, and is afterwards pumped into direct supply tanks known 
 as " settling tanks." These tanks are generally placed at some height 
 above the floor plates, and are intended to allow any water which 
 may have become mixed with the oil to settle to the bottom, leaving 
 the pure oil on top. This oil, after being heated and filtered, is then 
 pumped under pressure direct to the burners which are fitted on the 
 front of the furnaces. 
 
 Oil Spray. — The oil, under pressure, is sprayed into the furnace 
 through the nozzle and needle valve of the former, and this results in 
 atomising of the oil which flashes up just after leaving the nozzle 
 point, the effect produced being that of a mass of gas at white heat 
 filling up the entire space of the furnace or combustion chamber. 
 
 Burners. — In one system the oil jet is mixed with steam as it enters 
 the burner, and in another system air only is mixed with the oil jet 
 and forced through the burner. In the Navy, however, the oil, at a 
 pressure of about 100 lbs. and temperature of 200' Fahr., is forced 
 through the burner, and the air (of usual forced draught pressure) 
 enters the slots of a si)ccially designed cone, and so mixes with the 
 rotary spray. The burner itself sits inside the air cone at a slight 
 upward angle, and the air enters first by air doors on the boiler front, 
 and from these into the slots of the cone previously mentioned. Each 
 
6io 
 
 "Verbal" Notes and Sketches 
 
 cone is boxed in by division plates so that the air supply is localised 
 to the corresponding burner. 
 
 h 
 
 i 
 
 No. 19 — " Kermode " Type Oil Burner. 
 
 The Admiralty type burner is similar in principle to the above, but is of muc 
 .mproved design, giving higher efficiency. 
 
 A, Oil feed to burner. 
 
 B, Nozzle. 
 
 C, Regulating spindle. 
 
 D, Burner body. 
 
 E, Cap nut. 
 
 F, Graduated wheel. 
 
 G, Pointer. 
 
 H, Grooves in nozzle end. 
 
 Shale Oil. — With Scotch shale oil a heating temperature of about 
 125" Fahr. is generally sufficient. 
 Specific gravity of CO = -96. 
 
1, Fuel pumps. 
 
 2, Suction from supply tanks. 
 
 3, Air vessel. 
 
 4, Dischargee from pump to cold filter. 
 
 No 20— Oil Fuel System. 
 
 5, Cold filter or strainer. 
 
 6, Heater. 
 
 7, Hot filter or strainer. 
 
 8, Distribution chest or header. 
 
 9, Oil fuel to burner. 
 
 10, Oil burner. 
 
 11, Air tight box. 
 
 12, Air cone 
 
 The above is the system in use m the Navy. 
 
 13, Air doors. 
 
 14, Steam to heater. 
 
 15, Drain from heater to feed tank. 
 
 16, Thermometer for oil temperature 
 
 {,7oj.u,/H,j;.t,i 
 
Internal Combustion Engines 6ii 
 
 fc> 
 
 Working Oil Fuel.— The oil fuel is pumped from the supply tanks 
 by the oil pumps, and forced through a cold filter, then through a 
 steam heater where the temperature is raised, next through a second 
 or hot filter, and from there to the distribution header on the boiler 
 front, from which valves and pipes connect to the several burners fitted. 
 In Yarrow t}'pe boilers from eight to eleven burners are supplied, 
 but of course all of these may not be required except when steaming 
 under full power conditions. The pressure of the oil is about 
 ICO lbs., and the temperature 200', with "shale" or "Texas" oil as 
 fuel. 
 
 Control. — The regulation of the fires is controlled by the needle 
 valve of the burner, which can be altered to increase or decrease the 
 angle of discharge, and therefore the output or consumption ; one 
 small wheel on the burner constituting the entire control gear. The 
 combustion of the oil is therefore regulated by the oil needle valve 
 and the air supply doors. 
 
 The oil fuel is pulverised by being forced, under pressure, through 
 the restricted opening of the burner end, which, by means of the 
 grooves, imparts a rotary motion to the jet, the latter being dis- 
 tributed in a cone-like spray or cloud of pulverised oil particles. 
 
 In the Navy the closed stoke-hole forced draught system is 
 employed, which means a constant and steady air pressure on the 
 oil fuel. 
 
 Starting Up. — In starting up the fires, a hand pressure pump is 
 employed, which forces a small quantity of oil through a (J -shaped 
 and flexible tube which is placed inside the air cone ; and, having 
 previously set fire to a quantity of oily waste, the heat so produced 
 raises the temperature of the oil flowing through the [J tube on its 
 way to the starting burner. After the starting burner has been the 
 means of raising sufficient steam to set away the oil pumps, the 
 starting device described is withdrawn, and the other burners are 
 set away. About three hours is allowed to get up steam in water 
 tube boilers. 
 
 Leakage Test. — Before the fires are started a leakage test of the oil 
 system is generally made by raising a pressure of 50 lbs. or more with 
 the hand pump, and examining for leaks at the tanks, pipes, joints, 
 bilges, &c. 
 
 Colour of Gases. — The colour of the gases in the combustion 
 chamber space indicates the efficiency of the combustion taking place 
 inside, and the pressure and temperature of the oil, in addition to the 
 output required, is regulated accordingly. A very small tail of smoke 
 at the funnel top indicates that combustion is practically complete. 
 The colour of the gases can be observed by means of sighting holes 
 in the boiler casings. 
 
Internal Combustion Engines 6ii 
 
 Working Oil Fuel. — The oil fuel is puinpcti from the supply tanks 
 by the oil pumps, and forced through a cold filter, then through a 
 steam heater wiierc the temperature is raised, next through a second 
 or hot filter, and from there to the distribution header on the boiler 
 front, from which valves and pipes connect to the several burners fitted. 
 In Yarrow t}'pe boilers from eight to eleven burners are supplied, 
 but of course all of these may not be required except when steaming 
 under full power conditions. The pressure of the oil is about 
 ICO lbs., and the temperature 200 , with "shale" or "Texas" oil as 
 fuel. 
 
 Control. — The regulation of the fires is controlled by the needle 
 vahe of the burner, which can be altered to increase or decrease the 
 angle of discharge, and therefore the output or consumption ; one 
 small wheel on the burner constituting the entire control gear. The 
 combustion of the oil is therefore regulated by the oil needle valve 
 and the air supply doors. 
 
 The oil fuel is pulverised by being forced, under pressure, through 
 the restricted opening of the burner end, which, by means of the 
 grooves, imparts a rotary motion to the jet, the latter being dis- 
 tributed in a cone-like spray or cloud of pulverised oil particles. 
 
 In the Navy the closed stoke-hole forced draught system is 
 employed, which means a constant and steady air pressure on the 
 oil fuel. 
 
 Starting Up. — In starting up the fires, a hand pressure pump is 
 emplo}'ed, which forces a small quantity of oil through a (J -shaped 
 and flexible tube which is placed inside the air cone ; and, having 
 previously set fire to a quantity of oily waste, the heat so produced 
 raises the temperature of the oil flowing through the [J tube on its 
 way to the starting burner. After the starting burner has been the 
 means of raising sufficient steam to set away the oil pumps, the 
 starting device described is withdrawn, and the other burners are 
 set away. About three hours is allowed to get up steam in water 
 tube boilers. 
 
 Leakage Test. — Before the fires are started a leakage test of the oil 
 system is generally made by raising a pressure of 50 lbs. or more with 
 the hand pump, and examining for leaks at the tanks, pipes, joints, 
 bilges, &c. 
 
 Colour of Gases.— The colour of the gases in the combustion 
 chamber space indicates the efficiency of the combustion taking place 
 inside, and the pressure and temperature of the oil, in addition to the 
 output required, is regulated accordingly. A very small tail of smoke 
 at the funnel top indicates that combustion is practically complete. 
 The colour of the gases can be observed by means of sighting holes 
 in the boiler casincrs. 
 
6i2 "Verbal" Notes and Sketches 
 
 Flash Point and Firing Point — It should be noticed that the 
 spray of atomised oil at a flash point of 200" is below the " firing 
 point," but on striking the cone ring, the temperature of which 
 exceeds the flash point, ignition instantaneously takes place. 
 
 Firing Point. — The firing point of oil is above the flash point, and 
 means that the oil itself (instead of the vapour) ignites. 
 
 Flash Point. — By this is meant the temperature at which the 
 vapour formed from heated oil flashes into flame when brought in 
 contact with a light. The flash point varies from 70" in light petrol 
 spirit to about 240° in heavy burning oils. The Board of Trade 
 require a flash point of not less than 185° Fahr. 
 
 Sand.— As a safeguard against fire, boxes of sand are placed ready 
 for use in the stoke-holes, as the sand thrown on oil flame quickly 
 extinguishes the same. 
 
 Black Smoke. — This is caused by the temperature or pressure of 
 the oil fuel being too low for complete combustion. 
 
 White Smoke. — This may be caused by excessive air supply or by 
 faulty oil feed through the burner. 
 
 Ventilation Pipes. — To allow for the escape of oil vapour " swan- 
 neck " pipes should be led from the top of the oil tanks to the deck, the 
 ends of the pipes being open, but covered with gauze wire to reduce 
 risk of explosion by a naked light. When the tanks are empty, 
 however, the vapour formed by slow evaporation is much heavier 
 than the atmosphere, and will therefore occupy the loivest positions in 
 the tanks, and the gases thus formed are best removed by means of 
 exhausting fans. 
 
 Air Vessel. — To maintain a steady oil pressure in the sprayers an 
 air vessel is fitted on the discharge side of the oil supply pump. 
 
 Settling Tanks. — Sometimes these tanks are fitted with a steam 
 coil to heat up the oil, the effect of which is to separate more quickly 
 the water ; the heating up causing a greater difference in the respective 
 densities of the two liquids. The heating is done by exhaust steam 
 of low pressure and temperature, so that there will be no danger of 
 the oil vaporising. A gauge glass is fitted on the tanks, and the 
 water shown can be drained off' by suitable drain pipes. 
 
 A temperature of 180° is required to produce separation of the 
 water from the oil in the settling tanks. 
 
 Air Cone. — The air cone (Sketch No. 29) is fitted with small air 
 openings round the shell, these being formed by three-sided cuts, the 
 
 I 
 
Wix —*iC-CA5C&i«f J: 
 
No 21 — Sulzer Marine Diesel Engine, 200 I.H.P. 
 
 Speed 
 
 Revolutions per minute 
 Dial Run ( I.H.P. 
 
 ' liour 
 
 < l.M.l'. 
 
 j Fuel per I.H.P. per lie 
 
 I Cost of fuel per mile 
 
 IO-6 knots. 
 
 300. 
 
 174. 
 
 •40 of a pound. 
 
 15 pence. 
 
 C7<>/a«/a;^6li. 
 
Internal Combustion Engines 613 
 
 fourth side being bent outwards to form the air opening. This 
 arrangement gives a centrifugal motion to the entering air and to the 
 oil spray, which effect chiefly accounts for the efficiency of this 
 system. 
 
 Evaporation of Oil. — i lb. of oil fuel evaporates about 15 lbs. of 
 water into steam (from and at a temperature of 212°). 
 
 Water in Oil. — In burning oil fuel, water shows by the oil forming a 
 brown coloured foam near the burner nozzle. Sputtering also occurs 
 at the burner, and if the water present is excessive, the burner flame 
 may go out altogether. 
 
 White Vapour. — In burning oil fuel white vapour at the funnel top 
 indicates that the oil vapour is passing off unconsumed owing to 
 excessive air supply, which lowers the temperature of combustion, 
 with the result stated. 
 
 Diesel Oil Engine. 
 
 Regarding the development and application of the Reversing 
 Internal Combustion Engine on a large scale, it is the opinion of 
 most experts that a great future exists for this type of engine, and 
 it would appear that this future is by no means far distant, since all 
 the more important yards are preparing to supply Diesel Marine 
 Engines, and, in many instances, the construction has already 
 been begun. 
 
 It was apparent, however, that not being direct reversing, its 
 application to large steamers was impossible, inasmuch as the 
 systems employed for reversing the screw by means of revolving 
 blades or reversing the propeller shaft by special gear, could never 
 offer the same amount of safety in a large ship, and for this reason 
 underwriters considered it a greater risk than the steam marine 
 engine. These difficulties were overcome, however, in the year 1906 
 by the invention and introduction by Messrs Sulzer Brothers of 
 Winterthur and Ludwigshafen-on-the-Rhine of the direct reversing 
 engine which transformed the Diesel engine into an actual marine 
 engine suitable for the very largest vessels in which the shafts remain 
 coupled direct to the engine, as is invariably necessary in large boats. 
 After an experience extending over three years with marine engines 
 of the above mentioned firm, which had been supplied for a number 
 of boats still in service, and in view of the fact that substantial 
 improvements have been introduced into the details of construction, 
 the advantages possessed by this engine are now easy to prove. 
 Compared with a boat driven by steam, a saving of about one-third 
 in the length of engine-room is effected, while the weight of the entire 
 plant is about one-fourth that of a steam-engine plant of equal power, 
 so that considerably more cargo can be carried with a corresponding 
 
Id. 
 
 LTo face /■ag;e 613. 
 
Internal Combustion luigines 6i 
 
 v) 
 
 fourth side being bent outwards to form the air opening. This 
 arrangement gives a centrifugal motion to the entering air and to the 
 oil spray, which effect chiefly accounts for the efficiency of this 
 system. 
 
 Evaporation of Oil. — i lb. of oil fuel evaporates about 15 lbs. of 
 water into steam (from and at a temperature of 212°). 
 
 Water in Oil. — In burning oil fuel, water shows by the oil forming a 
 brown coloured foam near the burner nozzle. Sputtering also occurs 
 at the burner, and if the water present is excessive, the burner flame 
 may go out altogether. 
 
 White Vapour. — In burning oil fuel white vapour at the funnel top 
 indicates that the oil vapour is passing off unconsumed owing to 
 excessive air supply, which lowers the temperature of combustion, 
 with the result stated. 
 
 Diesel Oil Engine, 
 
 Regarding the development and application of the Reversing 
 Internal Combustion Engine on a large scale, it is the opinion of 
 most experts that a great future exists for this type of engine, and 
 it would appear that this future is by no means far distant, since all 
 the more important yards are preparing to supply Diesel Marine 
 Engines, and, in many instances, the construction has already 
 been begun. 
 
 It was apparent, however, that not being direct reversing, its 
 application to large steamers was impossible, inasmuch as the 
 systems employed for reversing the screw by means of revolving 
 blades or reversing the propeller shaft by special gear, could never 
 offer the same amount of safety in a large ship, and for this reason 
 underwriters considered it a greater risk than the steam marine 
 engine. These difficulties were overcome, however, in the year 1906 
 by the invention and introduction by Messrs Sulzer Brothers of 
 Winterthur and Ludwigshafen-on-the-Rhine of the direct reversing 
 engine which transformed the Diesel engine into an actual marine 
 engine suitable for the very largest vessels in which the shafts remain 
 coupled direct to the engine, as is invariably necessary in large boats. 
 After an experience extending over three years with marine engines 
 of the above mentioned firm, which had been supplied for a number 
 of boats still in service, and in view of the fact that substantial 
 improvements have been introduced into the details of construction, 
 the advantages possessed by this engine are now easy to prove. 
 Compared with a boat driven by steam, a saving of about one-third 
 in the length of engine-room is effected, while the weight of the entire 
 plant is about one-fourth that of a steam-engine plant of equal power, 
 so that considerably more cargo can be carried with a corresponding 
 
6i4 "Verbal" Notes and Sketches 
 
 increase in freight receipts. A further increase in freights is obtained 
 by the reduced weight of h'quid fuel as compared with coal. This 
 amounts to 20-25 per cent, less than would be required for the 
 coal of a steam-engine of similar power. There is a further saving 
 in working expenses, as no stoker is required, no repairs to boiler 
 are ever necessary and fewer hands are required to attend to the 
 machinery. 
 
 In the Diesel engine all physical processes for converting the 
 fuel into energy take place inside the working cylinder. Combustion 
 of the liquid fuel, which is introduced by means of compressed air, 
 takes place automatically in the hot air obtained by compression in 
 the working cylinder. The combustion is gradual, there is no increase 
 of pressure and, consequently, no explosions. The motor is started 
 by means of compressed air, which is stored at a pressure of about 
 800 lbs., and the supply is sufficient for twenty starts without 
 replenishing. Compressed air is admitted to the cylinders by simply 
 turning a wheel, a further turn puts the starting valve out of gear, and 
 operates the fuel valve, and the engine then begins to work upon the 
 introduction of the fuel. In the same way the engine is brought to a 
 standstill, restarted, and reversed. These engines require much less 
 attention than a steam-engine, the supply of liquid fuel to the 
 cylinders is automatic, and, therefore, one engineer is sufficient to 
 look after the engine. One great advantage in favour of the Diesel 
 motor as a marine engine and deserving of special mention is the fact 
 that it is always ready for use, and being on the two-stroke principle, 
 only the starting and fuel valves on each cylinder require reversing. 
 
 The following descriptions of the action of the Diesel type 
 marine engine are taken from a paper by J. T. Milton, Esq. (Vice- 
 President), read before the Institution of Naval Architects, 6th 
 April 191 1 : — 
 
 " It may be well to state here what is claimed for the Diesel 
 engine in the way of consumption. In an ordinary steam-engine 
 the power is generally reckoned as indicated horse-power. This is 
 the work performed by the steam on the piston, and is the gross 
 power obtained. It has to overcome the friction of the mechanism, 
 work the slide-valves and the pumps, and only about 85 per cent, in 
 round numbers is transmitted to the shaft. 
 
 " In the Diesel engine the indicated horse-power has similarly to 
 overcome the friction of the mechanism, it has to work the fuel-pump, 
 the mechanism for actuating the valves, and to supply the com- 
 pressed air necessary for injecting the fuel. In the two-stroke cycle 
 also it has to work the scavenging pump. These take up more of 
 the gross power than do the accessories in a steam-engine, and hence , 
 a less proportion of the gross, or indicated power, is transmitted to i 
 the shaft than in a steam-engine. P'or this reason the power of a ; 
 Diesel engine is more usually expressed as its brake horse-power — ! 
 that is, the power usefully exerted outside itself. 
 
Internal Combustion Engines 615 
 
 " It is usually claimed that the oil consumption per brake horse- 
 power per hour is 04 lb. when the engine is working at full power, 
 and when working at somewhat lower powers the rate of consumption 
 is not much increased. 
 
 " If one assumes that in a modern steam-engine the consumption 
 of coal is 1-25 lbs. per indicated horse-power per hour this corresponds 
 to about I 47 lbs. per brake liorse-power, so that the weight of fuel to 
 be carried for the same voyage in a vessel fitted with Diesel engines 
 would be only 28 per cent, of that of the coal necessary with ordinary 
 steam-engines. 
 
 "We will now turn to the engine itself. Its principle of working 
 is generally known. It is made in three forms for marine purposes — 
 viz., as a four-stroke cycle single-acting engine, a two-stroke cycle 
 single-acting engine, and a two-stroke cycle double-acting engine. 
 An essential feature of these engines is that they require, besides 
 their own cylinders and pistons, an auxiliary air-compressor capable 
 of producing a pressure of about 700 lbs. per square inch. 
 
 "In the four-stroke cycle-engine the cylinder-cover contains a 
 fuel-valve, a compressed-air admission-valve, one or more ordinary 
 air-admission valves, and one or more exhaust-valves. All these 
 valves are actuated — that is, opened — by means of cams fixed to a 
 cam-shaft, and are kept closed by powerful springs when the cams 
 are out of action. The cam-shaft is driven by a two-to-one gear — 
 that is, it makes only one revolution for two revolutions of the engine 
 crank-shaft. Broadly speaking, the cams are so arranged that the 
 air-admission valves are open during one whole down-stroke, and the 
 exhaust-valves during one whole up-stroke, but actually a little 'lead' 
 is necessary. The cams for the fuel-valve and the compressed-air 
 valve are so arranged that only one of these can be in operation at 
 a time, so that when either is in use the other is entirely inoperative. 
 In ordinary running, the fuel-valve is opened at the proper time when 
 the piston is at the top of its travel, and is closed again when about 
 one-tenth of the downward stroke has been made. The compressed- 
 air valve is only used for starting purposes, and it is kept open for 
 a longer period — say, for half or even more of the stroke— its range 
 of opening being made to depend upon the number of cylinders used, 
 so that when these valves are in gear there is no position of the 
 engine in which there is not at least one of them open. 
 
 " In starting the engines these valves are put into gear, and the 
 fuel-valves are consequently put out of action. When the engine has 
 made one or more complete cycles, the compressed-air valves are put 
 out of gear, the fuel-valves commence their work, and the engine then 
 continues its motion, working under ' fuel ' conditions. As the air- 
 admission valve-gear is in full operation during the starting opera- 
 tions, the full compression would have to be overcome in each cylinder 
 in turn, if it were not for a special arrangement made to relieve part 
 of the pressure in order to facilitate starting. This is put out of 
 action when the fuel admission is put into gear. 
 
6i6 "Verbal" Notes and Sketches 
 
 " Commencing with a piston at the top of the cylinder, the four- 
 stroke cycle is as follows : — 
 
 " First Down-Stroke. — The ordinary air-admission valve is opened 
 during the whole stroke, and the cylinder becomes filled with atmo- 
 spheric air at the ordinary atmospheric pressure. 
 
 " Second Stroke. — The air-valve is closed, and the piston returns 
 to the top of the cylinder, compressing the air which has been drawn 
 in during the previous stroke. The clearance is so proportioned that 
 in ordinary working at full speed the pressure becomes about 500 lbs. 
 per square inch, and the temperature is, at the same time, very much 
 raised. The compression is not quite adiabatic, as the cold cylinder 
 walls must abstract a little of the heat from the air. If it were truly 
 adiabatic the temperature of the air would be raised from, say, 60° 
 Fahr. to 1000° Fahr. 
 
 " During this stroke a quantity of fuel has been pumped by the 
 fuel-pump into an annular space round the fuel-valve. When the 
 piston is at the top of the stroke, the fuel-valve is raised, and, at the 
 same time, cold air from the air-compressor reservoir at a pressure of 
 700 lbs. per square inch blows the fuel into the cylinder, which con- 
 tains hot air, at a pressure of 500 lbs. per square inch. The construc- 
 tion of the fuel-valve is such that the oil is pulverised or atomised — 
 that is, it is divided up into a spray of very fine particles. These, 
 upon coming into the very hot air in the cylinder, ignite, and the heat 
 produced by the combustion increases the volume or the pressure of 
 the air. When the adjustment of the valve is correct, the admission 
 of the fuel and the combustion proceed at such a rate that they are 
 almost completed during the time taken for the piston to travel one- 
 tenth of its stroke, and during this period the pressure of 500 lbs. per 
 square inch is maintained. 
 
 " Third Stroke. — The third stroke of the cycle commences with 
 the combustion of the fuel as mentioned above, after which, during 
 the remainder of the stroke, the hot gases in the cylinder expand 
 until the end of the stroke is reached. 
 
 " Fourth Stroke. — The return of the piston constitutes the fourth 
 stroke, and during this time the exhaust-valves are open, and the 
 burnt gases are expelled from the cylinder. After this the cycle 
 commences afresh. 
 
 " In the two-stroke cycle single-acting engine, the cylinder covers 
 are similarly fitted with fuel valves and compressed-air valves for 
 starting purposes, but the ordinary air-inlet valves and exhaust valves 
 are replaced by scavenge air-valves. All these valves are actuated by 
 cams ; the cam-shaft, however, in these engines rotates at the same 
 speed as the main engine shaft. 
 
 " The pistons are made somewhat deeper than the total length of 
 stroke. At the lower end of the part of the cylinder barrel uncovered 
 by the movement of the piston, there are numerous ports leading into 
 the exhaust passage. These ports have a vertical dimension of about 
 one-seventh of the stroke. 
 
f^CycU 
 Intake 
 
 r 
 
 \ 
 
WORKING DIAGRAMS or SINGLE-ACTING DIESEL ENGINES. 
 
 t^Cycit 
 IntxxJce 
 
 Z"^ Cycle 
 
 FOUR-STROKE CYCLE. 
 
 3'-''Qrcle. 
 \ycrkin q Stroke . 
 
 4*Cycle. 
 EscJifuc^-t 
 
 1^ Cy cle 
 
 Sccwenging. 
 
 Campi 
 
 TWO-STROKE CYCLE. 
 
 2' ^QrxJ.e. 
 
 ^Workuuj Stroke. Ecchaust) 
 
 INDICATOR DIAGRAMS OF SINGLE-ACTING 
 
 DIESEL ENGINES. 
 
 {TAKEN FROM ORIGINAL DIAGRAMS.) • 
 
 IP— 1 
 
 -> FOUR-STROKL CyCLt 
 
 
 \ 1. Intake. 
 
 20- 
 
 \ .". Compression. 
 1 \ 3. Workutg Stroke 
 \ \ ■* Eochcuist 
 
 ^ ' 
 
 \ ^v 
 
 
 V \-.^^__^^^ 
 
 
 -J^^-— — ^ ~~~^ 
 
 
 i 
 
 TWO-STROHE CYCte. 
 
 1. Scavenijing. 
 2- Ccmpr&sstcn . 
 3. Working Stroke^. 
 4 Exhfucst. 
 
 [7'0/ace pa^. 6x6. 
 
Internal Combustion Engines 617 
 
 " The two-stroke cycle is as follows : — 
 
 " First Stroke. — When the piston is at the bottom of the stroke 
 the cylinder is full of pure air at atmospheric pressure, which air has 
 just been admitted throuj^h the scavcnge-valve. During the up-stroke 
 the air is comi)ressed up to 500 lbs. pressure per square inch, precisely 
 as in the compression stroke of the four-stroke c)'cle engine. 
 
 " Second Stroke. — The second stroke commences at the top centre 
 by the admission of fuel sprayed in by compressed air precisely as in 
 the previously described engine, and the stroke proceeds in exactly 
 the same way until the piston has travelled about six-sevenths of the 
 stroke. At this point it commences to uncover the exhaust ports 
 through the cylinder sides. So much of the hot gases escape through 
 these ports as to reduce the pressure in the C}'linder to about tl>at of 
 the atmosphere. The scavenge-valves are then opened, and fresh air 
 under pressure is admitted into the C}'linder, blowing out the re- 
 mainder of the burnt gases into the exhaust passages. With these 
 gases some of the scavenge air also passes into the exhaust. By the 
 time the piston has reached the bottom of its stroke the scavenge- 
 valves are closed, but the cylinder is left full of clean air ready for the 
 compression stroke to commence. 
 
 " There are different arrangements made by different makers for 
 suppl)-ing the scavenge air. In some designs each main cylinder has 
 its own air-compressing arrangement and receiver. In other designs 
 sometimes one, and sometimes two, air-pumps are provided, sometimes 
 worked b)' cranks from the crank-shaft, and in some cases by levers 
 similar to the method of working air-pumps in ordinary marine 
 steam-engines. 
 
 "There are also different methods of applying the scavenge-air, 
 one allowing it to enter through special valves in the cylinder cover, 
 another by admitting it at one side of the bottom of the cylinder 
 through ports uncovered by the piston in the same way as the exhaust 
 ports are uncovered. In this latter case the scavenge ports are on one 
 side and the exhaust ports on the other. 
 
 " The volume of the scavenge air-pumps is considerably greater 
 than that of the cylinders, the proportion being in general not less 
 than 1-8. This is necessary to ensure that all the burnt gases will be 
 swept out of the cylinder. As the full quantity of air dealt with by 
 the pump must pass from the reservoir into the cylinders every revolu- 
 tion, the pressure to which the air in the reservoir attains depends 
 upon the scavenge-valve openings. When these are large a less 
 pressure is required to force the air through them than when they are 
 small. Hence the larger the openings of these valves the less load 
 there is thrown on the scavenge air-pump. 
 
 " In some designs the scavenge air-pressure is as much as 7 lbs. to 
 8 lbs. per square inch, in others it is as low as 3 lbs. to 4 lbs. above 
 the atmosphere. 
 
 " In the preceding engines the pistons are of the trunk form. In 
 the double-acting two-stroke cycle engine they are necessarily made 
 
.4'&J. 
 
Internal Combustion Engines 617 
 
 " The two-stroke cycle is as follows : — 
 
 " First Stroke. — When the piston is at the bottom of the stroke 
 the cylinder is full of pure air at atmospheric pressure, which air has 
 just been admitted throuy;h the scavcnge-valve. During the up-stroke 
 the air is com[)ressed up to 500 lbs. [)rcssure per square inch, precisely 
 as in the compression stroke of the four-stroke c)'cle engine. 
 
 " Secotid Stroke. — The second stroke commences at the top centre 
 by the admission of fuel sprayed in by compressed air precisely as in 
 the previously described engine, and the stroke proceeds in exactly 
 the same way until the piston has travelled about six-sevenths of the 
 stroke. At this point it commences to uncover the exhaust ports 
 through the cylinder sides. So much of the hot gases escape through 
 these ports as to reduce the pressure in the cylinder to about tlnit of 
 the atmosphere. The scavenge-valves are then opened, and fresh air 
 under pressure is admitted into the cylinder, blowing out the re- 
 mainder of the burnt gases into the exhaust passages. With these 
 gases some of the scavenge air also passes into the exhaust. By the 
 time the piston has reached the bottom of its stroke the scavenge- 
 valves are closed, but the cylinder is left full of clean air read)- for the 
 compression stroke to commence. 
 
 " There are different arrangements made by different makers for 
 suppl)-ing the scavenge air. In some designs each main cylinder has 
 its own air-compressing arrangement and receiver. In other designs 
 sometimes one, and sometimes two, air-pumps are provided, sometimes 
 worked by cranks from the crank-shaft, and in some cases by levers 
 similar to the method of working air-pumps in ordinary marine 
 steam-engines. 
 
 "There are also different methods of applying the scavenge-air, 
 one allowing it to enter through special valves in the cylinder cover, 
 another by admitting it at one side of the bottom of the cylinder 
 through ports uncovered by the piston in the same way as the exhaust 
 ports are uncovered. In this latter case the scavenge ports are on one 
 side and the exhaust ports on the other. 
 
 " The volume of the scavenge air-pumps is considerably greater 
 than that of the cylinders, the proportion being in general not less 
 than 1-8. This is necessary to ensure that all the burnt gases will be 
 swept out of the cylinder. As the full quantity of air dealt with by 
 the pump must pass from the reservoir into the cylinders every revolu- 
 tion, the pressure to which the air in the reservoir attains depends 
 upon the scavenge- valve openings. When these are large a less 
 pressure is required to force the air through them than when they are 
 small. Hence the larger the openings of these valves the less load 
 there is thrown on the scavenge air-pump. 
 
 "In some designs the scavenge air-pressure is as much as 7 lbs. to 
 8 lbs. per square inch, in others it is as low as 3 lbs. to 4 lbs. above 
 the atmosphere. 
 
 " In the preceding engines the pistons are of the trunk form. In 
 the double-acting two-stroke cycle engine they are necessarily made 
 
6i8 "Verbal" Notes and Sketches 
 
 of box form, and are fitted with piston-rods, which, as they pass 
 throu^^h the burning gases at the lower side of piston, have to be 
 specially cooled. The pistons also, in general, have to be cooled by 
 either oil or water circulation. 
 
 "Water is the best cooling medium, as its specific heat is about 
 three or four times that of oil, but some prefer oil, as any leakage from 
 the water circulation washes off the lubrication of any of the rubbing 
 parts which it touches. 
 
 " The admission, fuel, &c., valves, are designed for both the top 
 and bottom of the cylinder. The exhaust ports are in the middle of 
 the length of the cylinders, and the pistons, as in the single-acting 
 engines, uncover the ports at nearly the end of the stroke. 
 
 " In small engines of the single-acting type the pistons are not 
 water or oil cooled, as it is found they may be kept at a sufficiently 
 low temperature by their contact with the cylinder sides, which are 
 water-cooled. A heated piston is not so objectionable as it is in an 
 ordinary gas or oil engine with timed ignition, because, in the Diesel 
 engine, pre-ignition cannot occur. The main objections are that, with 
 a large piston, overheating of the crown may be the cause of structural 
 weakness, and that the expansion of the metal by its high temperature 
 renders it necessary to make the piston crown initially smaller than 
 the c}'linder bore. This has to be arranged in all engines, and the 
 exact amount of allowance is one of those points in which experience 
 is the only guide. It may be said here that this is a matter of extreme 
 importance in those engines in which there are no piston-rods. This 
 will be again referred to further on. 
 
 " Experiments are being made in the case of an engine with a large 
 diameter of cylinder, to ascertain whether it is practicable to run it 
 without special piston cooling. 
 
 "In all the types of engines highly-compressed air is needed for 
 starting purposes, and also for the fuel injection. This has to be 
 supplied by an air-compressing plant worked by the main engine. 
 The compression is sometimes performed in two stages, although a 
 three-stage arrangement is generally used. The compressed air is 
 cooled at each stage. The volume of the compressor is such as to 
 provide a small surplus each revolution over that required for the fuel 
 admission in continuous working. This surplus is stored in a reservoir 
 constructed usually as a battery of seamless steel bottles. These are 
 tested by hydraulic pressure to 120 atmospheres. A safety valve is 
 provided loaded to 60 atmospheres. The compression of the air is 
 attended by the deposition of moisture from it, so that means of drain- 
 ing the steel bottles should be provided. 
 
 " Naturally there are advantages and disadvantages with each 
 type of engine, and a judicious consideration of these should determine 
 which is the more suitable type to use in any particular case. The 
 two-stroke double-acting engine will be higher than a single-acting 
 one with the same diameters of cylinders and stroke, but the power 
 will be obtained with a less number of cylinders. On the other hand, 
 
IntcriKil Coniljustioii l^igines 
 
 619 
 
 there is considerably more complexity in the valve arrangements, and 
 a probability of difiiculty with piston-rod stiiffinj^-boxes, to say nothing 
 of the trouble of cooling the pistons and rods by water or oil circula- 
 tion. There is also likely to be considerable difficulty, owing to want 
 of access for overhauling. It should be stated that no experience has 
 been had, as yet, with large engines of this type. 
 
 " Comparing single-acting engines of the two-stroke and four 
 stroke types, the former require onl)- half the number of cylinders 
 
 No. 23. — Air Inlet Valve and Exhaust Valve. 
 
 (Fuel Valve in Centre.) 
 
 which are requisite in the latter, either to produce the same power or 
 the same degree of uniformity of turning moment. The four-stroke 
 therefore means a longer engine, and necessarily a heavier one also 
 The valve-gear of the two-stroke engine, being actuated b)' a shaft with 
 the same rotational speed as the crank-shaft, is simpler than that in a 
 four-stroke engine, and the reversing arrangements are much less 
 complicated. The two-stroke, however, requires the addition of the 
 scavenge arrangements which are absent from the four-stroke, and 
 
620 
 
 "Verbal" Notes and Sketches 
 
 the necessity for supplying the energy for working these makes the 
 mechanical efficiency less. On the question of efficiency, however, it 
 may be urged that the four-stroke engine has to overcome the friction 
 of the piston, &c., for what maybe called two idle strokes out of every 
 four, and this must, to some extent, counti^rbalance the energy neces- 
 sary to work the scavenging pumps. In the four-stroke engine all the 
 hot used gases have to escape jiast the exhaust-valves, which thus may 
 
 I 
 
 ■* ; 
 
 No. 24. — Exhaust Valve, I.ever, and Cam. 
 
 become abnormally heated. On the other hand, in the two-stroke 
 engine they have to pass the bars between the exhaust-ports, and it is 
 thought by some that although these parts of the cylinder are water- 
 jacketed, they must become over-heated and lose their accuracy of 
 surface, and it must be remembered that all the piston-rings have to 
 pass these bars every stroke. Extended experience will be required 
 to settle all these points. It may be mentioned that an engine is 
 
Internal Combustion Engines 
 
 621 
 
 beinf^ made on the four-stroke system in which the major portion of 
 the_ exhaust passes out of the cyHnder throut^h ports precisely 
 as in the case of the two-stroke engine, leaving; only a part of the 
 burnt gases to be pushed out of the c}'linder through the ordinary 
 exhaust-valves. 
 
 Starting Handle 
 
 No. 25.— Fuel Inlet Valve, Lever, and Cam. 
 
 Fuel Valve. — The oil from the fuel i)ump enters through the 
 pipe A, the amount being regulated by the pump governor to suit 
 the engine load. The oil flows clown the c\-lindrical space K, and 
 enters the receiver C through the small opening D near the bottom, 
 and just above the spray nozzle. The sprayer consists of four metal 
 rings F, each containing over twenty small holes, which are arranged 
 42 
 
622. 
 
 Verbal " Notes and Sketches 
 
 in "staggered" form, the holes being about jV inch diameter. 
 Below the rings is a conical shaped fitting supplied with narrow 
 channels (about /,; "ich deep), which form a series of nozzles through 
 which the oil travels after passing the holes in the rings. The oil 
 then enters the c}'lindcr head by the expanding shaped opening 
 below the needle valve. The annular space C is in direct com- 
 munication with the air-blast pressure, so that whenever the needle 
 
 I 
 
 i I 
 
 9\ 
 
 No. 26.— Fuel Inlet Valve and Pulveriser. 
 
 valve lifts, the air pressure forces the oil accumulated in the space C 
 into the cylinder in the form of a spray. Ignition b)- the hot air 
 follows, and the resultant expansion of the gases generate force 
 down the piston, and constitute the working or power stroke of 
 the cycle. 
 
 Fuel Inlet Valve and Cam. — As will be seen from the illustration, 
 when the nose of the cam comes in contact with the valve lever 
 
Internal Combusiion Engines 
 
 62 
 
 the latter is forced outweirds, and the valve is opened against the 
 pressure of a spring which normally keeps the valve tight in its seat. 
 The starting handle when horizontal causes the starting valve lever 
 to come in contact with the nose of its cam as the cam shaft 
 rotates, while the fuel-valve lever is held clear of its cam at the same 
 time. With the starting handle in the vertical position the starting 
 \alve lever is clear of its cam while the fuel-valve lever then comes 
 into operation. The actual opening allowed the fuel valve is very 
 small, as the limited opening area increases the spraying action of 
 the oil injection. The air admission valve, exhaust valve, and starting 
 valve all open downwards or into the cylinder but the fuel valve 
 opens upwards or out of the cylinder, as shown by the various 
 sketches. 
 
 thus 
 
 No. 27.— Air Inlet Valve, Lever, and Cam. 
 In the four-cycle type the cylinder cover contains four valves, 
 
 Air Inlet Valve. 
 
 Fuel Valve. 
 
 Exhaust Valve. 
 
 Starting Valve (air blast). 
 
 In the two-cycle type "scavenge valves," one or two in number, 
 take the place of the air inlet valve and act similarly, with the 
 difference that the air is in this case under pressure when admitted 
 to the cylinder, and is intended to "scavenge" the cylinder of the 
 exhaust gases before compression of the pure air. 
 
624 "Verbal" Notes and Sketches 
 
 DIESEL ENGINE NOTES AND SKETCHES. 
 Action of 4-Stroke Diesel Engine. 
 
 1. Down-Stroke. — AtmospbcMJc air at engine-room temperature is 
 
 drawn into the cylinder through the suction silencer. Air 
 admission valve open. 
 
 2. Up- Stroke. — The air is compressed to about 500 lbs. |)ressure 
 
 and somewhere about 1200° Temp. Fahr. All valves shut. 
 
 3. Down-Stroke. — Just about the top centre the fuel valve is opened 
 
 by the cam and lever gear, and crude oil is blown in through 
 a sprayer on the end of this needle valve by means of the 
 injection air blast of about 750 lbs. pressure. The oil then 
 ignites, combustion takes place, and the expansion of the gases 
 formed force down the piston. The fuel valve remains open 
 for about yV of the stroke. This is the power or impulse 
 stroke of the cycle. 
 
 4. Up-Stroke. — The dead gases of combustion are forced out of the 
 
 cylinder through a water-cooled silencer to the atmosphere. 
 Exhaust valve open. 
 
 Action of 2-Stroke Diesel Engine. 
 
 •I. Down-Stroke, — (A) With the cylinder full of compressed air at 
 about 500 lbs. and 1 200° Temp, (as in the case of the second 
 stroke of the 4-cycle type), the oil is blown in as before 
 described, ignites, and combustion takes place, the expansion 
 of the gases driving the piston down. 
 
 (B) At about |-stroke the piston uncovers the exhaust belt port 
 openings, and the dead gases begin to pass away to the 
 atmosphere. 
 
 (C) x'\t about I'^-stroke the two small scavenge valves on the 
 cylinder cover are opened by their cam levers, and low pressure 
 air of about 6 lbs. pressure is blown into the cylinder, clearing 
 out the remainder of the dead gases, and at the same time filling 
 up the cylinder with pure air in readiness for the next com- 
 pression stroke. 
 
 2. Up-Stroke. — The air admitted by the scavenge valves is com- 
 pressed to about 500 lbs. and 1200° Temp. 
 
 It will be seen that in the 2-stroke cycle, three operations are 
 effected on the down-stroke, which in the 4-stroke tyj)e require three 
 separate strokes to perform. Again, in the 4-stroke cycle, the atmos- 
 pheric air is merely drawn into the c)'linder, whereas in the 2-stroke 
 cycle the air h forced in under pressure, the process only occup}'ing 
 a fraction of the stroke travel. 
 
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No. 28.— Plan of 4-Cycle Diesel Oil Engine Cylinder. 
 
 1. Air inlet valve. 
 
 2. Fuel valve. 
 
 3. Exhaust valve, 
 
 4. Starting valve. 
 
 5. Suction air silencer. 
 
 6. Exhaust pipe to silencer. 
 
 7. Fuel oil tank. 
 
 8. Fuel oil pump. 
 
 9. Fuel oil pipe to fuel valve. 
 
 npressor. 
 
 10. 3-Stage 
 
 11. After cooler. 
 
 12. High pressure a 
 
 13. High pressure a 
 
 (800 lbs. ED ..1 
 
 14. Lower pressure 
 
 {500 lbs. 0). 
 
 15. Starting air pipe to valve. 
 
 16. High pressure blast air pipe to fuel valve. 
 
 delivery to high pressure bottle, 
 bottle for fuel injection purposes 
 
 bottle for starting purposes 
 
 yj'o fa<€ pa^e 624. 
 
Internal rombustlon Eneines 
 
 625 
 
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Intornal Combustion KiiQ-ines 
 
 625 
 
 
 
 
 
 
 
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626 
 
 "Verbal" Notes and Sketches 
 
 No. 30. — Section through Cylinder of 2-Cycle Diesel Engine. 
 
 1, Fuel valve seat (water jacketed). 
 
 2, Scavenge valve seats (two). 
 
 3, Exhaust ports leading to exhaust belt 
 
 4, Exhaust belt. 
 
 5, Exhaust to silencer. 
 
 6, Water circulation of jacket. 
 
Internal Combustion Engines 627 
 
 Coolingf Circulation. — The cylinders, valves in the cover, and the 
 compressors arc all water jacketed. The pistons arc usually cast 
 hollow, and either oil or water cooling is provided for by means of 
 telescof^e piping (see sketch No. 45). 
 
 Lubrication. — Forced lubrication is employed, a pressure of about 
 10 lbs. at the pump giving 4 or 5 lbs. in the bearings. 
 
 Starting. — Having first pumped up the fuel valve by hand and 
 opened ui) the injection blast air bottle connection to the cylinder, 
 starting is effected by placing the starting lever or wheel in position 
 for the starting valve cam, the fuel valve lever being then out of 
 acting position. The valve on the starting air bottle is next opened 
 and the engine begins to move round under compressed air conditions, 
 the pressure being somewhere about 450 lbs. or higher. After a few 
 revolutions, the starting wheel is moved round so that the starting 
 air valve cam, as shown by the index pointer, is cut out and the fuel 
 valve cam slipped into gear position for fuel admission ; the engine 
 then continues running on fuel which should be admitted by degrees 
 in quantity to avoid rapid heating up of the c)'linder. 
 
 Reversing". — The cam shaft is usually supplied with a double 
 set of cams for each fuel, air, starting, and exhaust valve, one set 
 for ahead running, and the other set for astern running. After 
 stopping, the valve levers resting on the cams are all lifted clear 
 (either by hand or by suitable gear) and the shaft is moved along 
 laterally until the astern cams are in line with the levers, which are 
 then lowered again into working contact position. 
 
 Air is next admitted to the starting valve, and the engine begins 
 to revolve on compressed air exactly as in starting ; the air is then 
 cut out and the fuel admitted. 
 
 The operation of stopping and reversing may be described as 
 follows : — 
 
 1. Stop engines by shutting off fuel supply by hand j 
 
 control lever. I These movements 
 
 2. Lift valve levers off cams. are, in most 
 
 3. Throw out ahead cams and put in astern cams ^ cases, carried out 
 
 by moving cam shaft laterally. i automatically by 
 
 4. Give starting air. ^ I the reversing 
 
 5. Cut out starting air and give fuel gradually to | wheel gear. 
 
 avoid rapid heating up. 
 
 Power Control. — If required, certain of the cylinders can be 
 run on air and the remainder on fuel, and in some cases the gear 
 is also arranged to allow of the cutting out altogether of some of 
 the cylinders, which admits of running under reduced power conditions. 
 
 Tests. — Pet cocks are fitted on the fuel valve, fuel pump, and other 
 connections to allow of testing previous to starting up, for pressure 
 and atomisation of the oil spray, etc., all of which tests should always 
 be most carefully carried out beforehand. 
 
 The air blast emplo)'ed should always be kept as low as possible, 
 consistent with the power required. The correctness of the firing in 
 each cylinder can be tested by opening the indicator cock. 
 
628 
 
 " Verbal " Notes and Sketches 
 
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Internal Combustion Engines 
 
 629 
 
 Wear of Valves. — The exhaust valves usually show signs of 
 wear first, as the intense heat of the gases produce pitting on the 
 faces. As leak}' valves mean loss of compression, and therefore 
 reduced power, these valves require regular o\erhaul and attention. 
 The fuel valve also tends to wear away at the spra\-er end, and 
 therefore requires to be examined and ground in at regular intervals, 
 as any difference in setting due to pitting, etc., ma}' seriousl}' upset 
 the timing of the oil injection, and throw the c}iinder out of j^ower 
 balance with the other c}-linders of the engine. Premature ignition 
 ma}' also take place. If dirt enters with the fuel oil, choking up of 
 the pulveriser may also happen, resulting in falling off of power. 
 
 Fuel Valve Lift. — The lift of this valve seldom exceeds ^V in., 
 and the period that the valve remains open is usual!}- about yV of the 
 down stroke. Assuming the re\olutions to be, say, 120 p.m., then in 
 one minute the strokes= 120 x 2 = 240. So that time per stroke = 
 
 i- 
 
 J 10 — 4 sec. Time fuel valve remams open = i X jV = jV sec. 
 
 Smoke. — Heav}- smoke and deposit of carbon is due to one of 
 the following causes : — 
 
 1. Weak compression. 
 
 2. Fuel oil not atomising properl}'. 
 
 3. Excessive fuel supply. 
 
 4. Excessive piston lubrication. 
 
 ■HJ'.DeUvery 
 III tP^^HP Suction 
 
 -Suction, SiUncer 
 
 No. 34. No. 35. 
 
 Compressor Arrangements.* 
 
 No. 36. 
 
 No. 34. — 3-stage compressor driven from crosshcad by levers. 
 
 No. 35. — 3-stage compressor, L.P. and LP., driven from one rod, and H.P. 
 
 driven by lever from I.]\ and L, P. The whole worked by means 
 
 of links and crank from main sliaft. 
 No. 3^). — 3-stage compressor driven by crank on main shaft. 
 
 * Reprinted by kind permission from the \\feLhanicaI World. 
 
630 
 
 "Verbal" Notes and Sketches 
 
 No. 37.*— Two Stage 
 Compressor. 
 
 Driven from shaft by crank 
 and fitted with water circula- 
 tion jacket. 
 
 No. 38.*— Compressor 
 Delivery Valve. 
 
 After compression the 
 hot air passes to an 
 intercooler which is pro- 
 vided with water circula- 
 tion, and is reduced in 
 temperature before 
 entering on the next 
 stage of compression. 
 
 No. 39.— 2-Stroke Diesel Engine Diagram. 
 
 M.E.P.=:9S-6 lbs. per square inch. 
 Notice that in this case the pressure of com- 
 pression is 590 lbs. per square inch, also that no further 
 increase of pressure takes place after ignition. 
 
 * Reprinted by kind permission from the Mechanical World. 
 
Internal Combustion Enerines 
 
 631 
 
 No. 40. — Diagrams from 3-Stage Compressor. 
 (With pressures.) 
 
 L.P. compressor, M.E.P. = 13-2 lbs. per square inch. 
 
 I. H. P. =6-8. 
 LP. compressor, M.E.P. =80 lbs. ,, „ 
 
 I.H.P. = 10.2. 
 H.P. compressor, M.E.P. = 345 lbs. ,, „ 
 
 I.H.P. =96. 
 
632 
 
 " Verbal " Notes and Sketches 
 
 \-ll6. 
 
 KL^ 
 
 No. 41 —Diagrams from Scavenge Pump Cylinders; 
 (2) of 2-Stroke Diesel Engine. 
 
 Observe that the scavenge pump suction pressure is i lb. below 
 atmosphere, and the delivery pressure 9 or 10 lbs. gauge, which falls 
 to about 6 or 7 lbs. on entering the cylinder through the scavenge 
 
 valves. 
 
 Average M.E.P. =6-8 lbs. 
 I.H.P =205. 
 
 Consumption of Fuel. — The consumption of fuel per B.H.P. per 
 hour ranges from "4 to '5 of a lb. 
 
 Heat Efficiency. — Taking the oil consumption per B.H.P. as, say, 
 •45 of a lb. per hour, and the heat value of 19000 B.T.U., then the 
 efficiency works out as under : — 
 
 B.H.P. =r-85 of I.H.P. (average). 
 
 Then, .85 X -45 = -382 lbs. oil per I.H.P. per hour. 
 
 Efficiency (on I.H.P. basis) = ^^'^^^^ ^^g = -347, or 34-7 per cent. 
 
 The efficiency sometimes reaches the high value of ^6 per cent., 
 and even more, in cases of land installations. 
 
 The compressors usually absorb about 10 per cent, of the power 
 developed. 
 
k 
 
 No. 44— Exhaust Valve. 
 
 Fuel Valve. 
 
 1. Air « 
 per 
 
 2. Fuel 
 
 3. Air a 
 by 
 
 4. Admi,' 
 
 5. Air b 
 inci 
 
 6 (left « 
 
 6 ^ri h'^''^* ^'""^ ^"^' ^"'"^' ' ' ^°'^ *^^° ^° '^°° ^^^- Pressure 0). 
 '"^ * nlet from high pressure air bottle. :,' ' bore 
 fror , 
 
 - . assag-e of valve. « 
 
 7. Air a» ' 
 
 8. Exha,^^^^^^ **^ ^^'^^• 
 
 9. Exhai 
 
 10. Wate»ve. 
 
 11. Upper 
 
 12. Lowei for actuating the valve 
 
 13. Wate.^„ 
 
 14. Crossl 
 
 15. Lever 
 
 Of 4-S 
 
 [To faa p(K;c 632. 
 
 of each piston a ring i.s pmncd on to wipe tne lUDricaiint,^ on 01, me 
 cylmder walls. This oil is collected in a circular tray to prevent it 
 from mixing with the engine lubricating oil, and it is claimed that 
 . when filtered 60 per cent, of the original amount supijlied may be 
 recovered for use over again. 
 
No. 43. Fuel Valve. 
 
 No. 42. Working DJagram of 4-8troke Marine Type Diesel Oil Engir 
 
o; 
 
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 sction 
 ^ is of 
 
 the usual shallow tA.f)e, v^nth nine rings, and is supported in the centre 
 on the dished-out piston rod. The pistons are cx)oled by salt w-aler, 
 supplied through telescoping pipes kept tight by metallic packing, as 
 with pistons of this large size the subsequent cooling of the oil 
 required by oil cooling of the pistons is too difficulL On the bottom 
 of eiich piston a ring is pinned on to v»"ipe the lubricating oil off the 
 cj-linder walls. This oil is collected in a circular tray to prevent it 
 from mixing with the engine lubricating oil, and it is claimed that 
 when filtered 6o per cenL of the original amount supplied may be 
 recovered for use over again. 
 
_ jbower 
 
 developed. 
 
^33 
 
 d the 
 box- 
 
 i "g to 
 
 n the 
 )f the 
 
 '^ ' d are 
 
 () the 
 ^roLip 
 ns at 
 3t are 
 !, the 
 cross- 
 ■ By 
 -tight 
 rank- 
 ly for 
 , and 
 igine, 
 irgest 
 igs. 
 three 
 The 
 keeps 
 nsion 
 :ed of 
 ighies 
 
 n one 
 Tiade, 
 ; ends 
 carry 
 -plate 
 jre of 
 ;ction 
 
 _ . _ . is of 
 
 the usual shallow type, with nine rings, and is supported in the centre 
 on the dished-out piston rod. The pistons are cooled by salt water, 
 supplied through telescoping pipes kept tight by metallic packing, as 
 with pistons of this large size the subsequent cooling of the oil 
 required by oil cooling of the pistons is too difficult. On the bottom 
 of each piston a ring is pinned on to wipe the lubricating oil off the 
 cylinder walls. This oil is collected in a circular tray to prevent it 
 from mixing with the engine lubricating oil, and it is claimed that 
 when filtered 60 per cent, of the original amount supplied may be 
 recovered for use over a<iain. 
 
 I 
 
No. 45. Four-Cycle Diesel Marine Oil Engine. 
 
 Motor-Ship "Fionia." 
 Constructed by Messrs Burmeister and Wain, Copenhagen. 
 
 * Reprinted from Engineering. 
 
 To fare pate 633. 
 
Internal Combustion Engines 633 
 
 THE MOTOR SHIP "FIONIA." 
 
 General Description of Engines. 
 
 The six cylinders are arrani^cd in two sets of three, and the 
 cast-iron bed-plate is in two interchangeable pieces, with deep box- 
 girders unsupported in the centre, an arrangement justified owing U) 
 the through bolt system of construction adopted. The sump for the 
 lubricating oil is formed by welded-stcel plates. The design of the 
 crankcase and the means adopted for carr)ing the piston load are 
 departures from earlier engines, and give greater accessibih'ty to the 
 working parts. Between the cylinders, and at the ends of each group 
 of three cylinders, there is an A frame formed by box columns at 
 the front and at the back, to the tops of which the cyHnder feet are 
 bolted. At the front of the engine, between these columns, the 
 crosshead guides are bolted, and for stiffening purposes box cross- 
 girders connect the tops of the columns at the back of the engine. By 
 this means the back of the engine is enclosed by sheet-iron oil-tight 
 doors, and at the front sheet-iron oil-tight doors encase the crank- 
 chamber beneath the guides. This gives excellent accessibility for 
 the adjustment and examination of the top end, bottom end, and 
 main bearings. The guides are arranged in the front of the engine, 
 so that the working stroke-guide thrust may be taken in the largest 
 guide area. Forced lubrication is adopted to all the main bearings. 
 
 The crank-shaft is built up in two interchangeable pieces, of three 
 throws, and is drilled out for the forced lubrication system. The 
 connecting rod is of the usual marine design, and the absence of keeps 
 for both the top and bottom ends will be noted. The only tension 
 load to betaken is that due to inertia, which, with a normal speed of 
 rev(jlution of 100, and the light piston made possible with engines 
 of the four-c\-cle type, must be very small. 
 
 The cylinder jackets for each set of three c\'linders are cast in one 
 piece provided with feet, to which reference has already been made, 
 for bolting to the A frames. Between the cylinders, and at the ends 
 of each group, the cylinder jacket casting is swelled out to carry 
 through bolts from the cylinder tops to the bottom of the bed-plate 
 underneath the main bearings, so relieving all the engine structure of 
 tension stresses. This jacket casting is provided with inspection 
 doors, and liners are pressed in for each cylinder. Each piston is of 
 the usual shallow type, with nine rings, and is supported in the centre 
 on the dished-out piston rod. The pistons are cooled by salt water, 
 supplied through telescoping pipes kept tight by metallic packing, as 
 with pistons of this large size the subsequent cooling of the oil 
 required by oil cooling of the pistons is too difficult. On the bottom 
 of each piston a ring is pinned on to wipe the lubricating oil off the 
 cyHnder walls. This oil is collected in a circular tray to prevent it 
 from mixing with the engine lubricating oil, and it is claimed that 
 when filtered 60 per cent, of the original amount supplied may be 
 recovered for use over again. 
 
H 
 
 SSSBR??''^'^' 
 
 c.v. Jjower 
 
 developed. 
 
Internal Combustion Engines 633 
 
 THE MOTOR SHIP "FIONIA." 
 
 General Description of Engines. 
 
 The six cylinders are arranged in two sets of three, and the 
 cast-iron bed-plate is in two interchangeable pieces, with deep box- 
 girders unsupported in the centre, an arrangement justified owing to 
 the through bolt system of construction adopted. The sump for the 
 lubricating oil is formed by welded-steel plates. The design of tiie 
 crankcase and the means adopted for carr)ing the piston load are 
 departures from earlier engines, and give greater accessibility to the 
 working j:)arts. Between the cylinders, and at the ends of each group 
 of three cyhnders, there is an A frame formed by box columns at 
 the front and at the back, to the tops of which the cylinder feet are 
 bolted. At the front of the engine, between these columns, the 
 crosshead guides are bolted, and for stiffening purposes box cross- 
 girders connect the to[)s of the columns at the back of the engine. By 
 this means the back of the engine is enclosed by sheet-iron oil-tigiit 
 doors, and at the front sheet-iron oil-tight doors encase the crank- 
 chamber beneath the guides. This gives excellent accessibility for 
 the adjustment and examination of the top end, bottom end, and 
 main bearings. The guides are arranged in the front of the engine, 
 so that the working stroke-guide thrust may be taken in the largest 
 guide area. Forced lubrication is adopted to all the main bearings. 
 
 The crank-shaft is built up in two interchangeable pieces, of three 
 throws, and is drilled out for the forced lubrication system. The 
 connecting rod is of the usual marine design, and the absence of keeps 
 for both the top and bottom ends will be noted. The only tension 
 load to be .taken is that due to inertia, which, with a normal speed (jf 
 rev<jlution of 100, and the light piston made possible with engines 
 of the four-cycle type, must be very small. 
 
 The cylinder jackets for each set of three cylinders are cast in one 
 piece provided with feet, to which reference has already been made, 
 for bolting to the A frames. Between the cylinders, and at the ends 
 of each group, the cylinder jacket casting is swelled out to carry 
 through bolts from the cylinder tops to the bottom of the bed-plate 
 underneath the main bearings, so relieving all the engine structure of 
 tension stresses. This jacket casting is provided with inspection 
 doors, and liners are pressed in for each cylinder. Each piston is of 
 the usual shallow type, with nine rings, and is supported in the centre 
 on the dished-out piston rod. The pistons are cooled by salt water, 
 su[)plied through telescoping pipes kept tight by metallic packing, as 
 with pistons of this large size the subsequent cooling of the oil 
 required by oil cooling of the pistons is too difficult. On the botUnn 
 of each piston a ring is pinned on to wipe the lubricating oil off the 
 cylinder walls. This oil is collected in a circular tray to prevent it 
 from mixing with the engine lubricating oil, and it is claimed that 
 when filtered 60 per cent, of the original amount supplied may be 
 recovered for use over aaain. 
 
634 " Verbal " Notes and Sketches 
 
 In each cylinder-head, which is a separate casting, are the usual 
 valves — the inlet, exhaust, fuel injection, and starting air-valves — 
 operated by cams, push-rods, and levers. The camshaft is not 
 driven, as in former engines by the same firm, by spur-gearing and 
 connecting-rods, but by large spur-wheels, to give a more rigid 
 connection between the crankshaft and the camshaft. Longitudinal 
 movement of the camshaft to bring the ahead or astern cams under 
 the various push- rods, and rotation of the manoeuvring shaft to lift 
 and replace the rollers upon their cams, are effected by a compressed 
 air servo-motor of a similar type to Brown's reversing gear. The 
 starting of the engine is by compressed air at a pressure of 360 lbs. per 
 sq. in. 
 
 Separate fuel injection pumps are now provided for each cylinder, 
 and these are driven by levers and links from one of the intermediate 
 shafts driving the camshaft. The control of the engine is substantially 
 the same as in previous ships. 
 
 Reavell compressors for fuel injection and starting air are driven 
 from the forward end of the main engine crankshaft. 
 
 Starting air is taken from the two main-engine compressors at 
 about 360 lbs. per sq. in., and is stored in two reservoirs, each of 
 800 cub. ft. cubic capacity. When manoeuvring a Reavell auxiliary 
 compressor driven by an electric motor of 200 brake horse-power 
 is used, and when at sea this compressor serves as a stand-by for 
 either of the main engine compressors, being of the same size. Fuel- 
 injection air at about 850 lb. per sq. in. is stored in bottles placed 
 in the centre of the engine room platform. 
 
 The auxiliary machinery, all of which is electrically driven, 
 consists of two rotary cooling water pumps, two rotary lubricating 
 oil pumps, and two sets of plunger bilge, sanitary, and piston-cooling 
 pumps. The plunger piston-cooling water pump draws the water 
 from the pistons and delivers it overboard. The water is forced to 
 the pistons by the main cooling water pumps. These pumps are all 
 in duplicate, one of each type serving as a stand-by. The remaining 
 engine-room auxiliaries are : — One rotary ballast pump, a donkey 
 pump, fresh water and fuel-oil pumps, and a refrigerating machine. 
 For supplying electric current to these auxiliaries when the vessel is 
 at sea, and to drive the twelve electric 3-ton to 5-ton winches when in 
 port, two four-cylinder four-cycle oil-engines are provided. Each of 
 these engines is sufficient for the work, and develops 200 brake hor.se- 
 power at a normal speed of 225 revolutions per minute, and both are 
 of Messrs. Burmeister and Wain's usual design, being in every way 
 self-contained and provided with their own compressors, air-storage, 
 etc. The dynamos work at 220 volts, and for lighting the voltage 
 is transformed to 1 10 volts. To light the ship when in port, and when 
 the winches are not working, a small crude-oil engine and dynamo 
 set is provided, and by this engine a compressor for bottle-charging 
 can also be worked. In the engine room there are two daily service 
 fuel-oil tanks, each of sufficient capacity for twelve hours' running. 
 
lever i^ ny inc pin v, as snown, so mat oy rotating tne snart u^ the arc de- 
 scribed by the pin F is disi)laccd, and so varies the time of opening given to 
 the valve. 
 
 In starting up the engine with compressed air the valve gear is first set 
 in the desired position by rotating the lay shaft A with regard to the vertical 
 shaft W, by which it is driven from the crank shaft. This operation is con- 
 
No. 46.*~Two-Cycle Marine Diesel Engine. 
 
 Revs. 170. 4 Cylinders. H.P. 500. 
 Constructed by Mr Franco Tosi, Legnano. 
 
 Index to Parts. 
 
 A. Lay or half time shaft from which the fuel valve is operated by an eccentric. 
 W, Vertical shaft which by gear wheels from main shaft actuates the lay shaft 
 W overhead. 
 
 E, Lever on eccentric for operating fuel valve. 
 R, Roller for connecting to bell crank lever L,. 
 
 L,. Bell crank which engages with fuel valve spindle to lift same. 
 G, Link fixed to eccentric of shaft O,. and which connects to lever E by 
 pin F. 
 
 F, Pio on link G which is displaced in position when shaft O^^^ is rotated a 
 
 given amount : by this means the time of opening of the fuel valve 
 can be varied. 
 ,, L_., Levers for operating scavenge valves. 
 Cl- Cams for scavenge valve levers L, L^. 
 L;. Lever for workiag starting valve in ahead running. 
 
 Reversing shaft by rotating v 
 
 into gear as required. 
 Fuel pump driven by eccentric 
 
 rhich, either ahead or astern 
 
 I lay shaft A. 
 
 Lj, Lever for working starting valve i 
 Cad. Cam 
 
 V,V., 
 X,X, 
 
 . astern running. 
 
 Hand adjustment lever for fuel valves. 
 
 Reversing lever for working the air servomotor which, in turn, operates 
 
 the vertical shaft, and through it the lay shaft. 
 Servo motor which, when set in action by the reversing lever H, raises 
 
 or lowers the vertical shaft W. and cants over the lay shaft to the 
 
 required position (or the valve cam positions. 
 Hand gear for use in emergency if the servo-motor gives out. 
 Air supply valves to starting valves. 
 Cams for opening or closing valves V|V_,. 
 Reversing discs for operating reversing cam shafts 0,0- 
 Intermediate shaft for distributing lever M. 
 Distributing lever for all valves, and which automically unlocks when the 
 
 cams come mto the correct running position either ahead or astern. 
 
 Reprinted from Engineering^. 
 
Internal Combustion Engines 
 
 'JD 
 
 General Description of Two-Cycle Diesel Engine (No. 46). 
 
 The three-stage air compressor, situated above the scavenging pump, has 
 iwo cylinders, and is driven from the rod of the scavenging i)ump. The air 
 is first compressed below the lower cylinder in the chamber shown, and 
 thence passes successively to the upper end of this cylinder and to the high 
 pressure cylinder. The pump is water-jacketed, and between the stages the 
 air is passed through a cooler of ample cai)acity, and thus the increase in 
 temperature at each successive compression stroke is limited. 'Jliis precludes 
 the possibility of temperature being reached sufficient to lead to the ignition 
 of the cylinder lubricating oil which the air may carry away with it. 
 
 The engine is provided with a separate fuel pump for each cylinder, 
 these pumps, P^, and I\„ being mounted in pairs, and driven by eccentrics 
 from the lay shaft A. The control of the fuel supply is carried out in the 
 usual manner, the suction valve being held off their seats during the required 
 portion of the delivery stroke by means of the gear shown. The fuel supply 
 is automatically controlled by the governor, and provision for hand adjust- 
 ment is also given by the lever !>,; ; a separate adjustment, worked in con- 
 nection with the starting gear, is also provided, and will be dealt with more 
 fully later, in connection with the description of the distribution arrangements. 
 Either of the four pumps can be put out of action, as desired, by raising 
 the spindle at the bottom of the pump casting. The spindle in its raised 
 position prevents the closing of the suction valve, and thus prevents the 
 delivery of fuel to the cylinder corresponding to the pump affected. 
 
 The lubricating and water-circulating pumps, which are of the ordinary 
 piston type, are driven from the beam of one of the scavenging pumps, while a 
 separate pump, driven in the same manner, is used for raising the oil fuel from 
 the storage tanks to a fuel tank placed at a suitable height above the engine. 
 
 As will be seen, the valves are placed in the cylinder covers, the four 
 scavenging valves and starting valves being operated in the usual manner, by 
 simple cam and lever gear. The fuel valve, which is placed in the centre 
 of each cover, however, has a separate gear, since it is considered preferable 
 to provide it with adjustment entirely independent of the other valves. 
 .Although a common drive for all valves may appear more simple, it renders 
 the adjustment of the mechanism a more difficult matter, and on account of 
 the general interconnection, makes it practically impossible to adjust any 
 one valve without affecting the operation of the others. The scavenging 
 valves are operated in pairs by means of the levers L and L^, from the cams 
 Cl. Each starting valve is provided with two sets of driving gear, the lever 
 L3 and cam Cav being brought into operation for running ahead, whilst the 
 lever L^ and cam C.^o are used for going astern. The levers L3 and L^ are 
 mounted on eccentrics keyed to the shaft O,, in such relation that by the 
 suitable rotation of this shaft either set of gear comes into operation. The 
 fuel-valve is operated from an eccentric on the lay shaft A by means of the 
 lever E, which carries a roller R; this roller engages with the lower end of the 
 bell-crank lever hr^, the other end of which engages with the valve spindle. A 
 link C, which is mounted on an eccentric on the shaft Oo, is connected to the 
 lever E by the pin F, as shown, so that by rotating the shaft O^ the arc de- 
 scribed by the pin F is displaced, and so varies the time of opening given to 
 the valve. 
 
 In starting up the engine with compressed air the valve gear is first set 
 in the desired position by rotating the lay shaft A with regard to the vertical 
 shaft W, by which it is driven from the crank shaft. This operation is con- 
 
y 
 
 moouj 
 
 P /v., . ■ 
 
 is transformed to i lo volts. To light the ship when m port, and when 
 the winches are not working, a small crude-oil engine and dynamo 
 set is provided, and by this engine a compressor for bottle-charging 
 can also be worked. In the engine room there are two daily service 
 fuel-oil tanks, each of sufficient capacity for twelve hours' running. 
 
Internal Combustion Enorines 
 
 'JO 
 
 General Description of Two-Cycle Diesel Engine (No. 46). 
 
 The three-slage air compressor, situated above the scavenging pump, has 
 iwo cylinders, and is driven from the rod of the scavenging pump. The air 
 is first compressed below the lower cylinder in the chamber shown, and 
 thence passes successively to the upper end of this cylinder and to the high 
 pressure cylinder. The pump is water-jacketed, and between the stages the 
 air is passed through a cooler of ample capacity, and thus the increase in 
 temperature at each successive compression stroke is limited. This precludes 
 the possibility of temperature being reached sufficient to lead to the ignition 
 of the cylinder lubricating oil which the air may carry away with it. 
 
 The engine is provided with a separate fuel pump for each cylinder, 
 these pumps, P^., and P,,, being mounted in pairs, and driven by eccentrics 
 from the lay shaft A. The control of the fuel supply is carried out in the 
 usual manner, the suction valve being held off their seats during the required 
 portion of the delivery stroke by means of the gear shown. The fuel supi)ly 
 is automatically controlled by the governor, and provision for hand adjust- 
 ment is also given by the lever L,. ; a separate adjustment, worked in con- 
 nection with the starting gear, is also provided, and will be dealt with more 
 fully later, in connection with the description of the distribution arrangements. 
 Either of the four pumps can be put out of action, as desired, by raising 
 the spindle at the bottom of the pump casting. The spindle in its raised 
 position prevents the closing of the suction valve, and thus prevents the 
 delivery of fuel to the cylinder corresponding to the pump affected. 
 
 The lubricating and water-circulating pumps, which are of the ordinary 
 piston type, are driven from the beam of one of the scavenging pumps, while a 
 separate pump, driven in the same manner, is used for raising tlie oil fuel from 
 the storage tanks to a fuel tank placed at a suitable height above the engine. 
 
 As will be seen, the valves are placed in the cylinder covers, the four 
 scavenging valves and starting valves being operated in the usual manner, by 
 simple cam and lever gear. The fuel valve, which is placed in the centre 
 of each cover, however, has a separate gear, since it is considered preferable 
 to provide it with adjustment entirely independent of the other valves. 
 .Although a common drive for all valves may appear more simple, it renders 
 the adjustment of the mechanism a more difficult matter, and on account of 
 the general interconnection, makes it practically impossible to adjust any 
 one valve without affecting the operation of the others. The scavenging 
 valves are operated in pairs by means of the levers L and L^, from the cams 
 Cl. Each starting valve is provided with two sets of driving gear, the lever 
 L3 and cam Cav being brought into operation for running ahead, whilst the 
 lever L^ and cam C.^d are used for going astern. The levers L3 and L^ are 
 mounted on eccentrics keyed to the shaft O,, in such relation that by the 
 suitable rotation of this shaft either set of gear comes into operation. The 
 fuel-valve is operated from an eccentric on the lay shaft A by means of the 
 lever E, which carries a roller R; this roller engages with the lower end of the 
 bell-crank lever L.^, the other end of which engages with the valve spindle. A 
 link C, which is mounted on an eccentric on the shaft Oo, is connected to the 
 lever E by the pin F, as shown, so that by rotating the shaft O^ the arc de- 
 scribed by the pin F is displaced, and so varies the time of opening given to 
 the valve. 
 
 In starting up the engine with compressed air the valve gear is first set 
 in the desired position by rotating the lay shaft A with regard to the vertical 
 shaft W, by which it is driven from the crank shaft. This operation is con- 
 
636 "Verbal" Notes and Sketches 
 
 trolled by the reversing lever H, which actuates an air servo-motor S, which 
 in turn raises or lowers a sliding portion of the vertical shaft according to 
 the direction in which the lever is moved. The lay shaft A being driven by 
 helical gearing, this vertical movement of the shaft w results in a relative 
 motion of the two shafts, and since the vertical shaft is prevented from 
 rotating by the main shaft, the lay shaft itself is turned and places the valve 
 gear in the desired position. The vertical shaft runs in a thrust bearing of 
 ample proportions, and it is claimed that the method adopted of raising the 
 shaft in place of using the more general system of a sliding gear wheel results 
 in considerable reduction of wear. An alternative hand gear, controlled by 
 -the hand wheel K, is provided for this setting operating, which is available 
 in the event of the servomotor being out of operation. The movement of 
 the lever H also disengages a locking device, which prevents the accidental 
 movement of the vertical shaft whilst the engine is running ; this, however, 
 would appear to be a remote contingency, since the action of the driving 
 gear tends to maintain the shaft automatically in the desired position. 
 
 A further function of the reversing lever is the operating of a valve, 
 placed in the supply pipe to the servo-motor, which it opens immediately 
 before the distributing valve comes into action, and closes towards the end 
 of the reversing operation. Thus the air supply is entirely cut off from the 
 motor except during the time the latter is actually in use. 
 
 As soon as the desired adjustment of the lay shaft is completed the 
 distribution lever M is automatically unlocked ; this lever, which is mounted 
 on the shaft N, operates the reversing shafts Oj and O.^ by means of the 
 reversing discs on the shaft N and the gears Xj and X^. The discs, however, 
 are so arranged that the motion of the shaft N may be either transmitted to 
 one or both of the shafts O. 
 
 The movements effected in starting the engine in the ahead direction are 
 as follow : — 
 
 .1. The air supply valves Vj and Vg are opened by means of the cams Kj 
 and Ko, thus admitting air to the starting valves. 
 
 2. The starting valves, operated by the cams Cav and the lever Lg, then 
 admit air to the cylinders, and since at least one of the valves will be open, 
 whatever the point of the crank shaft, and the valves remain open during 
 crank movement of 120°, the engine starts running. 
 
 3. The starting valves on cylinders I. and II. are then put out of action 
 and the air valve V^, automatically closed, thus preventing any leakage of air 
 into the cylinders in the event of the starting-valves being out of repair. The 
 engine is now running on cylinders III. and IV. only, and thus the tjuantity 
 of air used in starting up is reduced to a minimum. 
 
 4. The position of the link G controlling the fuel valve on cylinders I. 
 and II. has now been brought to such a point that the roller R engages with 
 the lever L^, and causes the fuel valve to lift at an angle of advance of 15°, 
 and holds it oi)en during a crank movement of 35°. At the same time a 
 cam on the shaft N operates the gear, closing the suction valves on the fuel 
 pump Per, and thus cylinders I. and II. commence running on the oil-fuel, 
 whilst the other two cylinders continue to work by air. 
 
 5. The air sui)ply can now be cut off from the other two cylinders, and 
 the supply of fuel adjusted by means of the lever L,. to give the desired speed. 
 The engine can contiiiue to run on two cylinders only, and this will be 
 found a great convenience in mancx;uvring and for running at reduced speeds, 
 
 6. The fuel supply can next be admitted to the remaining two cylinders, 
 and the fuel valves adjusted to continue running at the reduced speed. 
 
i Internal Combustion Engines 637 
 
 7. Finally, the valves are adjusted to give the normal speed of the engine 
 by means of the lever already referred to. 
 
 For starting the engine in the reverse direction a similar cycle of move- 
 ments is carried out, with the difference that the reversing lever H and the 
 distributing lever M are both moved in the opposite direction. The correct 
 adjustment of the scavenging valve gear is carried out by the vertical move- 
 ment of the shaft W, and when running in the reverse direction the engine 
 develops the same power as under normal conditions. 
 
 From this description of the starting and reversing of the engine it will 
 be seen that the whole of the operations are controlled by the reversing and 
 distributing levers H and M. These are interlocked, so that it is only possible 
 to move the reversing lever when the other one is in its central or " stop " 
 position, and similarly, the distributing lever can only be operated when the 
 reversing lever is placed completely over into the ahead or astern position. 
 The arrangement therefore enables reversals to be carried out rapidly with 
 a minimum consumption of air, and eliminates the risk of accidents due to 
 the engineer attempting to carry out the movements out of their correct 
 sequence. The centrifugal governor fitted to the engine is adjusted to cut 
 the fuel pumps out of action should the speed rise 15 per cent, above the 
 normal. 
 
 When running at low speeds, as described above, the regulation is 
 effected in such a way that as the speed is reduced the angle of advance 
 and the duration of the fuel-valve opening, measured in relation to the 
 movement of the engine crank, are also decreased, as also is the lift of the 
 valve. Thus, in spite of the fact that the engine is running slower, the actual 
 time that the fuel valve remains open is only slightly increased, and since the 
 lift is decreased, the amount of fuel entering the cylinder is reduced, and 
 ignites gradually without allowing an excessive amount of air to pass. Further, 
 by throttling the exhaust at the silencer a higher pressure can be obtained 
 in the cylinder at the end of the scavenging stroke than occurs under normal 
 conditions, and thus on compression a sufficiently high temperature to 
 produce combustion can be secured, in spite of the increased loss of pressure 
 due to the slower travel of the piston. A further increase in the temperature 
 of the air can be obtained, if necessary, by reducing the amount of circulating 
 water to the scavenging pump. For running at reduced speeds also a lever 
 controlling all the fuel valves causes the oil to enter the cylinders immedi- 
 ately on the lift of the valve and without passing through the atomiser. Thus 
 ignition takes place before any air gains admission, which otherwise might 
 sufficiently reduce the temperature to prevent combustion ensuing. If this 
 lever should not be replaced on resuming normal speed, the only consequence 
 would be imperfect combustion, which would be immediately detected, but 
 the power of the engine would not be affected. 
 
 The small cooled area of the combustion chamber relative to its volume, 
 in addition to its general design assisting in the general diffusion of the fuel 
 throughout the air, result in perfect combustion being attained. The 
 scavenging is also very effective, since the provision of four comparatively 
 large valves and the large ratio of the length of cylinder to the diameter 
 prevent the creation of eddies. 
 
 As explained below, the pistons are made in two parts, and special 
 arrangements are made whereby they can be withdrawn from the cylinders 
 from below without in any way interfering with the valve gear. 
 
 43 
 
638 
 
 "Verbal" Notes and Sketches 
 
 No. 47.*— View of Cylinder Head with Fuel Valve, Starting 
 Valve, Cams, etc. 
 
 A, Lay or half time shaft from which the fuel valve is operated by an 
 eccentric. 
 
 E, Lever on eccentric for operating fuel valve. 
 R, Roller for connecting to bell crank lever L^. 
 
 L^', Bell crank which engages with fuel valve spindle to left same. 
 G, Link fixed to eccentric of shaft Oo, and which connects to lever E by 
 pin F. 
 
 F, Pin on link G which is displaced in position when shaft Oo is rotated 
 
 a given amount, and in this way varies the time of opening of 
 
 the fuel valve. 
 L3, Lever for working starting valve in running ahead. 
 L4, ,, ,, ,, ,, astern. 
 
 OiO.j, Shaft for placing cams in either ahead or astern running positions. 
 
 Reprinted from Engineering. 
 
i 
 
 Internal Combustion Engines 
 
 639 
 
 General Data of Marine Diesel Engines. (1 
 
 ^our C 
 
 ycle Ty 
 
 Revolu- 
 tions per 
 Minute. 
 
 pe.) 
 
 Name of Vessel. 
 
 Total Brake 
 Horse- 
 Povver. 
 
 Number 
 
 of 
 Engines. 
 
 Number of 
 Cylinders 
 per Each 
 Engine. 
 
 Diameter o( 
 Cylinders 
 in Inches. 
 
 Stroke 
 
 in 
 Inches. 
 
 Mean 
 Pressure 
 in Lbs. 
 
 
 
 
 
 Inches. 
 
 Inches. 
 
 
 
 "Fiona" 
 
 3250 
 
 2 
 
 6 
 
 29*1 
 
 43"3 
 
 TOO 
 
 91 
 
 "Selandia" - 
 
 1000 
 
 2 
 
 6 
 
 20-8 
 
 25-6 
 
 140 
 
 53-4 
 
 " Abelia " - 
 
 1200 
 
 ■y 
 
 4 
 
 I7-25 
 
 33 
 
 120 
 
 98 
 
 " Kangaroo " 
 
 2250 
 
 2 
 
 6 
 
 22 
 
 29-9 
 
 140 
 
 93"3 
 
 "Mississippi' 
 
 2900 
 
 2 
 
 6 
 
 2'J'I 
 
 40"5 
 
 ^15 
 
 71 
 
 Petroleum for Diesel Engines 
 
 
 Name. 
 
 Specific Gravity. 
 
 Flash Point. 
 
 B.T.U.'sperLb. 
 
 American (light) - 
 
 ■89 to -91 
 
 240° F. 
 
 19000 
 
 Texas - 
 
 •92 
 
 240° F. 
 
 19000 
 
 Shale (Scotch) 
 
 •85 to -86 
 
 230° F. 
 
 19500 
 
 The oils given in above table are chiefl}' composed of carbon 
 (85 per cent.) and hydrogen (about 14 per cent.), together with a 
 small proportion of oxygen, about i per cent. 
 
 Working Data of Diesel Engine. 
 
 The following data referring to a modern Diesel two-cycle engine 
 gives a good general idea of the various pressures carried in the 
 c)'lindcrs, compressors, scavenge lubrication, and cooling s}'stems, and 
 a careful study of the figures will be found of value to the student. 
 
 Engines. 
 
 No. of Cylinders. 
 
 Diameter of Each. 
 
 Stroke. 
 
 4 
 
 14 in. 
 
 21 in. 
 
640 
 
 Verbal " Notes and Sketches 
 
 Cylinder. 
 
 M.E.P. (Lbs. 0). 
 
 Revolutions. 
 
 i.H.r. 
 
 1 
 Total I.H.P. 
 
 No. I - - 
 
 102 
 
 180 
 
 149 
 
 
 „ 2 - - 
 M 3 - - 
 
 98 
 94 
 
 180 
 180 
 
 144 
 
 138 
 
 "? 576 
 
 „ 4 - - 
 
 99 
 
 180 
 
 M5 
 
 / 
 
 
 Compressor (Three-Stage). 
 
 
 
 M.E.P. (Lbs. 0). 
 
 Revolutions. 
 
 I.H.P. 
 
 I St stage 
 
 - 
 
 14-2 
 
 180 
 
 7-6 
 
 2nd „ 
 
 ■ 
 
 80 
 
 180 
 
 ro'2 
 
 3rd „ 
 
 - 
 
 350 
 
 180 
 
 9-2 
 
 Scavenge. 
 
 
 M.E.P. (Lbs. 0). 
 
 Revolutions. 
 
 LH.P. 
 
 No. I - 
 ,, 2 - 
 
 7'5 
 7-2 
 
 180 
 180 
 
 22 
 21 
 
 Horse-Power of Diesel Engines. 
 
 The power of Diesel engines is usually expressed as brake or 
 shaft horse (B.H.P.), and the consumption is referred to this standard. 
 The B.H.P. is measured eitiier by friction brakes for small power 
 engines or, in large engines, by first testing for the actual friction 
 horse-power, and deducting this from the calculated I.H.r., the 
 difference being equal to the B.H.P. The power required to chive 
 the compressors, and to overcome the friction and weight of the 
 moving parts, can be determined by coupling up the engine to a 
 dynamo of known resistance and efficiency, and this constitutes the 
 " friction horse-power." 
 
 So that, B.H.P. = LH.P. — Friction H.P. 
 
 The friction H.P. varies from about 25 per cent, to 10 per cent, 
 under various speed and power conditions, therefore the B.H.P. varies 
 from 75 per cent, to 90 per cent, of the I.H.P. 
 
Internal Combustion Eno"ines 
 
 641 
 
 Four Stroke Engine. 
 
 Revs. 
 
 LH.P. 
 
 Piston area X Stroke in feet X — z-^ X M.E.P. 
 
 33000 
 
 Two Stroke Engine. 
 
 J TT p _ Piston area X Stroke in feet X Revs. X M.E.P. 
 
 33000 
 
 NOTE— 
 
 In the four-stroke there is one impulse stroke in every four-stroke or 2 revs. 
 ,, two ,, ,, ,, ,, two ,, I rev. 
 
 Forced Lubrication System. 
 
 Pressure of Oil in 
 Lbs. [77] at Pump. 
 
 Oil Inlet Tempera- 
 ture at Cooler. 
 
 Oil Outlet Tempera- 
 ture at Cooler. 
 
 12 
 
 136° 
 
 93° 
 
 Water circulation pressure for jackets = 10 lbs. 
 
 Water circulation outlet temperature from jackets = 134°. 
 
 Pressures and Temperatures of Three-Stage Compressor. 
 
 Number of 
 Stage. 
 
 Suction Air Pressure 
 and Temperature. 
 
 Delivery Air Pressure 
 
 and Temperature 
 
 Before Cooling. 
 
 Delivery Air Pressure 
 
 and Temperature 
 
 After Cooling. 
 
 Gauge 
 Pressure 
 in Lbs. 
 
 Temperature 
 Fahr. 
 
 Gauge 
 Pressure 
 in Lbs. 
 
 Temperature 
 Fahr. 
 
 Gauge 
 Pressure 
 in Lbs. 
 
 Temperature 
 Fahr. 
 
 No. I - 
 
 n 2 - 
 
 ,. 3 - 
 
 
 
 45 
 280 
 
 62° 
 126° 
 128° 
 
 45 
 280 
 900 
 
 175° 
 320' 
 
 165° 
 
 45 
 280 
 900 
 
 126° 
 
 128' 
 104° 
 
 The cooling of the air before being used for oil injection purposes 
 is necessary to prevent pre-ignition taking place in the fuel valve 
 pocket above the sprayer ; for the same reason a high flash point oil 
 is required for Deisel engines. The flash point of the various more 
 or less crude or semi-crude oils in general use ranges from about 
 220° to 280° Fahr. 
 
APPENDIX. 
 
 Marine Steam Turbines.* 
 
 Principle of Turbine. — The steam turbine is a machine designed 
 to convert the kinetic energy of steam into direct rotary motion. 
 The two principal types of turbine are — (i) Impulse Turbines, those 
 arranged with expanding nozzles in which the high velocity of discharge 
 impinges against a series of small buckets secured on the circumference 
 of a large wheel keyed to the driving shaft, the De-Laval turbine being 
 an example of this t)'pe ; and those (2) Impulse-reaction Turbines, in 
 which the steam passes through a number of rings of fixed blades and 
 of moving blades, expanding as it travels, an example of which is 
 found in the Parsons turbine 
 
 Work by impulse is produced by high velocities, and as the work 
 is done at the expense of the internal heat, water is formed which 
 thus diminishes the heat left. 
 
 The Parsons _turbine is generally called a reaction turbine, although 
 the correct term should be " impulse-reaction " turbine, as the steam 
 actually does act first by impulse from the guide to the moving blades 
 and afterwards works by reaction from the moving to the guide blades 
 
 De-Laval Turbine. — In the specially shaped diverging nozzle ol 
 the De-Laval turbine shown in the sketch, the steam expands down 
 
 \^>.^^^^ 
 
 ARRANGEMENT OF NOZZLE AND SHU". TING-OFF VAl,g^ 
 
 No. I. — De-Laval Turbine. 
 
 * For more exhaustive information on turbine practice, see author's "The 
 Marine Steam Turbine " (published by Messrs Crosby Lockvvood & Son, London). 
 
 642 
 
I 
 
 Appendix 
 
 643 
 
 to the required exhaust pressure, and the resultant kinetic energy 
 acquired is appHed direct to the small buckets or vanes, the steam 
 being in consequence at a very high velocity. To obtain the best 
 efficiency the circumferential velocity of the turbine blades should be 
 equal to about half the velocity of the steam, and this, of course, 
 demands a very high revolution speed. In the De-Laval turbine the 
 speed is often as. high as 20,000 revolutions per minute; this can, 
 however, be reduced by suitable gearing to about 2,000 revolutions 
 
 No. 2. — View of De-Laval Turbine in Action. 
 
 per minute, but as even this is too high for the shafting of marine 
 engines, the non-adaptability of this turbine for marine purposes will 
 be obvious. The steam is admitted to the nozzles (usually four or six 
 in number) and controlled by regulating hand valves. 
 
 It is worthy of notice that in this type of turbine the turbine wheel 
 is rotated by steam at the expanded or lowest pressure, as the actual 
 expansion takes place in the nozzle (and not within the vanes or 
 buckets), which is specially designed for that purpose. 
 
 The De-Laval type of turbine is much in use for the driving of 
 
644 " Verbal " Notes and Sketches 
 
 dynamos, and many steamers are supplied with this turbine for the 
 hghting set of the steamer.* 
 
 Parsons Turbine.- — In this, the hitest and most successful develop- 
 ment of marine engineering, steam is admitted direct from the boilers 
 to blades on the shaft drum, thus doing away with the necessity for 
 piston valves or slide valves, cylinders, pistons, piston rods, crossheads, 
 connecting rods, cranks, eccentrics, eccentric rods, and links, &c. 
 
 The power to rotate the shaft is therefore applied direct, which in 
 itself constitutes one of the conditions of an ideal engine. The inventor, 
 the Hon. C. A. Parsons, M.A., F.R.S., gives the following brief descrip- 
 tion of the turbine : — 
 
 "The Parsons turbine consists of a CN'lhidrical case with numerous 
 rings of inwardly projecting blades. Within this c)-linder, which is of 
 variable internal diameter, is a shaft or spindle, and on this spindle are 
 mounted blades, projecting outwardly, by means of which the shaft is 
 rotated. The former are called fixed or guide blades, and the latter 
 revolving or moving blades. The diameter of the spindle is less than 
 the internal diameter of the cylinder, and thus an annular space is left 
 between the two. This space is occupied by the blades, and it is through 
 these the steam flows. The steam enters the cylinder by means of an 
 annular port at the forward end ; it meets a ring of fixed guide blades 
 which deflect it so that it strikes the adjoining ring of moving blades 
 at such an angle that it exerts on them a rotary impulse. W hen the 
 steam leaves these blades it has naturally been deflected. The second 
 ring of fixed blades is therefore interposed, and these direct the steam 
 on to the second ring of rotating blades. The same thing occurs with 
 succeeding rings of guide and moving blades until the steam escapes 
 at the exhaust passage." 
 
 Steam from the boiler is admitted by suitable hand valves to the 
 forward end of the casing surrounding the blades, and after passing 
 through a ring of guide blades fixed to the casing, strikes the first ring 
 of shaft or rotor blades ; it next passes through the second ring of fixed 
 blades, then the second ring of rotor blades, and so on, passing alter- 
 nately ring after ring of guide and rotor blades, and so rotating the 
 shaft, until it finally exhausts at the other end of the turbine casing at 
 a reduced jjressure. 
 
 Parallel Flow. — Parsons' marine turbine is known as that of the 
 impulse and reaction " parallel flow " type, as the steam enters the guide 
 vanes in lines parallel more or less to the shaft axis, and in this way 
 passes from end to end of the turbine, reacting, expanding, and falling 
 in pressure as it travels. 
 
 Action of Steam. — As will be seen from the foregoing, the steam 
 striking the blades imparts a turning movement to the shaft, and after 
 
 r /*1TTT> 
 
 reacting and passing through the series of rings of vanes ot the H.r. 
 * For further information on this subject see author's " Marine Steam Turbine." 
 
r^ 
 
 f 
 
 -n- 
 
 
 f G 
 
 in 
 
 ;9: •? ?? ?? f' *'??;? SJ.I:^ 
 
 >7T" i'.: tTf-H"-i--i > »i 
 
 ~f. 
 
 1NO.I 
 
 V 
 
) Revene eating. (5) Reverse casing brackets, (6) Ahead dummy. (7) First ahe«] expansion, (8) Second ahead expansion. (9) Third nhcad expaniion. (to) Tourth ah B^d expansion, (ii) Firth ahend expan si oa 
 it Eighth ahead expanrion. (15) Reirerse dummy. (16) First reverse expansion. (17) Second reverse expan<iion. {18) Third reverse expansion. (19) Fourth reverse expansion, (jo) Ahead steam from H.P. cxhausL 
 oilWB. (^3) Ahead wheel, (m) Reverse wheel, (aj) "Junction" wheel. (16) Oil baffles lij) (Hand ring bush. (18) Radial ■' fin" ring buvli. (19) "Leak off" pocket. (30) Guide columns for lifting cover. 
 ) Thnisl block. (311 Adjusting rings- (33) Worm fort^ounter gear, (n) Reverse sicam admission to lint expansion. (35) Main bearings 
 
No. 3.— Path traced out by Steam in Parsons Turbine. 
 
■h-\t'JiX^-m»:fA^V^.i'w', 
 
 >^Hs^v^-i4ri; 
 
No. 3.— Path traced out by Steam in Parsons Turbine. 
 
646 " V'^erbal" Notes and Sketches 
 
 turbine exhausts simultaneously into the two L.P. turbines, one on 
 either side, and expanding through the longer casing and shaft blades 
 of these turbines, finally exhausts, at a low absolute pressure of from 
 1 1 to 2 lbs., into the condensers, one for each L.T. turbine. 
 
 Flow of Steam through Blades. — The diagram on page 629 shows 
 graphically the path followed out by the steam as it passes through 
 each successive ring of fixed or moving blades. Observe that the 
 steam, after passing through the first ring of guide blades, strikes the 
 first ring of rotor or moving blades and by the action set up assists 
 in rotating the shaft ; by the time the steam has changed its direction 
 the rotor has moved round a certain distance (from i to 2), and the 
 reaction of the steam, due to its somewhat sudden change of direction, 
 still further assists in rotating the shaft. The steam then leaves the 
 rotor blades and enters the next ring of guide blades, where, after 
 again being deflected in its path, it enteis the next ring of moving 
 blades, where the action and reaction process is again repeated ; 
 leaving the second ring of moving blades at position 4 the steam 
 enters the third ring of guide blades at a point 5 still farther round the 
 circumference, and so on for each of the following rings. 
 
 It should be noted that the steam leaving the moving blades is 
 deflected by the blade curvature, and strikes the casing blades, 
 which, if free to revolve, would be acted on by the steam and moved 
 round similarly to the rotor blades, but in the opposite direction ; 
 instead of this taking place, however, the casing blades being fixed 
 resist the impact, and the resulting reaction throws back the steam, 
 the velocity of which is thus increased. The pressure is therefore 
 utilised in augmenting the steam speed, hence the statement that 
 " in the guide blades the steam does work on itself to increase its 
 own velocity." The steam thus describes a somewhat zigzag path 
 in passing along the rotor, its direction being not unlike that of a 
 screw thread. Work is done at each ring of blades and 'heat given 
 up, expansion of the steam taking place in due proportion, so that 
 the velocity of flow increases, and to allow for this the lengths and 
 spacings of the blades must be increased to maintain the same ratio 
 between the blade velocity and the steam velocity, upon which the 
 turbine efficiency depends. 
 
 The diagram shows the imaginary path described by a small 
 portion of steam, and the dotted blades show the circumferential 
 advance of the rotor blades at each ring, which produces the thread- 
 like path traced out by the steam. 
 
 Turbine Arrangements. — In steamers of normal size for either 
 channel or deep-sea service, the standard arrangement consists of five 
 turbines, three for ahead and two for reverse running ; three shafts are 
 fitted with one propeller on each, the reverse turbines being placed 
 within the L.P. turbine casings aft. In exceptionally large steamers, 
 such as the " Lusitania " and " Mauretania," four lines of shafting are 
 arranged, with two ahead H.P. turbines and two ahead L.P. turbines, 
 
( 6 ) Manctuvring valve for L.P. ahead o 
 1 L.l\ ahuad. 
 ) Steam pipe lo L.P. i 
 I H,P, exhaust steam to L.P. turbines. 
 ; loi Spring-loaded non-return valveT 
 to condensers, 
 o glands. 
 lisinhuiing chest i'or steam to glands. 
 ;. diiced sieam to port L.P. turbine glands. 
 
 turbines. This 
 
 omitted in the case of L.P. turbines, 
 
 but still exists in H.P. turbines, 
 
 (iS.\) Special H.P. gland "leak off" to con- 
 denser, used when working I-P. turbines 
 only. This connection is now omiucd. 
 
 (19) Relief valves. 
 
 (;o) Pummy "leak off" to 3rd expansion. 
 
 H.I', hye-piass steam to 3rd exp«n! 
 0:1 inlet 10 bearings. 
 
 bearings- 
 
 aier inlet to bearings. 
 
 atcr outlet from bearings. 
 
 iiculating n-aler to condenser. 
 
 irculating waiter discharge ovfrbotrd. 
 
 U'et" air pump suction from condeiucn. 
 
 Dry " air pun)p suction from condeitsers. 
 casing dnuns to "wet" air 
 [lumps. 
 H.P. tuibinc casing drain to LP. lorbi-iv 
 Scitwdown ^ulvc ot cock. 
 .\fier main beating. 
 V'.irrt-ard nuin l>earii% -uv't \hi\xix 
 
Appendix 
 
 (i) Standard arrangement, 
 one 1 1. 1', and two L.l'. 
 turbines, three shafts, one 
 propeller to each. 
 
 (2) Large passenger 
 steamer arrangement, 
 two H.P., two L.P., and 
 
 two independent reverse 
 turbines, four shafts, one 
 propeller to each. 
 
 (3) Torpedo craft arrange- 
 ment, one cruisin<^, one 
 I. P., one H.P., and one 
 L.P. turbine, three shafts, 
 one propeller to each. 
 
 Battleship or cruiser 
 arrangement, two cruis- 
 ingahead,twoH.P. ahead, 
 two L.P. ahead turbines, 
 also two H.P. reverse, and 
 two L.P. reverse turbines, 
 four shafts, one propeller 
 to each. 
 
Appendix 
 
 647 
 
 (i) Standard arrangement, 
 one 1 1. P. and two L.T. 
 turbines, three shafts, one 
 propeller to each. 
 
 L arge passenger 
 steamer arrangement, 
 two H.P., two L.P., and 
 two independent reverse 
 turbines, four shafts, one 
 propeller to each. 
 
 [3) Torpedo craft arrange- 
 ment, one cruising, one 
 LP., one H.P., and one 
 L.P. turbine, three shafts, 
 one propeller to each. 
 
 (4) Battleship or cruiser 
 arrangement, two cruis- 
 ing ahead, two H. P. ahead, 
 two L.P. ahead turbines, 
 also two H.P. reverse, and 
 two L.P. reverse turbines, 
 four shafts, one propeller 
 to each. 
 
648 " Verbal " Notes and Sketches 
 
 also two independent reverse turbines on the inner shafts. This 
 arrangement, with the further addition of other two reverse turbines 
 and two cruising turbines, is carried out in the case of large battle- 
 ships and cruisers ; sometimes the cruising turbines are compound, 
 one H.P. and one M.P., but generally both are of the same size, and 
 receive direct steam from the boilers simultaneously. It should be 
 noted that the Admiralty have decided to discard cruising turbines 
 altogether in future, as in most cases the consumption at the low- 
 powers developed by these turbines does not justify their existence, 
 in addition to the loss of power produced by the turbine blade 
 resistance when running ahead or astern with the main turbines. 
 Cruisers of the " Inflexible "-" Indomitable" type have ten turbines 
 fitted, four ahead turbines — two H.P. and two L.P. — and four reverse — 
 two H.P. and two L.P. — also two cruising turbines fitted, one on 
 each H.P, turbine shaft, and intended for low cruising speeds and 
 powers. 
 
 In torpedo craft the three-shaft arrangement is often carried out, 
 but the turbines are arranged in triple series, one H.P. (centre), one I\I.P. 
 (wing), and one L.P. (wing). Sometimes cruising turbines are fitted in 
 addition to these in the case of large high-speed destroyers. The fore- 
 going are the arrangements of turbines in present practice, but other 
 arrangements have been proposed by the Parsons Company. 
 
 As regards the new combination arrangement of reciprocating 
 engines and turbine, the steamers at present under construction are 
 fitted with two wing triple or quadruple engines, both exhausting at 
 a pressure below the atmosphere into the turbine on the centre shaft. 
 An alternative design consists of one centre reciprocating engine 
 exhausting into two wing turbines. 
 
 Steam Flow through Turbines. — In the standard turbine arrange- 
 ment of five turbines — three ahead and two reverse — the steam, after 
 expanding through the H.P. turbine, exhausts to both LP. turbines 
 simultaneously, and then to the two condensers. In the "Lusitania" 
 design, the steam expands through each H.P. turbine, then through 
 each L.P. to the condensers of each respective side. 
 
 In the " Inflexible"-" Indomitable " class turbine arrangement, 
 at full ahead power, the steam expands through each H.P., then each 
 L.Po, and then to the condensers of each side. At reduced ahead 
 power, the steam first expands through each ciuising turbine, then 
 through each H.P. and L.P. turbine of each side, finally exhausting 
 to the condensers. In running astern the steam first expands through 
 the H.P. reverse turbine, then the L.P. reverse turbine, and finally 
 exhausts to the condenser. 
 
 In the destroyer triple arrangement at full power, the steam first 
 expands through H.P. turbine, then M.P. turbine, and L.P. turbine 
 to the condenser, and at reduced power or cruising speed, the steam 
 first expands through the cruising turbine, H.P. turbine, M.P. turbine, 
 and L.P. turbine to the condenser. 
 
 ^ 
 
MARINE WORK 
 
 ^^^^.ij^-,u>Y,i,i.- ^■^-^■^-^■^ ^2!S^!:^±^±^ 
 
 
 
 
 
 
 
 
 
 
 Fig. 
 
 S. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 •^ 
 
 I"* 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ^'i. 
 
 ^ 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 o- 
 
 
 >^ 
 
 
 
 
 
 
 
 
 
 
 ~- 
 
 
 
 
 
 
 
 
 ^^ 
 
 ■'A 
 
 A 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 L^ 
 
 r 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 y 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 / 
 
 
 
 
 
 \ 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 1 
 i 
 
 
 
 
 
 
 
 
 
 i 
 1 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 \- 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 [_ 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 5 6 7 6 
 
 B 1 N. V f'CH ROV« 
 
 f To face, page 648. 
 
No. 4.— Sectional View of H.P. Turbine. 
 
 (Also Blade Angles and Steam Velocities.) 
 
 D 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 t^ 
 
 ^ 
 
 V * 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 -- 
 
 r" 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 -^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 , 
 
 < 
 
 r 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 y 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 y 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 / 
 
 
 
 
 
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 _i 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 - 
 
 ~ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 u 
 
 _ 
 
 
 1 
 
 
 L 
 
 U 
 
 
 _ 
 
 _j 
 
 1 
 
 u 
 
 
 
 
 
 
 
 [Tof(Utf<lit6l,%. 
 
RE 
 
RE 
 

 ^lif<ftk»d 
 
 iO^^^Bw/ 
 
 
 ^us^^k 
 
 \ 
 
 
 ■^ 
 
 *^%j 
 
 inmiHiiiii::;: :■ 4t -^ 
 
 p 
 
 k. _; :'/!! ^^M 
 
 *--^4^'" .|||P|I 
 
 ^ ^^^^^ 
 
 ■^^Bj^^^ 
 
 h < 
 
 w^ 
 
 ^f![| 
 
 ' ;aHyBh| 
 
 SW^^S^j' 
 
 
 fJ 
 
 jBw 
 
 Tt 
 
 &lfi 
 
 ^■'^•' 
 
 F 
 
 i 
 
 ^•^^^^^^ J 
 
 m 
 
 ^31 
 
 fcv?' \ .-. ■ 
 
 
 »HM^^^^ 
 
 Nk-ssrs A. & J. InglisHd 
 
 No. 5. ~L.P. Ahead and Reverse Turbines. 
 
 (The H.P. Turbine shown in background. Khedive's Yacht " Mahroussa. ") 
 
Appendix 
 
 649 
 
 Increase of Steam Volume. — To allow of the steam increasing 
 in volume, as fall of pressure takes place, the various sets of blades 
 increase in length from the forward to the after end, the clearance 
 spaces between the blades also increasing in proportion, which 
 necessitates packing pieces of a larger size being employed. The 
 blades also vary in shape or curvature, being flatter in section aft 
 
 >PER WIRE 
 
 BRASS WIRE 
 
 PACKING 
 PIECES 
 
 COPPER WIRE 
 
 No. 6. 
 
 PLAN 
 
 Elevation and Plan of Rotor Blades in Position, 
 showing how secured (full size). 
 
 than forward Each set of blades for each expansion requires its 
 own allowance for expansion of metals by heat, so that the working 
 clearance between the blades and casings or drums increases slightly 
 throughout the turbine from forward aft. One of the practical diffi- 
 culties met with in turbine construction at present is the correct 
 adjustment for this expansion, as slight mishaps have occurred in 
 
I 
 
 4 
 I 
 
 ! 
 
Appendix 
 
 649 
 
 Increase of Steam Volume. — To allow of the stc.-un increasing 
 in vol 11 me, as fall of pressure takes place, the various sets of blades 
 increase in length from the forward to the after end, the clearance 
 spaces between the blades also increasing in proportion, which 
 necessitates packing pieces of a larger size being employed. The 
 blades also vary in shape or curvature, being flatter in section aft 
 
 OPPER WIRE 
 
 BRASS WIRE 
 
 PACKING 
 PIECES 
 
 COPPER WIRE 
 
 PLAN 
 
 No. 6. — Elevation and Plan of Rotor Blades in Position, 
 showing how secured (full size). 
 
 than forward Each set of blades for each expansion requires its 
 own allowance for expansion of metals b)' heat, so that the working 
 clearance between the blades and casings or drums increases slightly 
 throughout the turbine from forward aft. One of the practical diffi- 
 culties met with in turbine construction at present is the correct 
 adjustment for this expansion, as slight mishaps have occurred in 
 
650 
 
 " Verbal " Notes and Sketches 
 
 one or two instances owing to fouling of the parts when heated up, 
 the clearance allowance being insufficient. 
 
 Strictly, each successive ring of blades should be either of a wider 
 pitch or greater height than the preceding one, as the steam is con- 
 tinuously falling in pressure and expanding in volume. 
 
 Dummies. — The dummies are placed at the steam admission end of 
 each turbine, and two kinds of dummies, known respectively as radial 
 and facial; are employed : the facial dummy is usually fitted in the ahead 
 turbine, and the radial dummy in the astern turbine. The principle of 
 the dummy is to prevent the steam from escaping through the interior 
 of the rotor to the exhaust end of the casing instead of doing its 
 legitimate work in passing thrdugh the blades of the turbine. Another 
 reason is that if no dummies weve fitted, the full initial pressure would 
 be on the glands instead of exhaust or terminal pressure. A facial 
 
 No. 8. — Ahead H.P. Dummy Facial Rings. 
 
 (With average dimensions.) 
 
 dummy consists of two parts called the casing dummy and the rotor 
 dummy. The casing dummy is a cast-iron cylinder, which is in two 
 halves, bolted together at the horizontal joint. This cylinder is bored 
 out and grooved, the grooves being usually |^ in. wide and ^o in- deep, 
 and into these grooves are driven brass strips. The brass strips 
 are bent to the radius of the cylinder, and a serration made 
 in them, so that the serration is just flush when the strip is driven 
 into groove. After the blades are in place, the metal of the cylinder 
 is caulked into the serration, thus binding the strips. The strips are 
 cut in leneths of about 6 in. 
 
(1) Ahead thr 
 
 (2) Astern thr 
 
 (3) Taper key 
 
 (4) Taper key 
 
No. 7.— Turbine Thrust Block. 
 
 Lower Half for Ahead Thrust; Upper Half for Astern Thrust 
 
 (1) Ahead thrust. 
 
 (2) Astern thrust. 
 
 (3) Taper key for adjustment of lower half. 
 
 (4) Taper key for adjustment of upper half. 
 
 (9) "Reliefs" for wear do 
 
 (5) Oil inlet. 
 
 (6) Counter gear worm. 
 
 (7) Inspection door. 
 
 (8) White metal of mean bearing. 
 
 iTo f<uc page bso. 
 
Appendix 
 
 651 
 
 "BLADING LIST." 
 
 The following example of a " blading list " from actual practice will 
 afford the student a fair idea as to the blade heights, &c., generally 
 fitted :— 
 
 Type — Fast Channel Steamer. 
 
 Speed, 22 knots. 
 Equivalent I.H.P., 8,500 (approximate). 
 
 Turbine Data. 
 
 II. r. Turbine. (Drum, 2 ft. 6 in. Diam.) 
 
 Expansion. • 
 
 Number of Blade 
 Rows. 
 
 Klade Heights. 
 
 I 
 
 2 
 
 3 
 
 4 
 
 13 
 13 
 14 
 
 14 
 
 \\ in. 
 
 3 ,> 
 4* „ 
 
 L.P. Ttirbines (two). (Drums, 3 ft. 9 in. Diam.) 
 
 Expansion. 
 
 Number of Blade n, , tt • 1 . 
 r, B acle Hemnts. 
 
 Rows. \ ° 
 
 I h in. 
 
 3 » 
 
 4i „ 
 
 8 „ 
 
 Astern Turbines. (2 ft. 6 in. Diam.) 
 
 Expansion. 
 
 Number of Blade 
 Rows. 
 
 10 
 10 
 10 
 10 
 10 
 
 Blade Heights. 
 
Ife 
 
 il 
 
Appendix 
 
 6sr 
 
 "BLADING LIST." 
 
 The following example of a " blading list " from actual practice will 
 afford the student a fair idea as to the blade heights, &c., generally- 
 fitted :— 
 
 Type— Fast Channel Steamer. 
 
 Speed, 22 knots. 
 Equivalent I.H.P., 8,500 (approximate). 
 
 Turbine Data. 
 //./'. Turbine. (Drum, 2 ft. 6 in. Diam.) 
 
 Expansion. - 
 
 Number of Blade 
 Rows. 
 
 Blade Heights. 
 
 I 
 
 2 
 
 3 
 4 
 
 13 
 13 
 14 
 14 
 
 \\ in. 
 3 ,. 
 
 L.P. Turbines ( 
 
 two). (Drums, 3 
 
 ft. 9 in. Diam.) 
 
 
 Number of Blade 
 
 
 Expansion. 
 
 Rows. 
 
 B'ade Heights. 
 
 I 
 
 7 
 
 I \ in. 
 
 2 
 
 7 
 
 2\ „ 
 
 3 
 
 7 
 
 3 „ 
 
 4 
 
 7 
 
 4i „ 
 
 5 
 
 7 
 
 6 V 
 
 6 
 
 7 
 
 8 „ 
 
 7 
 
 7 
 
 8 „ 
 
 8 
 
 7 
 
 8 „ 
 
 Astern Turbines. (2 ft. 6 in. Diam.) 
 
 Expansion. 
 
 Number of Blade 
 Rows. 
 
 Blade Heights. 
 
 I 
 
 2 
 
 3 
 
 4 
 
 5 
 
 10 
 10 
 10 
 10 
 
 10 
 
 2 " 
 
 -^1 » 
 
652 
 
 " Verbal " Notes and Sketches 
 
 the casing in one row a 9-in. piece is put in, and in the succeeding 
 row a 42-in. piece is put in, so that the joints in each row are not in 
 line. The strips are left "-012" clear of each other at the ends so as 
 to allow for expansion. After the blades are all in place and 
 caulked, the dummy is put into lathe, and the blades turned up. 
 The blades have a face bearing of "-015 " so as to ensure that if the 
 rotor dummy should touch, the friction caused thereby would 
 be reduced to a minimum. The rotor dummy is of steel, and 
 usually cylindrical, and is sometimes made in two halves. The 
 dummy is rigidly bolted to the rotor, and turned up in place. A 
 series of grooves corresponding to the brass strips in the casing 
 dummy are turned out, having a fillet in both sides of groove, the 
 grooves being fV in. deep. The brass strips in the casing dummy 
 project into the groove in the rotor dummy | in. W' hen the rotors 
 are set to position in the casing, the factor which determines this 
 position is the dummy clearance, this var)-ing according to the size 
 of turbines. For average sizes the clearance is usually as follows : — 
 
 ■025 to -040 in the high-pressure turbine, 
 and -025 to -060 in the low-pressure turbine. 
 
 The working clearance allowed between the tips of the rotor 
 blades and casing, also between the casing blades and rotor, are given 
 in the following table taken from an actual case : — 
 
 BLADE TIP CLEARANCES. 
 
 Taken when cold. 
 H.P. Turbine. 
 
 Rotor Drum, 48 in. Diameter. 
 
 Expan- 
 
 Radial Clearance 
 (Port). 
 
 Radial Clearance 
 (Starboard). 
 
 Longitudina 
 
 1 Clearance. 
 
 
 
 
 
 
 
 
 
 
 Rotor 
 
 Casing 
 
 Rotor 
 
 Casing 
 
 Port 
 
 Port 
 
 Starboard 
 
 Starboard 
 
 
 Blade 
 
 Blade 
 
 Blade 
 
 Blade 
 
 F(3rward 
 
 Aft 
 
 Forward 
 
 Aft 
 
 
 Tips. 
 
 Tips. 
 
 Tips. 
 
 Tips. 
 
 Side. 
 
 Side. 
 
 Side. 
 
 Side. 
 
 
 
 
 
 
 Inch. 
 
 Inch. 
 
 Inch. 
 
 Inch. 
 
 No. I 
 
 •041 
 
 •041 
 
 •052 
 
 •043 
 
 i 
 
 fV 
 
 1 .'. 
 Itj 
 
 '•.\'i 
 
 „ 2 
 
 •051 
 
 •055 
 
 •059 
 
 •049 
 
 
 4 
 
 1 
 
 4 
 
 1 
 
 4 
 
 .. 3 
 
 •063 
 
 •055 
 
 •070 
 
 •061 
 
 _y_ 
 
 1 
 
 4 
 
 •1 
 
 i 
 
 „ 4 
 
 •049 
 
 •055 
 
 •054 
 
 ■051 
 
 b i 
 
 Tff 
 
 :j -.; 
 
 
H 
 
 .^ 
 
 tA 
 
 
 O 
 
 ''5 
 
 
 
 Pi 
 
 aj 
 
 
 
 
 ^ 
 
 s: 
 
 
 o 
 
 '? 
 
 O 
 
 4J 
 
 
 
 5 
 
 -c 
 
 
 •z 
 
 tn 
 
 CS 
 
 
 ^ 
 
 ^ 
 
 3 
 
 
 o 
 
 '^ 
 
 
 
 o 
 
 
 
 
 z 
 
 3 
 
 
 
 
 
 
 "■y 
 
 0^ 
 
 D 
 
 
 
 x^ 
 
 ^ 
 
 
 o 
 
 o 
 
 "o 
 
 
 u 
 
 C 
 
 tJ 
 
 
 c 
 
 1) 
 
 C/5 
 
 rs 
 
 c5 
 
 cE 
 
 w 
 
 :-• 
 
 OJ 
 
 a> 
 
 
 < 
 
 3 
 cS 
 
 C 
 
 
 pq 
 
 1) 
 
 •5 
 
 ^ 
 
 
 > 
 
 Z3 
 
 , 
 
 
 
 
 
 ti- 
 
 tJ} 
 
 'tr 
 
 IT: 
 
 o 
 
 C 
 
 c: 
 
 rt 
 
 s ^ 
 
 H ^ 
 
 
 
Appendix 
 Starboard L.P. Turbine. 
 
 Rotor Drum, 68 in. Diameter. 
 
 '0.5 
 
 NOTE. 
 
 •050 inch = -5 — inch, 
 1000 
 
 •092 inch = -2^ inch, &c., &c. 
 1000 
 
 
 Kiulial Clearance 
 (I'ort). 
 
 Radial Clearance 
 (Starboard). 
 
 Longiludina 
 
 1 Clearance. 
 
 sion. 
 
 
 
 
 
 
 
 
 
 
 Rotor 
 
 Casing 
 
 Rotor 
 
 Casing 
 
 Port 
 
 Port 
 
 Starboard 
 
 Starboard 
 
 
 Blade 
 
 Blade 
 
 Blade 
 
 Blade 
 
 I'orward 
 
 Aft 
 
 Forward 
 
 Aft 
 
 
 Tips. 
 
 Tips. 
 
 Tips. 
 
 Tips. 
 
 Side. 
 
 Side. 
 
 Side. 
 
 Side. 
 
 
 
 
 
 
 Inch. 
 
 Inch. 
 
 Inch. 
 
 Inch. 
 
 No. I 
 
 •070 
 
 
 080 
 
 •068 
 
 •070 
 
 7 
 
 7 
 
 1 ••> 
 
 1 7 
 6T 
 
 » 2 
 
 •072 
 
 
 085 
 
 •070 
 
 •085 
 
 5 
 1ft' 
 
 7 
 
 i 
 
 iV 
 
 >> 3 
 
 •07S 
 
 
 090 
 
 •082 
 
 •092 
 
 1 1 
 
 9 
 
 i 
 
 1 7 
 
 '6'T 
 
 n 4 
 
 •0S2 
 
 
 092 
 
 •082 
 
 •085 
 
 3 
 
 n 
 
 5 
 
 To" 
 
 3 
 
 8' 
 
 M 5 
 
 •085 
 
 
 093 
 
 •08 s 
 
 •08S 
 
 7 
 
 11 
 
 15-1 
 
 1 1 
 
 1 1 
 
 ^2 
 
 „ 6 
 
 •095 
 
 
 T23 
 
 •098 
 
 •115 
 
 7 
 J 6" 
 
 i 
 
 13 
 
 l^ff 
 
 n 7 
 
 •102 
 
 
 1^5 
 
 •105 
 
 •112 
 
 iV 
 
 ^ 
 
 7 
 
 15 
 
 „ s 
 
 •102 
 
 •H5 
 
 •105 
 
 •II ^ 
 
 I'g- 
 
 A 
 
 1 (V 
 
 i 
 
 44 
 
 No. 9. — Plan of Turbine Room. 
 
654 
 
 "Verbal" Notes and Sketches 
 
 
 
 
 
 s 
 
 
 
 
 
 
 ei 
 
 
 
 
 
 
 a> 
 
 
 
 
 
 
 
 
 
 
 
 
 M 
 
 
 
 
 
 
 V 
 
 
 
 
 
 
 ^ 
 
 
 
 
 
 
 -O-i 
 
 
 
 
 
 
 M 
 
 
 
 
 
 
 u 
 
 
 
 
 
 
 
 
 
 
 
 # 
 
 I 
 
 CO 
 
 
 ■"-^ 
 
 p 
 
 1 
 
 Q 
 
 n 
 
 
 rt 
 
 
 
 Q 
 1^ 
 
 
 s 
 
 W5 
 
 s 
 
 
 
 U 
 
 £ 
 
 
 fo 
 
 tJ- 
 
 .3 
 •a 
 
 
 
 3 
 
 Q 
 
 
 
 •a 
 
 'Tn 
 
 o 
 
 (m 
 
 
 
 ^ 
 
 a 
 
 0) 
 
 o 
 
 
 
 0) 
 
 r- 
 
 •^ 
 
 
 
 
 bo 
 
 .5 
 
 5 
 
 0) 
 r5< 
 
 H 
 
 
 
 OT 
 
 T3 
 
 rt 
 
 
 
 
 2 
 
 c 
 
 ^ 
 
 •a 
 
 
 
 
 w 
 ii 
 
 < 
 
 S 
 
 f3 
 
 3 
 
 3 
 
 c: 
 
 O 
 
 1 
 
 b 
 
 3 
 
 'O 
 
 >> 
 
 1 
 
 3 
 
 o 
 
 c 
 
 
 
 © 
 
 u 
 
 h/1 
 
 ^ 
 
 o 
 
 
 
 Ih 
 
 n 
 
 
 O 
 
 Ui 
 
 
 
 
 u^ 
 
 ^ 
 
 
 o 
 
 o 
 
 S 
 
 
 fi) 
 
 
 Z 
 
 KU 
 
 
 J3 
 
 
 .s 
 
 o 
 
 a 
 
 
No. II. — Plan of Combined Reciprocating and Turbine Arrangement. 
 
 With Theoretical Horse Powers. 
 
 (1) Change valve, giving steam either to turbine or condenser direct 
 
 (2) Reciprocating engine thrust block. 
 
 (3) Turbine thrust block. 
 
 [^1 Efihaust trom reciprocating engine to turbine or to condenser. 
 (5) Branch to turbine. 
 (6i Branch to condenser. 
 
Appendix 655 
 
 Combined Reciprocating Engines and Turbines. — The most recent 
 practice in mercantile steamers is tlie combination of reciprocating 
 engines and turbines for vessels of moderate or low speeds. Several 
 steamers of this class are at present under construction, and the 
 arrangement consists of two wing triple or quadruple expansion 
 engines exhausting into a central low-pressure ahead turbine, driving 
 a third shaft and propeller, the revolution speed of the centre turbine 
 shaft being much higher than that of the wing shafts. An alternative 
 design is that of two wing low-pressure turbines and one centre re- 
 ciprocating engine. 
 
 The engines are arranged to be run as follows : — 
 (i) Boiler steam to both H.P. cylinders, and exhaust from these 
 to turbine, the exhaust from the turbine being divided and led into 
 two separate condensers. 
 
 (2) Boiler steam to both H.P. cylinders, and exhaust from these 
 to condensers direct, the turbine being then cut off. This is required 
 when running astern as the turbine is for ahead running only, and 
 may be used for ahead running with two propellers only. 
 
 (3) Boiler steam to either H.P. cylinder, and exhaust from L.P. 
 to centre turbine, then into one condenser only. 
 
 These combinations are obtained by the use of " change valves " 
 fitted on the L.P. exhaust pipes, and by large butterfly valves fitted 
 in the turbine exhaust branches. The change valves admit the 
 reciprocating exhaust steam of either side to the turbine, or to the 
 condenser as required, and the large valves in the turbine exhaust 
 I)ipe shut oiT the condenser on either side as may become necessary 
 should one reciprocating engine require to be disconnected through 
 breakdown. 
 
 Benefits of the System. — As, broadly speaking, the economy of the 
 reciprocating engine depends chiefly on high-pressure steam, and the 
 turbine on low-pressure steam, the judicious combination of the two 
 ought to result in higher efficiency results. 
 
 The turbine is therefore most effective in dealing with steam of a 
 pressure which cannot be utilised with benefit in a triple or quadruple 
 expansion engine, owing more particularly to the huge volumes 
 involved, and requiring increase of weight, space, and frictional losses. 
 
 The L.P. exhaust pressure to the centre turbine is usually 7 or 
 12 lbs. absolute. This will produce a difference in the usual L.P. 
 cylinder diagram cards, bringing up the exhaust line to a position 
 much nearer the atmospheric line than usual. 
 
 The loss of work energy so represented by the reduced indicator 
 card area in the L.P. engine will be more than balanced by the in- 
 crease of power developed in the turbine. 
 
 The economical result of the combination arrangement is, to all 
 appearance, beyond question, and may in time, with suitable improve- 
 ments which experience suggests, prov'e adaptable for the usual tramp 
 steamer speed of from 8 to 10 or 1 1 knots. 
 
 An innovation has been made in the case of the turbine glands, 
 
^[. . • . 
 
 CONDENSER 
 
 3 
 
 1? -I'd I 
 
 No. 
 
 (1) Change valve, giving steam either toiser. 
 
 (2) Reciprocating engine thrust block. 
 
 (3) Turbine thrust block. 
 
 ^oftuepa^ 655. 
 
A})peiKlIx 655 
 
 Combined Reciprocating- Engines and Turbines. — The most recent 
 practice in mercantile steamers is the combination of reciprocating 
 engines and turbines for vessels of moderate or low speeds. Several 
 steamers of this class are at present under construction, and the 
 arrangement consists of two wing triple or quadruple expansion 
 engines exhausting into a central low-pressure ahead turbine, driving 
 a third shaft and jjropeller, the revolution speed of the centre turbine 
 shaft being much higher than that of the wing shafts. An alternative 
 design is that of two wing low-pressure turbines and one centre re- 
 ciprocating engine. 
 
 The engines are arranged to be run as follows : — 
 (i) Boiler steam to both H.P. cylinders, and exhaust from these 
 to turbine, the exhaust from the turbine being divided and led into 
 two separate condensers. 
 
 (2) Boiler steam to both H.P, cylinders, and exhaust from these 
 to condensers direct, the turbine being then cut off. This is required 
 when running astern as the turbine is for ahead running only, and 
 may be used for ahead running with two propellers only. 
 
 (3) Boiler steam to either H.P. cylinder, and exhaust from L.P. 
 to centre turbine, then into one condenser only. 
 
 These combinations are obtained by the use of " change valves " 
 fitted on the L.P. exhaust pipes, and by large butterfly valves fitted 
 in the turbine exhaust branches. The change valves admit the 
 reciprocating exhaust steam of either side to the turbine, or to the 
 condenser as required, and the large valves in the turbine exhaust 
 pipe shut off the condenser on either side as may become necessary 
 should one reciprocating engine require to be disconnected through 
 breakdown. 
 
 Benefits of the System. — As, broadly speaking, the economy of the 
 reciprocating engine depends chiefly on high-pressure steam, and the 
 turbine on low-pressure steam, the judicious combination of the two 
 ought to result in higher efficiency results. 
 
 The turbine is therefore most effective in dealing with steam of a 
 pressure which cannot be utilised with benefit in a triple or quadruple 
 expansion engine, owing more particularly to the huge volumes 
 involved, and requiring increase of weight, space, and frictional losses. 
 
 The L.P. exhaust pressure to the centre turbine is usually 7 or 
 12 lbs. absolute. This will produce a difference in the usual L.P. 
 cylinder diagram cards, bringing up the exhaust line to a position 
 much nearer the atmospheric line than usual. 
 
 The loss of work energy so represented by the reduced indicator 
 card area in the L.P. engine will be more than balanced by the in- 
 crease of power developed in the turbine. 
 
 The economical result of the combination arrangement is, to all 
 appearance, beyond question, and may in time, with suitable improve- 
 ments which experience suggests, prove adaptable for the usual tramp 
 steamer speed of from 8 to 10 or 1 1 knots. 
 
 An innovation has been made in the case of the turbine glands, 
 
656 " Verbal " Notes and Sketches 
 
 which, instead of the frictionless steam packing hitherto adopted, have 
 in one case been changed for the usual marine type of piston-rod gland, 
 consisting of rack and pinion screwing-up gear with soft packing inside, 
 this type of gland being fitted at both ends of the turbine. 
 
 Description of the Propelling Machinery of the Q.SS. 
 " Reina Victoria-Eugenia." 
 
 Constructed by Messrs Swan, Hunter, & V/igham Richardson Ltd., 
 Newcastle-on-Tyne. 
 
 " The propelling machinery consists of two complete units of 
 reciprocating. engines and turbines, driving four screws in all. 
 
 " The reciprocating engines are of the well-known four-crank triple- 
 expansion type, balanced on the Yarrow-Schlick-T weedy principle, 
 with cylinders 29 in., 43 in., 45 in., and 47 in. in diameter, and a stroke 
 of 42 in. The low-pressure cylinders at each end of the engines are 
 designed to develop less power than the other two cylinders, so that 
 a very uniform turning moment is obtained, in addition to good 
 balancing. 
 
 " Each engine exhausts into a steam turbine through special 
 manceuvring-valves mounted at the back of each low-pressure 
 cylinder, and operated by levers on the reversing-shaft. These valves 
 are so arranged that the exhaust steam is passed direct to the con- 
 denser when the reversing-gear is in the astern position. Thus all 
 manoeuvring is done by the reciprocating engines on the inboard 
 shafts. Provision is made, by means of screw and hand-wheel, 
 whereby the turbines can be cut out entirely by passing the steam 
 directly into the condenser under all conditions. 
 
 " The turbine installation comprises two low-pressure Parsons 
 turbines driving the wing-shafts, and designed for working ahead 
 only. Steam enters each turbine at the forward end through two 
 i8i-in. diameter pipes — z>., one from each low-pressure cylinder — 
 with a suitable strainer in each branch, the admission pressure being 
 about 10 lbs. per square in. absolute, with a maximum steam con- 
 sumption of 135,000 lbs. per hour. The exhaust branch, having a 
 cross-sectional area of 30 sq. ft., is designed for a condenser pressure 
 of I lb. absolute. The rotor drum is parallel, 6S in. in diameter, and 
 carries thirty rows of blades. The dummy at the forward or steam 
 end is fitted with labyrinth-packing strips of the radial type — ten 
 strips in the rotor and ten in the casing. The diameter of the dummy 
 is such that the total axial steam thrust on the rotor substantially 
 balances the propeller thrust. The rotor shaft glands are of Parsons 
 combined labyrinth and ring type, each being fitted at the inner end 
 with ten rows of moving, and ten rows of fixed, rings, and with four 
 Ramsbottom rings at the outer end. The glands are so designed as 
 to be easily overhauled without lifting the turbine-cover. The rotor 
 journals at each end are 12 in. in diameter, working in white-metal 
 bearings, each 23^, in. long. A rotor adjusting-block is fitted at the 
 
.a^A 
 
 ^ 
 
 •.A .\ 
 
 recorded on a double run was i8-6 knots in shallow water (about 
 75 ft. deep), as, owing to the foggy weather, the mile-posts could only 
 be seen a small distance from the shore. 
 
 "A set of indicator-cards taken during the eight hours' trial is 
 shown, and the results are of special interest in view of the high pro- 
 
18 ei OveraU 
 
 Exhaust Branch 5 0>G ^^ 
 
 BranchtjIGiDia 
 
 SETN'IZ (IS.S.ReiNAVICTORIA-EUGENIA. SET N1I2 
 
 PORT ENGINE. a HOURS STEAM TRIAL STARBOARD ENGINE. 
 R^s.p»Min .in- J ^ FEB. 1313. jf^^ per Mm. 115S 
 
 J,H.fi616 LMJi 1S 6 
 Total nLF.3800 aGHOTotall.lW. 
 
 Total IMJ'. Both Engines 74SP 
 
 No. 12.— Parson's Exhaust Turbine for the Q.SS. " Reina Victoria Eugenia' 
 (and Set of Diagram Cards). 
 
 iTo/acefngcbii. 
 
Appendix 657 
 
 forward end for the purpose of adjustiiiij^ the axial position of the 
 rotor, and contains ten rini^s, which bear upon the faces of correspond- 
 in^j collars on the rotor shaft. Lubricating oil is supplied under 
 pressure to the bearings and adjusting-blocks by a duplex oil-pump. 
 The oil draining from the bearings, &c., is collected in a tank and 
 cooled before being discharged again to the bearings. One of the 
 turbines is illustrated on opposite page. 
 
 " The condensers are of the ' Uniflux ' type, and have each a 
 cooling surface of 5100 sq. ft., designed for a vacuum of 28 in. with 
 an average sea temperature of 75'. The 19-in. circulating-pumps 
 supplied by Messrs H. Watson & Co. have proved capable of dis- 
 charging 8500 gallons per minute against 23-ft head. 
 
 "The air-pumps are of Weir's latest 'Dual' type, of 13 in. by 
 24 in. by 17 in. each. There are further installed two pairs of Weir's 
 feed-pumps, with cylinders 13^ in. by 10 in. by 24 in., two 35-ton 
 evaporators, two 90-in. Howden fans, three 60-kw. dynamos, a 
 12-ton distiller, a ballast donkey, two general service donkeys, various 
 smaller pumps, a refrigerating plant, and a Clayton fire-extinguish- 
 ing machine, which has already been illustrated and described in 
 Engineering. The exhaust steam from all auxiliaries is utilised 
 for heating up the feed-water, a ' Neptune ' surface-heater being in- 
 stalled for this purpose. 
 
 "There are seven single-ended boilers of 16 ft. 3 in. outside 
 diameter and 11 ft. 6 in. in length, working on Howden's system of 
 forced draught. Each boiler has three large furnaces, yielding a total 
 grate surface of 480 sq. ft. : the total heating surface is 20,965 sq. ft., 
 and the working pressure 180 lbs. per sq. in. 
 
 "On trial the ship half laden was required to steam 17-5 knots for 
 eight consecutive hours, and when fully laden at a speed of 16 knots 
 for twenty-four consecutive hours. The actual results obtained are 
 given in the table on p. 642, and show that on the eight hours' trial 
 a speed of i8-i2 knots was obtained in adverse weather, while on the 
 twenty-four hours' trial the speed obtained was i6-io knots. In good 
 weather conditions and in deep sea, it is certain that higher speeds 
 would have been secured, and we are informed that off Cadiz, in a 
 deep sea and fine weather, the speed obtained has been greatly in 
 excess of that realised at the trials carried out off Newcastle. 
 
 " The steam consumption was measured by means of standard 
 nozzles regularly employed by the builders for this purpose ; the 
 figures given in the table include make-up feed (about 1-5 per cent.). 
 Progressive runs over the measured mile at St Mary's, on the North- 
 East Coast, were made during each trial in order to determine the 
 speeds obtained on the respective trials. The maximum speed 
 recorded on a double run was i8-6 knots in shallow water (about 
 75 ft. deep), as, owing to the ^oggy weather, the mile-posts could only 
 be seen a small distance from the shore. 
 
 "A set of indicator-cards taken during the eight hours' trial is 
 shown, and the results are of special interest in view of the high pro- 
 
i 1 
 
 / 
 
 commnea lauyr.iR.i ana ..ns '■J" !;=•'=-•-'' .7'fi4d'dng''s, and with four 
 with ten rows of '""-'"g; ^"f^J^ ;,""'^,:I ISs a^e so designed as 
 
 &tsr:^hi3it.roW^ t^^^xs^^,--^^^^ «-d at the 
 
Appendix ' 657 
 
 forward end for the purpose of adjusting; the axial position of the 
 rotor, and contains ten rings, which bear upon the faces of correspond- 
 ing collars on the rotor shaft. Lubricating oil is supplied under 
 pressure to the bearings and adjusting-blocks by a duplex oil-pump. 
 The oil draining from the bearings, &c., is collected in a tank and 
 cooled before being discharged again to the bearings. One of the 
 turbines is illustrated on opposite page. 
 
 "The condensers are of the ' Uniflux ' type, and have each a 
 cooling surface of 5100 sq. ft., designed for a vacuum of 28 in. with 
 an average sea temperature of 75. The 19-in. circulating-pumps 
 supplied by Messrs H. Watson & Co. have proved capable of dis- 
 charging 8500 gallons per minute against 23-ft head. 
 
 "The air-pumps are of Weir's latest 'Dual' type, of 13 in. by 
 24 in. by 17 in. each. There are further installed two pairs of Weir's 
 feed-pumps, with cjdinders 13^ in. by 10 in. by 24 in., two 35-ton 
 evaporators, two 90-in. Howden fans, three 60-kw. dynamos, a 
 12-ton distiller, a ballast donkey, two general service donkeys, various 
 smaller pumps, a refrigerating plant, and a Clayton fire-extinguish- 
 ing machine, which has already been illustrated and described in 
 Engi)iecring. The exhaust steam from all auxiliaries is utilised 
 for heating up the feed-water, a ' Neptune ' surface-heater being in- 
 stalled for this purpose. 
 
 "There are seven single-ended boilers of 16 ft. 3 in. outside 
 diameter and 11 ft. 6 in. in length, working on Howden's system of 
 forced draught. Each boiler has three large furnaces, yielding a total 
 grate surface of 480 sq. ft. : the total heating surface is 20,965 sq. ft., 
 and the working pressure 180 lbs. per sq. in. 
 
 "On trial the ship half laden was required to steam 17-5 knots for 
 eight consecutive hours, and when fully laden at a speed of 16 knots 
 for twenty-four consecutive hours. The actual results obtained are 
 given in the table on p. 642, and show that on the eight hours' trial 
 a speed of i8-i2 knots was obtained in adverse weather, while on the 
 twenty-four hours' trial the speed obtained was i6-io knots. In good 
 weather conditions and in deep sea, it is certain that higher speeds 
 would have been secured, and we are informed that off Cadiz, in a 
 deep sea and fine weather, the speed obtained has been greatly in 
 excess of that realised at the trials carried out off Newcastle. 
 
 " The steam consumption was measured by means of standard 
 nozzles regularly employed by the builders for this purpose ; the 
 figures given in the table include make-up feed (about 1-5 per cent.). 
 Progressive runs over the measured mile at St Mary's, on the North- 
 East Coast, were made during each trial in order to determine the 
 ij speeds obtained on the respective trials. The maximum speed 
 recorded on a double run was i8-6 knots in shallow water (about 
 75 ft. deep), as, owing to the '^o^^y weather, the mile-posts could only 
 be seen a small distance from the shore. 
 
 "A .set of indicator-cards taken during the eight hours' trial is 
 shown, and the results are of special interest in view of the high pro- 
 
658 
 
 "Verbal" Notes and Sketches 
 
 pulsive efficiency indicated by the low consumption of power. It 
 should be mentioned in connection herewith that the experiments 
 made by the builders some years ago with a self-propelled mo el 
 have induced them to choose the four-screw arrangement in preference 
 to the three screws, generally applied with the combined system." 
 
 Results of Trials of " Reina Victoria-Eugenia." 
 
 Trial 
 
 8 hours, half-loaded - 
 
 24 hours, fully loaded 
 
 Date 
 
 February 7; 191 3 
 
 February 15 and 16, 1 91 3 
 
 Mean draught 
 
 19 ft. 10 in. 
 
 24 ft. Sh in. i 
 
 Displacement (moulded) - 
 
 10, iSl tons 
 
 13,229 tons 
 
 Sea (waves) - - - - 
 
 ft. to 6 ft. 
 
 Smooth 
 
 Wind 
 
 18 knots ahead to 30 knots 
 
 \'ar}ing between and 
 
 
 starboard bow, 30 knots 
 
 10 knots 
 
 
 port quarter to 40 knots 
 
 
 
 port beam 
 
 
 Barometer . - - - 
 
 29-7 to 29'5 in. - 
 
 30-4 in. 
 
 Distances of runs in each 
 
 
 
 direction . . - . 
 
 2x71 knots 
 
 4 X 89 knots 
 
 Depth (average) 
 
 130 ft. - - - - 
 
 150 ft. 
 
 Speed - . . . . 
 
 l8'l2 knots 
 
 i6-io knots 
 
 Reciprocating engines 
 
 112-6 r.p.m. 
 
 I02-9 r.p.m. 
 
 >) i> 
 
 I per cent, slip - 
 
 4 per cent, slip 
 
 Turbines . - . . 
 
 481 r.p.m. 
 
 395 r.p.m. 
 
 )> 
 
 20 per cent, slip 
 
 13 per cent, slip 
 
 Indicated horse-power 
 
 7340 . - . . 
 
 5760 
 
 Shaft horse-power - 
 
 3500 .... 
 
 2157 
 
 Total horse-power - 
 
 10,840 - - - . 
 
 7910 
 
 s^d"* 
 
 
 
 H.P. 
 
 257 
 
 294 
 
 Pressure, H.P. chest 
 
 170 lbs. per sq. in. 
 
 170-5 lbs. per sq. in. 
 
 ,, turbine 
 
 7-8 lbs. per sq. in. absolute 
 
 5-4 lbs. per sq. in. absolute 
 
 ,, condenser 
 
 0'5 lbs. })er sq. in. absolute 
 
 0'56 lbs. persq. in. absolute 
 
 Temperature, sea - 
 
 43 deg. Fahr. - 
 
 45 deg. I'"ahr. 
 
 ,, discharge - 
 
 70 „ - - - 
 
 64 ' „ 
 
 ,, hot- well - 
 
 70 ,, ... 
 
 62 
 
 feed - 
 
 
 183 
 
 Feed-water consumption for 
 
 
 
 main engines 
 
 114,000 lbs. per hour- 
 
 85,000 lbs. per hour 
 
 Feed-water consumption for 
 
 
 
 auxiliaries - - - . 
 
 
 14,000 ,, ,, 
 
 Air pressure in ash-pits - 
 
 0-4 in. water 
 
 0-35 in. water 
 
 Coal heating value by calori- 
 
 
 
 meter ----- 
 
 14.200 B.Th.U.- 
 
 14,400 B.Th.U. 
 
 Ashes by calorimeter 
 
 
 3 per cent. 
 
 GEARED DOWN TURBINES. 
 
 To allow of combined high turbine speeds and low propeller shaft 
 speeds geared down turbines have recently been introduced. This 
 arrangement admits of economy at low ship speeds, owing to the fact 
 that turbines are most efficient at high revolution speeds, and 
 propellers most efficient at low revolution speeds, 
 
—z'.ei' -^(r 
 
 —z:o't,-—'^r 
 
 ^ 
 
 m^. 
 
 u I'T'i """" connecting rod coupled to the forward end of gear- 
 wheel shaft. The turbine and pinion shaft bearings are under forced 
 lubrication, similar to ordinary turbine practice. The teeth of the 
 
20 Z^- Over Gland MoiUhs 
 
 - n: n%' OverSxpaiwu 
 
 Centre Shaft Exhaust Turbine oi White Star Liner " Britannic." 
 
 (Reproduced by permission from "Engineering." Feb. 27, 1914.) 
 
 White Star Liner " Britannic. 
 
 (By Messrs Harland & Wolff Ltd,) 
 RECIPROCATING ENGINE DATA 
 The two-wing 
 
 ciprocatirig engines 
 ) LP. cylinders placed < 
 Schlick Tweedy system. 
 Diameter of cylinders 
 Stroke . . - , 
 
 Type of valves fitted ■ 
 Type of valve gear ■ 
 
 e of the four cylinder triple 
 at either end, and balanced 1 
 
 . 97 i 
 
 - 97' 
 
 all cylindei: 
 
 Type of pi« 
 
 ngs fitted 
 
 Diameter of H.P. and I P. 
 
 tension steel t 
 Diameter of LP. piston rods 
 
 HP and IP, connecting rods 
 
 LP connecting rods - 
 Diameter and k-ngtli of top ends iH.P. and I. P. 
 
 iL.P.) 
 Diameter of crank pins 
 Length of crank pins (H.P. and I. P.) 
 
 (LP,) 
 Diameter of crank shaft 
 
 thrust shaft 
 Number of collars 
 Total thrust surface per block 
 Diameter of line shafting 
 
 propeller shaft 
 
 Piston valves in 
 
 Stephenson link ; 
 ind Carlisle rings on all cylinder pistons, 
 n all piston valves. The HP 
 isbottom type. 
 
 ipt HP 
 
 s are of the Ra 
 
 .on rods (high 
 
 From 13J 
 
 16J in. by 17} . 
 
 n. 
 
 13! in. by 14! i 
 
 
 27V in. with 9 i 
 
 n, hole. 
 
 35 m. 
 
 
 27 in- with 9 in 
 
 hole. 
 
 27 in. with 9 in 
 
 hole. 
 
 14 in. 
 
 
 6860 sq. ft. 
 
 
 26) in. with 12 
 
 in. hole 
 
 28S in. with 12 ii 
 
 1. hole, reduce*! 
 
 to 6 in hole 
 
 It after end 
 
 Reciprocating Engine Data- -comniueii. 
 
 Propellers of Manganese- bronze with cast steel boss- 
 Diameter of wing propellers - - .2 
 Pitch ,, ..■-■-> 
 Revolutions per minute - .7 
 I. H.P. of combined wing^ reciprocating sets ■ 3 
 
 EXHAUST TURBINE DATA— 
 
 Initial pressure (LP. exhaust from 
 
 eating engines! 
 Vacuum (turbine exhanstl - 
 Over all length of turbine - 
 Weii;ht of rotor complete with bladi 
 Shaft horse power of turbine 
 Revolutions 
 
 Diameter of rotor drum 
 Length ., ,. 
 
 prt. 
 
 Number of collars on tlin 5 i| 
 Total thrust surface 
 Number of blade opansions 
 Blade lietghts (ist expansion} 
 (2nd 
 .. (3rd 
 
 irbine spindles 
 
 10 lbs. absolute. 
 28 in. (with 30 ii 
 50 ft, 
 
 150 tons. 
 
 170 per min. 
 
 14 ft, lit in. 
 reduced to i ft. 9I in. at shaft end. and 
 with hole 23 in diameter, reduced to 11 in diameter 
 at shaft end. 
 
 (4th 
 (Sth 
 
 Steam glands contain 20 ra 
 Size of turbine bearings 
 
 - ■■ j Semi wing and 
 : " j wing blades 
 
 nd 4 Ramsbottom rings. 
 
 3 ft. diameter and 6 ft. 9^ 1 
 
 Exhaust Turbine Data— r('w//««cfl'. 
 
 Diameter of turbine tunnel shaft • • 
 
 propeller shaft - 
 
 Propeller of solid type and of Manganese bronze- 
 Diameter of propeller 
 Pitch of propeller .... 
 
 Condensers Two mam conden'crs and one aux 
 Total cooling surface of mam condensers - 
 Diameter of tubes .... 
 Cooling surface of anxij ary cmidenser 
 
 • 20^ in. with ] 
 
 • 22|| ,, ,, 
 
 to 5 in. at £ 
 
 - 16 ft. 6 in. 
 
 - 15 ft, laboutl. 
 iliary condenser a 
 
 - 50000 sq. ft. 
 
 - :/ in. 
 
 - 3600 sq- ft 
 
 A "change valve " is fitted and connected to the reversing gear, so that when 
 running ahead the two wing reciprucating engine exliausls enter the centre turbine 
 as initial steam, and from thence in the two condensers; but when running astern, 
 the reciprocating engint- exhausts aie clmnged over and led direct tu ihe condensers, 
 thus cutting uut the turbine. Tliis arrangement, is required as the turbine is 
 designed for ahead running only. It will llujs be obvious ihat when running astern 
 the turbine will be turning idly, wl)irh action results in a sliijhl loss of power due to 
 the "windage" action of the turbine blades when revolving inside tho casing. 
 
 Note. — As proving the efficiency of the turbine to utilise low pressure steam, the 
 student should note that the two-wing reciprocating engine, each taking initial steam 
 at about 200 lbs. gauge pressure, and expanding down to a terminal pressure of 
 10 lbs. absolute, developes about i6coo I.H.J*., whereas ihe centre turbine taking 
 initial steam 4x to lbs. absolute pressure, and expanding down to a terminal pressure 
 of about I lb. absolute, developes .ihout iSooo S.H.P. 
 
 It should be noted, however, that the turbine receives to itself the steam of 
 both reciprocating engines combined, and running, as it does, at fully twice the 
 revolution speed of these latter, can dispose of the large steam volumes at low 
 pressure much more conveniently than could be done by ordinary engine cylinders. 
 
Appendix 659 
 
 Arrangement. — In the single propeller shaft arrangement one side 
 H.P. ahead turbine and one side L.P. ahead turbine arc connected by 
 two small gear wheels to two large gear wheels secured to the centre 
 driving shaft. The turbines run at about 1200 revolutions per minute 
 and the propeller shaft at 60 revolutions per minute, the gear-down 
 ratio thus being as 20 : I, because i200-f6o=20. In the two 
 propeller shaft arrangement the above system is usually duplicated, 
 two H.P. and two L.P. turbines being fitted and connected up 
 similarly. The turbines and gear wheels are joined up by flexible 
 type couplings. The gear wheels are enclosed in a casing, and an 
 oil service under pressure is sprayed in jets on to the contact surfaces 
 of the wheels. Thrust blocks are fitted near the forward end of the 
 propeller shaft, to take up the thrust, and the turbines are balanced 
 by steam pressure acting on differential type dummy pistons. The 
 helical-toothed gear wheels are very accurately cut out of hard steel 
 by a machine specially designed for the purpose. The astern turbines 
 are arranged as in ordinary turbine practice, being inside the ahead 
 turbine casing, and fitted with separate steam connections, &c. 
 
 It may be pointed out that the geared down arrangement can be 
 adapted for either low or high ship speeds, but is not so necessary 
 at high speeds as it is at low speeds. The gearing down allows of 
 speeds of 10 or 12 knots with reasonable economy, whereas at these 
 speeds and direct turbine drives the economy would fall off for the 
 reasons mentioned previously. 
 
 The "Vespasian " was built in 1887 by Messrs Short Brothers, of 
 Sunderland. Her dimensions are: — Length on load water line, 
 275 ft.; breadth, moulded, 38 ft. 9 in.; depth, moulded, 21 ft. 2 in.; 
 mean loaded draught, 19 ft. 8 in., and displacement, 4350 tons. The 
 boilers — two in number — are 13 ft. diameter by 10 ft. 6 in. long, with 
 a total heating surface of 3430 sq. ft., and grate area of 98 sq. ft., 
 working under a pressure of 150 lbs. with natural draught. The 
 propeller is of cast iron, and has four blades, having a diameter of 
 14 ft., pitch 16-35 ft., and expanded area of 70 sq. ft. 
 
 Description of Geared Turbines, SS. *'Vepasian." 
 
 The propelling machinery consists of two turbines in " series," 
 viz., one high-pressure and one low-pressure, the high-pressure 
 turbine being placed on the starboard side of the vessel and the low- 
 pressure on the port side. At the after end of each of the turbines 
 a driving pinion is connected, with a flexible coupling between the 
 pinion shaft and the turbine, the pinion on each side of the vessel 
 being geared into a wheel, which is coupled to the propeller shaft. 
 
 A reversing turbine is incorporated in the exhaust casing of the 
 low-pressure turbine. The air, circulating, feed, and bilge pumps 
 are of the usual design for tramp steamers, and are driven by means 
 of a crank and connecting rod coupled to the forward end of gear- 
 wheel shaft. The turbine and pinion shaft bearings are under forced 
 lubrication, similar to ordinary turbine practice. The teeth of the 
 
arrangement admits oi economy ai luw Mnp 3pv.<-vj^, ^^.....^ '^»- 
 
 that turbines are most efficient at high revolution speeds, and 
 propellers most efficient at low revolution speeds, 
 
Appendix 659 
 
 Arrangement. — In the single propeller shaft arrangement one side 
 H.P. ahead turbine and one side L.P. ahead turbine are connected by 
 two small gear wheels to two large gear wheels secured to the centre 
 driving shaft. The turbines run at about 1200 revolutions per minute 
 and the propeller shaft at 60 revolutions per minute, the gear-down 
 ratio thus being as 20 : i, because 1200-^-60 = 20. In the two 
 propeller shaft arrangement the above system is usually duplicated, 
 two H.P. and two L.P. turbines being fitted and connected up 
 similarly. The turbines and gear wheels are joined up by flexible 
 type couplings. The gear wheels are enclosed in a casing, and an 
 oil service under pressure is sprayed in jets on to the contact surfaces 
 of the wheels. Thrust blocks are fitted near the forward end of the 
 propeller shaft, to take up the thrust, and the turbines are balanced 
 by steam pressure acting on differential type dummy pistons. The 
 helical-toothed gear wheels are very accurately cut out of hard steel 
 by a machine specially designed for the purpose. The astern turbines 
 are arranged as in ordinary turbine practice, being inside the ahead 
 turbine casing, and fitted with separate steam connections, &c. 
 
 It may be pointed out that the geared down arrangement can be 
 adapted for either low or high ship speeds, but is not so necessary 
 at high speeds as it is at low speeds. The gearing down allows of 
 speeds of 10 or 12 knots with reasonable economy, whereas at these 
 speeds and direct turbine drives the economy would fall off for the 
 reasons mentioned previously. 
 
 The " Vespasian " was built in 1887 by Messrs Short Brothers, of 
 Sunderland. Her dimensions are: — Length on load water line, 
 275 ft. ; breadth, moulded, 38 ft. 9 in.; depth, moulded, 21 ft. 2 in. ; 
 mean loaded draught, 19 ft. 8 in., and displacement, 4350 tons. The 
 boilers — two in number — are 13 ft. diameter by 10 ft. 6 in. long, with 
 a total heating surface of 3430 sq. ft., and grate area of 98 sq. ft., 
 working under a pressure of 1 50 lbs. with natural draught. The 
 propeller is of cast iron, and has four blades, having a diameter of 
 14 ft., pitch 16-35 ft., and expanded area of 70 sq. ft. 
 
 Description of Geared Turbines, SS. "Vepasian." 
 
 The propelling machinery consists of two turbines in "series," 
 viz., one high-pressure and one low-pressure, the high-pressure 
 turbine being placed on the starboard side of the vessel and the low- 
 pressure on the port side. At the after end of each of the turbines 
 a driving pinion is connected, with a flexible coupling between the 
 pinion shaft and the turbine, the pinion on each side of the vessel 
 being geared into a wheel, which is coupled to the propeller shaft. 
 
 A reversing turbine is incorporated in the exhaust casing of the 
 low-pressure turbine. The air, circulating, feed, and bilge pumps 
 are of the usual design for tramp steamers, and are driven by means 
 jof a crank and connecting rod coupled to the forward end of gear- 
 wheel shaft. The turbine and pinion shaft bearings are under forced 
 lubrication, similar to ordinary turbine practice. The teeth of the 
 
66o 
 
 " Verbal " Notes and Sketches 
 
 pinions and of the gear wheel are lubricated by means of a "spray" 
 pipe extending the full width of the face of the wheel. Independent 
 oil pumps are fitted for supplying oil to the bearings and gear wheel, 
 with a view to the possibility of experimenting with different 
 lubricants for the gear wheel, the oiling system for the bearings being 
 separate from that of the gear wheel. 
 
 The high-pressure turbine is 3 ft. maximum diameter by 13 ft. 
 over all length, and the low-pressure 3 ft. 10 in. by 12 ft. 6 in. 
 length. The turbines are similar in design to a land turbine, being 
 balanced for steam thrust only, the propeller thrust being taken up 
 by the ordinary thrust-block of the horse-shoe type which is fitted aft 
 of the gear wheel. 
 
 The cooling surface of the condenser is 1165 sq. ft. 
 
 The gear wheel is of cast iron, with two forged steel rims shrunk 
 on. The diameter of the wheel is 8 ft. 3^ in. pitch circle, having 
 398 teeth — double helical — with a circular pitch of -7854 in. The 
 total width of face of wheel is 24 in. ; inclination of teeth 20" to 
 the axis. 
 
 The pinion shafts are of chrome nickel steel, 5 in. diameter 
 pitch circle, with 20 teeth -7854 circular pitch. The ratio of gear is 
 199 to I. 
 
 On the first four voyages careful measurements of water con- 
 sumption were taken. The following table gives the data and results 
 obtained on these voyages : — 
 
 Geared Turbines of SS. "Vespasian." 
 
 Results of First Four Voyages. 
 
 Date - - - - 
 
 9/6/10 
 
 1 6/6/ 10 
 
 1 6/6/ 10 
 
 22/6/10 
 
 22/6/10 
 
 22/6/10 
 
 29/6/10 
 
 Speed by log, knots - 
 
 9-35 
 
 9-22 
 
 10.58 
 
 9.61 
 
 9-27 
 
 10-22 
 
 9-37 
 
 Revs, per minute 
 
 65-0 
 
 64.9 
 
 73-0 
 
 64-8 
 
 63-85 
 
 70.6 
 
 62-9 
 
 Boiler pressure, lbs. 
 
 
 
 
 
 
 
 
 per square inch 
 
 '37 
 
 135 
 
 145 
 
 135 
 
 135 
 
 140 
 
 135 
 
 High-pressure turbine 
 
 
 
 
 
 
 
 
 (initial pressure, lbs. 
 
 
 
 
 
 
 
 
 per square inch) 
 
 86 
 
 86 
 
 121 
 
 86 
 
 86 
 
 III 
 
 81 
 
 Vacuum (in inches) - 
 
 28.5 
 
 29-1 
 
 28.6 
 
 .28-55 
 
 28.4 
 
 28.4 
 
 2S-3 
 
 Barometer - 
 
 30-01 
 
 30-5 
 
 30-52 
 
 29-9 
 
 29-9 
 
 29-88 
 
 29-6 
 
 Water, main engines 
 
 
 
 
 
 
 
 
 lbs. per hour - 
 
 12,140 
 
 12,300 
 
 15,680 
 
 11,890 
 
 11,730 
 
 14,510 
 
 11,100 
 
 Shaft horse- power 
 
 740 
 
 736 
 
 1,080 
 
 735 
 
 710 
 
 960 
 
 668 
 
 Water consumption, 
 
 
 
 
 
 
 
 
 lbs. per S.H.r. 
 
 i6'4 
 
 iS-o 
 
 14-5 
 
 l6-2 
 
 16-5 
 
 15-1 
 
 16-6 
 
 Geared Turbines of the "King Orry." 
 
 The machinery is on the twin-screw system, and includes two 
 high-pressure and two low-pressure turbines of the latest Parsons com- 
 bined impulse and reaction type. The arrangement of the turbines 
 and gear is shown on the two-page plate. The two high-pressure 
 turbines are in the centre, and the two low-pressure turbines, with 
 
.nsiaBqzdV i^nidiuT 
 
No. 13 —Geared Turbines, SS "Vespasian. 
 
 Plan of Engine Room and Stoke Hole. 
 
 [ To /{ux pa^ 660. 
 
Deing— nign-pressure lys^ to i and low-pressure 539 to i. iiie 
 circular pitch of the teeth is 0815 in., and the spiral angle 44° 2 i'. 
 
Deing — ftign-pressure i3-5« to i and low-pressure 539 to 1. ine 
 circular pitch of the teeth is 0815 in,, and the spiral angle 44° 2 i'. 
 
 k. 
 
No. 14. — Gear Wheels of "Vespasian's" Turbines. 
 
 (Cover removed. 1 
 
 {To J\uc /.ugc bbl. 
 
Appendix 66 1 
 
 which the astern turbines are incorporated, in the wings. The con- 
 ditions of the service demand ample astern power, and, in order to 
 provide for these requirements, this has been arranged to be not less 
 than 60 per cent, of the maximum ahead power. 
 
 The high-pressure rotors arc solid steel forgings, and bladed on 
 two diameters, 14 in. and 23 in. Three expansions of eleven rows 
 each are fitted on the smaller of these, and three expansions of 
 four rows each on the larger. The mean diameter of the blading 
 ranges from 1 ft. yi%; in. on the high-pressure end to 2 ft. 2| in. 
 at the other, in each turbine. As it is not possible to utilise the 
 propeller thrust to balance the steam thrust, owing to the presence of 
 the gear-box and its fittings, the whole of the steam thrust in this 
 type of turbine is designed to be taken on the dummies. As the rotor 
 is solid, equalising pipes are led from the end of the third expansion 
 to the forward side of the after dummy, and from the exhaust end to 
 the forward side of the forward dummy, thus keeping the rotor in a 
 practically floating condition axially. A small thrust bearing, as is 
 usual, is fitted at the forward end of each turbine to take the pressure 
 due to any variation in the speed. The arrangement is clearly shown 
 in the illustration. 
 
 The low-pressure turbines have six expansions of reaction blading 
 for going ahead, each having three rows of blades. The diameter of 
 the drum is 3 ft. i in., and the mean diameter of the blading ranges 
 from 3 ft. 3y^u in. to 3 ft. 7 j in. The astern turbines have each three 
 rows of impulse blading, followed by four expansions having four rows 
 each of reaction blading. The mean diameter of the impulse-wheel is 
 3 ft. 4 in., and in the case of the reaction blading the mean diameter 
 ranges from 2 ft. iiV in. to 2 ft. 4^ in. on a drum 2 ft. in diameter. 
 The low-pressure rotors are of the more usual hollow type, and there- 
 fore do not need the equalising pipes as fitted in the case of the high- 
 pressure rotors. 
 
 Each high-pressure turbine is designed to run at 2210 revolutions 
 per minute, and each low-pressure at 1617 revolutions per minute; 
 each is connected up with its pinion shaft through a flexible coupling 
 to correct any small want of perfect alignment. The gearing is of the 
 usual type, in two parts, with oppositely cut helices to neutralise end 
 thrust, and the pinion-shaft bearings are arranged in this case to be 
 of floating type with the object of equalising the pressures between 
 the working teeth, and preventing objectionable noise. The pinion 
 shafts, on which the teeth are cut from the solid, are of special 
 nickel steel, and the wheels into which they gear are of forged 
 steel. All these forgings were made at the Sheffield works of the 
 builders, and the gearing was cut by the Parsons Company. The 
 high-pressure pinions have thirty teeth, the low-pressure pinions forty- 
 one, and the wheels 221, the arrangement thus providing for the 
 essential hunting teeth. The ratios between turbines and propellers 
 being — high-pressure 13-58 to i and low-pressure 5-39 to i. The 
 circular pitch of the teeth is 0815 in., and the spiral angle 44° 2 i'. 
 
J^ 
 
ApjDendix 66 1 
 
 which the astern turbines are incorporated, in the wings. The con- 
 ditions of the service demand ample astern power, and, in order to 
 provide for these requirements, this has been arranged to be not less 
 than 60 per cent, of the maximum ahead power. 
 
 The high-pressure rotors are solid steel forgings, and bladed on 
 two diameters, 14 in. and 23 in. Three expansions of eleven rows 
 each are fitted on the smaller of these, and three expansions of 
 four rows each on the larger. The mean diameter of the blading 
 ranges from i ft. $-1% in. on the high-pressure end to 2 ft. 2] in. 
 at the other, in each turbine. As it is not possible to utilise the 
 l)ropeller thrust to balance the steam thrust, owing to the presence of 
 the gear-box and its fittings, the whole of the steam thrust in this 
 type of turbine is designed to be taken on the dummies. As the rotor 
 is solid, equalising pipes are led from the end of the third expansion 
 to the forward side of the after dummy, and from the exhaust end to 
 the forward side of the forward dummy, thus keeping the rotor in a 
 practically floating condition axialiy. A small thrust bearing, as is 
 usual, is fitted at the forward end of each turbine to take the pressure 
 due to any variation in the speed. The arrangement is clearly shown 
 in the illustration. 
 
 The low-pressure turbines have six expansions of reaction blading 
 for going ahead, each having three rows of blades. The diameter of 
 the drum is 3 ft. i in., and the mean diameter of the blading ranges 
 from 3 ft. 3/a in. to 3 ft. 7} in. The astern turbines have each three 
 rows of impulse blading, followed by four expansions having four rows 
 each of reaction blading. The mean diameter of the impulse-wheel is 
 3 ft. 4 in., and in the case of the reaction blading the mean diameter 
 ranges from 2 ft. lyV in. to 2 ft. 4^ in. on a drum 2 ft. in diameter. 
 The low-pressure rotors are of the more usual hollow type, and there- 
 fore do not need the equalising pipes as fitted in the case of the high- 
 pressure rotors. 
 
 Each high-pressure turbine is designed to run at 2210 revolutions 
 per minute, and each low-pressure at 1617 revolutions per minute; 
 each is connected up with its pinion shaft through a flexible coupling 
 to correct any small want of perfect alignment. The gearing is of the 
 usual type, in two parts, with oppositely cut helices to neutralise end 
 thrust, and the pinion-shaft bearings are arranged in this case to be 
 of floating type with the object of equalising the pressures between 
 the working teeth, and preventing objectionable noise. The pinion 
 shafts, on which the teeth are cut from the solid, are of special 
 nickel steel, and the wheels into which they gear are of forged 
 steel. All these forgings were made at the Sheffield works of the 
 builders, and the gearing was cut by the Parsons Company. The 
 high-pressure pinions have thirty teeth, the low-pressure pinions forty- 
 one, and the wheels 221, the arrangement thus providing for the 
 essential hunting teeth. The ratios between turbines and propellers 
 being — high-pressure 13-58 to i and low-pressure 5-39 to i. The 
 circular pitch of the teeth is 0815 in., and the spiral angle 44° 2 i'. 
 
662 " Verbal " Notes and Sketches 
 
 Each pinion-shaft is supported by three bearings of an aggregate 
 length of 3 ft. o^ in. by 5J in. in diameter, the width between the 
 teeth at each side of the centre bearing being 15^ in. The usual 
 thrust block for taking the thrust from the propeller is fitted im- 
 mediately aft of the gear-box, as may be seen from the engravings. 
 The whole of the gear is enclosed in an oil-tight casing, and lubrica- 
 tion arranged for by sprays designed to maintain a film of oil con- 
 tinually between the working surfaces of the teeth. Messrs B. R. 
 Vickers & Sons' patent frictionless stern-glands are fitted to the 
 propeller shafts to ensure that nothing in the way of preventable loss 
 may take place here. 
 
 The condensers are of the Weir " Uniflux " type, having steel 
 shells and cast-iron doors, and are guaranteed to maintain a vacuum 
 of 28^ in. with inlet water at 60' Fahr. Two of Messrs Weir's dual 
 air-pumps are fitted, 24 in. in diameter by 1 5 in. stroke, and the same 
 makers have supplied the main feed and forced-lubrication pumps. 
 The circulating water for the condensers is supplied by two of Messrs 
 Allen's 18-in. "Conqueror" centrifugal pumps, and they have also 
 supplied the two 6-ft. diameter forced draught fans, and the dynamo 
 and electric-light engine. The vessel is fitted with two bilge and 
 ballast pumps, a water service fresh-water pump, and a sanitary pump. 
 An exhaust feed-water heater is fitted for utilising the exhaust from 
 the auxiliary engines. 
 
 There are three boilers — two double-ended and one single-ended, 
 with a total collective heating surface of 14,385 sq. ft, and total 
 grate area of 383 sq. ft. The working pressure is 170 lbs., with a 
 closed stokehold system of forced draught. The removal of the ashes 
 from the stokehold is effected by two " Sentinel " ash-hoists, which 
 are fitted in the usual manner in the ventilators. A vertical auxiliary 
 boiler, by Messrs Cochran, of Annan, is installed to run the electric 
 light engine, &c., when the vessel is in port. 
 
 Very careful consideration has been given to the choice of speeds 
 for turbines and propellers, and it is confidently expected that the 
 arrangement will prove to be a highly efficient combination, showing 
 considerable economy in working compared with direct-driven types 
 workingf in similar vessels. 
 
^^^^ — ^ -. =- 
 
 ^ ^ -^ X O C O 13. O O^Vy-— 
 
 , V O f 1V»^ 
 
 [ 7(3 ;^a£-« /tff? 662. 
 
f, IS ll'Overall Length of Cyl':. . 
 
 EqvMJUxing Pipe 
 13 lOh Ot'craU Lerujth t-f Cytuiuie-r 
 
 No 15— Geared Turbines for the Isle of Man Twin-screw Steamer " King Orry/ 
 
 Constructed by Messrs Cammell Laird & Co.. Limited, Shipbuilders Birkenhead. 
 
 [ To lact pti^e 662. 
 
Appendix 
 
 66z 
 
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Appendix 
 
 663 
 
 A V ^ *^ ^ 
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 '-XI 
 
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 O 
 
No. 17.— Brown-Curtis Type Dovetail Reaction Blading. 
 
 (As fitted on Drum Stage.) Two blades and two packers shown. 
 
 E. Effective blade height. F. Width of groove opening at surface of drum. 
 
 G. Width of groove at bottom. H. Width of packers and blades. 
 
 Observe that the packers are bevelled away at the admission edges to reduce 
 blade tip leakage by deflecting the steam flow away from the blade tips. The 
 shroud rings of the reaction blading are flanged, and the flanges turned away 
 by machine to an actual "knife edge" sharpness at the tip. If, therefore, 
 the blades come into mechanical contact with the casing or rotor, bending over 
 or grinding away of the flange will, in most cases, be the limit of damage done to 
 the blading. The unequal expansion of the rotor and casing blading not being 
 correctly allowed for in the tip clearance, is a frequent cause of blade fouling. 
 
 O64 
 
No. l8.— Brown-Curtis Type Dovetail Impulse Blading. 
 
 (Two blades and three packers shown in plan.) 
 C. Depth of packer clear above drum and casing surface, 
 and intended to reduce tip leakage. 
 
 E. Effective blade height. 
 
 F. Width of groove opening at surface of drum. 
 
 G. Width of groove at bottom. 
 H. Width of packers and blades. 
 
 With impulse blading the shroud ring consists of a plain band as shown 
 above, the tip clearance allowed varying from -jV i"- ^° i "''■» ^^ ^^'^" more. 
 
 665 
 
666 
 
 Verbal " Notes and Sketches 
 
 Combined Impulse and Reaction Blading. 
 
 Parson's turbines are now generally fitted at the initial end with 
 a wheel and a set of impulse blading similar to that of the Curtis 
 turbine, the remainder of the blading being of the reaction type. 
 In some cases the astern turbines only are supplied with impulse 
 blading so as to allow of quick picking up of power when running 
 
 \r^^c\ 
 
 No. 19. — End View of Turbine Casing. 
 
 Showing Nozzle Control Valves. 
 
 astern. In other cases both reverse and ahead turbines are fitted 
 with impulse blading and wheel" at the first stage expansion, the 
 other expansions being of the usual reaction type blading. 
 
 Impulse blading has the advantage of allowing the full power to be 
 developed more quickly than is possible with reaction blading alone, a 
 point of considerable value in naval work. The steam is admitted to 
 the impulse wheel blades through expanding nozzles, the quantity being 
 regulated by means of hand valves, each one controlling a certain 
 number of nozzle openings. These area values are marked on the 
 hand wheels of the controlling valves. 
 
Appendix 
 
 667 
 
 Nozzle Box. 
 
 The nozzle plate forms a segment only of the turbine casing at the 
 top and does not, it should be noted, extend right round; the wheel is, 
 of course, complete and the impulse blades of the wheel also complete 
 the circle. It should, howev'er, also be noted that the impulse guide 
 blades which are fixed in the casing shell extend round the wheel circle 
 for the top half only. The nozzle box is bolted on to the end of the 
 turbine casing, and is fitted with a stop valve which admits steam to 
 the box, also with a number of hand controlling valves which allow the 
 steam to pass from the nozzle box to the nozzles, and so to the impulse 
 blades of the wheel. After expanding through the impulse nozzles 
 and blading, and dropping in pressure, the steam enters the first ex- 
 pansion of the reaction blading, which are very much less in height 
 than those of the impulse wheel. This will easily be understood, when 
 it is remembered that the nozzle openings only extend round the casing 
 for a very small part of the circumference, whereas the reaction blades 
 
 No. 20. — Nozzle Openings. 
 
 complete the circle, and in this way balance up the area of steam flow 
 at the reduced pressure. For given powers and speeds certain of the 
 control valves are opened, and at full power all may be opened up to 
 give full steam flow through the nozzle openings. Economy is there- 
 fore obtained at all powers, as the initial pressure is constant for all 
 nozzle opening areas, w^hether small or large in number. 
 
 Pressures. 
 
 After the steam passes through the impulse nozzles and blading 
 a considerable pressure drop takes place, and a corresponding 
 increase in steam velocity, and this change is allowed for in the 
 reaction blade expansions, which are designed accordingl}'. 
 
 Advantage of Impulse Blading. 
 
 The impulse blading, being much heavier and stronger than the 
 reaction blading, allows of greater steam flow when starting up without 
 risk of damage to blades, and results in a reduced steam pressure 
 admission to the first stage of the reaction blading of the turbine, which 
 is thus less subject to shock or vibration when steam is first turned on 
 for either ahead or astern. It will thus be evident that the maximum 
 steam pressures are exerted on the impulse blading only, the reaction 
 blading receiving the steam at greatly reduced pressure. 
 
668 
 
 " Verbal " Notes and Sketches 
 
 CURTIS TURBINES. 
 
 Ttie British Thomson- Houston Co. Ltd., Rugby, own the patent 
 for the Curtis steam turbine, which they have manufactured at their 
 Rugby works for a considerable time, and which they apply to their 
 electric generators. By the courtesy of the British Thomson- 
 Houston Co. Ltd., the author is enabled to reproduce the following 
 notes on turbines. 
 
 Impulse Turbine. 
 
 An impulse turbine is distinguished by the fact that the potential 
 energy of the steam is transformed into kinetic energy by expansion 
 of the steam through sjjecially shaped stationary nozzles. As a result 
 
 Row of 
 Moving Buckets 
 
 Stationary 
 h0Z2lc 1 
 
 No. 21. — Diagram of Simple Impulse Turbine. 
 
 of this the steam acquires great velocity, whereupon it is brought in 
 contact with suitable blades or buckets mounted on the periphery of 
 a wheel or wheels free to rotate, the buckets being shaped so as to 
 turn the issuing jet of steam gradually and without shock in a back- 
 wards direction. This is shown diagrammatically in No. 21. 
 
 The impact of the steam on the buckets results in the steam 
 giving up the whole or part of its velocity and consequent energy 
 to the buckets, thus causing rotation of the wheel. 
 
 It is sometimes argued that the velocity of the steam in an 
 imjDulse turbine is liable to cause damage to the moving buckets 
 through erosion, but this has been proved not necessarily to be the 
 case, as the buckets of Curtis turbines which have been running for 
 some years show on examination only the very slightest traces 
 of wear. 
 
Appendix 669 
 
 Principle of Impulse Turbine. 
 
 A mass which has been moving at a certain velocity will, in 
 coming to rest, give up the same amount of energy as was required 
 to give it the velocity it previously possessed. The object to be 
 attained in the design of an impulse turbine, therefore, is to arrange 
 the buckets so that they will bring the jets of steam issuing from the 
 nozzles to as near rest as possible, that is to say that the steam, after 
 passing through the buckets of the revolving wheel, shall possess no 
 motion and consequently no kinetic energy. 
 
 Best Bucket Speed. 
 
 It is easy to see that if a bucket is moving as fast as the steam 
 jet it will offer no opposition to the jet, nor will it extract any of 
 the velocity. 
 
 If, on the other hand, the wheel is so secured as to be immovable, 
 the steam jet will be directed backwards and will rebound from the 
 bucket with the same velocity with which it entered it, neglecting 
 friction in the bucket. 
 
 If, for the sake of example, however, the jet is assumed to be 
 travelling at the rate of 1000 ft. per second, and the bucket at 500 ft. 
 per second, then the steam will strike the bucket with a relative 
 velocity of 500 ft. per second, and on issuing from the bucket will 
 be directed backwards with a velocity relatively to the bucket of 
 500 ft. per second. 
 
 Since, however, the bucket is moving forward at the rate of 
 500 ft. per second, the backward velocity of the jet is equal and 
 opposite to the forward velocity of the bucket, so that the resultant 
 velocity of the steam relatively to a fixed point in space, as it emerges 
 from the bucket, is zero. The. emerging steam accordingly is inert, 
 having given up all its kinetic energy to the bucket. 
 
 It follows from this that for the best efficiency the buckets should 
 move at half the velocity of the steam jet. 
 
 As a matter of fact, steam when expanded from 1 50 lbs. pressure 
 per square inch to atmospheric pressure attains a speed of 2950 ft. 
 per second, while, if expanded into a 28 in. vacuum, it can attain 
 a velocity of 4010 ft. per second, or nearly twice the speed of a 
 modern rifle bullet, so that it is evidently impracticable to construct 
 a wheel which can run at half the velocity of such a jet. 
 
 Curtis Turbine. 
 
 The Curtis turbine, while utilising the principle of expanding the 
 steam through specially-shaped nozzles, has the great advantage that 
 it can be run with high efficiency at a relatively low speed. This is 
 accomplished in two ways, by means of — (i) "velocity stages," and 
 (2) " pressure stages." 
 
 45 
 
670 
 
 "Verbal" Notes and Sketches 
 
 Velocity Stages. 
 
 If a turbine such as just considered be run comparatively slowly, 
 the buckets on the rotating wheel will absorb less of the velocity of 
 the steam jet, but the steam emerging from the buckets will still 
 have considerable velocity and will be available for use over again. 
 
 If, therefore, the steam on emerging is redirected to a second row 
 of moving buckets fixed to the same wheel as the first row, it may be 
 
 No. 22. — Arrangement of Moving and Stationary 
 Elements in a Curtis Turbine. 
 
 compelled to part with its remaining velocity in the second row of 
 moving buckets. 
 
 This method of fractionall)' extracting the velocity of the steam,' 
 and known as a "velocity stage," is used to a differing extent in the 
 design of both Compound Impulse, and Combined Impulse, Curtis 
 turbines. 
 
 Steam entering the diverging nozzles (No, 22) at working pressure 
 is expanded during its passage through them, and issuing at great 
 velocity enters the first row of moving buckets. The steam leaves 
 these buckets in a backwards direction and enters the ring of 
 stationary buckets, in which it has its direction reversed, so that it 
 enters the second ring of moving buckets in the same direction as 
 at first. 
 
 I 
 
Appendix 67 1 
 
 The nozzles are designed so that practically all the potential 
 energy of the steam is converted into kinetic energy in the jet. In 
 other words the steam in passing through the nozzles is expanded 
 down to the pressure of the chamber or stage in which the wheels 
 are revolving, so that after leaving the orifice of the nozzle there is 
 practically no tendency for any further expansion, the steam acting 
 on the buckets in that stage simply by impact. 
 
 As a result of this action there is no appreciable difference of 
 pressure between the points of entrance and exit of the various rows 
 of buckets in a stage, and consequently no end thrust nor tendency 
 for the steam to leak across the clearance space, so that the moving 
 buckets of the Curtis turbine need no special minimum clearance 
 from the casing. 
 
 In the above respects the Curtis turbine shows the most marked 
 advantage over the reaction machine, as no compensating devices 
 for end thrust are required, and large bucket clearances are utilised 
 without loss of efficiency. 
 
 Pressure Stages. 
 
 It is obvious from the description just given that any degree of 
 expansion, with its resulting steam velocity, can be dealt with in one 
 pressure stage by providing a sufficient number of rows of buckets or 
 " velocity stages " to bring the speed of rotation down to a practicable 
 limit. 
 
 This method, however, if pushed to an extreme, becomes inefficient, 
 due to steam friction losses, and so another method of subdividing 
 the steam energy is also utilised in the Curtis turbine. Instead of 
 expanding the steam from boiler to exhaust pressure in one step, 
 this operation is divided over two or more sections or " pressure 
 stages." 
 
 The multi-stage machine can be best understood by imagining 
 a complete turbine to consist of a number of smaller turbines placed 
 in series. The distribution of steam pressure is regulated by the 
 size of the exhaust opening in each section, which opening usually 
 forms the nozzles for the succeeding section. No. 23 represents 
 a four-stage turbine, and clearly shows how the machine is divided 
 up into four sections or stages by means of steam-tight diaphragms, 
 which also carry the nozzles. 
 
 Each set of nozzles is designed to utilise one quarter of the total 
 energy in the steam during expansion from the boiler down to the 
 exhaust pressure. This being so, a relatively low velocity is 
 imparted to the steam jet in each stage, which in turn permits of 
 a comparatively low speed of rotation of the wheels. 
 
 The steam, after leaving the last row of moving buc"kets in the 
 first stage, has had nearly all of its velocity extracted, but on passing 
 through the nozzles in the diaphragm separating the first and second 
 stages it is again expanded and the same velocity as before imparted 
 to it. This occurs again in the third and fourth stages, the steam 
 
672 
 
 " Verbal " Notes and Sketches 
 
 finally emerging from the latter at the pressure of the exhaust, 
 having given up practically all the energy it previously possessed 
 
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 when in the boiler. It will be noted that the nozzles and buckets of 
 the successive stageshave to be made gradually larger to deal with 
 the increase in volume of steam resulting from each expansion. 
 
Appendix 6^^ 
 
 The simplest form of multi-stage machine is found in the simple 
 Impulse Turbine, which consists of a number of pressure stages 
 having but one row of moving buckets in each stage. 
 
 Curtis Compound Impulse and Combined Impulse Turbines. 
 
 To obtain the highest efficiency necessitates the proper blending 
 of " velocity steps " (number of rows of buckets per stage) with 
 " pressure steps " (number of stages.) These conditions have received 
 the most careful consideration in the design of the Curtis machine, 
 hence the adoption by the British Thomson-Houston Co. of the two 
 main types of turbines, viz., the Compound Impulse and the 
 Combined Impulse machines. The choice of type employed in any 
 instance is determined by the conditions to be met. 
 
 The difference between the two lies in the fact that in the 
 Compound Impulse turbine there are two or more rows of moving 
 buckets in each stage of the machine, while in the Combined Impulse 
 turbine there are two rows of moving buckets in the first stage, but 
 only one row in each of the following stages. 
 
 The Compound Impulse turbine, as a consequence, is a type 
 possessing few stages and is very short in length. The Combined 
 Impulse turbine, requiring as it does a greater number of stages than 
 the Compound Impulse machine, is longer over all. In the larger 
 sizes, under certain steam conditions, the Combined Impulse turbine 
 offers better economy than the Compound Impulse machine. 
 
 In the Compound Impulse turbine in the first stage the pressure 
 drop is much greater in proportion to the kinetic energy developed 
 than in the second stage, whilst in the third and fourth stages thy 
 pressure drop decreases, although producing the same kinetic energe 
 as in the second stage. In the fifth stage, whilst the energy liberated 
 is nearly as great as for the three previous stages, the pressure drop 
 here is insignificant. This shows indirectly how an increase in 
 vacuum {i.e., a drop in back pressure) adds so rapidly to the amount 
 of energy available per lb. of steam. 
 
 In the Combined Impulse turbine the pressure drop in the first 
 stage is also greater in proportion to the kinetic energy liberated 
 than in the succeeding stages ; but the kinetic energy liberated 
 in the first stage is very much greater than in the stages which follow. 
 In fact this is the peculiarity of the Combined Impulse turbine, and 
 under certain conditions it is conducive to economy. 
 
 Construction. 
 
 In No. 24 is shown a longitudinal section of a large high pressure 
 li-stage Curtis Combined Impulse turbine. The steam, passing 
 through the valve chest shown at the top left-hand side, proceeds 
 down the passage to the nozzle plate, and expanding through the 
 nozzles enters the moving and fixed rows of buckets of the first 
 stage. This stage comprises a single wheel having two rows of 
 
674 
 
 "Verbal" Notes and Sketches 
 
 buckets with a row of fixed intermediate blades between. From the 
 first stage the steam passes through the expanding nozzles in the 
 
 dish-shaped diaphragm and enters the buckets of the second stage. 
 From the second stage the steam passes to the nozzles and buckets 
 of the third stage, and so on through the succeeding stages, finally 
 
Appendix 675 
 
 exhausting through the opening at the bottom right-hand side of the 
 casing. The second and successive stages all contain wheels with 
 a single row of buckets. 
 
 A great advantage of the Curtis turbine lies in the fact that, after 
 expansion through the nozzles at the high pressure or governing end 
 of the turbine adjacent to the main bearing, the temperature and the 
 pressure of the steam are very much reduced. 
 
 As a result the steam sealing glands, the end cover, and the main 
 bearing at the high pressure end of the turbine are not subject to the 
 excessive temperatures and pressures found in turbines of other types. 
 
 Some Advantages of B.T.H. Curtis Turbines. 
 
 A feature of the greatest importance in connection with the Curtis, 
 as compared with the reaction turbine, is that the buckets at the inlet 
 end are not subjected to the effects of steam at high temperature. In 
 expanding through the first set of nozzles the steam temperature falls 
 considerably, so that no risk of damage to the buckets arises, even 
 when using steam superheated to the highest degree. 
 
 One of the most important advantages of the Curtis turbine is 
 that in the event of a quantity of water coming over from the boilers 
 with the steam, there is little danger of stripping the blades or other 
 damage. 
 
 Curtis turbines can be started up promptly from a cold condition 
 without danger from accumulation of condensed steam, or fear of 
 distortion due to change of temperature of the casing. 
 
 As compared with the reaction turbine, the Curtis machine shows 
 to great advantage in the matter of temperature fluctuation. 
 
 It is not always possible to keep the steam pressure and superheat 
 constant, and when these fluctuations occur they are, in the case of 
 reaction machines, transmitted direct to the turbine. 
 
 These changes, however, are of small importance in the Curtis 
 turbine, owing to the expansion of the steam in the first set of nozzles, 
 in which the fluctuations of pressure and temperature are damped 
 down before the steam enters the turbine proper. Thus there is not 
 the same tendency for mechanical distortion in the Curtis as is present 
 in the reaction machine. 
 
 In the Combined Impulse turbine, the first wheel with a double- 
 row of moving buckets takes the place of the first three wheels in a 
 simple impulse turbine, and the advantages gained are as follows : — 
 (i) The density of the steam surrounding the single compound 
 wheel is about two-thirds of the mean density of the steam 
 surrounding the three single-row wheels, causing the compound 
 wheel to have only about one-third the rotation losses of the 
 latter wheels. 
 (2) The lower stage pressure associated with the single compound 
 wheel causes less leakage of steam through the diaphragm and 
 end packing. This leakage is further reduced by the fact that, 
 as compared with the simple impulse machine, the Curtis 
 turbine requires fewer stages and so is shorter in length. This 
 
676 
 
 "Verbal" Notes and Sketches 
 
 enables a smaller shaft diameter to be used than is possible 
 with a longer machine, and so offers a considerably reduced 
 area for steam to leak through the diaphragm packing. 
 (3) It is possible in the Combined Impulse turbine to obtain 
 overloads without by-passing the first stage. In a Simple 
 Impulse Turbine, unless the energy drop through the first 
 wheel is very large, it is not possible to obtain overloads 
 without by-passing, so that whether the method adopted is to 
 allow an abnormal energy drop or to by-pass the steam, the 
 result is loss of efficiency. 
 
 The design of the Curtis turbine allows ample room for substantial 
 wheel bosses, as well as for efficient diaphragm packings. A sound 
 
 -NOZZLE 
 
 No. 25. No. 26. 
 
 Relation of Fixed and Moving Buckets in Curtis 
 Turbines. 
 
 mechanical construction is therefore possible, (i) entirely obviating 
 danger from the bucket wheels opening at the boss and becoming 
 slack upon the shaft due to centrifugal force, and (2) effectually 
 preventing leakage of steam from one stage to another. 
 
 Provision for Decreased Velocity of Steam. 
 
 It will be seen in No. 22 and No. 24 that the successive rows of 
 buckets in any given stage differ in length one from another. No. 25 
 shows diagramatically and on a larger scale the relation of moving 
 and stationary buckets in any one stage of a Curtis compound 
 impulse turbine. This figure also represents the first stage of a 
 combined impulse turbine, while the succeeding stages are as shown 
 in No. 26, Referring to No. 25, A and C are the moving and B the 
 stationary lines of buckets respectively. It might be assumed that 
 the divergence of the bucket area as shown is to provide for expan- 
 
Appendix 
 
 677 
 
 sion, and consequently increasing volume per unit weight of steam. 
 This, however, is not exactly the case. 
 
 Steam enters A at a higher velocity than it leaves C. During its 
 passage a continuous fall in velocity takes place, so that an increas- 
 ingly wider passage and consequently longer buckets are necessary to 
 accommodate the steam as it gradually moves more slowly. 
 
 This action may be compared with the flow of a non-expansive 
 fluid such as water through a funnel-shaped tube. If the tube be 
 filled with water moving from the smaller to the larger end, the 
 
 No. 27.— Diagram showing Adiabatic Expansion of Steam. 
 
 velocity will be high at the entrance, but relatively low at the discharge 
 end. Thus the velocity of the liquid drops considerably, but without 
 expansion or increase in volume. 
 
 Expansion of Steam. 
 
 It is a fact not generally realised that the energy liberated by 
 the expansion of a given weight of dry steam depends upon the 
 number of times that the original volume is increased, or upon 
 the ratio of the pressure drop, rather than the actual pressure drop. 
 For example, a pressure drop from 30 lbs. down to 15 lbs. absolute, 
 liberates very nearly the same amount of energy as a pressure drop 
 from 200 lbs. to 100 lbs. The pressure ratio is the same in both 
 cases, but the pressure difference is very much greater at the higher 
 pressures. 
 
 In No. 27 the curve represents diagrammatically the adiabatic 
 expansion* of i lb. of dry steam from 200 lbs. down to 10 lbs. absolute, 
 
 * Expansion without loss or gain of heat to or from surrounding bodies. 
 
678 " Verbal " Notes and Sketches 
 
 and is limited only by lack of space from continuing the process 
 further. The steam pressure is measured vertically, and the volume 
 horizontally from the point O, so that the area of the diagram (which 
 is the product of its length and average height) is proportional to the 
 energy developed, this being the product of pressure by change of 
 volume. 
 
 The volume occupied by one pound of dry steam at 200 lbs. 
 absolute pressure is 2-288 cubic feet, which is represented by the 
 position of the letter H in the diagram. If now the steam is 
 expanded down to 100 lbs. (C) the volume will be increased to the 
 point J, i.e., by 84 per cent., and the amount of energy liberated, 
 assuming the back pressure to be zero, will be denoted by the shaded 
 areaBCJH. 
 
 In the same way the area EFLM shows the work done by the 
 expansion of the steam from 30 to 15 lbs. This area is less than the 
 area BCJH, but is not nearly as much reduced as the pressure drop 
 has been reduced. The fall of pressure in the first case is 100 lbs., 
 whereas in the latter case it is only 15 lbs. The process of halving, 
 the pressures, etc., can still be continued, and it can be shown that 
 the adiabatic expansion of i lb. of steam from 2 lbs. to about 064 
 lb. absolute, i.e., from a vacuum of approximately 26" to one of 287" 
 of mercury (with barometer at 30"), liberates just as much energy as 
 the expansion of the same weight of steam from 200 lbs. to 100 lbs. 
 absolute. 
 
 As a matter of fact, in the steam turbine expansion takes place in 
 accordance with a curve which lies slightly higher than the adiabatic 
 curve, so that there is actually more energy liberated in the lower 
 expansions than is shown in No. 27. The point at issue, however, 
 will be clear, namely, that a very large amount of energy is available 
 in steam at low pressures. 
 
 Unsuitability of the Reciprocating Engine for Low Pressures. 
 
 The volumes of steam corresponding to the low pressures just 
 mentioned are very great, and for this reason reciprocating engines 
 cannot be adapted to accommodate them. The mechanical difficulties 
 presented by the undue size of the low pressure cylinders and valve 
 gear necessary preclude any advantage being realised with a vacuum 
 higher than 26". 
 
 Suitability of the Turbine for Low Steam Pressures, 
 
 Turbines, however, due to their inherent design and the absence 
 of slide valves and ports, together with the fact that in them the steam 
 is constantly in motion, can be designed to accommodate very large 
 volumes of steam at the lowest pressures, without entailing any great 
 increase in cost. 
 
 For this reason turbines can be used to great advantage for 
 running on the exhaust steam from reciprocating engines or other 
 steam using devices, and extracting thereby a very considerable 
 amount of the energy in the steam by expanding it down to the 
 lowest practicable limit. 
 
Appendix 
 
 679 
 
 No. 28.— Blades and Caulking Groove. 
 
 (Curtis Turbine.) 
 
 r. Groove in rim of impulse wheel. 
 
 2. Opening for insertion of blade packing pieces. 
 
 3. Blade (with undercut root). 
 
 4. Packer. 
 
 5. Top edge of packer. 
 
 The types of blades shown are fixed by means of "circumferential" caulk- 
 ing in place of " radial " cauikmg, and the enlarged opening (2) is closed up 
 after the blades and packers are all assembled by a closing key or caulking 
 piece which is hammered down and locked in place. 
 
 Note. — The blades can be entered in the grooves by turning them 
 sideways, but the packers can only be entered by means of the specially cut 
 opening (2). 
 
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 680 
 
jUgMB. u^a THRut^T 
 
 
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 O LBS 
 
 NOZZLE CONTROL 
 VALVES 
 
 Reaction Turbines 
 
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 CONDENSER 
 
 
 
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 No. 30— Parsons Type Combined Impulse and Reaction Turbines. 
 
 With Average Pressures from Practice. 
 
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 No. 31.— Port Turbines and Gear Wheels, TSS. "Tuscania. 
 
 Pressure Lquali^atm, 
 Flexible coupling. 
 
 1. H.P. Turbine steam. 
 
 2. H.P. exhaust to L.P. through strainer. 
 
 3. H.P. exhaust direct to condenser. 
 
 4. L.P. ahead steam. 
 
 5. L.P. astern steam. 
 
 6. Control valve to astern impulse nozzles. 
 
 7. Auxiliary exhaust steam. 
 S. Strainer. 
 
 14, 
 
 H.P. turbine pinion wheel. 
 
 L.P. 
 
 Thrust block. 
 
 iVoC,'.— Astern Turbine.— The nczzle control valve shown is only 
 intended to be used in cases of emergency, as the main mancuuvring 
 valves give steam direct to the stern turbine for about half the astern 
 power available, but if extra power for astern rinining is required, 
 the nozzle control valve can also be opened by hand, and this 
 admits an additional head of steam to the astern blading for the 
 ma.ximum astern power available. 
 
 {'1 face page 680. 
 
Appendix 
 
 68 1 
 
 ^(£<im' 
 
 Wi'CclJiMUr/t. Stearrd to L.P.J 
 
 101- ^ 
 
 P. Ahead, Steam Co H.BAfiead. 
 (Emergency) 
 
 1-3'. ^ 
 
 No. 32.— Manoeuvring- Valves. 
 
 ' ' Transylvania " and ' ' Tuscania. " 
 One hand wheel controls boiler steam to the ahead and astern 
 turbines. The slotted lever shown acts to lock the gear and so 
 prevent steam from passing to ahead and astern turbines at the 
 same time. Boiler steam direct to L.P. ahead turbines is also 
 arranged for as shown. A throttle valve connected up to the 
 turbine governors is fitted in the inlet branch of the chest. 
 
Appendix 
 
 68 1 
 
 5- r 
 
 t 
 
 i 
 
 —101 
 
 ^(eam' to L J*. Astern 
 
 . Steam) to L.P.J 
 
 loi- 
 
 P.Ahecui Stednh to H.P.Ahecul 
 {Emergency) 
 
 ,^.7j: ^ 
 
 No. 32.— Manoeuvring- Valves. 
 
 "Transylvania" and "Tuscania." 
 One hand wheel controls boiler steam to the ahead and astern 
 turbines. The slotted lever shown acts to lock the gear and so 
 prevent steam from passing to ahead and astern turbines at the 
 same time. Boiler steam direct to L.P. ahead turbines is also 
 arranged for as shown. A throttle valve connected up to the 
 turbine governors is fitted in the inlet branch of the chest. 
 
682 "Verbal" Notes and Sketches 
 
 Practical Operation of Turbine Machinery 
 
 Heating up. 
 
 The matter of warming up the turbines previous to starting is 
 of vital importance, and should receive special attention from the 
 engineers in charge. 
 
 1. Start running of the circulators and air pumps, and admit 
 heating steam at about lo lbs. pressure right through the turbines 
 to the condensers, after first getting rid of the heated air from the 
 boilers, etc. 
 
 2. Uniform heating of all parts should be aimed at, and during 
 this process (for which about six hours should be allowed) the rotor 
 should be moved round slowly by the turning gear for quarter turn 
 every thirty minutes. 
 
 3. During heating up the various clearances should be carefully 
 read and noted down. The turbine drains should be opened to get 
 rid of condensed water, which, if allowed to remain, might result in 
 blade stripping when starting up. 
 
 4. The pipe lines ahead and astern should also be heated up 
 gradually by opening up the steam admission valves of same. 
 
 5. The forced lubrication system should be tested by running the 
 oil to flood up the bearings, and then trying the test cocks on the 
 main bearings for oil flow through each. 
 
 6. Note. — In some steamers a rather ingenious tell-tale arrange- 
 ment is fitted which indicates when the oil flow is checked in the 
 turbine bearings. The action is as follows : — The oil flow from the 
 turbine bearings passes through a small float tank in which a metal 
 float moves vertically on a small spindle. When the oil flow falls 
 below a certain level, the float in dropping makes contact with a 
 metal stop below, and by means of a bell battery and connection 
 starts the ringing of a small alarm bell, thus indicating to the engineer 
 on watch that the oil service is at fault. 
 
 7. Steam should also be turned on to the steam glands until the 
 required pressure shows on the gauges. 
 
 8. In testing the turbines give steam to ahead for a few revolutions, 
 then shut off" and give steam to astern for a few revolutions. 
 
 9. Previous to reporting " ready " take dummy clearance. 
 
 10. Whenever possible work up to full power by degrees only. 
 
I 
 
 Appendix 683 
 
 11. When running up to speed required set gland steam and 
 drains, the latter at minimum opening, as any excess opening means 
 leakage. 
 
 12. Previous to getting under way start up oil pumps and obtain 
 required pressure of oil (this varies from 15 lbs. to 30 lbs.). Examine 
 sight glass for oil flow through bearings. (The sight glasses men- 
 tioned, unfortunately, soon become dirty and unreliable.) 
 
 13. When running astern be careful to take dummy clearance and 
 make record of same. The dummy clearance is affected by the 
 following : — 
 
 (a) Unequal expansion of rotor and casing. 
 
 (d) Amount of rotor " float " allowed for oil film at thrust. 
 
 (c) Effect of thrust pressure forward and steam pressure aft, 
 and which varies under different speed or power con- 
 ditions. 
 
 14. When running at any required speed or revolutions, it is best 
 to open the minimum number of nozzle valves which will give 
 sufficient steam for the purpose at the maximum boiler pressure. 
 
 It is bad practice to open more valves than actually necessary, and 
 then reduce the pressure by throttling to keep down the speed or 
 power to the required figure. 
 
 15. In changing speed or reversing it is advisable to work up or 
 work down to the power and speed required gradually, so that the 
 risk of accident due to sudden expansion or to sudden contraction of 
 the rotor or casing may be eliminated. 
 
 16. For quick emergency stopping of the turbines when running 
 ahead, steam can be admitted to the reverse end. 
 
 17. For any given number of nozzle valves open, the main steam, 
 vacuum, and gland pressures should be noted. This will afford a 
 guide to the operation of the turbines. 
 
 18. To allow for quick emergency changes from ahead to astern 
 the dummy clearances should not be kept too fine. 
 
 19. All impulse nozzles in use are best to be kept full open, and 
 all not in use tight shut. 
 
 20. A record should be kept of the revolution speed obtained by 
 various nozzle openings. This is important. 
 
 21. With Curtis turbines the gland steam seals are worked at a 
 pressure of about 3 lbs. Take accurate records of the oil temperatures 
 when entering and leaving the main bearings, the maximum of which 
 should not exceed about 130° Fahr. 
 
 22. The main bearing at initial end of turbine requires most 
 attention, as the highest temperature exists there. 
 
684 "Verbal" Notes and Sketches 
 
 23. The importance of the gland steam seal on the L.P. and 
 astern turbines should not be overlooked. 
 
 24. The efficiency of turbine machinery depends principally on 
 the following : — 
 
 (a) High pressure at initial end. 
 
 (d) Vacuum in condenser end, and in idle turbines. 
 
 (c) Fine blade tip clearance. 
 
 (cT) Tightness of glands against steam leakage out, and 
 against air leakage in. 
 
 (e) Closed exhaust system. 
 
 It should be noted that leaky L.P. glands allow the admission 
 of air, and therefore produce a reduced vacuum in the condenser. 
 
 25. When standing by after stopping, stop oil pumps, slow down 
 circulating pump, and open heating up steam to turbines, to prevent 
 cooling down and contraction of the working parts ; also open drains 
 from turbines. 
 
 26. Running ahead under closed exhaust system the auxiliary 
 exhausts are usually led to the third expansion of the turbine, but 
 when running astern or manoeuvring the auxiliary exhausts require 
 to be led to the condenser. 
 
 27. Turbine oil only is suitable for forced lubrication, as under 
 pressure ordinary engine oil tends to form an emulsion. 
 
 28. The steam strainers require to be examined and cleaned at 
 regular intervals. 
 
 29. The oil cooling service pipes, strainers, and other connections 
 require regular attention. 
 
 30. After lifting turbine top half casings for examination, cleaning, 
 or repair, before replacing same make careful examination for any 
 articles left behind, such as chisels, hammers, loose blades, or packers, 
 also turn rotor round slowly and examine closely for loose binding 
 wires on the blading. The neglect of this has in many cases led to 
 damage due to blade stripping, etc., when under way again, as in this 
 respect turbines are by no means " fool-proof" 
 
 31. A record should be kept of the blade tip clearances, the 
 blade side clearances, and, most necessary of all, of the dummy 
 clearance, taken "cold," "heating up," and when "running" ahead 
 and astern 
 
 32. Blade stripping is often caused by water : it is therefore 
 important that any tendency towards boiler priming should be 
 carefully guarded against. Defective drainage will also act in the 
 same way. 
 
Appendix 685 
 
 The Weir "Dual" Air Pump. 
 
 The duty of an air pump is to take from the condenser a mixture 
 of air, water, and vapour ; and to obtain economical working, this 
 should be done at the highest possible temperature. If a single 
 pump is used to handle this mixture, the hotwell temperature for a 
 given vacuum is dependent on the amount of air leakage and the air 
 pump capacity. Consequently, with a single air pump the tempera- 
 ture of the mixture must be a considerable degree colder than the 
 theoretical temperature due to the vacuum. 
 
 By the use of separate pumps handling the air and water, the dry 
 pump having a cold injection non-returnable to the feed, the above 
 conditions are changed, and higher thermal efficiency is rendered 
 possible. 
 
 This method enables the wet (or water) pump to handle water at 
 approximately the steam temperature, while at the same time the dry 
 pump will deal with the air and vapour at the volume and temperature 
 conditions imposed by the temperature of the injection water. 
 
 With the " Dual " pump the above advantages are obtained, 
 together with increased efficiency of the dry pump, due to its 
 contents being densified or decreased in volume through cooling by 
 the injection water, which circulates continuously, never leaves the 
 system, and is never subjected to atmospheric pressure with con- 
 sequent aeration. The dry air pump further works only at less than 
 half the pressure range, as it discharges below the head valves of the 
 wet pump. The apparatus, moreover, is compact, self-contained, and 
 of good mechanical design. 
 
 Description. — No. i shows in a diagrammatic form the arrange- 
 ment of Surface Condenser, " Dual " air pump, and injection water 
 cooler. In all cases the pump A or wet pump is situated below the 
 steam cylinder, as this pump is the only one which works under any 
 considerable load ; the dry pump B is driven by the beam and links 
 in the usual manner. One connection C is made to the condenser, 
 but a branch pipe is led to the dry pump, the connection being made 
 in such a manner that the water will all pass by C to the wet pump. 
 Both pumps are generally of the three-valve marine type, but in 
 certain cases the dry pump may be of the suction valveless type. 
 
 The first and most important difference from an ordinary twin 
 pump consists in the dry pump discharging through the return pipe 
 E, through a spring-loaded valve F, into the wet pump at a point 
 below its head valves. The next point concerns the supply of water 
 to the dry pump for water sealing, clearance filling, cooling, and 
 vapour condensing. When starting the pump the filling valve G 
 must be opened for a minute or so to enable the vacuum to draw in 
 ^6 
 
686 
 
 "Verbal" Notes and Sketches 
 
 a supply from the hotwell of the wet pump. The valve is then 
 closed, and the water passes from the hotwell of the dry pump by the 
 pipe H to the annular cooler, and after being cooled passes into the 
 suction of the dry pump, then, passing through the pump, it becomes 
 heated and again passes to the cooler, and so on in a continuous 
 
 jaro^'uaw^ P"=^ 
 
 closed circuit, any excess passing over the pipe E to the wet pump. 
 The spring-loaded valve F is adjusted to maintain about 20 in. 
 vacuum in the dry pump hotwell when the condenser is working at 
 28 in. vacuum, and this 8 in. difference of pressure is sufficient to 
 cause the water to overcome the cooler friction and pass into the 
 
THE WEIR "DUAL" AIR PUMP. 
 
 " X'erljal " Notes and Sketchts. 
 
 [ To face page 686. 
 
Appendix 
 
 687 
 
 suction, and at the same time never allow any direct air connection 
 between the dry suction and discharge. 
 
 Operation of Three-Wire System. 
 
 The generators of this system consist of an ordinary direct current 
 machine with two or more slip rings on the armature shaft extending 
 as shown in the sketch. These slip rings are connected to the arma- 
 ture winding in such a manner as to give single phase in the case of 
 two slip rings, three phase in the case of three slip rings, and two 
 phase in the case of four slip rings. 
 
 r 
 
 Balance Colls -% 
 
 Collector 
 
 
 Armature 
 
 No. 3.— Three-Wire System. 
 
 (With Single Dynamo.) 
 
 The slip rings are also connected through the brushes to one 
 or more auto-transformers or balance coils, the middle or neutral 
 point of the balance coils constituting the mid point of the direct 
 current circuit. 
 
 The sketch shows diagrammatically a two-pole direct current 
 armature. The direct brushes are shown as bearing on the com- 
 mutator, and the four slip rings are connected to points on the 
 armature diametrically opposite. An alternating voltage appears at 
 
688 "Verbal" Notes and Sketches 
 
 the slip rings, having a frequency equal to the number of poles 
 multiplied by the speed. Thus a four-pole generator running at 
 3000 revolutions per minute would have 12,000 alternations per 
 minute = 100 periods per second. 
 
 The balance coil is simply an alternating current transformer with 
 a single winding, and a tap from the middle point, and since it is 
 connected to an alternating current circuit, an alternating magnetising 
 current will flow through its windings ; but as this magnetising 
 current is ordinarily very small, it may be neglected when considering 
 the flow of the direct current from the neutral wire to the armature 
 windings. 
 
 Thus, under ordinary conditions, the only current in the coil which 
 need be considered is direct current. 
 
 The object of the balance coil is to give a point midway between 
 the direct current brushes to which the neutral wire of the system 
 may be connected, and to afford a path by which the current flowing 
 in the neutral wire may pass through the armature to one of the 
 main brushes. 
 
 It will be seen from the diagram that this system is very valuable 
 where it becomes necessary to have electric lighting on a low voltage, 
 and heavy driving power from the outers or high voltage. 
 
 An out of balance load up to 15 per cent, may safely be carried 
 between one outer wire and the neutral wire. 
 
 Knocking in Engines. 
 
 Knocking may be caused as follows : — 
 
 1. Want of clearance in cylinder, top or bottom ; if on bottom, 
 
 due perhaps to wear down. 
 
 2. Slack guide shoes. 
 
 3. High compression forcing slide valve off face at end of 
 
 stroke. 
 
 4. Loose piston rod nut. 
 
 5. Loose crosshead nut. 
 
 6. Worn top end brass or bottom end brass. 
 
 7. Water in cylinder due to priming. 
 
 8. Want of compression (remedy — shut in link). 
 
 9. Junk ring pins slackening back, or working out altogether. 
 10. Worn valve gear brasses, &c. 
 
 Diagram cards, if taken off at the time, would indicate causes i, 3, 
 7, and 8 ; for the others endeavour to locate position of knock, whether 
 internal or external. 
 
 If the knocking is due to priming, this will further show by 
 slowing down of the engines as the steam supply is reduced by the 
 water passing over with it from the boilers. 
 
Appendix 
 
 689 
 
 £ng^ine Data. — The following data referring to the machinery of a 
 modern twin screw meat-carrying steamer may be studied with 
 advantage by the student, as a good idea of the relative proportions 
 of the various working parts can be obtained by reference to the 
 data supplied. 
 
 Twin Screw Steamer, I.H.P. (Combined) 5000. 
 
 Cylinders 
 
 - 
 
 25, 42, 69 in. (2 off). 
 
 Stroke 
 
 - 
 
 - 4 ft. 
 
 Crank shaft 
 
 - 
 
 13I in. diameter. 
 
 „ pin 
 
 - 
 
 - 131 
 
 Length of crank pin 
 
 - 
 
 14 in. 
 
 Condensing surface 
 
 - 
 
 6000 sq. ft. (?). 
 
 Thrust surface 
 
 - 
 
 - 1324 (2). 
 
 Piston rods 
 
 - 
 
 6 2 in. diameter. 
 
 Connecting rod - 
 
 - 
 
 6| and "j} in. diameter. 
 
 „ cent 
 
 res - 
 
 - 8 ft. 6 in. 
 
 Valve rod, diameter in gland 
 
 - 3f i»- 
 
 Main steam pipe 
 
 
 8 in. diameter. 
 
 Propellers (2) 
 
 - 
 
 j 1 6 ft. 7 A in. diameter. 
 ( 20 ft. pitch. 
 
 Expanded area 
 
 - 
 
 - 68-8 sq. ft. 
 
 Projected „ 
 
 - 
 
 - 53-5 sq. ft. 
 
 Blades - 
 
 - 
 
 - 4' 
 
 „ thickness at root 
 
 - 6^ in. 
 
 J) )> 
 
 top 
 
 - h in- 
 
 Boss 
 
 
 Cast iron. 
 
 Blades - 
 
 
 Manganese bronze. 
 
 Studs 
 
 
 Mild steel. 
 
 Nuts 
 
 
 Gun metal. 
 
 Shaft nut - 
 
 
 Mild steel. 
 
 Boilers 
 
 
 5 single-ended, 15 ft. 6 in. 
 by 1 1 ft. 6 in. 
 
 Pressure - 
 
 
 180 lbs. 
 
 Tube surface 
 
 
 11,508 sq. ft. 
 
 Heating surface - 
 
 
 13.560 „ 
 
 Grate area 
 
 
 - 295 
 
 Tubes - 
 
 
 8 ft. 2 in. and 8 ft. i-^'^- in. 
 
 „ diameter - 
 
 
 2| in. 
 
 Length of fire bars 
 
 
 5 ft. 6 in. 
 
 Furnaces - 
 
 
 3 ft. 7 in. diameter. 
 
690 
 
 " Verbal '* Notes and Sketches 
 
 Stop Valves. 
 
 Boiler Stop Valve, i\ in. Diameter. 
 
 1 
 
 Inches Open. 
 
 Number of Turns of 
 Hand Wheel. 
 
 Steam .Speed. 
 (Feet per Second.) 
 
 \ in. 
 
 8 " 
 
 3 
 
 2i 
 
 2 
 
 185 
 
 231 
 
 Engine-room 
 
 Stop P'alve [balance 
 
 </), 8 in. Diameter. 
 
 2\ in. 
 
 lU 
 
 90-6 
 
 2 „ 
 
 i6\ 
 
 95-2 
 
 T 3 
 
 4 " 
 
 14 
 12JL 
 
 IOO-2 
 II7-3 
 
 li . 
 
 lol 
 
 140-5 
 
 Pressures on Bearing Surfaces. 
 
 M. Bearings. 
 
 13^ X 14 in. 
 
 234 lbs. per 
 sq. in. 
 
 Crank Pin. 
 
 472 lbs. per 
 sq. in. 
 
 C. Rod. 
 Top Ends. 
 
 7^ X 8 in. 
 
 737 lbs. 
 per sq. in. 
 
 Slipper Guide. 
 
 26x21 in. 
 
 38-1 lbs. 
 per sq. in. 
 
 Thrust 
 Surface. 
 
 44-2 lbs. 
 per sq. in, 
 
 Stern 
 Bearing. 
 
 28-8 lbs. 
 per sq. in. 
 
 Steam Speeds. 
 
 Cylinders. 
 
 Revolu- 
 tions. 
 
 Piston 
 Speed. 
 
 Port 
 Area. 
 
 Port 
 Opening. 
 
 Exhaust 
 .Speed. 
 
 Steam 
 Speed. 
 
 Valve 
 Travel. 
 
 Cut- 
 off. 
 
 „ , . Exhaust 
 SPfcd'n t to 
 P'P«s- j Condenser. 
 
 H.P. 
 
 ... 
 
 
 Sq. In. 
 67 
 
 Sq. In. 
 
 53-8 
 
 71-4 
 
 88-8 
 
 In. 
 
 5i 
 
 ■A 
 
 8 in. dia., 
 95 F.P.S. 
 
 
 LP. 
 
 73 
 
 584 
 
 I 12 
 
 93-8 
 
 I20-5 
 
 143-8 
 
 5i 
 
 ■7 
 
 
 
 L.P. 
 
 t 
 
 
 
 246f 
 
 229 
 
 M7-3 
 
 159 
 
 5i 
 
 •7 
 
 
 f no 
 (F.P.S. 
 
Appendix 691 
 
 Economy of Feed Water Heating. 
 
 (Weir System.) 
 
 Data. — 
 
 Boiler Steam, 185 lbs. gauge. 
 L.P. „ 10 
 
 Hot well Temperature, 110°. 
 „ feed „ 220^ 
 
 Heating steam drawn from L.P. chest. 
 
 Then, 185 + 15 = 200 lbs. absolute boiler steam. 
 
 200 lbs. absolute = 381-7 temperature (from Table, page 709). 
 
 Total heat = 1115 + 3 X T". 
 
 = 1115 4- -3 X 3817 = 12295 B.T.U. 
 
 Again, 10 + 15 = 25 lbs. absolute L.P. steam. 
 
 25 lbs. absolute = 240° temperature (from Table, page 705). 
 
 Total Heat = 1115 + 3 X 240 = 1187 B.T.U. 
 
 Heat available for feed heating per\ _ „ » _ ,^ r t II 
 
 lb. L.P. steam ( - "»7 110—10770.1.0. 
 
 Increase of feed temperature required = 220° — 110° = 110°. 
 
 Percentage of L.P. steam required "\ _ ,^„„ ,,^ t«« «-., <-- „«. ,,.-.» ~-» ^_-4. 
 for feed heating. 1 = '°77 : no : : 100 per cent. = io-2i per cent. 
 
 Heat required per lb. water for \ 
 evaporation in boiler without J- 
 feed heating. j 
 
 Heat required per lb. water for "i 
 
 evaporation m boiler with feed - = 1229-5 "~ 220° = 1009-5 B.T.U. 
 heating J 
 
 Extra water evaporated due to 1 = As, 11 19-5 : (iii9-5— 1009-5) :: 100 per cent, 
 feed heating / = 9-8 per cent. 
 
 Assuming about equal horse-power in each of the three cylinders: — 
 
 Loss of power due to withdrawal 1 ^^ __ „„^ _„„, . , „ . „„, „„„, 
 of L.P. steam / =^°-2i P^"^ ^^^nt. -r 3 = 34 per cent. 
 
 Then, Clear gain by feed heating = 9-8 per cent. — 3-4 per cent. = 6-4 per cent. 
 
 From the foregoing it will be evident that the heat units given up 
 by conden.sation in the heater by each pound of L.P. steam is sufficient 
 (neglecting transmission losses, etc.) to heat up 9-6 lbs. of feed water 
 from no" to 220" temperature, as 1077 -f no" = 9-6 lb.s. water heated. 
 
 Boiler Efficiency. 
 
 The efficiency of a boiler is the ratio of actual to theoretical 
 evaporation of i lb. coal for water from and at a temperature of 
 212°, which latter is expressed as the "equivalent evaporation," 
 and is the standard taken for test purposes. 
 
 To obtain " Equivalent Evaporation." 
 
 Example. Pres.sure, 165 lbs. gauge; temperature, 372-8"; feed 
 temperature, 160° ; actual evaporation (measured), 8-5 lbs. water per 
 pound coal. Find equivalent evaporation. 
 
692 
 
 " Verbal " Notes and Sketches 
 
 Equivalent evaporation = (iHi+jST" - f) X Ibs^water 
 
 966 
 
 Then, 
 
 Where, T° = Steam temperature, f = Feed temperature. 
 
 So that, ("^5 + -3 X 3725- 160°) X 8-5 ^ ^.33 i^g. (from and at 212). 
 906 
 
 Observe that 966 B.T.U.= 11 15 + -3 x 2i2°-2i2°. 
 
 Calorific (Heat) Value of Coal. — The following table gives the 
 average composition and heat unit value of Welsh, Newcastle, and 
 Scotch coal, also of petroleum. 
 
 Composition and 
 
 Heat 
 
 Value 
 
 OF Fuel. 
 
 Name. 
 
 Carbon. 
 
 Hydrogen. 
 
 Oxygen. 
 
 Sulphur. 
 
 Ash, 
 
 Nitrogen, 
 
 etc. 
 
 Total Heat 
 
 Units per 
 
 Pound. 
 
 Welsh coal 
 Newcastle coal 
 Scotch coal - 
 Petroleum 
 
 84 
 82 
 78 
 86-5 
 
 4-8 
 
 5"3 
 6 
 12-3 
 
 4 
 
 
 9 
 
 I"2 
 
 1-5 
 
 I'2 
 
 I 
 
 5-7 
 
 5-5 
 6 
 
 14700 B.T.U. 
 14600 „ 
 14000 „ 
 20000 ,, 
 
 The heat value of the fuel must be known to obtain anything like 
 accurate results, and usually a sample of the coal is specially analysed 
 to obtain the average calorific value per pound. 
 
 Then, 
 
 Boiler efficiency (per cent.) = Equivalent evaporation X 966 X 100 per cent.^ 
 
 Calorific valuel 
 
 Example i. Steam pressure (gauge), 170 lbs.: feed temperature, 
 180°; actual evaporation per pound coal (measured), 8-6 lbs. water ; 
 calorific value of fuel (Scotch coal), 14000 B.T.U. Find boiler 
 efficiency. 
 
 Then, 170 + 15 = 185 lbs. absolute pressure. 
 
 And, 185 lbs. = 375°. 
 
 Also, 1115 + -3 X 375°— 180° = 1047-5 B.T.U. lequired for evaporation. 
 
 Equivalent evaporation = ^°47'5 X — •_ _ ^.^^^ lbs. water from and at 212°. 
 
 906 
 
 Boiler efficiency = 9-32 X 966 X 100 per cent. ^ ^ ^^^^ 
 
 14000 
 
 Example 2. Pressure, 200 lbs. ; feed temperature, 170° ; actual 
 evaporation (measured), 9 lbs. water per pound coal ; calorific value 
 of coal, 12500 B.T.U. Find boiler efficiency. 
 
 Then, 200 + 15 = 215 lbs. absolute. 
 
 And, 215 lbs. = 388* temperature (from Table, page 709). 
 
 Equivalent evaporation = ("^3 + "3 X 3^° - 170°) X 9 — ^.gs lbs. from and at 212'. 
 
 Boiler efficiency = 9-88 X 966 X lOO per cent. ^ ^^.^ p^^ ^^^^ 
 
Appendix 693 
 
 The efficiency ranges from about 65 to 80 per cent, in ordinary 
 cases, and varies with type of boiler. The efficiency is increased 
 when the steam is superheated. 
 
 Coal and Water Consumption. — In testing a boiler for efficiency 
 the coal is supplied in measured quantities, and the feed water is 
 passed through measuring tanks or barrels, so that accurate records 
 may be obtained of the actual coal burnt and water evaporated in a 
 given time. From this the actual evaporation per pound coal is 
 obtained as follows : — 
 
 Total feed water evaporated, sav, per hour (as measured) Ait ^ *.- 
 
 ~—r-, i J r — ^-—, ^ xr = Actual evaporation. 
 
 Total coal consumed per hour (as measured) 
 
 Example. — In testing a boiler plant for the efficiency, the coal fired 
 in twenty-four hours (test period) measured 54620 lbs., and the water 
 evaporated in the same time as measured with the tanks was 
 478500 lbs. Find the actual evaporation per pound. 
 
 Then, Actual evaporation = 478500 -H 54620 = 876 lbs. Answer. 
 
 Exercise i. Find boiler efficiency, given the following: — Pressure, 
 180 lbs. gauge; feed water temperature, 162°; actual evaporation, 
 8-8 lbs. water; and heat value of fuel, 13000 B.T.U. per pound. 
 Answer, 72 per cent. 
 
 Exercise 2. Find boiler efficiency, given the following : — Pressure, 
 215 lbs. gauge ; feed water, 190° temperature; total coal burnt per 
 hour, 2500 lbs. ; and total water evaporated per hour, 21500 lbs. 
 Heat value of coal, 13500 B.T.U. per pound. Answer, 66-4. 
 
 Superheated Steam. — If the steam is superheated the number 
 of heat units required to produce the rise of superheat temperature 
 must be added to the total heat of the steam. To obtain the number 
 of heat units, the specific heat constant of superheated steam at 
 constant pressure has to be used, and this is usually taken at -48, 
 which means that to raise one pound of steam 1° Fahr. requires only 
 •48 of the heat required to raise one pound of water 1° Fahr. 
 
 Therefore, Heat units = -48 X Degrees superheat. 
 
 Example. Find number of heat units added to steam to produce 
 a superheat of 100° Fahr. (from 366° to 466° Fahr.). 
 
 Then, Heat units = -48 X 100' = 48 B.T.U. Answer. 
 
 Equivalent Evaporation (with superheated steam). 
 
 [(1115 + -3 X T° — f) + -48 X (Ti° — T°)] X Pounds water 
 
 966 " 
 
 Where, T° = Boiler steam temperature. 
 ,, <* = Feed temperature. 
 
 ,, Tj° = Temperature of superheated steam. 
 
 ,, 966 = Latent heat of evaporation from and at 212*. 
 
 Example. Boiler pressure, 200 lbs. gauge, surperheated to 500° 
 Fahr. Feed temperature, 190° ; actual evaporation (measured), 9-3 
 
694 
 
 Verbal " Notes and Sketches 
 
 lbs. water per pound coal ; and calorific value of coal, 13000 B.T.U. 
 per pound. Find boiler efficiency. 
 
 Then, 200 + i5 = 215 lbs. absolute. 
 
 Temperature = 388° (from Table, page 709). 
 
 Therefore, 
 
 evlporaS} = [("15 + -3 X 388° - 190° + -48 X (500^ - 388°)] X 9-3 
 
 _ (1115 + II6-4 - 190 + 53-76) X 9-3 
 966 
 
 = (^095- 16 X 93 = 10-45 lbs. water from and at 212*. 
 900 
 
 Boiler efficiency = i0'43 X 966 X 100 per cent. ^ ^ ^^^^ ^^^^^^ 
 ' 13000 
 
 Exercise. Boiler pressure, 185 lbs. gauge superheated up to 510° 
 Fahr. ; feed temperature, 165°; actual evaporation, 9 lbs. water per 
 pound coal ; and heat value of coal, 13500 B.T.U. per pound. Find 
 boiler efficiency. Answer, 74'9 per cent. 
 
 Engine and Boiler Data. 
 
 The following data constitutes a useful and valuable reference to 
 the various proportions of parts, as usually designed, for boilers and 
 engines of a given power, and the reader should carefully study and 
 compare the dimensions, proportions, and results as tabulated. 
 
 Vessel. 
 
 (Length 
 Breadth - 
 Depth 
 Mean draught 
 Gross tonnage 
 Dead weight 
 
 425 ft. B.P. 
 54 ft. 
 
 31 ft. 6 in. 
 27 ft. 6 in. 
 7300 tons. 
 9250 » 
 
 Boilers. 
 
 Four single - ended, , 
 fitted with Schmidt / 
 type superheater ' 
 tubes, f in. dia- 
 meter. 
 
 / Diameter - 
 ' Length - 
 Four furnaces 
 Diameter at mouth 
 
 „ inside corrugations 
 Length of bars 
 G.S. 
 
 No. of plain tubes per boiler 
 „ stay „ 
 
 Length of tubes - 
 Diameter of all tubes 
 Funnel diameter - 
 
 „ height 
 Boiler pressure 
 
 16 ft. 2 in. 
 12 ft. 
 Deighton type. 
 
 3 ft- 4^ in- 
 
 2 ft. I if in. 
 
 5 ft- 
 
 65 OlI per boiler. 
 
 206. 
 
 1 2 of yV in- thick. 
 
 60 „ f „ 
 
 98 M 16 » 
 
 7 ft. 6 in. 
 
 3 in- 
 
 8 ft. 
 
 44 ft. 6 in. above casing. 
 220 lbs. gauge. 
 
Appendix 
 
 695 
 
 Engines. 
 
 Quadruple expansion 
 balanced on Yar- 
 row, Schlick, and 
 Tweedy system, 
 total LH.P., 4300. 
 
 Propeller. 
 
 Four-bladed R.H. 
 
 Condenser. 
 Weir's Uniflux type. 
 
 Piston 
 Clearances. 
 
 Diameter of cylinders 
 
 H.P., 2 7 5 in.; ist LP., 
 
 
 39in.; 2nd LP., 56in.j 
 
 
 L.P., 81-5 in. 
 
 Stroke 
 
 54 in- 
 
 Length of connecting rods 
 
 9 ft. 6 in. 
 
 Diameter of piston rods - 
 
 8 in. 
 
 Depth of stuffing box 
 
 10 in. 
 
 Diameter of stufting box - 
 
 io| in. 
 
 ,, valve spindles 
 
 44 )> 
 
 Depth of stuffing box 
 
 8 „ 
 
 Diameter of stuffing box - 
 
 7 
 
 ,, crank shaft - 
 
 16 „ 
 
 „ pins - 
 
 i6i „ 
 
 „ tunnel shatt - 
 
 I si .. 
 
 „ propeller shaft 
 
 16^ „ 
 
 Diameter of propeller shaft 
 
 
 over liner 
 
 i8i „ 
 
 Diameter - 
 
 18 ft. 9 in. 
 
 Pitch 
 
 18 ft. 7-i in. 
 
 Surface - 
 
 120 □ 
 
 Boss of cast steel. 
 
 
 Blades of Bull's metal. 
 
 
 Diameter of studs 
 
 3?in- 
 
 Cooling surface - 
 
 3500 □ 
 
 Number of tubes - 
 
 1620 
 
 Diameter of tubes (ext.) - 
 
 f in. 
 
 Thickness „ 
 
 18 B.W.G. 
 
 Length between tube plates 11 ft. 
 
 NOTE. -I. H.P. =4300. * 
 
 Then, 35po = -8 [71 cooling surface per I. H.P. 
 \ 4300 ^ 
 
 
 Top. 
 
 Bottom. 
 
 iJ in. 
 , I 
 
 * 1 ti 5) 
 
 T 1 
 
 A H )> 
 
 T ' 
 
 ^ Hi )) 
 
 H.P. ... - 
 ist LP. - - - - 
 2nd LP. ... - 
 L.P. - - - - 
 
 T6 in. 
 7 
 
 TH" » 
 9 
 16 J» 
 
 Pump 
 Clearances. 
 
 
 Top. 
 
 Bottom. 
 
 Air pump 
 Bilge pump - 
 
 TF in- 
 1 
 2 " 
 
 \i- in. 
 
696 
 
 "Verbal" Notes and Sketches 
 Valve Settings. 
 
 
 H.P. 
 
 1st LP. 
 
 2nd LP. 
 
 L.P. 
 
 Travel of all Valves, 
 Sin. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Top. 
 
 Bottom. 
 
 Top. 
 
 Bottom. 
 
 Top. 
 
 Bottom. 
 
 Top. 
 
 Bottom, 
 
 Lead - 
 
 In. 
 i 
 
 In. 
 
 f 
 
 In. 
 5 
 16 
 
 In. 
 T6 
 
 In. 
 
 7 
 T6 
 
 In. 
 9 
 16 
 
 In. 
 9 
 16 
 
 In. 
 11 
 
 16 
 
 Steam lap 
 
 ^n 
 
 ll§ 
 
 2tV 
 
 ^li 
 
 2 
 
 l| 
 
 l| 
 
 If 
 
 Port opening 
 
 2tV 
 
 2tV 
 
 Ifj 
 
 2tV 
 
 2 
 
 H 
 
 2j- 
 
 2i 
 
 Exhaust lap - 
 
 + tV 
 
 4- 1 ^ 
 + 16 
 
 -i 
 
 + f 
 
 1 
 ~ 16 
 
 + \l 
 
 + tV 
 
 + 11 
 
 Cut-off - 
 
 42 
 
 37f 
 
 39? 
 
 35h 
 
 40 
 
 35i 
 
 4of 
 
 36i 
 
 Compression (from 
 end of stroke) 
 
 5h 
 
 6 
 
 5l 
 
 6i 
 
 6|- 
 
 7 
 
 7i 
 
 7f 
 
 
 Piston valve. 
 Diam. at top, 
 
 Piston valve. 
 Diam. at top, 
 
 Twin 
 Piston Valve. 
 
 Diam. at top, 
 
 Double 
 Ported 
 
 
 155 !"• 
 Diam.atbot., 
 
 22;^ in. 
 Diam.atbot., 
 
 18-^ in. 
 Diam.atbot., 
 
 Slide Valve. 
 
 
 15 m. 
 
 22 in. 
 
 13 in. 
 
 
 Observe that the difference in steam lap and in port opening top and 
 bottom is exactly equal to the difference in lead top and bottom (i in.) ; also 
 notice that, as link motion valve gear is fitted, the cut-off is later on the down 
 stroke in each case. Again, the xst LP., 2nd LP., and L.P. valves have all 
 minus exhaust lap on top and plus exhaust lap on bottom : this is designed 
 to reduce the top compression and to increase the bottom compression. 
 
 220 lbs. gauge. 
 208 „ 
 108 „ 
 
 - 47 » 
 ii*5 
 
 78"2 lbs. (mean cut- 
 off = 78 per cent). 
 
 39"4 lbs. (mean cut- 
 off = 71*5 per cent.). 
 
 20 lbs. (mean cut- 
 off = 707 per cent.). 
 
 12 lbs. (mean cut- 
 off = 7 1 "6 percent.). 
 
 - 78. 
 
 - 988 r T^^^i 
 ■ '°°°Jlh.p. 
 " '°^M 4366 
 
 Pressures. 
 
 Revolutions, 
 power, speed. 
 
 / Boiler steam 
 H.P. 
 ist LP. „ 
 2nd LP. „ 
 L.P. 
 M.E.P., H.P. 
 
 „ ist LP. - 
 
 2nd LP. - 
 
 „ L.P. 
 
 Revolutions 
 
 LH.P. ofH.P. - 
 ist LP.- 
 2nd LP. 
 L.P. - 
 
Appendix 697 
 
 Consumption 
 and Slip. 
 
 Tons coal per day 
 
 6o"5 tons. 
 
 Speed 
 
 1 2 "86 knots. 
 
 Slip per cent. 
 
 - 7-6. 
 
 Coal per I.H.P. hour 
 
 1-3 lbs. 
 
 Sea 
 
 Moderate. 
 
 NOTE. 60-5 X 2240^ j^g J pj p ^ 
 
 4366 X 24 -^ ^ 
 
 STANDARD SPECIFICATION FOR CARGO- 
 STEAMER ENGINES. 
 
 Guidance Specification for Reciprocating Triple Expansion 
 Marine Engines for Cargo Boats.* 
 
 Compiled by the Council and Members of the North-East Coast 
 Institutio7i of Engineers and Shipbuilders, 1917- 
 
 Specification. 
 
 1. Indicated Horse-Power. — For calculation purposes in this 
 specification and in average sea conditions the I.H.P. is to be found 
 as follows : — 
 
 I.H.P.=5!SN 
 700 
 
 D= Diameter of L.P. cylinder in inches. 
 
 S= Stroke in feet. 
 
 N= Revolutions per minute. Found as per section 2. 
 
 The divisor is adjusted for a referred mean pressure of 30 lbs. per 
 sq. in. 
 
 2. Revolutions. — 
 
 J. _ 32 (S + 4) 
 
 3. Boiler Pressure. — 180 lbs. per sq. in. (gauge). 
 
 4. Ratios of Cylinder Areas. — Ratio for 180 lbs. pressure. 
 
 H.P. M.P. L.P. 
 
 I About 274 About 7-5 
 
 „ I „ 2-74 
 
 5. Cuts off at Sea Power. — About 57-5 per cent. ; 57-5 per 
 cent. ; 55 per cent, 
 
 6. Speeds of Steam. — The mean steam speeds to be calculated 
 as follows : — 
 
 Area of cy li nder in square i nch X piston speed in feet per second. 
 
 Area of pipe, port or opening in square inch. 
 
 ^ speed in feet per second. 
 
 * Extract from paper read at the North-East Coast Institution of Engineers 
 and Shipbuilders, 3rd February 191 7. 
 
698 "Verbal" Notes and Sketches 
 
 Table of mean steam speeds in feet per second : — 
 
 
 H.P. 
 
 M.P. 
 
 L.P. 
 
 Main steam pipe 
 
 1 10 
 
 — 
 
 — 
 
 Port opening - - - 
 
 1 10 
 
 150 
 
 240 
 
 Steam ports - 
 
 80 
 
 85 
 
 100 
 
 Exhaust passage or pipe 
 
 60 
 
 65 
 
 75 
 
 Width of Steam Ports. — Width of ports to be about o-8 of 
 diameter of cylinder. 
 
 7. Maximum Load. — The maximum load on main working 
 parts to be taken as the product of the area of H.P. cylinder in inches, 
 and the boiler pressure in lbs. per square inch (gauge). 
 
 8. Crankshaft. — The diameter of crankshaft in body to be to 
 nearest 1 in. above Lloyd's Rule, and the proportions of the remain- 
 ing parts to be not less than the following : — 
 
 1. Diameter of crank-pin to be equal to diameter of shaft. 
 
 2. Diameter of crankshaft in web to be equal to diameter of 
 
 shaft, plus h in. 
 
 3. Diameter of webs to be equal to diameter of crank-pin by i-85. 
 
 4. Thickness of webs to be equal to diameter of shaft by 0-62. 
 
 5. Thickness of couplings to be equal to diameter of shaft byo-25. 
 
 6. Six coupling bolts to be used for shafts up to and including 
 
 15 in. diameter. Nine coupling bolts to be used for 
 
 shafts above 15 in. diameter. 
 *y. Diameter of pitch circle of coupling bolts to be 1-43 diameter 
 
 of crankshaft. 
 *8. Diameter of coupling bolts to be equal to : — 
 
 07 X 
 
 V r 
 
 diameter of shaft ^ in inches. 
 
 number of bolts X diameter of pitch circle in inches. 
 Bolts to be parallel. 
 
 9. Length of Connecting Rod. — Length of connecting rod 
 between centres to be twice the stroke or four times the crank radius. 
 
 Diameter of Connecting Rod. — Connecting rods may be made 
 parallel, same diameter as piston rod body. 
 
 Connecting Rod Top Ends. — Connecting rods to have single 
 top-end gudgeons for all engines having H.P. cylinders of 25-in. 
 diameter and under. 
 
 10. Crosshead Guides. — Main crosshead guides to be of the 
 single type in all sizes of engine. 
 
 * These two rules may be varied, provided that equivalent strength is given. 
 
 M 
 
Appendix 699 
 
 Load on Main Crosshead Guides.— Maximum load in lbs. on 
 crosshead guides to be taken as : — 
 
 Area of H.P. cylinder in square inches X boiler pressure in pounds 
 
 per square inch ( gauge) 
 
 4 
 
 11. Maximum Pressures on Principal Bearing Surfaces. — 
 
 Lbs. per sq. in. 
 Main bearings .... 250 
 
 Crank-pins ----- ^oo 
 
 Crosshead gudgeons - - - 1000 
 
 Guide shoes (ahead) - - - 55 
 
 „ „ (astern) - - - no 
 
 Diameter by length to be taken as area of bearings. 
 Overall length by overall breadth as area of guide shoes. 
 
 12. Maximum Stresses on Principal Working Parts. — 
 
 Lbs. per sq. in. 
 
 Ingot steel piston rod at screw - - - 6000 
 
 Piston rod body (after deducting I in. from diameter 
 
 to allow for returning) - - . . 3000 
 
 Piston and connecting rod bolts at screw - - 55°° 
 
 Main bearing bolts ----- 4500 
 
 Main bearing keeps (if forged) - - - 6000 
 
 Connecting rod bottom end keep (if forged) - 7500 
 
 Piston rod keep (if forged) - - - - 7500 
 
 (The keeps are calculated as beams with distributed load and sup- 
 ported ends.) 
 
 13. Valve Gear. — The valve gear sizes to be determined from the 
 load on the M.P. slide valve spindle, calculated as follows : — 
 
 Load in lb. = 0165 |s4 (A — B) — 9 c\ 
 
 Where A ^ Area of face of M.P. valve in square inch. 
 
 B = Combined area of steam ports in valve face in square inches. 
 C = Combined area of exhaust ports in valve face in square inches. 
 Valve Spindles. — Diameter of valve spindles at gland to be not 
 less than : — 
 
 Diameter of piston rod at gla nd ^ . 
 2 X « m. 
 
 Maximum Pressures on Bearing Surfaces of Valve Gears. — 
 
 Lbs. per sq. in. 
 
 Link block gudgeon - - - - 500 
 
 „ slippers .... 300 
 
 Eccentric rod top end pins . - . ^oo 
 
 ,, sheaves (ahead and astern) - - 85 
 
 14. Thrust Block. — When of horseshoe type the pressure on 
 thrust collars not to exceed 70 lbs. per sq. in. when calculated from 
 indicated thrust, which is determined as follows : — 
 
 Lbs. Indicated thrust = p.. . . — = — t^ — , ^! -. — 7— 
 
 Pitch in feet X revolutions per minute. 
 
700 " Verbal " Notes and Sketches 
 
 15. Circulating Water. — The amount ofcirculating water supplied 
 to be forty times the feed, taking the latter at 1 5 lbs. of steam per 
 I.H.P. per hour. 
 
 16. Main Eng-ine-Driven Reciprocating Circulating Pump 
 (Double-acting). — To be proportioned to deliver the above quantity 
 of water at a displacement efficiency of 80 per cent. 
 
 17. Maximum Speeds of Circulating Water. — 'ihe speeds of 
 circulating water are to be calculated as follows : — 
 
 o«8 area of bucket in sq. in. X bucket speed in ft. per sec. _ j r ^ater 
 
 Area of passage in sq. in. 
 
 Approximate Speeds in Feet per Second.— 
 
 Ft. per sec. 
 
 Main injection ..... 9-0 
 
 Passages in pump - - - - - 5"o 
 
 Valve grids - - - - - - 6"o 
 
 Past lift of valves ----- 9'5 
 
 Discharge pipe - - - - - 7 '5 
 
 18. Air Pump. — Capacity of air pump not less than yV of the 
 capacity of L.P. cylinder. 
 
 19. Main Engine-Driven Feed Pumps. — Capacity of each 
 engine-driven feed pump ^\^ of capacity of L.P. cylinder. 
 
 20. Pump Gear. — Load on pump gear to be calculated as follows : 
 Load in lb. = 25 (area of air pump bucket + area of circulating 
 pump bucket)-!- 15 (area of both feed pump rams -f area of both bilge 
 pump rams). All in square inches. 
 
 Maximum Pressures on Pump Gear Bearing Surfaces. — 
 
 Lbs. per sq. in. 
 Pump link pins ..... 400 
 
 Engine link pins . - . - - 300 
 
 Pump lever centre gudgeon bearings - - 250 
 
 For cargo vessels of large tonnage it is recommended that the 
 circulating and feed pumps be independently driven pumps. 
 
 21. Utilisation of Heat in Exhaust Steam from Auxiliary 
 Engines. — A source of very considerable economy in a marine in- 
 stallation being the complete absorption by the feed water of the heat 
 in the exhaust steam from the various auxiliaries, including the steer- 
 ing engine, electric-light engine and evaporator, such a vacuum should 
 be carried in the main condenser as will enable this to be effected in 
 all seas in which the vessel trades. A vacuum of 2"] in. maintained 
 in the steam space of the condenser, the temperature of the sea being 
 70° Fahr. (barometer 30 in.) has been found to meet these require- 
 ments on an average cargo boat. 
 
 22. Cooling Surface. — In determining the amount of cooling 
 surface per I.H.P. average at sea, provision should be made for the 
 rapid initial degrading effect of oil and scale on the tube surfaces, and 
 also for the permanent prejudicial effect on the condensing efficiency 
 of the residual air in the condenser. 
 
SS. Pump Crosshead and Links, 
 
DESIGN DRAWINGS AND CALCULATIONS. 
 
 FIRST CLASS. 
 
 The following Set of Drawings and Design Calculations include, among others, 
 those given at the Board of Trade Examinations to First-Class Engineer Candi- 
 dates, and for practice these should be drawn out to the scales marked on each. 
 Note. — The calculations shown for the various proportions of parts repre- 
 sent average practice, but it should be noted that these vary to some extent 
 in the designs of different engine builders. 
 
 Sheets i and 2 show proportions of Nuts, Bolts, and Screws. 
 
 Boilers— 
 
 1. Single-Ended Combustion Chamber. 
 
 2. Double-Ended Combustion Chamber. 
 
 3. Furnace and P^ire Bars. 
 
 4. Water Gauge Column. 
 
 5. Vertical Donkey Boiler. 
 
 6. Fire Bars and Bearers for Vertical Boiler. 
 Valves— 
 
 7. Dead Weight Safety Valve. 
 
 8. Spring-Loaded Safety Valve. 
 
 9. Boiler Stop Valve. 
 
 10. Engine Room Stop Valve. 
 
 11. Feed Check Valve. 
 
 12. Bilge Suction Valve Chest 
 1 2 A. Bilge Injection Valve. 
 
 13. Side Discharge Valve. 
 
 14. Cylinder Relief Valve. 
 
 15. Slide Valve and Spindle. 
 
 16. Inside Steam Piston Valve. 
 
 17. Double Ported Slide Valve. 
 Pumps — 
 
 18. Air Pump. 
 
 19. Feed Pump Complete. 
 
 19A. Feed Relief Air Vessel and Pump Valves. 
 Pistons, etc — 
 
 20. H.P. piston and Rod. 
 
 21. L.P. Piston and Rod. 
 
 22. L.P. Cylinder Cover. 
 
 23. Donkey Pump Cylinder and Valve. 
 Eccentric, etc. — 
 
 24. Eccentric and Rod Complete. 
 
 25. Quadrant Bars, etc. 
 
 26. Reversing Bell Crank. 
 Shafting, etc.— 
 
 27. Crank Shafting. 
 
 28. Thrust Shaft and Shoe. 
 
 29. Thrust Block. 
 
 30. Stern Tube and Shaft. 
 
 31. Propeller Boss. 
 
 Various — 
 
 32. Bottom Blow-Off Cock. 
 
 33. Three-Way Change Cock. 
 
 34. Main Bearing. 
 34A. Tunnel Bearing Block. 
 
 35. Steam Pipe Expansion Joint. 
 
 36. Pump Levers. 
 
 37. Connecting Rod. 
 
 38. Pump Crosshead and Links. 
 
\ 
 
 ^^ 
 
DESIGN DRAWINGS AND CALCULATIONS. 
 
 FIRST CLASS. 
 
 The following Set of Drawings and Design Calculations include, among others, 
 those given at the Board of Trade Examinations to First-Class Engineer Candi- 
 dates, and for practice these should be drawn out to the scales marked on each. 
 Note. — The calculations shown for the various proportions of parts repre- 
 sent average practice, but it should be noted that these vary to some extent 
 in the designs of different engine builders. 
 
 Sheets i and 2 show proportions of Nuts, Bolts, and Screws. 
 
 Boilers— 
 
 1. Single-Ended Combustion Chamber. 
 
 2. Double-Ended Combustion Chamber. 
 
 3. Furnace and Fire Bars. 
 
 4. Water Gauge Column. 
 
 5. Vertical Donkey Boiler. 
 
 6. Fire Bars and Bearers for Vertical Boiler. 
 Valves— 
 
 7. Dead Weight Safety Valve. 
 
 8. Spring-Loaded Safety Valve. 
 
 9. Boiler Stop Valve. 
 
 10. Engine Room Stop Valve. 
 
 11. Feed Check Valve. 
 
 12. Bilge Suction Valve Chest. 
 I2A. Bilge Injection Valve. 
 
 13. Side Discharge Valve. 
 
 14. Cylinder Relief Valve. 
 
 15. Slide Valve and Spindle. 
 
 16. Inside Steam Piston Valve. 
 
 17. Double Ported Slide Valve. 
 Pumps — 
 
 18. Air Pump. 
 
 19. Feed Pump Complete. 
 
 19A. Feed Relief Air Vessel and Pump Valves. 
 Pistons, etc.— 
 
 20. H.P. piston and Rod. 
 
 21. L.P. Piston and Rod. 
 
 22. L.P. Cylinder Cover. 
 
 23. Donkey Pump Cylinder and Valve. 
 Eccentric, etc. — 
 
 24. Eccentric and Rod Complete. 
 
 25. Quadrant Bars, etc. 
 
 26. Reversing Bell Crank. 
 Shafting, etc. — 
 
 27. Crank Shafting. 
 
 28. Thrust Shaft and Shoe. 
 
 29. Thrust Block. 
 
 30. Stern Tube and .Shaft. 
 
 31. Propeller Boss. 
 
 Various — 
 
 32. Bottom Blow-Off Cock. 
 2,^,. Three- Way Change Cock. 
 
 34. Main Bearing. 
 34A. Tunnel Bearing Block. 
 
 35. Steam Pipe Expansion Joint. 
 
 36. Pump Levers. 
 
 37. Connecting Rod. 
 
 38. Pump Crosshead and Links. 
 
i 
 
botrom o|- 
 
 ^ 
 
!?od!i;s 
 
 pikh X 3 
 
 , bol"l"orri of- 
 ffiread 
 
 pifcK '^ 3 
 
 Bolt and Nut Complete. 
 
 Nollce that the radius i>f curvature is taken as equal to the depth of the 
 nut (equal to dj : this is not strictly correct, hut is quite near enough for 
 practical purposes. Observe the positions of radius for the nut curvature in 
 the side view, which is about two-thirds distant from the top edge. 
 
 In the plan the construction circle (equal in diameter to the distance over 
 angles) is divided up into six by the circle radius distance in the compasses. 
 
 Nuts, Bolts, and Screws. 
 
 iWhitworth Standard 
 
 Let (/—-diameter of bolt. 
 
 Bolt and Lock Nuts. 
 
 The hexagon sides of the mil shown in the plan may be drawn in by applying the 60 degree 
 set square tangentially to the circle over flats. 
 
 This circle = 1.5 X </ + 5 in. 
 
 The nuts are chamfered off to an angle of 45". 
 
 ;EXAMPLE -Calculate the required dimensions of nut and bolt head for a bolt 2 in. diameter, 
 with 4.'. threads per inch. 
 
 Width across angles of nut = 1-75 X d -\- 1 
 Width across fiats ofnut =1-5 Xtf+^ 
 Depth of nut = d. 
 
 Diameter of round bolt head = 1-5 X d. 
 
 '•75 X a + 125 in. = 3'25 in. = 35 >" 
 i-S X 2+125 in- =3-"5 in. =3i '" 
 rf = 2 in 
 
 Depth of round bolt head 
 Diameter of point of bolt 
 Depth of point of bolt 
 Depth of top lock nut 
 Depth of bottom lock nut 
 Diameter of washer 
 Thickness of washer 
 
 = -75 yd. 
 
 — diameter at bottom o( thn 
 
 = pitch of thread / 3. 
 
 = d 
 
 = 7 X d. 
 
 = 2-2 X d. 
 
 = -2 X </• 
 
 en, Diameter over angles 
 Diameter over flats 
 
 Depth of nut =d = 
 
 Depth of lock nut (if fitted) = 7X2 in. = i-4- saj 
 
 Diameter of bolt head = I'S X 2 in. = 
 
 Depth of bolt head = 75 X 2 in. = 
 
 / ■■28\ , . 
 
 Diameter at bottom of thread ^2 'n. -(^^.^ ) = 1716 m, say. I. 
 
 Pitch of thread =1^45= 22 in. 
 
1 
 
 \.' 
 
p 
 
00 
 
 l»tc{\B 
 
 Screw for I 
 
 Whitworth Screws. 
 
 (Angular Threads. ) 
 
 Angle of thread = 55 degrees. 
 
 Depth .. = Pitch of thread X 64. 
 
 Pitch .. =1 in. -H threads per inch. 
 
 , 1-28 \ 
 
 Diameter at bottom of thread = Bolt diameter — ^^-j-hreads per inchj 
 Bolt Screws. 
 
 
 
 Uiamtlcr at Uottoni 
 
 Area at Hottum 
 
 1 lanwlcr of 
 
 
 of Thread 
 
 of Thread 
 
 Unit or Sluil. 
 
 1 breads pur inrh. 
 
 (Kffeclive Diameter). 
 
 (Effective .\rea). 
 
 i in. 
 
 20 
 
 •186 
 
 
 0270 
 
 
 12 
 
 •393 
 
 
 121 „ 
 
 
 
 10 
 
 •622 
 
 
 3°8 .. 
 
 I 
 
 
 S 
 
 •840 
 
 
 554 •, 
 
 'i 
 
 
 6 
 
 1-287 
 
 I 
 
 30 „ 
 
 
 
 4i 
 
 i-7'5 
 
 
 31 " 
 
 2.'. 
 
 
 4 
 
 2- 1 So 
 
 3 
 
 73 - 
 
 3 
 
 
 3i 
 
 2-6j4 
 
 5 
 
 45 n 
 
 3i 
 
 
 3 1 
 
 3-106 
 
 7 
 
 57 ,• 
 
 4 
 
 
 3 
 
 3-573 
 
 1002 ,, 
 
 EXAMPLE — 
 
 Find the diameter and area at bottoni uf thread for a 2-in. Ijult, iiaving 
 4^ threads per inch. 
 
 Then. 2 _ | ' - j = 1-716 in. diameter. 
 
 Area at bottom of thread = 1-716- X 7854 = 2-31 0- 
 
 Hexagon Sides of Nut. 
 
 In this method of construction the 30 degree angle set square is applied 
 lanfentially to the circle over flats (1-5 x ^+ ; in.), as shown above. 
 
 Rough Method of Drawing Nuts. 
 
 For small sizes of nuis, or for small scale drawings, it is sufficient to set 
 off the nuts as shown above. 
 
 Observe that the distance over nut angles is taken as equal to 2 x ,/ ; also 
 that the size over flats C is simply measured from the plan and transferred 
 to the elevation view on right. 
 
 This method is, of course, appro.ximate only, but is quite allowable under 
 conditions of small sizes or small scales. 
 
 Hexagon Sides of Nut. 
 
 In this method of construction the circle over .ingles ( 1 -751/4^ J in.) 1: 
 divided up into six by means of the circle radius distance in the compasses, 
 and the sides are then drawn in as shown. 
 
1 
 
J 
 
 1 
 
\.*cW£\.oeo (ffoN -roses. rdoMMoN 1 
 
 3i' Ext': ain't 
 
 N?7 Svyd rn,t:^ 
 
 (ST»y ^ 
 
 3i' , 
 
 %.-rH<i^ - MAKkeo S.- 
 
 ST«Y TOBILS M«B^fO It |,"tu.<;«. 
 
 Fi-c-ito W.-tu h 
 
 ,U-lS A-C Paor^-r 
 
 ^ , j^ , , R\\^v^V\Vv\\'\\\\\\vvvv\\\vvvv\\\\"xx^ 
 
 Girders. 
 
 To find required depth of girders, first, fix on the thickness, in thi 
 
 No. I.— Single Ended Combustifln Chamber. 
 
 [Proisure i8o lbs. natural draught. i 
 (Draw to a scale of i in — I ft.) 
 
 Tube Plates 
 
 and bossed 
 
 out for thf staysi. 
 
 Rule, 
 
 n»r,h r., EirH„. - /'W-P,xtfxLxRess 
 
 Where, 
 
 W = Width of combustion chamber 
 
 
 P— Pitch of top bolts 
 
 
 rf= Distance between girders 
 
 
 L=: Length in feet. 
 
 
 T = Thickness. 
 
 
 C = 825 for 3 bolts and 935 for 4 bolts. 
 
 single plate 
 
 Then, Depths A3i-^5-8)X7-25Xi:jXl8o^8 ^ , 
 
 V 1-625x825 ' 
 
 To pass other surveys, such as Lloyds or British Corporation, thi_' girde 
 made deeper tlian th:U required by the P. of T In the. present case Sf in 
 derided on, in place of barely 8 in. 
 
 Note.— Length of girder = 31 25+ ■: = 31-875 in., say 32 in. 
 
 Rule 
 
 Thickni 
 
 PressureXWxD 
 
 
 ;D-d)XC 
 
 Where, W = Width of combustion chamber. 
 D = Pitch of tubes 
 (/^Inside diameter of tubes 
 = 28000 (compressive stress limitl. 
 
 Then, Thickness = J?9>^^^^^^ = ■■ 
 (4-5— 2-891X28000 
 
 Note.— Tube thickness = 7 S.W-G., which is equal to -176 in. 
 
 Therefore. 3-25 in. — (-176 in. x 21 — 2.89 in. inside diameter of lubes. 
 
 Diameter of Stays (Steel) 
 
 Rule, Stay areaX900a= Surface K Pressure As the pitch is unci|ual. being 7i in , by 8 in the 
 Surface ='-S''+8'_j5,2j ^^ ,„ 
 
 in., or say it in. diameter. 
 
 Diameter of stays 
 
 / 58-28x1! 
 V ■7854x91 
 
 „the pros! 
 
 iiple, 
 
J 
 
J 
 
 1 
 
NoTR.— The calculations are similar to those of No. 
 
'A 
 m 
 
 4 
 
 -^^ 
 
 ^ 
 
 1 
 
 
 k 
 
 
 
 s 
 
 
 
 ^ 
 
 
 
 V 
 
 
 \ 
 
 K 
 
 1 
 
 I 
 
 I 
 
-fT' 
 
 Itn 
 
 \ 
 
 i 
 
p 
 
 ATTEOMii C^a faa^ 
 
 -r ae 
 
 (vuec^ 
 
 6 
 
 oe SIVRa « 
 
 Mo VIA,; 
 
 < aeA 
 
 R£K% 
 
 
 -To S6 F<- 
 
 -reo ,-1 
 
 FJ|^^ 
 
 jAde. 
 
 No. 3.— Furnace with Bars Complete. 
 (Draw to a scale of i^ in. = i ft.) 
 
1 
 

No 4 —Water Gauge Column. 
 
 iDraw to a scale of 6 in = i ftl 
 
J 
 
 1 
 
 ; I 
 
 I! 
 
8" 
 
No. 5 Vertical Type Donkey Boiler. 
 
 (Draw to a scale of i in, = i ft. i 
 
 NOTE —Vertical shell seams Idouble rivetiliEl Diameter c 
 
 Circumferential shell seams (single riveting) Dia 
 
 Pressure. loo lbs. per sq. i 
 
74 
 
 1 
 
 
' JV ft:>\l 
 
 .N 
 
 ! i 
 
'^ 
 
 ^!1 
 
 S 
 
No 6 —Donkey Boiler Fire Bars. 
 (Draw to a scale'oi i.J in. = i ft.) 
 
^ 
 
■>.J>_JVy 
 
 --> 
 
 / 
 
1 
 
//^. /,-£'■ 
 
 No. 7.— Dead Weight Safety Valve. 
 
 { Draw to a scale of 3 in. = i ft. ) 
 Data.— Boi\tr grate surface consists of 2 furnaces, each 5 ft. by 3 ft. 4 i 
 
 Rule. 
 
 Therefore, 
 
 and. 
 
 Then, 
 
 Pressure, 30 lbs. (gauge). 
 
 Total grate surface = 2x5X333 = 33-3. say 34 sq. ft, 
 37*5 -r- Absolute pressure ~ Valve area in sq. in. per sq, ft grate. 
 37-5 -^<30+ 15) = -833 sq. in.. 
 Total valve area = 34X -833=: 283 sq. in. 
 
 Diameter of valve 
 
 V 7854 
 
 diameter. 
 
 and, Load on valve = 6- X -7854X30= 848-2 lbs. 
 Assuming that weight of valve and spindle amount to, say, 20 lbs,. 
 
 Then, Actual load required = 848-2— 20 = 828-2. 
 
 Again. Fix on diameter of weights ag, say, 16 in. 
 
 Then, Depth of weights = ,-,6^^}.fs^ = 'S'^. -y '53 in- 
 
 Allowing 7 separate weights. 
 
 Then, *_575J5: = 2-25 in. =2^ in. thickness of each weight 
 
 -If a pair of valvi 
 
 fitted, each 
 
 Diameter of each valve 
 
 ^J% 
 
 nly requires to be half the 
 say 4^ in. diameter. 
 

 
 
 
 
 
 
 
 
 1 
 
w 
 
 ^ 
 
IE Coils 
 
 f souare sfeel 
 
 No. 8.— Pair of Spring Loaded Safety Valves. 
 
 {Scale. I', /n, = i flA 
 (Draw to a scale of 3 in. = i ft.) 
 
 Da/«.— Pressure 160 lbs. gauge, 3 furnaces, each grate 5 ft 6 in. by 3, ft, 6 i 
 forced draught, consumption 30 lbs. per. sq. ft. of grate per hour. 
 
 Then, 
 
 ~J^^— = -214 sq. in valve area per sq. ft. of grate at 20 lbs. consumption | 
 sq. ft. of grate. 
 
 Total valve area =.2I4X3X5-SXJ5X^= 18-53 sq. in. 
 
 Diameter of each valve— /— '^ =3-4 in , say 3i in. 
 
 Rule, 1 1000 V J :— Load on valveXMean diameter of coil 
 
 iiooo = Constant for square steel. 
 
 d =: Side of coil in inches 
 
 jioooxd-' = 3.5»x.78s4Xi6oX3 in 
 
 ,,_ 3 /3^5"X 7854X 160X 3 - .,- :„ 
 V "000 " 
 
 Notice tliiil th.' ,-uh- root requires lu Ijt; exlr.iil,-il iifu.i ilivisinn. 
 
 Diameter of boiler branch bore — \/^-^-X2 = 4-9 in. , say sin. diameter. 
 Flange Studs 
 
 Allow, say, 3000 lbs, per sq. in, stress on studs, and assume pressure to act i 
 as far as the pitch centre line of the studs ; also take pitch circle diameter as 10 
 
 When 
 
 Then, 
 And, 
 
 k number of studs 
 Diameter of studs 
 
 / lO'S-'X 160 _„ , , . 
 \/355oX7854-'''"y"" 
 
 NuiK.- -Only one valve of the pair is drawn * 
 
>r=' 
 
^ 
 
 
No. 9 -Boiler Stop Valve. 
 
 (Draw to a scale of 2 in. — I ft.) 
 
 D«(«.— Pressure 160 lbs, (gan^e). Heating surface Idotible ended boiler), 3200 sq. ft. 
 Forced draught. 
 
 Rule, Diameter of vatve :; 
 Then, Diameter of vaive = 
 
 Absolute pressure 
 
 y Heating surface 
 At 
 
 < /^ 
 
 „ . .^ , - .. Valve diameter „ rsr - , - 
 Rule, Diameter of spindle = X v Pressiire-f--l2. 
 
 Then, Diameter of spindle — V^X v'i6o+i2— 1-78 in., say il ii 
 
 Cover Studs. 
 
 Assume that 1 in. diameter studs are decided on for the cover, ar 
 not to exceed, say, 2000 lbs. pei sq. in. 
 
 Then. Number of studs = jj,-r^ = 9-6 studs. 
 
 To allow for a wide margin of safety it will be better to allow 
 
 N'nTtc— Inside diameter of chest = 11 in. 
 
 say, 12 studs of i 
 
r^~f^'o 
 
 
 "^ 
 
 4^ 
 
 JTTDJi 
 
 ^ 
 
 (P 
 
 ■J) 
 
 '^;*^ 
 
ito< 
 

 Is- 
 
 -, 1/' 
 
 UJ 
 
 i 93DJ. 
 
 tP 
 
 i i 
 
 1 
 
 .'1 
 
No 10— Engine Room Stop Valve. 
 
 Scale, 2 ln. = i ft. 
 (Draw to a scale of 3 in. = i ft.) 
 Note.— The calculations are similar to those of the boiler stop valve, No. 9. 
 
>I(D 
 
 (H 
 
 <.w 
 
^■■ 
 
 "IBlh 
 
 J 4T) I 
 
 ■fr-fr — 'i 
 
>!(D 
 
 (Tl 
 
 r^- 
 
No. II.- Feed Check Valve, 
 (Scale. 3 in, = i ft) 
 
 Data. — Pressure, 200 lbs. Valve, 3 in. diameter. 
 
 Allow diameter of chest, inside, 
 Then, 3 in, X l-'; = 
 
 e not less than : 
 3 in, X 1-5 = 4-5 in. ; say S in. diameter. 
 Diameter of spindle=diameter of valve-; 
 
 , times diameter of valve. 
 
 Allow a tensile stress of 3000 sq. in 
 
 „. , . /diameter of 
 Diameter of studs — . / 
 
 Diameter of studs— . /i^--t7 
 V 2500 X 
 
 I studs, and fixing on, say. 6 studs. 
 
 571 
 
 Then 
 
 To allow of a good safety margin fix on. say, ',' in, diameter studs. 
 
 Allow width of flange for studs = stud diameter X 3, 
 
 •625X3=1-875 in., say 2 in. on each side. 
 
 Diameter of cover = 5 in. + 2 in. + 2 in, = 9 in. 
 
 Allow full lift clearance of valve equgil to \ diameter, 
 n, 3 in. —4 = 75 in, lift clearance. 
 
 The thickness of the chest is taken as g in. ; for a larger valve allow ;,' in. 
 NoTK- -Allow the thickness of the flanges to always be in excess of the 
 
 No 
 
 -The 
 
 ring parts are marked A, 
 

 A 
 
i 
 
N 
 
 o 
 
 ll\ 
 
 o 
 
 
 \ ii.a 1 
 
 
 O 
 
 \57 
 
 o 
 
 
 No. 12— Bilge Suction Box. 
 (Draw to a scale of 3 in. = i ft.) 
 
1 
 
 then, 
 Allow dii 
 Allow pil 
 Then, 
 
 Then, 
 
i 
 
1 
 
 \ 
 
 then, 
 Allow du 
 Allow pil 
 Then, 
 
 Then, 
 
W 10 -- ^ 
 
 I '<-\ s, „ - -J ' 
 
 No. I2a.— Bilge Injection Valve. 
 
 (Draw to a scale of 4 in. ^ i ft. 1 
 
 No special caJciriations are required for this drawing as the stresses on the working parts are low. 
 Full lift clearance of valve — diameter -i- 4 — 6 in. -:-4=3 ij in. 
 
1 
 
 then, 
 Allow di) 
 Allow pil 
 Then, 
 
 Then, 
 
then, 
 Allow dii 
 Allow pil 
 Then, 
 
 Then, 
 
 1 
 
% cskBoits 
 
 / Q 
 
 /o ■% 
 
 "A, \ '-xfi! \ 
 / , \ (0 \ 
 
 frr- 1 ♦ o 
 
 
 - 
 
 
 V-7- 
 
 No- 13. —Side Discharge Valve. 
 
 (Sca/e, li to. = j /■(.) 
 (Draw to a scale of z in. il ft.) 
 As the pressure on this type of valve-is low, it is sufficient if the various parts are of light 
 cunslriiction as shown above. The inside diameter of the chest is equal to about i'3 times 
 the diameter of the valve. 
 
 Width of aange = stud diameter X 3 = 75 X 3 = 225 in. 
 Then, Diameter of cover = 2'25 in. + l6 in.+2.2S in.=20.i in., or, say, 21 in. 
 
 Allow full lift equal to \ diameter of valve, or 3 in. 
 
 The studs in the flange on ship's side are screwed through the plate, countersunk, and 
 rivetted over on the outside, with clearing holes in the chest flange inside. 
 
g' Rod 
 
 then, 
 Allow dij 
 Allow pii 
 Then, 
 
 Then, 
 
I 
 
 / 
 
g" Rod 
 
 then, 
 Allow dii 
 Allow pi< 
 Then, 
 
 Then, 
 
No. 14— Cylinder Relief Valve. 
 
 iSca/c, 3 in. = 1 ft.) 
 
 (Draw to a scale qf 4 in, = 1 ft ) 
 
 Data. Valve, 4 in. diameter. Pressure. 20 lbs. 
 
 Fix on mean dianic Ici of s|iiiin; as being about equal to diameter of valve or, say. 
 
 3*i" 
 
 Then, Rule, 
 
 Thei 
 
 T-' = Mean diameter of coil X Load on valv 
 
 T = 3-5 X 4- X -7854 X 20, 
 
 -[, = t5_X 4iXj^7jM X 20 ^ ,^^^ 
 
 lay, f) in. coil. 
 
 •P = V.0799 = -43 in . 
 Observe Ihal ail'e ;'(/(7/ extracliun is required. 
 Alluw 6 suids of ample strengtii, say j in. or J in. diameler. 
 
 Diameter of spindle = Valve diameter ~ 3. 
 
 -3=' 
 
 
.aiDfitqc i)nb 
 
 /*> J - 
 
 then, 
 Allow dij 
 Allow pil 
 Then, 
 
 Then, 
 
then, 
 Allow dij 
 Allow pil 
 Then, 
 
 Then, 
 
i 
 
 
 r 
 
 
 
 1 
 1 
 
 
 =* ■■ ;; 1 !: 
 
 
 ^- 
 
 -2 - 
 
 
 
 ■I '■: 
 
 
 
 f 
 
 Q 
 
 ) 
 
 H ' ,: 
 
 
 
 ■: 
 
 
 
 , 1 4 lo — ■ ■ ■ ■ J 
 
 No. 15.— Slide Valve and Spindle. 
 
 (toaie, 2 /n.= i ft). 
 (Draw tc a scale of 3 in. = i ft.)- 
 
 0«/fl.— Cylinder ports — 24 io. 
 
 Valve travel = 7 in. 
 Top lead ^ i in. 
 Bottom lead := J in 
 Top exhaust lap = o in. 
 Bottom exhaust lap — -|-i in 
 Pressure = 56 lbs. 
 Cylmder diameter — 24 in. 
 Stroke — 36 in. 
 Assume that. 
 
 
 Top steam port opening - 
 Bottom steam port opening = 
 
 As the bottom lead is ^ in. more than top lead, the bottom 
 port opening is al!;o ^ in. more than top port opening. 
 
 Rule, i travel = Steam lap + Lead (either top or bottom). 
 Then, 
 
 (Top), 7 in.H~2=3-5 in., and 3-5 in.— 1-25 = 2.25 steam lap. 
 And, 
 
 (Bottom), 7 in- -=-2 = 3-5 in-, and 3-5 — i-375 = z-i25 steam lap. 
 Length of ports = Diameter of cylinder x 75. 
 .. =24 in. X -75-^18 in. 
 Allow bearing width at sides as, say, 2 in. 
 Then. 
 Depth of valve face — 2^ -f- 2I + i^ -|- 6 -f ij -|- zj 4. 2ft = 19 in. 
 
 And. 
 Rule, 
 
 Allow 
 
 Then, 
 
 Diam- at 
 
 Width of valve face = 2 in. -f 18 -)- 2 = 22 in. 
 
 Face area X Pressure X '2 
 
 " 3500 X 7854 
 tensile stress per sq. ii 
 
 Diameter at screw = . / 
 z ioT friction, and 3500 It 
 
 'V^ 
 
 ^J?^5|^- = .3ia.,s.y.jm.diam 
 
 3500 X -7854 
 
 Diameter of spindle below screw = 1-5 in. X 1-33 =1-99 in,, 
 say 2 in. diameter. 
 
 gland = 1-5 in. X 1-6 = 2-4 i" . say 
 
 in front of spindle and J in- clear at 
 
 Bottom exhaust opening with crank on top centre = Top 
 
 steam lap -{- Lead — Bottom exhaust lap. 
 Then, 225 + -125 — -25 = 2-125 opening to exhaust. 
 
 bottom). 
 Then, 
 
 of piston and 
 
 port opening compared (foi 
 
 24'-'X-78 54^i8, or A. 
 18 X 1-375 
 
 Area of piston and exhaust port opening compared 
 (crank on top). 
 
 Then. 24- X -7854 = „ or ^r. 
 
 18 X 2-125 
 
X>^t 
 
 Valve (ravel 7' 
 
 ^ea.a 
 
 then, 
 Allow d« 
 Allow pil 
 Then, 
 
 Then, 
 
JD^t 
 
 Va\ve>avcl-7' 
 
 ^ea.a 
 
 then, 
 Allow d« 
 Allow pil 
 Then, 
 
 1 
 
 Then, 
 
}/,X,eU.^i 
 
 <(. 
 
 B-fc. 
 
 i.e»a 
 
 -%■■ 
 
 %' 
 
 5r«»Ui. 
 
 a^V 
 
 2" 
 
 1?,.=V",„ 
 
 !/♦' 
 
 I'/e 
 
 U..^ I'H 
 
 0" 
 
 ■A' 
 
 
 a*- 
 
 ' 3&" 
 
 No. i6.— Inside Steam Piston Valve. 
 
 (Draw to a scale of 3 in. = l ft, ) 
 
 Rule. Diameter of valve rod at body = Valve diameter y, 15. 
 Then, „ ., ., =l5inX'lS = 225'n.say2*i 
 
 Half valve travel = Steam lap + Port opening. 
 Then, „ „ =(Top) 21 in.+l} in. =3! i 
 
 „ =(Bot) 2 in.+ljin. =3li 
 Observe that the difference in lead lop and bollora is also equal to the difference 
 in steam lap and port opening top and hottom (that is, } in. difference). Agani, 
 notice that the sum of *' stea 
 
 
 Thus, Top, 2i in.+J in. 
 
 and Bottom. 2 in.+ a 
 
 5 + lead" is the samt for top and bottom. 
 = 28 i 
 

 -•iWI W9( 
 
 then, 
 Allow dii 
 Allow pil 
 Then, 
 
 Then, 
 
r ■ . 
 
 
 then, 
 Allow dij 
 Allow pi( 
 Then, 
 
 Then, 
 
130X60 
 
 „ depth =262^4875 = 5-37 m ■ say 5^ in 
 As the valve is double-ported, 
 
 then, 5-5-^-2 =;2'75 in , depth of each port 
 
 Note. It should be noted that steam ports only open part width for steam 
 
 admission, but open full for exhiiust ; it is therefore advisable to calculate the actual 
 
 port sizes from the exhaust data 
 
 Half travel — Steam lap+Pert opening. 
 Then, Top 8 ui -^2=4 in , and 4 in. — 2il in, = i; in, port opening lor steam. 
 Again, Bottom 8 in. -2-4, and 4 — !{£ in. -~2^ in, port opening for steam. 
 The difference m steam lap and port opening top and bottom is exactly equal to 
 
 the lead difference top and bottom- 
 Thus, Lead Bottom = i in 
 
 I'fl difference. 
 
 It should be carefully noted that the inner ports of the valve only admil steam 
 to the cylinder, and do not lake exhaust steam ; it is therefore sufficient to make 
 the depth of these ports equal to the port openings for steam. 
 
 For the top this is, as previously shown, i| in., and for the bottom jyV if- 
 which are, therefore, the sizes of the pons referred to. 
 
 Depth of Large Bars. 
 
 Depth = Steam lap -\- Pott opening -|- Metal thickness •{■ Half travel 
 .. =2i + i;-t-li+4'n :-9i m. 
 The depth of the cylinder exhaust port is of no consequence, provided that it is 
 at least equal to twice that of the steam ports. 
 
 Diameter of Valve Rod (Bottom of Thread). 
 
 Rule. /P^?J^a^30X-_2^ Diameter. 
 
 \/ 2600-^-7854 
 Note.— Allow 30 lbs. as the pressure on L H valves, 
 
 2600 lbs, tensile stress per sq in. 
 
 •2 for friction 
 
 lughly 50 in. by 52 
 
 diameter, 
 in Allow die 
 
 So that the stc.-im lap diffun 
 
 mil be 
 1 data given 
 
 . and the porl opening differeni 
 
 NoiE. — The valve face mt 
 rod at gland = diameter at scr 
 
 Therefore, 275X 1-4 = 3-85, say 34 in. diameter, 
 
 The rod is swelled out at top and bottom to 3 in. diameter, which forms the outside 
 diameter of the screw Allow spindle \ ui clear at front and i in clear .it back for 
 
' 
 
 then, 
 Allow di! 
 Allow pil 
 Then, 
 
 Then, 
 
J 
 
 then, 
 Allow du 
 Allow pil 
 Then, 
 
 Then, 
 
No. i8.— Air Pump Complete. 
 
 (Draw to a scale of 2 in. =1 ft.) 
 in. diameter. Stroke. 42 in, Air pump stroke, 
 
 o , rt- _ -^ L.P. cylinder capacity 
 Rule Air pump capacity = ■" — "^ ^■ 
 
 Then, Air pump diameter = /Z4_254f_ — : ^ 24, say 25 in, 
 
 Nnri'.. — 7854 cancels out top and bottom. 
 
 Rule, Diameter of pump rod = Di""eter of pu mp^.e. 
 
 Then, „ „ „ = ^-S+.6 = 3-37 i" , s»y 3* in- 
 
 9 
 
 Rule, Thickness of barrel = Diameter_of_pump + .3. 
 
 Then, „ „ „ = ^ + .3 =1.716 in., say J in- 
 
 Length of barrel /ns/rfe = Stroke + Bucket + Valve depth-t-Clearani 
 
 = 20 + 5 in- + 3! +2 i"- 
 
 NnTK.— Allow, say, I in. clearance top and bottom. 
 
 Then to find 
 
4 
 
 then, 
 Allow d» 
 Allow pit 
 Then, 
 
 Then, 
 
then, 
 Allow dij 
 Allow pil 
 Then, 
 
 Then, 
 
No. 19.— Feed Pump Complete with Air Vessel. 
 
 (Draw to a. scale of 3 in. = i ft. 1 
 
 Daia.— I. HP.. 1500 Engine revolutions or pump strokes, 65 per min. Stroke of pump, 24 in. Steam ( 
 water consumption taken as 15 lbs. per I.H.P hour. , Assume pump efficiency as equal to 50 per cent, 
 Then to find diameter of each feed pump of a pair. 
 
 Pump Plunger. 
 
 Rule I.H.P. Xlbs. waterXa7-66= Diameter=X78s4XStroke in. XStrokes per min. x6ox Efficiency. 
 Therefore, 1500X15x27-66 = Diameter=X-7854X24 in. X65X6ox-5o, 
 
 so that Diameter^ = 1500x15x2766 ^ g 
 
 •7854X24X65X60X-50 ^' 
 
 and Diameter X Vi6-9 = 4 in. diameter of each feed purap plunger. 
 
 Note.— 27.66 cub. in. of fresh water = i lb. 
 
 Relief Valve Spring. 
 
 Rule. iioooxd^= Load c 
 say, 125 lbs. per sq. in. 
 Then 
 
 ) that 
 
 1 valve x: Mean diameter of spring. Assume 1 
 
 oxd' = 3^X -7854x125X3. 
 w:i- 3-X-78S4Xi2 5X3^ 
 
 loading pressure of, 
 
 d~\'-24 = -62 in., say, J in. square steeL 
 ; 1000 — constant for square steel. 
 
 d = side of square of steel spring. 
 Mean diameter of coil:=3 in. 
 
 Then, Capacity of air vessel (exclu: 
 
 s capacity of the pump chamber, and fix dia 
 top and bottom) = 5'-x7854K24 in. xi-7~8o 
 
J 
 
 Then, 
 then, 
 then, 
 Allow dii 
 Allow pil 
 Then, 
 
 w? 
 
 
 Ml 
 
 i' 1 
 
 „£....J i. •. 
 
 i 
 
 Then, 
 
J 
 
 Then, 
 then, 
 then. 
 Allow d« 
 Allow pil 
 Then, 
 
 ^immn 
 
 Then, 
 
No. 19a. Feed Relief, Air Vessel, and Pump Valves. 
 
 (Draw to a scale of 3 in — i ft. 1 
 
 See Drawing 19 No. for calculations and data. 
 
/ 
 
 lUiins \c\ (on 
 
 4 VjUU-lfi 
 
 Then, 
 then, 
 then, 
 Allow dii 
 Allow pit 
 Then, 
 
 Then, 
 
(i 
 
 \\ 
 
 / ,' 
 
 "*.rr": 
 
 -X 
 
tUims t'''l loin 
 4 Ow.u-ire, 
 
 J 
 
 Then, 
 then, 
 then, 
 Allow di) 
 Allow pil 
 Then, 
 
 Then, 
 

 No. 20.— H.P. Piston and Rod (Cast Steel). 
 
 (Scale, 2 in. = i ft.). 
 (Draw to a scale of 2 in = i ft.). 
 
 Da/a.— Piston, 16 in. diameter. 
 Pressure, 180 lbs. 
 
 Diameter of rod at screw (bottom of thread) ; 
 Diameter of rod at body : 
 
 Piston area X Pressure 
 5000 X 7854 ~' 
 
 Piston area X Pressure 
 
 3000 X 7854 
 
 5000 lbs. sq. in. for tensile stress limit. 
 3000 lbs. sq. in. for compressive stress limit 
 
 Diameter of screw __ /16- X 180 . ,. 
 
 (bottom of thread) ~ .y^ "5000^ =3 "». diameter. 
 
 Diameter of rod = 
 
 fier X 180 
 
 3000 
 
 )r, say, 4.^ in. , which allows 
 good margin of safety. 
 
 Allow, Depth of piston at boss = Rod diameter x 1-5. 
 
 Then, Depth = 425 x 1-5 = 63 in., or, say. 6 in. only. 
 
 Allow i of this as taper, and make the remainder parallel. 
 Allow a toper of f in. for 4 in. of length as shown. 
 
 The number and size of studs allowed provide ample strength for the junk ring. 
 A i m. shoulder is allowed for the fitting of the piston on the rod. 
 
 4 
 
lO 
 
 7'- 
 
 Then, 
 
 then, 
 then, 
 Allow dii 
 Allow pil 
 Then, 
 
 Then, 
 
K — lo 
 
 7 
 
 J 
 
 i 
 
 Then, 
 then, 
 then, 
 Allow dij 
 Allow pil 
 Then, 
 
 Then, 
 
No. 21. L.P. Piston and Rod (Cast Steel). 
 
 [Scale, I in. = i ft.}. 
 
 (Draw to a scale of 2 in. = i ft.). 
 
 Dala. -Cylinder, 60 in. diameter. Pressure. 25 lbs. 
 
 Diameter of rod at 1 
 
 (bottom of thread) 
 
 _ /6o- 
 
 V ' 
 
 XJ5. 
 4400 
 
 Diameter of rod at body = /^°12<J5 = i.y [„,, or. say, y in d 
 
 Allow 4400 lbs. per sq. in. for tensile sttess limit (large piston rods) 
 
 ,, 2000 ,, ,, compressive .. ( .. ,. ) 
 
 Depth of piston at boss = Rod diameter X 1-5. 
 
 = 7 X 1-5 = 10 in. 
 
 Allow, say, 7 in, for taper, and 3 in. for parallel portion of rod. 
 
 Thickness of piston at boss fillet = Rod diameter X -288. 
 
 = 7 in X -288 = 2 in, thick. 
 Make thickness of piston near junk ring rather less than near boss, say !■( 
 Thickness of piston rings — :,' in. 
 Diamet>n- of spring coil = ij in. 
 
Then, 
 then, 
 then, 
 
 Allow dij 
 Allow pil 
 Then, 
 
 Then, 
 
I -1 
 
 -'^F^ 
 
Then, 
 then, 
 then, 
 Allow dij 
 Allow pi) 
 Then, 
 
 Then, 
 
No. 22.— L.P. Cylinder Cover. 
 
 Scale, I in. = i ft. 
 (Draw to scale of 2 id. = x ft) 
 
 J Cylinder 
 1 Pressure 
 
 60 i 
 
 ' lbs. 
 
 Allow thickness of cylinder walls to be, say, i^ in. or ij i 
 Then. Thickness of cover =1-25 in. +-25 =1-5 in. 
 
 then, Thickness of cover flange = 1-25 in. X 1-4= 175 in, 
 
 then. Thickness of cylinder flange — 1*25 in. X 1-6 = 2 in. 
 
 Allow diameter of flange studs to be equal to cylinder thickness, that is, i^ 
 Allow pitch of studs to equal 5 stud diameters. 
 Then, 5 X 1-25 in. = 6-25 in. pitch limit. 
 
 Take pitch circle as 64^ in. diameter (centre to centre of flange). 
 Then, 645 in x 3-i4i6-^6-25 in. =32-6, or, say, 32 studs exactly. 
 
 4 
 
Then, 
 then, 
 then, 
 Allow di 
 Allow pi< 
 Then, 
 
 Then, 
 
Then, 
 then, 
 then, 
 Allow di 
 Allow pi 
 Then, 
 
 Then, 
 
No. 23.- Donkey Pump Cylinder and Valve. 
 
 I Draw to a scale of 6 in. ^r^ i foot.) 
 Valve travel— I ^ in. Cut off := 9 stroke, 
 NOTE -As this engine is not fitted with a connecting rod, equal steam lap and lead is gi\ 
 
 VT^Valve travel = i4" 
 
 C . Cut-ol) = •'i 
 
 o)5tr<.(fe 
 
 1 = 
 
 Lead 
 
 TqIo 
 
 BC?? 
 
 / 
 
 ^h" 
 
 S = 
 
 Steam 
 
 I ah 
 
 t; 
 
 t.' 
 
 p. 
 Port 
 
 % 
 
 t; 
 
 Clearance 
 
 % 
 
 V 
 
 . at either end of the valve. 
 
 Da^a. Pressure, 180 lbs. Revolutions, 72 per 
 
 Stroke, 8 i 
 
 N- > II., —Stroke -|- Piston -j- Top and bottom clearance = Length of 
 cylinder. 
 
 Then, Length = 8+11+ ;,, + ,'■, - io\ in. 
 
 Piston Rod Diameter. 
 
 Allow a compressive stress limit of, say, 3000 Ibs- per sq, in. 
 
 Then, Diameter of rod (at body) = /6-X-78S4Xi8o_ j -^^ j^ j^ 
 
 V 3000 X -7854 
 Thickness of Cylinder. 
 
 Rule, Thickness = ^'^"^^^^'^.T'.^^^^ + -25. 
 
 5000 ' ^ 
 
 Th.n, Thick: 
 
 . Diameterx Pressure 
 
 5000 
 . 6in. X180 , 
 5000 
 
 "+■25= : 
 
 I., say A in. 
 
 Steam Port Areas. 
 
 Allow speed of exhaust steam to be. say, only 20 ft. per second 
 
 Rule, Piston areaX stroke in ft. X2X Revolutions = 20 X 60 X Port area. 
 
 Then, 6-X-7854X ,^5X2X72 = 20X6oX Port area. 
 
 e .. . D (. 6-X7854X,'',X2X72 
 
 So that, Port area = 1 -j-i =226 sq. m. 
 
 20 X 60 ^ 
 
 Depth of port = 2-26 -;- 4 in. = -56 in., say \ m. deep. 
 
 NoTR.- Width of port=^4 in. 
 
 Allow depth of exhaust port to be equal to twice that of the steam 
 
 ports, therefore ^ in. x 2= i,|i in. 
 NoTF,. -For small sizes of auxiliary engine cylinders the steani speeds 
 
 allowed per second are much less than for main engines. 
 
The ex; 
 
 Note.— Depth of key: 
 
 Thickness „ I 
 
 Observe that "linked uf 
 
 horizontal 
 
■4 1 
 
 
 {i:>iiq 9^y 
 
Note. 
 
 The ex; 
 -Depth of key:^ 
 
 Thickness ,, 
 Observe that "linked up 
 horizontal 
 
No. 24. — Eccentric and Rod Complete. 
 
 I Draw to a scale of 2 in, — i ft, ) 
 Data Shaft 14 in diameter. Valve travel 7 in. Diameter of valve spindle (d) 3^ 1 
 say j8 in. 
 
 Rule Diameter of pulley — d a. y-Z = 35 x 7-8 = 27-3 
 Diameter of bolts and studs — (dx -S) + -2. 
 
 Diameter of eccentric rod pins ^ d x -85 + -5 = 3-47 
 , Shaft diameter 14 in, 
 
 key- 6 = .- =233 
 
 
 
 Depth of c 
 
 Diameter of bolts in top end brass = . / 
 Thickness of cap and butt = diameter or bolts x 1-33 
 
 diameter or one strap bolt - 
 
 say 1-5 I 
 = 1-5 in. X 
 
 ■■33= '-99 ■" . say ; 
 
y 
 
 The ex; 
 NoTE.—Depth of key = 
 
 Thickness ,, 
 Observe that "linked uf 
 horizontal 
 
■ ' i 
 
The ex 
 Note. — Depth of key = 
 
 Thickness ,, 
 Observe that "linked ut 
 horizontal 
 
No. 25. -Quadrant Bars, Valve Eye Block, and Drag Links. 
 
 (Draw to a scale of 2 in. = i ft.) 
 
 Valve travel, 7 
 
 n. Diameter of valv 
 
 e spindle at bod 
 
 .31 in 
 
 = </. 
 
 Rule, 
 
 Distance between 
 
 bars = dxi-7S' 
 
 h-25- 
 
 
 Then, 
 
 
 ■ . =3-5X175 
 
 + ■25 = 
 
 6-37, say 6 
 
 Diameter of valve rod eye (steel) =: ixdepth of bars. 
 Then. ,, ., .. ,. —1X5 in, =5111, 
 
 Allow eye block brass to be. say, i in. thi.k. 
 
 Length of slipper = c/X3-6. 
 Then, ., ,, = 3-5 x 3-6 = 12-6, say 12^ in, 
 
 Allow thickness of slipper to be about i in. at centre. 
 Allow eye block thickness at sides to be about ,' in. 
 Allow eye block thickness at top and bottom to be about 1} in. 
 
 Diameter of bolts in eye block — dx-5-f -2. 
 
 = 3-5X-5+ 2^i-95- say : 
 Diameter of drag links (2):=(/x*7Z. 
 
 — 3-5X72 = 2-52. say 2A in. 
 NoiE. For other proportions of quadrant bars and eccentric rods. pins. 
 
0^ 
 
 The ex; 
 Note.— Depth of key:j 
 
 Thickness ,, 
 
 Observe that "linked uf 
 
 horizontal 
 
(jy 
 
 The ex: 
 Note. — Depth of key 
 
 Thickness ,, 
 
 Observe that "linked u] 
 
 horizonta 
 
No. 26— Reversing Gear Bell-Crank and Expansion Slot. 
 
 ( Draw to a Scale of 3 in. = i ft. ) 
 The expansion block has a range of 4 inches in the slot. 
 
 NoTF,.— Depth of key = 
 
 shafc diameter 
 
 +•125= 
 
 _ 5 inches 
 
 •125=1375, 
 
 lil inches. 
 
 Thickness „ = Depth x-5 = -6875, or }} inch. 
 Observe that "linked up" ahead becomes "full gear" astern, owing to the change from the 
 horizontal position to the vertical position of the expansion slot. 
 
CXD 
 
 
 -5 — 
 
 i! t^ 
 
 No. 26— Re 
 
 The ex 
 
 No IE. — Depth of key 
 
 Thickness ,, 
 
 Observe that "linked u] 
 
 horizonta 
 
No. 26. —Re 
 
 The ex 
 Note. — Depth of key 
 
 Thickness ,, 
 
 Observe that "linked uj 
 
 horizonta 
 
No. 27 —Crank Shafting. 
 
 (Sca/f, i in. = 1 fi.) 
 (Draw to a scale of i in. = i ft.) 
 
 Rule 
 Where 
 
 Data. —Cylinders 30 in., 52 in., 80 
 Stroke, 48 in. 
 Boiler steam, 1S5 lbs. 
 
 C X P X D- = S' X Constant 
 
 (^+"> 
 
 C = Length of crank. 
 P =^ Absolute boiler pressure. 
 D = L. P. cylinder. 
 d=H.P. 
 
 S = Shaft diameter. 
 Constant = 1110 for propeller shafts and crank shafting. 
 = 1295 ,, tunnel shafting. 
 C X P X D- 
 
 S==- 
 
 Constant X (2 + ^")' 
 X 200X 8o=_,„. 
 
 -(^+i) 
 
 S (shaft diameter 
 
 ^1.2=14-5 >n-. or. say. 15 ; 
 Note. — Observe that cube root extraction is required. 
 Note.— Stroke = 48 in. therefore crank (C) =24 in. 
 
 185+15 = 200= P. 
 Diameter of couplings = Shaft diameter X 2 (at least). 
 
 = 15 X 2 = 30, say 31 in. diameter. 
 
 Thickness of couplings = shaft x 3. 
 
 = 15x3=4-5 in- 
 Coupling fillet radius ^= shaft X -2. 
 
 = 15 X •2 = 3 in. 
 Bolt pitch circle diameter = shaft X i-S- 
 
 = 15 X 1-5 = 22-5 1 
 
 Bolt diamater = / Shaft diameter- X half shaft radius 
 V Bolt pitch radius X number of bolts 
 
 ^ / i5"XI7-5 in.H-2, 
 V 11-5X6 
 
 = 3-5 (nearlyi say, 3-5 in. diameter. 
 
 Six bolts have been allowed. 
 Bolt radius =23 in. ^-2=11-5. 
 Thickness of crank webs = shaft X 7- 
 
 = 15 X 7 = 10-5. or, say. 11 in. 
 Diameter of web bosses = shaft X 2. 
 
 = 15x2 = 30 in. 
 Allow length of crank pin := Diameter of crank pin = Diameter of shaft 
 Therefore. Crank pin = 15 in. x 15 in. 
 
 Length from centre of coupling to centre of crack pin is equal to half 
 length of pin + web thickness 4- clearance + twice pulley thickness + length of 
 bearing + clearance and coupling radius + coupling thickness- 
 Allowing pulley thickness as 4I (eathi and bearing 15 m. length. 
 Then. 
 7.5+ii-Uiin. +gin. + I5in +1 in. + 3 in. + 4-5 in, = 52 in. centres 
 
35- 
 
 3-0 
 
 No. 28.— Thrust Shaft and Shoe. 
 
 (Draw to a scale of li in. =1 ft.) 
 /(^^ compute design calcuhtioiis see Drawing No. 29. 
 
 ^ 
 
 I 
 
 ^i|,^Oi|^ 
 
 ^^a Rhial oil :iir^,rf 
 
 V.)-.r 5tr„ci 
 
 B«/a.— I.H.P. 1500. 
 
 Speed, 10 knots. 
 Pressure on shoes 
 Ahead surface - 
 Astern ,, 
 
 60 lbs. per 
 567 sq. in. 
 
 Notice that the actual bearing surface is equal to about 5 only of the total surface of the 
 shaft collars. 
 
 Then, Shaft + clearance = 12 in. + i in. + i in. = 13 in. 
 
 Annulus area of collar = (18-— 13'-) X -7854= I2I-7 sq. in. 
 Actual bearing surface^ 121-7 X § =8i-i. 
 As there are 7 shoes for ahead, then, Si-i X 7 = 5677 sq. in. 
 ,, ,, 6 ,, astern, ,, 8l.ix6 = 486.6 sq. in. 
 
 Total pressure on block = L5™ ^JSMOX^S = 33218 
 •^ 10 X 6080 ^■^ 
 
 lbs. 
 
 Pressure per square inch on each shoe = ^^ — = 58 lbs. , or, say. 60 lbs. 
 NoiE.— Allow .68 of total I.H.P. as effective power on block. 
 
shaft. 
 
 5o tnat, b (diameter ot snatt) = \'i5o» = 11-5, nearly, say, 12 in. 
 
 Observe that cube root extraction is required. 
 Stroke. 42 in. -^ 2 = 21 in. leng-th of crank. 180 + 15 = 195 lbs. absolute. 
 
30 tnat, s (diameter ot snatt) = \'i5o8 = 11-5, nearly, say, 12 in. 
 shaft. 
 
 Observe that cube root extraction is required. 
 
 Stroke. 42 in. -f- 2 = 21 in. leng-th of crank. 180 + rS = ^95 lbs. absolute. 
 
.MO. 29 -Thrust Block. 
 (Draw to a scale of l^ in. = i ft. 
 Data.~l. HP. 2000. Ship speed, 15 knots. To find required bearing surface of shoes 
 allowing a, maximum of fio lbs. per sq. in., and 7 shoes to be fitted. 
 
 Then Total pounds pressure on block = -li^?--^-?i°9?l^. 
 Speed in feet per 
 
 ^2000X3300Ci><:68^ lbs. nearly, 
 
 1520 •" 
 
 Speed in feet per 
 
 The effective I HP. on thrust block is generally assumed as equal to 68 per cent, of 
 total I.H.P 
 
 Pressure on each shoe = ^°°°°- = 4J00 lbs, nearly. 
 
 Bearing area of each shoe = ^^ = 7l'6 sq. in. 
 Diameter of collars = Shaft diameter X 1-6. 
 
 = 13'375XI-6 = 2I in. 
 Thickness of collars = Shaft diameterx-i5 
 
 = I3-375X-I5 = 2 in- 
 Thickness of shoes = Collar thickness X 2 
 = 2 in.X2 = 4 in. 
 Thickness of white metal = i,Collar thickness H- 51 +'oS, 
 
 ,, =2-^5 + -o8 = -48 in. 
 Distance between collars = 5 in. 
 Allowing a stress of, say, 2200 lbs. on side stay bars, then, 
 
 y>^ = 2-9 in., or say 3,[ in. diameter over 
 
 2200x2x7857 
 
 : of bars= / - 
 
 S' 2 
 
* - "^^ fr Sh££T ido^ LlOS 
 
 SO tnat, s (diameter ot snatt) = \'i5o» = ii-5, nearly, say, 12 in. 
 shaft. 
 
 Observe that cude root extraction is required. 
 Stroke. 42 in. -^ 2 = 21 in. leng-th of crank. 180 + 15 = 195 lbs. absolute. 
 
^ hS^e£f \(io») Lios 
 
 shaft. 
 
 3o tnat, a (diameter ot snatt: = \'i50J5 = ii-s, nearly, say, 12 in. 
 
 Observe that cude root extraction is required. 
 Stroke. 42 in. ^ 2 = 21 in. length of crank. 180 + 15 = 195 lbs. absolute. 
 
£>a<a. — Cylinders. 24 in. —40 in., 66 in. 
 Stroke. 42 in. 
 
 Boiler pressure, 180 lbs. 2;auge. 
 Diameter of tunnel shafting, il^ in. 
 Shaft. 12 in. diameter. Length of taper. 
 
 30 I 
 
 Allow thickness of brass liner to be J in. at forward end and 
 ■rs less at after end to allow of easy withdrawal and insertion 
 of the shaft. 
 
 For the same reason make diameter of tube shoulder at forward 
 c-nd (22 in.) J in. more than diameter of shoulder at after end 
 {2ii): this is important. 
 
 Allow a taper of about f in., or \ in. per. foot, which reduces 
 the shaft diameter from 12 in. to about ^a\ in., as shown. 
 
 Allow lignum strips of i in. by 2\ in. or "3 in. 
 
 No. 30.— Stern Tube and Shaft. 
 
 iScafe, { in. = 1 ft \ 
 
 { Draw to a scale of i J in. = i ft. ) 
 
 Allow length of after bearing (lignum vitse) to be equal to four 
 times diameter of shaft. Then, 12 in. x 4 in. = 48 in. length of 
 wood in bearing. 
 
 Observe the lip (| in. thick) cast on the forward end of the 
 brass bush to hold the wood in place, also the check ring fitted 
 aft for the same purpose. 
 
 NoiE.— The sectional view on line A B is drawn to double the 
 scale of the other vievr. 
 
 The di.imeter of the shaft is determined as follows : — 
 
 Rule, C X P X D= = S» X Constant X ( ^ + '^^ )■ 
 
 Where, C = Length of crank. 
 
 P = Absolute boiler pressure. 
 
 D = L P. cylinder 
 
 </= HP. cylinder. 
 S = Shaft diameter. 
 Constant = mo for propeller shafts and crank shafting. 
 ., =^ 1295 for tuimel shafting. 
 en _ C X P X D- 
 
 Constant X ( z + —_ V 
 
 21 X IQS X 66- 
 
 IIIOX 
 
 = 1508. 
 
 24-/ 
 
 (diameter of shaft' = \ 1508 
 
 11-5, nearly, say. 12 i 
 
 Observe ihat cube root exiraction is required. 
 Stroke, 42 in. -;- 2 = 21 in. length of crank. 180 + 15 = 195 lbs. absolute. 
 
-^4' 
 
 3/ 
 
 ^ 
 
 
 Then, 
 
 d= H.P. cylinder. 
 S = Shaft diameter. 
 Constant = mo for propeller shafts and crank shafting. 
 ,, = 1295 for tunnel shafting. 
 
 g.; _ C X P X D2 
 
 Constant X I 2 
 
 +§:)■ 
 
 53 _ 21 X 195 X 6 6- 
 
 1508. 
 
 So that, S (diameter of shaft) = X'lSoS^ 11-5, nearly, say, 12 in. 
 shaft. 
 
 Observe that cube root extraction is required. 
 Stroke. 42 in. ^ 2 = 21 in. length of crank. 180 + 15 = I95 lbs. absolute. 
 
'^ 
 
>K- 
 
 IS' ^4^ 
 
 > 
 
 S/B 
 
 ih^ 
 
 wi|<-- /a'--^ 
 
 ^"^r 
 
 c 
 
 fc 
 
 7-7^r^W^ 
 
 \k^ 
 
 ;^' 
 
 m. 
 
 
 s 
 
 I r 
 
 !<-t /(?'-^;< /(9 --> 
 
 ■lO 
 
 I ^ 
 
 V^ 
 
 I 
 
 -H 
 
 1 
 I 
 
 ^<x^^c ^x\ : ,^ ^ 
 
 ^ 
 w 
 
 
 3* 
 
 ^ 
 
 
 ± _ 
 
 Then. 
 
 d= H.P. cylinder. 
 S = Shaft diameter. 
 Constant = mo for propeller shafts and crank shafting. 
 ,, = 1295 for tunnel shafting. 
 
 S' = C X P X D- 
 
 Constant X ('2+^^ 
 
 So that, S (diameter of shaft) = Vi5o8 = 11-5, nearly, say, 12 in. 
 shaft. 
 
 Observe that cube root extraction is required. 
 
 Stroke. 42 in. ^ 2 = 21 in. length of crank. 180 + rS = 195 lbs. absolute. 
 
No. 31.— Propeller Boss. 
 
 (4 Bladed Propeller.) 
 (Scale, 1 in. = i ft) 
 I Draw to a scale of i^ in. = 1 ft.) 
 
 Da/a.— Cylinders 
 
 I.H.P. 
 
 Pitch of propeller 
 
 Diameter of propeller - 
 
 Circumference of propelle 
 
 Slip per cent. 
 
 Tunnel shaft 
 
 Propeller ,. - 
 
 1600. 
 16 ft. 
 
 10 per cent. 
 
 11^ in. diameter. 
 
 Length of boss ^ Tail shaft diameter y 2-6 ft. 
 
 — 12 in. >■ 2-6 = 31-2 m , or. say. 
 Diameter of boss — Shaft diameter X 2^— 30 in, 
 
 of blade flange = Shaft diameter x 2-i. 
 
 = 12 in. X 2-1 =25-2. or, say. 25^, 
 Thickness of blade flange = Shaft diameter x -25. 
 
 ». " = 12 in. X -25 — 3 in. (bronze j. 
 
 Combined area of studs"! cu n ^/ , 
 
 for each blade j = ^^^^^ ^^^^ ^ "^^^ 
 
 Combined area of studs \ „., ,, „-,„ , „ 
 
 for each blade / = '^- X -7354 X -22 = 24-8 sq. m. 
 
 Allowing 8 studs per blade. 
 , 24-8 -^8 = 3-1 sq. in. area of each stud. 
 
 V 7854 
 
 Shaft diameter 
 
 Then, 
 
 So that, Diameter of studs 
 
 Breadth of key 
 
 say, 2 in. diameter. 
 
 . bf key 
 
 -f- -6. 
 = " + -6 = 26. or 2!; 1 
 
 = Breadth of key X -5. 
 = 2-625 in X 5 = 1-3125. 
 
 The boss is recessed uul to fil the blaclt flanges al an angle of 
 60 degrees. 
 
 NoTF.- Blades of bronze. Boss of cast steel. 
 
8 JOINT. 
 
 4 BOLTS SCREWED' ^ 
 
 INTO PIATE AND RIVETTED 
 
 No, 32— Bottom Blow Down Cock. 
 
 (Ship's Side. 1 
 
 (Draw to a scale of 6 in. = 1 ft) 
 
 Boiler pressure, 180 lbs. gauge per sq. in. 
 
 Least aroa of port = Area of pipe. Taper of plug = 3 in per ft. 
 
 Mean width of port = ^'5+^ — 2.25 
 
 Area of port = 4X2-25 = 9 sq. in. (approximately) 
 „ pipe = 3" X 7854 = 7 sq. in. 
 Allow a stress of 3000 lbs, per sq, in, on the four studs. 
 1- /5'X-7854Xi8o _ , . , ■ J. 
 
 Diameter of studs : 
 
 N.iM- Studs of i in, diameter would be sufficient, but to allow for a margin of safety say 
 ^ diameter. 
 
 Tnn.r „r i,„ h. I J /Mean circumference of i)lug . 
 
 Lover or lap when dosed = (^ I- ^"j-iMean width of port). 
 
 I i )- (2.25) =4.42 in. 
 
 2 '" =4'^5 in. mean diameter of plug, i 
 

I 
 
Dl^j 
 
 51 II 
 
? 3-^ ^ -. 
 
 Q;a"o jj.™ 
 
 . =. 2. r^ C < 
 
 -^ CL =r '^ J5 
 
 3 3 t; ■o g 
 
 
 3 » Z 
 a '^ o 
 
 
 3 " 2, 
 " o o 
 
 O S' • 3 
 
 qs 
 
 X g g- ° 
 
 1 S-' S" S 
 
 5| 
 ■§ i 
 
 ^_ cr 
 
 'J//V y- ^H. A y. A A i> ~ ^" i_ 
 
s- III 
 
« 
 

No. 34. Main Bearing. 
 
 iSca/e, 1} /n. = 1 ft.) 
 ( Draw to a scale of 2 in. — x ft. ) 
 
 Oafa.— Cylinders 24. 38, 64 ill, H.P. steam, 180 lbs. Allowing a tensile stress limit of 3300 lbs. pe 
 sq. in. , then the diameter of the bolts can be found as follows ; 
 
 ;.P. areax Pressure 
 4x3300x7854^" 
 
 /Hi 
 Rule, Holding down bolt diameter = . / — '- 
 
 Then, HoldmE down bolt diametcr = . /^'t"^'?°=2-6, say 2j in. diameter (bottom of thrcadl. 
 
 V 4x3300 
 
 Note. — Allow a tensile stress of 3300 lbs. per sq. in. 
 NoTE—7854 cancels out top and bottom. 
 
 XoTi!.— The total load on each crank is taken up by a pair of main bearings, hence 4 bolts 
 Thickness of white metal = -04 X Diameter of shaft + ■! in. 
 
 = -04Xi3-375 + -i = -635in., say 8 in. 
 
 Thickness of metal (W.M. included) = Diameter of shaft X -144 + -3. 
 
 = 13-375 X ■■44 + -3 =2-22, say 2i in. 
 Thickness of caps = Bolt diameter X 7+ Bolt pitch X -l. 
 
 = 275x7 + 245 XI = 4-37 in. say 48 in. 
 
o 
 
 -i-- 
 
'1 
 
 M 
 
o 
 
 -4- 
 
i 
 
 6 fhreads p«r it\cr 
 \^Hord wood seot". 
 
 No. 34a —Tunnel Bearing Block 
 
 Scale = 14 in. per ft. 
 
 ( Draw to a scale of 2 in. = 1 ft. ) 
 
 The size of the holding down bolts depends on the shearing stresses set up by the rolling or pitching of the vessel. 
 White metal at thickest part = shaft diameter X 05 = 14 X 05 = 7 in., say i' in. 
 
I I 
 
 -J®L. 
 
 ir^ boov. 
 
I. 
 
U-J^ 
 
 No. 35— Steam Pipe Expansion Joint 
 
 (Draw to a scale of 3 in. = 1 ft.) 
 
 {Pre^surfi, 180 lbs. per $q. in.) 
 
 Diameter of Tie Bolts. 
 
 Allow a tensile stress of 3700 lbs. per sq. in. on the bolts. 
 
 Then, Diameter of each tie bolt= /~^''- = 1.24 ic, say li in. diameter. 
 
 V 2x3700 1 ' ^ » 
 
 Note. — The pressure is taken as acting on an 8 in. diameter circle, in place of that of the pip** bore. 
 
/ 
 
 .' J B » 
 
w 5, » 
 
 D. S O ~ „ "■• = 
 
 ? _ ?^ ;i 3 2 
 
 ^ 
 
 s 
 
 ■ s 
 
 '■ S , . 
 
 3 
 &. 
 
 3 
 
 5 
 
 m "■ 2, 
 
 J3 O 
 
 S. 5 S 
 
 
 
 
 n 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 s. 
 
 s 
 
 "' 
 
 
 
 g" ■" 3- 
 
 ■^ i o 
 
 
 
 V 
 
 «s 
 
 •n 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 S- 
 
 • ■ c 
 
 
 ^ 
 
 
 
 
 
 
 
 o 
 
 ■"■ 
 
 3 
 
 o 
 
 
 
 n 
 
 
 & 
 
 S" § 5- 
 
 ^ a. ft 
 
 
 
 ^ 
 
 
 •o 
 
 -, 
 
 _ 
 
 ■U N 4k (0 
 
 — 
 
 
 3 
 
 
 
 
 
 '^ 
 
 ■' 
 
 r 
 
 n 
 < 
 n 
 -J 
 
 1 
 
 
 "- -. 3' 5' 
 3 ? ■ • 
 
 
 
 
 3 1 ^ 
 
 1 
 
 n 
 
 II 
 
 
 
 4k 
 
 
 
 
 a- 
 
 3 s S. 
 1 f i 
 
 
 
 
 
 
 
 Sit 
 
 
 ;r5 
 
 
 
 1 
 
 
 
 
 
 
 
 In 
 II 
 
 II 
 
 e. 
 
 2 ^ 
 
 
 
 a 
 
 B « »• 
 
 
 
 
 
 
 
 S 5-S- 
 
 o :t 
 
 -. o y 
 

§ SfggI pi A 
 
 Data. -Cylinders, 24 in.. 40 in-, 66 in. 
 Stroke, 42 in. 
 Boiler steam, 170 lbs 
 Crank pin, 124 in. diameter by 14*1 
 Crosshead pin, 6^ in. diameter by t 
 Piston rod, 6^ in. diameter. 
 
 No. 37.— Connecting Rod. 
 
 [Scale I in. = 1 ft.) 
 (Draw to a Scale of i^ in. = i ft.) 
 
 Allow a tensile st 
 
 rentre, to be equal to 
 
 Allow length of nid, (x\ 
 stroke x 2-3. 
 
 Then, 42111. X2-3 = 966, or, say, 98 in. 
 
 Make diameter of rod at small end equal to diameter of 
 piston rod, and allow i in. taper in length, which gives 
 6i in. and 7^ in. as the two diameters. 
 
 Make thickness of jaw := rod diameter at top X -55- 
 
 Then, 6-5 in. X -55 = 3-57 ">■■ or, say. 3g in. thick. 
 
 Inner radius of jaw, 5 in., and outer radius = 5 in. 4-3I in.=8fi in. 
 
 .\fter striking oft" the jaw curve at Sj; in. radius, continue 
 the line of jaw into rod with a ho" angle set square, as 
 shown. 
 
 Width of jaw = diameter of rod (small end) x i*i. 
 
 Then, 6-5 in. X i-i =7-1 in., say 7 in. width. 
 
 Diameter of bottom end bolts = / -^^-?-"_P>?t?H_. 
 (2 bolts) V 2 X stress X -7854 
 
 Diameter of top end bolts = /j-oad^njiston . 
 (4 bolts) V 4 X stress x ■7BS4 
 
 of 4000 1 
 
 Diameter = /^^l ><i7o ^ 3.^9, 
 V 2X4000 ^^^ 
 
 . tensile stress of. 4000 I 
 
 end bolts. 
 Then, 
 
 per sq. in. on bottom 
 
 . say, 3-5 1 
 .. per sq. 
 
 diameter. 
 1. on tcp end 
 
 diameter. 
 
 Diameter = / ^^' ^172 — 2-47, or. say, 25 i 
 
 V 4 X 4000 
 
 Thickness of connecting rod butt = bolt diameter x 1-32. 
 Then, 3-5 in. X 132 = 4-62 in., or. say, 48 in. ihck. 
 Thickness of butt at jaws = bolt diameter X i-2. 
 Then, 2-5 x 1*2 = 3 in. thick. 
 
 The thickness of the cups, lop and botlur 
 L-ss than thai of the butts, as will he ohser\ed. 
 
 Total thickness of metal round crank pin and < 
 = pin diameter X -16. 
 Then, 12.5 X -16= 2 in. (bottom end), 
 
 and, 6-5 X -16= 1-04 in. (top end). 
 
 is ^lit;hll, 
 osshead pin 
 
 edured 
 
 Allow thickness uf white nielal ': in. lo 
 to \ in. between n-ccssuil dovtiails. 
 
 Depth of nuts + collars = diameter of bolts (at leasi). 
 Width of bottom end butt and cap = bolt diameter X 2-6. 
 
 Then. 3-5 in. X 2-6 = 9-10 in., or. say. 9^ in. 
 
 Width of top end butt and caps = length of crosshead pin, Icsa 
 clearance at sides. 
 
3^^'' 
 
Gg 
 
 ^^-^ 
 
No. 38- Pump Crosshead and Links. 
 
 iScale, i in. =1 //.) 
 (Draw to a scale of ij in. = i ft.) 
 
 „ f Air pump, 24 in. diameter. 
 
 1, Circulating pump, 18 in. diameter. 
 
 Feed pumps (2), 4 in. diameter. 
 Bilge „ (2), 4 
 
 For pumps of llie sizes given, tlie above are tlie average dimensions and proportions adopted in practice. 
 
'f^ 
 
If. 
 
 No 7— Steam Stop Valve and Seat. 
 
 The valve seat is made of brass. 
 
 The valve is made of brass. 
 
 The seat is secured by three set pins ^"' diameter. 
 
 No. 8- -Valve and Seat for Spring Safety Valve- 
 
 The valve is made of brasa. 
 The spindle ,, ,, 
 
 A pair of valves as shown 
 100 square feet of gyrate. 
 
 sufficient for 
 
SECOND CLASS DRAWINGS. 
 
 (Given at Board of Trade Examinations.) 
 
 Under the revised Regulations for Second Class Certificates (191 7), candi 
 dates are now required to make a sketch or, if preferred, a scale drawing' 
 of some simple part of the machinery or boilers. 
 
 The following drawings, which are fully dimensioned, should be carefully 
 copied out for practice, either by hand sketch or roughly to scale, and if the 
 latter, the scales marked for each drawing should be employed. 
 
 LIST OF DRAWINGS. 
 
 (SECOND CLASS.) 
 
 NOTE.— It is important that all sizes be marked on the drawings. 
 
 1. Main Bearing Bolt, complete. 
 
 2. Bottom End Bolt, complete. 
 
 3. Tapered Coupling Bolt, complete. 
 
 4. Distance Piece for Bottom End Brass. 
 
 5. Main Bearing " Brass." 
 
 6. Bottom End Brass. 
 
 7. Steam Stop Valve and Seat. 
 
 8. Safety Valve, Seat, and Spindle. 
 
 9. Winch Slide Valve. 
 ID. Slide Valve Spindle. 
 
 11. Eccentric Pulley. 
 
 12. Eccentric Strap. 
 
 13. Crank Shaft and Webs. 
 
 14. Thrust Shaft. 
 
 15. Tail End Shaft. 
 
 16. Piston Rod and Crosshead. 
 
 17. Guide Shoe. 
 
 18. Gland and Stuffing Box. 
 
 19. Winch Cylinder Piston. 
 
 20. Air Pump Valve. 
 
 21. Feed Pump Plunger. 
 
 22. Tee Piece for Steam Pipe. 
 
 23. Link and Lever for Indicator Gear. 
 
 24. Box Spanner. 
 
 25. Spanner. « 
 
 26. Boiler Manhole. 
 
 27. Fire Bar. 
 
 28. Fire Bar Bearer. 
 
 29. Stay Tube and Common Tube. 
 
 30. Tube Stopper. 
 
 31. Combustion Chamber Girder. 
 
 32. Double Butt Strap Joint. 
 
 33. Main Stay. 
 
 34. Combustion Chamber Stay. 
 
 35. Double Riveted Lap Joint. 
 
 36. Crank Pin Disc for Winch. 
 
 37. Check Valve Chest Cover and Spindle. 
 58. Hand Wheel for Steam Stop Valve. 
 
 39. Air Vessel. 
 
 40. Water Gauge Column Bracket. 
 
SECOND CLASS DRAWINGS. 
 
 (Given at Board of Trade Examinations.) 
 
 Under the revised Regulations for Second Class Certificates (191 7), candi 
 dates are now required to make a sketch or, if preferred, a scale drawing' 
 of some simple part of the machinery or boilers. 
 
 The following drawings, which are fully dimensioned, should be carefully 
 copied out for practice, either by hand sketch or roughly to scale, and if the 
 latter, the scales marked for each drawing should be employed. 
 
 LIST OF DRAWINGS. 
 
 (SECOND CLASS.) 
 
 NOTE.— It is important that all sizes be marked on the drawings. 
 
 1. Main Bearing Bolt, complete. 
 
 2. Bottom End Bolt, complete. 
 
 3. Tapered Coupling Bolt, complete. 
 
 4. Distance Piece for Bottom End Brass. 
 
 5. Main Bearing " Brass." 
 
 6. Bottom End Brass. 
 
 7. Steam Stop Valve and Seat. 
 
 8. Safety Valve, Seat, and Spindle. 
 
 9. Winch Slide Valve. 
 
 10. Shde Valve Spindle. 
 
 11. Eccentric Pulley. 
 
 12. Eccentric Strap. 
 
 13. Crank Shaft and Webs. 
 
 14. Thrust Shaft. 
 
 15. Tail End Shaft. 
 
 16. Piston Rod and Crosshead. 
 
 17. Guide Shoe. 
 
 18. Gland and Stuffing Box. 
 
 19. Winch Cylinder Piston. 
 
 20. Air Pump Valve. 
 
 21. Feed Pump Plunger. 
 
 22. Tee Piece for Steam Pipe. 
 
 23. Link and Lever for Indicator Gear. 
 
 24. Box Spanner. 
 
 25. Spanner. 
 
 26. Boiler Manhole. 
 
 27. Fire Bar. 
 
 28. Fire Bar Bearer. 
 
 29. Stay Tube and Common Tube. 
 
 30. Tube Stopper. 
 
 31. Combustion Chamber Girder. 
 
 32. Double Butt Strap Joint. 
 
 33. Main Stay. 
 
 34. Combustion Chamber Stay. 
 
 35. Double Riveted Lap Joint. 
 
 36. Crank Pin Disc for Winch. 
 
 37. Check Valve Chest Cover and Spindle. 
 
 38. Hand Wheel for Steam Stop Valve. 
 
 39. Air Vessel. 
 
 40. Water Gauge Column Bracket. 
 
- 4-^- -\ 
 
 No. I.— Main Bearing Bolt. 
 
 (Draw t'j u 3" scale.) 
 
 The total stress on bolt = Area of bolt x 3000 lbs. =275^ x iTx 3000= 17820 lbs. 
 The bolt is made of mild steel, 3I threads per inch. 
 The nuts are made of iron. 
 
 NOTE. — Allow 3000 lbs. tensile stress per [77]. 
 
 "Verbal'' Notes and Sketches. 
 
! I 
 
 I 
 
No. 2 — Bottom End Bolt. 
 
 (Draw to a 3" scale.) 
 The diameter of the rod is 6". 
 The bolt is made of steel. 
 
 Verbal '" Notes and Sketches. 
 
7ioH Dnji raojjoti i. .oM 
 
No. 3— Tapered Coupling Bolt 
 
 I Draw til a 4" scale. I 
 The bolt is made of mild steel. The diameter of the pitch circle is i? 
 
 The I.H.P. of engines is 1200. The number of bolts is 6. 
 
 The diameter of shaft is 12 . The revolutions per minute are 65 
 
 L£ Dowel PinS 
 8 
 
 Brass StriPJ 
 
 
 No. 4.— Distance Piece for a Bottom End Brass 
 
 I Draw to a 4 " scale. ) 
 The diameter of the bolts is 3V'- 
 
 ,. ,, connecting rod is 1". 
 
 Verbal" Notes and Sketches. 
 
ho 
 
 
 
 "rt 
 
 c 
 
 
 
 
 <Tt 
 
 
 
 
 lU 
 
 OQ 
 
 
 c 
 o 
 
 .5 
 
 c 
 
 — . 
 
 
 ^ 
 
 c« 
 
 
 
 o 
 
 S 
 
 
 o 
 
 
 
 5 
 
 
 el 
 
 
 rt 
 
 
 S 
 
 
 n 
 
 h 
 
 
 V) 
 
 
 
 
 V 
 
 . 
 
 w 
 
 u 
 
 
 
 cd 
 
 vS 
 
 rt 
 
 ~ 
 
 r 
 
 5 
 
 u 
 
 ^_^ 
 
 Wl 
 
 
 n 
 
 
 in 
 
 fV) 
 
 
 
 en 
 
 c 
 
 
 
 
 
 
 
 
 
 in 
 
 
 ^ 
 
 
 o 
 
 
 
 
 2 
 
 
 JS 
 
 j= 
 
 CVi 
 
 H H 
 
 D__ 
 
 I" 
 
 lJ 
 
CI 
 
 OQ 
 
 
 
 A 
 
 
 
 i 
 
 t 
 
 
 
 ''' » 
 
o 
 
 o 
 
 6 
 2 
 
 Kit 
 Vi 
 
 
 1 
 
 QQ 
 
 
 J3 
 
 4-> 
 
 -o 
 
 •J 
 
 ^ 
 
 r, 
 
 c« 
 
 73 
 
 m 
 
 o 
 
 a 
 
4 
 
 r\ 
 
 
 U'! J 
 
 4^ 
 
 I 
 
 H^^^' 
 
 
 
 .-if- 
 
 /ivUV \(t^l£S -oM-P .."^ iK^i?5 hni; 
 
 3 oM 
 
 ,, aibniqa odT 
 
- -^- 
 
 
 V 
 
 *-! 
 
 A 
 
 -\ 
 
 "^1^ 
 
 ^ 
 
 I 
 
 -i-- 
 
 
 
 1 
 
 
 4^" 
 
 
 
 ' 1 1 
 
 
 
 
 
 
 1 , 1 
 
 i ' 1 
 
 1 
 
 
 
 
 ^- 1" 
 
 ^ 
 
 <c 
 
 1 1 1 
 
 — ^^l"-> 
 
 
 — 
 
 — - 
 
 1 1 : 
 
 
 
 i 
 
 1 
 
 
 
 1 
 
 
 
 
 
 l^ 61"- . 
 
 No. 9.— Winch Slide Valve. 
 
 (Draw to a 6" scale.) 
 
 The travel of the valve is i^' . 
 
 The lead ,, ,, /.." top and i" bottom. 
 
 The lap „ ,, li" .. „ ' " 
 
 " Verl)al " N(ites and Sketches. 
 
i-> 
 
 10 ' Ql ? 
 
 No. 10 —Slide Valve Spindle. 
 
 (Draw lo a 2" scale.) 
 
 The valve spindle is made of mild steel. 
 
 The nuts are made of brass. 
 
 The boiler pressure is 100 lbs. per square inch. 
 
 "Verbal" Notes and .Sketches. 
 

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 05 
 
 No. 17.— Guide Shoe. 
 
 (Draw IC) a 2" scale.) 
 
 The shoe is made of cast iron. 
 
 The rubbing surface is made of white metal. 
 
 The pressure on the guide is about 40 lbs. per [77]. 
 
 ■Verbal" Notes iind Sketches. 
 
No. i8.— Gland and Stuffing Box for L.P. Cylinder.- 
 
 {Draw to a 3" scale. ) 
 
 The gland is made of cast iron. 
 The gland bush is made of brass. 
 
 \'erbal " Notes and Sketches. 
 
No. 19. — Winch Piston. 
 
 (Draw to a 6" scale.) 
 
 The piston is made of cast iron. 
 
 The packing rings are made of cast iron. 
 
 The difference in diameter allowed before cutting ring is fV 
 
 "X'erbal"' Notes and Sketches. 
 
m 
 
 ,-y 
 
 loieiH AoniV 
 
 .aoii izso "to abfitn e; aojgxq srlT 
 .11011 icjiO \o »b&m sijs z^nh ;gat:>(3£q erf''" 
 
No 20— Air Pump Valve. 
 
 (Draw to a 6" scale.) 
 
 The guard is made of brass. 
 
 The valve is formed of thin brass plates. 
 
 Verbal " Notes and Sketches. 
 
.^>\ 
 
3f 
 
 € 
 
 Vz^A 
 
 No. 21— Plunger for Feed Pump. 
 
 (Draw to a 2" scale.) 
 
 The plunger is made of brass. 
 The stud at top is of wrought iron. 
 
 Verbal "' Notes and Sketches. 
 
i< 12_ _>< \z ->] 
 
 I ._,,,! 
 
 w 
 
 zzzzzzz? 
 
 !-^ 
 
 / 
 
 f fi- 
 
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 el^ 
 
 
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 l^j^F 
 
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 No, 22. -Brass T-Piece for a Steam Pipe. 
 
 (Draw to a 2" scale.) 
 Boiler pressure. 150 lbs. 
 
 Verbal " Notes and Sketches, 
 
ii:sT Y^TW s s \ s •^TvrvrvTv^ 
 
rs 
 
 
 
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 ^'.- 
 
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 No. 24— Box Spanner for a Blow off Cock. 
 
 (Drau Id a 4" scalo. ) 
 The spanriM- is made of iron. 
 
 "Verbal'" Notes and Sketches 
 
x„ 
 
 lOI 13 
 
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 2C 
 
No. 26.— Boiler Manhole Door. 
 
 (Draw to a 2" scale. ) 
 
 The size of the manhole is i6"xi2". 
 The door is made of mild steel. 
 
 No 27 —Furnace Bar. 
 
 (Draw to a 2" scale.) 
 The amount of expansion of bar averages about i" 
 
 r r' Notes and Sketches. 
 
3'- I" 
 
 -^ 
 
 • 
 
 © 
 
 © 
 
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 T 
 
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 4 BOLTS l— j| THIMBLES 
 
 No. 28.— Bearer for Furnace Bars. 
 
 (Draw to a 2" scale.) 
 
 The bearers are made of iron. 
 
 They are supported at ends by snugs on side of furnace. 
 
 FRONT 
 
 8' 0" 
 
 >^8 *r 
 
 BACK 
 
 10 THREADS PER INCH p ^ 
 
 I" THICK 
 
 ^ 
 
 STAY TUBE "jw 
 
 hO r- 16 THICK 
 
 
 COMMON TUBE 
 
 ^;V^^S\\\SS'>N\N\Vfc'^\\SSSS\SS\S\\SS\ '.^^^^^■v^^^ vVvVSv. v v s\\\\ \ \' . -v \ ^'v^ .V ^ '.'. -vCT: 
 
 NO- 29. —Boiler Stay Tube; Boiler Smoke Tube. 
 
 (Draw to a 4" scale.) 
 
 These tubes are made of iron. 
 
 The number of stay tubes fitted is about .1 of total tubes. 
 
 al " Notes and Sketches. 
 
8TJ( 
 
 -r- ■'■J*' 
 
 ■ 
 
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 917- 
 
 
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 No. 32.— Double Butt Strap Joint. 
 
 (Draw to a 2" scale.) 
 
 Diameter of boiler is 14-6". 
 Pressure ,. 180 lbs. 
 
 Rivets are made of steel. 
 
 Stress allowed is 23 tons per square inch on rivets. 
 ,, 28 ,, ,, plate 
 
 Factor of safety is 4-5. 
 Rivet diameter ., i§'. 
 ,. pitch ,. 10". 
 
 'irbal" Notes and Sketches 
 
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No. 34.— Combustion Chamber Stay. 
 
 (Draw to a 4" scale.) 
 
 Stays of mild steel. 
 Nuts of mild steel. 
 
 No. 35.— Double Rivetted Lap Joint 
 
 (Draw to a 4" scale.) 
 
 Rivets are of mild steel. 
 Plates are of mild steel. 
 Joint strength, 67 7o- 
 
 ' Verbal " Notes and Sketches 
 
liilii'^cSi^liiiiiii^ 
 
 -JS32 
 
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 —9" 
 
 No 37— Check Valve Cover. 
 
 (Draw to a 4" scale.) 
 
 Cover of brass. 
 Spindle of mild steel. 
 
 "Verbal" Notes and Sketches. 
 
t 
 
I 
 
 No. 38.— Hand Wheel for Stop Valve. 
 
 (Draw to a 6" scale.) 
 The wheel is made of cast iron. 
 
 "Verbal" Notes and Sketches. 
 
No. 39 Air Vessel 
 
 el of cast iron feed pump plunger 3" diameter. 
 ' in pipe. 30 lbs. iheateri. 
 
W- 
 
 
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 Z' 
 
 - y_ 
 
 V 
 
 ! 
 J 
 
 
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 1 ;i 
 
 _ Y . 
 
 No. 40.— Water Gauge Column Bracket. 
 
 !" Verbal" Notes and Sketches. 
 
K 
 
 CM 
 
 1 . 
 
 ,^a - -[.5 _-.^ 
 -I 
 
 
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 ir^dS: 
 
 
 ^-§M 
 
 4- 
 
 (M 
 CM 
 
 
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 No. 40.— Water Gauge Column Bracket. 
 
 "Verbal'" Notes and Sketches. 
 
Il 
 
Data.- 
 
 RULE.- 
 
 Appendix 70 1 
 
 Vertical Donkey Boiler 
 
 Pressure = 80 lbs. (gauge). 
 Diameter = 5 feet 
 H eight := II feet. 
 
 Mean diameter of fire box — ( ^-5t4\ -4.25 feet. 
 
 Height of fire box -5 feet 9 inches. 
 
 Fire grate area = 4-s-x •7854=15-9 square feet 
 
 Area of uptake = Grate areax^^-.- 
 
 Then, Diameter of uptake =^ / J5-9ili_ ^ j.2q feet, say it; inches, 
 
 V 7854 X 12 ' ■' " 
 
 Vertical shell seams double riveted, circumferential shell seams 
 and all internal parts, single riveted. 
 
 Allow a factor of safety of 6, and a joint strength of about 70 per 
 iCent. for the vertical seams and about 54 per cent, fur the circum- 
 ferential seams. 
 
 Shell.— 
 
 28 2240 X T inch ■ 2 ■ Joints Diameter in inches x Factor ;: Pressure. 
 
 30 that, 28 2240 , T ' . 2 .. 70 = 60" 6 : 80. 
 
 ■rherefore, T inch=-- 60x6^80 ^ ^^j^ „. .^^ 
 
 28 X 2240 X 2 X -70 
 
 Rivet diameter=i-2\ T = i.2x \'^37S=734 inch, say % inch. 
 
 NOTE.— As the plate thickness is low, it will be advisable to allow rivets of, 
 ly, I f; inch diameter. 
 
 ''ertical Shell Seams (Double riveting).— 
 
 Rivet pitch ^I^^-i^'^^^L^iameter 
 100 - Joint 
 hpn - ^00 ■■' '8125 ^ „ • . • u 
 
 "^"' »» >> ,,j:^^ ^ = 27 mches, say av mches. 
 
 100-70 
 
 NOTE.— 1} inch = -8125. 
 L'LE.— 
 
 Distance between rivet row3^ \ (Iip-r4tf) x (p + 4tf) _ 
 
 10 
 
 NOTE. — p- rivet pitch, </— rivet diameter, 
 len, 
 
 Distance between rows = '^ ' " " ^'75 - 4 - -8125) ^ (275 -r 4 -8125) 
 
 10 
 
 -I -41 inches, say li inches. 
 
 Distance between edge of plate and centre of rivet = 1-5 x </=i.5x -8125 
 
 = 1-21 inches, say i^ inches. 
 
 Width of lap = ii + xi-:-ii; inches = 4 inches. 
 4/ 
 
702 '' Verbal " Notes and Sketches 
 
 Circumferential Shell Seams (Single riveting). — 
 
 Rivet diameter same as before=|| = '8i2S. 
 
 Rivet pitch = — ° ^ '^^^ ^1-7 inches, say if inches. 
 100-54 
 
 Width of lap (3 rivet diameters) = [g + fg + iB inch = 2i"s inches. 
 
 Fire Box (Welded).— 
 Rule. — 
 
 90000 xT-=( Height in feet+i) x Diameter in inches x Pressure. 
 
 _,, - -p_ /(Height in feet + 1) x Diam . in inches x Pressure 
 
 • ' ~V 90000 
 
 Allow, say, six stays round uptake, each with a working stress of 
 9000 lbs. per square inch. 
 
 Then, Area of surface to be supported = (54-- 30") x •7854 = 1583-3 square inches. 
 
 NOTE.— As the fillets of the shell and fire box act to stay the top end of the 
 boiler, the unstayed area may be taken to be equal to the difference between a 
 54-inch circle and a 30-inch circle, which will sufficiently allow for the strengthen' 
 ing effect of the uptake ring. 
 
 Diameter of stays- / ^ ^^ ^'^ ^ — =i-7 inches, say i| inches diameter. 
 
 ^ V 6x7854x9000 ' » J 4 
 
 Fire Box Riveting. — 
 
 Plate j-g inch thick. Rivets i inch diameter. 
 Jomt strength = 53 per cent. 
 
 Pitch = ^°°'^^ ^"^^ = 2-12 inches, say 2j inches. 
 100-53 
 
 Seam strength=— ^^ — x 100 = 53 per cent, of solid plate (nearly). 
 Rivet strength = ?!:7854.11^23xwo^^^ p^j. ^^^^^ ^^ g^^jj pj^^g (nearly). 
 
 As the smaller result = joint, then 53 per cent, is the joint strength. 
 This riveting also holds good for the crown plate of the shell, the || 
 cross water-tube flanges, and the solid ring joining the uptake and 
 the crown plate. 
 
 To Verify Joint Strength, 
 Vertical Shell Seams.— 
 
 Rule. — 
 
 „ ,. , ,, Pitch - Diameter ,^^ 
 Seam section strength = p-ph 
 
 fjjyg|. „ Rivet are a x No. in a pitch x 23 x 100 
 
 Pitch X Thickness x 28 
 NOTE.— Shear strength of steel rivets = 23 tons per square inch. - 
 
 Tensile ,, ,^ plates = 28 ,, .. ,, 
 
Plan of Boiler 
 
 ^\^>^\i^\i'< 
 
 \_'J\' fttic ia^^d yo2. 
 
 No. S-Longitudinal (Vertical) Shell Riveting. 
 
 Plates g inch thick. 
 
No. 2.— Sectional Plan showing Fire Bars and Bearer Ring. 
 
 No. 3. -Plan of Boiler. 
 
 [/. /;..L-.-.iif ;o-. 
 
Appendix 
 
 703 
 
 No. 4— Circumferential Shell Riveting. 
 
 Plates ^ inch thick. 
 
 No. S-Longitudinal (Vertical) Shell Riveting. 
 
 Plates I inch thick. 
 
'«?^-.:^dlt^" 
 
 rf>nr>i 
 
 Seam section strength = 
 Rivet ,, ,, : 
 
 X 100. 
 
 Pitch 
 . Rivet area x No. in a pitch x 23 x ico 
 
 " " Pitch X Thickness X 28 
 
 NOTE.— Shear strength of steel rivets = 23 tons per square inch. 
 Tensile ,, ,^ plates = 28 ,, ,, 
 
Appendix 
 
 703 
 
 No. 4— Circumferential Shell Riveting. 
 
 Plates 2 inch thick. 
 
 H DIA, 
 
 No. 5— Longitudinal (Vertical) Shell Riveting. 
 
 Plates f inch thick. 
 

 704 "Verbal" Notes and Sketches 
 
 Then, 
 
 Seam strength=?:21"-^^x 100=70-4 per cent, of solid plate. 
 2*75 
 
 and. Rivet strength -8xH^^851x2^^3JiiOO^ 82-5 per cent, of solid plate. 
 
 Circumferential Shell Seams.— 
 
 Seam strength = '-:^5- -^'2-5 x 100-56 pcr cent, of solid plate. 
 I -075 
 
 Rivet strength=:8i25^_54^3^JP?.6o.S per cent, of sohd plate. 
 
 Stresses on Shell Seams. 
 Vertical (longitudinal) Seams.— 
 Rule. — 
 
 Diameter in inches x Pressure = T" x 2 x Stress per square inch. 
 
 . . Diameter" x Pressure 
 Therefore, Stress square mch = 1'^^ 
 
 _6o ^;_8o_g Q njg^ square inch. 
 .375x2 
 
 Circumferential Seams. — 
 
 Rule.— 
 
 Diameter x Diameter ,. -7854 Pressure = D" x 3.1416 x T" x Stress per sq. in. 
 or, Diameter" x Pressure = T" x 4 x Stress per square inch. 
 
 ©"xD"x.7854_D" ♦ 
 
 NOTE.- -^ ' "3*^ 4 ■ 
 
 _ „ . . Diameter" x Pressure 
 Therefore, Stress square inch ^ T^'T; 4 
 
 _ 6o"x8o _^-gQQ jjjg square inch. 
 •375x4 "^ 
 
 As will be seen from the foregoing, the stress longitudinally is 
 exactly equal to twice the stress circumferentially in all cases, hence 
 the necessity for the stronger type of joints required for the long^, 
 tudinal shell seams. 
 
 Manhole Door Compensating Ring.— 
 Rule.— 
 
 Breadth of ring (if same thickness as shell) = Small diameter of door x -J. 
 
 Then, Breadth of ring =12 inches x -5 = 6 inches. 
 
 Therefore, Outside sizes of compensating plate ring = 
 
 6 inches 1 16 inches + 6 inches =-28 inches 1^^. ^s inches by 24 inches. 
 6 inches + 12 inches + 6 inches = 24 inches J 
 
Saturated Steam Tables 
 
 705 
 
 Properties of Saturated Steam 
 Of from 0-5 lb. to 250 lbs. Absolute Pressure per Square Inch. 
 
 Absolute 
 Pressure per 
 Square Inch. 
 
 Temperatures. 
 
 Total Heat of 
 I lb. of Steam 
 from Water sup- 
 plied at 32' Fahr. 
 
 Total Latent 
 Heat of .Steam. 
 
 1 
 
 1 Density or Weight 
 
 of I Cubic Foot of 
 
 Steam. 
 
 Volume of I 11.. ol 
 Steam. 
 
 L1.S. 
 
 Deg. Fahr. 
 
 Units. 
 
 Units. 
 
 Lbs. 
 
 Cubic Feet. 
 
 0-5 
 
 8o-2 
 
 I 105-5 
 
 1058-4 
 
 I -001376 
 
 726-608 
 
 1 
 
 102-I 
 
 III2-5 
 
 1042-9 
 
 -003027 
 
 330-360 
 
 1-5 
 
 115-9 
 
 I I 16-7 
 
 1033-2 
 
 •004433 
 
 225-580 
 
 2 
 
 125-3 
 
 I I 19-9 
 
 1025-8 
 
 •00581 1 
 
 172-080 
 
 -■5 
 
 134-6 
 
 II22-5 
 
 IOI9-9 
 
 ■007 1 6g 
 
 139-488 
 
 ,> 
 
 i4i-() 
 
 I 124-6 
 
 1015-0 
 
 -00851 1 
 
 I 17-500 
 
 3-5 
 
 147-7 
 
 I 126-4 
 
 IOIO-6 
 
 -009839 
 
 101-632 
 
 4 
 
 1 53- 1 
 
 II28-I 
 
 1006-8 
 
 -01116 
 
 89-632 
 
 4-5 
 
 157-9 
 
 I 129-6 
 
 1003-4 
 
 •01246 
 
 80-231 
 
 5 
 
 162-3 
 
 II 30-9 
 
 1000-3 
 
 -01370 
 
 72-991 
 
 5-5 
 
 1 66-4 
 
 II32-I 
 
 997-4 
 
 -01505 
 
 66-428 
 
 6 
 
 170-2 
 
 ' 133-3 
 
 994-7 
 
 •01634 
 
 61-201 
 
 6-5 
 
 173-6 
 
 J 134-3 
 
 9923 
 
 •01 762 
 
 56-761 
 
 7 
 
 176-9 
 
 II35-3 
 
 990-0 
 
 •01889 
 
 52-936 
 
 7-5 
 
 iSo-o 
 
 1136-3 
 
 987-8 
 
 •02016 
 
 49-610 
 
 8 
 
 182-9 
 
 II37-2 
 
 985-7 
 
 •02142 
 
 46-686 
 
 8-5 
 
 185-7 
 
 I 138-0 
 
 983-8 
 
 •02268 
 
 44-097 
 
 9 
 
 188-3 
 
 I I 38.8 
 
 981-9 
 
 •02394 
 
 41-777 
 
 9-5 
 
 190-8 
 
 I 139-5 
 
 980-1 
 
 -02547 
 
 39-261 
 
 10 
 
 193-3 
 
 1140-3 
 
 978-4 
 
 •02642 
 
 37-845 
 
 IO-5 
 
 195-6 
 
 I 141-0 
 
 976-7 
 
 •02767 
 
 36-145 
 
 1 1 
 
 197-8 
 
 II41-7 
 
 975-2 
 
 •02890 
 
 34-599 
 
 '••5 
 
 200-I 
 
 I 142-4 
 
 973-6 
 
 •03026 
 
 33-045 
 
 12 
 
 202-0 
 
 I 143-0 
 
 972-2 
 
 •03137 
 
 31-879 
 
 '-'•5 
 
 204-0 
 
 1143-6 
 
 970-8 
 
 -03260 
 
 30-678 
 
 13 
 
 205-9 
 
 I 144-2 
 
 969-4 
 
 •03382 
 
 29-573 
 
 K^-l 
 
 207-8 
 
 I 144-8 
 
 968-1 
 
 -03504 
 
 28-536 
 
 '4 
 
 209-6 
 
 1 1 45 -3 
 
 966-8 
 
 •03627 
 
 27-573 
 
 14-7 
 
 2120 
 
 1 146-1 
 
 965-2 
 
 •03797 
 
 26-360 
 
 15 
 
 2131 
 
 1 146-4 
 
 964-3 
 
 •03870 
 
 25-843 
 
 16 
 
 216-3 
 
 1 147-4 
 
 962-1 
 
 •04112 
 
 24-320 
 
 17 i 
 
 219-6 
 
 1 148-3 
 
 959-8 
 
 •04253 
 
 23-5'3 
 
 18 
 
 222-4 
 
 1 149-2 
 
 957-7 
 
 -04594 
 
 21-766 
 
 ^9 
 
 225-3 
 
 1 1 50- 1 
 
 955-7 
 
 -04834 
 
 20-687 
 
 20 
 
 228-0 
 
 1150-9 
 
 953-8 
 
 -05074 
 
 19-710 
 
 21 
 
 230-6 
 
 1151-7 
 
 951-9 
 
 •0531 1 
 
 18-828 
 
 22 
 
 ""-ll-^ 
 
 1152-5 
 
 950-2 
 
 -05549 
 
 18022 
 
 23 
 
 2355 
 
 1153-2 
 
 948-5 
 
 -05786 
 
 17-282 
 
 24 
 
 237-8 
 
 II53-9 
 
 946-9 
 
 -06023 
 
 16603 
 
 25 
 
 240-1 
 
 1 154-6 
 
 945-3 
 
 •06259 
 
 •5977 
 
 26 
 
 242-3 
 
 1155-3 
 
 943-7 
 
 •06495 
 
 15-401 
 
7o6 
 
 " Verbal " Notes and Sketches 
 Properties of Saturated Steam — continued. 
 
 Absolute 
 Pressure per 
 Square Inch. 
 
 Lbs. 
 
 Temperatures. 
 
 Deg. Fahr. 
 
 Total Heat of 
 I lb. of Steam 
 from Water sup- 
 plied at 32* Fahr. 
 
 Units. 
 
 Total Latent 
 Heat of Steam. 
 
 Density or Weight 
 
 of I Cubic Foot of 
 
 Steam. 
 
 Volume of i lb. of 
 Steam. 
 
 27 
 
 244-4 
 
 28 
 
 246-4 
 
 29 
 
 248-4 
 
 30 
 
 250-4 
 
 31 
 
 252-2 
 
 32 
 
 254-1 
 
 33 
 
 255-9 
 
 34 
 
 257-6 
 
 35 
 
 259-3 
 
 36 
 
 260-9 
 
 37 
 
 262-6 
 
 38 
 
 264-2 
 
 39 
 
 265-8 
 
 40 
 
 267-3 
 
 41 
 
 268-7 
 
 42 
 
 270-2 
 
 43 
 
 271-6 
 
 44 
 
 273-0 
 
 45 
 
 274-4 
 
 46 
 
 275-8 
 
 47 
 
 277-1 
 
 48 
 
 278-4 
 
 49 
 
 279-7 
 
 50 
 
 281-0 
 
 51 
 
 282.3 
 
 52 
 
 283-5 
 
 53 
 
 284-7 
 
 54 
 
 285-9 
 
 55 
 
 287-1 
 
 56 
 
 288-2 
 
 57 
 
 289-3 
 
 58 
 
 290-4 
 
 59 
 
 291-6 
 
 60 
 
 292-7 
 
 61 
 
 293-8 
 
 62 
 
 294-8 
 
 63 
 
 295-9 
 
 64 
 
 296-9 
 
 65 
 
 298-0 
 
 66 
 
 299-0 
 
 67 
 
 300-0 
 
 68 
 
 3009 
 
 69 
 
 301-9 
 
 II55 
 II56 
 
 1157 
 1 157 
 
 II58 
 II58 
 
 II59 
 II60 
 II60 
 II6I 
 II6I 
 II62 
 II62 
 II62 
 
 II63 
 II63 
 1 164 
 
 1 164 
 
 II65 
 II65 
 
 1 165 
 
 II66 
 II66 
 
 II67 
 1167 
 II67 
 
 II68 
 1 168 
 
 II69 
 II69 
 II69 
 
 II70 
 II70 
 II70 
 II7I 
 II7I 
 II7I 
 II72 
 II72 
 II72 
 II72 
 
 II73 
 II73 
 
 Units. 
 
 942 
 
 940 
 
 939 
 937 
 936 
 935 
 934 
 932 
 931 
 930 
 929 
 928 
 927 
 926 
 924 
 923 
 922 
 921 
 920 
 919 
 919 
 918 
 917 
 916 
 
 915 
 914 
 
 913 
 912 
 912 
 911 
 910 
 
 909 
 908 
 908 
 907 
 906 
 905 
 904 
 904 
 
 903 
 902 
 902 
 901 
 
 06728 
 
 05971 
 07196 
 07430 
 07663 
 07894 
 08128 
 
 08358 
 
 08590 
 
 08821 
 
 09050 
 
 09282 
 
 09510 
 
 09740 
 
 09946 
 
 020 
 
 042 
 
 065 
 
 088 
 
 III 
 
 134 
 156 
 179 
 202 
 224 
 247 
 269 
 292 
 314 
 337 
 357 
 382 
 
 404 
 426 
 
 449 
 471 
 493 
 516 
 
 538 
 560 
 
 583 
 604 
 627 
 
 Cubic Feet. 
 
 863 
 
 345 
 896 
 
 459 
 050 
 666 
 300 
 964 
 640 
 
 337 
 
 050 
 
 773 
 
 515 
 267 
 
 054 
 806 
 
 592 
 386 
 191 
 003 
 821 
 650 
 482 
 322 
 170 
 02 1 
 880 
 
 741 
 610 
 482 
 370 
 238 
 123 
 01 1 
 902 
 798 
 696 
 
 596 
 502 
 410 
 318 
 233 
 147 
 
Saturated Steam Tables 
 
 -07 
 
 Properties of Saturated Steam — continued. 
 
 Absolute 
 Pressure per 
 Square Inch. 
 
 Temperatures. 
 
 Total Heat of 
 I lb. of Steam 
 from Water sup- 
 plied at 32* Fahr. 
 
 Total Latent 
 Heat of Steam. 
 
 Density or Weight 
 
 of I Cubic Foot of 
 
 Steam. 
 
 Volume of i lb. of 
 Steam. 
 
 Lbs. 
 
 Deg. Fahr. 
 
 Units. 
 
 Units. 
 
 Lbs. 
 
 Cubic Feet. 
 
 70 
 
 302-9 
 
 II73-8 
 
 * 900-8 
 
 -1650 
 
 6-059 
 
 71 
 
 303-9 
 
 II74-I 
 
 900-3 
 
 -1671 
 
 5-984 
 
 72 
 
 304-8 
 
 II74-3 
 
 899-6 
 
 -1693 
 
 5-905 
 
 73 
 
 305-7 
 
 1 174-6 
 
 898-9 
 
 -1716 
 
 5-829 
 
 74 
 
 306-6 
 
 1x74-9 
 
 898-2 
 
 -1738 
 
 5-764 
 
 75 
 
 307-5 
 
 1175-2 
 
 897-5 
 
 -1760 
 
 5-683 
 
 76 
 
 308-4 
 
 II75-4 
 
 896-8 
 
 -1782 
 
 5-610 
 
 77 
 
 309-3 
 
 1175-7 
 
 896-1 
 
 -1803 
 
 5-544 
 
 78 
 
 310-2 
 
 1176-0 
 
 895-5 
 
 •1826 
 
 5-476 
 
 79 
 
 311-1 
 
 1176-3 
 
 894-9 
 
 -1848 
 
 5-411 
 
 80 
 
 312-0 
 
 1176-5 
 
 894-3 
 
 •1870 
 
 5-348 
 
 81 
 
 312-8 
 
 1176-8 
 
 893-7 
 
 -1892 
 
 5-286 
 
 82 
 
 i^z-^ 
 
 1177-1 
 
 893-1 
 
 -T912 
 
 5-230 
 
 83 
 
 314-5 
 
 1177-4 
 
 892-5 
 
 •1936 
 
 5-167 
 
 84 
 
 315-3 
 
 1177-6 
 
 892-0 
 
 -1957 
 
 5-109 
 
 85 
 
 3I6-I 
 
 1177-9 
 
 891-4 
 
 -1980 
 
 5-052 
 
 86 
 
 316-9 
 
 1178-1 
 
 890-8 
 
 -2001 
 
 4-996 
 
 87 
 
 317-8 
 
 1178-4 
 
 890-2 
 
 -2023 
 
 4-942 
 
 88 
 
 318.6 
 
 1178-6 
 
 889-6 
 
 -2046 
 
 4-889 
 
 89 
 
 319-4 
 
 1178-9 
 
 889-0 
 
 -2067 
 
 4-837 
 
 90 
 
 320-2 
 
 1179-1 
 
 888-5 
 
 -2088 
 
 4-790 
 
 91 
 
 321-0 
 
 1179-3 
 
 887-9 
 
 -2III 
 
 4-737 
 
 92 
 
 321-7 
 
 II79-5 
 
 887-3 
 
 •2133 
 
 4-688 
 
 93 
 
 322-5 
 
 1179-8 
 
 886-8 
 
 •2154 
 
 4-642 
 
 94 
 
 323-3 
 
 1 180-0 
 
 886-3 
 
 •2176 
 
 4-595 
 
 95 
 
 324-1 
 
 ii8o-3 
 
 885-8 
 
 ■2198 
 
 4-549 
 
 96 
 
 324-8 
 
 1 180-5 
 
 885-2 
 
 •2220 
 
 4-505 
 
 97 
 
 325-6 
 
 ii8o-8 
 
 884-6 
 
 -2241 
 
 4-462 
 
 98 
 
 326-3 
 
 1181-0 
 
 884-1 
 
 •2263 
 
 4-419 
 
 99 
 
 327-1 
 
 1181-2 
 
 883-6 
 
 -2286 
 
 4-375 
 
 100 
 
 327-9 
 
 1181-4 
 
 883-1 
 
 •2307 
 
 4-335 
 
 lOI 
 
 328-5 
 
 1181-6 
 
 882-6 
 
 -2329 
 
 4-305 
 
 102 
 
 329-1 
 
 1181-8 
 
 882-1 
 
 -2350 
 
 4-256 
 
 103 
 
 329-9 
 
 1182-0 
 
 881-6 
 
 -2372 
 
 4-216 
 
 104 
 
 330-6 
 
 1182-2 
 
 881-1 
 
 ■2393 
 
 4-178 
 
 105 
 
 331-3 
 
 1182-4 
 
 880-7 
 
 -2415 
 
 4-140 
 
 106 
 
 331-9 
 
 1182-6 
 
 8802 
 
 -2437 
 
 4-104 
 
 107 
 
 3326 
 
 1182-8 
 
 879-7 
 
 -2458 
 
 4-068 
 
 108 
 
 333-3 
 
 1183-0 
 
 879-2 
 
 -2480 
 
 4-033 
 
 109 
 
 334-0 
 
 1183-3 
 
 878-7 
 
 •2502 
 
 3-998 
 
 110 
 
 334-6 
 
 1183-5 
 
 878-3 
 
 -2523 
 
 3-963 
 
 III 
 
 335-3 
 
 1183-7 
 
 877-8 
 
 -2545 
 
 3-930 
 
 112 
 
 336-0 
 
 1183-9 
 
 877-3 
 
 -2566 
 
 3-897 
 
7o8 
 
 "Verbal" Notes and Sketches 
 Properties of Saturated Steam — continued. 
 
 Absolute 
 
 
 Total Heat of 
 I lb. of ijteam 
 
 Total Latent ^^^\ 
 
 ity or Weight 
 
 Volume of 1 lb. of 
 
 Pressure per 
 Square Inch. 
 
 Lbs. 
 
 Temperatiires. 
 
 from Water sup- 
 plied at 32° Fahr. 
 
 Heat of -Steam. °" * 
 
 ^ubic rout i.f 
 Steam. 
 
 Steam. 
 
 Deg. Fahr. 
 
 Units. 
 
 Units. 
 
 Lbs. 
 
 Cubic Feet. 
 
 336-7 
 
 1184-1 
 
 876-8 
 
 2588 
 
 3-865 
 
 114 
 
 337-4 
 
 I184 
 
 3 
 
 876-3 
 
 2610 
 
 3-832 
 
 "5 
 
 338-0 
 
 I184 
 
 5 
 
 875-9 
 
 2631 
 
 3-801 
 
 116 
 
 338-6 
 
 I 184 
 
 7 
 
 875-5 
 
 2653 
 
 3-770 
 
 117 
 
 339-3 
 
 I184 
 
 9 
 
 875-0 
 
 2674 
 
 3-740 
 
 118 
 
 339-9 
 
 1185 
 
 I 
 
 874-5 
 
 2696 
 
 3-7IO 
 
 119 
 
 340-5 
 
 1185 
 
 
 
 874-1 
 
 271.7 
 
 3-681 
 
 120 
 
 341-1 
 
 I 185 
 
 4 
 
 873-7 
 
 2738 
 
 3-652 
 
 121 
 
 341-8 
 
 I185 
 
 6 
 
 873-2 
 
 2760 
 
 3-623 
 
 122 
 
 342-4 
 
 1185 
 
 8 
 
 872-8 
 
 2781 
 
 3-595 
 
 123 
 
 343-0 
 
 I186 
 
 
 
 872-3 
 
 2803 
 
 3-567 
 
 124 
 
 343-6 
 
 1x86 
 
 2 
 
 871-9 
 
 2824 
 
 3-541 
 
 125 
 
 344-2 
 
 1186 
 
 4 
 
 871-5 
 
 2846 
 
 3-514 
 
 126 
 
 344-8 
 
 1186 
 
 6 
 
 871-1 
 
 2867 
 
 3-488 
 
 127 
 
 345-4 
 
 1186 
 
 8 
 
 870-7 
 
 2889 
 
 3-462 
 
 128 
 
 346-0 
 
 1186 
 
 9 
 
 870-2 
 
 2910 
 
 3-436 
 
 129 
 
 346-6 
 
 1187 
 
 I 
 
 869-8 
 
 2931 
 
 3-41 1 
 
 130 
 
 347-2 
 
 1187 
 
 3 
 
 8694 
 
 295T 
 
 3-388 
 
 131 
 
 347-8 
 
 1187 
 
 5 
 
 869-0 
 
 2974 
 
 3-362 
 
 132 
 
 348-3- 
 
 1187 
 
 6 
 
 868-6 
 
 2996 
 
 3-338 
 
 133 
 
 348-9 
 
 1187 
 
 8 
 
 868-2 
 
 30x7 
 
 3-315 
 
 134 
 
 349-5 
 
 ii88 
 
 
 
 867-8 
 
 3038 
 
 3-291 
 
 135 
 
 350-r 
 
 • 1188 
 
 2 
 
 867-4 
 
 3060 
 
 3-268 
 
 136 
 
 3506 
 
 1188 
 
 3 
 
 867-0 
 
 3080 
 
 3-246 
 
 '37 
 
 351-2 
 
 1188 
 
 5 
 
 866-6 
 
 3102 
 
 3-224 
 
 138 
 
 351-8 
 
 1188 
 
 7 
 
 866-2 
 
 3123 
 
 3-201 
 
 139 
 
 3524 
 
 1188 
 
 9 
 
 865-8 
 
 3145 
 
 3-180 
 
 140 
 
 352-9 
 
 1189 
 
 
 
 865-4 
 
 3166 
 
 3-159 
 
 141 
 
 353-5 
 
 1189 
 
 2 
 
 865-0 
 
 3187 
 
 3-138 
 
 142 
 
 354-0 
 
 1189 
 
 4 
 
 864-6 
 
 3209 
 
 3-117 
 
 143 
 
 354-5 
 
 1189 
 
 6 
 
 864-2 
 
 3230 
 
 3-096 
 
 144 
 
 355-0 
 
 1189 
 
 7 
 
 863-9 
 
 3251 
 
 3-076 \ 
 
 145 
 
 355-6 
 
 1 189 
 
 9 
 
 863-5 
 
 3272 
 
 3-056 
 
 146 
 
 356-1 
 
 1 190 
 
 
 
 863-1 
 
 3293 
 
 3-037 
 
 147 
 
 356-7 
 
 1 190 
 
 2 
 
 862-7 
 
 3315 
 
 3-017 
 
 148 
 
 357-2 
 
 .1190 
 
 3 
 
 862-3 
 
 3336 
 
 2-998 
 
 149 
 
 357-8 
 
 1 190 
 
 5 
 
 861-9 
 
 3357 
 
 2-979 
 
 150 
 
 358-3 
 
 1 190 
 
 7 
 
 861.5 
 
 3378 
 
 2-960 
 
 151 
 
 359-0 
 
 1 190 
 
 9 
 
 8611 
 
 3400 
 
 2-941 
 
 152 
 
 359-5 
 
 1191 
 
 
 
 86o-7 
 
 3421 
 
 2-923 
 
 153 
 
 360-0 
 
 1191 
 
 2 
 
 860-4 
 
 3442 
 
 2-905 
 
 '54 
 
 360-5 
 
 1191 
 
 4 
 
 860-0 
 
 3463 
 
 2-887 
 
 ^55 
 
 361-1 
 
 1191-5 
 
 859-6 
 
 3484 
 
 2-870 
 
Saturated Steam Tables 
 Properties of Saturated Steam — continued. 
 
 709 
 
 Absolute 
 Pressure per 
 S»[uare iich. 
 
 l.l.s. 
 
 Temperatures. 
 
 Total Heat of 
 I lb. of Steam 
 from Water sup- 
 plied at 32° Fahr. 
 
 Total Latent ''^"^^ 
 Heat of Steam. °' ' ^ 
 
 y or Weight 
 ubic Foot of 
 iteam. 
 
 Volume of i 11.. of 
 Steam. 
 
 Deg. Fahr. 
 
 Units 
 
 Units. 
 
 Lbs. 
 
 Cubic Feet. 
 
 156 
 
 361-6 
 
 1191-7 
 
 859.2 
 
 3505 
 
 2-853 
 
 157 
 
 362-1 
 
 I 191-8 
 
 858-9 
 
 3527 
 
 2 
 
 S36 
 
 158 
 
 362-6 
 
 I 1920 
 
 858-5 
 
 3548 
 
 2 
 
 818 
 
 159 
 
 Zf^l"^ 
 
 I 192-1 
 
 858.1 
 
 3569 
 
 2 
 
 S02 
 
 160 
 
 363-6 
 
 II92-3 
 
 857-8 
 
 3590 
 
 2 
 
 785 
 
 165 
 
 366-0 
 
 I 192-9 
 
 856-2 
 
 3696 
 
 2 
 
 706 
 
 170 
 
 368-2 
 
 1193-7 
 
 854-5 
 
 380I 
 
 2 
 
 631 
 
 175 
 
 370-8 
 
 I 194-4 
 
 852-9 
 
 3905 
 
 2 
 
 559 
 
 180 
 
 372-9 
 
 II95-I 
 
 851-3 
 
 4011 
 
 2 
 
 493 
 
 X85 
 
 375-3 
 
 1195-8 
 
 849-6 
 
 4115 
 
 2 
 
 430 
 
 190 
 
 377-5 
 
 1 196-5 
 
 848-0 
 
 4220 
 
 2 
 
 370 
 
 195 
 
 379-7 
 
 1197-2 
 
 846-5 
 
 4324 
 
 2 
 
 313 
 
 200 
 
 381-7 
 
 1 197-8 
 
 845-0 
 
 4419 
 
 2 
 
 263 
 
 2ro 
 
 3860 
 
 1199-1 
 
 841-9 
 
 463 
 
 2 
 
 157 
 
 220 
 
 389-9 
 
 1200-3 
 
 839-2 
 
 484 
 
 2 
 
 065 
 
 230 
 
 394-0 
 
 12O1-0 
 
 836-0 
 
 505 
 
 1 
 
 98 
 
 240 
 
 397-0 
 
 1202-0 
 
 833-0 
 
 525 
 
 1 
 
 90 
 
 250 
 
 401-0 
 
 1203-0 
 
 831-0 
 
 546 
 
 1-83 
 
7IO 
 
 " Verbal " Notes and Sketches 
 Table of Circumferences and Areas of Circles. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 •03125 
 
 -0981 
 
 •00077 
 
 6 
 
 1 8^8496 
 
 28-274 
 
 12 
 
 37-0991 
 
 113-10 
 
 •0625 
 
 •1963 
 
 •00307 
 
 6-125 
 
 19-2423 
 
 29-465 
 
 12-125 
 
 38 0918 
 
 115-47 
 
 •125 
 
 -3926 
 
 •01227 
 
 6-25 
 
 19-6350 
 
 30-680 
 
 12-25 
 
 38-4845 
 
 117-86 
 
 •25 
 
 •7853 
 
 •04909 
 
 6-375 
 
 20-0277 
 
 31-919 
 
 12-375 
 
 38-8772 
 
 120-28 
 
 •375 
 
 M781 
 
 •11045 
 
 6-5 
 
 20-4204 
 
 33-183 
 
 12-5 
 
 39-2699 
 
 122-72 
 
 •5 
 
 1.5708 
 
 •19635 
 
 6-625 
 
 20-8131 
 
 34-472 
 
 12-6-25 
 
 39-6620 
 
 125-19 
 
 •625 
 
 r9635 
 
 •30680 
 
 6-75 
 
 21-2058 
 
 35-785 
 
 12-75 
 
 40 0553 
 
 1-27-68 
 
 •75 
 
 2^3561 
 
 •4417 
 
 6-875 
 
 21-5984 
 
 37-122 
 
 12-875 
 
 40-4480 
 
 13019 
 
 •875 
 
 £•748 
 
 •601 
 
 
 
 
 
 
 
 
 
 
 7 
 
 21-9911 
 
 38-485 
 
 13 
 
 40-8407 
 
 132-73 
 
 1 
 
 31416 
 
 •7854 
 
 7-125 
 
 22-3838 
 
 39-871 
 
 13-125 
 
 41-2334 
 
 1.35-30 
 
 1125 
 
 3 5342 
 
 0-9940 
 
 7-25 
 
 22-7765 
 
 41-282 
 
 13-25 
 
 41-6261 
 
 137-89 
 
 125 
 
 3-9269 
 
 1-2272 
 
 7-375 
 
 23-1692 
 
 42-718 
 
 13-375 
 
 42-0188 
 
 140-50 
 
 1375 
 
 4^3196 
 
 1-4849 
 
 7-5 
 
 23-5619 
 
 44-179 
 
 13-5 
 
 42-4115 
 
 143-14 
 
 1-5 
 
 4^7129 
 
 1-7671 
 
 7-625 
 
 23-9546 
 
 45-664 
 
 13-625 
 
 42-8042 
 
 145-80 
 
 1^625 
 
 5^1050 
 
 2 0739 
 
 7-75 
 
 24-3473 
 
 47-173 
 
 13-75 
 
 43-1969 
 
 148-49 
 
 175 
 
 5 4977 
 
 2-4053 
 
 7-875 
 
 24-7400 
 
 48-707 
 
 13-875 
 
 43-5896 
 
 151-20 
 
 r875 
 
 5^8904 
 
 2-7612 
 
 
 
 
 
 
 
 
 
 
 8 
 
 25-1327 
 
 50-265 
 
 14 
 
 43-9823 
 
 153-94 
 
 2 
 
 6-2831 
 
 3-1416 
 
 8-125 
 
 25-5-224 
 
 51-849 
 
 14-125 
 
 44-3750 
 
 156-70 
 
 2125 
 
 6-6758 
 
 3-5466 
 
 8-25 
 
 25-9181 
 
 53-456 
 
 14-25 
 
 44-7677 
 
 159-48 
 
 2-25 
 
 7-0865 
 
 3-9761 
 
 8-375 
 
 26-3108 
 
 55-088 
 
 14-375 
 
 45-1604 
 
 162-30 
 
 2-375 
 
 7-4612 
 
 4-4301 
 
 8-5 
 
 26-7035 
 
 56-745 
 
 14-5 
 
 45-5531 
 
 165-13 
 
 25 
 
 7-8539 
 
 4-9087 
 
 8-625 
 
 27-0962 
 
 58-426 
 
 14-625 
 
 45-9458 
 
 167^99 
 
 2^625 
 
 8-2466 
 
 5-4119 
 
 8-75 
 
 27-4889 
 
 60-132 
 
 14-75 
 
 46-3385 
 
 170^87 
 
 2-75 
 
 8-6393 
 
 5-9396 
 
 8-875 
 
 27-8816 
 
 61-862 
 
 14-875 
 
 46-7312 
 
 173^78 
 
 2-875 
 
 9-0320 
 
 6-4918 
 
 
 
 
 
 
 
 
 
 
 9 
 
 28-2743 
 
 63-617 
 
 15 
 
 47-1239 
 
 176-71 
 
 3 
 
 9-4247 
 
 7-0686 
 
 9-125 
 
 28-6670 
 
 65-397 
 
 15-125 
 
 47-5166 
 
 179-67 
 
 3125 
 
 9-8174 
 
 7-6699 
 
 9-25 
 
 29-0597 
 
 67-201 
 
 15-25 
 
 47-9093 
 
 182-65 
 
 3 25 
 
 10-2102 
 
 8-2958 
 
 9-375 
 
 29-4524 
 
 69-029 
 
 15-375 
 
 48-3020 
 
 185-66 
 
 3375 
 
 10-6029 
 
 8-9462 
 
 9-5 
 
 29-8451 
 
 70-882 
 
 15-5 
 
 48-6947 
 
 188-69 
 
 3 5 
 
 10-9956 
 
 9-6211 
 
 9-625 
 
 30-2378 
 
 72-760 
 
 15-625 
 
 49 0874 
 
 191-75 
 
 3 625 
 
 11-3883 
 
 10-321 
 
 9-75 
 
 30-6305 
 
 74^662 
 
 15-75 
 
 49-4801 
 
 194-83 
 
 3-75 
 
 11-7810 
 
 11-045 
 
 9-875 
 
 31-0232 
 
 76-589 
 
 15-875 
 
 49-8728 
 
 197-93 
 
 3-875 
 
 121737 
 
 11-793 
 
 
 
 
 
 
 
 
 
 
 10 
 
 3r4159 
 
 78-540 
 
 16 
 
 50-2655 
 
 201-06 
 
 4 
 
 12-5664 
 
 12^566 
 
 10-125 
 
 3r8086 
 
 80-516 
 
 16-125 
 
 50-6582 
 
 204-22 
 
 4-125 
 
 12-9591 
 
 13^364 
 
 10-25 
 
 32^2013 
 
 82-516 
 
 16-25 
 
 51-0509 
 
 207-39 
 
 4-25 
 
 13-3518 
 
 14^186 
 
 10-375 
 
 32^5940 
 
 84-541 
 
 16-375 
 
 51-4436 
 
 210-60 
 
 4-375 
 
 13-7445 
 
 15 033 
 
 10-5 
 
 32 •9867 
 
 86-590 
 
 16-5 
 
 51-8363 
 
 213-82 
 
 4-5 
 
 14-1372 
 
 15^904 
 
 10-625 
 
 33-3794 
 
 88-664 
 
 16-625 
 
 52-2-290 
 
 217 08 
 
 4-625 
 
 14-5299 
 
 16^800 
 
 10-75 
 
 33-7721 
 
 90-763 
 
 16-75 
 
 52-6217 
 
 220-35 
 
 4-75 
 
 14-9226 
 
 17-721 
 
 10-875 
 
 34-1648 
 
 92-886 
 
 16-875 
 
 53-0144 
 
 223-65 
 
 4-875 
 
 15-3153 
 
 18 •665 
 
 
 
 
 
 
 
 
 
 
 11 
 
 34-5575 
 
 95-033 
 
 17 
 
 53-4071 
 
 226-98 
 
 5 
 
 15-7080 
 
 19-635 
 
 11-125 
 
 34-9502 
 
 97-205 
 
 17-125 
 
 53-7998 
 
 230-33 
 
 5-125 
 
 16-1007 
 
 20-629 
 
 1125 
 
 35-3429 
 
 99-402 
 
 17-25 
 
 54-1925 
 
 233-71 
 
 5-25 
 
 16^4934 
 
 21-648 
 
 11375 
 
 35-7356 
 
 101-62 
 
 17-375 
 
 54-5852 
 
 237-10 
 
 5-375 
 
 16^8861 
 
 22-691 
 
 115 
 
 36-1283 
 
 103-87 
 
 17-5 
 
 54-9779 
 
 240-53 
 
 5-5 
 
 17-2788 
 
 23-758 
 
 11625 
 
 36-5210 
 
 106-14 
 
 17^625 
 
 55-3706 
 
 243-98 
 
 5^625 
 
 17^6715 
 
 24-850 
 
 11-75 
 
 33-9137 
 
 108-43 
 
 17^75 
 
 55-7633 
 
 247-45 
 
 5-75 
 
 18 •0642 
 
 25-967 
 
 11 •875 
 
 37-3064 
 
 110-75 
 
 17-875 
 
 56-1560 
 
 250-95 
 
 5-876 
 
 18^4569 
 
 27-109 
 
 
 
 
 
 
 
Areas and Circumferences 71 1 
 
 Table of Circumferences and Areas of C\vc\ts— continued. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 18 
 
 56-5487 
 
 254-47 
 
 24 
 
 75-3982 
 
 452-39 
 
 30 
 
 94-2478 
 
 706-86 
 
 18125 
 
 56-9414 
 
 258-02 
 
 24-125 
 
 75-7909 
 
 457-11 
 
 30-125 
 
 94-6405 
 
 712-76 
 
 18-25 
 
 57-3341 
 
 261-59 
 
 24-25 
 
 76-1836 
 
 461-86 
 
 30-25 
 
 95-0332 
 
 718-69 
 
 18-375 
 
 57-7268 
 
 265-18 
 
 24-375 
 
 76-5763 
 
 460-64 
 
 30-375 
 
 95-4^259 
 
 724-64 
 
 18-5 
 
 58-1195 
 
 268-80 
 
 24-5 
 
 76-9690 
 
 471-44 
 
 30-5 
 
 95-8186 
 
 730-62 
 
 18-625 
 
 58-51-22 
 
 272-45 
 
 •24-625 
 
 77-3617 
 
 476-26 
 
 30-625 
 
 96-2113 
 
 736-62 
 
 18-75 
 
 58-9049 
 
 276-12 
 
 •24-75 
 
 77-7544 
 
 481-11 
 
 30-75 
 
 96-6040 
 
 742-64 
 
 18-875 
 
 59-2976 
 
 279-81 
 
 -24-875 
 
 78-1471 
 
 485-98 
 
 30-875 
 
 96-9967 
 
 748-69 
 
 19 
 
 59-6903 
 
 283-53 
 
 25 
 
 78-5398 
 
 490-87 
 
 31 
 
 97-3894 
 
 754-77 
 
 19-125 
 
 60-0830 
 
 287-27 
 
 25-125 
 
 78-9325 
 
 495-79 
 
 31-125 
 
 97-7821 
 
 760-87 
 
 19-25 
 
 60-4757 
 
 •291-04 
 
 25-25 
 
 79-3252 
 
 500-74 
 
 31-25 
 
 98-1748 
 
 766-99 
 
 19-375 
 
 60-8684 
 
 294-83 
 
 25-375 
 
 79-7179 
 
 505-71 
 
 31-375 
 
 98-5675 
 
 773-14 
 
 19-5 
 
 61-2611 
 
 298-65 
 
 25-5 
 
 80-1106 
 
 510-71 
 
 31-5 
 
 98-9602 
 
 779-31 
 
 19-625 
 
 61-6538 
 
 302-49 
 
 25-625 
 
 80-5033 
 
 515-72 
 
 31 -625 
 
 99-35-29 
 
 785-51 
 
 19-75 
 
 62-0465 
 
 306-35 
 
 25-75 
 
 80-8960 
 
 520-77 
 
 31-75 
 
 99-7456 
 
 791-73 
 
 19-875 
 
 62-4392 
 
 310-24 
 
 25-875 
 
 81-2887 
 
 525-84 
 
 31-875 
 
 100-138 
 
 797-98 
 
 20 
 
 62-8319 
 
 314-16 
 
 26 
 
 81-6814 
 
 530-93 
 
 32 
 
 100-531 
 
 804-25 
 
 20-125 
 
 63-2246 
 
 318-10 
 
 26-125 
 
 82 0741 
 
 536-05 
 
 32-1-25 
 
 100-924 
 
 810-54 
 
 20-25 
 
 63-6173 
 
 322-06 
 
 26-25 
 
 82-4668 
 
 541-19 
 
 .•^2-25 
 
 101-316 
 
 816-86 
 
 20-375 
 
 64-0100 
 
 326-05 
 
 26-375 
 
 82-8595 
 
 546-35 
 
 32-375 
 
 101-709 
 
 823-21 
 
 20-5 
 
 64-4026 
 
 330-06 
 
 26-5 
 
 83-2522 
 
 551-55 
 
 32-5 
 
 102-102 
 
 829-58 
 
 20-625 
 
 64-7953 
 
 334-10 
 
 26-625 
 
 83-6449 
 
 556-76 
 
 32-625 
 
 102-494 
 
 835-97 
 
 20-75 
 
 65-1880 
 
 338-16 
 
 26-75 
 
 84-0376 
 
 562-00 
 
 32-75 
 
 102-887 
 
 842-39 
 
 20-875 
 
 65-5807 
 
 342-25 
 
 26-875 
 
 84-4303 
 
 567-27 
 
 32-875 
 
 103-280 
 
 848-83 
 
 21 
 
 65-9734 
 
 346-36 
 
 27 
 
 84-8230 
 
 572-56 
 
 33 
 
 103-673 
 
 855-30 
 
 21-125 
 
 66-3661 
 
 350-50 
 
 •27-125 
 
 85-2157 
 
 577-87 
 
 33-125 
 
 104-065 
 
 861-79 
 
 21-25 
 
 66-7588 
 
 354-66 
 
 27-25 
 
 85-6084 
 
 583-21 
 
 33-25 
 
 104-458 
 
 868-31 
 
 21-375 
 
 67-1515 
 
 358-84 
 
 27-375 
 
 86-0011 
 
 588-57 
 
 33-375 
 
 104-851 
 
 874-85 
 
 21-5 
 
 67-5442 
 
 363-06 
 
 27-5 
 
 86-3938 
 
 593-96 
 
 33-5 
 
 105-243 
 
 8S1-41 
 
 21-625 
 
 67-9369 
 
 367-28 
 
 27-625 
 
 86-7865 
 
 599-37 
 
 33-625 
 
 105-636 
 
 888-00 
 
 21-75 
 
 68-3296 
 
 371-54 
 
 27-75 
 
 87-1792 
 
 604-81 
 
 33-75 
 
 106-029 
 
 894-62 
 
 21-875 
 
 68-7223 
 
 375-83 
 
 27-875 
 
 87-5719 
 
 610-27 
 
 33-875 
 
 106-421 
 
 901-26 
 
 22 
 
 69-1150 
 
 380-13 
 
 28 
 
 87-9646 
 
 615-75 
 
 34 
 
 106-814 
 
 907-92 
 
 22-125 
 
 69-5077 
 
 384-46 
 
 28-125 
 
 88-3573 
 
 621-26 
 
 34-125 
 
 107-207 
 
 914-61 
 
 22-25 
 
 69-9004 
 
 388-82 
 
 28-25 
 
 88-7500 
 
 626-80 
 
 34-25 
 
 107-600 
 
 921-32 
 
 22-375 
 
 70-2931 
 
 393-20 
 
 28-375 
 
 89-1427 
 
 632-36 
 
 34-375 
 
 107-992 
 
 9-28-06 
 
 22-5 
 
 70-6858 
 
 397-61 
 
 28-5 
 
 89-5354 
 
 637-94 
 
 34-5 
 
 108-385 
 
 934-82 
 
 •22-625 
 
 71-0785 
 
 402 04 
 
 28-625 
 
 89-9281 
 
 643-55 
 
 34-625 
 
 108-788 
 
 941-61 
 
 22-75 
 
 71-4712 
 
 406-49 
 
 •28-75 
 
 90-3208 
 
 649-18 
 
 34-75 
 
 109-170 
 
 948-42 
 
 22-875 
 
 71-8639 
 
 410-97 
 
 28-875 
 
 90-7135 
 
 654-84 
 
 34-875 
 
 109-563 
 
 955-25 
 
 23 
 
 72-2566 
 
 415-48 
 
 29 
 
 91-1062 
 
 660-52 
 
 35 
 
 109-956 
 
 962-11 
 
 23-125 
 
 72-6493 
 
 4-20-00 
 
 29-125 
 
 91-4989 
 
 666-23 
 
 35-125 
 
 110-348 
 
 969-00 
 
 23-25 
 
 73-0420 
 
 424-56 
 
 29-25 
 
 91-8916 
 
 671-96 
 
 35-25 
 
 110-741 
 
 975-91 
 
 23-375 
 
 73-4347 
 
 429-13 
 
 29-375 
 
 92-2843 
 
 677-71 
 
 35-375 
 
 111-134 
 
 982-84 
 
 23-5 
 
 73-8274 
 
 433-74 
 
 29-5 
 
 92-6770 
 
 683-49 
 
 35-5 
 
 111-527 
 
 989-80 
 
 23-625 
 
 74-2201 
 
 438-36 
 
 29-625 
 
 93-0697 
 
 689-30 
 
 35-6-25 
 
 111-919 
 
 996-78 
 
 23-75 
 
 74-6128 
 
 443 01 
 
 29-75 
 
 93-4624 
 
 695-13 
 
 35-75 
 
 112-312 
 
 1003-8 
 
 23-875 
 
 75-0055 
 
 447-69 
 
 29-875 
 
 93-8551 
 
 700-98 
 
 35 -875 
 
 112-705 
 
 1010-8 
 
712 ''Verbal" Notes and Sketches 
 
 Table of Circumferences and Areas of Circles— continugd. 
 
 D!am. 
 
 Grcum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Aiex 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 Inchcj. 
 
 Inches. 
 
 Sq. In. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 36 
 
 113 097 
 
 1017-9 
 
 42 
 
 131-947 
 
 1385-4 
 
 48 
 
 150-796 
 
 1809-6 
 
 36 125 
 
 113-490 
 
 1025 
 
 42-125 
 
 132-340 
 
 1393-7 
 
 48-125 
 
 151-189 
 
 1819-0 
 
 36-25 
 
 113-883 
 
 1032-1 
 
 42-25 
 
 132-732 
 
 1402-0 
 
 48-25 
 
 151-582 
 
 1828-5 
 
 36-375 
 
 114-275 
 
 1039-2 
 
 42-375 
 
 133-125 
 
 1410-3 
 
 48-375 
 
 151-975 
 
 1837 -a 
 
 36-5 
 
 114-668 
 
 1046-3 
 
 42-5 
 
 133-518 
 
 1418-6 
 
 48-5 
 
 152-367 
 
 1847-5 
 
 36-625 
 
 115-061 
 
 1053-5 
 
 42-625 
 
 133-910 
 
 1427-0 
 
 48-625 
 
 152-760 
 
 1857-0 
 
 36-75 
 
 115-454 
 
 1060-7 
 
 42-75 
 
 134-303 
 
 1435-4 
 
 48-75 
 
 153-153 
 
 1866-5 
 
 36-875 
 
 116-846 
 
 1068-0 
 
 42-875 
 
 134-696 
 
 1443-8 
 
 48-875 
 
 153-544 
 
 1876-1 
 
 37 
 
 116-239 
 
 1075-2 
 
 43 
 
 135-088 
 
 1452-2 
 
 49 
 
 153-938 
 
 1885-7 
 
 37-125 
 
 116-632 
 
 1082-5 
 
 43 125 
 
 135-481 
 
 1460-7 
 
 49-125 
 
 154-331 
 
 1895-4 
 
 37-25 
 
 117-024 
 
 1089-8 
 
 43-25 
 
 135-874 
 
 1469-1 
 
 49-25 
 
 154-723 
 
 1905-0 
 
 37-375 
 
 117-417 
 
 1097-1 
 
 43-375 
 
 136-267 
 
 1477-6 
 
 49-375 
 
 155-116 
 
 1914-7 
 
 37-5 
 
 117-810 
 
 1104-5 
 
 43-5 
 
 136-659 
 
 1486-2 
 
 49-5 
 
 155-509 
 
 1924-2 
 
 37.625 
 
 118-202 
 
 1111-8 
 
 43-625 
 
 137-052 
 
 1494-7 
 
 49-625 
 
 155-904 
 
 1934-2 
 
 37-75 
 
 118-596 
 
 1119-2 
 
 43-75 
 
 137-445 
 
 1503-3 
 
 49-75 
 
 156-294 
 
 1943-9 
 
 37-875 
 
 118-988 
 
 1126-7 
 
 43-875 
 
 137-837 
 
 1511-9 
 
 49-875 
 
 156-687 
 
 1953-7 
 
 38 
 
 119-381 
 
 1134-1 
 
 44 
 
 138-230 
 
 1520-5 
 
 50 
 
 157-080 
 
 1963-5 
 
 38-125 
 
 119-773 
 
 1141-6 
 
 44-125 
 
 138-623 
 
 1529-2 
 
 50-125 
 
 157-472 
 
 1973-3 
 
 38-25 
 
 1-20-166 
 
 1149-1 
 
 44-25 
 
 139-015 
 
 1537-9 
 
 50-25 
 
 157-865 
 
 1983-2 
 
 38-375 
 
 120-559 
 
 1156-6 
 
 44-375 
 
 139-408 
 
 1546-6 
 
 50-375 
 
 158-258 
 
 1993-1 
 
 38-5 
 
 120-951 
 
 1164-2 
 
 44-5 
 
 139-801 
 
 1555-3 
 
 50-5 
 
 158-650 
 
 2003-0 
 
 38-625 
 
 121-344 
 
 1171-7 
 
 44-625 
 
 140-194 
 
 1564-0 
 
 50-625 
 
 159 043 
 
 2012-9 
 
 38-75 
 
 121-737 
 
 1179-3 
 
 44-75 
 
 140-586 
 
 1572-8 
 
 50-75 
 
 159-436 
 
 2022-8 
 
 38-875 
 
 122-129 
 
 1186-9 
 
 44-875 
 
 140-979 
 
 1581-6 
 
 50-875 
 
 159-829 
 
 2032-8 
 
 39 
 
 122-522 
 
 1194-6 
 
 45 
 
 141-372 
 
 1590-4 
 
 51 
 
 160-221 
 
 2042-8 
 
 39-125 
 
 122-915 
 
 1202-3 
 
 45-125 
 
 141-764 
 
 1599-3 
 
 51-125 
 
 160-614 
 
 2052-8 
 
 39-25 
 
 123-308 
 
 1210-0 
 
 45 '25 
 
 142-157 
 
 1608-2 
 
 51-25 
 
 161-007 
 
 2062-9 
 
 39-375 
 
 123-700 
 
 1217-7 
 
 45-375 
 
 142-550 
 
 16170 
 
 51-375 
 
 161-399 
 
 2073-0 
 
 39-5 
 
 124-093 
 
 1225-4 
 
 45-5 
 
 142-942 
 
 1626-0 
 
 51-5 
 
 161-792 
 
 2083-1 
 
 39-625 
 
 124-486 
 
 1233-2 
 
 45-625 
 
 143-335 
 
 1634-9 
 
 51-625 
 
 162-185 
 
 2093-2 
 
 39-75 
 
 124-878 
 
 1241-0 
 
 45-75 
 
 143-7-28 
 
 1643-9 
 
 51-75 
 
 162-577 
 
 2103-3 
 
 39-875 
 
 125-271 
 
 1248-8 
 
 45-875 
 
 144-121 
 
 1652-9 
 
 51-875 
 
 162-970 
 
 2113-5 
 
 40 
 
 125-664 
 
 1256-6 
 
 46 
 
 144-513 
 
 1661-9 
 
 52 
 
 163-363 
 
 2123-7 
 
 40-125 
 
 126-056 
 
 1264-5 
 
 46-125 
 
 144-906 
 
 1670-9 
 
 52-125 
 
 163-756 
 
 2133-9 
 
 40-25 
 
 126-449 
 
 1272-4 
 
 46-25 
 
 145-299 
 
 1680 
 
 52-25 
 
 164-148 
 
 2144-2 
 
 40-375 
 
 126-842 
 
 1280-3 
 
 46-375 
 
 145-691 
 
 1689-1 
 
 52-375 
 
 164-541 
 
 2154-5 
 
 40-6 
 
 127-235 
 
 1288-2 
 
 46-5 
 
 146-084 
 
 1698-2 
 
 52-5 
 
 164-934 
 
 2164-8 
 
 40-625 
 
 127-627 
 
 1296-2 
 
 46-625 
 
 146-477 
 
 1707-4 
 
 52-625 
 
 165-326 
 
 2175-1 
 
 40-75 
 
 128-020 
 
 1304-2 
 
 46-75 
 
 146-869 
 
 1716-5 
 
 52-75 
 
 165-719 
 
 2185-4 
 
 40-875 
 
 128-413 
 
 1312-2 
 
 46-875 
 
 147-262 
 
 1725-7 
 
 52-875 
 
 166-112 
 
 2195-8 
 
 41 
 
 128-805 
 
 1320-3 
 
 47 
 
 147-655 
 
 1734-9 
 
 53 
 
 166-504 
 
 2206 2 
 
 41-125 
 
 129-198 
 
 1328-3 
 
 47-125 
 
 148-048 
 
 1744-2 
 
 53-125 
 
 166-897 
 
 2216-6 
 
 41-25 
 
 129-591 
 
 1336-4 
 
 47-25 
 
 148-440 
 
 1753-6 
 
 53-25 
 
 167-290 
 
 2227 
 
 41-375 
 
 129-993 
 
 1344-5 
 
 47-375 
 
 148-833 
 
 1762-7 
 
 53-375 
 
 167-683 
 
 2237-5 
 
 41-5 
 
 130-376 
 
 1352-7 
 
 47-5 
 
 149-226 
 
 1772-1 
 
 53-5 
 
 168-075 
 
 2248-0 
 
 41-625 
 
 130-769 
 
 1360-8 
 
 47-625 
 
 149-618 
 
 1781-4 
 
 53-625 
 
 168-468 
 
 2258-5 
 
 41-75 
 
 131-161 
 
 1369 
 
 47-75 
 
 150011 
 
 1790-8 
 
 53-75 
 
 168-861 
 
 2269 1 
 
 41-875 
 
 131-554 
 
 1377-2 
 
 47-875 
 
 150-404 
 
 1800-1 
 
 53-875 
 
 169-253 
 
 2279-6 
 
Areas and Circumferences 7 1 3 
 
 Table of Circumferences and Areas of Circles— ca/i^i/tued. 
 
 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 54 
 
 169-646 
 
 2-290-2 
 
 60 
 
 188-496 
 
 28^27 -4 
 
 66 
 
 •207-345 
 
 3421-2 
 
 04 125 
 
 170-039 
 
 2300-8 
 
 60-125 
 
 188-888 
 
 2839-2 
 
 66-125 
 
 207-738 
 
 3434-3 
 
 04-25 
 
 170-431 
 
 2311-5 
 
 60-25 
 
 189-281 
 
 2851-0 
 
 66-25 
 
 •208-131 
 
 3447-2 
 
 54-375 
 
 170-824 
 
 2322 1 
 
 60-375 
 
 189-674 
 
 2862-9 
 
 66-375 
 
 208-5'23 
 
 3460-2 
 
 54-5 
 
 171-217 
 
 2332-8 
 
 60-5 
 
 190-066 
 
 2874-8 
 
 66-5 
 
 208-916 
 
 3473-2 
 
 54-fy25 
 
 171-609 
 
 2343-5 
 
 60-625 
 
 190-459 
 
 2886-6 
 
 66-625 
 
 209-309 
 
 3486-3 
 
 54-75 
 
 172-002 
 
 2354-3 
 
 60-75 
 
 190-852 
 
 2898-6 
 
 66-75 
 
 209-701 
 
 3499-4 
 
 54-875 
 
 172-395 
 
 2365 
 
 60-875 
 
 191-244 
 
 2910-6 
 
 66-875 
 
 210-094 
 
 3512-6 
 
 55 
 
 172-788 
 
 2375-8 
 
 61 
 
 191-637 
 
 2922-5 
 
 67 
 
 210-487 
 
 35'25-7 
 
 55-125 
 
 173-180 
 
 2386-6 
 
 61-125 
 
 192030 
 
 2934-5 
 
 67-125 
 
 210-879 
 
 3538-8 
 
 55-25 
 
 173-573 
 
 2397-5 
 
 61-25 
 
 192-423 
 
 2946-6 
 
 67-25 
 
 211-272 
 
 3552-0 
 
 55-375 
 
 173-966 
 
 •2408-3 
 
 61-375 
 
 192-815 
 
 2958-6 
 
 67-375 
 
 211-665 
 
 3565-2 
 
 55-5 
 
 174-358 
 
 2419-2 
 
 61-5 
 
 193-208 
 
 2970-6 
 
 67-5 
 
 212-058 
 
 3578-5 
 
 65-625 
 
 174-751 
 
 2430-1 
 
 61-625 
 
 193-601 
 
 2982-7 
 
 67-625 
 
 212-450 
 
 3591-7 
 
 55-75 
 
 175144 
 
 2441 1 
 
 61-75 
 
 193-993 
 
 2994-8 
 
 67-75 
 
 212-843 
 
 3605-0 
 
 55-875 
 
 175-536 
 
 2452 
 
 61-876 
 
 194-386 
 
 3006-9 
 
 67-875 
 
 213-236 
 
 3618-3 
 
 56 
 
 175-929 
 
 2463 
 
 62 
 
 194-779 
 
 3019-1 
 
 68 
 
 213-628 
 
 3631-7 
 
 56-125 
 
 176-322 
 
 2474-0 
 
 62-125 
 
 195-171 
 
 3031-3 
 
 68-125 
 
 214 021 
 
 3645-0 
 
 56-25 
 
 176-715 
 
 2485-0 
 
 62-25 
 
 195-564 
 
 3043-5 
 
 68-25 
 
 214-414 
 
 3658-4 
 
 56-375 
 
 177-107 
 
 2496-1 
 
 62-375 
 
 195-957 
 
 3055-7 
 
 68-375 
 
 214-806 
 
 3671-8 
 
 56-5 
 
 177-500 
 
 2507-2 
 
 62-5 
 
 196-350 
 
 3068 
 
 68-5 
 
 215-199 
 
 3686-3 
 
 66 -6-25 
 
 177-893 
 
 2518-3 
 
 62-625 
 
 196-742 
 
 3080-3 
 
 68-625 
 
 215-592 
 
 3698-7 
 
 56-75 
 
 178-285 
 
 2529-4 
 
 62-75 
 
 197-135 
 
 3092-6 
 
 68-75 
 
 215-984 
 
 3712-2 
 
 56-875 
 
 178-678 
 
 2540-6 
 
 62-875 
 
 197-528 
 
 3104-9 
 
 68-876 
 
 216-337 
 
 3725-7 
 
 57 
 
 179 071 
 
 2551-8 
 
 63 
 
 197-920 
 
 3117-2 
 
 69 
 
 216-770 
 
 3739-3 
 
 57-125 
 
 179-463 
 
 2563-0 
 
 63 125 
 
 198-313 
 
 3129-6 
 
 69-125 
 
 217-163 
 
 3752-8 
 
 57-25 
 
 179-856 
 
 2574-2 
 
 63-25 
 
 198-706 
 
 31420 
 
 69-25 
 
 217-555 
 
 3766-4 
 
 57-375 
 
 180-249 
 
 2585-4 
 
 63-375 
 
 199 098 
 
 3154-5 
 
 69-375 
 
 217-948 
 
 3780-0 
 
 57-5 
 
 180-642 
 
 2596-7 
 
 63-5 
 
 199-491 
 
 3166-9 
 
 69-5 
 
 218-341 
 
 3793-7 
 
 67-625 
 
 181-034 
 
 2608-0 
 
 63-625 
 
 199-884 
 
 3179-4 
 
 69-625 
 
 218-733 
 
 3807-3 
 
 67-75 
 
 181-427 
 
 2619-4 
 
 63-75 
 
 200-277 
 
 3191-9 
 
 69-75 
 
 219-126 
 
 3821-0 
 
 57-875 
 
 181-820 
 
 2630-7 
 
 63-875 
 
 200-669 
 
 3204-4 
 
 69-875 
 
 219-519 
 
 3834-7 
 
 58 
 
 182-212 
 
 2642 1 
 
 64 
 
 201-062 
 
 3217-0 
 
 70 
 
 219-911 
 
 3848-5 
 
 58-125 
 
 182-605 
 
 2653-5 
 
 64-125 
 
 201-465 
 
 3-229-6 
 
 70-125 
 
 220-304 
 
 3862-2 
 
 58-25 
 
 182-998 
 
 2664-9 
 
 64-25 
 
 201-847 
 
 3242-2 
 
 70-25 
 
 220-697 
 
 3876 
 
 58-375 
 
 183-390 
 
 2676-4 
 
 64-375 
 
 202-240 
 
 3254-8 
 
 70-375 
 
 221 090 
 
 3889-8 
 
 58-5 
 
 183-783 
 
 2687-8 
 
 64-5 
 
 202-633 
 
 3267-5 
 
 70-5 
 
 221-482 
 
 3903-6 
 
 58-625 
 
 184-176 
 
 2699-3 
 
 64-625 
 
 203-025 
 
 3280-1 
 
 70-625 
 
 221 ^875 
 
 3917-5 
 
 58-75 
 
 184-569 
 
 2710'9 
 
 64-75 
 
 203-418 
 
 3292-8 
 
 70-75 
 
 222^268 
 
 3931-4 
 
 58-875 
 
 184-961 
 
 2722-4 
 
 64-875 
 
 203-811 
 
 3305-6 
 
 70-875 
 
 222^660 
 
 3945-3 
 
 59 
 
 185-354 
 
 27340 
 
 65 
 
 204-204 
 
 3318-3 
 
 71 
 
 2^23 053 
 
 3959-2 
 
 59-125 
 
 185-747 
 
 2745-6 
 
 65-125 
 
 204-596 
 
 3331-1 
 
 71-125 
 
 223 ^446 
 
 3973 1 
 
 59-25 
 
 186-139 
 
 2757-2 
 
 65-25 
 
 204-989 
 
 3343-9 
 
 71-25 
 
 •223 ^838 
 
 3987-1 
 
 59-375 
 
 186-532 
 
 2768-8 
 
 65-376 
 
 205-382 
 
 33.56-7 
 
 71-375 
 
 224-231 
 
 4001-1 
 
 69-5 
 
 186-925 
 
 2780-5 
 
 65-5 
 
 205-774 
 
 3369-6 
 
 71-5 
 
 224-624 
 
 4015-2 
 
 59-625 
 
 187-317 
 
 2792-2 
 
 65-625 
 
 206-167 
 
 3382-4 
 
 71-625 
 
 2-25-017 
 
 4029-2 
 
 59-75 
 
 187-710 
 
 2803-9 
 
 65-75 
 
 •206-560 
 
 .•5395 -3 
 
 71-75 
 
 225-409 
 
 4043-3 
 
 59-875 
 
 188-103 
 
 2815-7 
 
 65-875 
 
 206-952 1 
 
 3408-2 
 
 71-876 
 
 225-802 
 
 4057-4 
 
714 "Verbal" Notes and Sketches 
 
 Table of Circumferences and Areas of CircXts— continued. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Diam, 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 Inches. 
 
 Inches. 
 
 Sq In. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 72 
 
 226-195 
 
 4071-5 
 
 78 
 
 245-044 
 
 4778-4 
 
 84 
 
 263-894 
 
 5541-8 
 
 72 125 
 
 2-26-587 
 
 4085-7 
 
 78-125 
 
 -245-437 
 
 4793-7 
 
 84-125 
 
 264-286 
 
 5558-3 
 
 72-25 
 
 226-980 
 
 4099-8 
 
 78-25 
 
 245-830 
 
 4809-0 
 
 84-25 
 
 264-679 
 
 5574-8 
 
 72-375 
 
 227-373 
 
 4114-0 
 
 78-375 
 
 246-2'22 
 
 48-24-4 
 
 84-375 
 
 265-072 
 
 5591-4 
 
 72-5 
 
 227-765 
 
 4128-2 
 
 78-5 
 
 246-615 
 
 4839-8 
 
 84-5 
 
 265-465 
 
 5607-9 
 
 72-625 
 
 228-158 
 
 4142-5 
 
 78-625 
 
 247-008 
 
 4855-2 
 
 84-6-25 
 
 265-857 
 
 5624-5 
 
 72-75 
 
 228-551 
 
 4156-8 
 
 78-75 
 
 247-400 
 
 4870-7 
 
 84-75 
 
 266-250 
 
 5641-2 
 
 72-875 
 
 228-944 
 
 4171-1 
 
 78-875 
 
 247-793 
 
 4886-2 
 
 84-875 
 
 266-643 
 
 5657-8 
 
 73 
 
 229-336 
 
 4185-4 
 
 79 
 
 248-186 
 
 4901-7 
 
 85 
 
 267-035 
 
 5674-5 
 
 73-125 
 
 229-729 
 
 4199-7 
 
 79-125 
 
 248-579 
 
 4917-2 
 
 85-125 
 
 267-428 
 
 5691 -2 
 
 73-25 
 
 230-122 
 
 4214-1 
 
 79-25 
 
 248-971 
 
 4932-7 
 
 85-25 
 
 267-821 
 
 5707-9 . 
 
 73-375 
 
 230-514 
 
 4228-5 
 
 79-375 
 
 249-3G4 
 
 4948-3 
 
 85-375 
 
 •268-213 
 
 5724-7 r 
 
 73-5 
 
 230-907 
 
 4242-9 
 
 79-5 
 
 249-757 
 
 4963-9 
 
 85-5 
 
 -268-606 
 
 5741-5 
 
 73-625 
 
 231-300 
 
 4257-4 
 
 79-625 
 
 250-149 
 
 4979-5 
 
 85-625 
 
 268-999 
 
 5758-3 
 
 73-75 
 
 231-692 
 
 4271-8 
 
 79-75 
 
 250-542 
 
 4995-2 
 
 85-75 
 
 269-392 
 
 5775-1 
 
 73-875 
 
 232-085 
 
 4286-3 
 
 79-875 
 
 250-935 
 
 5010-9 
 
 85-875 
 
 269-784 
 
 5791-9 
 
 74 
 
 232-478 
 
 4300-8 
 
 80 
 
 251-3-27 
 
 50-26-5 
 
 86 
 
 270-177 
 
 5808-8 
 
 74-125 
 
 232-871 
 
 4315-4 
 
 80-125 
 
 251-720 
 
 5042-3 
 
 86-125 
 
 270-570 
 
 5825-7 
 
 74-25 
 
 233-263 
 
 43-29-9 
 
 80-25 
 
 252-113 
 
 5058-0 
 
 86-25 
 
 270-962 
 
 5842-6 
 
 74-375 
 
 233-656 
 
 4344-5 
 
 80-375 
 
 252-506 
 
 5073-8 
 
 86-375 
 
 271-355 
 
 5859-6 
 
 74-5 
 
 234-049 
 
 4359-2 
 
 80-5 
 
 252-898 
 
 5089-6 
 
 86-5 
 
 271-748 
 
 5876-5 
 
 74-625 
 
 234-441 
 
 4373-8 
 
 80-625 
 
 253-291 
 
 5105-4 
 
 86-625 
 
 272-140 
 
 5893-5 
 
 74-75 
 
 234-834 
 
 4388-5 
 
 80-75 
 
 -253-684 
 
 5121-2 
 
 86-75 
 
 272-533 
 
 5910-6 
 
 74-875 
 
 235-227 
 
 4403-1 
 
 80-875 
 
 254-076 
 
 5137-1 
 
 86-875 
 
 272-926 
 
 5927-6 
 
 75 
 
 235-619 
 
 4417-9 
 
 81 
 
 254-469 
 
 5153 
 
 87 
 
 273-319 
 
 5944-7 
 
 75-125 
 
 236-012 
 
 4432-6 
 
 81-125 
 
 254-862 
 
 5168-9 
 
 87-125 
 
 273-711 
 
 5961 -8 
 
 75-25 
 
 236-405 
 
 4447-4 
 
 81-25 
 
 255-254 
 
 5184-9 
 
 87-25 
 
 274-104 
 
 5978-9 
 
 75-375 
 
 236-798 
 
 4462-2 
 
 81-375 
 
 255-647 
 
 5200-8 
 
 87-375 
 
 •274-497 
 
 5996-0 
 
 75-5 
 
 237-190 
 
 4477-0 
 
 81-5 
 
 256-040 
 
 5216-8 
 
 87-5 
 
 274-889 
 
 6013-2 
 
 75-625 
 
 237-583 
 
 4491 -8 
 
 81-6-25 
 
 256-433 
 
 5232-8 
 
 87-6-25 
 
 275-282 
 
 6030-4 
 
 75-75 
 
 237-976 
 
 4506-7 
 
 81-75 
 
 256-825 
 
 5248-9 
 
 87-75 
 
 275-695 
 
 6047-6 
 
 75-875 
 
 238-368 
 
 4521-5 
 
 81-875 
 
 257-218 
 
 5264-9 
 
 87-875 
 
 276-067 
 
 6064-9 
 
 76 
 
 238-761 
 
 4536-5 
 
 82 
 
 257-611 
 
 5-281-0 
 
 88 
 
 276-460 
 
 6082-1 
 
 76-125 
 
 239-154 
 
 4551-4 
 
 82-125 
 
 258-003 
 
 5297-1 
 
 88-125 
 
 276-853 
 
 6099-4 
 
 76-25 
 
 239-546 
 
 4566-4 
 
 82-25 
 
 258-396 
 
 5313-3 
 
 88-25 
 
 277-246 
 
 6256-7 
 
 76-375 
 
 239-939 
 
 4581-3 
 
 82-375 
 
 258-789 
 
 5329-4 
 
 88-375 
 
 277-638 
 
 6134-1 
 
 76-5 
 
 240-332 
 
 4596-3 
 
 82-5 
 
 259-181 
 
 5345-6 
 
 88-5 
 
 278-031 
 
 6151-4 
 
 76 ■6-25 
 
 240-725 
 
 4611-4 
 
 82-6-25 
 
 259-574 
 
 5361-8 
 
 88 •6-25 
 
 278-424 
 
 6168-8 
 
 76-75 
 
 241-117 
 
 4626-4 
 
 82-75 
 
 259-967 
 
 5378-1 
 
 88-75 
 
 278-816 
 
 6186-2 
 
 76-875 
 
 241-510 
 
 4641-5 
 
 82-875 
 
 260-359 
 
 5394-3 
 
 88-875 
 
 279-209 
 
 6203-7 
 
 77 
 
 241-903 
 
 4656-6 
 
 83 
 
 260-752 
 
 5410-6 
 
 89 
 
 279-602 
 
 6-221-1 
 
 77-1-25 
 
 242-295 
 
 4671-8 
 
 83-125 
 
 261-145 
 
 5426-9 
 
 89 1-25 
 
 279-994 
 
 6-238-6 
 
 77-25 
 
 242-688 
 
 4686-9 
 
 83-25 
 
 261-538 
 
 5443-3 
 
 89-25 
 
 280-387 
 
 6-256-1 
 
 77-375 
 
 243-081 
 
 4702-1 
 
 83-375 
 
 261-930 
 
 5459-6 
 
 89-375 
 
 280-780 
 
 6273-7 
 
 77-5 
 
 243-473 
 
 4717-3 
 
 83-5 
 
 262-323 
 
 5476-0 
 
 89-5 
 
 281-173 
 
 6-291 -2 
 
 77-625 
 
 243-866 
 
 4732-5 
 
 83-625 
 
 262-716 
 
 5492-4 
 
 89-6-25 
 
 281-565 
 
 6308-8 
 
 77-75 
 
 244-259 
 
 4747-8 
 
 83-75 
 
 263-108 
 
 5508-8 
 
 89-75 
 
 281-958 
 
 6326-4 
 
 77-875 
 
 244-652 
 
 4763-1 
 
 83-875 
 
 263-501 
 
 5525-3 
 
 89-875 
 
 282-351 
 
 6344-1 
 
Areas and Circumferences 715 
 
 Table of Circumferences and Areas of Circles— tro/i/inuetf. 
 
 D!am. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Diam. 
 
 Circum. 
 
 Area. 
 
 Inches. 
 
 Inches. 
 
 .<5.]- In. 
 
 Inches. 
 
 Inches. 
 
 Sq. In. 
 
 Inches. 
 
 Inch'-s. 
 
 Sq. In. 
 
 90 
 
 282-743 
 
 6361-7 
 
 94 
 
 295-310 
 
 6939-8 
 
 98 
 
 307-876 
 
 7543-0 
 
 901'2o 
 
 283 136 
 
 6379-4 
 
 94-1-25 
 
 295-702 
 
 69.58-2 
 
 98-1 '25 
 
 308-269 
 
 7562-2 
 
 90-25 
 
 283-529 
 
 6397-1 
 
 94-25 
 
 296-095 
 
 6976-7 
 
 98-25 
 
 308-661 
 
 7581-5 
 
 90-375 
 
 283-921 
 
 6414-9 
 
 94-375 
 
 296-488 
 
 6995-3 
 
 98-375 
 
 309-054 
 
 7600-8 
 
 90-5 
 
 284-314 
 
 6432-6 
 
 94-5 
 
 296-881 
 
 7013-8 
 
 98-5 
 
 309-447 
 
 7620-1 
 
 90-625 
 
 284-707 
 
 6450-4 
 
 94-625 
 
 •297-273 
 
 7032-4 
 
 98-6'25 
 
 309-840 
 
 76.39-5 
 
 90-75 
 
 285-100 
 
 6468-2 
 
 94-75 
 
 297-666 
 
 7051-0 
 
 98-75 
 
 310-232 
 
 7658-9 
 
 90-875 
 
 285-492 
 
 6486-0 
 
 94-875 
 
 298-059 
 
 7069-6 
 
 98-875 
 
 310-625 
 
 7678-3 
 
 91 
 
 285-885 
 
 6503-9 
 
 95 
 
 298-451 
 
 7088-2 
 
 99 
 
 311-018 
 
 7697-7 
 
 91 125 
 
 286-278 
 
 6521-8 
 
 95-125 
 
 •298-844 
 
 7106-9 
 
 99-125 
 
 311-410 
 
 7717-1 
 
 91-25 
 
 286-670 
 
 6539-7 
 
 95-25 
 
 299-237 
 
 7125-6 
 
 99-25 
 
 311-803 
 
 7736-6 
 
 91 -375 
 
 287-063 
 
 6557-6 
 
 95-375 
 
 •299-629 
 
 7144-3 
 
 99-375 
 
 312-196 
 
 7756-1 
 
 91-5 
 
 287-456 
 
 6575 "5 
 
 95.5 
 
 3(X)022 
 
 7163-0 
 
 99-5 
 
 312-588 
 
 7775-6 
 
 91-6-25 
 
 287-848 
 
 6.593-5 
 
 95.625 
 
 300-415 
 
 7181-8 
 
 99-625 
 
 312-981 
 
 7795-2 
 
 91-75 
 
 288-241 
 
 6611-5 
 
 95-75 
 
 300-807 
 
 7200-6 
 
 99-75 
 
 313-374 
 
 7814-8 
 
 91-875 
 
 288-634 
 
 6629-6 
 
 95-875 
 
 301-200 
 
 7219-4 
 
 99-875 
 
 313-767 
 
 7834-4 
 
 92 
 
 289-027 
 
 6647-6 
 
 96 
 
 301-593 
 
 7238-2 
 
 100 
 
 314-159 
 
 7854-0 
 
 92125 
 
 289-419 
 
 6665-7 
 
 96 125 
 
 301-986 
 
 7257-1 
 
 
 
 
 92-25 
 
 289-812 
 
 6683-8 
 
 96-25 
 
 302-378 
 
 7276-0 
 
 
 
 
 92-375 
 
 290-205 
 
 6701-9 
 
 96-375 
 
 302-771 
 
 7294-9 
 
 
 
 
 92-5 
 
 290-597 
 
 67-20-1 
 
 96-5 
 
 303-164 
 
 7313-8 
 
 
 
 
 92-625 
 
 290-990 
 
 6738-2 
 
 96-625 
 
 303-556 
 
 7332-8 
 
 
 
 
 92-75 
 
 291-383 
 
 6756-4 
 
 96-75 
 
 303-949 
 
 7351-8 
 
 
 
 
 92-875 
 
 291-775 
 
 6774-7 
 
 96-875 
 
 304-342 
 
 7370-8 
 
 
 
 
 93 
 
 292-168 
 
 6792-9 
 
 97 
 
 304-734 
 
 7389-8 
 
 
 
 
 93-125 
 
 •292-561 
 
 6811-2 
 
 97-125 
 
 305-127 
 
 7408-9 
 
 
 
 
 93-25 
 
 292-954 
 
 6829-5 
 
 97-25 
 
 305-5-20 
 
 7428-0 
 
 
 
 
 93-375 
 
 293-346 
 
 6847-8 
 
 97-375 
 
 305-913 
 
 7447-1 
 
 
 
 
 93-5 
 
 293-739 
 
 6866-1 
 
 97-5 
 
 306-305 
 
 7466-2 
 
 
 
 
 93 ■6-25 
 
 294-132 
 
 6884-5 
 
 97-625 
 
 306-698 
 
 7485-3 
 
 
 
 
 93-75 
 
 294-5-24 
 
 6902-9 
 
 97-75 
 
 307-091 
 
 7504-5 
 
 
 
 
 93-875 
 
 294-917 
 
 6921-3 
 
 97-875 
 
 307-483 
 
 75-23-7 
 
 
 
 
7i6 
 
 " Verbal " Notes and Sketches 
 
 Hyperbolic Logarithms. 
 
 No. of 
 
 
 No. of 
 
 
 No. of 
 
 
 No. of 
 
 1 
 
 Expansions 
 
 Hyp. log. 
 
 Expansions 
 
 Hyp. log. 
 
 Expansions 
 
 Hyp. log. 
 
 Expansions 
 
 Hyp. log. 
 
 R. 
 
 
 R. 
 
 
 R. 
 
 
 R. 
 
 
 11 
 
 0-0953 
 
 3-6 
 
 1 -2809 
 
 6-1 
 
 1-8083 
 
 8-6 
 
 2-1518 
 
 1-2 
 
 0-1823 
 
 3-7 
 
 1 -3083 
 
 6 
 
 2 
 
 
 8245 
 
 8-7 
 
 2-1633 
 
 1-3 
 
 0-2624 
 
 3-8 
 
 1 -3350 
 
 6 
 
 3 
 
 
 8405 
 
 8-8 
 
 2-1748 
 
 1-4 
 
 0-3365 
 
 3-9 
 
 1-3610 
 
 6 
 
 4 
 
 
 8563 
 
 8-9 
 
 2-1861 
 
 1-5 
 
 0-4055 
 
 4-0 
 
 1-3863 
 
 6 
 
 5 
 
 
 8718 
 
 9 
 
 2-1972 
 
 1-6 
 
 0-4700 
 
 41 
 
 1-4110 
 
 6 
 
 6 
 
 
 8871 
 
 9-1 
 
 2-2083 
 
 1-7 
 
 0-5306 
 
 4-2 
 
 1-4351 
 
 6 
 
 7 
 
 
 9021 
 
 9-2 
 
 2-2192 
 
 1-8 
 
 0-5878 
 
 4-3 
 
 1 -4586 
 
 6 
 
 8 
 
 
 9169 
 
 9-3 
 
 2-2300 
 
 1-9 
 
 0-6419 
 
 4-4 
 
 1-4816 
 
 6 
 
 9 
 
 
 9315 
 
 9-4 
 
 2-2407 
 
 2-0 
 
 0-6931 
 
 4-5 
 
 1 -5041 
 
 7 
 
 
 
 
 9459 
 
 9-5 
 
 2-2513 
 
 21 
 
 0-7419 
 
 4-6 
 
 1 -5261 
 
 7 
 
 1 
 
 
 9601 
 
 9-6 
 
 2-2618 
 
 2-2 
 
 0-7885 
 
 4-7 
 
 1 -5476 
 
 7 
 
 2 
 
 
 9741 
 
 9-7 
 
 2-2721 
 
 2-3 
 
 0-8329 
 
 4-8 
 
 I -5686 
 
 7 
 
 3 
 
 
 9879 
 
 9-8 
 
 2-2824 
 
 2-4 
 
 0-8755 
 
 4-9 
 
 1 -5896 
 
 7 
 
 4 
 
 2 
 
 0015 
 
 9-9 
 
 2-2925 
 
 2-5 
 
 0-9163 
 
 5-0 
 
 1 -6094 
 
 7 
 
 5 
 
 2 
 
 0149 
 
 10 
 
 2-3026 
 
 2-6 
 
 0-9555 
 
 5-1 
 
 1-6292 
 
 7 
 
 6 
 
 2 
 
 0281 
 
 10-5 
 
 2-3513 
 
 2-7 
 
 0-9933 
 
 5-2 
 
 1-6487 
 
 7 
 
 7 
 
 2 
 
 0412 
 
 11-0 
 
 2-3979 
 
 2-8 
 
 1-0296 
 
 5-3 
 
 1-6677 
 
 7 
 
 8 
 
 2 
 
 0541 
 
 11-5 
 
 2-4430 
 
 2-9 
 
 10647 
 
 5-4 
 
 1-6864 
 
 7 
 
 9 
 
 2 
 
 0669 
 
 120 
 
 2-4849 
 
 3 
 
 1-0986 
 
 5-5 
 
 1-7047 
 
 8 
 
 
 
 2 
 
 0794 
 
 12-5 
 
 2-5262 
 
 3-1 
 
 1-1314 
 
 5-6 
 
 1 -7228 
 
 8 
 
 1 
 
 2 
 
 0919 
 
 130 
 
 2-5649 
 
 3-2 
 
 1-1632 
 
 5-7 
 
 1-7405 
 
 8 
 
 2 
 
 2 
 
 1041 
 
 13-5 
 
 2-6027 
 
 3-3 
 
 1-1939 
 
 5-8 
 
 1 -7579 
 
 8 
 
 3 
 
 2 
 
 1163 
 
 140 
 
 2-6391 
 
 3-4 
 
 1 -2238 
 
 5-9 
 
 1 -7750 
 
 8 
 
 4 
 
 2 
 
 1282 
 
 150 
 
 2-7081 
 
 3-5 
 
 1-2528 
 
 6-0 
 
 1-7918 
 
 8-5 
 
 2-1401 
 
 16-0 
 
 2-7726 
 
 Printed at Thf, Darien Press Edinburgh. 
 
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