'.* 
 
 t 
 
 
Q 
 
X^^u-*^ t-^y 
 
 THE 
 
 WORKING ENGINEER'S 
 PRACTICAL GUIDE 
 
 TO THE 
 
 MANAGEMENT OF THE STEAM ENGINE 
 AND BOILER': 
 
 WITH RULES AND INSTRUCTIONS FOR 
 
 VALVE SETTING: 
 
 SO AS TO SECURE A FULL DEVELOPMENT OE THE MOTIVE POWEB. 
 ILLUSTRATED BY DIAGRAMS AND ENffkAVlMS. '''*,;' 
 
 BY JOSEPH HOPKINSON, 
 
 i 
 
 Of the Firry^ (tfjjJ- Hopkinson Sf Co., Engineers, Huddersfield, 
 
 LONDON: 
 
 JOHN WEALE, HIGH HOLBORN ; AND SIMPKIN, MARSHALL, AND CO. 
 MANCHESTER t THOMSON AND SON ; AND A. HEY WOOD. HUDDERSFIELD : B. BROWN. 
 
 1866. 
 
PRINTED BY B. BROWN, HUDDERSFIELD. 
 
PREFACE. 
 
 WITH confidence the Author submits the present work, "THE WORKING 
 ENGINEER'S PRACTICAL GUIDE," to the judgment of those whose duty it is to 
 superintend the working of the Steam Engine and Boiler, in their many and 
 varied forms and applications. The many encomiums the Author has received 
 from parties who have benefited from following the instructions and advice 
 contained in his larger work, "THE WORKING OF THE STEAM ENGINE EXPLAINED 
 BY THE USE OF THE INDICATOR," (four large Editions of which have been 
 published, and rapidly disposed of,) and the very general desire he has heard 
 expressed that portions of the matter composing that work should be published 
 in a form and at a price more accessible to the working Engineer, has induced 
 him to prepare the work now presented, in the confident belief that it will be 
 found to be of practical advantage to those for whose information and use it has 
 been designed. 
 
 The aim of the Author, in all he has published, has been, by means of homely 
 language, accompanied with familiar and practical illustration, to instruct those 
 who are entrusted with the care and management of Steam Engines, so that they 
 may ascertain with certainty whether they are deriving the greatest amount of 
 practical advantage from the several quantities of impulsive power they may 
 generate and apply. Interspersed with these instructions he has given hints and 
 examples, intended to show how practical improvements in the working of most 
 Steam Engines may be effected at little cost, to the great saving of fuel, and the 
 steady application of the motive power all these being points of manifest 
 importance to the proprietors of Steam Engines, and of advantage to the practical 
 Engineer. The conclusions recorded in this work have resulted from observation 
 and study, not in the closet, but in company with the Steam Engine, in its various 
 stages and alterations : and although the mere theorist, or the scientific literary 
 writer, may object to the plain and simple manner in which the different topics 
 descanted on are treated, the Author is assured, from the difficulties which in the 
 early period of his own experience he himself had to contend with and overcome, 
 that his plan of procedure is the best that he could possibly have adopted for the 
 accomplishment of his main object in undertaking the work the instruction of 
 the practical working Engineer. 
 
 The chapters of the present work, on the management of the Boiler and 
 Engine, will, the Author flatters himself, be found to contain instructions and 
 
hints, calculated if acted on and carried out to be of great advantage to 
 working Engineers, as well as to the proprietors of Steam Engines, by enabling 
 the former to pursue their avocations so as to produce something like certainty of 
 results, and to know, in a great measure, the cause of any derangement in the 
 working of either the Boiler or Engine that may occur. 
 
 The section of the work devoted to the question of the Expansion of Steam, 
 with the examples adduced, shows how this is to be effected in the most available 
 manner with the best practical results. The Author knows of nothing else 
 hitherto published which imparts the information on this important subject he 
 has endeavoured to convey. Yet this is one of the real questions of the the day 
 the main direction in which further improvements of the Steam Engine are to 
 be effected. Economy in the working of the Steam Engine is known to be in 
 the application of high pressures. The higher within the limits of safety we 
 can get, the more economical. To obtain the whole benefit of high steam, we 
 must apply the principles of Expansion, beginning with the highest pressure of 
 steam we have, and parting with it at the lowest possible pressure. How this 
 principle is to be applied with practical advantage, the Author has here 
 endeavoured to indicate. 
 
 The Tables appended to the work will also, it is believed, be found to be of 
 service to the practical Engineer, aiding him in his calculations for various 
 matters connected with the Steam Engine and its working. In those Tables, and 
 indeed, throughout the work, decimals have been, to a great extent, dispensed 
 with, and also fractional parts, with the exception of those expressed by the 
 common signs |, , f , the calculations when so reduced and expressed, being 
 near enough for all practical purposes, and more intelligible to a large portion of 
 the class for whom the work is designed. In fact, throughout the treatise, the 
 aim of the Author has been to express himself in simple phraseology ; and 
 though his production may not possess the charm of literary embellishment, he 
 trusts that it may be found to possess at least the merit of perspicuity in the 
 treatment of a dry subject, and to be of practical utility. In short, he trusts that 
 it will be found to be what he has endeavoured to make it, a " PRACTICAL GUIDE 
 TO THE WORKING ENGINEER." 
 
 BRITANNIA WORKS, 
 
 Huddersfield, January, 1866. 
 
CONTENTS. 
 
 CHAPTER I. ON THE MANAGEMENT OF THE BOILER AND 
 STEAM ENGINE. 
 
 Duties of an Engineer, 1 
 
 General Management of the Boiler, 1 
 
 Boilers properly stayed, 1 
 
 Feed Valves, Self Feeders, Gauge Taps, 
 Stop Valves, &c., 2 
 
 The Safety Valve should let off the steam, 
 should the water become deficient, 2 
 
 Not Safety Valves, 2 
 
 A proper Safety Valve, 3 
 
 Length of Safety Valve Lever, 3 
 
 Boiler Fittings taken to pieces, 3 
 
 Boiler becomes Over-heated, 3 
 
 Lead Plugs fusible metal, 3 
 
 Open Column Pipes, 3 
 
 A proper Safety Valve, 4 
 
 Boiler well blown out, 4 
 
 Feed Water for the Boiler, 4 
 
 Where there are two or more Boilers, \ 
 &c., 5 
 
 Junction Steam Valves, 5 
 
 Pipes fixed to the Boiler, 6 
 
 Boilers wear out faster when not in use, 5 
 
 Extra Boiler room, 5 
 
 Setting Boilers, 6 
 
 Be your own Inspector, 6 
 
 Steam Gauges, 6 
 
 Certain Sign of Slovenliness, 6 
 
 Feeding Steam Boilers with Water, 6 
 
 Expansion and Contraction of Boilers, 6 
 
 Getting up of Steam, 6 
 
 Internal Flues expand, 8 
 
 The two Forces, Expansion and Con- 
 traction, 8 
 
 Boiler Plates overlap each other, 8 
 
 Thick and thin Plates of Boilers, 9 
 
 Unequal Pressure in Boilers, 9 
 
 Oval Flues without Stays, 9 
 
 Flues crushing .upwards, 10 
 
 Boiler Explosion Castle Mills, Sheffield, 10 
 
 Boiler stronger when hot, 10 
 
 Diagram No. 1, Exploded Boiler Flue, 11 
 
 Maximum Strength of Iron, 12, 
 
 Form, Strength, and Staying of Boilers, 1 2 
 
 Double Fire-box or Flue Boiler, 12 
 
 Danger from Inner Tubes or Flues, 12 
 
 Pressure applied internally the best, 1 3 
 
 Double Fire-box Boiler by 0. Evans, 13 
 
 Boiler Explosions in America, 13 
 
 Pressure not uniform on Flues, 14 
 
 Diagram No. 2, Cross Section of Boiler, 14 
 
 Flat Ends of Boilers, 15 
 
 Boiler Stays, 1 5 
 
 Diagram No. 3, Boiler Stays, 16 
 
 Gusset Stays, as applied to Boilers, 17 
 
 Stop Valve placed between the Boiler and 
 Safety Valve, 17 
 
 Diagram No. 4, Stop Valve, 18 
 
 Inquest Aspley Boiler Explosion Fair- 
 bairn's Evidence, 1 8 
 
 Verdict of the Jury at Aspley, 19 
 
 Strength of Wrought-iron Bars and 
 Plates, 20 
 
 Staffordshire and Yorkshire Boiler Plates, 
 20 
 
 Punching and bending Boiler Plates, 
 cold, 20 
 
 Heating Boiler Plates, 21 
 
 Boring Boiler Plates instead of punching 
 them, 21 
 
 Strength of Steam Boilers, 21 
 
 Rule for calculating the strength of Cylin- 
 ders on Boilers, as generally applied, 22 
 
 Testing Boilers, 23 
 
 Cleansing Boilers, 23 
 
 Diagrams Nos. 5, 6, and 7, 24-25 
 
 Various modes of Cleansing Boilers, 26 
 
 The Safety Valve, 26 
 
 The Inventor of the Safety Valve, 27 
 
 Diagram No. 8, Safety Valve, 28 
 
 Hopkinson's Patent Compound Safety 
 Valve, 30 
 
 Description and Cut of Valve, 31 
 
 Rule to ascertain at what pressure a Safety 
 Valve is weighted, 32 
 
 Plan and Dimensions of a Nominal 40- 
 Horse power Double-flue Fire-box 
 Boiler, 33 
 
 Diagram No. 9, Improved Steam Boiler, 34 
 
 Longitudinal Section of a Nominal 40- 
 Horse Steam Boiler, with Stay Pipes, 35 
 
 Diagram No. 10, of Steam Boiler, 36 
 
 Diagram No. 11, Section of Flue of a 
 Steam Boiler, 37 
 
 Table showing the Increase and Decrease 
 of the Strength of Iron at various tem- 
 peratures from tests by the Committee of 
 the Franklin Institute, 38-9 
 
CONTENTS. 
 
 CHAPTER II. THE FURNACE AND ITS ADJUNCTS. 
 
 Grate surface to the absorbing surface of 
 
 the Boiler, 40 
 To prevent the formation of a great portion 
 
 of the Smoke, 40 
 Necessity of Stoking the Furnace when the 
 
 Steam is up, 40 
 Diagram No. 12, of a Double Fire-box 
 
 Boiler, 41 
 Evaporative Power of Coal according to 
 
 Draught, 42 
 Newcastle-upon-Tyne experiments on the 
 
 Evaporation of Coal and the Prevention 
 
 of Smoke, 42 
 A dirty Furnace creating Smoke, 42 
 
 A dirty Ashpit a sure sign of bad manage- 
 ment, 42 
 
 Diagram No. 13, Dead-plate of Furnace, 43 
 Additional air to the Furnace, 43 
 The Author's experience with Smoke 
 
 Prevention Apparatus, 43 
 Furnace Doors, 44 
 Diagram No. 14, Grate Bar, 44 
 Form of Furnace Bridges, 44 
 Openings between the Grate Bars, 44 
 Careful Firing, clean Grates, c., 45 
 Table of the comparative Evaporative Power 
 
 of different kinds of Coal, 45 
 Lancashire and Yorkshire Coal, 45 
 
 CHAPTER III THE ENGINE. 
 
 Indicate the Engine every day, 46 
 Rule for the Horse-power example, 46 
 Diagram No. 15, clearing pump rose, 47 
 Unsteady Working of the Engine, 48 
 Crank Pin and other bearings, 48 
 Recipe for cooling Necks, &c., 49 
 Prevention is better than cure, 49 
 Proper attention to Packing, &c., 49 
 Pipes and Cylinders clothed, 49 
 Vacuum Gauge and Vacuum, 49 
 What is the Vacuum of a Steam 
 
 Engine ? 50 
 
 Steam an invisible fluid, 50 
 The literal meaning of the term " vacuum " 
 
 50 
 
 The first Steam Engine, 51 
 Watts' first improvements, 51 
 Steam from an open vessel, 51 
 Pressure of the Atmosphere, 51 
 Atmosphere on the Safety Valve, 52 
 Engines vary in speed according to the 
 
 Atmosphere, 52 
 Vacuum not power, 52 
 The term " suction " 52 
 Condensing Engines and Non-condensing 
 
 Engines, 53 
 
 Engine not heavily loaded, 53 
 Expansion of Steam, 55 
 Discovery is due to Hornblower, 55 
 Hornblower's Specification, 56 
 Expansion of Steam strictly mechanical, 56 
 It is a saving, and not a gain, 56 
 The main-spring of a watch actuates its 
 
 machinery, 57 
 
 Advantages arising from Expansion, 57 
 Working Steam expansively in one 
 
 Cylinder, 57 
 The great benefit derived from Expansion 
 
 in one Cylinder, 58 
 Resistance of the Atmosphere, 58 
 
 Example when calculating the pressure of 
 
 Expansion of Steam on the Piston, 58 
 
 Diagram No. 16, representing the 
 
 Cylinder of a Steam Engine, 59 
 Expansion of Steam in the Cylinder, 59 
 Diagram No. 17, of Expansion, with 
 
 Examples. 60 
 
 Table showing the quantity of Steam used 
 when worked without Expansion, and 
 the power obtained ; also the quantity 
 when worked expansively, 61 
 Steam passing through a number of Cylin- 
 ders, 61 
 
 Table showing the average Pressure of 
 Steam upon the Piston throughout the 
 stroke, when cut off in the cylinder from 
 one-eighth to one-twelfth the stroke, vary- 
 ing from lOfos to 150ft>s pressure, 62-3 
 Examples of the foregoing Table, 64 
 Nominal and indicated horse-power of 
 
 Steam Engines, 65 
 
 The term " Nominal Horse-power," 65 
 Example Nominal Horse-power, 66 
 Real power ascertained by the Indicator, 66 
 Non-condensing Engines Nominal Horse- 
 power, 66 
 
 Examples of the power of Non-condensing 
 Engines with various pressures of Steam, 
 66 
 To find the power of a Steam Engine on 
 
 the basis of Watts' definition, 67 
 Rule to find the power of a Steam Engine 
 
 by means of the Indicator, 67 
 Diagram No. 18, Friction Diagram, 68 
 Explanations of Figuring of Diagrams, 69 
 Rule to ascertain the power required to 
 drive any quantity of machinery ; or 
 the power the Engine is exerting, 69 
 Diagram No. 19, from a Condensing 
 Engine, 70 
 
CONTENTS. 
 
 Example of the mode adopted to calculate 
 
 Horse- power, 71 
 Example and Rule to ascertain the quantity 
 
 of Coal consumed per hour per Horse- 
 power, 72 
 
 Explanation of a Diagram, 72 
 Diagram No. 20, example, 73 
 General mode of measuring Diagrams, 74 
 Construction and Action of Valves, 74 
 Common Three-port Slide Valve, 74 
 Figure No. 21, Cylinder and Slide Valve, 
 
 75 
 
 Explanation of a Three-port Valve, 76 ^ 
 Diagram No. 22, from a Non-condensing 
 
 Engine, 77 
 
 Lap, or cover, of Three-port Slide Valve, 78 
 Figure No. 23, Cylinder and Slide Valve, 
 
 with lap, 79 
 Balancing the working parts of an 
 
 Engine, 81 
 
 The D Slide Valve, 81 
 Diagram No. 24, from a Non-condensing 
 
 Engine with lap on Valve and V on the 
 
 edge, 82 
 
 Explanation of D Valves, 83 
 Figure No. 25, Section of a Steam Engine 
 
 Cylinder, with D Slide Valves, Rock 
 
 Shaft, and Eccentric, 84 
 Figure No. 26, an Enlarged Section of 
 
 Steam Engine Cylinder with D 
 
 Valves, 85 
 The Cornish, or Double-beat Drop Valve, 
 
 87 
 Description of Figures 27 and 28, Drop 
 
 Valves, 87 
 Figure 27, Section of Steam Engine 
 
 Cylinder, Side-pipes with Cornish Drop 
 
 Valves, 88 
 Figure 28, Side view of Cylinder and 
 
 Side-pipes, with Cornish Valves and 
 
 Revolving Tappets, 89 
 Improved Slide Valve, with Double 
 
 Exhaust, 91 
 
 Figure No. 29, Improved Slide Valve, 91 
 Figure No. 30, Improved Slide Valve, 92 
 Opening of the Valve to admit the Steam 
 
 to the Piston and the Condenser, 94 
 On the Setting of Steam Engine Valves, 94 
 Diagram No. 31, taken from the top of a 
 
 Low-pressure Cylinder with Q Valves 95 
 Dingram No. 32, taken from the top of the 
 
 Cylinder of a Condensing Engine, 96 
 Cushioning the Steam, 96 
 Tappet Valve, to cut off the Steam and 
 
 open the Exhaust at any required 
 
 distance, 96 
 Diagram No. 33, from a Condensing 
 
 Engine, 97 
 Explanation of D Slide Valve of Diagram 
 
 No. 33, 98 
 Two Engines coupled, working at right 
 
 angles, 98 
 Diagram No. 34, another example of D 
 
 Valve cutting off the Steam, 99 
 
 Proportions of a Pair of 28 nominal horse- 
 power Condensing Beam Engines, show- 
 ing the mode in which the Valves are 
 
 set, 101 
 Diagram No. 35, from a pair of Beam 
 
 Engines 28 nominal horse-power, 102 
 Table showing the amount of Lap required 
 
 for Slide Valves, when the Steam is to 
 
 be worked expansively, 103 
 Explanation of Diagrams, 103 
 Diagram No. 36, taken from the top of the 
 
 Cylinder of a Condensing Engine, 104 
 To ascertain the power required for any 
 
 particular machine, 1 04 
 Large Steam- ways, 105 
 Contracted Steam- ways, 105 
 Diagram No. 37, from the bottom of the 
 
 Cylinder, 106 
 
 Comparison of various Engines, 106 
 Diagram No. 38, from the top of a Cylinder 
 
 with Tappet Valves, 108 
 Diagram No. 39, from the same Engine as 
 
 No. 38 Diagram, 109 
 Diagram No, 40, Derangement of Valves, 
 
 110 
 
 Difference of Indicators, 111 
 Extreme pressure being imparted to the 
 
 Crank at " plumb centre," 1 12 
 Valve-setting with too much lead, 112 
 Small Indicators, 1 12 
 Diagram No. 41, from the same Engine as 
 
 No. 40 Diagram, 113 
 Great changes have taken place amongst 
 
 Engineers, in the use of the Indicator, 
 
 114 
 Diagram No. 42, from the same Engine as 
 
 No. 41 Diagram, 115 
 Benefit of a better knowledge of this 
 
 important portion of an Engineer's 
 
 duty, 116 
 Equilibrium Valves, with inside Hoops, 
 
 116 
 Last three Diagrams show the advantage 
 
 of good management, 116 
 Boiler Associations, Insurance Societies, 
 
 &c., 117 
 Inspectors 1 services being dispensed with, 
 
 1851, 415 horse-power ; in 1860, the same 
 Engines gave 670 horse-power, and the 
 quantity of fuel required, .1 17 
 Had these Engines been compounded, 117 
 Diagram No. 43, another example of 
 
 improper Valve-setting, 119 
 Pressure of Steam upon the Piston at 
 
 " plumb centre," 119 
 Foundation of Engine gives way, 1 1 9 
 j Breakdowns from improper Valve-setting, 
 
 119 
 
 V-shaped Valve-edge, Figure 44, 120 
 Diagram No. 45, from same Engine as 
 
 Diagram No. 43, 121 
 Messrs. Cook & Son's Letter, 122 
 Necessity of Engine being indicated, 122 
 
CONTENTS. 
 
 Were Engineers taught the principles of 
 Indicating, 122 
 
 " Report "-maker has been elevated into 
 the position of " Official Dictator," 123 
 
 Mr. Gledhill's Letter on the Alteration of 
 
 an High-pressure Engine, 123 
 Too little lead of the Exhaust, 124 
 Direct-acting Horizontal Condensing Steam 
 Engine, 125 
 
 CHAPTER IV. THE STEAM ENGINE INDICATOR. 
 
 History of the Instrument, 126 
 Mr. Southern's Improvements, 126 
 Hopkinsons 1 Improvements, 127 
 M'Naught and Richards' Indicator, 127 
 Indicator manfactured by Messrs. J. Hop- 
 
 kinson, much larger, 127 
 The American Indicator, 128 
 Advantages of the Steam Engine Indi- 
 cator, 128 
 
 Description of the Steam Engine Indicator as 
 manufactured by Messrs. J. Hopkinson, 
 129 
 
 Plate No. 46, Steam Engine Indicator, 1 30 
 
 How to affix and use the Indicator, 133 
 
 Explanation of a Diagram, 134 
 
 Office Engineering, 136 
 
 Mr. E. Ingham's Letter on Indicators, 136 
 
 Comparing Diagrams, 137 
 
 APPENDIX containing Tables and other information calculated 
 
 to be of service to Engineers and others entrusted with the 
 
 Management of the Steam Engine and Boiler. 
 
 Table : Expansion of Air by Heat, iii. 
 
 Imperial Standard Measures, iv. 
 
 Rule to ascertain the Weight of Cast-iron 
 
 Balls of any diameter, vi. 
 Boiling point of Water under different 
 
 pressures of the Atmosphere, vi. 
 Geometry, vi. 
 Table of Weights, vii. 
 Weight of Cast-iron Balls from 3 to 13 
 
 inches diameter, useful for Safety 
 
 Valves, &c., vii. 
 Weight of Cast-iron Plates per superficial 
 
 foot, as per thickness, vii. 
 Weight of Boiler-plates 1 foot square, 
 
 and from one-sixteenth of an Inch, viii. 
 Weight of Square Bar-iron from \ inch to 
 
 6 inches square, 1 foot long, viii. 
 Weight of Round Bar Iron, from ^ inch to 
 
 6 inches diameter, 1 foot long, ix. 
 Weight of Sheet Lead per Superficial Foot, 
 
 as per thickness, ix. 
 Weight of Cast-iron Pipes, I foot in 
 
 length, from | inch thick, and from 3 to 
 
 24 inches diameter, x. 
 Weight of Materials, xi. 
 Table showing the difference in the Strength 
 
 of Metals, xii. 
 Heat-conducting powers of different Metals 
 
 xii. 
 
 Table showing the temperature Metals melt 
 at, xii. 
 
 Table of Areas for Safety Valve Cylinders, 
 Air-pumps, &c., from one-sixteenth of an 
 Inch to 1 00 inches diameter, xiii. 
 
 Table showing the Pressure of Steam from 
 2^ft>s up to 60Ibs, and the height of a 
 column of Mercury, and the number of 
 Feet and Inches of Water in a column 
 at the different pressures, xxv. 
 
 Steam produced from impure water is not 
 of equal density to Steam from pure 
 water, xxv. 
 
 Table showing the Temperature of Steam 
 at different pressures, from lft> to 240ft>s 
 per square inch, and the quantity of 
 Steam produced from a cubic inch of 
 Water, according to pressure, xxvi. 
 
 Advantage of generating and using High- 
 pressure Steam, xxvii. 
 
 Table showing the weight of Water in 
 Pipes of various diameters, I foot in 
 length, xxviii. 
 
 Durable Cement for Steam and Water 
 Joints, Gas Retorts, &c. xxix. 
 
 Useful Cement for Reservoirs, Cisterns, 
 Walls, Water Courses, &c., xxix. 
 
THE WORKING 
 
 PRACTICAL 
 
 CHAPTER I. 
 
 ON THE MANAGEMENT OF THE BOILER AND 
 STEAM ENGINE. 
 
 THE duties of an Engineer, entrusted with the managenent of a Steam 
 Engine and Boiler, are of more importance than at first sight would 
 appear. He ought to be attentive, and conversant with all the details 
 of the constructions placed in his charge, otherwise he will be liable 
 to make mistakes, and may unwittingly cause much damage. 
 
 Boilers require careful and constant attention : but under the control 
 of judicious managers, with proper fittings, they are perfectly safe, when 
 properly constructed. But when their construction and management 
 fall into the hands of incapacity and ignorance, or where reckless folly 
 and hardihood have their full fling, death and destruction almost 
 inevitably follow. 
 
 As this work is intended to be of practical service to the "Working 
 Engineer, we shall, in homely style, and with familiar illustrations and 
 examples, endeavour to make plain and understandable the several duties 
 connected with his avocation. And first, of 
 
 THE GENERAL MANAGEMENT OF THE BOILER. 
 
 The Boiler and Furnace require the especial attention of the Engineer, 
 these being the places where the power he has to apply and regulate is 
 first generated, and from which the most dangerous consequences may 
 arise, either from neglect or ignorance. The following short rules for 
 good management ought to be deeply engraven on the memory of every 
 one entrusted with the care of Steam Engine Boilers, viz : 
 
 I. All dirt and lumber ought to be kept from the top of the Boiler, 
 and from every part of the Boiler-house, and no person admitted into 
 the latter, except on business. 
 
 II. It should be ascertained that the Boiler is properly stayed, where 
 stays are necessary, particularly if fixed with angle iron ; and the cotters 
 
 2 
 
(if any) kept up, and repaired as they are worn down ; and it should also 
 be seen that all fixings attached to the Boiler are well riveted on, and 
 good joints made with proper cement, free from injurious compounds 
 detrimental .to tjie- metal of the Boiler. All leakages ought to be 
 <pxeyented,> or stopped as soon as they are discovered, or they will soon 
 rlestroy the-B^ilei;. /-The 'flues and the surfaces exposed to heat should 
 t^kept'' clean; Soot and dirt are non-conductors, and cause a loss of 
 fuel, besides decreasing the heat-conducting power of the Boiler. 
 
 III. See that the feed- valve is in good working order ; see also that 
 the float (if any) and glass-gauge are well attended to. If a self- 
 regulating feeding apparatus is used, it should be closely watched, and 
 on no account be implicitly trusted. Self-feeders to Boilers are liable to 
 get out of order, from friction in stuffing-boxes from dirt, and from other 
 similar causes. Ascertain that the pipes and taps of the gauge are not 
 made up with dirt or scale. If gauge taps alone are used, do not rely 
 upon them to test the height of the water in the Boiler. If the water be 
 below the tap, the moment the latter is opened to test the height, the 
 water in the Boiler primes, and rushes to the tap, and shows water when 
 the Boiler is actually short particularly where great pressure is used. 
 Gauge taps have been the cause of many Boiler explosions, from having 
 deceived the attendant. Where a float is used, see that the float-wire is 
 not strained, or worn to a shoulder, but kept free in the packing ; and 
 when worn smaller at the foot where the wire passes through the Boiler, 
 see that it be renewed with a small wire the smaller the better. 
 Where steam is at a pressure above lOIbs to the square inch, the common 
 float is of little use. In most cases, with high steam they are positively 
 dangerous, and should not be trusted. Stop-valves, or other spindle- 
 valves, should be constructed so that the thread on the spindle is outside, 
 and may be seen at any time. This may be effected by means of a 
 bridge-casting attached to the part through which the spindle-thread 
 passes. 
 
 IV. Be provided with means to prevent the steam getting to a 
 greater pressure than fixed upon. Should the water from any cause 
 become deficient, the safety-valve should let off the steam and stop the 
 working, independent of any control, until water is again supplied in the 
 required quantity : thus saving the Boiler from explosion. Often ascer- 
 tain that the safety-valve is properly adjusted. Be particular that the 
 spindle or guides (if any) have sufficient room to work, and also to 
 prevent the parts adhering. In no case have a stuffing-box or spring to 
 a safety-valve. Safety-valves, as commonly made and understood, are 
 valves simply for the letting off of steam under certain calculated 
 circumstances of pressure. Thus constructed, they are, in fact, only 
 
steam-valves, and not safety-valves. A properly constructed safety- 
 valve will not only liberate the steam when the pressure is too high from 
 over-firing, but also when the water in the Boiler from any cause becomes 
 too low for safe working. A proper safety-valve is also weighted in 
 such a manner that when set at the pressure beyond which it is 
 determined the steam shall not rise, that weight cannot be changed or 
 tampered with whilst the Boiler is at work. 
 
 V. Let the length of the safety-valve lever be as short as possible, to 
 prevent the extreme pressure you are working at from being increased 
 with the same weight. When the lever of a commonly constructed 
 safety-valve is too long, the valve is easily tampered with. Indeed, the 
 working pressure may, under such circumstances, be easily increased to 
 or beyond the point of danger, by the weight being accidentally removed 
 on the long lever. Let the joints of the fulcrum of the lever be of brass 
 or some other metal that will not corrode, or cause the parts to oxydize 
 and become fast. The fittings on the Boiler should be taken to pieces at 
 least once a year, cleaned, refitted, and adjusted. This will prevent the 
 parts becoming magnetised, and adhering to each other. 
 
 VI. Whenever from any cause, the Boiler-plates become over-heated, 
 open the damper and furnace-doors to the full, that the cold air may 
 cool the Boiler. Closing the damper increases the heat in the flues, and 
 by that means the danger is increased. Lead plugs or fusible metal 
 inserted in the flues, do not melt at the temperature required, after being 
 in use a short time ; therefore place no reliance upon such contrivances. 
 They only tend to lull the proprietor of the Steam Engine and the 
 Engineer into a fancied security. Above all, do not admit water into 
 the Boiler or relieve the pressure suddenly : as either will cause a violent 
 agitation or foaming of the water and this, washing over the heated 
 plates, will generate more steam than the safety-valve can discharge 
 creating most imminent danger of an explosion. Under extreme circum- 
 stances of this nature, the water sent into the Boiler, or that brought into 
 contact with the highly heated surface, will flash into high steam, just as 
 if a quantity of gunpowder had been ignited within the Boiler, tearing 
 everything asunder. The starting of the Engine is quite sufficient to 
 produce a violent agitation of the water, by the pressure being relieved 
 when the Boiler is overcharged with heat, and disastrous consequences 
 may be the result. Above all, do not depend on open column-pipes 
 inserted in the Boiler, as a means of safety from explosions ; for though 
 they will relieve at times from over-pressure to the great danger in such 
 cases of running the Boiler empty they are positively dangerous from 
 another cause. It has been ascertained, by experiment, that though the 
 water in the Boiler may be reduced so low as to lay some of the plates 
 
bare to the action of the fire, the water from the pipe will not descend 
 below a certain point, but will hang from the bottom of the pipe in the 
 form of a cone a striking illustration of what is known as the cohesion 
 of adhesion. Should this cone, from any cause, agitation or otherwise, 
 become detached from the end of the pipe, and be dispersed over the 
 heated plates, the consequences above pointed out are almost inevitable. 
 In fact, these open column-pipes are no safeguard whatever against a 
 Boiler becoming low in water, or, indeed, practically empty. Where a 
 proper safety-valve has been applied, these open stand-pipes, fusible 
 plugs, and also water-gauging taps are wholly unnecessary as, with the 
 former appliance it is impossible for the Boiler to become short of water 
 and have pressure within it at the same time : the prevention of danger 
 from this cause being, under the circumstances spoken of, sure and 
 certain. 
 
 VII. See that the dirt in the Boiler is well blown out. Some 
 descriptions of water will require the Boiler cleansing every three hours, 
 others not so often, according to the quality of the water. If this point 
 be attended to, the Boiler will wear much longer, and seldom require 
 opening ; the consumption of fuel will also be much less. In Marine 
 Boilers, the blowing out at stated intervals from the surface and the 
 bottom, prevents the deposition of salt and lime, and is the only thing 
 required to keep the Boilers clean. 
 
 VIII. Have the feed water for the Boiler as hot as possible, and sent 
 into the Boiler near the surface of the water inside. The cold water will 
 descend ; but before arriving at the bottom it will have become heated, 
 thus tending to keep the Boiler at an even temperature. If the water 
 injected be low in temperature, it should be well distributed in the mass 
 of water already in the Boiler, and not allowed to impinge on any portion 
 of the metal of the Boiler or that portion of the Boiler where the cold 
 water thus comes into contact will be liable to crack and rend, from the 
 continual action of contraction and expansion which such an arrangement 
 inevitably causes. When the water is sent into the Boiler near the 
 bottom, it does not rise till it has become heated ; and this mode of 
 feeding therefore tends to keep the Boiler bottom cooler than the other 
 portions an evil which ought to be avoided. The Cornish, Double 
 Fire-box, and Tubular Boilers are more subject to this evil of unequal 
 expansion and contraction than most others. The Engineer should there- 
 fore have the feed-pipes raised in the Boiler, when they are inserted in or 
 near the bottom, otherwise the Boiler may break in the centre, and cause 
 much loss or damage by the parts of the Boiler separating. With round 
 Boilers, with the fire under the bottom, and particularly where they are 
 hard-fired, some mode should be devised to cause a continual circulation 
 
of the water near to the bottom of the Boiler : otherwise the steam 
 generated at that place will partially displace the water, and thus allow 
 the plates to become overheated and weakened. 
 
 IX. When there are two or more Boilers, with feed-pipes connected 
 together, without a self-acting stop-valve between each, shut off the 
 feed- valve to each Boiler during the night, or whenever it is not working ; 
 the water being liable otherwise to empty itself from one Boiler into 
 another as the pressure in the Boilers varies, leaving one of the Boilers 
 nearly empty ; more particularly where there are Boilers working at 
 different pressures. A self-acting stop-valve is in the last case absolutely 
 necessary. But where Hopkinson's Patent Compound Safety Valve is 
 on the Boiler, this will be prevented. Should the water lower, the valve 
 will let off the steam, and the water will then be equalised, thus being 
 what its name imports a Safety- Valve under all circumstances. 
 
 X. Where junction steam-valves are used, or a valve placed between 
 the Boilers and the main steam-pipe, see that the valve-spindle is one 
 without a weight or screw, and take every precaution to prevent the 
 valve from being weighted down when the steam is up. Sometimes the 
 safety-valve is on the steam-pipe ; in that case junction-valves are 
 dangerous, where they can be fastened down. In the stop-valve for the 
 Boiler, the spindle should be constructed with a screw-thread, and be 
 outside. The nut for the screw can be fastened in the centre of a bridge 
 cast to the valve-box lid. Where the screws are inside, difficulties often 
 arise. In all pipes fixed to the Boiler, have them so arranged that the 
 condensed steam will drain back to the Boiler, and not go through the 
 Engine ; a great saving will be thereby produced the hot water 
 supplying the place of cold, according to the amount condensed. The 
 arrangement will also, in many cases, prevent breaks-down, from the 
 water of condensation getting into the cylinder. 
 
 XL Where there are two or more Boilers, do not keep any one out 
 of action longer than is absolutely necessary for cleansing or repairs. A 
 Boiler wears out faster when not in use, by oxydizing and corroding, 
 than if moderately worked. It will be found more economical to work 
 with " extra Boiler room," than to have one or more " standing." It 
 will also tend to prevent " priming." The furnaces will be easier stoked 
 by working a thick fire, allowing the heat to accumulate, thereby main- 
 taining a high temperature in the furnace with slow combustion. The 
 furnace doors not having to be so often opened as with thin-firing, 
 the temperature in the flues will be more regular, the cooling down 
 whilst firing much less, and the contraction and expansion also corres- 
 pondingly less. By this mode of firing, furnaces will last much longer, 
 and in the case of a Fire-box Boiler, the plates in contact with the hot 
 
fuel will generate steam much quicker, with less labour and attention, 
 there being an extra amount of absorbing surface in contact with the 
 fuel, with the same area of grate. 
 
 XII. Where the Boilers are set in brickwork, do not use lime in 
 contact with the iron. In setting the bricks, use fire-clay, or common 
 clay. Lime with damp, quickly eats away the iron ; therefore do not 
 use it at all about the metal of a Boiler. Where a " midfeather" is placed 
 under a Boiler, it ought to be of cast-iron, in the form of a A, for the 
 Boiler to rest upon. Should any leakage take place, there will be little 
 surface for the water to lodge on. Whenever the flues are cleaned, 
 examine the exterior and interior of the Boiler thoroughly, and do this 
 yourself. Do this also whenever the Boiler is let off. By keeping the 
 surface of the Boiler and the flues clean, the draught will be improved, 
 more steam will be generated in the same time, fuel will be saved, and 
 the Boiler will wear longer. Be your own Inspector, and become what 
 you ought to be a practical Engineer. 
 
 XIII. Have a good steam-gauge to the Boiler, one that cannot be 
 tampered with, and one not liable to get out of order. Do not place a 
 tap between the Boiler and the gauge : for this, by being opened and 
 closed, will interfere with the correctness of the indications. Fix the 
 steam-gauge in a situation where the frost or cold cannot affect it. A 
 column of mercury is the truest indicator, when used without a floating 
 stick, or " steam peg." " Pegs " can be made longer or shorter, to suit 
 the convenience of the Fireman. Avoid all enclosed metallic springs, or 
 India-rubber washers, to indicate pressure. Do not depend upon them ; 
 for the springs corrode, and lose their elasticity, while India-rubber 
 washers become indurated and the indications of the gauge will vary 
 accordingly. There are various forms and makes of steam gauges ; but 
 many of them are nothing better than philosophical toys. 
 
 [In concluding this section, we would impress on all persons having 
 charge of Steam Boilers, that there is no more certain sign of slovenliness 
 than a dirty water-gauge or steam-gauge on the front of a Boiler, or the 
 furnace-door covered with slime or dirt. Wherever these are met with, 
 tliere is little hope of good management being found elsewhere under the 
 same control.] 
 
 FEEDING STEAM BOILERS WITH WATER. 
 
 BETWIXT the Boiler and the Engine-pump have a self-acting stop- 
 valve, independently of the pump, to prevent the water from returning 
 when once it has passed the valve. It should be so placed that the 
 
water forced from the pump will lift the valve from its seat, and allow 
 the water to pass into the Boiler but when the pump ceases action, 
 the pressure in the Boiler should close the valve, and thereby retain the 
 water which the Boiler has received. 
 
 Betwixt the self-acting stop-valve and the pump have a tap, branching 
 from the side of the pipe. When this tap is closed, the whole of the 
 water will pass into the Boiler ; but in case the water from the pump is 
 more than is required to supply the Boiler, the tap can be partly opened, 
 so that one portion of the water forced by the pump may be sent through 
 the small opening of the tap, and conveyed by a pipe to any required 
 place, and the remainder forced through the valve into the Boiler. In 
 proportion to the opening or closing of this tap, so will the supply of 
 water to the Boiler be less or more. Another advantage of this arrange- 
 ment is, that when no water for the Boiler is required, the tap can be set 
 fully open, and the water will flow easily away, and offer no resistance to 
 the action of the pump ; or it can be forced into a cistern, to serve as a 
 reserve for any purpose. The ordinary method is to have a weighted 
 escape-valve, which requires power to force the water through more 
 power, in fact, than to feed the Boiler. The weighted valve also involves 
 great wear and tear. A common inch tap will answer the purpose much 
 better, at a twentieth part of the cost. 
 
 A small tap may be inserted in the pump bottom, or in any part of 
 the barrel. When the pump is required to force its full quantity of 
 water into the boiler, the tap must be closed. If no water is required 
 into the Boiler or cistern, open the tap. Air will then be admitted, and 
 the pump will continue to work, without lifting or forcing water, and 
 taking little power. This is all that is required to regulate the working 
 of the pump, and that, too, without putting it in or out of gear. 
 
 " The " Injector," for feeding a Boiler by its own pressure of steam, is 
 now largely used, particularly for Locomotive Boilers. The greatest 
 drawback to the use of the " Injector " is, that the water used must be 
 cold, or not more than 80 degrees temperature, otherwise the " Injector" 
 will not act. 
 
 EXPANSION AND CONTRACTION OP BOILERS. 
 
 A great difficulty to be contended with in the management and 
 working of Steam Boilers, arises from the unequal expansion and 
 contraction of parts of the structure. In some instances these are so 
 great as to be the cause of more " wear and tear " than any other 
 process to which the Boiler is subjected. In the "getting up" of steam, 
 therefore, great care should be taken, otherwise a Bpiler may be seriously 
 
8 
 
 weakened in the process. An instance is well known where, from this 
 cause, a Double Fire-box Boiler, when quite new, was broken quite 
 across the bottom, or under-side, the first time the fire was applied to 
 " get up " the steam, from the fire being urged too rapidly. This caused 
 the internal flues to expand at a much quicker and greater rate than the 
 outward shell ; and the ends of the Boiler were thus forced outwards, 
 until the strain tore the Boiler asunder. When the flues of Boilers of 
 this form of construction are placed nearer to the bottom than to the 
 top, the strain from unequal expansion and contraction is often such, 
 that the plates of the under part of the outer shell are torn or broken ; 
 and, in other cases, leakages take place in positions where they are most 
 difficult to discover. Whenever a Boiler has been allowed to " cool 
 down," the next time it is worked the firing should be slow and moderate 
 at first, so as to allow the heat to be absorbed gradually and the evil 
 arising from undue and unequal expansion and contraction prevented, as 
 far as it is possible. 
 
 In the " setting " of Boilers, all the surface possible should be exposed 
 to the action of the heat of the fire not only that the heat may be 
 thus more completely absorbed, but that a more equal expansion and 
 contraction of the structure may be obtained. With round Boilers with 
 " e gg" or " dished" ends, and with the furnace underneath, too much of 
 the surface of the Boiler cannot be exposed to the action of the fire and 
 the heated gases. In some instances, where convenience serves, it will 
 be found of advantage to pass the flue over the top of the Boiler, to 
 equalise, in some measure, the heat, and consequently the expansion. 
 By this mode of " setting," fuel will be saved through a more complete 
 application of the heat, and the prevention of its escaping. 
 
 When a Boiler of the last-named description is " set " with only a 
 small portion of its bottom exposed to the heat, and a great portion of 
 the structure exposed to the atmosphere, as is the common practice, a 
 powerful action is left at full liberty to work out most injurious results. 
 The heat will assuredly expand that portion of the Boiler to which it is 
 applied ; while the other portion exposed to the cold atmosphere will as 
 assuredly contract. Thus the two forces are left to exert their respective 
 powers against each other tending to tear the Boiler asunder, by means 
 almost imperceptible ; and the ultimate result is not unfrequently a 
 Boiler explosion, in spite of the fact that a structure in this form is the 
 strongest possible, excepting the truly spherical. 
 
 In the construction and fixing of a Boiler, there are other matters 
 that require attention. Parts where the plates overlap should be 
 exposed as little as possible to the direct action of the fire. Where this 
 point is neglected, the outer plate is in danger of being burnt and 
 
9 
 
 weakened, until in the end leakage is caused, and the plate is rent, both 
 these tending to the destruction of the Boiler. 
 
 The thickness of the plates of which a Boiler is composed is of 
 importance in other respects besides that of requisite strength for the 
 working pressure required. It is commonly supposed that a thin plate 
 allows heat to pass through it into the water within, quicker than a 
 thick plate can do. This is true, so far as getting the water heated 
 to the boiling point. The Author has found, by direct experiment, 
 that in a Boiler formed of plate one-sixteenth of an inch thick, 
 water was brought to the boiling point in half the time it could be 
 accomplished in a Boiler formed of plate three-eights of an inch thick, all 
 other circumstances being the same. But he found, also, that when the 
 fire in the respective cases had been three hours at work, the Boiler 
 formed of the thick plate had evaporated much more water than the one 
 formed of the thin plate. Repeated experiments were invariably followed 
 with the same results showing the advantage of a moderately strong 
 plate for the flues and furnace portion of a Boiler. The Author has 
 found half-inch plate to be a desirable thickness for the fire-box and 
 flues of Cornish Boilers, having regard to strength, economy, and dura- 
 bility. It may not be amiss to observe also, that the quality of the iron, 
 and the character of the workmanship are also necessary things to be 
 attended to, in the construction of a Boiler. 
 
 Another matter to be observed in relation to a Boiler at work, is the 
 unequal pressure to which its several parts are subject at the same time. 
 Take, for instance, a Fire-box Boiler, working at 50!bs pressure to the 
 square inch. That would be the pressure exerted on the upper side of 
 the flues, slightly covered with water. Suppose the flues to be three feet 
 in diameter, on the under side of those flues the pressure would be 51 Jffis 
 to the square inch the weight or pressure of the column of water 
 having to be added to the steam pressure of 501bs. It is from this fact, 
 that the pressure is necessarily greater on the under-side than on the 
 upper side of internal flues, that, in cases of giving way from over- 
 pressure, such flues crush upwards much more often than they crush 
 downwards. There are also other actions going on in a Boiler of 
 this construction, which add to this tendency the strain and tension 
 produced by unequal expansion and contraction. This is aided, too, 
 sometimes, by the ignorance of the Boiler maker, of which an instance 
 was given by one at Stockport, who constructed a Boiler with an 
 oval internal flue, and who stayed the upper side of the flue, but 
 not the under side, where the largest amount of pressure necessarily 
 had to be sustained probably from a notion that the only pressure 
 
 to be provided against, at that part, was the weight of the water, 
 s 
 
10 
 
 The Boiler exploded the flue crushing upwards : and seventeen 
 lives paid the forfeit. However ridiculous it may appear to suppose 
 that such a notion as the one described above could be entertained 
 by a Boiler-maker, the fact was sufficiently illustrated in the case of 
 the Boiler explosion at the Castle Mills, Sheffield, some years ago. The 
 first time that steam was " got up " in the Boiler in question, the bottom 
 portion of the flat end at the back, below the flues, gave way, and the 
 Boiler was sent like a rocket out of its seating, right across a public 
 street, smash through some buildings on the opposite side of the street to 
 the Mills, and on into the river Don four lives being lost. On an 
 examination of the Boiler, the Author found that the flat ends had not 
 been stayed at the bottom portion, where the greatest pressure would 
 necessarily be ; and on the Boiler-maker being spoken to regarding this 
 serious defect in construction, he excused himself by observing he did not 
 think the Boiler required staying in that part, because where there was 
 no steam there was nothing but water, and consequently no pressure. 
 Nothing possibly could be more absurd ; and the two cases, out of many 
 that could be adduced, show the necessity for all the parts of a Boiler 
 being made suitable for the various strains to which the structure is 
 subjected when in use. 
 
 The accompanying engraving, Diagram No. 1, illustrates in a remark- 
 able manner what has just been enforced and illustrates also the 
 tremendous effects produced on the structure known as the Boiler, by a 
 Boiler explosion. The drawing represents the blown-out flue of a Steam 
 Boiler, taken exactly as it lay after it had been sent with artillery-force 
 out of the Boiler, through the wall of the Boiler-house, and across a wide 
 goit of water into a passage on the other side, near to where there was 
 another Boiler at work, which narrowly escaped destruction from the 
 flying missiles the large stone shown in the foreground of the engra- 
 ving having been sent through the wall of this second Boiler-house, with 
 one of its corners impinging on the Boiler at work, producing a large and 
 deep indentation. In this case also, the flat ends of the Boiler were 
 only stayed on the upper side. We shall subsequently refer more at large 
 to this engraving, and the positions it illustrates. 
 
 This brings us to another subject connected with the working of Steam 
 Boilers, viz : whether the iron of which the Boiler is composed is stronger 
 that is, better able to resist tension or a crushing force when cold, or 
 when heated up to the ordinary temperature of a Boiler when at work, 
 according to the pressure of the steam or from 212 to 300, or 
 more. At a Coroner's Inquest held in Leeds, on the occasion of a 
 Boiler explosion in the neighbourhood, the following question was put 
 to an Engineer a witness called to show the cause of the explosion : 
 
11 
 
 " Do you consider the Boiler to be stronger, or weaker, when heated by 
 the pressure and temperature of the steam V Answer : " I consider that 
 the Boiler is much weaker when the temperature is increased, than when 
 cold." Question : " How much with steam at 50Ebs pressure 1" Answer : 
 "Twenty-five per cent." It is lamentable that ignorance like this, 
 
 though put forward with all the assurance of professional dogmatism, 
 should pass current in a Court charged with a most important and 
 delicate inquiry an inquiry into the cause of death consequent on a 
 Boiler explosion. The very reverse of that deposed io, was the fact : for 
 
12 
 
 iron, when heated up to about 600 degrees, increases in strength up to 
 that temperature that is, it increases in power to resist tensile strain, or 
 to carry weight, up to the temperature named ; and this is therefore held to 
 be the point where the maximum strength of iron is attained. Thus, the 
 internal flue of a Boiler at work, where the upper side is necessarily at a 
 higher temperature than the under side, is the weakest in the latter part, 
 as the result of two actions : first, less temperature and second, higher 
 pressure, as before shown. Here, then, in the matter of difference of 
 strength arising from difference of temperature, we have another cause to 
 account for the fact that Boiler-flues, in cases of explosion from over 
 pressure, are more often crushed in from the under than the upper side. 
 The two actions we speak of, which are continually in operation when 
 a Boiler is in use, tend to force the flue out of the form in which it 
 was first made and thus, as it departs more and more from the perfect 
 cylinder, to become weaker and weaker. 
 
 THE FOKM, STRENGTH, AND STAYING OF BOILEES. 
 
 THE Double Fire-box, or Flue Boiler, the form now in most exten- 
 sive use, is generally formed of three tubes two lesser, and one larger. 
 The two lesser are placed within the larger, and all are bound together 
 by end flat plates. The space around these tubes, and between them and 
 the outer shell, constitutes the water space and the steam chamber. The 
 pressure, whatever it is, which the steam exerts within the Boiler, is 
 exerted within this space that pressure being internal to the large or 
 outer shell, and external to the smaller inner tubes or flues. That pres- 
 sure also, whatever it may be, is exerted upon the flat ends of the Boiler. 
 This form of construction, which is the prevailing and favourite form, is 
 not only not safe without careful staying, but positively and of necessity 
 unsafe ; and it follows, as a matter of course, that with the high pres- 
 sures now worked at, this want of safety becomes in many cases absolute 
 danger ; while, with all Boilers of this construction, unstayed, and at 
 whatever pressures they may be worked, if that pressure be appreciable, 
 their giving way is but a question of time. 
 
 The great source of danger in this form of Boiler is the inner tube or 
 flue, and the flat ends. When pressure is exerted within a tube or 
 cylinder, with spherical ends, the tube can only give way by the metal 
 being torn asunder ; and the tendency of the strain is to cause the tube 
 to assume the true cylindrical figure, or spherical form the form of 
 greatest resistance. With pressure exerted on the outside of a tube, the 
 tendency of that pressure is to crush in the tube to flatten it. 
 
13 
 
 It is a well-known fact that iron of any strength, when formed into a 
 tube, will bear a much greater strain to tear it asunder if that pressure 
 be applied internally, than it will bear without crushing in, when applied 
 externally. A bar of iron, when used as a tie-rod, will resist a very 
 large amount of tearing force ; but that same bar placed as a prop only 
 under the weight exerted in the former case, would be doubled up, and 
 crushed out of form. The inner tube of a Boiler of this construction is 
 but a series of props placed to sustain the immense weight of the pressure 
 exerted externally to its diameter. The constant and never-ceasing 
 tendency is for those props to give way for the cylindrical tube to 
 depart from the form of greatest resistance to become flattened or 
 bulged ; and its ultimate crushing-in is, in the best of cases, where 
 proper staying has not been resorted to, only a question of time. 
 
 The Double Fire-box Boiler was invented in America by OLIVER 
 EVANS, and was for a considerable period, and in some parts is still, 
 known as OLIVER EVANS' Boiler. It was used in America so far back 
 as 1786. Boiler explosions have been by no means uncommon in 
 America, as is well known ; indeed, so numerous had they been, and 
 attended with such dire results, that in 1817 a searching enquiry into 
 their cause, with a view to prevention, was instituted under the 
 sanction of the American Government. In reference to the Fire-box 
 Boiler, the report presented after that investigation states : " Many 
 respectable Mechanics and Engineers in this country considered that the 
 improved Boiler invented by OLIVER EVANS obviated the objections to 
 High-pressure Engines. The late melancholy occurrence on board the 
 Etna, in the waters of New York Harbour, is evidence that they have 
 been deceived." Mr. JACOB PERKINS, in his report on the same form of 
 construction, says, " This form of Boiler should certainly be abandoned." 
 Another eminent Engineer, Mr. C. J. JAR vis, wrote as follows : " A 
 flue of this kind may be placed in such circumstances, that when the 
 steam and temperature get unusually high, it suffers a minute change of 
 form. Under these circumstances it will inevitably collapse sooner or 
 later, according to the extent to which its form is altered at each time it 
 is unusually heated and the frequency of that occurrence, let it be 
 surrounded with as much water as it may." 
 
 There is no doubt that, providing the flues were strictly cylindrical, 
 their strength would be very great ; but such is not the case, nor is it 
 possible to make them strictly true. The very weight of the material 
 itself is sufficient to destroy the true figure of the flue, even providing it 
 were made of one whole plate without rivets or lap joints ; but in the 
 ordinary flue, as used in all Boilers, the figure of greatest resistance is let 
 go at once by the overlapping of the plates. In the case of horizontal 
 
14 
 
 tubes, as employed in Steam Boilers, the pressure is not uniform ; for, as 
 has been already shown, while the pressure on the top part of a flue, 
 three feet diameter, may be 50Jbs per square inch, the pressure upon the 
 under side would be IJSbs more; because the weight of the column of 
 water has to be added to the pressure on the lower part of the tube. 
 What should be the cylindrical figure in that case is not the true figure 
 of greatest resistance. We therefore need not be surprised at the explo- 
 sions which occur from collapse of flues, when not properly stayed. The 
 very form almost seems to invite the occurrence. It is by a continued 
 working of such description of Boiler, and the always increasing weakness 
 of the flue, from its varied pressure and temperatures, and its consequent 
 change of form, that explosions ultimately occur. Heuce the reason why 
 a tube that has been tested to a pressure of 80flbs or lOOlbs to the square 
 inch may afterwards fail under a pressure of less than half that amount. 
 
 Diagram No. 2. 
 
 CROSS SECTION OF BOILER, UPPER ASPLEY, HUDDERSFIELD, 
 
 A. Internal Flue, three feet diameter, 
 
 B. Outer Case of Boiler, five feet diameter. 
 
 The dotted lines on Flue show the form the Flue assumed when crushed upwards, 
 as shown in Diagram No. 1. 
 
 The accompanying Diagram, No. 2, is here given to illustrate what has 
 just been advanced. It is from an exploded Boiler the blown-out flue 
 being shown by Diagram No. 1. The one now presented illustrates the 
 general form of constructing the Cornish one-flued Boiler, showing the 
 relative sizes of the two tubes of which the Boiler is composed, and also 
 their relative position. A is the inner tube, or flue, open at each end ; 
 B is the outer tube, or case, closed at each end by the flat plates placed 
 
15 
 
 between the inner edge of B and the outer edge of A. The inner circle, 
 A, shows the form of the flue as originally made, and when at work. 
 The small dotted lines on this inner circle show the form that flue 
 assumed when it was crushed upwards by over-pressure, and sent out of 
 the case like a tremendous bolt from a monster gun, torn, jagged, and 
 rent in all directions, as shown by Diagram No. 1. The two lines of 
 larger dots, radiating from the outer edge of A to the inner edge of B, 
 indicate the position of the two gusset-stays placed at the fire-box end of 
 the Boiler. 
 
 It has already been pointed out that there are other changes in con- 
 nection with this form of Boiler which cannot altogether be prevented 
 from taking place. Plates crack and give way on the under side of the 
 Boiler from unequal contraction and expansion, caused by the difference 
 of temperature of the top and bottom side of the Boiler. A Boiler also is 
 materially hastened in its destruction by the emptying of it while hot, 
 and then suddenly cooling it by admitting cold water, to get off the scale. 
 Double Fire-box Boilers have been fractured on the under side, both in 
 the line of rivets and even across the plates, from this cause. Observe 
 also, when starting a Boiler and getting up the steam, and notice the 
 length of time the water on the under side of the flue is before it is even 
 lukewarm. Here, also, is an important action taking place in reference 
 to the safety of the Boiler. 
 
 The flat ends of this form of Boiler are also a source of weakness. 
 The reason of this will be at once apparent. The tendency of the force 
 within the Boiler is to cause the flat end to bulge outwards to assume, 
 in fact, the spherical form. This brings unusual and unequal strain upon 
 the rivets which join the plates together. These at last give way, being 
 either torn out, or the plate itself is riven asunder across the line of rivets, 
 and then out the ends go. Instances of this kind can be seen in almost 
 every explosion. In some cases the plates have been torn asunder as 
 though they were but paper. When once any part of a Boiler gives way 
 the other parts become exposed to unequal strain from the expanding 
 contents, which exercise a tearing and impelling force equal to that of 
 gunpowder. 
 
 To counteract this tendency of the flat ends bulging outwards, it is 
 usual to stay them. Stays, at best, are but inferior substitutes for the 
 form of greatest resistance. Stays would be of no service applied in a 
 sphere subjected to internal pressure the power of resistance would be 
 exactly that of the metal to sustain the strain, exerted upon all parts 
 alike. Stays could be of no advantage in such a construction unless they 
 could be applied so as to strengthen that metal in all its parts ; and this, 
 as will be seen at once, could only be accomplished by using metal of 
 greater thickness or strength for the original 
 
16 
 
 Boiler stays, therefore, are at all times but a substitute for real strength 
 of construction ; but the manner in which they are almost invariably 
 applied renders them insecure, and, at times, positively dangerous, because 
 they incite to the idea of security where it is in reality absent. Diagram 
 No. 3 illustrates the common method of applying stays inside a Steam 
 Boiler. The reader is to suppose that the outer lines of the engraving 
 represent a section of a cylindrical Steam Boiler, and that the straight 
 and continuous lines across the centre, marked A, represent an iron stay 
 rod, proceeding from end to end, to counteract the tendency of those flat 
 ends to bulge outwards, or be blown off with the internal pressure. It 
 will be at once apparent that if we desired to secure the utmost benefit 
 this stay-rod is capable of rendering, we should let it proceed through 
 each end of the Boiler, in a direct line with its own length ; and then by 
 means of washers, screws, and nuts, secure it in that place. The strain 
 would then be direct to its own length, and its power of resistance would 
 be equal to the weight applied perpendicularly which the iron rod would 
 sustain without tearing asunder. But stays are scarcely ever thus 
 applied. The Diagram illustrates the usual mode of application. 
 
 Diagram No. 3. 
 
 1 
 
 1 
 
 c 
 
 A C 
 
 Instead of proceeding through the Boiler-ends, the stay-rods are bent at 
 a right angle, and riveted or bolted to the Boiler through the bent parts, 
 as shown at B B of the Diagram. The strain, as will at once be seen, is 
 mainly on the bent portions of the stay : and the tendency is for those 
 bent portions to straighten out. Instead of the pull being in a direct line 
 to the length of the stay-rod, as would be the case if applied as before 
 described, the pull from each end is in the direction of the dotted lines 
 from B B to A, and the constant tendency is for the rod to leave the 
 Boiler-ends at C C, and for the end to bulge out by all the length the rod 
 can obtain by straightening at those angles. This is on the supposition 
 that the rod does not break at those angles or across the rivet holes the 
 weakest part, but on which there is the greatest strain, and that a 
 
17 
 
 bending one ; and also supposing that the rivets or bolts do not give 
 way. When we apply tie-rods to a floor or a roof, or to a beam of any 
 kind, we do not copy the mode of application adopted with Steam Boiler 
 tie-rods ; we apply them so as to secure the full power of their resistance 
 against strain or weight ; and we ought also to do so in the case of 
 Steam Boilers. 
 
 The principle of application appertaining to the gusset-stay is precisely 
 that just described and illustrated. It is formed, as before stated, of 
 angle iron and a gusset of boiler plate. An accurate representation of 
 the actual stays used in the case of the Aspley Boiler is given at 0, in 
 the engraving representing the crushed-in flue (Diagram No. 1.) The 
 strain in the case of the gusset-stays is on the angles of the angle-irons, 
 and on the rivets or bolts by which these are attached to the ends and 
 sides of the Boiler, the same as in our illustration No. 3. The power of 
 resistance is just the strain which these angles and rivets will bear with- 
 out straightening, or breaking, or tearing out. It is not by any means 
 the amount which the same metal differently applied would give. 
 Samples of all the above recited modes of giving way were to be seen in 
 connection with the gusset-stays of the Boiler at Aspley. In some cases 
 the heads of the rivets were torn off, in others the metal was torn across 
 the rivet holes, in others the angle was straightened, and in another the 
 angle was broken, and appeared to have been so for some time. 
 
 In a former page we warned the Engineer against the danger of 
 having a stop-valve placed between the Boiler and the safety, or blow-off, 
 valve. Many Boiler explosions have arisen from this cause, of which the 
 one at Upper Aspley, Huddersfield, involving a loss of twelve lives, was 
 a memorable instance. On the top of the Boiler in question there was 
 affixed a stop- valve, which is here represented in section by Diagram No. 4. 
 The lower lines of the Diagram represent the Boiler top, with the pipe A 
 standing upon it. To this pipe two arms, B B and C, were attached, 
 these also being pipes. B B led to the safety-valve, which was placed at 
 a considerable distance from this point ; and C C led to the Engine. At 
 A, a stop-valve was placed, its seat being BELOW BOTH THE APERTURES, 
 B B and C G. This valve was worked by a wheel and screw, repre- 
 sented at D. When the valve was open, the part which in our 
 Diagram closes the passage at A, was raised up above the openings of 
 the cross-pipes B B and C C, and then allowed the steam to pass either 
 way, either to the Engine or to the safety-valve, or to both. When the 
 valve was closed, it was screwed down as now represented at A, com- 
 pletely " bottling up the Boiler," and preventing all escape of the steam, 
 except by rending the Boiler asunder ! This was the exact state of this 
 stop-valve stop-valve up to a point indeed it proved to be ! and of the 
 
18 
 
 Boiler at the time of the explosion, and the state in which it had been 
 for some time, perhaps for nearly an hour, before the explosion. This it 
 was that prevented the steam from passing to the 'Engine, and induced 
 the attendants to conclude that " the steam was down." Hence the 
 injunctions to " fire up," although danger then existed ; and hence also 
 the firing, until the limits of resistance within the Boiler had been 
 Hence also the catastrophe and its fatal results ! ! 
 
 Diagram No. 4. 
 
 
 PLAN OF STOP-VALVE ON UPPER ASPLEY BOILER, IN SECTION. 
 
 A, Pipe proceeding from Boiler. C C. Feed-pipe to Engine. 
 B B, Pipe proceeding to Safety Valve. D, Wheel and Screw to raise and lower Stop-valve A. 
 
 The Inquest held on one of the twelve persons killed from the cause 
 above detailed, was attended by Mr. WILLIAM FAIRBAIRN, 0. E., in a 
 professional capacity; and he on that occasion recanted, in a great 
 measure, his former teachings in relation to the strength or power of 
 resistance of the internal flues of Boilers, with the pressure exerted exter- 
 nally to the diameter. His evidence on this occasion was : " I may 
 mention that I have recently been making some experiments with regard to 
 the collapse of tubes. It was found that some flues collapsed unexpectedly, 
 
19 
 
 and when according to our ideas, they ought not to have collapsed. This 
 induced a series of experiments interesting and conclusive. The Royal 
 Society of London made me a grant for these researches. I took a Boiler 
 of 36 feet, with a flue of three feet diameter, and another of 18 feet long, 
 and I found that the long flue will go with half the pressure of the short 
 one : that the strength is inversely as the length. I must confess that 
 previously myself and other Engineers thought that the length made no 
 difference at all ; but I find that the strength of all Boiler flues, all tubes 
 whatever, whether of iron or copper, follow a certain law, that the 
 resistance is inversely to the length." 
 
 In relation to the explosion itself, Mr. FAIRBAIRN said in his report : 
 " It will not be necessary to enter into calculations as to the forces 
 generated in the Boiler, which led to such unfortunate results. Suffice it 
 to observe that the flues and the ends were the weakest parts, and the 
 first to give way. The former collapsed from compression on its exterior 
 surface, and the fracture which gave vent to the elastic power of the 
 pent-up steam was quite sufficient to account for the results that followed 
 namely, the demolition of the buildings, and the projection of the 
 Boiler, flues, &c., into the positions in which they were found." 
 
 The result of a most searching, patient, and extended enquiry was the 
 following verdict : " The jury find that the death of Joseph Lum was 
 caused by the explosion of a Steam Boiler, the explosion resulting from 
 the screwing-down of a stop-valve, placed on the top of the Boiler, which 
 when closed, completely cut off all connection with the safety-valve ; but 
 who closed that stop-valve, the jury have no evidence before them to 
 show. But the jury, in returning that verdict, cannot but record their 
 strongest condemnation of that combination of stop-valve and safety-valve 
 which put it in the power of any one at any time to prevent the action 
 of the safety-valve by merely closing the stop-valve ; and the jury con- 
 sider that the Engineers who applied this dangerous construction are 
 highly censurable, as is also the proprietor of the Boiler, who permitted 
 it." 
 
 With regard to the strength of iron, the table which follows is the 
 result of a series of tests conducted by Messrs. ROBERT NAPIER & SONS, 
 of Glasgow. 
 
20 
 STRENGTH OF WROUGHT-IRON BARS AND IRON PLATES, 
 
 BY MESSRS. ROBERT NAPIER AND SONS. 
 
 
 IRON BARS. 
 
 
 Tenacity in fbs 
 per sq. inch. 
 
 Tenacity in fts 
 per sq inch. 
 
 Yorkshire: strongest ... 
 
 ... 62886 
 
 West of Scotland : weakest 
 
 ... 56655 
 
 weakest 
 
 60075 
 
 Sweden: strongest 
 
 48232 
 
 (forged) ... 
 
 ... 66392 
 
 weakest 
 
 ... 47855 
 
 Staffordshire: strongest 
 
 62231 
 
 Russia: strongest 
 
 56805 
 
 weakest... 
 
 ... 56715 
 
 weakest 
 
 ... 49564 
 
 West of Scotland : strongest 
 
 64795 
 
 
 
 IRON PLATES. 
 
 56005 I Yorkshire : strongest crosswise 
 52000 I weakest crosswise 
 
 50515 
 46221 
 
 Yorkshire : strongest length wise 
 weakest lengthwise 
 
 NOTE. The strongest lengthwise is the weakest crosswise, and vice versa. 
 
 According to these tests, Staffordshire bars were nearly equal to those 
 from Yorkshire. Yorkshire Boiler Plates vary from the strongest, 
 lengthwise, 56,005, to the weakest, crosswise, 46,221. These figures 
 would represent the tenacity, or the resisting power of a Boiler, supposing 
 that the plates were welded together ; but as this is not practicable, one- 
 half, or thereabouts, of the resisting power is cut away by the formation 
 of rivet-holes. The strength of the Boiler is thus at once reduced to 
 23,110, or half the strength of , the plate; and this, too, on the 
 supposition that the rivet-holes in the plates are bored. In the case 
 supposed, this rule would apply ; but in the ordinary way of Boiler- 
 making, the rivet-holes are not bored, but punched out of the solid cold 
 metal by powerful machinery. This punching to a great extent impairs 
 the tenacity of the remaining portion of the plate betwixt the holes. 
 Then follows another process more injurious than the former what is 
 technically called " drifting." This " drifting " is a process whereby the 
 holes of one plate are made to correspond with the holes of another 
 plate, when the plates are in progress of being riveted together. When 
 the holes do not exactly meet each other, so that the rivet will pass easily 
 through both, the Boiler-maker uses an instrument called a " drift." 
 This is a taper " mandril," which is driven into the two holes, and widens 
 them out by the force of blows with the hammer. It often happens 
 that the metal betwixt the holes at the edge of a plate is " cracked " 
 with the " drifting " in many cases weakening, and in others so far 
 destroying, the tenacity of the remaining metal, that the strength of the 
 remaining portion cannot be taken at more than 20,OOOBbs. In some 
 instances where the plate in its process of manufacturing has had but 
 little cut from its edges, when being " squared up," the edges of the 
 
21 
 
 plate are quite brittle ; and then, what with the before- mentioned mode 
 of punching, and what with bending the plate in a cold state, such plate 
 may be frequently seen " cracked " from hole to hole. From these and 
 similar causes, a Boiler is often more than half destroyed before it leaves 
 the Boiler-maker's yard. 
 
 In the process of bending Boiler Plates cold, the fibres of the metal 
 are stretched, and their tenacity impaired or destroyed. Were they 
 passed between bending-rollers, when heated to a proper working heat, 
 the fibre would be properly drawn out, and its tenacity preserved the 
 same as in any other process of forging or shaping wrought iron. There 
 cannot be a doubt that in the case of Boiler-flues bent cold to diameters 
 varying from two feet to three feet, the plates are thereby weakened to 
 a great extent. So long as the present mode of Boiler-making is 
 pursued, we shall have weak and defective Boilers. The expense of 
 heating the plates, for the purpose of bending them without injury, 
 would be trifling. And there would be another resulting advantage : if 
 there were any " flaws " in the metal, these would sooner show in the 
 plate when in a heated state, than when bended in a cold state. 
 
 The suggestion has often been thrown out, that were the rivet-holes 
 of Boiler Plates bored instead of being punched, one part of the evil 
 above pointed out would be remedied. There is no doubt but that 
 process would be a great improvement upon the present practice j and if 
 some independent firm would make Boilers with the same care and 
 attention to material and workmanship as is done in Steam Engine 
 construction, they would command a trade, although their prices would 
 necessarily be higher than those who " make " in the ordinary manner. 
 To the user, Boilers thus carefully built would be much cheaper in the 
 end, to say nothing of the reduction to risk of life the loss of which 
 cannot be compensated for ; and this to the humane is a consideration 
 of importance. 
 
 The rule laid down for the strength of Steam Boilers, taking the 
 tenacity of the plates at 60,000, is, according to the tests of the Messrs. 
 NAPIER, far too high ; and considering the before-mentioned methods of 
 Boiler-making, we ought not to calculate the resisting power of Boilers 
 at more than two-thirds the amount we have been in the habit of 
 calculating. That is, instead of calculating the tenacity at 30,OOOS>s, 
 we should not calculate that tenacity at more than 20,OOOIbs. Thus, 
 the bursting pressure of a tube 30 inches diameter, made of f inch 
 plates, under the old rule, would be 750Ibs to the square inch ; according 
 to the new rule it would only be 500Ibs to the square inch. This new 
 rule will be much nearer to the truth in practice than the former rule ; 
 and the tube would also require to be of good material, and well made, 
 to resist 5005>s to the square inch. 
 
22 
 
 Whatever may be the strength of Boiler Plates before they are worked 
 into shape, if care and attention are not paid to the bending, punching, 
 drifting, and riveting, the best iron will become comparatively valueless. 
 With the best material, the strength of a Boiler must greatly depend 
 upon the manner in which it is made, and the care used in its construc- 
 tion, even if its form be correct in principle. 
 
 RULE FOR CALCULATING THE STRENGTH OF CYLINDERS OR BOILERS, AS 
 GENERALLY APPLIED.* 
 
 The tenacity of the metal of which a Boiler is constructed is about 
 60,0001bs, or six-sevenths that of good wrought-iron a bar one inch 
 square being the standard. 
 
 As, however, the cylinder which constitutes the Boiler is not whole, or 
 in one piece welded together, but is composed of a number of plates 
 riveted together the plates also being cut away for the holes it will be 
 necessary to diminish the number which expresses the tenacity. Let, 
 therefore, the tenacity be put at 30,OOOK>s, in place of 60,OOOS>s. 
 
 Multiply the numerator of the thickness by the tenacity of the metal, 
 and multiply the denominator by half the diameter of the cylinder in 
 inches ; then divide the numerator by the denominator, and the quotient 
 will give the strength of the cylinder, or bursting pressure. 
 
 EXAMPLE I. 
 
 Take a cylinder 30 inches diameter, made of f inch plate : thus 
 
 3 30,000 90,000 
 
 - x = then 90,000 
 
 8 15 120 
 
 120 = 750fts, the bursting pressure. 
 
 EXAMPLE II. 
 
 A cylinder of six feet diameter, made of inch plate : thus 
 
 6 feet = 72 inches 
 
 1 30,000 30,000 
 
 - x = then 30,000 -f- 
 
 2 36 72 
 
 72 = 416 and 17-18ths fts., working pressure. 
 
 * This rule is the one generally acted upon, and is no doubt pretty nearly correct, when the 
 metal is without flaws, and the workmanship without defects. But as these cannot always be 
 relied upon, the rule and the deduction from it will be found to be far too high for ordinarily made 
 Boilers. [See observations and deduction on preceding page.] 
 
23 
 
 TESTING BOILERS. 
 
 THE utility of testing Boilers to an extreme, or to considerably more 
 than the strain sustained in actual use, is more than questionable. 
 Practice has taught that it is better not to test Boilers, beams, or bars of 
 iron, with more than the ordinary strain required. We may, by an 
 extreme test, prove that the article tested has withstood such and such a 
 strain : but we do not know how such strain may have injured the 
 substance tested. For instance, a cast-iron beam was tested at the 
 foundry of Messrs. MILLBURN'S, Staley bridge. The beam was 27 feet 
 long. A weight of 24 tons was hung on the centre, with which the beam 
 deflected 1 J inches. When the weight was removed, the beam assumed 
 its former form. The same beam was shortly afterwards tested with 1 6 
 tons hung on the centre, when it broke though there were eight tons 
 less than it had withstood before. 
 
 Another instance was afforded in the test of a Steam Boiler at Messrs. 
 HARGREAVES, at Accrington. The hydraulic test was resorted to. The 
 extreme working pressure of the Boiler was a little under 40Ibs to the 
 square inch, and the test the Boiler was submitted to was 703bs to the 
 square inch. To all appearances, under the test the Boiler was safe at 
 that pressure. In about three months after this testing, the Boiler 
 exploded ; and on investigation, there was sufficient to show that the test 
 to which the Boiler had been subjected injured the structure and from 
 that time till the whole gave way, the Boiler had been gradually getting 
 weaker. The flues had been strained by the test, the pressure being on 
 the outside of the diameter. 
 
 There can be no doubt that the testing of any structure or machine to 
 the full strain the apparatus may be expected to resist, is highly neces- 
 sary ; but beyond that, there is more risk of injury to the apparatus 
 tested, than any chance of good resulting from an extreme test. 
 
 The word " test " carries with it to the theorist and the casual observer 
 an idea of security because such test affords proof that the machine or 
 structure has withstood a certain force. This may be quite true : but it 
 does not follow that the same machine or structure will resist the same 
 amount of force again, or anything approximating to it. 
 
 CLEANSING BOILERS. 
 
 It is well known that water impregnated with earthy matters produces, 
 when boiling in a Steam Boiler, a scum on the surface. If this scum be 
 collected and blown out, the Boiler will seldom require to be opened and 
 cleansed ; but if the scum be allowed to accumulate and settle upon the 
 
25 
 
 plates where the fire impinges, the injury to the Boiler will be in propor- 
 tion to the thickness of the accumulation, which, according to the nature 
 of the deposit, assumes the form of scale, or mud. When it assumes the 
 first-named form, the Boiler will require to be often opened and cleansed, 
 or the injury from the burning of the plates will be great. 
 
 An arrangement has been patented by Mr. NEEDHAM, of Duckinfield, 
 near Manchester, for the collection and riddance of the scum, or deposit. 
 His apparatus consists of a number of hopper-like mouthed vessels, 
 introduced into the Boiler standing a little above and below the water- 
 line. These vessels communicate, by means of vertical pipes, with a 
 horizontal pipe that passes through to the outside of the Boiler. As the 
 scum arises, and falls again in the water, the open-mouthed vessels 
 collect it ; and, as at intervals, the valve at the end of the pipe spoken 
 of is opened, the collected scum or deposit is " blown out," and the Boiler 
 plates are thus kept clean. See Diagrams Nos. 5, 6, and 7. 
 
 Diagram No. 7. 
 
 In the above diagrams the longitudinal pipe, extending from end to 
 end, is shown at A, which is perforated with two rows of small holes, 
 communicating by the elbow pipe, C, to the cock or valve, D. At the 
 top of the longitudinal pipe, A, there are vertical pipes, E, each mounted 
 by a cast-iron funnel, F, at the level of the water, the mouth of which 
 faces the front, or firing end of the Boiler. The cast-iron funnel in 
 Diagrams No. 5 and 7 is supplied with elevated partitions, H, leading 
 to the receiving chamber at the top of the vertical pipe, E. The heat 
 from the firing end causes a continual roll or flow of water towards the 
 
26 
 
 back end, by which means the scum enters the funnels, from whence, by 
 opening wide the cock, or valve, D, it is swept away into the sewer or 
 drain. The apparatus can be so modified as to suit every description of 
 Boiler, whether multitubular, two-flued, or egg-shaped ; and in adapting 
 it to the Boiler, the latter requires no cutting. Any length of Boiler 
 can be cleansed from end to end in less than one minute, without 
 stopping the working. 
 
 There are other modes of collecting the scum, namely, by open trays 
 placed in the Boiler ; and also by a pipe from the bottom of the tray to 
 the outside of the Boiler, with a tap. By opening the tap, the heavy 
 matter collected in the trays is blown out. Mr. ROBERT ARMSTRONG, 
 formerly of Manchester, applied the tray principle to Boilers more than 
 thirty years ago ; since then, various modifications have been adopted, 
 and improvements made as shown by Mr. NEEDHAM'S plan. 
 
 In water there is a great difference in quality for Steam Boiler purposes. 
 Some waters scarcely give out any deposit, while with others the deposit 
 is great ; and this is the cause of considerable difficulty, if not constantly 
 removed. It therefore behoves the Engineer, when he has to work with 
 water of the latter description, to be exceedingly attentive, and to look 
 well after the interior, as well as the exterior, of his Boiler : and par- 
 ticularly where the water has spent-dye wares and acids mixed up with 
 it, as is often the case in manufacturing districts. In this matter, as in 
 many others, he may lay it down as a rule, that the utmost cleanliness 
 possible will result in a saving of fuel, and in the prevention of much 
 " wear and tear " to the Boiler. 
 
 THE SAFETY VALVE. 
 
 THE form and construction of this indispensable adjunct to the Steam 
 Boiler are of the highest importance, not only for the preservation of 
 life and property, which would, in the absence of that means of " safety," 
 be constantly jeopardised, but also to secure the durability of the Steam 
 Boiler itself. And yet, from the manner in which many things called 
 Safety Valves have been constructed of late years, it would appear that 
 the true principle by which safety is sought to be secured by this most 
 valuable adjunct, is either not well understood, or it is disregarded 
 by many Engineers and Boiler-makers. Many of those unfortunate 
 calamities Boiler explosions have occurred when, to all appearance, 
 the Safety Valves attached have been in good working order: and Juries 
 under the presidency of Coroners, have not unfrequently been puzzled, 
 and sometimes guided to erroneous verdicts, by scientific evidence adduced 
 
27 
 
 before them, tending to show that nothing was wrong with the Safety 
 Valves and that the devastating catastrophes could not have resulted 
 from over-pressure, because in such case the Safety Valve would have 
 prevented them. 
 
 If the inventor, Dr. PAPIN,* of that most useful and scientific appa- 
 ratus, the Safety Valve, could but witness some of the forms given to 
 the instrument, and some of the modes of construction adopted, he would 
 indeed marvel to see the degeneracy which, in this day of general 
 improvement, is but too often apparent in the manufacture and construc- 
 tion of this essential and indispensable adjunct. 
 
 The portions numbered 1 and 2 on the accompanying engraving, page 
 28, represent variations of the Common, or Mushroom Valve. This is 
 usually constructed with a guide-pin, to pass through a hole or socket 
 provided in the cross-bar inserted in the seating of the Valve such 
 guide-pin and steadying-socket being underneath the Valve, and conse- 
 quently within the Boiler, constantly and fully exposed to the action of 
 the steam, the varying temperatures, and to the accumulations of dirt 
 and other extraneous matters. With this form of construction alone, 
 numerous Boiler explosions have occurred from the stem, or guide-rod, 
 of the Valve having got bent, or otherwise damaged ; from its having 
 become corroded in the steadying-socket of the cross-bar; from its 
 becoming fast in its place, when closed ; or from many other and obvious 
 causes. It is clear that when the Mushroom Valve is in any one of 
 these states it is impossible for it to act, and the Boiler is then, to all 
 intents and purposes, as if nothing in the shape of a Safety Valve 
 had been provided. 
 
 Another objection to this form of Safety Valve is, that the weight to 
 keep down the valve till the limit of safety is approached, is applied in 
 the worst form possible to ensure accuracy in the indications of the valve, 
 or to allow of the free working of that valve when over-pressure requires 
 it to open. In valves of this construction, there is generally provided 
 on the lever a swell, or projection, rounded down at the end to a dull 
 point ; and this dull point rests in a small counter-sunk hole in the outer 
 tip, or central projection of the valve (as in the portion numbered 2 of 
 the engraving, page 28) ; or the point on the tip of the valve rests in 
 the counter-sunk hole in the projecting portion of the lever (as in the 
 portion of engraving numbered 1). When the weight is hung on the 
 other end of the lever, or at such place upon it as has been arranged for, 
 the swell, or projection, on the lever bears upon the tip of the valve, and 
 keeps that valve down on its seat until it is raised therefrom by over- 
 
 * Dr. Denys Papin, a native of Blois, in 1680, invented the common Lever Steam Valve, mis- 
 named the " Safety Valve." 
 
pressure of steam within the Boiler. But it is a question arising from 
 this mode of applying the weight, whether the valve can act at the time 
 and in the manner designed. In the first place, the joint at the end of 
 the lever, where it is attached, must necessarily have some play given it. 
 
 Oftentimes greatly too much is given j or rather, no care to have exact- 
 ness of fitting is exercised. This play, from the action of the lever and 
 wear and tear, becomes greater and greater ; and every departure from 
 exactness, either in the original manufacture, or from subsequent wear, 
 
29 
 
 takes the weight from the centre of the valve, and brings it more upon 
 one or other of its sides than the rest. These deviations from exactness 
 may be small, almost infinitesimal, in themselves : but multiplied as they 
 are in fact, in the ratio of the length of the lever from its attachment 
 to the point of bearing on the valve, they become anything but inappre- 
 ciable, or non-detrimental to the free action of the valve. When the 
 valve is thus weighted out of its centre, two separate but injurious 
 actions take place : first, when over-pressure occurs, instead of the valve 
 being lifted bodily from its seat, it becomes tilted, and the steam escapes 
 at one side only : and second, in consequence of this tilting, the guide- 
 rod often becomes bound fast in the guiding-socket of the cross-bar ; and 
 the valve is thus prevented from operating, except in a very limited 
 degree not nearly sufficient in cases of over-pressure. The worst is, 
 that under the circumstances supposed, the higher the pressure that is, 
 the greater the danger from which the valve is required to relieve the 
 less capable does it become of operating in the manner for which it was 
 calculated and designed : for the greater the force brought to bear upon 
 the tilted portion of the valve (and be it remembered that this tilting 
 exposes more of the surface of the valve-face on the tilted side than on 
 the side which still remains covered by the seating) the more firmly 
 does the valve become bound in the guiding-socket. From these and 
 other causes of a similar nature, Safety Valves of this construction 
 cannot be made to work accurately and they are totally inapplicable 
 for high pressures, if " safety " is to be a consideration. The indications, 
 however carefully the valves may have been weighted, are often most 
 inaccurate. The Author has known valves of this description to be kept 
 as perfectly down to their seatings as they are capable of being kept 
 that is, without any escape of steam from over-pressure when the 
 pressure in the Boiler, as measured by a more accurate test, has been 
 12Ibs more than the valve was calculated and weighted to blow off at. 
 With a valve of this description, any one, by moving the lever to and 
 fro, may cause the steam to escape at either of its sides. To counteract 
 this tendency to tilt, other guides have at times been applied ; but it has 
 been found in practice, that this attempt to remedy one evil has only 
 been to create others, which equally tended, and in like manner, to 
 prevent the proper and safe working of the valve. 
 
 The main portion of the accompanying engraving, (Diagram No. 8,) 
 is a representation of a Safety Valve which has been designed and 
 introduced to prove that a valve of the ordinary kind may be made to 
 act well, generally speaking to blow off from over-pressure, with far 
 greater accuracy than either of the constructions before considered, and 
 also with a uniform discharge of steam from all sides of the valve orifice, 
 
30 
 
 when open. The valve is of the spherical form on its under side ; and 
 it is placed within outward guides affixed to the seating. The weight 
 is brought upon the valve from a low-fixed centre the centre-pin 
 being jointed to the lever, or fixed thereon by other means, so that there 
 be the requisite play for the pin always to bear on the centre of the 
 spherical Valve. The small weight on the short or fastened end of 
 the lever, is merely for the purpose of balancing the long end of the 
 lever, so that when the ball-weight for weighting the valve is off, the 
 valve is entirely free from outward pressure. Where this portion of 
 the arrangement is dispensed with, the weight of the lever as it bears 
 on the valve has to be taken into account, when calculating the weight 
 to be used for weighting the valve, and also the several distances on 
 the lever at which that weight will have to be placed for the various 
 pressures required. 
 
 In all cases it is advisable to have the face of the seating of the Safety 
 Valve as narrow as the varying modes of construction will allow. The 
 spherical-faced Valve is best adapted for this and other beneficial 
 purposes : for it is found in practice that the sharp edge of the seating, 
 taken off only by grinding it and the spherical Valve to a face, results 
 in the greatest accuracy that can be obtained while this form and mode 
 of construction also ensures the best fitting valve for " bottling up " the 
 steam when it is not required to escape. 
 
 The Valve shown in the foregoing illustration is not adduced and 
 recommended as one perfect in every particular ; but it is believed to be 
 as good a valve as can be made simply as a Lever Valve securing the 
 greatest accuracy of which this form of construction is capable one 
 providing for the discharge of steam better than any other mere Lever 
 Valve yet introduced. 
 
 In connection with this subject of Safety Valves, the Author would 
 not be doing his duty to those for whom his work is intended, were he, 
 from any feeling- of mock-modesty, to refrain from describing the 
 construction and the advantages of what is now very well known as 
 " HOPKINSON'S (PATENT) COMPOUND SAFETY VALVE" as that Valve 
 possesses important features not to be found in connection with any other 
 valve : and as it provides against that prolific source of Boiler explosions, 
 deficiency of water, as well as for the copious discharge of steam at 
 over-pressure, under the ordinary conditions of working. When 
 the facts are stated, that this Compound Valve has been applied 
 to upwards of four thousand Boilers and that in no single instance has 
 a Boiler with this Valve attached, exploded or suffered injury, either from 
 over pressure or deficiency of water while most numerous are the 
 instances where Boilers have been saved by the simple, but certain, action 
 
31 
 
 of the instrument, under circumstances which, with the ordinary valve, 
 would inevitably have resulted in explosion, the Author feels that he 
 may fairly claim to be exempt from the charge of " puffing his own 
 wares " in giving the following description of a construction which has 
 already effected mucli good, and which, as experience warrants him in 
 saying, is the most effectual Safety Valve ever yet introduced into Steam 
 Engineering. 
 
 The description of the Compound Valve which follows, formed part of 
 a Paper read before the British Association, at the Leeds Meeting in 
 1858 : 
 
 "THE (PATENT) COMPOUND SAFETY 
 VALVE comprises two distinct valves : a 
 large 54-inch diameter valve, with, flat 
 face, and a spherical, or ball-faced valve, 3 
 inches diameter, The smaller, or ball- 
 valve seats upon an opening in the centre 
 of the larger valve. The larger valve is 
 weighted by means of a lever and ball, as 
 in the common Safety Valve. There is an 
 iron bridge, or cover casting, which fits to 
 the large valve, and forms the centre for 
 the centre-pin to give pressure upon the 
 valve enclosed within the casing. Resting 
 upon the holed-centre of the large valve is 
 the ball- valve. This last is weighted by a 
 dead weight inside the Boiler the dead 
 weight being composed of iron-plate cast- 
 ings. When the steam exceeds the pres- 
 sure this ball-valve lifts, and the steam 
 escapes through the openings in the bridge 
 casting into the dome, or shell-casing, and out into the atmosphere. As soon as the ball- 
 valve lifts from its seat, the large flat valve also lifts from it$ seat ; thus a, double means 
 of discharge is given to the excess of steam. This feature is of importance, inasmuch as 
 the whole construction forms a valve possessing an opening, or discharging area, equal 
 to an ordinary Safety Valve 8 inches diameter. 
 
 " The Compound Valve cannot be weighted beyond its working pressure whilst the 
 Boiler is at work. Should an attempt be made to over-weight the outside lever, or 
 even should a man press upon it with all his force, it would be useless. So long as the 
 ball-valve is there, properly weighted inside the Boiler, all is right. Should the 
 ball-valve be over-weighted intentionally, whilst the Boiler is standing for cleaning, it 
 may instantly be detected on getting up the steam. 
 
32 
 
 " Turning to the next feature, we come to an improved arrangement for deficiency of 
 water. There is a lever suspended in the Boiler. The rod which bears the dead weight 
 for the ball- valve passes through a large hole in this suspended lever. On this rod is 
 fixed a collar, arranged so as to allow the lugs of the lever to come in contact with it. 
 One end of the lever, or beam, suspended in the Boiler, bears a large float ; and at the 
 opposite end there is a balance-weight, to counteract the buoyancy of the float when 
 immersed in the water. The smaller weight is also to keep the tip of the lever up against 
 the underside of the top of the Boiler. The float on the other end, or long arm of the 
 lever, is immersed in the water to such a depth as is fixed for extreme "low- water mark." 
 Should the water begin to leave the float, the specific gravity of the float will be brought 
 upon the long end of the lever. This lever, it will be remembered, is hung to the Boiler, 
 and works on a centre. By the depression of the long end, the lugs of the short end are 
 brought into contact with the collar on the rod attached to the central, or spherical, valve, 
 and that valve is thereby raised from its seat. Should the water still get lower, the valve 
 continues to rise, and will continue raised until the water be again at its proper height, 
 Should the first warning be disregarded, the steam will be discharged from the Boiler, 
 stopping all working, and rendering explosion impossible. Timely notice is given of such 
 first deficiency by the continual quivering of the valve on its seat ; and if this be not 
 attended to, the valve will open to the full extent. 
 
 " The advantages of the Compound Valve are as follow: Its combination of parts, which 
 are such as to act for excessive pressure and deficiency of water ; its general mechanical and 
 practical arrangement the Valve possessing neither spindles, guides, rubbing surfaces, 
 nor parts liable to adhere. It is simple in construction, and certain in action, while it 
 can be used as any other valve for general working ; it prevents the careless, the ignorant, 
 or the wanton, from causing either injury to the Boiler, or Boiler explosions ; it is not 
 liable to derangement, and is in every detail what a Safety Valve ought to be." 
 
 To this the Author has only to add that he believes the Compound 
 Valve, constructed as above described, has not hitherto been exceeded for 
 accuracy, if indeed it has been reached. It is so sensitive in action, that 
 when the steam is of that pressure as to just affect the Valve on its seat, 
 should the Engine be then started, the revolutions of the Engine may be 
 observed and counted by merely noticing the pulsations of the Valve 
 as it will rise and fall according to the minute variations of pressure 
 occasioned by the withdrawals and stoppages of steam from the Boiler to 
 impel the piston. 
 
 RULE TO ASCERTAIN A*T WHAT PRESSURE A SAFETY VALVE IS WEIGHTED. 
 
 First ascertain the length, in inches, of the fulcrum, and the length, in inches, of the 
 lever, from its attachment to the place where the weight is hung. Then ascertain the 
 weight, in pounds, of the ball- weight. 
 
 Multiply the length of lever by the weight of the ball- weight. Then multiply the area 
 of the Valve* by the distance of the fulcrum from the attached end of the lever. Then 
 take the product of the former, and divide by the latter. The quotient is the pressure for 
 which the Valve is weighted in pounds per square inch. 
 
 * The area of any Valve may be found on reference to the " Table for Safety Valves, Cylinders, 
 Air Pumps, &c.," in the Appendix. 
 
33 
 
 RXAMPLE. 
 
 42 fts, weight of ball. 10 inches, area of Valve. 
 
 50 inches, length of lever. 3 length of fulcrum. 
 
 2100 30 
 
 30 ) 2100 ( 70ft>s per square inch. 
 210- 
 
 This illustration is from the Valve shown by the engraving on page 28, which has the 
 respective measurements and weights figured thereon. 
 
 The introduction of the above simple method of calculation is not for 
 the purpose of superseding any readier method, or those usually adopted 
 by the mathematician, and the skilled and practical Engineer. It is 
 intended for those who have not any other means of arriving at the 
 required result. 
 
 PLAN AND DIMENSIONS OP A NOMINAL FORTY-HORSE POWER 
 DOUBLE FLUE FIRE-BOX BOILER. 
 
 Length, 30 feet ; diameter, 7 feet 6 inches. Two fire-boxes and flues, 
 3 feet diameter. The whole composed of J inch plate, except the ends, 
 which should be f of- an inch thick. A Boiler of this size and strength 
 is well calculated to resist a working pressure of 60Ibs to the square 
 inch, and will generate sufficient steam, with a good draught, to drive an 
 Engine working 150 indicated horse power, besides steam for warming 
 and other purposes. 
 
 The accompanying Illustration, Diagram No. 9, of a Steam Boiler, of 
 the dimensions above set forth, shows also the Patent Spiral Circulating 
 Pipes attached to the flue behind the bridge, six of which are placed in 
 each flue. 
 
 The engraving also shows an improved method of staying the fluea 
 and ends of a Steam Boiler, and providing for the expansion and 
 contraction of the flue, without injury to the Boiler ends or the angle 
 irons. In the Illustration four hoops or rings are shown encircling the 
 flue. These hoops or rings do not touch, nor are they attached to the 
 flue, except by means of bolts or rivets, which are set so that there is a 
 space betwixt the plate and hoop of about one inch. This space allows 
 the water to have free contact with the whole of the surfaces, and 
 prevents an undue thickness of metal being exposed to the fire an 
 arrangement so objectionable in flues stayed with T iron. The improved 
 hoops or ring-stays can be put together either whole, or in segments, 
 
02 
 
35 
 
 The staying of the ends is accomplished by riveting a plate on the 
 inside of the end plate of the shell, that plate having slits or spaces for 
 cross plates or bars of such thickness and width as may be deemed of 
 sufficient strength to bear the pressure brought upon the ends of the 
 Boiler. Bolts or rivets proceed through the end of the Boiler, and are 
 drawn up against a collar on the edge of the plates or bars across the 
 Boiler ends. These prevent the Boiler ends from buckling, or getting out 
 of form. 
 
 An expansion joint is also shown in the back part of the flue, provided 
 to allow for the expansion and contraction of the flue an action which 
 in the ordinary construction is very injurious to Boilers, from the sudden 
 heating or cooling, and the various changes in pressure. There is a hoop, 
 to which the sides or copper flanches are affixed, which flanches open or 
 compress as required. The bridge, as shown with an inclined surface, is 
 so formed that the flame and gases may have a free and unobstructed 
 passage into the flue. The feed-pipe is also shown extending some distance 
 into the Boiler, and is perforated with holes, to distribute the water 
 near the surface. 
 
 The (Patent) Compound Safety Valve is also shown in elevation on 
 the Boiler. The raised manhole, with branch steam pipe, answers the 
 purpose of a steam chest. 
 
 LONGITUDINAL SECTION OP A NOMINAL FORTY-HORSE STEAM 
 BOILER, WITH STAY PIPES, 
 
 For strengthening Flue Tubes of Boilers, and increasing their evaporative power. 
 
 THE Stay Pipes, of which illustrations are given in Diagrams No. 10 
 and 11, have been devised with the two-fold object of strengthening the 
 weakest portion of the Cornish Boiler, and of greatly increasing the heat- 
 absorbing surface. The Stay Pipes, when applied, act as a series of props 
 or stays, against the crushing-in tendency of the pressure exerted on the 
 outer diameter of the flue : thus enabling a flue to resist efficiently a 
 much greater pressure than any flue of the ordinary construction could 
 bear, without that change of form which, under ordinary circumstances, 
 is constantly taking place while, as will be seen at a glance, they add 
 in a very appreciable degree to the evaporative power of the Boiler. 
 
 These Stay Pipes may be fixed in any position, and in considerable 
 number each tube being so much of an addition to the former heat- 
 absorbing surface. They can be applied to old Boilers as well as to new 
 ones. They are fixed with conical collars into taper holes, and well fitted 
 
37 
 
 with screws and nuts on the outer diameter of the flue, so that the latter 
 is kept closely pressed up to the pipes. The pipes are made of cast iron, 
 about | of an inch thick. When fixed, the whole flue and pipes or 
 props, together, are framed into one compact mass, capable of resisting 
 any pressure that the outer shell of the Boiler will sustain. 
 
 Another advantage arising from the application of the Stay Pipes, is, 
 that circulation of the water from the space underneath the flue is 
 thereby secured. The pipes take in their supply from the bottom, and 
 discharge the highly-heated water at the top of the flue thus tending 
 to keep an even temperature in the Boiler, and to prevent that uneven 
 expansion which in the ordinary Boiler is known to be very destructive. 
 
 Diagram No. 11. 
 
 SECTION OF FLUE OF A STEAM BOILER, 
 
 With Cast Iron Pipes with Wrought Iron Ends, Conical Collars, and Nuts. 
 
 In the preceding pages hints and suggestions have been put forth, as 
 briefly as was consistent with the important subject in hand. At page 
 12, on the strength of iron at different temperatures, reference is made to 
 the maximum strength of iron, when heated. The following Table, 
 taken from experiments conducted by the Franklin Institute, in America, 
 will be found worthy of consideration. 
 
 - 
 
 OF THE 
 
 fUir/EESITY 
 
38 
 
 TABLE: 
 
 SHEWING THE INCREASE AND DECREASE OF THE STRENGTH OF IRON ) 
 
 AT VARIOUS / 
 
 Comparative view of the influence of High Temperatures on the \ 
 strength of Iron* as exhibited by 73 experiments on 47 different > 
 specimens of that metal, at 46 different temperatures from ) 
 
 
 15 4J 
 
 
 e 
 
 ta i 
 
 
 a 
 
 2 
 
 *Ja 
 
 
 1 
 
 re observed 
 ent of f ractu 
 
 te 
 
 ordinary ten 
 
 periments 
 temperature; 
 
 if 
 
 xperiments 
 iperatures. 
 
 variation iro 
 y in the co 
 nts. 
 
 S9 
 
 
 1 
 
 II 
 
 ,- 
 
 2s 
 
 m >- 
 | 
 
 21 
 
 1 
 
 2|| 
 
 ^ll 
 
 8 
 
 *s 
 
 
 If -8 
 |11 
 
 <3 
 
 1 
 
 fl 
 
 of 
 
 ||| 
 
 |!' 
 
 1 
 
 si 
 
 H" 
 
 
 
 
 
 35 
 
 ,"* 
 
 * 
 
 H 
 
 9 
 
 1 
 
 212 
 
 137 
 
 56736 
 
 1 
 
 67939 
 
 
 
 + 197 
 
 
 2 
 
 214 
 
 133 
 
 53176 
 
 1 
 
 61161 
 
 
 
 + 150 
 
 
 3 
 
 394 
 
 58 
 
 68356 
 
 1 
 
 71896 
 
 
 
 + 052 
 
 
 4 
 
 394 
 
 148 
 
 65143 
 
 1 
 
 69752 
 
 
 
 + 070 
 
 
 5 
 
 394 
 
 23 
 
 62646 
 
 2 
 
 67765 
 
 
 1041 
 
 + 081 
 
 
 6 
 
 394 
 
 125 
 
 57182 
 
 1 
 
 63322 
 
 
 
 + '107 
 
 
 7 
 
 394 
 
 61 
 
 55297 
 
 5 
 
 61917 
 
 
 2026 
 
 + 119 
 
 
 S 
 
 396 
 
 75 
 
 60433 
 
 3 
 
 62415 
 
 I 
 
 0444 
 
 + 031 
 
 
 9 
 
 440 
 
 224D 
 
 49782 
 
 4 
 
 59085 
 
 1 
 
 0908 
 
 + 187 
 
 
 10 
 
 520 
 
 224B 
 
 54934 
 
 4 
 
 58451 
 
 1 
 
 0992 
 
 + 064 
 
 
 11 
 
 550 
 
 199A 
 
 76986 
 
 4 
 
 79846 
 
 2 
 
 0936 
 
 + 037 
 
 The standard 
 for the original 
 
 12 
 
 550 
 
 221A 
 
 60518 
 
 4 
 
 60322 
 
 1 
 
 1680 
 
 004 
 
 strength may 
 
 13 
 
 552 
 
 14 
 
 52542 
 
 1 
 
 55932 
 
 1 
 
 
 + 064 
 
 possibly be a 
 little too high. 
 
 14 
 
 554 
 
 218A 
 
 58124 
 
 4 
 
 60412 
 
 1 
 
 0730 
 
 + 039 
 
 
 15 
 
 554 
 
 22 
 
 54372 
 
 4 
 
 61680 
 
 3 
 
 1919 
 
 + 134 
 
 
 16 
 
 560 
 
 224E 
 
 50528 
 
 7 
 
 58824 
 
 1 
 
 0605 
 
 + 158 
 
 
 17 
 
 562 
 
 224c 
 
 53385 
 
 5 
 
 59623 
 
 1 
 
 1919 
 
 + 104 
 
 
 18 
 
 563 
 
 60 
 
 60907 
 
 4 
 
 72588 
 
 2 
 
 0460 
 
 + 191 
 
 
 19 
 
 564 
 
 74 
 
 51030 
 
 5 
 
 58824 
 
 1 
 
 0764 
 
 + 142 
 
 
 20 
 21 
 22 
 
 568 
 572 
 572 
 
 9 
 219B 
 49 
 
 67211 
 
 66724 
 59607 
 
 2 
 2 
 3 
 
 76763 
 66620 
 62278 
 
 1 
 1 
 1 
 
 0601 
 0325 
 0878 
 
 + 042 
 002 
 + 045 
 
 {Standard pro- 
 bably too high 
 for the mean 
 strength. 
 
 23 
 
 572 
 
 222s 
 
 56165 
 
 4 
 
 60117 
 
 2 
 
 1550 
 
 + 070 
 
 
 24 
 
 573 
 
 10 
 
 64511 
 
 1 
 
 67503 
 
 3 
 
 
 + '046 
 
 
 25 
 
 574 
 
 231 
 
 76071 
 
 5 
 
 65387 
 
 1 
 
 1373 
 
 + -014 
 
 
 26 
 
 575 
 
 220A 
 
 54263 
 
 4 
 
 60988 
 
 1 
 
 0280 
 
 + -124 
 
 
 27 
 
 575 
 
 62 
 
 58376 
 
 3 
 
 70081 
 
 3 
 
 0262 
 
 + -200 
 
 
 28 
 
 575 
 
 207 
 
 51924 
 
 5 
 
 63825 
 
 3 
 
 1225 
 
 + -229 
 
 
 29 
 
 576 
 
 221s 
 
 59234 
 
 5 
 
 66065 
 
 I 
 
 1190 
 
 -f -115 
 
 
 30 
 
 576 
 
 223B 
 
 43386 
 
 6 
 
 50068 
 
 1 
 
 0760 
 
 + -154 
 
 
 * Showing that Iron Steam Boilers become stronger as the temperature increases, up to 
 about 600, beyond that temperature it becomes weaker. Copper decreases in strength from 
 56 upwards. 
 
39 
 
 TEMPERATURES, FROM TESTS BY THE COMMITTEE OF THE FRANKLIN 
 INSTITUTE. 
 
 ( 212 to 1317 Fah., compared 
 <J tried at ordinary temperatures : 
 (the latter being 163. 
 
 with the strength of each bar when 
 the whole number of experiments at 
 
 
 *i 
 
 gs 
 
 i 
 
 & 
 
 2 
 
 A E2 
 
 O 
 
 a! ^ 
 
 
 g 
 
 If 
 
 ^ * 
 
 
 
 1 
 
 ! 
 
 fiS 
 
 M*S 
 
 
 t 
 
 I! 
 
 o2 
 
 ? 
 
 a 
 
 1 
 
 a 
 
 f 
 
 II 
 l*j 
 
 % 
 
 P<g 
 
 
 fl 
 
 
 
 
 
 * J Js 
 
 o . 
 
 "rt 
 
 *" fc 
 
 rt 
 
 Sj^l 
 
 .sl 
 
 02 
 
 
 
 J3 
 
 ii 
 
 i-.. 
 
 3| 
 
 rt 3 
 
 * 
 
 jjjj 
 
 i 
 
 2'M 
 
 13 'g'a 
 
 a 
 
 =3 
 
 1! 
 
 ^8 
 
 fl 
 
 
 
 | g 
 
 o 
 
 11,! it 
 
 2 
 
 o 
 
 N 
 
 Is'f I 
 
 |l 
 
 o 
 
 
 
 o 
 
 tai 
 
 SCB 
 
 ig PnO 
 
 w 
 
 & 
 
 
 
 ^ 
 
 02 
 
 fc 
 
 
 
 fc 
 
 -< 
 
 M 
 
 M 
 
 31 
 
 577 
 
 164 
 
 58769 
 
 5 
 
 66929 
 
 2 
 
 1214 +'139 
 
 
 32 
 
 578 
 
 224A 
 
 52406 
 
 5 
 
 59197 
 
 1 
 
 0565 +-129 
 
 
 33 
 
 578 
 
 223A 
 
 45757 
 
 5 
 
 53465 
 
 1 
 
 .0896 +-168 
 
 
 34 
 
 580 
 
 86 
 
 62156 
 
 3 
 
 77163 
 
 2 
 
 09861 + '052 
 
 
 35 
 
 590 
 
 220B 
 
 59459 
 
 5 
 
 62966 
 
 1 
 
 0680 
 
 + 058 
 
 
 36 
 
 598 
 
 90 
 
 50316 
 
 5 
 
 57310 
 
 2 
 
 2401 
 
 + 138 
 
 
 37 
 
 38 
 
 630 
 636 
 
 219A 
 16 
 
 59530 
 53543 
 
 4 
 1 
 
 60010 
 50039 
 
 1 
 
 1 
 
 1440 
 1563 
 
 + 008 
 067 
 
 r This experiment was on 
 sa part probably defec- 
 
 39 
 
 662 
 
 150 
 
 59307 
 
 5 
 
 58181 
 
 1 
 
 0644 
 
 019 
 
 (tive. 
 
 40 
 
 722 
 
 152 
 
 57133 
 
 3 
 
 54441 
 
 1 
 
 0507 
 
 047 
 
 
 41 
 
 732 
 
 14 
 
 52542 
 
 1 
 
 53378 
 
 1 
 
 1310 
 
 + 016 
 
 
 42 
 
 734 
 
 150 
 
 59397 
 
 1 
 
 57903 
 
 1 
 
 0644 
 
 026 
 
 
 43 
 
 766 
 
 16 
 
 56891 
 
 1 
 
 54819 
 
 1 
 
 1563 
 
 037 
 
 
 44 
 
 770 
 
 149 
 
 56825 
 
 2 
 
 54781 
 
 1 
 
 0234 
 
 036 
 
 
 
 [824 
 
 
 
 
 
 
 
 
 
 45 
 
 \ and 
 
 214 
 
 59219 
 
 1 
 
 55892 
 
 I 
 
 0413 
 
 073 
 
 
 
 (S14 
 
 
 
 
 
 
 
 
 
 46 
 
 825 
 
 149 
 
 56825 
 
 2 
 
 56644 
 
 1 
 
 0234 
 
 029 
 
 
 47 
 
 932 
 
 214 
 
 59219 
 
 1 
 
 45531 
 
 1 
 
 0413 
 
 240 
 
 
 48 
 
 947 
 
 232 
 
 58341 
 
 2 
 
 42401 
 
 1 
 
 0446 
 
 273 
 
 
 49 
 
 1022 
 
 214 
 
 59219 
 
 2 
 
 37410 
 
 1 
 
 0413 
 
 369 
 
 
 50 
 
 1037 
 
 152 
 
 58992 
 
 1 
 
 37764 
 
 1 
 
 0507 
 
 360 
 
 
 51 
 
 1097 
 
 227 
 
 53426 
 
 6 
 
 27604 
 
 1 
 
 0330 
 
 483 
 
 
 52 
 
 1111 
 
 227 
 
 53426 
 
 6 
 
 27602 
 
 1 
 
 0330 
 
 483 
 
 {The metal was decidedly 
 
 53 
 
 1142 
 
 226 
 
 54758 
 
 2 
 
 18672 
 
 1 
 
 1147 
 
 659 
 
 defective at the point 
 where this fracture was 
 
 
 
 
 
 
 
 
 
 
 made flaws visible. 
 
 54 
 
 1155 
 
 227 
 
 53426 
 
 6 
 
 21967 
 
 1 
 
 0330 
 
 589 
 
 
 
 
 
 
 
 
 
 
 
 f The 8th experiment on 
 
 55 
 
 56 
 
 1159 
 1187 
 
 229 
 227 
 
 55774 
 53426 
 
 3 
 6 
 
 25620 
 21910 
 
 1 
 
 1 
 
 1102 
 0330 
 
 5Q ) this bar being taken as 
 } the standard, would ex- 
 '589 Chibit the effect '550, 
 
 57 
 
 1235 
 
 226 
 
 54758 
 
 2 
 
 21298 
 
 I 
 
 1147 
 
 611 
 
 
 58 
 
 1245 
 
 226 
 
 54758 
 
 2 
 
 20703 
 
 1 
 
 1147 
 
 622 
 
 
 59 
 
 1317 
 
 226 
 
 54758 
 
 2 
 
 18913 
 
 1 
 
 1147 
 
 654 
 
 
 Mean 57525 
 
CHAPTER II. 
 
 THE FURNACE AND ITS ADJUNCTS. 
 
 AFTER seeing that all the fittings of the Boiler are in the best possible 
 order, and the Boiler in good working condition, turn attention to the 
 Furnace. There is more required here than the simple process of feeding 
 the fire with fuel. In the first place, the nature of the coal should be 
 ascertained whether or no it be of a coking description. If it be, the 
 grate bars will require to be more open than for coal of a light and 
 gaseous nature. Adjust the grate-surface to the heating or absorbing 
 surface of the Boiler. This will greatly depend upon the quality of the 
 fuel and the draught, and the quantity of steam required. If the 
 draught be good, work a thick fire ; but do not break the coal except it 
 cannot be got in at the Furnace door, taking care to feed the Furnace on 
 one side, not covering more than one half the grate at a time. When 
 that is sufficiently coked, feed the other side, putting plenty on at a time, 
 leaving the middle of the Furnace much lighter and thinner of fuel than 
 the sides, and keeping the grate bars well open. This mode of stoking 
 placing the coal on one side at a time will prevent the formation of a 
 great portion of the smoke which would otherwise result, and also pro- 
 duce a more steady heat. The coal so placed will partially damp that 
 side of the Furnace on which it is placed : therefore the necessity of 
 stoking the Furnace when the steam is up. From this method of firing, 
 the gas generated will be given out slowly. The greatest quantity of air 
 will pass through that portion of the grate where the fuel is most con- 
 sumed, and where the coal has not been made small by breaking, leaving 
 the interstices wide ; and as the oxygen of the air will generally be in suffi- 
 cient quantity, if this mode of firing be adopted, to unite with the gas as 
 it is extracted from the coal, a continuous flame will be kept up, and 
 smoke prevented. When one side of the Furnace so fired is sufficiently 
 coked, raise the burning fuel gently with the poker, but do not break it 
 into pieces. At the next firing, place the coal on the other side of the 
 Furnace, and similar results will follow. Replenish first one side, and 
 then the other : and continue to do so in the working of the Furnace. 
 Keep the Furnace door open no longer than is absolutely necessary, and 
 thus prevent the admission of large volumes of cold air to cool the Boiler 
 and flues. Place your coal, before firing, near to the Furnace, that there 
 
41 
 
 may be no loss of time in charging the fire. Cold air coming in 
 contact with the Boiler lets down the temperature, and does harm. To 
 ensure that the coals be sufficiently near, and that the Stoker cannot 
 have them too far from the Furnace doors, it is best to erect a barrier in 
 front of the Boiler, at about six feet distance, with an opening at the 
 bottom. The coals behind this barrier will have to be up to the opening 
 at the bottom. This mode will enable the Stoker to charge his Furnace 
 with fuel without moving from the front. He will thereby take less 
 time, and ,be able to close the door earlier, than if he followed the 
 ordinary modes of stoking. 
 
 Diagram No. 12. 
 
 If the Engineer is working a Double Fire-box Boiler, let him fire each 
 Furnace alternately, in the manner above described, and as illustrated by 
 the accompanying engraving, Diagram No. 12, where A and B represent 
 the sides of the fires last stoked, with the gas given out from the new 
 fuel, mixing with the air which passes in the greatest quantity through 
 the thin portion of the fire, as indicated by the arrows : and with that 
 also which passes through the apertures in the furnace doors, or through 
 
42 
 
 any special provision that may be made. Being thus mixed with air at 
 a high temperature, the gases ignite, and comparatively thorough com- 
 bustion is secured, preventing smoke and saving fuel. This mode of 
 firing is applicable to most Furnaces, whether single or double fire-box, 
 or with the fire wholly beneath the Boiler. The hotter the fire, the more 
 steam will there be generated with the same quantity of fuel ; and though 
 a greater amount of heat may pass up the chimney, there will be a cor- 
 responding saving of fuel, in proportion to the increase of temperature. 
 
 There are various qualities of coal, and various power of draughts. A 
 good quality of coal, with a good draught, will evaporate Tibs of water 
 for each lib of coal, in a Double Fire-box Boiler ; and other qualities not 
 so good, from 51bs to Tibs. In a trial at Newcastle-upon-Tyne, the 
 Author evaporated ll.TOSbs of water with lib of coal, without any smoke 
 being evolved. The experiment was made with a Marine Boiler, with 
 multitubular flues. The temperature in the chimney varied from 500 to 
 650 ; and it was found that as the temperature of the Furnace was 
 increased, the heat in the chimney also increased : but steam was gene- 
 rated much quicker, and less fuel was proportionately consumed. 
 
 If the coal be of a light gaseous description, burning to white ashes, 
 work the Furnace in the manner above described, with the bars a little 
 closer together. Where there is a bad draught, the Furnace will require 
 working differently placing a little coal on at each time of firing, equally 
 over the grate. But this mode of firing is, generally speaking, not an 
 economical one. Much, however, depends on the nature and quality of 
 the coal for there are some descriptions which will not fire in any other 
 manner. By this latter mode of firing, the gas is extracted from the fuel 
 quicker than the oxygen passes through the grate to consume it. In that 
 case a great portion of the fuel passes up the chimney in the form of 
 smoke ; and the Furnace door having to be often opened to replenish the 
 fire, admits large quantities of cold air, which cools the Furnace and the 
 flues, besides contracting the Boiler an evil somewhat modified by 
 partially closing the damper when firing. A dirty Furnace will have a 
 similar effect in creating smoke. If the grate be covered with clinkers or 
 rubbish, the oxygen is prevented from entering, and the fuel is converted 
 into smoke. In fact, this is one of the most prolific sources of the 
 " smoke nuisance." 
 
 By all means avoid having a dirty ashpit. A pit nearly full of ashes 
 is a sure sign of bad management. It is as necessary to keep the ash-pit 
 of a Furnace clean and cool, and the air as dense as possible, as it is to 
 feed the fire with fuel. If the ash-pit be hot, the heat expands the air, 
 and the Furnace will require greater quantities to pass for the amount of 
 oxygen which would be supplied by less quantities of cold air. These 
 
43 
 
 greater quantities impair the draught. When convenient, use water for 
 the bottom of the ashpit, allowing it to remain to quench the ashes as 
 they fall from the Furnace. The evaporation will tend to keep the 
 grate cool. Have, if possible, some water near the Furnace, so that 
 when cleansing the fire you can cool the slag, that you may remove it 
 early. These things, properly attended to, will cause the Furnace to 
 wear much longer, and also save fuel. There will likewise be less 
 labour to produce more steam in the same time than a slovenly mode 
 of stoking would produce. 
 
 A great body of fire will evaporate more water with a less proportion 
 of fuel than a small and thin fire. The greater the intensity of the fire, 
 the more will be the steam generated with the same amount of fuel. 
 Where there are a number of Boilers, it is important that the duty of 
 stoking should be properly attended to ; and as smoke is a great nuisance, 
 easily prevented, its prevention is a duty which every Engineer ought to 
 attend to. 
 
 Diagram No. 13. 
 
 With regard to the consumption of smoke, it may be observed that 
 the heat of one fire coming into contact with the gases of another fire 
 behind the bridge, or in what is called the " combustion chamber," does 
 not consume the smoke. Smoke cannot be consumed after it has left the 
 Furnace, unless air be admitted to mix and ignite with it, and the gas 
 must also be of sufficient temperature to cause ignition. The best part of 
 the Furnace in which to admit air to ignite the gas, is near to where the 
 gas is generated. If additional air be required to that which passes 
 through the grate and Furnace-door, it is best admitted at the bottom of 
 the Furnace-door, or through the dead-plate, as illustrated by Diagram 
 No. 13, which represents a dead-plate pierced with apertures for the 
 admission of air through and amongst the coking coal. This method of 
 admitting air has been much resorted to since the first edition of the work 
 in which it was described and made public, first appeared.* This method 
 is recommended by the " Lancashire Association for the Prevention of 
 Boiler explosions /' and the Author, having had more than twenty years' 
 experience with all and every kind of smoke-prevention apparatus, is able 
 
 * " The Steam Engine Explained by the use of the Indicator," by Joseph Hopkinson. 
 
44 
 
 to say that he never found anything to answer so effectually as the mode 
 of firing before described and illustrated, in combination with this mode of 
 admitting air at the Furnace-door or through the dead-plate, when the 
 requisite amount cannot be got through the ordinary grate. 
 
 All Furnace-doors should have a number of half-inch holes cast or 
 drilled through, independent of all other contrivances. The air passing 
 through these holes into the Furnace keeps the doors cool, and assists 
 combustion. 
 
 The annexed Diagram, No. 1 4, is a representation of a grate bar, and 
 bearers. The bar C shows one end hooked on to the left hand bearer B. 
 The other end of the bar slopes, and rests upon the other or right-hand 
 bearer B. As the bar expands or contracts, the sloping end, being 
 loose, can^move without straining, or buckling the bar. With this free 
 action, the grate will last much longer than ordinarily, and the openings 
 can be kept more even. 
 
 Diagram No. 14. 
 
 B 
 
 The form of the Furnace bridge is also of importance. If it be made 
 inclined, as shown by Diagrams No. 9 and 10, it will last much longer, 
 and the heat will be more evenly distributed in the Furnace, to the increase 
 of the evaporating power. When the Furnace is cleansed, the hot fire can be 
 pushed up the incline, while the clinkers are removed : thus enabling the 
 stoker to clean the whole of the grate at one time. And, besides this, the 
 reflected heat of the hot brick-work will impinge against the top part of 
 the fire-box flue, or the bottom of the Boiler, if of another construction ; 
 thus keeping the Furnace-door much cooler than when the bridge is built 
 perpendicularly the reflected heat in the latter case impinging on the 
 front, causing that part to be much hotter than where the bridge is 
 inclined, as here described. 
 
 The opening between the grate-bars is an important point to be 
 attended to. If these are not sufficiently wide, the Furnace becomes a 
 retort for the destructive distillation of coal, th gases passing off in the 
 form of smoke for want of a sufficient quantity of air to consume them 
 as they are generated. Smoke is often produced from the bars being too 
 close together ; and it is false economy to suppose that fuel is saved by 
 having the apertures between the grate-bars too small. A proper thick- 
 ness of the bars, also, is a requisite in practice. These have been found 
 to answer best when about one-half or three-quarters of an inch thick. 
 
Attention to the foregoing rules, viz : careful firing, clean grates, 
 wetting the small coal, placing plenty on at a time, firing alternately at 
 the sides, a clean ash-pit, and, above all, a good draught, will, for all 
 practical purposes, prevent the formation of smoke. That attention will 
 also prevent waste of fuel, save time and labour, and reduce wear 
 and tear. Of course, under different circumstances, modifications will be 
 required, varying accordingly; but by the adoption of the principles 
 herein laid down, the " smoke nuisance " would soon cease to be a cause 
 of complaint. 
 
 The following Table of the evaporative powers of various descriptions 
 of coal when burned under Boilers, is given by Mr. Wicksteed : 
 
 TABLE OF THE COMPARATIVE EVAPORATIVE POWERS OP DIFFERENT 
 KINDS OF COAL. 
 
 No. 
 
 Description of Coal. 
 
 Water 
 evaporated 
 per ft of 
 Coals. 
 
 Compara- 
 tive Cost 
 per Ton in 
 London. 
 
 1 
 
 The best Welsh 
 
 Ibs. 
 9"403 
 
 s. d. 
 17 11 
 
 2 
 
 
 9'014 
 
 17 
 
 3 
 4 
 5 
 
 The best small Newcastle 
 Average small Newcastle 
 
 8-524 
 8-074 
 8-045 
 
 16 1 
 15 2| 
 1 " 9i 
 
 6 
 7 
 8 
 9 
 10 
 11 
 
 Coke from gas-works 
 Coke and Newcastle, small ^ and 
 Welsh and Newcastle, mixed | and | 
 Derbyshire and small Newcastle, 4 and ^ 
 Average large Newcastle 
 
 7-908 
 7-897 
 7-865 
 7-710 
 7-658 
 6-772 
 
 1O 6% 
 
 14 11 
 14 lOf 
 14 10 
 14 61 
 14 51 
 12 91 
 
 12 
 
 Blythe Main, Northumberland 
 
 6-600 
 
 12 5i 
 
 The Author evaporated ll'TOIbs of water in a Marine Boiler, with 
 15) of the best Newcastle coal, when contesting for the ,500 prize 
 offered by the Newcastle Coal Owners' Association some years ago, for 
 the best smoke preventive ; and he further offered to evaporate 12'70Bbs 
 of water with lib of coal, provided the Furnace were altered as he 
 might direct. 
 
 With good Lancashire or Yorkshire coal, and a Double Fire-box Boiler, 
 new, and a moderate draught, 7tt>s of water can be evaporated with lib 
 of Coal. When the Boiler has been some years at work, the evaporation 
 will vary from 5Bbs to 75>s the work greatly depending upon the state 
 of the flues and the cleanliness of the Boiler-plates, inside and outside. 
 Inferior coal will not evaporate more than from 4Ibs to 51bs of water 
 with IK) of coal. The strength of the draught has a good deal to do 
 with the economy of fuel : the stronger the draught, and the greater the 
 evaporative power of the coal. The greater the intensity of the fire, 
 the more completely are the gases consumed. 
 
CHAPTER III. 
 
 THE ENGINE. 
 
 THE Engine itself requires but little attention when in good order, except 
 the ordinary routine of packing, cleaning, and oiling the working parts, 
 and occasionally adjusting the cotters, which on no account ought to be 
 neglected. 
 
 Indicate the Engine every day. Perform the operation when the load 
 is on. Work up the diagram, and place it in a book, with the date, for 
 reference at any future time. This mode will denote the difference of 
 power required under different circumstances, and also make known any 
 defective working, whenever any part of the Engine gets out of order, or 
 whenever any shafting or machinery is taking more power at one time 
 than another. 
 
 It will not be necessary to work up the diagram each time. When the 
 Indicated Horse-power has been once ascertained, the following rule will 
 be found to be correct enough for all practical purposes, and much more 
 ready than working the diagram each time thoroughly out. 
 
 EXAMPLE: 
 
 Say the Diagram represents 99 horse power, when the friction of the 
 Engine and shafting is deducted. 
 
 Divide by the average pressure, 
 
 say...l2fos ) 99 ( 8fts horse power for each pound pressure per 
 96 square inch upon the piston. 
 
 3 remains ; this being ^ of 12, it makes the total to 
 be 8^ horse power. 
 
 If a diagram be taken from the same Engine, with less, or more, 
 average pressure, multiply the average pressure upon the piston by 8 '25, 
 to ascertain the horse power the Engine is then exerting. 
 
 EXAMPLE : 
 
 1 5K>s the pressure upon the piston. 
 8'25 the number of horse power for each 
 
 pound pressure upon the piston. 
 75 
 30 
 120 
 
 12375 horse power. 
 
47 
 
 The horse power being 123JBbs. It matters not whether the horse- 
 power be required independent of the shafting and Engine, the calcula- 
 tions are made the same. Each Engine indicated will require the first 
 diagram taken to be figured up, and worked out in the ordinary way, 
 hereinafter described, to ascertain the horse power the Engine is turning. 
 
 Diagram No. 15. 
 
 Use a thermometer to test the temperature of the condensing water, 
 which ought not to exceed 120 degrees of Fahrenheit. Work as much 
 below that temperature as is consistent with the supply of water to the 
 
48 
 
 Boiler, and the quantity the air-pump will discharge keeping the 
 delivering- valve closed as long as possible. If the water in the air-puinp 
 thump and plunge, a small air-pipe inserted in the" pump lid will often 
 prove to be a remedy. 
 
 Should the rose of the pump become choked, or stopped with dirt or 
 leaves, as is often the case when water is drawn from rivers, pools, dams, 
 streams, and even wells, the foregoing sketch of a pump-head, tail- 
 pipe, and rose, illustrates a mode of clearing the rose without stopping 
 the pump, or getting down to the rose. Insert a small pipe and tap 
 under the low valve, or " clack," of the pump the pipe end being open 
 to the atmosphere. When the pump is working, the tap will be closed, 
 of course. By opening the tap, the pressure of the atmosphere will act 
 upon the column of water in the tail-pipe of the pump, betwixt the low 
 " clack " and the rose. The water in the tail-pipe will rush back with a 
 force proportionate to the column, and force away the accumulations, as 
 shown by Diagram No. 15. If the pump be not placed much higher 
 than the rose, the column will be short, and have very little force to 
 drive off the debris. In that case the pipe above the tap should be 
 carried to an elevated cistern, containing water. Then, when the tap is 
 opened, the rush of water will clear the rose. In performing these 
 operations, no stoppage will be required. The attendant has simply to 
 open the tap for a short time, while the water descends, and then close 
 it again. This little simple apparatus is calculated to save much time 
 and trouble ; for in some rivers the covering of the rose by refuse matter 
 is a great annoyance, which, under the old method of clearing, involves 
 a waste of time and labour. 
 
 Unsteady working of the Engine is sometimes caused by the connec- 
 tions between the governor and the throttle-valve being too weak ; in that 
 case the parts spring and give way, and vibration is the consequence. 
 When the throttle- valve is too large, a similar effect is produced ; and this 
 is often the cause of Engines working unsteadily. Throttle-valves regu- 
 lated by pumps, vary with the pressure of the atmosphere ; for the 
 water is " high " or " low," in accordance with the varying pressure. 
 
 Should the crank-pin, or the bearings of the fly-wheel shaft, or any 
 of the other parts become hot, particular attention is required to prevent 
 their destruction. Lead filings mixed with oil will be found to be 
 useful. The lead coats the bearings, and interposes another body between 
 the rubbing surfaces. Sulphur mixed with oil has also a similar effect ; 
 and quicksilver may be said to be better than either. 
 
 The following recipe for cooling necks of shafts will be found useful, 
 not only for the crank shaft, but for all other descriptions of shafting 
 particularly the feet of upright shafting : 
 
49 
 
 ] Gibs of Tallow, dissolved in a vessel. 2fts of white Sugar of Lead. When the 
 Tallow is melted, but not boiling, put in the Sugar of Lead, and let it be dissolved. 
 Then put in 3B>3 of black Antimony. Keep stirring the whole mass till cold. 
 
 It is an axiom that " prevention is better than cure." There would 
 seldom be heating of necks of shafting, were those necks made of a 
 proper length. They should, in all cases, be at least twice the length of 
 the diameter of the shaft. The "brasses," or "steps," should be made of 
 good metal, composed of three parts of copper to one part of tin. Good 
 brasses involve more " first cost," but they secure a saving of oil, and also 
 power. More attention than is now usual ought to be paid to the 
 quality of the metal of which " steps," or the bearings of shafting, are 
 made. Above all, be careful to keep dust away from the necks and 
 " brasses" of shafting, and other bearers : for cleanliness in this particular 
 is a great preventive of destruction. 
 
 Pay proper attention to all packings, to prevent the escape of steam or 
 water. Such leakages often cause more destruction than ordinary wear 
 and tear. If the injection cock or the condenser be leaky, the water will 
 get into the cylinder when the Engine is standing, in consequence of the 
 partial vacuum ; and at starting afterwards, the water will, in all proba- 
 bility, be the means of breaking the beam or some other part. Care 
 should be taken that all taps connected with the cylinder are closed when 
 the Engine is at rest, except a small tap connected to the condenser ; and 
 whenever the Engine is stopped, this tap should be opened to destroy the 
 vacuum, or the water may, from some cause, get into the cylinder. At 
 starting the Engine, close the tap. This simple arrangement will be the 
 means of saving much trouble, and probably prevent breaks-down. This 
 tap will also be found useful in stopping the Engine at any required 
 angle of the crank, by admitting air to the condenser, and destroying 
 the vacuum. 
 
 Keep the pipes and cylinders clothed with a non-conducting substance, 
 to prevent the escape of caloric from the steam. It will pass away very 
 quickly, if means are not used to retain it causing a loss of fuel. 
 
 Have a vacuum-gauge fixed near to where you pass in the Engine- 
 house, that the quality of the vacuum in the condenser, or the amount 
 of the uncondensed steam, may be easily examined. The vacuum-gauge 
 should be one that shows the pressure of the uncondensed steam left in 
 the cylinder, and the pressure of the atmosphere at the same time. 
 Otherwise it cannot be ascertained by the Indicator, when the vacuum 
 varies, whether it be from the pressure of the atmosphere or the deficient 
 vacuum of the Engine. In some states of the weather the pressure of 
 the atmosphere will be under 1 4Ibs to the square inch, and at other times 
 it will be upwards of 15R>s to the square inch. Steam may be 2( 
 
50 
 
 above the atmosphere ; but when the pressure of the latter is 141fos, the 
 steam will be 341bs. But if the pressure of the atmosphere be lolbs to 
 the square inch, the steam in the Boiler will be '351bs ; and so on in 
 proportion to the varying pressures of the surrounding medium. 
 
 Have proper taps fitted to the top and bottom of your cylinder, that 
 you may indicate your Engine with ease. By indicating each end, you 
 will see if your valves are equally set. Both ends can be indicated on 
 one paper. After using the Indicator, clean it well : a dirty Indicator 
 is an indication of a slovenly Engineer. 
 
 WHAT IS THE VACUUM OF A STEAM ENGINE ? 
 
 IT is essential that we define and understand the term " VACUUM," as 
 commonly applied to the Steam Engine (and unless this be well under- 
 stood by the Engineer, he cannot clearly understand the Condensing 
 Engine) before we enter into a description of the diagrams which are 
 hereafter given. The following popular explanation is therefore attempted. 
 
 Steam is an invisible fluid. When steam, as it is called, is seen like 
 white smoke, it is not steam, but minute particles of water. Pure steam 
 in a glass will not show at all but the vessel appears to be filled with air 
 only. One cubic inch of water converted into steam at the atmospheric 
 pressure of 155)8, the temperature 212, will expand to 1700 cubic 
 inches of steam. If the temperature be increased, the pressure will be 
 increased also in the ratio of the temperature. Thus, with steam at 251 J 
 degrees, the pressure will be 15Bbs above atmospheric pressure ; the total 
 pressure, 305>s to the square inch, and the bulk 883 times greater than 
 the bulk of the water from which the steam was produced. If the total 
 pressure be COBbs, or 451>s on the steam gauge, the bulk will be 470 
 times greater than the water the steam had been produced from. In 
 proportion to the increase of pressure, so is the density.* 
 
 The literal meaning of the term " vacuum," is space unoccupied by 
 matter. The cylinder of a Steam Engine filled with steam, though 
 vaporised from a small quantity of water, cannot be said to be void of 
 matter ; but condense that steam to its original bulk into water, and 
 withdraw this water from the cylinder, and the space formerly occupied 
 by the steam will be unoccupied. No matter remaining in the cylinder, 
 there is what is termed a " vacuum," or a void space. We have supposed 
 this operation to have taken place under the piston of a Steam Engine, 
 and in that case there is no resistance to be overcome in the descent of 
 
 See the Table hereafter given, shewing the " Temperature of Steam at different pressures." 
 
51 
 
 the piston. The pressure of the atmosphere alone, which is 1 55>s to the 
 square inch, or thereabouts, would suffice to force the piston down with 
 a power equal to the degree of vacuum formed, up to the limit stated 
 151bs, if the vacuum be perfect. On this principle the first Steam and 
 Atmospheric Engine was constructed : a cylinder with its upper end open 
 to the atmosphere ; steam was admitted below the piston to raise it, and 
 this steam being condensed in the cylinder itself by the application of cold 
 water, the pressure of the atmosphere alone caused the downward stroke 
 in the manner above described. If steam be allowed to take the place of 
 the atmosphere, as in WATT'S Engine, steam at atmospheric pressure will 
 produce the same effect. 1700 cubic inches of steam, or one cubic inch 
 of water converted into steam at atmospheric pressure, will have a force 
 sufficient to raise a weight of one ton one foot high ; two cubic inches of 
 water, two tons ; and each ton extra, one additional inch of water con- 
 verted into steam. One of WATT'S first improvements was to attach to 
 the Steam Engine a second vessel, in which to condense the steam. This 
 he called a " condenser." He also introduced other alterations by which 
 the vacuum was much improved, and the steam made to answer two 
 purposes. First, by closing the cylinder with a cover, and admitting the 
 steam between the cover and the piston, and connecting each side of the 
 piston with the second vessel, or condenser the condenser being supplied 
 with cold water the steam was admitted at the same time by valves 
 opening and closing at each stroke of the Engine. The steam was thus 
 condensed, and a partial vacuum formed ; and thus the power of steam 
 at a pressure above the atmosphere was made available, in addition to the 
 pressure of steam below the atmosphere. By admitting the steam alter- 
 nately on each side of the piston, after a partial vacuum had been formed 
 in the second vessel, or condenser, and the Engine cylinder, the Engine 
 was thereby made to be double-acting, and its power increased in propor- 
 tion to the pressure of the steam above the pressure of the atmosphere. 
 
 Steam arising from an open vessel for instance, from the manhole of 
 a Steam Boiler has a force greater than the pressure of the atmosphere, 
 inasmuch as it has to displace the atmosphere before it can rise above the 
 surface of the water. The resistance of the atmosphere is equal to about 
 151bs on the square inch. It varies from 13 Jibs to upwards of 151bs ; 
 on the average it is about 14 Jibs to the square inch. 2'037 inches of a 
 column of mercury balances lib pressure to the square inch. Therefore, 
 steam enclosed in a Steam Boiler at 51bs pressure per square inch above 
 the atmosphere, or, in other words, at 51bs on the steam gauge, is, in 
 reality, a pressure of 201bs on the square inch, as applied to the piston of 
 a Steam Engine under the conditions above stated taking the pressure of 
 the atmosphere at 151bs. If the pressure be less, as it often is, say 141bs 
 
52 
 
 then the pressure upon the piston would be 191bs, because the resistance 
 of the atmosphere on the safety-valve and steam-gauge would be less, and 
 the steam in the Boiler also less, in proportion to the reduced pressure of 
 the atmosphere. Hence it arises that an Engine heavily loaded varies 
 in its speed with the varying pressure of the atmosphere. Suppose 
 that the vacuum is not perfect and in practice it never is so and 
 that there remains in the cylinder a portion of uncondensed steam, 
 the resistance of which is equal to 31bs to the square inch, then 
 the steam on the upper side of the piston at 51bs to the square 
 inch above the pressure of the atmosphere, would act with an effective 
 force of 171bs upon the square inch : the upper side of the piston having 
 exerted upon it a pressure equal to 201bs to the square inch, and the 
 under side a pressure, or resistance, equal to 31bs to the square inch. 
 Under these circumstances, the condenser will have exhausted steam from 
 the cylinder equal to 121bs to the square inch, commonly termed a 121bs 
 vacuum ; and uncondensed steam will have been left in the cylinder, 
 having a resisting force equal to 31bs to the square inch. In proportion 
 to the quantity of steam condensed to the whole, so is the value or 
 available pressure upon the piston. If the uncondensed steam left in the 
 cylinder were equal to Gibs to the square inch, then, in the other circum- 
 stances supposed, the available pressure upon the piston would be 
 only 141bs to the square inch a proof that vacuum is not power, as 
 many are led to suppose. All power in the Steam Engine is derived from 
 the pressure of the steam upon the piston. If there be no resistance on 
 the other side of the piston, the whole pressure is available ; when there 
 is resistance, whatever be the amount, it has to be deducted. The avail- 
 able power of steam on the piston is what is left of the whole force 
 when that deduction is made. The term " suction " is often used. There 
 is no such process in nature, or in mechanics ; and the use of the term 
 only tends to confound the practical worker. All power derived from air, 
 steam, or gas, is the result of pressure, or density ; and in proportion to 
 the pressure, so is the power. 
 
 If 51)s more pressure to the square inch be added to the 55bs before 
 described, the pressure of the steam above the atmosphere will be lOBbs 
 to the square inch, making only 25Ibs as the available pressure. Many 
 suppose that by doubling the pressure above the atmosphere, or double 
 the pressure on the steam gauge, they double the power of the steam, 
 and that they also double the power of the Engine. Such is not the 
 case. They have only, in the case last supposed though the pressure 
 of steam in the Boiler above the atmosphere is doubled added 5ft>s to 
 the 20R>s already available. This only gives 25K>s to the square inch 
 upon the piston of the Engine, in place of 201hs. The increased power 
 
53 
 
 of the Engine is as 25 is to 20, supposing the non-resistance, or in other 
 words, the vacuum, to be the same. In the practical working of Engines, 
 it is seldom that the full pressure in the Boiler can be brought to bear 
 upon the piston. To ascertain the real pressure operating on the piston 
 at any given time, the Indicator has to be resorted to, in the manner 
 hereinafter explained. 
 
 These examples have reference only to Condensing Engines. High- 
 pressure, or Non-condensing Engines, are constructed upon a different 
 principle. In them, the power of the Engine is as the pressure of the 
 steam above atmospheric pressure. Steam at SOEbs to the square inch 
 above the atmosphere, that is SOIbs on the steam gauge, applied to the 
 piston of a High-pressure or Non-condensing Engine, will exert a force 
 equal to the pressure in the Boiler above the atmosphere, providing there 
 be sufficient room in the passages betwixt the cylinder and the Boiler, so 
 that obstructions in the steam course do not reduce the pressure before 
 entering the cylinder the other side of the piston being open to the 
 atmosphere, and the steam only having to overcome the atmospheric pres- 
 sure in its escape from the cylinder, loflbs from the total pressure of 
 4ott>s is lost, provided the steam has been expanded in the cylinder to its 
 full limit, which is not often the case in practice. If not expanded, the 
 loss will be greater ; it will be in proportion to the pressure of the steam 
 on the piston above the atmosphere at the termination of the stroke. If 
 we double the pressure in the case just supposed, and bring the whole 
 to bear upon the piston, and expand the steam to atmospheric 
 pressure, the power of the Engine will not be doubled, but will be as 52 
 is to 31; because the pressure of the atmosphere added to 60 makes 75, 
 not twice 45, which would be 90. Where a partial vacuum is formed, 
 as in the Condensing Engine, steam at SOIbs to the square inch above 
 the atmospheric pressure would press with a force equal to 421bs per 
 square inch, supposing the resistance of the uncondensed steam to be 
 only equal to 3ft>s to the square inch. As before observed, the one side 
 of a piston of a High-pressure Engine is open to the atmosphere through 
 the exhaust pipe, when the steam is exerting its force on the other side ; 
 and as the resistance of the atmosphere is 151bs to the square inch, it 
 follows that the power of the steam is as its own pressure above the 
 atmosphere : or in other words, the pressure above the atmosphere is the 
 available power obtained in the High-pressure or Non-condensing Engine, 
 when the full pressure in the Boiler is brought upon the piston. 
 
 The steam upon the piston of some Condensing Engines, is, at one portion 
 of its stroke, below the atmospheric pressure. The pressure of the steam 
 upon the piston at the commencement of the stroke or descent of the piston, 
 is for one-seventh the length of the cylinder, equal to 321bs to the square 
 
54: 
 
 inch, or 1 Tibs to the square inch above the pressure of the atmosphere. 
 The valve is then closed, and the communication with the Boiler cut off 
 and the steam in the cylinder is expanded for the remainder of the stroke, 
 decreasing as the piston approaches nearer and nearer to the end of the 
 cylinder. Suppose the grease tap in the cylinder to remain open during 
 the whole length of the stroke, the steam will rush out in proportion to 
 its own pressure above the atmosphere, until the pressure is equalised. 
 As the piston descends, the pressure of steam is reduced, by expansion, 
 until it gets below the pressure of the atmosphere ; and then the atmo- 
 sphere will rush into the cylinder. At the same time the cylinder will 
 be full of steam. After crossing the atmospheric line, the steam is not 
 equal to the resistance, or the power of the surrounding medium ; 
 therefore, at one portion of the descent of the piston the steam will rush 
 out, displacing the air for a certain distance of the stroke from the top 
 of the cylinder ; and at the other portion of the stroke, or of the piston's 
 descent, the air will rush into the cylinder, when the steam is below the 
 pressure of the atmosphere, and will exert a force upon the piston equal 
 to the difference in pressure between the steam and the air, because the 
 pressure of the steam in the cylinder has been reduced by expansion 
 below the pressure of the atmosphere ; but when steam below the pres- 
 sure of the atmosphere is admitted into the cylinder at the commence- 
 ment of the stroke, the air will rush into the cylinder at the time the 
 steam from the Boiler is admitted, if the grease-tap be kept open from 
 the commencement of the stroke to the end ; thus showing the Engine 
 to be working with steam at a less pressure than steam from an open 
 vessel ; or in other words, steam below the pressure of the atmosphere. 
 Were the openings sufficiently large to admit a sufficient quantity of air, 
 no steam could enter the cylinder against the superior pressure of the 
 atmosphere. If the steam in the Boiler were below the pressure of the 
 atmosphere, the Boiler would soon be filled with air. 
 
 When steam at a pressure above the atmosphere is admitted into the 
 cylinder, and kept up to the end of the stroke, the steam would rush 
 out of the grease-tap, were it open the whole length of the stroke 
 because the steam in the cylinder has not been reduced by expansion, 
 but has to be condensed in the condenser by an extra quantity of water ; 
 thus giving the air-pump more work to do, and losing a quantity of 
 steam in proportion to the pressure. If the steam be reduced to the 
 lowest practical working pressure by expansion, the most has been made 
 of it ; but if not expanded to its full limit, the loss will be in proportion 
 to the amount of pressure left in thejeylinder previous to condensation 
 or the exhaustion into the atmosphere, if a High-pressure Engine. 
 
 In a Steam Engine not heavily loaded, working with steam below the 
 
55 
 
 pressure of the atmosphere from the Boiler and in the cylinder, were the 
 Safety-valve lifted from its seat, air would rush into the Boiler, until the 
 pressure became equal to the pressure of the atmosphere. Thus, air and 
 steam would rush into the cylinder of the Engine with a force equal to 
 the pressure of the atmosphere. As air cannot be condensed, like steam, 
 the vacuum would be destroyed, and there would consequently be an 
 equal pressure on each side of the piston. The result in such case, 
 would be a stoppage of the Engine. 
 
 EXPANSION OF STEAM. 
 
 EXPANSION of steam takes place when the communication with the 
 Boiler is cut off from the cylinder of the Engine, after the piston has 
 travelled a portion of its stroke. The steam thus enclosed betwixt the 
 piston and top (or bottom) of the cylinder, forces the piston forward to 
 the end of the stroke. Supposing the valve to have closed when the 
 piston had travelled one-fourth the length of the cylinder, and its pressure 
 at that time to be 201bs above atmosphere on each square inch, or 351bs 
 the total pressure per square inch upon the piston, it would begin to 
 decrease in pressure as the piston were forced forward, till the piston 
 reached the end of the stroke, when the pressure would be 8|lbs 
 per square inch. For one-fourth the length of the cylinder, the pressure 
 would be 351bs per square inch ; that is, while the communication 
 between the Boiler and the face of the piston remained open. This 
 communication being closed at that point, the steam would begin to 
 expand, forcing the piston forward. When the latter arrived at half 
 stroke, or at the half length of the cylinder, the pressure would be 17Jlbs 
 upon the square inch ; when it arrrived at three-fourths the length of 
 the cylinder, the pressure upon it would be 12|lbs per square inch ; and 
 at the end of the stroke the pressure would be 8Jlbs per square inch, or 
 6Jlbs per square inch below the pressure of the atmosphere the steam 
 having gradually expanded during the traverse of the piston, from 351bs 
 at the commencement and up to one-fourth of that traverse, down to 
 8 fibs at the termination of the stroke leaving only the latter amount of 
 steam to be condensed. 
 
 Expansion is, perhaps, the most extraordinary property of steam. The 
 merit of the discovery is due to HORNBLOWEK, who, in 1781, obtained 
 a patent for the invention. He states that when steam is confined on 
 one side of a piston, and a partial 1 vacuum is formed on the other, the 
 steam will move the piston till its force is in equilibrium with the friction 
 and uncondensed steam on the under side of the piston, and power is 
 
56 
 
 communicated during the motion, in addition to the ordinary effect of 
 the original steam pressure. To apply this power, which was lost before, 
 HORNBLOWER used two cylinders in which the steam was to act. He 
 employed the steam, after it had acted in the first cylinder, to operate a 
 second time in the second and larger cylinder, by permitting it to expand. 
 This he accomplished by connecting the cylinders together by proper 
 apertures. We give his own description in the words of his specifica- 
 tion : " I employ the steam after it has acted in the first vessel to 
 operate a second time on the other, by permitting it to expand itself, 
 which I do by connecting the two vessels together." 
 
 The expansive property of steam is strictly mechanical, and is a pro- 
 perty common to all fluids air, gas, &c. It simply consists in this 
 that vapour of a given elastic force will expand to certain limits, and 
 during the process of expansion will act on opposing bodies with a force 
 gradually decreasing, causing a diminution of elastic power in an inverse 
 ratio to the increase of volume, until it has reached the limits of its 
 power, or is counterbalanced by the resistance of a surrounding medium. 
 Thus, steam of any given pressure, expanded to twice its original bulk, 
 will exert only one half its original power. If a partial vacuum be 
 formed on one side of a piston, its motion will be continued until the 
 density of the steam on the other side be as low as that of the uncon- 
 densed vapour on the vacuum side of the piston. It is clear that the 
 power which may be obtained by thus impelling a piston will be the 
 average between the highest and the lowest pressure upon the piston. 
 It must also be understood that IT is A SAVING, AND NOT A GAIN, 
 that thus results from expansion : a power being made available which 
 was before lost, by using the steam up to its last impelling force, and not 
 allowing it to escape until the whole of that available force has been 
 expended. This accounts for some Engines using more fuel and steam 
 than others, because the steam is not expanded to its utmost limit, in 
 consequence of the steam not being cut off by the valve soon enough ; or 
 that the load on the Engine is great, and requires the steam to be longer 
 on the piston before it is cut off. If the load on the Engine be such as 
 to allow the steam to be cut off early, and to expand to its full available 
 limits in the cylinder, then the most will have been made of it ; the 
 highest pressure in the Boiler will have been used upon the piston, and 
 down to the lowest point. Were atmospheric air compressed so as to 
 exert a force of SOlbs on the square inch, and were the supply to be con- 
 tinued throughout the stroke, an impulse would be given to the piston 
 equal to 201bs to the square inch during the whole stroke ; but if the air 
 was allowed to expand, the impulse would only be as the average, or 
 lOlbs. It will be evident that, if in the former case the air was suffered 
 
57 
 
 to depart from the cylinder at the same elasticity as that which it entered, 
 we should lose the force which was necessary to compress it to its 
 density ; while, by expanding it to its limits, we apply every part of 
 that force. The main spring of a watch actuates its machinery in this 
 manner : an increasing effort is required to wind up the spring, and a 
 decreasing impulse is given back to the machinery. But, if after the 
 spring had partially uncoiled itself, it were then liberated, the force which 
 wound it up to its last impelling point would be totally lost. So in the 
 Steam Engine : if the steam be allowed to escape from the cylinder 
 before its force is expended by expanding to the lowest available pressure, 
 the loss will be in proportion to the amount of the pressure not made 
 available. 
 
 A certain quantity of fuel is required to raise steam to a certain 
 elasticity. If that steam be allowed, after having moved the piston, to 
 escape into the atmosphere or condenser without having acted expansively, 
 a portion of the fuel which was consumed to raise the steam up to that 
 point of elasticity will have been lost. In one case a given bulk of fuel 
 would produce fifty : in the other case it would produce fifty, added to 
 all the intermediates down to the lowest expansive force. 
 
 By this it will be apparent that the advantages arising from expansion 
 increase with the density of the steam. In round numbers, 65 of high- 
 pressure steam will perform more than seven times the duty of 25 of 
 low-pressure steam : a fact greatly in favour of high-pressure steam and 
 expansion. In Condensing Engines the steam expands to half an 
 atmosphere, and sometimes below. In Non-condensing Engines the 
 steam expands to one or two pounds above atmosphere, but often not so 
 low. This entails a loss in proportion to the pressure of the steam 
 thrown into the atmosphere. 
 
 WORKING STEAM EXPANSIVELY IN ONE CYLINDER. 
 
 THERE are two modes of applying the power of steam to the working 
 cylinder, namely : one, allowing steam to flow from the Boiler during the 
 whole length of the stroke ; and the other, cutting it off from the Boiler 
 when the piston has travelled a determined distance the great and 
 paramount object of this last arrangement being a saving of fuel. 
 
 If steam be applied the full length of the stroke, the average pressure 
 will be as the pressure per square inch upon the piston ; but if the steam 
 be cut off at half stroke suppose the pressure to be Golbs per inch when 
 the pressure of the atmosphere is added there will be a mean equivalent, 
 or average pressure, throughout the stroke of 55R>s per square inch ; 
 
58 
 
 being only lOIbs less than the full pressure, or 16 per cent, of a loss in 
 power, though half the former quantity of steam has only been used. This 
 alone effects a saving of 34 per cent, in fuel, and shows the great benefit 
 to be derived from expansion in one cylinder. 
 
 If this principle be true and its truth is undeniable it is quite evident 
 that the greatest economy will result from extending expansion to its full 
 limit, and making the cylinders of Steam Engines of sufficient capacity 
 for this purpose ; though with the high-pressures with which expansion 
 is most available, they will require to be less than are usually made, to 
 allow the Engines to produce the maximum effect. The table which 
 follows this section shows, according to the pressure used, the average 
 pressure of steam upon the piston when cut off at any portion of the 
 stroke. The table begins at lOEbs above atmosphere, and advances in 
 51bs up to 1501bs per square inch. This table will enable the Engineer 
 to determine, by any given pressure, the amount of expansion required 
 for the power to be obtained, and the saving thereby to be effected. 
 
 The principle of expanding the steam in the Condensing Engine is the 
 same as in the Non-condensing Engine, excepting that the steam, which 
 exhausts into the atmosphere, cannot expand below 15Ibs per square inch, 
 because the exhaust is open to the pressure of the atmosphere in all cases. 
 The resistance of the atmosphere (15Ibs) must be added to the pressure 
 of steam above atmospheric pressure, when calculating the pressure of the 
 expansion of steam upon the piston. For example : steam at 20K>s 
 pressure above the atmosphere upon the piston, cut off at one-fourth the 
 stroke, will be 8|lbs at the termination of the stroke, as shown by the 
 following calculation : 20fbs added to loBbs, the pressure of the atmo- 
 sphere, equals 35Ibs. This divided by four, gives the quotient 8f Ibs. 
 Thus, 8f Ibs is the pressure at the termination of the stroke, or GJBbs 
 below atmospheric pressure. The diagram which follows, No. 16, and 
 the explanation, illustrate the principle more fully. 
 
 A represents the cylinder of a Steam Engine, divided into eight equal 
 parts. The pressure of the steam used is supposed to be 50 Ibs per square 
 inch above the pressure of the atmosphere. Suppose the steam to be cut 
 off at one-eighth the stroke, and the piston to be travelling the other 
 seven portions by the force of the expanding steam : in calculating what 
 will be the pressure at the termination or at any other portion of the 
 stroke, add the pressure of the atmosphere to the pressure of the steam 
 above atmospheric pressure. Thus, in this case : 501>s added to 15tt>s, 
 equals 65 ; this divided by 8, gives 8 J. To make this rule more per- 
 fectly understood, let the Engineman add together the pressure of the 
 steam and that of the atmosphere, and divide by the number of expan- 
 sions, and the quotient will give him the pressure on the piston at the 
 
59 
 
 end of the stroke. For the average on the piston throughout the stroke, 
 see the accompanying table ; which average will be found to be 251bs 
 throughout the whole of the stroke. 
 
 Diagram No. 16. 
 
 G51bs- 
 
 32 J- 
 
 21f- 
 
 -16J- 
 
 13 
 
 10*- 
 
 By using steam on the piston of an Engine throughout the stroke at 
 651bs pressure, the average is as the pressure, or 651bs : by cutting off 
 at one-eighth of the stroke, the average is 251bs. It therefore follows that 
 as we only use one-eighth the quantity of steam to obtain 25, as we use for 
 the one stroke with steam throughout, we obtain additional power by 
 expansion indeed, upwards of three times the power, or as 200 is to 65. 
 
 The annexed figure, Diagram No. 17, illustrates the expansion of 
 steam in the cylinder, and gives a mode whereby to ascertain the 
 pressure at any portion of the stroke. In the figure the steam is repre- 
 sented at the commencement as being at 651bs on the piston, cut off at 
 one-eighth the stroke. The figures 1, 2, 3, 4, 5, 6, 7, and 8, are the 
 numbered divisions of the cylinder. To ascertain the pressure when the 
 piston has travelled either one-fourth or one-third, or any other portion 
 of the stroke, the pressure in the first division must be divided by the 
 number of divisions, or portions, whose pressure is required to be known. 
 Thus, if the pressure be required when the piston has travelled half 
 the length of the cylinder, we must divide by 4, the piston having 
 travelled four parts out of the eight into which the cylinder is divided. 
 So also with each division, or number of divisions. Where the expan- 
 sions are either less or more, the cylinder must be divided accordingly 
 into the same number of parts as there are expansions. 
 
 For example : steam at 20Jbs above the atmospheric pressure, cut off 
 at one-third of the stroke, will be, at the end of the stroke, 1 1 |-R>s ; 
 thus, 20S>s of steam and 155>s atmospheric pressure equals. 35K>s cut off 
 
60 
 
 at one-third is 3-f-35 = ll f 2, or nearly 4fbs below atmosphere. If a 
 High-pressure Engine, the pressure of the atmosphere must be added in 
 th same way. Example : 805>s cut off at one-sixth the length of the 
 cylinder : 80 added to 15, equals 95 ; 6 in 95 = 15-5. The steam in 
 
 Diagram No. 17. 
 
 Pressure at the end of 
 the stroke. 
 
 ft>s fts 
 
 65-8- 8 
 
 ,, 7 = 9? 
 6 = 10* 
 5 = 13 
 
 3 = 21 
 
 65 
 
 Pressure at beginning 
 of the stroke, above 
 atmosphere, SOfts, 
 15 added = 65ft s. 
 
 7. 
 
 50. 
 
 15. 
 
 this case will have expanded down to the pressure of the atmosphere 
 within five-sixths of a pound, and therefore will have been practically 
 used up in a Non- condensing Engine before it is allowed to escape. In 
 
61 
 
 a Condensing Engine, the 15'5Ibs would, in practice, expand down to 
 5Ibs or lOIbs below atmosphere : the difference being power lost in a 
 Non-condensing Engine. 
 
 In using steam of high-pressure, another advantage is obtained, iuso- 
 inuch as it requires proportionately less fuel for the generation of increased 
 high-pressure steam. The cost of the raw material, or fuel, for steam 
 at various pressures will hereafter be shown, and the saving effected oy 
 generating and working with steam at high-pressure will be noted. 
 
 Steam on. 
 
 Quantity 
 of steam 
 used. 
 
 Pressure of 
 steam above 
 atmosphere. 
 
 Pressure of 
 steam with 
 the 
 atmosphere. 
 
 Power 
 obtained. 
 
 Pressure of 
 steam at the 
 end of the 
 stroke. 
 
 Full length 
 
 100 
 
 80fts 
 
 95Rs 
 
 100 
 
 95fts 
 
 
 1 
 
 874 
 
 ... 
 
 ... 
 
 97 
 
 83 
 
 
 I 
 
 75 
 
 ... 
 
 ... 
 
 95 
 
 71 
 
 "S 
 
 1 
 
 621 
 
 ... 
 
 ... 
 
 92 
 
 59 
 
 1 - 
 
 4 
 
 50 
 
 ... 
 
 ... 
 
 84 
 
 474 
 
 tt 
 
 1 
 
 374 
 
 ... 
 
 ... 
 
 71 
 
 3Ii 
 
 
 i 
 
 25 
 
 ... 
 
 ... 
 
 60 
 
 234 
 
 
 i i 
 
 JJ 
 
 ... 
 
 ... 
 
 37 
 
 Hf 
 
 The accompanying table shows the quantity of steam used when 
 worked without expansion, and the power obtained also the quantity 
 when worked expansively, varying from J to -J- the cut-off, and the pres- 
 sure of the steam at the termination of the stroke. It will be observed 
 that in proportion as the steam is expanded to the greatest limit, so is 
 the saving : the principle of expansion being a saving, and not a gain. 
 But the whole of the steam is made available when expansion is carried 
 to its full extent. Thus, if steam at 601bs, or any other pressure, be 
 brought upon the piston, and cut off at a point to enable it to expand to 
 the lowest practical limit, the most will have been made of it, although 
 the expansion has been effected in one cylinder. 
 
 When the steam passes through a number of cylinders, there is a 
 loss by condensation and friction, particularly if the pressure be high. 
 The conducting properties of the metal rob the steam of its heat in pro- 
 portion to the difference of the temperature. Hence the necessity of 
 clothing high-pressure cylinders and pipes with felt, or other non-con- 
 ducting substance, to prevent the absorption of the caloric ; or of casing 
 them, keeping steam in the casings at the pressure of the Boiler. The 
 higher the temperature at which the cylinders of Steam Engines can be 
 maintained, the better. 
 
62 
 
 A TABLE, 
 
 Shewing the average Pressure of the Steam upon the Piston throughout the 
 
 Stroke, when cut off in the Cylinder from -^ to {-^, commencing with 
 
 lOfts and advancing in 5ft>s up to 150ft>s Pressure. 
 
 Steam Cut off in 
 the Cylinder. 
 
 Pressure in Ibs. at the commencement of the Stroke. 
 
 2 
 3 
 
 4 
 5 
 6 
 
 7 
 8 
 9 
 
 10 
 11 
 12 
 13 
 14 
 15 
 Jfi 
 17 
 lii 
 19 
 20 
 21 
 22 
 23 
 24 
 25 
 20 
 27 
 28 
 29 
 30 
 31 
 
 33 
 34 
 35 
 .%' 
 
 : " 
 
 10 
 
 15 
 
 20 
 
 25 
 
 30 
 
 35 
 
 40 
 
 45 
 
 50 
 
 55 
 
 60 
 
 65 
 
 70 
 
 75 
 
 Average Pressure in Ibs. upon the Piston. 
 
 * 
 
 7 
 94 
 
 104 
 14 
 
 144 174 
 
 181' 231 
 
 21 
 
 241 
 
 28 
 
 314 
 
 35 
 
 ~46f 
 
 381 
 
 42 451 
 564 61 
 
 49 
 
 521 
 
 * 
 
 284 
 
 321 
 
 374! 42 
 
 514 
 
 654 
 
 704 
 
 i 
 
 6 
 
 9 
 
 12 
 
 15 
 
 171 
 
 201 
 
 231 
 
 261 
 
 291! 32 I 35 1| 381 
 
 411 
 
 441 
 
 4 
 1 
 
 81 
 
 121 
 
 17 
 
 21 
 
 254 
 
 294 
 
 331 
 
 38 
 434 
 
 424! 461 
 
 501 
 
 55 
 
 594 
 
 631 
 
 94 
 54 
 
 144 
 
 194 
 
 24 
 
 281 
 
 334 381 
 
 484 
 
 53 
 
 571 
 
 62| 
 
 674 
 
 724 
 
 | 
 
 71 
 
 104 
 
 13 
 19 
 
 151 
 23 
 
 184 
 261 
 
 201 234 
 
 26 
 
 281 
 
 314 
 
 34 
 
 361 
 
 39 
 
 i 
 
 74 
 
 114 
 
 154 
 18 
 
 194 
 
 304 344 
 
 384 42 
 
 46 
 
 491 
 "58| 
 
 534 
 
 574 
 671 
 
 f 
 
 9 
 
 13 
 141 
 
 221 
 231 
 
 27 
 
 314 
 
 364 401 
 
 454 
 
 491 
 531 
 
 544 
 
 634 
 
 t 
 
 91 
 
 294 
 
 344 
 
 39 
 
 44 
 201 
 "444 
 181 
 
 49 
 
 581 
 
 631 
 
 731 
 
 i 
 
 44 
 91 
 
 7 
 141 
 
 94 
 
 114! 14 
 
 164 
 
 184 
 
 234 
 
 251 
 
 iP 
 
 321 
 
 341 
 
 
 
 191 
 
 341 
 
 391 
 
 494 
 
 54 
 
 64 
 
 69 
 
 731 
 
 f 
 
 8 
 
 r 
 
 44 
 
 64 
 
 104 
 
 16 
 191 
 224 
 
 124 
 
 141 
 
 161 
 251 
 
 21 
 
 234 
 
 254 
 
 274 
 
 294 
 45 
 
 314 
 
 61 
 
 91 
 
 121 
 
 194 
 
 224 
 
 281 
 
 32 
 
 354 
 
 381 
 
 411 
 
 484 
 
 71 
 
 111 
 
 151 
 171 
 
 231 
 
 271 
 
 311 35^ 
 354 40 
 
 391 
 
 434 
 
 49 
 
 474 
 
 514 
 
 551 594 
 
 
 81 
 94 
 
 134 
 
 261 
 
 314 
 
 334 
 341 
 
 444 
 47| 
 
 534 
 
 571 
 
 621 
 661 
 
 6(>f 
 
 5 
 
 144 
 
 19 
 
 231 
 ~24| 
 
 281 
 
 384 
 
 421 
 444 
 
 524 
 
 544 
 
 214 
 
 574 
 
 62 
 
 714 
 
 91 
 
 141 
 
 191 
 
 Tlf 
 
 394 
 154 
 
 594 
 
 631 
 
 744 
 
 | 
 
 31 
 
 51 
 
 T84 
 
 221 
 
 131 
 
 174 
 
 194 
 
 23 
 
 25 
 
 27 
 
 281 
 551 
 
 ~T 
 
 74 
 
 11 
 
 141 
 184 
 
 224 
 -274 
 
 26 
 
 291 
 
 331 
 
 ~44| 
 
 37 
 
 401 
 
 1*4 
 
 541 
 
 441 
 554 
 
 52 
 
 94! 131 
 
 32 
 
 361 
 394 
 
 451 
 
 591 
 644 
 23 
 
 1 
 
 681 
 "744 
 
 f- 
 
 91 
 34 
 54 
 
 141 
 
 191 
 
 241 
 
 291 
 
 341 
 
 494 
 
 594 
 
 54 
 
 7 
 
 81 
 
 104 
 164 
 
 124 
 
 194 
 
 144 
 
 151 
 
 171 
 
 194 
 
 261 
 
 i 
 
 84 
 12 
 
 11 
 
 131 
 
 224 
 
 25 
 
 271 
 
 304 
 
 334 
 484 
 
 36 
 
 381 1 411 
 
 I 
 
 8 
 
 16 
 "174 
 
 20 
 
 24 
 
 28 
 
 32 
 
 36 
 394 
 
 404 
 
 444 
 
 524 
 
 564 60 i 
 
 | 
 
 134 
 
 22 
 
 264 
 
 301 
 
 354 
 ~38f 
 
 44 
 
 484 521 
 
 564 
 
 611 
 
 66 
 -721 
 
 744 
 23 
 
 1 
 
 94 
 9| 
 
 144 
 
 194 244 
 
 29 
 
 34 
 
 431 
 
 484 
 494 
 
 534 
 
 584 
 594 
 
 68 
 
 I 
 
 141 
 
 44 
 
 191 
 6 
 
 241 
 
 291 
 
 341 
 
 391 
 
 444 
 
 544 
 
 694 
 
 TT 
 
 3 
 
 71 
 124 
 154 
 
 94 
 141 
 
 101 
 
 124 
 
 154 
 
 1<)'| 
 
 184 
 
 294 
 
 20 
 
 401 
 
 ~474 
 
 214 
 
 TT 
 
 91 
 
 174 
 
 211 
 
 19i| 22 
 
 244 
 
 314 
 
 27 
 
 344 
 
 361 
 
 A 
 
 64 
 
 94 
 
 124 
 
 181 
 
 25 
 
 28 
 
 344 
 
 374 
 
 431 
 
 TT 
 
 74 
 
 8 
 
 144 
 
 184 
 
 204 
 
 211 
 244 
 
 254 
 
 294 
 
 321 
 
 364 
 "401 
 
 404 
 
 431 
 481 
 
 51 
 
 541 
 
 ^T 
 
 12 
 
 164 
 
 284 
 
 324 
 
 364 
 
 444 
 
 521 
 
 561 
 
 601 
 651 
 ~694 
 
 TT 
 
 81 
 
 13 
 
 174 
 
 264 
 
 304 
 
 35 
 
 394 
 
 431 
 46 
 
 48 
 50| 
 
 521 
 
 561 
 
 61? 
 
 T 7 r 
 
 94 
 94 
 
 131 
 
 184 
 
 23 
 
 274 
 
 324 
 334 
 
 361 
 
 414 
 
 554 
 
 60 
 
 644 
 
 R 
 
 TT 
 
 144 
 141 
 141 
 
 19 
 
 231 
 244 
 
 "^ 
 
 21 
 
 -24J 
 
 281 
 
 384 
 ~39~ : 
 
 43 
 
 471 
 
 521 
 54 
 
 574 
 
 _62i 
 631 
 "64| 
 
 TTT 
 
 91 
 
 194 
 
 294 
 
 344 
 
 44 
 
 49 
 
 581 
 
 681 734 
 
 JT 
 T* 
 
 91 
 21 
 84 
 
 191 
 
 291 
 ~25j 
 
 341 
 10 
 
 391 
 
 441 
 13 
 
 491 
 
 541 
 
 591 
 
 694 
 
 744 
 
 44 
 
 51 
 
 114 
 
 144 
 
 151 
 
 174 
 
 181 
 
 204 
 
 211 
 
 TV 
 
 124 
 
 161 
 
 294 331| 38 
 
 424 
 
 464 
 
 501 55 
 
 594 j 631 3 o 
 
 TIT 
 
 9|l 14f 191 
 
 291 
 
 341 391 
 
 441 
 
 491 
 
 541| 591) 64f 
 
 691! 741 40 
 
63 
 
 A TABLE, 
 
 Shewing the average Pressure of the Steam upon the Piston throughout the 
 
 Stroke, when cut off in the Cylinder from ^ to -]-^, commencing with 
 
 lOlbs and advancing in 51bs up to 1501bs Pressure. 
 
 Pressure in Ibs. at the commencement of the Stroke. 
 
 80 
 
 85 
 
 90 
 
 95 
 
 100 
 
 105 
 
 110 
 
 115 
 
 120 
 
 125 
 
 130 
 
 135 
 
 140 
 
 145 
 
 150 
 
 Average Pressure n Ibs. upon the Piston. 
 
 56" 
 
 591 1 63 
 
 664 
 
 70 
 ~93f 
 
 73 
 
 "984 
 
 774| 804 84 
 
 874 
 
 91 
 
 944 
 
 98 
 
 1014 
 
 105 
 
 75 
 
 794 
 
 841 
 
 89 
 "56! 
 
 103 
 
 107? 
 
 1124 
 "714 
 
 117 
 
 121? 
 
 1264 
 "804 
 
 1144 
 
 131 
 
 135? 
 
 1404 
 
 47? 
 
 50? 
 
 53? 
 
 59? 
 
 62? 
 
 654 
 
 684 
 
 744 
 
 774 
 
 834 
 
 861 
 
 891 
 
 67? 
 
 72 
 
 764 
 87 
 
 804 
 
 84? 
 
 89 
 
 934 
 1064 
 
 974 
 111 
 
 1014 
 TT5? 
 
 105? 
 
 110 
 
 1184 
 
 122? 
 
 TIo" 
 
 127 
 144| 
 
 774 
 41? 
 
 82 
 
 91? 
 
 964 
 
 1014 
 
 120? 
 
 1251 
 
 1304 
 
 1354 
 
 444 
 
 47 
 
 494 
 
 54? 
 
 574 
 
 60 
 
 624 
 
 654 
 
 67? 
 
 704 
 
 73 
 ToTJ 
 
 754 
 
 784 
 
 
 65 
 
 69 
 ~8l4 
 
 72? 
 
 764 
 
 804 
 
 844 
 
 88 
 
 91? 
 
 95? 
 U34 
 
 991 
 
 1034 
 
 ill 
 
 115 
 
 72i 
 
 77 
 
 86 
 
 904 
 
 954 
 
 991 
 
 1044 
 
 108? 
 
 117? 
 
 1224 
 
 126? 
 
 1311 
 
 135 
 
 146? 
 "69? 
 
 784 
 
 83 
 
 88 
 
 92? 
 "444 
 
 97? 
 "464 
 
 102? 
 ~48f 
 1031 
 
 1074 
 
 1121 
 
 1174 
 
 1224 
 "58" 
 
 1274 
 
 132 
 
 136? 
 "65" 
 
 141? 
 
 374 
 
 391 
 
 41? 
 
 514 
 
 534 
 
 55? 
 
 601 
 
 62? 
 
 674 
 
 78? 
 
 83? 
 
 88? 
 "37? 
 
 934 
 
 981 
 
 1084 
 
 1134 
 "484 
 
 1184 
 504 
 
 1234 
 
 128 
 
 133 
 
 137? 
 
 142? 
 
 147 
 
 331 
 
 35? 
 
 40 
 
 42 
 
 44 
 
 464 
 
 524 
 
 54? 
 
 58? 
 90 
 
 61 
 "93| 
 
 63 
 
 514 
 
 541 
 
 57? 
 
 61 
 
 644 
 
 674 
 
 70? 
 "87" 
 
 74 
 
 774 
 
 804 
 
 834 
 
 102J 
 
 86? 
 
 961 
 
 634 
 
 674 
 
 7H 
 
 754 
 
 79 
 
 83 
 ~93i 
 1004 
 
 91 
 
 94? 
 
 98? 
 
 106? 
 
 110? 
 
 114? 
 
 118? 
 
 ^4 
 
 75? 
 
 80 
 
 844 
 
 89 
 
 98 
 
 1024 
 T09? 
 
 106? 
 
 1114 
 
 1204 
 128? 
 
 124? 
 
 1294 
 
 1334 
 1434 
 
 81 
 
 85? 
 
 90? 
 
 951 
 
 105 
 
 1141 
 
 1194 
 1231 
 
 1331 
 
 1384 
 
 79 
 
 84 
 
 89 
 
 93? 
 
 98? 
 
 103? 
 
 108? 
 ^2? 
 
 113? 
 
 118? 
 "461 
 
 1281 
 "50" 
 
 1334 
 
 1384 
 
 1431 
 
 1484 
 
 30? 
 
 32? 
 
 344 
 
 364 
 
 401 
 
 444 
 
 48 
 
 52 
 
 544 
 
 564 
 
 57? 
 
 591 
 
 63 
 
 66? 
 
 704 
 
 744 
 
 81? 
 
 854 
 105| 
 
 89 
 
 92? 
 
 1004 
 
 104 
 
 107? 
 
 1H4 
 
 137? 
 
 731 
 
 78 
 
 874 
 944 
 
 91? 
 
 961 
 
 101 
 109" 
 
 1104 
 
 114? 
 
 1194 
 
 124 
 
 1284 
 
 1334 
 
 794 
 
 844 
 
 894 
 
 99 
 
 104 
 
 114 
 
 119 
 
 124 
 
 128? 
 
 133? 
 
 138? 
 "491 
 
 143? 
 
 148? 
 
 284 
 
 304 
 
 33? 
 
 374 
 
 39 
 
 40? 
 
 424 
 
 46 
 
 47? 
 75 
 
 514 
 791 
 1164 
 
 534 
 
 441 
 
 474 
 
 55 
 
 57? 
 
 554 
 
 584 
 
 61 
 
 63? 
 
 66? 
 
 691 
 1004 
 
 1211 
 
 724 
 
 77? 
 
 83 
 1204 
 
 644 
 
 684| 724 
 
 764 
 
 804 
 
 841 
 924 
 
 884 
 
 924 
 
 964 
 
 1041 
 
 1084 
 
 1124 
 123| 
 
 70J 
 
 74? 
 
 794 
 
 83? 
 
 88 
 
 97 
 
 1014 
 
 105? 
 
 119 
 
 127? 
 14T 
 14l~ 
 
 1324 
 
 77? 
 
 82? 
 
 874 
 
 924 
 
 974 
 
 102 
 
 107 
 1094 
 
 111? 
 
 1144 
 
 U94 
 
 1261 
 
 1314 
 
 1364 
 
 145 
 149" 
 
 794 
 
 844 
 
 891 
 
 944 
 
 994 
 
 1044 
 
 124 
 
 129 
 40 
 "63? 
 
 134 
 
 139 
 
 ^34 
 
 244 
 
 264 
 
 27? 
 
 294 
 
 30? 
 
 324 
 
 33? 
 
 351 
 
 37 
 59 
 
 381 
 
 411 
 
 44? 
 
 464 
 
 394 
 
 41? 
 
 444 
 
 46? 
 ^591 
 
 49 
 
 511 
 
 54 
 
 561 
 
 664 
 
 68? 
 
 714 
 
 73? 
 
 50 
 
 534 
 
 564 
 
 65? 
 
 68? 
 
 72 
 
 754 
 
 87? 
 
 784 
 914 
 
 814 
 
 841 
 
 87? 
 
 90| 
 
 94 
 
 584 
 
 62 
 
 65? 
 73 
 
 694 
 
 73 
 814 
 
 76? 
 
 804 
 
 84 
 
 95 
 
 984J 1024 
 
 106 
 
 1091 
 
 65 
 
 69 
 
 77 
 
 854 
 
 894 
 
 931 
 
 974 
 
 1014 
 
 1054 
 
 109? 113? 
 
 117? 
 
 T3l~ 
 1384 
 
 70 
 
 744 
 
 78? 
 
 83 
 
 874 
 924 
 
 964 
 
 100? 
 
 105 
 
 TTof 
 
 1091 
 
 113? 
 
 11841221 
 
 127 
 
 73? 
 
 784 
 
 83 
 
 87? 
 91 
 "93j 
 
 97 
 
 1011 
 T05j 
 
 1061 
 
 1154 
 
 120 
 
 124? 
 
 1294 
 
 133? 
 139" 
 
 76? 
 
 814 
 
 864 
 
 95? 
 
 1001 
 
 115 
 TT7? 
 
 119? 
 122? 
 1244 
 
 1241 
 
 1294 
 1324 
 
 1344 
 
 1434 
 
 784 
 
 834 
 
 884 
 
 103 
 
 108 
 
 112? 
 
 1274 
 1294 
 
 1374 
 
 1424 
 
 1474 
 1494 
 
 791 
 
 844 
 
 944 
 
 994 
 
 1094 
 
 1144 
 334 
 
 1194 
 
 1344 
 
 1394 
 
 1444 
 
 234 
 
 241 
 
 26 
 
 274 
 
 29 
 
 301 
 
 31? 
 
 34? 
 
 354 
 
 37? 
 
 39 
 
 404 
 
 42 
 T22? 
 
 431 
 
 67? 
 
 72 
 
 764 
 
 804 
 
 84? 
 
 89 
 1044 
 
 934 
 1091 
 
 974 
 
 1014 
 
 105? 
 
 110 
 
 1144 
 
 1184 
 1391 
 
 127 
 
 794 
 
 844 
 
 894 
 
 944 
 
 994 
 
 1144 
 
 1194 1244 
 
 1294 
 
 1344 
 
 1444 
 
 1494 
 
64 
 
 THE FOREGOING TABLE 
 
 SHOWS, according to the pressure used, the average pressure of steam 
 upon the piston, cut off at any portion of the stroke, beginning at lOBas, 
 and advancing in 5Ibs up to 1501bs per square inch ; enabling the 
 Engineer to determine, at any given pressure, the amount of expansion 
 requisite for the full power to be obtained, and the saving thereby to be 
 effected. In all cases the pressure of the atmosphere must be added to 
 the pressure of the steam above atmosphere, when reference is made to 
 the table for the average throughout the stroke. 
 
 Example : 151bs pressure on the piston above atmosphere, cut off at 
 one-fourth the piston's traverse, will be thus: 151bs steam and lolbs the 
 pressure of the atmosphere = 30 : then look for 301bs at the head of the 
 table, and down the first column for J ; trace that J under 30, and you 
 will find the average to be 17 jibs throughout the stroke. For other 
 proportions follow the same principle that is, supposing the vacuum to 
 be 151bs. If there be not 151bs of a vacuum, the amount of pressure 
 below must be deducted from the average. 
 
 If a Non-condensing Engine, where the steam is expanded into the 
 atmosphere, the case will be different : because the steam cannot expand 
 below 151bs to the square inch, that being the pressure of the 
 atmosphere. 
 
 Example: 451bs steam above atmosphere upon the piston of a 
 High-pressure Engine, cut off at one-fourth the length of the stroke. 
 The average pressure throughout will be allowing lib for friction and 
 back-pressure to force out the steam in the cylinder 19 Jibs. Thus : 
 451bs steam cut off at one-fourth the stroke, with 151bs added, make 
 601bs. Look for 60 on the top line of the table, and J en the side. 
 Trace that J to the figures under 60, and the average will be found to 
 be 35 Jibs. Take 161bs from 35 Jibs, for atmospheric pressure and 
 friction, and there remains 19 Jibs the available average pressure on 
 the piston. 
 
 Example: 301bs cut off at one-third. Add 15, 45. The average 
 in the table will be 31 J : deduct 161bs, and there remain 15 Jibs, the 
 available average pressure upon the piston. 
 
 Another Example : 151bs cut off at half-stroke. Add 15, = 30. The 
 average in the table will be 25J. Deduct 1 61bs and 9 Jibs remain, the 
 average available pressure. 
 
 In these examples the steam in the cylinder has expanded to 
 atmospheric pressure. 
 
 In proportion to the pressure of the steam, the cut-off will have to be 
 varied, as shown by the examples, if the steam is to be expanded to its 
 full limit in the cylinder of a Non -condensing Engine ; that is, down to 
 151bs, or equal to the pressure of the atmosphere. 
 
65 
 
 NOMINAL AND INDICATED HORSE-POWER OF STEAM ENGINES. 
 
 THE nominal horse-power of a Steam Engine, as laid down by JAMES 
 WATT, the inventor of the Steam Engine Indicator, is 33,0001bs raised 
 one foot high per minute, or any less weight a proportionately greater 
 height in the same space of time. Upon this calculation he defined the 
 power exerted. His first premise was to ascertain the average pressure 
 of steam upon the piston ; and for this, as a standard, he laid down, as 
 a rule, an available pressure of Tibs per square inch. The speed of the 
 piston he computed at 220 feet per minute. These, in his day, were 
 about the average pressure and speed Steam Engines were worked at. 
 Thus, a Steam Engine with a cylinder 26 inches diameter, with an 
 average pressure of steam and vacuum* on the piston of 7K>s per square 
 inch when the friction of the Engine is deducted travelling 220 feet 
 per minute, will be of twenty-four horse-power, or, as it is termed, a 
 twenty-four horse Engine. It would, in fact, be no more when worked 
 at the before-named pressure and speed ; that is, it would exert no more 
 than twenty-four horse-power. This then is, nominally, a twenty-four 
 horse Engine ; and were the Indicator to be applied, it would show the 
 Engine to be working not more than twenty-four available horse-power ; 
 for the " indicated " horse-power in this case would be precisely the same 
 as the " nominal " viz., 33,OOOK>s raised one foot high per minute. 
 
 The term " nominal horse-power " is used because we ascertain 
 originally the power of an Engine by calculation on the basis above laid 
 down ; and when we say " indicated horse-power," it is because we 
 ascertain the power by means of the instrument known as the Indicator. 
 A horse-power, whether termed " nominal " or " indicated," is therefore 
 nothing more nor less than 33,OOOBc>s raised to the height before described 
 independently of the friction of the Engine. 
 
 But let us suppose the same Engine to be worked at an increased 
 pressure say at 305>s per square inch average steam and vacuum ; and 
 the speed, instead of being 220, to be increased to 350 feet per minute 
 (and many Engines are worked at the speed and pressure here referred 
 to) the power of the Engine would be increased to 168 horse-power 
 or to seven times the amount of the " nominal " designation. Though 
 still " nominally " a twenty-four horse Engine, it would, in reality, be an 
 Engine of 168 horse-power. At the speed and pressure above stated, it 
 would indicate that amount. Thus it is by the increase of speed and 
 pressure that Steam Engines are made to exert more power than they 
 were originally calculated for; or at least, more power than the "nominal" 
 designation. Steam Engines are now made much stronger for the same 
 
 * This term is here used as in general parlance : not that there is POWER in vacuum ; but to 
 make the rule understood amongst those who use the term, the popular idea is here adopted. 
 10 
 
" nominal " power, than in the days of WATT. With all Steam Engines, 
 as the pressure and speed are increased, so is the power increased ; but 
 this augmentation of power is not obtained without 'an increased quantity 
 of steam proportionate to the increased pressure, except where steam is 
 used expansively. It will therefore be apparent that the term "nominal" 
 horse-power can only be legitimately used in the sale or purchase of an 
 Engine. On this rule a twenty-four horse Engine means that the cylinder 
 shall be 26 inches diameter, if a Condensing Engine ; and in the same 
 proportion for a larger or a smaller Engine ; for 22 square inches of area 
 in the piston is one " nominal " horse, if a Condensing Engine. If we 
 multiply the diameter of the cylinder by the diameter, and divide by 28, 
 the product will be the number of " nominal " horse-power. 
 
 EXAMPLE. 
 
 Diameter of Cylinder, 30 inches. 
 30 
 
 28 ) 900 ( 32 horse-power. 
 84 
 
 60 
 56 
 
 The purchaser of a Condensing Engine should have 22 square inches 
 area of piston for each " nominal " horse-power, whatever the speed or 
 pressure. The real power exerted can only be ascertained by the 
 Indicator ; hence the term " indicated horse-power." 
 
 This is the standard mode of ascertaining the real power for Condensing 
 Engines, as laid down and established by WATT. It is now universally 
 followed by Engineers. In a case tried at Westminster, where power 
 had been " let by the horse," it was referred to arbitration ; and the 
 question arose, " what constitutes a horse-power T After due enquiry, 
 it was legally established, for the first time, that 33,0001bs raised one 
 foot high per minute is one horse-power, which in the Steam Engine can 
 only be correctly ascertained by the use of the Indicator. 
 
 Non-condensing, or High-pressure Engines, are calculated for the 
 " nominal " power by the following rule : Eleven square inches area of 
 piston is one "nominal" horse-power. Multiply the diameter of the 
 cylinder by the diameter, and divide by 14, the quotient will be the 
 number of " nominal " horse-power. 
 
 A High-pressure Engine, working with 40R>s steam above atmosphere 
 upon the piston, cut off at one-third the length of the cylinder, and 
 expanding the remainder, the piston travelling 220 feet per minute, 
 
67 
 
 would only exert the power for which it was nominally calculated, 
 independent of friction ; but take the same Engine and increase the 
 speed from 220 to 440 feet per minute which is quite practicable in a 
 Horizontal Engine, if the fly-wheel be not too large the power of that 
 Engine would then be doubled, less the extra friction ; but double the 
 quantity of steam would have been used. The exhaust steam would be 
 thrown away at the termination of the stroke at 3 pbs above the pressure 
 of the atmosphere. Suppose steam were introduced to the same cylinder 
 at SOBbs pressure, and cut off at one-third, and worked expansively, as 
 in the first case, the exhaust steam would be thrown away at 16pbs 
 above the pressure of the atmosphere, being five and a half times the 
 pressure, or loss, sustained from steam at 40Ebs. The power given out 
 would also be less in proportion. Steam at 40R>s would yield 38 J horse- 
 power, whilst steam at 80Bbs, and cut off at the same point, would only 
 yield 66 J, thus showing that the steam has not been used up. A portion 
 of it is lost, in consequence of not being expanded to its full limit, the 
 lost portion escaping into the atmosphere, exerting a corresponding back 
 pressure upon the piston. 
 
 High-pressure Engines work at such varied pressures and speeds, that 
 the real power can only be ascertained by the Indicator; but the 
 " nominal " power can be calculated by the rules explained above. In 
 the purchase of a High-pressure Engine, the buyer should have eleven 
 square inches area of piston for each " nominal " horse-power, whatever 
 may be the speed or the pressure the Engine can be worked at. One 
 cubic foot of water evaporated per hour is taken to be one " nominal " 
 horse-power, or 1,700 cubic feet of steam, at atmospheric pressure. 
 
 TO FIND THE POWER OF A STEAM ENGINE ON THE BASIS OF WATTES DEFINITION. 
 
 As before explained, a HOESE POWER is that amount of moving force 
 which, besides overcoming all friction, will raise 33,OOOBbs weight one 
 foot high per minute : or any smaller weight a proportionately greater 
 height in the same time. 
 
 RULE. 
 
 By means of the Indicator, take off a friction diagram when the 
 Engine has no machinery attached only the shafting. Divide the length 
 of the figure into ten equal parts. Measure across the centre of each 
 division by the scale of the instrument, or with a common rule. When 
 the number of pounds to the inch has been ascertained, write them down 
 on each division of the diagram ; then cast them up, and divide the 
 product by ten. If the figure be divided into more than ten, the product 
 must be divided by the number of the divisions on the diagram. The 
 
68 
 
 quotient will be the average pressure in pounds upon each square inch 
 of the piston see diagrams Nos. 18 and 19. No. 18 is a friction 
 diagram, and No. 19 a diagram with the Engine loaded with machinery. 
 It may be mentioned that the average friction of Stationary Engines 
 with the shafting, is 3K>s to the square inch, and of Marine Engines 
 1 Jibs to the square inch upon the Engine piston. If a friction diagram 
 cannot be conveniently obtained, the above is the calculation generally 
 
 Friction Diagram, No. 18. 
 Taken from the Top of a Condensing Engine Cylinder. 
 
 -13-5--- 
 
 35 
 
 3-5 
 
 4-5 
 
 5. 
 
 <- 13-5 > 
 
 3-5Ibs. 
 Average Pressure, 3*5fbs to the square inch upon the piston. 
 
 adopted by Engineers, when the available power is required to be known ; 
 but where possible, it is best, for accuracy, that a friction diagram should 
 be taken. For example, see Friction Diagram No. 18. 
 
 In this diagram, the steam in the cylinder is below the pressure of the 
 atmosphere the full length of the stroke. 
 
69 
 
 EXPLANATION OF THE FIGURING OF DIAGRAMS. 
 
 3*5Ibs means three pounds and a half upon the square inch. Ten 
 being the whole number, five is half ; and all figures from one to ten are 
 in proportion. 2*5, with a dot between, means two and a half pounds ; 
 2-8 means two and eight tenths of a pound ; and so on with all figures 
 below ten. 10 -5 also means ten and a half pounds to the square inch ; 
 so with other numbers; 21 '6 means twenty one pounds and six-tenths 
 of a pound. 
 
 Our rule for calculating the diagrams from the Indicator is given in 
 this simple way, that any person possessing only an indifferent knowledge 
 of figures may understand that rule for many who were disposed to 
 learn the use of the Indicator have been deterred by the use of Algebraic 
 signs in the figuring and calculating of diagrams. These signs are as 
 Greek to a great number of Enginemen, who have not had the benefit of 
 a mathematical education. With the rule here laid down, the compara- 
 tively uneducated amongst them can have no difficulty, and the result, 
 for all practical purposes, will be sufficiently accurate. 
 
 If the steam upon the piston be below the atmospheric line, the same 
 as in No. 18 Diagram, there will only be one column to add up; but if 
 the steam on the cylinder be above atmospheric pressure, as in No. 19 
 Diagram, there will be two columns to add up, one on the steam side, 
 and one on the vacuum side ; and these two will have to be added 
 together to get the whole pressure. They may be measured at one 
 measurement when the steam and the vacuum are on the tenth scale, 
 which is the case where the pressure is under 255>s upon the piston. In 
 the case of a High-pressure Engine, there will only be one column the 
 steam side ; and where there is a back pressure upon the piston, that 
 must be deducted. In a compound High-pressure cylinder, sometimes 
 there is a partial vacuum caused by the steam in the condensing cylinder 
 being below the pressure of the atmosphere ; and in some cases, a con- 
 siderable back pressure is the consequence of the steam on the condensing 
 cylinder being above atmosphere. In the first case, there will be two 
 columns one for the steam, and one for the vacuum. 
 
 RULE TO ASCERTAIN THE POWER REQUIRED TO DRIVE ANY QUANTITY OF 
 MACHINERY : OR THE POWER THE ENGINE IS EXERTING. 
 
 With the Indicator take off a diagram when the load is on, or with 
 the machinery in operation you wish to know the power it will take to 
 drive. For example : Diagram No. 19 is taken from a Condensing 
 Engine with the whole of the machinery in motion, belonging to Mr. 
 GOADSBY, of Manchester that Engine being considered a good example 
 of expanding steam in the cylinder, and also of the setting of valves. 
 
70 
 
 RULE. 
 
 The area of the cylinder being given in square inches, multiply by the 
 speed the piston travels in feet per minute, and multiply by the available 
 average pressure in pounds per square inch upon the piston, having 
 deducted the friction of the Engine and shafting, as below : the multi- 
 plicand will give the number of available horse-power independently of 
 the friction of the Engine when divided by 33,OOOB)s. 
 
 Diagram No. 19, 
 Taken from the Top of a Condensing Cylinder. 
 
 4'6 steam. 
 
 10 '4 vacuum. 
 
 10*4 vacuum. 
 4 - 6 steam. 
 
 Deduct friction diagram ; or the power 15-0 the average pressure upon the piston, 
 required for Engine and shafting ... 3'OBbs. 
 
 12-Ofts., the available pressure upon each 
 square inch of the piston. 
 
 By giving the number of feet per minute traversed by the piston and 
 the diameter of the cylinder, with a diagram, any person conversant with 
 
71 
 
 the use of the Indicator will be able at any time to ascertain the state of 
 his Engine, and what amount of available power it is exerting, or the 
 power for the whole of the machinery the Engine is . driving, including 
 shafting and its own friction. It will not be necessary to send for any 
 one to examine the Engine ; the diagram will be quite sufficient to 
 explain its condition. For example, examine Diagram No. 19. 
 
 Multiply twice the length of the stroke in feet by the number of 
 revolutions per minute ; the product will be the speed the piston 
 travelled in feet per minute. 
 
 EXAMPLE. 
 
 Diameter of cylinder, 32 inches ;* speed of piston in feet per minute, 
 340. 
 
 Multiply the cylinder's diameter 32 
 by the diameter 32 
 
 64 
 96 
 
 To ascertain the number of square 1024 
 
 inches, multiply by "7854 which is the decimal area of a circle of 
 
 one inch, 10,000 being one square inch. 
 
 4096 
 5120 
 8192 
 7168 
 
 804-2496 square inches of the piston. Multiply 
 340 by speed of piston 340 feet per minute. 
 
 321699840 
 Multiply by the effective pressure 24127488 
 
 upon the piston when the 
 
 friction of the Engine and 273444-8640 
 
 shafting has been deducted - 12fi>s., the average available pressure. 
 
 Divide by 33000 ) 3281338-3680 take off four figures, being the decimal 
 297000 ( 99 figures of 7854 ; and the dividend 99 is 
 - the number of horse-power. 
 
 311338 
 297000 
 
 14338 towards 33000. 
 
 By the rule given, we find that this Engine was exerting 99 available 
 horse-power, or 119 horse, including friction of Engine and shafting. At 
 the time the diagram was taken, the Engine was consuming eleven tons 
 of coal per week, including steam for mill, &c., with two boilers of 
 FAIRBAIRN'S patent oval flue, and double fire-box construction. Suppose 
 the eleven tons to be consumed by the Engine when working 60 hours 
 per week, what is the quantity of coal consumed per hour ? 
 
 * To save the trouble of squaring the diameter, see Table of Circumferences and Area of 
 Circles, given afterwards, which gives the areas of circles per square inch. In this case it will be 
 found to be 804 '2496 square inches area. 
 
 ff^T OP THE $^ 
 
 (/U3U7BK3ITT 
 
EXAMPLE. 
 
 Multiply the number of hours GO 
 by the horse-power 99 
 
 540 
 540 
 
 5940 hours and horse power together. 
 
 Reduce the weekly consumption of 2240ft)9., or 1 ton. 
 
 tons into fibs 11 the number of tons per week. 
 
 Divide by the horse-power and the 
 
 number of hours together 5940 ) 24640 ( 4lbs 2oz. 5dr., the consumption per hour 
 23760 per horse-power. If we deduct the 
 
 steam for heating the mill, this will 
 
 Multiply by the number of ounces 880 reduce the consumption for the Engine 
 
 in the lb 16 under 41bs per available horse-power, 
 
 or to 31bs per hour per horse, for the 
 
 5280 whole power exerted. 
 880 
 
 Divide by the divisor as before 5940 ) 14080 ( 2oz. 
 
 11880 
 
 Multiply by the number of drachms 2200 
 in the ounce 16 
 
 1 3200 
 2200 
 
 Divide by the divisor 5940 ) 35200 ( 5 drachms. 
 
 29700 
 
 5500 towards 1 drachm. 
 
 EXPLANATION OF A DIAGRAM. 
 
 Diagram No. 20 taken from the top of the cylinder of a Beam 
 Engine. The steam corner A shows the valve at the commencement of 
 the stroke to be rather too forward. It would be better were it a little 
 later. Then the diagram would be a little rounded at the corner A, thus 
 preventing the steam from pressing too much upon the piston when the 
 crank is at the " plumb centre." The Engine is supposed to be working 
 without expansion. The steam continues to the end of the stroke, as 
 shown at B, nearly at the same pressure the whole length, showing that 
 the valve on the steam side has been open the full length of the stroke. 
 The commencement of the exhaust corner, C, being rounded, shows that 
 the valve is too late. It would be better had the exhaust more " lead : " 
 that is, were the valve on the exhaust side to open a little sooner. This 
 would allow the steam to escape into the condenser earlier, and give more 
 power to the steam at the commencement of the stroke. The termination 
 of the exhaust corner D being square, shows the valve also to be too late 
 
73 
 
 in closing the exhaust. If closed sooner, the Engine would work much 
 better. Should the valve be a D, or a common slide three-port valve, 
 add a little lap to the steam side, and set forward the valve by the 
 eccentric. The valve in that case would not open full port. The 
 exhaust would be opened sooner, and closed sooner, which is required. It 
 
 Diagram No. 20. 
 
 Taken from a Beam Engine with D Valves without Lap, from the Top of the Cylinder. 
 B 
 
 10. 
 
 9-8 
 
 9-8 
 
 10. 
 
 10-5 
 
 10-5 
 
 11. 
 
 11-3 
 
 11-6 
 
 | 12-2 
 
 A ' 
 
 Pressure of Steam, 10'67lbs 
 above Atmosphere. 
 
 8-5 
 
 10. 
 
 10-5 
 
 11. 
 
 11-5 
 
 12. 
 
 12-3 
 
 12-3 
 
 12-3 
 
 D 
 
 10*641bs vacuum. 
 
 10'671bs pressure of Steam. 
 
 21'311bs average pressure of Steam 
 upon the piston. 
 
 would then show a rounding at the corner D in proportion to the distance 
 the valve had been moved forward. (See Diagram No. 19, which shows 
 the exhaust closed sooner, as explained.) If the valves are of the kind 
 known as the tappit, they can be regulated independently of each other 
 by the moving of the tappits. 
 
74 
 
 The diagram being divided into ten equal parts, and each measured by 
 the scale, and figured as shown, the average pressure of the steain above 
 atmosphere, and the amount of vacuum, when added together, will show 
 the average pressure upon the piston at each stroke. The average pres- 
 sure as shown in the example is 21 '3 libs per square inch upon the piston. 
 The bottom, or under side, of the piston should be indicated, and the 
 average of the top and bottom taken for the mean pressure per square 
 inch throughout the stroke. This mode of measuring a diagram viz., by 
 dividing the length of the figure into ten parts, is the mode generally 
 practised, and is found sufficiently correct for practical purposes. Where 
 great exactness is required, a greater number of divisions can be resorted 
 to, and the indication will thereby be the more correct, especially when 
 the indication is from an Engine working steam expansively. 
 
 THE CONSTRUCTION AND ACTION OF VALVES. 
 
 THE reader, by this time, will have learned something respecting the 
 form and the different points to be understood of a diagram. It has, 
 therefore, now become necessary to explain the different forms of valves 
 used in the working of steam in connection with the Steam Engine ; and 
 as these parts may be said to be, as in the human frame, the heart of 
 the structure, should the heart be diseased or deranged, the whole of the 
 structure or system will be thereby affected. How necessary is it, 
 therefore, that the form and proper working of valves should be fully 
 understood. 
 
 COMMON THREE-PORT SLIDE VALVE. 
 
 The annexed engraving, Fig. 21, is an illustration of a Steam Engine 
 cylinder with a three-port slide valve, without " lap." The arrow at H 
 denotes the admission of steam into the valve chest, from thence to the 
 cylinder, and from the cylinder, after having exerted its force upon the 
 piston through the valve and exhaust port to the condenser or into 
 the atmosphere, if a Non- condensing Engine. 
 
 On reference to the illustration it will be seen that the steam and 
 exhaust ports are of equal dimensions ; F F are the thoroughfares to each 
 end of the cylinder, and E the thoroughfare for the exhaust steam to 
 escape into the condenser or into the atmosphere, as the case may be. 
 
 The valve, as now shown, is attached to the rod C, the traverse being 
 attained by the usual means. When the Engine makes one-half of a 
 revolution, or one stroke up or down, the valve changes its position 
 accordingly. 
 
75 
 
 Figure No. 21. 
 
 CYLINDER AND SLIDE VALVE. 
 
76 
 
 As before observed, the arrow H denotes the steam passage from the 
 Boiler to the valve chest D. As the valve is shown, there is a direct 
 opening for the steam through the steam-way F, to act upon the piston 
 B ; and on the under side A, through the exhaust way F, there is a free 
 passage for the exhaust steam into the condenser, or atmosphere, as 
 shown at E. The valve being hollow on the under side, permits the 
 egress, as shown. It will be observed that the faces of the valve will 
 little more than cover the ports, and this construction is therefore 
 appropriately termed " without cover " or " lap." 
 
 Suppose, then, that the piston had proceeded in its traverse to the end 
 of the stroke, the valve would also have changed in position and action ; 
 the steam from the steam chest would be admitted at the other end of 
 the valve on to the other side of the piston, and the steam, which in the 
 former position of the valve had forced the piston to the end of the 
 cylinder, would now be liberated, and allowed to exhaust or depart into 
 the condenser, or atmosphere, through E. The traversing motion of the 
 valve, which is effected by the eccentric, thus changes the application of 
 the steam to each end of the cylinder, provides an inlet for the steam to 
 the piston, and also an opening for exhaustion through the proper 
 channels, after power has been exerted, producing a continuous backward 
 and forward action of the piston of the Engine, and, by means of a beam 
 and connecting-rod attached to the piston, communicating motion to the 
 crank, or in some cases direct to the crank by a connecting-rod only. In 
 the latter case the Engine is called a Direct-action Engine. 
 
 The regularity of speed and economy in the working of the Steam 
 Engine depends in a great degree upon the proper arrangement of the 
 valves. It is of the utmost consequence that full and complete infor- 
 mation on this branch of the subject should be acquired by all who are 
 entrusted with the care and direction of this valuable instrument of 
 power. Many Engines work inefficiently, not only from the defective 
 construction of the valves, but also from imperfect " setting." It will 
 work inefficiently if the thoroughfares are contracted, or the valve-box 
 be too short, or both. In such cases there is little chance of effecting 
 much improvement in the working. 
 
 The three-port valve described above is, as we have said, without 
 " cover" or " lap," being only just sufficient to cover the ports, and prevent 
 the steam passing into both ports at one and the same time. It will be 
 observed that as one port closes the other opens, and the exhaust also. 
 Valves constructed and set in this manner admit steam upon the piston 
 the whole length of the stroke ; the exhaust is also open for the full 
 length of the stroke. Were an Indicator applied, the diagram would be 
 similar to that of No. 22, which is from a High-pressure Engine 
 
77 
 
 working without expansion the exhaust neither opening nor closing 
 before the piston has traversed its full length. The working and economy 
 of this Engine would be greatly enhanced by " lapping " the valve, as in 
 Fig. 23 the steam being used expansively. The steam port has been 
 
 s 
 
 closed earlier, therefore the steam has been cut off before the termination 
 of the stroke. The steam already in the cylinder would then expand and 
 force the piston forward the remainder of the stroke. To produce the 
 same power, however, a greater pressure of steam would be required on 
 
78 
 
 the piston at the commencement of the stroke ; but as the Boiler in this 
 instance is already pressed up to the limit of safety, the Engine neces- 
 sarily consumes a greater quantity of fuel than- it would if the steam 
 could be worked expansively. 
 
 To enable this valve to cut off earlier and work expansively,. without 
 adding " lap," would be to make up part of the thoroughfares at each 
 end of the valve-box towards the outer edge, and cut away some of the 
 metal in the inside of the ports, so that the ports would not be much 
 contracted. In that case the valve would cut off the steam the same as 
 if it had " lap." The hollow of the valve would require to be propor- 
 tionately less, by being " bitted " in the same way as the thoroughfares. 
 This mode is resorted to when the valve-box is too short, and where 
 " lap " cannot be added to the valve ; this is called " lapping the 
 thoroughfares." 
 
 " LAP," OR COVER OP THREE-PORT SLIDE VALVES. 
 
 Fig. 23 is a representation of a cylinder and a three-port slide valve. 
 The same letters denote the same parts as in Fig. 21. In this instance 
 the valve is shown with " lap " or cover, so as to cut off the steam to 
 work expansively. This latter is accomplished to a greater or less 
 degree according to the amount of " lap " or cover of the valve. It will 
 be observed in Fig. 23 that the cover is three-fourths broader than the 
 steam ports, and being worked by the same eccentric, with the same 
 length of traverse, it does not open the steam port more than one-fourth 
 of its width, which in some cases would not be sufficient to admit the 
 full pressure of steam to the piston ; but where the ports are of sufficient 
 width, and there is a proper pressure in the Boiler, no difficulty is expe- 
 rienced by adding " lap " to the valve. 
 
 Let us ascertain the effect of this additional breadth of valve face. 
 When the valve edge arrives at the port, ready to admit the steam upon 
 the piston, it will have moved three-fourths the length of its traverse. 
 The remaining distance is the amount of opening given for the admission 
 of steam to the piston, which will not be more than half an inch, if the 
 ports be two inches wide : the valve is then reversed by the motion or 
 throw of the eccentric, and it will therefore have opened and closed the 
 steam port with one inch of traverse, half an inch each way. As this 
 valve is V shaped on the edge, the steam is admitted to the piston easily, 
 and cut off easily. This is technically termed " easy steaming." Were 
 the Indicator applied, the diagram would be similar to Diagram No. 24. 
 At the termination of the piston's descent, the steam is fully exhausted 
 ready for the return stroke. This is called " lead of the exhaust." The 
 full length of the traverse of the valve is four inches for one revolution 
 
7'.) 
 Figure No. 23. 
 
 CYLINDER AND SLIDE VALVE, WITH " LAP. 1 ' 
 
80 
 
 of the Engine. This arrangement cuts off the steam at about one-fourth 
 the length of the stroke, the remainder of the stroke being worked by 
 the expansibility of the steam. Each end of the valve is of the same 
 width. 
 
 The ports, being two inches wide, require that the face of the valve, 
 with the same traverse, shall be 3J inches broad, being 1 J inches broader 
 than the width of the ports. It will also be perceived that the exhaust 
 side of the valve will be three-fourths open when the crank is at the 
 plumb centre. By these means the steam in the cylinder is exhausted 
 ready for the return stroke. The closing of the exhaust is also effected 
 much earlier, whereby the uncondensed steam left in the cylinder becomes 
 compressed towards the end of the stroke. This in practice is found to 
 act as a buffer to the piston, preventing a sudden shock at the termina- 
 tion and commencement of the stroke. The steam thus compressed is 
 not lost, but gives back a portion of its power on the reversal of the 
 piston. 
 
 It is necessary for an Engine running quickly, with rapid reversals of 
 the piston, that the valves should cut off the steam early in the cylinder, 
 and the exhaust also close early. The example we have given is con- 
 sidered an extreme amount of " lap " on a three-port valve. Other 
 proportions of " lap," less or more, follow the same principle : that is, if 
 the " lap " or cover be less, the steam will be longer on the piston before 
 it is cut off. The opening and closing of the exhaust will be in like 
 ratio. The traverse of the valve may be increased by a new eccentric, 
 having more throw, or by moving the rock-shaft stud nearer to the centre, 
 providing the valve-box be of sufficient length to enable the valve to 
 travel a longer distance in the same time, by which the ports will be 
 opened wider for the admission of steam to the piston than with its 
 former traverse ; and the steam will be cut off at the same point as 
 before, because the valve travels quicker. This is usually termed 
 " travelling over port." 
 
 This form and description of the three-port valve and slide is princi- 
 pally used for High-pressure Engines. Various may be the alterations 
 required, according to the width and distance of the ports and the length 
 of traverse, which may be either increased or decreased, if worked by a 
 rock-shaft. The makers of small portable Engines will find that 
 attention to the form and setting of three-port valves will be attended 
 with advantage by admitting the steam to the piston easily. They 
 should also allow plenty of room in the thoroughfares, so that in the 
 process of exhaustion there be no back pressure, that the speed of the 
 Engine may be increased when more power is required. At the Royal 
 Agricultural Show at Leeds, 1861, there was observable a general defect 
 
81 
 
 in this class of Engines want of speed of the piston, which could not 
 well be increased on account of the fly-wheel being too large. Defects 
 such as these are serious drawbacks upon High-pressure Portable Engines, 
 or to Engines of any other form. Attention to balancing the working 
 parts of an Engine steadies the working, and requires less matter to be put 
 and kept in motion to equalise the speed. If the pressure were increased 
 from 45Ebs to 70 or 805>s to the square inch (which might be safely 
 effected with small Boilers of the Portable class), the steam would be 
 used more expansively : consequently, less fuel would be used, and an 
 increased power obtained. We are aware that there is an objection to 
 high-pressure steam among agriculturalists ; but how that arises it is 
 difficult to understand, seeing that Railway Locomotives work steam at 
 from lOOlbs to 1505>s pressure to the square inch with perfect safety 
 exerting great power, and occupying little space. 
 
 THE D SLIDE VALVE. 
 
 This description of valve, which is in very general use for Condensing 
 Steam Engines, when first introduced was worked without " lap," or 
 extra cover, and the valve-boxes were generally of such a length that 
 they would not admit of the valve travelling over port, consequently, the 
 steam was admitted the whole length of the stroke, which caused the 
 exhaust side of the valve to be too late both in opening and closing. For 
 a long period Low-pressure Engines worked in the manner described ; 
 but as the property of the expansion of steam became better understood, 
 various methods were adopted whereby the D valve could be made to 
 work on the expansive principle. It was found that by enlarging the 
 valve-box to allow of more traverse, thus giving room for extra " lap," 
 the steam could be cut off at almost any portion of the traverse. This 
 fact was partially known previous to 1841 ; but in that year a Mr. 
 BOULD, cotton spinner, of Halifax, in Yorkshire, took out a patent for 
 " Improvements in Condensing Steam Engines," in which he describes 
 tlje D valve and the mode of " lapping." As it appears from his specifi- 
 cation that he clearly understood the subject of " lapping," and setting 
 valves, extracts from that specification, in his own language, will be 
 found of advantage. He says : 
 
 " My invention relates to the mode of arranging the valves (which 
 slide over the ports) of Condensing Steam Engines, in such a manner 
 that the exhaustion port shall be fully open at the time the piston has 
 completed its stroke, at either end of the cylinder, and at the same time 
 allow of the steam being worked expansively by means of the same 
 
 12 
 
82 
 
 Diagram No. 24. 
 
 Irom a High-pressure or Non-condensing Engine, with ," lap " on the Valve, 
 and V on the edge. 
 
 
 ~ -s 
 
 S g -3 
 1 I? 
 
 I 2 
 I -I I 
 
 ^ <D '-3 
 
 I -5 
 
 S g 
 
 Is I 
 I 
 I < 
 
 II 
 
83 
 
 I 
 
 valves. * In constructing and applying valves to Condensing 
 
 Steam Engines, the valves of which are worked by eccentrics, it is usual 
 to form the valves of such dimensions that they will only just cover the 
 ports or openings into the cylinder, or only very slightly exceed the 
 dimensions of the port ; hence, when the valves are moved, the ports are 
 simultaneously, or nearly simultaneously, opened and closed. * * * 
 By enlarging the size of the slides so that they will be much larger (at 
 least twice as large as the ports they work over), the induction valve may 
 remain closed during a considerable length of movement of the valves ; 
 hence it may be closed at any desired part of the stroke of the Engine, 
 and the exhaustion valve remain open to the condenser ; and what is 
 also very important, the exhaustion valve may be fully open at the ter- 
 mination of the stroke at either end of the cylinder, so that a good 
 vacuum may at the commencement of the stroke be obtained, and con- 
 sequently at the time the induction port is open for the flow of steam. 
 
 " Fig. 25 represents a diagram of a steam cylinder and valves, and 
 also the eccentrics and parts which work the valves. In Fig. 25 the 
 valves are shown in the position they would be at the termination of the 
 stroke at the upper end of the cylinder ; and it will be seen that the 
 exhaustion valve has passed away from the exhaustion port, and the 
 induction or steam valve has partially opened the induction port. * * 
 That is not necessary ; but if desired, it will be evident to the Engineer 
 that that might be done either by increasing the throw of the eccentric, 
 or by shortening the lever e, 1 to which the eccentric rod is attached. 
 
 " Fig. 26 shows a section of a steam cylinder and valves, and the lever 
 which works them, the eccentric which gives motion to the lever not 
 being shown the valves in this figure being in the reverse position to 
 that shown in Fig. 25. The valves a a are made of such length as to be 
 equal to three times the opening of the ports ; and it will be seen by 
 tracing the movement which will take place in the parts of Fig. 25, that 
 when the stroke in the upward direction has been completed, and the 
 steam or induction valve opened to the required extent, and steam 
 admitted above the piston, the steam or induction valve will be closed by 
 the time the piston has moved about one-third of its stroke ; but this 
 may be varied, and the exhaustion port will remain open, and the move- 
 ment of the eccentric, and the parts actuated thereby, will, near the end 
 of the stroke, close the exhaustion port at the upper end of the cylinder, 
 and bring the parts into the positions shown in Fig. 26 ; and it will also 
 be seen that these effects will be consequent on the enlargement of the 
 valves in respect to the ports over which they work, and the extent of 
 movement given to the valves, whereby one or other of the valves can be 
 moved for a considerable length whilst over its port, without uncovering 
 
84 
 
85 
 
 Figure No* 26. 
 An Enlarged Section of Steam Engine Cylinder with D Valves. 
 
80 
 
 that port, allowing the exhaustion port to be fully open at the time of 
 completing the stroke at either end of the cylinder. At Fig. 25, b is the 
 eccentric on the main shaft c, and the rod d and levers e and e, 1 for 
 moving the slides. These are of the ordinary construction, allowing only 
 for the quantity of motion given to the valves. And it is important to 
 call attention to the circumstance, of the distance over which the valves 
 are moved, as on that circumstance, combined with the length of the 
 valves, depend the beneficial results obtained. 
 
 " Figures 25 and 26 show the parts so arranged as to cause the valves 
 to move a distance equal to four times the depths of the ports ; and if it 
 were desired that the steam port should be opened fully, then the valve 
 would have to move five times the length of the depth of the port ; and in 
 case of making the valves less, to the extent of their being twice the length 
 of the depth of the ports. Then the movement given to them is to be four 
 times the depth of the ports to fully open the steam ports. The move- 
 ment ought not to be reduced three times the depth of the ports, as the 
 steam port will then be only half opened. It should be stated that 
 although I prefer to work the slides with an eccentric, it will be evident 
 that a crank may be substituted. * * * Although I have shown the 
 valves as being equal to three times the length of the depth of the ports 
 over which they work, yet I do not confine my claim thereto, as they 
 might be slightly increased, and even less extensive valves may be used, 
 varying the other parts accordingly ; but I have found there is little 
 advantage to be derived when the valves are not at least equal to twice 
 the length of their ports, measured in the direction of the movement of 
 the valves. What I claim is, the mode of constructing the valves of 
 Condensing Steam Engines, when worked by eccentrics or cranks, whereby 
 the exhaustion ports may be fully opened at the completion of the stroke, 
 and whereby steam may be cut off, and more effectually worked expan- 
 sively by the same valves as above described." 
 
 This description of the " lapping " and traversing of the D slide valve, 
 given by Mr. BOULD in the specification of his patent, is evidence that if 
 he was not the first inventor of the process, he was in advance of many 
 Engineers of the clay ; and there can be no doubt that the publication of 
 his specification supplied information which has enabled other Engineers 
 to improve the working of the Steam Engine. 
 
 There are other descriptions of cylinder valves than those described, 
 such as the long D, the trellis, the piston, and the single and double drop 
 valves, all of which are one and the same in principle. An Engineer 
 acquainted with the principle of the valves here explained will have no 
 difficulty in understanding all the various valves in use, and the modes 
 by which they are worked. For the latter, the eccentric movement is in 
 
87 
 
 most general use ; but there are also the movements of the cam, the 
 tappit, the crank, and the lever. 
 
 THE CORNISH OR DOUBLE-BEAT DROP VALVE. 
 
 This description of valve derives its name from its first being adopted 
 in Cornwall. In that locality Steam Engines are largely used for mining 
 and pumping purposes, and the piston of the Engine travels at a slow 
 rate. A valve, therefore, that could be closed or opened on the . steam 
 and exhaust sides separately, became a useful and important improve- 
 ment over the old " hand gear" single valve, and also over the three-port 
 or D slide valve. 
 
 Fig. 27 is a vertical section of a pair of side pipes of a Steam Engine 
 cylinder, with valves of the Cornish construction. These last are shown 
 in their respective positions, both on the steam and exhaust sides. The 
 steam from the Boiler enters the steam chest at B, and takes the direction 
 as shown by the arrows at C, entering both at the under and top sides of 
 the valve to the piston. F F are the thoroughfares to the cylinders. 
 The bottom valve C being open, allows the steam to enter the thorough- 
 fare F ; and the top exhaust valve D being also open, allows the used 
 steam on that side of the piston to escape from the cylinder through the 
 thoroughfare F, and through the valve D into the exhaust pipe E E, and 
 thence to the condenser. The bottom exhaust valve D being closed, 
 prevents the steam from passing from F to D ; and the top valve C 
 being also closed, prevents the exhaust steam from the cylinder F passing 
 through C to B. At each stroke or reversal of the piston, the valves 
 change their position. G G G G are the valve spindles connected to a 
 rod with arms, as shown by Fig. 27, which is a side elevation of the 
 cylinder and side pipes. 
 
 In Fig. 28 the cylinder I, and the valve chests K K, together with the 
 tappet P, and the projecting arms M M, attached to the main upright 
 valve rods, are sufficient to show the parts necessary to explain the action 
 of the Cornish valve. The tappet P is fixed to a horizontal shaft under 
 the floor of the Engine house, and makes exactly the same number of 
 revolutions as the crank shaft. Each valve has its separate spindle and 
 arm, and separate rod and tappet also. As the tappet shaft P revolves, 
 the full side of tappet P comes in contact with small pulleys fitted to the 
 bottom of the valve rods, and raises the valves from their respective 
 seats, according to the requirements of the case. Pulleys are used to 
 cause as little friction as possible in the working of the tappets, which 
 are four in number. The advantage in the opening and closing of the 
 
88 
 
13 
 
90 
 
 valves by this method consists in so forming the tappets that the steam 
 valve can be opened and closed at any required distance the piston may 
 have travelled giving every facility for cutting off the steam, either 
 gradually or suddenly, according to the description of work on the 
 Engine, or the amount of expansion of the steam required. 
 
 The exhaust valves have also separate tappets on the same shaft ; and 
 as they are required to keep open the valve nearly the full length of the 
 stroke, the tappet is so formed as to cause the valves to open and close 
 at the most advantageous times. 
 
 The Cornish Valve has two faces, or two inlets and outlets, as shown 
 by section of valve C and D, which gives a double opening for the 
 ingress or egress of the steam. It also admits of the exhaust valve 
 being raised much higher from its seat, so as to give a free and uninter- 
 rupted passage to the condenser. This form of valve possesses a decided 
 advantage over the single faced drop valve. When the tappet has raised 
 the valve to the highest point required, it again falls to its seat by its 
 own weight, and is kept there by the pressure of steam, until the tappet 
 again comes in contact with the pulley at the foot of the valve-rod, and 
 is again raised. 
 
 On reference to the illustration it will be seen that the exhaust valve 
 is larger than the steam valve, which, coupled with the extra height the 
 exhaust valve rises from its seat, gives free egress for the steam to the 
 condenser. With double-beat valves the steam can be kept longer on the 
 piston before exhausting, because the exhaust valve being large, allows 
 the steam to escape much quicker than the three-port, or D slide valve. 
 Where drop valves are used, and worked by a revolving shaft and 
 tappets, they are much easier to get at by the Engineer than the three- 
 port or D slide valve. Each tappet being separate, the valves can be 
 regulated separately, either by the shaping of the tappet's circumference, 
 or moving it partially round the shaft, so as to give more or less lead on 
 the steam or exhaust sides of the stroke j or to take off or keep on the 
 steam in the cylinder, according to the load and pressure : thus enabling 
 the Engineer to economise fuel by working his steam more expansively 
 when less power is required. In this form of valve there is often one 
 defect : the tappets are so formed as to allow the valve to drop upon its 
 seat too suddenly, causing much wear and noise. Were the tappets made 
 to allow the valves to be steadied on their seats, the valves would keep 
 steam-tight much longer than the present construction. 
 
91 
 
 IMPROVED SLIDE VALVE, WITH DOUBLE EXHAUST. 
 
 Fig. No. 29 is a representation of the Improved Slide Valve, with 
 double exhaust ; S and B are the valve chest, V the slide valve, P and 
 D the steam- ways to each end of the cylinder, and E the exhaust. It will 
 
 Figure No. 29. 
 
 be perceived that the valve has a considerable amount of lap, which will 
 cut off the steam early, and thus work expansively, proportionate to the 
 amount of lap. 
 
92 
 
 Fig. 30 is another representation of the same description of valve, 
 
 except with less lap. The same Figure denotes the same parts as Fig. 29. 
 
 It is well known that when " lap " is applied to the ordinary slide 
 
 Figure No. 30. 
 
 valve, the exhaust interferes too early with the action of the Engine, and 
 allows the steam to escape to the condenser or atmosphere before it has 
 had full opportunity of giving out to the piston the whole of its impelling 
 
93 
 
 force. This defect prevents that economy of fuel which would otherwise 
 be realised from the working of steam expansively. 
 
 With the slide valve of the ordinary construction, the exhaust has to be 
 set forward exactly in proportion to the amount of " lap " applied over 
 the other thoroughfare, where " lap " is sufficient to cut off the steam so 
 as to work with any considerable degree of expansion, and thus secure a 
 reduction in the consumption of coal. The exhaust interferes in the 
 manner above pointed out. To remedy this, many Engineers have 
 abandoned both the slide valve and the eccentric, and have adopted 
 other forms of valves, of a costly and complicated description ; but these 
 complicated constructions require too much nicety of management, and 
 are liable to derangement. 
 
 On reference to Figures No. 29 and 30, it will be observed that the 
 steam passages are changed, both in the side pipes and in the slide valve, 
 and that they have such a form given to them as to enable " lap " to be 
 conveniently applied on the exhaust side of the valve without any 
 hindrance to the speed of exhausting the steam. It will also be perceived 
 that two openings are provided for the steam to exhaust through, by 
 which a quick exhaust is accomplished with half the traverse that is 
 required by the old arrangement ; aud that, too, without such an enor- 
 mous amount of lead being given to the exhaust in advance of the 
 termination of the piston's traverse. 
 
 By reducing the traverse one-half, one half the amount of " lap " only 
 is required. In the improved valve very little " lap " on the exhaust side 
 will be sufficient to confine the steam longer in the cylinder, so as to 
 enable it to give out the whole of its expansive force upon the piston 
 before it is discharged to the condenser or to the atmosphere. The old 
 form of slide valve has been repeatedly tried to accomplish this, with 
 " lap " on the exhaust side, but in consequence of its long traverse, the 
 amount of " lap " required was so great as to choke up the thorough- 
 fares, and thus cripple the power of the Engine. 
 
 On examining Figure No. 30, an opening will be perceived, 
 sunk in the crossbar. This opening is provided specially for that small 
 portion of steam to escape which is left in the cylinder when the piston 
 approaches the termination of the stroke. A small opening such as this 
 is found to be necessary for the exhaust not wholly to close until the 
 crank has arrived near the dead centre, in order to prevent those expen- 
 sive breakdowns, which have been too frequently the result of the exhaust 
 closing too early, otherwise it would be difficult to start the Engine. 
 
 The short traverse of the valve, under the new arrangement, has the 
 advantage of admitting the steam on the piston slowly at the commence- 
 ment of the stroke, and that, too, without a V being provided for the 
 
94 
 
 purpose. The steam can therefore be cut off much sooner, and the 
 expansive principle thus becomes more practically accomplished with 
 slide valves of this construction. 
 
 In practice, it is found that with a Boiler pressure of SOlbs, an opening 
 of a quarter of a square inch in area per nominal horse is sufficient for 
 the valve to open to admit steam to the piston ; that a Boiler pressure 
 of 155)S requires one- third of a square inch; and that a Boiler pressure 
 of Tibs requires an opening of half a square inch for each nominal horse. 
 The exhaust requires one square inch area, or upwards, for each nominal 
 horse. Where the opening of the exhaust is less than this, the working 
 of the Engine will be crippled, and a loss of fuel the consequence. 
 
 For Locomotive Engines this form of valve will be of considerable 
 advantage, as the cut-off can be effected easily, and the exhaust opened 
 quickly, allowing the steam to depart with a greater speed than the 
 ordinary arrangement. 
 
 ON THE "SETTING OF STEAM ENGINE VALVES. 
 
 The proper " setting " of Steam Engine valves is perhaps the most 
 important duty the Engineer has to undertake, involving nicety of 
 calculation and mechanical accuracy, that the strain upon the Engine 
 may be equal throughout the whole length of the stroke. With the 
 assistance of the Indicator, the Engineer will be enabled to regulate Ins 
 valves, and employ the motive power to the best advantage, according to 
 the varying circumstances arising from the peculiar construction of the 
 Engine, the pressure of the steam, or the amount of work the Engine 
 may have to perform. From the fact that these circumstances of con- 
 struction, pressure, and work of different Engines do vary, it will at once 
 be apparent that one uniform rule for valve-setting cannot be laid down. 
 A perusal of the foregoing pages will have shown, by several of the 
 diagrams and the accompanying comments, that various alterations in 
 the setting of valves were required to improve and perfect the working of 
 the different Engines. Fuel is saved, and power increased or, in other 
 words, the power generated is rendered most available, when the valves 
 are set, so as to " beat " at the proper time. This setting will, for the 
 reasons before assigned, necessarily have to be regulated and modified 
 according to the pressure of the steam, the size of the steam ports, and 
 the different degrees of expansion. For example, see Diagram No. 31. 
 
 The corner A is the steam side of the piston. When the crank is at 
 the " plumb-centre " the valve is one-sixteenth of an inch open at the 
 bottom of the V, and this is called one-sixteenth of an inch lead on the 
 
9o 
 
 steam side. When the piston has travelled one-third the length of the 
 cylinder, the valve has been opened as much as is required, and it is then 
 
 closed having cut off the steam at one-third of the stroke, except the 
 
 V portion, which closes slowly. By the expansive action of the steam, 
 the piston is forced forward the remaining portion of the stroke. When 
 the piston arrives at the bottom of the cylinder, the crank is at the 
 
 Diagram No. 31. 
 
 Taken Jrom the Top of a Low-pressure Cylinder with D Valves. 
 B 
 
 11-5 
 
 '2-7 
 
 12-5 
 
 8. 
 
 11-6 
 
 14-7 
 
 16-7 
 
 17-7 
 
 17-7 
 
 12-7 
 
 12-8 
 
 13. 
 
 13. 
 
 13-1 
 
 13-3 
 
 13-5 
 
 17-7 
 
 11. 
 
 opposite " plumb-centre." The exhaust-valve is then open two-thirds 
 in some cases fully open, where the thoroughfares are small. This is 
 usually termed "the lead of the exhaust"; the steam having escaped 
 into the condenser, and a vacuum having been formed ready for the 
 return stroke. [See corners B and C.] The exhaust-valve closes when 
 the piston has travelled nine-tenths of the length of the cylinder : and 
 this is called the closing of the exhaust. [See corner D.] The little 
 
90 
 
 steam remaining in the cylinder when the exhaust is closed, is compressed, 
 and performs the office of a buffer checking the speed of the piston at 
 the termination of the stroke, ready for the return. This is called 
 " cushioning." The Engine works much easier when the exhaust closes 
 before the end of the stroke, more particularly when the piston travels 
 quickly, the steam between the piston and the cylinder top or bottom 
 becoming compressed care being taken that the amount of compression 
 be not too great, so as not to decrease the power, or strain the Engine. 
 
 Diagram No. 32. 
 Taken from the Top of the Cylinder of a Condensing Engine. 
 
 The compressed steam expands at the return stroke giving out power 
 proportionate to the compression. 
 
 The foregoing description applies to an Engine with D, or slide valves. 
 
 Tappet valves may be fixed to cut off the steam and open the exhaust 
 at any required distance the piston may have travelled in the cylinder, by 
 having the tappet made movable, or the faces formed as required. In 
 Diagram No. 32, the valves are tappet valves, and the steam is cut off at 
 
97 
 
 one-seventh the length of the cylinder. The expansive principle can thus 
 be made available for the varying amount of the work required, and 
 showing also that valve-setting must vary as the load on the Engine and 
 pressure vary. The equilibrium, or double-beat Cornish valves, can be 
 set to any degree of cut-off or exhaust. When the steam is cut off as 
 above, and D valves, or common slides, are used, an additional cut-off 
 valve, or a great amount of " lap " is required, and a great pressure in 
 the Boiler. " Lap " is added on the steam side of the valve, so that the 
 
 Diagram No. 33. 
 Taken Jrom the Top of the Cylinder of a Condensing Engine. 
 
 steam port is only partially opened, and also so that it will close sooner 
 in proportion to the amount of extra " lap." In such case the eccentric 
 requires moving forward in proportion to the extra " lap " added. The 
 pressure being great, and the steam port having sufficient room, allows 
 the pressure to come upon the piston gradually, during the time the valve 
 is partially open. The valve in that case does not open more than three- 
 eighths of an inch, the steam being cut off when the piston has travelled 
 
 14 
 
9S 
 
 one-seventh the length of the cylinder. Where the pressure in the 
 Boiler is 30Bbs to the square inch, the opening on the steam side, if of 
 one quarter of a square inch area for each nominal horse, will be quite 
 sufficient, or that area of opening for each 22 square inches area of 
 piston. The opening on the exhaust side should be at least one square 
 inch area for each nominal horse. Where the valve box is too short, and 
 where there is not room for " lap," the thoroughfares may be partially 
 made up to answer the purposes of " lap." 
 
 Diagram No. 33, is from an Engine which has valves of the D con- 
 struction. In this example, when the crank is at the " plumb-centre," 
 the steam side of the valve is one-sixteenth of an inch open, and the 
 exhaust- valve four-fifths open. The latter begins to close at eight-tenths 
 the length of the stroke. The " lap," or cover, of the valve is also long 
 at the end ; and this " lap," or cover, has an additional breadth of face 
 on the steam side greater than the width of the two " steam ports." 
 This is for the purpose of cutting off the steam early. In all cases 
 where " lap " is added, the eccentric should be moved forward, in the 
 exact proportion of the " lap," providing there were little or no lead 
 previously which will give the same proportion of lead to the exhaust. 
 Short slide valves, which are in general use for High-pressure Engines, 
 derive advantages from similar arrangements. The principle of " lap," 
 or cover, applies to both under similar circumstances. When the vacuum 
 is bad, the closing of the exhaust requires to be later because in conse- 
 quence of there being steam left in the cylinder uncondensed, the exhaust 
 requires to be kept open longer than would otherwise be necessary. 
 
 TWO ENGINES COUPLED, WORKING AT RIGHT ANGLES. 
 
 Diagram No. 34 is from one of two Engines coupled together, 
 belonging to Messrs. SELLERS, of Burnley. The pressure of steam in the 
 Boiler was 755>s per square inch. The valves are of the common D 
 construction, worked with the ordinary eccentric. 
 
 This case shows that valve-setting, with any description of valve, may 
 be made to cut off at any part of the stroke, when the steam in the 
 Boiler is of sufficient pressure. The valves and ports are not large, con- 
 sequently they require an increased pressure of steam. When the steam 
 is reduced to 455>s per square inch, the Engines begin to lose speed, 
 although there is not more than 2 libs per square inch upon the piston 
 when the Engines are at full speed, because the " lap " on the steam side 
 is so much that the port is not more than one-fourth open when the 
 valve is at the extent of its traverse. The whole value of valve-setting 
 and working expansively consists in having sufficient pressure in the 
 Boiler ; for in cases where the thoroughfares are small, the pressure 
 
09 
 
 Diagram No. 34. 
 Taken from the Top of the Cylinder of a Condensing Engine. 
 
100 
 
 makes up the difference. If the steam ports be large, expansion, or 
 cutting off in the cylinder, is effected with less pressure in the Boiler 
 and that, too, without expansion valves or complicated apparatus. 
 Expansion can be well effected with the ordinary valves, when the steam 
 is at sufficient pressure ; and in constructing new Engines there can be 
 no objection to having the valve boxes and thoroughfares so large that 
 the Engineer may be enabled to set his valves in accordance with the 
 varying pressure in the Boiler, or the load on the Engine. 
 
 Diagram No. 34, shows that the steam is cut off at one-sixth the length 
 of the stroke, without shock or vibration because the V in the valve 
 face allows the steam to be cut off early and admitted easily, thus main- 
 taining the pressure on the piston regularly. It will be perceived that 
 the exhaust closes as recommended in the instructions on valve-setting. 
 The steam side is a little late, allowing the cranks to have passed their 
 centres, before the steam is admitted on to the pistons. At this pressure 
 the valves are better without lead, so as to open steadily, and admit the 
 steam on easily ; for when a valve allows the pressure to come upon the 
 piston easily, it will be taken off in a similar manner. In all cases of 
 valve-setting this is an important point to be attended to what is 
 termed " easy steaming." In Marine Engines the valves have generally 
 too much lead. Were this point properly attended to, Marine Engines 
 would work much easier, and lasf much longer. 
 
 Cornish, or drop valves, which are usually opened and closed by 
 tappets, require to be accurately shaped according to the amount of 
 expansion. Expansion also depends upon the pressure of the steam in 
 the Boiler, and the dimensions of the ports. There is difficulty in forming 
 tappets to raise the valves easily, so that the steam may not rush 
 to the piston with too great a force while the crank is passing the centre. 
 To effect this, hoops are fitted to the inside of the seat of the valve, so 
 that when the valve is raised from its seat to admit the steam to the 
 piston, it has to pass through the openings cut in the rims of the valves. 
 Where the Indicator is used and understood, if the valve opens too 
 quickly, the fault can be at once ascertained. 
 
101 : \ , t > ,, , 
 
 PROPORTIONS OP A PAIR OP 28* NOMINAL PCRSE-POWER CONDENSING BEAM 
 
 ENGINES, SHOWING THE MODE IN WHICH" THE fofel&i A^.2 ^STJ 1 ' '' ' " / - \ 
 
 (See Diagram No. 35, taken from these Engines.) 
 
 Inches. 
 
 Diameter of Cylinders 28 
 
 Length of Stroke 60 
 
 Length of Steam Ports 14 
 
 Depth of Steam Ports 3| 
 
 Cover or Lap of Valve steam side 
 
 Breadth of Valve face 5| 
 
 Traverse of Valves 7| 
 
 Both Exhausts open at each end when the Valve is in the centre .. Of 
 
 Full extent of opening of Valve on steam side 0| 
 
 Full opening of Exhaust side (being 1| inches more than width of Port) 4 
 
 Lead of Valve on steam side ... .. 
 
 Lead of Exhaust at plumb-centre of Crank (being five-eighths of an 
 
 inch more than width of Ports) ... ... ... ... ... 4f 
 
 Traverse of Piston when the steam is cut off; or near one-third the 
 
 length of the Cylinder 19 
 
 Traverse of Piston when the Exhaust Valve begins to open ... 48 
 
 Vacuum 134 Ibs 
 
 Average pressure of Steam and Vacuum ... 12| 
 
 Number of Strokes per minute 30 
 
 Working hours per week 60 
 
 Tons of Coal consumed per week 14 
 
 Pressure of Steam in Boiler 30 Ibs 
 
 Injection Water 38 
 
 Water from Hot Well 90 
 
 Valves, long slides, with five-eighths of an inch bevel on the end of Valve, 
 in place of a V exhausting down the centre. 
 
 Two Beam Engines, coupled at right angles. 
 Indicated horse-power of the two Cylinders, 121. 
 
 * These Engines are at Bradford, in Yorkshire. They are called in that locality 25 horse- 
 power Engines being three horses less than the calculated rule. 
 
102 
 
 'Diagram No. 35. 
 Taken from a pah' of 2*8 Nominal Horse Power Condenshig Engines, at Bradford. See Page 101. 
 
103 
 A TABLE 
 
 SHOWING THE AMOUNT OF " LAP " REQUIRED FOR SLIDE VALVES, WHEN THE 
 STEAM IS TO BE WORKED EXPANSIVELY. 
 
 The traverse of the valves being ascertained, and also the amount of 
 cut-off desired, the following table shows the amount of " lap " required. 
 
 Traverse 
 of the 
 
 Valve in 
 inches. 
 
 The traverse of the piston where the steam is cut off. 
 
 n~fi~Ai'~rrAi~i"rii~flT 
 
 The required " lap." 
 
 21 71 3 ! ! ! 
 8 I II TS 
 
 i A 
 
 H 
 
 i i Hi m A' i 
 
 H ii I 
 
 A' 
 
 1* 
 
 1 1 i 
 
 1* 
 
 
 J_!^ 
 
 it 
 
 ill lAIJiJ 
 2 i ill' IA 1 
 
 i i n 
 
 1 1 f 
 
 if 
 
 
 2A 
 
 2A 2 | 11; 
 
 2A' 2 T \ 2 
 
 1 
 
 Ht! i 
 
 f 
 
 1 2A! 2 
 
 if 
 
 _LJ_rii JAIJLIJA 2 
 
 H I 2; 
 
 If 
 
 3A 3 T V; 3 
 
 if 
 
 f 3 T ^i 
 
 if 
 
 3A' 3 
 
 4 I 3if 3| 
 
 3 2if 
 
 if 
 
 2| 2 
 
 10 
 
 3 
 
 10J 
 
 11 
 
 4 3J 
 
 2 
 
 12 
 
 I 3] 
 
 21 Si 
 
 EXPLANATION OF DIAGRAMS. 
 
 WE now suppose the reader to have made himself practically conver- 
 sant with the principles involved in the construction of the Steam Engine, 
 and the construction of the common slide and other valves also of the 
 expansion of steam. If so, he will readily understand the explanations of 
 diagrams which here follow, and be able to apply the instructions therein 
 conveyed to his own case with advantage. 
 
 , - 
 
 ro? THB 
 
104 
 
 No. 36 Diagram was taken from the Engine at Castle Mills, Sheffield, 
 at the commencement of work after dinner. The Indicator was in 
 operation until the whole of the work was propelled by the Engine, the 
 diagram showing by the various lines, as the various machines were set 
 to work, the extra quantity of steam required, and the decreased vacuum 
 
 Diagram No. 36. 
 Taken from tlte Top of the Cylinder of a Condensing Engine. 
 
 in proportion to the extra quantity of steam to be condensed. The 
 different degrees on the diagram show, when measured, the power taken 
 by each machine as it was put in motion. A similar result could be 
 obtained where there are different rooms of machinery. Each room, as set 
 to work, would describe on the paper the extra quantity of steam required 
 to propel the machinery, and thus show the value or the cost of the 
 power in each room. By this method we are enabled to ascertain the 
 
105 
 
 power required for any particular machine, or number of machines, as 
 well as the most economical amount of power the Engine will exert, in 
 accordance with its construction, pressure of steam, size of condenser, 
 dimensions of steam-ways, and the quantity and temperature of condens- 
 ing water available. 
 
 The diagram shows the steam to be on the full length of the stroke. 
 The valves were D valves, without " lap," consequently the steam was 
 not cut off before the termination of the stroke. The pressure at the end 
 is lessened, the difference in this case being caused by the condensation of 
 the steam from the low temperature of the cylinder. 
 
 By Diagram No. 36 it is shown that the Engine has large steam-ways, 
 as indicated by the great quantity of steam to be condensed at the termi- 
 nation of the stroke. If the eccentric was moved forwards, and " lap " 
 added to the valve, less steam would be used, because the steam would 
 be worked expansively, and the exhaust would be closed earlier, making 
 a diagram rounded at the closing of the exhaust. The Engine would then 
 work better, and the consumption of fuel would be considerably reduced. 
 It will be observed that the various lines on the vacuum side are in 
 accordance with the amount of steam to be condensed. The greater the 
 quantity of steam, the less the amount of vacuum. 
 
 No. 37 Diagram was taken from an Engine belonging to Mr. JOHN 
 DAVISON, corn miller, Gateshead, which has since been destroyed by the 
 great fire at Gateshead and Newcastle-upon-Tyne. The pressure of steam 
 in the Boiler was lOEbs to the square inch above the atmosphere. This 
 Engine was supplied with cold water from the river Tyne ; therefore 
 that useful agent for the Condensing Engine was in abundance. The 
 valves were two short slides the pressure of the steam upon the back of 
 the valves pressing them to the face. These slides required considerable 
 power to work them a consideration that should not be lost sight of in 
 the construction of an Engine, particularly where high-pressure steam is 
 used. 
 
 This diagram gives an example of contracted steam-ways, and shows 
 the crippled state of the Engine. The average pressure upon the piston 
 is 7'2Ibs to the square inch, with steam in the cylinder near atmospheric 
 pressure at the commencement of the exhaust. Deduct the friction of 
 the Engine and shafting at the regular allowance, 3Ebs to the square inch, 
 and the available power remaining is 4Ibs to the square inch. Compare 
 this diagram with Diagram No. 19. The average pressure upon the 
 piston in No. 19 is 15Bbs to the square inch, with steam in the cylinder 
 at the commencement of the exhaust 65>s below the pressure of the 
 atmosphere. The one Engine has to condense fourteen, and the other 
 nine, making a difference of 30 per cent, in favour of No. 19 Engine, in 
 
 15 
 
IOC 
 
 the steam used and the steam to condense showing the superiority of 
 one Engine over the other. No. 19 Diagram shows 15fos to the square 
 inch, which, with 35>s for the friction of the Engine and shafting taken 
 off, leaves an available power of 12Ebs to the square inch upon the piston 
 or three times the power of No. 37, with 30 per cent, less fuel used, 
 and 30 per cent, less water for condensing. 
 
 Diagram No. 37. 
 Taken from the Bottom of the Cylinder. 
 
 4-3 
 
 6. 
 
 7. 
 
 7-6 
 
 8-1 
 
 9. 
 
 9-5 
 
 10. 
 
 11 
 
 Average vacuum, 7'21bs. 
 
 The maker of the Gateshead Engine prided himself upon the superiority 
 of this Engine over others, from the great noise the steam made on the 
 exhaust side he mistaking the noise for a good vacuum, when as shown 
 by the diagram, the contrary was the fact. At this mill there were two 
 Engineers at work, two Engines, two sets of Boilers, and more than four 
 times the quantity of fuel used than was necessary. Had the Engine, 
 No. 37, been properly constructed, it would have been able to propel more 
 than both Engines were propelling, to say nothing of the daily expen- 
 diture being at least three-fourths reduced, and leaving out of question 
 
107 
 
 the wear and tear, and the space uselessly occupied. Had either the 
 maker or the proprietor been practically acquainted with the Indicator, 
 it would have been of advantage to both. If the one had made a 
 mistake, the other would have been able to point out the defect, and 
 between them the Engine might have been put in proper working 
 condition. Instead of this, however, they were both satisfied with it in 
 its crippled condition ; the one believing that he had constructed an 
 Engine which could not be exceeded, and the other believing that his 
 Engine was one of the best. As a proof that it was a good one, several 
 people were called in to hear the good vacuum the Engine was making. 
 The noise produced by the exhaust was similar to the noise made by the 
 escaping steam at the top of a Locomotive Engine chimney. This is not 
 a solitary instance of this kind of Engineering, but a sample of what 
 may be frequently met with. 
 
 No. 38 Diagram was taken from an Engine belonging to Mr. RICKETTS, 
 Corn Miller, Sheffield. By this diagram the state of the Engine will at 
 once be apparent. The steam was too late, the exhaust was too late, 
 and also closed too soon. In this state the Engine worked for a con- 
 siderable time. There was a most irregular motion, causing the stones 
 to tremble, and the whole machinery to appear in an agitated state. The 
 Engine was consuming a great quantity of fuel, and by most parties it 
 was considered overloaded. The valves were of the conical description, 
 worked by revolving tappets. Several Engine-makers had examined the 
 Engine, and various were their conjectures. At length, as a remedy, one 
 of them applied several tons of metal to the rim of the fly-wheel. The 
 result was not as anticipated : the additional weight which had to be 
 propelled ! did not improve the working, and the conclusion come to, 
 after this alteration was, that the Engine was too small for the work it 
 had to do. Diagram No. 38 was taken when the Engine was in this 
 state. 
 
 Diagram No. 39 was taken from the same Engine, in the short space 
 of one hour after the Indicator had been applied. The tappets which 
 worked the drop valves had moved from their places, as will be seen on 
 reference to No. 38 Diagram. The tappets were adjusted, the Indicator 
 again applied, and No. 39 Diagram obtained. 
 
 Examine the difference : the improved vacuum the steam on at the 
 proper time, cut off at one-fourth the length of the stroke working by 
 expansion and the exhaust sooner. The average pressure of No. 39 
 Diagram is 10'86Ebs, and the average pressure of No. 38 Diagram 
 1 4-305)8 ; thus showing that the Engine, before the valves were properly 
 set, was consuming steam equal to 3 Jibs to the square inch to work itself 
 more than No. 39. The result of the alteration was, that the Engine 
 
108 
 
 consumed little more than half the fuel it did before, the stsnes run 
 steadily, the whole machinery at the proper speed y and sufficient surplus 
 power remained to have driven one-third more work. This case shows 
 pre-eminently the advantage and use of the Indicator over the guess- 
 
 Diagram No. 38. 
 Taken from the Top of a Condensing Engine Cylinder. 
 
 Steam 6'66R>s. 7-641bs. Vacuum. 
 
 6-66 Steam, 
 
 14'30 Average Pressure. 
 
 work of some Engine-makers and managers of Steam Engines. By its 
 use the real defects were at once laid bare, and the simple remedy 
 applied. An Engineer without an Indicator is like the Captain of a 
 ship at sea without a Compass. 
 
109 
 
 Diagram No. 40 was taken November 24th, 1855, from an Engine 
 belonging to Messrs. HYDE, SONS, AND SOWERBY. This Diagram is also 
 illustrative of our present subject, " Derangement of Valves " ; and as 
 there are numerous Engines working with valves set in a similar manner, 
 
 Diagram No. 39. 
 Taken from the Top of the same Engine as No. 38. 
 
 
 5-5 
 
 12-7 
 
 12-8 
 
 13. 
 
 11. 
 
 Steam, l'94ft>s. 8-92fts Vacuum. 
 
 1-94 Steam. 
 
 10-86 Average Pressure. 
 
 it is important that the facts and particulars of the case should be fully 
 entered into and attentively considered j because a mistaken opinion 
 exists amongst Engineers as to the cause of the irregularity which the 
 diagram exhibits. Many suppose that the irregularity of the figure is 
 
no 
 
 Diagram No. 40. 
 Taken from the Top of the Cylinder of a Condensing Engine. 
 
 O 7 
 
 o 
 
 111 
 
 
 
 19 
 
 11 
 
 121 
 
 12~6 
 
 129 
 
 150 
 
 15-1 
 
 lo 
 
 Steam, 6'54K>s. 
 
 11-40K.8 Vacuum. 
 6-54 Steam 
 
 17'94lbs Average Pressure of the steam on 
 the piston throughout the stroke. 
 
Ill 
 
 caused by the irregularity of action in the Indicator, arising from a want 
 of correctness in the working parts, or from the spring of the instrument 
 being too weak, In the present instance this idea prevailed ; and, as a 
 proof that the irregularity arose from this cause, other diagrams were 
 taken by a differently constructed Indicator, with the pencil projecting 
 at a right angle from the cylinder the barrel, or cylinder to which the 
 paper is affixed being detached from the body of the instrument. This 
 latter description of Indicator is not sensitive enough to show the true 
 action of the steam upon the piston of the Engine, because the pencil- 
 holder, with the pencil in fche position described, acts as a lever with a 
 motion opposed to the motion of the piston, and adds additional friction, 
 preventing a true tracing on the barrel of the Indicator. It thus arose 
 that the valves of the Engine from which Diagram No. 40 was taken 
 were in the state shown, because the Indicator formerly used did not 
 exhibit the irregularity made apparent when a larger and more sensitive 
 instrument was applied. It will be seen from the diagram that on the 
 steam side, at the commencement of the stroke, the steam is exerting a 
 pressure upon the piston of 19Ibs per square inch, the crank being then 
 at the plumb centre. As soon as the crank has turned the centre, and 
 the piston moved forward, the pressure of the steam is reduced to 13Bbs 
 per square inch. Then again it is raised to 14B)s, until the valve begins 
 to close nearly at the half-stroke. It will be observed that here another 
 irregularity occurs, which was said to be produced by the faultiness of 
 the Indicator. In many instances where similar diagrams are taken, 
 these irregularities are considered to arise from defectiveness in the 
 instrument. Of course it is much easier to blame the Indicator than to 
 explain its action. But to proceed with our description : the diagram 
 shows that the steam was forcing the piston of the Indicator upwards 
 against the spring, the resistance of which was equal to a pressure of 
 19S>s per square inch. Were not this so, how could the piston have 
 been sent up ? There must have been sufficient force to overcome the 
 resistance of the spring. This extra pressure at the beginning of the 
 stroke top and bottom has a very injurious effect upon an Engine, 
 and is the cause of more breakdowns and the breaking up of more 
 foundations, than almost all other causes put together. Were the art 
 of valve-setting more fully understood, so as to bring judiciously the 
 pressure of the steam to bear upon the piston, we should seldom hear 
 of Engines being stopped to repair breakdowns, which are now of 
 constant occurrence, from the cause just explained. 
 
 Wherever the Indicator makes a diagram similar to that of No. 40, 
 it will be found that there is a great strain upon the pillars, beam, centres, 
 crank, and other fixings of the Engine, which may be easily detected by 
 placing the hands upon the parts, and particularly upon the pillars. 
 
112 
 
 In Diagram No. 40, the pressure of the steam in the Boiler was 25Ibs 
 to the square inch. The diagram gives an average pressure throughout 
 the stroke of 17 '94^8 to the square inch. The average pressure of steam 
 above atmospheric pressure is 6'54K>s, with a pressure upon the piston 
 at the commencement of the stroke of 191bs per square inch above the 
 atmosphere. This extreme pressure being imparted to the crank at 
 "plumb centre," every part of the Engine was thereby subjected to 
 severe strain, there being on the beam, crank, and centres, a dead lift 
 twice during every stroke. This was the result of the valve having too 
 much lead, and of opening too quickly, so tbat the rush of the steam 
 struck the piston of the Engine with great force in the same way as 
 steam is applied to " the steam hammer." This caused the Engine to 
 tremble, and be, to all appearances, heavily loaded. At the closing of 
 the valve at half-stroke, the steam was reduced down too quickly. The 
 diagram shews that the valve closed too rapidly, causing vibration and 
 unsteadiness from the irregularity of the pressure upon the piston. This 
 diagram exhibits the evil of steam being cut off too quickly, instead of 
 being shut off regularly and easily : for it is as important for the steam to 
 be taken off easily as for it to be let on easily, that the steady working of 
 the Engine may not be disturbed. In the case we are considering, had 
 there not being a heavy fly-wheel to overcome the sudden changes 
 occasioned by the steam being thrown on and cut off too quickly, the 
 vibration would have been much greater. 
 
 This mode of setting valves, with too much lead, of which Diagram 
 No. 40 is a faint example, is a relic of the olden times, when low pressure 
 steam was used from 4Bbs to lOSbs per square inch. The practice is 
 not nearly so objectionable with low pressure as with high pressure 
 steam. Had there been a proper Indicator in use "at the time we speak 
 of, we should not now have had to combat the deep-rooted prejudices 
 and mistaken opinions which prevail amongst those who have been in 
 the habit of using the small Indicator with its pencil fixed contrary to 
 the traverse of the Indicator piston. We shall have to shew in our 
 further explanations of diagrams the evils which result from this 
 description of instrument, and the injury done by parties who, without 
 consideration, report on Steam Engines from diagrams taken by this 
 defective instrument. In so doing, we shall give practical examples and 
 facts to bear out our representations. We have only one object in view, 
 that of dispelling the errors of those who ought to be more fully 
 acquainted with the use and utility of a sensitive Indicator for valve- 
 setting ; and unless we give the names of the parties, and the circum- 
 stances we are commenting upon, others might be blamed. Since the 
 publication of the practical facts contained in the early editions of the 
 
113 
 
 Diagram No. 41. 
 
 Taken from the Top of the 
 
 Cylinder of the same Engine 
 
 as No. 40. 
 
 Steam, 9-10Bbs. 
 
 12-441bs Vacuum. 
 9-10 Steam. 
 
 21-54 Average Pressure of steam on the 
 piston throughout the stroke. 
 
114 
 
 " Steam Engine Explained," by J. HOPKINSON, a great change has taken 
 place amongst practical Engineers in the use of th'e Indicator, particu- 
 larly in valve-setting, where great nicety is required. 
 
 Diagram No. 41 was taken March 12th, 1856, from the same Engine, 
 and by the same Indicator, after the valves had been adjusted so as to 
 apply the steam easily at the commencement of the stroke, and also to 
 cut it off easily. We here see that instead of the corner of the diagram 
 on the steam side having a projecting point, the corner is rounded, because 
 the full pressure of the steam on the piston is not applied until the 
 crank has passed the centre, thereby preventing a dead lift at the 
 foundation, the beam, the centres, the crank, and the pin. It will also 
 be observed, that on the valve closing short of the half-stroke, it closes 
 regularly, and the diagram does not exhibit the variations which are 
 shown in Diagram No. 40. The pressure in the Boiler, when Diagram 
 No. 41 was taken, was 25Ebs to the square inch, the same as in No. 40 ; 
 average pressure on the steam side of the piston, as shown by the diagram, 
 is 9'lOBbs, and on the vacuum side, 12'44K>s : average, 2r54fcs per 
 square inch, being 3'60Ebs more than with Diagram No. 40 showing 
 the Engine to be exerting twenty per cent, more power, with less strain 
 upon the various parts than before. The greatest pressure in No. 40 
 Diagram is 18Ebs above the atmosphere, and that is after the crank has 
 passed the centre, that being a more favourable position to receive the 
 full pressure. After the valves had been altered, and more work put on 
 the Engine, the straining of the parts was comparatively removed, as 
 shown by the diagram ; another instance of the correctness of the 
 Indicator in describing the changes effected by alterations of valves. 
 
 No. 42 Diagram was taken from the same Engine, on August 23rd, 
 1856, by the same Indicator. Here will be seen a greatly increased 
 power over No. 40 Diagram. The average pressure of No. 40 Diagram 
 was 17-94S)s; of No. 41 Diagram, 21-54; and of No. 42 Diagram, 
 23'971bs ; being in the last case upwards of thirty per cent, more 
 power performed by the same Engine. In both the last cases, the strain 
 upon the parts was steady and regular, and the Engine was not nearly so 
 injuriously affected as when the steam was introduced in full force upon 
 the piston by the old method of valve-setting. The valves in No. 40 
 would by many be considered to be properly set ; and had the diagram 
 been taken with a small Indicator, such as that made by M'NAUGHT 
 and others, the irregularities would not have been shown, and the valves 
 would in that case have been passed as being correctly set. A state of 
 things like these is too often the case, and forms one of the obstacles to 
 the further improvement of the Steam Engine. When this defective 
 instrument is relied upon, where one set of valves are found to be as well 
 
115 
 
 Diagram No. 42. 
 Taken from the Top of the Cylinder. 
 
 Steam, lM3ft>s. 
 
 12'84ft>s Vacuum. 
 11-13 Steam. 
 
 23-97 Average pressure. 
 
116 
 
 set as in the instance we are illustrating, a greater number will be found 
 to be worse. With valves set as in the case of No. 42, it would be almost 
 impossible for a breakdown to occur from improper action on the part of 
 the Engine itself, as the strain is nearly equal throughout the stroke, 
 and without undue pressure upon the crank. 
 
 The benefit of a better knowledge in this important portion of an 
 Engineer's duty is apparent in the increased power in Diagrams Nos. 41 
 and 42, with very little increased cost of fuel, and with a great preven- 
 tion of strain upon the parts of the Engine, decreasing materially the 
 cost of wear and tear. This case also presents an example of an 
 Engineer who properly understands the use of the Indicator ; and it 
 makes manifest the advantages to be derived by employers from the use 
 of the instrument in the hands of a man competent to apply it. There 
 are Engineers who know, but who do not like to acknowledge, their 
 former opinions to have been erroneous respecting the improved Indicator; 
 and they have in some cases found it convenient to have one of the 
 latter to set valves by, because they have found the facts stated in the 
 " Steam Engine Explained " to have been of use to them. 
 
 In this Engine the valves were of the equilibrium conical form, 
 worked by FAIRBAIRN'S patent vertical revolving tappets. When the 
 valves were altered, hoops were fixed to the inside of the valve, about 
 one and a half inches deep, and of nearly the same diameter as the 
 opening of the valve seat. The mode of working the valves was the 
 same as before the alteration ; but openings, or thoroughfares, were cut 
 in the rim of the hoops of such form and dimensions, that when the 
 valves were raised from their seats, the openings in the hoops allowed 
 the steam to pass in proportion to the distance the valve was raised, by 
 which means the steam was admitted on to the piston at the pressure 
 required, and at any part of the stroke. The steam was also cut off in 
 the same manner. A similar effect may be produced by the tappets being 
 so formed as to raise the valves at any required speed : but the former 
 method is more permanent, and more easily accomplished than the other. 
 Tappets are liable to wear, and to move ; but the placing of a hoop 
 inside the valve is not liable to this defect. The plan of the hoop was 
 introduced by the Engineer above referred to ; and it will be found to be 
 a step in the right direction in the practical application of improve- 
 ments to the valves of Steam Engines. To the equilibrium or double- 
 cone throttle valves, the hoop has been found to be a valuable improve- 
 ment, producing steadiness in turning. 
 
 By studying the last three diagrams, those conversant with the 
 improvements therein shown, as having been made in the working of the 
 Engines, and of the increase of real power obtained from the same 
 
117 
 
 nominal force, will at once see the advantage of good management over 
 the bombast and guess-work of those who are ignorant of the use of 
 the Indicator, and who rely upon the reports made to them by the 
 Inspectors of "Boiler Associations," "Insurance Societies," &c., many 
 of which are found oftener wrong than right. Unless the modern system 
 of centralisation and company-making, intended principally to find places 
 for theoretical Engineers, be discountenanced, the further progress of the 
 Steam Engine will be much retarded. In the three instances, just referred 
 to, the recommendations in the reports from the Boiler Association were 
 found to be at variance with sound practice. Had the advice of the 
 Inspector been followed, the results would have been very different. In one 
 case, the suggestions in the report were adopted, to show the Inspector 
 his own want of practical knowledge. The result was, that before the 
 Engine had worked two hours, it had to be stopped, and the alterations 
 reversed. This led to the Inspector's services being dispensed with. 
 Where an Engineer is driving his Engines without using an Indicator, 
 proper working will be merely the result of chance. 
 
 In 1851, Messrs. HYDE, SONS, AND SOWERBY'S Engines were giving 
 415 indicated horse power, and consuming 83 \ tons of coal per week, 
 being 7 Jibs of coal per horse power per hour. This included the steam 
 for the mills, and other purposes requisite in the processes beginning with 
 cotton in its raw state, and delivering it in the woven piece. 
 
 In 1860, the same Engines were giving out 670 indicated horse 
 power, with a consumption of fuel of 94J tons per week ; that is, 
 under 5 Jibs of coal per hour per horse power : thus showing an increased 
 power of upwards of fifty per cent, obtained from the same Engines, 
 without the least alteration except the proper setting of the valves, and 
 increasing the pressure of the steam from lOBbs to the square inch in 
 1851, to SOBbs to the square inch in 1860. Since the above date, this 
 consumption of fuel has been further reduced by increasing the pressure 
 in the Boilers, casing the cylinders, and using the boiler-pressure in the 
 casings. 
 
 Nothing can be more clear than this case. The facts speak for 
 themselves. Had these Engines been compounded, and the pressure 
 increased in the same ratio, more fuel would have been consumed, to say 
 nothing of the great cost of compounding, and the increase of wear and 
 tear. Instead of this, the Engines only required the usual outlay in 
 repairs. There was no loss of time ; and the result was equally steady 
 turning to that of others whose expenses had been much greater. What 
 can this superiority of management be attributed to ? Simply to the 
 proprietors and the Engineer using and understanding the Steam Engine 
 Indicator ; for without this instrument they would not have been able 
 
118 
 
 Diagram No. 43. 
 Taken from the Top of the Cylinder oj a Condensing Engine. 
 
119 
 
 to increase and regulate their power, but would have been like many 
 continually guessing as to what the result of various alterations would be. 
 
 Diagram No. 43 was taken from an Engine belonging to Mr. SAMUEL 
 COOKE, of Mill Bridge. This is another example of improper valve- 
 setting, and of the most frequent cause of Engines breaking down. The 
 pressure of the steam in the Boiler, when this diagram was taken, was 
 30ft>s to the square inch. The diameter of the cylinder is 42 inches : 
 the thoroughfares each 20 inches long, and 5 inches wide. The valves 
 are two short slides. When the crank was at the " plumb centre," the 
 steam side of the valve was one-eighth of an inch open the full width, 
 and the exhaust side two and a half inches open. The pressure of the 
 steam upon the piston, when the crank was at the " plumb centre " was 
 201)s per square inch above atmosphere. When the crank had passed 
 the centre, the steam was reduced down to 5Ibs per square inch, which 
 was all the Engine required for the work it had to do ; and this amount 
 of pressure ought not to have been exceeded at any time for the amount 
 of power given out, unless the valves had been set to work the steam 
 expansively. As before observed, 20Ibs was brought upon the piston ; 
 but this 205>s did not act as steam giving out power to work the 
 machinery, but only as a force to break up the Engine. The great strain 
 thus cast upon the Engine would in time have caused the foundation to 
 give way j and there was every probability that either the beam, the 
 beam centres, or the crank would break. Such occurrences are not 
 un frequent. When they happen they are often ascribed to anything but the 
 proper cause ; and to prevent the recurrence of such disasters, stronger 
 parts to the Engine are substituted, as the others are deemed too weak 
 when, in fact, they were fully strong enough had the valves opened and 
 closed at the proper time, and at a proper speed. 
 
 In the case now under consideration, the valves were set and left 
 working without the Indicator having been applied, although the pro- 
 prietor had one in his possession. The result was, the valves were in the 
 state described. If the proprietor had not known the use and advantage 
 of the Indicator better than the Engineers who erected his Engine, in 
 all probability it would have continued in the state as left by them, until 
 it had tumbled to pieces. To remedy the defect, the valves required 
 more lap, and less lead on the steam side. With the size of steam-port 
 provided in this case, the opening would be too large at the beginning. 
 In such a case the required opening can be obtained and regulated by 
 cutting the valve edge in the form of the letter V, as shewn in the 
 following engraving. 
 
 The V portion is taken out at A, that the steam may be admitted upon 
 the piston gradually ; the dotted line shewing the amount of lead (or no 
 
120 
 
 lead) on the steam side when the crank is at the plumb centre, before 
 the valve opens to full pressure. 
 
 It will at once be seen that as the valve moves forward, the opening 
 increases in size. The crank will have passed the centre before the valve 
 has opened to the whole length of the thoroughfare, or so much as is 
 required ; the strain will thereby be taken off the Engine, and the piston 
 and crank will be prepared to receive the full pressure of the steam. By 
 these means the force exerted is properly applied, instead of being 
 expended in a dead lift upon the beam, the centres, and other parts of 
 the Engine itself. By adding more lap to the valve, the steam would 
 be sooner cut off, and more pressure thereby brought upon the piston 
 during the time the valve was open : thus working more expansively, 
 and consequently more economically. This ought to have been the case 
 
 No. 44. 
 
 A, the^V shaped grove made in the Valve edge. 
 
 in the instance under consideration, as there was SOIbs pressure in the 
 Boiler. We often find that the pressure in the Boiler is no criterion or 
 measure of the pressure in the cylinder, or the power the Enginejis 
 exerting ; and it often happens that where there are no means of indi- 
 cating the Engine, great discrepancies arise, and alterations are made 
 without data, or knowledge of the real state of the Engine. These 
 generally result in loss of fuel, in repairs, and in loss of time. 
 
 Diagram No. 45 is from the same Engine as No. 43. It will be 
 perceived that the steam expands to the lowest practical quantity, making 
 the most of it, and taking little water to condense with. It will be 
 apparent that the steam is not so soon on the piston, and that the 
 exhaust opens earlier. A very slight alteration made the difference as 
 before explained. The following letter was received with the diagram : 
 
121 
 
 Diagram No. 45. 
 'taken from the Top of the same Engine Cylinder ax No. 43> 
 
 IT 
 
122 
 
 " Liverscdye, near Leeds, May 29lh, 1861. 
 " Messrs. HOPKINSON & Co. 
 
 " GENTLEMEN, We have made the alteration (suggested by your Mr. HOPKINSON, 
 when last here) on the exhaust side of the valves. Except the wavy line on the steam 
 side, we think we have now a very fair diagram. Enclosed we beg to hand a copy, 
 
 " And remain yours respectfully, 
 
 "SAMUEL COOKE & SON/' 
 
 This example shows the necessity of the Engine being indicated every- 
 day, and the diagram put into a book for reference : so that should any 
 alteration take place in the working of the Engine or the machinery, or 
 even an increase of friction from bad oil or other causes, it is easily 
 detected. It is found out before it is visible in the amount of fuel 
 wasted ; and instead of the fuel being lost, the defect is remedied. This 
 is as it ought to be ; and were the practice followed up in all cases with 
 the same exactness as the time of starting and stopping the Engines, it 
 would be productive of great advantage to owners, and save Engineers 
 many a late hour now spent in the examination of Engines after the 
 work of others has terminated. It is as necessary for an Engineer to 
 have the working interior of his Engine laid open before him in a 
 diagram taken every day, as it is for him to see the exterior. Such a 
 practice, if regularly attended to, would save many " break-downs " and 
 expensive repairs, besides making the mind familiar with the internal 
 working of the Engine. Any alteration in the working of his Engine 
 would cause the Engineer to reason out the various changes that take 
 place from day to day. The advantage would become so apparent, that 
 he would continue to make improvements in the management and 
 working of his Engine, to economise the fuel, and regulate the speed. 
 These important benefits could all be attained with less labour than is 
 entailed by the hap-hazard and guess-work system. 
 
 Were Engineers taught the principles of indicating, and the nature of 
 the machine entrusted to their care, Inspectors of Steam Engines and 
 Boilers would not be required. These Inspectors are often more con- 
 versant with report-making than with the practical management of the 
 Steam Engine or Boiler. This system of extraneous inspection is retro- 
 grade in tendency. By its means responsibility is taken from the proper 
 parties upon whom it should be devolved, and placed in the hands of an 
 irresponsible body, managed according to official routine. Experience 
 has proved that this course does not result in progress ; for under it 
 there is the want of practical information and competitive power to 
 stimulate to progressive action. Many Steam Engine establishments and 
 Mill owners do not possess an Indicator, but rely upon the Inspector, who 
 may call once in three months with an instrument one adopted by 
 
123 
 
 official power, small in construction, and not very sensitive. To carry a 
 larger one would be too burdensome to the Inspector, although it is better 
 calculated to give a diagram that could be properly read. Under such 
 circumstances, the Engineer is left to grope his way, a state of things 
 that may be sustentative of officials, but it is not advantageous to the 
 manufacturers or the proprietors of Steam Engines, and it certainly is 
 detrimental to science. 
 
 If the amount of money expended in Lancashire and Yorkshire in the 
 formation and sustentation of " Associations " to remove responsibility 
 from where it ought to rest, had been expended in the scientific and 
 practical instruction of the working Engineers of those two counties, the 
 result would have been of a more valuable and permanent character : 
 for the latent talent which often lies concealed in humble positions would 
 then have a chance of development. Such a course, at any rate, would 
 have taught the working Engineers, as a body, to understand scientific 
 principles as applicable to their art and calling ; and also enabled them 
 to understand in practice the motive power entrusted to their care. 
 They would thereby have been enabled to understand the force and 
 bearing of " Reports" emanating from any "Association," and practical 
 science would thus have received a stimulus. Instead of this, however, 
 the working Engineer has been considered to be only a machine to 
 perform the functions prescribed by others, while the " Report "-maker 
 has been elevated into the position of " official " dictator. 
 
 The following letter from a working Engineer, on the principle of 
 expanding steam in one cylinder of a Non-condensing Engine, is another 
 proof of practical experience over "office" Engineering and official 
 routine : 
 
 " DucMnfield, April 5th, 1857. 
 " Mr. J. HOPKINSON. 
 
 " SIR, I wish to draw your attention to the particulars of an experiment with a 
 High-pressure Engine, which I have been conducting at the Central Works, Sheffield, 
 belonging to Mr. SHORTCLIFFE. The Engine had a nine-inch cylinder. The steam was 
 admitted during the whole length of the stroke, without expanding. The Boiler evaporated 
 900 gallons of water in five hours, with a weekly consumption of twelve tons of coal. 
 The pressure was 72fts per square inch in the Boiler, and yet they could not maintain 
 the speed of the Engine when all the work was on. 
 
 " The alteration which was made was simply replacing the nine-inch cylinder with one 
 of thirteen inches diameter,* and arranging the valves so as to cut off the steam before 
 the piston had travelled half the length of the cylinder, allowing the steam to expand 
 the remainder of the stroke. 
 
 " Sir, if I must state what was the general impression amongst the Engineers of 
 Sheffield, it was to this effect: that the new cylinder would drive the work, provided 
 there was an additional Boiler to supply it with steam. Only imagine their surprise, 
 
 * The area of the nine-inch cylinder is 63 inches, and of the thirteen-inch cylinder, 132$ 
 inches square nearly double the size. 
 
124 
 
 when they found that the Engine was driving the whole of the work at the proper speed, 
 and the Boiler only evaporating 415 gallons of water in five hours, at 551bs pressure 
 less by one-half than what was required before ; and this, too, with half the firing. 
 Instead of requiring another Boiler, we had half the present Boiler to spare for other 
 purposes. 
 
 " Since the alteration, additional work has been added to the Engine ; still the weekly 
 consumption of coal is only seven tons. 
 
 " This result, good as it is, is nothing more than you would expect from allowing the 
 steam to expand, over that of no expansion at all. 
 
 " In travelling the country, I find that a great number of owners of Engines have yet 
 to derive the advantages which others are deriving, by allowing the steam to expand 
 before leaving the cylinder. The reason of this is, that the means of carrying out expan- 
 sion and early exhaust are but little understood by those who ought to have a practical 
 knowledge on the subject. No doubt one great cause is a want of a more general know- 
 ledge of the Indicator, and its frequent application, in order to obtain that information 
 which it is enabled to convey respecting the interior of the Engine. 
 
 " The diagrams from the Condensing Engine I enclose will show you the former and 
 present state of the Engine alluded to. By the first figure it is apparent that the valves 
 were in such a state that 63 indicated horse power was the very utmost the Engine could 
 drive at the proper speed. It is now working 146 horse power, with a less consumption 
 of steam than before. 
 
 " I feel convinced that parties who wish to work their Engines with economy, can 
 accomplish that purpose by applying the Indicator, and studying the cause of its peculiar 
 delineations upon the paper. By this means they may obtain a sound knowledge of the 
 working of any Engine, and ascertain where improvement is practicable. 
 
 " I confess I am greatly indebted to that instrument, and remain, 
 
 " Yours truly, 
 
 "ENOCH GLEDHILL." 
 
 In the case referred to, great advantages have been derived from the 
 alteration detailed. Similar results would have been obtained by using 
 the small cylinder, with an increased pressure of steam, worked expan- 
 
 It is from the high-pressure expansive principle alone that we are 
 enabled to travel at great speed on railways ; and it cannot be contro- 
 verted that High-pressure Stationary Engines are, on the average for 
 the effects produced consuming more than double the quantity of fuel 
 to that consumed by Locomotives. So little do makers of High-pressure 
 Engines appear to understand the principle of using steam expansively, 
 that it is rare to meet with a High-pressure Engine with its valves set 
 to cut off the steam until very near the termination of the stroke. The 
 exhaust has almost invariably too little " lead," and the thoroughfares 
 are too small ; thereby entailing a back-pressure upon the piston or, in 
 other words, a loss of power. The hints here given will indicate to the 
 practical Engineer how the remedy is to be applied ; and if this be 
 effected judiciously, similar beneficial results to those detailed above will 
 follow. 
 
125 
 
 DIRECT-ACTING HOEIZONTAL CONDENSING STEAM ENGINES. 
 
 The Frontispiece of this book represents a 20 nominal horse power 
 Direct-acting Horizontal Condensing Steam Engine. It contrasts greatly 
 with the beam construction hitherto generally applied to Condensing 
 Engines. The great change now taking place with regard to the form, 
 construction, and working of Steam Engines, is a subject on which we 
 might dwell at great length ; but we here content ourselves by giving 
 this plate as an example of one of the departures from the ordinary con- 
 struction. The economy in construction and room, besides the advantage 
 of strength combined with simplicity there being fewer parts for wear 
 and tear should be inducements for its adoption. Should a breakdown 
 occur, the damage will be much less, compared to such an occurrence with 
 a Beam Engine, with its massive beam, connecting rod, pillars, &c. 
 
 On reference to the plate, it will be seen that the condenser and air- 
 pump are placed at the back end of the cylinder, in a place easy of access. 
 The air-pump is worked by links from the back piston-rod attached to a 
 bell-crank ; the cylinder valves are worked by the ordinary eccentric ; 
 and the Engine is governed in the usual way. The whole of the working 
 parts are bound together on one frame, and are, therefore, not liable to be 
 separated or strained by the foundation or building giving way. 
 
 By some parties it has been urged that the lower portion of the 
 cylinder of a Horizontal Engine wears more than the other parts. This 
 objection is not verified in practical working. With the cylinder placed 
 horizontally, it is found to work equally as well as a vertical cylinder and 
 piston and in the same way, too, wearing the cylinder a little wider in 
 the centre. Of course the horizontal cylinder requires, like all other 
 cylinders, to be made of a good quality of metal ; and then, when worked 
 with a metallic piston, there is little chance of any uneven wear. 
 
 All the parts of the Engine should be well balanced, to produce equal 
 motion, and the air-pump should have as short a stroke as convenient. 
 In a 40-horse Horizontal Condensing Engine at the works of the Messrs. 
 HOPKINSON, the stroke of the piston is 4ft. 6in.; the stroke of the air- 
 pump, single action, is 12in. The speed of the piston is 400 feet per 
 minute. There cannot be a doubt that Direct-acting Engines are the 
 best. Where there are numerous parts and great weights to be kept in 
 motion, more power is required than where the parts are fewer and 
 simpler. 
 
CHAPTER III. 
 
 THE STEAM ENGINE INDICATOR 
 
 HISTORY OF THE INSTRUMENT. 
 
 THE Instrument known by the name of the Steam Engine Indicator was 
 invented by the celebrated JAMES WATT a man whose name is indelibly 
 associated with the improvement of the Steam Engine. The genius of 
 WATT, combined with the facility of practical application possessed by 
 him in an eminent degree, enabled him to become one of the greatest 
 promoters of civilization, by placing at the command of his species a 
 motive power for manufacturing and industrial operations almost illimit- 
 able. Having by his improvements created, as it were, this new motive 
 power the Steam Engine an instrument to enable him to measure the 
 definite amount of the power of each Engine, and to indicate defects in 
 construction or working, became to him an indispensable requirement. 
 To supply that want, he devised what is at present known as the Steam 
 Engine Indicator. For a considerable period WATT kept the knowledge 
 of that useful instrument to himself ; but having at length to send a 
 Steam Engine abroad, and the responsibility of its erection and proper 
 working devolving upon the firm of which WATT was a member, he 
 furnished a mechanic, whom he sent out to superintend the erection of 
 that Engine, with an Indicator, having previously instructed him in the 
 art of its application : showing him that by its aid he could set the 
 valves of the Engine so as to produce the greatest effect from a given 
 quantity of impulsive power. It was to this circumstance that the 
 Engineering profession are indebted for this most valuable instrument ; 
 for, as will readily be imagined, a knowledge of the important aid it was 
 calculated to render to the practical mechanic having been thus imparted, 
 it could not long be kept secret, as WATT had hitherto kept it. 
 
 Since the period we speak of, the Steam JSngine Indicator has 
 received several minor, but important, improvements. In principle, it is 
 as it left the hands of WATT ; it is only in detail where alterations and 
 improvements have been made. Mr. SOUTHERN, an ingenious mechanic 
 in Messrs. BOULTON & WATT'S service, added the revolving cylinder, 
 with its attached paper and pencil, in place of the former traversing 
 board, to enable the instrument to register its own observations. Some 
 
127 
 
 makers have this revolving cylinder detached, or apart, from the other 
 portions of the instrument ; but Messrs. HOPKINSON find by experience 
 the test of all improvement that it is best to have the revolving 
 cylinder placed upon the steam cylinder of the Indicator, because it is in 
 that place the most convenient and firm for the operation which has to 
 be performed upon it. The pencil holder should be parallel to the cylinder 
 piston, as by that mode the instrument is rendered the most sensitive, 
 and, as a necessary consequence, the most correct indications are obtained. 
 This improvement, though a minor one in appearance, will hereafter be 
 shown to be of considerable importance. The difference of the indications 
 given by this instrument will be shown by contrasting its diagrams with 
 those given by the description of instrument called the M'Naught and 
 the Richards, on which the pencil operates at right angles to the traverse 
 of the piston, and where the revolving cylinder is detached from the body 
 of the instrument, and as in Richards' Indicator, where the pencil is fixed 
 to levers, to increase the size of the diagram. It will at once be seen 
 that a tremulous or unsteady motion of the pencil on the revolving 
 cylinder must impart a corresponding effect to the diagram, and is there- 
 fore calculated to lead to erroneous conclusions in the modes of valve- 
 setting points of extreme nicety as to the actual condition of the Engine, 
 or the minute alterations of its working parts which may be required to 
 secure the greatest effect with the least expenditure of power. 
 
 In several other particulars Messrs. HOPKINSON have improved the 
 Steam Engine Indicator for practical use. The instruments of their 
 manufacture are not flimsy in construction : and care is taken to have all 
 the working parts truly and accurately fitted, so as to produce true and 
 steady motion, with the least possible friction. Messrs. HOPKINSON have 
 no hesitation in asserting that in these particulars the instruments of 
 their manufacture will commend themselves, and that the practitioner 
 will find the new arrangement both convenient and useful. The diagrams 
 taken by the Indicator manufactured by the Messrs. HOPKINSON are 
 much larger than those usually taken by the instrument as commonly 
 constructed, while the vacuum side of the diagrams is never decreased, 
 whatever the pressure of the steam. The inch is divided into tenths on 
 the vacuum side, one-tenth representing 15) pressure per square inch. 
 This scale also applies to the steam side, for low pressures up to 25S>s. 
 For high pressures up to 751bs, the inch is divided into thirtieths, one- 
 thirtieth part of an inch representing 1 lb pressure. From this arrange- 
 ment the diagrams are much more readily divided and " read off," and 
 the defects in the working of the Engine more clearly shown, than by the 
 ordinary mode. Experience has shown that the working cylinder of the 
 Indicator should be drawn out of brass tubing. By this method it i 
 
128 
 
 much truer and harder, and if the piston be well ground in, the working 
 of the instrument will be more accurate, and assist the operator in setting 
 his valves with greater precision : advantages which cannot fail to be 
 appreciated by those for whose use and benefit the instrument has 
 been designed and improved. 
 
 At the Exhibition of 1862, an American Indicator was shown, and it 
 was stated in its prospectus, and also by a portion of the press, that it 
 possessed advantages over others in taking diagrams from Engines 
 working at quick speeds. No doubt the editors of these journals thought 
 BO, but had they been practically acquainted with the subject, they would 
 have known that the reverse was the fact that the difficulty of indica- 
 ting quick-speeded Engines with such an Indicator was the revolving of 
 the barrel backward and forward with a coiled spring, the American 
 Indicator being similarly constructed in that respect to the English ones, 
 and in other parts even much more complicated. 
 
 ADVANTAGES OF THE STEAM ENGINE INDICATOR. 
 
 WITH the Steam Engine Indicator a person may, at any time when 
 his Engine is in motion, ascertain the working condition of that Engine 
 find out its defects measure the power it is exerting ascertain the 
 difference of the pressure of steam upon the piston and within the Boiler 
 and, at every part of the upward or downward stroke, know the exact 
 pressure of the steam upon the piston at its various distances from the 
 bottom to the top, and from the top to the bottom : also ascertain the 
 amount of lead the valve is working with, on the steam and exhaust 
 sides. The Indicator thus enables the operator to calculate with accuracy 
 the pressure of steam exerted on the- average throughout the whole length 
 of the stroke and learn at what part of the cylinder the piston is when 
 the valve opens or closes, and what quantity (if any) of expansion he is 
 working with. At one glance of the diagram he will have the interior 
 the inner working of his machine, laid open as it were to view; its 
 good qualities and its defects registered on paper by the Engine itself : 
 thus dispensing with that system of guess-work often resorted to by 
 Engineers who pretend to know defects and derangements by the working 
 and beating of the Engine : a kind of fortune telling which many 
 proprietors of Steam Engines have had to pay dearly for. Without the 
 Indicator and some experience in its use, and without a proper knowledge 
 of the diagram when taken, no man ought to be allowed to alter or set 
 up a Steam Engine to work, or to take the management of its working ; 
 for it is otherwise impossible to know anything of the inner working of 
 
129 
 
 the Engine, excepting from mere conjecture. The Indicator is of as 
 much importance to the Engineer and the proprietor of an Engine as a 
 mariner's compass is to the captain of a ship navigating the seas. WATT 
 placed the greatest reliance upon this valuable instrument ; and it is not 
 too much to say that it contributed greatly to the success of his many 
 improvements in the Steam Engine. In a Condensing Engine, by means 
 of the Indicator, the vacuum can be minutely examined and its quality 
 ascertained. The instrument will also show the exact pressure and time 
 of the steam upon the piston the opening and closing of the exhaust 
 very important to the proper working of the Engine. It will enable the 
 Engineer to find the exact quantity of condensing water required, 
 according to the temperature and quantity of steam to be condensed. 
 In fact, by judicious observation, through the instrumentality of the 
 Indicator, the working of an Engine may, in most cases, be improved, 
 and the power increased, the quantity of fuel being at the same time 
 decreased. By means of this instrument the proprietor of a mill may 
 ascertain the whole of the power in operation, and the force required to 
 overcome the friction of his Engine and machinery; or the power required 
 for any single room, or any particular machine or number of machines. 
 Thus, where power is " let off," he may with accuracy determine the 
 value according to the power required. He may also calculate how much 
 more power the Engine will exert by the increase of pressure, or the 
 different degrees of expansion, according to the construction of his 
 Engine and the other circumstances of the case. An extended knowledge 
 of this instrument, therefore, becomes of importance to all connected 
 with the Steam Engine, whether as makers, owners, or managers : for 
 by its means they may obtain a correct knowledge of the working 
 condition of every description of Engine, and also ascertain how to 
 increase the power of each to its extreme limit of capability, with the 
 least expenditure of fuel. 
 
 DESCRIPTION OF THE STEAM ENGINE INDICATOR, 
 
 AS MANUFACTURED BY MESSRS. HOPKINSON. 
 
 PLATE No. 46 is an engraved representation of the Indicator, with 
 the additions and improvements made by Messrs. HOPKINSON. The. plug 
 A screws into the cylinder cover, or grease tap. The tap H forms a 
 communication between the cylinder of the Indicator and the cylinder of 
 the Engine. There is a small hole in the side of the tap, which opens 
 into the tap-plug ; and when the tap is open to the cylinder of the Steam 
 Engine and the Indicator, this small hole is closed by the plug being 
 
131 
 
 turned with its perfect side against the hole. When the tap is closed, 
 the connection with the Engine cylinder is cut off. The small hole in 
 the tap is then open through the plug to the cylinder of the Indicator, 
 so that any steam remaining between the piston of the Indicator and 
 the plug of the tap may escape into the atmosphere, and allow the pencil 
 attached to the piston of the Indicator to settle down to the atmospheric 
 line. The cylinder of the Indicator is fitted with a piston, the rod of 
 which is shown at R This piston is accurately ground into the cylinder, 
 thereby avoiding packing ; and, when properly oiled and cleaned, it is 
 steam-tight, except at very high pressures, where perfect tightness is not 
 required, as any small portion of steam which may escape cannot affect 
 the bulk of the pressure in the cylinder. From this construction, the 
 piston works freely, with little friction. The piston-rod R is attached to 
 the spiral spring S, within the tube or casing F, placed above the steam 
 cylinder of the instrument. This spring is so adjusted, that when the 
 piston index is forced one-tenth of an inch above the atmospheric line 0, 
 marked on the scale E, it represents 15) pressure of steam. The pointer 
 forced upward each tenth of an inch, up to 25 tenths, will represent as 
 many pounds pressure to the square inch. In the same way, when the 
 vacuum is formed in the Engine cylinder, the spring will be distended by 
 the pressure of the atmosphere upon the upper side of the Indicator 
 piston, and the piston will be forced downward as many tenths of an inch 
 as the degree of rarity, or the quantity of steam extracted from the 
 Engine cylinder in pounds per square inch below the pressure of the 
 common atmosphere. Affixed to the casing there is the scale E, with 
 the atmospheric line in the centre. The tenths below to 1/5, indicate 
 the vacuum ; and above to 25 tenths, the steam pressure above the 
 atmospheric pressure. The pencil-holder G is attached to the piston-rod 
 K, through an aperture cut in the casing F, to allow the pencil-holder to 
 move up and down with the piston-rod of the Indicator. The pencil can 
 be screwed backward or forward to obtain the exact length required, and 
 is adjusted by a spring to allow it to accommodate itself to any little 
 inequalities there may be on the revolving cylinder or the paper. In all 
 cases a soft and good pencil should be used. The less the pressure upon 
 the paper, the less the resistance to the free action of the piston I is the 
 revolving cylinder outside the casing F. This cylinder revolves on its 
 own axis. The paper on which the diagram is to be taken is fixed around 
 this cylinder, and held in its place by the clip J. On the bottom of the 
 cylinder there is a cord round the pulley R, which, after passing over the 
 swivel pulley A, is then attached to the radius-bar of the Engine. It will 
 be obvious that the traverse of the radius-bar will pull the cylinder so far 
 round as the string thus travels. On the relaxation of the string, caused 
 
132 
 
 by the descent of the Engine piston, the pulley will again take up the 
 cord, because an internal spring, similar to the spring of a self-winding- 
 up measuring tape, is enclosed in the revolving cylinder. The traverse 
 of the radius-bar pulls the cylinder one way round, and the spring the 
 other. By means of the cord attached to the radius-bar of the Engine, 
 there is thus produced a regular traversing motion of the cylinder I ; 
 and as the pencil presses at the same time against the paper affixed to 
 the cylinder, and also moves up and down with the Indicator piston, 
 which piston is propelled by the same force as the Engine piston the 
 pencil will describe a diagram according to the circumstances. The area 
 of the cylinder of the Indicator is a quarter of a square inch ; and each 
 tenth of an inch on the index represents lib pressure to the square inch 
 on the piston of the Engine. The spring S, compressed, shows the steam 
 pressure ; distended, it shows the atmospheric pressure upon the piston 
 of the Indicator caused by the formation of the vacuum in the Engine 
 cylinder, varying in accordance with the pressure of the uncondensed 
 steam left in the cylinder. This spring is so adjusted as to meet the 
 requirements of the pressure as it increases. When the steam exceeds 
 25Ibs to the square inch above the pressure of the atmosphere, there is 
 an additional spring enclosed in a case for higher pressures, up to 7 5 Bos 
 to the square inch or for a still further increased pressure, if required 
 which is to be screwed on to the top of the casing F. This additional 
 spring is represented at M. The piston-rod of the Indicator passes up 
 the centre of the spring M, when it is fixed on the top of the casing F, 
 and comes in contact with the top attached to the second spring so that 
 instead of the resistance of only one, there is the resistance of two springs 
 for high-pressure steam. On the scale E for high pressure, the distances 
 are marked thirty to the inch for steam above 25ibs, one-thirtieth of an 
 inch representing 1K> pressure to the square inch on the steam side. The 
 scale on the vacuum side is ten to the inch : or one- tenth of an inch 
 represents lib pressure to the square inch, whether with high or low- 
 pressure steam. It should be borne in mind that whatever may be the 
 pressure of the steam, high or low, when the Engine is a Non-condensing 
 or High-pressure Engine, the vacuum side of the Indicator is not 
 required. 
 
 Means must be adopted to get the proper extent of traverse of the 
 cylinder I. If the Engine be of the Horizontal or Cross-head kind, 
 sometimes a lever is affixed to the cross-head of the piston, and the 
 string from the Indicator attached to that lever at the requisite distance 
 for the traverse required. Sometimes a stand with a moveable pulley is 
 fixed to the Engine cylinder-cover by one of the bolts, to carry the string 
 from the radius bar of the Engine to any part of the cylinder where the 
 
133 
 
 Indicator may be fixed. With a Beam Engine, however, the Indicator 
 is best fixed under the radius bar into a proper tap made for the purpose, 
 screwed into the cover, or the bottom, of the Engine cylinder, where it 
 can remain as a fixture ready for use at any time. For Locomotive 
 Engines another and larger pulley may be attached, the circumference of 
 which should be equal to the length of the stroke of the piston. The 
 string may in that case be fixed direct to the cross-head or slide of the 
 piston rod. The large pulley on the barrel of the Indicator will give 
 out a sufficient length of string for one stroke of the Engine. 
 
 For Engines working at higher pressures than 75K>s, say as high as 
 SoOIbs per square inch, the Indicator is provided with another spring 
 similar to the 75Ib spring, and attached to the instrument in the same 
 manner. Each case enclosing the spring to be used has marked on the 
 outside the amount of pressure the spring will work up to. The 
 measuring scale accompanying the Indicator is also so marked, that any 
 figure taken by any of the three springs can be measured by it ; thus 
 dispensing with more than one portable scale. The 25B6 spring is at all 
 times a fixture, enclosed in the barrel of the instrument. The other 
 springs require to be attached to the provision made at the uppermost 
 part of the instrument for them. 
 
 HOW TO AFFIX AND USE THE INDICATOR. 
 
 BE particular before using the Indicator that the parts are well 
 cleaned that the piston of the instrument freely vibrates in the cylinder 
 and that all the working parts are carefully oiled with clean sperm 
 oil. If the instrument be new, let it be worked a few days on the Engine, 
 and be well oiled and cleaned three or four times each day. To affix it, 
 first screw the plug of the Indicator into the grease-tap, or into a tap in 
 the cylinder cover provided for the purpose : or to the bottom of the 
 cylinder, into a tap there inserted. The Indicator will work horizontally 
 as well as perpendicularly. When the plug or tap is thus fixed, open the 
 tap, and blow the steam through, so that any dirt which may have 
 accumulated may be blown away, instead of being sent into the cylinder 
 of the instrument. Then screw the Indicator on to the plug, or tap. 
 Take one end of the string which is wound round the grove of the pulley 
 on the bottom of the revolving cylinder, and connect it with a string on 
 the radius bar of the Engine, if it be a Beam Engine. If a Marine 
 Engine, or Cross-head Engine, attach to some convenient part which will 
 give the string the requisite traversing motion, which must be from the 
 direct action of the stroke, or the piston's traverse. The string must be 
 so adjusted as to pull round the cylinder of the Indicator only about 
 
134 
 
 three-fourths of a revolution. There is a stop or catch to prevent the 
 cylinder being pulled round too far. On the string to be attached to the 
 radius bar, there is a small brass plate, called a running loop. By 
 pulling this loop backward or forward, the proper length of the string 
 may be easily obtained, without detaching either from the Engine or the 
 Indicator. When the strings are properly adjusted, unhook them, and 
 open the tap between the cylinder of the Engine and the cylinder of the 
 Indicator to allow the Indicator-piston to be worked a few strokes, so 
 that the temperature of the cylinder of the instrument may be raised to 
 that of the Engine cylinder. Then affix the paper round the moveable 
 cylinder. When the paper is properly affixed, close the tap previously 
 opened. The piston of the Indicator will then settle with the index or 
 pointer opposite the atmospheric line 0. Put down the pencil upon the 
 paper, taking care that the pencil does not press too much on the paper 
 fixed on the cylinder. By means of the adjusting screw of the pencil- 
 holder, the required amount of pressure upon the paper can be obtained 
 to trace the diagram. When all else is ready, connect the two strings 
 together by the hooks on each end. The traverse of the string attached 
 to the radius bar of the Engine, will pull the revolving cylinder as far 
 round as has been arranged for ; and its own internal spring will cause 
 it to recede back again with the return stroke of the Engine. During 
 these motions the pencil will make a line on the paper round the 
 cylinder. This line is called the atmospheric line. When that line 
 is well defined, open the tap gently, so as to make a connection between 
 the cylinder of the Engine and the cylinder of the Indicator. The piston 
 of the Indicator will then partake of the motion, and travel up and down 
 with the piston of the Steam Engine, each stroke of the Indicator being 
 exactly that of the stroke of the Engine both being propelled by the 
 same force. By these motions a diagram will be traced on the paper of 
 the revolving cylinder by the pencil. Then shut the tap and disconnect 
 the cord. Take off the paper, and the diagram will be found delineated 
 thereon. By the aid of the scale sent with the Indicator, or the one 
 affixed to the instrument, or by means of a common rule, the distances 
 on the diagram from the atmospheric line on the steam side can be 
 measured, which will give the exact pressure of steam per square inch, 
 upon the piston of the Engine. Pursue the same means with the vacuum 
 side of the diagram, and the amount of vacuum obtained, and also the 
 quantity of uncondensed steam left in the cylinder, will be ascertained. 
 
 Thus, every change and every deviation of the Engine will be exhibited, 
 including those of expansion, lead, traverse of the valve, and closing of 
 the exhaust. Expansion produces, to all appearance, an irregular or 
 defective diagram (see Diagram No. 19); but this is not the case, 
 
135 
 
 because the diminished pressure of the steam at the end of the stroke, or 
 at the termination of the piston's descent, is much below the pressure of 
 the atmosphere, thereby reducing the steam to a low degree, which is 
 more than compensated by the saving of fuel. A very little lead of the 
 valve is required if the pressure be high. A diagram with the steam 
 corner rounded shows the valve to have little or no lead, the steam being 
 admitted upon the piston easily. A diagram square and pointed shows 
 the valve to have too much lead, that it opens too quickly, admitting 
 the steam upon the piston with too great a force before the crank is in a 
 proper position to receive it. This will in most cases cause the Engine to 
 tremble, and, by consequence, the Indicator also. Too much rounded at 
 the commencement of the exhaust corner shows also a defect for want of 
 lead, or a quicker opening of the valve, or longer traverse of the valve on 
 the exhaust side. In a great many instances the steam passages are too 
 small. When that is the case, the exhaust valve ought to be fully open 
 when the crank is at the plumb centre. If the diagram be square at the 
 termination of the exhaust, the valve closes too late. It would be better 
 for the Engine were the valve to close sooner, more particularly if the 
 speed of the Engine be great. Then the diagram would show a rounding 
 at the bottom corner (see Diagram No. 19). This is important for the 
 steady working of the Engine preventing, in many instances, a rapping 
 noise in the centres, which is often mistaken for loose cotters, or steps. 
 The closing of the exhaust before the termination of the stroke, is called 
 " cushioning the piston." This will have to be regulated according to 
 the speed of the Engine. The exhaust should be closed when the piston 
 has to travel one-tenth the length of the entire stroke. The piston and 
 most of the working parts of an Engine having to be reversed, require to 
 be brought to a stand before the return stroke. The steam left in the 
 cylinder will be compressed, and check the speed of the piston at the 
 end of the stroke. The elasticity of the compressed steam between the 
 bottom or the top of the cylinder and the piston, is ready, by its force, 
 to commence the return stroke with ease, preventing an undue strain 
 upon the Engine. The steam side of the valve does not require to be as 
 forward as when the exhaust is open the full length of the stroke, because 
 the compressed steam between the piston and the top or bottom of the 
 cylinder will act with a force according to its compression on the return 
 stroke. For a very quick speed of the piston, the opening on the steam 
 side requires to be earlier, and as much steam admitted before the stroke 
 is completed as will check the speed, and act as a cushion or buffer to 
 the piston. If the valve be of the D kind, or if a tappet valve, it should 
 be constructed so as to admit the steam on easy, before the valve opens 
 full port. The Engine will in that case work much steadier with less 
 
136 
 
 strain upon it. When the steam side of the valve has too much lead 
 a serious defect, which has already been noticed a rapping takes place. 
 This is too often the result of imperfect valve-setting, and causes the 
 Indicator to rebound by the suddenness of the pressure upon the piston, 
 giving to the diagram an irregular line on the steam side. This irregu- 
 larity is too often attributed to defection in the instrument, instead of 
 the real cause, viz. : too much lead of the valve, and opening too 
 quickly. In the working of an Engine, and in the taking of a diagram, 
 care should be exercised to ascertain whether any defect of this kind 
 exists, or an erroneous conclusion from the appearance of the diagram 
 may be the result. 
 
 We fearlessly assert, that if either the Manchester, or any other 
 Association, continue to work to the indications given by such a class of 
 instrument as they have hitherto employed, they are liable to serious 
 mistakes, particularly where high-pressure steam is used. And then, the 
 system adopted may be objected to on principle. " Office-Engineering " 
 has not brought the Steam Engine to its present state of efficiency ; nor 
 has the cotton manufacture grown to its present national importance 
 under red tapism, or official routine. It has acquired its status by fair, 
 free, and unshackled competition, independently of all " authority"; and 
 if the continued progress of the Steam Engine is desirable and worthy of 
 being promoted, that progress can only be secured by Engineers remaining 
 free from divided responsibility the industrious Engineer left at liberty 
 to apply correct principles to sound practice without the fear or favour 
 of official prejudice. 
 
 On the occasion of a recent vacancy for the Chief- Inspectorship of 
 the Manchester Association, Mr. EDWAED INGHAM, of Oldam, a prac- 
 tical Engineer, was one of three candidates selected by the Committee 
 as most eligible for the office, and, we believe, was placed second in the 
 vote. The following letter received from him, treating upon this branch 
 of our subject, we here give, as corroberative of the remarks made : 
 
 " Croft Bank Mills, Oldham, Oct. 20^, 1857. 
 " Mr. HOPKINSON : 
 
 " SIR, Last night, in our Lecture-room, we had a most interesting discussion on 
 the comparative merits and demerits of ' MCNAUGHT'S versus HOPKINSON'S Indicator." 1 
 I endeavoured to shew that most of the objections raised against HOPKINSON'S were 
 based upon prejudice and false notions. 1 told them how I myself had been deceived 
 with respect to the weight and area of the piston ; how you had kindly and lucidly 
 explained to me the fallacy of those notions; and how we were all of us apt to form 
 erroneous notions when led by the judgment of others, without examining for ourselves. 
 I was surprised to find that many in our Association had long entertained correct notions 
 with respect to the sensitiveness of your Indicator, but had not had the moral courage 
 to enunciate their views in opposition to currently received notions, until some one, upon 
 
137 
 
 whose authority they placed some little weight, had the courage to express similar views 
 to their own. The moment some one whom they durst venture to chime in with* 
 advanced similar ideas to those they had entertained for a long time, they began to give 
 vent to their pent-up feelings, which before they durst not even moot, because different 
 to the views entertained by the majority. I assure you we had a large number present 
 who for a considerable length of time have looked upon your Indicator as giving a truer 
 index of the internal workings of the Steam Engine than any other. I hope you will 
 send me your work as early as conveneint ; I shall then, perhaps, be able to discover 
 some other important features, upon which I and the rest of my fellow Engineers may 
 have entertained somewhat mistaken notions. 
 
 " I am, 
 
 " Yours most respectfully, 
 
 "EDWARD INGHAM." 
 
 We have often been called in to deal with cases where the Engines 
 have been labouring under difficulties. One instance was at Messrs. 
 ADSHEAD BROTHERS, at Staleybridge. Here we found the Engines 
 labouring under extraordinary difficulties 605>s pressure upon the 
 piston, and a lifting at the centres sufficient to break the Engines down. 
 After indicating, and comparing diagrams with those sent in by the 
 Manchester Association, we found that those taken by the larger arid 
 more sensitive instrument were just the reverse of the diagrams of the 
 Association, as it regarded the working of the Engines and the setting 
 of the valves. The cause of the tremendous strain on the Engine was 
 at once made apparent by the large Indicator. The valves were re-set, 
 and the Engines are now in proper working order. 
 
 In very many instances we have demonstrated the superiority of the 
 larger and more sensitive instrument, as a real Indicator, to that of the 
 construction used by the Manchester Association. We have proved this 
 by altering the Engines, showing the Engineers the various stages of the 
 process taking diagrams at each slight alteration until the Engines 
 were brought, so far as regards their working, into a state of comparative 
 perfection : showing also, at the same time, that the small Indicator 
 would not indicate the difference of the changes made. The American 
 Indicator is of even worse construction than that used by the Manchester 
 Association. 
 
APPENDIX: 
 
 CONTAINING 
 
 TABLES AND OTHER INFORMATION CALCULATED 
 
 TO BE OF SERVICE TO 
 
 ENGINEERS AND OTHERS ENTRUSTED WITH THE 
 MANAGEMENT OF THE STEAM ENGINE. 
 
TABLE. 
 EXPANSION OF AIR BY HEAT: 
 
 SHOWING THE INCREASE OF BULK IN PROPORTION TO THE INCREASE 
 OF TEMPERATURE. 
 
 Fahrenheit. 
 
 Bulk, i Fahrenheit. 
 
 Bulk. 
 
 Ternp. 
 
 32 
 
 Freezing Point 1000 Temp. 75 
 
 1099 
 
 
 
 33 
 
 1002 
 
 76 
 
 Summer Heat 1101 
 
 
 
 34 
 
 1004 
 
 77 
 
 1104 
 
 
 
 35 
 
 1007 
 
 78 
 
 1106 
 
 
 
 36 
 
 1009 
 
 79 
 
 1108 
 
 
 
 37 
 
 1012 
 
 80 
 
 1110 
 
 
 
 38 
 
 1015 
 
 81 
 
 1112 
 
 
 
 39 
 
 1018 
 
 82 
 
 1114 
 
 
 
 40 
 
 1021 
 
 83 
 
 1116 
 
 
 
 41 
 
 1023 
 
 84 
 
 1118 
 
 
 
 42 
 
 1025 
 
 85 
 
 1121 
 
 
 
 43 
 
 1027 
 
 86 
 
 1123 
 
 
 
 44 
 
 1030 
 
 87 
 
 1125 
 
 
 
 45 
 
 1032 
 
 88 
 
 1128 
 
 
 
 46 
 
 1034 
 
 89 
 
 1130 
 
 
 
 47 
 
 1036 
 
 90 
 
 1132 
 
 
 
 48 
 
 1038 
 
 91 
 
 1134 
 
 
 
 49 
 
 1040 
 
 92 
 
 1136 
 
 
 
 50 
 
 1043 
 
 93 
 
 1138 
 
 
 
 51 
 
 1045 
 
 94 
 
 1140 
 
 
 
 52 
 
 1047 
 
 95 
 
 1142 
 
 
 
 53 
 
 1050 
 
 96 
 
 Blood Heat 1144 
 
 
 
 54 
 
 1052 
 
 97 
 
 1146 
 
 
 
 55 
 
 1055 
 
 98 
 
 1148 
 
 
 
 56 
 
 Temperate 1057 
 
 99 
 
 1150 
 
 
 
 57 
 
 1059 
 
 100 
 
 1152 
 
 
 
 58 
 
 1062 
 
 110 
 
 Fever Heat 112 1173 
 
 
 
 59 
 
 1064 
 
 120 
 
 1194 
 
 
 
 60 
 
 1066 
 
 130 
 
 1215 
 
 
 
 61 
 
 1069 
 
 140 
 
 1235 
 
 
 
 62 
 
 1071 
 
 150 
 
 1255 
 
 
 
 63 
 
 1073 
 
 160 
 
 1275 
 
 
 
 64 
 
 1075 
 
 170 
 
 Spirits Boil 176 1295 
 
 
 
 65 
 
 1077 
 
 180 
 
 1315 
 
 
 
 66 
 
 1080 
 
 190 
 
 1334 
 
 
 
 67 
 
 1082 
 
 200 
 
 1364 
 
 
 
 68 
 
 1084 
 
 210 
 
 1372 
 
 
 
 69 
 
 1087 
 
 212 
 
 Water Boils 1375 
 
 
 
 70 
 
 1089 
 
 302 
 
 1558 
 
 
 
 71 
 
 1091 
 
 392 
 
 1739 
 
 
 
 72 
 
 1093 
 
 482 
 
 1919 
 
 
 
 73 
 
 1095 
 
 572 
 
 2098 
 
 
 
 74 
 
 1097 
 
 680 
 
 2312 
 
IV. 
 
 IMPERIAL STANDARD MEASURES. 
 
 L MEASURE OF LENGTH. 
 12 inches 1 foot. 
 36 3 1 yard. 
 
 198 16J 5J 1 pole or perch. 
 7920 660 220 40 1 furlong. 
 63360 5280 ., 1760 320 8 1 English mile. 
 2240 1 Irish 
 
 1984 1 Scotch 
 
 SPECIAL MEASUKES OF LENGTH. 
 
 Nautical Measure. 
 1 nautical mile ... 6082-66 feet. 
 
 3 miles 1 league. 
 
 20 leagues ] degree. 
 
 Land Measure. 
 
 7-92 inches 1 link. 
 
 100 links 1 chain. 
 
 80 chains 1 mile. 
 
 69-121 miles 1 geo. deg. 
 
 360 degrees = earth's circumference 
 
 6 feet = 1 fathom used in measuring ropes, chains, &c. 
 
 2. MEASURE OF CAPACITY. 
 
 General Measure of Solidity. 
 
 1728 cubic inches ...... 1 cubic foot. 
 
 27 cubic feet ...... 1 cubic yard. 
 
 42 cubic feet ...... 1 ton of shipping. 
 
 3. IMPERIAL GALLON MEASURE FOR LIQUIDS, CORN, &c. 
 
 WATER. 
 Cubic Inches. Ibs. av. 
 
 8-665 & 
 34-659 1J 
 69-818 2J 
 277-274 10 
 554-548 20 
 2218-19 80 
 17745-5 640 
 
 1 gallon 
 
 
 1 
 
 1 gill. 
 4 1 pint. 
 8 2 1 
 32 8 4 
 64 16 8 
 256 64 32 
 2048 512 256 
 
 of sea water weighs . . . 
 oU ... 
 proof spirits 
 
 quart. 
 
 1 
 
 2 
 8 
 64 
 
 ... JO 
 ... 9 
 ... 9 
 
 gallon. 
 1 peck. 
 4 1 bush. 
 32 8 1 qr. 
 
 32Ibs avoirdupois. 
 32 
 3 
 
 Thirty-two gallons of proof spirits in winter will, without being 
 diluted, measure thirty-three in summer. 
 
 All fluids expand with heat, and contract with cold down to 40 
 degrees, but expand when freezing. 32, freezing point ; 56, temperate 
 heat ; 76, summer heat ; 96, blood heat ; 112, fever heat ; 176, spirits 
 of wine boil j 2 1 2, water boils, when the pressure of the atmosphere is 
 155>s to the square inch ; if the pressure be less, water boils at a less 
 temperature. 
 
 These temperatures are Fahrenheit, by which we are guided in England. 
 The centrigrade rule is used in France, where the freezing point is zero, 
 or 0, and the boiling point 100. Reaumur's rule is used by many 
 continental nations freezing point, or zero, 0, and boiling point 80. 
 
V. 
 
 4.- TROY WEIGHT. 
 
 24 grains 1 pennyweight. 
 
 480 20 1 ounce. 
 
 5760 240 12 1 pound. 
 
 By this weight are weighed gold, silver, jewels, electuaries, and all 
 liquors. 
 
 The standard for gold coin is 22 carats of fine gold and two carats of 
 copper melted together. For silver, 1 1 oz. 2 dwts. of fine silver, and 
 18 dwts. of copper. 
 
 lOOBbs 1 cwt. 20 cwt. 1 ton of gold or silver. 
 
 To reduce pounds troy into avoirdupois, multiply by 144, and divide 
 by 175, the quotient will be the number of pounds avoirdupois. 
 
 5. AVOIRDUPOIS WEIGHT. 
 
 16 drams 1 ounce. 
 256 16 1 pound. 
 
 3584 224 14 1 stone. 
 
 7168 448 28 2 1 quarter. 
 
 28672 1792 112 8 4 1 cwt. 
 573440 35840 2240 160 80 20 1 ton. 
 
 A keel of coal at Newcastle is 21 tons 4 cwt., and a chaldron is 53 
 cwt. A chaldron of coal in London is 28| cwt. 
 
 About 426 cubic inches of cast iron ... ... 1 cwt. 
 
 8520 or nearly 5 cubic feet ... 1 ton. 
 
 13 cublic feet of stone 1 
 
 23 sand 1 
 
 29 coal 1 
 
 38 tallow 1 
 
 39 oil 1 
 
 40 rough timber ... 1 
 50 squared timber ... 1 
 
 6. MEASURE OF SURFACES. 
 
 144 inches 1 square foot. 
 1296 9 1 square yard. 
 
 39204 272J 30J 1 square pole. 
 
 1568160 10890 1210 40 1 rood. 
 6272640 43560 4840 160 4 1 acre. 
 
 By this measure are measured all things that have length and 
 breadth, such as land, painting, plastering, flooring, thatching, plumbing, 
 glazing, &c. 
 
vi. 
 RULE TO ASCERTAIN THE WEIGHT OF CAST-IRON BALLS 
 
 OF ANY DIAMETER. 
 
 Cube the diameter, and divide by 7 -27. The quotient is the weight. 
 
 EXAMPLE : 9 inches diameter. 
 9 
 
 81 
 9 
 
 7-27)729-00(100 T | T lbs. 
 
 727 
 
 2-00 
 BOILING POINT OF WATER, 
 
 UNDER DIFFERENT PRESSURES OF THE ATMOSPHERE. 
 Barometer, 
 
 26 inches 
 26J 
 
 27 
 
 "'2 " 
 
 28 
 28J 
 
 29 
 
 29 J 
 
 30 
 30 J 
 
 Water in vacuum boils at about 98 degrees Fahrenheit, and assumes a 
 solid at 32 degrees in the atmosphere, when it expands T Vth its original 
 bulk. At a temperature of 212 degrees it becomes vapour, or steam, 
 nor can that temperature be increased in an open vessel. In a closed one 
 it may be heated to redness. Mercury will fall T Vth of an inch for every 
 100 feet perpendicular height. In ascending Snowden, in North Wales, 
 the mercury fell 3 T ^ths inches, 3,720 feet above the sea. The velocity 
 of wind in a strong gale is 30 to 35 miles per hour ; hard gale, 40 to 
 45 ; storm, 50 to 55 ; and a hurricane, 80 to 100 miles per hour. 
 
 GEOMETRY. 
 
 45 degrees ... of a circle. 
 90 ... 1 quadrant, or quarter of a circle. 
 
 360 ... 1 circle. When divided into part, are called degrees. 
 
 Many calculations are founded on this division of the circle. 
 
 Pressure. Boiling Pt 
 
 int. 
 
 1 31bs per square inch 205 
 
 degrees. 
 
 13} , 2051 
 
 . )? 
 
 131 
 
 206^ 
 
 
 
 13| 
 
 207^ 
 
 
 
 14 
 
 208J 
 
 M 
 
 34J 
 
 209J 
 
 n 
 
 id 
 
 210} 
 
 a 
 
 14f 
 
 211 
 
 3) 
 
 15 
 
 212 
 
 J) 
 
 15|- 212} 
 
 
 
 154 213| 
 
 
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X. 
 
 Weight of Cast-iron Pipes 1 foot in length, from | inch to 1 J inch 
 thick, and from 3 to 24 inches Diameter. 
 
 Diameter of 
 Bore in Inches. 
 
 THICKNESS IN INCHES. 
 
 1 
 
 I 
 
 Mil 
 
 1 i 
 
 H! H 
 
 frs 
 
 1)8 
 
 B&s fi)s 5s j fi)s 
 
 Ibs | fts 
 
 3 
 
 84| i2i in 
 
 22i 274 
 
 I 
 
 1 
 
 3} 9J| 14i 191 
 
 25i 
 
 35 
 
 1 
 
 
 
 4 10 
 
 16fi 22 
 
 281 
 
 
 
 
 
 4| 11|| 18 
 
 241 
 
 31J 38| 
 
 
 
 
 5 
 
 13 
 
 19} 27 
 
 34|: 42| 
 
 501^ 59 
 
 
 
 5i| 15 
 
 21i 294| 37J 46 
 
 | 541: 63} 
 
 
 
 6 | 231 32 
 
 40| 49} 
 
 59 
 
 68J 
 
 78| 88| 
 
 64| 
 
 25i| 34*1 43}; 53^ 
 
 631 
 
 73j 
 
 781 
 
 841 95 
 
 7 
 
 
 27i! 36J| 46jj 56| 
 
 67} 
 
 89} 1014 
 
 74| 
 
 29 39 50 60| 
 
 72 
 
 83i 
 
 9511071 
 
 8 
 
 
 30}i 41| 53 
 
 64i| 761 
 
 88i 
 
 lOOf 1131 
 
 y 
 
 33 | 44J 56i 
 
 684| 8 ! 
 
 93i 106|-120 
 
 9 
 
 
 34i 
 
 46J 59 
 
 71| 
 
 84| 
 
 981 
 
 111} 
 
 125| 
 
 91 
 
 36i 
 
 49 
 
 62 
 
 75^ 
 
 89 
 
 103 
 
 1171 
 
 132 
 
 10 
 
 
 38i 
 
 51J 65i 
 
 794! 931 
 
 108 
 
 122} 
 
 138 
 
 10J 
 
 
 54 
 
 68i 82| 
 
 97j 
 
 112| 
 
 1281 
 
 1441 
 
 11 
 
 
 564| 71i 86J 
 
 102 
 
 117| 
 
 134 
 
 1504 
 
 111 
 
 
 
 
 59 
 
 76i 
 
 90 |I061 
 
 122|139il56i 
 
 12 
 
 
 
 6H 
 
 77J 
 
 
 
 1271 
 
 145 
 
 162J 
 
 13 
 
 
 
 
 82}|101J|118i 
 
 137^154 
 
 1731 
 
 14 
 
 
 
 
 89i 108J 126J 
 
 14611654|1854 
 
 15 
 
 
 
 
 95ill5||135| 
 
 15641761198 
 
 16 
 
 
 
 
 1234 
 
 143 
 
 166 |187i 
 
 2111 
 
 17 
 
 
 
 
 
 1304 
 
 152^ 
 
 1781 
 
 1981 
 
 2231- 
 
 18 
 
 
 
 
 
 137 
 
 1614 
 
 1854 
 
 209 
 
 2351 
 
 19 
 
 
 
 
 
 
 1691 
 
 195| 
 
 222|- 
 
 247 
 
 20 
 
 
 
 
 
 178 
 
 2051 
 
 2334 
 
 259 
 
 21 
 
 
 
 
 
 ! 
 
 214 
 
 2431 
 
 2731 
 
 22 
 
 
 
 
 
 
 
 223J 
 
 254| 
 
 2851 
 
 23 
 
 
 
 
 
 
 23-31 
 
 2651-J2981 
 
 24 
 
 
 
 
 
 
 2454 
 
 277^310^1 
 
xi. 
 
 WEIGHT OF MATERIALS. 
 
 
 Weight of 
 a cubic foot 
 in Ibs. 
 
 Weight of 
 a cubic inch 
 in ozs. 
 
 No. of 
 cubic inches 
 in a Ib. 
 
 Weight of 
 a cubic inch 
 in Ibs. 
 
 Mercury 
 
 848 
 
 7-851 
 
 2-037 
 
 4908 
 
 Lead 
 
 709 
 
 6-456 
 
 2-437 
 
 4103 
 
 
 477 
 
 4.-14-0 
 
 3-623 
 
 276 
 
 Cast Iron . 
 
 454|- 
 
 4-203 
 
 3-802 
 
 263 
 
 Sheet Copper ... 
 Cast Copper 
 
 557 
 5491 
 
 5-159 
 5-086 
 
 3-103 
 3-146 
 
 3225 
 
 3178 
 
 Cast Brass 
 
 5241 
 
 4-852 
 
 3-223 
 
 3037 
 
 Brick 
 
 "'4 
 
 125 
 
 1-456 
 
 13-824 
 
 0723 
 
 Stone 
 
 151 
 
 1-396 
 
 11-443 
 
 0873 
 
 Water 
 
 62 
 
 
 27 1 
 
 
 
 uwig 
 
 
 1 2 
 
 
 Thirty-six feet of common water make 1 ton. 35 feet of sea water 
 make 1 ton. 
 
 One cubic foot of water = 6 J imperial gallons, or 62ilbs. 1 cylindrical 
 foot = 5 gallons, or 4 9 Ibs. 
 
 11 '2 imperial gallons 1 cwt. 224 imperial gallons = 1 ton. 1 gallon 
 of fresh water = lOibs. 1 gallon of sea water = 10 Jibs. 
 
 At; a temperature of 62 Fahrenheit, between 62 and 42, water 
 attains its greatest density ; and the pressure is as the perpendicular 
 height, independent of quantity. 
 
 Water is not compressible. It presses in every direction, and finds a 
 level ; thus, a small quantity will balance and support a great quantity, 
 whatever the difference in dimension. 
 
 The centre of the pressure of a column of water is two-thirds of its 
 depth from the surface. 
 
 Ten pounds of distilled, or rain, water equals the standard gallon at 62. 
 
 2-004 inches of a column of mercury lib. 
 
 27-648 water lft>. 
 
 26-895 sea water.. . 1R>. 
 
Xll. 
 
 A TABLE SHOWING THE DIFFERENCE IN THE 
 STRENGTH OF METALS. 
 
 Wrought Iron 1000 Gold 273 
 
 Copper 550 Zinc 199 
 
 Platinum 494 Tin 63 
 
 Silver 349 Lead 50 
 
 A copper bolt or rod of the same thickness as iron, will sustain little 
 more than one-half the weight iron will. Iron- wire one-sixteenth of an 
 inch diameter is capable of sustaining a weight of 5005>s. A bar of 
 wrought iron one inch square, when sound and good, will require 25 
 tons to pull it asunder. 
 
 HEAT-CONDUCTING POWERS OF DIFFERENT METALS. 
 
 Gold 1000 Iron 374 
 
 Silver 973 Zinc 368 
 
 Copper 898 Tin 304 
 
 Platinum 391 Lead 108 
 
 A TABLE SHOWING THE TEMPERATURE METALS MELT AT. 
 
 Degrees, Degrees. 
 
 Gold 2016 Lead 612 
 
 Platinum 3280 Tin 442 
 
 Silver 1873 Zinc 773 
 
 Copper 1996 Cast Iron 2786 
 
 Brass ., ... 1900 Mercury boils 672 
 
 Tin 2 parts, Lead 2 parts, mixed, melts at 332. 
 
 With Cast-iron, melted from the pig, its strength may be represented 
 by 1 ; the second time by \\ j the third time by 2, and so on until it 
 has been melted nine or ten times, when it will have attained its 
 maximum strength that being about four times the strength of the 
 first casting. This shows how important it is to have all toothed wheels, 
 particularly the first driving wheels, beams, cranks, shafts, or other parts 
 of a Steam Engine and going gear, made from good old metal, and not 
 new Pig-iron. By being re-melted, the metal becomes refined, closer in 
 the pores, works smoother, and wears longer. 
 
 Metal melted in a blast furnace is not equal in strength to the same 
 metal melted in an air furnace. 
 
A TABLE FOR SAFETY VALVES, 
 CYLINDERS, AIR-PUMPS, &o., 
 
 Containing the Circumferences and Areas of Circles from j*$ of an 
 inch to 10 inches, advancing by T V of an inch ; and by ^ of an inch, 
 from 10 inches to 100 inches Diameter. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 , 
 
 .1963 
 
 .0030 
 
 2 in. 
 
 6.2832 
 
 3.1416 
 
 1 
 
 .3927 
 
 .0122 
 
 A 
 
 6.4795 
 
 3.3411 
 
 A 
 
 .5890 
 
 .0276 
 
 f 
 
 6.6759 
 
 3.5465 
 
 1 
 
 .7854 
 
 .0490 
 
 T 3 6 
 
 6.8722 
 
 3.7582 
 
 A 
 
 .9817 
 
 .0767 
 
 i 
 
 7.0686 
 
 3.9760 
 
 | 
 
 1.1781 
 
 .1104 
 
 T 5 g- 
 
 7.2649 
 
 4.2001 
 
 
 1.3744 
 
 .1503 
 
 1 
 
 7.4613 
 
 4.4302 
 
 I 
 
 1.5708 
 
 .1963 
 
 TB" 
 
 7.6576 
 
 4.6664 
 
 A 
 
 1.7671 
 
 .2485 
 
 \ 
 
 7.8540 
 
 4.9087 
 
 1 
 
 1.9635 
 
 .3068 
 
 A 
 
 8.0503 
 
 5.1573 
 
 
 2.1598 
 
 .3712 
 
 1 
 
 8.2467 
 
 5.4119 
 
 f 
 
 2.3562 
 
 .4417 
 
 \\ 
 
 8.4430 
 
 5.6727 
 
 
 2.5525 
 
 .5185 
 
 I 
 
 8.6394 
 
 5.9395 
 
 * 
 
 2.7489 
 
 .6013 
 
 if 
 
 8.8357 
 
 6.2126 
 
 *f 
 
 2.9452 
 
 .6903 
 
 I 
 
 9.0321 
 
 6.4918 
 
 
 
 
 
 
 9.2284 
 
 6.7772 
 
 1 in. 
 
 3.1416 
 
 .7854 
 
 
 
 
 A 
 
 3.3379 
 
 .8861 
 
 3 in. 
 
 9.4248 
 
 7.0686 
 
 i 
 
 3.5343 
 
 .9940 
 
 j^. 
 
 9.6211 
 
 7.3662 
 
 A 
 
 3.7306 
 
 1.1075 
 
 * 
 
 9.8175 
 
 7.6699 
 
 
 3.9270 
 
 1.2271 
 
 * 
 
 10.0138 
 
 T.9798 
 
 ft 
 
 4.1233 
 
 1.3529 
 
 
 10.2102 
 
 8.2957 
 
 1 
 
 4.3197 
 
 1.4848 
 
 A 
 
 10.4065 
 
 8.6179 
 
 & 
 
 4.5160 
 
 1.6229 
 
 f 
 
 10.6029 
 
 8.9462 
 
 
 4.7124 
 
 1.7671 
 
 A 
 
 10.7992 
 
 9.2806 
 
 A 
 
 4.9087 
 
 1.9175 
 
 i 
 
 10.9956 
 
 9.6211 
 
 
 5.1051 
 
 2.0739 
 
 A 
 
 11.1919 
 
 9.9678 
 
 A 
 
 5.3014 
 
 2.2365 
 
 i 
 
 11.3883 
 
 10.3206 
 
 3 
 
 4 
 
 5.4978 
 
 2.4052 
 
 
 11.5846 
 
 10.6796 
 
 
 5.6941 
 
 2.5801 
 
 t 
 
 11.7810 
 
 11.0446 
 
 I 
 
 5.8905 
 
 2.7611 
 
 if 
 
 11.9773 
 
 11.4159 
 
 
 6.0868 
 
 2.9483 
 
 I- 
 
 12.1737 
 
 11.7932 
 
XIV. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 Diameter. 
 
 Circum. 
 
 Area 
 
 if 
 
 12.3700 
 
 12.1768 
 
 \ 
 
 20.4204 
 
 33.1831 
 
 
 
 
 ft 
 
 20.6167 
 
 33.8244 
 
 4 in. 
 
 12.5664 
 
 12.5664 
 
 | 
 
 20.8131 
 
 34.4717 
 
 A 
 
 12.7627 
 
 12.9622 
 
 H| 
 
 21.0094 
 
 35.1252 
 
 i 
 
 12.9591 
 
 13.3640 
 
 f 
 
 21.2058 
 
 35.7847 
 
 ft 
 
 13.1554 
 
 13.7721 
 
 it 
 
 21.4021 
 
 36.4505 
 
 i 
 
 13.3518 
 
 14.1862 
 
 1 
 
 21.5985 
 
 37.1224 
 
 1% 
 
 13.5481 
 
 14.6066 
 
 H 
 
 21.7948 
 
 37.8005 
 
 I 
 
 13.7445 
 
 15.0331 
 
 
 
 
 A 
 
 13.9408 
 
 15.4657 
 
 7 in. 
 
 21.9912 
 
 38.4846 
 
 i 
 
 14.1372 
 
 15.9043 
 
 A 
 
 22.1875 
 
 39.1749 
 
 A 
 
 14.3335 
 
 16.3492 
 
 i 
 
 22.3839 
 
 39.8713 
 
 1 
 
 14.5299 
 
 16.8001 
 
 ft 
 
 22.5802 
 
 40.5469 
 
 
 
 14.7262 
 
 17.2573 
 
 
 22.7766 
 
 41.2825 
 
 t 
 
 14.9226 
 
 17.7205 
 
 ft 
 
 22.9729 
 
 41.9974 
 
 it 
 
 15.1189 
 
 18.1900 
 
 f 
 
 23.1693 
 
 42.7184 
 
 1 
 
 15.3153 
 
 18.6655 
 
 ft 
 
 23.3656 
 
 43.4455 
 
 tf 
 
 15.5716 
 
 19.1472 
 
 
 
 23.5620 
 
 44.1787 
 
 
 
 
 ft 
 
 23.7583 
 
 44.9181 
 
 5 in. 
 
 15.7080 
 
 19.6350 
 
 1 
 
 23.9547 
 
 45.6636 
 
 ft 
 
 15.9043 
 
 20.1290 
 
 ft 
 
 24.1510 
 
 46.4153 
 
 i 
 
 16.1007 
 
 20.6290 
 
 3 
 
 4 
 
 24.3474 
 
 47.1730 
 
 ft 
 
 16.2970 
 
 21.1252 
 
 H 
 
 24.5437 
 
 47.9370 
 
 i 
 
 16.4934 
 
 21.6475 
 
 1 
 
 24.7401 
 
 48.7070 
 
 * 
 
 16.6897 
 
 22.1661 
 
 if 
 
 24.9364 
 
 49.4833 
 
 
 16.8861 
 
 22.6907 
 
 
 
 
 ft 
 
 17.0824 
 
 23.2215 
 
 8 in. 
 
 25.1328 
 
 50.2656 
 
 i 
 
 17.2788 
 
 23.7583 
 
 :nr 
 
 25.3291 
 
 51.0541 
 
 ft 
 
 17.4751 
 
 24.3014 
 
 | 
 
 25.5255 
 
 51.8486 
 
 f 
 
 17.6715 
 
 24.8505 
 
 T 3 
 
 25.7218 
 
 52.8994 
 
 ft 
 
 17.8678 
 
 25.4058 
 
 I 
 
 25.9182 
 
 53.4562 
 
 I 
 
 18.0642 
 
 25.9672 
 
 1% 
 
 26.1145 
 
 54.2748 
 
 it 
 
 18.2605 
 
 26.5348 
 
 
 26.3109 
 
 55.0885 
 
 f 
 
 18.4569 
 
 27.1085 
 
 A 
 
 26.5072 
 
 55.9138 
 
 *f 
 
 18.6532 
 
 27.6884 
 
 $ 
 
 26.7036 
 
 56.7451 
 
 
 
 
 A 
 
 26.8999 
 
 57.5887 
 
 6 in. 
 
 18.8496 
 
 28.2744 
 
 I 
 
 27.0963 
 
 58.4264 
 
 ft 
 
 19.0459 
 
 28.8665 
 
 \l 
 
 27.2926 
 
 59.7762 
 
 1 
 
 19.2423 
 
 29.4647 
 
 f 
 
 27.4890 
 
 60.1321 
 
 A 
 
 19.4386 
 
 30.0798 
 
 it 
 
 27.6853 
 
 60.9943 
 
 i 
 
 19.6350 
 
 30.6796 
 
 f 
 
 27.8817 
 
 61.8625 
 
 A 
 
 19.8313 
 
 31.2964 
 
 H 
 
 27.0780 
 
 62.7369 
 
 f 
 
 20.0277 
 
 31.9192 
 
 
 
 
 A 
 
 20.2240 
 
 32.5481 
 
 9 in. 
 
 28.2744 
 
 63.6174 
 
Diameter. 
 
 Circum. 
 
 Area. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 A 
 
 28.4707 
 
 64.5041 
 
 | 
 
 41.2338 
 
 135.2974 
 
 I 
 
 28.6671 
 
 65.3968 
 
 x 
 
 41.6262 
 
 137.8867 
 
 tV 
 
 28.8634 
 
 66.2957 
 
 I 
 
 42.0189 
 
 140.5007 
 
 } 
 
 29.0598 
 
 67.2007 
 
 
 42.4116 
 
 143.1391 
 
 A 
 
 29.2561 
 
 68.1120 
 
 1 
 
 42.8043 
 
 145.8021 
 
 I 
 
 29.4525 
 
 69.0293 
 
 1 
 
 43.1970 
 
 148.4896 
 
 A 
 
 29.6488 
 
 69.9528 
 
 Q 
 
 43.5897 
 
 151.2017 
 
 * 
 
 29.8452 
 
 70.8823 
 
 
 
 
 A 
 
 30.0415 
 
 71.8181 
 
 14 in. 
 
 43.9824 
 
 153.9384 
 
 1 
 
 30.2379 
 
 72.7599 
 
 l 
 
 44.3751 
 
 156.6995 
 
 W 
 
 30.4342 
 
 73.7079 
 
 i 
 
 44.7676 
 
 159.4852 
 
 f 
 
 30.6306 
 
 74.6620 
 
 | 
 
 45.1605 
 
 162.2956 
 
 H 
 
 30.8269 
 
 75.6223 
 
 ^ 
 
 45.5532 
 
 165.1303 
 
 f 
 
 31.0233 
 
 76.5887 
 
 | 
 
 45.9459 
 
 167.9896 
 
 if 
 
 31.2196 
 
 77.5613 
 
 3 
 
 46.3386 
 
 170.8735 
 
 
 
 
 | 
 
 46.7313 
 
 173.7820 
 
 10 in. 
 
 31.4160 
 
 78.5400 
 
 
 
 
 1 
 
 31.8087 
 
 80.5157 
 
 15 in. 
 
 47.1240 
 
 176.7150 
 
 1 
 
 32.2014 
 
 82.5160 
 
 l 
 
 47.5167 
 
 179.6725 
 
 3 
 
 32.5941 
 
 84.5409 
 
 JL 
 
 47.9094 
 
 182.6545 
 
 1 
 
 32.9868 
 
 86.5903 
 
 J 
 
 48.3021 
 
 185.6612 
 
 
 33.3795 
 
 88.6643 
 
 | 
 
 48.6948 
 
 188.6923 
 
 J 
 
 33.7722 
 
 90.7627 
 
 
 49.0875 
 
 191.7480 
 
 s 
 
 34.1649 
 
 92.8858 
 
 4 
 
 49.4802 
 
 194.8282 
 
 
 
 
 5 
 
 49.8729 
 
 197.9330 
 
 11 in. 
 
 34.5576 
 
 95.0334 
 
 
 
 
 J 
 
 34.9503 
 
 97.2053 
 
 16 in. 
 
 50.2656 
 
 201.0624 
 
 | 
 
 35.3430 
 
 99.4021 
 
 | 
 
 50.6583 
 
 204.2162 
 
 1 
 
 35.7357 
 
 101.6234 
 
 
 51.0510 
 
 207.3946 
 
 I 
 
 36.1284 
 
 103.8691 
 
 \ 
 
 51.4437 
 
 210.5976 
 
 
 36.5211 
 
 106.1394 
 
 1 ! 
 
 51.8364 
 
 213.8251 
 
 j 
 
 36.9138 
 
 108.4342 
 
 
 52.2291 
 
 217.0772 
 
 | 
 
 37.3065 
 
 110.7536 
 
 
 52.6218 
 
 220.3537 
 
 
 
 
 9 
 
 53.0145 
 
 223.6549 
 
 12 in. 
 
 37.6992 
 
 113.0976 
 
 
 
 
 $ 
 
 38.0919 
 
 115.4660 
 
 17 in. 
 
 53.4072 
 
 226.9806 
 
 I 
 
 38.4846 
 
 117.8590 
 
 l 
 
 53.7999 
 
 230.3308 
 
 | 
 
 38.8773 
 
 120.2766 
 
 l 
 
 54.1926 
 
 233.7055 
 
 | 
 
 39.2700 
 
 122.7187 
 
 | 
 
 54.5853 
 
 237.1049 
 
 
 39.6627 
 
 125.1854 
 
 I 
 
 54.9780 
 
 240.5287 
 
 S 
 
 40.0554 
 
 127.6765 
 
 
 55.3707 
 
 243.9771 
 
 1 
 
 40.4481 
 
 130.1923 
 
 T 
 
 55.7634 
 
 247.4500 
 
 
 
 
 | 
 
 56.1561 
 
 250.9475 
 
 13 in. 
 
 43.8408 
 
 132.7326 
 
 
 
 
XVI. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 Diameter, 
 
 Circum. 
 
 Area 
 
 18 in. 
 
 56.5488 
 
 254.4696 
 
 23 in. 
 
 72.2568 
 
 415.4766 
 
 I 
 
 56.9415 
 
 258.0161 
 
 | 
 
 72.6495 
 
 420.0049 
 
 1 
 
 57.6342 
 
 261.5872 
 
 
 73.0422 
 
 424.5577 
 
 3 
 
 57.7269 
 
 265.1829 
 
 | 
 
 73.4349 
 
 429.1352 
 
 i 
 
 58.1196 
 
 268.8031 
 
 I 
 
 73.8276 
 
 433.7371 
 
 
 58.5123 
 
 272.4479 
 
 
 74.2203 
 
 438.3636 
 
 J 
 
 58.9056 
 
 276.1171 
 
 | 
 
 74.6130 
 
 443.0146 
 
 I 
 
 59.2977 
 
 279.8110 
 
 i 
 
 75.0057 
 
 447.6992 
 
 19 in. 
 
 59.6904 
 
 283.5294 
 
 24 in. 
 
 75.3984 
 
 452.3904 
 
 i 
 
 60.0831 
 
 287.2723 
 
 i 
 
 75.7911 
 
 457.1150 
 
 
 60.4758 
 
 291.0397 
 
 I 
 
 76.1838 
 
 461.8642 
 
 | 
 
 60.8685 
 
 294.8312 
 
 | 
 
 76.5765 
 
 466.6380 
 
 _! 
 
 61.2612 
 
 298.6483 
 
 i 
 
 76.9692 
 
 471.4363 
 
 1 
 
 61.6539 
 
 302.4894 
 
 1 
 
 77.3619 
 
 476.2592 
 
 3 
 4 
 
 62.0466 
 
 306.3550 
 
 | 
 
 77.7546 
 
 481.1065 
 
 1 
 
 62.4393 
 
 310.2452 
 
 1 
 
 78.1473 
 
 485.9785 
 
 20 in. 
 
 62.8320 
 
 314.1600 
 
 25 in. 
 
 78.5400 
 
 490.8750 
 
 i 
 
 63.2247 
 
 318.0992 
 
 l 
 
 78.9327 
 
 495.7960 
 
 I 
 
 63.6174 
 
 322.0630 
 
 l 
 
 79.3254 
 
 500.7415 
 
 3 
 
 64.0101 
 
 326.0514 
 
 | 
 
 79.7181 
 
 505.7117 
 
 | 
 
 64.4028 
 
 330.0643 
 
 f 
 
 80.1108 
 
 510.7063 
 
 
 64.7955 
 
 334.1018 
 
 
 80.5035 
 
 515.7255 
 
 | 
 
 65.1882 
 
 338.1637 
 
 | 
 
 80.8962 
 
 520.7692 
 
 s 
 
 65.5809 
 
 342.2503 
 
 7 
 8 
 
 81.2889 
 
 525.8375 
 
 21 in. 
 
 65.7936 
 
 346.3614 
 
 26 in. 
 
 81.6816 
 
 530.9304 
 
 i 
 
 66.3663 
 
 350.4970 
 
 i 
 
 82.0743 
 
 536.0477 
 
 I 
 
 66.7590 
 
 354.6571 
 
 
 82.4670 
 
 541.1896 
 
 a 
 
 67.1517 
 
 358.8419 
 
 | 
 
 82.8597 
 
 546.3561 
 
 1 
 
 67.5444 
 
 363.0511 
 
 i 
 
 83 2524 
 
 551.5471 
 
 
 67.9371 
 
 367.2849 
 
 
 83.6451 
 
 556.7627 
 
 J 
 
 68.3298 
 
 371.5432 
 
 3. 
 
 84.0378 
 
 562.0027 
 
 i 
 
 68.7225 
 
 375.8261 
 
 I 
 
 84.4305 
 
 567.2674 
 
 22 in. 
 
 69.1152 
 
 380.1336 
 
 27 in. 
 
 84.8232 
 
 572.5566 
 
 1 
 
 69.5079 
 
 384.4655 
 
 | 
 
 85.2159 
 
 577.8703 
 
 
 69.9006 
 
 388.8220 
 
 
 85.6086 
 
 583.2085 
 
 | 
 
 70.2933 
 
 393.2031 
 
 f 
 
 86.0013 
 
 588.5714 
 
 | 
 
 70.6860 
 
 397.6087 
 
 I 
 
 86.3940 
 
 593.9587 
 
 
 71.0787 
 
 402.0388 
 
 
 86.7867 
 
 599.3706 
 
 | 
 
 71.4714 
 
 406.4935 
 
 4 
 
 87.1794 
 
 604.8070 
 
 1 
 
 71.8641 
 
 410.9728 
 
 I 
 
 87.5721 
 
 610.2680 
 
XV11. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 28 in. 
 
 87.9648 
 
 615.7536 
 
 33 in. 
 
 103.6728 
 
 855.3006 
 
 i 
 
 88.3575 
 
 621.2636 
 
 i 
 
 104.0655 
 
 861.7924 
 
 ^ 
 
 88.7502 
 
 626.7982 
 
 1 
 
 104.4582 
 
 868.3087 
 
 | 
 
 89.1429 
 
 632.3574 
 
 1 
 
 104.8509 
 
 874.8497 
 
 I 
 
 89.5356 
 
 637.9411 
 
 -k 
 
 105.2436 
 
 881.4151 
 
 
 89.9283 
 
 643.5494 
 
 \ 
 
 105.6363 
 
 888.0051 
 
 4~ 
 
 90.3210 
 
 649.1821 
 
 i 
 
 106.0290 
 
 894.6196 
 
 I 
 
 90.7137 
 
 654.8395 
 
 7 
 8 
 
 106.4217 
 
 901.2587 
 
 29 in. 
 
 91.1064 
 
 660.5214 
 
 34 in. 
 
 106.8144 
 
 907.9224 
 
 
 
 91.4991 
 
 666.2278 
 
 i 
 
 107.2071 
 
 914.6105 
 
 i 
 
 91.8918 
 
 671.9587 
 
 I 
 
 107.5998 
 
 921.3232 
 
 | 
 
 92.2845 
 
 677.7143 
 
 3 
 
 107.9925 
 
 928.0605 
 
 i 
 
 92.6772 
 
 683.4943 
 
 I 
 
 108.3852 
 
 934.8223 
 
 
 93.0699 
 
 689.2989 
 
 
 108.7779 
 
 941.6086 
 
 "4 
 
 93.4626 
 
 695.1280 
 
 "4 
 
 109.1706 
 
 948.4195 
 
 I 
 
 93.8553 
 
 700.9817 
 
 I 
 
 109.5633 
 
 955.2550 
 
 30 in. 
 
 94.2480 
 
 706.8600 
 
 35 in. 
 
 109.9560 
 
 962.1150 
 
 i 
 
 94.6407 
 
 712.7627 
 
 i 
 
 110.3487 
 
 968.9995 
 
 1 
 
 4 
 
 95.0334 
 
 718.6900 
 
 l 
 
 4 
 
 110.7414 
 
 975.9085 
 
 I 
 
 95.4261 
 
 724.6419 
 
 1 
 
 111.1341 
 
 982.8422 
 
 1 
 
 95.8188 
 
 730.6183 
 
 i 
 
 111.5268 
 
 989.8003 
 
 | 
 
 96.2115 
 
 736.6193 
 
 I 
 
 111.9195 
 
 996.7830 
 
 3 
 
 4 
 
 96.6042 
 
 742.6447 
 
 3 
 4 
 
 112.3122 
 
 1003.7902 
 
 I 
 
 96.9969 
 
 748.6948 
 
 1 
 
 112.7049 
 
 1010.8220 
 
 31 in. 
 
 97.3896 
 
 754.7694 
 
 36 in. 
 
 113.0976 
 
 1017.8784 
 
 i 
 
 97.7823 
 
 760.8685 
 
 f 
 
 113.4903 
 
 1024.9592 
 
 1 
 
 4 
 
 98.1750 
 
 766.9921 
 
 1 
 
 113.8830 
 
 1032.0646 
 
 
 98.5677 
 
 773.1404 
 
 1 
 
 114.2757 
 
 1039.1946 
 
 1 
 
 98.9684 
 
 779.3131 
 
 i 
 
 114.6684 
 
 1046.3941 
 
 | 
 
 99.3531 
 
 785.5104 
 
 1 
 
 115.0611 
 
 1053.5281 
 
 "4 
 
 99.7458 
 
 791.7322 
 
 | 
 
 115.4538 
 
 1060.7317 
 
 
 100.1385 
 
 797.9786 
 
 I 
 
 115.8465 
 
 1067.9599 
 
 32 in. 100.5312 
 
 804.2496 
 
 37 in. 
 
 116.2392 
 
 1075.2126 
 
 i 
 
 100.9240 
 
 810.5450 
 
 i 
 
 116.6319 
 
 1082.4898 
 
 
 101.3166 
 
 816.8650 
 
 i 
 
 117.0246 
 
 1089.7915 
 
 | 
 
 101.7093 
 
 823.2096 
 
 f- 
 
 117.4173 
 
 1097.1179 
 
 i 
 
 102.1020 
 
 829.5787 
 
 1 
 
 117.8100 
 
 1104.4687 
 
 
 102.4947 
 
 835.9724 
 
 1 
 
 118.2027 
 
 1111.8441 
 
 | 
 
 102.8874 
 
 842.3905 
 
 | 
 
 118.5954 
 
 1119.2440 
 
 i 
 
 103.2801 
 
 848.8333 
 
 1 
 
 118.9881 
 
 1126.6685 
 
XVill. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 38 in. 
 
 119.3808 
 
 1134.1176 
 
 43 in. 
 
 135.0888 
 
 1452.2046 
 
 1 
 
 119.7735 
 
 1141.5911 
 
 i 
 
 135.4815 
 
 1460.6599 
 
 j- 
 
 120.1662 
 
 1149.0892 
 
 
 135.8742 
 
 1469.1397 
 
 i 
 
 120.5589 
 
 1156.6119 
 
 | 
 
 136.2669 
 
 1477.6342 
 
 i 
 
 120.9516 
 
 1164.1591 
 
 i 
 
 136.6596 
 
 1486.1731 
 
 | 
 
 121.3443 
 
 1171.7309 
 
 
 137.0523 
 
 1494.7266 
 
 J 
 
 121.7370 
 
 1179.3271 
 
 1 
 
 137.4450 
 
 1503.3046 
 
 i 
 
 122.1297 
 
 1186.9480 
 
 1 
 
 137.8377 
 
 1511.9072 
 
 39 in. 
 
 122.5224 
 
 1194.5934 
 
 44 in. 
 
 138.2304 
 
 1520.534i 
 
 i 
 
 122.9151 
 
 1202.2633 
 
 i 
 
 138.6231 
 
 1529.1860 
 
 _L 
 
 123.3078 
 
 1209.9577 
 
 l 
 
 139.0158 
 
 1537.8622 
 
 | 
 
 123.7005 
 
 1217.6768 
 
 | 
 
 139.4085 
 
 1546.5530 
 
 | 
 
 124.0932 
 
 1225.4203 
 
 | 
 
 139.8012 
 
 1555.2883 
 
 
 124.4859 
 
 1233.1884 
 
 
 140.1939 
 
 1564.0382 
 
 1 
 
 124.9787 
 
 1240.9810 
 
 a 
 
 140.5866 
 
 1572.8125 
 
 1 
 
 125.2713 
 
 1248.7982 
 
 i 
 
 140.9793 
 
 1581.6115 
 
 40 in. 
 
 125.6640 
 
 1256.6400 
 
 45 in. 
 
 141.3720 
 
 1590.4350 
 
 i 
 
 126.0567 
 
 1264.5062 
 
 i 
 
 141.7647 
 
 1599.2830 
 
 I 
 
 126.4494 
 
 1272.3970 
 
 
 142.1574 
 
 1608.1555 
 
 1 
 
 126.8421 
 
 1280.3124 
 
 I 
 
 142.5501 
 
 1617.0427 
 
 ^ 
 
 127.2348 
 
 1288.2523 
 
 I 
 
 142.9428 
 
 1625.9743 
 
 | 
 
 127.6275 
 
 1296.2168 
 
 
 143.3355 
 
 1634.9205 
 
 | 
 
 128.0202 
 
 1304.2057 
 
 1 
 
 143.7382 
 
 1643.8912 
 
 I 
 
 128.4129 
 
 1312.2193 
 
 I 
 
 144.1209 
 
 1652.8865 
 
 41 in. 
 
 128.8056 
 
 1320.2574 
 
 46 in. 
 
 144.5136 
 
 1661.9064 
 
 i 
 
 129.1983 
 
 1328.3200 
 
 i 
 
 144.9063 
 
 1670.9507 
 
 l 
 
 129.5910 
 
 1336.4071 
 
 1 
 
 145.2990 
 
 1680.0196 
 
 | 
 
 129.9837 
 
 1344.5189 
 
 1 
 
 145.6917 
 
 1689.1031 
 
 1 
 
 130.3764 
 
 1352.6551 
 
 i 
 
 146.0844 
 
 1698.2311 
 
 | 
 
 130.7691 
 
 1360.8159 
 
 1 
 
 146.4771 
 
 1707.3737 
 
 "4 
 
 131.1618 
 
 1369.0012 
 
 3 
 4 
 
 146.8698 
 
 1716.5407 
 
 I 
 
 131.5545 
 
 1377.2111 
 
 1 
 
 147.2625 
 
 1725.7324 
 
 42 in. 
 
 131.9472 
 
 1385.4456 
 
 47 in. 
 
 147.6552 
 
 1734.9486 
 
 | 
 
 132.3399 
 
 1393.7045 
 
 i 
 
 148.0479 
 
 1744.1893 
 
 
 132.7326 
 
 1401.9880 
 
 .1 
 
 1484406 
 
 1753.4545 
 
 | 
 
 133.1253 
 
 1470.2961 
 
 I 
 
 148.8333 
 
 1762.7344 
 
 i 
 
 133.5180 
 
 1418.6287 
 
 
 
 149.2260 
 
 1772.0587 
 
 1 
 
 133.9107 
 
 1426.9859 
 
 I 
 
 149.6187 
 
 1781.3976 
 
 3 
 
 134.3034 
 
 1435.3675 
 
 | 
 
 150.0114 
 
 1790.7610 
 
 1 
 
 134.6961 
 
 1443.7738 
 
 I 
 
 150.4041 
 
 1800.1490 
 
 I 
 
 
 
 
 
 
Diameter. 
 
 Circum. 
 
 Area. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 48 in. 
 
 150.7968 
 
 1809.5616 
 
 53 in. 
 
 166.5048 
 
 2206.1886 
 
 I 
 
 151.1895 
 
 1818.9986 
 
 i 
 
 166.8975 
 
 2216.6074 
 
 i 
 
 151.5822 
 
 1628.4602 
 
 1 
 
 167.2902 
 
 2227.0507 
 
 | 
 
 151.9749 
 
 1837.9364 
 
 | 
 
 167.6829 
 
 2237.5187 
 
 I 
 
 152.3676 
 
 1847.4571 
 
 i 
 
 168.0756 
 
 2248.0111 
 
 | 
 
 152.7603 
 
 1856.9924 
 
 1 
 
 168.4683 
 
 2258.5281 
 
 J 
 
 153.1530 
 
 1868.5521 
 
 I 
 
 168.8610 
 
 2269.0696 
 
 I 
 
 153.5457 
 
 1876.1365 
 
 7 
 8 
 
 169.2537 
 
 2279.6357 
 
 49 in. 
 
 153.9384 
 
 1885.7454 
 
 54 in. 
 
 169.6464 
 
 2290.2264 
 
 1 
 
 154.3311 
 
 1895.3788 
 
 i 
 
 170.0391 
 
 2300.8415 
 
 i 
 
 154.7238 
 
 1905.0367 
 
 
 170.4318 
 
 2311.4812 
 
 i 
 
 155.1165 
 
 1914.7093 
 
 | 
 
 170.8245 
 
 2322.1455 
 
 I 
 
 155.5092 
 
 1924.4263 
 
 i 
 
 171.2172 
 
 2332.8343 
 
 1 
 
 155.9019 
 
 1934.1579 
 
 
 171.6099 
 
 2343.5477 
 
 3 
 
 156.2946 
 
 1943.9140 
 
 j 
 
 172.0026 
 
 2354.2855 
 
 1 
 
 156.6873 
 
 1953.6947 
 
 i 
 
 172.3593 
 
 2365.0480 
 
 50 in. 
 
 157.0800 
 
 1963.5000 
 
 55 in. 
 
 172.7880 
 
 2375.8350 
 
 i 
 
 157.4727 
 
 1973.3297 
 
 i 
 
 173.1807 
 
 2386.6465 
 
 1 
 
 157.8654 
 
 1983.1840 
 
 1 
 
 173.5734 
 
 2397.4825 
 
 | 
 
 158.2581 
 
 1993.0529 
 
 | 
 
 173.9661 
 
 2408.3432 
 
 i 
 
 158.6508 
 
 2002.9663 
 
 1 
 
 174.3588 
 
 2419.2283 
 
 
 159.0435 
 
 2012.8943 
 
 1 
 
 174.7515 
 
 2430.1833 
 
 1 
 
 159.4362 
 
 2022.8467 
 
 I 
 
 175.1442 
 
 2441.0772 
 
 
 
 159.8289 
 
 2032.8238 
 
 7 
 
 i 
 
 175.5369 
 
 2452.0310 
 
 51 in. 
 
 160.2216 
 
 2042.8254 
 
 56 in. 
 
 175.9296 
 
 2463.0144 
 
 i 
 
 160.6143 
 
 2052.8515 
 
 | 
 
 176.3323 
 
 2474.0222 
 
 I 
 
 161.0070 
 
 2062.9021 
 
 
 176.7150 
 
 2485.3546 
 
 
 161.3997 
 
 2072.9764 
 
 | 
 
 177.1077 
 
 2496.1116 
 
 | 
 
 161.7924 
 
 2083.0771 
 
 i 
 
 177.5004 
 
 2507.1931 
 
 | 
 
 162.1851 
 
 2093.2014 
 
 
 177.8931 
 
 2518.2992 
 
 | 
 
 162.5778 
 
 2103.3502 
 
 j 
 
 178.2858 
 
 2529.4297 
 
 i 
 
 162.9705 
 
 2113.5236 
 
 I 
 
 178.6785 
 
 2543.5849 
 
 52 in. 
 
 163.3632 
 
 2123.7216 
 
 57 in. 
 
 179.0712 
 
 2551.7646 
 
 i 
 
 163.7559 
 
 2133.9440 
 
 | 
 
 179.4639 
 
 2562.9688 
 
 
 164.1486 
 
 2144.1910 
 
 i 
 
 179.8566 
 
 2574.1975 
 
 "8 
 
 164.5413 
 
 2154.4626 
 
 | 
 
 180.2493 
 
 2585.4509 
 
 | 
 
 164.9340 
 
 2164.7587 
 
 | 
 
 180.6423 
 
 2596.7287 
 
 
 165.3267 
 
 2175.0794 
 
 
 181.0347 
 
 2608.0311 
 
 3 
 
 165.7194 
 
 2185.4245 
 
 | 
 
 181.4274 
 
 2619.3580 
 
 i 
 
 166.1121 
 
 2195.7943 
 
 1 
 
 181.8201 
 
 2630.7095 
 
XX. 
 
 Diameter 
 
 Circum. 
 
 Area. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 58 in. 
 
 182.2128 
 
 2642.0856 
 
 63 in. 
 
 197.9208 
 
 3117.2526 
 
 
 182.6055 
 
 2653.4861 
 
 i 
 
 198.3135 
 
 3129.6349 
 
 
 182.9982 
 
 2664.9112 
 
 1 
 
 4 
 
 198.7062 
 
 3142.0417 
 
 s 
 
 183.3909 
 
 2676.3609 
 
 
 199.0989 
 
 3154.4732 
 
 i 
 
 183.7836 
 
 2687.8351 
 
 I 
 
 199.4916 
 
 3166.9291 
 
 | 
 
 184.1763 
 
 2699.3338 
 
 
 199.8843 
 
 3179.4096 
 
 J 
 
 184.5690 
 
 2710.8571 
 
 J 
 
 200.2770 
 
 3191.9146 
 
 i 
 
 184.9617 
 
 2722.4050 
 
 7 
 8 
 
 200.6697 
 
 3204.4442 
 
 59 in. 
 
 185.3544 
 
 2733.9774 
 
 64 in. 
 
 201.0624 
 
 3216.9984 
 
 i 
 
 185.7471 
 
 2745.5743 
 
 A 
 
 201.4551 
 
 3229.5770 
 
 1 
 
 186.1398 
 
 2757.1957 
 
 i 
 
 201.8478 
 
 3242.1782 
 
 | 
 
 186.5325 
 
 2768.8418 
 
 1 
 
 202.2405 
 
 3254.8080 
 
 1 
 
 186.9252 
 
 2780.5123 
 
 i 
 
 202.6332 
 
 3267.4603 
 
 | 
 
 187.3179 
 
 2792.2074 
 
 
 203.0259 
 
 3280.1372 
 
 J 
 
 187.7106 
 
 2803.9270 
 
 | 
 
 203.4186 
 
 3292.8385 
 
 1 
 
 188.1033 
 
 2815.6712 
 
 1 
 
 203.8113 
 
 3305.5645 
 
 60 in. 
 
 188.4960 
 
 2827.4400 
 
 65 in. 
 
 204.2040 
 
 3318.3151 
 
 1 
 
 188.8887 
 
 2839.2332 
 
 | 
 
 204.5917 
 
 3331.0900 
 
 
 189.2814 
 
 2851.0510 
 
 
 204.9894 
 
 3343.8875 
 
 | 
 
 189.6741 
 
 2862.8934 
 
 | 
 
 205.3821 
 
 3356.7137 
 
 | 
 
 190.0668 
 
 2874.7603 
 
 i 
 
 205.7748 
 
 3369.5623 
 
 
 190.4595 
 
 2886.6517 
 
 
 206.1675 
 
 3382.4355 
 
 J 
 
 190.8522 
 
 2898.5677 
 
 3 
 
 206.5602 
 
 3395.3332 
 
 I 
 
 191.2419 
 
 2910.5083 
 
 I 
 
 206.9529 
 
 3408.2555 
 
 61 in. 
 
 191.6376 
 
 2922.4734 
 
 66 in. 
 
 207.3456 
 
 3421.2024 
 
 l 
 
 192.0303 
 
 2934.4630 
 
 l 
 
 207.7383 
 
 3434.1737 
 
 1 
 
 192.4230 
 
 2946.4771 
 
 J 
 
 208.1310 
 
 3447.1676 
 
 1 
 
 192.8157 
 
 2958.5159 
 
 | 
 
 208.5237 
 
 3468.1901 
 
 f 
 
 193.2084 
 
 2970.5791 
 
 i 
 
 208.9164 
 
 3473.2351 
 
 
 193.6011 
 
 2982.6669 
 
 | 
 
 209.3091 
 
 3486.3047 
 
 J 
 
 193.9931 
 
 2994.7792 
 
 3 
 
 209.7018 
 
 3499.3987 
 
 i 
 
 194.3865 
 
 3006.9161 
 
 1 
 
 210.0945 
 
 3532.5174 
 
 62 in. 
 
 194.7792 
 
 3019.0776 
 
 67 in. 
 
 210.4872 
 
 3525.6606 
 
 i 
 
 195.1719 
 
 3031.2635 
 
 i 
 
 210.8799 
 
 3538.8283 
 
 1 
 4 
 
 195.5646 
 
 3043.4740 
 
 
 211.2726 
 
 3552.0185 
 
 
 195.9573 
 
 3055.7091 
 
 1 
 
 211.6653 
 
 3565.2374 
 
 I 
 
 196.3500 
 
 3067.9687 
 
 i 
 
 212.0580 
 
 3578.4787 
 
 | 
 
 196.7427 
 
 3080.2529 
 
 1 
 
 212.4507 
 
 3591.7446 
 
 j 
 
 197.1354 
 
 3092.5615 
 
 3 
 
 4 
 
 212.8434 
 
 3605.0350 
 
 7 
 8 
 
 197.5281 
 
 3104.8948 
 
 I 
 
 213.2361 
 
 3618.3300 . 
 
Diameter. 
 
 Circum. 
 
 Area. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 68 in. 
 
 213.6288 
 
 3631.6896 
 
 73 in. 
 
 229.3368 
 
 4185.3966 
 
 | 
 
 214.0215 
 
 3645.0536 
 
 i 
 
 229.7295 
 
 4199.7424 
 
 
 214.4142 
 
 3658.4402 
 
 I 
 
 230.1222 
 
 4214.1107 
 
 I 
 
 214.8069 
 
 3671.8554 
 
 | 
 
 230.5149 
 
 4228.5077 
 
 1 
 
 215.1996 
 
 3685.2931 
 
 * 
 
 230.9076 
 
 4242.9271 
 
 
 215.5923 
 
 3698.7554 
 
 i 
 
 231.3003 
 
 4257.3711 
 
 3 
 
 215.9850 
 
 3712.2421 
 
 i 
 
 231.6930 
 
 4271.8396 
 
 1 
 
 216.3777 
 
 3725.7535 
 
 i 
 
 232.0857 
 
 4286.3327 
 
 69 in. 
 
 216.7704 
 
 3739.2894 
 
 74 in. 
 
 232.4784 
 
 4300.8504 
 
 i 
 
 217.1631 
 
 3752.8498 
 
 | 
 
 232.8711 
 
 4315.3926 
 
 
 217.5558 
 
 3766.4327 
 
 
 233.2638 
 
 4329.9572 
 
 3 
 
 217.9485 
 
 3780.0443 
 
 | 
 
 233.6565 
 
 4344.5505 
 
 1 
 
 218.3412 
 
 3793.6783 
 
 i 
 
 234.0492 
 
 4359.1663 
 
 
 218.7339 
 
 3807.3369 
 
 | 
 
 234.4419 
 
 4373.8067 
 
 3 
 
 219.1266 
 
 3821.0200 
 
 j 
 
 234.8346 
 
 4388.4715 
 
 1 
 
 219.5193 
 
 3834.7277 
 
 1 
 
 235.2273 
 
 4403.1610 
 
 70 in. 
 
 219.9120 
 
 3848.4600 
 
 75 in. 
 
 235.6200 
 
 4417.8750 
 
 I 
 
 220.3047 
 
 3862.2167 
 
 A 
 
 236.0127 
 
 4432.6135 
 
 1 
 
 220.6974 
 
 3875.9960 
 
 i 
 
 236.4054 
 
 4447.3745 
 
 3 
 
 221.0901 
 
 3889.8039 
 
 1 
 
 236.7981 
 
 4462.1642 
 
 J 
 
 221.4828 
 
 3903.6343 
 
 | 
 
 237.1908 
 
 4476.9763 
 
 
 221.8755 
 
 3917.4893 
 
 
 237.5835 
 
 4491.8130 
 
 4^ 
 
 222.2682 
 
 3931.3687 
 
 | 
 
 237.9762 
 
 4506.6742 
 
 I 
 
 222.6609 
 
 3945.2728 
 
 I 
 
 238.3689 
 
 4521.5600 
 
 71 in. 
 
 223.0536 
 
 3959.2014 
 
 76 in. 
 
 238.7616 
 
 4536.4704 
 
 i 
 
 B 
 
 223.4463 
 
 3973.1545 
 
 i 
 
 239.1543 
 
 4551.4023 
 
 I 
 
 223.8390 
 
 3987.1301 
 
 i 
 
 239.5470 
 
 4566.3626 
 
 1 
 
 224.2317 
 
 4001.1344 
 
 | 
 
 239.9397 
 
 4581.3486 
 
 i 
 
 224.6244 
 
 4015.1611 
 
 i 
 
 240.3324 
 
 4596.3571 
 
 
 225.0171 
 
 4029.2124 
 
 1 
 
 240.7251 
 
 4611.3902 
 
 4T 
 
 225.4098 
 
 4043.2882 
 
 | 
 
 241.1178 
 
 4626.4477 
 
 i 
 
 225.8025 
 
 4057.3886 
 
 7 
 8 
 
 241.5105 
 
 4641.5299 
 
 72 in. 
 
 226.1952 
 
 4071.5136 
 
 77 in. 
 
 241.9032 
 
 4656.6366 
 
 | 
 
 226.5879 
 
 4085.6631 
 
 f 
 
 242.2959 
 
 4671.7678 
 
 
 226.9806 
 
 4099.8350 
 
 
 242.6886 
 
 4686.9215 
 
 | 
 
 227.3733 
 
 4114.0356 
 
 a 
 
 243.0813 
 
 4702.1039 
 
 | 
 
 227.7660 
 
 4128.2587 
 
 i 
 
 243.4740 
 
 4717.3087 
 
 
 228.1587 
 
 4142.5064 
 
 
 243.8667 
 
 4732.5381 
 
 | 
 
 228.5514 
 
 4156.7785 
 
 J 
 
 244.2594 
 
 4747.7920 
 
 7 
 I 
 
 228.9441 
 
 4171.0753 
 
 1 
 
 244.6521 
 
 4763.0705 
 
XXll. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 Diameter, 
 
 Cireum. 
 
 Area. 
 
 78 in. 
 
 245.0448 
 
 4778.3736 
 
 83 in. 
 
 260.7528 
 
 5410.6206 
 
 1 
 
 245.4375 
 
 4793.7012 
 
 i 
 
 261.1455 
 
 5426.9299 
 
 
 245.8302 
 
 4809.0512 
 
 
 261.5382 
 
 5443.2617 
 
 | 
 
 246.2229 
 
 4824.4299 
 
 | 
 
 261.9309 
 
 5459.6222 
 
 f 
 
 246.6156 
 
 4839.8311 
 
 i 
 
 262.3236 
 
 5476.0051 
 
 
 247.0083 
 
 4855.2568 
 
 
 262.71G3 
 
 5492.4118 
 
 } 
 
 247.4010 
 
 4870.7071 
 
 | 
 
 263.1090 
 
 5508.8446 
 
 1 
 
 247.7937 
 
 4886.1820 
 
 i 
 
 263.5017 
 
 5525.3012 
 
 79 in. 
 
 248.1864 
 
 4901.6814 
 
 84 in. 
 
 263.8944 
 
 5541.7824 
 
 | 
 
 248.5791 
 
 4917.2053 
 
 | 
 
 264.2871 
 
 5558.2881 
 
 i 
 
 248.9718 
 
 4932.7517 
 
 
 264.6798 
 
 5574.8162 
 
 | 
 
 249.3645 
 
 4948.3268 
 
 | 
 
 265.0725 
 
 5591.3730 
 
 i 
 
 249.7572 
 
 4963.9243 
 
 i 
 
 265.4652 
 
 5607.9523 
 
 | 
 
 250.1499 
 
 4979.5456 
 
 | 
 
 265.8579 
 
 5624.5554 
 
 J 
 
 250.5426 
 
 4995.1930 
 
 
 266.2506 
 
 5641.1845 
 
 I 
 
 250.9353 
 
 5010.8642 
 
 1 
 
 266.6433 
 
 5657.8357 
 
 80 in. 
 
 251.3280 
 
 5026.5600 
 
 85 in. 
 
 267.0360 
 
 5674.5150 
 
 i 
 
 251.7207 
 
 5042.2803 
 
 i 
 
 267.4287 
 
 5691.2170 
 
 l 
 
 252.1134 
 
 5058.0230 
 
 
 267.8214 
 
 5707.9415 
 
 | 
 
 252.5061 
 
 5073.7944 
 
 | 
 
 268.2141 
 
 5724.6947 
 
 1 
 
 252.8988 
 
 5089.5883 
 
 i 
 
 268.6068 
 
 5741.4703 
 
 | 
 
 253.2915 
 
 5106.4060 
 
 
 268.9997 
 
 5758.2697 
 
 
 253.6842 
 
 5121.2497 
 
 f 
 
 269.3922 
 
 5775.0952 
 
 1 
 
 254.0769 
 
 5137.1173 
 
 
 269.7849 
 
 5791.9445 
 
 81 in. 
 
 254.4696 
 
 5153.0094 
 
 86 in. 
 
 270.1776 
 
 5808.8184 
 
 J 
 
 254.8623 
 
 5168.9260 
 
 | 
 
 270.5703 
 
 5825.7168 
 
 
 255.2550 
 
 5184.8651 
 
 
 270.9630 
 
 5842.6376 
 
 | 
 
 255.6477 
 
 5200.8329 
 
 | 
 
 271.3557 
 
 5859.5871 
 
 i 
 
 256.0404 
 
 5216.8231 
 
 i 
 
 271.7484 
 
 5876.5591 
 
 f 
 
 256.4331 
 
 5232.8371 
 
 
 272.1411 
 
 5893.5549 
 
 i 
 
 256.8258 
 
 5248.8772 
 
 I 
 
 272.5338 
 
 5910.5767 
 
 1 
 
 257.2105 
 
 5264.9411 
 
 i 
 
 272.9265 
 
 5927.6224 
 
 82 in. 
 
 257.6112 
 
 5281.0296 
 
 87 in. 
 
 273.3192 
 
 5944.6926 
 
 | 
 
 258.0039 
 
 5297.1426 
 
 1 
 
 273.7119 
 
 5961.7873 
 
 
 258.3966 
 
 5313.2780 
 
 I 
 
 274.1046 
 
 5978.9045 
 
 | 
 
 258.7893 
 
 5329.4421 
 
 I 
 
 274.4973 
 
 5996.0504 
 
 | 
 
 259.1820 
 
 5345.6287 
 
 I 
 
 274.8900 
 
 6013.2187 
 
 
 259.5747 
 
 5361.8391 
 
 
 275.2827 
 
 6030.4108 
 
 j 
 
 259.9674 
 
 5378.0755 
 
 | 
 
 275.6754 
 
 6047.6290 
 
 1 
 
 260.3601 
 
 5394.3358 
 
 1 
 
 276.0681 
 
 6064.8710 
 
)iameter. 
 
 Circum. 
 
 Area. 
 
 iameter. 
 
 Circum. 
 
 Area. 
 
 88 in. 
 
 276.4608 
 
 6082.1376 
 
 93 in. 
 
 292.1688 
 
 6792.9248 
 
 | 
 
 276.8535 
 
 6099.4287 
 
 I 
 
 292.5615 
 
 6811.1974 
 
 1 
 
 4 
 
 277.2462 
 
 6116.7422 
 
 
 292.9542 
 
 6829.4927 
 
 
 277.6389 
 
 6134.0844 
 
 | 
 
 293.3469 
 
 6847.8167 
 
 i 
 
 278.0316 
 
 6151.4491 I 
 
 | 
 
 293.7396 
 
 6866.1631 
 
 | 
 
 278.4243 
 
 6169.8376 
 
 
 294.1323 
 
 6884.5338 
 
 'j 
 
 278.8170 
 
 6186.2591 
 
 4" 
 
 294.5350 
 
 6902.9296 
 
 1 
 
 279.2097 
 
 6203.6905 
 
 1 
 
 294.9177 
 
 6921.3497 
 
 89 in. 
 
 279.6024 
 
 6221.1534 
 
 94 in. 
 
 295.3104 
 
 6939.7946 
 
 | 
 
 279.9951 
 
 6238.6408 
 
 i 
 
 295.7031 
 
 6958.2636 
 
 
 280.3878 
 
 6256.1507 
 
 
 296.0958 
 
 6976.7552 
 
 3 
 
 280.7805 
 
 6273.6893 
 
 3 
 
 296.4885 
 
 6995.2755 
 
 } 
 
 281.1732 
 
 6291.2503 
 
 i 
 
 296.8812 
 
 7013.8183 
 
 
 281.5659 
 
 6308.8351 
 
 
 297.2739 
 
 7032.3853 
 
 3 
 
 281.9586 
 
 6326.4460 
 
 ~4b 
 
 297.6666 
 
 7050.9775 
 
 1 
 
 282.3513 
 
 6344.0807 
 
 I 
 
 298.0593 
 
 7069.5940 
 
 90 in. 
 
 282.7440 
 
 6361.7400 
 
 95 in. 
 
 298.4520 
 
 7088.2352 
 
 i 
 
 283.1367 
 
 6379.4238 
 
 i 
 
 298.8447 
 
 7106.9005 
 
 
 283.5294 
 
 6397.1300 
 
 
 299.2374 
 
 7125.5885 
 
 3 
 
 283.9221 
 
 6414.8649 
 
 3 
 
 299.6301 
 
 7144.3052 
 
 | 
 
 284.3148 
 
 6432.6223 
 
 i 
 
 300.0228 
 
 7163.0443 
 
 
 284.7075 
 
 6450.4039 
 
 
 300.4155 
 
 7181.8077 
 
 f 
 
 285.1002 
 
 6468.2107 
 
 | 
 
 300.8082 
 
 7200.5962 
 
 I 
 
 285.4929 
 
 6486.0418 
 
 s 
 
 301.2009 
 
 7219.4090 
 
 91 in. 
 
 285.8856 
 
 6503.8974 
 
 96 in. 
 
 301.5936 
 
 7238.2466 
 
 i 
 
 286.2783 
 
 6521.7772 
 
 i 
 
 301.9863 
 
 7257.1083 
 
 
 286.6710 
 
 6539.6801 
 
 I 
 
 302.3790 
 
 7275.9926 
 
 | 
 
 287.0637 
 
 6557.6114 
 
 1 
 
 302.7717 
 
 7294.9056 
 
 ^ 
 
 287.4564 
 
 6573.5651 
 
 i 
 
 303.1644 
 
 7313.8411 
 
 1 
 
 287.8491 
 
 6593.5431 
 
 
 303.5571 
 
 7332.8008 
 
 1 
 
 288.2418 
 
 6611.5462 
 
 J 
 
 303.9498 
 
 7351.7857 
 
 1 
 
 288.6345 
 
 6629.5736 
 
 I 
 
 304.3425 
 
 7370.7949 
 
 92 in. 
 
 289.0272 
 
 6647.6258 
 
 97 in. 
 
 304.7352 
 
 7389.8288 
 
 i 
 
 289.4199 
 
 6665.7021 
 
 1 
 
 305.1279 
 
 7408.8868 
 
 i 
 
 289.8125 
 
 6683.8010 
 
 
 305.5206 
 
 7427.9675 
 
 3 
 
 290.2053 
 
 6701.9286 
 
 3 
 
 305.9133 
 
 7447.0769 
 
 I 
 
 290.5980 
 
 6720.0787 
 
 | 
 
 306.3060 
 
 7466.2087 
 
 
 290.9907 
 
 6738.2530 
 
 
 306.6987 
 
 7485.3648 
 
 | 
 
 291.3834 
 
 6756.4525 
 
 | 
 
 307.0914 
 
 7504.5460 
 
 I 
 
 291.7661 
 
 6774.6763 
 
 1 
 
 307.4841 
 
 7523.7515 
 
XXIV. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 Diameter. 
 
 Circum. 
 
 Area. 
 
 98 in. 
 
 307.8768 
 
 7542.9818 
 
 i 
 
 311.4111 
 
 7717.1563 
 
 1 
 
 308.2695 
 
 7562.2362 
 
 J_ 
 
 311.8038 
 
 7736.6297 
 
 1 
 
 308.6622 
 
 7581.5132 
 
 | 
 
 312.1965 
 
 7756.1318 
 
 | 
 
 309.0549 
 
 7600.8189 
 
 i 
 
 312.5892 
 
 7775.6563 
 
 1 
 
 309.4476 
 
 7620.1471 
 
 
 312.9819 
 
 7795.2051 
 
 5 
 
 309.8403 
 
 7639.4995 
 
 | 
 
 313.3746 
 
 7814.7790 
 
 | 
 
 310.2330 
 
 7658.8771 
 
 7 
 8 
 
 313.7673 
 
 7834.3772 
 
 1 
 
 310.6257 
 
 7678.2790 
 
 
 
 
 
 
 
 100 in. 
 
 314.1600 
 
 7854.0000 
 
 99 in. 
 
 311.0184 
 
 7697.7056 
 
 
 
 
 ! 
 
 
 
 
 
 
XXV. 
 
 A TABLE 
 
 Showing the Pressure of Steam from 2JBbs up to 605>s ; and the height 
 
 of a Column of Mercury, and the number of Feet and Inches 
 
 of Water in a Column at the different Pressures. 
 
 Pressure of 
 Steam. 
 
 Inches of 
 Mercury Column. 
 
 Feet and Inches 
 of Water in height at 
 the Temperature and 
 Pressure. 
 
 Pounds. 
 
 Inches, 
 
 Feet. Inches. 
 
 2J 
 
 5-15 
 
 5 9 
 
 3 
 
 6-18 
 
 6 11 
 
 31 
 
 7-21 
 
 8 Of 
 
 4 
 
 8-24 
 
 9 2J 
 
 41 
 
 9-27 
 
 10 4 
 
 5 
 
 10-30 
 
 11 6 
 
 ^i 
 
 11-33 
 
 12 8 
 
 6 
 
 12-36 
 
 13 10 
 
 6J 
 
 13-39 
 
 15 
 
 7 
 
 14-42 
 
 16 2 
 
 7J 
 
 15-45 
 
 17 4A 
 
 8 
 
 16-48 
 
 18 5 
 
 10 
 
 20-60 
 
 23 
 
 12 
 
 24-72 
 
 27 8 
 
 15 
 
 39-90 
 
 34 6 
 
 20 
 
 41-20 
 
 46 1J 
 
 25 
 
 51-50 
 
 57 7J 
 
 30 
 
 61-80 
 
 69 1J 
 
 35 
 
 72-12 
 
 86 8 
 
 40 
 
 82-41 
 
 92 2J 
 
 45 
 
 92-70 
 
 103 9 
 
 50 
 
 103-00 
 
 115 3 
 
 55 
 
 113-31 
 
 126 9 
 
 60 
 
 123-60 
 
 138 3J 
 
 Additional Column of 
 
 
 2 feet 3J inches of a 
 
 2-037 Inches of 
 
 
 column extra for 
 
 Mercury for each extra 
 
 
 each increased pound 
 
 pound pressure. 
 
 
 pressure. 
 
 Steam produced from impure water is not of equal density to steam 
 from pure water. Steam from pure water at a temperature of 212 
 degrees, supports a column of mercury 30 inches ; and steam from sea 
 water at the same temperature supports only 22| inches. Common 
 water, at a temperature of 220 degrees, supports 35 inches ; and sea 
 water, at the same temperature, 26 J inches of a column of mercury. 
 Pressure and temperature in this case varies. In all cases where accuracy 
 of pressure is requisite, an open column of mercury is the most sensitive 
 and correct indicator. 
 
XXVI. 
 
 A TABLE 
 
 Showing the Temperature of Steam at different Pressures, from lib per 
 
 Square Inch to 240K)S, and the quantity of Steam produced 
 
 from a Cubic Inch of Water, according to Pressure. 
 
 NOTE. Add the pressure of the atmosphere, 15ft>s, to the pressure on the stearn gauge, 
 to correspond with the table. 
 
 Total 
 Pressure 
 of Steam 
 in fibs per 
 Square 
 Inch. 
 
 Corresponding 
 Temperature 
 of Steam 
 to Pressure. 
 
 Cubic Inches of 
 Steam from 
 a Cubic Inch of 
 Water according 
 to Pressure. 
 
 Total 
 Pressure 
 of Steam 
 in tbs per 
 Square 
 Inch. 
 
 Corresponding 
 Temperature 
 of Steam 
 to Pressure. 
 
 Cubic Inches of 
 Steam from 
 a Cubic Inch of 
 Water according 
 to Pressure, 
 
 1 
 
 102-9 
 
 20868 
 
 32 
 
 255-5 
 
 833 
 
 2 
 
 126-1 
 
 10874 
 
 33 
 
 257-3 
 
 810 
 
 3 
 
 141-0 
 
 7437 
 
 34 
 
 259-1 
 
 788 
 
 4 
 
 152-3 
 
 5685 
 
 35 
 
 260-9 767 
 
 5 
 
 161-4 
 
 4617 
 
 36 
 
 262-6 748 
 
 6 
 
 169-2 
 
 3897 
 
 37 
 
 264-3 
 
 729 
 
 7 
 
 175-9 
 
 3376 
 
 38 
 
 265-9 
 
 712 
 
 8 
 
 182-0 
 
 2983 
 
 39 
 
 267.5 
 
 695 
 
 9 
 
 187-4 
 
 2674 
 
 40 
 
 269-1 
 
 679 
 
 10 
 
 192-4 
 
 2426 
 
 41 
 
 270-6 
 
 664 
 
 11 
 
 197-0 
 
 2221 
 
 42 
 
 272-1 
 
 649 
 
 12 
 
 201-3 
 
 2050 
 
 43 
 
 273-6 
 
 635 
 
 13 
 
 205-3 
 
 1904 
 
 44 
 
 275-0 
 
 622 
 
 14 
 
 209-1 
 
 1778 
 
 45 
 
 276-4 
 
 610 
 
 1 K Press, of O 1 9-8 
 
 - 1 - " Atmsnhr ""-"<-' 
 
 1669 
 
 46 
 
 277-8 
 
 598 
 
 16 
 
 216-3 
 
 1573 
 
 47 
 
 279-2 
 
 586 
 
 17 
 
 219-6 
 
 1488 
 
 48 
 
 280-5 
 
 575 
 
 18 
 
 222-7 
 
 1411 
 
 49 
 
 281-9 
 
 564 
 
 19 
 
 225-6 
 
 1343 
 
 50 
 
 283-2 
 
 554 
 
 20 
 
 228-5 
 
 1281 
 
 51 
 
 284-4 
 
 544 
 
 21 
 
 231-2 
 
 1225 
 
 52 
 
 285-7 
 
 534 
 
 22 
 
 233-8 
 
 1174 
 
 53 
 
 286-9 
 
 525 
 
 23 
 
 236-3 
 
 1127 
 
 54 
 
 288-1 
 
 516 
 
 24 
 
 238-7 
 
 1084 
 
 55 
 
 289-3 
 
 508 
 
 25 
 
 241-0 
 
 1044 
 
 56 
 
 290-5 
 
 500 
 
 26 
 
 243-3 
 
 1007 
 
 57 
 
 291-7 
 
 492 
 
 27 
 
 245-5 
 
 973 
 
 58 
 
 292-9 
 
 484 
 
 28 
 
 247-6 
 
 941 
 
 59 
 
 294-2 
 
 477 
 
 29 
 
 249-6 
 
 911 
 
 60 
 
 295-6 
 
 470 
 
 30 
 
 251-6 
 
 883 
 
 61 
 
 296-9 
 
 463 
 
 31 
 
 253-6 
 
 857 
 
 62 
 
 298-1 
 
 456 
 
XXV11. 
 
 Total 
 Pressure 
 of Steam 
 in fts per 
 Square 
 Inch. 
 
 Corresponding 
 Temperature 
 of Steam 
 to Pressure. 
 
 Cubic Inches of 
 Steam from 
 a Cubic Inch of 
 Water accoi ding 
 to Pressure. 
 
 Total 
 Pressure of 
 Steam 
 in fts per 
 Square Inch. 
 
 Corresponding 
 Temperature 
 of Steam 
 to Pressure. 
 
 Cubic Inches of 
 Steam from 
 a Cubic Inch of 
 Water according 
 to Pressure. 
 
 63 
 
 299-2 
 
 449 
 
 89 
 
 323-5 
 
 328 
 
 64 
 
 300-3 
 
 443 
 
 90 
 
 324-3 
 
 325 
 
 65 
 
 301-3 
 
 437 
 
 91 
 
 325-1 
 
 322 
 
 66 
 
 302-4 
 
 431 
 
 92 
 
 325-9 
 
 319 
 
 67 
 
 303-4 
 
 425 
 
 93 
 
 326-7 
 
 316 
 
 68 
 
 304-4 
 
 419 
 
 94 
 
 327-5 
 
 313 
 
 69 
 
 305-4 
 
 414 
 
 95 
 
 328-2 
 
 310 
 
 70 
 
 306-4 
 
 408 
 
 96 
 
 329-0 
 
 307 
 
 71 
 
 307-4 
 
 403 
 
 97 
 
 329-8 
 
 304 
 
 72 
 
 308-4 
 
 398 
 
 98 
 
 330-5 
 
 301 
 
 73 
 
 309-3 
 
 393 
 
 99 
 
 331-3 
 
 298 
 
 74 
 
 310-3 
 
 388 
 
 100 
 
 332-0 
 
 295 
 
 75 
 
 311-2 
 
 383 
 
 110 
 
 339-2 
 
 271 
 
 76 
 
 312-2 
 
 379 
 
 120 
 
 345-8 
 
 251 
 
 77 
 
 313-1 
 
 374 
 
 130 
 
 352-1 
 
 233 
 
 78 
 
 314-0 
 
 370 
 
 140 
 
 357-9 
 
 218 
 
 79 
 
 314-9 
 
 366 
 
 150 
 
 363-4 
 
 205 
 
 80 
 
 315-8 
 
 362 
 
 160 
 
 368-7 
 
 193 
 
 81 
 
 316-7 
 
 358 
 
 170 
 
 373-6 
 
 183 
 
 82 
 
 317-6 
 
 354 
 
 180 
 
 378-4 
 
 174 
 
 83 
 
 318-4 
 
 350 
 
 190 
 
 382-9 
 
 166 
 
 84 
 
 319-3 
 
 346 
 
 200 
 
 387-3 
 
 158 
 
 85 
 
 320-1 
 
 342 
 
 210 
 
 391-5 
 
 151 
 
 86 
 
 321-0 
 
 339 
 
 220 
 
 395-5 
 
 145 
 
 87 
 
 321-8 
 
 335 
 
 230 
 
 399-4 
 
 140 
 
 88 
 
 322-6 
 
 332 
 
 240 
 
 403-1 
 
 134 
 
 This table shows that the saving of fuel is in proportion to the increase 
 of pressure. The advantage of generating and using high-pressure steam 
 is thereby made apparent. The table shows that the last lOlbs of 
 additional pressure only requires four degrees of heat to raise it ; whereas 
 the first lOBbs of pressure above the atmosphere requires 29 additional 
 degrees of heat to raise it a difference of 25 degrees. Hence a small 
 accession of heat at a high temperature produces an increase of elastic 
 force ; and a small abstraction of heat reduces its bulk, by the application 
 of cold, in the ratio of its density ; proving the advantage of clothing 
 cylinders, steam-pipes, boilers, &c., with a non-conductor of heat or cold 
 a sure saving of fuel, where adopted, and more particularly required 
 where high -pressure steam is used, 
 
xxvm. 
 A TABLE 
 
 SHOWING THE WEIGHT OF WATER IN PIPES OF- VARIOUS DIAMETERS, 
 ONE FOOT IN LENGTH. 
 
 Diameter 
 iu Inches. 
 
 Weight 
 in Pounds. 
 
 Diameter 
 iu Inches. 
 
 Weight 
 in Pounds, 
 
 Diameter 
 in Inches. 
 
 Weight 
 in Pounds, 
 
 3 
 
 3 
 
 
 121 
 
 51 
 
 23 
 
 1804 
 
 4 
 
 j 
 
 
 llf 
 
 531 
 551 
 
 24 2 
 
 1881 
 1961 
 
 8| 
 
 
 
 13 4 
 
 571 
 
 241 
 
 2041 
 
 4 
 
 5| 
 
 
 i^i 
 
 59| 
 
 25 
 
 213 
 
 44 
 
 6; 
 
 
 13| 
 
 624 
 
 251 
 
 2211 
 
 
 7' 
 
 
 
 641 
 
 26 
 
 2301 
 
 4 
 
 *l 
 
 
 14 ? 
 
 66| 
 
 261 
 
 2391 
 
 5 
 
 8j 
 
 
 141 
 
 691 
 
 27 
 
 2481 
 
 54 
 
 9j 
 
 \ 
 
 141 
 
 711 
 
 271 
 
 257| 
 
 4 
 
 10; 
 
 
 14| 
 
 744 
 
 28 
 
 267^ 
 
 5| 
 
 11; 
 
 
 15 
 
 76f 
 
 28j 
 
 276f 
 
 6 
 
 12} 
 
 
 154 
 
 794 
 
 29 
 
 286J 
 
 6| 
 
 13; 
 
 
 151 
 
 82 
 
 29J 
 
 2961 
 
 
 14; 
 
 
 
 15 j 
 
 84J 
 
 30 
 
 306f 
 
 e| 
 
 15i 
 
 
 16 
 
 874 
 
 30J 
 
 3171 
 
 7 
 
 *j 
 
 [ 
 
 , 
 
 164 
 
 90 
 
 31 
 
 327^ 
 
 
 18 
 
 
 161 
 
 924 
 
 31J 
 
 3381 
 
 ti 
 
 19- 
 
 
 
 16| 
 
 95| 
 
 32 
 
 349 
 
 7f 
 
 20; 
 
 
 17 
 
 98A 
 
 32J 
 
 360 
 
 8 
 
 21^ 
 
 [ 
 
 . 
 
 171 
 
 1011 
 
 33 
 
 3714 
 
 8* 
 
 234 
 
 17J 
 
 104; 
 
 33^ 
 
 3821 
 
 81 
 
 24J 
 
 r 
 
 
 107i 
 
 34 
 
 394 
 
 8f 
 
 26 
 
 
 18 4 
 
 110^ 
 
 34J 
 
 405f 
 
 9 
 
 27^ 
 
 f 
 
 1^4 
 
 113; 
 
 35 
 
 4171 
 
 91 
 
 29; 
 
 t 
 
 181 
 
 1161 
 
 35j 
 
 4291 
 
 9 i 
 
 30| 
 
 ; 
 
 18j 
 
 H9f 
 
 36 
 
 441f 
 
 9| 
 
 32 j 
 
 | 
 
 19 
 
 123 
 
 36J 
 
 454 
 
 10 
 
 34" 
 
 
 1^4 
 
 1261 
 
 37 
 
 4661 
 
 104 
 
 35J 
 
 ' 
 
 191 
 
 1291 
 
 37J 
 
 4791 
 
 li 
 
 37i 
 
 r 
 
 19| 
 
 132 
 
 38 
 
 4924 
 
 11 
 
 4lj 
 
 , 
 f 
 
 20 
 201 
 
 1361 
 1434 
 
 39 2 
 
 5054 
 5181 
 
 Hi 
 
 43; 
 
 ' 
 
 21 
 
 150| 
 
 39J 
 
 531f 
 
 iii 
 
 45 
 
 
 21| 
 
 1571 
 
 40 
 
 545J 
 
 
 47 
 
 
 22 
 
 165 
 
 
 
 12 
 
 49 
 
 
 22J 
 
 1721 
 
 
 
XXIX. 
 
 DURABLE CEMENT FOR STEAM AND WATER JOINTS, 
 GAS RETORTS, &c. 
 
 Take 1 05>s of Ground Litharge, 4tts of Ground Paris White, |S> of 
 Yellow Ochre, 2ft>s of Red Lead, Joz. of Hemp, cut into lengths of half- 
 an-inch. Mix all together with Boiled Linseed Oil, to the consistence of 
 very stiff Putty. Make the joint with the Cement in the usual way. 
 The above mixture well made, will set quickly when heat is applied. It 
 answers well for the joints of steam pipes, for leakages in Boilers, for 
 cisterns, gas retorts, or any other purpose requiring a durable Cement. 
 It resists fire, and will set in water. 
 
 See that the whole is well ground and mixed together. 
 
 Be particular that the Litharge is good. It is too often adulterated 
 by the retail dealers. 
 
 Since this receipt was first published, several parties make and vend 
 the Cement, but of a very inferior quality the greatest portion of the 
 ingredients being Bristol Brick and Sea Sand, with a little Litharge. 
 
 The Cement may be had, mixed, of Messrs. HOPKINSON AND Co., 
 Britannia Works, Huddersfield, in Casks at 42/- per Cwt. 
 
 USEFUL CEMENT FOR RESERVOIRS, CISTERNS, 
 WALLS, WATER COURSES, &c. 
 
 Take 90 parts of well-burnt Brick or Clay (Fire Brick is the best) and 
 10 parts of Litharge, well pulverised and mixed together with Boiled 
 Linseed Oil, to the consistency of thin plaster. 
 
 Use it in the same manner as plaster, previously wetting the parts to 
 be covered with water. This last precaution is indispensable, or the Oil 
 will be absorbed, and prevent the Cement from hardening. Applied in 
 the mode stated, in three or four days the Cement will become firm. 
 
 B. BROWN, PRINTER, HUDDERSFIELD. 
 
PREPARING FOR PUBLICATION, 
 
 the Fifth Edition of 
 
 THE STEAM ENGINE EXPLAINED 
 
 BY TflE 
 
 USE OF THE INDICATOR. 
 
 Of the Firm of J. Hopkinson $ Co., Britannia Works, Huddersfield. 
 
 PRICE 12s. 6d. 
 
 OF 
 
 '0SIVBRSITY 
 

 
 1344 
 
 MTO wsc ocr o 3 
 
51 
 
 GENERAL LIBRARY -U.C. BERKELEY 
 
 THE UNIVERSITY OF CALIFORNIA LIBRARY