REESE 
 
 UNIVERSITY OF CALIFORNIA 
 
 
 
THE 
 
 MINER'S HANDBOOK 
 
 A HANDY BOOK OF REFERENCE 
 
 OX THE SUBJECTS OF 
 
 MINERAL DEPOSITS, MINING OPERATIONS, 
 ORE DRESSING, ETC. 
 
 FOR THE USE OF STUDENTS AND OTHERS 
 INTERESTED IN MINING MATTERS 
 
 COMPILED BY 
 
 JOHN I\/[ILNE, F.R.S. 
 
 PROFESSOR OF MINING IN THE IMPERIAL UNIVERSITY OF JAPAN 
 
 LONDON 
 CROSBY LOCKWOOD AND SON 
 
 7, STATIONERS' HALL COURT, LUDGATE HILL 
 1893 
 
PREFACE. 
 
 THE MINER'S HANDBOOK is a reprint, with corrections and 
 additions, of a compilation, the first part of which was printed 
 fourteen years ago at the Imperial College of Engineering, 
 Tokio, Japan. Although here and there a few notes collected 
 by the writer when visiting mining districts in various parts of 
 the world have been added, the book as a whole is little more 
 than a collection of well-known facts, put together in an order 
 following the writer's lectures. 
 
 A list of works from which material has been derived is 
 added as an Appendix (pp. 295 300) ; and if acknowledge- 
 ment has in any case been omitted, it is hoped that the 
 omission will be regarded as an oversight. But little, if any- 
 thing, is put forward as original. 
 
 The object of the work is to enable students to remember 
 more detailed descriptions of machines and processes, so as to 
 allow them time to sketch from diagrams and models, and also 
 
IV PREFACE. 
 
 to serve as a book of reference for those who have some know- 
 ledge of mining matters. 
 
 For permission to use certain formulae, and for suggestions 
 and assistance when revising proofs, the writer offers sincere 
 thanks to Mr. J. H. Merivale, Mr. W. Frechville, Mr. L. J. 
 Healing, the Publishers, and above all to his colleagues. 
 
 TOKIO, February, 1893. 
 
 P.S. It may be noted that, with the exception of the Title- 
 page, Preface, and Contents, the work has been printed in 
 Japan under the Author's direction. 
 
CONTENTS. 
 
 I.- MINERAL DEPOSITS. 
 
 Classification of Deposits Regular deposits Lodes and veins For- 
 mation of lodes Length and width of lodes Dip Depth of lodes 
 Contents of lodes Structure of lodes Contents of lodes in relation to 
 their direction In relation to each other In relation to the country 
 rock Influence of walls Slickensides Faults Age of lodes Gossans 
 Distinction of veins and beds Theories relating to the filling of 
 lodes ;:'-'' v . . . f . *. . . . i 24 
 
 Beds and Layers Their formation Beds of coal and ironstone 
 Thickness of coal Irregularities and impurities Seams in a district 
 Age of coal Analysis of coal Formation of coal Iron ore Copper 
 ore Salt, lead, and sulphur beds Surface deposits of gold, iron, 
 stream tin . . , . . .'*... . . 24 31 
 
 Irregular Deposits Segregations Stockworks Impregnations 
 Examples of contact deposits Depcs'.ts in non-itratified rocks In 
 metamorphic rocks In limestone . . , . . . 31 36 
 
 II. MINING OPERATIONS. 
 
 Boring, Objects of Methods of Examples of bore holes Operation of 
 boring Rate of progress Diameter of holes Rods Sliding joints 
 Chisels Sludgers Accessory tools Rocking lever Bore frames 
 Guide tubes Tubing Sets of tools Accidents Japanese method 
 American method Mather and Plait's apparatus Diamond boring 
 
VI CONTENTS. 
 
 Boring journal Cost of boring Precautions Precautionary holes- 
 Force on tillers Thickness of a bed Dip of a bed Quantity of 
 water Survey of a hole 37 50 
 
 Breaking Cirouurt Varieties of ground Weight and bulk of material 
 Mining tools : Shovels, Spades, Picks, Hammers, Sledges, Borers, 
 Handles Blasting Tamping Fuses Electrical fuses Firing explo- 
 sives Strength of explosives Classification and list of explosives 
 Position of bore holes Line of least resistance Selection of an explo- 
 siveForce of gunpowder Coal cutters Coal wedging machines 
 Coal drifting machines Rock drills Air compressors . . 51 82 
 
 ftystems of Working Openworks Slate quarries Examples of open- 
 works Monoliths Hydraulic or placer mining Dams Flumes 
 Pipes Working lodes Sloping Narrow and wide lodes Working 
 irregular deposits Working stratified deposits Classification of 
 methods Post and stall method Dimensions of pillars Getting coal 
 Long wall method Effect of subsidence Steep seams Thick seams 
 Working in, slices Cost of breaking ground Waste of coal Fires 
 in mines Preventing fires Extinguishing fires Officers and men in 
 mines . .......... 83 102 
 
 Shafts Varieties of Site of Form and size of Shaft timbering Prop- 
 crib timbering Plank or box timbering Solid cribs Sinking in soft 
 ground Methods of Triger, Guibal, Kind and Chaudron, and Poetsch 
 Iron tubbing Cost of sinking Shaft fittings Ladders Work on 
 ladders Man engine . . 103111 
 
 levels Varieties, dimensions, and position of levels Timbering and wall- 
 ing Varieties of wood Form of timbering Driving in soft ground 
 Archwork and its cost 112 117 
 
 Haulage Kibbles Tubs Resistance to traction Slopes of equal re- 
 sistance and equilibrium Roads Elevation of rails Self-acting 
 inclines Work of men and horses Steam haulage Tail rope, endless 
 rope or chain, and main rope systems Cost of transport Electrical 
 haulage Locomotives Canals Wire tramways . . n3 130 
 
CONTENTS. A 11 
 
 Winding Duty of engines Horse power required Dimensions of 
 engines Indicated and nominal horse power Quantity of material 
 raised Boflers Head gear Pulle"ys Winding drums Brakes 
 Ropes Chains - - Guides Keeps Cages Balancing loads 
 Pneumatic hoisting Man engine and endless chain hoisting Water 
 wheels Use of men and horses Water balance Accidents 
 Over-winding , ; . '"'' ".'"' . . . . ^ . 131 147 
 
 Pumping Dams Raising water by kibbles Cornish pumps Rods- 
 Rocking beams Valves Stroke and lift Pipes Classification of 
 pumps Duty of pumps Hydraulic engines Pulsometer Horse- 
 power for pumping Diameters of pumps Comparison of pump 
 gear 148158 
 
 Lighting Candles Oil Safety lamps Electric lamps Fleuss lamp 
 Aerophores 159162 
 
 Ventilation Necessity for Vitiation of air Carbonic anhydride Car- 
 bonic oxide Methane, Sulphuretted hydrogen, and other gases Dust 
 Detection of gases Osmoscopes Use of barometer and thermometer 
 Earth tremors Lamp detectors Avoidance of explosions Natural 
 ventilation Force of ventilating current Ventilating pressure Velo- 
 city of current Equivalent orifice Obstructions to flow of air Towers 
 Cowls Sollars Falling water Water trompe Furnaces above and 
 below ground Furnace paradox Use of steam Ventilating machines 
 Duck pump Marihaye's and other ventilators Piston machines 
 Centrifugal ventilators Pressure of a fan Guibal's, Waddle, Schiele, 
 and other fans Screw ventilators Ventilating wheels, like Fabry's 
 Considerations respecting various forms of ventilation Efficiency of 
 ventilators Air required in a mine Air splitting Brattices Stoppings 
 Doors Conveyance of air by pipes 163 215 
 
 III. ORE DRESSING. 
 
 Reduction, Sizing, and Sorting Loss in Concentration Metals re- 
 quiring separation Reduction Rock breakers Stamps Mortars and 
 screens Stems, heads, and cams Working effect of stamps Arrange- 
 
V1U CONTENTS. 
 
 ment of stamps Pneumatic and other stamps Cost of mills Rolls 
 Grinding The Arastra Chili mill Centrifugal mills and pulverizers 
 Pan amalgamators 216232 
 
 Concentration Varieties of materials Separation of ore Washing ore 
 Riddles Cradles Trommels Sieve scale Particles required for 
 concentration Theory of concentration Movements of single 
 particles Movements of particles en masse- Jigging Coal cleaning 
 Pointed boxes Spitzlutte Troughs Strips Launders Blanket 
 tables Theory of separation Feeders Buddies Tables Frue and 
 other vanners Rotating cylinders Dolly tubs Use of a dense fluid 
 Magnetic separators Raff wheels Treatment of amalgam Weight 
 of sand 233273 
 
 Machinery in Hills Specifications for plant Examples of processes 
 
 274294 
 
 LIST OF WORKS ON MIXING 295300 
 
 INDEX 301-313 
 
i 
 
 MINERAL DEPOSITS. 
 
 Classification of Mineral Deposits. The following table 
 illustrating the more general forms under which minerals are found 
 in nature, has been drawn up from Von Cotta's Treatise on Ore 
 deposits. 
 
 A. REGULAR DEPOSITS. 
 
 I. Lodes or Veins. 
 
 1. True Veins, transverse to the stratification of the beds in 
 which they occur. 
 
 2. Bedded Veins, parallel to the stratification. 
 
 3. Contact Veins, at the contact of two dissimilar forma- 
 tions. 
 
 Belonging to these three divisions but named according 
 to some peculiarity of their form or position are "gash" 
 veins, lenticular veins, cross courses, cross veins or flucans 
 &c. 
 
 II. Beds and Layers. Mineral deposits which are members 
 of a stratified series. 
 
 B. IRREGULAR DEPOSITS. 
 
 I. Segregations or deposits which are irregular in form but 
 have definite limits. 
 
 II. Impregnations or irregular deposits without definite 
 limits. 
 
 Another classification for Irregular Deposits is as follows: 
 
 1. Deposits at the contact of dissimilar rocks. 
 
 2. embedded in igneous rocks. 
 
 3. , ,, M stratified or metamorphic rock. 
 
 4. occurring in limestone. 
 
A. REGULAR DEPOSITS. 
 
 I. LODES AXI) VEINS. 
 I.odes and their formation. 
 
 When we speak of a lode or vein we usually mean a fissure in the 
 rocky crust of the earth which is filled with mineral matter. 
 
 In Australia a vein is called a reef and in California a ledge. 
 Other equivalents are, Gang (German ), Filon (French), Filoni (Italian). 
 
 A Champion lode is the main lode in a district. Running from 
 it there may be ribs, strings, branches, serins. Rake veins are inclined 
 veins. Right running lodes are those following the general direction 
 of lodes in a district; cross courses are those at right angles to this 
 direction and counter lodes those which are oblique. The material 
 in cross courses and counter lodes is usually different to that in the 
 right running lodes. The sides of a lode are known as its cheeks. 
 The more usual expressions are upper or hanging wall, and lower or 
 footwall. The rocks through which a lode runs are spoken of as the 
 country. A parting, as for instance, a film of clay between a vein and 
 the country rock is called a selvage. 
 
 These fissures have been produced by various causes. The 
 general contraction of a cooling globe is perhaps the most general 
 hypothesis. When we feel the shock of an earthquake it may indicate 
 that either a new fault is being formed or that an old one is being 
 extended. 
 
 If the forming cause, whatever it may be, is evenly distributed 
 then the fissures which result must evidently be parallel to one another 
 unless there is an utter want of homogeneity in the rocky crust. And 
 if we see in any district that the lodes are similar and that rocks are 
 like in character, we can imagine the forming causes to have originat- 
 ed at considerable distance. We also see that two or more series of 
 such fissures may be formed, those of each series being parallel to each 
 other, but the members of one series making an angle with those of 
 another series. 
 
 These different sets of fissures may have been produced at the 
 same time, or more probably perhaps at different times as is indicated 
 by the differences in character of the contained minerals, a fact which 
 is more or less pronounced in several mining districts. 
 
 If we regard these lodes as fissures in the earth which have been 
 filled with mineral matter since their Opening we must at once be 
 
struck with the idea that it is highly improbable and almost impossible 
 that such long gaping fissures as many of these lodes must have once 
 presented could by any means have remained open without support. 
 
 It would seem that they must always have been full of liquid 
 material at a great pressure or else they would have fallen in. If this 
 were not the case it remains for us to suggest the way in which the 
 long lodes we observe in nature could have originated. The sugges- 
 tion as given by Fox, is that since the commencement when the fissures 
 were of small size, they have gradually been increasing in length by 
 some expansive action of the material they contained. This expansion 
 may have taken place as follows. Because a lode from the metallic 
 matter it contains is a better conductor of heat than the walls which 
 bound it, and is connected with the hotter portion of the earth it will 
 be subjected to comparatively great expansions and contractions. 
 Another suggestion is that a lode may have gradually been formed 
 by the accumulation and crystallization of mineral matter in a primary 
 fissure or joint. If we regard a lode in this way we see the probability 
 of its continunally tending to open itself and extend in length, 
 evidence of which we have in the nature and appearance of the 
 matter in many lodes, which seem to indicate that since their first 
 deposit there have been many reopenings. 
 
 It might be expected that if matter is trying to force its way 
 upwards from below it will rather tend to extend an old lode than to 
 make a new one. 
 
 of Lodes. Lodes vary considerably in length, the 
 longest lodes being generally those which are broadest. 
 
 In Cornwall the average length of a lode is about a mile, in 
 Freiberg three to four miles. In California there are lodes from 40 to 
 50 miles long. 
 
 The following are examples of the. lengths to which lodes have 
 been traced. 
 
 Wales (Cardigan and Monmouth) 6 to 9 miles- 
 
 /"Noble quartz formation... .. I 
 
 Baritic 52 
 
 HartzMts 8-10 
 
 Schemnitz 
 
The Old lode in the United Mines (Camborne) has been traced 
 about 7 miles, but in this case, as in the case of nearly all lodes whose 
 length is supposed to be great, it seems likely that mistakes may have 
 arisen by confusing two or three lodes in nearly the same "run" and 
 measuring them as if they were identical. 
 
 Strike. Among the more ordinary questions put by a visitor to" 
 the manager of a mine about a lode, is an enquiry about its direction or 
 Strike. On careful examination it will generally be found that this is 
 not usually very accurately represented by the straight lines which are 
 so often seen upon the maps of mineral districts. For not only 
 may it vary in the position of its outcrop through its having been cut 
 away by the erosion of valleys, but also it may often have irregularities 
 of its own, and a slightly waving sinuous line following a general 
 direction may be found to be more accurate that the straight one. 
 
 As before explained lodes are sometimes classified according to 
 their direction as right running lodes, counter lodes c. If the rocks 
 are regular in a district as in the gneiss at Freiberg the lodes may be 
 regular, but if the rocks are foliated and not homogeneous as in the 
 schists at Andreasburg they may undulate. 
 
 In Cornwall the general direction of strike is ENE to WSW. In 
 the north of England the right running lodes are E and W. In 
 Prussia some of the iron lodes strike N and S. In a given district as 
 at Freiberg the lodes may run in various direction. 
 
 When a lode changes its strike or dip it is said to come out of its 
 hour. 
 
 Width. In Cornwall the average width of a lode is 3 or 4 feet 
 but we have examples of lodes like the Comstock in Nevada which in 
 parts is 200 to 300 feet, or even more in width. 
 
 If we make measurements of any particular lode we shall generally 
 find that it has considerable variations either as we descend in depth 
 or as we trace it along its outcrop. This may be due to the rock at the 
 time of its formation having yielded more at one point than at another. 
 Another explanation might be that the first fissure had been a sinuous 
 line and the rocks on one side of this had subsequently been moved 
 relatively to those on the other side. Or lastly we might be able to 
 shew that erosive powers either chemical or mechanical, had acted in 
 one portion of the fissure more than in another. 
 
In making any measurements of the width of a lode we must be 
 careful to see that these are made at right angles to the walls. Some- 
 times however the lode "melts'' into the country, in which case it 
 is difficult to define the position of the walls. 
 
 If a lode h,as been opened by the rending action referred to when 
 speaking of the length of lodes, we might expect that a lode passing 
 through rocks of different characters would at different points along 
 its length have been differently affected, -an action about which 
 something might be learnt by observing if there is any connection 
 existing between the width of a lode and the nature of the rocks it 
 penetrates. 
 
 In Cornwall, Henwood observed that lodes were wider in slate 
 than in granite. The greatest width was observed where tin and 
 copper occur together. Copper lodes are wider than tin lodes. The 
 lodes are wider within 100 fms. of the surface than at greater depths. 
 Generally the width of a lode will vary with the hardness and other 
 characters of the rock through which it runs. It will also vary 
 with the nature of its own contents. In Cornwall there are lodes 10 
 ft. wide. The Great Devon Consols 42 ft. The Laxey Mine 12-18 ft. 
 The Foxdale 36 ft. At Schemnitz there are lodes 120 ft. wide. 
 At Kremnitz 30-90 ft. wide The gold-tellurium veins in Transylvania 
 are a few millimeters in thickness. The silver veins at Kongsberg are 
 only 2 or 3 in. wide. 
 
 Dip, hade or underlie. The dip of a lode may vary as you 
 descend in depth or at various points along the strike. The dip is 
 spoken of as being steep or flat. In Cornwall it has been remarked 
 that the north south veins dip more steeply than those running east 
 and west. When a lode, changes its dip suddenly it is said to " throw 
 a hook" if it increases in dip it "throws itself" while, if the dip 
 decreases it " raises itself." The Samson lode at Andreasburg dips in 
 two directions while the Abendstern Morgen lode at Freiberg dips 
 oppositely at its two ends. It has been observed that some lodes are 
 richer in their steeper portions. At Monte Catini the copper ore 
 chiefly occurred on the foot wall side of the lode. 
 
 In Cornwall it is said that if a lode dips beneath a hill, the 
 superincumbent mass squeezes out the ore, and it becomes poorer. 
 
 Depth. With the exception of veins like "gash" veins which 
 are wedge shaped openings from the surface, the depth to which veins 
 extend downwards has not yet found a limit. As examples of gash 
 
veins certain lead deposits in the Mississippi valley may be men- 
 tioned If veins are openings from the surface downwards as we 
 generally suppose them to be, their depth will probably be less than 
 that of any veins which may have been formed by fissures opened 
 from below. It is possible perhaps that veins of this latter kind 
 may be represented by one or two doubtful examples which are said 
 not to extend up to the surface of the ground. 
 
 The greatest depth to which a lode has been followed downwards 
 is at Przibram in Bohemia, where one of the mines which is still being 
 deepened has a depth of more than 1000 meters. 
 
 In July 1880 the Dolcoath mine was 410 fms. deep, Tresavean 
 340 fms. 
 
 The following are examples of the depth to which shafts have 
 reached. 
 
 Clausthal 300 fms. 
 Freiberg 230 
 Schemnitz 220 
 
 The Samson mine at Andreasburg 410 fms. At Kongsberg veins 
 2 and 3 in. wide have been worked down to 266 fms. Comstock lode 
 500 fms. (See Shafts.) 
 
 With a change of rock a vein may appear to stop, For example the 
 lead lodes of Derbyshire apparently cease when they meet the basalt 
 or toadstone. 
 
 At Freiberg some lodes become poor with depth, others however 
 become richer. Certain silver mines in Bolivia became poor with 
 depth. The gold veins in the crystalline slates of the Sal/burger Alps 
 are worked at the top of the mountains 6-8coo ft. high, while in the 
 valleys, 2000 ft. below the lodes are poor. 
 
 In N and S Carolina gold is chiefly. found in the upper part of 
 veins. At a mine in Schemnitz, gold was also only found near the 
 surface. 
 
 In California and Australia the influence of depth is not noticeable 
 while in many mines, as the silver lead mines at Przibram, there has 
 been a marked increase in the value of the ores with an increase in 
 depth. 
 
 Contents of lodes. In examining a lode we must observe the 
 nature of the various minerals it contains and the proportions which 
 these hold to each other. Sometimes we may observe that certain 
 groups of minerals are often to be seen together, the presence of one 
 
being favourable to the existence of the other. At other times the 
 reverse will be remarked, the existence of one mineral being a sign 
 of the absence of another. 
 
 The practical advantages to be derived from a series of observa- 
 tions shewing such results, are too obvious to be overlooked. 
 
 The following table shewing the association of ore in metalliferous 
 veins is given by Phillips and von Cotta. 
 
 Two Members. Three Members. Four or more Members. 
 
 {Galena, blende, iron pyrites, 
 
 r , ,, , (Galena, blende, iron jquartz and spathic iron, dial; 
 Galena, blende. | pyrites (silver ores) <^ Ct brown % par> calc spar '. 
 
 \pr heavy spar. 
 
 Iron pyrites, chal-J ro! ? P vntes Cnalco ~j galena, blende; and spathic 
 copyrite. I WW *2UST^' P / iron ' diallogite, brown spar, 
 
 {Gold, quartz, iron pyrites, 
 
 Cold auartz (Gold, quartz, iron Jgalena, blende and spathic 
 
 (pyrites. Jiron, diallogite, brown spar, 
 
 (calc spar ; or heavy spar. 
 
 ! Cobalt and nickel ores, iron 
 pyrites ; galena, blende 
 quartz spathic iron ore, dial- 
 logite, brown spar; calc spar; 
 or heavy spar. 
 
 Tin ore, wolfram. ( Tin re, wolfram, (Tin ore, wolfram, quartz, 
 I quartz. (mica, tourmaline, topaz etc. 
 
 {Gold, tellurium tetra-fGold, tellurium, tetrahedrite, 
 hedrite (various tellu-J quartz ; and brown spar; or 
 Hum ores.) /calc spar. 
 
 r . rCinnabar,tetrahedrite(P" nabar ' t elluriura ' tetra ; 
 
 Cmnabar, xetra-1 . '^.^ Jhednte, pyrites, quartz ;; and 
 
 hednte. V \ ick ^ ilver0 Wthic iron, diallogite, brown 
 
 ^spar, calc spar; or heavy spar. 
 
 Magnetite, chlor-f Magnetite, chlorite, p lagnetite \ ch ! rit !,' garnet ' 
 ite iaarnet X pyroxene, hornblende, pyrites 
 
 (etc. 
 
8 
 
 Arrangement of material in a lode. As the material in 
 a lode may be collected together in so many different manners, for 
 example it may be banded, in combs, ribbon like concentric, 
 brecciated, compact, vughy, granular, disseminated, amygdaloid al &c., 
 it is well that the arrangement should be observed because the struct- 
 ure of a lode will almost always tell us something about its history. 
 
 Sometimes we find the ore throughout the whole length of a lode 
 to be tolerably well distributed with the gangue. Generally however 
 it occurs more at one point than at another, existing in aggregations 
 known technically by such names as bunches, nests, chimneys, shoots, 
 pipes, courses, squats, &c. By carefully observing all the circumstances 
 attending such deposits, rules and reasons for material aggregating 
 more at one point than at another may perhaps be discovered. Closely 
 connected with this is the fact that the mineral in a lode is often 
 collected together in more or less horizontal zones. This is sometimes 
 so marked that from time to time it may change the whole character 
 of a mine, for example a mine which was commenced as a tin mine 
 may at a lower depth yield nothing but copper, which in turn as in the 
 case of the Dolcoath mine in Cornwall may eventually be replaced 
 by tin. Some of the tin mines in the Erzgebirge with increasing 
 depth yielded argentiferous copper. 
 
 A pocket or bonanza in the Comstock lode measured in length 
 650 ft., in depth 500 ft. and in thickness from 10 to 100 ft. 
 
 In some of the Freiberg lodes from 16 to 20 bands of quartz 
 galena, blende, and pyrites may be counted. These bands may be 
 arranged without any symmetry or in such a manner that similar bands 
 occur to the right and left of one or more given lines. 
 
 In some lodes we find pebbles and even fossils. 
 
 Relation between the direction of a lode and its 
 contents. In certain districts it has been shewn that there is a great 
 similarity in the contents of those lodes which run in similar direc- 
 tions. Thus in the Freiberg district where within an area of about 
 IO by 6 miles there are 900 lodes, we have the lodes classified into 
 groups according to their direction, the members of each group being 
 characterized by the minerals they contain. These groups are as 
 follows. 
 
 Stehende gange run between N and NE, and contain silver, galena, 
 and quartz. 
 
Morgan gange run between NE and E, and contain silver, barytes, 
 and calcite. 
 
 Spat gange run between E and SE, and contain silver and copper 
 ore, with barytes in quantity. 
 
 Flache gange run between SE and S, and contain little silver. 
 
 In Cornwall the ENE lodes yield tin, copper and sometimes lead, 
 while the NS lodes usually yield 'clay and lead. 
 
 There are however exceptions to the above rules, thus at 
 Clausthal, lodes in the same direction vary along their length, thus 
 towards the north, spathic iron decreases, quartz and blende increase, 
 barytes is rare and the galena is not so argentiferous. Towards the 
 south barytes and quartz becomes less, blende dissapears and the 
 galena is argentiferous. 
 
 In the Isle of Man we have the Laxey lodes running E and W and 
 the Foxdale N and S, but the galena they yield is equally argentifer- 
 ous. The NS lodes may however be more bunchy and unequal. 
 
 In Flintshire the galena in the E W lodes is laminated while in 
 the cross lodes it is more earthy. The E W lodes also contain a little 
 blende. 
 
 In the Duchy of Nassau and Siegen the N S and the E\V lodes 
 yield lead and iron equally. 
 
 Relation of lodes to each other. In Cornwall it has been 
 remarked by the miners, that if there is a certain portion of a lode 
 which is rich, it is not unlikely that opposite to this point the portions 
 of neighbouring lodes which are parallel will also be rich. This 
 phenomenon is expressed by saying that " ore lies against ore." In 
 order to understand this, we can imagine that at the time of the 
 formation of these lodes parallel ruptures were formed along lines 
 transversely to which the rockshad similar characters, where each 
 of the lodes crossed rocks of like character it is probable that the 
 conditions accompanying the precipitation of mineral matter would be 
 identical. 
 
 If two lodes intersect we may have them either simply crossing, 
 or we may have one of them acting as a dislocator. In the former 
 case at the point of crossing the arrangement of the materials of the 
 two lodes, may give evidence of their having been filled simultaneously, 
 or else we may have evidence that one of them was first filled, and was 
 afterwards intersected ><!e:second which was filled subsequently. 
 
 fW- **> 
 
 UNIVEKSITY 
 
10 
 
 In this latter case, and in the case where one of the lodes acts as 
 a dislocator, we are able to determine the relative ages of the two 
 lodes. 
 
 If two lodes intersect it has been observed that they often have an 
 influence upon each other. At the junction of two lodes, minerals- 
 different to those found in other portions of the mine, together with a 
 richer yield of ore, may be met with. These intersections will make 
 certain angles with each other. These angles might be observed, 
 because in some districts the obtuseness of the intersection is considered 
 as having an influence on the richness or poorness of the mineral at 
 the junction. In Cornwall it has been observed that at a junction of 
 lodes having opposite direction of dip the contents are poor, while if 
 they meet at an acute angle the contents are rich. Whilst enquiring 
 about the intersections of lodes with each other, the existence of strings 
 or small veins of ore connected with the main lode, might also be 
 considered, as these also often give rise to accumulations of ore at 
 their points of junction, which are not found in other portions of the 
 lode. In some mining localities the miners hold that if these come in 
 on the " hanging wall " side of a lode, they will be good for the 
 lode, but if they leave it from the " foot wall " side they will " rob " 
 it of its ore. 
 
 Relation of the contents of :i lode to tlae country. 
 
 When examining a lode we must also examine the rocks through 
 which it runs. Generally speaking we shall find that in most mining 
 districts these are geologically very old. However lodes are not 
 entirely confined to old rocks, as for example the copper lodes of Ani, 
 in the province Ugo in North Japan, partly run through tuffs of 
 Tertiary age. 
 
 For a district, or for a small country, it may be found that rocks 
 of a particular horizon will carry a particular set of minerals, but this 
 we shall see is probably due to the lithological character of the rocks 
 of that area and the alterations to which they have been subject, rather 
 than to their age. 
 
 However it is a well recognized fact, that certain rocks seem to 
 be favourable to particular minerals. Thus tin is very often found 
 in the vicinity of granitic rocks, whilst copper is more commonly 
 associated with serpentines, diorites, chloritic schists and slates. 
 
II 
 
 Granite yields gold, silver, copper, lead, antimony, iron, tin. 
 Schists, mica slate and clay slate, yield a variety of minerals like gold, 
 tin, copper, iron &c. Limestone yields lead in many countries. In 
 Chili and Australia it yields lead and silver. Jn Belgium it yields zinc 
 carbonate and in England iron and lead. 
 
 Observations of this kind are especially marked when considered 
 in reference to some particular district, as for example in Cornwall 
 where AVC have large bosses of granite penetrating through clay slate. 
 In the former rock we generally find veins of tin, near the junction 
 copper, whilst in the latter, at some distance from the granite are found 
 the veins of lead. 
 
 Not only does the change in character of the rock effect a change 
 in the nature of an ore, but it also causes a change in its richness. 
 
 Lead veins appear to be more influenced by the nature of the 
 country rock than almost any other kind of mineral veins. Thus in 
 Yorkshire lead is contained in fissures running through limestones, 
 shales and grits. 
 
 When the opposite walls are limestone, the lode is good. 
 \, grit and limestone, not so good. 
 
 shale and limestone the lode is worse. 
 
 shale and shale the lode is worst. 
 
 In Cardigan and Monmouthshire where the rocks are hard and 
 gritty the lodes are poor, but where they pass through slaty grey rock 
 which is fissured and shistose they are good. 
 
 At Llanrwst however a lode was best in a hard grey gritty rock 
 and at the new Llangynog lead mine it was best in a hard porphyritic 
 rock. 
 
 In Spain there was more silver in the galena from slaty rocks 
 than from the limestones. 
 
 At Lake Superior the copper lodes in the amygdaloid were 2 ft. 
 wide and productive, while in the greenstone, conglomerate and 
 sandstone they were thinner and relatively not so productive. 
 
 Sometimes lithological changes cause even greater alterations, for 
 example a vein which was rich when in one class of rocks, may on 
 crossing into a new kind of rock be so poor that it is worthless. In 
 Cornwall when granite is soft it said to be "kind" and generally 
 when granite is coarse grained and where it is not pure but contains 
 accessory minerals it is richer than in other parts. 
 
12 
 
 In Cornwall when a lode crosses an elvan it becomes either richer 
 or poorer. At Wheal Alfred the lode was poor in slate but rich in 
 elvan. The lodes are richer in light coloured slates containing mica 
 and quartz. The hard brown slates yield tin, while the blue slates 
 yield copper. 
 
 Striking examples of this are to be found in the silver veins of the 
 Falilbands of Norway. At Kongsberg in Norway the Fahlbands are N 
 and S bands of schist ^quartzose, with mica, hornblende, chlorite) 
 containing iron pyrites, magnetite and blende, which run through the 
 gneissic and slaty rocks of the district. When the E. W. veins which 
 carry silver run through the Fahlbands, they are rich. Similar 
 phenomena are observable where quartz veins carrying gold cross the 
 bands of Berezite (a kind of granite) at Berezovsky in the Urals. 
 
 Not only may the character of a lode be changed when it passes 
 from one kind of rock to another, but it may also be altered by passing 
 through varieties of the same kind of rock. 
 
 For example, the lead veins of Cornwall are usually richest where 
 the slates are soft and fissile, and poor where they are slaty and hard. 
 Or again Von Cotta tells us, that where we have granites and gneiss, 
 together with mica schist and grey gneiss, silver ores shew a preference 
 for these latter rocks rather than for the former. If we reflect upon 
 the fact that the conductivities of different rocks both for heat and for 
 electricity will have been different, it is not difficult to understand 
 that differences in the country rock should have produced differences 
 in the minerals which have been deposited. 
 
 Influence of tlie walls of a lode upon its contents. 
 
 The influence which the walls of a lode have upon the contents of 
 the lode, is evidently very closely connected with the more general 
 influence produced by the country. 
 
 There are many instances where the mineral has been deposited 
 more upon one wall of a lode than upon another as at Mount Catini 
 (See 1 Dip p. 5.) That the minerals upon the two walls are different is 
 not uncommon. Thus at the Rammelsburg mine on the west wall a 
 grey mixture of iron pyrites, copper pyrites, galena and blende was 
 found while on the east wall there was a yellow mixture of iron and 
 copper pyrites. 
 
'3 
 
 Alickensides. 
 
 The movements to which a lode has been subjected may be learnt 
 from slickensides and faults. The former are represented by polished 
 and striated surfaces of ore or gangue. These are generally only a few 
 inches in area. Sometimes however, as at the iron mines of Nijni 
 Tagil in the Urals, they may be seen upon faces of ore, the area of 
 which must be reckoned in yards rather than in inches. By observing 
 these carefully, the direction in which a movement has taken place 
 may be determined. They are sometimes observed in coal mines near 
 to faults. 
 
 The regularity or irregularity, together with the intensity of this 
 movement, may also often be made out. As these movements have 
 rendered the ground loose, and in some cases brittle, the mines in 
 which many of these slickensides occur, are often dangerous for the 
 workmen. 
 
 At the Gang mine, Cromford, Derbyshire, slickensides have split 
 themselves off with violent explosions. At the Eyan copper mine 
 they have exploded by scratching. 
 
 Faults, (slides, heaves.) 
 
 A more important class of movements which ought to be enquired 
 into are those which have produced a discontinuity in the material 
 of the lode. These are known as faults. 
 
 Some of these have been produced by fractures which have 
 intersected a bed or lode, like a more or less inclined plane. 
 
 The portion of the lode and the strata which were superincumbent 
 on the plane, are the parts which generally have suffered displace- 
 ment. The movement will usually have been down the upper side of 
 the plane. In exceptional cases the movement may have been 'the 
 opposite and a " reversed fault " produced. 
 
 The direction of movement may be sometimes seen by striated 
 surfaces, traces of mineral on the surfaces along which movement has 
 taken place, by the direction in which strata have been bent c. 
 
 By carefully studying and tabulating these movements rules for 
 the guidance of the miners may be established. It must be 
 remembered that these movements have generally taken place both> 
 
horizontally and vertically, the two motions being usually combined. 
 Schmidt who wrote on faults in 1810 gave a rule respecting the direc- 
 tion in which a miner ought to turn on meeting a fault. In 1828 
 Zimmerman who generalized on Schmidt's theory, gave a geometrical 
 interpretation of the rule which may be stated as follows. 
 
 In order to find the continuation of a lode turn to the side on 
 which a perpendicular to the fault or cross course falls with regard to 
 the line of intersection of the lode and cross course drawn in plan 
 that portion of the line of intersection and the perpendicular being 
 considered which lie at the side of the cross course opposite to the 
 side on which the known portion of the lode lies. 
 
 Striation on the walls of a faulting fissure often shew that the 
 movement has not being down the dip but obliquely across it, and 
 farther as pointed out by Professor Hoeffer there may sometimes have 
 been a partial revolution of the mass on the hanging wall of the fault. 
 Perpendiculars to such striations ought unless the revolution has been 
 accompanied by a movement of translation to give the center of the 
 motion. 
 
 Sometimes the fissures of these faults are filled with clayey 
 material or flucan, at other times with gangue and ore, so that we have 
 the appearance of one lode having intersected and dislocated another. 
 In addition to earthy matter and ore, there may also be many empty 
 spaces which become reservoirs for gas or water, rendering it a 
 necessity where such faults exist, to approach them with caution. 
 
 Lastly we may have a dyke of igneous rock acting as a dislocator, 
 which is of common occurrence in some of our coal fields. In some 
 instances these dykes have not only destroyed the continuity of a seam 
 of coal, but they have coked, charred, and reduced it to cinders, for 
 considerable distances on each side of ihe line of intersection (see p. 27.) 
 
 The throw of a fault may only be a few inches or it may be 
 several thousands of feet. In the latter case it is measured or its 
 existence is proved by the relative positions of certain geological 
 strata. The horizontal and vertical displacement will vary along the 
 length of a fault, at one end of which it may be zero. The throw and 
 width of a fault may vary with the nature of the rocks. In soft rocks 
 faults are sometimes narrow and shew striated surfaces like slickensides. 
 
15 
 
 Sometimes the strata are bent in the direction of the throw, and "dip 
 to the downthrow" and "rise to the upthrow." A fault crossing a 
 synclinal or anticlinal might throw the beds on one side of it relatively 
 to corresponding beds upon the other side, either away fro:n or 
 towards each other. 
 
 Such an effect is observable when two lodes dipping in opposite 
 directions are heaved by the same cross course, as at \Vheal Alfred, 
 where the horizontal distance apart of two lodes on one side of a faulr 
 is different from the horizontal distance apart of the same two lodes 
 on the other side. In calculating the quantity of material in a lode or 
 bed beneath a given area it must be remembered that an ordinary 
 fault may diminish that quantity while a reversed fault might increase 
 k, it being assumed that the faults are not absolutely perpendicular. 
 Faults like lodes may have branches or they may dislocate each other. 
 A trough fault may be described as two faults hading or underlying 
 towards each other. Reversed faults may be explained on the assump- 
 lion that a wedge shaped portion of the earth's crust with its apex 
 downwards has been caused to slide upwards by a horizontal thrust, 
 while an ordinary fault may be explained by the sliding upwards of a 
 wedge shaped piece with its apex upwards. 
 
 The following table gives the results of observations made in 
 Cornwall by Mr. Kenwood of 272 intersections. 
 
 (Of all the lodes the proportion intersected but not heaved 
 
 \ is 2.7 or 2.7 o/ 
 
 <^ Of the tin lodes the proportion intersected but not heaved is. 18.0 ., 
 JOf lodes yielding both tin and copper ,, 37.2 
 (Of copper, lodes 17.7 
 
 !Of all the lodes the proportion heaved towards the right 
 
 hand is 13.5 or 5.0 
 
 Of the tin lodes proportion heaved towards the right hand is. 56.0 ,, 
 
 Of the lodes yielding both copper and lin 44.0 ,, 
 
 Of the copper lodes ,, 52.4 
 
 {Of all the lodes the proportion heaved towards the left 
 
 hand is 8.0 or 3.3 ,. 
 
 Of tin lodes the proportion heaved towards the left hand is. 26 o 
 
 Of lodes yielding both tin and copper 18.6 
 
 Of copper lodes 29.8 
 
i6 
 
 Of all the lodes the proportion heaved toward the greater 
 
 angle is 18.1 or 6.7 /e 
 
 Of the tin lodes the proportion heaved towards the greater 
 
 angle is , 52.0 
 
 Of lodes yielding both tin and copper the proportion heaved 
 
 towards the greater angle is 56;o 
 
 Of copper lodes the proportion heaved towards the greater 
 
 angle is . 74.2 
 
 Of all the lodes the proportion heaved towards the smaller 
 
 angle is 3.4 or 1.3 
 
 Of the tin lodes the proportion heaved towards the smaller 
 
 angle is. 30.0 
 
 Of lodes yielding both tin and copper the proportion heaved 
 
 towards the smaller angle is 6.8 
 
 Of copper lodes the proportion heaved towards the smaller 
 
 angle is 8.8 
 
 The mean distance of the heaves of all the lodes is.... 16.4 ft. 
 
 ,, ,, ,, ,, ,, the tin lodes is !5-4 
 
 ,, ,, lodes yielding tin and 
 
 copper 14.6 
 
 The mean distance of the heaves of copper lodes 17.5 
 
 /"The mean distance of the right hand heaves is 18.7 
 
 ] ,. left hand 120 ., 
 
 jThe mean distance of the heaves towards the greater angle. 19.3 
 (. >? v * smaller 17.1 
 
 The percentage of heaves in different rocks. 
 
 In Granite. In Slate. 
 
 The intersections without heaves 26.2 /o 21.5 /a 
 
 Heaves towards the right hand 5 2 -4 5-5 
 
 ,, left hand 21.4 ,, 26.0 
 
 greater angle 65.6 64.0 
 
 ,, ,, smaller angle 8.2 14.5 
 
 The mean distance of all the heaves is 16.4 ft, 
 
 ,j in Granite 17.1 
 
 > , ,, t Slate 16.3 
 
 The 233 intersections consist of 125 veins of clay or flucan and 
 108 quartzose veins or cross courses. They are distributed as 
 follows. 
 
In Granite. In Slate. 
 
 Flucan 78.7 /o 47.0 
 
 Cross course 21.3 53.0 
 
 From this it is seen that in granite the cross veins are generally 
 flucans while in the slate they are quartzose. 
 
 From other tables Mr. Kenwood shews- that the extent of heaves 
 is in direct proportion to the width of the lodes and to that of the 
 cross vein. 
 
 It appears as pointed out by Mr. Henwood, that the general rule 
 is that the heave of the same lode by the same cross course is in the 
 same direction at all depths. Exceptions to this however occur, as at 
 Gunnis Lake. 
 
 The heaves towards the greater angle chiefly occur with flucans. 
 
 The agre of faults and lodes. 
 
 If a fault or lode cuts through a series of rocks A but does not 
 pass upwards into a set of rocks B, we may assume that the lode is 
 younger than A but older than B. For reasons like this we may say 
 that the E and W veins of Cornwall which break through the Trias 
 are younger than that formation, while the N and S veins which break 
 through Cretaceous rocks are younger than the Cretaceous. Many 
 of the veins in California are younger than the Jurassic. When a vein 
 intersects another vein it is evident that the intersected vein is the 
 older of the two, or if a vein contains fragments of a bed or of 
 another vein, the vein containing these fragments must be younger than 
 the bed or vein from which they were derived. 
 
 As examples of veins of relatively recent age Phillips gives the 
 following. 
 
 At Aveyron in France veins of argentiferous galena traverse 
 Liassic strata. In Algeria similar lodes are of Cretaceous age. 
 Auriferous quartz veins at YSrospatak in Transylvania in Tertiary 
 sandstones. Near Volcano in Amador county California, there is a 
 quartz vein cutting beds of sand and gravel, while at Steamboat Springs 
 in Nevada the writer has seen veins in- the process of formation. 
 
 When a lode B passes through but not beyond the walls of a lode 
 A and the continuation of B is somewhere to the right or left of the 
 point of intersection, it would appear that as B was thrown by A, that 
 
i8 
 
 B was the older lode. It may however happen that A is older than 
 B, the throw of B having been due to a movement along one wall of A 
 after it had been intersected by B. 
 
 Rucks of lodes, basset, broil, gossans fcc. If the material 
 of which a lode is composed is harder than the rock through which it 
 runs, by processes of degradation it may be left standing up like a 
 ridge or wall. In the Atlas Mountains lodes of spathic iron with 
 barytes stands up above Cretaceous rocks. Other examples are in the 
 lead lodes of Cardigan and Montgomery, certain quartz lodes in 
 Australia &c. On the other hand if it is softer, it is worn away to 
 form a hollow. In both cases its direction will be more or less marked 
 across the country through which it courses. 
 
 In the latter case it may form a channel along which water will 
 percolate, in consequence of which we may have a line of luxuriant, 
 or of some particular kind of herbage springing up. 
 
 In many cases the exterior portions of a lode will be more or less 
 decomposed to form a mass of friable earthy matter, which from the 
 presence of iron is generally of a red colour. This is called a gossan. 
 (eisennerhut. Gr., chapeau defer, Fr., pacos, colorados, Sp.} 
 
 These gossans ought to be carefully examined as they often give 
 a good idea of the nature of the minerals which will be found at a 
 lower depth. For example at the surface we might have earthy red 
 oxide of iron, while lower we might find oxide of iron with oxide and 
 carbonate of copper and native copper, still lower copper pyrites. 
 Generally in gossans we find oxides and oxidized salts, combinations 
 with water, carbonic acid, phosphoric acid, bromine, chlorine &c., 
 but no sulphides. Copper pyrites may change as follows 2 (Cu Fe S.) 
 + 11 O = 2 Cu SO 4 -fFe2 O 3 ; or galena after becoming a sulphate may 
 suffer farther transformation in the presence of calcium carbonate into 
 lead carbonate and calcium sulphate. Native metals often occur in 
 gossans thus at Lake Superior native copper and silver were chiefly 
 found near the surface. In Cornwall the average thickness of the 
 decomposed portion of a lode is from 30 to 40 fathoms, but there are 
 instances where it has been as much as 150 fathoms in thickness. 
 When a lode is very porous, and contains much iron pyrites we may 
 expect to find a good gossan. In such cases it will be of a red colour. 
 If the color is dark and quartz is absent the gossan is considered good 
 
19 
 
 Sometimes the gossans are of a bluish green colour, due to the decom- 
 position of a copper ore, or greenish and brownish from a lead ore. 
 These colours however are rare, the one produced by iron generally 
 masking all others. According to its structure and colour a gossan is 
 described as sugary, tindery, irony &c. 
 
 By carefully observing the phenomena which gossans present to 
 us, much may be learnt about the transformations to which mineral 
 matter is subject. 
 
 If the back of a lode reaches to the surface., the soil which lies" 
 upon it will generally be more or less affected, and the growth of 
 vegetable matter will be prevented. In consequence of this we shall 
 see along the line of a lode either barren strips of soil, or a peculiar 
 vegetation. 
 
 In most countries a good gossan is regarded as being indicative 
 of a good lode, and there are cases on record where a mine has been 
 taken up from the appearance of its gossan. In Cornwall it is said 
 that, 
 
 "A lode will ne'er cut rich and fat, 
 Unless it have an iron hat." 
 
 The depth to which a gossan may reach greatly depends on the 
 drainage level. 
 
 Gaetzschmann gives a long list of plants indicative of saline 
 spring. Dumps of red and brown hematite or clay iron stone grow a 
 special vegetation chiefly malvaceous. The Calamine hills of West- 
 phalia have a peculiar, flora, a most noticeable plant being Viola 
 Calaminaria. In Michigan, Wisconsin and Illinois we have the lead 
 plant Amorpha canescens. 
 
 An iron ore vein near Siegen can be traced for nearly two miles 
 by birch trees growing on its outcrop. In Montana an Eriogowini is 
 said to be indicative of silver ores. An analysis of this plant shewed 
 the presence of arsenic (see Indicative Plants by W. Raymond. Trans. 
 Am. Inst. Min. Eng. Vol. XV. p. 644). 
 
 When certain minerals are decomposing a slight odour might be 
 produced, this being especially noticeable when the weather is warm 
 and showery. 
 
 Over the backs of certain lodes, lambent flames are said to have 
 been sometimes visible, an appearance which may have been due 
 to decomposition. If these decompositions give rise to heat, we 
 
might expect that snow \vould not remain so long over the backs of 
 lodes as at other places. And it may also be remarked that as the 
 contents of a lode may be better conductors of heat than the rocks 
 of the neighbourhood, independently of the effects of decomposition, 
 more heat will constantly be conducted out of the ground along the 
 back of a lode than at other places. 
 
 These together with other appearence.s and phenomena which the 
 backs of lodes present to us, are well worthy of our attention, as it is 
 by them that we are guided when searching for mineral desposits. 
 
 Distinction between bedded veins and beds. 
 
 It may sometimes happen that a fissure has been formed parallel 
 to the stratification, which opening has subsequently been filled like a 
 lode. 
 
 As deposits 6f this kind have often great resemblances to those 
 members of a stratified series which are included under the head of 
 beds or layers, it is necessary that the observer should be on the 
 alert to sei/e those signs which may aid him in making the necessary 
 distinction. Thus for instance if the deposit has a banded structure, 
 we shall know that it is a vein with which we are dealing. Or again, 
 if it should send off branches into the surrounding strata, or if it 
 includes fragments of the superincumbent rocks, we should also see 
 that it could not belong to a series which had been regularly 5-trati- 
 fied. 
 
 Filling- of Veins. It has already been pointed out that fissures 
 which when filled with mineral matter constitute mineral veins, may 
 either be one of the results of secular contraction or they may have 
 been gradually opened and at the same time filled by the crystalliza- 
 tion of mineral matter along a primary fissure. 
 
 The following theories refer to the formation and filling of veins. 
 
 1. Contemporaneous Formation. This theory implies 
 that a lode was built up at the same time that the rock which 
 encloses it was formed. This theory fails to explain any of 
 the many observed phenomena which lodes present. 
 
 2. Igneous Injection. In this theory it is assumed that veins 
 were formed and filled by the injection of igneous matter 
 from below. In support of the view that certain veins may 
 
21 
 
 have been filled in this manner we have the fact that many 
 minerals may be produced artificially during the process 
 of fusion. Ebelmen and Berthier by decomposition in the 
 presence of fluxes like boracic acid produced crystals of 
 corundum, emerald, quartz, etc. We also known that many 
 metals occur in eruptive rocks. At Lake Superior there 
 are copper lodes in amygdaloid, but as pointed out by Phillips, 
 if the copper had been deposited from igneous fusion it would 
 have been alloyed with the silver with which it is associated. 
 Some of the lodes at Scheinnitz may be of eruptive origin. 
 
 The mullock veins of Australia are decomposed eruptive dykes 
 with gold and silver in their joints, the concentration of metal having 
 probably taken place in conjunction with the decomposition. 
 
 Notwithstanding the above facts it is only in an extremely few 
 instances that the hypothesis of igneous injection is sufficient to 
 explain the phenomena presented by lodes. 
 
 3. Electric Currents. It seems possible that metals may 
 have been precipitated in lodes from solutions of their salts by 
 means of electric currents. Mr. R. W. Fox experimented on 
 the electric currents which he observed in the lodes in Corn- 
 wall. In a summary of his views he remarks that with the 
 electrical decomposition of earthy and metallic salts the bases 
 would be deposited at the electric negative pole but a rock 
 which was electro negative in one position might be electro- 
 positive in another. 
 
 The experiments made by M. Becquerel and independently by 
 Mr. Fox have shewn how varions metals may be precipitated by feeble 
 currents and how materials like clay, plaster of paris, and even soft 
 sandstone may become laminated and generally alter their struct- 
 ure. 
 
 At Pennance mine the current flowing between a copper and a 
 pyrites lode was found to be sufficient to produce electro-type copies 
 of medals, electro magnets, and even to occasionally yield faint sparks. 
 Many of these currents may be the result of chemical decomposition in 
 a lode or of chemical action at the earth plate. The most elaborate 
 investigations on this subject made during recent years are those 
 
22 
 
 carried out by Carl Barns on the Comstock lode. The hypothesis was 
 that as currents (probably hydro-electric) had been flowing for many 
 years, such currents had become constant, equipotential surfaces might 
 therefore be discovered and mapped. The result of the work indicat- 
 ed that in certain instances an electrometrical survey of this descrip- 
 tion might lead to the discovery of ore bodies (United States Geolog: 
 Survey. Monograph III.) 
 
 Thomson has said that thermo-electric currents in the earth can 
 never have been of any appreciable magnitude, but the electric 
 currents in the earth which have caused terrestrial magnetism, or 
 which may have been an effect of terrestrial magnestism, are quite 
 competent to produce electro-metallurgical processes of the greatest 
 magnitude. 
 
 Under particular circumstances by electric actions, metals might 
 be successively precipitated from a solution containing a mixture of 
 salts. The order in which these precipitations would take place must 
 be sought for by the laws of electrometallurgy. Such an action would 
 also give a possible explanation of the sequence in any bands we might 
 observe. 
 
 If material is being deposited by electric actions we must remem- 
 ber that such currents although on the whole travelling in one direc- 
 tion more than in another, go oppositely every day. This therefore 
 whilst tending to give a greater deposit on one side than on another, 
 might possibly be employed to explain why we sometimes find the 
 same metal deposited en two sides of a lode. 
 
 4. Aqueous deposition from above. 
 
 That fissures were filled by the flowing in of metalliferous solution 
 from above was a theory propounded by Werner. It received great 
 support from Mr. "W. Wallace who wrote on the lead veins in the 
 north of England. Amongst many other observations Mr. Wallace 
 points out that the lead chiefly occurs in the rocks favourable to the 
 descent of water, while at great depths which are unfavourable for the 
 descent of water the veins contain but little lead. 
 
 5. Sublimation. 
 
 At Nagyag in Transylvania metallic arsenic has been deposited on 
 the lower faces of crystals of diallogite. This is a fact supporting the 
 
23 
 
 view that at least a portion of the material in such a vien has been 
 deposited by sublimation. That metallic minerals like iron glance are 
 formed on the lavas of certain volcanoes is also a fact supporting the 
 same theory. Many minerals like magnetite, galena, blende have 
 been formed in smelting furnaces. Durocher and other experimenters 
 have succeded in forming many minerals by passing metallic vapours 
 through heated tubes. Notwithstanding these facts it would seem that 
 the cases where metals have been deposited by sublimation are 
 extremely rare. 
 
 6. Lateral secretion. 
 
 The theory which best explains the phenomena of ordinary lodes 
 is that their contents have been deposited from solution, the solutions 
 having been mineralized by percolation through the country rock. 
 
 Among the numerous facts which support this hypothesis may be 
 mentioned. 
 
 1. The contents of many veins are similar to the rock through 
 which they run. Thus in limestone we find veins of calcite, 
 in silicious rocks veins of quartz &c. 
 
 2. All waters contain mineral matter in solution. In the waters 
 from mines many of the elements have been detected. 
 Copper as sulphate is sometimes found in sufficient quantity 
 to be of commercial value. In sea water, silver, lead, copper, 
 iron and zinc have been found. It is said that the Munz 
 metal on ships which have been for some years at sea has in 
 certain instances increased in the percentage of silver it con- 
 tained. The author found that this was not the case with 
 the sheathing of a vessel which had been for some years in 
 the North Pacific. 
 
 At Steamboat in Nevada, silica and metallic minerals like 
 cinnabar may be seen in the process of deposition from hot 
 water. 
 
 3. The artificial production of many minerals by deposition from 
 solution as for instance in the experiments of Senarmont. 
 
 4. The fact that the country rock of metalliferous regions 
 contains metallic elements. The proof that there is a relation 
 between the mineralogical contents of mineral veins and the 
 nature of the rocks is due to Prof Sandberger. Instead cf 
 
24 
 
 making a general analysis of the rock Prof: Sandherger 
 separately analysed its mineral constituents and in this way 
 he found nearly all the elements which occur in veins. 
 
 Thus in olivine, iron, nickel, copper, and cobalt were found. In 
 augite, copper, cobalt, iron, nickel, lead, tin and zinc have been 
 found. The micas yielded many metals. Copper is found in nearly 
 all clay slates. 
 
 Where organic matter is present as in the Mansfield slates it has 
 probably acted as a reducing agent, converting sulphates into 
 sulphides, precipitating silver gold &c. 
 
 5. Many of the phenomena presented by veins as for instance 
 their banded symmetry which is so often observed. 
 
 7. Solution and ascension. 
 
 In this theory it is assumed that the material which fills up a lode 
 has been brought in solution from great depths and not from the rocks 
 in the immediate vicinity of the lodes. The heat and pressure at 
 great depths would certainly favour solution. 
 
 In looking at the various theories which have been advanced to 
 explain the formation of mineral lodes, which have been enumerated 
 in the order given by Phillips, the one most adequate to explain the 
 various phenomena we meet with in lodes is that of lateral secretion. 
 As to the exact manner in which matter has been precipitated in veins 
 we have but little definite information, in one instance it may be due 
 to cooling, in another the precipitation may be chemical while in 
 another it may have been electrical. 
 
 II. BEDS AND J.AYERS. 
 
 Their formation and subsequent alteration. 
 
 The beds and layers with which the miner has to deal, are those 
 members of a stratified series which are made up of useful minerals. 
 
 At the time of their deposition they were more or less horizontal 
 and uniform in character over large areas, the only variations to which 
 they would be subject, being similar to those we might expect in a 
 sediment which was being formed upon the bed of a lake or of an 
 
ocean ; for instance we might expect the material which was 
 accumulating near a shore line to be coarser than that which was 
 being deposited in deeper water, also there might be gradations in 
 thickness &c. After a bed had been formed, by denudation and 
 metamorphism it might suffer many changes. 
 
 Thus for instance channels of water running across abed may wear 
 it out into hollows. These may subsequently be rilled with sand and 
 extraneous material. By actions like these we get the appearances 
 known to coal miners as swells and kmickle saddles, trough saddles or 
 channels. Or again metamorphic actions may raise beds up from their 
 original horizontal positions and bend them into gentle folds or into 
 the most varied convolutions. When we observe that changes in posi- 
 tion have taken place we generally find that chemical, lithological, 
 and physical changes have also been induced. 
 
 By studying all these variations of position and of character which 
 beds have suffered during and subsequent to their deposition, much of 
 their history may be learnt, which is not only of value scientifically, 
 but is also of value to the practical miner, enabling him to form rules 
 both general and special for the district in which he is employed. 
 
 Beds of coal, ironstone Ac. 
 
 The most common of bedded deposits with which a miner has to 
 deal are those of coal. These occur in seams generally from 2 to 4 feet 
 in thickness, but in some cases, as in the brown coal of Bohemia, as 
 much as 80 to 90 feet in thickness. 
 
 In examining these beds their thickness, strike, dip, depth from 
 the surface, with all their variations, ought to be observed. Also 
 the partings, faults, and other irregularities, together with the various 
 effects which they have produced upon the seam, must be noted. 
 
 Many kinds of iron ore are found in beds, the most common being 
 perhaps the clay ironstone of the coal districts of England &c. 
 
 Beds and layers are also known as strata, measures, sills, mines, 
 bassets, delfs, girdles. 
 
 The dip which may be measured by degrees or by so many inches 
 per yard is sometimes spoken of as the pitch or hade. In connection 
 with the dip we hear the terms, " strong dip " " rearing measures," 
 when the dip is steep, while when it is gentle a seam is said to be 
 u flat." The deepest portion of a set of workings are said to be on the 
 " dip side," while the shallower workings are on the " rise side." 
 
26 
 
 As examples of Coal seams having a steep clip we may take those 
 of Belgium, North France, Pennsylvania, North Japan &c. For ex- 
 amples of coal seams bent into zig zags the student may refer to the 
 Anzin district. Irregular masses of coal are found at Creuzot, Mont- 
 chain &c. (see Ponson). 
 
 Thickness of Coal. In Bohemia, France and Hungary, there 
 are beds of Lignite from 60 to 100 feet in thickness. The Bezenet 
 seam is up to 200 ft. Brown coal at Zittau in Saxony reaches 154 
 ft. in thickness. In Staffordshire there is a bed of bituminous coal 
 IO yards in thickness. Seams which are ordinarily worked are from 
 4 to IO feet in thickness. A seam 2 V 2 ft. thick may be considered as 
 thin. In Somersetshire seams 1 1 in. thick are worked. In the Hartz 
 mountains a seam from 15 to 20 cm. in thickness is worked. Seams 
 like these latter can only be worked when the coal is of a qualtity that 
 will command a special market, as for the manufacture of gas or 
 metallurgical purposes. 
 
 Irreg-nlarities nd Impurities. Most of the large seams as 
 for instance the " ten yard seam " of Staffordshire are usually an as- 
 sociation of seams, in which we find coals of varying quality which 
 may be in juxtaposition or separated by bands of shale or sandstone or 
 other worthless materials called " partings" In this manner certain 
 seams maybe subdivided into 20 or 30 distinct layers. 
 
 In a seam of coal at Pictou 116 inches thick, there are 14 layers of 
 shale with a total thickness of 19 in. 21 layers of tolerably good coal 
 and 4 layers of coal containing iron pyrities. From an example of this 
 sort it maybe inferred that in a given seam of coal we might find coal 
 fit for making gas, for metallurgical purposes, suitable for domestic 
 purposes, fit for coke, worthless coal, shale &c. 
 
 A heavy mass of impurity say, of sandstone, thinning away at its 
 ends, occurring in a seam of coal is known as a hotse, its two ends 
 being respectively its head and tail. 
 
 Seams of coal are sometimes traversed by more or less pronounced 
 systems of jointing which give it a tendency to split in definite direc- 
 tions. The planes of division are known ys cleats, faces, slynes. If 
 there are two sets of joints one may be called backs and the other 
 cutters. Jn consequence of these fractures some coals break into 
 cuboidal, rhomboidal or other regular forms. 
 
If a seam of coal is in contact with an igneous rock it may be fri- 
 able, earthy, cindery or like coke, the changes having been produced 
 by the heat of the dyke. The altered coal is sometimes called blind 
 coal. 
 
 It has been remarked that the lower beds in a series, or the lower 
 portions of a given bed sometimes are more anthracitic in their charac- 
 ter than the seams or portions lying at a higher level. 
 
 Again the beds which are the most tilted or which occupy the 
 regions which have been most contorted are usually more anthracitic 
 than those which are relatively flat and lie in the undisturbed regions. 
 This is exemplified in the coal seams of South Wales and Pennsylvania. 
 
 Along its outcross a seam of coal may be so changed that it can 
 hardly be recognized as coal. 
 
 Seams in a district. The number of seams in a given district 
 or coal basin are very different. Thus at Newcastle there are about 
 40 different seams, at Mons in Belgium about 116. 
 
 Age of Coal. In Europe and America most of the coal which 
 is worked is of carboniferous age but seams are known of various 
 ages. Thus at Brora in Scotland and in Virginia there is a miocene 
 lignite. In Japan most of the coal is tertiary or cretaceous. 
 
 Analysis of Coal. The following are maximum and minimum 
 values for the carbon contained in various coals compiled from data 
 given in Dana's System of Mineralogy. An analysis of Peat and Wood 
 are added to the table. 
 
 C H O N S Ash. 
 
 Anthracite. S. Wales 92.56 3.33 2.53 1.58 
 
 Pennsylvania 84.98 2.45 1.15 1.22 ... 10.20 
 
 Caking coal Pas de" Calais 86.78 4.98 5.84 2.40 
 
 Zwickau 72.27 4.16 10.73 0.34 o.Si 6.00 
 Non-caking coal Valenciennes 90.54 3.66 2.70 3.10 
 
 S.Staffordshire 72.13 4.32 17,11 0.54 6.44 
 
 Cannel coal Wigan 84.07 5.71 7.82 8.94 
 
 Tyneside 78.06 5.80 3.12 1.85 2.22 8.94 
 
 Brown coal Hesse Cassel 71.71 4.85 21.67 ... 1.77 
 
 Irkutsk 47.46 4.56 33.02 14-95 
 
 Peat 58.00 55 29.0 1.5 6.00 
 
 Wood 50.00 6.0 41.5 1.0 1.5 
 
28 
 
 All ordinary coals contain from .5 to I or 2 per cent of water. 
 The lignites may contain from 12 to 40 per cent of water. Anthracites 
 have a S G of 1.3 or 1.4. Bituminous coals about 1.25 and lignites 1.2 
 or i.i. From an examination of the above table it will be observed 
 that during the process of the formation of anthracite from vegetable 
 matter there is a loss of oxygen, hydrogen and nitrogen and therefore 
 an increase in the percentage of carbon. 
 
 Formation of Coal. It is difficult to accurately trace the 
 changes which vegetable matter has passed through to produce the 
 different varieties of coal, which chiefly depend upon the purity of the 
 coal, its degree of bituminization and the proportion of fixed and 
 volatile matter it contains. Le Conte ascribes the origin of these 
 varieties to decomposition of vegetable matter in contact with air and 
 out of contact with air. Anthracite is an extreme form of coal pro- 
 duced by heat and metamorphic action. 
 
 Pengelly regards the formation of coal after the primary decom- 
 position of vegetable matter, to have taken place in four ways. 
 
 By a dry process with heat (Ex. anthracite). 
 
 By a dry process without much heat (Ex. steam coal, Wigan 
 cannel). 
 
 By a wet process with heat (Ex. bituminous house coals). 
 By a wet process without much heat (Ex. certain bituminous coals 
 and lignite). 
 
 Iron Ore. 
 
 Clay iron stone occurs in beds as concretionary nodules associated 
 with coal and coal shales in South Wales, and Staffordshire. Some- 
 times it occurs as a bituminous shale as for example the black band ore 
 in Scotland. These ores are chiefly carbonates and contain 20 to 30 
 per cent of iron. 
 
 Beds of iron stone also occur in liassic and oolitic strata in 
 Yorkshire, Northamptonshire, and Lincolnshire. These ores are 
 hydrated oxides of iron containing 25 to 30 per cent of iron. 
 
 Hematite occurs in beds containing 60 per cent of iron as in 
 Missouri, Michigan etc. These ores are usually siliceous. In Algeria 
 there is a bed 5 yards thick which is said to contain 65 per cent of 
 iron. At Cleator, Moor, Cumberland, there is a deposit 60 ft. thick. 
 
2 9 
 
 Copper Ores. The Kupfer schiefer of Prussia is a stratified 
 deposit of bituminous marly slate containing various ores of copper 
 together with iron pyrites, galena, zinc, nickel, cobalt, silver, bismuth 
 &c. At Mansfeld it is 1 1 to 20 in. thick and yields from 2^ to $% 
 of copper. Cupriferous shale beds have been worked in Shropshire 
 and in China. 
 
 At Alderly Edge in Cheshire a bed near the base of the new red 
 sandstone is saturated with blue and green carbonates of copper. It 
 yielded \}4 to 3 per cent of copper. 
 
 At the Parys mine Anglesea, there are beds mineralized with 
 copper. Copper is also precipitated from the water pumped from the 
 mines. 
 
 Snl*. In Cheshire 75 to 100 ft. thick. The Sperenberg bore 
 hole passes through 3,890 ft. of saliferous strata. 
 
 Lead ore. The Bunter sandstone of Bleiberg yields nodular 
 lead ore, chiefly galena but also cerussite. 
 
 Most of the beds containing minerals like copper and lead are 
 the results of mineralization subsequently to the original formation of 
 the beds. 
 
 Sulphur. Occurs in beds in Sicily, Greece, Yezo. and other 
 countries. 
 
 Surface deposits. 
 
 By surface deposits we mean those beds, of alluvium which more 
 or less cover the face of all countries. 
 
 These have been chiefly created by various mechanical agents, 
 which after having degraded the higher rocks carry the material which 
 has thus been formed down to lower levels. By degradation most 
 mineral deposits are so comminuted, that by their exposure tc the 
 atmosphere they are decomposed and destroyed. Substances like 
 cassiterite, platinum, gold, &c. being exceptions to this, that is not 
 being so readily subject to decomposition, have in consequence been 
 more or less preserved and buried amongst these surperficial deposits. 
 
 In observing deposits of this kind, we must notice their general 
 situation, area, thickness, and richness. Often we may have several 
 beds ranged one above another, in which case we may have to deter- 
 
3 
 
 mine their relative value. If we are tracing any particular deposit, as 
 for example whilst ascending a valley, if the particles of ore increase 
 in size and in number, we may expect that we are approaching their 
 common origin. Another indication that we are near this point of 
 origin will be that we shall find the mineral less worn. 
 
 In looking for a deposits of this kind, in a country where superficial 
 deposits are known to occur, we may be often guided like the Tung- 
 usians in Northern Siberia, who search for gold by first looking at the 
 general contour of the country, and observing those places where any 
 obstacles like a projecting range of hills would be likely to prevent 
 material being directly washed from higher to lower ground. Holes, 
 sudden bends, or anything which would cause a diminution in the force 
 of a current of water, are points at which we should expected that 
 heavy material like gold or platinum would be likely to collect. In 
 Australia although the most gold is generally found in pot holes and 
 behind hat d bars, it has often been found upon the shallow bends of 
 ancient river courses. The lowest of a series of beds is generally the 
 richest. This may be perhaps explained by a Hypothesis due to Mr. 
 Belt who suggested that because large nuggets of gold are only found 
 in the alluvial deposits, therefore the upper portions of the lodes or 
 deposits which were first worn away, were richer than the lower por- 
 tions. The more probable reason is that it is due to the action of 
 gravity. Another reason for finding large nuggets in the alluvium 
 may be due to their having been formed in situ by precipitation from 
 a solution of chloride. 
 
 Chloride of gold is precipitated in the presence of vegetable 
 matter with considerable rapidity. Gold has been found in fossil wood 
 and in mine timbers. 
 
 By observing the nature of the associated minerals, which may be 
 in the form of gravel or sand, we may often learn something about the 
 rocks from which the deposit originated. 
 
 By carefully examining these surface deposits we shall find that 
 like lodes, they have many peculiarities. Thus the alluvial deposits 
 of gold in the Urals are said to be chiefly, and almost only, found on 
 the Eastern flanks of these mountains, a fact which points to the 
 mountains of Asia, rather than to those of Europe, as being the source 
 from which they originated. 
 
In Australia the best wash-dirt is on the bed rock in the lowest 
 parts of a lead called the gutter. The gravels of ancient river courses 
 in which it occurs may be on the surface or at the depth or several 
 hundred feet being covered by beds of basalt (blue stone) or even 
 beneath a hill. 
 
 The largest nugget was the " Welcome stranger " 2,268 oz. In 
 1876 in Victoria 574,164 tons of drift averaged 22.67 grains of gold per 
 ton ; 35,938 tons of cement which required crushing yielded 4 dwt. 
 J 3X grains per ton. Certainly drifts have yielded 10 dwts. to 2^ oz 
 per cubic yard. 
 
 In California the gold bearing beds are from six to several hundred 
 of feet in thickness. They usually consist of gravels which may be 
 cemented to form a conglomerate, sands, , bands of tuff, clay, fossil 
 wood etc. They from a band 60 miles wide along the western flanks 
 of the Sierra Nevada. The big Blue lead extends 65 miles and has a 
 depth of from I to 300 feet. Three or four cents per cubic yard will 
 pay the expense of hydraulicing but near the base of certain leads as 
 much as 10 per cubic yard has been obtained. 
 
 Magnetite occurs in alluvial deposits. In North Japan it seems 
 to be uniformly distributed through nearly all the soil that is met with. 
 In places it has collected together in beds and is smelted. 
 
 Bog iron and manganese ore which have accumulated by precipita- 
 tion in marshy places or in lakes usually contain too much impurity 
 to be of commercial importance. 
 
 Stream tin occurs in gravels much in the same way as gold. 
 
 B. IRREGULAR DEPOSITS. 
 I. SEGREGATIONS. 
 
 Segregations, like veins, occur in rocks of various descriptions. 
 Sometimes they appear in a^jjorm which is more or less vertical ap- 
 proaching in character {j/%c\&$ t f. -other times they approach in 
 character ,o a bed. 
 
 , . 
 
 - A I ICr, 
 
32 
 
 Under this head we have Stockworks or floors, may Contact 
 deposits, and irregular deposits like those occurring in limestones. 
 
 Slock work si consist of a number of small veins of ore running in 
 an irregular manner through a large mass of rock. 
 
 The relation of segregations to the rocks in which they exist is 
 unfortunately not so definitely marked as in the case of veins, never- 
 theless certain relations may be sometimes observed, as for example at 
 Tilt Cove in Newfoundland, where we have huge segregations of 
 copper pyrites showing a preference to a particular band of serpentinous 
 rock about 200 yards in width, whilst in the neighbouring rocks out- 
 side this band no metals are found. 
 
 Although the phenomena presented by segregations are difficult to 
 understand, nevertheless they may perhaps be interpreted by a 
 careful observation of the appearances which these deposits present us 
 with. 
 
 II. 
 
 The greater number of impregnations have probably been formed 
 by the permeation of mineral matter through the rocks in which 
 they occur, the matter at the time of this permeation being in the 
 state of gas, fusion, or solution. 
 
 It often happens that impregnations occur in the immediate 
 vicinity of deposits like lodes, or segregations. In such a case it 
 remains for us to decide whether the impregnation was derived from 
 the mineral mass, or vice versa, not forgetting that it is also quite 
 possible that the two might have been simultaneous formations. 
 
 From the manner in which the ores occur something may be learnt 
 about the origin of an impregnation. Thus for instance some im- 
 pregnations can only be regarded as the colouring matter of the rocks 
 they penetrate, at once suggesting the idea that they originated from 
 the infiltration of some solution. The red colour of certain sandstones 
 which are coloured by a pelicle of oxide of iron surrounding each 
 grain, are known to have been formed in this way. Again, the green 
 coloured deposits of copper at Alderly Edge in Cheshire, may be taken 
 as another example. 
 
 The impregnating ore may pass in films through a rock, or it may 
 be distributed in grains and globules. Sometimes it may occur in 
 crystals like the crystals of feldspar in a porphyry, a good example of 
 
33 
 
 which we have in a deposit of galena on the Port au Port peninsula,- 
 Newfoundland, where the ore is distributed in small cubes through a 
 mass of soft silurian limestone. 
 
 In some few instances we seem to have evidence of particles of 
 mineral matter having been deposited together with sediment to form 
 one of the members of a stratified series. Although the resultant beds 
 might be said to be impregnated, it is perhaps better that they should 
 be classed with the regular deposits. 
 
 Even if a bed should subsequently to its formation become im- 
 pregnated with metallic matter, it may be convenient from its 
 regularity to place it with the same group. 
 
 Examples of mineralized beds have already been given (p. 29). 
 
 As it is evident that the formation of an impregnation, must to a 
 great extent be dependent on the physical and chemical nature of the 
 rocks in which it has been precipitated, it is scarcely needful to remind 
 the student that a study of those rocks may be fraught with the 
 greatest interest, and valuable results may be obtained. 
 
 EXAMPLES OF IRREGULAR DEPOSITS 
 
 (Segregations' m and Impregnations). ' '. 
 
 1. Contact Deposits. 
 
 In Arizona red oxide of copper occurs between limestone and 
 granite and slate rocks. At the Tanokuchi mine, Tosa, Japan, copper 
 pyrites, between clay slate and diorite. Lake Superior, native coppei 
 between trap and sandstone. 
 
 At Chessy near Lyons, where there are ancient copper mines, 
 deposits occur in and between metamorphic rocks and Bunter sandstone. 
 In the metamorphic crystalline rocks there are yellow ores (copper and 
 iron pyrites) grey and black ores (melaconite, iron pyrites etc.) which 
 occur in a wedge shaped bed of grey rock between the crystalline 
 rocks and the sandstone ; red ores (cuprite) occur in clay against the 
 sandstone; blue ores < % azurite etc.) occur in nobules in the sandstone. 
 The original deposit from which the others were derived was the 
 yellow deposit. 
 
 Comstock Lode, Nevada. Here there are silver ores between 
 diorite and diabase. In places it is altogether in the diabase. Be- 
 
34 
 
 tween 1859 and June 1880 it produced $175,000,000 of silver and 
 $140,000,000 of gold. 
 
 Near Christiana at Narverud and Danemora near Upsala there 
 are contact deposits of magnetite between granite and slate. 
 
 At Clausthal there are deposits of hematite between similar rocks; 
 
 Running N. and S. for 150 miles through Servia there is a band of 
 syenite, greenstone &c. which traverses Jurassic and cretaceous rocks. 
 Between the eruptive rocks and the metamorphosed sedementary rocks 
 there are many contact deposits yielding gold, copper and iron pyrites, 
 galena, magnetite &c. They are described in detail by von Cotta. 
 
 2. Imbedded in Igneous or Non-stratified Rocks. 
 
 At Zinnwald (Bohemia) in a dome shaped mass of greisen (quartz 
 and mica) there are horizontal narrow veins of tin, forming stock- 
 works. 
 
 At Altenberg there is a greisen like rock called zwitter, through- 
 out which tin is finely disseminated to the extent of y$ or y z per cent, to 
 form a stockwork. Somewhat similar deposits occurs in granite. In 
 Cornwall small veins of tin were discovered at the china clay works near 
 .St. Austell. Some of the veins which run through granite consist of 
 schorl and quartz. Near Stanthorpe in Queensland, grains of tin are 
 disseminated through a granitic rock as if forming one of its chief 
 constituents. 
 
 The carbonas at St. Ives are masses of coarse granite charged with 
 tin and connected with the lode by a film of quartz. 
 
 At Monte Catini in Tuscany the cretaceous strata is broken 
 through by serpentine and gabbro rosso. At the outcrop the lode was 
 about 3ft. broad, but 12 to 30 feet below, it widened out and contained 
 pockets with dimensions of 30 feet by 100 feet. The ores are 
 erubescite, copper pyrites. 
 
 In Cuba and in Newfoundland, rich deposits of copper occur in 
 serpentines. 
 
 In Cornwall, granites and slates containing 8 to 9 Ibs. of tin stuff 
 to the ton of rock yield a good profit. Sometimes 2 Ibs. of tin stuff has 
 been sufficient. A man can break down l% to 2 tons of hard rock 
 per day and 7 to 8 tons of soft killas. 
 
35 
 3. Imbedded in Stratified or Mefamorpliic Rocks. 
 
 At the Rammelsberg in the Hartz there is an ore bed which dips 
 downwards and then forks like an inverted Y. The rock is clay slate. 
 It has been described as a stockwork, a segregation, and as a bed. At 
 one point its dimensions were 1,900 by 150 feet. Fifteen different 
 metals are found, but the chief are galena, copper ore and zinc. It 
 has been worked since A.D. 1,000. 
 
 In Andalusia, S. Spain, there are amygdaloidal masses of galena in 
 metamorphic silurian limestones. 
 
 In the metamorphic rocks following the band of eruptive rocks 
 of the Banat, there are many irregular deposits. 
 
 At Fahlun, Sweden, there is an enormous irregular deposit of 
 copper pyrites (3 to 4/ of Cu.) in metamorphic chloritic rocks. 
 
 4. Imbedded in Limestone. 
 
 The irregular deposits in limestone are chiefly those of lead, zinc 
 and iron. In Derbyshire there are pipe and flat veins of galena 
 following the bedding of the limestone, while small veins called skrins 
 fill the joints. The deposits in Cumberland are very similar to those 
 in Derbyshire. 
 
 In Flintshire at the Fawnog mine, galena and carbonate of lead 
 form an irregular bed-like deposit between limestone and sandstone. 
 
 In Wisconsin, in cambro-silurian limestone, pockets and flat veins 
 of lead occur. 
 
 The silver lead deposits in the dolomitic limestone of Leadville, 
 were probably formed by the gradual displacement of the limestone 
 and were not deposited in pre-existing cavities. 
 
 In Belgium (La Nouvelle Montagne near Verviers and near Air 
 la Chapelle) carbonate of zinc and galena occur in beds and pockets in 
 limestone. In quartz slate, zinc carbonate and hematite are found. 
 
 In the Forest of Dean at the base of the Millstone grit and at the 
 top of the carboniferous limestone, in fissures, in veins and in irregular 
 deposits called chums, some of which measure 14 by 300 yards, hematite 
 is found. 
 
 In Cumberland, in cavities in carboniferous limestone beneath 
 millstone grits and boulder clay, large irregular deposits of earthy and 
 crystallized hematite occurs, sometimes o feet thick (see p. 28). 
 
 " 
 
MINING OPERATIONS. 
 
 BORING. 
 
 Objects of Bore Holes. Bore holes which are usually from 3 
 to IO inches in diameter are sunk for the following purposes : 
 
 1. Testing the character of superficial deposits. 
 
 2. Exploring and testing mineral deposits. 
 
 3. Precautional purposes (10 or 15 feet in advance in soft ground; 
 2 or 3 feet in advance in hard ground). 
 
 4. Ventilation. 
 
 5. Obtaining water, brine and mineral oil. 
 
 One of the most complete treatises on Boring, is Tecklenburg's 
 " Handbuch der Tiefbohrkunde." 
 
 Methods of Boringr. 
 
 [Ordinary method of chipping and removing 
 With rods< 
 
 {Ordinary method of chipping and 
 debris. 
 Japanese method of plunging and not 
 debris. 
 
 removing 
 
 Percussion boring. ^ f Chinese and other methods with a spring 
 
 \ pole. 
 [With rope^Ordinary method in American oil districts. 
 
 | Special methods of Mather and Platt and 
 L others 
 
 T, , f Boring with augers in soft materials. 
 
 Rotary boring. | Diam Snd rock drill. 
 
 Hydraulic boring. Applied to rotatory and percussion boring. 
 
 Examples of Bore Holes. 
 
 Sperenberg. 15111. -i2in. 4194^. rock salt 
 
 Mondorff. 2400 brine 
 
 Crenelle. -[ *g 34 ," 1798 water 864000 gals 
 
 Passy. ^857" * ft ' 4 ' n> I923 54ft> 5582000 
 
 Kissingen. 1878^ 48^:.^^-^-. brine 
 
Chicago. 
 
 Louisville. 
 
 Charlestown. 
 Newsalwerk. 
 
 1848 
 
 DIAMETER. 
 
 SHI. 
 
 3 in. 
 
 
 ft. 7111. 
 
 DEPTH. 
 
 I,700\ 
 1,000 j 
 
 2,086 
 
 1,250 
 
 2,288 
 
 HEIGHT 
 SPOUTED UP. 
 
 10ft. 
 
 800,000 gals: 
 
 800,000 ,, 
 16,700 ,, 
 
 Creusot. -3,017 coal 
 
 Place Hebert Paris. 3ft. 6in. 2,359 water 
 
 Schladebach. iiin-i.aain, 5,732 
 
 Operation of Boring. Choice of place depends on geological 
 considerations, character of the ground, presence or absence of water, 
 nearness of roads, &c. 
 
 First sink a staple or pit 5 or 6 feet in diameter, if possible down 
 to the solid rock. Dig a hole and place in it the guide tube (of wood 
 or iron), one foot of which may project above the ground. 
 
 The amount of turn given to the boring rods between each blow 
 is from one-eighth to one-sixth of a revolution. The length of the 
 stroke will vary with the hardness of the rock and weight of rods; in 
 clay about 6 inches, in limestone about 24 inches. Ponson gives as 
 limits, .15 .6 m. which are practically the same. 
 
 Rate of Progress. In soft alluvium the first 30 or 50 feet 
 may be easily bored in one day. 
 
 The number of strokes is generally about 18 or 20 per minute. 
 
 In soft rock a chisel may penetrate 6 inches without resharpening, 
 but not more than 2 inches in very hard rocks. 
 
 A sludger will descend 1000 ft. in 3^ minutes. Pumping requires 
 4 or 5 mitutes and it may then be raised by a windlass in 12 or 15, 
 minutes. 
 
 Rates of progress in different rocks in II hours: (Andre}. 
 
 Progress. 
 
 1. Tertiary and Cretaceous strata to a depth of 
 
 2. Cretaceous strata, without flints. 
 
 3. ,, ,, with flints, 
 
 4. New red sandstone 
 
 5. New red sandstone 
 
 6. Permian strata 
 
 7. Coal measures 
 
 8. Coal measures 
 
 General average 
 
 a de{ 
 
 )th o 
 
 f TOO yards i f 
 250 ,, 2 
 250 ,, i 
 
 t. 8 it 
 
 i 
 4 
 
 
 
 500 ,, i 
 250 ,, 2 
 
 2OJ ,, 2 , 
 
 400 ,, i 
 
 5 
 o 
 
39 
 
 Pass rapidly through weak ground, which ought to be quickly 
 lined. During the operation of boring in soft ground, clay dropped 
 into the bore hole gives strength to the sides. 
 
 Diameter of Bore Holes. 
 
 DEPTH. DIAM. OF HOLE. 
 
 300-403 ft. 6 in. 
 
 1,0:0-2,000 ft. 8 in. 12 in. 
 
 Artesian wells. 16 in. 2 ft. 6 in. 
 
 If the ground is difficult, the diameter should be greater than if the 
 ground is easy. Up to 600 or 700 feet boring may be done by 6 or 7 
 men. For greater depths a small engine 6 16 H. P. will be required. 
 
 Rods. Iron rods may be square, octagonal or circular in section. 
 Their length is usually 12-15 ^ eet > some times 25 feet. With screw- 
 joints, the female socket is deeper than the male plug. In passing, 
 rods down a bore hole the socket in the lower end goes downward. 
 Collars ought not to touch. Iron rods one inch square in section weigh, 
 lo Ibs. per yard in air, but 8.7 Ibs. per yard in water. S.G. of wrought 
 iron = 7. 7. 
 
 For a 3^-4in. hole, lin. square rods may be used to a depth of 
 90-100 fathoms with rotatory boring; lin. square rods to a depth of 
 50 fathoms with percussive boring ; j^-^in. square rods to IOO 
 fathoms, if a free falling cutter is used. 
 
 I inch square rods may be 12 feet in length. 
 
 1/2 18 
 Lengthening rods are multiples of the lengthening screw. 
 
 I inch square rods have screws \%" in diameter, 2^# long, 
 7 threads to an inch. 
 
 Wooden rods are made of straight pine 20-35 ft- l n with a 
 square section and not less than 2j^ inches in the side. 
 
 At Schoningen (2013 feet), Rods 2^5" diam., 4C/ 6" long, 3^ Ibs. 
 per foot in weight. Lowest 22&y 2 ft. of rods were of wood and 
 weighed 902 Ibs. in air (786 Ibs. in water.) X^^-t^F ^J?r> 
 
 rsr. 
 
40 
 
 The remaining 1,784^ ft. of rods weighed 7,007 Ibs. in air (2,047 
 Ibs. in water.) 
 
 The latter when of iron weighed 8,676 Ibs. in air (7,042 Ibs. in 
 water.) 
 
 When of wood the weight to be raised was 2,833 M )S - or r -35 I DS -~ 
 per foot and was raised in \ l / 2 hour. When of iron, they weighed 
 7828 Ibs. or 3.9 Ibs. per foot, and were raised in 3-4 hours, so that the 
 saving in time by using wood was 56 per cent. 
 
 To obviate the severity of shock to a tool in a deep bore hole, 
 hollow rods may be used. 
 
 Sliding- Joints and Free Falling- Cutters. In 1834 CEyn- 
 hausen invented the sliding joint. Kind's free-falling apparatus acts 
 by the resistance of the water in the bore hole. The action of 
 Degousee's cutter depends upon a portion of the apparatus resting at 
 the bottom of the hole. Fabian's free falling cutter depends upon a 
 twist being given to the rods. Dru's contrivance acts by a sudden 
 shock being given to the rods. 
 
 Chisels or Bits. The form, the sharpness and the temper of 
 the edges of cutting tools are modified according to the rock to be cut. 
 The various forms of chisels are known as flat or straight chisels for 
 ordinary rock, the diamond pointed or V drill for hard rocks, the T 
 chisel for gravel. X + Z and S chisels (cross and club borers) are 
 difficult to sharpen. They may be used in inclined fissile strata. For 
 earthy materials augers are employed. An annular arrangement of 
 cutters is used for core boring. 
 
 Sludgers are usually from 3 to 10 feet in length. The valves 
 are flat or balls. These may be weighted to suit, the consistency of 
 the sludge which is to be entered. The rope to raise the sludger is 
 % to i in. in diameter. 
 
 Accessory Tools. Verifying tools, clearing tools, regulating 
 tools, guides to prevent vibration, stirrup with screw or chain for 
 rotating and gradually lengthening the rods, a tiller or brace head, 
 lifting dogs, tigers, nipping forks, dogs &c. A parachute may be em- 
 ployed to prevent a sudden fall of the rods. 
 
 Extracting* Tools. For small articles a spider box, Kind's 
 catch clutch or a ball of clay kneaded with oil and hemp placed in 
 
41 
 
 the end of a sludger or screw bell may be sufficient ; otherwise-they 
 may be slowly chipped to pieces or dissolved by acid. Broken rods 
 may be extracted by a crow's foot, screw bells, box bells, &c. 
 
 Rocking: I-ever and Trestle. The length of the lever may 
 be 10 20 feet. Its leverage which is variable, is generally about I : 4 
 or 1:5. The lever may be worked by a crank or cam with steam 
 power. The lever may be supplied with a balance weight and if a 
 sliding joint is used an elastic stop will be required. To work the 
 rods, a spring pole or a windlass and rope may also be employed. 
 
 Bore Frames and Towers. These vary from 30 to 80 feet in 
 height. Windlasses provided with brakes are required. If the hole 
 is to be deep let there be two pulleys to work the rods. Diameter of 
 the windlass about 20 inches. 
 
 Guide Tubes. These are of iron or wood with shutters. In 
 Japan the guide tube is attached to the bore tower above the hole. 
 In Europe it is placed in the ground in the upper part of the hole. 
 
 Tubing-. Square and made of narrow planks ; cylindrical of 
 wood, or iron (cast or wrought) with screw, socket, lap or muff 
 joints. If in corrosive water, of brass or copper. Iron tubes which 
 have been tinned maybe used for water supply. The lower end of 
 the tube is sharpened. Tubes are put down by percussion or pressure. 
 Tubes may be passed through running sand by forcing water through 
 a series of holes in the end of a pipe passed down the inside of the 
 lining which latter is under pressure. Tools may be used to enlarge 
 a hole below a set of tubes. To raise a set of tubes, use a screw plug, 
 Kind's plug or Alberti's tube drawer. Tools may be employed to cut 
 tubes and thus draw them up in sections. Mandrels are required to 
 straighten tubes. Clay may be used as a temporary lining. 
 
 A Set of Boring: Tools for 5OO Feet. 
 
 i Pair tillers with spare screws. j Flat Chisel, each 4%, 5%, 6% in. 
 
 50 Ten feet lengths i ^ in. boring rods. iV 
 
 Short Swivel rod. i T 
 
 Gin wheel and irame. i S ,, 
 
 Snatch block. i Shoe nose shell, each 4, 5, 6 
 
 Spring hook and 30 ft. rope. i Auger. 
 
 Auger board. i Auger cleaner. i Worm Auger. i Crows Foot, 
 
 ron work for shear legs, i Windlass. i Bell Box. i Spiral Worm. 
 
 Clay Auger, each 4 i/, 5 #, 6# in. 2 Lifting Dogs. 2 Hand Dcgs. 
 
42 
 
 IMfficultie* and Accidents. Rods become brittle by blows 
 and consequent vibration. Rods, chisels, bolts, &c., by carelessness 
 may fall into the hole. By want of rotation projections may be left 
 and the hole looses its circular form. Deviation of the hole from the 
 vertical. Falling in of the sides of the hole. Jamming of the 
 apparatus. By change of strata or fissures, the hole may become 
 narrower. Breaking and falling in of sludging apparatus. 
 
 Japanese Method of Boring. This is chiefly applicable to- 
 alluvial deposits, which from the surface are penetrated at the rate 
 of 50 or 60 feet per day. The tools consist of solid round iron rods 
 connected by fish joints and terminating with a pear shaped plunger 
 for soft ground and an obtuse pyramidal point for hard ground. By a 
 rocking lever terminating with a Jizai kagi or kettle catch (peculiar to 
 Japan) the rods are pumped up 6 inches at a time to a height of from 2 
 to 15 feet when they are allowed to fall. Material is but seldom taken 
 out of the hole. During the operation the hole is kept filled with water 
 charged with clay. Subsequently it may be lined with a bamboo 
 pipe. The method is cheap and rapid. 
 
 Rope Boring* (American System). 
 
 The disadvantages according to Lottner are : 
 
 1. The impossibility of employing ordinary chisels. 
 
 2. The uncertainty in the rise and fall of the tool. 
 
 3. The necessity of having rigid rods in case of hindrance and 
 breakage. 
 
 4. The impossibility of rotating the tool in soft clayey ground. 
 
 5. The small effect compared with that obtained by the free 
 falling apparatus. 
 
 6. The impossibility of knowing the effect of the borer by hold- 
 
 ing the rope. 
 
 Notwithstanding the above objections, from the writer's own. 
 observations, the American system of Rope Boring is probably one of 
 the most practical in existence. In Pennsylvania several thousand 
 wells each from 1,000 to 1,500 feet in depth are bored through shales 
 and limestones every year. At starting, a hole is 8 in. in diameter but 
 
43 
 
 when lined is about 5^ in. The boring bar is 70 ft. in length 
 with a sliding joint near the middle. A small engine works the walk- 
 ing beam at about 60 strokes per minute, subsequently it raises the tool 
 and works the sludger. Two men carry on the operation. The total 
 cost of a 1,500 ft. hole as given by Prof. A. Lupton is as follows : 
 
 Dollars. 
 Carpenters' Rig (Derrick or pulley frame with housing for borers, 
 
 boiler. c 350 
 
 Belt, bull rope, engine telegraph, water and steam pipes, and boiler 
 
 fittings ico 
 
 Boiler 20 h. p. Engine 15 h. p. on ground 750 
 
 Contract for drilling Contractor to furnish fuel, tools, cable, sand 
 
 pump, line, &c., at 65 cents a loot ior 15,000 ft 975 
 
 Casing, say 300 it. at 80 cents 240 
 
 Tubing, say i, 600 ft. at 20 cents 320 
 
 Torpedo (almost invariably used before tubing) 100 
 
 Packer 25 
 
 Working barrel 8 
 
 Casing head , 3 
 
 Tees and elbows 5 
 
 One 25 barrel tank 25 
 
 One 250 barrel tank no 
 
 Tank house 25 
 
 Expenses of tubing and packing well 20 
 
 Expenses of hauling material 50 
 
 Total 650 = $3,106 
 
 Extra for pumping tackle 100 
 
 Apart from plant the cost of a 1,500 ft. hole is only 750 or ^"200, 
 and this where wages are from los. to i6s. per day. 
 
 Mather and Platfs Rope-boring: Apparatus. 
 
 The chief features of this apparatus are : 
 
 1. The contrivance for rotating the rod. 
 
 2. The arrangement for giving the blow. 
 
 3. The details of the sludging apparatus. 
 
 Many holes have been put down in various rocks 300 to 1,200 feet 
 deep at average rates of i' 6# to 4' per day. 
 
 Diamond Boring*. The average rate in stratified rocks appears 
 to be from 5 ft. to 6 ft. per day, and this for holesfj-Qm 1,000 to 1,300 
 feet deep and 18 inches in diameter. 
 
44 
 
 In diamond boring a number of black diamonds are fixed on 
 the end of a steel cylinder attached to tubular rods. By suitable 
 machinery on the surface the rods are rotated, water being pumped 
 down the rods to wash up the debris. The chief advantages are 
 rapidity and obtaining solid cores of the rocks penetrated. 
 
 Diamond Rock Drills are largely used for prospecting in many 
 mining districts as for example at Cletor moor in Cumberland 
 (Haematite), Australia (Gold), Japan (Coal), Pennsylvania (Oil), Michi- 
 gan (copperj. 
 
 The diamond drill will cut through the hardest rock. The follow- 
 ing table is given by Andre as the ordinary rate of progress : 
 
 Granite and hardest limestone 2 to 3 inches per minute. 
 Quartz I inch per minute. 
 
 Sandstone,, 4 inches per minute. 
 
 Difficulties are met with in rocks which are irregular in their 
 character like conglomerates, 
 
 Boring- Journal {Andre]. 
 Boring executed at in the County of 
 
 Began 
 
 189-. 
 
 On the Estate of 
 Completed 
 
 189-. 
 
 
 
 c 
 
 V 
 
 
 
 
 S 
 
 u- 
 
 >, JC 
 
 S 
 
 i 
 
 
 
 
 
 
 
 g 
 
 P. 
 
 2 
 
 
 zr c M 
 
 rt 
 
 
 
 
 
 rt 
 ft 
 
 ijLg 
 
 o. of specir 
 in case. 
 
 Thickness 
 
 -1 
 
 P. 3 
 fi 
 
 'o 
 
 JU 
 
 "bJD 
 
 C 
 
 ameter of I 
 hole. 
 
 c > 
 
 
 
 It 
 
 tjjU 
 
 ime actua 
 
 occupied i 
 ssing throu 
 
 lantity of w 
 met with. 
 
 rganic rems 
 
 Remarks 
 
 
 
 fc 
 
 
 
 
 p 
 
 Q " 
 
 P. 
 
 g 
 
 
 
 Cost of Boring:. 
 
 The cost of the diamond boring, exclusive of the cost of lining: 
 
 8s. a foot for the first 100 feet. 
 i6s. second 100 feet. 
 24*. third 100 feet. 
 
45 
 
 so on in arithmetical progression, increasing 6s* at each IOO feet. 
 Above 1,500 feet in depth, special rates are charged. 
 
 The formula for finding the cost of a diamond bore hole : 
 
 s = .5 d (o. 44-0. 004 cT) 
 s = sum in pounds sought. 
 d= depth in feet. 
 
 Andre gives the following formula to calculate the cost of ordinary 
 boring, in pounds sterling. 
 
 35. 6 d. a yard for the first JO yards. 
 ^s. o d. second 
 los. 6 d. third 
 
 From the above it is seen that the increase is in arithmetical 
 progression. 
 
 Generally, if* 
 
 s = sum sought in pounds sterling. 
 d = depth of the boring in yards. 
 s = o. 5 d. (o. 175 + o. 0.175 d). 
 
 These examples of the cost of boring are only given to illustrate 
 the method of calculation. From the writers own experiences with 
 bore holes in Japan they cost rather more than they do in Pennsylva- 
 nia, notwithstanding the fact that wages in Japan are only about 1/15 
 of what they are in the United States (See p. 42). 
 
 To the above, the cost of sinking the staple must be added. 
 When extra hard rocks are met with, the cost will rise at an extra 
 rate per fathom, or by day's wages. It may be stipulated that the 
 employer may abandon a boring if conditions arise necessitating a 
 change in the contract. Further it may be arranged for the boring 
 master to receive an extra sum for every week that the boring has 
 been completed before the stipulated time, which sum may be that 
 paid for the last week of work or a certain proportion of that sum. If 
 the stipulated time is exceeded, a reduction say of 25 per cent, may be 
 made on the sum due to the boring master. For neglect or unneces- 
 sary delay the employer may break the contract. 
 
46 
 
 Cost of Boring: Tools (Bmver Scott and Western}. 
 
 In the following table the depths are given in feet, and the price 
 for tools in pounds sterling. Windlass, with one each of different 
 dimentions of Augers, Shells and Chisels are included. Shear legs 
 not included: 
 
 Depth 30 
 
 50 100 200 
 
 300 
 
 500 
 230 
 
 Price 
 
 20 
 
 35 
 
 60 
 
 85 
 
 130 
 
 Compare these prices with prices on p. 42. 
 
 Precautions. Keep the bole hole plumb, otherwise its devia- 
 tion from the vertical may increase. 
 
 Keep the bore hole circular by regular rotation. Keep a careful 
 record of all that is mentioned in the headings of the boring journal. 
 
 Examine the rods for flaws. Keep them straight and let them be 
 numbered. Test the temper of tools. See that their edges are sym- 
 metrical. 
 
 From time to time obtain specimens, either as chips or cores from 
 the bore hole. 
 
 Do not allow a tool to lie at the bottom of a hole, but during the 
 time when work is not going on raise it a few feet. 
 
 In attempting to withdraw rods which have been jammed, use 
 steady pressure and light blows. Sudden shocks may result in 
 fracture. 
 
 If a bed is reached at a depth much greater or much less than was 
 expected, it must be remembered that the difference may be due 
 either to one large fault, to many smaller ones, or to a change in dip. 
 
 Precautionary Bore Holes. There are holes bored hori- 
 zontally in advance of levels approaching old wastes which may be 
 filled with water. One hole is kept in advance of the level, while 
 others may be driven obliquely right and left. The length of these 
 holes which are l% to \ l / 2 " diameter depends on the depth from the 
 surface and the hardness the rocks : 
 
 Depth from surface in fms 5 10 15 20 25 30 50 75 100 
 
 Length of hole in advance in yds 6 7 8 9 10 n 15 20 ^(Collins). 
 
47 
 
 To determine Hie force wlifcli may be applied to the 
 Tillers of Boring Rods (I lumber). 
 
 The moment of resistance M to torsion of a rod or bar is given in 
 'the following formulae : 
 
 fit* 
 
 For a solid circular section M = 
 
 For a hollow circular section M = , * , - 
 
 S- 1 ^! 
 
 For a solid squares section M = .28/h 3 
 
 AVhere d\ and d* are the external and internal diameters of the 
 rods, a is the side of the square, in inches and /"is the resistance of the 
 material to shearing in pounds per square inch of section. The values 
 for/" are as follows : 
 
 Wrought Irnn 50,000 
 
 Cast iron (average) 27.000 
 
 Oak 2,300 
 
 Fir 500 to 1,500 
 
 Ash and elm i,4 
 
 The force acting on the rods, is that which is applied by the men 
 at the end of the tillers. 
 
 It may be expressed M=Pl 
 
 where /= length of lever in inches 
 and P= force applied to lever in Ibs. 
 
 This force ought not to exceed one quarter of that calculated by 
 the above formulae. 
 
 The first of the above formulae finds more practical application in 
 determining the diameter of shafts, drums, pulleys, c. 
 
 Thickness of a Bed. Having obtained the dip of a bed 
 
 and its apparent thickness a, its true thickness may be calculated as 
 follows. 
 
 True thickness = a. cos. 0. 
 
 J>ip of bed. A bed has been reached at three points from a hori- 
 zontal-plane at depths of x, y and z feet respectively; to find its dip. 
 
4 8 
 
 1st Solution. Plot the points x, y and z in plan ; join them. Draw 
 the plane containing these lines. The inclination of this plane 
 taken at right angles to its horizontal trace is the dip required. 
 
 2nd Solution. If / be the true dip of a bed, z'the apparent dip in 
 a direction 6 away from the direction of true dip then, 
 
 Therefore if we plot x y equal to the tangent of its inclination to- 
 the horizontal, and x z equal to the tangent of its inclination to the 
 horizontal, each in its proper direction, and from y and z erect perpen- 
 diculars to meet in o, then x o shews the direction of the true clip and 
 measures its tangent. 
 
 3rd Solution (Merivale). Let A B fbe three bore holes. 
 
 6"= angle of dip of bed. 
 
 F=angle between the strike of the bed and A B. 
 
 a distance A B 
 rt x =distance A C 
 W= angle in a horizontal plain between A B and A C. 
 
 d= difference in depth of A and B 
 
 fj/ 4 C 
 
 " 
 
 Tan S= : 
 asm V 
 
 -^sin W 
 Tan F= 
 
 da' ,,, 
 
 a _ cos W 
 
 d f 
 
 The Quantity of "Water. The quantity of water flowing from 
 bore hole made in an old waste may be calculated as follows : 
 
 Let H= the head of water in feet. 
 
 ;/=the diameter of the bore hole in inches. 
 /= length of the bore hole in feet. 
 G= number of gallons delivered per hour 
 
49 
 
 Then. 
 
 It must be remembered that the head decreases, and therefore 
 to determine the time taken to empty a given reservoir it is better to 
 calculate the times taken to empty so many successive horizontal 
 sections of the reservoir. A more practical method is to dam up the 
 drift and allow the water to escape through a notch of known dimen- 
 sions (See JDnwiage}. 
 
 Survey of Bore Holes. The most satisfactory instrument to 
 determine the angle of deviation of a bore hole from the perpendicular 
 and the direction of deviation is Macgregor's clinograph. This consists 
 of a small pendulum of glass floating by means of a hollow glass float 
 inside a bulb, and a magnetic needle similarly floating in a lower bulb. 
 The fluid in the bulbs is a hot solution of gelatine These bulbs are 
 fitted in a protecting tube. While the solution is hot they are lowered 
 in the bore and there allowed to cool. On withdrawal from the hole 
 they can be placed at the angle at which they cooled and the inclina- 
 tion of the bore and its asimuth of deviation determined. 
 
BREAKING GROUND. 
 
 VARIETIES OF OROUND. 
 
 1. Rolling, running or watery (quicksands). 
 
 2. Mild, soft, easy (clay, chalk coal). 
 
 3. Jointy, scaley (vein stuff and fissured rocks). 
 
 4. Fast, hard (like the above but without joints). (In these rocks 
 
 explosives are required). 
 
 5. Unusually hard materials like quartz, iron pyrites. 
 
 6. Soluble materials (rock salt). 
 
 Weights and Bulk of Material. The weight of a cubic 
 foot of any material in Ibs. is its specific gravity X 62.425 or the 
 weight of a cubic foot of water. One ton of quartz when solid occupies 
 about 13 cubic feet, but when broken about 20 cubic feet. Rocks 
 when solid as compared to the same when broken usually increase in 
 volume in the ratio of I : 1.5 or I : 1.8 the increase being dependent on 
 the size and form of the fragments. A knowledge of these facts may 
 be of use in calculating the dimensions of a tub to carry a given 
 weight of coal, in calculating the quantity of cement that will be 
 absorbed in the interstices of broken rock when making a given 
 volume of concrete, &c. 
 
 "With fine materials there may be a decrease in bulk by the 
 addition of water. Sand may in this way loose 20 per cent of its 
 volume, therefore a cubic foot of wet sand ought to weigh more than 
 a cubic foot of dry sand. The writer however finds that this is only 
 true when the sand is weighed in the box in which it was moistened. 
 Jf wet sand is loaded into a vessel it packs with difficulty and therefore 
 in practice it may be found that a load of wet sand is lighter than a 
 load of dry sand. 
 
 MIXING TOOLS 
 
 (See Manual of Alining Tools bv W. Alargaiis}. 
 
 Shovels, Spades. Shovels are flat or dished, with a centra? 
 ridge or crease and straps. For loose materials they are large and 
 
52 
 
 square, otherwise they are pointed. Width of plate or blade from 8 to 
 16 inches. It is made of steel, or iron with a steel edge and it meets 
 the helve which is long (4 or 5 feet) or short (30 inches) at an angle 
 of 140 to 1 60. 
 
 Scrapers are used with a box, tray or basket. 
 
 . Iiks. tlaf looKs. Haiidrels. Slitters or Huek**. 
 
 The head of wrought iron with steel tips. Cast steel heads are liable 
 to fracture. 
 
 A pick in its action, is a combination of a hammer, wedge and 
 lever. Points are square or chisel edges. 
 
 The heads may be straight, sweeped, elbowed or anchored. 
 
 For overhand work, square work and holing, light straight picks 
 are used. For underhand surface work, heavy picks with a little 
 sweep are employed. Weight of heads from 2 to 8 Ibs. Helves 24 to 
 33 inches. 
 
 Poll Picks used by metal miners, have one stem of 12 inches and 
 a stump of 3 inches to form the poll. Weight 4 Ibs. To avoid wincing 
 the eye should be long and oval at ends. Rectangular and round eyes 
 are sometimes used. Eyes are punched across the laminee of the bar. 
 To resist wincing, corbel bits or straps may be employed. 
 
 Patent picks have movable tips or heads. They are only servi- 
 ceable for light work 
 
 Varieties of Picks. Picks for holing, benching kirving or 
 undergoing. Bottom picks. Striping mandrels or picks for pulling 
 down. Driving, stone picks or twibills &c. 
 
 A smith and boy sharpen 70 to 100 tips of colliers picks per hour, 
 and perhaps 40 to 60 tips of metal miners picks. 
 
 Hammers and Sledges. Large hammers used with two 
 hands are called sledges. 
 
 For single handed boring, hammers of 2^ to 4 Ibs. are used. For 
 double handed boring the sledges weigh 4 to 10 Ibs. usually 5 to 7 &c. 
 
 The striking face or pane which is slightly convex, is usually of 
 steel. 
 
53 
 
 Varieties. Bully pattern, block, bloat, plug, dolly which is 
 circular or many sided. Lump sledges, cobbing hammers, bucking 
 irons, spalling hammers. 
 
 A smith and two strikers can forge eight 7 Ib. sledges per day. 
 A smith and striker can resteel 12 sledges per day. 
 
 Cast steel sledges are said to give a smarter blow. 
 
 Borers, Drills, Augers. A Jumper is a bar of iron with a 
 steel bit at each extremity and a heavy bead in the center, dividing 
 the tool into two stocks. It has a lively action and is good for vertical 
 holes. 
 
 Steel borers are more effective than those of iron, a short borer or 
 an old borer is more effective than one which is long or new. 
 
 The edges are straight or curved. They should not be " nipped, ' r 
 " oddcornered " or partially " backward." 
 
 For good borers it is necessary to have, good steel, good 
 shape, good tempering when good fuel is required, good striking and 
 turning. 
 
 Diameter of hole or width of bits in inches, i i 1 /^ 1% 1% i% 2 2^ 2^ 
 Diameter of stock in inches. ^ % Ji i i> *% i^i *% 
 
 Angle of cutting edge from 60 to 100. 
 
 Borers are sometimes sharpened with a swage. The colour for 
 tempering varies from straw to purple, the former for hard ground and 
 the latter for soft. 
 
 A smith and striker sharpen 45 single borers per bour. Sometimes 
 borers wear away at the striking end more rapidly than at the bit end. 
 
 Varieties. Swallow tail bit, club bit, nicker bit, S bits, X bits, 
 Z bits. These latter are difficult to sharpen. 
 
 Revolving bits and augers are used in benching down coal, also 
 in earth and other soft materials. 
 
 Gads which are pointed and wedges with chisel edges are from 
 3in to 2ft in length. 
 
 Helve**, Handles, Shafts, Sticks. Helves require to be 
 light and elastic. 
 
54 
 
 Ash and hickory make good helves. 
 
 For picks and sledges, the cross section is oval. Round cross 
 section for shovels. 
 
 Helves are ?plit out of logs, being afterwards hewn and dressed, 
 so that the long axis of the feather radiates from the log. 
 
 Sawn helves are apt to break. The average life of a good 
 collier's helve is 4 months. In metal mines a helve may only last 2 
 weeks. 
 
 BLASTING. 
 
 Miscellaneous Tools used in Blasting 1 . Scrapers to clear 
 Coring dust, meal or sludge out of a bore hole. Drag twist, loop drag, 
 swabstick or sludgers, for cleaning a hole. Scoops and spoons for 
 charging powder. Clay iron, shooting needle or nail, pricker. Tamp- 
 ing bar which is tipped with copper or made of bronze. Shooting 
 needles and prickers ought also to be made of bronze. Tamping case. 
 
 Tamping' or Stemming. Above the charge place a small 
 quantity of some soft material, after which fill up with loose rubbish 
 which ought not to be quartzoze. 
 
 Hard clay, broken brick, or shale are good materials for tamping. 
 
 Dry sand, plaster of paris, a plug o^ wood so cut that the 
 effect of an explosion is to tighten it in its position, have been 
 employed. Humble has invented an India rubber tamping but it is 
 costly. Johnson's plug is of phosphor-bronze. 
 
 A tamping made of coal dust may if blown out into a dangerous 
 atmosphere result in an explosion. Blown out shots in certain coal 
 mines are always a source of danger the flame extending when gas 
 is present as much as 15 yards. 
 
 Fuses. A rush, reed, paper or quill rilled with powder and 
 terminated with a piece of touch paper may be employed. The 
 ordinary material is Bickford's patent safety fuse. This is made of 
 tape or yarn, with a specialy prepared slow burning powder as a core. 
 Guttapercha and metallic covered fuse is employed for subaqueous 
 explosions. 
 
55 
 
 Some varieties of fuse like white fuse, give but little or no smoke 
 and flame, other varieties are impervious to damp. (Red fuse, sump 
 fuse, tape fuse). Specially covered fuses are required in hot countries. 
 A patent Quarry fuse conveys the fire to the bottom of a charge. 
 
 By using these fuses a better effect is obtained, there being no hole 
 left in the tamping, time is saved, the danger of a pricker is avoided 
 and there is little smoke or smell. 
 
 Electrical Fuses. Quantity fuses explode by ignition of a 
 material like meal powder round a platinum wire which is heated. 
 The platinum wire, which has a high resistance and a low specific 
 heat, is heated by the passage of a current from a battery. The 
 leading wires which may be of copper do not require perfect insulation. 
 
 Tension fuses explode by the ignition of a chemical compound 
 (chlorate of potash, subsulphide and subphosphide of copper) caused by 
 the passage of a spark. The spark may be produced by a magneto- 
 electric machine as Wheatstone's, Breguet's, Saxton's, Clarke's, an 
 electro-dynamic machine like Siemen's, Ladd's, Farmer's, Gramme's, a 
 frictional machine-like Bornhardt's, or a secondary current from an 
 induction coil. The former machines are more convenient than the 
 latter. Perfect insulation is needed on the line. The resistance of 
 the line has little effect on the current. 
 
 With quantity fuses, the line must have a low resistance or many 
 fuses can not be exploded simultaneously. The state of the line may 
 at any time be tested by a feeble current. Small dry batteries 
 may be used. 
 
 With electric fuses several charges may be ignited simultaneously. 
 The same result may be obtained by a patent fuse which flashes from 
 the point where it is ignited down to where it enters the charge. 
 Several of the flashing fuses are united, and at the point of junction 
 -they are simultaneously fired with a piece of ordinary fuse. 
 
 Firing Explosive Substances. By the application of heat 
 dynamite simply burns, but by the explosion of a small quantity of 
 substance like fulminate of mercury in the dynamite, the latter ex- 
 plodes with violence. 
 
 Detonators are copper caps containing fulminate of mercury. 
 They are placed on the end of a fuse. Bj^^V {explosion of the 
 
 ff^&- Of ^/"^Pv * 
 , UNIVERSITY 
 
detonator the explosion of the substance with which it is in contact is 
 accelerated. Different substances require different quantities or kinds 
 of material to produce detonation. With gunpowder detonation may 
 be a mechanical action, while with chemical compounds like nitrogly- 
 cerine it may be the result of molecular vibration. 
 
 For complete detonation a charge ought to be confined. If loose, 
 only part of it may explode. 
 
 The following table by Messrs. Roux and Sarrau shews the 
 advantage of detonation. 
 
 Substance. 
 
 Simple 
 Explosion. 
 
 Detona- 
 tion. 
 
 Relative 
 Weight 
 of Gases. 
 
 Heat disengaged 
 by ilb. 
 
 Simple 
 Explosion. 
 
 Detona- 
 tion. 
 
 Fulminate of Mercury. 
 
 I.OO 
 
 4.80 
 3.00 
 2.04 
 1.84 
 
 9.28 
 4-34 
 10.13 
 6.46 
 5-5 
 5-30 
 
 0.414 
 
 .800 
 .850 
 .892 
 .740 
 
 units. 
 
 1316 
 397 
 1902 
 1491 
 1417 
 
 units. 
 
 1354 
 1318 
 3200 
 1909 
 1563 
 
 N itroglycerine 
 
 Picric Acid 
 Picrate of Potash 
 
 Two or more charges fired simultaneously give a better effect than 
 if they had been exploded separately. 
 
 For this reason other 'things being equal it is better to remove 
 large masses of material by simultaneously firing a large number of 
 small charges or even by one large charge. 
 
 In 1885 Hell Gate or Flood rock was removed by the simultane- 
 ous explosion of 14,000 cartridges of dynamite and a mixture of 
 nitroglycerine and coaltar oil (rackarock). 
 
 The holes were 9 ft. by 2^ in. The material removed was about 
 275,000 cubic yards. 
 
 In this case 42,331 Ibs. of dynamite acted as a detonator for 240,399 
 bs. of rackarock. 
 
57 
 
 Relative strength of Explosives {Noble}. 
 
 
 Weight for weight by 
 mortar test. 
 
 Bulk for bulk computed 
 from the ist column. 
 
 Gunpowder 
 
 i. co 
 
 1. 00 
 
 Guncotton 
 
 2.84 
 
 2-57 
 
 Dynamite 
 
 2.8Q 
 
 4- 2 3 
 
 Nitroglycerine 
 
 4.00 
 
 5-71 
 
 EXPLOSIVES. 
 
 A rending compound is one where the gas resulting from explosion 
 is developed gradually, as in gunpowder. Here explosion is occa- 
 sioned by combustion. 
 
 In a shattering compound the gas is generated rapidly, as in 
 dynamite. In this case explosion is due to detonation. 
 
 Cundhili gives the following classification of explosives : 
 
 1. Gunpowder ordinarily so called. 
 
 2. Nitrate mixtures other than gunpowder. 
 
 3. Chlorate mixtures. 
 
 4. Nitro-compounds containing nitro-glycerine. Dynamites. 
 
 5. Nitro-compounds not containing nitro-glycerine. Guncotton. 
 
 6. Explosives with picric acid or picrates. These are strictly 
 
 nitro-com pounds. 
 
 7. Explosives of the Sprengel type, in which the principle is the 
 
 admixture of an oxidising with a combustible agent (at the 
 time of or just before being required for use) the constituents 
 of the mixture being themselves non-explosive. 
 
 8. Miscellaneous explosives. 
 
 Gunpowder is a mixture of about 75 / nitre, 15 /o carbon and 
 10 / sulphur. Sometimes nitrate of soda is used. This may be 
 recognized by its rhombohedral crystals. The explosive force of 
 gunpowder may be reduced by mixing it with sawdust, chaff, filings, 
 
5* 
 
 lycopodium, burnt lime &c. Glass powder which may be removed by 
 sifting, renders powder inexplosive. A decrease in the quantity of 
 nitre or an increase in the size of grains makes a slow burning powder 
 suitable for blasting. The sulphur accelerates the combustion. When 
 fired the resulting gases are, nitrogen, carbonic oxide, carbon dioxide* 
 potassium sulphide. The latter is the white smoke. 
 
 All the constituents for powder are specially prepared. They are 
 ground and sifted separately. Next mixed, made into a paste, pressed, 
 granulated and finally sorted. Blasting powder is glazed with graphite 
 which retards ignition. Compressed powder is sometimes used. 
 
 The strength of powder may be tested by the distance to which it 
 projects a ball from a mortar. By the velocity of a projected ball, as 
 observed either directly or as calculated from the deflection of a 
 ballistic pendulum. By tests with a differential Mercury gauge, ordinary 
 blasting powder gives 22,000 Ibs. and sporting grades 40,000 Ibs. per 
 sq. in. Temperature causing explosion 600 F. 
 
 Good powder ought to be regular, hard, clean (not soil the hand 
 or paper) and dry. A small quantity ought to explode on paper 
 without soiling the same. 
 
 Powder containing nitrate of soda readily becomes damp. Good 
 powder gives greater space for tamping than bad powder. 
 
 Schultze's Powder. Consists of nitre and grains of wood-pulp 
 converted into nitro-cellulose. It is said not to be injured by moisture, 
 to be stronger than ordinary powder and that the resultant gases are 
 not injurious. 
 
 Haloxyline is made from wood or vegetable fibre and nitre. It 
 is hygroscopic and not so effective as ordinary powder. 
 
 BTenmeyer's Powder is a slow burning powder with less 
 sulphur and more charcoal than ordinary gunpowder. It may be 
 useful for coal and salt. 
 
 Kiij's Powder is like ordinary powder but with a large 
 proportion of barium nitrate. It burns slowly. 
 
 White Blasting: Powder consists of chlorate and prussiate 
 of potash and cane sugar. There are several varieties. 
 
59 
 
 Xitro-s-l.yoerine. Discovered by Sobrero in 1847. Brought 
 into use by Nobel. 
 
 Tt is liable to explosion by concussion, especially when frozen, 
 (freezes at 4 C.) or in consequence of spontaneous decomposition. 
 
 Its use is forbidden in England, Belgium, Sweden and Austria. 
 
 Nitro-glycerine is formed by the action of nitric acid on glycerine. 
 It is a white colourless liquid with a sweet aromatic taste. S. G. I.S 
 and therefore sinks in water. Three varieties, (mono,-di,-and tri- 
 nitroglycerine) may be produced, the last being the one employed for 
 blasting. Insoluble in water but soluble in alcohol. Solidifies at 45 
 F = (5C)and decomposes at 420 F. With a higher temperature it 
 explodes. At some mines it is prepared on the spot a short time 
 before being used. Its solution in alcohol is inexplosive. The alcohol 
 may be removed by washing. 
 
 If frozen it must be thawed by placing in a vessel of hot water. 
 Its contact with the body is injurious- The gases produced by an 
 explosion have a bad effect on the health of miners. 
 
 When exploded, I vol. of nitroglycerine gives 1,300 vols. of gas, 
 and if this is expanded 10 times by the heat, we get 13,000 vols. of gas. 
 The production of this is very sudden. 
 
 It requires a small bore hole and its effect is great, no tamping 
 required and the presence of water does not prevent its action. 
 
 l>.vimmite consists of nitroglycerine mixed with kieselguhr, a 
 silicious infusorial earth. Coal ash may be used instead of kieselguhr. 
 
 The Rhenish Dynamite Company have the following three 
 varieties : 
 
 Percentage 
 cf Xiti o-glycerine. Kieselguhr. 
 
 IA 75 77 2325 For the hardest rocks and small levels. 
 
 1 70 71 2930 Hard rocks and large levels. 
 
 TT [Soft rocks and assisting No. I A 
 
 11 6o ~ 61 39-4 | removing side cute &c 
 
 When ignited it burns quietly unless it is in a confined space. It 
 is exploded by detonation. A thin layer on stone or iron may be 
 exploded by a sharp blow. When in bulk concussion produces no 
 effect. At 46 F it freezes and can not be easily exploded. It there- 
 fore requires to be thawed (in a watertight can placed^ jn a jvessel of 
 hot water). It is not hurt by water. /^^^ 
 
 - " ^ 
 
6o 
 
 Its use gives economy in labour, in boring and also in tamping, 
 loose sand or water being sufficient. Can be used under water or in 
 watery ground. Does not give smoke. In using Dynamite, use small 
 holes, increase the depth and angle. After a miss fire do not remove 
 a charge unless water tamping has been used. 
 
 In tunnel work the rate of advance will be 3 or 4 times the rate 
 obtained with gunpowder. It is safe to use. The gases developed are 
 not injurious. 
 
 Dynamite may be employed in submarine work, in removing trees, 
 breaking down salamanders, in bore holes to increase the flow of oil or 
 water. 
 
 Its strength as compared with that of other explosives may be 
 determined by exploding a small quantity of the substances to be 
 
 compared (2 to 7 grammes) in cylindrical holes (say 0.08 deep by o.oi 
 diameter) bored in blocks of lead. The volumes of the cavities pro- 
 duced in the lead may be taken as proportional to the strength of the 
 explosives. 
 
 Fair estimates of the relative strength of dynamites and other 
 explosives have been obtained from the diagrams given by seismo- 
 graphs, the charges being fired under similar conditions. 
 
 Other tests are with a Mortar and ball or with a pressure gaugue 
 where the result of an explosion is to compress a cone of lead. 
 
 Brain's Blasting: Powder. Nitro-glycerine, chlorate and 
 nitrate of potash, charcoal, coal, sugar. 
 
 arbonite. Nitro-glycerine, wood meal, potassium nitrate,. 
 organic sulphur compound. Used for fiery mines. 
 
 Oelig-nite. Nitro-glycerine, nitro-cotton, wood meal, potassium 
 nitrate. In appearance like Blasting Gelatine. 
 
 Fiilmatiit. 85 per cent nitro-glycerine and 15 per cent of a 
 chemical mixture in place of kieselguhr. 
 
 Gelatine. 86.4 per cent, nitro-glycerine, 9.6 per cent, soluble 
 gun-cotton, camphor 4 per cent, potassium nitrate. Properties very 
 
6i 
 
 similar to dynamite but more powerful. One variety is not unlike 
 Forcite. It needs strong detonators. 
 
 Lithofracteiir contains nitro-glycerine, kieselguhr, powdered 
 coal and other substances. A black plastic material. Properties 
 similar to Dynamite. 
 
 I>iia1ine. Nitro-glycerine mixed with sawdust which has been 
 treated chemically. Many of its properties like dynamite. When 
 confined it may however be exploded by simple ignition. 
 
 Giant Powder. Nitro-glycerine, sodium nitrate, resin, sulphur, 
 infusorial earth. Also a name used for Dynamite. 
 
 Jiidson Powder. Nitro-glycerine, sodium nitrate, resin, sur- 
 phur, asphalt, coal. Also a form of Dynamite. 3^,, 
 
 Atlas Powder. Nitroglycerine, sodium nitrate, wood fibre, 
 magnesium carbonate. 
 
 Hercules Powder. Nitro-glycerine, potassium nitrate, and 
 chlorate, magnesium carbonate and white sugar. A form of Dynamite. 
 
 JEtna Powder. Nitro-glycerine, &c. A form of Dynamite. 
 Different grades of the above are manufactured which vary in the 
 percentage of nitro-glycerine. 
 
 Miclialowoki's Blasting- Power. This is a chlorate com- 
 pound with manganese binoxide and organic matters. 
 
 Picric Acid Compound*. Oil of tar treated with nitric acid 
 yields crystals of picric acid the salts of which are explosive. The 
 powders containing these salts have not been much used. Abel's 
 powder, Designolle's powder, Melinite. 
 
 <; u ii -co i ton. Gun-cotton is prepared by treating cotton or 
 cellulose with a mixture of sulphuric and nitric acid. After this it is 
 well washed and treated with a dilute alkali. 
 
 It may he exploded by a smart blow and it ignites at temperatures 
 between 50 and 100 C. 
 
 It is prepared as solid or hollow cartridges, granulated, as cord 
 and as paper. When not confined it only burns. The gases after an 
 explosion are CO, CO 2 , CH 4 , N, H 2 O, and H. The fumes of CO 
 render the use of guncotton in mines objectionable. 
 
62 
 
 Preparations of guncotton soaked with nitrates and chlorates have 
 been prepared. 
 
 <> is a mixture of barium nitrate and gun cotton. 
 
 Rob 11 rite is a mixture of ammonium nitrate and chloro-nitro- 
 benzine. Used in the Wigan coal district. 
 
 Securite is nearly the same at Roburite and Bellite. 
 Belli te is a mixture of ammonium nitrate and di-nitrobenzole. 
 Ammonite. Here there is an excess of ammonium nitrate. 
 Amongst the smokeless gunpowders, we find : 
 
 Amide Iowfer. A mixture of potassium and ammonium 
 nitrates and charcoal. 
 
 Nobel's S'owder. Nitro-glycerine, nitro cellulose, camphor. 
 Pondre Vieille. Used with the Libel rifle. 
 
 4aens lowder. Nitro-cellulose, potassium nitrate, ammonium 
 ulmate. Walthamite, Cordite &c. 
 
 For a complete list of explosives see "A Dictionarv of Explosives'' 1 
 by Major J. P. Cundill. 
 
 IJme Cartridges. Generate a steam pressure of 2,850 Ibs. and 
 expand to five times their original bulk. They are extremely safe and 
 give neither smoke or smell. Sebastian Smith and Moore. 
 
 Water Cartridge's. When an explosion is surrounded by 
 water it may secure safety against blown out shots in a dangerous 
 atmosphere. Settle and Abel's. 
 
 Position off Bore Holes. If there is only one unsupported 
 face, a hole requires to be angled. Thus in sinking a shaft or in driv- 
 ing a level, one or more holes angled in the center of the face to be 
 removed, will form a 'cut, key or core. Successive holes may be 
 driven at right angles to the face and arranged either concentrically- 
 round the key* or else parallel to the sides of the level. Rupturing 
 holes are sometimes employed. 
 
 In driving a level where the dip is downward and towards you, 
 work from above downwards, but when the dip is away from you, work 
 
from below upwards. If driving parallel to the strike, work from an 
 advanced cut, either to the right or left or across a level. 
 
 of least resistance. The quantity of explosive employ- 
 ed in different bore holes in the same class of rock ought to be pro- 
 portional to the cube of the line of least resistance. 
 
 This rule apparently implies that the weight of rock which is- 
 lifted is proportional to the resistance to be overcome. - So far as- 
 rupturing the rock is concerned, the quantities of explosive employed 
 in any two cases ought to vary as the square of the line of least 
 resistance. 
 
 With a quick explosive where inertia is a factor in the resistances 
 to be overcome, the quantities of explosive may be proportional to the 
 length of the line of least resistance. 
 
 To increase the resistance along the line of tamping, a strong ex- 
 plosive occupying little bulk must be employed. The length of tamping 
 may be increased by enlarging the bottom of a bore hole. In limestone 
 rocks at Marseilles this has been accomplished by the use of nitric 
 acid. The length of the line of least resistance should not exceed 
 half the depth of the hole. 
 
 For gunpowder, one rule is to use half the cube of the line of least 
 resistance measured in feet, as equal to the number of ounces to be 
 employed. 
 
 XL* 
 The rule given by Molesworth is, P= g 
 
 When Z=Line of least resistance in feet. 
 
 X= Number of ounces of powder required when L 2. ft. 
 P= Quantity of powder required in ounces. 
 
 For large blasts see Hydraulic Mining p. 86, also p. 56. 
 
 Selection of an Explosive. In selecting an explosive con- 
 sider its strength, its safety, the effect produced upon it by moisture, 
 heat &c., the gases evolved by explosion, and its price. 
 
 An explosive whose detonation temperature is less than 4000 F 
 fired in a properly stemmed hole will not ignite fire damp. Under very 
 favourable circumstances a temperature of 1200 F may ignite fire 
 
6 4 
 
 damp. For safety the temperature of detonation should not exceed 
 2700 F. Nitrate of Ammonia detonates with a temperature of 1850 F 
 and it is used with dynamite, gun cotton, &c. to reduce the temperature 
 of detonation. The French Government has ordered the use of this class 
 of explosives for fiery and dusty mines. H.M. Inspectors of Explosives 
 adversely report on the use of ammonium salts except the carbonate, 
 the reason being that ammonium salts by exposure become acid 
 and nitro-compounds like gun-cotton, nitro-glycerine are affected by 
 acids, and decomposition followed by ignition or explosion may occur. 
 
 The strength depends upon, the quantity of gases developed, the 
 nature of the gases, the heat generated to cause expansion, and the 
 rapidity of explosion. In similar bore holes the space occupied by 
 equal weights of different explosives will be inversely as their 
 densities. 
 
 SPECIFIC GRAVITY. 
 Gunpowder I or over. 
 Dynamite 1.5 
 
 Cotton powder 1.5 2 
 Gun-cotton I or under. 
 
 Nitro-glycerine 1.6 
 
 TEMP. OF EXPLOSION. 
 2231 C. 
 2940 
 
 2 6 3 6 C 
 3 i 7 o c 
 
 Contents of One Inch of a Bore Hole (Andre). 
 
 Diam : hole inches. 
 
 i 
 
 itf 
 
 ^ 
 
 $ 
 
 2 
 
 *y 
 
 2^ 
 
 *% 
 
 3 
 
 Gunpowder or Gun \ 
 cotton, oz j 
 
 .419 
 
 .654 
 
 .04 
 
 1.283 
 
 *-675 
 
 2.I2O 
 
 2.618 
 
 3.166 
 
 3-769 
 
 Dynamite, oz 
 
 .670 
 
 1.046 
 
 1-507 
 
 2.053 
 
 2.680 
 
 3-392 
 
 4.189 
 
 5.066 
 
 6.030 
 
 Force developed by explosion of Gunpowder (Andre). 
 
 When gunpowder is exploded 56 / of solid matter is formed and 
 43 % of gas, or the solid matter is to the gaseous matter as 6 : 4. 
 
 The gas produced at a temp, of 32 F is 280 times the bulk 
 of the powder employed, therefore the pressure developed is 
 
 X 15 = 10,500 Ibs. =4.68 tons. But the temperature is raised to 
 
65 
 
 4,ooo F (absolute temp.) : or starting from an absolute zero (461.2 F)- 
 the temperature has been raised 8 - ii times. 
 
 The pressure in the cavity is therefore 4-68xS-n or 42-6 tons per 
 square inch. Such pressures have been indicated by gauges. 
 
 COAL CUTTERS, 
 
 When we consider the unfavourable circumstances under which a 
 collier works whilst hewing coal, we should naturally suppose that 
 the work ought to be better accomplished by means of some machine. 
 
 One of the machines devised for this purpose was invented by Mr. 
 Pierce, of Wigan It consisted of a pick attached to a bell crank lever 
 which was worked backwards and forward, by having one of its arms 
 attached to a reciprocating piston rod of a small engine. The method 
 in which it cut the coal was similar to the method in which it was cut 
 by hand labour. For this reason the miners christened it the " Iron 
 man." Like many other inventions, which are the first of a series, it 
 did not realize its originator's expectations, and quickly fell into 
 disuse. Since the death of the ' Iron man" a number of other 
 machines have been devised, and several of these are to be seen io 
 daily use at several of our collieries. These machines have not how- 
 ever yet reached that perfection, which there is every reason to believe 
 they are destined to attain, and whether any particular coal cutter 
 works satisfactorily still depends greatly upon local circumstances. 
 
 From the following notes on Coal Cutters, which are largely taken 
 from Andre's Coal Mining, it will be seen that these machines may be 
 divided into three groups, those working with a percussive chipping 
 action like a pick, those which pare or cut the coal like a plane, and 
 those which cut or scrape it away like a circular saw. 
 
 Commencing with the oldest type like the ' Iron man " we have 
 the following. 
 
 Firth's Coal C litter. This consists of ahorizotal steam cylinder 
 5in. diameter I2in. stroke. The piston rod of this, works the arm of a 
 bell crank lever, to the opposite end of which a pick is fitted. To 
 allow of a certain regulation for the position of the line of under- 
 cutting, this pick can be fixed at various ela**ffiSpsTiTW.filpt. On the 
 
66 
 
 piston rod there is a tappet which gives a reciprocating motion to the 
 slide valve. From this it will be seen that the pick must make its full 
 stroke before it can be drawn back. The machine is advanced by 
 "hand, by means of gearing connected with the hind wheels of the frame 
 or car on which the machine is carried. When working, the first cut 
 is made with a pick of about 75 Ibs. weight, working at the rate of 70 
 "blows per minnte, to a depth of about 2 feet. After this, the pick of 
 75 Ibs. weight, is replaced by a longer pick weighing 90 Ibs., and the 
 same cut is gone over again and is completed to a depth of about 3 ft. 
 5in. In 24 hours a cut of this depth has been made along a face 257ft. 
 in length. 
 
 In an improved form of the machine the whole depth is cut at one 
 operation and the advance of the machine is automatic. The pick will 
 cut in any position, and the back stroke of the pick, by making the 
 front side of the piston of less area than the back, is more gentle. 
 
 The vibration to which the machine is subjected and the loss of 
 time during the back swing of the pick seems to have rendered 
 machines of this discription not so desirable as those which have been 
 constructed upon other principles. 
 
 Soliram and Oliver's patent coal cutting machine. This ma- 
 chine is percussive in its action, working a system of five or more picks 
 making up to 400 strokes per minute. 
 
 C'arrtt and Marshall's Coal C'nitr. This consists of a small 
 hydraulic cylinder 5in. in diameter, the piston of which makes a stroke 
 of i8in. To the end of this piston there is a bar about 4 ft. in length in 
 which 3 cutters are fixed. These cutters project one beyond the other 
 like a series of steps. As this bar reciprocates it cuts its way into 
 the coal. At the same time that the forward portion of this move- 
 ment takes place, that is while the coal is being cut and when there is 
 consequently a heavy back thrust upon the carriage carrying the 
 machine, water is admitted into a second cylinder standing vertically, 
 which in consequence drives its piston, the end of which is provided 
 with a bearing surface against the roof. By this means the carrying 
 carriage is clamped down tightly upon its rails. During the return 
 stroke of the cutter, the clamping piston is drawn down and the car- 
 riage is automatically advanced ready for the second cut. 
 
 In this way about .zo cuts are made per minute, and during an 
 hour, the coal will be undercut to the depth of 4ft. 6 in. for a length 
 
67 
 
 of about 20 yards. The water is under a pressure of about 300 Ibs. 
 By means of a hand wheel the cutting cylinder can be turned so that 
 the bar may work into the coal in various directions, or whilst being 
 removed from one point to another, may be placed parallel with its 
 -carrying car. 
 
 Economic Coal Cutter. The essential portion of this 
 machine is a long bar on which a deep screw has been cut. On the 
 thread of this screw a number of cutting teeth are so fixed that when 
 the bar is revolved against a face of coal it tends to cut its way in a 
 direction at right angles to its length. By means of suitable gearing, 
 this cutting bar can be canted or turned round. The advance is 
 automatic. 
 
 The I.VSK Wining- Machine. This also works with a cutter 
 bar with 26 bits on it, which is revolved. 
 
 liaird's C'oal Cutter. In this machine we have a small air 
 cylinder 8^in. diameter with a I2in. stroke which by means of suitable 
 gearing drives two horizontally placed star wheels. These carry an 
 endless chain bolted into the links of which, are the cutters. In one 
 hour it will undercut to the depth 3 ft. for a distance of about 15 yards. 
 The motion of the machine along the face is automatic. 
 
 Wiiistanle.v and Barker's C'oal Cutter. This machine 
 undercuts the coal in a manner similar to the way in which the work 
 would be done by using a horizontally revolving circular saw. 
 
 In this machine 2 oscillating cylinders drive a vertical shaft, 
 carrying a star wheel gearing into the teeth of a large wheel placed 
 horizontally. This latter wheel, which is 3 ft. 6in. in diameter, has each, 
 of its teeth furnished with a socket, into which a cutter is bolted. 
 The teeth of the star wheel are so large that they do not touch the 
 cutters. The cutting wheel is carried on a large arm which can be 
 turned out or in by means of a hand wheel turning a worm gearing in 
 .a rack fixed on to the arm at the opposite end from the cutting wheel. 
 By this contrivance it will be observed that the cutting wheel may be 
 -caused to hole its way into the coal. 
 
 It will cut 3 ft. deep for a distance of from 20 to 25 yards per hour. 
 
 Oil lot and Copley's Cal Cntter. The general principle of 
 this machine is similar to the one just described. One chief difference 
 
68 
 
 is that the cutting wheel can not be pivoted in and out, being carried: 
 upon a fixed arm. This cutting wheel is driven by beveled gearing, 
 in connection with 2 air cylinders. These which are yin. diameter 
 and I2in. stroke are placed side by side. 
 
 This machine makes a cut about 3ft. 4in. deep for a length of 
 about 20 yards per hour. 
 
 Oeiieral remark* on Coal Cutters. All the machines which 
 have been referred to with the exception of Garret and Marshall's coal 
 cutter, which is worked by water power, are driven by compressed air. 
 The reason that water power is required in the Garret and Marshall 
 Machine is because the principle on which the cutters work make it 
 necessary to apply a strong steady pressure, and as only small 
 cylinders are admissible in underground machines, such a pressure 
 could not well be obtained by means of air. As there is comparatively 
 little expansion to be obtained when working with air, the engines 
 which are used, are specially constructed. The ports are made large, 
 the stroke short and the speed quick. 
 
 In nearly all these machines, quick speeds are reduced and power 
 is gained, so that the cutting portion of the machine has comparatively 
 a slow motion. This intermediate gearing although advantageous in 
 giving a steady powerful motion, is not to be recommended on 
 account of its liability to derangement. When we consider the 
 circumstances under which a coal cutting machine works, it is 
 evident that because it is so liable to derangement it ought to be 
 made light and rigid, and at the same time its parts as few as possible. 
 The advance of these machines is generally automatic, the machine 
 hauling or winding itself upon a chain, one end of which is anchored 
 at the end of the face along which it is cutting. The rails on which 
 the machines run ought to be of the same gauge as those which are 
 ordinarily used in the mine. In many cases the gauge is broader. The 
 machine ought also to hold itself upon its rails or else be capable of 
 being easily clamped. In Baird's machine it will be observed that 
 the action of cutting, tends to drag the carriage towards the face which 
 is being cut, while in Garret and Marshall's machine the carriage is 
 being pushed in an opposite direction. Much may be done to coun- 
 teract these forces by fixing the hauling chain in a proper position- 
 Generally speaking it will be better the nearer it is to the face. 
 
6 9 
 
 When circular cutters are used it will be observed that it will be 
 necessary to make the floor as even as possible. The feed ought to be 
 self regulating, and the cutter ought to be able to cut in various direc- 
 tions. Most of the coal cutters can only be used for holing or under- 
 cutting, and the slitting has to be accomplished by hand. As many 
 parts as possible of a machine ought to be protected by a cover. 
 
 Bar cutters can be more easily made to undercut to a greater 
 depth than disc cutters; they are not so likely to be jammed when 
 working in tender coal, and as the bar can be replaced, new cutters are 
 put in more quickly than they can be with a disc machine. Many disc 
 machines do not cut their way into the coal. Bar cutters may be 
 more conveniently driven by electric motors which run at about 700 
 revolutions per minute, the cutter making 500 revolutions. Amongst 
 electrically driven coal cutters we have those of Edison, Goolden &c. 
 
 The advantages which we should expect to derive by using a 
 well adapted coal cutter are many. The work would be accomplished 
 quickly, and fewer men would be employed. As a consequence of a 
 reduction in the working staff fewer lives would be exposed to ac- 
 cident. Most important of all, however, would be the great saving in. 
 coal due to the more perfect undercutting. "When undercutting is ac- 
 complished by hand, say to a depth of 3 feet, a more or less wedge shap- 
 ed opening is made, which at the front is 10 to I5in in height. The coal 
 which in this way is reduced to a state of powder may in a thin seam 
 -amount to 25 per cent of the whole quantity which is excavated. Not 
 only does a machine avoid a great portion of this waste by making a cut 
 which is not more than 3 to 4in. in height, but by undercutting to a 
 greater depth, it renders the process of wedging more easy, and a 
 larger quantity of coal is extracted at one operation than can be 
 extracted when the operation has been performed by men. Also we 
 may remark, that a machine will almost equally well perform the 
 operation of undercutting in a hard parting, as in the softer coal. For 
 these and other reasons it seems certain that the time is not far distant 
 when coal cutters will be more universally used, and it will only be 
 in exceptional cases where the coal miner will be called upon to carry 
 out the laborious and dangerous operation of undercutting. 
 
 Coal Vk'fdKiiiyr Machines. The wedge of Bidder and Jones 
 is a modification of the plug and feathers system used in Quarrying 
 blocks of stone the wedges corresponding to the feather being forced 
 
7 o 
 
 apart by a hydraulic press. In Cox's wedge, the portion corresponding: 
 to the plug is driven in by a sledge. Another wedge is that of 
 Grafton Jones. In the Sampson Coal Getter the wedges are forced in 
 by a screw. With Burnett's Roller Mining Wedge, a wedge is drawn 
 between rollers which force out feathers. 
 
 Stanley's ConI l>rif'fii>8r Machine. This machine cuts ah 
 annular groove rouifd the face of a drift leaving a core which is 
 then broken down. At Nuneaton Colliery it is said to work well, the 
 rate of advance being four times that of hand labour. Diameter of 
 level 5 '.4". 
 
 Other tunneling machines are Brunton's and Beaumont's. The 
 latter was used in the Channel Tunnel. 
 
 ROCK 
 
 The following notes on Rock Drills and air compessors are chiefly 
 epitomized from more complete descriptions give by Andre in his 
 "Mining Machinery." 
 
 Rock drills should be simple, light, strong, small ; they should 
 strike the rock directly, the stroke should be capable of alteration, 
 sudden removal of the resistance should not cause injury, the rotation 
 should be automatic, the feed should be regulated by the advance of 
 the piston ; they should be able to work with pressure, easily taken to 
 pieces ; finally they should be adjustable at any angle, and portable; 
 Hand feeding is usual. 
 
 It is better to have a heavy blow produced by mass than by a high 
 velocity. With a small mass and high velocity, vibration and wearing 
 take place. 
 
 About 1845 M. Mans who was engaged in the construction of the 
 Turin-Genoa line of railway designed a set of drills which were 
 pressed backwards by means of cams against a set of springs; on being 
 relieved, they flew forward and struck a blow. 
 
 In 1851 Cave introduced the principle of making a drill the 
 prolongation of a piston rod worked by air or steam. 
 
In 1855 Thomas Bartlett introduced a drill, consisting of a simple 
 acting engine, the piston rod of which passed into a cylinder where at 
 each stroke it compressed the included air. By the expansion of this 
 air the drill which was attached to the piston rod was forced forwards. 
 One of the first practical machines was introduced by Sommeiller in- 
 driving the Mount Cenis tunnel, his great improvement being to make 
 the " feed " automatic: 
 
 The general nature of the working parts of a rock drill may be 
 understood from the three following brief descriptions. 
 
 Iner*rsoll Roek Drill. The tool is a continuation of a piston 
 rod working in a cylinder. The' back part of the piston is hollow and: 
 runs backwards and forwards upon a spirally grooved bar inside the 
 cylinder. At the end of this bar there is a ratchet with a detent which 
 will allow it to be turned only in one direction. As the piston comes- 
 back it twists itself upon the bar which is prevented from turning by 
 the ratchet and detent, whilst during the forward motion because the 
 bar turns with it, it goes out straight. This gives the requisite rotation. 
 to the tool. 
 
 By means of tappets and spindles the requisite motion is given to- 
 the valve in the valve box. As the tool cuts into the rock the fore 
 part of the piston continually approaches a tappet. On striking it, the 
 motion of the tappet partially turns a rod and this by palls and. 
 ratchets turns the feed screw and the tool is automatically advanced to- 
 its work. 
 
 ]>iiIis-Francois Roek I>rill. This drill is one which is 
 much used in Belgium and France. Its mode of action is based upon 
 the machine of Sommeiller. The piston like the pistons of other 
 machines has a larger area at the back than in front. This works in 
 a cylinder into which compressed air is admitted by an ordinary slide 
 valve. This valve is connected with two small pistons. When air is 
 admitted into the valve chest, because the right hand piston is larger 
 than the other, the valve moves to the right and air enters the 
 cylinder. This drives the main piston and the boring tool forwards. 
 During the time that this action is going on, air is escaping by a small 
 passage to the back of the larger of the small pistons, and this con- 
 tinues until there is equilibrium on both sides ofjj^pisteft. The air 
 is now able to act upon the smallest piston anoVb^yo^i moves to the 
 left, and air enters the main cylinder at its front end, and the main 
 
72 
 
 piston makes its back stroke. During this back stroke an annular 
 projection strikes a lever, which opens a valve and allows the air to 
 escape from the back of the larger of the small pistons. The equi- 
 librium of this piston being destroyed, it is again driven to the right 
 :and the action repeated. 
 
 In connection with the main air passages, are two small single 
 acting pistons which have an alternating up and down motion. This 
 is communicated through a rod to a ratchet wheel, and the requisite 
 feed obtained. 
 
 Darlington Rock I>rill. The Darlington Rock drill, is a 
 drill which deserves especial attention on account of its simplicity. 
 All valve gear is dispensed with, and on account of the fewness of its 
 iparts, it is a machine which is 1 likely to take a leading place amongst 
 Rock Drills. 
 
 In the main cylinder the piston and its rod by working backwards 
 and forwards upon a spirally grooved bar in connection with a ratchet 
 wheel, receives the requisite twisting motion, as in the Ingersoll Drill. 
 
 Air entering at an inlet port, drives the piston to the right. As 
 it goes back, it first covers the exhaust port and then opens an 
 equilibrium valve passage. The air then acts on the back of the 
 piston, and because this back area is larger than the front area, the 
 piston before it reaches the end of its back stroke is driven forwards. 
 AVhen it passes the exhaust port, the air escapes, and the equilibrium 
 passage is closed and the air again only acts upon the front face of the 
 ipiston. 
 
 With a pressure of 40 Ibs., 1,000 blows per minute can be given. 
 
 Amongst the many other drills which have been invented we 
 "have the Victor, the Royal, the Eclipse, the Barrow, the Cornish, the 
 Excelsior, the Cranston etc. The following will serve as an example 
 of the cost of rock drills. It is quoted from the price list of the 
 'Sandycroft Foundry near Chester. 
 
 The Randy-croft Patent, Rock I>rill. This Drill is being 
 used in Mines in various parts of the world with excellent results. 
 'Some of its principal advantages are durability, simplicity in operation, 
 economy in the consumption of compressed air, and adjustability. 
 The pressure necessary to drive the Drill may vary from 2 5 to 70 Ibs. 
 per square inch, and the number of strokes of the Drill, from 50 to 
 J,ooo blows per minute. 
 
73 
 
 Prices of Air-Compressing- Engines and Roclt Drills : 
 
 Number of\ 
 
 
 
 
 
 
 
 
 
 
 
 Drills Air-1 
 
 ~~ 
 
 ^~ 
 
 c 
 
 .= = 
 
 = ~ 
 
 
 c~ 
 
 = -^ 
 
 z . 
 
 = - 
 
 Compressor f 
 will supply.-) 
 
 rf9 
 
 Q 
 
 ^ 
 
 voQ 
 
 0-4 
 
 MM 
 
 _ 
 
 5 
 
 *"C 
 
 voQ 
 
 --- 
 
 oo~ 
 
 Rock Drills ... 
 
 45 
 
 90 
 
 /i8o 
 
 &7 
 
 ' 
 ^405 
 
 540 
 
 120 
 
 ^240 
 
 360 
 
 480 
 
 Air-Compres- 
 sing Engine./ 
 
 13 
 
 i95 
 
 380 
 
 46* 
 
 ^635 
 
 7*o 
 
 380 
 
 635 
 
 820 
 
 ^945 
 
 Electrically driven Rock Drills. In one class of these 
 drills the reciprocating motion is obtained by sending a current first 
 through one solenoid and then through another, the iron core being 
 attracted first in one direction and then in another. Owing to the 
 heating of the solenoids this type of drill has not yet become successful. 
 
 In a second type, a motor by gearing, drives a cam which forces the 
 drill back against a spring, which when the cam has passed, drives the 
 drill forwards and strikes a blow. 
 
 Hand power drills. In hand power drills by the revolution 
 of a wheel turned by hand, cams are caused to force a piston behind 
 the drill, back into a cylinder and then compress the included air. 
 After the passage of the cam past its tappet, the expansion of the 
 included air drives the drill forward. Amongst these drills we have 
 Tordans and Burtons. In Ingersoll's hand power Rock Drills the blow 
 is obtained from the compression of a 200 Ib. volute spring. 
 
 Borer Bits. The Bits or Drills which are used with rock 
 cutting machines are in many respects similar to those which are used 
 for hand boring. To keep the bore hole perfectly straight it is 
 necessary that the borer should be well centered, that is a line along 
 the center of the piston rod, if continued, ought to pass through the 
 central edges of the bit. The edge of the bit may be straight or 
 curved, x, T, and Z shaped bits, give a greater cutting surface, and 
 tend Jo keep the hole straight. They also clear the hole of accumulat- 
 ing debris better than a straight edged bit. The sharpening of them 
 is, however, more difficult. The shape at the end of the shank will 
 depend upon the method in which it is attached to the end of the 
 holder on the piston rod. That this attachment should be simple and 
 secure is a point worthy of careful attention. 
 
74 
 
 Fixing Rock Drills. When sinking a shaft the drill is 
 generally supported upon a horizontal bar, along which it can slide, or 
 if desired, be clamped at any point. The bar which ought to be both 
 light and strong, carries at either end a lengthening screw. By turning 
 these two screws outwards the bar can be fixed against the walls of the 
 shaft. Sometimes by means of four radial bars a leg is firmly fixed in 
 the center of the shaft. The top of this leg then acts as a pivot for 
 one end of the stretcher bar carrying the drill, the other end of this 
 bar being fixed by a lengthening screw against the side ol the shaft. 
 By this arrangement a large number of holes may be rapidly bored, 
 very little time being lost in shifting the machine from one point to 
 another. Before blasting takes place, the whole of these arms and 
 stretcher bar are by means of a chain raised a sufficient distance up the 
 shaft to escape damage. 
 
 When driving a level, a stretcher bar may be used, fixed either 
 horizontally or vertically. In the latter case, to facilitate removal 
 before blasting, it is sometimes carried at the end of a small car running 
 on rails. The drill itself is supported on a small arm branching at 
 right angles from the main bar. This arm can be raised or lowered 
 along the main bar, and it can be fixed to the side of the level by a 
 lengthening screw. If the tunnel which is being driven is of large 
 dimensions, a number of rock drills may be arranged together on a 
 suitable frame-work, the whole being carried on a tram. In open 
 works where it is inconvenient to use a stretcher, the drill may be 
 supported on a tripod. 
 
 The speed attained with drills depends a good deal on the speed 
 with which the machines are got to work after blasting. To attain 
 this the chief points to be observed are : 
 
 1. Quick clearing away of smoke by mechanically ventilating 
 
 the end. 
 
 2. Quick removal of stuff by having track laid up to the end, and 
 
 an organized system of removing. 
 
 3. Quick and firm securing of machine in a position for farther 
 
 work. To do or this, judgment in the men and a good 
 supply of carefully cut wedges are needed. 
 
 4. A fair proportion of skilled men looking after the machines. 
 
 5. A spare machine or two always on hand in working order. 
 
75 
 
 Economy of Rock Drills. Rock drills may often be used with 
 advantage in places where the difficulties of transmitting compressed 
 air are not very great, and where the drill being once in position may 
 be employed in boring a number of holes. 
 
 The greatest advantage will be obtained when working upon hard 
 rocks like granite, in which holes may be bored at the rate of 5 in. per 
 minute. In these rocks by using a machine, there may be a gain 
 both in time and money. In mild rocks, however, the gain will be 
 only one of time, machine work being perhaps twice as rapid as hand 
 work. 
 
 In India (Mysore) the speed compared with coolie hand labour is 
 from three to as much as seven times as great. 
 
 In soft rocks hand labour will be the most economical. 
 
 When holes are bored by hand as much as 5 or 6 times the 
 quantity of steel may be used, as compared with the quantity which 
 would have been used in replacing old borers had the work been done 
 by machine. 
 
 By hand work a man can bore per day in granite 50-100 inches 
 and in limestone 300-400 inches. 
 
 RotMry Rock Drills. In Belgium and France, for boring 
 holes in soft rocks like gypsum, salt or coal, a drill, in principle very 
 much like the tool used by mechanical engineers when boring a hole 
 through an iron plate, is often employed. Lisbet's drill consists of a 
 steel pointed auger turned by a lever and a ratchet, the arrangement 
 being such that it can be either turned round whilst remaining in 
 one position or it can be advanced into the rock. 
 
 Macdermott and Williams rock perforator used in making holes 
 for the reception of a hydraulic wedge when lalling coal is of this 
 order. 
 
 Another form of rotary rock drill is in its action very similar to 
 the large Diamond borer employed in sinking deep bore holes. 
 
 In Leschot's drill, a tube is furnished at one end with a crown 
 of diamonds. By suitable machinery this is rotated against the rock 
 which is to be bored. The advance of the borer is effected by means 
 of gearing. This gearing connects the revolving borer with a screw 
 which carries it. As the borer revolves to cut the rock, the screw 
 
7 6 
 
 slowly turns and keeps it to its work. The rock is cut away in the 
 form of a core which passes into the hollow borer. Water is forced 
 down the borer to clear away the debris. 
 
 These diamond borers have not yet been very largely employed 
 for holes for blasting, but the larger drills have been considerably 
 used for prospecting. 
 
 Use of Water. Whilst the boring operation is going on it is 
 customary to keep the hole wet by means of a jet of water. This 
 jet may be supplied from a water lank, the water in which is kept 
 under pressure by means of a pipe in connection with the air conduits 
 of the drill. 
 
 By.keeping a hole wet, the debris is cleared out, the wear of the 
 drill is lessened and the rate of advance is usually quickened by one 
 half more than what the rate would be if the hole were dry. 
 
77 
 
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 s 
 
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 s 
 
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 t^. \rt vo HJ CO 
 
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AIR COMPRESSORS. 
 
 An ordinary air compressor may be described as a large air pump. 
 It consists of a cylinder with two sets of valves, one set opening inwards 
 and the other set outwards. By the reciprocating action of a piston-, 
 air is drawn in at the former and driven out at the latter. 
 
 Blanzy Collieries. At these collieries the cylinders of the air 
 compressors are placed horizontally. At each end of them there are 
 two valves one of which opens inwards and the other outwards. 
 Through the former, air is taken in from the atmosphere and through 
 the latter it is compressed into the receiver. Round the cylinder there 
 is a jacket in which cold water circulates, and at one end of it there is 
 a water pipe which injects a jet of spray into the cylinder itself. 
 
 Collation's Air Compressor. In this compressor, which 
 was used during the making of the St. Gothard tunnel, water circulates 
 round the cylinder and at each end two small jets which strike each 
 other and break up into a fine spray are injected. The piston and the 
 piston rod are hollow. The latter, which is continuous, slides upon a 
 small pipe passing into its hollow interior. Throngh this a jet of water 
 is forced and by means of a series of suitably placed diaphragms a 
 continuous circulation of water is kept up through the piston and 
 its rod. 
 
 Sturgeon's Air Compressor. The action of this compressor 
 depends upon the peculiarity of the inlet valves which allow the 
 machine to be run at high speeds. These valves form a portion of the 
 stuffing boxes through which the piston slides. When the piston 
 moves from one end of the cylinder, the stuffing box by its own fric- 
 tional grip is carried with the piston until it meets with a stop. This 
 motion of the stuffing box opens the valve, the action being independent 
 of any vacuum being formed inside the cylinder. When the piston 
 returns this frictional grip of the stuffiing box carries it with the piston, 
 and the valve is closed, independently of any compression on the inside 
 of the cylinder. The delivery valves are closed by springs. 
 
 The crank of the engine and compressor are placed at right angles 
 so that when the piston of the compressor is near the end of its stroke 
 and the greatest power is required, the steam crank pin is in its best 
 position for supplying the required force. 
 
79 
 
 The receiver forms the bed on which the compressor and its 
 engine rest. By means of a plunger working in this receiver, as the 
 pressure increases the speed of the compressor is decreased. 
 
 Roncliini Collieries. The compressors at these collieries 
 consist of two vertical iron cylinders in connection with the two open 
 ends of a horizontal cylinder in which there is a reciprocating piston. 
 The vertical cylinders which are partially filled with water, have on 
 their tops a delivery valve working upwards and two clack valves 
 working inwards to admit the air. 
 
 By the use of the column of water no clearance space is lost at the 
 end of a stroke, at the same time the air is kept cool even when com- 
 pressing to a pressure of four atmospheres. 
 
 Snrrebruck collieries. The compressors at these collieries 
 work on a similar principle to those last described, namely by the 
 intervention of a column of water. 
 
 J,oss of Work. For the sake of simplicity we will imagine 
 that the compressor is a cylinder C in which there is a piston P 
 without weight, and working without friction. The work which is 
 being done is to compress air through a valve V into a receiver R 
 where there is a constant pressures of two atmospheres. 
 
 As the piston P moves down the cylinder, the air, which at the 
 commencement was at the ordinary atmospheric pressure, is compres- 
 sed, and heat is developed. If this heat escapes through the cylinder, 
 that is to say, if the temperature of the air which is being compressed 
 remains constant, then, if we double the atmospheric pressure, we 
 shall reduce the volume of air in the cylinder C to half its original 
 bulk and the piston will descend half way down the cylinder to M N. 
 
 The pressure in the recevier R being equal to two atmosphere?, 
 the valve V will now open and the compressed air from the cylinder 
 will enter the receiver. To complete the work which is being done 
 in driving the air which originally occupied the whole of the cylinder 
 C into the receiver R, the piston will work against a pressure, of two 
 atmospheres through the space M Q. 
 
 If, however, the heat which is developed by compression does 
 not escape, but raises the temperature of the compressed air, and thus 
 causes it to expand, the pressure of two atmospheres will be reached 
 
 0' 
 
 
8o 
 
 when the piston reaches some line Tike O A and to force this air 
 into the receiver, the piston, in order to complete its work, will have to 
 work against a pressure of two atmospheres through the distance O Q. 
 
 If the volume of air O A Q S forced into R retained the volume 
 with which it entered, there would be no loss of work. But because 
 in practice it is imposible to confine the heat which gives this volume, 
 the air contracts and the actual air in the receiver is not more than if 
 the volumes M Q S N at a lower temperatnre had been forced in. 
 The result of this is that the piston P has worked against a force 
 through the distance O M, which work has been converted into heat 
 and the heat subsequently lost. 
 
 To remedy this evil, as it is impossible to prevent the genera- 
 tion of heat, instead of allowing it to raise the temperature of the air 
 it is carried off in the water jacket on the cylinder. 
 
 Loss due to Sltp and Clearance. In an air compressor in 
 which a column of water is employed, the water drives all the air 
 through the discharging valves on towards the receiver. Where a 
 piston 'acts on the air, as it is not possible to allow the piston to come 
 close up to the end of the cylinder in which it works, a certain 
 portion of compressed air always remains in the clearance space at the 
 end of each stroke. This quantity may be increased by the slip, at the 
 discharging valves, in consequence of which a certain quantity of air 
 which had been once forced out of the cylinder into the receiver, 
 slips back into the cylinder during the discharge. If valves are very 
 large and open wide, this quantity which slips back may be very 
 great. 
 
 At the end of each stroke of the piston there will therefore always 
 be a certain amount of compressed air left in the cylinder, and before 
 the inlet valves of the cylinder can open to admit more air, the 
 entrapped air will have to expand until it is below atmospheric 
 pressure. The distance that a piston will have to travel back to 
 allow this expansion to take place, will grow greater as the compres- 
 sion increases. 
 
 Loss of Work from other Sources. There is a loss of work 
 due to the friction of the various parts of the machine, and also by 
 the friction of the air in the various passages through which it 
 moves. If valves are contracted and have a small lift, there will be 
 
8* 
 
 much friction. In the conduits, so long as the velocity of the air 
 is low, say not more than 4ft. per second, the loss by friction is 
 very small. 
 
 The friction varies with the area of the surface over which it 
 rubs. It therefore varies directly as the length of the pipes through 
 which it passes, and inversely as their diameters. If the rates of flow 
 rae small, it will vary with the square of such velocity. (See Notes 
 on Ventilation.} 
 
 Air Conduits. These are usually pipes made out of cast or 
 wrought iron, flanged at their ends and fitted together with India 
 rubber washers to make them air tight. If such pipes are long it 
 may be necessary, every 100 yards or so, to insert a bent copper pipe 
 or to bend the pipes to form a loop, so that expansion may take place.. 
 
 The branch pipes leading from the main conduits up to the 
 machines are usually flexible India rubber tubes, about 2in. in diameter 
 covered with canvas or served with marlin. 
 
 Air Receivers. As it is necessary that a machine should be 
 supplied with a steady flow of air. also as the air is not used so 
 regularly as it is supplied from the compressor, air receivers are 
 employed. 
 
 For this purpose old boilers are very often used. These should 
 have a capacity about 20 times as great as the average consumption 
 per minute. As a large amount of water is carried with the compres- 
 sed air when it leaves the compressor into the conduits leading to the 
 receiver and into the receiver itself, means must be provided for its 
 discharge. In some cases this consists of a simple cock or valve 
 worked by hand. In other cases by taking advantage of the rising of 
 a float in the water, this is made automatic. The exit from receivers 
 should not be opposite to the entrance but by preference on the same 
 side. 
 
THE PRINCIPAL DIMENSIONS OF AIR COMPRESSORS AT THE 
 BLANZY COLLIERIES (Andre.) 
 
 Diameter of steam cylinder 25.6 inches 
 
 Diameter of compressor cylinder 21.7 ,, 
 
 Stroke of pistons 63.0 ,, 
 
 Area of suction valves 59.0 sq. in. 
 
 Area of discharge valves 47-74 ,, ,, 
 
 Number of revolutions per minute 25 
 
 Velocity of the piston per second 4.37 ft. 
 
 Theoretical volume generated by the compression piston 
 
 at each stroke 13.5 cub. ft. 
 
 Which gives for each revolution of the two compressors... 54.0 ,, 
 And for the two compressors, running at a velocity of 25 
 
 revolutions per minute 1350 a 
 
 This reduced to a pressure of three atmospheres will equal a 
 
 theoretical volume of 450 
 
 In practice the actual volume will not amount to more than 
 
 90 per cent, of the theoretical 405 
 
SYSTEMS OF WORKING. 
 
 Under this heading, reference is made to the working of open- 
 -works, lodes, stratified, deposits like coal, and irregular deposits. 
 
 OPENWORKS. 
 
 Openworks include ordinary quarries for building-stone, slate 
 quarries, the working of alluvial deposits for tin and gold, stockworks, 
 ^alluvial deposits worked by hydraulic mining, c. 
 
 Among the preliminary questions to be entered into before 
 opening a quarry are, I the nature of the material, 2 the quantity of 
 material, 3 the nature of the concession, 4 the cost of raising, 5 the 
 cost of transport. 
 
 Amongst other matters determine the existence or non-existence 
 of faults. Is there room for rubbish ? If a slate quarry, does the slate 
 decay ? Is there water power ? Observe the natural joints, posts, &c. 
 Does the slate split well ? Are the slates thick or thin, smooth or 
 rough? Are there bends, cramps &c. ? What is the colour of the 
 slate ? Is there much pyrites ? 
 
 The first work usually consists in the removal of overburden^ tirr, 
 callow or cover. When removing waste it is contracted for by quantity. 
 Vegetable soil may be removed carefully so that when the operations 
 of quarrying are completed it may be replaced. A clay may be used 
 for brickmaking. Sometimes, as in slate quarries, a large quantity of 
 decomposed slate has to be moved. 
 
 All this material should be removed so that it will not interfere 
 with the development of the works. 
 
 In attacking a deposit consider, I. The direction of natural 
 cleavages (backs and attters.} It is usual to advance at right angles to 
 the backs. 2. The direction of strike. It is usual to advance at right 
 angles to the direction of strike. 3. The direction of dip. If rocks dip 
 steeply towards you, the face of a quarry may be in danger of sliding 
 in upon the works. In such a case a low face is safer than a high 
 one. If rocks dip away from you, water may accumulate in the working 
 
84 
 
 face and further, it is more difficult for workmen to extract a block of" 
 stone as compared with the difficulty they experience when the rocks 
 dip towards them. 4. The general contour of the ground. By working 
 up a valley or a river bed, the working face keeps dry by the water 
 draining away from the same. 
 
 Lay out a quarry or openwork in steps, slopes or galleries. In some- 
 quarries the face of each stope may be a particular bed, so that ma- 
 terials of different qualities may be worked separately. 
 
 S!at< <iu;irri<>M. Tn opening a slate quarry on a hill side 
 in galleries, let each bargain be 10 yards long. Galleries 40 yards 
 long will therefore give 4 bargains. The perpendicular face of a- 
 gallery may be 15 yards and its length not less than 20 yards. 
 
 Small veins say 25-40 yards thick, worked as underground quarries 
 in Wales, yield the greatest proportion of good slate. 
 
 Underground quarries are however more expensive to work. 
 Lights are needed, men cannot distinguish good slate from bad, they are 
 delayed by smoke from blasts, there is danger from falls &c. Beneath 
 a level country engine power is required. 
 
 The most favourable position to work is where the cleavage is 
 parallel to the strike, and at right angles to the beds, and the beds dip 
 gently towards you. 
 
 To work a bed of slate dipping under a hill from its side, drive 
 an adit from the face of the hill to intersect the slate bed on its under 
 side, and pass through it to its upper side. After this precede to stope 
 in horizontal slices across the bed. 
 
 If a bed of slate lies beneath level country, sink a shaft on the dip 
 side, drive an air adit along the roof of the bed to meet an air shaft 
 sunk on the rise side, and then work from the bottom of the first shaft 
 with underhand stopes towards the air shaft. A deposit of this des- 
 cription might also be worked as an open quarry. (See Davies* "Slate 
 Quarrying"). 
 
 At the Penrhyn slate quarries there are 16 stopes or stages, each 
 about 40 feet in height. They are connected by inclined planes; 3,500- 
 men are employed, and in 1872, 250,000 tons of slate were raised. 
 Stopes may be 20 yards broad and from 40 to 60 feet in height. When 
 working horizontally stratified rocks beneath a level country, sink a 
 shaft and as it increases in depth lay off stopes. Each of these stopes 
 
85 
 
 will advance in a horizontal direction. An inclined wire tramroad will 
 pick up materials from each stage. 
 
 The chalk near Paris is worked with chambers and pillars; the 
 lower chambers being smaller than those above. 
 
 Slates of Cambrian and Silurian age are found in Wales, the Isle 
 of Man, \Vicklow, France, Canada, the United Stales, Moravia, Silesia. 
 Devonian slates are found in Cornwall, France, Luxemburg. In 
 Devonshire we have Carboniferous slates and in Italy slates of 
 Liassic age. 
 
 Irregularities met with in slate quarries are posts or hard bands, 
 bends, ctirls, dykes, veins of quartz, hardened ash beds,joznts. 
 
 Usually there is from 10 to 20 tons of rubbish to one ton of slate. 
 In addition to this there may be a large quantity of top rock to be re- 
 moved at the commencement. 
 
 Examples of Openworks. Most stone quarries, slate quar- 
 ries like those in Wales, stockworks (massive rock traversed by a net- 
 work of small veins) like those of Altenberg, Geyer, Zinnwald, and 
 Carclaze in Cornwall. Magnetite deposits of Niji Tagil in Russia. 
 The diamond mines in S. Africa. The Kimberly mine has a face of 
 500 feet, but there is also much drifting. At the Bischoff tin mine in 
 Tasmania, there is a face about 100 feet in height. Alluvial deposits 
 of gold in Siberia, Australia and California. 
 
 When a deposit is worked as an openwork there is a saving in 
 the price of getting, timbering, stowing and lighting. Further, all the 
 material is extracted. Gallon reckons the saving in excavating coal at 
 27d. per ton or 27X^ = 2o#d. per cubic yard. 
 
 This sum must be calculated for any given seam, and before decid- 
 ing to work by removing overburden, the result must be compared 
 with the cost of excavating from the surface. 
 
 The disadvantages of openworks are the destruction of the surface 
 and the expense of removing the overburden. 
 
 Monoliths. One of the largest blocks of stone excavated by the 
 Egyptians is 99 feet long. 
 
 Cleopatra's needle, now in London, is a piece of syenite 64 feet 
 long and 8 feet square at the base. IJlCQbelfisk of Luxor, now in 
 Paris, is 79 feet high and 8 feet squar/fjiffc base'. p n > 4 / S> x 
 
 f ^ ' ot THE 'r^ 
 
 UNIVERSITY 
 
86 
 
 Alexander's column in St. Petersberg is 84 feet long. When 
 excavated it was 102 feet long and 14 feet square at the base. 
 
 Monoliths like those met with in Egypt may have been obtained 
 "by first uncovering two faces of the rock and then adopting one of the 
 three following processes. 
 
 1. By simultaneously striking a number of wedges inserted along 
 
 a line parallel to a vertical free face. 
 
 2. By cutting a groove on the horizontal free face parallel to its 
 
 length. Covering this with fire to heat and expand the 
 rock, and then causing sudden contraction to take place 
 by the application of water. 
 
 3. By driving plugs of wood into holes along a line parallel to 
 
 the length of the block, and then causing the same to expand 
 by the application ot water. 
 
 In Siberia when simply breaking down rock, advantage is taken 
 of the intense cold during winter, when fires are lighted against the 
 working faces which by subsequent contraction during cooling are 
 split and fractured. 
 
 HYDRAULIC OK PLACER 
 
 In Nevada County, California, the writer saw deposits which were 
 upon the face from 100 to 300 feet in height. They consisted of 
 gravels, sometimes cemented to form a hard mass, tuffs and clays. 
 When deposits are strongly cemented a tunnel is driven a distance 
 two-thirds of the height of the bank to be blasted and terminated by 
 cross drifts. At the end of the cross drifts from 100 to 1,000 kegs of 
 powder may be placed (i keg = 25 Ibs.) and then exploded. From 10 
 to 20 Ibs. of powder are required per 1,000 cubic feet ground. The 
 talus thus formed is washed away by jets of water. 
 
 Dams, Flumes, Pipes. The water supply is contained in dams. 
 Earthen dams ought not to be less than JO feet thick at the top and if 
 over 60 feet in height they are dangerous. Wooden dams may be 
 built of a series of cribs each about IO feet square the face of the dam 
 being made tight with a skin of planks. Dry rubble stone work faced 
 
87 
 
 with planks is also used for dams. From the dams the water is 
 conveyed in open ditches and wooden flumes. Because the latter are 
 smaller than the former, they have a steeper grade. 
 
 Ordinary flumes made of 2j^ inch planks, may be 3 feet 10 inches 
 broad and I foot 10 inches deep. Some flumes have dimensions I foot 
 by 4 feet. The grade is usually about 30 teet per mile. 
 
 In a commanding position above the claim a pressure box built of 
 1% inch planks is placed, from which the water is conveyed in iron 
 pipes down to the claim. These pipes may be from 8 to 40 inches in 
 diameter and may have to stand a pressure of 400 feet. 
 
 Branch pipes may be made of crinoline hose which will bear 180 
 feet of water, From the end of these the water is allowed to escape 
 through a nozzle from 3 to II inches in diameter. The pressure is from 
 100 to 200 Ibs. on the square inch. The material washed away passes 
 along trenches lined with boulders and blocks of wood about I foot 
 6 inches square, with a space between each of 2 inches. It is here 
 that the gold is collected. 
 
 The water, is supplied by companies (Ditch companies) at a 
 certain rate per miner's inch. A miner's inch is the quantity of water 
 which will escape though a hole I inch square in a 2 inch plank under 
 a head of 6 inches over the opening, in 10 hours. The miner's inch 
 however, varies in different localities. The definition here given is- 
 however the most usual. The discharge of the miner's inch per hour 
 is 94.404 cubic feet. The cost of working is 2 to 4 cents per ton. 
 Under favourable circumstances gravels containing 3 cents worth of 
 gold per cubic yard will yield a profit. 
 
 When working in an excavation on a flat country it is found that 
 the debris and water from the face can be raised to the ditches on the 
 general level by a heavy jet of water shooting up an inclined pipe. 
 
 The method of working destroys the surface of a country, silts up 
 rivers resulting in floods, interferes with harbours, and creates other 
 damage. In 1871 in California there were 516 ditches bringing water, 
 having a length of 4,800 miles. 
 
 One company with 10 men at i6/- per day and 4,000 gals: of water 
 worked 224,000 cubic feet of gravel in 6 days. The gold obtained was 
 valued at 600. The profits at ^"470. Another company with 40,000 
 gals : of water in loo days washed 1,000,000 cubic yards and obtained 
 ^"6,400 worth of gold. Profit ^"2,400. 
 
88 
 
 For more complete details see Bowie's " Treatise on Hydraulic 
 Mining" 
 
 WORKIXtt I.OI>i:s. 
 
 Before opening a metal mine it is well to consider the follow- 
 ing points. 
 
 The nature and quantity of the material to be extracted ; the 
 general form of the deposit ; the depth at which you may have to 
 work ; the nature of the boundaries (roof, floor, walls] the thickness of 
 >the deposit ; its hardness and physical structure ; the existence or non- 
 existence of faults ; the quantity of water which may be met with c. 
 
 To work economically, if possible arrange the works so that 
 'the underground transport shall be short, the slopes clear of water, 
 and so that there shall be good ventilation, and the men not crowded. 
 
 In ordinary lodes, half or three quarters of the men employed under- 
 ground may be engaged in exploratory work (dead or tut work.) 
 
 Working- Lodes of Ordinary Width. Ordinary lodes which 
 are from 2 feet to 6 feet wide, are worked either by overhand or 
 underhand sloping. 
 
 In Cornwall the price of stoping varies from 2/6 to 6/- per ton. 
 
 1. Overhand Stopinur. It is better to commence from a 
 winze than by breaking in. Tools and materials can be easily lowered 
 down a winze, and the winze also acts as a passage for air. A fair 
 height for a stope is 6 or 7 feet. A high face allows the material to 
 come down in blocks, but the stage necessary for the workmen in such 
 a case has to be removed before firing a shot. The length of a face 
 may be from 20 to 40 feet. When the slopes are small the men may be 
 inconveniently near to each other when a shot is fired. The workmen 
 advance quickly if the joints in the rock dip towards them. 
 
 A pass is formed by the walls, stemples and attle, or it may be 
 timbered like a winze. The bottom of the pass ought to be larger than 
 the top to prevent jamming. In a 90 feet pass the top may be 3 feet 
 square and the bottom 4 feet 6 inches square. The limiting inclination 
 is about 50. 
 
 The advantages of overhand stoping are, I. The ground breaks 
 readily. 2. The ore is thrown down a pass. 3. The water drains 
 
89 
 
 away. 4. The ventilation is good. 5. There is less timber em- 
 ployed as compared with underhand sloping, unless there are not 
 enough deads to fill in with. 
 
 The disadvantages are. I. The dead work of driving a level 
 beneath the deposit. 2. The danger to the workmen. 3. The loss 
 of ore amongst the attle. 4. The inconvenient position in which 
 the men work. 
 
 2. Underhand S topi tit? . The floor and face of a stope 
 ought to dip downwards. The height of the face may be 6 or 10 feet 
 and the floor 25 to 40 feet. The advantages of this method are, I. 
 The work may be commenced without previous dead work. 2. There 
 is little risk of accident. 3. The workmen may use heavy double 
 handed tools. 4. There is little loss of ore. 
 
 The disadvantages are, I. The passing up of the ore. 2. The 
 risk of water accumulating. 3. The quantity of timber required. 
 4. The difficulty of ventilation. 
 
 These latter objections hardly apply if the usual system is fol- 
 lowed of putting down a winze and bottom-stopping into it. 
 
 Narrow Ijodos. In working narrow veins a strip of the wall 
 may be first removed and then the vein broken down unmixed with 
 wall rock (stripping)^ otherwise they are worked by the ordinary 
 methods of sloping. 
 
 Working Wide Lodes. Wide lodes are lodes where the ma- 
 terial of the lode is too weak to stand as a roof without support.' 
 Generally any lode over 8 or 10 feet will fall within this calegory. 
 
 I. By Horizontal Slices. A level is driven along the foot- 
 wall and at intervals of say 18 feet, levels or cross cuts are driven 
 across the lode to the hanging wall. By driving these levels, a certain 
 quantily of material is obtained from the lode. The cross cuts are 
 then packed with attle, and a second set of new cross cuts are started 
 inside the pillars: These being packed, a third set of cross cuts (each 
 cross cut being 6 feet in width j will complete the extraction of a 
 horizontal slice taken out transversely or across the lode from the 
 footwall to the hanging wall. A second slice is then taken out at a 
 higher level and so the work proceeds slice by slice working upwards. 
 
 If it is not desirable to come in contact with the stowing, a thin 
 slice of the vein may be left as a floor between two successive slices. 
 
90 
 
 When taking out slices in a descending order, the works in the 
 upper slice should be in advance of those below. 
 
 2. By Vertical Slices. At Almaden in Spain, slices are taken 
 vertically from level to level, the walls being supported by masonry. 
 
 3. Working by Pillars. This method is adopted where stowage 
 is difficult to obtain. The slices, which are much thicker than in 
 the previous method, are removed in descending order. Cross-cuts 
 are driven from a main level in the hanging wall side, and possibly 
 also another set of levels at right angles, so that a slice is divided up 
 into a number of pillars. The pillars and portion of the roof are then 
 cut away until the roof commences to fall, these operations commencing 
 in the part of the mine furthest removed from the shaft. After this a 
 second slice is commenced at a lower level, leaving a sufficiently strong 
 roof between it and the crushed-in workings above. When working 
 several slices simultaneously, the stripping of pillars, in a lower level 
 must not be commenced until the upper level has been completely 
 worked. 
 
 Examples of the cross-cut method with pillars are found at the 
 Stahlberg Iron Mines, the calamine workings in Silesia, the alum 
 shales at Liege &c. 
 
 WOKKIXtt R01 >I> HORSES OR IRREGULAR 
 DEPOSITS. 
 
 If the deposit is large, drive round it a horizontal contour level. 
 This may be used as a main level from which cross cuts may be driven 
 and the deposit worked out by the method of horizontal slices. The 
 pillar method may also be employed. When material is extracted by 
 a series of chambers the pillars of a lower tier are made larger than 
 those of a tier at a higher level. At Musen near Siegen the vaults 
 are i8ft. high and the pillars between are 1 2ft. thick. Only one-third 
 of the material (iron carbonate) is obtained from each level. 
 
 At the salt mines of Salzburg the salt is obtained by dissolving it 
 out of chambers. 
 
91 
 WORKING STRATIFIED DEPOSITS. 
 
 As a typical example of a stratified deposit we will take coal. 
 The more ordinary conditions which may affect the method chosen to 
 work a given seam of coal are the following. 
 
 1. The thickness af the seam. 
 
 2. The dip of the seam. 
 
 3. The nature of the floor and roof. 
 
 4. The depth of the seam from the surface. 
 
 5. The chemical and physical nature of the coal. 
 
 6. The natural cleavage or cleat of the coal (backs and cutters.} 
 
 7. The presence or absence of water. 
 
 8. The vicinity of other seams or workings which should not be 
 
 interfered with. 
 
 9. The position of the seam with regard to rivers, roads, canals, 
 
 towns &c. 
 
 Before commencing work, many commercial questions as to the 
 price of labour, the means of transport, facilities for sale &c. must be 
 answered. 
 
 The following classification of systems of working is modified 
 from a table given by O. J. Heinrich. (Trans. A. T. It, E. Vol. II. 
 p. 107). 
 
 I. For Seams of 1O Feet or less. 
 
 1. Dip from 45 to horizontal. 
 
 a. Pillar and stall, post and stall, stoop and room, pillar and 
 
 chamber (Exploitation pas serres hautes el courtes. Kur- 
 zer and langer Pfeilerbatt ; Felderbati). 
 
 b. Long wall system (Exploitation par failles grandes, drcites 
 
 et cauchantes ; Strebbau mit Breitem Blick ; Stossbau; 
 Diagonaler Pfeilerbau}. 
 
 2. Dip from 45 to vertical. 
 
 a. Overhand sloping (Exploitation par tailles a gradins ren~ 
 verses ; Firstenbau). 
 
92 
 
 b. Working by longitudinal pillars (Exploitation par serres 
 longitndinales ; StreicJiender Pfeilerbati). 
 
 II. For S<'amM over 1O Feet Thick. 
 
 1. Dip from 45 to horizontal. 
 
 Post and stalls with or without stowages (gobbing) (Ex- 
 ploitation par serres a methode par retnblais ; Pfeiler und 
 Feldtrbau mi oder ohne Bergversatz). 
 
 2. Dip from 45 to vertical. 
 
 By crosscuts or benches and stowage ( Ouvrage a travers 
 et par reuiblais ; Querbau mit Bergversatz). 
 
 All these methods are variations of the post and stall method, the 
 long wall method, or of the methods described as applicable to the 
 working of lodes which may be regarded as inclined seams. In the 
 following description of methods, the above classification is not strictly 
 followed. 
 
 . Post and Stall Method. Usually a shaft is sunk on the 
 deepest side (dip side) of the area to be worked, in a central position 
 on that side. 
 
 Two or more levels (say 10 feet wide) are driven parallel to 
 the strike (dip head level, lodgment level or water way) slightly 
 inclined towards the shaft. The lower of these is used to convey 
 water to the sump, while the others are employed for haulage or as a 
 level from which the stalls or bords are laid out when working 
 (winning) the coal. These are usually laid out, so that they advance 
 in a direction at right angles to the cleat or cleavage, such a direction 
 being known as " on the face or bordways" The direction at right 
 .angles to this is known as " on the ends." 
 
 Occasionally circumstances (as for example a steep dip) demand 
 that the boards shall advance obliquely to the cleat or even parallel 
 to it, that is on the ends. 
 
 When there is only one direction of cleat, the coal has a tendency 
 to break into prismatic forms. If there are two sets of cleavage at 
 right angles (backs and cutters) the coal will be cuboidal if oblique, 
 rhomboidal &c If advancing at right angles to well defined backs, 
 the coal will come away with ease, but in consequence of the under 
 -Cutting and falling, so many additional fissures may be produced, that 
 
9J 
 
 two much stnaffs or dust coal may be produced. In such a case,- 
 advance the bords in some direction oblique to the backs or even on 
 end. 
 
 The winning headway from which bords are driven may therefore 
 be parallel to the strike, the dip, or in some intermediate direction. 
 At least two bordways which are as wide as the roof will stand 
 without support (10 to 15 feet) are driven together. After advancing 
 a certain distance the working faces are joined by a passage or thirling, 
 parallel to the winning headway. The bords are then advanced, a 
 second thirling driven and the first thirling may be temporarilly 
 stopped. The ventilating current now passes round the working faces 
 through the second thirling. 
 
 By a system of bords and thirl ings at right angles to each other 
 the area to be worked, is cut up into a series of pillars. 
 
 If these pillars are made too small they become crushed and cannot 
 be subsequently removed, and more than half of the whole seam may 
 be destroyed. 
 
 In getting iron ore in headings, the cost is I/- to 2/6 per ton- 
 while when robbing the pillars it is 9 d. to 1/6 per ton. 
 
 Dimension* of li liars. -The dimensions of pillars depend 
 upon the strength of the roof, the floor, and the coal, the depth below 
 the surface, and the length of time they have to stand. Thus with a 
 softyftwor sole or with soft coal, large pillars are required. Hyslop 
 gives the following table : 
 
 PROPORTION OF PILLARS, 
 
 DEPTH IN FATHOMS. SIZE OF PILLARS IN YARDS. TO BORDS. 
 
 20 20 X 5 41 
 
 40 20 X 6 -SO 
 
 60 22 X 7 .52 
 
 80 22 X 8 .57 
 
 100 22 X 9 !, < .59 
 
 I2O 22 X 12 .6l 
 
 140 26 x 13 .63 
 160 26 X 16 .66 
 
 200 28 x 16 .71 
 
 200 30 X 21 .77 
 
 300 30 x 24 .79 
 
94 
 
 An average size is 12x40 yards. With long pillars the propor- 
 tion of length to width is 4 : I to 3 : 2. If pillars are too long there is 
 a difficulty in ventilation. When a pillar is too small or too weak to 
 support the superincumbent strata, it gives way by cracking and 
 crumbling. This is called thrust. "Sits" are falls of the roof. When 
 the pillar is small and the floor is soft, the downward pressure causes 
 the floor to rise. This is called creep. When creep once sets in, it 
 has a tendency to spread and the expense of repairing roadways and 
 keeping airways open, may be very great. 
 
 Near the shaft, large pillars at least 40 yards square are left to 
 support the shaft. This may be sufficient for a depth of 100 yards. 
 For each increase of 20 yards in depth the sectional area of the shaft 
 pillars may be increased 5 square yards. 
 
 Between main roadways and areas which are being worked, a 
 strong barrier of coal is left to protect such roadways. 
 
 An area may be worked as follows : 
 
 1. As a whole, commencing in the vicinity of the shaft and 
 working outwards or awav from home until the limits of the area are 
 reached. After this the pillars are removed (robbed] and the roof col- 
 lapses. The pillars first formed are therefore worked the last. 
 
 In this system many air ways and roadways have to be kept up 
 for many years and the risk of thrust and creep and other accidents is 
 increased. The pillars first formed have deteriorated by long exposure 
 to pressure and to the atmosphere. 
 
 2. By driving roadways to the limit of the area and working 
 towards the shaft ("towards home"}. In this way pillars may be 
 removed shortly after they have been formed. 
 
 3. By Mr. Buddie's system of dividing a district into pannels or 
 small areas separated from each other by strong barriers of coal, 
 each 40 to 60 yards wide. Each of these pannels is worked by its 
 own system of bords and pillars, has its own ventilation and is inde- 
 pendent of neighboring pannels. 
 
 4. By long block system. Long pillars maybe 1 20x60 yards. 
 Examples are the " Single Road" and ""Double Road Stall" systems 
 of S. Wales. 
 
 Getting- the i'oal. The first operation is to cut a groove in 
 
95 
 
 the coal at the bottom of the seam parallel to the floor, to a depth 
 of 2 / .6 / / or 3'. This is called holing, kirvwg or benching; and is per- 
 formed by hewers. The height of the groove at the entrance will be 9 
 to 12 inches. 
 
 Each hewer works a certain length called a stint. Small props 
 called sprags are used to prevent an unexpected fall of the undercut 
 coal. The next operation is shearing or the making of vertical cuts. 
 The last operation is the removal of the sprags and the forcing down 
 of the coal by wedges or blasting. This is getting the coal. Lastly 
 the coal is loaded in sleds or trains and taken to the nearest roadway 
 where putters take it to the bottom of the shaft. 
 
 b. r,ongr Wall Working. From a shaft sunk on the dip 
 side of the seam two roadways with a good wall of coal are driven 
 waterways. The face of the upper road is undercut along its length 
 and the coal is got. After a certain number of strips have in this way 
 been removed the roof beind the miners falls to form goaf. To prevent 
 the roof falling too near the working face, one, two or three lines of 
 props at from 3 to 9 feet apart are placed parallel to the working face. 
 After a strip of coal has been got the back row of props are removed 
 -and are reset in front of what was the front row. On the top of the 
 props a cap or iid 2 to 3 inches thick and one or two feet square may be 
 placed. Roadways or gob roads are built through the fallen roof or gab 
 to connect the working face with the main roadway leading to the shaft. 
 Along the sides of these roadways, pack walls are made of refuse stones 
 obtained from the coal or fallen roof. 
 
 Instead of having one long wall (working face) from loo to 500 
 yards long, a number of working faces (stalls) arranged in a step like 
 form and each about 50 yards in length may be used. Each of these 
 will have its gob road leading to a main roadway. Such a method 
 would be used in a steeply inclined seam. It is evident that instead of 
 having the working faces parallel to the strike, they may be in some 
 direction depending on the dip of the seam, the direction of cleat, &c. 
 In working homewards, gob roads have not to be built and much 
 expense is saved. There is however the preliminary expense of driving 
 roadways through the solid coal to the limit of the area to be worked. 
 
 The long wall method gives, according to Greenwell, about 14 % 
 more coal than the post and stall method. Coal cutters may be most 
 advantageously employed, there is little risk of danger, the ventilation 
 
9$ 
 
 is good, and the working ca>n be easily supervised. It is best applied" 
 to seams of moderate dimensions. 
 
 For thick seams this method requires long props which are 
 expensive and the gob roads are expensive. In all cases the work must 
 go on continuously and regularly. The system is interfered with by 
 faults. 
 
 Long wall has been used at Monkwearmouth at a depth of 1,800* 
 feet on a seam 6 feet thick. It is employed, in Staffordshire, Derby- 
 shire, Leicestershire, Somersetshire, &c. In Lancashire it was em- 
 ployed in 1812. At Zwickaw in Saxony they work homewards. Other 
 examples are in France, Westphalia, Japan, &c. In America hard 
 coal is sometimes worked by long wall, while soft coal is worked by 
 post and stall, one reason being that the smalls of soft coal can be better 
 utilized than the smalls of hard coal. 
 
 Effect of Subsidence. The removal of a seam 2 or 3 feet 
 thick will usually produce but little effect at 30 feet above it, but the 
 removal of a 20 or 30 feet seam may produce an effect at 100 feet. In 
 the case of 2 seams near to each other, it will usually be best to work 
 the upper one first. 
 
 In America two parallel seams have been worked simultaneously 
 by the post and stall method, the pillars in the lower set of workings- 
 being exactly below those in the upper set. To carry this out practic- 
 ally is a matter of some difficulty. 
 
 The subsidence on the surface follows the workings beneath but 
 at a distance back from them dependent on the depth of the workings, 
 the nature of the strata, the dip &c. R. Hausse gives the following 
 rule to determine the direction of the plane of fracture making an angle 
 6 with the horizontal plane, the dip of the strata being $. 
 
 I+COS2 
 
 tan 0=- 
 
 f cos ft 
 
 Gallon says subsidence causes fractures along the perimeter of 
 the area at right angles to the plane of stratification. 
 
 c. Seams which are steeply inclined. If a seam is 
 steeply inclined and the advance is towards the rise, then there is 
 danger of coal sliding from the working face down upon the men. 
 This may be partially obviated when working by a long wall method,. 
 
97 
 
 by making the working faces (s/atts) short and arranging them in a 
 ziz-zag line or by advancing in the direction of the strike by a system 
 of overhand stopes as in the north of France and Belgium. 
 
 The steeper the dip, the smaller are the stopes. Stopes are 
 usually about 6 feet high and 12 feet long. Inclined planes or passes 
 through the goaf carry the coal to a lower level. With a dip of 30 to 
 60 the stopes or step like stalls may be as much as 50 by 70 yards. 
 
 d. Tliiclt Seams (TJie Staffordshire Method]. Square work. 
 This method which is applied to the 10 yard seam at Dudley is a 
 form of post and stall. Narrow levels are driven at right angles, 
 dividing the coal up into blocks 50 to 70 yards square. Narrow holes 
 (bolt holes] 8 or 10 yards long are driven into these blocks, after which 
 the work goes on in stalls to the right and left until the block has been 
 hollowed out to form a chamber, the roof of which is supported by four 
 or more pillars. These which are 3 or 4 yards square and 12 yards apart 
 are called men of war. The men work upwards toward the roof in over- 
 hand stopes, standing on the broken coal or scaffoldings. The final 
 operation is to thin the pillars until the roof falls in, when the chamber 
 is abandoned and the bolt holes are closed. The method is dangerous 
 and the loss of coal is great say 50 per cent. 
 
 Some of the Pensylvanian anthracites are worked in chambers, but 
 by commencing at the top and using underhand stopes. 
 
 e. Working: " Slices {Blanzy]. Work off an upper slice say 
 6 feet thick of a thick seam by post and stall or by long wall and allow 
 the roof to settle. Next a second slice may be taken beneath the 
 broken roof, and so on until the seam has been completely won. 
 
 At Montceau les Mines, the seam was divided into 3 parts by two 
 partings each 3 m. thick the coal between being 1.5 m. The upper 
 layer was worked with pillars (12 m. in direction of strike and 25 m. 
 in direction of dip). These were cut away until they were 4 m.x 5 m. 
 when the roof crushed. Two years later the lower layer was worked. 
 
 In some mines it has been found that it does not require a great 
 interval of time for the broken roof to consolidate, so that several slices 
 may be practically worked together, providing that the upper workings 
 are kept in advance of those below. 
 
 If packing is employed, a seam may be worked in slices taken in 
 ascending order. In this way gob roads are under foot instead of over- 
 
9 8 
 
 head. In this case the coal settling on the packing may be much 
 fissured, and the risks of spontaneous combustion are increased. 
 
 If a seam does not exceed 15 or 16 feet, it may be worked by 
 overhand slopes, props being used to support the roof and the faces 
 of the stopes. 
 
 If a seam is thick and has a steep inclination, it can be worked 
 by a system of cross cuts with stowage, taking transverse slices in an 
 ascending order. The galleries may be driven in the wall. (See 
 method of working wide lodes.) 
 
 As Dombrowa Poland, seams 52 to 59 ft. thick, and inclined at 15 
 to 40 are worked by cross-cuts in descending order, a layer of coal 
 being left between each slice. In Upper Silesia seams 33 ft. thick are 
 worked in long blocks paralled to the strike. At Kladno in Bohemia 
 the workings are somewhat similar to those in Silesia, but here they 
 bring down 20 or 30 ft. of coal at one fall. 
 
 Cost of Breaking 1 Ground (Agendas Dimod). For driving 
 a level 3.50 in. square section (2 m. high with a circular crown and 
 2 m. broad), miner's wages 4 francs per day, powder 2.50 francs per 
 kilogramme, 2 shifts per day and 25 working days per month. See 
 the following table. 
 
 NATURE 
 
 OF 
 
 ROCKS. 
 
 No. of 
 days per 
 running 
 meter. 
 
 Powder 
 con- 
 sumed. 
 
 PRICE. 
 
 Monthly 
 advances. 
 
 Per running 
 meter. 
 
 Per cubic 
 meter. 
 
 Exceptionally 
 
 
 Kilos. 
 
 Francs. 
 
 Francs. 
 
 Meters. 
 
 hard rocks 
 
 So 
 
 12 
 
 236 
 
 67 
 
 2 
 
 Hard granite and 
 
 
 
 
 
 
 quartzoze rocks. 
 
 20 to 30 
 
 8 to 10 
 
 120 tO 145 
 
 34 to 41 
 
 3-33 to 5 
 
 Hard veins and 
 
 
 
 
 
 
 very quartzoze.. 
 
 24 
 
 3-5 
 
 I4 -75 
 
 3 
 
 4 
 
 Hard coal mea- 
 
 
 
 
 
 
 sures, grits &c. 
 Moderately hard 
 
 15 tO 20 
 
 4 to 8 
 
 70 to ioo 
 
 20 to 28.50 
 
 5 to 6.87 
 
 coal measures 
 
 
 
 
 
 
 ordinary granite 
 Ordinary coal mea- 
 
 10 to 15 
 
 3 to 4 
 
 40.50 to 70 
 
 13 50 tO 20 
 
 6.67 to 10 
 
 sures, soft argil- 
 
 
 
 
 
 
 laceous or mica- 
 
 
 
 
 
 
 ceous schists 
 
 7 to 10 
 
 1.5103 
 
 31.751047.50 
 
 9 to 13.50 
 
 10 to 14 
 
 Soft coal measures 
 
 4 to 6 
 
 i to 1.5 
 
 18.501027.75 
 
 5.20 to 8 
 
 15 to 25 
 
 Coal 6m. sq. in 
 
 
 
 
 
 
 section 
 
 2 to 4 
 
 o.o to .3 
 
 8 to 16.75 
 
 1.33 to 2.80 
 
 25 1050 
 
99 
 
 In Cornwall the cost of sinking per cubic fathom is given by 
 Collins as follows : 
 
 NEAR SURFACE. BELOW 20 FKM. 
 
 In soft killas or clay . 2 to ; 3 3 to ; 4 
 
 In compact killas or pick & gad ground 4 to 6 5 to % 
 
 In fair blasting ground 6 to 20 10 to 30 
 
 For driving levels; */j cheaper for non-blasting, and % cheaper for 
 blasting ground. As Bottalack the cost of driving levels 3 / x6 / per 
 running fathom is from 4 to 6. 
 
 In the Polberro mine the cost per fathom was for shafts, ^4.12. for 
 driving in the lode ^"6.8.6 and for sloping 2.2. 
 
 For a level 7' high, 3 / .6 // in the cap, 4/.6'' at the bottom with 
 half timber sets and i^' inch laths, the cost of driving per fathom will 
 be about 2.10 to ^3 and for timbering i.$ to ^i.io (Collins). 
 
 The following numbers give the relative cost of different kinds of 
 work, sloping openworks being taken us the unit. 
 
 Driving small levels 4 Stoping underground 2.6-3 
 
 Large sections i% ,, moderate vein 2 
 
 Vertical rising 6 ,, thick vein 1/^-2 
 
 Shaft sinking 6-8 
 
 In England under fair conditions, two men and a boy in a shift 
 of 8 hours, may extract 8 to 10 tons of coal. Hewing and falling may 
 cost 8d. to rod. per ton, but including proping, cogging and stowing 
 1/6. per ton for large, and 6d. per ton for smalls. (See cost of sink- 
 ing p. 108.) 
 
 Waste of Coal by Weathering 1 . The weathering of coal 
 greatly depends on the absorbtion on oxygen forming CO*., HoO. and 
 upon the presence of Iron Pyrites (Marcasite). By weathering, the 
 heating power may be diminished 6 / or more, and the coking power 
 2 to 5 %. The volatile matter in coal rapidly diminishes by exposure. 
 Pyrites decomposes rapidly in a damp place. Coals without pyrites 
 may decompose more rapidly in a dry place. 
 
 Fires in Coal Mines. Some coal mines have continued burning 
 for 50 and some even more than 100 years. 
 
 Fires are occasioned by carelessness. Timber near underground 
 boilers has taken fire. The material in stables has been accidently 
 
100 
 
 fired. Ventilating furnaces have not been carefully protected. Coal 
 dust in suspension in the air may be exploded by a flame and a fire 
 result &c. 
 
 A common cause is spontaneous combustion, which may originate 
 in the coal or in a heap of waste material like greasy cotton. 
 
 Coals with a large percentage of oxygen are liable to spontaneous 
 combustion. Burat says that poor coals giving a longvflame are subject 
 to spontaneous combustion. 
 
 In many coals hydrocarbons like CH 4 . are formed (see Ventilation). 
 By a fall in atmospheric pressure or by a fall of the roof a large 
 quantity of these gases may be forced into a level and coming in 
 contact' with a light, the result is an explosion and fire. 
 
 If the pillars of a mine are too small, they are cracked and fissured 
 and the surfaces for oxidation are increased. The decomposition ' 
 of Iron Pyrites also tends to crack the coal and in this way assists the 
 oxidation. The result of oxidation is that a pillar may become hotter 
 and hotter until fire is produced. 
 
 Preventing Fires. Careful inspection. Walling off places 
 where gases accumulate. Burying places which are burning, with sand. 
 A small quantity of water producing dampness, may increase the 
 chemical changes which are producing heat. Keep the workings clear 
 of small coal. Good ventilation sometimes may cool a place, while at 
 other times it may accelerate oxidation. 
 
 Extinguishing Fires. Certain American mines have a water 
 supply through the main levels under the pressure of a main in the 
 shaft. By a hose which may be screwed on these pipes, a jet of water 
 may be quickly turned upon a fire in any portion of the mine. 
 
 Portable Extincteurs giving a jet of CO?., and water, have some- 
 times been useful. 
 
 Fires have often .been extinguished by damming so that no fresh 
 air can gain excess. 
 
 To approach a fire, run a central brattice along a level, along one 
 side of which the smoke escapes, while a current of air is sent in upon 
 the other side. 
 
 The ordinary plan is to drown the mine with water (which may 
 partially destroy the timbering, cause falls &c.,) steam, or carbon 
 dioxide. 
 
101 
 
 Carbon dioxide was used successfully at Ruabon. 
 
 265 Ibs. of limestone and 580 Ibs. of ordinary hydrochloric acid 
 which may be mixed in a box lined with lead give 1,000 cubic feet 
 of gas. The same gas may be produced by burning coke or coal 
 together with limestone in a* specially arranged furnace. The resulting 
 gases (CO-2 and N) are forced into the mine by a jet of steam. 
 
 Officers and Workmen in Mines. 
 
 IN COLLIERIES. IN METAL MIXES. 
 Chief Viewer corresponds to Inspecting Captain or Manager. 
 Resident or CJnderviewer and ) f Chief Resident Captain, Sub- 
 Overman, j " " \ captain, Grass captain. 
 Deputy Overman. nearly Pitmen, Shaftmen. 
 
 Timbermen. 
 
 Tributers and Tutworkmen. 
 
 Trammers. 
 
 Fillers. 
 
 Landers. 
 
 Dressers. 
 
 Smiths, Carpenters. 
 
 Enginemen. 
 
 "W astemen. 
 
 Firemen. 
 
 Hewers, Getters. 
 
 Putters, Rolley drivers. 
 
 Onsetters, Hangers-on. 
 
 Doorkeepers, trappers. 
 
 Banksmen. 
 
 Screeners. 
 
 Smiths, Carpenters. 
 
 Enginemen. 
 
 In Tutwork, todtwork or dead ivcrk when driving levels, the price 
 paid is usually so much per fathom. 
 
 Tributers work an area called a pitch and receive a certain 
 percentage of the value of the ore extracted. If ore is rich say I/- in 
 the , but if poor I3/- in the . These contracts are usually let to 
 the lowest bidder. Each class of workmen has certain charges to 
 pay. Thus a tributer may pay J/6 per ton for drawing and crushing 
 the ore, 6d. per ton for dressing, 2/- for sampling, 8d. for weighing, 
 mending chisels id. each, mending 3 picks 2d. candles 8d. per lb, also 
 he pays for powder, fuse, doctors fund &c. (Collins). 
 
 As Himmelsfurst, Saxony, there were employed I surface captain, 
 I underground captain, 16 under captains, 362 miners and hewers, 54 
 timbermen and masons, 122 trammers, windlassmen and fillers, 171 
 dressers, 21 smiths, 3 enginemen, 2 watchmen and I clerk. Total 754. 
 
 At the Levant Mine, Cornwall. There are about 300 people 
 underground and 100 on the surface. 
 
Atlhe Bottalack Mine, there are about 190 underground, and 210, 
 including boys and girls, on the surface. 
 
 At the Whitehaven Colliery about 1,500 men and boys are 
 employed. 
 
 At the Ashio Copper Mine in Japan 4,000 workman are employed. 
 
SHAFTS. 
 
 Varieties of Shafts. Engine, ventilating, pumping, coaling, 
 upcast and downcast shafts. Blind shaft, winze, sump shaft, broken 
 shaft. 
 
 The Adalbert shaft at Prizbram 572 fms. The Viviers Reunis 
 coal mine at.Gilly near Charleroi is 581.5 fms. (the staple at the 
 bottom being \\y 2 fms.) In England the Ashton Moss Colliery near 
 Manchester is 475 fms. The Dolcoath tin mine is 404 fms. In 
 1886 the Comstock reached 3,250 feet. 
 
 Site of a Shaft. Place a shaft on level ground or in a valley 
 near the center of the works. Works however are usually located 
 to suit the shaft and not vice versa. A shaft should not be on swampy 
 ground or where it may be flooded. Shafts near the sea have been 
 lost by tidal waves. It ought not to be too near a building or too far 
 distant from a road or canal. It must be remembered that the 
 engineers require a water supply. 
 
 The mouth of a shaft should be 20 feet above the surrounding 
 level. This enables a bank or stage to be constructed from which the 
 material from the mine may be readily discharged. 
 
 Shafts are usually sunk from the surface but as in the case of long 
 adits, which to expedite the work maybe commenced at several points 
 along their length, a shaft may be sunk from the surface and from 
 several levels, the manner on which the different holings meet being 
 dependent in the accuracy of the mine survey (Ex. Konigin Marie 
 Shaft, Hartz Mts). 
 
 In coal seams, sink on the dip side of the bed and on the dip side 
 of an ordinary fault. With a reversed fault or where the seam dips 
 against the fault, it may be better to sink on the rise side. 
 
 A shaft may be vertical or inclined, in a lode, or outside in the 
 country rock. Its long side is placed parallel to the strike of vein. 
 Vertical shafts are usually sunk on the hanging wall or dip side of a 
 lode, to intersect the lode at about half the maximum depth of the 
 intended workings. This arrangement gives a minimum length for 
 
io 4 
 
 the cross cuts. Such a shaft does not explore the lode or help to pay 
 the expense of sinking. It is good for a quick out-put and saves 
 expense in winding, pumping and (for shafts of equal depth) in 
 timbering. 
 
 If a lode is nearly vertical, the shaft may be sunk entirely on the 
 foot wall side. There is less chance of dislocations taking place in 
 the walls of the shaft. A rectangular shaft ought to be sunk with its 
 long sides transverse to the cleavage or bedding of the rocks through 
 which it passes; this may prevent the sides from slabbing off. It is 
 assumed that the plane of bedding is nearly vertical. 
 
 An inclined shaft in a lode is usually cheaper to sink, and it may 
 be drier than a shaft in the country rock. While sinking, the lode is 
 explored and ore is won. If it is in the country rock it ought to be on 
 the foot wall side of the deposit. It is longer than a perpendicular, 
 shaft, and there may be more movement in its walls. For these reasons 
 more timber and other materials are required. Mechanical arrange- 
 ments may be complicated and wear and tear is increased. There 
 may be difficulties in opening parallel veins near such a shaft. 
 
 Form and Size of Shafts. Rectangular, square, polygonal, 
 elliptical or circular. 
 
 Rectangular shafts are common at metal mines ; the two long sides 
 being formed by the side of the lode, the two ends being portions 
 of the lode and forming shaft pillars. On the Comstock lode the end- 
 pieces are 5 to 6 feet, while the wall plates forming the long sides, are 
 from 20 to 24 feet. More ordinary dimensions are 4 feet to 10 feet by 
 9 feet to 1 6 feet. Rectangular shafts are convenient for dividing. 
 
 Square shafts are stronger than rectangular shafts and require less 
 material for a given sectional area. 
 
 Circular shafts are usual at nearly all coal mines, they are the, 
 strongest, most easily made water tight, give the largest area for a 
 given periphery, but they are not so convenient to divide. A common 
 diameter is 12 or 14 feet but for costening 4 feet may be sufficient. 
 
 Shaft Timbering?. Shafts in lodes sometimes only require 
 timbering on their shorter sides, the longer sides being the walls of the 
 lode. This timbering consisting of sets and laths is very similar to 
 that used for the roof of levels. 
 
Timbering a shaft 10 ft. by 7 ft. with sets and laths, the sets of 9 inch 
 timber 4 feet apart, the laths 1^ inch thick, costs about ^"3.10 per 
 fathom of depth (Collins). 
 
 Prop-crip Timbering;. On the surface a day frame with 
 bearing ends is placed. After excavating 8 or 9 feet, bearing stemples 
 are wedged across the shaft from the hanging to the foot wall. On 
 these a crib is laid, and on the crib 4 props which carry a second crib 
 and so on until the last props bear against the under side of the day 
 frame. Wedges are driven in between the cribs and the sides of the 
 shaft. The bearing stemples may bear and rest on blocks. The 
 distance apart of cribs may be 2 feet 6 inches to 4 feet. Lagging may 
 by used behind the cribs. 
 
 If the wall plates of cribs are liable to be bent, they may be 
 propped by cross bars, buntons or dividings, and to prevent cribs being 
 forced out of shape, inclined struts or stringing planks are used. 
 Stringing pieces may be notched against the cribs and held in position 
 by cross bars, or spiked, 
 
 When one frame or crib is placed upon another the lining forms 
 solid crib timbering. 
 
 Frames are kept apart by corner pieces, stiiddles or jogs. 
 
 Plank or Box Timbering;. This consists of planks 6 inches 
 or 8 inches deep and 2 inches to 4 inches thick, notched together to 
 form a box ; the ends of the sides of which may be left projecting. 
 
 These boxes are supported by their ends or on stemples, and they 
 are packed behind with attle or clay. This timbering is only suitable 
 for small shafts. 
 
 Circular shafts may be lined by planks bent to form hoops with 
 lagging behind or with wooden cribs built up in sections and propped 
 apart. These are lined on the inside with planks, on the inside of 
 these again lighter cribs may be placed. Where the pressure is great, 
 the cribs may be 9 inches X 7 inches. 
 
 In sinking, a depth may be reached equal to the length of the 
 lagging, say 9 feet. Here a crib is placed and the lagging placed 
 behind it. A second crib is then placed on props (punch props] at a 
 height of 3 feet in front of the lagging, ajid so on up to the surface. 
 The excavation now proceedsy^o^pn^ftHetf^^^j^t, parallel with the 
 
 . UNIVEKSITT 
 
io6 
 
 inside face of the crib first inserted, which may be supported by rods, 
 chains or stringing deals from the surface, by driving in bars beneath 
 it, by props from below, or by a portion of the earth or rock beneath 
 it, this being removed gradually. 
 
 Solid Crib Timbering-. Where pressure due to a head of 
 water has to be resisted, one solid crib is placed upon another. The 
 lowest in the series is usually a wedging curb or crib. The cross 
 section of the timber out of which it is built is greater than that of the 
 cribs it carries. Between it and the walls of the shaft there is a plank 
 sheathing which is forced back against a bed of moss by a series of 
 wedges the moss being between the sheathing and the walls. 
 
 Sinking- in Soft CSrouiid. In soft ground the method is 
 similar to spilling, yet to be described. By driving diverging spills the 
 section of the shaft remains constant (Dutch cribbing or framing]. If 
 the spills are driven vertically, the diameter of the shaft is decreased 
 at each length of timbering by an amount equal to twice the thickness 
 of the cribs and spills. 
 
 Another method, by which a short length of soft ground may be 
 passed when descending from the surface, is to make a large conical 
 excavation, timber or brick vertically upwards and then fill in. 
 
 Soft ground may be penetrated by sinking a lining or drum curb 
 formed by a succession of cribs or tubs provided with a cast iron shoe. 
 As the lining descends, being forced downwards by screw presses or 
 weights, its length is increased above and the shaft excavated. 
 
 A great difficulty is to keep the drum vertical, especially when 
 obstacles like boulders are met with. 
 
 For details and drawings relating to the above notes see "Mine 
 Timbering and Shaft Timbering" by J. Clark Jefferson, A.R.S.M.Wh.Sc. 
 Vols. VII and VIII. Chesterfield and Derbyshire Institute of Engineers. 
 
 Trig-er's Mvlliml. This method is applicable to depths of 80 
 or 100 feet. It consits in sinking a drum-headed cylinder of boiler 
 plates which being filled with compressed air prevents the access of 
 water. By means of an air-trap workmen can enter the cylinder and 
 carry on the work of excavation. It was first employed on the Loire, 
 and in a modified form it is now being used in Victoria, Australia. 
 The pressure of the atmosphere can not exceed four atmospheres 
 
without affecting the workmen, and thus the depth of descent, as in 
 diving, is limited. 
 
 Ciuibal's Method. This method consists in forcing downwards 
 a cylinder of wood or iron which has a diaphragm across its center 
 from the middle of which a large tube rises upwards. As the cylinder 
 descends, the water rises in the tube, and curbs are inserted on the 
 inside of the sliding cylinder. Obstacles are removed by tools which 
 are passed down the tube. 
 
 Kind and Cliaudron's Method. By means of large trepans 
 (boring tools) a shaft 4 or 5 feet in diameter is excavated, which is 
 enlarged hy other tools to 10 or 15 feet. After this a series of iron 
 cylinders are gradually sunk in the excavation and the hole lined. 
 The details of sinking the lining and rendering it water tight, are 
 important features in this system. It has been successfully employed 
 in several countries. The system necessitates considerable strength in 
 the sides of the shaft. 
 
 Since 1878, altogether 16 shafts have been sunk by this method 
 5 in Belgium, 3 in France, 7 in Germany, and I in England. 
 
 Poetschs' Method. On the area where the shaft is to be sunk, a 
 series of holes are put down and lined with copper tubes through which 
 a freezing mixture is caused to circulate until the ground has solidified, 
 after which the excavation can be carried on. The method is not 
 unlike that practiced by gold prospectors in Siberia, who reach the 
 bottom of a river by gradually cutting a pit through the ice and 
 allowing it to thicken beneath. After thickening, the excavation is 
 deepened. 
 
 In May 1891 at the Lens Collieries, the site for a shaft 137 feet 
 9 inches deep was being frozen by a solution of calcium chloride at 
 12 C being circulated through the lining of 28 bore holes. Altogether 
 to complete the freezing it was expected to take 120 days. 
 
 Iron Tubbing-. If tubbing is in complete rings as in the Kind 
 and Chaudron system, it is difficult to put in and difficult to repair. 
 It is therefore usually built up as a series of flanged plates, ^ inch 
 to 1% inch thick and from I to 3 feet square. Between the joints 
 y^ inch to ^ inch of sheathing is inserted. The "wedging ctirb at 
 the bottom is in the form of a hollow box. If the flanges of the plates 
 
io8 
 
 are on the inside they are convenient for the attachment of the shaft 
 fittings. As iron is liable to decomposition, especially in up-cast 
 shafts, it may be varnished or lined with brick or wood. Should any 
 fractures occur, they are unfortunately hidden by the lining. 
 
 Shaft linings, whether of iron, masonry or wood should be stronger 
 below than above. The thickness of the lining varies with the dtametelr 
 of the shaft and the height of the column of water to be supported. 
 
 If ^=the radius in meters of the circle inscribed on the exterior 
 of the polygon. 
 
 .//=the height of the column of water in meters then Pernolet 
 gives the following formula for the thickness of the tubbing. 
 
 E= thickness in meters. 
 
 H R 
 
 For wood -"= - - 
 1,200 
 
 For cast iron as used by Kind and Chaudron. 
 
 2O,OOO 
 
 For greater safety Chaudron takes. 
 H R 
 
 J5= -- j-0.020 
 
 500 ^ 
 
 For the thickness of cast iron tubbing Greenwood gives the follow- 
 ing formula. 
 
 X= required thickness in feet. 
 P vertical depth in feet. 
 D= diameter of pit in feet. 
 
 P D 
 
 5O,OOO 
 
 The thicknesses actually employed are usually determined from 
 experience. 
 
 ost of Sinking- (Agendas Dunod}. The average cost of sink- 
 ing a shaft 4 meters in diameter or 16 meters, square, per running 
 meter is approximately as follows. 
 
 1. Solid ground, no walling .................................... 350 to 400 francs. 
 
 2. ,, ,, with walling ................ . ................ 500 to 600 ,, 
 
109 
 
 Fissured ground, water in small quantity requiring 
 timbering but not pumping 900 to 1,200 
 
 Ground traversed by the Kind-Chaudron system 
 and lined with iron 2,30010 4,000 
 
 Watery ground requiring heavy pumps 2,000 to 24,000 
 
 srficial sand 
 
 Superficial sands not more than som. in thickness, 
 traversed by compressed air 
 
 4,000 to 8,000 
 
 Cost of Sinking in Coal Measures 
 
 Total labour cost of sinking and walling 
 
 Contractor for sinking and small stores 
 
 Making walling beds each 
 
 Walling with fire clay lumps 
 
 Tubbing with cast iron 
 
 Plank brattice 
 
 Guides of wood 
 
 Guides iron or steel (50 Ibs per yard) 
 
 Wire rope guides 
 
 Total cost of finished pit about 
 
 per fathom 25 
 
 90 
 
 2.10 
 O.I 5 
 2.10 
 
 i- 5 
 50.00 
 
 Cost of walling a pit 14 feet diam. with stone may be from ^15 to 
 20 per fathom. Metal tubbing will cost 50 to 60 per fathom 
 exclusive of fixing which may be 10 per fathom extra. Brick 
 lining may cost ]^ less than stone. (See cost of breaking ground p. 98). 
 
 Shaft Fittings. Where shafts approximate to a steeply in- 
 clined level, steps may be cut in the floor, or they may be boarded to 
 form a staircase. Near Salzburg men enter the mine by sitting on 
 wooden rails and sliding down the inclined shaft. They return by 
 steps. AVhen sinking, men descend in a kibble or on a cross stick. 
 In parts of Spain they descend by sitting with one leg in a loop, a 
 second loop passing round the chest. 
 
 Ladders. Ladders are chiefly used in metal mines. Men can as- 
 cend on stemples. Ordinary ladders consist of two cheek pieces usually 
 rectangular in section say 2 / ' X 4 // , in. by in. set 12 inches to 14 inches 
 apartby a series of staves. The staves are either rectangular or circular 
 in section and thickened in the middle, placed 10 inches apart. Iron 
 staves are trying to the hands and when worn become sharp, but they 
 last much better. An angle of 70 is a good inclination for a ladder. 
 When vertical the center of gravity of a man falls outside the ladder 
 and the strain on the muscles in lifting causes unhealthy fatigue. The 
 foot of each ladder rests on a stage, the upper end passing through a 
 man hole (soil a r) in an upper stage. Underground ladders do not 
 usually exceed 6 fms.; 2 and 3 frns. lengths are common. 
 
no 
 
 In shafts with the sets 4 ft. apart ladders may be usually about 
 16 ft. long the sollar being on every 3rd set. 
 
 Chain ladders are often used in sinking. They can be lengthened 
 as the sinking proceeds and they are not readily damaged while 
 blasting. 
 
 Ladders may be rased to depths of 100 or 200 fms. 
 
 Work done on Ladders. In a mine 200 fins, deep from 
 the bottom of 'which 300 miners each weighing 150 Ibs. ascend daily, 
 the work done in ascending is 2oox6x 3OOX I5o=54',ooo,ooo foot 
 Ibs. and in a year of 300 days the work is 16,200 X io c foot Ibs. 
 
 If a days' work is worth 4/ and a man accomplishes 1,000,000 
 foot Ibs. per day the value of the above work would be ^3,240 or 
 sufficient to pay for the employment of engine power, and thus enable 
 the miners to go and return from their work without fatigue. 
 
 Engine (Fahrkunst}. These were first employed at 
 Clausthall in 1839. They were independently invented and employed 
 in Cornwall in .1842. Collins says that a man engine was used at the 
 Tresavean Mine, Cornwall, in 1835. 
 
 A single man engine consists of a series of rods, like pump rods, 
 which slowly oscillate up and down the shaft. At intervals corres- 
 ponding to the length of stroke, steps are placed. At the end of each 
 stroke these steps are in front and near to a series of steps fixed on the 
 side of the shaft. In descending, a man steps on to the step on the 
 rod, and descends with it until opposite a fixed step on the side of the 
 shaft. Here he steps off upon the fixed step and waits until the rod 
 has moved upwards to bring the second step on the rods in front of his 
 position on to which he moves and descends to a second fixed step in 
 the shaft. 
 
 In a double acting man engine two rods move side by side but in 
 alternate directions. Each of these is provided with steps which come 
 opposite to each other at the end of each stroke. 
 
 By moving from a step on one rod to that on the other at the end 
 of each stroke a miner may ascend or descend. 
 
 Motion is given to the rods by a crank working a rocking beam. 
 By this means, although the crank has a continuous motion, at the 
 
I "1 
 
 dead points of revolution the motion of the rod is reduced to zero, and 
 the miner has time to move from step to step. 
 
 The balancing and the regularity of motion of two rods is secured 
 by I. Coupling the rocking beams together. 2. By a rack on each rod 
 working in a pinion placed between them. 3. By connecting the two 
 rods by a chain passing over a pulley fixed in the shaft. 4. By 
 plungers attached to the rods, each working in a chamber containing 
 water, the two chambers being connected. 
 
 The speed may be regulated by the rod raising a plunger which 
 as it rises sucks water in at a valve. As it descends, the water escapes 
 through an opening the size of which may be regulated. 
 
 For safety in case of accident catch pieces are placed at intervals 
 on the back of the rods which overhang or embrace bearers crossing 
 the shaft. If a breakage occurs the rods may either fall or in con- 
 sequence of the balance bobs fly upwards. The catch pieces coming 
 in contact with the bearers regulate the length of this motion. 
 
 Length of stroke 6-12 feet. The rods are 7 or 8 inches 
 square. Sometimes they are made of angle iron or iron rope. The 
 weight of the rods with all connections is about 25 cwt. per fathom and 
 the cost of a man engine with driving engine complete for 200 fms. is 
 about ^2,000 to ,2,500 (Collins}. For farther details see "Mining 
 Statistics West of the Rocky Mountains." Raymond and Blake. 
 
LEVELS. 
 
 Variety of Levels. Adit, Sough (Derbyshire) Gutter (Stafford- 
 shire). Shallow adits, deep adits. Drift, headway, cross cuts, cut 
 outs, branches, tunnels, roads, gates, rollyways, jig brow, durk drifts. 
 The end of a level is called the forebreast or end. 
 
 Dimensions of Levels. Levels for exploring or costeaning 
 may be 2.V 2 by 4 feet. Main levels are usually from 3 by 5 feet to 4^ 
 by 7 feet. In metal mines they are usually the width of the lode, 
 while in coal mines they are usually the height of the seam. The width 
 greatly depends upon the strength of the roof. A double road for two 
 lines of rails may be 4 or 5 yards broad. 
 
 In England a drift (6 feet X 9 feet) thought coal and soft 
 materials costs about 3o/- per fathom. (see p. 99.) 
 
 Adit or drainage levels may be 8 to 12 feet high and 5 to 8 feet 
 broad. In soft ground the gradient may be I in 200 (3/16 in. per yard) 
 and in hard ground I in 600 and even I in 1,000. 
 
 The County adit in Cornwall drains 30 square miles. It is 40 m. 
 long and 30 to 90 fms. deep. 
 
 The Beaumont adit is 6,567 yards long and 70 fms. deep, gradient 
 I in 660. 
 
 The Ernst. August adit, Clausthal, is 18 m. long (25,956 meters). 
 Greatest depth 222 fms. Sectional area 10 by 6 feet. Gradient I in 
 2,000. It took 13 years to make and cost ^85,500. 
 
 The Sutro Tunnel 4 miles long (Comstock Lode) is 10 by 12 feet 
 square and 2,000 feet deep. It was completed by 9 distinct holings. 
 
 To drive a long level quickly, work by means of shafts from 
 several points, increase the number of shifts, use machines, employ 
 picked men, and drive a narrow gallery ahead. 
 
 Position of Levels, Usually in a lode but if outside you get 
 an uninterrupted road. If partly on a foot wall you obtain a good 
 gutter for drainage but a bad roof. 
 
In lodes with slight dip, the levels are close when the distance 
 between them is measured vertically, if far apart, the expense of 
 putting in pumps may be great. In determining the distance apart, 
 consider the cost of driving, the cost of underground transport, 
 which is usually cheaper if there are many levels, the distribution 
 of the minerals, the method of working &c. In Cornwall levels were 
 usually 8 fms. apart, now they are lo and 15 fms. apart. In Saxony 
 20 to 40 fms. apart. 
 
 TimiM i i nx and Walling:. As to whether an excavation shall 
 be timbered or walled, depends upon the material and workmen in the 
 district, the length of time that the excavation is to remain open, &c. 
 Timber is put up more quickly, is cheaper, and occupies less space 
 than masonry. It accomodates itself to small movements. Masonry 
 is stronger and more durable than timberwork, but it can only be put 
 up slowly ; also it may crack. Levels are sometimes supported by 
 iron. Where old rails can be employed, it is cheap and can be erected 
 quickly. 
 
 Varieties of Wood. Leaf wood has a compact core but is soft 
 outside. Pine wood is soft throughout and contains turpentine. Pine 
 also has sap wood. 
 
 English Oak is durable under all circumstances. It may last 25 
 years or more. It is strong but occurs in short lengths. Beech and 
 Birch are strong but liable to red rot, and decompose in a stagnant 
 atmosphere. Acacia, resists decomposition ; tough and flexible. Ash, 
 may be bent ; used for handles, rungs of ladders. Elm, used for 
 frames and curved work. 
 
 Hard wood like oak and elm used for cribs, costs in England 3/- 
 to 4/- per cubic foot. 
 
 Pine decays in a bad atmosphere, but is light and cheap and 
 therefore much used. In England, Scotch Fir (Pinus Sylvestris) and: 
 Spruce (Abies conimunis} or red and white wood, is imported from. 
 Norway and Sweden. For pump spears, headstocks, pitch pine is 
 imported from America. In Cornwall, Norwegian pine delivered at 
 the mine costs about I/- per cubic foot. American pitch pine used 
 for pump spears costs 1/9 to 2/6 per foot. Larch is similar to pine 
 but containing more rosin is not so liable to rot. Fir is more brittle 
 than Pine and Larch, and more suitable for timbering in water. 
 
114 
 
 Wood is best cut in winter and barked to dry. It should be 
 stored in sheds where it will be dry and be open to a free circulation 
 of air. In coal mines timber is often destroyed by crushing. By dry 
 rot, timber is converted into a white powder. By damp rot, the timber 
 becomes slimy. It usually occurs where there is variation in moisture. 
 Under pressure, timber may be destroyed in a few weeks, but under 
 .good condition oak may last 25 years, and pine 6 or 6 years. In old 
 workings, timber which has been constantly wet, has lasted from 100 to 
 300 years. In some of the Hartz mines the shaft timber is purposely 
 Icept wet. 
 
 In English collieries the cost of timbering is from 4d. to pd. per 
 ton of coal worked. 
 
 Timber may be preserved by charring, covering with tar, lime or 
 cement. By removing the sap by water or steam and then filling up 
 the pores with salt, zinc sulphate, copper sulphate, tin, zinc or mercury 
 chloride. By treating first with phosphate of soda, and then with 
 barium chloride; barium phosphate, which is a solid stoney substance, 
 is precipitated in the pores of the wood, while the soluble sodium 
 chloride, which is simultaneously formed, may be washed away. 
 
 Timber saturated with creosote has a strong smell and therefore 
 objectionable when used underground. 
 
 The square section of a piece of timber which can be cut from a 
 given log is approximately four-fifths of a quarter of the square of the 
 mean circumference. 
 
 Timbering Levels. In coal mines many props or posts with a 
 lid or cap above and sill beneath are employed. They may be with- 
 drawn by a hooked lever and chain called a dog. If the upper ends 
 of legs are hollowed they are apt to split. Legs may be prevented 
 from being forced inwards by wedging, nailing, notching, or a strut. 
 Legs and their caps, head pieces or collars, may be united by scarfing, 
 the nature of the joint being regulated by the relative amounts and 
 direction of pressure. 
 
 Stemples or stull pieces may have to support a hanging wall and a 
 load of attle or deads. One end rests in a stemple-notch or hitch. The 
 stemple is usually so placed, that aijiy movement of the hanging wall 
 tends to wedge it tighter, by bringing it into a direction perpendicular 
 to .the two walls. The rise or difference from the perpendicular 
 
"5 
 
 A similar 
 
 tendency to wedge may be obtained by properly shaping the ends of a 
 stemple. Similar principles are followed in inclined coal seams. 
 Wedges or lids may be used at the end of stemples, corresponding to 
 cap pieces used with props. 
 
 Box, nog or chock timbering, is used for great pressures or high 
 roofs. 
 
 A simple form of roof timbering, consists of a series of stemples 
 covered with lagging. In wide lodes, stemples may be supported by 
 struts from the hanging wall. In flat lodes, the strut rests on the foot 
 wall. Stemples may be supported by struts from both walls. Rafter 
 timbering, is where two stemples rise from the walls to meet in the 
 middle of the lode where they but against a plank. 
 
 In stratified deposits, levels are usually supported by two leg 
 pieces and a cap. If the levels are wide, a central prop or strut from 
 the legs may be required to support the cap. Above the caps, lagging 
 may be employed and the frames or door sets, consisting of leg pieces 
 and caps, may require backing behind, and stringing pieces to keep 
 them apart. Stringing planks, held in position by struts or stemples, 
 are employed to support the sides or walls of a lode with a soft floor. 
 Sole pieces or sills are placed beneath the legs or stanchions. 
 
 In salt mines the floor is sometimes timbered with an inverted 
 arch of wooden blocks. A level may be completely arched in this 
 manner. 
 
 Driving in Soft Ground. Spilling, is timbering which is 
 carried on simultaneously or partially in advance of the work of exca- 
 vation, in running or quick ground. 
 
 The spills are planks about 2 inches thick, 4 inches wide and 6 or 
 7 feet long. These are sharpened by slightly beveling one end so 
 that when they are driven into the soft ground horizontally they rise or 
 diverge. The method consists in driving spills into the end of a level 
 and then excavating. The spills are supported as the excavation 
 proceeds. If the ground is very quick, breast or closing boards will 
 be required to support the face of a level. This method has some 
 resemblance in principle to that which, in 1823, enabled Brunnel to 
 drive the Thames tunnel, the sectional area of which was 38 feet by 
 22 feet 6 inches. He employed a shield of iron made up of 12 frames 
 
with 3 cells in each. The shield was forced forwards by hydraulic 
 rams, and brick work inserted in the space thus gained. To relieve 
 the pressure behind, the shield the cells could be opened. 
 
 Mr. Victor Simon, a Belgian engineer, devised a plan for penetrat- 
 ing soft ground which has succeeded where ordinary spilling has 
 failed. This consists in covering the floor, roof and face of a level 
 with a mass of conical wedges each about 3 feet long. As these are 
 driven forwards, the space which is opened is filled with solid door 
 sets. 
 
 Arcliworlc nd Walliii:?. The thickness of an arch in feet 
 = .0694 X radius in feet + I foot. It should not be less than 9 
 inches. 
 
 The height of crown = <; inches to 6 per yard of span. Under 
 pressure, 8 inches per yard. For inverted arches 3 inches per 
 yard. 
 
 An arch 2 feet wide and 1 1 inches thick will hold 45 feet of attle. 
 The pressure is the weight of the attle less its own friction. 
 
 In an inclined lode, arches to carry attle are placed so that their 
 springing line is at right angles to the dip. 
 
 Side walls have a batter of I inch to i^ inch per yard. For 
 watertight walling, the joints are increased from ^ inch to ^ inch. 
 Walls are destroyed by splitting, buckling, shearing and overturning. 
 For a wall not to be overturned, the line of resistance, which for a 
 rectangular wall is an hyperbola, must fall inside the foot of the wall. 
 Crushing strength in Ibs. per square inch. 
 
 Brick 500 1,000 Ibs. 
 
 Limestone 4,000 5,000 
 
 Granite 5,ooo 10,000 
 
 Dry walling only, resists crushing. In English bond, a course 
 consists entirely of headers or of stretchers., while in Flemish bond, 
 each course consists of headers and stretchers. Open spaces between 
 masonry and the roof or sides of levels must be carefully packed. 
 Sand forms a good packing. 
 
Cost of Arching (Collins). For a drift 8 feet x 7 feet one brick 
 thick, with lime mortar and well rammed behind with clay. 
 
 , s. D. 
 
 1,500 bricks at 20 shilling per thousand I. 10. o 
 Lime 2 cwt. at 9 d. I. 6 
 
 Sand 6 cwt. at 2 d. I. o 
 
 Labour of laying and pugging behind 10. o 
 
 2. 2. 6 
 
 If there is an inverted arch below the cost is % ir.ore. If half a 
 .brick is sufficient the cost is less. 
 
 
n8 
 
 HAULAGE. 
 
 General Woles. In mines with irregular roads it is necessary 
 to transport materials in bags, basket or trays. In working the cJwins 
 of iron stone in the Forest of Dean, boys carry from ^ to ^ cwt. in 
 a tray called a billy. To carry coal along a working face to a gob 
 road, sleds are often used. Originally the coal was placed in large 
 baskets called wves, which were placed on the sled and carried to 
 the bottom of the shaft. 
 
 Narrow wheelbarrows with a low center of gravity are sometimes 
 used underground. In Cornwall a wooden barrow without legs, costing 
 from 8/6 to 12/6 carries from I cwt. to \]^ cwt. The hund is a four 
 wheeled waggon used in Germany. The front pair of wheels are 
 placed almost under the center of gravity. When it is moved it is 
 slightly tipped so that it runs on two wheels, while when standing it 
 rests on four. 
 
 Trolleys are four wheeled flat trucks without sides. In 1775 
 Mr. Carr of Sheffield used iron tram plates. 
 
 Nicholas Wood, who experimented on haulage, says that on a 
 good road on the surface, a horse will draw 133 tons I mile per day. 
 Underground with wheels I foot in diameter it may draw 30-50 tons, 
 but if the wheels are less, it may only draw 15 tons. 
 
 Kibbles or Barrels. Of wood or %H sheet iron ; 22" at top, 
 34" in the middle, and 15^ below. Skips or boxes which run on guide 
 rollers are about 2' square and 4 or 5' long. They carry 6 to 10 cwt. 
 
 Kibbles are usually suspended on trunions which pass through 
 holes in the handle, the point of suspension being below the center 
 of gravity of the kibble. 
 
 Tubs. Tubs ought to be light and strong. The wheels may 
 be, I. Fixed on the axle, as on ordinary railroads. 2. The axle may 
 be fixed and the wheels revolve on the axle. 3. One wheel loose and 
 one fixed to the axle. 4. There may be as many axles as wheels. 
 
 In the first system when passing round a curve, inasmuch as the 
 two wheels on the same axle do not pass over the same distance, one 
 of them must be rubbing while the other is rolling. In running round 
 a curve in consequence of the inertia of the tub the flange of the outer 
 
119 
 
 wheel grinds against the inner side of the outer rail. Wheels which 
 are slightly coned partially obviate this. In passing round a 
 sharp curve, two axles of a tub do not tend to remain parallel. To 
 allow for this tendency to deviate from parallelism, play of say 
 2^ inch is given to the wheels. If a tub is turned round on successive 
 journeys along the same curves, the wearing of wheels and bearings 
 such as those just mentioned may be equalized. The flanges of wheels 
 are slightly rounded. Such a form offers resistance to derailment and 
 a tub is easily placed on its track. Wheels are usually 7^ to 15 inches 
 in diameter and axles i% inch to \y 2 inch. 
 
 The height of tubs may depend on the thickness of the seam. 
 Small tubs carry 3 to 4 cwts. Ordinary tubs carry 6 to 1 1 cwts. In 
 S. Wales there are tubs carrying I to 1^ tons. Large tubs are difficult 
 to handle. Percentage of dead load to useful load is from .25 to .50. 
 
 A waggon 30" x 42" X 20" holds about I ton of iron ore. 
 
 Tubs carry about 50 Ibs. of unscreened coal per cubic foot 
 of contents. 
 
 Ordinary tubs are usually constructed of hard wood, like elm or 
 oak ; ^ to I inch thick, bound with angle iron. The rectangular 
 boxlike form is the commonest. Prismatic forms are also used. Iron 
 tubs are lighter for a given capacity but they are difficult to repair. 
 Rectangular forms slightly bellied, are considered good designs. Length 
 3 / .7 // , breadth 2 / .6 / , depth I'.io". The axles turn on steel bearings. 
 On each side there is a fixed and a loose wheel. Wooden tubs at Pas 
 de Calais weighed no k. and carried 400 k. 
 
 At Blanzy, loose wheels on loose axles have been used. .The 
 journal box is oval and the play thus afforded diminishes the chance 
 of derailment. Well greased washers keep the wheels apart. 
 
 At the Pleasley Colliery, tubs carrying 13^ cwt. with 13*4 inch 
 steel wheels, 2 feet gauge, wooden sides 7 sheet iron ends, weigh 7 cwts. 
 
 By elbowing the axles, the bottom of the tub comes below the 
 axles. In this way the height is reduced, while a large capacity and 
 an increased stability are obtained. 
 
 Steel tubs, as for instance those made by Hudson & Co., carrying 
 II cwts. of coal and costing ,4.10.0 are durable and satisfactory. 
 
 At coal mines, on reaching the bank a tub is run into a tippler or 
 tumbler, and its contents discharged upon the screens. 
 
120 
 
 Resistance to Traction or Rolling:. The resistance to 
 traction may be estimated, 
 
 1. By determining the force required to keep a tub in motion. 
 This may be done by attaching an apparatus like a strong spring 
 'balance to the line which pulls the tub. 
 
 2. By finding the least inclination which can keep the tubs 
 .running. The tangent of this slope is the coefficient of resistance to 
 traction. 
 
 3. By observing the distance up an incline which a tub will run 
 
 after having descended another incline. 
 
 4. By noting the time taken by a tub in running down a slope 
 
 of given length and given inclination ( Merivale). 
 Let L = length of the incline in feet. 
 /f=height 
 Z=time taken to descend in seconds. 
 W= weight of tub in Ibs. 
 R= friction in Ibs. 
 a = angle of inclination of incline. 
 -=gravity= 32. 
 
 / 2Z \ 
 
 /?= IV (sin a - 1 cos a. 
 
 This friction usually varies between -J- and T i- - of the weight 
 of the loaded tub. On ordinary railroads at low speeds it is about 
 8 Ibs. per ton. With tubs it is from 2 to 4 Ibs. per cwt. 
 
 The resistance to rolling on a level may also be expressed. 
 Let W =the load in a tub. 
 
 W"i = the weight of the waggon or tub and its frame. 
 H / 2 = the weight of the wheels. 
 W\-\- ^2 = the weight of an empty waggon. 
 f =the coefficient of friction of the axle and its bearings. 
 
 Say .018 to .035. 
 
 ./^coefficient of rolling friction. Say .001. 
 r =the radius of the axle. 
 
 R =the radius of the rubbing portion of the wheels. 
 S =the total resistance to rolling on a level. 
 
 Then S =/^(Wi + W + W2)H /( W+ W{\. 
 
 R 
 
121 
 
 The coefficients given are for Railroads. See Molesworth, 
 
 Resistance to be overcome, or force of traction on 
 slope of inclination i. 
 
 Ascending. 
 
 sn t . 
 
 Descending. 
 
 This and the next two formula are given as in Gallon. On a 
 badly laid tramway rolling friction may be considerable and should be 
 introduced as in the last formula. 
 
 To reduce the force of traction, make f small by polished and 
 lubricated surfaces, make the axles small, increase the radius of the 
 wheels. 
 
 In reducing the value of r t the strength of the axle has to be 
 considered, while when increasing R the height of the tubs must not 
 be overlooked. In practice we may have. 
 
 /=.!. 
 
 [For wheels .2Om. to .2501. in diam. this may be 
 increased, while for wheels of .50111. diam it 
 may be less, say Viz- 
 
 \ = .29 W. 
 
 S =.0129 IV on a level for a full waggon. 
 $ =.0029 JFfor an empty waggon. 
 
 For a full waggon the resistance is therefore about four times more 
 than for an empty waggon. 
 
 Slope of equal Resistance. This is a slope on which the 
 work done in taking the full waggons towards the shalt, equals the work 
 done in returning with the empty waggons. This slope i is given by 
 the following formula. 
 
122 
 
 The value for sin i in practice is about .0055 and the slope is 5 or 
 6 millimeters per meter or i in 200. Andre gives i in in. 
 
 On such a slope the force of traction or .Si = .0051 W, or 5 thou- 
 sandths of the weight transported. 
 
 Slope of Equilibrium. A slope of equilibrium is one where 
 the full waggons when once started will continue in motion by them- 
 selves. In such a case the trammer rides behind the full waggon to the 
 end of its journey, his only work being to push the empty waggons 
 back to the starting point. Such slopes are used on long well con- 
 structed roads. 
 
 Such a slope is given by the following formula. 
 fr W+ Wi 
 
 g?/-ar 
 
 In practice Sin i may equal .0092, or 10 millimeters per meter or 
 I in 100. Andre gives i in 61, but it might be I in 88. 
 
 To bring back the empties on such a slope the force of traction 
 F\ =.0066 W or 6 to 7 thousandths of the weight moved. (See 
 Gallon.) 
 
 Roads. The narrower a road the less resistance is there on the 
 curves but the tubs are more unstable. Rails are often flat iron bars 
 ly-i" by K /x to 2 W b y %" These are fixed in sleepers 2> to 2'.$" 
 apart by wedges driven on the inside. The ends of two rails should 
 terminate at a notch. Bridge rails, T shaped and double headed rails 
 are used on main roadways. They weigh from 10 to 20 Ibs per yard 
 of length. The ordinary rail now used is flat bottomed and weighs 
 12-15 ^bs. per yard. The gauge 12^-24^. Minimum radius of curves 
 6-10 feet. 
 
 Bridge rails weighing 14 Ibs. per yard spiked with 2" nails to 
 sleepers 7* wide 2" thick, cost and about 3/- to 4/6 per yard. The 
 gauge may be 36". 
 
 Elevation of Hails at a Curve (MolesiuortJi) 
 
 Let 7i = elevation of outer rail in inches. 
 
 W= breadth of line in feet. 
 V the velocity in miles per hour. 
 R= radius of curve in feet. 
 
123 
 
 F2 
 
 Then /*= 
 
 1.25 X. 
 
 The section and weight of rails vary with' the load they carry,, 
 and the gauge. 
 
 At junctions where a train of tubs has to pass, movable points are 
 used. For single tubs these are not required. At rectangular cross- 
 ings where tubs may be turned, iron .plates and guide rails are 
 employed. \Vith inclinations of more than I in 30 self acting planes 
 where the full tubs descending pull up the empty ones are used. For 
 very steep inclines the tubs are carried down upon trolleys with a level 
 floor. On self acting planes, brakes are required. These may consist 
 of a segment of wood or an iron band. To prevent a rope slipping it 
 may be carried several times round a single pulley or back and forth 
 round two pulleys. A pulley with a conical groove lined with 
 wooden plugs grips a rope. Fowler's clip pulley answers a similar 
 purpose. 
 
 To lessen the chances of accidents from runaway tubs on self 
 acting inclines, at the top of the incline there should be slops to hold 
 the tubs, and at the bottom seizers to hold the rope or chain. 
 
 To avoid friction on a self-acting plane, the sag of the rope is 
 carried on sheaves placed between the rails. 
 
 Self-acting: Inclines (Merivale). 
 
 Let L = length of incline in feet. 
 //= height of incline in feet. 
 =angle of incline 
 /^weight of full set in Ibs. 
 E= weight of empty set in Ibs. 
 T= time running in seconds, 
 .^gravity =32. 
 ^=weight of rope in Ibs. 
 6"=weight of rollers and sheave in Ibs. 
 m coefficient of friction of tubs on level road. 
 w^= coefficient of friction of rollers and sheave = about .03 
 on average. 
 
I2 4 
 
 W= weight in Ibs. of the whole mass in motion. 
 P=force in Ibs. moving the sets. 
 Then P=Fs\na{niFcosa'i s -mE cos a -\-mfS-3f E 
 
 = 7 r sin a {in cos a(F-}- )+m'S+sin a(E-\-R}} 
 
 but sin ^=~Y and cos a practically = I. 
 
 T^TT T7 
 
 L L, 
 
 / 
 
 H 
 
 L 
 
 f - 
 
 Comparison of Work done by Men and Horses. From 
 experiments made years ago at the mine Vicoigne, it would appear 
 that the gain in employing horses underground to do the same work 
 as men or boys may be expressed as follows. 
 
 If the gain in money on carrying loo m. be x. then the gain. 
 
 For 2oom. = 2.7 x. 
 
 300 = 3.4*. 
 
 400 = 5.4^. 
 
 500 = 6.2x. 
 
 600 = 6.ix. 
 
 700 = 6.7*. 
 
 800 = 7.2X. 
 
 900 = 7.4^. 
 
 1000 = 8.5^. 
 
 1200 = 10.5*. 
 
 The useful effect is greatly influenced by the nature of the road. 
 Burat says that at Charleroi with a straight road and a slope of .005111. 
 per meter, a young woman may perform the work of 1,500 kilos per 
 kilometer. At Mons the same work is difficult for a man. 
 
125 
 
 Ifnulnaro ty Steam Power. I. Tail Rope System. A train 
 of lo or 20 tubs is drawn by a rope coiling on a drum, at the same time 
 a smaller rope (tail rope) is uncoiled from a second drum running 
 freely on a shaft. This latter rope passes over a system of pulleys, and 
 is attached to the end of the train, so that when the train has reached 
 its destination near the hauling engine, the second rope has been 
 uncoiled for a length equal to double that which the tubs have travelled 
 and is therefore ready on reversing the engine and throwing its drum 
 into gear with the shaft, to draw a train of empty tubs back to the 
 point from which the full tubs started. 
 
 2. Endless Rope or Chain Systems. In these systems a chain or 
 rope passes round two large pulleys, one situated at each end of the line 
 along which the tubs are to travel. One of these pulleys is driven 
 continuously and slowly in one direction so that part of the rope or 
 chain is continuously travelling in one direction over the center of one 
 line of rails and the other in an opposite direction over the center of a 
 another but parallel line of rails. The full tubs are fixed at intervals 
 on to the rope or chain travelling over one set of rails, while the empty 
 tubs are similarly fixed on the rope or chain over the other line 
 of rails. 
 
 In the 1st system two drums are each provided with brakes and can 
 be separately thrown in or out of gear with the shaft. When hauling 
 full tubs the tail rope drum is out of gear. When empty tubs are 
 returning the tail rope drum is in gear and the main rope drum is out 
 of gear. The tail rope is carried along or down a level on a system 
 of pulleys placed in an angle of the roof. Up the center of the line 
 of rails a series of sheaves are placed to lessen the friction occasioned 
 by the main or tail ropes sagging on the ground- Here a single line 
 of rails is only required but one engine may drive four drums to be 
 used on two different levels. Time is lost in the return journey, but 
 this is compensated for by high speeds varying from 12-16 feet per 
 second (10-15 miles per hour). Strong ropes are required. 
 
 3. Main Rope System. With inclination of more than I in 
 28 the tail rope may be dispensed with, as empty tubs by gravity alone 
 will drag out the main rope as they run back towards the starting point. 
 To avoid the running away of tubs behind the last in a train, a 
 trigger or devil is placed, which so long as the tubs are ascending 
 
126 
 
 trails on the ground. A bridle chain will hold a train of tubs 
 together. 
 
 With the no menclature of p. 123. 
 
 P= K sin a (in cos a E-\-m f S-\-m'R}. 
 
 and we get 
 
 - - {mE + m'S+ m'R}. 
 
 T= -V { FH \ 
 
 g{-= (mE+m'S+i'R-}\ 
 
 IV2.L 
 
 (Merhate). 
 
 E 
 
 In the endless rope or chain system to prevent a rope from slip- 
 ping, it either passes several times round a pulley or a special pulley 
 (Fowler's clip pulley or a V groved pully fitted with plugs of wood) 
 may be employed. Fowler's clip pulleys are usually employed to 
 transmit power to a wire rope used for haulage, or to turn a shaft at a 
 distance. These pulleys are at either end sufficiently high to clear 
 the tubs, but the chain by its sag reaches them at a short distance, 
 where it catches in forks fixed to the top of each tub. Sometimes the 
 rope or chain runs beneath the tubs and these are attached to the rope 
 by clips (Hanson's Clip. Humble's Clip.) 
 
 The speed is usually about 6 feet per second (4 miles 'per hour). 
 At the upper end of the line the tubs run down an incline and catch 
 the chain automatically. By an incline at the lower end they dis- 
 engage themselves automatically. A similar arrangement enables a 
 tub and the chain to pass round a curve, at which place the chain is 
 raised by a guide pulley. As the curve is approached the tub is 
 disengaged by the chain being raised, and it runs round a slope and 
 again engages itself with the chain after passing the curve. The tubs 
 are run on to the line at intervals of 20 or 30 yards. After a tub has 
 reached a certain point, it may be caused to give an automatic signal 
 indicating that another tub may be started. The weight of the chain 
 dds to the frictional resistances on the line. 
 
127 
 
 With a given velocity, more tubs can be conveyed in a given time 
 than by other systems. On an incline, the weight of the full tubs 
 assists in raising the empty tubs. 
 
 The endless chain system is suitable for straight roads which may 
 be undulatory. The tail rope system may be employed on roads which 
 are crooked or branched but not undulatory. 
 
 In considering the relative merits of these systems we have to 
 consider. I. First cost of waggon way. 2. First cost of plant (engines, 
 rails, &c.) 3. Cost of conveying coal per ton per mile. 4. Cost 
 of maintenance (ropes, chain and plant generally). 5. H. P. required, 
 &C. 
 
128 
 
 
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 Tn the tail rope system the total cost per ton per mile varies from- 
 1.948 to 2.iy2d. In endless chain from .551 to i.Sd. and in endless 
 rope from 2.06 id. 
 
 Cost of Transport per Ton per Mile (Ue 
 
 ^ d. Ordinary railroad with locomotive. 
 
 6 d. Ordinary road with horses, excluding maintenance of road. 
 % d.(?)Canal with horses, excluding maintenance of canal. Canals 
 with steam-tug as low as 1/100 & exclusive of mainte- 
 nance of canal. 
 
 \% d. Level railroad with horses. 
 %y 2 d. Underground level roily way with horses. 
 
 2 d. Ordinary underground roily, rope or chain haulage. 
 
 Electrical Haulage. Tn the arrangements for electrical 
 haulage a motor by gearing drives a drum. In a plant put up by 
 Messrs. Crompton as the Abercanaid Colliery S. Wales to replace 27 
 horses, the motor is built to run at 800 revolutions and takes 80 amperes 
 at 850 volts. The Dynamo will give 180 amperes at 500 volts running 
 at 550 revolutions. The cable is 3,200 yards long and composed of 37 
 strands of No. 14 high conductivity copper. Its resistance is 3,192 
 ohms, and there is a loss of potential of 51 volts or 10 per cent. 
 
 Underground Locomotives. These have been used ira 
 certain coal mines in Pennsylvania. Weight 1,100 Ibs. wheels 2 feet 
 diam : gauge 3 feet 6 inches. Length 12 feet. Height 6 feet. The 
 first cost and subsequent working expenses are less than when mules 
 have been used. 
 
 Underground Canals. Under favourable circumstances, as at 
 certain mines in Silesia, at Clausthal, in Lancashire and Flintshire,. 
 levels partly filled with water are used as underground canals. 
 
 Wire Tramways. For the conveyance of material upon the 
 surface, a load is carried upon a continuously moving wire rope, or by 
 haulage along a rope which is fixed. The cost of one of the former 
 lines capable of transporting loo tons a day is about ^400 per mile, 
 while maintenance and cost of transporting is about two pence per ton 
 per mile. 
 
 Hallidie's wire tramway in principle of working is like the endless 
 rope system. The recepticles for material are suspended on the 
 
130 
 
 rope which works round clip pulleys at the ends of the line. Cost 
 $6,000 to $8,000 per mile. Runs 200 feet per minute and with buckets 
 loo feet apart each carrying 100 Ibs. delivers 6 ton, per hour. 
 
 A single endless cable near the Ashio Mines, Japan is as follows : 
 
 Length 3760 metres, Supports 17. Longest spans 550, 423 and 
 350 metres. Maximum load per bucket 200 Ibs. Spacing 100 metres. 
 Speed 50 metres per minute. H. P. about 8 or 9. Roe and Bedling- 
 ton's Automatic clip saddles are used which prevent slip on steep 
 gradients and also during wet weather. Also patent balanced sheaves 
 are used. These latter increase the angle taken by the cable at the 
 trestles, adjust themselves to take an equal share of cable pressure, 
 and prevent local pressure or set. 
 
 With the same system in which there is equal wear over the 
 length of the cable, loads of 600 Ibs. or more may be carried. 
 
 In some systems stationary ropes stretched at the end are used as 
 tracks. On an incline the empties may be pulled up by the full 
 buckets. 
 
 lmn> Hit. 
 
.ili^til <> 
 
 WINDING. 
 
 Engines. Some winding engines lift 1,000 to l,6oo 
 tons of coal per day. The cost being about d. per ton per 100 
 fathoms. At some mines however from 2,000-3,000 tons of coal are 
 raised per day. Double cylinder, high pressure, condensing or 
 non-condensing engines are usually employed. For small loads 
 single cylinder engines with gearing are used. Vertical engines 
 occupy a smaller space and can be placed nearer a shaft than hori- 
 zontal engines. They require firm supports, and the forces applied 
 to the crank in the upward and downward stroke differ by twice the 
 weight of the piston and its rod. Horizontal engines can be readily 
 inspected, a solid foundation is easily obtained, but the wear on the 
 two sides of the piston, &c. is unequal. These are the most common 
 type. 
 
 With compound condensing engines at water works, a consumption 
 of 1.9 Ibs. coal gives one effective H. P. and 1.6 Ibs. gives one indicated 
 H. P. With small coal at collieries, pumping engines do fairly well if 
 they only burn 3^ Ibs. per I. H. P. 
 
 I>nty of Engines. In the best marine engines one I. H. P. 
 per hour may be obtained by the consumption of 1.5 Ibs. of coal. In 
 others engines 7 to 8 Ibs. may be used. In Cornwall 125 million Ibs. 
 of water has been raised by burning one bushel (84 Ibs.) of coal. A 
 -duty of 65 to 75 millions is common. 
 
 Horse Power reqnired at a griven Shaft. 
 
 Let H= depth in feet. 
 
 7"=s number of tons raised per day of ;/ honrs. 
 /*=the theoretical horse power required. 
 
 Then 
 
 nx 60x33,000 
 
 The effective horse power or the power actually required to over- 
 come frictional resistances, inertia &c. will be about three times that 
 which is calculated. 
 
132 
 
 The Resistance due to Inertia. 
 
 Let -tf=resistance in Ibs. 
 
 W= weight of load in Ibs. 
 
 rr i -A. e ^ 
 
 V=. maximum velocity in feet per se 
 
 g force of gravity = 32 feet. 
 
 7~=time in seconds to acquire the velocity. 
 
 Then 
 
 Experiment has shewn that when a cage is suddenly lifted the 
 strain on the rope is about double that of the load. 
 
 Dimensions of Engines. 
 
 Let H = depth of shaft in yds. 
 wi=weight of cage. 
 W2= weight of tubs. 
 W3=coal raised at each journey. 
 W4=:weight of rope unbalanced in shaft. 
 .'. wi+W2-f-tt>3+W4= W\ or weight on one rope and 
 
 s= W% or weight on other rope. 
 Statical load at starting=7tv 3 -f ?c> 4 = W^. 
 
 If the circumferences of the drum in feet = C, the stroke of the 
 engine in feet = Z, the mean steam presure in Ibs. per sq. in=P. and 
 the area of the piston in sq. in. = A. 
 
 Then 4xPX2L=Cx W* 
 
 C*$W*'** K lft l> *' !>'* ""^wo'I *>>tol 
 
 A T^T 
 
 To overcome the friction and the inertia at starting, A may be 
 increased about three times, ".and from this area, the diameter 2) or 
 the cylinder calculated. 
 
 To overcome dead points, and in case one engine might break 
 down, two engines with cylinders of diameter D are usually employed. 
 
 The engine power actually employed is therefore about three times 
 that which is calculated. Ordinary winding engines have a stroke 
 of 4 to 6 feet and a diameter of 24 to 34 inches. 
 
133 
 Indicated Horse Power. 
 
 ^/=area of piston in square inches. 
 
 P= average presure of steam in Ibs. per square inch in the 
 
 cylinder. 
 
 Z=length of stroke in feet. 
 A^number of revolutions per minute, then, 
 
 2 PLAN 
 
 Indicated horse power = . 
 
 33,000 
 
 Xominal Horse Power. For scientific calculations this term 
 is meaningless. It is used by makers of small high pressure engines 
 who allow 10 circular inches of piston area per nominal H. P. 
 
 Quantity of Material Raised. To determine the quantity 
 of material which may be lifted per hour, calculate the number 
 of revolutions made by the winding drum each journey, and from that 
 calculate the distance travelled by the piston. Knowing the average 
 piston speed, which may be from 300 to 600 feet per minute, the time 
 taken per journey is readily determined. The time taken for hanking 
 may be from 30 to 60 seconds and this added to the time taken for 
 winding gives the time occupied in raising and discharging a given 
 load. With this as a unit, the number of tons discharged per hour 
 may be readily calculated. 
 
 The maximum speed of a cage in a shaft may be 50 feet per 
 second. 
 
 Boilers. The boilers usually employed are the Lancashire 
 boiler with two flues or the Cornish with one flue. According to 
 Molesworth for each nominal H. P. a boiler requires, 
 
 I. Cubic foot of water per hour. 
 I. Square yard of heating surface. 
 i. Square foot of fire grate surface. 
 I. Cubic yard of capacity. 
 28. Square inches flue area; 18 inches over bridge. 
 
 For Lancashire boilers an approximate rule is; 
 
 Length in feet X Diameter in feet 
 
 = Nominal horse power. 
 
134 
 
 Table of Dimensions of Cylindrical Boilers. 
 
 (Molesworth}. 
 
 Nominal 
 H.P. 
 
 Length of 
 Boiler. 
 
 Diameter of 
 Boiler. 
 
 Diameter of 
 Flues. 
 
 Number of 
 Flues. 
 
 
 ft. in. 
 
 ft. in. 
 
 ft. in. 
 
 None. 
 
 i 
 
 6. o 
 
 i. 9 
 
 
 ... 
 
 2 
 
 7. 6 
 
 2. 
 
 
 
 3 
 
 9. o 
 
 2. 6 
 
 
 
 4 
 
 10. 
 
 2. 9 
 
 
 
 5 
 
 II. O 
 
 3- 
 
 
 
 10 
 
 16. o 
 
 4. 6 
 
 2. 
 
 i 
 
 15 
 
 18. o 
 
 5- 3 
 
 2. 4 
 
 i 
 
 20 
 
 20. 
 
 6. o 
 
 i. 9 
 
 2 
 
 25 
 
 25. o 
 
 6. o 
 
 i. 9 
 
 2 
 
 3 
 
 28. o 
 
 6. 6 
 
 2. 
 
 2 
 
 35 
 
 30. o 
 
 7- o 
 
 3 
 
 2 
 
 For more than 35 H. P. two or more boilers are required. Extra 
 boilers are required lo avoid stopping the engines while repairing or 
 cleaning. 
 
 The student's attention is Tiere called to the meaning of the term 
 nominal horse power. 
 
 Head Gear. Poppet Heads. The essential parts of a pit; 
 head frame are the legs (vertical supports) and the spurs (inclined 
 supports). 
 
 The height varies from 30 to 60 feet. Wooden legs (American 
 pine) may be 14^ X 1 8" square. These and the spurs are secured in iron 
 sockets. The spurs or back stays are so situated that the direction of 
 the resultant of the forces applied to the pulley, one by the rope 
 descending the shaft and the other by the rope leading to the drum, 
 falls within the base of the frame. 
 
 Wooden frames may last 30 or 40 years, but there is the danger 
 of their being destroyed by fire. 
 
 An iron frame 80 feet high to take a load of 2j^ tons should not 
 weigh more than lo tons (Collins). 
 
 Formulae relating to the strength of long and short columns may 
 be referred to in Molesworth's Pocket Book. 
 
135 
 
 "When two pulleys are used side by side the ropes lead to different 
 sides of the drum and therefore the angles made by the ropes round 
 the pulleys are different. This may be avoided by placing the pulleys 
 behind or above each other. The pulley frame ought to be adjustable,. 
 so that in case of shrinkage of the frame the line of the rope descend- 
 ing the shaft may be made central. 
 
 As wire ropes are good electrical conductors the head-gear might 
 be provided with lightning conductors. 
 
 Piil leys. Pulleys are from 6 to 16 feet in diameter. At Kiveton. 
 Park Collieries, Nr Sheffield, the pulleys are 20 feet, diameter. The 
 spokes are of wrought iron and the rim and bosses cast. The shape 
 of the groove varies with the shape of the rope. 
 
 Let F= force in Ibs. applied at rim of pulley to overcome 
 
 Iriction of axle. 
 W= weight of pulley in Ibs. 
 Z>=diameter of pulley in inches. 
 d= axle in inches. 
 *tt=coefficient of friction (say .07). 
 
 Then jp=. . (ColKns.) 
 
 A rope I inch circum : requires 10 foot pulley. 
 *% -.* IO K 
 
 1 2 > <j I II W 
 
 !^ >t ,iff t , j , ijj. IJ /4 ' 
 &C., &C., &C., 
 
 Winding: Drum. Cylindrical or conical. Flat rope winds on 
 itself in a vertical plane. As the rope leading to the head gear is 
 always in the same plane, a drum for a flat rope may be placed near a 
 shaft, say 20 yards distant. Drums of large diameter are used with 
 wire rope. 
 
 The diameter of a drum ought not to be less than that of the 
 winding pulley. Drums of too small diameters shorten the life of a 
 rope. Drums are covered with wooden battens on which the rope coils. 
 
 With 10 ft. as a minimum diameter for a drum for a rope I in. 
 circumference Andre tells as to add 6 in. to the diameter for every 
 % in. increase in the circumference of the rope. 
 
136 
 
 To determine the dimensions of shafts and axles, and distances 
 apart at which supports may be placed and the diameter of a winding 
 barrel for flat ropes (see Molesworth's Pocket Book). 
 
 Brakes. A common form of brake is a series of blocks of wood 
 which are brought into contact with the drum by means of a system 
 of levers. With a constant pressure the friction of the brakes on the 
 drum is theoretically independent of the extent of contact surface. 
 A single block of wood, in which holes are bored and filled with sand, 
 brought into contact by means of a system of levers is very effective. 
 Steam brakes and brakes which act automatically are sometimes em- 
 ployed. 
 
 Rope. Round or flat. Theoretically they ought to be tapered 
 but tapered rope is expensive to make and difficult to coil. 
 
 Burat gives the following as an example of the economy of a taper 
 rope. A rope 375 m. long was required to support 4,000 kilos. The 
 whole length was divided into 3 section each 125 m. long with weights 
 as follows, 688, 750 and 812 kilos. The total weight was therefore 
 2,250 kilos. If the rope had been constant in section in would have 
 weighed 8 kilos per meter, with a total weight, of 3,000 kilos. 
 
 The gain was therefore 750 kilos or on two ropes 15,00 kilos and 
 if the cost was 1.5 francs per kilo, the money gain was 2,250 francs, 
 and as a rope may last 18 months the gain per year was 1,500 francs. 
 
 To Calculate Dimensions of Taper Ropes (West}. 
 
 If G is the girth at the top, if the girth at" the bottom (calculated 
 by ordinary rules), /''the length in fathoms, then, 
 
 F 
 
 For steel taper rope log G= - X log g. 
 
 For iron taper rope log G= X log g. 
 
 A steel rope may last 2 or 3 years. In a record respecting the 
 wear of ropes, the size, length, cost of material, number of windings 
 .per day, maximum load, total load, durability &c. are noted. 
 
 The rope is fixed to the drum by taking two or three turns round 
 the drum and then passing it through a suitable opening to the inside 
 where it is coiled on the shaft. 
 
The attachment of the rope to the bridle chains is by a link and 
 .capping. The methods of attaching a rope to a link by means of an 
 iron cap is an operation deserving close attention. 
 
 Ropes often yield near the cage. To avoid the effects of jerking 
 they are attached to the bridle chains by a strong spring. Iron ropes 
 rapidly corrode in a ventilating shaft. 
 
 In ordinary wire ropes the wear is in the crown of the strand 
 when there is the most bending. In Lang's patent rope owing to the 
 principle of making a longer surface of wire exposed to friction the 
 wear is consequently more distributed. 
 
 Flat ropes can be wound on a smaller drum than round ropes 
 Their strength is approximately equal to ' the sum of the strength 
 of the round ropes of which they are composed less 10 per cent. 
 
 Hempen ropes are heavy and their weight is increased by moisture*. 
 
 The breaking strength of ropes for each pound per fathom is 
 approximately, 
 
 Hemp ropes .....l ( . l ..'.l;'ll.;... ....................... I ton. 
 
 Iron ropes ............................................. 2 
 
 Steel ropes .......................................... 3 
 
 If the breaking strain in tons= Wand the circumference in inches 
 =*C, then for 
 
 Hemp ropes W= .25 C* 
 
 Iron wire ropes W= 1.50 C" 2 
 
 Crucible steel ropes W= 3 2 
 Plough steel ropes IV= 4 C 2 
 
 The proof strain is \ to \ the breaking strain or twice the working 
 load which is \ to -^ of the breaking strain. 
 
 If W is the weight of a rope in Ibs. per fathom then for 
 
 C 2 
 Hemp ropes W= 
 
 ; *' ' Iron or s.eel \ ^f^j 
 
 (For tables of strength &c. see Molesworth.)' 
 
 The gain in lightness by using steel ropes is in deep shafts very 
 considerable. 
 
138 
 Broken ropes are joined by a shackle or by a splice. 
 
 As an illustration of the limit to which ropes may be used take 
 the case of a 2^ inch steel rope weighing 2 Ibs. per foot and with a 
 breaking strength of 84,000 Ibs. This ought to sustain 42,000 feet of its 
 the own length but for safety only 6,000 feet. If it carries a load 
 of 3 tons the safe maximum length would be 3,000 feet. 
 
 Chains. If the breaking strain in tons= W andZ? the diameter 
 in sixteenths of an inch. 
 
 Z>2 
 W= . Factor of safety 10. 
 
 Guides. Usually of wood 4 inches by 4 inches, costing I2/- to 
 I5/- per fathom, sometimes bridge rails, angle iron, round rods, or wire 
 rope. The latter is usually stretched by a weight of 2 or 3 tons 
 hanging in the sump. The clearance for cages should not be less 
 than 9 inches. The slides, cheeks or guide slippers on the cage which 
 clasp the guides on three sides are bell mouthed above and below. 
 With guides of wood the slides are malleable cast iron, but with rope 
 guides they are of brass. When iron guides are used, allowance must 
 be made for expansion and contraction. 
 
 Wooden guides of oak or pitch pine may be in lengths of about 
 12 feet united by scarf joints and wedged to transverse timbers about 
 6 feet apart. If bolted to the transverse pieces, the bolt heads must 
 be countersunk. With guides a cage may travel at rates up to 5 feet 
 per second. 
 
 Keeps. Landing dogs, keeps, fans, shuts or chairs, consist of a 
 series of levers at the pits mouth, which are thrown back by the 
 ascending cage. After the cage has passed, they return by the action 
 of a spring or simply fall into their original position and the cage is 
 lowered upon them, where it rests while the tubs are being exchanged- 
 
 The keeps below support the top deck of a cage. 
 
 The plummer blocks carrying the keeps ought to be bedded on 
 some elastic material. This would reduce the severity of the shocks- 
 a cage receives when it is lowered on the keeps. 
 
 Cages. These are usually of wrought iron. A single decked cage 
 for one tub weighs 5 to 6 cwts., for two tubs 10 cwts. At Monkwear- 
 
139 
 
 mouth a double decked cage for four tubs weighs 24 cwls. At the 
 Grand Hornu Colliery a four decked cage for 8 tubs weighs 2,692 Ibs. 
 The lightest and best cages are made of mild steel ; their weight being 
 y z to % of the gross load (tubs and coal). An iron cage weighs % 
 of its load. 
 
 At the Pleasley Colliery double decked steel cages carrying 
 2 tubs on each deck weigh 53 cwts. Cages carrying one tub on each 
 deck weigh 29 cwts. 
 
 Cages with several decks may be loaded or unloaded at a series 
 of platforms corresponding in position to the height of the decks. 
 
 Cages are suspended by 3 or 4 or even 6 bridle chains. For 
 safety, cage chains in the north of England are annealed once a month. 
 To make these chains of exactly equal length so that they may equally 
 share the load they may be altered in length by twisting or by a screw 
 at the point where they connect with the cage. Catches which fall 
 into position are employed to keep the tubs in the cage, or a false 
 bottom in the cage which sinks an inch or two, may be used. 
 
 To Find Jleetiitg-s with Flat Ropes (Merrvale). 
 
 Let 11 = half the number of revolutions. 
 
 d distance of meetings from bottom of pit in inches. 
 
 r= radius of drum at lift in inches 
 
 /= thickness of rope in inches. 
 Then d=$.l$i6n (2r+nit}. 
 
 Let Z>= depth of pit in inches. 
 
 w = number of revolutions. 
 
 r= radius of drum at lift in inches 
 
 /= thickness of rope in inches. 
 
 D= 
 
 Balancing: Loada. 
 
 The forces acting on a drum shaft in opposite directions are often 
 very unequal. On one side we have a cage with full tubs together 
 
I 4 
 
 with the weight of the rope in the shaft (W^i acting with a leverage 
 equal to the radius of the drum on which it is coiled {R\}. On the 
 other side tending to turn the shaft in an opposite direction we have a 
 cage with empty tubs W^ acting on the shaft with a leverage equal to 
 the radius of its drum RI. To balance, the loads W X A\ must equal 
 IVz X R<>. Now as the full tubs ascend the rope becomes short and 
 the quantity W\ X R\ become less, while the rope carrying the empty 
 tubs becoming longer the quantity W^ X R^. becomes greater. 
 
 After Wi X R has sufficiently exceeded W\ x R\, it will tend 
 to pull the engine round and if steam were cut off the winding would 
 be continued. Even if W z X R% remains less than IV\ X R steam 
 may be cut off near the end of a journey and the winding will be com- 
 pleted by the inertia of the moving loads. 
 
 The variation in loads here indicated may be more or less equa- 
 lized by the following methods. 
 
 1. Use flat ropes coiling on themselves. As the cage ascends 
 R\ gradually becomes larger and may approximately keep the quantity 
 R\ X W\ constant. While for the descending cage R* becomes less 
 and keeps the quantity R-> X IV* approximately constant. 
 
 2. By using round rope coiling in the grove of a conical drum. 
 For the ascending load R becomes greater while for the descending 
 load /v*2 becomes less. 
 
 3. By a chain so connected with the engine shaft that by means 
 of a series of weights attached at its other end which hang in a 
 pit, it tends at the commencement of the journey to lift the full load 
 in the shaft. As weight after weight reach the bottom of the pit, the 
 assistance given to the engine becomes less and less. When all the 
 weights have reached the bottom and the chain has run out, it com- 
 mences to retard the engine which retardation is increased as weight 
 by weight is lifted. This form is common. 
 
 4. Instead of a weighted chain, a rope or chain with a loaded 
 tub running down and up a properly formed incline may be used as at 
 Killingworth Colliery. 
 
 5. Employ a tail rope connecting the bottom of the ascending 
 and descending cages hanging in the sump. In this case the winding 
 rope carries the weight of the balance rope. A better form is to have 
 a balance rope leading from the winding drums and guided by special 
 pulleys down special compartments in the shaft. With this latter 
 
141 
 
 arrangement the shackle of the winding rope only carries the cage and 
 its contents. (Lindenberg and Meinickes System], 
 
 6. A pendulum counterbalance as at the Dudley Colliery. This 
 may be used for shallow shafts. 
 
 7. Engines with automatic variable expansion gear cause the 
 power to vary with the load to be overcome. 
 
 Examples of Winding* Loads {Burat}. 
 
 1. A drum is 6 m. diam. Length of rope 400 m. Weight 
 of rope 7 k. per meter. Useful load 1,500 kilos. Dead load 2,000 
 kilos. , 9fl) " gnj ,,i M1 jnwnomtet 4 
 
 Then the moment at starting is (1.5004-2,0004-2,800) 3 2,000x5 
 = 12,900 kilos. And at the end of the journey (1,5004-2,000) 3 
 (2,0004-2,800) 3= 3,900 kilos. 
 
 In this case towards the end of the lift the moment being negative 
 the winding is effected without the aid of the engine. 
 
 2. At the Robiac Shaft at Besseges the depth is 400 m. Cylin - 
 drical drum 3.60 m. diam. Two pulleys of the same diameter on 
 movable guides. Load 1,850 k. Cage 1,800 k. or total load 2,750 k. 
 Round and conical rope 402 m. with a working strength % its 
 breaking strength. In this case the moments are : 
 
 At starting i.^irnm-wW^ntwr^M^ ^S*) * 
 
 Just lifting the load ....: 5,835 
 
 At the middle a.^JJ^..tV.^w.vJ.n-.XV.Xife.. 3*358 >, .(i) 
 At the end.^.^f,.~.\,v.v+.....* 880 M 
 
 The drum makes 35 turns and at the end the moment is positive. 
 
 The moments may vary with the age of a rope. If a new rope 
 has a diameter J /] greater than an old rope, then the initial radii of 
 the drum with old and new will vary and the balancing be altered. 
 
 With flat ropes the biggest initial diameter and the smallest 
 diameter of rope are the most favourable especially for a deep pit. 
 
 Calculations relating 1 to the Balancing of Loads. 
 
 I. Counter balancing on an inclined plane. 
 Let P= weight on inclined plane. 
 
 a= angle of inclination of the plane. 
 
142 
 
 R =radius of drum carrying P. 
 r =radius of winding drum. 
 w weight of winding rope in Ibs. per foot 
 WQ= weight of empty cage. ' 
 
 H depth of pit. 
 
 x = height of cage from bottom at the time t. 
 ///!= moment exerted by the engine. 
 
 _ f W*+ W+(H-x\ iu- \ 
 
 Then I , ^ 4.!^) I r= moment resisting the engine. 
 
 This must equal the moment exerted by the engine plus the force 
 exerted on the inclined plane, or. 
 
 R P sin a+mi = r ( W+(H-x) ww x). 
 
 From which equation given R and P, the inclination of the plane 
 can be found corresponding to any position of the cages. 
 
 I. Counter balancing by conical drums, one of which has a radius 
 n when the radius of the other is r 2 . With values as above, for the 
 same values of x the following two equations must be true. 
 
 (I). {IV Q + W+(H-x} w} x^-(W^x w) 
 (2). 
 
 Substituting in (i). 
 
 .'. (2 
 
 rf rr 
 
 (2 W + W+Hzv} n = . (21^0+ W+2 w x). 
 
'43 
 
 2 WQ-+ W+ 2 W X 
 
 ffw-2 Wx 
 
 r 2=~ ~ 
 
 Pneumatic Hointinitr. This has been put into practice at the 
 Epinac Colliery by M. Blanchet. By exhaustion, a piston in a tube is 
 caused to rise and to this is attached the cage and tubs. The installa- 
 tion was expensive but it was chiefly abandoned because the workings 
 were unremunerative. Up to 820 feet one ton of coal was raised by 
 burning 16.5 Ibs. coal. With cables for the same depth 55 Ibs. were 
 required. 
 
 With two tubes the efficiency increaces with depth and it may 
 possibly be used for very deep mining. (Trans.: Am.: Mining En- 
 gineers. Vol. XIX. p. 115). 
 
 Man Engine and Endles* Chain HoUtlnff. The Mehu 
 
 man engine was tried at Anzin and Ronchamp and the endless chain 
 at Saint Jacques at Montlucon. They were expensive and dangerous 
 and therefore abandoned. 
 
 Water Wheels. Undershot, overshot, breast wheels, turbines 
 and other pressure wheels. 
 
 Theoretical Horse Power. 
 
 Q= quantity of water in cubic feet per minute. 
 // = head of water from tail race in feet. 
 P= theoretical horse power. 
 
 ^=.001892 Qh Q= 
 
 l if 
 
 Memoranda. 
 
 A cubic foot of water =62.425 Ibs. 
 
 /= pressure in Ibs. per sq. inch. 
 
 ^ = head of water in feet. 
 
 V= theoretical velocity in feet per second. 
 
 g= force of gravity (32.2 feet). 
 
 Then /= 7/x. 4335. ^=/x 2.307. 
 
144 
 
 Pressure per sq. foot=^ 62.4. 
 
 y-2 
 h= =.01555 v<i 
 
 Effective horse power for different motors : 
 
 ^ 
 
 Theoretical power being ........ .......... = i.oo 
 
 Undershot wheel ....... ................... .35 
 
 Poncelet's undershot wheel ............ .63 
 
 Breast wheel ................................. .55 
 
 High breast ................................. .60 
 
 Overshot wheel ........................... .68 
 
 2"? 106 .: ........... ". ........................ " i a 
 
 Hydraulic ram raising water ............ .60 
 
 Water pressure engine .................. .80 
 
 Knight and Pelton wheels ............... .82 
 
 In undershot wheels the power depends upon the square of the 
 velocity of the water. To increase the velocity a stream may be 
 narrowed in as it approaches the wheel. Power is gained by increasing 
 the width of a float. Its depth must not be increased unless it is so 
 arranged that it leaves the water in a direction perpendidular to its 
 surface. The velocity of the periphery of the undershot water wheel 
 should equal the theoretical velocity due to the head of water x 0.57. 
 
 of water. 
 
 (? quantity of water in cubic feet per minute. 
 jP= effective horse power. 
 
 Q= I5 " P P=.oco66 Q h 
 
 In breast wheels the power depends upon the weight water. 
 
 In overshot wheels which are the most common, the power 
 depends partly upon impact and partly upon weight. In order that 
 water may readily enter a bucket it is necessary that there should be a 
 suitable opening in the shrouding through which air may escape. 
 (Ventilated buckets). The effect obtained among other things depends 
 
'45 
 
 upon the height at which the water enters the wheel and the shape 
 of the buckets. According to Fairburn the diameter should be ~fe 
 more than the fall. The number of buckets should be twice the 
 diameter reckoned in feet. A velocity of periphery for a fall of 5 feet 
 is 7 feet per second. Ordinary wheels are 15 to 20 feet in diameter. 
 At the Laxey Mine there is a wheel 72 feet 6 inches in diameter. 
 These large wheels are difficult to construct and not so effective as two 
 smaller wheels. 
 
 For Breast and Overshot Wheels. 
 
 -=head of water in feet, 
 
 Q= quantity of water in cubic feet per minute. 
 
 P= effective horse power. 
 
 Q = in low breast wheels. 
 
 88i/> . 
 Q 7 in high _, if 
 
 777 P 
 
 Q= ^ in overshot 
 h 
 
 P= .00104 Q h'\o. low breast wheels. 
 
 ^=.00113 Qh in high 
 
 P= .00128 Q h in overshot 
 
 Turbines. Where there is a considerable head of water it is 
 essential to use a Turbine. There are inward, outward, parallel and 
 another class which may be called tangential flow wheels. 
 
 For formulae relating to Jonval's low pressure turbine and Four- 
 neyron's high pressure turbine see Molesworth. 
 
 Hurrty Onrdy, Knight or Pelton Wheels. In these 
 wheels which are simple in construction one or two jets under high 
 pressure impinge against cups on the rim of a cast iron wheel. Their 
 eflfeciency is said to exceed 82.6 per cent. 
 
 Men and Horses, Windlasses, Horse Whims. Tackle or 
 windlasses may be used to a depth of 20 fms. the kibble or bucket 
 being made from boiler plate about 14^ high and 12" diameter, and 
 carrying I to ij cwt. With horses a whim, derrick or whipsey deny 
 may be used, the whim kibbles being 20" to 24" high and 14" to "" 
 wide and holding 4 to 6 cwt. 
 
 r^ f tn -TV 
 <^-x,-a'S * 
 
I 4 6 
 
 For inclined shafts, skips running upon wheels are employed. 
 The cost of a skip road or shaft railway is from i.io to ; 3.10 per 
 fathom (Collins}. 
 
 Three or four men at a windlass, do not usually cost more than a 
 horse and its driver. A horse will do the work of about seven men. 
 With horse whims, the main axle may be vertical or horizontal. 
 Rather than employ three horses, it may be better to use a small 
 engine. Materials may also be extracted from a mine by water wheels, 
 pressure wheels, like turbines and Pelton wheels, hydraulic motors, by 
 a water balance, &c. 
 
 Comparative Cost (Colhns\ 
 
 Two men with windlass, from a depth of 10 to 15 fms., raise 12 
 tens in 8 hours, at a cost of about ^ d. per ton-fathom. 
 
 One horse whim, from a depth of 40 fathoms, raises 15 to 20 tons 
 in 8 hours, at a cost of about y$ d. per ton-fathom. 
 
 With engine power from 150 to 800 fathoms, 20 to 30 tons may be 
 raised at a cost i/ 3 o d. per ton fathom. 
 
 Winding by Water Balance. Let a tank in the descending 
 Cage be loaded with until its weight is sufficient to raise the full tubs. 
 The water is discharged at the bottom of the shaft and run off 
 through an adit. At Montceau les Mines it has been applied to a depth 
 of 225 feet. 
 
 Accidents in Shafts. To prevent tubs running from the bank 
 into the shaft, the mouth of the shaft is fenced with gates which slide 
 vertically. When the cage comes up these are lifted. When the cage 
 descends they fall down into their place. 
 
 In England between 1880 and 1890 there were 45 accidents result- 
 ing in 87 deaths, due to the breaking of ropes and chains in shafts. 
 
 To avoid such accidents, safety catches are attached to cages. So 
 long as the cage is hanging by the rope, a strong spring or series of 
 springs are compressed. If the rope should break, these springs 
 immediately extend themselves, and their movement is used to force 
 chisels or toothed eccentrics into contact with the guides which prevenj 
 the cage from falling. 
 
147 
 
 At Anzin, safety catches have been used for a long time without 
 accident, but it is thought that if the velocity of descent be high, the 
 tension on the rope might be so far reduced that the catches might act 
 when they were not required, resulting in greater or less damage to 
 the guides. 
 
 They are largely used in the Australian Gold mines. 
 
 King and Humble's safety grip works upon guide ropes. If the 
 winding rope is used to convey a current of electricity acting on electro 
 magnets in the cage, these may be used as suggested by Mr. J. Yates 
 to hold back griping cams, which if the rope should break must 
 come into action. 
 
 It may here be mentioned that a current on the winding rope 
 been tried in the Durham district to signal between the cage and the 
 engine house. 
 
 Overwinding;. As the drums on which the rope is coiled are 
 large, it might happen that by one revolution of the engine after the 
 cage has reached the bank, the cage might be carried to the head gear. 
 To prevent accidents of this kind, the engine man ought to have a 
 clear view of the pit's month so that he can see a mark on the 
 winding rope which indicates that the cage is near the surface. A 
 tell-tale or indicator representing the movement of the cages in the 
 shaft placed near the engine driver tells him at any instant the 
 position of the cage. The movement of the model is derived from 
 the winding engine. Sometimes the ascending cage is caused to 
 ring a bell announcing its arrival near the surface. Sometimes the 
 rope is attached to the cage by means of a safety hook (King and 
 Humbles). In case of over-winding the hook is partially pulled 
 through an opening in a set of timbers crossing the head gear. The 
 lower part of the hook being large it is unable to pass the opening. 
 It therefore comes forcibly in contact with it. By this contact the 
 upper part of the hook is opened and the rope is freed. At the same 
 time two projecting pieces are thrown out laterally and catch on the 
 upper side of the cross piece and the cage is left suspended. 
 
 Another device to prevent over-winding is the use of a steam brake 
 which comes- into action after a certain number of revolutions of the 
 engine. 
 
148 
 
 PUMPING. 
 
 Martin found in Staffordshire that in 125 sq. miles area the 
 quantity of water pumped was 50,000,000 gals or 220,000 tons in 24 
 hours. That is to say 10 times the quantity of coal which was raised 
 in that district. The force required was 5,000 H. P. 
 
 In other districts, even when mines run beneath the sea, the water 
 to be extracted may be very small. Water may be kept out of some 
 mines by surface drains, or by tubbing oft feeders. The temperature 
 or the chemical character of underground water will sometimes indicate 
 the source from which it comes. Limestone districts are usually 
 watery. 
 
 To measure the water from a/eeder, build a dam across the drift 
 and let the water escape through a rectangular notch cut in a thin 
 plate of metal, then 
 
 If =gallons per minute. 
 
 d= depth in inches of the sill of the notch below the surface 
 
 of the water. 
 /=length of notch in inches. 
 
 Then = 2.67 Id Vd~ 
 
 A more certain measure of the water from a feeder is to determine 
 the same from the time taken to fill a box of known capacity. 
 
 Dams. Dams are used to prevent water passing from one portion 
 of a mine to another. If of timber, they are built of wedge shaped 
 blocks 3 to 8 feet long, put together as an arch of 18 to 30 feet radius, 
 the back of the arch being on the side from which the pressure comes. 
 Between the blocks there may be tarred flannel and wedges. They 
 are built on a bed cut in the solid rock, in a narrow part of the level. 
 During building, a large central man hole 18 inches in diameter is left 
 for the ingress of workmen, a hole below for the escape of water and a 
 hole above, I inch in diam for the escape of air. On completion, the 
 lower hole is closed, then the man hole by drawing inwards a wedge 
 shaped block, and finally, after water escapes above and the air has 
 been expelled, the upper hole is closed. 
 
149 
 
 Wooden dams will withstand 30-50 yards head of water. Brick 
 dams are made with two arches about 2 feet apart, the space between 
 being filled with clay. 
 
 Dams, Tubbing-, Arc. 
 
 k= thickness in inches. 
 r= external radius in inches. 
 
 7= ultimate crushing strength in Ibs. per square inch. 
 /=head of water in Ibs. per square inch. 
 Then for cylindrical dam, walling or tubbing. 
 
 Spherical Dam. 
 
 
 A factor of safety of 10 is allowed for in the formula . 
 
 The values for Tare as follows : 
 
 Wrought iron 38,080 
 
 Cast iron 107,520 
 
 Beech 8,500 
 
 Oak 10,000 
 
 Pitch pine 6,500 
 
 Brick ordinary red 800 
 
 Stourbridge fire 1 >7 1 7 
 
 Sandstone 2,185 to 7> 88 4 
 
 Concrete 2,000 
 
 {Molesioortfi). 
 
 Raising: Water by Simple means. At the Wallesend and 
 Hebburn collieries barrels of sheet iron 16 feet long, 3 feet 4 inches 
 in diameter, each holding 800 galls, were used. Below they had a large 
 valve which allowed them to be readily filled and readily emptied. 
 
 By this means as much 3,000 galls of water have been raised per 
 minute. 
 
 In a mine 300-400 feet in depth a kibble of 2 cubic meters 
 content, making 40 journeys per hour, will raise 80 c. m. per hour or 
 640 c. m. per day of 8 hours (Burat). 
 
150 
 
 At mines worked by primitive methods small, hand pumps are 
 used, each having a lift of 3 or 4 feet. In Japan these are 12 feet long, 
 4 inches diameter and have a stroke of 2 feet 8 inches. Sometimes 
 Egyptian wheels about 8 feet diameter are employed. Rag and chain 
 pumps are simple contrivances. 
 
 Water may be raised and carried over a barrier by a siphon, at the 
 end of which there ought to be valves so arranged that when the water 
 falls too low they are closed by floats, and the siphon remains full. 
 Rotary pumps are good for lifting muddy water. 
 
 Suction pumps theoretically draw up water to about 32 feet (a 
 height which varies with the height of the barometer) but on account 
 of friction, slip, imperfect vacuum &c., they only draw to about 25 feet. 
 
 Force pumps theoretically work to any height, but when they 
 exceed 100 feet the valves are subjected to great strains. 
 
 The lift of a so called suction pump may be 30-40 meters and 
 sometimes even 70 meters (Burat). 
 
 At water works, compound reciprocating engines with double 
 acting pumps are used. The duty reduced to 112 Ibs. is from 95 to 
 100 million or even more foot Ibs. With Cornish engines the duty is 
 from 50 to 70 million foot Ibs. 
 
 Cornisli Pumps. For the first lift commencing at the sump, a 
 suction pump is used. Above this are a series of force pumps, all of 
 which are worked by "off sets" from one set of rods. 
 
 In force pumps the plunger may either entirely fill the case, or 
 the space in the case may be approximately equal to the solid content 
 of the plunger. In this latter case, the flow of water may be made 
 continuous. The plunger is made of iron or bronze. 
 
 Main, Bods, Pump Spears, Rocking: Beams. A-<. Rods 
 are usually of pitch pine. Theoretically they should be tapering. 
 The lengths of pine are joined by scarf joints, wrought iron strapping 
 plates and bolts. At Wheal Vor, which is 300 fathoms deep, we have 
 the following : 
 
 From surface to 780 ft. 2 timbers. each I2// square. 
 
 780 864 I timber. i6// 
 
 864 984 M" 
 
 984 1044 13 
 
 1044 to bottom 12 
 
As the Consolidated copper mines Gwennap, Cornwall, the main 
 rod was one third of a mile long and weighed 95 tons. The other 
 rods weighed 40 tons; 39 tons of this balanced the water in the pumps 
 and the remaining 96 tons were balanced by counter weights &c. 
 (Collins). 
 
 Iron rods do not work so smoothly as wooden rods. 
 
 Guides are employed at intervals as with the rods of a man engine. 
 
 The engine, which is single acting, raises the rods, and these 
 falling by their weight, which is about i/io greater than the corres- 
 ponding water column, raise the water. Any excess of weight is taken 
 off by balance bobs placed at intervals in the shaft. 
 
 The main rods are worked by a rocking beam which may be of 
 wood, wrought or cast iron. 
 
 In 1 86 1 a cast iron beam at the New Hartley Colliery 34 feet 
 long and weighing 42 tons broke, and carrying in the sides of the 
 shaft as it fell, buried all who were below. 
 
 At Tresavean the rods and balance bobs were as follows. 
 
 Rods 16-17 tons. 
 4 balance bobs 16 tons each. 
 4 loaded balance bobs 18 tons each. 
 
 These with the water which is raised, represent 260 tons of 
 material which is in motion at each stroke. 
 
 A counter balance framed like a triangle with the apex downwards 
 carrying two balance weights has sometimes been employed. \Yhen 
 the rods commence to fall, a large weight at the apex assists the rods, 
 causing them to fall for a short distance very quickly and thus reducing 
 the slip. 
 
 Hydraulic balances are sometimes employed to reduce the weight 
 of the rods. They consist of a plunger which as it descends lifts a 
 column of water. A plunger compressing air may be similarly 
 employed. 
 
 In case of breakage, indoor and outdoor catches are placed at 
 intervals down the shaft (see Man engine rods). 
 
 Talves. Valves should be light and open to about an angle of 
 70. If they open more, the slip, which is usually from 5 to 20 \ m 
 will be increased, and if less, the free entrance of the water is impeded. 
 
152 
 
 Classification of Valves. Michell in his "Mine Drainage, 
 gives the following. 
 
 I. Metallic Valves. 
 
 a. Ordinary clack valves. 
 
 b. Clack valves with contrivances to facilitate the exit, of 
 
 water. 
 
 2. Valves with vertical lift. 
 
 a. Single beat. b. Double beat. 
 
 c. Treble beat. d. Qnadruple beat. 
 e. Six beat. 
 
 II. India Rubber Valves. 
 
 1. Flat valves. 
 
 2. Conical valves. 
 
 3. Lip valves. 
 
 Clack valves are almost entirely used in Cornish pumps. 
 The concussion in closing is great if the lift is high. 
 
 The slip is also great; sometimes 10 / . They are not suitable 
 for steam pumps. 
 
 Those with contrivances to facilitate the exit of water are not 
 suitable for high speeds. They do not close with sufficient rapidity. 
 
 Among single beat valves we have cup valves, wing or mitre 
 valves, spill or mushroom valves and ball valves. All these valves 
 have a high lift. Excepting the ball valve, they are suitable for light 
 lifts. For high speeds they should have an India rubber spring and 
 a large area compared with the working barrel. Double beat valves, 
 like Harvey and Wests, have a large lifting area, a large water way 
 and a low lift. The concussion and slip are therefore small. They 
 are used for water works, but they are unsuitable for dirty mine water. 
 An India rubber spring gives a quick close. Treble beat and other 
 similar valves are still less suitable for dirty water. 
 
 India Rubber valves which are circular discs resting on a grating, 
 and opening round the circumference, are suitable for pressures not 
 exceeding 50 Ibs. 
 
 Massey's valve, which has a revolving disc, has been used for 
 pressures up to 150 Ibs. per square inch. 
 
Valves are made of wood, leather or India rubber. 
 
 In suction (lifting) pumps, the area of the upper valve is about 
 one half the area of the cross section of the barrel. On the lowest 
 suction valve a ring is placed, so that it can be raised for examination. 
 
 To avoid a shock on the valve a slight pause is made before 
 commencing the downward stroke. The shock may be mitigated by 
 dividing a valve into 3 or 4 parts. (See Michell's Mine Drainage). 
 
 Stroke and Lift. The stroke is usually 2-10 feet and the lift 
 may be 70 to 130 feet. A small diameter and long stroke is preferable 
 to a large -diameter and short stroke, as the slip is less. In Cornwall 
 the lifts rarely exceed 300 feet. They are usually 30 to 40 fathoms. 
 At Creusot the lifts are 80-92 m., the lift depends greatly on the 
 strength of the valves. 
 
 Gallon describes a pump with a lift of 300 m. (328 yards). 
 
 Burat says, to raise 1,000 c. m. per day, the stroke should be 2 m., 
 for 2,000 c. m. it should be 3 m., and for 3,000 m. 4 m. stroke. Long 
 strokes give difficulty in the management of balance bobs &c. and 
 necessitate a lower speed of working. 
 
 The following shews the advantage of a long stroke. 
 
 1. With a 4 m. stroke. 
 
 Rising 4 sec. } 
 
 Descending 7 y Total 16 sec. or 4 strokes per minute. 
 
 Repose 5 J 
 
 2. With a 2 m. stroke. 
 
 Rising 2 sec. ~t 
 
 Descending 4 [-Total n sec. or 6 strokes per minute. 
 
 Repose 5 J 
 
 In the former we get 16 meters raised per minute while in the 
 latter only 12 meters. In exceptional cases there may be 12 strokes. 
 Five or six strokes are however more common. 
 
 In ordinary force pumps the water does not rise in a straight line. 
 To obviate this a hollow cylindrical plunger with a double beat valve 
 at one end has been designed. By this arrangement the water rises 
 in a straight line through the plunger. The disadvantages are the 
 difficulties of construction, and it can only be used for a small heights. 
 
154 
 
 Pipes. Pipes are usually of cast iron, but in case of lifting 
 pumps sometimes of wrought. They may be galvanized. 
 
 If the water of the mine is acid, the inside of the pipes may be 
 painted and then lined with wood. Under such circumstances the 
 principal parts of the pump may be made of gun metal. 
 
 For cast iron pipes, if T = thickness in inches, D = diameter of 
 pipe be inches, -#head of water feet that will burst the pipe, then, 
 
 If W= weight in Ibs. per foot of pipe, D = outside diameter in 
 inches and d = inside diameter in inches. 
 
 Two flanges equal the weight of I foot of pipe. 
 
 An ordinary length for pipes is 9 feet. Internal diameters 9-10 
 inches and ^ inch to j^ inch thick. They are tested to 10 or 20 
 atmospheres. In ordinary joints, between the unplaned flanges, a ring 
 of wrought iron covered with tarred flannel is placed. Flanges with 
 planed faces do not require the ring. Sometimes a ring of lead 
 wrapped with lamp cotton or a ring of gutta percha is employed. 
 Specially formed flanges, where a groove has been cut for packing, 
 withstand pressures of from 400 to 1000 Ibs. per square inch. (See 
 Michell's "Mine Drainage"). 
 
 The velocity of water in pipes is usually 3 or 4 feet per second. 
 Pipes should be straight and without contractions. 
 
 The thickness varies with the diameter. 
 Friction in Pipes. 
 
 For velocities of 2 feet per second. 
 
 (Boulton & Watt). (Weisbach). 
 
 3 36-00 34.79 
 
 6 18.00 17.37 
 
 12 9.00 8.71 
 
 2 4 4-50 4-33 
 
155 
 
 3 
 6 
 
 12 
 
 2 4 
 
 12 
 
 ~4 
 
 For velocities of 3 feet per second. 
 
 Sl.OO 71.28 
 
 40.50 35.85 
 
 20.25 17.89 
 
 10.12 8.98 
 
 For velocities of 7 feet per second. 
 
 441 335-28 
 
 220.50 
 110.25 
 
 55-12 
 
 197.70 
 
 83-95 
 41.82 
 
 A general formula given by Merivale is 
 
 .//=head of water in feet required to overcome resistance. 
 (7=gallons per minute. 
 L = length of pipe in yards. 
 Z?=diameter of pipe in inches. 
 
 Classification of Pumps. Michell gives the following classi- 
 fication of steam pumps. 
 
 I. HORIZONTAL ENGINES. 
 
 A. ROTARY. 
 
 (Expansive condensing engines 
 with connecting rod crank and 
 fly wheel). 
 
 a. Simple steam pumps. 
 
 b. Compound steam pumps. 
 
 B. NON-ROTARY. 
 
 a. Simple steam pumps. 
 
 (Non expansive, non-condensing 
 like the "Special"). 
 
 b. Compound steam pumps. 
 (Expansive, non-condensing). 
 
 II. 
 
 A. ROTARY. 
 
 a. Simple steam pumps. 
 
 VERTICAL ENGINES. 
 
 (Expansive non-condensing). 
 
 B. NON-ROTARY. 
 
 b. Simply steam pumps. 
 
 (Non-exjiensive, non-condens- 
 
 
 \fO^ 
 
156 
 
 It will be observed that all pumps with their engines in the above 
 classification form one machine, whereas the Cornish engine and its 
 pumps are separate machines. The Bull engine is a Cornish engine 
 working directly over a shaft and therefore direct acting. In this case 
 the pumps are also adjuncts to the engine. The objection to Bull 
 engines is that they block up the shaft. 
 
 Fuel. 
 
 A cornish engine requires about 3.5 Ibs. of coal per H.P. 
 
 A common ,, ,, ,, 5 ,, 
 
 A high pressure engine requires about 10 Ibs. of coal per H.P. 
 
 A small high pressure engine requires about 15 to 20 Ibs. of coal per H.P. 
 
 Duty of Pumps (Michell). 
 
 At the Tynewydd Collierya "Special " (steam cylinder I2// water 
 cylinder io r / stroke 18^) consumed about 14 cwts. coal to raise 300 
 tons of water 66 feet. This equals a duty of 3,168,000 Ibs. raised 
 I foot by I cwt. of coal and allowing for loss of heat say 4,000,000 Ibs. 
 which is 1/20 of the duty of a Cornish engine. A Cornish engine will 
 give a duty of 95,750,000 Ibs. raised I foot, by burning I bushel of coal 
 (94 Ibs.) or 1 14,000,000 Ibs. for I cwt. of coal, or 33 times that performed 
 by the above "Special." Mr. John B. Simpson assumes that a "special" 
 requires 10-12 Ibs. of coal per effective H.P. per hour. Michell says 
 that underground it may require 15 Ibs. This is equivalent to a duty 
 per cwt. of coal of 14,784,000 feet Ibs. which does not agree with the 
 above statement of 4,000,000 Ibs. Further, the duty of a Cornish 
 Engine appears to be too high. 
 
 A "Special" has lifted 120 galls per minute 1040 feet and has 
 worked for 2 years under heads of 500 feet. (Michell). 
 
 The compound differential pumping engine (Davey's Patent) 
 works with high expansion and great economy. 
 
 There is usually considerable loss in conveying steam from a boiler 
 on the surface to a pump of the Special type placed under ground. 
 
 Hydraulic Engines. Hydraulic Engines are used for drawing 
 water from dip workings or places where an ordinary engine might 
 be submerged. The principle on which they work is to cause a small 
 quantity of water under the pressure due to a considerable head, to 
 aise a large volume of water a small height. The difference between 
 
a hydraulic engine and a steam engine lies chiefly in the construction 
 and method of actuating the slide valve. The hydraulic engines of 
 Davey, Carrett Marshall are well known. 
 
 The pressure available in working such pumps is evidently the 
 difference between the pressure in the pressure pipe and that of the 
 back pressure in the delivery pipes. This principle is inverted in the 
 Hydraulic Ram. 
 
 At the Comstock Lode, Nevada, a pair of hydraulic engines on the 
 2400 feet level, raise water 800 feet to the Sutro Tunnel. They are 
 worked by water columns from the surface which are actuated by 
 plunger pumps driven by a compound engine. 
 
 Water ejectors may be used for heights up to 100 feet. 
 
 Pnlsometer. A pulsometer works to a height of about 60 feet, 
 and dirty water does not interfere with its action. 
 
 Horse Power for Pumping. (Moleswortfi). 
 
 G= number of gallons to be raised in 24 hours. 
 F= number of cubic feet to be raised in 24 hours. 
 h =height in feet to which the water is to be raised. 
 H P= actual horse power required. 
 
 HP 
 
 -rz -r = 
 
 4752000 
 
 25 per cent is added to overcome friction and 50 or 60 per cent 
 more for contingencies, making a total of 70 or 80 per cent additional 
 power. 
 
 Diameter of a Single Acting: Pump. (Moksvjorth'). 
 
 L = length of stroke in feet. 
 
 G= number of gallons to be delivered per minute. 
 F= number of cubic feet to be delivered per minute. 
 JV= number of strokes per minute. 
 Z>=diameter of pump in inches. 
 F=. 00545 IT- LN. 
 
I 5 8 
 
 - /HE" 
 
 \ .034 L N 
 
 m 
 
 .00545 L N 
 
 These formulse give the net diameter of the plunger which is 
 usually increased i/4th to allow for leakage &c. 
 
 Comparison of Pumping Gear. I. Pumping from the 
 surface by means of rods. Here there is the theoretical objection that 
 a large weight, a heavy mass of machinery and water, is continually 
 being set in motion, first in one direction and then in another. The 
 cost of the rods, balance bobs &c. is great and they encumber the 
 shaft. The engine which may be compound, works with a high rate of 
 expansion and is economical. Where Bull engines are employed, 
 rocking beams &c. are avoided, and the first cost is less than with an 
 ordinary Cornish engine, but the shaft is partially blocked. 
 
 2. Pumping from below. In this case the engine is badly placed 
 and liable to accident from floods, falls &c. Rods are avoided and the 
 cost is relatively small. Great pressures have to be provided against. 
 The steam is not employed so economically as it is with surface 
 engines. 
 
'59 
 
 LIGHTING. 
 
 Lighting usually costs from i^ d. to 2^ d. per shift per man. 
 
 A primitive method is to use torches. The ordinary method is to 
 use candles or lamps. Occasionally gas and the electric light is used. 
 Petroleum wells may be lighted by reflection from the surface. 
 
 Caudles. The candles usually employed run from 20 to 50 to 
 the Ib. In Cornwall there are 12 to 16 per pound. The smaller candles 
 are used where fire damp occurs. They may be carried in a lantern, on 
 a holder or in a lump of clay. Unless carefully used there is much 
 waste. \}/z to 2 Ibs. may be used in three shifts of 8 hours each. 
 
 Oil. In the south of France olive oil is employed while, in the 
 north, colza is used. Sometimes walnut oil and fish oils are employed. 
 The quantity used depends upon the size of the wick. Usually 4 oz. 
 valued at i]/ 2 d. to 2 d. are burnt per shift 8 of hours. A spherically 
 formed tin lamp used in Scotland costs 2^ d. and it may be burnt 
 for 7 or 8 hours for I d. 
 
 Safety Lamps. All ordinary safety lamps consist of an oil lamp 
 surrounded by fine wire gauze. An explosive gas entering the lamp 
 takes fire inside, but because the wire is a good conductor of heat the 
 flame can not pass to the outside until the gauze has become sufficiently 
 heated, or it is forced through by a draught. In 1811 Clanny invented 
 a safety lamp, which in 1815 was followed by the lamps of Davy and 
 Stevenson, all of which embody the above principle. 
 
 Davy's Lamp. In this lamp there are 28 wires to the linear 
 inch or 784 apertures per square inch. It must not be placed in a 
 current of air of 7 or 8 feet per second. Therefore it must not be 
 swung or carried too quickly. It requires careful cleaning. This is 
 done by heating the gauze in a muffle and then well washing. Weight 
 \% Ibs. and cost j/. It gives about 3/10 of the total light. It may be 
 so arranged that on opening it is extinguished. The lamp may be 
 fastened with a lead rivet, or so arranged that the lock can only be 
 opened by means of a powerful magnet. Davy's are used in the more 
 dangerous workings. 
 
 ' 
 
i6o 
 
 Stevenson's Lamp. (The Geordie). This has a large cylinder 
 of glass with gauze above. The air enters below. It is heavier than 
 the Davy, but gives more light. It goes out when hot. 
 
 Clanny's Lamp. This also has a glass cylinder but not so 
 large as in Stevenson's lamp. It is heavy and brittle. 
 
 Mneseler's Lamp. This is used in Belgium. It has a glass 
 cylinder, a central horizontally placed gauze diaphragm, and a central 
 metal chimney up which the heated gases ascend. It therefore burns 
 well and gives a good light. It is easily extinguished in an ascending 
 current or if inclined. It is one of the best lamps and its use Is 
 extending. 
 
 There are many other lamps but none of them are safe unless 
 used with caution. When on fire inside they ought to be extinguished 
 or quietly withdrawn to a pure atmosphere. Lamps with glass 
 cylinders are liable to be accidentally broken or cracked by the firing 
 of gas inside or by cold water dropping upon them. When the Evan 
 Evan's lamp takes fire inside, a string is burnt, and springs are released 
 which close the ingress and egress apertures for air, and the light is 
 extinguished. In other lamps these openings are closed by hand and 
 the lamp is extinguished by the products of combustion. 
 
 Davy, Clanny, and Stephenson lamps are respectively unsafe in 
 currents of 400, 600 and 800 feet per minute. In mines, currents of 40x3 
 feet per minute are frequent and in main airways, currents approaching 
 2000 feet per minute have been recorded. 
 
 The Royal Commission on Accidents in Mines (1881) especially 
 mentioned four lamps worthy of special attention. There were how- 
 ever others nearly if not quite as good. The lamps mentioned were. 
 
 Evan Thomas This is a bonneted Clanny. It is safe in strong, 
 currents. 
 
 Marsaut lamp, which is a Clanny with three gauze caps. 
 
 Grays' Lamp is of the Eloin type. 
 
 Mueseler, with a shut off. 
 
 A lamp that has stood severe tests, which gives a good light and 
 is self extinguishing in an explosive atmosphere is the Thornebuny 
 Safety Lamp. 
 
I6f 
 
 Before Davy's discovery, a steel mitt, invented by Spedding in 1740 
 which gave light by means of the sparks produced by a steel disc 
 revolving in contact with a flint was used. Explosions were however 
 traced to its use. 
 
 Attempts have been made to use phosphorescent bodies like calcium 
 sulphide and it is said that in S. America fire flies have been employed 
 by miners. 
 
 For ordinary lighting, petroleum is sometimes used. It is 
 cheap and in a pure still air gives a good light. The necessity of 
 using glass chimneys or even of clock work to cause a draught is ob- 
 jectionable. Petroleum lamps can therefore only be used in special 
 places. 
 
 Air forced through gasoline by a clock work arrangement gives a 
 good light. 
 
 In some mines at the bottom of a shaft and along main levels, gas 
 is employed. At Duffryn in S. Wales, the gas from a " blower " was 
 collected and used on the surface. 
 
 Electric Lamps. Electric incandescent lamps have been used 
 at certain collieries in England and again in certain gold mines in 
 Victoria One H. P. is required for 8 or 10 lamps each 20 candle 
 power. 
 
 Portable electric lamps have been invented for working places, as 
 for example. 
 
 1. A Geissler tube illuminated by a Bunsen cell and aRuhmkorff 
 coil. 
 
 2. An incandescent lamp illuminated by six or more small 
 bichromate elements. 
 
 3. An incandescent lamp illuminated by small accumulators. 
 Mr. Swan's lamp weighs in all about 9 Ibs. and measures "j)4 in. by 
 4^ in. It gives a light of 2 or 3 candle power and burns II hours. 
 A 5 H.P. dynamo will charge 300 of these lamps at one operation. 
 
 Other electric lamps are Brist5l's portable safety lamp. Pitkin's 
 portable batteries and hand lamps. Cathcart, Peto and Radford's 
 lamps. Woodhouse and Rawson's lamps. These lamps usually 
 employ secondary batteries. They weigh from 2 to 9 Ibs.; give a light 
 of from i to 4 candle power aud burn from 4 to 10 hours. 
 
162 
 
 Fleuss Lamp. la the Fleiiss lamp the combustion is supported 
 by a special supply of oxygen which drives the flame of a spirit lamp 
 against a ball of lime. 
 
 Aerophores are practically air tight bags containing about 12 
 cubic feet of air which can be carried on the miner's back. The air is 
 used for respiration and to keep a lamp alight, as for example, after an 
 explosion. In the Denayrouze form, the air is compressed to 300 or 
 350 Ibs per square inch. 
 
VENTILATION. 
 
 Necessity for Vonf Elation. That there is proper supply of 
 air to a Mine is a point which must be attended to by every Mining 
 Engineer. 
 
 Should the ventilation be insufficient the health of the workmen 
 will be impaired. In many districts especially where mining operations 
 are conducted on principles which are more or less primitive, evidence 
 of this may be seen in the sickly appearance of the Miners. In other 
 districts the same result, although not directly exhibited in the indivi- 
 dual, is seen in the statistics of the death rate and the cost of out pitt, 
 for men can neither work so well, nor live so long, in a vitiated 
 atmosphere as they can in one where the air is plentiful and pure. In 
 this way we see that the proper ventilation of a mine, becomes a 
 means of lessening expense. It is also the means by which explosive 
 gases like those which emanate from so many of our coal mines, are 
 swept away, and sudden destruction of life and property are conse- 
 quently avoided. Also in mines where Gunpowder and other explo- 
 sives are used for blasting purposes, a quantity of smoke is invariably 
 produced, which if not rapidly swept away becomes a serious impedi- 
 ment to the men in returning to their work, thus causing delay and 
 consequently another source of expense. For reasons such as these, 
 but more especially perhaps to avoid the loss of life, many governments 
 have drawn up rules to insure proper ventilation in mines. Thus in 
 certain parts of the United States, it is provided that air shall be 
 supplied at the rate of 55 cubic feet per second for every 50 men. 
 
 Where much fire damp is present 70 cubic feet may be required 
 per minute per man or 53 cubic feet per ton of coal extracted in 24 
 hours. 
 
 Causes vitiating tle Air of Mine. The goodness or 
 badness of the air in a mine depends to a great extent upon its 
 composition. An average analysis of air in the climate of England, 
 is as follows. ^.,i 
 
i6 4 
 
 {Nitrogen, 77-95 per cent. 
 Oxygen, 20.610 
 Water, 1.040 
 Carbonic anhydride, 04 1 
 
 Of these constituents which are mechanically mingled together, 
 oxygen the chief supporter of life and combustion, is the most impor- 
 tant. If by any means it is diminished by only one per cent, the 
 remaining air is no longer fit to be breathed. If it is reduced by two 
 per cent, it is only just capable of supporting the flame of a candle, 
 and if four per cent is taken away a lamp will refuse to burn, whilst 
 air with five per cent less oxygen than that contained in the ordinary 
 atmosphere can not be breathed. 
 
 Not only is air vitiated by the withdrawal of oxygen, but it is 
 also vitiated by the addition of various deleterious gases. The most 
 important of these are as follows. 
 
 Carbonic anhydride. CO% S.G. 1.529. In the ordinary 
 atmosphere this gas exists in traces. One of its chief sources is from 
 respiration. Air which passes through the lungs of a man loses from 
 3 to 4 per cent of its oxygen, nearly all of which is exhaled in the 
 form of carbonic anhydride. For an ordinary individual it is calculated 
 that 15 cubic feet of air per minute would be sufficient, but for a person 
 actively engaged it has been estimated that nearly four times this 
 quantity would be required. Accepting this latter estimate of 60 cubic 
 feet per minute as being a liberal allowance for a working miner, and 
 that ^/i per cent of this quantity is converted into carbonic anhydride, 
 we have each man producing 2.1 cubic feet of this gas per minute. 
 A horse produces about 6 times this quantity. This gas is also formed 
 by the action of almost any feeble acid upon carbonates. During 
 processes of fermentation and by the oxidation of organic matter in 
 solution, whenever any body containing carbon is burnt, carbonic 
 anhydride is also obtained. 
 
 Angus Smith estimated that the burning of two candles produces 
 about the same quantity of carbonic anhydride as one man would 
 produce during an equal interval of time. Andre however gives 2.5 
 cubic feet as being produced per hour by the burning of a candle, 
 which is about the same quantity as that which is produced by the 
 gnition of I Ib. of blasting powder. 
 
i6 5 
 
 When mixed with air it forms one of the principal constituents 
 of choke damp, a mixture of the deleterious gases which result from the 
 explosion of carburetted hydrogen or fire damp. Choke damp is also 
 known by the names black damp, after damp, stythe &c. 
 
 In coal mines especially in those where lignite is worked it is 
 often found in quantity, but in other mines it occurs but seldom and 
 then only in traces. 
 
 In the concentrated form it is irrespirable, producing spasm of the 
 glottis. If the proportion of the gas in the air reaches 8 to 10 per 
 cent lights refuse to burn. This power of extinguishing a light 
 affords a test for its presence when in quantity, but it must be borne in 
 mind that it is quite possible for a light to burn in an atmosphere 
 containing a sufficient quantity of this gas to cause death. Three to 
 four per cent of it will act as a narcotic poison, and even smaller 
 quantities are very injurious. 
 
 In wells where CO* has accumulated men have lost their lives. 
 At Pontgebaud in S. France machines could not keep it out. In 
 Auvergne 17 cubic feet of this gas have escaped per minute from a 
 surface of 10 feet and in another 1 100 cubic feet in 10 minutes. 
 
 In the air from mines Dr. Angus Smith found on an average as 
 much as .78 per cent, and in several extreme cases as much as 2 per 
 cent of this gas. If it is necessary to enter an atmosphere containing 
 this gas, as for instance after an explosion, Graham has suggested that 
 the mouth and nostrils should be covered with a cloth containing a 
 layer about I inch thick of moist lime and crystallized sodic sul- 
 phate, such a layer being porous enough to allow of respiration, whilst 
 the lime absorbs the carbonic anhydride. 
 
 The power of this gas to extinguish flame has been applied by 
 Sir Goldsworthy Gurney to extinguish conflagrations, such as those 
 which occasionally break out in coal mines. In such cases all entrances 
 to the mine excepting two were closed. One of these was used for 
 the entrance of the gas, and the other for its exit. The gas was 
 produced either by forcing a current of air over a furnace in which 
 coke and charcoal were burning or else by acting on carbonate of lime 
 with sulphuric acid. This was forced in to the mine with jets 
 of steam, the water thus formed assisting to cool down the workings, 
 (see p. 100) 
 
166 
 
 On account of its high specific gravity CO2 will tend to accu- 
 mulate in the lowest portions of a series of workings. But it is also 
 often found to be more or less diffused through the air particularly 
 when assisted by currents of air and varying temperatures. It is easily 
 absorbed by water. The absorption is increased if the water contains 
 slaked lime. Advantage can not be taken of this property for the 
 removal of this gas, because the absorptive action has been found to be 
 too local. 
 
 Carbonic Oxide. CO. S.G. .967. This gas is often produced 
 in quantity when combustion takes place, as for instance during the 
 process of "fire setting." Like carbonic anhydride it is transparent 
 and colourless, but unlike it, it is only absorbed in small quantities 
 by water. As might be expected from its specific gravity it readily 
 mingles with air. It is very poisonous and according to Dumas and 
 JLeblcmc, if air contains only one per cent of this gas, it is sufficient 
 when breathed to cause a miserable death. Although carbonic oxide 
 is a non-supporter of combustion, a lamp may burn in an atmosphere 
 containing a sufficiently large quantity to cause death. 
 
 In small quantities it produces a trembling dizziness which is 
 followed by insensibility. Fortunately for the miner this gas is of rare 
 occurrence. It was met with at the Hetton Colliery. 
 
 te, Marsh Ctas or C'arbnretted Hydrogen. Gr. 
 
 dampf or schlagende wetter. Fr. grison. CH 4 S.G. .557. This gas is 
 sometimes formed by the spontaneous decomposition of vegetable 
 ; matter beneath stagnant water. From this it has been called marsh 
 gas. By processes of natural distillation it is produced and given 
 off from many coal seams where you may often hear it escaping 
 with a low hissing sound. Sometimes it is given off with great 
 violence, having evidently been under pressure. Mr. Lindsay Wood 
 observed at Boldon a pressure of 461 Ibs per square inch. The 
 fissures or orifices from which it thus escapes are called blowers. 
 The length of time that a blower may continue to give off gas is 
 very indefinite ; it may exhaust itself in a few hours or it may 
 even continue for years. In mines where large quantities of this gas 
 are given off, it is necessary that bore holes be carried along in front 
 of the miners lest a reservoir of it should be suddenly tapped. By this 
 means it may often be slowly drained away, and the danger of a sudden 
 explosion avoided. It is especially met with in coal \vhich is soft and 
 
167 
 
 friable. It occurs but seldom in brown coal. The largest quantity 
 of gas is given off from newly made openings or from freshly broken 
 coal. But although the quantity which is given off continually tends 
 to decrease, it will slightly vary with the atmospheric pressure, the varia- 
 tion of a ventilating current, the increasing of the temperature of the 
 mine. Owing to its lightness it tends to rise towards the highest 
 workings, and almost invariably large quantities of it will accumulate 
 in the goaf. It is estimated that the air space in gocrces is one sixth 
 of the volume of the coal removed. From these places it escapes in 
 quantity by any variation in pressure. 
 
 As to whether there are large accumulations of gas in a bed from 
 which it is known to be given off, depends largely upon the geological 
 nature and position of the seam and the surrounding rocks. Some- 
 times a fault may act as a reservoir in which to store the gas, but on the 
 other hand it may act as a canal to drain the gas away. This draining 
 away of the gas may also occur when the surrounding rocks are 
 wanting in compactness, or when the seam reaches up to the surface 
 of the ground &c. 
 
 This gas is not only found in the coal, but also in the shales which 
 surround the coal. In districts where substances like Naphtha and 
 Asphalt are found it is likely to occur. In one or two instances it has 
 been found in salt and metal mines, but such cases are rare, carburetted 
 hydrogen being a gas which is essentially peculiar to coal mines. 
 
 In metal mines it has been met with in the Hartz, in Flintshire, 
 Montgomeryshire : Okel Tor in Cornwall, at Lead Mines in Derby- 
 shire, at Silver Islet. It has also been observed in iron mines. 
 
 It is a colourless inodorous gas, a non-supporter of combustion, but 
 itself inflammable, burning with a blue flame. %<& 
 
 When mixed with air, with which it is easily diffused, it constitutes 
 "fire damp " an explosive mixture often met with in many coal mines. 
 
 If 3 volumes of carburetted hydrogen are mixed with 30 volumes 
 of air, its presence is indicated by the flame of a lamp becoming long 
 and thin. From appearances of this kind, as for example by the 
 formation of a blue halo round the flame of a candle, the separation 
 of the flame from the wick to form a 'top' or 'cap] the miner receives 
 warning of its presence. At one time to test whether gas of this 
 nature was present in a mine, special men were employed, who before 
 
1 68 
 
 the entrance of the workmen, advanced cautiously towards the danger- 
 ous places holding out before them a small thin taper. If any change 
 in the flame was observed to be taking place they cautiously withdrew. 
 Now the miner is warned by the enlargement of the flame in his safety 
 lamp, which he then carefully extinguishes, either by drawing down 
 the wick, or else by plunging it into water. 
 
 At the Oaks Colliery, Barnsley, gas suddenly came out along a 
 length of 50 yards. All the Stephenson's lamps were put out. Davys' 
 lamps became red hot but were extinguished by drawing down the 
 wicks. The return air did not go over the furnace and in consequence 
 of these precautions there was no explosion. 
 
 When the proportion between gas and air is as I : 12 a weak 
 explosion will take place, but with the proportion of about I : 8 a 
 violent explosion will occur. With the ratio I : 5 the explosion is 
 more moderate, and with I : 3 all explosive power is lost. 
 
 The result of a powerful explosion is represented as follows : 
 20 vols of air 2 vols of gas " after damp" 
 
 8 N 2 + O 2 4- CH 4 = 8 N 2 + CO 2 4- 2 H 2 O. 
 
 Not only has the production of after damp or stythe proved fatal 
 to those in the immediate vicinity of an explosion who may have been 
 fortunate enough to have escaped the effects of mechanical violence, 
 but also to others who have ventured to their assistance, or who may 
 have been engaged at work in some portion of the mine to which this 
 deleterious mixture has been subsequently carried. 
 
 By looking over a series of analyses of the gases which escape in 
 coal mines, it seems that we may obtain mixtures of very variable 
 compositions. We have generally from 77 to 98 per cent of carburet- 
 ted hydrogen, a small percentage of oxygen, from .1 to 7 P er cent of 
 carbonic anhydride, from .5 to 17 per cent of nitrogen and a small 
 quantity of aqueous vapour. 
 
 Sulphuretted Hydrogen. H 2 S. S.G. 1.19. This is a trans- 
 parent colourless gas, which is easily recognized by its disgusting 
 odour. When concentrated, it is highly poisonous. With 1500 times 
 its bulk of air it is fatal to birds, and with 250 times its bulk, to larger 
 animals, like horses. It takes fire at a low red heat. It is formed 
 
169 
 
 spontaneously by the action of decaying animal or vegetable matter 
 on a soluble sulphate. It is also formed by the explosion of gun- 
 powder. Although explosions are on record as having been caused 
 by this gas, it is of rare occurrence, and it is only in old workings, 
 and rarely even there, that it is found in any quantity. It occurred 
 in Collieries at Whitehaven. 
 
 Sulphurous Anhydride. SO?. S.G. 2.24. This gas which is 
 often emitted from the craters of volcanos, is produced when sulphur 
 is burnt. It is irrespirable and non-inflammable. It is produced whe- 
 never gunpowder is exploded. 
 
 Ammonia, H 3 N. S.G. .59. This gas is formed by the spon- 
 taneous decomposition of animal matter, such as the excrement 
 of animals. 
 
 Arsenic and Jlerciiry. In mines where these metals are 
 worked, their vapours are sometimes produced. Vapours of arsenic 
 are easily removed by ventilation, but the removal of those of mercury 
 is more difficult. 
 
 l>tist, Aqueous Vapour Ac. In addition to the above men- 
 tioned gases, the air of a mine may be rendered impure by the addition 
 of various mechanical impurities ; thus for instance we often find that 
 in coal mines, and especially in those which are very dry, dust is very 
 plentiful. This is naturally a check upon the free respiration of the 
 workmen, and should an explosion take place in an atmosphere thus 
 charged, the effects are considerably intensified. Galloway has 
 shown that an explosion may be caused by coal dust and air. The 
 danger resulting from coal dust depends upon its fineness and on its 
 inflammability. 
 
 If the atmosphere of a mine is charged with aqueous vapour, and 
 more especially if this be accompanied with a high temperature, ill 
 effects will be produced not only upon the workmen, but also upon the 
 materials of the mine. 
 
 Determining: the presence of Various Oases. The 
 
 presence of various gases of a deleterious nature in the workings of a 
 mine, is to a careful observer, evidenced by many appearances. The 
 health of the workmen, the way in which the lights burn, how the 
 timber stands, and many other signs, often indicate the presence of a 
 
170 
 
 greater or less quantity of obnoxious gas. When the quantity of any 
 gas is large, its effects are more decided. Sometimes lights are 
 suddenly extinguished, at other times explosions take place. 
 
 When air is not fresh and pure, either from the want of oxygen, 
 or by the addition of deleterious gas, the flame of a lamp or candle, 
 instead of being bright and clear, becomes smoky and sooty. Should 
 fire damp be present, it burns blue ; if carbonic anhydride is present, 
 it may be extinguished. 
 
 One of the older plans to determine the presence of explosive 
 gases in a mine, was as has already been mentioned when speaking 
 of Carburetted Hydrogen, to employ special men to inspect the sus- 
 pected districts by means of lighted tapers. 
 
 Another but not altogether practical plan which has been sug- 
 gested is to have an electric circuit, broken at many points, running 
 through the mine. By sending a current, it was possible at such 
 places to cause sparks to pass, and thus ignite any explosive gases 
 which might be present there. Although danger to the workmen 
 might be thus avoided, the danger to the mine was too great to 
 warrant its application, excepting under peculiar conditions. 
 
 The Tiirqiiau Detector. To determine the presence of fire 
 damp, Turquau a Frenchman, constructed an alarum, the stop of which 
 was held by a string dipped in Saltpetre passing through the gauze 
 of a safety lamp. Before an explosion took place, the gas ignited in 
 the inside of the lamp, the string was burnt and the stop set free. 
 The noise of the alarum gave notice to the miners who had at once to 
 quickly leave the mine. 
 
 Osmoscopes. A number of instruments have been constructed 
 to take advantage of the diffusion of gases. 
 
 One form arranged by Ansell, is that of a bent tube, terminated 
 at one end by a cup the top of which is covered with a lid or diaph- 
 ragm of burnt clay or marble. At the other end there is a small 
 globe, running through which there is a metal screw. This tube is 
 filled with mercury which is in connection with one end of an electric 
 circuit, the other end of which terminates in the above mentioned 
 screw. If such an instrument as this be placed in an atmosphere of 
 explosive gas, the gas will by diffusion pass more quickly through the 
 marble or clay diaphragm than the air which is inside, can escape. 
 
The consequence of this is that the mercury will be forced up the 
 branch of the tube until it reaches the screw. The circuit being com- 
 pleted an electric bell will be set in action and the miners warned. 
 
 If the point of the screw be placed very near the surface of the 
 mercury the warning will be given very soon. In this way, and also 
 by altering the nature and thickness of the diaphragm the action of the 
 instrument may be varied. 
 
 Another form consists of a bent tube passing through a cork 
 covered with sealing wax into the interior of a porous cell. By 
 diffusion, explosive gas enters the cell more quickly than the air escapes, 
 and water is forced up one arm of the tube. On the other hand, 
 should gas like carbonic anhydride be present, the air will come out 
 quicker than this dense gas can enter and the coloured liquid will rise 
 in the other arm. 
 
 Instruments of this type when suddenly immersed in an atmosp- 
 here which has a density different to the air they contain, work satis- 
 factorily, but when the outside gas accumulates slowly as in a mine, 
 osmosis is sufficiently rapid to keep the pressure inside the instrument 
 practically equal to that outside and therefore as fire damp detectors 
 these contrivances are useless. 
 
 A Whistle I>etector. Prof. George Forbes has devised a 
 whistle the note of which varies with the density of the gas in which 
 it is sounded. 
 
 A Balloon. A small balloon floating in mine gas will exert 
 more or less force upon a spring holding it captive according to the 
 greater or less density of the atmosphere in which it floats. 
 
 In consequence of diffusion the value of such an arrangement 
 would be quickly destroyed. 
 
 The Barometer and Thermometer. The evolution of gas 
 at a mine, especially from goaves, ought certainly to vary with 
 atmospheric pressure, the greatest quantity escaping when the 
 barometer in low. This is so far recognized that the Mines 
 Regulation Act demands that a barometer and thermometer be 
 placed near the entrance of a mine. That some engineers have 
 failed to recognize the value of these instruments may be because 
 they have only had experience at mines which are not sensitive 
 it being exceedingly probable that for the same reason that 
 
172 
 
 it is only certain volcanoes and springs which show a close relationship 
 with fluctuations in atmospheric pressure, it may also only be at certain 
 mines where changes in the weather are closely connected with the 
 giving out of gas. For a mining engineer to take full advantage of 
 barometric changes he should be able to foretell such changes. To 
 accomplish this a mining district requires to be in connection with- a 
 Meteorological Bureau and receive the same information that is 
 furnished to sea ports. The use of the thermometer and hygrometer 
 in conjunction with the barometer are obvious. 
 
 Earth Tremors and 3Iine Cas. Several writers have drawn 
 attention to the relationship of earthquakes and colliery explosions, 
 while committees have been formed to determine whether there 
 is a connection between the escape of gas and earth tremors. In 
 England the instruments employed only recorded earthquakes. In 
 France tromometers have been employed to record earth tremors but 
 it is the author's opinion that none of the experiments were of a nature 
 likely to yield the best results. The instruments required are those 
 which record minute rapidly recurring earth tilting and these have 
 hitherto only be used in Japan. Earth pulsations may be regarded as 
 similar to the swell on an ocean. They are closely connected with 
 barometrical changes, they outrace the wind and to determine whether 
 they are connected with the escape of fire damp would be a legitimate 
 investigation. 
 
 Lamp Detectors. Pieler's alcohol lamp is a practical fire 
 damp detector, the flame being very sensitive. In Livings' apparatus 
 the light from two incandescent platinum spirals, one being in the air 
 and the other in the mine gas, are compared by a photometer. 
 
 Swan's fire damp indicator acts on the principle that if a mixture 
 of air and fire damp is burnt the volume of the mixture is diminished 
 in proportion to the percentage of fire damp present, pressure and 
 temperature remaining constant. The apparatus consists of a com- 
 bustion tube inside which there is a platinum spiral which can be 
 heated by the current from a battery. The diminution in volume is 
 determined by the rise of liquid in a gauge tube. 
 
 Maurice's fire damp indicator works on similar principles. In 
 Murday's fire damp detector, two platinum wires are heated by a current. 
 One is exposed to the air of the mine and if gas is present it is more 
 highly heated than the other which is enclosed in an air tight cylinder. 
 
173 
 
 The result is a differential expansion, and this actuates a pointer which, 
 may be used to ring a bell. 
 
 Avoidance of the accumulation of deleterious Gases. 
 
 From what has been said of these various gases and vapours it will be 
 seen that their development and accumulation may to a great extent 
 be avoided by careful attention to the ordinary management of a mine. 
 
 To keep the air of a mine pure, the mine itself should be kept 
 pure ; bad timber, putrescible and excremental matter should be 
 removed, the water channels should be kept clean, smoking and all 
 unnecessary burning of material should be avoided. All old workings 
 where bad gases may accumulate should be carefully closed. To do 
 this it is well, where possible, to build either a stone, or else a brick 
 and mortar wall, which may then be covered with asphalt. It is also- 
 advisable to work regularly for if this is not done it will often be found 
 that many of the workings during the absence of the workmen gradu- 
 ally become filled with gas. 
 
 In sinking shafts and other special works it is sometimes found 
 that gas which only accumulates slowly may be destroyed by leaving 
 lighted lamps which decompose the gas as it is formed. 
 
 Various chemical means for destroying carburetted hydrogen 
 and other gases have been tried, but chiefly on account of their local 
 action, the nature of the resulting compounds, and the expense, these 
 do not appear to have attained any great success. 
 
 Dust may be kept down by sprinkling crude salt in the roadways 
 or by watering them. 
 
 Avoidance of Explosions due to Gas and Dust: The 
 
 danger of explosions due to the ignition of gas or dust may be mini- 
 mized by the use of safety lamps, the firing of charges by electricity 
 or friction caps, and the use of explosives incapable of causing flame. 
 Ordinary dynamite in holes stemmed with dust has given a flame 95 
 feet in length and all high explosives act similarly. The Austrian 
 fire damp Commission recommend the use of Soda-wetter-dynamite, 
 which is a dynamite containing 32 per cent of crystallized carbonate 
 of soda. Roburite, Securite, Carbonite &c. have also low temperatures 
 of explosion (see p. 61). The same Commission also suggest that for 
 safety the return air should not contain more than 1)4 per cent 
 
174 
 
 of fire-damp and ^ per cent of carbonic acid, and that the air in the 
 mine should be frequently tested with a Pieler lamp. 
 
 Expulsion of Bad Air, and supplying- of Fresli Air. 
 
 In most mines and especially in collieries it is found impossible to so- 
 far check the formation and accumulation of bad gases that a systematic 
 ventilation is unnecessary. At the end of levels, in small pits tlie 
 miner will often remove an accumulation of bad air by waving to and 
 fro a branch of leafy twigs or his jacket. This however is a method 
 of ventilation which can only be applied to openings which are not 
 of large extent. More generally however, in order to obtain a current 
 of air through the workings of a mine we have to depend upon the 
 relative positions of various openings and the judicious opening or 
 closing of levels, or else to rely upon the action of some machine or 
 contrivance by which a current of air produced artificially may be 
 either drawn or forced through the various passages which we wish to 
 ventilate. This leads 1o the consideration of the two principal methods 
 by which a mine may be ventilated, namely natrirally or artificially. 
 In some cases a mine is altogether ventilated by either one or other 
 of these methods, and sometimes by the two combined. 
 
 Natural Ventilation. The natural ventilation of a mine 
 depends to a large extent upon the difference in temperature above 
 ground and beneath. 
 
 One cause producing this is the natural temperature of the earth.. 
 At a sufficient depth to escape the effects of superficial changes of 
 temperature, the rate of increase is about 1 for every 50 feet of descent. 
 In volcanic districts this gradient may be steeper. 
 
 This temperature is increased by the burning of gunpowder, by 
 lights and by breathing of men and animals. In some mines it is 
 augmented by the burning of combustible gases, while in mines like the 
 copper mine of Beshi in Shikoku, by chemical decomposition. At 
 this latter place even at the entrance to the mine, there is a tempera- 
 ture of 95 F. In the lower levels of the Comstock Lode the water 
 has reached 170^. 
 
 In many cases these natural temperatures are sufficient to produce 
 a continuous current of air, but in other cases, either from time to time, 
 or else continuously they will require more or less artificial assistance. 
 
 We find examples of natural ventilation in the hilly lands of 
 Devon, Cornwall and in the Midland Districts. 
 
175' 
 
 Nicholas Wood gives the following instance of natural ventilation. 
 
 In the Seaham Collieries, Hetton Seam, a shaft 360 fms. drifts 1 
 336' long. Diam: of pit 14'. Temp, on bank 44, at bottom of down- 
 cast 49." At base of upcast 52^. The result was 7002 cubic feet of 
 air per minute. 
 
 At the Tythe Pit 672 feet deep. Surface Temp. 43; at the bottom 
 of downcast 45 ; the return air 63. This gave 36,564 cubic feet per 
 minute. . _- 
 
 When air is heated it expands, becomes lighter and consequently 
 tends to ascend, whilst the cooler and denser air sinks down to take its 
 place. If we imagine a tall chimney to represent the shaft of a mine, 
 the entrance to which is represented by an adit level, we see that just 
 as the fire in a furnace produces an upward draft of air in the chimney, 
 so would any internal heat of a similarly arranged mine also produce a 
 current of air through its adit and up the shaft. 
 
 It A B is a shaft and B C is an adit. So long as the air in the 
 mine is of the same temperature as the air outside there will be a 
 column of air A B in the shaft of the same density as an imaginary 
 column D C vertically above Con the outside, and the two will there- 
 fore balance each other. However should the air in the inside of 
 the mine become warmer than that outside, the column A B in the 
 shaft will be lighter than the column D C on the outside and will 
 therefore be outweighed by it, and a current of air will set into the 
 mine at C and come out at A. 
 
 In this case the shaft of the mine acts like the chimney. It may 
 however happen that the air in the mine will be cooler than the air 
 outside, in which case A B being heavier than D C, the column of air 
 outside, in which case A B being heavier than D C the current of air 
 will enter at the top of the shaft A and find an exit at C. t 
 
 Force of a Ventilative Current. To determine the force 
 which produces the ventilating current we must determine the differ- 
 ence in weight between the column of air in the shaft, and that over 
 the mouth of the level. This difference which is the moving force, is 
 usually measured by what is called the Head- 
 
 The head is the height of a column of cold air whose weight is 
 equal to the above force. 
 
1 7 6 
 
 If T be the mean temperature of the shaft, and t that of the air 
 outside, and if T is less than /, then the head in feet equals, 
 
 t + 273 I + a t 
 
 whereas if T'be greater than / then the moving, force or head equals, 
 
 T + 273 ~i + a T ' 
 
 In both these cases H equals the depth of the shaft or AB or CD of 
 the preceding supposition, and a = . 00377 or ^-'-^ this being the incre- 
 ment produced by an elevation in temperature of one degree centigrade 
 in the volume of gas at zero under a constant pressure. 
 
 In these expressions the head \s expressed as a column of air so 
 many feet in height. The same column might be expressed as a 
 column of mercury or of water so many inches in height. 
 
 Instead of considering the case of a mine which is ventilated by 
 means of a shaft and a level, we consider the case of a mine which is 
 ventilated by means of two shafts, one of which called the upcast, being 
 used for the exit of the air, and another called a daumcast for its 
 entrance, we arrive at similar result. 
 
 Farther, we observe that the greater we make the difference 
 between the temperatures in the two shafts, that is, between T and t, 
 the greater will be the moving force producing a ventilating current. 
 
 * i. Outside there is a column of air //"of a temperature t. 
 
 2. In the shaft there is a column of air //of a higher temperature T. Let 
 Hi be the height of the air in the shaft when at OC. 
 
 Then h + a Th = H 
 
 H 
 
 h= i+aT 
 The height in the shaft at f> will therefore be, 
 
 ^ + Z- 
 
 \-aT^ i + a 
 
 and the difference between this and the column // outside, which is of the same 
 temperature is, 
 
 H H I * a l or Ha ^~ '*)- head in feet. 
 i + a/ i + Y 
 
177 
 
 Because in a wet shaft, the air is generally cooler than in a dry 
 one, such a shaft would usually be the one chosen for a downcast. It 
 is for this reason that the shaft in which the pumps are placed is the 
 one which is used for the downcast. 
 
 Measurement of Pressure. From readings of the thermo- 
 meter we see that it is possible to calculate the pressure of air produc- 
 ing a ventilative current. This is however usually observed directly 
 by means of a Water Guage which is a bent glass tube, in the bend 
 of which there is a small quantity of water. It is open at both ends. 
 
 By placing this in such a position, as, for instance, with one of its 
 ends through a hole in a stopping, the current of air, passing in at the 
 opening in one of its arms, forces the water up in the other. By 
 graduations upon this latter arm, the pressure is read off as so many 
 inches of water. We also see that barometric readings might indicate 
 the pressure in millimeters of mercury. 
 
 If a barometer were placed near the top of an ttpcast and another 
 at the entrance to an adit, this latter would stand higher than the 
 former, and the difference between them would indicate in millimeters 
 of mercury a portion of the moving force. If we had an upcast and a 
 daamcast situated near the same level, barometers placed near the 
 entrances to these ought continually to give the same readings. They 
 would however differ from the readings of barometers placed at the 
 bottoms of two such shafts, and these latter would again differ from 
 one another, the one placed at the bottom of the upcast standing higher 
 than the one at the bottom of the downcast. 
 
 As readings on a mercury column due to great differences in 
 Head are only small, and also as they vary not only with the pressure 
 but also with the velocity and temperature of the air, the barometer can 
 not be so successfully employed as the Water Guage in the measure- 
 ment of pressure. Anemometers of various descriptions also indicate 
 pressure but they are usually employed to measure velocity. 
 
 Velocity of a Current. If a body has fallen from a height h t 
 
 it has a velocity which is equal to ^/2gh. It happens that the same 
 formula gives us the velocity of a fluid : that is, if air is flowing from 
 one place to another, the difference in pressure between the two 
 places being measured as a head h, then the velocity v with which air 
 flows to the place of lower pressure is approximately ^/2- r /} 
 
 ' 
 
1 7 3 
 
 The head h is the height of a column of air whose weight is the 
 difference in pressure between the two places. 
 
 Having given the head, from this expression the velocity may be 
 calculated. It may also be remarked that if the velocity has been 
 
 V 1 * 
 observed, the head, which is may be calculated. 
 
 2g 
 
 Sometimes it will be convenient in the formula v = */ zgh, to 
 
 substitute for h its value Ha ( ) (see p. 176) and we obtain. 
 
 v I -f- a T I 
 
 v = ( 2g Ha 
 
 I + a T< 
 
 To observe the velocity of a current anemometers are used. 
 These are of two kinds, 1st those with a rotary motion, and 2nd those 
 which act by the pressure of the passing air against a swinging vane. 
 
 Amongst the former, Biram's is perhaps one of the most common 
 which is used in England. It consists of 12 small sails upon which 
 the current of air acts like the air upon the sails of a wind mill. The 
 number of revolutions which are made are registered by gearing in 
 connection with a counter. A delicate form of this instrument is made 
 by Casella. In France and Belgium an instrument constructed on a 
 similar principle is used. It is known from its originator as Combes' 
 anemometer. These and other instruments chiefly differ from each 
 other in the number and nature of their sails, the great object being to 
 obtain one which, whilst being self registering, is sufficiently frictionless 
 and delicate to move in a light current. By the use of an empirical 
 formula the velocity of the current of air is deduced from the number 
 of revolutions indicated by the counter. 
 
 In the second class of instruments we have Dickinsons anemometer. 
 This consists of a small rectangular frame swinging on an axis. From 
 the number of degrees it is deflected when held at right angles to the 
 current, the velocity of the air is determined. 
 
 The velocity of air in a level may also be measured by observing 
 how long some light material like smoke takes to travel over a given 
 distance. This smoke may be produced by the explosion of a small 
 quantity of gunpowder. First the time of the explosion is noted and 
 subsequently the time at which the smoke arrives at some given point. 
 
J79 
 
 From these observations the velocity is readily deduced. In making 
 such observations the two points of observation ought to be in a 
 straight part of the level so that the person who records the arrival of 
 the smoke may have been able to note the time at which the explosion 
 took place. The section of the level ought also to be regular or there 
 will be variable velocities at different points along its length. Also it 
 may be observed that varying results will be obtained according as we 
 note down the arrival or the final disappearance of the smoke. 
 
 A still rougher method of approximately finding the velocity 
 of air in a level, is to walk along the level in the direction of the 
 current carrying a lighted lamp or candle. If you move slower than 
 the current, the flame is blown and inclined before you ; if you walk 
 faster, it is blown back towards you ; whilst if you walk at the same 
 rate it will remain vertical, and your rate of walking measures the 
 velocity of the current. In such determinations as these it is well to 
 take a mean of several observations. 
 
 The velocity of air will vary at different points in the same section 
 of a level. It therefore must be measured at several places and a mean 
 velocity calculated. When once calculated for a given section, as the 
 ratio of the mean velocity to the velocity at any point in the section is 
 constant, subsequent measurements may be made at one selected point 
 in the section. 
 
 The Equivalent Orifice (Murgue). 
 
 Q = quantity of air in cubic feet per second passing through the 
 opening (i.e. circulating round thejmine). 
 
 h a = ventilating pressure in feet of air column required to over- 
 come the resistance of the mine. 
 
 A = opening in a thin plate in square feet (i.e. equivalent orifice). 
 K = coefficient of contraction of orifice (i.e. Vena contracta = .65). 
 
 Then Q = V ' 2gh a X .65 A 
 
 A = 
 
 If Q is in thousands of cubic feet per minute and ha in inches of 
 water gauge, 
 
i8o 
 
 T (~) A *\/ h I O \2 
 
 U&ri-v 10 = -^- and * a = .1369 (-^) 
 
 The average value of A for English mines is about 20 and for 
 Belgian about 8.6 square feet. 
 
 Obstructions to the flow of Air. In practice it will be 
 found that the velocity of air calculated from the head, will be greater 
 than the velocity actually observed by experiment. This is due to 
 having omitted to consider the various resistances, which the air meets 
 with as it travels along the galleries of a mine. These resistances are 
 those of friction. Obstructions and contractions, usually referred to 
 as stopping the flow by arresting its momentum, are really to be con- 
 sidered as producing large amounts of internal friction in the flowing 
 mass of air. 
 
 W T hen one body moves or slides across another, there is a certain 
 resistance to the motion which we call friction. The amount of this 
 resistance depends upon the pressure which these two bodies exert upon 
 each other. If we could imagine that a force due to the head of air 
 might be employed in sliding a body along a level, the resistance to 
 the motion of such a body would be proportional to the weight or to 
 the pressure which that body exerted on the bed over which it moved. 
 This would be solid friction. 
 
 In the case of air moving along a level under the influence of the 
 pressure caused by the head, although we know that the pressure is 
 transmitted by the air in the levels to the surfaces over which it moves, 
 the resistance is not, as in the case of solid bodies, proportional to the 
 pressure. We have here a case of fluid friction, which is independent 
 of pressure, being as great for a small pressure as for a large. 
 
 Some of the laws governing fluid motion are however evident. 
 First it will be observed that the resistance to the flow of a column 
 of air will depend upon the extent of siirface which bounds its flow. 
 
 To take advantage of this, air ways ought to be made as short as 
 possible, because a long level will offer the greater resistance to the 
 passage of air. As the rubbing surface in a level depends upon its 
 sectional perimeter, for a given sectional area we ought to make this 
 perimeter as small as possible. Thus a level of circular perimeter may 
 have a larger area and therefore allow a larger quantity of air to flow 
 along it, than a level of rectangular section with an equal perimeter. 
 
Therefore a circular level so far as the friction of air is concerned, 
 would be the best form for an air passage. Lastly, the sides of an air 
 passage ought to be made smooth, because they present less rubbing 
 surface than one which is rough. 
 
 Not only is the resistance to fluid motion dependent on surface, 
 which in a mine is measured by the length and perimeters of its levels, 
 but it is also greatly dependent upon its velocity. 
 
 As the air travels along a level we may imagine it arranged in 
 rings, those which are nearer to the sides of the level being retarded 
 more than the air in the centre. 
 
 From experiments it is found that for small velocities, the frictional 
 resistance is proportional to the velocity, for greater velocities it is 
 proportional to the square, cube, and higher powers of the velocity. 
 With the motion of water in pipes, conditions similar to those which 
 would be obtained for air moving very fast, are found to exist. 
 
 In the following formulae, which give the head of air necessary to 
 overcome friction r we suppose the friction to be proportional to the 
 square of the velocity, because this is found to agree well enough with 
 experiments upon the flow of air in mines, but it must be remembered 
 that this law is only roughly true. 
 
 Let F force of friction in Ibs. 
 
 k = is a number found by experiment. 
 
 / = length of openings traversed by air. 
 
 c = the mean perimeter of cross section of these openings. 
 
 v velocity of air in feet per second. 
 
 Q = quantity of air in cubic feet per second. 
 
 A = area of cross section in square feet. 
 
 Then F= k. L c. r-, also v = -- 
 
 Now if the friction is overcome by a head h it is overcome by an 
 urging force h. A. w, (where to is the weight of a cubic foot of air,) 
 which is the equivalent of this head, 
 
 Therefore h. A. w = k. I. c. H? 
 
182 
 
 Now is a number determined by experiments in mines where 
 w 
 
 obstructions due to timbering &c. render the conditions somewhat 
 different to those obtained for the flow along an even channel. Andre 
 gives for this constant .00066. 
 
 Augmentation of n Natural Current. All means taken 
 to augment a natural ventilation which involve additions to the 
 ordinary arrangements of the mine, may be considered as being, in a 
 greater or less degree forms of artificial ventilation. Just as in all 
 rooms to which there is an opening, there is more or less circulation 
 in the air, so it is in all mines, and as by the opening or shutting of 
 certain doors we are able to increase the draft in a room, so the draft 
 which exists in a mine may be also increased. 
 
 Towers. From what has already been said about the natural 
 ventilation of a mine, it will be seen that if the temperature in a mine 
 be different from that outside, the greater the difference in level 
 between the opening at which the air enters and that from which it 
 leaves, the greater will be the ventilation current. Where this diffe- 
 rence in level does not exist, it may sometimes be conveniently created 
 by building a chimney over one of the openings. 
 
 As the quantity of air passing out of any shaft is directly propor- 
 tional to its velocity, we see that if the temperature producing motion 
 remains constant, the quantity must he proportional to the square root 
 of the height (see page 177). 
 
 We have therefore the velocity and quantity of air varying as 
 V ' H. If we increase the length of the shaft by a tower h, the velocity 
 
 and quantity of air will be proportional to A///-J-//. And if we com- 
 pare the ratio of increase in a shaft //, and in a shaft H surmounted 
 by a tower /z, this increment will be measured by 
 
 \///+ h -Vff 
 
 VJT 
 
If H is very large, that is if a shaft be deep, it will be seen that 
 the above ratio, or ratio of augmentation, for a given chimney h, 
 becomes very small, a result which might naturally be expected. 
 
 This difference in level, in hilly districts, may often be formed by 
 driving special galleries. 
 
 Minds. In the tropics where for long periods there are constant 
 and steady winds, the pressure which these exert may be taken advan- 
 tage of, to force a current of air through the workings of a mine, by the 
 opening or closing of suitable entrances or levels. 
 
 Cowls. The action of the wind may also be taken advantage of 
 by placing over the upcast and downcast, or over openings connected 
 with these, towers terminated by moveable cowls. The cowl which is 
 over the dvivncast is so arranged that it always presents its open face 
 to the influence of the wind, in consequence of which a current of air 
 will always tend to pass down into the mine. The cowl over the 
 upcast is always in a reverse position, so that the wind as its rushes 
 past its edge, tends to drag the air from the interior along with it. 
 
 Pipe and Cap Head. This is a pipe with a moveable mouth- 
 piece placed at right angles to its length. This latter portion is above 
 ground and is kept facing the wind, whilst the pipe extends down to 
 the workings. The action is similar to the cowls on air towers, or to 
 the ventilating arrangements we see on board ships. 
 
 Air Sollars. An air sollar is formed in a level by carrying the 
 tramway on a board floor raised about 6 inches above the actual floor 
 of the level. This floor which divides the level in to two unequal 
 portions may be made air tight by covering the joints with clay. If the 
 floor of the level is not too steep, and there is not a rapid current of 
 water flowing beneath it, a current of cold air will set up the air sollar 
 beneath the floor, whilst heated air will pass out above the floor, along 
 the level. 
 
 Air Head. In the Staffordshire coal districts it is sometimes 
 customary for ventilative purposes to drive a small drift or air head 
 above a main level. With this it is connected by vertical openings 
 called spouts. The bad air from the main level ascend by these spcnits 
 into the air head which leads it away towards an ttpcaxt. 
 
1 84 
 
 Falling- Wafer. In case of an emergency water may be 
 allowed to fall into the downcast. This by cooling and also by the 
 draging action it exerts upon the air in the shaft tends to create a 
 current. In the event of an explosion or the breaking of a machine, 
 by which the ventilative currents had been deranged the turning of a 
 properly arranged water cock might be used to restore the ventilation. 
 
 By Cooling the Air. We see that just as air maybe caused to 
 ascend by its being heated, so it may be caused to descend by having 
 been cooled. Apparatus for assisting in the cooling and the ventilating 
 of a mine have been designed on this principle. The general character 
 of these machines is that of a large still, where air which is the 
 material to be cooled, instead of flowing through the worm, flows 
 downwards through the vessel in which this is contained. Through 
 the worm an upwards current of water is kept in circulation. 
 
 Water Trompe. This contrivance consists of a pipe usually 
 from 9 to 12 feet in length down which water falls into a closed 
 reservoir. In the upper part of this pipe there are lateral openings 
 pointing inwards and downwards. As the water falls past these open- 
 ings, it drags and sucks air from the exterior. On the upperside of 
 the reservoir there is a pipe to lead away the air which is being 
 continually entrapped. The water is kept at a level which covers the 
 orifice by which it escapes, and thus prevents the simultaneous escape 
 of the air. 
 
 The upper end of the pipe at which the water enters is slightly 
 conical. Exactly beneath the pipe in the reservoir, there is a board 
 placed above the opening at which the water escapes. This is struck 
 by the falling water which being broken up, liberates the air. 
 
 The mean average effect for such machines is given at 12^ per 
 Cent, from which it will be seen that they could not be used unless 
 water power was plentiful. Another obvious condition for the employ- 
 ment of such a machine is, that there should be every facility for 
 draining away the water from the level down to which it falls. 
 
 Furnaces and Steam Jets. It is evident that if we increase 
 the temperature of air in an iipcast we shall increase the current. For 
 this purpose jets of steam and furnaces are used. Furnaces are placed 
 sometimes at the top of a shaft, sometimes in the middle, but more 
 
i8 5 
 
 generally at the bottom, where without discussing the question it is 
 evident that they would be in the most favourable position to produce 
 the best effect. 
 
 Furnaces in .Shafts. During sinking processes, or for some 
 temporary expedient, a fire held in an iron grate is sometimes suspended 
 in a shaft for the purpose of heating the air and producing an upward 
 current. Where an opening is narrow, and where there is much 
 timber the danger of such a proceeding is obvious. 
 
 Furnaces above Ground. Sometimes the draft in an upcast 
 may be improved by making a connection between it and the chimney 
 of some of the boilers or furnaces which may be near the mouth of the 
 shaft. 
 
 When furnaces are placed on the surface of the ground their 
 action is similar to that which we should obtain by placing the mouth 
 of the shaft in communication with a chimney. 
 
 Furnace Ventilation may require 35 Ibs of coal per H.P. per hour 
 which is not economical. 
 
 Ventilation of this description may be useful in cases where the 
 workings are not deep, or in cases where we have a natural ventilation 
 which it is occasionally necessary to revive. 
 
 Furnaces under Ground. Furnaces above ground are but 
 seldom used, whilst furnaces beneath the surface are very common, 
 especially at some of the English Coal mines. Where it so happens 
 that a special shaft can be devoted to them they may be placed 
 immediately beneath it. It is more usual however to place them 80 or 
 100 feet distant, connecting them with the shaft by means of an inclined 
 level or dumb drift. This ought to be of sufficient length to prevent 
 sparks reaching the upcast. In this way annoyance to the onseffers is 
 avoided. 
 
 The smoke which comes to the top of the shaft may be carried 
 away through an inclined side drift entering the shaft beneath the 
 settle, and leading towards a chimney. 
 
 These furnaces are generally so arranged, that in case it would be 
 dangerous to allow the air which is being drawn out of the mine to 
 come in contact with the fire, they can be supplied with a special 
 branch of fresh air led to them direct from the downcast. 
 
186 
 
 Above they are covered by an arch. In order to safely protect 
 the roof from fire, this arching is sometimes made double. So that the 
 proper quantity of air shall pass beneath the fire bars, the space above 
 them may be regulated by a sliding door. On either side of the furnace, 
 arched air-ways are sometimes built. At the back of the furnace there 
 is a chamber to catch flying sparks. The average dimension of a 
 furnace is about 6 feet in breadth, by 8 or 9 feet in length. 
 
 At Monkwearmonth a furnace 12 feet wide with 3 feet above and 
 3 feet below the bars, gave 120,000 cubic feet per minute. 
 
 Sometimes several furnaces may be required. These may be either 
 arranged in juxtaposition, or be placed separately and worked accord- 
 ing to the requirements of the mine. 
 
 Over a shaft which is ventilated by a furnace, a tower may be 
 erected. In the shaft, such supports as from their position if made 
 of wood would be in danger of fire, must be replaced by iron, or else 
 by stone or brickwork. The latter is preferable, first because the 
 conduction of heat in brick work is less than it is with metal, and 
 secondly because of the heat and the gases resulting from combustion, 
 metal- work is slowly destroyed. 
 
 To supply the furnace with air taken directly from the downcast 
 naturally weakens the current which has to pass through the workings, 
 and as it may happen that only a certain district of a mine produces 
 dangerous gases, these alone are prevented from coming in contact 
 with the furnace, and some portion of the air which has passed through 
 other portions of the mine may be used to feed the furnace. 
 
 In N. France at Anzin a small shaft is sometimes sunk near to 
 the ^lpcast for the purpose of supplying a furnace with air. 
 
 Work done by Fnrnnces. As at different mines the condi- 
 tions are usually so varied, the nature and size of the mine, the 
 quantity of the coal which is used, the part played by natural ventila- 
 tion &c., it is difficult to compare the effects produced by various fur- 
 naces. To shew what has been done, it may be mentioned that at 
 Hetton Colliery with three furnaces, 190,000 cubic feet of air, and 
 with four furnaces as much as 220,000 cubic feet, have been drawn 
 out of the mine per minute. At the Haswell Colliery the velocity of 
 the air in the tipcast has been 29 feet per second. . And at Wallsend in 
 the levels underground, a velocity of 21 feet per second has been 
 
1*7 
 
 obtained by the aid of furnaces. The greatest heat in the upcast has 
 been from 145 to 180 F. 
 
 In the north of England it is considered that a furnace 6 feet 
 broad, and 6 to 8 feet long, using in 24 hours about 2 tons of coal will 
 cause a flow of from 40,000 to 50,000 cubic feet of air per minute, and 
 the water guage will shew a pressure varying from 26 ram - to 42 mm - 
 
 The average temperature of the air in the upcast, from a well 
 arranged furnace, ought to be from 150 to 160 F. 
 
 Theoretical Considerations. From page 178, we see that the 
 velocity and quantity of air passing through the upcast is proportional 
 
 to -v x Tt> that is v, varies as the square root of the difference of 
 temperature in the iipcast and d&ivncasf. If we call this difference d, 
 and the quantity of air in cubic feet per second Q 
 
 then v and Q oo \/d. 
 
 The cost of the materials whicli produce this heat depends upon 
 the increase in temperature they produce or d, and the quantity of air 
 
 which passes on \/d 
 
 therefore the cost oo *>/ d. d. or ds or v 3 . 
 
 Furnace Paradox. If we take a series of examples we shall 
 see that by doubling or trebling the temperature, we neither double 
 nor treble the velocity nor the quantity of air which passes. 
 
 The first three columns of the following table illustrative of this 
 result, are given by Burat. 
 
 Temp : of Velocity of Nos. porpotional 
 
 ascending current. to quantity of 
 
 current. fuel used. 
 
 30 43 86 
 
 40 5' 153 
 
 50 58 232 
 
 60 64 320 
 
 100 79 711 
 
 If we suppose the above numbers given by Burant to have been 
 obtained by experiment, then because the quantity of coal consumed 
 
 = 86 = i* 3 = 2J2 = 320 711 ,& $ 
 43 3 57 3 58 3 848 7<^r c *;. 
 
 r//> \< 
 
 ivt, 
 
1 88 
 
 Taking the mean of these equations, c = .00121. 
 
 For any given velocity we can now calculate a number propor- 
 tional to the quantity of coal which will be used. In the following 
 table the same velocities as those given by Burant are taken, and it 
 will be seen that the quantities of coal which are burnt, accord pretty 
 nearly with the quantities before given. 
 
 Velocity of Nos. proportional 
 
 current. to fuel used. 
 
 43 96 
 
 51 1 60 
 
 58 236 
 
 67 s 1 ; 
 
 79 596 
 
 If we make our calculations simply from the theoretical considera- 
 tions given on page 178, because v varies as *vT- t and the quantity 
 of coal varies as ^ 3 , we shall see that if we have the difference in 
 temperature in an upcast &&& a downcast represented by the first column 
 of figures in the following table, the second and third columns will 
 respectively represent the corresponding velocities which will be ob- 
 tained, and the quanties of coal which will be used. 
 
 Differences in 
 tempeiature. 
 or T t. 
 
 Nos. proportional 
 to velocity of 
 current. 
 
 Nos. proportional 
 to coal which 
 will be used. 
 
 36..., 
 
 6 
 
 216 
 
 AQ 
 
 7 
 
 94-3 
 
 64... 
 
 .. 8..., 
 
 .. <(12 
 
 Si 9 929 
 
 loo 10 looo 
 
 From these considerations it will be seen that high temperatures 
 besides rendering it impossible to use the upcast, necessitate the ex- 
 penditure of enormous quantities of fuel as compared with that requir- 
 ed to produce low temperatures or low velocities. 
 
 Employment of Steam. Very often, as for instance at some 
 of the collieries of S. Lancashire, the waste steam from an engine is 
 allowed to escape at some point in the it-pcast. In this way the air in 
 the shaft is heated and an upward current is produced. If the steam 
 which is employed for under ground engines is supplied to them by 
 
189 
 
 pipes from the surface, the radiation from these pipes also tends to 
 accelerate an upward draft. At \Yigan several experiments have been 
 made to employ steam not only to create a draft by heating the air, 
 but to act mechanically by escaping under pressure in the direction 
 of the moving current. 
 
 These were carried out by allowing 14 or 18 small jets of high pres- 
 sure steam to escape in the ttpcast. So that these should not interfere 
 with each other, a cylinder about I foot in diameter and 6 feet long 
 was placed above each. The remaining space not occupied by these 
 cylinders was carefully closed. 
 
 One of the best results was the exhaustion of air at the rate of 
 6,250 cubic feet by the burning of I Ib. of coal. In the same shaft the 
 burning of the same quantity of coal produced an exhaust of 10,650 
 cubic feet per minute. 
 
 From these experiments it seems that it would not be economical 
 to generate steam specially for ventilative purposes, but if steam is at 
 hand, as for instance from the escape of an under ground engine, it 
 may be used with advantage. 
 
 Ventilating: Pressure fcc. (Merivale). 
 
 If J\l = motive column (Ventilating pressure) in feet of air 
 
 of temperature in upcast. 
 D = depth of upcast in feet. 
 /, 7\t^ = temperature of air in downcast, upcast and returns 
 
 respectively. 
 
 P = ventilating pressure in Ibs per square foot. 
 I = height of barometer in inches. 
 VV ' = weight of one cubic foot of the return air in Ibs. 
 Q = cubic feet of air per minute in main return. 
 X = Ibs of coal burnt per hour. 
 Y = area of furnace in square feet. 
 
 Then M = D X ~~ 
 
190 
 
 W Q x Tfy. .238 x 60 
 
 14000 
 
 X say 2. 
 
 X 
 Y = roughly. 
 
 c 1.3253 X / 
 
 1.3253 
 
 T-} 
 
 I 459 + / 459 
 
 Theoretically about 150 cubic feet of air are required per Ib. 
 of coal burnt, practically 300 cubic feet. 
 
 Consumption of Fuel on Pit Furnaces 
 
 ( Trans NEL, VI). 
 
 Locality. 
 
 Depth in 
 
 Coals per/// 3 
 per hour ex- 
 cluding power 
 due to heat of 
 
 Coals per H P 
 per hour in- 
 cluding power 
 due to heat of 
 
 Quantity 
 of air per 
 mine. 
 
 
 
 mine. 
 
 mine. 
 
 
 
 feet. 
 
 Ibs. 
 
 Ibs. 
 
 cubic feet. 
 
 Thornley 5 '4 seam 
 
 556 
 
 85-5 
 
 37-5 
 
 45,756 
 
 Thornley Hutton seam. 
 
 868 
 
 162.4 
 
 57-1 
 
 26,574 
 
 Walker 
 
 q6o 
 
 
 1-5.6 
 
 44,800 
 
 Castle Eden 
 
 1038 
 
 29.1 
 
 28.3 
 
 42,326 
 
 South Hellon 
 
 1212 
 
 27.2 
 
 *5'S 
 
 132,895 
 
 Wearmonth 
 
 l8oo 
 
 69-5 
 
 7-9 
 
 70,500 
 
 Average 
 
 
 60.7 
 
 27.6 
 
 
 
 
 
 
 
 Ventilating; Machines. The various machines which are 
 used for purposes of ventilating mines may be divided into two great 
 classes. First there are those machines working backwards and for- 
 wards with the motion of an ordinary pump, and secondly those ma- 
 chines which have a rotatory motion like a winnowing machine or fan. 
 
 I>uck Pump (Harzer Wettersatz). This consists of a cylindrical 
 vessel closed at one end inverted over the end of an air pipe coming 
 up through the bottom of a second vessel partly filled with water. On 
 the closed end of the inverted vessel, and over the open end of the air 
 pipe, there are valves, both of which open upwards. By raising and 
 lowering the upper vessel it will be seen that air will be drawn up 
 through the air pipe to be discharged through the valve into the in- 
 verted cylinder. 
 
I 9 J 
 
 This up and down motion is often given by attaching the upper 
 vessel to the pump rods. 
 
 By reversing the motion of the valves, instead of exhausting the 
 air from the workings, air might be forced in. 
 
 By placing two air pipes with valves moving in opposite direc- 
 tions beneath a moving cylinder which is without a valve, air would 
 be drawn up one of these pipes and forced down another. In this 
 way bad air drawn from one point in a mine, instead of being dis- 
 charged near to the pnmp, might be discharged some distance away. 
 Small machines are i^ to 2 feet in diameter. 
 
 Mnriliaye's Ventilator. This ventilator is a more perfect 
 form of the Duck pump. If we imagine the air pipe of the Duck 
 pump to be increased until it almost fills the interior of the fixed cy- 
 linder, so that the movable cylinder has only a small annular space in 
 which to move, we shall see the general arrangement of Marihaye's 
 ventilator. On the top of the movable cylinder, which has a diameter 
 of 3.66 met - and a height of 2.6 met. there are 16 valves. 
 
 The same number of valves are placed on the end of the cylinder 
 which corresponds to the air pipe. The whole is constructed of sheet 
 iron. Two of these may be worked by one engine, which is placed 
 between them. 
 
 The useful effect is given as being from 33 to 39 per cent. 
 
 Struve's Ventilator. Struve's Ventilator consists of a large 
 chamber closed above and below, in the sides of which there are a 
 number of valves. On one side communicating with the shaft these 
 valves open inwards. On the opposite side they open outwards. 
 Inside this chamber these is a large bell like the movable cylinder of 
 a Duck pump working up and done in a chamber filled with water. 
 When this rises, the air in the upper part of chamber is compressed 
 and forced out of the valves which are on the opposite side to the 
 shaft, at the same time the air in the lower portion expands, and the 
 lower valves on the side of the shaft are opened whilst those opposite 
 are closed. When the piston descends the reverse happens. 
 
 Another form of this machine is where instead of the water cham- 
 ber, a cylinder within which there is a piston, is placed inside the 
 exterior chamber. This cylinder is held is position by supports 
 
192 
 
 from above and below. To divide the upper valves from the lower 
 ones, a horizontal partition is placed between the centre of the cham- 
 ber, and the cylinder. 
 
 These machines are usually worked in pairs by means of one 
 engine. 
 
 In this latter arrangement where there is a piston working in a 
 cylinder, it will be observed that a considerable amount of friction has 
 to be overcome which is not felt in those forms where instead of the 
 piston, there is a bell working in water. An objection which has been 
 raised against these machines is that any sudden change of motion, 
 will disturb so large a body of air that its effect may be felt in distant 
 places, and be the cause of dangerous results. It may also be 
 mentioned that the valves are apt to get out of order. Notwithstanding 
 these objections this machine has been successfully ussed at many 
 collieries, especially in S.Wales. At the Risca colliery two pistons 
 18 feet in diameter and 6 feet stsoke with a small engine and 35 Ibs 
 of steam gave 43000 cubic feet of air per minute. 
 
 The pistons have a diameter varying from 12 to 22 feet, and a 
 stroke from 6 to 8 feet. 
 
 They are capable of exhausting from 20,000 to 100,000 cubic feet 
 of air per minute. One machine gave for every Ib. of coal which was 
 burnt, 5233 cubic feet of air, with an average manometric pressure 
 of 35 mm - 
 
 Piston Machines. These consist of a rectangular or more 
 usually a cylindrical case made from wood or iron. At one end this 
 is open, and at the other end it is covered by valves. Inside this 
 cylinder there is a closely fitting piston also covered with valves. As 
 such an arrangement will be intermittent in its action, two cylinders 
 are so arranged that they work alternately. These may be placed 
 vertically and worked by means of a beam or they may be placed 
 horizontally. The efficiency of ventilators arranged on the former 
 of these systems has varied from 20 to 40 per cent, and with the latter 
 it is said that as much as 65 per cent has been obtained. One of the 
 first of these piston machines was erected in 1828 by M. Brisco at 
 Charleroi. In 1858 it was improved upon by M. Mahaux. 
 
 9Iahanx's Ventilator. Here two pistons are placed at 
 opposite extremities of a piston rod. The valves are suspended 
 
193 
 
 vertically, this being the position in which they offer the least resist- 
 ance to motion. These are large. One of these machines with pistons 
 4.9 feet diameter, gave 45,000 cubic feet of air per minute. 
 
 3fixon ? s Ventilator. This ventilator consists of a chamber, 
 at the ends of which valves are arranged as in Struve's ventilator. 
 Moving backwards and forwards in this chamber there is a large piston. 
 To lessen the resistance this is supported on wheels. At Navigation 
 Pit near Aberdare, the piston which had a stroke of 7 feet, measured 
 30 feet by 22. The valves, which for lightness are made of wood and 
 leather, measure 16 by 24 inches, and are 672 in number. Theoretic- 
 ally such a ventilator at 9 strokes per minute will gives 166,000 cubic 
 feet of air. 
 
 An objection to these machines is that there is much leakage* 
 and also that owing to the piston not being able to make a full 
 stroke, the ventilalive effect is interfered with, by the fact that 
 between the end of the cylinder and the piston there is always a 
 large space. 
 
 Centrifugal Ventilators or Fans. Fans which are used for 
 the purpose of blowing furnaces move with a high velocity and produce 
 a small current of air at a high pressure. Fans which are used for 
 mines are required to produce large volumes of air at a comparatively 
 low velocity. All these fans consist of a wheel provided with vanes 
 enclosed in a case. This has two openings one central and another 
 tangential. As the fan is revolved air enters at the former of these 
 openings and is expelled at the latter. By connecting first one 
 of these openings and then the other with a shaft, air might either 
 be forced into a mine or drawn out. The course which may be 
 pursued will depend upon the conditions of the mine. Occasionally 
 air may be forced into a mine, but the usual plan is to ventilate 
 by exhaustion. 
 
 Since early times fans with radial vanes centered round an axis 
 and enclosed in a wooden case have been used and even now for 
 temporary purposes, and in small workings they are employed with 
 advantage. By building these fans of sheet iron, and by altering the 
 form of the case, great improvements have been achieved, but the chief 
 alterations have been with regard to the position and form of the 
 vanes. 
 
194 
 
 Ventilating: pressure of a Fan \Merlvale). 
 
 H=s gross ventilating pressure (theoretical depression) in 
 feet of air column, of density of flowing air. 
 
 u = tangential velocity of fan in feet per second. 
 
 u 2 
 Then theoretically H '= 
 
 ^ s 
 
 But as H = we may say that the theoretical depression is 
 
 ^~S 
 double the height due to the tangential velocity. 
 
 With H*s above 
 
 P ventilating pressure in Ibs per square foot. 
 W G = water gauge in inches. 
 d = density of water = 1000. 
 d / = density of air = 1.2 approx. at ordinary pressure and 
 
 temperature. 
 Then P= 5.2 WG. 
 
 d W G 1000 WG 1.2 X 12 H 
 
 Jl = =r . . W Cr = 
 
 d'X 12 1.2 X 12 IOOO 
 
 The following formulae are from Mr. A. L. Steavenson's translation 
 of M. Murgue's work. 
 
 Let H = theoretical depression in feet of air column given by 
 a perfect fan if its eye were shut off from the mine 
 and atmosphere. 
 
 h a = effective depression in feet of air column ; i.e. the 
 ventilating pressure required to overcome the 
 resistance of the workings = the water gauge in 
 the fan drift. 
 
 h = useless depression in feet of air column ; i.e. the 
 ventilating pressure required to overcome the 
 resistance the air meets with in passing through the 
 fan. To obtain this the communication between 
 the fan eye and the workings must be closed and 
 the eye connected direct with the atmosphere. 
 
 Q the quantity of air in cubic feet per second. 
 
195 
 
 A = Equivalent orifice in square feet. 
 
 O = Orifice of passage in square feet ; i.e. the area of a 
 hole in a thin plate which would offer the same 
 resistance to the air that the fan offers. 
 
 k = coefficent of efficiency of fan (varying in the case 
 of well designed fans from .5 to .8). 
 
 ^ = gravity, say 32.19. 
 
 u = tangential speed of fan in feet per second. 
 
 Then H = h a + // 
 
 .65 A V 2 $ H 
 
 /^f 
 
196 
 
 And for practical calculations : 
 
 hn= 
 
 __ .65 V 2k A u 
 
 / A*- 
 
 v i + -& 
 
 Combes and Redtenbacher say, that the vanes ought to be tangen- 
 tial to the exterior circumference and make an angle at the centre. 
 Others whilst making them tangential to the exterior make them 
 radial on the interior. 
 
 It seems to us that they ought to make an angle at the circumference 
 and also at the centre, and these angles may be calculated from known 
 principles. 
 
 However it is not of any importance what is the shape of the 
 vanes of a fan, except that from considerations of friction, they ought 
 to be made as direct as possible. The angle made by the vane at its 
 inner edge with the direction of motion must be such that the air 
 enters the vanes without shock. That is, if A is the area in feet of 
 all the openings round the inner edges of the vanes, Q the quantity 
 of fluid flowing per minute, n the number of revolutions per minute, r 
 the internal radius, and the angle which the vanes make with a 
 tangent to the inner circumference, then, 
 
 tan 6 = -- 
 
 27T rnA 
 
 The angle made by the vanes with the outer circumference may 
 have almost any value, if there is a large enough space surrounding 
 the fan. The discovery of the fact that centrifugal fans have nearly 
 all the same efficiency, if they are all surrounded with a large enough 
 space in which a natural whirlpool can establish itself, is due to Pro- 
 fessor James Thomson. 
 
 Eckardt's Ventilator. This ventilator has six vanes, each of 
 which is bent to form a semicircle, the radius of which is equal to 
 quarter the diameter of the whole wheel. 
 
197 
 
 Diameter of the wheel... 16. inches. 
 Breadth ..................... 4 inches. 
 
 Exit epening ............... 4 square inches. 
 
 The whole is made of sheet iron and and is driven by means of 
 a band, at the rate of 5 to 1000 revolutions per minute. The useful 
 effect is 20 per cent. 
 
 Two such wheels may be placed on the same axle, being so ar- 
 ranged by suitable divisions, that one will drive fresh air into a work- 
 ing whilst the oiher sucks out the bad air, and drives it on to some 
 distant point. 
 
 Reichenbacli and Cioylays's Ventilator. The peculiarity 
 of this ventilator is that the metal vanes are replaced by a circular 
 brush made from wire or whale bone. It is probable that the effe- 
 ciency of this machine is low. 
 
 Ventilator. In this ventilator the wings are so 
 constructed that the curvature of the vanes on the outside is tangen- 
 tial to a radius, and on the inside they are tangential to a line which 
 makes an angle of 47 with a second radius at the point where they 
 meet the inner circle. The whole is enclosed in a case. It makes 
 from 300 to 600 revolutions per minute. 
 
 A ventilator with a radius of 19.6 inches and 15 vanes, gave 
 52.37 per cent of the calculated work. 
 
 This ventilator is also constructed on a large scale. One of 13 
 feet diameter with vanes making 80 to 400 revolutions per minute 
 extracted about 400 cubic feet of air per second = 24,000 per minute. 
 
 Ventilators lor a whole mine. These always act by ex- 
 haustion and therefore with but few exceptions they can be used 
 without being enclosed in a case. They are generally placed at some 
 distance from the shaft, with which they communicate by means of an 
 inclined tunnel. 
 
 Xasmytli'H Ventilator. At Abercarn in S. Wales, one of 
 these ventilators had 8 radial wings formed from sheet iron, each 3 feet 
 long and 3^ feet broad. The total diameter of the machine was 13^ 
 feet. The foul air coming from the mine passed up between two 
 side walls and entered at the centre of the fan to be discharged at its 
 circumference. 
 
It was driven by an Engine of 13 Horse power and made from 60 
 to' So turns per minute. 
 
 The work done per minute was, 
 
 By natural ventilation 26,545 cubic feet. 
 60 revolutions ...... 49>3 T 4 >, 
 
 So revolutions ...... 61,704 
 
 Ventilator. This ventilator usually consists of four 
 flat wings which are inclined at angles of from 105 to 135 at the 
 extremity of four radial arms. 
 
 The diameter of these machines is from 6 to 10 feet. They make 
 from 200 to 300 revolutions per minute, and the useful effect is from 
 23 to 26 per cent. Burat gives in two cases a usuful effect of from 
 40 to 44 per cent. 
 
 If the inlet is too large, it is said that two draughts may arise, 
 one entering the machine near the axis and the other flowing out. 
 The quantity of air is proportional to the velocity, the manometric 
 pressure to the square of the velocity, and the power of sucking to 
 the cube of the velocity. 
 
 If a high pressure is not required, this machine recommends it- 
 self on account of its simplicity and cheapness. It is much used 
 near Mons. It gives a gauge of 2 inches and over. 
 
 Crtiibal's Fan. Amongst centrifugal ventilators, this is perhaps 
 one of the commonest which are employed at mines. It consists of 
 from 4 to lo vanes braced in such a way to a series of radial spokes r 
 that both strength and lightness are obtained. These vanes are made 
 from sheet iron, and are slightly bent forward?. The opening by 
 which the air is received from the shaft is large. The one by which 
 it is discharged occupies about one quarter of the circumference, but 
 its size can be regulated by a movable shutter. Outside this latter 
 opening there is a chimney, which from its base to its summit increases 
 in its dimensions. In this way, before the discharged air comes in 
 contact with the outside air, its velocity is gradually reduced. 
 
 A large ventilator of this description at Usworth Colliery near 
 Newcastle had the following dimensions. 
 
 Diameter ............ 45 feet. 
 
 Breadth ............... 12 feet. 
 
 Number of wings... 10. 
 
199 
 
 With 40 revolutions per minute it extracted 147,000 cubic feet of 
 air, with a pressure of 6 m m. 
 
 The efficiency of these ventilators is given by Lottner and Serlo 
 been 44 and 64 per cent. 
 
 By adding a second of these expanding chimneys, but placed in 
 a reversed position and connected with the shaft, air may be either 
 drawn out or forced into the mine. 
 
 These ventilators are usually from 20 to 30 feet in diameter and 
 make from 50 to 100 revolutions per minute. The smaller number of 
 revolutions is preferable. 
 
 Guibal Fan experiments at Staveley gave the following results. 
 
 1. The quantity of air discharged is proportional to speed 
 
 of fan. 
 
 2. The water gauge increases proportionally to the square 
 
 of the number of revolutions of the fan per minute. 
 
 3. The H.P. in the air increases as the cube of the quantity. 
 
 4. The steam pressure in the cylinder is in proportion to 
 
 the square of the piston speed. 
 
 5. The H.f>. of the engine is proportional to the cube of the 
 
 number of revolutions per minute, or to cube of volume 
 of air (R. Howe. Trans : Chesterfield &c. Institute 
 of Engineers Vol. I. p. 55). 
 The useful effect ranges from 56 to 70 per cent of the steam power 
 
 of the engine and the consumption of coal from 7 to 16 Ibs per H. P. 
 
 per hour. 
 
 Duty of Fan at a Fair Speed. 
 
 Diameter 
 feet. 
 
 \Vidth 
 feet inches. 
 
 Volume of air 
 per minute 
 cubic feet. 
 
 Water Gauge 
 in inches. 
 
 Stroke 
 inches. 
 
 Diam of cylin- 
 der inches. 
 
 10 
 
 4 o 
 
 20,000 
 
 0.50 
 
 6 
 
 12 
 
 12 
 
 4 o 
 
 30,000 
 
 0.65 
 
 12 
 
 12 
 
 16 
 
 5 6 
 
 40,000 
 
 0.80 
 
 12 
 
 18 
 
 20 
 
 6 6 
 
 50.000 
 
 1.20 
 
 18 
 
 18 
 
 24 
 
 8 o 
 
 70,000 
 
 2.OO 
 
 20 
 
 20 
 
 30 
 
 IO O 
 
 100,000 
 
 2-75 
 
 24 
 
 2 4 
 
 36 
 
 19 o 
 
 150,000 
 
 3-50 
 
 3 
 
 33 
 
 40 
 
 12 
 
 200,000 
 
 4-25 
 
 36 
 
 36 
 
 The duty varies with the condition of the shaft, air ways &c. 
 
200 
 
 Waddle Fan. This fan discharges its air round the circumfer- 
 ence into the atmosphere. The air passage through the fan has a 
 decreasing section from the centre to the circumference, so that the 
 velocity of revolution at any distance from the centre, multiplied by the 
 sectional area of the passage at that distance, is preserved constant 
 with a view of keeping the fan filled up to its circumference with 
 issuing air, and preventing the possibility of reentries of air (Oliver & 
 Co. Catalogue). 
 
 The blades which are inclined backwards and the casing, are in 
 one piece and revolve together. 
 
 The engine is geared on one side while the air enters on the other. 
 
 The S*liiele Fan. This is a high speed Ventilator usually 
 driven by a belt, receiving air on both sides and discharging into a 
 volute formed air chamber increasing in area round the tips of the 
 blades. The blades are broad in the center and taper to the tip. 
 They revolve between walls following their form. It has an expanding 
 chimney. 
 
 The apell Fan. This fan consists of a revolving cylinder in 
 which port holes are cut. The wings are attached from the edges 
 of the port holes on the inside and the outside of the cylinder. The 
 discharge is to an expanding chimney. The port hole area is greater 
 than that of the inlet. The fan is small, being from 8 to 15 feet in 
 diameter, and is run at a high speed. It is stated to have given a water 
 gauge of 10 inches and reached an efficiency of 80 per cent. It is 
 driven by belt or rope gearing making from 100 to 300 revolutions 
 per minute. 
 
 Other modern fans are the Bowlker, the Medium, and the Rateau. 
 
 It must be remembered that the results obtained from a fan at 
 one colliery will be different for the same fan at another colliery 
 the conditions at the two mines being different. The Austrian Fire 
 Damp Commission recommends large fans with low speed where there 
 are large air ways, and small fans with a high speed where the air 
 ways are narrow. 
 
 Brunton's Ventilator. This is a ventilator where the axis 
 of the fan is placed vertically. 
 
201 
 
 Andemar's Ventilator. This ventilator is somewhat similar 
 to Guibal's but like Brunton's it turns upon a vertical axis. The 
 air from the mine is drawn in at the centre and is discharged round 
 the circumference. The air which is entering is separated from that 
 which is leaving by a rim of metal on the under side of the wheel 
 which dips into a circular trough filled with water built on the top of 
 a wall surrounding the axis. 
 
 An objection to this machine is that there is a large weight 
 supported on the extremity of an axis, in consequence of which it 
 is constantly requiring to be repaired. 
 
 Harzg's Ventilator. This also is a ventilator which works 
 upon a vertical axis. It consists of a large number of curved vanes. 
 Round the circumference of this there are a large number of fixed 
 vanes between which the air has to pass before it can escape. Each 
 pair of these, acts like Guibal's expanding chimney in gradually reducing 
 the velocity of the out-going air. 
 
 Combe'* Ventilator. This is of historical interest. Although 
 not intended, it reduces the velocity of the outgoing air to a minimum. 
 At first it was constructed with a vertical axis, afterwards with an axis 
 which was horizontal. Also at first it had only one inlet for the 
 passage of air, but later on, it was constructed with two. Its efficiency 
 is given by different writers as being from 15 to 39 per cent. 
 
 Screw Ventilators. The action of these may be regarded as 
 the reverse of a wind mill. The following are examples of this type 
 of ventilator. 
 
 Lesonine's Ventilator. The efficiency of this machine is 
 given as being from 25 to 26 per cent. 
 
 L,a Jlotte's Ventilator, This consists of a horizontal cast 
 iron cylinder on which there is a sheet iron screw. It is driven by an 
 endless band. The maximum efficiency is given as being about 20 or 
 21 per cent. 
 
 Giiibal's Hydropneumatic Ventilator. This was a screw 
 made out of sheet iron about 16 feet in diameter, placed horizontally 
 and partially immersed in water. 
 
 Theoretically it will give extremely good results, but so far, Burat 
 considers that this form of ventilator has not yet been fairly tested. 
 
202 
 
 Pasquet's Ventilator. The efficiency of this ventilator is 
 given 27^ per cent. 
 
 Ventilation Wheels. Under this class of ventilators we 
 include those contrivances which act by entrapping the air, and then 
 as they revolve sweeping it out before them. 
 
 Fabry's Ventilator. The action of this ventilator is similar 
 to that which we should obtain by the revolution of two wheels 
 furnished with long projecting teeth so placed that as they revolve, the 
 ends of the teeth come in contact and sweep along with each of them 
 a certain quantity of air. 
 
 As constructed Fabry's ventilator consists of two revolving axes 
 on which are fixed three radial vanes. On these, cross vanes are 
 placed. The edges of these cross vanes have epicycloidal curvatures. 
 The two axes are placed at such a distance, that when they revolve in 
 opposite directions, the epicycloidal surfaces, which may be covered 
 with felt or leather, roll over each other. 
 
 The whole of the arrangement is placed in a case or trough, the 
 sides of which are smooth and so curved that when the vanes revolve 
 the ends of the radial spokes just pass along the walls. 
 
 When the vanes revolve towards each other, a certain portion of air 
 is enclosed and carried downwards, but a larger portion is at the same 
 time swept from below to the right and left upwards. The difference 
 between these two quantities is the air which would be drawn out 
 of the mine, which by the movement we have here supposed, would 
 result in exhaustion of air from the mine. 
 
 This ventilator has been constructed with eight vanes and also 
 with only two. 
 
 The efficiency of a small ventilator of this description has been 
 given at 51 per cent. 
 
 I<emielle*s Ventilator (BeJgiaii}. This consists of a cylinder 
 and a drum, the latter revolving eccentrically upon a horizontally 
 placed axis within the other. 
 
 On the internal drum, shutters are placed. By means of rods 
 moving upon a fixed axis, at the point where the eccentric cylinder 
 closes against the internal surface of the large cylinder, these shutters 
 are drawn in, whilst in other portions of its revolution they open out. 
 
The form of the internal drum will depend upon the number of 
 shutters which are used. When there are three shutters, the drum 
 will have three sides. In place of rods springs may be used. 
 
 One ventilator 10 feet long with 6 shutters each 4 feet, 3 inches 
 long, with 16 revolutions, gave from 225 to 235 cubic feet of air per 
 second, with a manometric depression of from 2 inches to 2^. inches. 
 
 The efficiency is from 62 to 65 per cent. 
 
 Root's Blower. This consists of two wooden wing wheels each 
 of which has the form of a figure 8. These are fixed at right angles 
 to each other on separate axes in such a mananer, that when they are 
 caused to revolve in opposite directions, the convexity of one fills the 
 concavity of the other. 
 
 These are covered by a case in such a way, that when they revolve, 
 during half of every revolution, they glide over its semi-circular sides. 
 Outside the case, the axes of these moving vanes are connected by two 
 toothed wheels. 
 
 These are sometimes 6 or 7 feet long and 2 feet 9 inches broad. 
 They are driven by a band at a rate of from 200 to 250 revolutions per 
 minute. They are chiefly used for cupolas and forges. 
 
 JEvrard's Ventilator. This consists of two cylinders of unequal 
 diameters. Along the smaller of these there are two epcycloidal 
 grooves. Projecting from the larger, are four radial vanes so arranged 
 that as the two cylinders, which are placed side by side, revolve, they 
 sweep through the epicycloidal hollows. According to the direction 
 in which these cylinders revolve, air will be either swept outwards or 
 inwards. 
 
 Cook's Ventilator. As in Lemielle's, there is a cylinder 
 working excentrically in a cylindrical chamber. 
 
 To prevent the ingoing air meeting with that which is going out, 
 a shutter is, by the pressure of the air and a spring, kept in contact with 
 the movable cylinder. One of these at Bishop Auckland had a rotating 
 cylinder 8 feet in diameter and 16 feet long. 
 
 General Notes on Ventilators. Sketches and general de- 
 scriptions of many of the above mentioned Ventilators will be found in 
 Lottner and Serlo's Bergbaukunde. Very many of them are only 
 of historical interest. 
 
204 
 
 The fans in general use are the Guibal, Waddle, Schiele, and 
 Capell. They are described by C. Pamley in his Colliery Managers 
 Handbook. 
 
 Considerations respecting Natural Ventilation. An 
 
 objection to natural ventilation is that it is liable to variation and even 
 to stoppage. One of the chief causes which tend to produce variability, 
 is the change at various seasons in the temperature of the atmosphere. 
 
 For instance, it may happen that in summer time the external air 
 is warmer than the air in the mine, whilst in winter time the reverse 
 occurs. The consequence of this would be, that the force tending to 
 produce a current, would during these different seasons act in different 
 directions. And twice during every 12 months the external tempera- 
 ture being equal to that in the mine, these forces would balance each 
 other. 
 
 As the differences in the strength of a ventilating current due to 
 variations in external temperature will be different in different districts, 
 in order to study say their monthly variations, a table shewing the 
 mean monthly temperature must be constructed, and compared with 
 the under-ground temperature of the mine which in most cases may 
 be regarded as being nearly constant. 
 
 A curve passing through a series of ordinates, the lengths of which 
 were proportional to the square root of the difference in temperature 
 of the outside air and that in the mine, would give a graphical repre- 
 sentation of the variation in the force of the ventilating current. 
 
 The fact that the heat which is received from the surface of the 
 earth travels downwards in a series of slowly advancing waves, would 
 up to a certain depth, tend to make the difference between the outside 
 air and that in the mine, sometimes greater, and sometimes less. These 
 effects are however too small to be of any practical importance. 
 
 Owing to the variability of a natural ventilating current, it is often 
 necessary to supplement its action by means of a furnace or some 
 machine. 
 
 Another objection to a system of natural ventilation is, that it is 
 seldom possible to increase its effect above a certain point. In certain 
 cases, as for instance in mines subject to sudden outbursts of gas which 
 it is necessary to sweep away, such a defect would be serious. 
 
205 
 
 Although natural ventilation may be subject to variability, it will 
 seldom be subject to a sudden stoppage Such as might be expected 
 from the breakage of a machine. 
 
 If any of the devices which are sometimes resorted to in order 
 to increase the natural ventilation, as for instance the building of a 
 chimney, tend in any way to obstruct or narrow a passage, their use 
 will not produce the effect which is expected from them. The same 
 remark will also apply to furnaces and machines. 
 
 Considerations respecting: the use of Furnaces. An 
 
 objection to the use of furnaces is, that in the case of fiery mines, un- 
 less special means are taken to supply them with fresh air, accidents 
 may arise. 
 
 In the North of England, notwithstanding the fact that many of 
 the mines are fiery, furnaces are used for ventilation. On the continent 
 it is more usual to employ machines. 
 
 From the following table, Burat endeavours to shew, that the 
 conditions under which the coal miners work in France, where fans 
 are chiefly employed, must be better than the conditions under which 
 the English miners are employed. 
 
 France 1864. England 1865. 
 
 1. Production. 11,242,634 tons. 100,493,748 tons. 
 
 2. Number of workmen 76,666. 315.451- 
 
 3. Annual production per wokman 147 tons. 318 tons. 
 
 4. Number of wokmen killed 186. 984. 
 
 5. Proportion of killed to total 1 
 
 number of workmen. ( 002 4- -0031. 
 
 6. Quantity of coal produced corres-) , 
 
 ponding to each workman killed, j fo '" tons 1O2 ' I2 7 tons - 
 
 From 3 we see that the French coal miner only does about half 
 the work done by an English miner, and also that for the production 
 of a given quantity of coal, double the number of Frenchmen are 
 exposed to accident as would be exposed in England. 
 
 From 6 we see that for the extraction of a given quantity of coal 
 there are only about half as many accidents as there are in France. 
 
 From 5. we see that as compared with the total number of per- 
 sons, exposed to danger there are fewer accidents in France than in 
 England. 
 
 It is on this that Burat lays stress and in consequence concludes 
 that where fire damp occurs, furnaces ought to be replaced by fans. 
 
206 
 
 Before accepting such conclusions it would be necessary to care- 
 fully examine the statistics and general conditions of several groups of 
 mines. 
 
 In England although annually there are about 1000 death at the 
 collieries not more that j^ of them are caused by explosions, and many 
 of these explosions are caused by other means than by furnaces. 
 
 For example during eleven years we find that the deaths in English 
 coal mines were divided as follows, 
 
 From explosions of fire damp 2 3-57 per cent. 
 
 From falls of roof and sides 4-77 
 
 From miscellaneous causes 35-66 
 
 In the case where a mine is ventilated by means of a furnace 
 in order to double the quantity of air we are obtaining, the quantity 
 of fuel must be increased many fold. Regarded in this way, ventilation 
 by means of a furnace may not be economical. 
 
 This however can to a great extent be overcome by using a pair 
 of furnaces, or else a furnace which is very long and of large area. 
 
 The action of a furnace will largely depend upon the wetness 
 or dryness of a shaft, and the conductivity of its walls. 
 
 . The first cost of a furnace is small, and in coal mines where 
 fuel is cheap the cost of working may be also small. 
 
 Considerations respecting- the use of machines. When 
 machines are used for ventilating purposes, air may be either forced 
 into a mine or sucked out. When the former method is persued 
 there is a tendency to prevent the escape of gas, but when the latter 
 is followed the barometric pressure is to some degree lowered, and 
 the escape of gas is facilitated. In mines therefore which are subject 
 to the escape of gases, the former method may perhaps be found to 
 be the most advantageous. To meet all circumstances, many venti- 
 lators are contrived to work on either principle. 
 
 In the case of Guibal's fan when it is employed to force air into 
 a mine, according to Burat it only gives of the pressure it gives 
 when used in sucking out. For this reason it is found preferable 
 to draw the air out from a mine rather than to force it in. 
 
 Unlike furnaces, the first cost of a machine and subsequently 
 keeping it in working order is great. 
 
307 
 
 Because it appears that it is more economical to produce a draft 
 by means of a fan than by burning fuel to heat a chimney, it would 
 also seem that it must be more economical to create a current by 
 means of a properly constructed ventilator. 
 
 The action of a machine does not depend so much upon the dry- 
 ness of a shaft as is the case with a furnace, also by an explosion, a 
 ventilator is not likely to be interfered with. 
 
 With a ventilator the current of air can be more easily varied 
 than it can with a furnace. 
 
 Centrifugal ventilators are cheap in construction and are good 
 where only a small pressure is required. If they are made to give a 
 high pressure their efficiency diminishes. Fans of the Guibal type 
 are the best. 
 
 When these are very large they are apt to be deranged by being 
 driven at a high rate, and also they allow of considerable leakage. 
 
 In cases where large pressures are required, a piston ventilator 
 constructed like an air pump may be used. As a rule, however, the 
 pressure they produce is greater than that which is required in or- 
 dinary mines. 
 
 The chief objection to these machines lies in the working of the 
 valves, there being great difficulty in balancing them, especially in 
 cylinders which stand vertically. 
 
 In " bell machines " like the duck pump or Struves' ventilator, 
 the same difficulty is experienced. In addition to these difficulties 
 in working, it may be mentioned that the first cost is generally great. 
 
 Amongst the various wheel ventilators, Fabry's is perhaps the best. 
 
 The first cost of these machines is greater than that of the centri- 
 fugal ventilators. Unlike them however, they give the best results 
 at high pressure. 
 
 To calculate the efficiency of a Ventilator. The effi- 
 ciency of a ventilator like that of any other machine, is the ratio of 
 work given to it as compared with the work which it actually per- 
 forms. 
 
 If a ventilator is driven by means of a steam engine, indicator 
 diagrams will furnish us with the means of calculating the Horse 
 power which is supplied to it. This we will call HP. 
 
208 
 
 The work done by the ventilator will be equal to the volume o 
 air which passes any point per minute, which we will call F, mul- 
 tiplied by the greatest difference in pressure which it exerts in Ibs. per 
 square foot, which we will call P, this difference ought to be that 
 between the air in the mine before the machine is working, and that 
 after the machine is in motion, taken in some open portion of the 
 mine to avoid any effect from a current. The work done will there- 
 fore be represented by the expression VP. 
 
 VP 
 
 This expressed as horse power will be 
 
 33000 
 
 The efficiency of the ventilator will therefore be, 
 HP* 33000 
 
 VP 
 
 Efficiency of a Furnace as Compared with a Machine. 
 
 Let w Ibs. of coal be burnt per minute, and let the units of heat given 
 out by I Ib. coal = 5040. (Welsh coal), and let 1390 units of work be 
 the equivalent for I unit of heat. (Joule's equivalent centigrade.) 
 
 TO X 5040 X 1 390 
 
 Then = Horse power of such coals in a perfect 
 
 33000 
 
 engine. 
 
 Let i?i = efficiency of engine, (or the ratio of the work done by 
 the engine as compared with that which is applied to it). 
 
 Let <?2 = efficiency of a machine. 
 
 Then 10 X 5040 X 1390 e^e 2 = V.P. (i) 
 
 If <?3 = efficiency of a furnace as a draught producer then w X 5040 
 X 1390 X ez = V.P. (2) 
 
 Comparing e$ with the product e\ e% we see when a furnace will be 
 better than an engine and fan. 
 
 At the Hollingwood and Springwell Collieries it appears that the 
 saving in fuel by fans compared with furnaces, was about 83 per cent. 
 The calculations were made upon the quantity consumed per H. P. 
 in the air (R. Howe. Trans. Chesterfield &c. Institute of Engineers 
 Vol. I. p. 60). 
 
209 
 
 The greater efficiency of a fan as compared with a furnace will 
 vary according to a variety of local circumstances. The deeper the 
 shaft the greater will be the efficiency of the furnace. 
 
 Relation between Volume Pressure Ac. (Merivale). 
 The ventilating pressure varies as : 
 The depth of the upcast (furnace ventilation). 
 The difference of temperature in upcast and downcast. 
 The H.P. of the ventilating machine or furnace. 
 The quantity of coals burnt. 
 The qtlantity of air circulating varies as : 
 The revolutions of the fan. 
 The tangential velocity of the fan. 
 The square root of the ventilating pressure. 
 The square root of the depth of the upcast ( furnace ventilation). 
 The square root of the difference of temperatures (nearly). 
 The cube root of the H.P. of the ventilating machine. 
 The cube root of the coals burnt. 
 
 The student may compare this summary with formulse already 
 given. 
 
 Pressure to produce a Current. The amount of pressure 
 required to drive a given quantity of air through a mine chiefly depends 
 upon the amount of friction which has to be overcome. Because of the 
 complication of this and other conditions it is necessary that the 
 requisite pressure should be determined by experiment. 
 
 A ventilator ought to be capable of producing a pressure of from 
 I to 4 inches of water. Where much fire damp is present which it is 
 necessary to sweep away, pressures of from 2.5 to 3.5 inches may be 
 necessary. 
 
 One inch of a water column represents a pressure of about 5.3 Ibs. 
 per square foot. These pressures might be calculated as being equiva- 
 lent to a column of air so many feet in height. 
 
 Velocity of Air. The velocity at which air passes through the 
 workings of a mine is usually about 3 feet per second. If the velocity 
 is much less than this it may not be sufficient to carry out the deleteri- 
 ous gases, whilst if it is 5 feet per second it will be sufficient to force 
 burning gases through the wire gauze of a Davy lamp and thus be the 
 cause of an explosion. 
 
In the upcast the velocity sometimes reaches as much as 28 feet 
 per second. 
 
 Quantity of Air Necessary for a Mine. The quantity of 
 air sent through a mine will depend upon the quantity of deleterious 
 products which it is necessary to sweep out. 
 
 If the number of persons in a mine = m 
 
 horses = h 
 
 pounds of powder used every hour = p 
 
 average out-put of coal in tons per minute = q 
 
 exposed surface of coal in square yards = s 
 
 and the ventilative current in cubic feet per minute = V 
 
 Then Andre says, 
 
 V = m 24 + h 72 +/ 192 + q loo + s. 
 
 In the North of England loo to 500 cubic feet of air per minute 
 per man and 30 to 160 cubic per minute per ton of coal extracted per 
 day is supplied. The velocity is about 4 feet per second. 
 
 Sometimes we see that the quantity of air passing through a mine 
 is considered in proportion to the quantity of coal which is extracted. 
 As explosive gases are chiefly given off from the surface of freshly 
 broken coal, this method of regulating the ventilation of a mine will 
 be valuable where such gases are largely developed. 
 
 In Belgium 60 to 120 cubic feet are allowed per minute for each 
 miner. The Mining law of Pennsylvania requires 200 cubic feet per 
 minute per man. Each horse will require three time as much as a 
 man. At Mount Cenis I Ib. of gunpowder was calculated to require 
 1616^ cubic feet of air, but 4043 cubic feet was considered to be a 
 better allowance (see p. 163). 
 
 These quantities, especially those having reference to the quantity 
 of coal which is extracted, are given differently by different authorities, 
 and although they are sufficiently great for an ordinary mine, for the 
 case of a mine giving off large quantities of deleterious gas it would 
 be well to increase them. 
 
 In some large collieries from 150,000 to 300,000 cubic feet of air 
 and even still larger quantities are caused tq circulate per minute. 
 
 Admission, of Air into a Mine, A single shaft will often 
 ventilate itself by a current of warm air tending to rise up the center 
 
211 
 
 whilst the external air is pouring over the edges and creeping down 
 its sides. 
 
 In a level, the cool air will tend to creep along the floor, whilst 
 the heated air will flow out along the roof. 
 
 These actions will be better marked in winter than in summer, 
 when the respective courses taken by the heated and cool air may be 
 reversed. 
 
 For the ventilation of small mines it is often sufficient to have a 
 single shaft divided by a brattice, one side of which is used as a 
 " downcast" and the other side as an " upccis A" If possible however 
 it is better to have two shafts. In the English mines, the employment 
 of two shafts is made a necessity by law, as is also the case in 
 Pennsylvania. 
 
 In order to prevent any retardation in the flow of air, the cross 
 section of the upcast is made about \ larger than the downcast. 
 This is in order to allow for the expansion which, the air has un- 
 dergone by passing through the workings or the mine. The return 
 air ways ought to be similarly increased. 
 
 Ventilatin&r a Single Level. The ordinary method of doing 
 this is to carry a division or " brattice " down the centre of the level 
 almost up the working face. 
 
 If the level to be ventilated has its exit in the open air, it may 
 be necessary to force air down one side of the brattice by means of a 
 machine. 
 
 Ventilation of Parallel Levels. As the ventilation of a 
 single level requires a brattice, in coal mines, levels or bords are driven 
 in parallel pairs, and to allow the air to pass, they are joined by passages 
 called thirlings. When the ends of these levels have advanced some 
 distance beyond a thirling, a second thirling is driven and the old one 
 closed by a stopping which may be made of brick. 
 
 The result is that the area is divided up into a series of more or 
 less rectangular blocks, the dividing lines being bords and thirlings. 
 
 To Ventilate a Chamber. When gas is accumulating in the 
 upper part of a chamber like opening, it may be removed by erec- 
 ting a vertical brattice until it nearly reaches the roof. The air then 
 sweeps along the upper part of the chamber and carries out the ac- 
 
212 
 
 cumulating gas. Tn the lower portion of the brattice, a door is left 
 for the passage of the miners. 
 
 Afr Splitting:. From the formula on p. 181 we see that the 
 
 quantity of air flowing along a level may be expressed /v / L from 
 
 W. k I c 
 
 which it follows that an air current would divide itself between two or 
 more air ways inversely as the square root of their length or of their 
 perimeters, other conditions remaining constant. Again with a given 
 head or urging force, the quantity flowing will be greater by allowing 
 the air to pass through several courses rather than by allowing it to pass 
 through one course, the length of which is equal to the sum of the 
 length of the branches. For this reason the air at the bottom of a 
 downcast is split into several branches each of which circulates 
 through its particular district and then returns to the upcast. Farther, 
 by splitting, each set of workings receives air which has not been 
 vitiated and in case of an explosion, a disturbance in one district is 
 not likely to interfere with another district. 
 
 Brattices. These are usually made out of | or \ inch deals 
 supported between temporary props. 
 
 A special kind of canvass is also very largely used for brattic- 
 ing. The advantage of a brattice of this kind is that it can be very 
 quickly constructed. Its liability to take fire is however a drawback 
 to its use. 
 
 Stoppings. When it is wished to completely isolate one por- 
 tion of a mine from another, as for instance t\\egoafor old workings 
 from places where workmen are actively employed, dams or partitions 
 called stoppings are built in the levels. These are usually constructed 
 of stone or brick and are made from 2 to 4 feet in thickness. To 
 make them air tight they may be covered with tar or asphalt. 
 
 Where it is expected that a stopping might be required to resist 
 great pressure, as for instance the effects of an explosion, it might 
 be built of two curved walls, the intermediate space being filled with 
 rubbish. 
 
 Doors. In the roads along which traffic passes, the stoppings 
 are replaced by movable doors. These are made to open in the direc- 
 
2*3 
 
 tiort of the loaded tub, and so hung that they swing to of their own 
 accord. In order that the opening and shutting of these doors shall 
 cause as little disarrangement as possible in the ventilating current, 
 they are made in pairs, and placed at such a distance apart, that a 
 train of tubs can pass through one of them and then close it, before 
 opening the second. 
 
 In order to attend to these doors, more especially to see that 
 they are properly closed, a boy called a "trapper" is stationed near 
 them. 
 
 In some mines instead of using well fitting doors they use a 
 square of canvass hanging like a curtain. 
 
 If this is tarred it may have an objectionable odour, and where 
 fire damp occurs it is said that it might prevent the miners detecting 
 the presence of such gas by its smell. In dry mines it forms a cheap 
 and tolerably good substitute for wooden doors. 
 
 Self Acting? Doors. Instead of employing "irappers" self act- 
 ing contrivances have been employed at several mines. One plan is 
 to have two folding doors hung upon axes which are slightly inclined 
 from the vertical. When a tub strikes these, they are forced open. 
 After the tub has passed, they then swing together by their own weight. 
 
 By other contrivances the doors after being forced open, swing 
 together by means of a falling weight. 
 
 As a rule these self acting doors have not hitherto been suffi- 
 ciently successful to guarantee their employment. 
 
 Main Doors. All main doors cutting off one portion of a mine 
 from another are also made in pairs. If these become destroyed the 
 ventilation of the whole mine may be stopped. So that they may not 
 be tampered with they are usually kept locked. 
 
 Man Doors, are doors opening into the return air ways. They 
 are always carefully locked, and can only be used by the overmen. 
 
 I>ain I>oors, are doors which are ready to be fixed in a level 
 for the purpose of cutting off one portion of the mine from another, 
 as for instance would be necessary in the case of spontaneous com- 
 bustion. 
 
214 
 
 Safety Doors. At the time of an explosion it may happen that 
 many of the doors in a mine are blown down and the ventilation at 
 the moment when it is most needed becomes totally deranged. To 
 obviate this, safety or swing doors have been devised. These are doors 
 which swing upon a horizontal axis. Usually they are held up 
 against the roof. When an explosion occurs the support which keeps 
 them in this position is carried away, and they then fall by their own 
 weight to stop up the level. 
 
 Some forms require to be loosened by hand. The plan seems 
 to be good but Burat says he does not know a single case where they 
 have been successful. 
 
 Cross! iigrs. Wherever two currents of air have to cross each 
 other it is well to allow the return current to pass above the ingo- 
 ing one. This is best done by carrying one level over the other, and 
 at such a height that sufficient material shall remain between them to 
 resist the effects of an explosion which might tend to destroy the 
 partition. 
 
 Sometimes one is carried over the other by brick or stone arch- 
 i ng, or as at Wigan by means of arching made from boiler plate. 
 
 Conveyance of Air by Means ol Pipes. In small mines 
 and for the purpose of ventilating single levels or openings which 
 are not of any very great extent, pipes are very often used. These 
 have usually a square cross section and are made of planks. At the 
 joints they are covered with clay to make them air tight. 
 
 At one end, these pipes are made to taper so that they can be 
 joined together by fitting one inside the other. 
 
 Pipes with circular sections are much better than those which are 
 square and for this reason metal pipes are often used. The most com- 
 mon are those made from sheet zinc. These are circular in section 
 and are joined together by placing the end of one inside the other, 
 and then smearing the joint with a kind of putty. 
 
 Cast iron pipes have been used, but they are expensive Sheet 
 iron pipes, are much better. Copper and lead have been also em- 
 ployed. Earthenware pipes are easily broken. Pipes made from 
 papier mache have been tried, but these are destroyed by moisture. 
 Canvass pipes strengthened by wooden rings may be employed to lead 
 away a strong current. 
 
2*5 
 
 In using zinc pipes all iron fastenings must be kept away, other- 
 wise electric actions set in, and the zinc is rapidly destroyed. 
 
 Sometimes a notch or trench is cut along the side of a gallery, 
 the face of which being covered with boards a pipe, known technically 
 as a ragglin or trumpeting is formed. Air sollars, which have been 
 spoken about on page 183 might be classed with pipes of this descrip- 
 tion. 
 
216 
 
 ORE DRESSING. 
 
 Ore dressing is the separation of valuable minerals from the 
 valueless materials with which they are associated when brought out 
 of the mine. The usual processes are reduction, sizing and sorting. 
 The ore is broken up to free the valuable mineral of a certain size, 
 which is then sorted. The remaining ore is then reduced to a smaller 
 size and more valuable mineral sorted out from the mixture, redttction, 
 sizing and sorting forming a cycle of operations. The word concentra- 
 tion is usually applied to certain processes by which the lighter and 
 poorer portions of a mixture are gradually eliminated by washing. 
 
 The degree to which concentration may be carried depends upon 
 local and other circumstances. For example. 
 
 1. The loss of valuable mineral is greater the higher the 
 concentration. Valuable ores therefore should not be concentrated 
 too closely. 
 
 2. The loss of metal which takes place during subsequent 
 metallurgical processes, will vary with the degree and nature 
 of the concentration. 
 
 3. The expenses connected with reduction processes which 
 may be so much per ton or may vary with the degree of concen- 
 tration. 
 
 4. Expenses connected with the processes of concentration 
 itself. 
 
 5. The cost of transport before and after concentration. 
 
 At Mount Bischoff, Tasmania, tin ore is concentrated from 2 or 
 3 per cent up to about 75 per cent. To reduce the cost of transport 
 by rail, the damp concentrates were dried. This resulted in a loss 
 of the ore as dry dust, the value of which was greater than the extra 
 cost of transporting the ore when damp. 
 
 Loss in Concentration. The loss chiefly depends upon the 
 fineness of pulverization, the degree of concentration attempted, the 
 nature of the ore and its associated gangue. 
 
217 
 
 Kustel gives as average losses, galena 15 to 20 per cent. Silver 
 ores like sulphides 35 to 45 per cent. Gold 5 to 30 per cent. For 
 the latter from 10 to 40 per cent might be a nearer approximation. 
 
 At Clausthal where the stamp ore averages 3 to 4 per cent argen- 
 tiferous galena, the dead slimes often run 2 to 4 per cent of lead. 
 Total loss in all dressing processes may be 12 to 16 per cent. 
 
 Dletals and Minerals which require to be Separated. 
 
 The following is abstracted from Gaetzschmann's Aufbereitung- 
 Vol. I p. 17. 
 From Copper separate Iron ores (except spathic iron) lead. 
 
 Tin Iron, copper and arsenical pyrites, blende, wol- 
 
 fram. Bismuth makes tin dull. Copper makes 
 it brittle. 
 
 Lead Arsenic makes it brittle, antimony hard. 
 
 Zinc Lead. 
 
 Silver Nickel, antimony, arsenical pyrites, carbonate of 
 lead, galena if the silver is obtained by amalga- 
 mation. 
 
 Cobalt Calc, manganese spar, hornstone, feruginous 
 quartz, galena. 
 
 The methods of separation vary, thus a mixture of tin, iron, wolfram, 
 molybdenum, blende, arsenical iron and copper pyriles. bismuth, 
 antimony ores and earthy minerals may be reduced by washing to tin 
 ore, wolfram, arsenical iron and copper pyrites. After roasting and 
 reducing the sulphides to oxides, a second concentration reduces the 
 mixture to tin ore and wolfram which are separated by a smelting 
 process. 
 
 In many instances it is advantageous for two minerals to occur 
 together, thus the smelting of magnetic iron is assisted by the presence 
 of calcite, garnet, augite, hornblende &c. The smelting of lead, silver 
 and copper ores is assisted by fluor spar. Spathic iron and heavy 
 spar assist in smelting lead ores. 
 
 At Iserlohn in Westphalia, blende and iron pyrites are separated 
 by roasting by which they are reduced to zinc oxide and ferric oxide. 
 Subsequent jigging gives marketable products. At the Lintorf lead 
 mines (Rhenish Prussia) blende and iron pyrites are sepa^rtn&IJ"frf first 
 
218 
 
 passing through a disintegrator which breaks up the former more than 
 the latter. The broken product in then sized. 
 
 Some ores are separated by means of electric magnets. Thus 
 iron pyrites and spathic iron may by proper roasting be converted into 
 magnetic oxide. A machine by Siemens 3^ feet long 2. l / 2 feet in 
 diameter, treats I to 2 tons of ore per hour. 
 
 REDUCTION. 
 
 This section relates to the breaking or crushing of ore preparatory 
 to concentration, to effect which satisfactorily the ore must be reduced 
 to particles of a proper shape and size. If a ore is crushed too fine, 
 during the subsequent washing processes the loss may be very great. 
 
 Hock Breakers. Before fine crushing, the blocks of ore may 
 be broken by sledges, or by a heavy single stamp weighing about 1500 
 Ibs and giving 15 blows per minute or by some form of rock breaker. 
 
 Rock breakers of which Blake's is the best known type, consist 
 of two heavy jaws ons of which is caused to approach and recede from 
 the other. Sometimes both jaws are movable. If the width of a jaw 
 at the top is 12 inches and the distance between the two jaws is 6 
 inches, the size of such a machine is described as 12 x 6. 
 
 The following table gives the sizes, the work that may be accom- 
 plished and the H. P. required for a series of Blake-Marsden rock 
 breakers. 
 
 
 Approximate Product 
 
 
 
 Size of machine 
 
 per hour. 
 
 Power 
 
 Total weight of 
 
 at mouth 
 
 Road metal. 
 
 Fine Gravel. 
 
 required. 
 
 machine. 
 
 Inches 
 
 T. C. 
 
 T. C. 
 
 N.H.P. 
 
 T. C. Q. 
 
 10 x 8 
 
 4- 3 
 
 0. 20 
 
 3 
 
 4. 14. i 
 
 12 x 8 
 
 5- 8 
 
 o. 25 
 
 3 
 
 4. 16. o 
 
 15 X 8 
 
 6- 5 
 
 o. 29 
 
 5 
 
 5. 12. I 
 
 15 X 10 
 
 7. 10 
 
 o. 32 
 
 6 
 
 6. 19. i 
 
 20 X 10 
 
 10 
 
 o. 40 
 
 8 
 
 10. 5. o 
 
 24 X 13 
 
 15 
 
 o. 50 
 
 10 
 
 14. ii. 3 
 
 2 4 X *7 
 
 16. 5 
 
 o. 55 
 
 14 
 
 14. 15. o 
 
 2 4 X 19 
 
 17. 10 
 
 o. 60 
 
 16 
 
 18 o. o 
 
219 
 
 Fragments obtained from a machine having a mouth 10 inches X 
 2 inches, and moving about one eighth of an inch are suitable for 
 jigging- 
 
 Quartz which has been reduced by a breaker may increase the 
 efficiency of a stamp battery 20 to 25 per cent. 
 
 If a Rock Breaker produces dust likely to injure machinery in a 
 mill it may be placed in a separate building. 
 
 There are many varieties of Rock Crushers in the market practic- 
 ally embodying the same principle as Blake's as the Lancaster Rock 
 Breaker and. the Universal Crusher. This latter crushes down to dust. 
 In the Mtech crusher the jaws are concave and convex. 
 
 The Comet Rock Crusher. This consists of a conically 
 
 shaped crusher head carried on a vertical shaft which below is % to 
 ^ inch out of center. When this revolves the crusher head moves too 
 and fro approaching and receding from the sides of the conical casing 
 by which it is surrounded. The head does not turn while crushing the 
 material which is fed between it and the outside lining. According 
 to the size of the machine it is said that from 4 to 60 tons of rock may 
 be crushed to the size of Macadam per hour. 
 
 Stamps. When an ore has to be roasted after reduction, or when 
 water is scarce, material may be stamped dry. Material by stamping 
 is usually reduced to about ij^ to 4 mm. in diameter. In Australia 
 experiments have shewn that for gold quartz, a preliminary roasting 
 has sometimes resulted in a large yield of gold and in less wear to the 
 machinery. The reports respecting the result of roasting are however 
 often conflicting. Usually mine stuff is crushed with water so that the 
 fine material passes through the gratings as pulp. \Ve generally find 
 five stamps working in one mortar. 
 
 Ten stamps in a mill usually constitute a battery. 
 
 The foundations of a battery consist of a series of heavy timbers 
 laid horizontally in layers, the timbers in one layer being transverse to 
 those above and below, the whole being bolted together by vertically 
 placed bolts. Sometimes the mortars stand on the end of timbers 
 placed vertically in the ground, 8 or 10 feet long and resting on heavy 
 base timbers. Above the foundation and attached to it are the uprights 
 held in position by struts and ties and horizontal cross pieces acting 
 as guides. 
 
Iron battery frames are used where there is a want of timber. In 
 UmulamPs battery a number of stamps are placed in a circle. 
 
 In ordinary batteries the stamps which consist of stems with heavy 
 heads are lifted by a cam, after which they fall and strike a blow. In 
 certain patent batteries the stamps are lifted and caused to fall directly 
 by steam as in a steam hammer. 
 
 In Pneumatic stamps an accelerated rate of fall is obtained by the 
 expansion of air in a cylinder which had been compressed during the 
 upwards motion of the stem. Steam stamps act somewhat similarly. 
 
 JIrtars and Screens. A cheap from of mortar may be made 
 of heavy planking lined with iron plates, the bottom being composed 
 of quartz fragments beaten down to form a hard bed. It is stated that 
 such a bottom yields a fine material and the metallic materials are not 
 beaten into scales which is a form disadvantageous for concentration. 
 It is difficult to keep such mortars tight. 
 
 Ordinary mortars which are bolted to the mortar blocks are made 
 of cast iron, 4 or 5 feet long and deep. They have circular dies beneath 
 each head, placed 2 or 3 inches below the discharge. They are some- 
 times lined with iron plates which can be replaced when worn. At 
 the upper side of the mortar there is a long narrow opening 3 or 4 
 inches wide for the admission of material to be crushed, and on the 
 front side a screen or grate 12 to 18 inches deep through which the 
 material is discharged. 
 
 With dry crushing the batteries are closed tightly with a box, and 
 the dust is drawn from the mortars through a wire cloth grate or a slit, 
 by a draught of air created by a fan or chimney and carried on to dust 
 chambers where it is deposited. The dust may be assisted in settling 
 and even drawn away from the batteries by a jet of steam. In wet 
 crushing the ore is sometimes admitted at one end of the mortar and 
 after passing underneath all the stamps which fall successively it is 
 discharged at the other end. With this arrangement the stamps are 
 of different weights and lifts. 
 
 The usual plan is to discharge on the long side of a mortar. 
 Discharging on two sides or double discharge has been given up. 
 Sometimes this is through a slit the size of which can be varied, through 
 grates made of wrought iron bars, or through screens made of punched 
 iron plates, brass or steel wire cloth. Sheet iron plates which are 
 
221 
 
 made of the best Russian iron, are placed so that the side of the plate 
 from which the holes were punched, is on the outside, as the holes 
 are smoother on this side and slightly larger. This arrangement assists 
 in preventing choking. Nevertheless it is necessary to repeatedly 
 brush the screens. 
 
 By keeping the level of the water outside the screens equal to 
 that in the mortar the tendency to choke is also reduced. 
 
 Screens are numbered from I to 10, number I being the coarsest. 
 They are tacked on to a wooden frame, lined with strips of blanket. 
 
 Brass and wire cloth wears away rapidly. 
 
 Fraser and Chalmers manufacture annealed iron wire cloth from 
 No. I mesh (No. 3 wire) to No. So mesh (No. 40 wire) and heavy steel 
 tempered battery wire cloth No. 4 mesh (No. 12 wire) to No. 50 mesh 
 (No. 34 wire). 
 
 Steins, heads and cants. Usually the stems or lifters are made 
 of iron circular in section but slightly coned at both ends. Length 
 lo to 20 feet and 2 l /> to 3 inches in diameter. Square wooden stems 
 are used for cheapness. 
 
 The heads or sockets for round stems are cylindrical blocks of cast 
 iron with conically formed holes at each end, ofte for the admission of 
 the stem and the lower and larger one for the shoe. 
 
 The neck of the shoe is covered with strips of wood before being 
 wedged into the head. This admits of its removal. Each end of the 
 head is strengthened by wrought iron bands. 
 
 Shoes are made of white cast iron. They wear away at the rate 
 of y 2 to I Ib. per ton of hard quartz. 
 
 Old forms of heads were rectangular in section and composed of 
 one piece. Each stamp falls on a die of cast iron about 4 to 6 inches 
 thick. The die is held in its place in a circular recess in the bottom 
 of the mortar. 
 
 On each stem there is a lifter or tappet which in modern 
 stamps is cylindrical in form. This is fixed on the smooth stem by a 
 gib and keys. By the friction of the cams upon the tappets while 
 lifting, the stem is caused to revolve. In wooden stamps where the 
 tappets are simple wooden tongues there is no rotation, in consequence 
 of which the effects of friction and wear are unevenly distributed. 
 
222 
 
 The cam face is curved to form an involute of a circle which has 
 a radius equal to the distances between the center of the cam and the 
 center of the stem. Cams of this shape lift the tappet vertically 
 and uniformly. Their faces are not oiled as that would reduce the 
 friction too much, but instead, are covered with a composition of oil, 
 tar, resin and tallow which is sufficiently lubricating and at the same 
 time keeps the metals from actual contact. 
 
 Working Effect of Stamps. (Kustel}. 
 If p = the weight of a stamp in pounds. 
 
 h its lift in feet, 
 
 f = the area of the stamp in square inches. 
 
 W = the working effect. 
 
 w = per square inch. 
 
 4>k 
 
 Then W = ph and w - Ar- 
 
 P'or very hard rock w = 6 to 7 feet pounds. 
 
 hard rock w = 5 
 
 moderately hard rock w = 4 
 
 A stem II feet long 23^ inches diameter weighs about 220 Ibs. 
 Head 8 inched diameter 19 inches high ,, 185 
 Shoe 90 
 
 Tappet 65 
 
 Total 560 Ibs. 
 
 Stamps sometimes weigh 8co Ibs. and each stamp requires about 
 l H. P. 
 
 If p = weight of a stamp in Ibs. 
 h = lift in feet. 
 
 n number of lifts per minute. 
 N = stamps in a battery. 
 
 Then the H. P. 
 
 On account of friction this quantity requires to be increased ^. 
 
 Arrangement., weight and lilt of stamp-*. Cams are 
 arranged on a shaft so that the shaft experiences a uniform resistance. 
 They are usually in groups of ten. 
 
With a long line of cams on a single shaft, the repairs which may 
 be required for one of them may necessitate the stopping of a series of 
 batteries. For this reason separate shafts are used for each battery or 
 each pair of batteries. Another principle to be observed in arranging 
 cams is to make the order of lifts such that when one stamp falls, the 
 adjoining stamps on the right and left are being lifted. 
 
 Tn two five stamp batteries with stamps I, 2, 3, 4, $, and i x , 2', 3', 
 4', 5 X , the cams might be arranged to lift in the following order I, i x , 
 5, 5'> 3, 3'. 2, 2', 4, 4'. 
 
 To hang up the stamps, that is to raise them above the range of 
 the cams, while the cam is moving, a workman places on the face of a 
 cam a piece of wood which causes the stamp to be lifted higher than 
 usual, at which moment a hinged strut (a hanger) is placed beneath 
 the tappet ; the cam passes on and the stamp is left suspended on the 
 hanger. 
 
 The lift and weight of stamp depends upon the quality of the ore. 
 For fine crushing, high lifts, light stamps and deep mortars are used, 
 while for coarse crushing, heavier stamps, low lifts and shallow 
 mortars are employed. 
 
 Work done by stamps. 600 Ib. stamps, with 75 blows per 
 minute and No. 4 or 5 screens, will crush I to 3 tons per head in 24 
 hours. 
 
 In Cornwall about i^ cwt of fuel are burnt per ton of stuff crushed. 
 
 Clayey ore requires more water than clean material, 10 Ibs per 
 minute for quartz. For quartz rocks each stamp requires about J to 
 J cubic foot of water per minute. One man can supply ore at the 
 rate of 25 to 30 tons to batteries per 24 hours, providing that the 
 material to be supplied is near at hand and of proper size. When the 
 stamp requires ore, it may strike a lever, which in turn strikes the 
 bottom of a hopper and a certain quantity of ore is caused to slide 
 forwards. Such a feed is intermittent. A continuous feed may be 
 obtained by causing a stamp to repeatedly lift a hopper or box which 
 when it falls causes a small quantity of ore slide forward. 
 
 Amongst automatic feeders we have Stanfords, the Tullech and 
 CJialleiige. 
 
 With an automatic feed one man may attend to So to 150 stamps. 
 
224 
 
 At Clausthal there are batteries with eleven heads falling in the 
 following order, 6, 2, 10, 7, II, 3, 9, 8, 4, 7, 5. The stems are 5 inches 
 from center to center. The dies are half an inch broader than the 
 shoes. Working 22 hours per day they last 10 to 12 weeks. The 
 stamps weigh 440 Ibs. and the drop is 8 inches. 
 
 There are 60 drops per minute. Each head yields \V Z tons of 
 quartzose material i. in diameter : per day. Each battery requires 
 7^ cubic feet : of water per minute. 
 
 The objection to all forms of stamps is the large quantity ot pulp 
 which is produced 190 per cent) and as this is rich in mineral, the loss 
 in subsequent dressing operations is great. 
 
 When quicksilver is used in a battery to amalgamate gold, y$ to 
 % oz of mercury is added on the feed side about every half hour. 
 
 Sometimes the long sides of the mortar are lined with amalgamat- 
 ed copper plates. 
 
 At the Mettacom mill, Austin, Nevada, it was found that with dry 
 crushing, the gain in quantity crushed was more than proportionate to 
 speed, as is indicated in the following table : 
 
 No. of Drops 
 per minute. 
 
 Horse Power 
 per stamp 
 
 Increase in 
 Power. 
 
 Yield in tons 
 per 24 hrs. 
 
 Increase of 
 Yield. 
 
 So 
 90 
 
 102 
 
 1.36 
 2.04 
 
 2.22 
 
 50 per cent 
 10 per cent 
 
 4 1 A 
 10 
 
 tsK 
 
 122 per cent 
 115 per cent 
 
 Shoir* IlfM-oil Stamper. The stamp being worked by the 
 movement of a spring beam, the blow has an elastic recoil. They re- 
 duce about I ton per hour. 
 
 'M Osoillatiiitr Stamp Mill. This consists of 
 a bifurcated arm. On the bifurcations which are like an inverted Y 
 are the shoes which rest on the dies. As the upper arm is oscillated 
 the shoes alternately strike and slightly slide on the dies. It therefore 
 crushes and grinds the ore. 
 
 l*niimntic and Elephant Stamps. These stamps are said 
 to crush I ton of quartz per hour. The cost is said to be 60 per cent 
 less than Cornish stamps of the same power, and less fuel is consumed 
 in their working. Repairs are however frequently required. 
 
Knoll's Patent Direct Aetin? Pneumatic Stamps. 
 
 These stamps are manufactured in pairs, and are guaranteed to l>e of 
 the capacity of 36 ordinary heads of cam and lifter stamps. 
 
 Kendall's Quartz Mill. In this mill, the stamp stem Is 
 rotated. By its rotation the tappet, which is fixed upon it, rises up the 
 cam, which is a plain curved incline. \Vhen it drops from this, a 
 grinding action is produced. 
 
 McLeans Patent Alpine Crushing Machine. Here 5 
 
 stamps work in a box, the from of which is the segment of a circle. 
 Twelve cams or inclined plains are bolted on the rim of a horizontal 
 wheel which, as it revolves lifts the stamps. 
 
 It is doubtful whether the last four mentioned forms of stamps have 
 met with any marked success. 
 
 Price of stamp Mills. 
 
 The following prices are taken from a list issued by the Sandy- 
 croft Foundry. 
 
 No. of Stamps. 5 St^mp loStimp 15 Stamp ao Stamp 30 Stamp 
 
 Mill Mill. Mill. Mill. Mill. 
 
 
 
 Price of Mills. 180. 360. 540. 720. 1,080. 
 
 Price of Wood Framing. 75. 95. 170. 190. 285. 
 
 Price of Iron Framing. 1 10. 145. 190. 290. 455. 
 
 Price of Wood Foundation. 32 los. 65. 97 los. 130. 195. 
 
 Approximate Prices of complete Gold Mills, including Engines, 
 Boilers, Stonebreaker, Stamps, Countergear, Copper Plates, Blankets, 
 Amalgamating Pans, Settlers, Retort, &c, 
 
 5 Stamp 10 Stamp 15 Stamp 20 Stnmp 30 Stamp 
 
 Mill. Mill. Mill. Mill. Mill. 
 
 1,100. i, 800. 2,400. 3,ioo. 45- 
 
 Rolls. Rolls for crushing ore are cylindrical in form, from 9 to 36 
 inches long and 18 to 24 inches in diameter. A pair of rolls are con- 
 nected by gearing. For coarse crushing, the rolls are corrugated. The 
 speed on the circumference is from 12 to 36 inches per second. They 
 are employed for soft materials like limestone. The material after 
 passing through one or two pairs of rolls is sifted i-n a trommel, and 
 
226 
 
 the coarse material returned by a raff wheel to the upper side of the 
 rolls, for re-crushing; 
 
 Rolls are covered on the outside with a mantel or ring ij^ to 2 
 inches thick, of cast iron or steel, which, when worn can be replaced. 
 The material treated is usually \]/^ to 2^/j inches in diameter. Tailings 
 from jigging ^ inch in diameter are sometimes crushed. When 
 material has been reduced to ^ inch in diameter it may be jigged. 
 Sometimes it is reduced to */} inch diameter. 
 
 At Przibram, one pair of coarse rolls delivers stuff to two pairs of 
 middle rolls, which supply one pair of fine rolls. The sizes obtained 
 are 22, 14, and 9 mm. in diameter. The driving may be by belting. 
 
 The frame carrying a pair of rolls is massive and strongly bolted 
 to a solidly built foundation. The bearings are arranged to slide in 
 grooves and are kept in adjustment by springs, or by weighted levers. 
 The result of this is, when any unusually hard material comes between 
 the rollers, by compressing the springs or raising the levers, the rollers 
 Separate and the obstruction passes between them. So that the sepa- 
 ration of the rolls may not affect the driving wheels these latter are 
 connected with the axis of the rolls by a tumbling shaft. Involute 
 teeth are used because they work truly at varying distances of their 
 centers. For fine material it has been customary to reduce the diameter 
 of the rolls, but this does not appear to be necessary. The feed may 
 be automatic, as with stamps, the material by means of a stone breaker 
 being first reduced to a uniform size, say not greater than 2 inches in 
 diameler. Usually the ore is crushed wet. 
 
 .If D = diameter of the rolls. 
 
 d = diameter of the material to be crushed. 
 
 s = the distance apart of the rolls or the diameter of the 
 
 crushed material. 
 
 Then Z>>i8 (</-/) 
 
 Resistance to rupture by compression per sq : centimeter. 
 Galena 45 Kilos. 
 
 Fluor spar 70 
 
 Iron pyrites 90 
 
 Blende 100 
 
 Ouartz 100-300 
 
227 
 
 
 
 
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228 
 
 <; rinding-. Ores are usually subjected to grinding 4 processes 
 when metals like gold or silver have to be separated from them by 
 amalgamation, the amalgamation being sometimes conducted simulta- 
 neously with the grinding as it is sometimes conducted with the 
 stamping. 
 
 The Arastra or Tehniia. The arastra is a circular excavation 
 12 or 16 feet in diameter lined with a paving of hard rock. In the 
 center of this, there is a vertical axle carrying four or more horizontal 
 arms to which by means of chains or ropes large grinding stones are 
 fixed. As the axle and arms are turned the stones drag over the 
 pavement, and reduce fine ore to a powder or pulp. 
 
 The Chili or Klj;o Mill. This is a machine which is com 
 monly used for grinding cement. It consists of two rollers 3 to 6 
 feet in diameter standing on their edges in a horizontally placed iron 
 basin. Either the edge rollers are caused to run round the inside of 
 the basin over the material to be crushed, or the basin which may be 
 pivotted at its center runs round beneath the rollers or runners. 
 
 Ball mills are a modification of the Chili mill, where balls are used 
 in a basin instead of the rollers. 
 
 In some Pulverizers a large number of small balls are placed with 
 finely divided ore in an iron cylinder which can be revolved. In 
 Thompson' s Pulverizer a single ball does the grinding. 
 
 The Morey's Prtlverizer the balls work in a covered dish running 
 on a vertical spindle. 
 
 In Cylinder mills the grinding is carried on between the side of a 
 cylinder and a fixed surface. 
 
 Berdan Pans are largely used in Australia for gold amalgamation. 
 
 Horizontal stone or iron mills similar to the form used in grinding 
 corn, are sometimes employed for dry grinding. They wear out quickly 
 and are not very satisfactory. 
 
 Centrifugal Hill* and Pulverizers. In centrifugal mills 
 material is supplied at the center of a horizontal disc provided with 
 radial arms. As the material travels outwards, by the particles striking 
 each other and the arms and finally the surrounding case, it is disinte- 
 grated. In Carres disintegrator the material strikes a series of arms 
 revolving in opposite directions. 
 
In the Sturtevant mill two cylindrical heads are placed on the 
 opposite sides of a hopper and are caused to revolve in opposite direc- 
 tions. It is simple and small. 
 
 A 4 inch Sturtevant is advertised to crush 100-400 Ibs. of 
 material per hour requiring 5 H. P. while an 8 inch mill crushes I,ooo- 
 2,900 Ibs. and requires 13 H. P. 
 
 In Jordan's Patent Pulverizers two sets of four arms revolve in 
 opposite directions close to each other. 
 
 Among other pulverizers we have the Griffin and Lightning 
 
 Pulverizers. 
 
 In Waring 's Centrifugal Pulverizer the work is done by 3 rollers 
 which are pushed round the interior of a rotating cylinder. The frisbte 
 Lucop mill is another centrifugal roller pulverizer. 
 
 Among the newer machines used in the comminution of ore we 
 have the Dingey puiverizer, the Heberle mill, the Brink and Huebner 
 disintegrator and the Schranz roller mill. 
 
 The results of experiments made with three of these at Przibram 
 representing the average of a year's work is as follows (Kunhardt). 
 
 Comparison for. 
 
 Order of Efficiency ist, and, ^rd, and 4th for the. 
 
 . 
 
 Heberle 
 mill. 
 
 Dingey 
 mill. 
 
 B. and H. 
 
 D.sintegra- 
 tor. 
 
 Fine Rolls. 
 
 Minimum production of) 
 fine pulp j 
 
 i 
 
 4 
 
 a 
 
 3 
 
 Labor, power, lubrication. 
 
 ii5('r 
 
 3 
 
 2 
 
 . i 
 
 Wear per ton ore 
 
 U*u '; J o;/*Vu 
 
 3 
 
 4 
 
 ,qoi 
 
 In the Schranz roller mill, grinding action is avoided and but little 
 fine pulp it produced. In reducing stuff of 5 and I mm. down to 
 2.4 mm. it gave as compared with a mill the following results 
 expressed as percentages. 
 
230 
 
 
 
 
 
 
 
 n- 
 
 O. 
 
 3 
 
 \5 
 
 
 * 
 
 o 
 
 <^ 
 
 >n 
 
 
 
 Sig 
 
 "s M 
 
 g.| 
 
 ii 
 
 
 
 
 
 
 
 
 
 
 
 
 S 
 
 Is 
 
 
 <>g 
 
 lr> g 
 
 in G 
 
 t?"* 3 
 
 
 1 - 
 
 
 
 
 1-1 
 
 
 
 j" 
 
 E s 
 
 g U 
 
 " 
 
 Stamp battery 
 
 
 4.68 
 
 1 5- 1 5 
 
 16.96 
 
 24.08 
 
 16.72 
 
 5.87 
 
 3-88 
 
 12.66 
 
 SchranzMill 
 
 6-95 
 
 21.07 
 
 26,27 
 
 16.92 
 
 a* 
 
 7 .2I 
 
 2.23 
 
 0.71 
 
 183 
 
 The Schranz Mill wears well, uses but little power and as seen 
 from the above table yields good results. 
 
 Varney's quartz grinde r consists of two conical grinders with bases 
 downwards. The material is gradually reduced as it descends between 
 the conical surfaces "which at the top are separated for the introduction 
 of the ore, 
 
 The Pneumatic Pulverizer. In this machine two jets of 
 superheated steam drive two streams of mineral particles into collission 
 which pulverize each other by their impact. 
 
 Pan Amalgamators. In Pan amalgamators, amalgamation 
 and grinding may be carried on simultaneously. This however is not 
 usual. The charge is wet, definite in quantity and is worked upon for 
 a specified period. According to the form of the grinding surface 
 Kustel divides pans into four classes, 1st plane circular, 2nd conical, 
 3rd tractory conoidal, 4th vertical mullers. 
 
 An ordinary amalgamator consists of a circular iron pan rising 
 from the center of which there is a hollow cone. The bottom of the 
 pan is lined with a disc or dies of white cast iron. The sides may be 
 of wood. Passing up the hollow cone there is a shaft which projecting 
 at the top, carries by means of arms or a hollow cone enveloping the 
 pan cone, the revolving grinding surface or muller which is faced with 
 shoes. 
 
 -. :;. Usually the muller can be raised from the bottom of the pan by 
 .screwing it up the central shaft, or the shaft itself which is driven by 
 .gearing beneath the pan, can be lifted by a lever. In this way the 
 grinding power of the muller can be regulated. 
 
231 
 
 About 600 to 800 Ibs. of stuff are treated at a time. Coarse sand 
 which is mixed with water to form a pulp, takes to grind .and amalga- 
 mate about 4 hours, finer material 2 hours. About 5 H. P. is required 
 per pan. By rapid motion of the mullers (65 to 85 or even ioo revolu- 
 tions per minute) the pulp is thrown outwards. At the periphery of 
 the pan it comes in contact with properly placed curved plates, which 
 guide it back towards the center of the pan. 
 
 To assist amalgamation the pulp may be kept hot by a jet of steam 
 or by a steam jacket on the bottom of the pan. In Roe 1 s patent elatric 
 system of amalgamation, a current of electricity is passed through the 
 pulp, with the result, it is said, of preventing the fouling and consequent 
 loss of quicksilver. Several electrical arrangements which are said 
 to improve and accelerate amalgamation, have been used in connection 
 with stamp work and pan amalgamation. Each pan requires loto ioo 
 Ibs. quicksilver. One hundred pounds of mercury dissolve }+ to 1*4 
 oz. of gold. Among pans with plane circular grinding surfaces, we 
 hvae the A'nox, the Varney and the Wheeler pans. 
 
 The pans with conical mullers may have the bottom of the pan 
 inclining downwards towards the center as in the Hepburn and Peter- 
 sons pan, or as in the Belden pan inclining upwards towards the center. 
 
 In the former pan the pulp tends to flow inwards without the 
 assistance of guide plates. 
 
 In the Excelsior and other pans the form of the base of the pan 
 and mullers is conoidal. 
 
 The Combination Pan may be taken as a standard form. 
 
 In HinkU and Capp amalgamator and grinder, perpendicular 
 mullers are pressed laterally by centrifugal force against the perpen- 
 dicular sides of the pan. 
 
 From grinding pans the pulp passes to settlers where it is thinned 
 by the addition of water, and the quicksilver and amalgam, which has 
 become finely divided, is allowed to settle. 
 
 A ten stamp silver mill requires about six pans and three settlers. 
 
 A panjholds from one to two tons of pulp. A 5 foot pan weighs 
 6,500 Ibs. 
 
 The lie ii ii eft Amalgamator. This is used for placer works. 
 The ground is scooped up by a dredger and passed into a trommel 
 
revolving partly under water. Here the stones are separated from pay 
 dirt which falls into a water tank where jets of water cause it to pass 
 over amalgamated plates. It requires 150,000 gals, of water per 1,000 
 cubic feet of earth. It is said to work placer ground for I to 3 cents 
 per cubic yard, the usual price being 3 to 9 cents. 
 
233 
 
 CONCENTRATION. 
 
 The simplest method of concentration is washing by hand in a 
 pan. This method is carried out mechanically in several concentrators 
 where the hand movement is closely imitated by machinery as in A'ew 
 and Jones concentrator used tor the waste from Berdan pans and clean- 
 ing pyrites. 
 
 In ordinary concentration the processes which are followed after 
 reduction are generally as follows. 
 
 1. For coarse stuff, (a) a classification into equally si/ed 
 grains by sieves. (A) sorting into equally falling grains by machines 
 like jigs. 
 
 2. For fine stuff, (a) a sorting into equally falling grains by 
 apparatus like pointed boxes, (b) a classification by trie action 
 of a thin stream of water carrying the material down an inclined 
 surface. 
 
 V:ri-i f Jfslerisl. The different varieties of material 
 yielded during different processes depend partly upon the nature of the 
 material and partly upon the method of reduction. 
 
 The following table shexvs the percentages of different materials 
 obtained by various operations. 
 
 
 Smalls from 
 mine. 
 
 Rolls. 
 
 Stamps. 
 
 Nut (Stufen N 
 
 p.c. 
 74- 
 
 p.c. 
 
 p.c. 
 
 Pea (Graupen) 
 Sand (Gries) 
 
 1 4 
 
 70 
 2O 
 
 32 
 33 
 
 Meal(Mehl). . 
 
 A 
 
 IO 
 
 >* 
 
 "?2 
 
 Pulp (Staub) 
 
 4 
 
 IO 
 
 16 
 
 
 
 
 
234 
 
 From rolls we may obtain. 
 
 Round grains 50 per cent. 
 Flat 25 
 Long 25 
 
 These percentages however depend upon the cleavage of the 
 minerals, thus. 
 
 
 R ound 
 grains. 
 
 Flat grains. 
 
 Long'grains. 
 
 Galena 
 
 p.c. 
 60 
 
 p.c. 
 2C 
 
 p.c. 
 I e 
 
 Quartz 
 
 40 
 
 "3O 
 
 T.O 
 
 
 
 
 
 SEPARATION AND SIZING. 
 
 S*>j>:ir!ilion of Gansriif 1 from Ore. The ore is sometimes 
 roughly broken at the mine, for which purpose large steel sledges 
 18 to 25 Ibs weight are employed. It is then roughly picked, the result 
 being attic, rich ore, middle ores and sjnalh. 
 
 Outside the mine there are the processes of ragging, spalling and 
 cobbing, each of which consists in breaking the rock and picking. 
 Ragging hammers may be 6 or 8 Ibs. weight, while those for spall ing 
 are two pounds weight. The extent to which these processes are 
 carried depends on the nature of the ore and the price of labour. 
 With high wages it might be more economical to send an ore at once 
 to the mill, while in countries where laboui is cheap it might be more 
 economical to first pick out the more worthless portions, and to separate 
 certain ores and minerals from each other which otherwise would be 
 detrimental to one another during concentrating and metallurgical 
 processes. 
 
 Cobbing hammers are i^ to 2 Ibs weight and have one end sharp 
 edged. The ore is broken on dies which, if the ore has a tendency to 
 fly may be surrounded by iron rings The smalls are usually jigged. 
 
 Sometime ores may require to be specially picked, and specially 
 arranged tables at which the pickers sit are required. Before the ore 
 comes to the pickers it is washed. Picking tables are sometimes made 
 to revolve so that the minerals to be sorted pass before several pickers. 
 
235 
 
 Some ores, like nickel ore?, can only be recognized as valuable after 
 having been exposed to the weather. Certain iron ores may be exposed 
 to the weather so that they may be readily separated from adhering 
 gangue. The result of these operations is to give worthless material, 
 first class ore or prills ready for reduction, middle class ore or halvings 
 requiring to be crushed and concentrated, and a third class ore or 
 smalls ready to be jigged. 
 
 In picking ores, crushing ores are usually separated from cobbing 
 ores. The former may be subdivided into roll rock and stamp rock. 
 All of them may be subdivided according to their mineral constituents. 
 Thus it would be well to separate galena (SG 7.5) from cassiteriie (SG 
 6.8) or blende from copper pyrites, and these again from barren rock. 
 
 Wnsliiiitr and Sizing. I3y raking the ore to and fro upon a 
 grate upon which water is falling, the smalls pass through the grate and 
 the remainder which is roughly washed is prepared ready to be picked. 
 Several gratings with different sized holes may be employed in 
 conjunction. 
 
 The ore coming from the mine may be tipped on grates having 
 opening, about 2% inches wide, the lump ore passing over the grate 
 and the finer stuff through it. The percentage of fine ore depends 
 partly on the nature of the ore and on the method of working. Where 
 explosives are employed the percentage of fine ore may be 50 or 60 
 per cent of all the ore. (Kunhanit"). 
 
 Material 1% to ^ inch diamete is usually separated into several 
 sizes for jigging. In dressing copper pyrites in Cornwall such material 
 however is only divided into two classes. 
 
 In sluices which are inclined troughs about 2 feet wide and 4 to 
 IO feel long, ore is washed and concentrated. 
 
 The Laiiterrinne is a trough 2 feet broad and 12 feet long, inclined 
 2 inches per foot. Material and clear water is supplied at the upper 
 end, and as the material is raked downwards it is washed. At the 
 lower end it passes over a scries ol sieves arranged in a step like series. 
 
 Kiddles. Riddles of various sizes and shapes may be used for 
 washing and si/ing. Oblong square riddles suspended by four chains 
 or rods, two of which by means ol screws may be altered in length, can 
 be swung backwards and forwards by hand, or by cams, and caused to 
 strike a block. When ore is placed on such a riddle a portion of it 
 
2 3 6 
 
 passes through the grating while another portion travels forward to be 
 discharged at the end. 
 
 If water is supplied on the stuff, the ore is washed. Several of 
 these riddles of different si/es are employed together. Jarring or 
 swinging riddles may be inclined and have a vertical motion. 
 
 The latter however are not so effective as the former, the motion 
 tending to choke the holes. The riddles ought to be arranged so that 
 the stuff first falls on the coarsest riddle. If it falls on the finest riddle 
 first, the gratings will be rapidly destroyed. The less the inclination 
 the slower the passage of the ore and the more effective the sifting. 
 Different sized riddles ought to have different inclinations. 
 
 Size of holes -Jg- to I inch in diameter. Length of sieve 3 to 7 feet- 
 Inclination I to 5 inches per foot. Speed '^o to 70 strokes per minute. 
 Water required, 3 to 1 6 cubic feet per minute. Sieves last 2 to 12 
 weeks (A'ustel). Three to four H.P. work the heaviest riddles. Shaking 
 riddles with 150 to 200 blows per minute give a cleaner and better 
 separation than trommels where the effective screening surfaces is small 
 and the shocks due to the fall of the material in the trommel are feeble 
 and not more than 60 per minute. Riddles however require more 
 power and wear more quickly than trommels. 
 
 Cradles. The cradle or rocker is as lightly inclined coal scuttle 
 shaped box resting on rockers. The stuff, for example auriferous drift, 
 is supplied on a tray or sieve at the upper end of the box, and while 
 the box is rocked by hand, water is poured on the stuff, the finer parts 
 of which are carried inside and flow down the inclined bottom. Cross- 
 ing the bottom are strips of wood, behind which particles of gold are 
 arrested. It is a combination of a sieve and a moving sluice. 
 
 Trommels. Trommels may be described as cylindrical, prismatic 
 or conically shaped sieves which are used for sizing and washing. For 
 stuff to travel through a cylindrical trommel the central shaft on which 
 it is carried must be inclined, or if horizontal, the inside of the trommel 
 must be fitted with a spiral. The common form is the conical trommel, 
 along the inside of which the materials travel even when the shaft is 
 horizontal. Conical trommels require less motive power and are easier 
 to manage than those which are cylindrical. For coarse work trommels 
 are constructed of iron bars built together at spaced distances to form 
 a drum, or of perforated boiler plate or cast iron. If the material 
 which has to pass through the trommel is of a clayey nature the inside 
 
237 
 
 of the trommel is fitted with a spiral arrangement of spikes. For 
 washing purposes water is supplied inside the trommel either from a 
 hollow axle or separate pipe, or the trommel revolves partially in a 
 tank of water. 
 
 At the upper end of a trommel there is a conical collar to prevent 
 stuff from falling out, and at the lower end another collar which widens 
 outwards to assist the discharge. 
 
 For sizing, the trommels are made of sheet iron, copper plates, 
 copper or brass wire cloth. 
 
 The slope inside a trommel will be less, the more washing a 
 material requires. One in twelve is usually a sufficient fall. Length 
 9 to 12 feet, and diameter 4 to 5 feet. About 10 to 20 revolutions per 
 minute. Inclination of axis 3 to 6. 
 
 Trommels of different grades like sieves, may be arranged in series 
 following each other longitudinally, or be placed concentrically, and 
 grains of different sizes obtained. 
 
 Jets of water playing upon the outside of a sizing trommel prevent 
 the choking of the holes. Clayey and slimey materials ought not to 
 be admitted. 
 
 One separating and four or five sizing trommels, size about 25 
 tons of smalls in twelve hours {Kustel\ 
 
 To obtain the best wearing of the sieves, the stuff ought to pass 
 through the coarsest first. Sometimes stuff may be separated into four 
 groups by four sizes of decreasing holes, and subsequently each group 
 may be divided into four classes by a system of sieves with increasing 
 holes. 
 
 Patent trommels with concentrically arranged sieves are difficult 
 to repair and usually heavy. 
 
 Trommels of punched sheet metal usually have round holes but 
 those with square holes do better work. 
 
 At Clausthal it has been found that copper sheet trommels which 
 do not rust, last twice as long as iron trommels They cost 80 per 
 cent more than the iron trommels. For coarse screens where rusting 
 is of little consequence iron or steel is used. The ore may be fed from 
 a pointed hopper from which the ore falls upon a rectangular oscillating 
 pan which throws it forward to the trommel. A trommel 3^ feet in 
 diameter and 9 to 12 feet long, sizes "]% to 8 tons of ore per hour. 
 
Trommels may be set in steps side by side, one drum in front 
 of another, or on a single inclined axis. In the latter case they may 
 be conical in form and so coned that they have a slight dip at their 
 lower end. 
 
 Dimensions of Sieve Holes. 
 
 The following table is taken from Kunhardt's " Ore Dressing in 
 Europe." It is similar to Rittinger's table. 
 
 Diameter of grains. 
 
 Wire cloth. 
 
 Name. 
 
 Millimetres' 
 
 Inches. 
 
 Mesh. 
 
 No. ofW r ire. 
 
 '45-2 
 32 
 22.6 
 
 2.56 = 21 
 
 1.80 =13. 
 1.28 =Ii 
 
 .90 = -1 
 
 3m. 
 
 oo 
 o 
 
 2 
 
 4 
 
 Large ) No. I 
 V Nut 
 Small \ (Stufe/i) 
 
 16 
 
 .64 = 1 
 
 TS 
 
 
 Large / No. 2 
 
 V 
 
 5.6 
 
 45 = -i-s 
 32 = T V 
 
 22 = 
 
 No. 2} 
 
 12 
 14 
 
 V Pea 
 
 Small \ (Grau^en) 
 
 4 
 
 2.8 
 2 
 
 .16 = JL- 
 
 .11 = i 
 
 08 3 
 
 ;; ? 
 
 8 
 
 15 
 
 16 
 18 
 
 Coarse I No. 3 
 > Sand 
 
 
 o55= T V 
 
 12 
 
 22 
 
 Fine 1 (Cries] 
 
 71 
 
 .04 = gS- 
 
 .028= - 3 v 
 
 16 
 
 24 
 
 2 5 
 28 
 
 Coarse 1 No. 4 
 > Meal 
 
 5 
 35 
 
 .02 = -g^L 
 
 CI 4= 6\ 
 
 >, 35 
 50 
 
 3 1 
 
 38 
 
 Fine \ (Mehl) 
 
 25 
 
 i mifo 
 
 7o 
 
 38 
 
 Pulp (Staub) 
 
 It will be observed that alternate numbers of the above series 
 progress in geometrical ratio, or taking them successively one is 1411 
 times the other. In some mills the factor of the geometrical ratio is 
 1.35 in others 2. The volumes of the grains which pass successive 
 screens are 2.828 times each other. 
 
239 
 
 The reason for proportioning the holes in sieves in this manner 
 will be understood from the section treating of the relation between 
 the diameters, volumes, weights and densities of equally falling 
 particles. 
 
 If d is the diameter of a hole in a sieve, then the distance between 
 the centers of the holes = -| d, and for fine sieves 2 d. 
 
 For fine material, sieves are made out of copper or brass wire, the 
 holes being square. 
 
 >"afure of t'articlon Required lr C'oncenf ration. Ore 
 
 particles subjected to processes of concentration are usually either 
 those which are of equal sizes or those which fall though a column 
 of water with equal velocity. 
 
 The operation of jigging is dependent upon the different rates at 
 which particles of the same size but of different specific gravities fall 
 through a column of water. 
 
 All particles treated in a given jig ought therefore to be of the 
 same size. 
 
 The lighter particles of equally falling stuff are larger than the 
 denser particles, and therefore if placed upon an inclined table over 
 which a film of water is flowing are more easily moved than the small 
 denser particles which only receive an impluse from the film of water 
 immediately in contant with the surface of the inclined place which 
 more or less adheres to its surface. 
 
 Separation of reduced material into equally falling particles may 
 be accomplished by one of the following methods. 
 
 1. By allowing the material to fall in still water. 
 
 2. By allowing the material to fall in a stream of water 
 rising vertically. 
 
 3. By combining methods I and 2. 
 
 4. By the action of a horizontal stream'of water. 
 
 Fine sands are sometimes treated on fine jigs. Meal is usually 
 reated on percussion tables and pulp on round tables. 
 
240 
 
 THEORY OF 
 
 (a) The Movement of Single Particles. 
 1. Carrying power of current. 
 
 Let r/be the diameter of a body lying on the bed of a stream with- 
 a velocity V, then the pressure exerted by the water tending to move 
 the particle is: 
 
 a V2 J2 
 where a is a constant. 
 
 The pressure of the body on the bed of the stream is proportional to 
 
 d* (d - I) 
 
 where 6 is the density of the body and I the specific gravity of water. 
 The frictional resistance of the body to be moved, where b is a 
 constant, is therefore 
 
 b </3 ( 5 _ ! ) 
 
 Equating this with the moving force, then 
 
 a yz d* = l>d*($ - i) 
 
 and collecting the constants under the symbol C. 
 yi = c<i(6 - i) 
 
 or the maximum diameters of bodies of equal densities that can be 
 carried along are proportional to the square of the velocity of the 
 current. 
 
 Cubing both sides and changing the symbol of the constant to k 
 y& = kd*($ - i;3 
 
 which shows that the maximum weights (which are proportional to </ 3 ) 
 of different bodies of equal densities that can be carried along, are 
 proportional to the sixth power of the velocity of the current. 
 
 The application of this law to the regulation of the flow of water 
 in sluices is self evident. It must be remembered that it is usually the 
 bottom velocity of a stream that has to be considered, and farther that 
 ordinary rocks lose from a half to one third of their weight in air 
 when immersed in water. 
 
 As an illustration of the above law the following is quoted from 
 the observations of David Stevenson. 
 
A velocity of 3 inches per second just moves fine clay. 
 6 lifts find sand. 
 
 8 lifts coarse sand. 
 12 sweeps along fine gravel. 
 
 ,, 24 t , ; ' '>'"' rolls along rounded pebbles one 
 
 inch diameter. 
 y,^ c:!^> L 36 sweeps along slippery angular 
 
 stones the size of an egg. 
 
 Von Sparre says that the diameters of particles of the same specific 
 gravity deposited in shallow currents are directly proportional to the 
 fourth roots of those velocities. 
 
 In considering questions relating to the movement of particles in 
 a fluid like water, Pernolet and subsequent investigators like Sparre 
 and Rittinger, assume the particles to be sufficiently far separated that 
 the movement of any one is unaffected by the proximity of its neighbours 
 and it is on assumptions of this nature that the following formulae 
 taken from RittingeSs Aufbereitungskunde are based. The practical 
 application of these formulae in the Continental System of dressing is 
 extensive, and for this reason, and because they may be regarded as 
 introductory to formulae which follow, where the movement of particles 
 2n masse is considered, they are here given. As these formulas are 
 but abbreviated extracts from Rittinger's work, students are referred to 
 the original text. 
 
 2. The resistance of fluids to bodies falling: through 
 them. 
 
 Pressure per square meter exerted by a stream of water rising 
 vertically with a velocity of I meter per second. 
 
 For a horizontal plain. 
 
 a = 51 Kilos. 
 Against the horizontal head of a wedge : 
 
 a 
 aj = - where, b = the breadth of the head, h = the 
 
 height of the wedge. 
 
 Against the horizontal head of an. equally sided wedge, 
 
242 
 
 Against the horizontal base of a right angled wedge. 
 
 a 
 
 2 
 Against the horizontal base of a cone. 
 
 02 _ where r is the radius ot the base and h the height 
 
 of the cone 
 
 Against the horizontal base of a right angled cone. 
 
 a 
 
 * 2 = - 
 
 Against the horizontal base of a hemisphere 
 <7 3 = -^- = 25.5 Kilogr. 
 
 In the following formulae. 
 
 (/ = the diameter of the particle or sphere in meters. 
 $ s= the density of the particle. 
 /\ = the density of the fluid, (for water j\ = i). 
 g = 901.809 acceleration due to gravity. 
 y = looo kilogr, the weight of a cubic meter of water. 
 t = the time in seconds during which a particle falls. 
 v = the velocity of the body in meters per second. 
 s = the distance traversed. 
 
 3. The fall of a small particle through a fluid at rets 
 is approximately. 
 
 For small spherical bodies C= 5.11. 
 For small flat grains it may = 1.92. 
 A mean value for irregular grains = 2.44. 
 
 For a small spherical particle falling through water after it has 
 reached uniform motion, its velocity is approximately. 
 
The following table gives the velocity in meters per second 
 attained by grains of galena and quartz falling through a column of 
 water. The size of the grains follows the Rittinger's sieve scale, the 
 velocities are calculated from the formulae. 
 
 a = 2.44 V d($ -i) 
 
 Sized' 
 in meters. 
 
 Velocity of fall in meters. 
 
 Galena 8 =. 7.5 
 
 Quartz 8 = 2.1 
 
 .064 
 .0452 
 .032 
 
 1-570 
 1.322 > I 
 
 1.112) 
 
 .780, 
 .671 III 
 
 .0226 
 
 9 22 ) 
 
 457) 
 
 .016 
 
 'oolf 11 
 
 If* 
 
 .008 
 
 ^556) 
 
 .276) :-< 
 
 .0056 
 
 463) 
 
 .230) 
 
 .004 
 
 39 2 f TTT 
 
 '95 ( TV 
 
 .0028 
 
 3271 
 
 .i6if 1V 
 
 .OO2 
 
 .278) 
 
 137) 
 
 .0014 
 
 
 .115) 
 
 .001 
 
 TV 
 
 97( v 
 
 .00071 
 
 
 .o82f V 
 
 .OOO5 
 
 
 073) 
 
 .00035 
 .OOO25 
 .000125 
 
 .116) 
 
 .098 (V 
 .o6 9 j 
 
 058) 
 .048 ( VI 
 034) 
 
 4. The space a small particle describes in an ex- 
 tremely short time, (say .01 to 1 second) in still water is 
 approximately given by the formula. 
 
 It is therefore only dependent upon the density of the particle. 
 Two equally falling grains might therefore be separated if the height 
 
244 
 
 of fall is extremely small, and jigs may be used as hydraulic sizing 
 apparatus. 
 
 Von Sparre gives the period of acceleration for particles 16 mm. 
 in diameter as i second, and if i mm. in diameter as .25 second. ' 
 
 The following table gives the space described by small particles 
 falling through still water during extremely short intervals of time. 
 
 Time Falling in Seconds. 
 
 d 
 
 s 
 
 .01 
 
 .02 
 
 3 
 
 05 
 
 .10 
 
 !5 
 
 .20 
 
 25 
 
 30 
 
 50 
 
 I.OO 
 
 Mill 
 
 
 
 Space described in Meters. 
 
 4 
 
 2.6 
 
 .0003 
 
 .0012 
 
 .0026 
 
 .0069 
 
 .0229 
 
 .0425 
 
 .0620 
 
 0831 
 
 1035 
 
 .1842 
 
 .3898 
 
 4 
 
 7-5 
 
 .0006 
 
 .0019 
 
 .0038 
 
 .0102 
 
 0365 
 
 .0711 
 
 .IIO7 
 
 .1489 
 
 .1890 
 
 3556 
 
 7532 
 
 25 
 
 7-5 
 
 .0004 
 
 .0016 
 
 .0036 
 
 .0091 
 
 .0272 
 
 0475 
 
 .0678 
 
 .0881 
 
 .1084 
 
 .1896 
 
 3927 
 
 5. Relation between the diameters, volumes and 
 weights, and the densities of equally falling particles. 
 
 Spherical grains of different diameters and densities which fall. 'with 
 equal velocities in water or other fluids are called equally falling grains. 
 
 Then if d^ and dz = the diameters, 
 
 61 and $2 = the densities, 
 
 V\ and V* the volumes, 
 
 jPi and PZ = the weights, 
 
 of two spherical particles. Then if these fall through a given column 
 of water in equal times. 
 
 Then by (2) 
 
 _ 
 
 d z (Si - i) 
 V\ = (62- i) 3 
 ?2 ~ (Si ~ i) 3 
 
 62 (61 - 
 
For example for equally falling grains of quartz and galena : 
 
 if i = 4 & 
 Fi = 64 F 2 
 
 If /\ = the density of the fluid, the first of the above equations 
 becomes. 
 
 **i = (Sz - A) 
 <k ~ (61 - A) 
 
 Calling d<z the diameter of a spherical grain of galena with density 
 <$2 = 7.5, and d\ the diameter of a similar grain of quartz with density 
 2.6, for these to fall equally. 
 
 In air (\ = 0.00125) ^1 
 
 In water ( ^ = l) d\ = 4 d% 
 
 In zinc sulphate ( //\ = 1.5) ^i = 545 dz 
 
 To separate galena and quartz in machines when the separation 
 depends upon the velocity with which different grains of these materials 
 fall through water, the broken material are according to the continental 
 system of jigging (but not according to the English) classified by sieves 
 into sizes, the maximum size of the grains in each division being in the 
 ratio, i, 4, 16, 64, &c. 
 
 6. The suspension of a body in a stream of water 
 rising: vertically. 
 
 The velocity of the stream which holds a body in suspension is 
 equal to the velocity which the body would acquire in falling were 
 the water at rest. 
 
 For a spherical body as shewn in (3) : 
 
 The following table gives the velocity in meters per second of the 
 upward current which holds different round bodies of different diame- 
 ters in suspension. 
 
246 
 
 Material. 
 
 Density. 
 
 Diameter in Millimeters. 
 
 10 
 
 8 
 
 6 | 4 
 
 3 
 
 2 
 
 I 
 
 % 
 
 Velocity in Meters per second. 
 
 Gold (with Silver). 
 Galena 
 
 15-0 
 
 7-5 
 5-0 
 
 2.6 
 
 i-3 
 
 1-93 
 i-3i 
 1.03 
 .63 
 .28 
 
 1.72 
 1.17 
 .92 
 56 
 25 
 
 1.50 
 
 1.02 
 
 79 
 49 
 
 .22 
 
 1.22 
 
 83 
 
 65 
 .40 
 17 
 
 1.05 
 .72 
 56 
 35 
 IS 
 
 .86 
 
 59 
 .46 
 .24 
 
 .12 
 
 .6l 
 
 .41 
 32 
 .20 
 .08 
 
 32' 
 .29 
 
 2 3 
 
 3 
 
 Iron Pyrites 
 Quartz .. 
 
 Coal 
 
 
 With the formula V = 2.44 V ' d ($ I) the following table giving 
 the velocity necessary for the suspension of irregularly formed grains 
 has been calculated. 
 
 Substance. 
 
 Density. 
 
 Diameter of seive in Millimeters. 
 
 10 
 
 8 
 
 6 
 
 4 
 
 3 
 
 2 
 
 I 
 
 % 
 
 Velocity in Millimeters. 
 
 Gold (with Silver). 
 Galena 
 Iron Pyrites 
 Quartz 
 Coal 
 
 15-0 
 7-5 
 S-o 
 
 2.6 
 
 i-3 
 
 .90 
 .62 
 49 
 3 
 13 
 
 .80 
 55 
 43 
 .27 
 
 .12 
 
 .70 
 
 4 
 
 .24 
 .10 
 
 57 
 39 
 30 
 .19 
 .08 
 
 5o 
 
 & 
 
 17 
 .07 
 
 
 
 .22 
 .14 
 .06 
 
 .29 
 .20 
 
 *5 
 
 .10 
 
 .04 
 
 .20 
 .14 
 .10 
 .07 
 03 
 
 7. Movement of a particle in a rising: stream of 
 water. 
 
 The velocity v which a body will attain in a rising current, is 
 approximately the velocity of the current C, minus the velocity neces- 
 sary to hold the body in suspension or, 
 
 8. Tbe space a particle describes in an upward cur- 
 rent of water in an extremely small interval of time (say 
 .01 to 1 second) is approximately given by tbe following- 
 formula, 
 
 where 
 
From this it follows that the smaller of two equally dense grains 
 rises the higher, and for two equally sized grains the least dense rises 
 the higher. The denser falls the quicker. If the bodies do not rise 
 the denser will sink lower than the less dense as in quiet water. 
 
 Of two equally falling grains, at the commencement the smaller 
 and denser moves higher than the greater and less dense. The upward 
 stream therefore tries to place equally falling particles in the reverse 
 order to what they would have in ordinary sieve work providing that 
 these particles are free to move. If however the velocity of the 
 descending current is small and equally falling particles are allowed 
 to fall, the denser particle would fall quicker than the less dense as in 
 still water. 
 
 9. Movement of a particle during: an extremely 
 small interval of time in a descending 1 stream of water. 
 
 Before a body attains the velocity of a descending stream C, it has 
 an acceleration. 
 
 During this period it has a velocity, 
 
 V = C - tan (tan-i AC- Bt) 
 
 A 
 
 And when C = V. 
 
 _ tan-i^C 
 ~~B~~ 
 The distance described until the commencement of this is, 
 
 ^ 1 AC - i lo S n ( l 
 
 The time taken for particles of quartz and galena to attain the 
 velocity of a descending stream and the space they describe in attaining 
 that velocity are given in the following two tables. 
 

 Quartz SG 2.6 
 
 Galena SG 7.5 
 
 
 Diameter in mm. 
 
 Diameter in mm. 
 
 
 
 
 of stream in 
 
 i 
 
 4 
 
 16 
 
 i 
 
 4 
 
 16 
 
 Meters. 
 
 
 
 
 
 
 
 
 Times in Seconds. 
 
 25 
 
 .030 
 
 37 
 
 .040 
 
 .026 ! .029 
 
 .029 
 
 50 
 
 .040 
 
 .060 
 
 075 
 
 043 -053 
 
 057 
 
 75 
 
 .044 
 
 073 
 
 .101 
 
 .0=52 
 
 .072 
 
 .083 ' 
 
 I.OO 
 
 .047 
 
 .081 
 
 .121 
 
 .057 .085 
 
 .106 
 
 
 Distance in Meters. 
 
 25 
 
 .0043 
 
 .0049 
 
 .0051 .0034 
 
 .0036 
 
 0037 
 
 50 
 
 .0133 
 
 0173 
 
 .0196 
 
 .0123 
 
 .0139 
 
 0145 
 
 75 
 
 .0239 
 
 .0340 
 
 .0416 
 
 .0242 
 
 .0295 
 
 .3206 
 
 I.OO 
 
 .0352 
 
 .0532 
 
 .0693 
 
 .0379 .0493 
 
 .0054 
 
 In the above expressions, 
 
 A- / _JSi4 
 
 V 2yd (6 - 
 
 K / 3"3 
 
 >=*/ 
 
 6 V 2 y 
 
 3 = 25.5 kilogr, 
 
 A) 
 
 -A) A 
 
 6 V d 
 
 A formula which approximately expresses the distance described 
 by a particle falling in a downward current during a short interval of 
 time may be written : 
 
 303 C2 2y d\ p/2 
 
 For two equally sized grains the denser sometimes goes over a 
 greater distance sometimes over a less, thus if 
 
 I~V S 
 V ~T< 
 
the denser goes first. In the opposite case the denser remains behind. 
 In the case 
 
 3*3 
 
 the two equally sized grains fall equally without any regard to their 
 difference in density. 
 
 For two equally dense particles at first the smaller falls the 
 quicker and traverses a greater distance. 
 
 For two equally falling grains, the denser goes first and indeed 
 even much quicker than in still water, from which it follows that a 
 downward current may be extremely useful in separating equally 
 falling particles. 
 
 1O. The fall of a particle in a stream moving: hori- 
 zontally with a velocity C. 
 
 Let x the distance moved horizontally in the time /. 
 
 y = the distance moved vertically downwards in the time /. 
 Then approximately for spherical particles, 
 
 x = Ct 
 
 ! 
 
 when C\ and A have value as before. 
 
 For irregular particles where D is the size of sieve. 
 yC 
 
 -I) 
 
 Here the body follows a straight line diagonally downwards. 
 For two bodies of different size and density we have 
 
 jl 1 = / D1 (fo - D 
 
 x-i \ 
 
 D l (Si - I) 
 
250 
 
 from which it follows, that for equally falling bodies where 
 
 A (62 - i) = A (tfi - I), 
 therefore also x = x% 
 
 and these equally falling bodies reach the bottom at the same place. 
 A horizontal stream of water may therefore be used to obtain equally 
 falling grains. 
 
 11. Particles in flowing water on an inclined plane. 
 
 Let 
 
 <p = Inclination of the plane. 
 
 s = Coefficient for sliding friction. 
 
 b Breadth of base of a prismatic body, in meters. 
 
 d = Height of base in meters. 
 
 k = weight of particle in kilos. 
 
 r = The resistance of sliding friction. 
 
 w = rolling 
 
 c = velocity of the water in meters per second. 
 f = The section of the nearly spherical particle at right angles 
 
 to the current. 
 
 4 = Experimental value for pressure of water with a velocity of 
 I meter on a surface I square m. in area (see p. 241). 
 
 Then r = s ($ i) cos <f> 
 
 o 
 
 w = ~d ' 7 ^ ~ *) cos ^ 
 
 According as r is > or -< w so will the body slide or roll. 
 The velocity to balance sliding fiction is: 
 
 For polygonal bodies nearly spherical 
 
* 
 
 The velocity to balance rolling is : 
 
 And for polygonal bodies : 
 
 *. cosy- sin?) 
 
 V 34 
 
 where # = 
 a 
 
 From the above we see that when two different particles are carried 
 along (sliding or rolling) the relationship of velocities of current is as 
 follows : 
 
 SL = /(5i - 
 cz V (Sz - 
 
 From which it follows that equally falling bodies can not be 
 separated by a stream of water either according to there density or 
 according to their size. A flowing stream of water can however be 
 used to classify or separate according to density in the case of equally 
 sized bodies, or it can be used for separation according to size in the 
 case of approximately equal density in the particles. 
 
 Equally falling grains may be separated into ccarse and fine in a 
 stream with decreasing velocity, or according to density in a very thin 
 stream (see p. 262). 
 
 12. Influence of centrifugal force npon particles 
 falling in water. 
 
 Let V 
 
 k = the weight of particle. 
 v = the velocity of rotation. 
 
 r = the distance of the particle from the axis of rotation. 
 g = force of gravity. 
 
 Centrifugal force F = - 
 S r 
 And for a spherical body of diameter d and density $ : 
 
 1& JT V 
 
252 
 
 For two different bodies of diameter d\ and dz and densities 
 di and fa : 
 
 fj ^i 3 di 
 
 If the two bodies are of the same size then : 
 
 ~^" = "dT = 
 
 That is for bodies of the same size centrifugal force directly varies 
 with the density. 
 
 In the case of bodies of equal density, that is di = d2 " 
 
 F! s 3 
 
 ~Fk ~ 2 
 
 That is to say centrifugal force varies as the cube of the diameter. 
 For equally falling bodies : 
 
 d\ (dl I) = *& (62, ~ !) 
 and when dl > da then it can be shewn that : 
 
 It therefore follows that of two equally falling particles the denser 
 has the less centrifugal force. 
 
 For two equally falling bodies let di = n d2 
 
 /da ! \ 3 r , 
 
 i hen f\=n\ J /qj 
 
 \ T^da i . 
 
 Comparing the centrifugal force of equal falling particles of quartz. 
 iron pyrites and galena with densities, d2 = 2.6; d 1 = 5.2 and di = 7-5 
 
 we get for iron pyrites F\ = .in F 2 
 galena F = .039 F 2 
 
 Therefore the centrifugal force of iron pyrites is n per cent and 
 that of galena 4 per cent more than that of quartz. 
 
(b) The movement of Particles en masse. 
 
 As in certain dressing operations for example in jigging, grains do 
 not fall freely but in the interstices between their neighbours Prof. H.S. 
 Munroe experimented on the fall of particles through tubes and en masse. 
 (See The English verstts the Continental System of Jigging. Trans.: 
 Am.: Idst.: Min.: Eng. Vol. XVII p. 637). 
 
 The results he obtained are as follows : 
 
 With D representing the diameter of a tube, and the other nomen- 
 clature as before : 
 
 ..;<,- =5 ' II v 1 -^ 
 
 The more nearly d = D the slower the rate of fall. 
 The falling velocity is but little affected if: 
 
 10 
 
 The maximum falling velocity is when : 
 
 10 
 For spheres moving en masse. 
 
 v = .833 vV (6" i) 
 
 Spheres en masse have therefore only about i of the velocity of 
 free falling spheres. 
 
 An increase in the velocity of a current beneath a mass of shot 
 lifts them and tends to force them apart, the interstitial space or D 
 increases and a greater velocity is required to support the shot. The 
 same material may therefore be worked in jigs run at different speeds 
 and with different strokes. 
 
 In rounded grains of uniform size falling en masse: 
 
 v = .490 V ' d (<5 i) 
 For angular grains of uniform size falling en masse : ^ ^o * Pi?" " 
 
 . ^ /~m r 0^ 
 
 - i) 
 
254 
 
 For large spheres moving in a mass of small spheres when the 
 difference in diameter is considerable : 
 
 v = .307^/^(5 - I) 
 
 In a mass of grains of different sizes the large grains move 
 relatively in smaller channels than the small grains and are therefore 
 more retarded. 
 
 It the diameter of a quartz grain is d and the diameter of a galena 
 grain d\ : 
 
 Then .307 V ' d, (2.6 I) = .833 VVi (7.5 i) 
 
 31 
 
 or the diameter of equal falling grains are in the ratio = and 
 not in the ratio which only applies to free falling grains. 
 
 For separation, grains of quartz and galena might be sized between 
 limits of say I and 30 mm. 
 
 From the above formulae, velocity of jig currents may be calculated, 
 and from this the length and number of strokes. 
 
 From Prof. Munroe's investigation unless the difference in specific 
 gravity is small, close sizing is not necessary, the small stuff in a mixture 
 being concentrated in the interstices between the coarse stuff forming 
 the mineral bed. 
 
 For fine stuff on jigs, close sizing is a disadvantage. 
 
 The size of the mesh of the jig sieve is of great importance. It 
 determines the size of the particles in the jig bed and these determine 
 the size of the interstices. 
 
 Stuff less than T 4 ^ the size of the smallest interstices between the 
 coarse stuff, can not be treated successfully. 
 
 It has already been shewn that the greater the density of a particle 
 the greater is the space described during the short interval of time 
 while there is acceleration. The short duration of the strokes of a jig 
 are therefore favourable to the separation of unsized material and 
 therefore the size ratio of particles is even greater than that which has 
 been deduced. 
 
CONCENTRATION OF COARSE .MATERIAL. 
 
 Jigging. The operation of jigging may be illustrated by taking 
 a mixture of materials like galena and calcite in particles of about the 
 same size, and placing them in a sieve which is rapidly moved up 
 and down in a vessel of water. At each downward movement the 
 galena particles fall more quickly than the calcite, the result after a 
 series of movements being that the galena forms a layer on the bottom 
 of the sieve and the calcite remains on the top. In this case the jig 
 acts as an hydraulic sorter. 
 
 It has been stated that when the strokes are short, a jig may be 
 used as an hydraulic sizer. 
 
 Comparing for instance quartz and galena we see from the table 
 (p. 243) that a spherical grain of quartz 4 mm. in diameter falls through 
 water at about the same rate as a similarly shaped grain of galena I 
 mm. in diameter, although the former is 64 times larger and twenty 
 two times heavier than the latter. It would therefore appear that to 
 separate different materials by jigging, the particles ought to be appro- 
 ximately of equal sizes, and as the relative speeds of round, oblong 
 and flat grains when falling in water are roughly as 1. 12: .97: .79 
 they ought as far as possible to be of similar shapes. " 
 
 In the English system of jigging there is no preliminary sizing. 
 The crushed ore is first treated on coarse or roughing jigs and that 
 which passes through these is then treated on fine or finishing jigs 
 A layer of coarse material is kept on the jigs. In the Continental 
 system, the materials are first sized and the different sizes treated on 
 different jigs. 
 
 The two systems may be combined. 
 
 In the English system the plant is simple and requires less 
 power to run. It is good for low grade ores on a large scale. The chief 
 objection is the imperfect concentration of material that has passed 
 the jig bed. Hidch work may be retreated on finishing jigs, or 
 classified in pointed boxes and retreated in jigs and the slime on 
 tables. 
 
 The materials which are subjected to jigging are usually the smalls 
 from crushing between i-| and ^ inch in diameter. It has only been 
 
2 5 6 
 
 in exceptional instances that materials of 2 m. and even as low as I 
 mm. in diameter have been jigged. 
 
 The smallest size that can be treated satisfactory may be taken at 
 1.5 mm. 
 
 These are often too rich to be thrown away and too poor to be 
 directly smelted. If they were reduced by fine crushing for concen- 
 tration, considerable loss might be incurred by the floating away of fine 
 particles. 
 
 Before jigging, according to the continental method the particles 
 require sizing, different sizes being treated separately. The upward 
 movement of the water or the downward movement of the sieve must 
 be quick. Successive movements must not succeed each other too 
 quickly or the particles have not time to Settle. With very fine 
 materials the time of settling will be greater than with the coarse 
 materials. The size of sieves corresponds with that of the grains. If 
 ore is finely disseminated in the gangue, it is not jigged. 
 
 The laws governing the jigging of fine materials like sand and 
 coarse meal classified as equally falling particles by Spitzkaslen or 
 Spitzluttee, are those relating to the period of acceleration (see p. 246 
 and 247). 
 
 1 Fine jigging was tried at Ciausthal for slimes I and 5 mm. but the 
 treatment by central discharge tables gave better results. At Scharley 
 in Upper Silesia sand jigs have replaced round buddies. It would 
 however seem that fine jigging can only be resorted to in special cases. 
 
 If the piston be provided with valves, and valves be arranged 
 below as in a pump, the water may be caused only to move upwards 
 and during the down stroke the ore is settling in comparatively still 
 water to form a more regular layer. 
 
 The piston lift If is calculated from the formula: 
 
 n TT 
 
 D = the sieve class (diameter of hole in sieve). 
 <5 = density of the particles. 
 h = the number of lifts per minute. 
 
257 
 
 As a test of the accuracy of Prof. Munroes' invesigations, the mill of 
 the St. Joseph Lead Co. Bonne Terre, Mo.: is given. The roughing 
 jigs treat unsized stuff from 4 mm. to slime. 
 
 Pistons make 150 strokes of 2 inches per minute. Piston area is 
 -i sieve area. 
 
 The velocity of the current is therefore .08 m. per second which 
 ought to raise a 4 mm. grain of galena. Jig sieves are No. 6 with 2.8 
 m. openings. The grain of maximum velocity is about mm. 
 
 Finishing jigs treat stuff I mm. and less. There are 270 stroke of 
 ^ inch per minute. Jig sieve is No. 8 (2 mm). 
 
 The concentration is satisfactory, the stuff treated being first from 
 2 mm. to -i mm. and afterwards I mm. to -^ mm. without loss in 
 tailings. 
 
 Movable Jiggers. The simplest form of a jigger is a sieve 
 which is jerked up and down beneath the surface of water contained 
 in a fub, kieve or hutch. The movement may be given directly by 
 hand, or the sieve may be suspended from a lever which is worked 
 by hand or by a cam. 
 
 The sieve may be circular, square or oblong, about 6 or 9 inches 
 deep and 4 or 8 feet area. Stuff which passes through the meshes of 
 one jigger may be treated on a second jigger with a finer mesh. 
 
 For I square foot area, 4 cubic feet of material may be jigged per 
 hour. 
 
 Stationary Jiggers. These jiggers consist of a sieve or set of 
 sieves arranged in a box filled with water, which by the reciprocat- 
 ing movements of a piston, is caused to pulsate up and down in the 
 sieves. The movement causing the smalls to rise must be quick. 
 The piston stroke is 4 or 5 inches and there may be 40 to 80 strokes 
 per minute. 
 
 If stuff is fine so that water does not readily penetrate between its 
 component parts, it has to be worked in thin layers. For very fine 
 materials less than 2 mm. in diameter, there may be 1 20 to 150 
 strokes of i to f inch per minute. 
 
 Continual Jiggers. In Rittinger's Setzherd the sieves'are sup- 
 ported on a frame which is caused to swing through a range of 2 to 
 
2 5 8 
 
 4 inches, when it comes in contact with a block and receives a jerk. 
 This takes place during the downward motion of the piston. 
 
 The result is that the piston causes a vertical separation of the 
 grains of ore, which, in consequence of the blows, are travelling from 
 the upper end of the sieve, where they are fed from a hopper, towards 
 the lower end where they are sized and dischaged. With a sieve 13 
 inches broad, 30 to 40 cubic feet may be discharged per hour. 
 
 In some continual jiggers, the rich material is discharged through an 
 opening in the bottom of the sieve by the opening of a valve which is 
 lifted at each downward stroke of the piston. 
 
 In Kaiser's patent jigger as used as Mount Bischoff, the chief point in 
 the construction is the fastening down of the sieve to prevent warping. 
 
 The jigging machine most commonly in use is the one where the 
 piston works in a box at the side of the sieves. 
 
 One jig may have 2, 3 or 4 sieves, the lighter materials from the top 
 of one sieve being carried by a current of water upon the second sieve, 
 where the jigging action is continued. 
 
 Jig boxes are. usually made of wood strengthened with angle iron. 
 The piston may have an area equal to that of the sieve. The width 
 of the sieve is 18 to 22 inches and length 28 to 36 inches. The piston 
 has about \ inch play round its edges. The sieves are made of per- 
 forated sheet iron or brass wire. 
 
 Length of stroke. 
 
 For 2 inches stuff = 5^ inches. 
 
 fine = i-i 
 
 The number of strokes for coarse stuff may be 75 per minute, while 
 for fine stuff 150 to 200 per minute. 
 
 The thickness of the mineral bed upon the sieve, is between and 
 3- inches, the stuff to be separated above this being ! to 8 inches thick. 
 
 Other jigs are the Huet and Geyler, Colloms jig, the Patent jig 
 of Kitto and Paul. 
 
 I>ry Jig-grins 1 . Where it is difficult to obtain water, materials of 
 different specific gravities may be separated by a current of air, heavy 
 
259 
 
 particles being carried to a less distance by a given current than light 
 particles with similar and equal surfaces. Such separation may be 
 carried on in covered airways or chambers. 
 
 In Aufermanrfs dry jigger the arrangement is in many respects 
 similar to a wet jigger, the ore resting on a sieve and being repeatedly 
 lifted by a blast of air instead of a pulse of water from beneath. It 
 separates grains less than 7 ' & inch in diameter. 
 
 Coal cleaning:. At many mines the coal is cleaned by picking 
 out the dross by hand the coal being passed over a shaking screen 
 or travelling band which moves about 40 feet per minute. The cost 
 varies from 1^ d. to 2 d. per ton for every 5 per cent of dross removed. 
 For small coal, as for example that used in coke and briquette 
 making, the first operation is sizing on trommels, after which it is 
 jigged. The cost may be from 2 </. to 6 d. per ton. Amongst Machines 
 we have the rotary form as used in Tokyo (Robinson type) the 
 ordinary jig (Sotithgate Engineering C) the Bell and Ramsay trough 
 machine &c. 
 
 In a complete plant, jigs, inclined trommels, elevators, mixers, 
 conveyors, and for briquette making, rolls and pitch breakers (edge 
 rolls) might be required. 
 
 CONC'EXTRATIOX OF FINE MATERIAL. 
 
 I. Sorting- into equally falling: grains. 
 
 Pointed Boxes. (Spitzkasten). These boxes are in form 
 square pyramids with the base upwards. They are arranged in series, 
 the smallest box being at the upper end and the largest and deepest 
 at the lower end. They are connected by gently inclined troughs. 
 A current of water flowing downwards carries the sands. In the first 
 box the heavier and larger grains are deposited. The current being 
 less swift in the second box another quality of equally sinking grains 
 remain. In the last box the finest material is caught. 
 
 The accumulated sands are drawn off by pipes from the bottoms 
 of the boxes. 
 
 The top box has one tenth of a foot width for each cubic foot 
 of material received per minute. The breadths of a series of boxes 
 are in the ratio of I, 2. 4. 8. 
 
260 
 
 If the first box has a length of 6 feet, the other boxes are each 
 9,12 ,15 feet long. 
 
 The sides have an inclination of 5 - 
 The inclination of the conveying trough per 6 feet is : 
 For coarse sand I to IJ- inch. 
 middle fine ^ to f 
 
 rM ., 
 
 shme i- to i 
 The percentages received from the boxes are : 
 1st. box 40 per cent sand. 
 2nd. 28 
 3rd. 1 8 
 4th. 10 
 
 At Schemnitz, Hungary, where 20 tons are crushed in 24 hours, 
 four boxes have the following dimensions 
 
 1 box. 6 feet long 2?- feet wide 4 feet deep. 
 
 2 )) 9 5 & n 
 
 3 I2 8 8 
 
 4 15 15 10 
 
 At least 10 heads of stamps are required for a set of boxes. 
 The size of the discharge orifice is regulated by a nozzle. 
 
 If a set of spilzkaslen has the same dimensions, to obtain classi- 
 fication, the outlets are made of decreasing diameters and syphon dis- 
 charge pipes are used, those dischanging the coarse material being the 
 shortest. 
 
 Spitzlutte. Here there is a series of inverted wedge shaped 
 boxes, inside which are smaller wedge shaped boxes which can be 
 raised or lowered. The sands flow in the conduits formed between 
 the two boxes, therefore first descending towards the edge of the 
 wedge and then ascending. The wedge shaped box is raised or low- 
 ered according to the quantity of stuff that may be flowing. The dis- 
 charge of the coarser material is from the bottom of the outside box, 
 which may be 3 feet deep. The width of the conduit between two 
 wedges is 3 to 6 inches. Spitnlutte are adapted to classify a small volume 
 of thick slime, or to sort several classes of sand and coarse meal from a 
 volume of dilute slime, this latter being separated in spitzkasten. 
 
26l 
 
 With spitzlutte or spitzkasten classifiers when sorting sands, an 
 upward current of clear water is admitted from the apex of the wedge. 
 In the former apparatus this increases the upward current, while in the 
 latter it creates one. In a set of classifiers for fine sands the upward 
 current of the first may be 6 inches per second, the factor of diminishing 
 velocity in succeeding classifiers of larger size being from .35 to .50. 
 The sectional area of the current, diameter of discharge outlet are 
 more easily regulated in the spitzlutte than in spitzkasten. (Kunhardt}. 
 
 In some forms of classifiers the pulp is conveyed by a pipe to the 
 bottom of the pointed box where it meets with the upward current 
 of water. In others it may be admitted to the upward current half 
 way down the pointed box. One box may work 6 to 10 tons of pulp 
 per 24 hours. 
 
 Troughs, strips, launders, runs, canals, labyrinths. 
 
 Slimes and sands may be separated by deposition, as they flow along a 
 series of troughs. The first troughs along which the materials flow 
 are the narrowest and most steeply inclined, and in them the current 
 is most rapid. For I cubic foot per minute, a breadth of 6 inches may 
 be given. The breadths of a series of troughs are in a geometrical 
 ratio, the highest exponent being 1.5, or in the ratio, I, 1.5, 2.25, 3.37. 
 Thus to separate 8 cubic feet per minute ; the breadths of the 
 troughs might be 4, 6, 9 and 13 feet, and the lengths 12, 18, 24 and 30 
 feet. The inclination of the upper troughs about \ to f in. per 6 
 feet. The lower ones are horizontal. The troughs may be in series 
 or in broken lines according to space. Sometimes they are placed in 
 duplicate series so that one set may be in use while the other set is 
 being cleaned. 
 
 The quantity of material deposited in the various troughs may be, 
 1st trough 60 per cent. 
 
 2 12 
 
 3 ., 10 
 
 4 10 
 loss 8 
 
 The percentage of metal in each division may be the same. 
 
 Some of the loss from the strips may be saved by deposition in 
 slime pits, through which the water is allowed to flow before finally 
 escaping from the works. 
 
262 
 
 One source of loss, is due to the partial drying'of the [mineral in 
 the strips before it is fed upon slime tables, resulting in the production 
 of float mineral. 
 
 Blanket Tables. These are troughs about 10 or 15 feet long, 
 15 or 16 inches broad, inclined at about 10 or 15 and covered with 
 coarse blanket. They are extensively used at quartz mills in Australia 
 and California for catching the gold as it flows from the batteries. 
 Several troughs are used side by side, so that while the blankets of 
 one are being washed, the gold sand may be flowing over the others. 
 If there is a series of troughs extending longitudingly 20 or 60 feet 
 in length, the upper blankets may be washed every hour, while the 
 lower ones may only require to be washed once a day. The upper 
 blankets may contain 70 or 75 per cent of the gold. 
 
 The gold obtained is mixed with iron pyrites and other material 
 and it is therefore further washed by hand in pans. 
 
 Blanket stuff may also be concentrated on tables or be directly 
 amalgamated. 
 
 . Classification of equally falling- grains. (Concentra- 
 tion on tables.) 
 
 Theory of separation. From pointed boxes and other 
 apparatus described, equally falling grains are obtained. These may 
 be separated by the action of a thin stream of water on an inclined 
 table, the water acting with more force on the larger grains than on 
 the smaller grains. 
 
 The separation depends upon : 
 
 1. The velocity of flow which may be regulated by the 
 inclination of the table. 
 
 2. The thickness of the stream water. 
 
 3. The consistency of the sands or slimes. 
 
 Slimes and sands may be conducted from pointed boxes directly 
 to the tables, while material from troughs requires to be first diluted 
 with water and supplied by a feeder. 
 
 Stationary Feeders. One type of feeder is a box 3 or 4 feet 
 long, \y 2 foot broad and ij^ foot high, with a base inclined forwards 
 and sloping right and left towards the sides. A stream of water is so 
 
arranged that it is admitted at the upper end of the bottom, and as it 
 flows down beneath the sands, it spreads right and left in towards the 
 sides. The stuff as if comes out is diluted with water. 
 
 Rotating: feeders. In an ordinary rotating feeder there is a 
 circular conically shaped disc furnished with radiating ribs of iron. 
 As this slowly rotates, the ribs of iron pass beneath and close to the 
 base of one or more hoppers filled with sands, and each rib carries 
 with it a definite quantity of material which is eventually washed off 
 the rotating cone by a jet of water. 
 
 The diameter of the cone =45 inches 
 Inclination =3 in. per foot 
 No. of ribs = 48 
 
 Revolutions per hour = 6 to 10 
 Work per hour = 4 to 10 cubic feet. 
 
 Hand Buddie. This is a box 12 to 14 feet long, 22 inches 
 wide and deep. The inclination for 12 feet may be from 20 to 6 
 inches. The latter is for very fine material. The sands are charged 
 about ^ a cubic foot at a time at the head of the box, and as they tend 
 to travel downwards are, raked upwards. When the buddle is nearly 
 filled, say in I hour, the deposit is divided into 3 parts, head, middle 
 and fail. These three parts are washed separately in other buddies. 
 It will be observed that as the material accumulates, the inclination 
 of the washing surface decreases and the head continually tends to 
 become poorer. 
 
 Sleeping: Tables. Are similar but wider than hand buddies. 
 They are used for fine material. 
 
 The Knife, Propeller or Impeller Buddie. This is an 
 inclined plane down which the sands flow. Close above this is a 
 revolving cylinder with projecting paddles arranged like a screw. As 
 these slowly rotate the lighter materials are forced off the side of the 
 inclined plane while the heaviest come out at the end. 
 
 Sweeping: Tables. Length 20 to 30 feet, 3 to 4 feet wide 
 and sides 6 inches high. They are used for finer materials than hand 
 buddies. 
 
264 
 
 When the table is covered with stuff, the slime is washed off, 
 after which the concentrated ore at the upper end of the table is 
 washed through a slit which is opened in the middle of the table. 
 Inclination for sands 10 to 12 
 slime 5 to 6 
 
 The diluted stuff that can be washed per minute is : 
 Sands .3 to .5 cubic feet containing from 6 to 10 Ibs. sand. 
 Slimes .08 to .12 ., .28 to .78 ., 
 
 The slimes ought to flow over the table at a low velocity. If they 
 move at a high velocity the particles may slide rather than roll and be 
 carried off with the tailings. 
 
 Convex Buddie. This may be described as a circular box 16 
 or 20 feet in diameter with a gently inclined conical bottom and sides 
 15 or 30 in hight. In the center there is a more steeply inclined cone 
 about 6 feet in diameter. The slimes and fine materials for which 
 these buddies are used is supplied at the center. It then flows down 
 the inner cone and drops about I foot upon the outer more gently 
 inclined cone. As it travels towards the periphery, its surface is gently 
 swept by brushes hanging from revolving arms, which are attached 
 to a central vertical shaft. 
 
 The arms revolve 3 to 6 times per minute. In 2 or 3 hours 
 the buddle may be rilled, the heavier materials remaining near the 
 center and the lighter round the periphery. The materials may then 
 be divided into head, middles or fore and hind krazers and tails, 
 and each product rewashed. A disadvantage is that as materials 
 accumulate the inclination changes. In Cornwall, ore with 2.y 2 to 3 
 per cent cassiterite is dressed up to 93 to 94 per cent, the loss in 
 tailings being from 3 to 6 Ibs of tin ore per ton. It is said that slimes 
 with i Ib. of tin to the ton may be washed with profit. 
 
 Concave Buddie. Here the base is inclined inwards at about 
 6, the central portion of the cone being a circular box about 6 feet in 
 diameter. Four revolving arms carry scrapers or brushes to sweep 
 the slimes as they flow inwards. Here there is a larger area for the 
 accumulation of the heads, and the slimes are more readily carried off 
 as the velocity of the inflowing stuff increases as it approaches the 
 center. The speed of the arms varies with the stuff. 
 
Sands 8 revolutions per minute. 
 
 Fine slimes 14 to 16 ., 
 
 Amongst other concave buddies there are Borlase?s where the 
 central outflow may be adjusted, and Sunday's, so largely used in 
 Australia. 
 
 Linlcenbach's tables. These tables are coned surfaces of iron 
 covered with cement and supported on iron frames. The supply pipes, 
 distributing aprons at the apex of these cones which are placed one 
 above the other, and the wash pipes, revolve. Single tables have 
 been made 26 feet in diameter. At Ems the apparatus concentrates 
 lead ore up to 38 per cent, but it has worked up to 65 per cent. 
 
 Percussion Tables. Percussion tables are tables suspended 
 by rods or chains so that they are free to swing. By means of a cam 
 they are pushed forwards and then suddently released, when they 
 swing back and strike a fixed block. The result of a succession of 
 these blows, which may be given at the end or side of the table, is to 
 cause the heavier particles of ore to travel towards the side or end of 
 the table where the blow is struck, more rapidly than the lighter 
 particles. 
 
 End blow Percussion Table. Length of the table 12 feet. 
 Breadth 5 feet. Height of sides n inches at upper end; 5 inches 
 at lower end. Length of chains and rods by which it is suspended at 
 upper end 4 feet, at the lower end 6 feet. Beneath the table is the 
 percussion rod which strikes against a fixed percussion block. 
 
 By raising or lowering the chains at the lower end, the inclination 
 of the table may be altered ; while by altering the point of attachment 
 to the table of the upper chains the effectiveness of the percussion may 
 be varied. When the percussion rod rests against the percussion block 
 the chains are not perpendicular. By the movement of the cams the 
 deviation of the chains from the perpendicular is increased. The 
 stuff enters and is distributed over the head of the table where the 
 blows are struck. As the heavier materials accumulate at this end, 
 the chains at the lower end may be raised and the slope of the wash- 
 ing surface kept constant. 
 
 A table 5 feet wide requires per minute. 
 Diluted sands .5 to .7 cubic feet; 
 Diluted slimes .10 to .17 cubic feet. 
 
266 
 
 One cubic foot of water may contain, Sands 2o to 40 Ibs., slime 
 5 to 10 Ibs. 
 
 No : of strokes per minute, for sands with elastic percussion 
 blocks 12 to 1 6 with rigid 40 to 50, slimes with rigid block 60 to 80. 
 Stroke. For sands 12 inches, for slimes 4.8 inches. 
 
 One table will wash per day of 10^ working hours from 16 cwt to 
 I ton of stuff. The total quantity of water required is .83 cubic feet 
 per minute. It does not give satisfactory results if the slimes are 
 tough. The tables are used for low grade slimes. The slimes which 
 flow off the table may be retreated from 3 to 12 times. One table can 
 treat per day (22 hours) 30 tons of coarse meal, 5 or 6 tons of pulp. 
 As the headings are retreated at least twice, the capacity per day be- 
 comes 8 to 10 tons of ore slime and i-i to 2 tons for pulp. The deposit 
 is allowed to accumulate until it is 6 to 8 inches thick and the time 
 required for this is 3 hours for ore sands, and 9 to 12 hours for pulp. 
 
 Tlit J/iilirig Compound Tanner, consists of several end blow 
 tables the surfaces being travelling bands so arranged that the middles 
 from upper tables are automatically fed upon the lower tables. It 
 treats 9 tons per 10 hours. 
 
 The Dodge Concentrator is an end blow table where the mineral 
 moves up the inclined concentrating surface, whilst the light worthless 
 material is swept downwards. 
 
 Hal/ey's Concentrator is an end blow table where the heavy mineral 
 is caught in a depression of the washing surface. 
 
 Ritting > er"s side blow table. In this table the blows are 
 given on one of the long sides. By means of a series of revolving cams 
 the table is pushed sideways against a long wooden spring. As each 
 cam passes, the table is suddenly released, and it then flies back to 
 strike the percussion block. The stuff is admitted at the upper end 
 of the table on the opposite side to that on which the blow is struck. 
 The lighter and larger particles tend to travel down the table in almost 
 a straight line, while the denser particles travel downwards more 
 diagonally, being finally discharged at the bottom of the table on the 
 side of the percussion block. The materials are therefore discharged 
 continuously. 
 
 Length of table 8 feet; breadth 4 feet. 
 
267 
 
 Two tables each of 4 feet wide are built on one frame. 
 
 The inclination varies between 6 and 3 degrees, the latter inclina- 
 tion being for fine materials. 
 
 Quantity of stuff supplied per minute. Sands 22 cubic feet, con- 
 taining per cubic foot 17 Ibs. of dry stuff. Slimes 10 cubic feet, con- 
 taining per cubic foot 6.8 Ibs. of dry stuff. 
 
 In 24 hours, one double table treats, sands 5.38 tons, slimes 
 1 .08 tons. 
 
 Clear water required per foot width. Sands 22 cubic feet. Slimes 
 13 cubic feet. 
 
 Strokes. Sands 70 to 80 per minute each 2 inches, slimes 90 to 
 100 per minute each to f inches, tough slimes 120 to 140 per 
 minute. 
 
 The wooden spring is II feet long, 3 inches wide, 2^- in thick. 
 
 Four double percussion tables concentrate 10 to 15^ tons in 24 hrs. 
 
 The loss is about 20 per cent. 
 
 .25 H.P. is required per table per hour. 
 
 On four double tables 10 to 15 tons may be concentrated in 24 hrs. 
 
 The washing surface is usually a fine grained wood, but surfaces of 
 iron, or slabs of marble give good results. The framing is of wood, 
 iron or steel. If two tables moving in opposite directions are fixed to 
 the same foundation the tendency to move laterally is neutralized. If 
 material is too coarse, say over 5 mm. so that it readily rolls, or if it is 
 too fine, say less than .25 mm. like certain pulp, it can not be satisfac- 
 torily treated on side blow tables. These tables give rich headings. 
 
 For pulp slime the Frtte Vanner or Embrey Concentrator, is better 
 than side blow tables. 
 
 Rotary Buddies. These buddies are employed for the con- 
 centration of fine sands and slimes. 
 
 C'oncave Buddie. In this buddle an inverted 
 cone or flat 16 faced pyramid, which is slowly rotated by a vertical shaft, 
 forms the washing table. The stuff to be washed is admitted at 4 or 8 
 points round the periphery. As the table turns, the stuff passes water 
 distributors, which wash the ore as it flows down towards the center of 
 
268 
 
 the table. Still farther and just in advance of the next ore distributor 
 each compartment comes beneath a strong }et of water which cleans 
 the section of the table over which it flows. At the lower end of each 
 section of the table there are holes which carry the various products 
 into different gutters and launders beneath the table. 
 
 Diameter of table 16 feet 
 
 Inner diameter 7 feet 
 
 Length of washing slope 4^ feet 
 Inclination 6 to 9 
 
 Revolutions per hour 4 to 6 
 
 Stuff passing each distributing board 8 to 12 inch wide per minute, 
 Cubic foot of sands ,35 
 slimes .15 
 
 Quantity of dry stuff per cubic foot, 
 
 Sands 10 Ibs. 
 
 Slimes 5 Ibs. 
 
 Loss 20 to 25 per cent. Ten to fifteen buddies require I H.P. 
 Water required per minute, 
 
 Sands 15 cubic feet 
 Slimes 8 
 Work per 24 hrs, 
 
 Sands 6 to 8 tons. 
 Slimes 2.8 to 3.6 
 
 Convex rotary buddle. These buddies are made from 10 
 to 1 8 feet in diameter. The inclination is about 5 One revolution in 
 2 /^z to 5 min. 
 
 There is only one charge for a complete revolution, when the 
 heavier materials are washed away by a strong jet of water. 
 
 They perform their work more quickly and better than ordinary 
 sleeping tables. 
 
 One half to three quarters H.P. per apparatus. Of an ore easily 
 dressed. 22.5 tons dry weight of coarse meal or 6 tons of fine pulp may 
 be washed in 22 hours. The grain of the wood on the table surface is 
 at right angles to the direction of flow. 
 
Good results may be obtained by mounting a concave buddle or 
 central discharge table above a convex buddle or outward discharge 
 table. 
 
 On the upper table coarse midlings will be deposited, the remain- 
 der (fine pulp) being washed on the lower table. Such an arrangement 
 has given satisfactory results at Clausthal. Fine pulp with 2-1 per cent 
 of low grade argentiferous galena has been profitably washed on round 
 tables. 
 
 Brunton's Table. In this machine there is a table 10 feet long 
 and 4 feet wide furnished at the ends with rollers carrying a cloth, 
 which beneath the table hangs down and dips in a tank of water. 
 The stuff is distributed on the cloth and the light particles flow down 
 its length. The heavier particles however are carried upwards against 
 the direction of the stream and over the end of the table down to the 
 tank of water where they are deposited. 
 
 Frue Tanner. In this machine a continuous rubber belt 4 feet 
 wide and 274 feet long passes over light rollers to form the surface of 
 an inclined plane on which the stuff is concentrated. Below, the belt 
 which is flanged, passes beneath rollers into a box containing water 
 where the concentrates are deposited. While the belt travels the table 
 is shaken back and forth laterally. 
 
 The belt travels up hill at from 3 to 12 feet per minute at the 
 same time receiving about 180 to 200 back and forth side shakings. 
 The^inclination of the belt is from 4 to 12 in. per 12 feet. 
 
 The surface of the belt lasts 2 or 3 months when it is painted with 
 rubber paint The belt receives ore from a distributor about 4 feet 
 from its upper end. As it travels upwards, it meets with small jets of 
 water^from a clear water distributor. 
 
 The water required is 3 to 6 gallons per minute. One machine 
 treats 6]tons per 24 hours of stuff passing a 40 mesh screen, or 2 Van 
 ners to 5 stamps. 
 
 Materials may be treated directly from the batteries and I man can 
 attend to 16 machines. Each machine requires one quarter H.P. 
 
 It does not appear to be well adapted to obtain middlings. In 
 gold washing where the mineral is often reduced by the stamps to a 
 finer condition than the gangue, from 80 to 85 per cent may .be -saved 
 A saving of 90 per cent has been attained. X^fcJr 
 
 ' 
 
270 
 
 Embrey Concentrator. This differs from the Frue Vanner 
 in that the shaking is longitudinal instead of lateral. 
 The Triumph Concentrator is very like the Embrey. 
 
 Golden Gate Sulplinret Concentrator. This consists of a 
 tray II feet in length which has a longitudinally reciprocating move- 
 ment. Material fed on the tray is caused to travel along it to a 
 " protecting plate " where the inclination of the tray changes. The 
 heavy material passes beneath this plate, and the light material above 
 it is drawn off by an exhaust pipe. 
 
 Rittinger's Separirtrichter. In this machine where advan- 
 tage is taken of centrifugal fore, a wing wheel revolves in a vessel 2 
 feet in diameter and 5-i feet high. The water contained in this vessel 
 being in revolution, the stuff to be separated is admitted above. As it 
 descends to the bottom, a portion of the stuff passes through a funnel, 
 whilst that which has been thrown the farthest outwards, descends 
 between the funnel and the sides of the containing vessel. 
 
 The falling ore may also be collected and discharged from radially 
 arranged compartments at the bottom of the cylinder. 
 
 21 ii nd Ts Rotating cylinder. (Stromsetz machine). In this 
 machine there is a tub divided radially at the bottom into a series 
 of compartments. In the center of this, revolving on a perpendicularly 
 placed shaft there is a double cylinder, the inner part of Jwhich is 
 slightly conical, with its base downwards. As the shaft revolves the 
 cylinders revolve, and with them the water in the tub. Ore is 
 introduced into the space between the cylinders, and as it falls is 
 separated. In consequence of the heavy material falling more per- 
 pendicularly than the lighter material which describes a flatter spiral, 
 the general result is that materials of different specific gravities reach 
 different compartments at the bottom of the tub, from which the 
 material as it accumulates is from time to time discharged. The tub 
 is about 5 feet in diameter and the radial compartments 17 inches high. 
 The space between the rotating cylinders at their base is about 2 inches. 
 With | inch grains, a five feet water column requires 3 revolutions per 
 minute. Coal requires 2 revolutions and i^ foot of water. 
 
 The speed and height of the water column vary with the size of 
 the grains. 
 
271 
 
 In another of Hundt's concentrators, the stuff descends two screw 
 shaped inclined planes which are broader at the bottom than at the 
 top and which revolve. on a shaft. 
 
 Doily Tub. The dolly tub or tossing kieve'is a tub about 3^ 
 feet diameter. Water is introduced, and then with a stirrerm dolly set 
 into a circular motion. While this is in progress, finely divided con- 
 centrated ore like tin or lead is introduced until the mixture is thick, 
 after which the stirrer is withdrawn and the mixture allowed to settle. 
 During the settling the outside of the tub is struck with a hammer and 
 the ore is packed. The rich heavy ore accumulates on the bottom 
 and the slime above. 
 
 The mixing takes about 15 minutes and the settling 2cTminutes. It 
 is used for headings from buddies, about 2 cwt being treated at a time. 
 
 In the Duncan concentrator the material is separated in a pan 
 making about 8 revolutions per minute the pan at the same time 
 havine a jigging motion. Three pans are required for 10 stamps. At 
 the Ashiwo mines it gives good results with copper ore. 
 
 The Hendy concentrator is a circular iron basin, the bottom slightly 
 convex with a circular trough round the periphery. The basin is 
 caused to turn in a quick vibratory manner on its center. K; , 
 
 The heavy materials are moved towards the trough where they 
 are discharged, while the tailings are discharged at the center. 
 
 Separation by means of a dense fluid. Rittinger points 
 out that by means of a solution of zinc sulphate (S G. 1.5 ), slate (S G. 
 2.6) might be separated from coal (S G. 1.31 inasmuch as the coal 
 would float and the slate would sink. In separating the constituents 
 of rock masses a solution of iodides of potassium and mercury S G. 
 3.19 may be employed. Methods of this description on account of the 
 expense of the solution can only be employed upon a small scale. 
 
 Under this head Rittinger includes the separation of gold which 
 when pure has a S G. 19.33 from associated minerals by means of 
 mercury S G. 13.6. In this case the separation is chiefly due to the 
 gold amalgamating with the mercury from which it is subsequently 
 separated by distillation. 
 
 Information about amalgamation may be found under the section 
 relating to stamps, grinding and tables. 
 
272 
 
 Magnetic Separators. Magnetic iron sand maybe concentrat- 
 ed by passing it over tables or belts beneath or above which, magnets are 
 placed (Conkling separator}; by passing the sand over or under magnetic 
 rolls (Bachanan and Wenstroirfs Separator}; or by allowing the sand to 
 fall in front of the pole of a fixed magnet, when the magnetic sand will 
 be deflected and the ordinary sand will fall vertically (Edison Separator}. 
 In the latter the magnet is 6 feet long, 30 inches wide, 10 inches thick 
 and wighs 3400 Ibs. It is excited by a current of 1 6 amperes with an 
 E.M.F. of 116.5 volts, consuming 2^ H.P. 
 
 For other separators, (see Trans.: Am.: Inst.: Min.: Voll XVIT. p. 
 728. also Vol XIX. p. 65. and p. 187). 
 
 Apparatus for Raising Material, &c. 
 
 RafF wheels. For raising slimes and sands, wheels are con- 
 structed on the principle of an Egyptian wheel. The diameter of 
 the wheel depends upon the height to which the material is to be 
 raised. The breadth of the wheels may be 6 to 9 in. At distances of 
 about I foot round the periphery spade shaped buckets are arranged. 
 These buckets branch from the periphery, at an angle of about 30. 
 Below, the wheel dips into a trough containing the material to be 
 raised, which is scooped up and discharged at the upper side of the 
 wheel. 
 
 Raff wheels are often employed in connection whith crushing by 
 rollers. The material after passing through the rollers is received in 
 a trommel where it is sized. The larger particles not passing through 
 the trommel are received in the buckets of a raff wheel and carried 
 upwards to be again passed through the rolls. 
 
 Centrifugal pumps are sometimes employed for slimes. 
 
 Jacob's ladders may be vised for various materials while for con- 
 veying material horizontally or up an incline of less than 30 an 
 endless band or an archimedian screw may be employed. 
 
 Treatment of amalgam. The gold amalgam is collected 
 and strained through a cloth and pressed into balls about \% inches 
 diameter. The gold contained is about 33 per cent. The squeezing 
 may be done in a screw press. The balls are then placed in a cast 
 iron retort and the mercury driven off by heat; time occupied being 2 
 or 3 hours. The loss of mercury is 3 per cent. 
 
273 
 
 To determine weight of sand or slime contained 
 in stuff* from boxes, batteries etc. 
 
 1. A given measure of the stuff is weighed, after which the 
 water is drained off and the sands or slime dried, when it is again 
 weighed. The difference between these weights is the weight of 
 solid material in the given quantity of stuff. 
 
 2. The density of the dry sand may be determined by 
 observing how much water is displaced by a given weight of the 
 sand when introduced into an ordinary specific gravity bottle. 
 
 4. Rittinger recommends that a graduated glass tube, each 
 division of which corresponds to .025 cubic inch of water be 
 filled with water to a division //, after this p grains of the dry 
 sand are put in and the water rises to the division n\. The density 
 $ is then given by the formula. 
 
 s= I59 8 / 
 n\ n 
 
 4. Another method recommended by Rittinger to find the weight 
 P and the density d of the sand, is as follows. 
 
 Let a 1/2 or 3/4 litre bottle be half rilled with the wet sand and 
 then filled up with water. The weight of this=/ > i 
 
 Remove the water and then fill up to the same mark with a 
 solution of zinc sulphate (S G. 1.5) The weight of this = -P;> 
 
 Now if v = volume, S the density of the sand. 
 7'1 = Si = I water. 
 v% = S 2 = zinc sulphate. 
 
 Then P 2 = v S y -f- v 2 62 "/ 
 
 p =v6r 
 
 PI 62 - 
 
 p= 
 
 S =-= 
 
 62-1 
 Pi 62 - p* 
 
 2i fa -Oft + 02) 
 
274 
 
 MACHINERY REQUIRED IN MIL.I.S (Fraser and Chalmers]. 
 Ten Stamp Wet Crushing Silver 
 
 I No. 2 Blake Crusher 10 X 7 inches. 
 
 1 Grizzley or ore screen 4 feet X 10 feet. 
 
 2 Tulloch automatic ore feeders. 
 
 lo Stamps of 850 Ibs. each in one battery including all iron work, 
 wooden pulley and hard wood guides for stamp stems. 
 I Set of water pipes for battery. 
 6 Combination amalgamating pans 5 feet diameter complete. 
 
 3 Combination settlers 8 feet diameter complete. 
 I Clean-up pan, 4 feet diameter, complete. 
 
 I Set of water pipes with hose for pans and settlers. 
 
 I Set of steam pipes from boiler to pans. 
 
 I China pump to return surplus water from settling tanks to 
 supply reservoir. 
 
 I Automatic quicksilver system complete, including quicksilver 
 elevator, distributing tank, bowls and pipes. 
 
 3 Amalgam safes. 
 
 I Amalgam car. 
 
 i Retort 12 inch 4 feet complete with smoke stack. 
 
 I Sheet-irom plate for retort-room floor. 
 
 I Bullion melting furnace with crucible, tongs and bullion mould. 
 
 I Overhead crawl and one ton differential pulley block with chain 
 to be placed over stamps. 
 
 I Do. of two ton capacity over pans. 
 
 All track iron and nails for crawls. 
 
 I Line of shafting running under pans and coupled to engine, 
 with bearings and pulleys to drive pans and settlers. 
 
 I Countershaft for stamps with bearings and pulleys. 
 i Countershaft for crusher with bearings and pulleys. 
 
 All belting and lace leather. 
 
 i Corliss engine 14 X 42 inches. 
 
 I Tubular boiler 45 x 1 6 inches complete. 
 
 i No. 3 steam teed pump. 
 
 I Tubular heater 20 inches diameter. 
 
 All pipe connections to make power complete. 
 
The capacity of the above mill averages about 25 tons of ore each 
 24 hours. 
 
 The steam power described is of capacity for the 10 stamp mill 
 only as described. It is advisable to put in an engine capable of dri- 
 ving a 20 stamp mill necessitating a Corliss engine 18 x 42 inches 
 and when the additional 10 stamps with pans and settlers, etc., are 
 added, a second 54 X 16 boiler must then be introduced. 
 
 Ten Stamp Dry Crushing: Silver Mill, 
 
 I No. 2 Blake crusher 10 X 7 inches. 
 I Grizzley or ore screen 4 feet X 10 feet. 
 
 3 Tulloch automatic ore feeders (one for ore dryer). 
 
 I Automatic revolving ore drying cylinder 44 x 36 inches x 18 
 feet complete. 
 
 IO Stamps of 850 Ibs. each in one battery, including all iron work, 
 wooden pulleys and hard wood guide boxes for stamp stems. 
 
 I Screw conveyor for front and back of stamps to convey pulp 
 to elevator. 
 
 i Elevator with belt, elevator cups, pulleys and shafts. 
 i Screw conveyor, overhead from elevator to furnace hopper. 
 I Roasting furnace, either Bruckner, Howell, White, O'Harra or 
 Stetefeldt. 
 
 1 Hot ore car and track iron with nails. 
 
 4 Combination amalgamating pans 5 feet dia. 
 
 2 Combination amalgamating settlers 8 feet dia. 
 
 1 Clean-up pan 4 feet dia. 
 
 2 Set of water and steam pipes for pans and settlers, 
 
 I Line shaft running under pans and coupled to engine with 
 bearings and pulleys to drive pans and settlers. 
 
 I Countershaft for stamps with bearings and pulleys. 
 I Countershaft for crusher and ore dryer with bearings and 
 pulleys. 
 
 I Countershaft for roasting furnace with bearing and pulleys. 
 
 All belting and lace leather. 
 
 i Amalgam retort 12 incites X 4 feet, complete, with smoke stack. 
 
2 7 6 
 
 to be 
 
 Plate for retort room floor. 
 
 Bullion melting furnace with crucible tongs and bullion mould. 
 Overhead crawl and one ton differential pulley block with chain 
 placed over stamps. 
 
 Do. of two ton capacity to be placed over pans. 
 
 Corliss engine 14 X 42 inches. 
 
 Tubular boiler 54 inches X 16 feet, complete. 
 
 Steam feed pump No. 3. 
 
 Tubular heater 20 inches dia. 
 
 All pipes, valves and fittings to connect engine, boiler, pump and 
 heater to make power complete. 
 
 The capacity of the above mill averages 15 tons each 24 hours. 
 
 The steam power described is of capacity for the lo stamp 
 mill only as described. It is advisable to put in an engine capable of 
 driving a 20 stamp mill neccessitating a Corliss engine 18 X 42 inches 
 and when the additional 10 stamps with pans and settlers, etc, are 
 added, a second 54 inches X 16 feet boiler must be added. 
 
 Ten Stamp Gold Mill, 
 
 
 
 i No. 2 Blake crusher 10 x 7 inches. 
 
 1 Grizzley or ore screen 3 feet X 10 feet. 
 
 2 Tulloch automatic ore feeders. 
 
 lo Stamps of 850 Ibs, each in one battery, including all iron work, 
 wooden pulley and hard wood guides for stamp stems. 
 
 1 Set of water pipes for battery. 
 
 2 Copper table plates 54 inches X 8 feet X I to 8 inches thick, 
 pure L.S. copper free from flaws. 
 
 4 copper lining plates for mortars 3 to 16 inches thick, same 
 quality. 
 
 Amalgam retort and condenser. 
 
 Countershaft for stamps with bearings and pulleys. 
 
 Countershaft for crusher with bearings and pulleys. 
 
 All necessary belting and lace leather. 
 
 Engine 9 X 14 inches 20 H.P. 
 Boiler 40 inches x 10 feet, complete. 
 
hours. 
 
 277 
 
 I Feed pump with belt, 
 i Heater. 
 
 AlKpipe connections to make power complete. 
 
 The capacity of this mill will average 25 tons of ore each 24 
 
 Power required for a lO-Stump Wet-Crushing 
 Oold 
 
 1 " Blake " rock-breaker, 'No. 2 .................. = 6 horse power. 
 
 2 Ore-feeders .......................................... = o 
 
 i o Stamps, 750 Ibs., 90 drops ..................... = 12 
 
 4 Frue Vanner concentrators .............. . ...... = 2 
 
 I Grinding pan. 3 feet diameter .................. = 3 
 
 i Settler ............................................... = 3 
 
 Friction ...................................................... = 4 ,, 
 
 Total ............................................. =30 *yiitiwO 
 
 The above fornijOfgmill is capable working 15 to 18 tons per day 
 of twenty four hours. 
 
 Power required for a 2O-$tatnp W<>t-riishingrJ 
 Gold 
 
 I " Blake " rock-breaker, No. 2 .................. = 6 horse power. 
 
 4 Ore-feeders .......................................... = o 
 
 20 Stamps, 750 Ibs., 90 drops ..................... =23 
 
 8 Frue Vanner concentrators ..................... = 4 
 
 I Grinding pan, 3 feet diameter .................. = 3 
 
 I Settler ................................................ = 3 
 
 Friction ...................................................... = 7 
 
 Total J =46 
 
 The above is capable of working 35 to 40 Ions of ore per day of 
 twenty-four hours. 
 
Power required for a KKStamp Wet-Crushing: Silver Mill. 
 
 1 " Blake " rock-breaker, No. 2 = 6 horse power. 
 
 2 Ore-feeders = o 
 
 10 Stamps, 750 Ibs., 90 drops = 12 
 
 6 Grinding pans, 5 feet diameter = 30 
 
 3 Settlers, 8 feet diameter = 9 
 
 Friction = 7 
 
 Total = 64 
 
 The above power is capable of working 18 to 20 tons of ore per 
 day of twenty-four hours. 
 
 Power required for a 20-Stamp Wet-Crushing: Si Ivor Mill. 
 
 I " Blake " rock-breaker, No. 2 = 6 horse power. 
 
 4 Ore-feeders . = o 
 
 20 Stamps, 750 Ibs., 90 drops = 23 
 
 12 Grinding pans, feet diameter = 60 
 
 6 Settlers, 8 feet diameter = 18 
 
 Friction = 13 
 
 Total = 120 
 
 The above power is capable of working 40 tons of ore per day of 
 twenty-four hours. 
 
 Allowance is made for grinding in the pans in both of the above 
 cases. 
 
 Power required for a lO-Stamp Dry.C mailing; Silver Mill. 
 
 1 " Blake " rock-breaker, No. 2 = 6 horse power. 
 
 2 Ore-feeders = o 
 
 io Stamps, 750 Ibs., 90 drops = 12 
 
 1 " Howell White " furnace, 40 inches = 4 
 
 4 Amalgamating pans, 5 feet diameter = 8 
 
 2 Settlers, 8 feet diameter = 6 
 
 Friction = 9 
 
 Total =45 
 
279 
 Water required for a'Quartz Mill. 
 
 The quantity of water required to work either golcPTor silver'ores 
 by wet battery process is generally estimated as follows : 
 
 For boiler, 7-i gallons per horse power per hour. 
 
 For each stamp, 72 gallons per hour. 
 
 For each pan, 120 gallons per hour. 
 
 For each settler, 60 gallons per hour. 
 
 If the water used in the battery, pans!f and settlers be run into 
 settling tanks it can be re-used with a loss of about 25 per cent. 
 
 Ten-Stamp Free Ore Kil ver'.>lill. 
 
 (Sixth annual Report of the State Mineralogist?? California 1886) 
 
 One 4 feet by 12 feet grizzly. 
 One 8 by 10 Blake crusher. 
 Two automatic ore feeders. 
 
 One 10 stamp battery, 750 to 800 pound stamps. 
 Four 5-foot combination amalgamating pans. 
 Two 8-foot settlers. 
 One 3 foot clean-up pan. 
 One amalgam safe and strainer. 
 One quicksilver elevator, with tanks, pipes, etc. 
 Two traveling crabs for battery and pans. 
 One 14 inch silver retort. 
 One melting furnace. 
 Shafting, pulleys, boxes, etc., for mill. 
 Belting for mill. 
 Pipes and fittings complete. 
 
 One Duncan concentrator for saving quicksilver and amalgam. 
 Weight of the above, 87,000 pounds. 
 Power required: 
 
 One 5-horse power engine. 
 
 One 5o-horse power boiler. 
 
 One 5o-horse power feed-water heater. 
 
 One No. 3 steam pump. 
 
 Steam and water connections. 
 
 Weight of the above, 24,500 pounds. 
 
 Total weight of the above, 111,500 pounds. 
 
 
280 
 
 Twenty-Stamp Free Ore Silver Mill. 
 
 One 4 feet by 12 feet grizzly. 
 
 One 8 by 10 Blake crusher. 
 
 Four automatic ore feeders. 
 
 Two 10 stamp batteries. 
 
 Eight 5-foot combination pans. 
 
 Four 8-foot settlers. 
 
 One 4-foot clean up pan. 
 
 One quicksilver elevator, with tanks, pipes, etc. 
 
 Three traveling crabs and track for batteries and pans. 
 
 Two amalgam safes and strainers. 
 
 Two 14-inch silver retorts. 
 
 One melting furnace. 
 
 Shafting, pulleys, boxes, etc., for entire mill. 
 
 Belting for entire mill. 
 
 Pipes and fittings for mill. 
 
 One Duncan concentrator, for saving amalgam and quicksilver. 
 
 Weight of the above, 180,000 pounds. 
 
 Pcnuei' required: 
 One loo-horse power engine. 
 Two 5o-horse power boilers. 
 One So-horse power feed water heater. 
 One No. 4 steam feed pump. 
 S'eam and water connections. 
 Weight\>f the above, 5o,ooo^pounds. 
 Total weight of the above, 230,000 pounds. 
 Grizzly, 4 feet by 12 feet, weighs about 2,000 pounds. 
 8 by lo Blake crusher weighs about 8,000 pounds. 
 Automatic feeder weighs about 700 pounds. 
 5-foot pan, combination, weighs about 6,200 pounds. 
 8-foot settler weighs about 6,000 pounds. 
 
 Ten-Stamp Gold 
 
 One grizzly, 4 feet by 10 feet. 
 
 One 8 by 10 Blake crusher. 
 
 Two automatic ore feeders. 
 
 One lo-stamp battery, 750 pound to 800 pound stamps, 
 
One traveling crab for battery. 
 
 Sixty square feet of silver-plated copper plate,' No. 14 guage, 
 
 plated I ounce of silver to the square foot. 
 Shafting"for mill. 
 Battery, pipes, andTittings. 
 Belting for mill. 
 One gold retort. 
 Weight of the above, 37,500 pounds. 
 
 Power required: 
 
 One 25-horse power engine. 
 
 One 3O-horse power boiler. 
 
 One 20 horse power feed water heater. 
 
 One No. 2 steam pump. 
 
 Steam and water connections. 
 
 One No. 2 steam pump. 
 
 Steam and wafer connections. 
 
 Weight of the above, 10,500 pounds. 
 
 Total weight of the above, 48,000 pounds. 
 
 Twenty-Stamp Gold 
 
 One grizzly, 4 feet by 12 feet. 
 
 One 8 by 10 Blake crusher. 
 
 Four automatic ore feeders. 
 
 Two lo-stamp batteries, 750 pound to Soolpound stamps. 
 
 Two traveling crabs for batteries. 
 
 One bunded and twenty square feet silver-plated copper plates, 
 
 No. 14 gauge, plated I onnce of silver to the square foot. 
 Shafting for mill. 
 Battery pipes and fittings. 
 Belting for mill. 
 One gold retort. 
 Weight of the above, 72,000 pounds. 
 
 Power required: 
 
 One 5o-horse power engine. 
 
 One 5o-horse power boiler. 
 
 One 5-horse power feed water heater. 
 
 One No. 3 steam pump. 
 
282 
 
 Steam and water connections. 
 Weight of the above, 24,500 pounds. 
 Total weight of the above, 96,500 pounds. 
 
 Specifications of' Twenty. Stamp Gold Quartz Hill for 
 
 the Buchanan mine, Tuoluinne county, 
 
 California. (J. Hamilton^ 
 
 One (i) Grizzly, to be made off inch by 2^ inch wrought iron, 12 
 feet long, 4 feet wide j spaced 2 inches between the bars, and secured 
 by three f inch bolts, and cast-iron thimbles and washers ; also end 
 bars. 
 
 Rock Breaker. One Blake crusher, fitted with two flywheels, 
 4 feet in diameter, and one (i) pulley, 30 inches in diameter, and 
 12 inch face crankshaft, to have outboard bearings; holding-down 
 bolts for each, to be long enough for 14 inch timbers ; all caps for 
 boxes to be fitted to use zinc oil cups, and " Albany " lubricating com- 
 pound. 
 
 Battery. Four (4) single discharge gold mortars, each weigh- 
 ing about 5,000 pounds; the bottoms to be 6 inches thick; well 
 planed ; the screw frame bearings to be planed also ; the bases to be 
 26 inches wide, 3 inches thick, and cored for eight (8) mortar bolts i-| 
 inches in diameter ; the feed mouth to be 26 inches long and 3^ inches 
 wide, at the smallest part ; the mortars to be well finished, and to be 
 56 inches long, and about 52 inches high. 
 
 THortar Bolts. Thirty-two (32) mortar bolts, i-i inches in 
 diameter, and 36 inches long; nuts on both ends, and thirty-two (32) 
 4 inch square countersunk washers for the lower ends; one (I) 
 wrought-iron wrench; jaw designed for the nuts of mortar bolts; arm 
 to be 6 feet long, slightly curved, made of I inch by 2-J inch iron. 
 
 Stamp Dies. Stamp dies, 7 inches deep, 8-1 inches in diameter, 
 with square bases, having beveled corners, and all made to properly 
 fit the mortars, and to be cast of the best car-wheel iron ; stamps to 
 weigh 850 pounds each. 
 
 Shoes. Twenty (20) stamp shoes, 8 inches in diameter, 7^ in- 
 ches long; to be cast of the best car-wheel iron. 
 
Heads. Twenty (20) stamp heads, 8^ inches in diameter, 18 
 inches long; keyholes to be 1^ inches by 3 inches ; one (i) key for 
 driving out shoes and stems, and to be made as may be directed. 
 
 Tappets. Twenty (20) double-faced gib tappets, made of the 
 best steel faces, 9 inches in diameter; tappets to be 12 inches long; 
 bands or flanges turned, and each to have gibs and three (3) steel keys, 
 and all to be marked ; keys to be boxed for shipment. 
 
 Cains. Twenty (20) double-armed cams, made of best steel ; ten 
 (10) to be right, and ten (10) to be left-handed; hubs on one side, and 
 to be strongly banded with J inch by 2 inches wrought iron bands, well 
 shrunk on ; the faces of the cams to be well smoothed, and to be fitted 
 to 5^ inches cam shafts, and to be properly marked. 
 
 Feeders. Four (4) Hendy Challenge ore feeders, complete with 
 all latest improvements; also, twenty (20) steel keys for same, to be 
 marked and fitted, and properly boxed for shipment ; the cams to be 
 about 32 inches long, with 2-k inches face, and struck to give an & 
 inches drop if required. 
 
 Corner Boxes. Six (6) corner boxes, for 5^ inches cam shafts ; 
 cored for I inch bolts; backs to be planed true, and bearings to have a 
 strip running lengthwise, and the balance of the bearings to be well 
 babbitted and bored : the ends to be faced; the cap to be solid, bored, 
 but not babbitted, unless required, and bored with three (3) inch 
 holes each, for using "Albany" compound. 
 
 Cain Shaft*;. Two (2) cam shafts, 5^ inches in diameter, and 
 14 feet 6 inches long, and key-seated between bearings. 
 
 Jack Shafts. Four (4) jack shafts to be 3 inches in diameter 
 and 59 inches long, with eight (8) bearings for same, and to be made 
 of cast-iron. 
 
 Stems. Twenty (20) stamp stems 3^ inches in diameter, 14 feet 
 long ; turned and. tapered oft" both ends for heads ; made of rolled iron. 
 
 Latch-sockets. Twenty (20) open latch-so k e ts; all to be well 
 lined with heavy leather. 
 
 <; uides. For (4) complete sets of best white oak guides. The 
 lower guides to be 16 inches wide and 4 inches thick, and the upper 
 
2 8 4 
 
 to be 14 inches wide and 4 inches thick ; bored for 3^ inches stamp 
 stems, and to be 10 inches between centers ; all to be 60 inches long. 
 
 Cam-shaft Pulleys. Two (2) wood pulleys, 72 inches in 
 diameter, with 16 inches faces and 6 inches thickness of wood between 
 the flanges, and to be made of the best kiln dried sugar pine ; to be 
 turned and well bolted to 40 inches diameter cast-iron sleeves ; flanges 
 for 5 inches cam shaft; the flanges to be faced. 
 
 All of the keys for this mill to be made of the best steel. 
 
 Overhead Crabs. One (i) crab for battery having flanged 
 wheels 7 inches in diameter and 2 feet face ; the axles to be I J inches 
 square and long enough to set the wheels 10 inches between the 
 flanges ; the boxes to be I inches thick, and all made of the best 
 wrought iron. 
 
 Piping:, etc. All piping, hose, valves, bibs, cocks, ells, tees, 
 unions, etc,, to be furnished as per detailed bill. All necessary bolts, 
 belts, nuts, and washers, also copper plate for battery and aprons, to be 
 furnished of proper weight, and as shown on drawings, -J inch thick, 
 not plated; also, silver-plated copper plate, 20 inches wide and 20 feet 
 long. 
 
 Belting-. One (i) main driving belt, to be about 55 feet long, 20 
 inches wide, and made of the best 5 ply rubber of the "Boston Belting 
 and Packing Co.'s " manufacture, patent stretched. 
 
 Battery Belts. One hundred and ninety (190) feet of the best 
 5 ply rubber, 16 inches wide. 
 
 Rock Breaker Belt. Ninety (90) feet of 4 ply rubber, 12 
 inches wide. 
 
 Boxes for Shafting:. All boxes to be planed on the bottom 
 and faced on the ends, and to be well babbitted, and the caps to be 
 bored with -| inch holes, for Tatum & Bowen's lubricating compound. 
 Two (2) steel collars and set-screws for each. 
 
 Shafting: and Pulleys. One (i) main battery line shaft to be 
 made in two lengths, 4 inches in diameter, 20 feet long, and 3^ inches 
 diameter, 20 feet long, coupled together with solid coupling. One (i) 
 countershaft for driving rock breaker, 3 inches diameter, 20 feet long ; 
 
both shafts fitted with all necessary bearing boxes, and holding down 
 bolts for 14 inches timbers. 
 
 Pulleys. One (i) main driving pulley to be fitted to engine 
 crank shaft at mine, to be 48 inches diameter, 21 inches face. 
 
 One (i) pulley for main battery line shaft, to be 72 inches dia- 
 meter, 21 inches face, 4 inches gauge. 
 
 One (i) pulley to drive crusher countershaft, 40 inches diameter, 
 12^ inches face, 4 inches gauge. 
 
 One fi) pulley to drive battery, 34 inches diameter, i6- inches 
 face, 34 inches gauge. 
 
 One (i) pulley to drive crusher, about 40 inches diameter, I2 
 inches face, 3 inches gauge. 
 
 One (i) pulley on crusher countershaft, 26 inches diameter, 12^ 
 inches face, 3 inches gauge. 
 
 Tighteners. Two (2) battery tighteners, 16 inches diameter, 
 20 inches face, with racks, pinions, frame?, handwheels, pawls, and 
 pawl plates, complete for stopping and starting the batteries. 
 
 One (i) rock breaker tightener complete, as above specified, for 
 stopping or starting the crusher. 
 
 All necessary bolts for batteries and buildings, and all necessary 
 belt rivets for securing the belts. All belting used in this mill to be 
 of Boston Belting Co.'s manufacture, best quality and patent stretched. 
 
 All castings to be made of good material, smooth and free from 
 blow-holes or other imperfections. All keys to be made to fit and 
 properly marked. 
 
 Mortars are to be cast from selected patterns or drawings, which 
 will be furnished. 
 
 Should anything be lacking to complete this mill which has not 
 been specified, it must be supplied the same as if fully mentioned. 
 
 Everything to be delivered on the ground (at company's expense), 
 and timbers to be cut according to plans to be supplied. 
 
 NOTE. The company already had an engine and boiler. The 
 building, also, over the mill was built by the company. The cost of 
 the above material^was $5,985, and of the labor, $2,300. Save a slight 
 
286 
 
 change in the tappets, the work was satisfactorily done, and the mill 
 crushed over two tons per stamp, of hard quartz, every 24 hours. 
 
 The total cost of grading, building, machinery, etc., was a little 
 short of $15,000. 
 
 Examples of Processes. 
 
 The first seventeen of these examples are recommended by Fraser 
 and Chalmers, manufacturers of mining machinery in Chicago. 
 
 1. For free gold that can be panned out and no spuUmrets. Wet 
 
 stamping and quicksilvered copper plates. In the Black Hill 
 $8 ore yields good returns, the milling only costing 60 cents per 
 ton of ore. 
 
 2. Free gold with sulphurets. By sulphurets are meant iron and 
 copper pyrites, galena, blende. Tellurides, selenides, antimonides 
 may also occur with these ores together perhaps with silver. 
 
 Wet stamping and catching the products in blankets or hides. 
 Subsequent treatment in a pan or arrastra. A better method is, 
 wet stamping and quicksilvered copper plates. The tailings are 
 treated on a vanning machine (two of Frues vanners to 5 heads 
 of stamps) subsequent roasting, treatment with chlorine gas and 
 lixivation with water, the gold being precipitated with ferrous 
 sulphate. Chlorination costs 8 to 10 $ per ton of concentrates. 
 Another process is to roast and amalgamate in pans. 
 
 3. Free gold in small quantity but with much silver in the sulpJmrets. 
 
 Roasting milling or free gold milling with Vanners for the 
 tailings and subsequently smelting. Sulphides foul amalgam. 
 When these are present dry stamping, mixing with salt, roasting 
 to form chlorides and then lixivationf The alternative is to smelt 
 the concentrates. 
 
 4. Chloride of silver, native silver at id decomposed portions of silvee vein 
 out crops containing over 6 oz per ton. Free silver milling. 
 
 5. Silver ores, partly chloride and partly silver bearing snlphureis. 
 
 Free milling, Vanners and smelting (see 3). For high grade ore, 
 roasting milling (see 3). 
 
 6. Silver ore with base metal sulphuret if low grade. Fine concentra- 
 
 tion and smelting or for higher grade, roasting and milling. 
 
28 7 
 
 By fine concentration is meant fine crushing and treatment 
 on Frue Vanners, revolving buddies, Evan's slime table, Rittinger's 
 tables, end blow tables or some form of slime machine. The 
 process costs $i to $2.50 per ton. Smelting cost SS to $30 per ton. 
 
 7. L0iu (trade silver ores with gray copper, ruby, bridle or native silver. 
 
 Fine concentration and smelting. 
 
 8. Heavy mineralized ores of lead, copper, zinc often carrying silver. 
 Fine concentration and smelting. 
 
 9. Highly mineralized ores of lead, copper and zinc. Fine concentra- 
 tion and smelting. 
 
 10. Carbonate or oxide of lead and copper. Smelting. 
 
 11. Solid galena. Hand selection or coarse concentration and smelt- 
 ing. Coarse concentration means, coarse crushing, sizing on re- 
 volving screens, jigging and treatment of slimes on a slime machine. 
 In Western camps it costs Si to $3 per ton. 
 
 12. Metallsc copper ores. Stamping, coarse concentration and melting 
 to ingot. 
 
 13. Antimony ores. Hand picking, concentration and smelting for 
 metal. 
 
 14. Zinc blende and zinc carbonate. Coarse or fine concentration and 
 reduction by zinc smelting process. 
 
 15. Tin ores. Fine concetration, roasting and smelting. 
 
 16. Copper pyrites, copper glance. Hand picking, concentration, 
 partial roasting and matting; or if convenient selected and con- 
 centrated products are sent to refineries. If of low grade, lixivation 
 for copper and silver. 
 
 17. Heavy iron pyrites carrying gold. Chlorination process or roasting 
 and intermixing with ores for smelting. 
 
 1 8. For lead, silver lead, with blende, pyrites &c. the following 
 installation may be employed. 
 
 Crushing rolls, revolving classifier, the coarse material from 
 which returns to the rolls. The remaining material is sized and 
 delivered to corresponding jigging machines. The slimes pass to 
 pointed boxes and the coarsest of these may go to fine jiggers or the 
 whole of them to a rotating buddle. George Green of Aberystwyth 
 
288 
 
 recommends for a capacity of 15 tons per day, .3 self acting, jiggers, 3 
 patent classifiers and 3 round buddies. (With wooden hutches jiggers 
 cost 270, with iron hutches ^310). (Rolls 28 inches X 16. inches 
 capacity per day of 35 tons, cost ^140). 
 
 19. Port Philip Company, Climes, Victoria. Ore, 
 gold quartz with pyrites. Machines, Two Appleton's rock brea- 
 kers. Stamps 80 heads, square heads 6 to 8 cwts each. Grates 
 thick copper plates with 84 holes' to sq. in., buddies to collect 
 pyrites each 24 feet diameter, 5 amalgamating barrels. Shaking 
 table. Two Chilian Mills for grinding roasted pyrites, one 24 
 inches cylinder engine 60 H. P. working up to 120 //. P. 
 
 20. Defiance mills. Charters Towers, Queensland. 
 Ore, gold quartz with pyrites. Machines, Battery 25 heads. 
 Quicksilvered copper plates, shaking table and plates, convex 
 buddle, sands entering at periphery, with Mondy's patent scrapers, 
 Wheeler's pans and Berdan pans. 
 
 21. Mount ISishoff, Tasmania. Ore, tin stone in loose 
 soil which is dressed from \\ or 2\ per cent up to 72 or > ]^%. 
 The ore is first roughly washed in sluices, the coarse stuff going to 
 three mills. In the first two mills the plan is approximately as 
 follows. 
 
 Stamps 
 
 Revolving sieves, fine material to pointed boxes 
 
 r ' ~~i 
 
 Fine stuff Coarse stuff 
 
 Fine quick jigs Coarse slow jigs 
 
 I ~1 II 
 
 Black Tin Buddies Black Tin Buddies 
 
 Revolving tables Revolving tables 
 
 I I 
 
 Waste to 3rd Mill 
 
 Pointed Boxes. Revolving 
 
 table for slimes. Concave Buddies. 
 
289 
 
 22. Walnut free Bridce Colliery. By a Jacob's ladder 
 the coal is dropped into a hopper where it meets a stream of 
 water. From the hopper it passes down an inclined plane to an 
 iron jigger. The small coal u>ed for coke conies from the bottom 
 of the jigger while the clean coal passes over the lip. 
 
 23. Miners* Lead Mine, Xr. WrexZiam. Ore, galena 
 with much blende. Gangue, limestone. Machines, a pair of 
 rolls, 4 hand jiggers, 6 or 7 square buddies and one circular buddle. 
 Smalls go to settling pit and fine material is treated in square 
 buddies. Produce 500 tons blende, and loo tons galena per 
 month. 
 
 24. Van Lead Mine, Wales. Ore, galena, with blende, 
 a little copper pyrites and earthy matter. Treatment^ picking, 
 Blake's crusher, rolls. The smalls go by a launder to pointed 
 separating box. The fine material goes to concave buddies and 
 the remainder to jiggers. The purest material is washed in 
 square buddies while other ore from the jiggers is washed by hand 
 and the mixed ore is ground fine and then washed on an Impeller 
 buddle. The fines from the separating box go to a conical buddle 
 18 feet diameter. Produces 100 tons blende, and 200 tons of 
 galena per month. Cost of dressing works ^"60,000. 
 
 25. Roman Gravel Lead Mine 3Fr. Shrewsbury. 
 
 Ore, galena, blende with calcite and blue elvan country. Treat- 
 ment Spalling, yielding rich, middle and waste. Washing and 
 picking. In the mill we have, 
 
 Rolls, two revolving sizing sieves giving materials to two classes 
 of jiggers. The fine materials from the sieves and rolls pass to two 
 sizing boxes with upward currents of water, each of which give material 
 to a set of fine jigs with II or 12 holes per inch. The fine slimes pas- 
 sing the sizing boxes pass to a settling box and then to circular 
 buddies. Mixed ore from jigs is recrushed and washed on a special 
 jigg er - 
 
 The first revolving sieve has 4 holes per inch and the second 5 
 holes. 
 
 Produce about 300 tons of galena per month, dressed to 82 per 
 cent of lead. 
 
290 
 
 26. I,an-ley Barony !,<>ad mine (Nr. Newcastle}. The 
 ore is galena with calcite, barytes, a little quartz, earthy matter 
 and very little blende. Here are rolls, trommels, jigs as above. 
 The finest materials is treated on a convex revolving buddle, the 
 clean ore being washed off at the end of each revolution. There 
 are three qualities of dressed ore, with 81, 76 and 73 per cent 
 of lead respectively. 
 
 27. S. I VPS Consols, Cornwall. Ore, tin and grey 
 copper. Jreatnient, Moderate concentration on buddies and 
 frames. Roasting in Brunton's revolving calciner. Washing in 
 square buddies to get rid of copper sulphate from which the 
 copper is precipitated with iron. Tin stuff washed on revolving 
 table. Tossing and packing. 
 
 28. Levant Mine. Cornwall. Ore, tin stone and coppei 
 pyrites. Produce 100 tons of copper and 12 to 20 tons of concen- 
 trated tin stuff per month. Process. picking and the copper ores 
 after rough treatment sold. For tin ore; stamping, buddies 25 
 feet in diameter (buddling repeated three times) tossing and 
 packing in a kieve. Roa-ted for 24 hours, the arsenic fumes being 
 caught in a flue. Roasted ore sprinkled with water and copper 
 sulphate removed in solution. Buddling. 
 
 29. Malleiiear Copper Mine. Ore, copper pyrites 
 blende, galena, iron pyrites with fluor spar, quartz calcite &c. 
 
 Process, Ore descends over grates to dressing floor. The top 
 grate of bar iron 4 inches apart, to lower grate of round iron I inch 
 apart. Sometimes ores are picked and sized and then repicked. 
 Four classes of ore (A,B,C,D.) are obtained and are treated as follows. 
 
 A. Large. Divided into 4 parts. 
 
 1st best work, crushed to \ inch square, sold. 
 2nd class work, cobbed and separated to waste and best. 
 The latter crushed to \ inch square, sold. 
 
 3rd class work, jigged and waste to heap. 
 4th class blende and galena. 
 
 B. Middles which do not pass I inch holes, go to a water pit and 
 then classified into four divisions as above. 
 
291 
 
 C. Which does not pass i inch holes. Washed with hand sieves 
 and classified as above. 
 
 D. Which pass J inch holes. Hand jigged on sieve, 5 holes per 
 in. The waste scraped from the top. Result gives, prills which are 
 sold, and dradge with 3rd class from above which goes to machine jig. 
 
 Waste or enemy rejigged by tributers. Fine from all the 
 above goes to square buddle. The material for machine jigging is put 
 through a pair of 2/6 // rolls and a revolving sieve 5 holes per inch. 
 After this it is sized by other sieves and the different sizes treated 
 separately in three jigs. Refuse goes to slime pit. Rich from bottom 
 of jigs to setting tanks. Rich from first jig sold, that from 2nd and 
 3rd. jig is rejigged. 
 
 The three jigs have respectively : 
 
 1st strokes j inch holes per inch 5 | ^ ^^ 
 
 "p " * " " " " ( per minute. 
 3 rd . i , S) 
 
 Two boys and one man attend to the jigs. Slimes passing 18 
 holes to the inch are treated on 6 buddies each 20 feet diameter. Two 
 treat the products direct from jigs, and 4 treat the products from the 
 two. Contents of the first two are divided into 3 parts. Heads go to 
 third buddle, middle to fourth, tail and over flow to pits. The contents 
 of the 3rd buddle are divided into three. Heads sold. Middle 
 rebuddled. tail to forth, overflow lo pit. Contents of the 4th buddle 
 divided into 3 parts. Heads go to third, middle rebuddled, tails to 
 pit. Settled slimes are treated in 5th and 6th buddies. 
 
 Quality of ores 
 
 Best work 17 per cent 
 Second Class 7 to 8 per cent 
 Buddie 5 per cent. 
 
 Engine for crusher 28 H.P. 
 
 Engine for 12 Jigs, 6 buddies, 10 H.P. 
 
 Consumption of coal 290 to 300 tons per month. 
 
 30. Great Devon Consols (AV. Tavistock} Copper ore. 
 The ore is sized in revolving trommels. The slimes are washed 
 in stationary concave buddle, in which the arms with brushes 
 revolve by the reaction of the water supplied to the buddle. 
 The heads are roasted for arsenic, the middles are rich and the 
 tails are rebuddled. 
 
2 9 2 
 
 31. <oneral n-m-s on C'omisli Tin .Hiii*-*. \Vhere 
 wolfram occurs with, tin it is separated by picking, or the reduced 
 and dressed ore is roasted with salt or carbonate of soda and the 
 resulting tungstate of soda subsequently washed out. At East 
 Pool Mine the ore is sold with the wolfram. If tin is disseminat- 
 ed it is crushed fine with stamps in high mortars and no grates,, 
 as at Wheal Kitty. This flush system avoids restamping. At 
 Dolcoath and in Camborne generally, the ores are restamped 
 At Tin Crown, convex buddies are used for ordinary work and 
 concave for fine slimes from the frames. In finishing operations 
 many frames are employed. 
 
 32. Sado, Japan. Ore is finely disseminated silver and 
 gold with sulphurets in quartz. The process was : 
 
 Spall ing screen (2^ grate) 
 
 Hand trommels (i" X " meshes) 
 
 picking 
 
 I 
 
 picking 
 
 I 
 
 I. 2. 3. rubbish 
 I II 
 
 III 1 
 
 I. 2. 3. rubbish 
 
 I I I 
 
 fine sand ore 
 
 Stamps (wet) 
 
 Stamps (wet) 
 Pointed boxes 
 
 
 A 
 
 End percus. T. 
 
 - 1 
 
 Retorting 
 
 1 
 1 
 
 Labyrinth 
 1 
 
 
 
 ar * 
 i 
 
293 
 
 33- Ikuno Japan. Ore is quartz with argentite, copper and 
 iron pyrites, blende, galena &c. 
 
 Trommel , 
 1 
 
 ie 5th < 
 
 Wetst 
 
 . 
 Percussic 
 
 :lass 
 amps 
 >n table 
 
 Picking 
 
 III! 
 
 I. 2. 3. 4, fir 
 
 1 1 "1 1 
 
 1 
 
 
 
 I I 
 Chloridizing roasting 
 
 Grinding- 
 
 -Sifting 
 
 Amalgamation barrels 
 Retorting. 
 
 34. K osaka, Japan. Ore, a yellow clay ore with from 4 to 
 40 oz of silver per ton and a black sulphuret with blende, copper &c. 
 with about 12 oz of silver per ton. 
 
 Crushing (by hand) 
 Grinding (by rolls and mills) 
 
 Chloridizing, roasting. 
 
 Lixivation by brine 
 
 Precipitation of silver by copper. 
 ! 
 
 Refining. Precipitation of copper by iron. 
 

A LIST OF WORKS ON MINING. 
 
 Abel Accidents in mines. 
 
 Agricolse (Q.) De re Metallica. 
 
 Andre A Descriptive Treatise on Mining Machinery. (2 vols.) 
 
 Andre A Practical Treatise on Coal Mining. (2 vols.) 
 
 Andre A Practical Treatise on Rock Blasting. 
 
 Andree (R.1 Die Metalle bei den Naturvolkern. 
 
 Atkinson (J. J.) Practical Treatise on the Gases met with in Coal 
 
 Mines. 
 
 Bagot (A.) Accidents in Mines. 
 Bainbridge Law of Mines and Minerals. 
 Beer (A. H ) Erdbohrkunde. 
 Berg-und Huttenmannische Zeilung. 
 Berg-und Huttenmannisches Jahrbuch d. K. K. Bergakademien zu 
 
 Leoben und Pribram. 
 Blake Mining Machinery. 
 
 Blake U.S. Report on the Precious Metals ; Paris Exhibition. 1867. 
 Bowie (A. J.) A Practical Treatise on Hydraulic Mining in California. 
 Braun (E.) Die Ketten-Forderung. 
 Brough Mine surveying. 
 
 Brown Bainbridge's Law of Mines and Minerals, 4th edition. 
 Browne Mineral Resources of the Pacific States. 
 Budge The Practical Miner's Guide. 
 Burat Course d'Exploitation des Mines. (2 vols.) 
 Burat Traite du Gisement et de la Recherche des Mineraux Utiles. 
 Burgoyne Quarrying and Blasting. 
 Caillaux (N.) Mines Metalliques et des Combustibles Mineraux de 
 
 la France. 
 
 Gallon (M. J.) Cours D'exploitation des Mines. 
 Gallon (M. J.) Lectures on Mining, translated by Foster and Galloway. 
 Gallon (M. J.) Preparation Mecanique. 
 Collins First Book of Mining and Quarrying. 
 Collins Principles of Coal Mining. 
 Collins Principles of Metal Mining. 
 Colyer Pumps and pumping machinery. 
 
2 9 6 
 
 Combes (C.) Handbuch der Bergbaukunst. 
 
 Creswick, (W.) Galloway, (W.) and Hopton (W.) -Essays on the 
 
 Prevention of Explosions and Accidents in Coal Mines. 
 Crew Practical treatise on petroleum. 
 Cundill Dictionary of explosives. 
 Daddow Coal, Iron, and Oil. 
 Das Sicherheits Lampen-wesen Beim Steinkohlen-Bergbau (Bericht 
 
 der Preussischen Schlagwetter Commission.) (2 vols.) 
 Davies (D. C.) Treatise on Earthy and other Minerals and Mining. 
 Davies (D. C.) Metalliferous Minerals and Mining. 
 Davies Treatise on Slate and Slate Quarrying. 
 Degosee et Laurent Guide du Sondeur. (2 vols.) 
 Delius (T.) Anleitung zu der Bergbaukunst; I8o6. 
 Demanet (C.) Der Betrieb der Steinkohlenbergwerke 
 Der Silber-und Blei-bergbau zu Pribram. 
 Die Mechanische Aufbereitung der Silberhaltigen Bleierze. 
 Drinker (H. S.) Tunneling, Explosive Compounds, and Rock Drills. 
 Egleston Hydraulic Mining in California. 
 Egleston Carifornian stamp mills. 
 Eissler (M.) The Modern High Explosives. 
 Emma Mine Investigation, 1st Session, 44th Congress. 1875-76. 
 Fairley (W.) Colliery Manager's Calculator. 
 Fairley (W.) Colliery Mannager's Catechism. 
 Fauck (A.) F"ortschritte in der Erdbohrtechnik. 
 Frommann (C. W.) Die Bohr-methode der Chinesen oder das Siel- 
 
 bohren. 
 
 Gaetzschmann (M. F.) Die Aufbereitung. 
 Gaetzschmann (M. F.) Die Lehre von den Bergmannischen Gewin- 
 
 nungsarbeiten. 
 
 Gaetzschmann (M. F.) Anleitung zur Grubenmauerung. (2 vols.) 
 Gaetzschmann (M. F.) Die Aufsuchung und Untersuchung von Lager- 
 
 statten niitzbarer Mineralien. 
 
 Gesner Practical Treatise on Coal, Petroleum, &c. 
 Glepin Sur le Nouveau Mode d'Extraction et de Triage de la 
 
 Houille. Annales des Travaux Publics de Belgique 
 Good year Coal Mines of the western coast of the U.S.A- 
 Green, Miall, Thorpe, Rucker, and Marshall Coal, Its History and 
 
 Uses. 
 
 Guttmann Blasting. 
 Greenwell Mine Engineering. 
 
297 
 
 Haton Grundriss der Aufbereitungskunde. 
 
 Hatton Colliery Manager's Handbook. 
 
 Haupt Die Stollenanlagen. 
 
 Hayer Die Ursprung der Grubenwasser. 
 
 Kenwood Metalliferous Deposits and Subterranean Temperature. 
 
 Hoefer (H.) Beitrage zur Spreng-oder Minen Theorie. 
 
 Hoppe (O.) Die Bergwerke, Aufbereitungs-Anstalten and Hiitten. 
 
 Hoppe Stammbau der neuen Aufbereitungsanstalt bei Clausthal. 
 
 Hughes (H. \V.) A Text-Book of coal mining. 
 
 Hull Coal fields of Great Britain. 
 
 Hunt (R.) British Mining : A Treatise on the Metalliferous mines 
 
 of the United Kingdom. 
 Hyslop Colliery Management. 
 Ihlseng A Manual of Mining. 
 Industrie Minerale Beige; Expositon Universelle de Paris; 1878, 
 
 Catalogue Specielle. 
 Jahrbuch fur das Berg-und Hiittenwesen im Konigreich Sachsen auf 
 
 das Jahr 1886-87. (2 vols.) 
 Japing (E.) Draht und Drahhvaaren. 
 Jevons Coal Questions. 
 Karsten und Dachen Archiv fur Mineralogie, Geognosie, Bergbau, 
 
 und Hiittenkunde. 
 
 Kind (E. G.) Anleitung zum Abteufen der Bohrlocher. 
 King Atlas of Mining Industry. 
 
 Klostermann (R.) Lehrbuch des Preussischen Bergrechtes. 
 Kohler (G.) Die Storungen der Gange, Fl5tze, und Lager. (Pamphlet.) 
 Kohler Lehrbuch der Bergbaukunde. 
 Krom Mechanical Engineer, and Manufacturer of Machinery for 
 
 Systematic Crushing, Screening and Concentration of Ores. 
 Kunhardt (W. B.) Practice of Ore Dressing in Europe. 
 Kustel (G.) A Treatise on Concentration of all kinds of Ores. 
 Lamprecht Kohlen Aufbereitung. 
 Leo (_M.) Lehrbuch der Bergbaukunde. 
 Linkenbach (C.) Die Aufbereitung der Erze. 
 Lintern The Mineral Surveyor's Guide. 
 Lintern (W.) The Mineral Surveyor's Guide. 
 Lock The Miner's Pocket Book. 
 Lock Mining and Ore Dressing Machinery. 
 Lottner (H.) Leitfaden zur Bergbaukunde. (2 vols.) 
 Macfarlane The Coal Regions of America. 
 
Merivale Notes and formulae for mining students. 
 
 Michell (S.) Mine Drainage. 
 
 Milne Notes on the Ventilation of Mines. 
 
 Mineral Statistics of Victoria. 
 
 Mining Journal. 
 
 Molesworth Pocket Book of Engineering Formulce. 
 
 Morgans Mining Tools. 
 
 Murgue Ueber Grubenventilatoren &c. 
 
 Netto On Mining and Mines in Japan (Memoirs of the Science De- 
 partment, Toyko Daigaku, Japan.) 
 
 Nitzsch (F.) Ueber Fangvorrichtungen an Bergwerksforderungen. 
 
 Oppel Bericht vom Bergbau ; 1869. 
 
 Pamley (C.) The Colliery Managers Handbook. 
 
 Percy Mechanical Engineering of Collieries. 
 
 Pernolet (M. M. A.) et Aguillon (1..) Exploitation et Reglementation 
 des Mines a Grisou en Belgique, en Angleterre et en Allemagne. 
 (2 vols.) 
 
 Phillips (J. S,) The Explorers' and Assayers' Companion. 
 
 Phillips Metallurgy and Mining of Gold and Silver. (2 cops.) 
 
 Phillips Gold Mining and Assaying. 
 
 Phillips The Explorer's, Miner's, and Metallurgist's Companion. 
 
 Phillips (J. A.) Ore Deposits. 
 
 Phillips and Darlington Records of Mining and Metallurgy. 
 
 Poetsch (F. H.) Das Gefrierverfahren. 
 
 Ponson Exploitation der mines de Houille. 
 
 Raymond (R. W.) Mineral Resources of the Rocky Mountains (Sta- 
 tistics of.) 1869-76. 
 
 Reports of the Mining Surveyors and Registrars. 
 
 Riedler Gesteins-bohrmaschinen. 
 
 Riedler Unterirdische Wasserhaltungs machinen mit gesteuerten Ven- 
 tilen. 
 
 Rogers The Law of Mines, Minerals, and Quarries, 1884-76. (2 
 vols.) 
 
 Ronne (L.) Das Allgemeine Berggessetz fur die Preussichen Staaten. 
 
 Sawyer Accidents in mines, their causes and the means of diminishing 
 their frequency. 
 
 Schmidt Theorie der Verscheibungen Aelterer Gange. 
 
 Serlo (A.) Leitfaden zur Bergbaukunde. (2 vols.) 
 
 Seume (T.) Das Allgemeine Kgl. S. Berggesetz. 
 
 Sickel (C. A.) Die Grubenzimmerung. 
 
299 
 
 Silversmith Handbook for Miners, Metallurgists, and Assayers, &C. 
 
 Simonin Underground Life ; or Mines and Miners. 
 
 Smith Cable traction as applied to the working of street and other 
 
 railways. 
 
 Smyth Coal and Coal Mining. 
 
 Smyth The Goldfields and Mineral Districts of Victoria. 
 Smyth Lectures on Mining. 
 Spaare Zur theorie der Separation der Krit. 
 Spon Dictionary of Engineering. 
 
 Spon The Present Practice of Sinking and Boring Wells. 
 Strippelmann (L.) Die Tiefbohrtechnik im Dienste des Bergbaus und 
 
 der Eisenbahntechnik. 
 
 Swindell Well-Digging, Boring, and Pump-work, 
 Tables showing the Production and Expenditure of Japanese Mines. 
 Tarbuck ( J.) Mine Rent : Ready Reckoner or Tables. 
 Techlenburg (T.) Handbuch der Tiefbohrkunde. 
 Thomas (J. W.) A Treatise on Coal Mine-gases, and Ventilation. 
 The Engineering and Mining Journal. 
 The Journal of the Iron and Steel Institute. 
 Transactions of the American Institute of Mining Engineers. 
 Transactions of the North of England Institute of Mining Engineers. 
 Von Cotta Treatise on Ore Deposits. 
 Wardle Reference Book of practical and scientific information for the 
 
 use of colliery managers. 
 
 Whitney (J. D.) Metallic Wealth of the United States. 
 Wilson (J.) Ready Reckoner for Tubs and Scores. 
 Zimmermann (C.) Die Wiederausuchtung Verworfener Gange, Lager, 
 
 und Flotze. 
 
INDEX. 
 
 PAGE 
 
 Abel's powder 61 
 
 Accidents in mines 205 
 
 Accidents in shafts 146 
 
 Adit levels 112 
 
 ^Erophores 162 
 
 ^Etna powder 61 
 
 Afterdamp 165 
 
 Air, admission to mine 210 
 
 Air, composition of 164 
 
 Air compressors 78 
 
 Air conduits 81 
 
 Air crossings 214 
 
 Air friction of 181 
 
 Air head of 176 
 
 Airhead 183 
 
 Air in pipe 214 
 
 Air, obstructions to flow 180 
 
 Air, pressure of 177 
 
 Air, quantity required 210 
 
 Air receivers 81 
 
 Air sollars 183 
 
 Air splitting 212 
 
 Air velocity of 177,209 
 
 Air, vitiating mines 163 
 
 Alberti's tube drawer 41 
 
 Alluvial deposits 29 
 
 Amalgam, treatment of 272 
 
 Amide powder 62 
 
 Ammonia 169 
 
 Ammonia nitrate of 64 
 
 Ammonite 62 
 
 Anemometers 178 
 
 Aqueous vapour 169 
 
 Arastra .. .. 228 
 
 PAGE 
 
 Archwork 116, 117 
 
 Arsenic 169 
 
 Ashio, wire tram at 130 
 
 Atlas powder 6l 
 
 Audemars ventilator 201 
 
 Aufermann's jig 259 
 
 Augers 53 
 
 Backs 26, 83 
 
 Bad air, expulsion of 174 
 
 Baird's coal cutter 67 
 
 Balance bobs 151 
 
 Balancing, calculations on ... 141 
 
 Balancing loads 139 
 
 Balancing, methods of 140 
 
 Balancing rods in 
 
 Ball mill 228 
 
 Barometer at mines 171 
 
 Barrow drill 72 
 
 Barrels 118 
 
 Bartlett's drill 71 
 
 Barns' experiments 22 
 
 Batteries 219 
 
 Batteries, dry 220 
 
 Battery foundations 219 
 
 Bassets 18, 25 
 
 Beaumont's tunneling ma- 
 
 chine| 70 
 
 Becquerel's experiment 21 
 
 Beds 24 
 
 Bed, dip of 47, 48 
 
 Beds, formation of 25 
 
 Beds, thickness of 47 
 
 Belden pan 231 
 
3 oi 
 
 PAGE 
 
 Bellite 62 
 
 Belt, on nuggets 30 
 
 Benching 95 
 
 Bennett amalgamator 231 
 
 Berthier's experiments 21 
 
 Bidder and Jones wedge 69 
 
 Bits 40 
 
 Bits for borers 73 
 
 Blanket tables 262 
 
 Blanzy, compressors at 78 
 
 Blasting 54 
 
 Blasting tools 54 
 
 Blind coal 27 
 
 Bog iron, alluvial 31 
 
 Boilers 133, 134 
 
 Bolt holes 97 
 
 Bonanzas 8 
 
 Bore frames 41 
 
 Bore hole, contents of 64 
 
 Bore holes, depth of 37 
 
 Bore holes, diameter 39 
 
 Bore holes, examples of 37 
 
 Bore holes, precautionary ... 46 
 
 Bore holes, position of 62 
 
 Bore holes, survey of 49 
 
 Bore holes, water in 48 
 
 Bore towers 41 
 
 Borers, varieties of 53, 73 
 
 Boring 37 
 
 Boring, accidents 42 
 
 Boring, American 42 
 
 Boring, cost of 44, 45 
 
 Boring, cost of with rope 43 
 
 Boring, contract for 45 
 
 Boring, diamond 43 
 
 Boring, difficulties of 42 
 
 Boring, hydraulic 37 
 
 Boring, Japanese 42 
 
 Boring journal 44 
 
 PAGE 
 
 Boring, Mather and Platt ... 43 
 
 Boring, methods of 37 
 
 Boring, objects of 37 
 
 Boring, ordinary operation of 38 
 
 Boring, percussion 37 
 
 Boring, precautions taken ... 46 
 
 Boring, rate of 38, 43, 44 
 
 Boring rods 39 
 
 Boring rods, tortion of 47 
 
 Boring, rope 42 
 
 Boring, rotary 37 
 
 Boring, strokes per minute... 38 
 
 Boring tools 40 
 
 Boring tools, set of 41 
 
 Boring tools, cost of 46 
 
 Brains powder 60 
 
 Brakes 136 
 
 Branches 2 
 
 Brattices 212 
 
 Breaking ground 51 
 
 Breaking ground, cost of 98 
 
 Bridle chain 126, 137, 139 
 
 Brink and Huebner mill 229 
 
 Broil 18 
 
 Brunton's tunneling machine 70 
 
 Brunton's ventilator 200 
 
 Buddies, concave 164 
 
 Buddies, convex 264, 268 
 
 Buddies, hand 263 
 
 Buddies, impeller 263 
 
 Buddies, knife 263 
 
 Buddie, Rittinger's 267 
 
 Buddies system 94 
 
 Buddies, rotary 267 
 
 Bulk of material 51 
 
 Bunches 8 
 
 Buntons 105 
 
 Burnett's roller wedge 70 
 
 Burton's hand drill 73 
 
303 
 
 PAGE 
 
 Cages 138 
 
 Cams 221 
 
 Canals 261 
 
 Canals, underground 129 
 
 Candles 159 
 
 Capell fan 200 
 
 Cap head 183 
 
 Capping 137 
 
 Carbonas 34 
 
 Carbonic anhydride. 164 
 
 Carbonic oxide 166 
 
 Carbonite 60 
 
 Carburetted hydrogen 166 
 
 Garret and Marshall's coal 
 
 cutter 66 
 
 Cartridges, lime 62 
 
 Catches 151 
 
 Catch pieces in 
 
 Cave's drill 70 
 
 Centrifugal force 251 
 
 Centrifugal mills 228 
 
 Centrifugal ventilators 193 
 
 Cement, gold in 31 
 
 Chains 138 
 
 Chambers, ventilation of 211 
 
 Channels 25 
 
 Chilli Mill 228 
 
 Chimneys 8 
 
 Chisels 40 
 
 Choke damp 165 
 
 Churns 35 
 
 Clearance with compressor. 80 
 
 Cleat 26 
 
 Clips, Hanson's 126 
 
 Clips, Humble's 126 
 
 Coal, age of 27 
 
 Coal analysis 27 
 
 Coal beds 25 
 
 Coal cleaning 259 
 
 PAGE 
 
 Coal cutters 65 
 
 Coal cutters, general remarks 
 
 on 68 
 
 Coal, formation of 28 
 
 Coal, getting 94 
 
 Coal, impurities of 26 
 
 Coal mines, fire in 99 
 
 Coal, thickness of 26 
 
 Coal, waste of 99 
 
 Coal wedging machine 69 
 
 Cobbing 234 
 
 Colladon's air compressor... 78 
 
 Collom's jig 258 
 
 Combes' ventilator zoi 
 
 Combination pan 231 
 
 Compressors, dimensions of. 82 
 Compressor, loss of work... 79, 80 
 
 Concentration 233 
 
 Concentration, coarse materi- 
 al 255 
 
 Concentration, degree of 216 
 
 Concentration, loss in 216 
 
 Concentration, fine material. 289 
 Concentration, theory of. 240, 241 
 
 Concentrator, Dodge 266 
 
 Concentrator, Duncan 271 
 
 Concentrator, Embrey... 267, 270 
 
 Concentrator, Golden Gate... 270 
 
 Concentrator, Halley 266 
 
 Concentrator, Hendy 271 
 
 Concentrator, Triumph 270 
 
 Conduits for air 81 
 
 Contact deposits 33 
 
 Contents of lodes 6 
 
 Cook's ventilator 203 
 
 Copper ore, beds of 28 
 
 Cornish drill 72 
 
 Cornish mines 292 
 
 Cornish pumps 150 
 
PAGE 
 
 Corves 118 
 
 Costeaning 104 
 
 Counterbalance 157 
 
 Country rocks 10 
 
 f Q 
 
 Courses o 
 
 Cowls 183 
 
 Cox's wedge 70 
 
 Cost of breaking ground 98 
 
 Cost of levels 99 
 
 Cost of shafts 99 
 
 Cradles 236 
 
 Cranston drill 7 2 
 
 Creep 94 
 
 Cribs 105 
 
 Cross courses I, 17 
 
 Cross cuts 104 
 
 Crossings 123 
 
 Ctows foot 41 
 
 Crushers, comparison of 230 
 
 Cundhill, on explosives 57 
 
 Current, pressure for 209 
 
 Curves 122 
 
 Current, carrying power of... 240 
 
 Cutters 26, 83 
 
 Cylinder mills 228 
 
 Damp rot 114 
 
 Dams 86, 148 
 
 Darlington drill , 72 
 
 Davy's lamp 159 
 
 Day frame 105 
 
 Dead work 101 
 
 Defiance mills 288 
 
 Degousee's free falling cutter 40 
 
 Delf 25 
 
 Deposits, irregular 31 
 
 Deposits irregular, examples 
 
 of 33 
 
 Deposits in igneous rocks ... 34 
 
 PAGE 
 
 Deposits in limestone 35 
 
 Deposits in metamorphic 
 
 rocks 35 
 
 Deposits in nonstratified 
 
 rocks 34 
 
 Depth of lodes 5 
 
 Designolles' powder 61 
 
 Detonation 56 
 
 Detonators 55 
 
 Diamond boring 43 
 
 Dingey pulverizer 229 
 
 Dip, apparent 48 
 
 Dip, from bore holes 48 
 
 Dip of bed 47 
 
 Dip of lodes 5 
 
 Direction of lodes and con- 
 tents 8 
 
 Dolly tub 271 
 
 Doors 212 
 
 Doors, main 213 
 
 Doors, man 213 
 
 Doors, safety 214 
 
 Doors, self acting 213 
 
 Doors, trap 213 
 
 Dressing, theory of 241 
 
 Drills 53 
 
 Drills, speed of 74 
 
 Drills, supports for 74 
 
 Driving in soft ground 115 
 
 Dry jigs 258 
 
 Dry rot 114 
 
 Drum curb 106 
 
 Drum, winding 135 
 
 Dru's free fall apparatus 40 
 
 Dualine 6 1 
 
 Dubois-francois drill 71 
 
 Duck pump 190 
 
 Dumb drift 185 
 
 Durocher's experiments 23 
 
305 
 
 PAGE 
 
 Dust in mines 169 
 
 Dutch cribbing 106 
 
 Dynamite 59 
 
 Dynamite, testing 60 
 
 Earth pulsations 172 
 
 Earthquakes 172 
 
 Earth tremors 172 
 
 Ebelmen's experiments 21 
 
 Eckhardt's ventilator 196 
 
 Eclipse drill 72 
 
 Economic coal cutter 67 
 
 Edge mill 228 
 
 Electric amalgamation 231 
 
 Electric coal cutters 69 
 
 Electric drills 73 
 
 Electric haulage 129 
 
 Elephant stamps 224 
 
 Endless chain 125 
 
 Endless rope 125 
 
 End pieces 104 
 
 Engines, dimensions of 132 
 
 Engines, duty of 131 
 
 Engines, hydraulic 156 
 
 Engines, pumping 155 
 
 Engines, winding 131 
 
 Equal falling particles 239 
 
 Equivalent orifice 179 
 
 Explosions, avoidance of 173 
 
 Explosions in coal mines ... 168 
 
 Explosion, temperature of ... 64 
 
 Explosives 57 
 
 Explosives, firing of 55 
 
 Explosives, selection of 63 
 
 Explosives, strength of 57 
 
 Errard's ventilator 203 
 
 Excelsior drill 72 
 
 Exelsior pan 231 
 
 Extincteurs . ,. 100 
 
 PACE 
 
 Fabry's ventilator 202 
 
 Faces 26 
 
 Fahlbands 12 
 
 Fahrkunst no 
 
 Fans 193 
 
 Fan, duty of 199 
 
 Fan, pressure of 194 
 
 Fan, shape of vanes 196 
 
 Faults 13 
 
 Faults, age of 17 
 
 Faults, throw of 4 
 
 I Feeders 148 
 
 ! Feeders, automatic 223 
 
 ! Feeders, rotating 263 
 
 ' Feeders, stationary 262 
 
 Fire damp 165, 167, 170 
 
 Fire damp detectors. 170,171,172 
 
 Fire in coal mines 99 
 
 Fire setting 166 
 
 Fires, prevention of 100 
 
 Fires, extinguishing 100 
 
 Firth's coal cutter 65 
 
 Flames over lodes 19 
 
 Flat veins 35 
 
 | Fleuss lamp 162 
 
 ! Flood rock 56 
 
 i Flucan 17 
 
 i Flumes 86 
 
 | Forbe's detecVor 171 
 
 i Fowler clip pulley 123 
 
 j Fox's experiments 21 
 
 Fox, on growth of lodes 3 
 
 Free falling cutters 40 
 
 Fuel, for engines 156 
 
 Fuel, for pit furnaces 190 
 
 Fuel, for ventilation 187 
 
 Fulmatin 60 
 
 Furnace paradox 187 
 
 Furnace, efficiency of 208 
 
306 
 
 PAGE 
 
 Furnaces for ventilation 184 
 
 Furnaces, underground 185 
 
 Furnace ventilation 205 
 
 Furnaces, work by 1 86 
 
 Fuses 54 
 
 Fuses, electrical 55 
 
 Gabbro rosa 34 
 
 Grens powder 62 
 
 Gas, avoidance of 173 
 
 Gases, detection of 119 
 
 Gelatine 60 
 
 Gelignite 60 
 
 Getting coal 97 
 
 Giant Powder 6l 
 
 Gillot and Copley's coal cutter 67 
 
 Girdles 25 
 
 Goaf 95 
 
 Gob 95 
 
 Gold mills 276 
 
 Gossan 18 
 
 Grafton Jones wedge 70 
 
 Great Devon Consols 291 
 
 Greisen 34 
 
 Grinding 228 
 
 Ground, varieties of 51 
 
 Guibal's fan 198 
 
 Guibal's method of sinking... 107 
 Guibal's hydropneumatic ven- 
 tilator 201 
 
 Guides 138 
 
 Guide tubes 41 
 
 Gun cotton 61 
 
 Gunpowder 57 
 
 Gunpowder, force of 64 
 
 Gutter 31 
 
 Hacks 52 
 
 Hade 25 
 
 PAGE 
 
 Hade, of lodes 5 
 
 Hallidies' wire tram 129 
 
 Haloxyline 58 
 
 Hammers 52 
 
 Handles 53 
 
 Hand power drills 73 
 
 Hard bars 30 
 
 Harze ventilator 201 
 
 Haulage 118 
 
 Haulage, cost of .< 128 
 
 Haulage, electrical 129 
 
 Haulage, steam 125 
 
 Hausse's rule 96 
 
 Head gear 134 
 
 Head of air 176 
 
 Heads 221 
 
 Heberle mill 229 
 
 Heaves 13 
 
 Hell Gate 56 
 
 Helves 53 
 
 Hepburn and Peterson fan ... 231 
 
 Hercules powder 61 
 
 Hinkle & Capp amalgamator. 231 
 
 Hoisting, endless chain 147 
 
 Hoisting man engine 143 
 
 Hoisting pneumatic 143 
 
 Holing 95 
 
 Horse power at shafts 131 
 
 Horse power, effective 131 
 
 Horse power, indicated 133 
 
 Horse power, nominal 133 
 
 Horse whim 145 
 
 Horse, working of 90 
 
 Howland's battery 220 
 
 Hund 118 
 
 Huntingdons' mill 224 
 
 Hurdy gurdy 145 
 
 Hutch work 255 
 
 Hydraulic mining 86 
 
PAGE 
 
 Ikuno, process at 293 
 
 Impregnations I, 32 
 
 Inclined seams 96 
 
 Inclines, self acting 123 
 
 Indicators 147 
 
 Inertia, in winding 132 
 
 Ingersoll drill 71 
 
 Ingersoll's hand drill 73 
 
 Iron man 65 
 
 Iron ore, beds of 28 
 
 Ironstone beds 25 
 
 Iron tubbing 107 
 
 Irregular deposits, working of 90 
 
 Jacobs ladders 272 
 
 Jigging 255 
 
 Jiggers, continual 257 
 
 iggers, movable 257 
 
 iggers, stationary 257 
 
 igging, theory of 241, 253 
 
 igs, formulce for 256 
 
 ordan's hand drill 73 
 
 Jordan's pulverizer 229 
 
 Tudson's powder 6 1 
 
 Kaiser's jig 258 
 
 Keeps 138 
 
 Kendall's quartz mill 225 
 
 Kibbles 118 
 
 Kieve 257 
 
 Kind and Chaudron's method. 107 
 
 Kind's catch clutch 40 
 
 Kind's free falling cutter 40 
 
 Kind's plug 41 
 
 Kirving 95 
 
 Kitto and Paul's jig 258 
 
 Knox pan 231 
 
 Kosaka, process at 293 
 
 Kiips powder 58 
 
 PAGE 
 
 Labyrinths 261 
 
 Ladders 109 
 
 Ladders, work on HO 
 
 Lagging 115 
 
 La Motte ventilator 201 
 
 Lamps 159 
 
 Lamp detectors 172 
 
 Lamps, electric 161 
 
 Langley Barony Lead Mine. 290 
 
 Launders 261 
 
 Lauterrinne 235 
 
 Laws of falling particles 241 
 
 Layers 24 
 
 Lead 31 
 
 Lead ore, beds of 29 
 
 Le Conte, on coal formation. 25 
 
 Legg mining machine 67 
 
 Lemielle's ventilator 202 
 
 Leschot drill 75 
 
 Lesonine ventilator 201 
 
 Letoret's ventilator 198 
 
 Levant Mine 290 
 
 Levels 112 
 
 Levels, cost of 112 
 
 Levels, dimensions of 1 12 
 
 Levels, position of 114 
 
 Levels, timbering of 114 
 
 Levels, varieties of 112 
 
 Levels, ventilation of 211 
 
 Lift of pumps 153 
 
 Lighting 159 
 
 Lime cartridges 62 
 
 Line of least resistance 63 
 
 Lisbets drill 75 
 
 Lithofracteur 61 
 
 Locomotives, underground ... 129 
 
 Lodes, age of 17 
 
 Lodes, back of 18 
 
 Lode, champion 2 
 
303 
 
 PAGE 
 
 Lodes, counter 2 
 
 Lodes', electric phenomena of. 21 
 
 Lodes, formation of 2 
 
 Lodes, in dykes 21 
 
 L'-des, intersections of 10 
 
 Lodes, length of 3 
 
 Lodes, narrow 89 
 
 Lodes, ordinary width 88 
 
 Lodes, relation to each other. 9 
 
 Lodes, right running 2 
 
 Lodes, wide 89 
 
 Lodes, working of 88 
 
 Long block system 94 
 
 Long wall working 95 
 
 Macdermott and Williams 
 
 drill 75 
 
 Machine ventilation 206 
 
 Magnetite, alluvial 31 
 
 Mahaux ventilator 192 
 
 Main rope 125 
 
 Mallenear Mine 290 
 
 Mandrels 5 2 
 
 Man Engine no 
 
 Manganese, alluvial 31 
 
 Marhaye's ventilator 191 
 
 Marsh gas 166 
 
 Materials from concentration. 233 
 
 Materials in lodes 7 
 
 Mather and Platt, boring 43 
 
 Mattocks 52 
 
 Maurice's detector 172 
 
 Maus drill 70 
 
 McLean's crusher 225 
 
 Measures 25 
 
 Melinite 6 1 
 
 Men and horses 145 
 
 Men at mines 101 
 
 Men of war 97 
 
 PAGE 
 
 Mercury 169 
 
 Metals, separation of 217 
 
 Methane 166 
 
 Michalowski's powder 61 
 
 Mills, comparison of 230 
 
 Mills, dry 275 
 
 Mills, examples of 274 
 
 Mills, wet 274 
 
 Mineral deposits I 
 
 Minera Lead Mine 289 
 
 Minerals, separation of 217 
 
 Mine accidents 205 
 
 Mines 25 
 
 Mining machinery 282 
 
 Mining tools 5 1 
 
 Monofiths 85 
 
 Mortars 220 
 
 Motors, water 144 
 
 Mount Bischoff 288 
 
 Nasmyth's ventilator 197 
 
 Natural ventilation 204 
 
 Nests 8 
 
 Neumeyer's powder 58 
 
 Nitrate of ammonia 64 
 
 Nitro-glycerine 59 
 
 Nixon's ventilator 193 
 
 Nobel's powder 62 
 
 Oeynhausen's sliding joint ... 40 
 
 Officers at mines 101 
 
 Oil 159 
 
 Open works 83 
 
 Open works, example of 85 
 
 Ore against ore 9 
 
 Ore dressing 216 
 
 Ores, separation of 217 
 
 Ore, treatment of 286 
 
 Osmoscopes 170 
 
309 
 
 PAGE 
 
 Overburden 83 
 
 Overwinding 147 
 
 Pan amalgamators 230 
 
 Pannel system 94 
 
 Pans 230 
 
 Partings 26 
 
 Particles for concentration ... 239 
 
 Particles, equal falling 239 
 
 Particles equal, sizes ..., 239 
 
 Particles, falling, in water ... 241 
 
 Pasquet's yentilator 202 
 
 Pelton wheels 145 
 
 Pengelly on coal formation... 21 
 
 Penrhyn Slate Quarries 84 
 
 Picks, varieties of 5 2 
 
 Picric acid, compounds 6l 
 
 Pikes 52 
 
 Pillars, dimension of 93 
 
 Pipes 86, 154 
 
 Pipes, friction in 154 
 
 Pipe veins 35 
 
 Piston ventilators 192 
 
 Pitch 25 
 
 Placer mining 86 
 
 Planes self acting 123 
 
 Plant, examples of 274 
 
 Plant growth on lodes 19 
 
 Pneumatic hoisting 143 
 
 Pneumatic stamps 224 
 
 Pockets Ao=ll 
 
 Poetsche's method 107 
 
 Pointed boxes 259 
 
 Points 123 
 
 Poppet heads 134 
 
 Post and stall working 92 
 
 Port Phillip Co 288 
 
 Potholes 30 
 
 Poudre vieille , 62 
 
 PAGE 
 
 Pressure of air 177 
 
 Processes, examples of 286 
 
 Props 114 
 
 Pulleys 135 
 
 Pulsometers 15? 
 
 Pulverizers 228 
 
 Pulverizer, pneumatic 230 
 
 Pumping 148 
 
 Pumping engines 155 
 
 Pumps, classification of 155 
 
 Pumps, comparison of 158 
 
 Pumps, cornish 15 
 
 Pumps, diameter of 157 
 
 Pumps, duty of 156 
 
 Pump rods 15 
 
 Pump rods, weight of J5 1 
 
 Pumps, suction.... 15 
 
 Punch props 105 
 
 Quarries 83 
 
 Ragging 234 
 
 Raff wheel 226, 272 
 
 Rails 122 
 
 Receivers for air 8l 
 
 Reduction 218 
 
 Reichenbach's ventilator 197 
 
 Resistane, line of least 63 
 
 Rew and Jone's concentrator 233 
 
 Ribs 2 
 
 Riddles 235 
 
 Rittinger's, formulae 241 
 
 Rittingers jigger 257 
 
 Rittinger's ventilator 197 
 
 Roads 122 
 
 Robbing pillars 94 
 
 Roburite 62 
 
 Rock breakers 218 
 
 Rock crushers 219 
 
3 io 
 
 PAGE 
 
 Rock drills 70 
 
 Rock drills, economy of 75 
 
 Rock drills, dimensions of ... 75 
 
 Rock drills, rotary 76 
 
 Rock drills, water for 77 
 
 Rocking lever 41 
 
 Rolls 225 
 
 Rolls, dimensions of 227 
 
 Roman Gravel lead Mine ... 289 
 
 Ronchamp, compressors at ... 79 
 
 Root's blower 203 
 
 Ropes 136 
 
 Ropes, dimensions of 136 
 
 Ropes, strength of 137 
 
 Ropes, to find meetings 139 
 
 Rotating cylinder, Hundt's... 270 
 
 Runs 261 
 
 Royal drill 72 
 
 Saddles, nuckle.... 25 
 
 Saddles, trough 25 
 
 Sado, mine at 292 
 
 Safety catches 147 
 
 Safety grip 147 
 
 Safety hooks 147 
 
 Safety lamps 159 
 
 Salt beds 29 
 
 Sampson coal getter 70 
 
 Sandberger's observations ... 23 
 
 Sand, weight of 293 
 
 Sandycroft drill 72 
 
 Sarrebruck, compressors at... 79 
 
 Schiele fan 200 
 
 Schmidt's rule 14 
 
 Schram and Oliver's, coal 
 
 cutter 64 
 
 Schranz mill 229 
 
 Schultze's powder 58 
 
 Screens .. .. 220 
 
 PAGE 
 
 Screw bells 41 
 
 Screw ventilators 201 
 
 Serins 2, 35 
 
 Seams in a district 27 
 
 Secretion, lateral 23 
 
 Securite .. 62 
 
 Segregations I, 31 
 
 Seizers 123 
 
 Selvage 2 
 
 Senarmont's experiments ... 23 
 
 Separation 234 
 
 Separation by dense fluid .., 271 
 
 Separation, magnetic 272 
 
 Separators, magnetic 272 
 
 Separirtrichter, Rittinger's ... 270 
 
 Settlers 231 
 
 Setzherd 257 
 
 Shafts 53, 103 
 
 Shaft accidents 146 
 
 Shaft fittings 109 
 
 Shafts, form of 104 
 
 Shaft furnaces 185 
 
 Shaft, horse power at 131 
 
 Shafts, site of 103 
 
 Shaft, size of 104 
 
 Shaft timbering 104 
 
 Shaft timbering, cost of Io5 
 
 Shafts, varieties of Io3 
 
 Shells' pneumatic stamps ... 225 
 
 Shells' recoil stamps 224 
 
 Shoots 8 
 
 Shovels ft 
 
 Sieves 235, 236 
 
 Sieves, dimensions of 238 
 
 Sills 25 
 
 Sinking, cost of 108 
 
 Sinking in soft ground 106 
 
 Siphons 150 
 
 S. Ives Consols 290 
 
PAGE 
 
 Sizing ore 234, 235 
 
 Skip road 146 
 
 Slates, geological age of 85 
 
 Slates, irregularities of 85 
 
 Slate quarries 83, 84 
 
 Sledges 5 2 
 
 Sledges, varieties of 53 
 
 Slickensides 13 
 
 Sliding joints 40 
 
 Slides 13, 138 
 
 Slime pits 261 
 
 Slime, weight of 273 
 
 Slip with compressors 80 
 
 Slitters 52 
 
 Sleds 118 
 
 Slope of equilibrium 122 
 
 Slope of equal resistance 121 
 
 Sludgers 4 
 
 Sluices 235 
 
 Slynes 26 
 
 Soft ground, driving in 115 
 
 Soft ground, sinking in 106 
 
 Sollars no 
 
 Sommetller's drill 71 
 
 Spades 5 1 
 
 Spalling 234 
 
 Special pump 156 
 
 Specification, example of ... 282 
 
 Spilling 106, 115 
 
 Spitzkasten 259 
 
 Spitzlutte 260 
 
 Squats 8 
 
 Staffordshire method 9? 
 
 Stamps 219 
 
 Stamps, lift of 222 
 
 Stamp mills, price of 225 
 
 Stamps, pneumatic 220 
 
 Stamps, weight of 
 
 Stamps, working effect.... 
 
 . 
 
 PAGE 
 
 Stamps, work of 223 
 
 Stanley's coal drifting ma- 
 chine 70 
 
 Steam haulage 125 
 
 Steam jets 184 
 
 .Steam ventilation 188 
 
 Steel mill 161 
 
 Stemming 54 
 
 Stemples 114 
 
 Stems 221 
 
 Sticks 53 
 
 Stockwerks 32 
 
 Sloping, overhand 88 
 
 Sloping, underhand 89 
 
 Stoppings 212 
 
 Stops 123 
 
 Strata 25 
 
 Stream tin 31 
 
 Strike of lodes 4 
 
 Strings /- *2 
 
 Strips 261 
 
 Stroke of pumps I5J 
 
 Stromsetz machine 270 
 
 Slruve's ventilator 191 
 
 Studdles 103 
 
 Stuff", weight o( 273 
 
 Sturgeon's air compressor ... 78 
 
 Sturtevant mill 229 
 
 Subsidence, effects of 96 
 
 Sulphur, beds of 29 
 
 Sulphurous anhydride 169 
 
 Sulphuretted hydrogen 1 68 
 
 Surface deposits 29 
 
 Survey of bore holes 49 
 
 Swan's detector 172 
 
 Swells 25 
 
 Tables 262 
 
 Bruntoirs 269 
 
 UNIVERSITY 
 
312 
 
 Tables, end blow 
 
 Tables, Linkenbach 
 
 Tables, percussion 
 
 Tables, sleeping 
 
 Tables, -sweeping 
 
 Tail rope system 
 
 Tamping 
 
 Tell tales 
 
 Thames tunnel 
 
 Thermometer at mines 
 
 Thick seams 
 
 Thirlings 
 
 Thrust 
 
 Tillers, force on 
 
 Timbering levels 113 
 
 Timbering, plank and box ... 
 
 Timbering, prop crib 
 
 Timbering shafts 
 
 Timbering, solid crib 
 
 Tipplers 
 
 Tonite 
 
 Tower's, ventilation 
 
 Traction, force of 
 
 Traction, resistance to 
 
 Tramways, wire 
 
 Transport, cost of 
 
 Trestle 
 
 Tributers 
 
 Triger's method 
 
 Trommels 
 
 Troughs 
 
 Tubbing 
 
 Tubbi n g iron 
 
 Tubing, bore holes 
 
 Tubs 
 
 Turbines 
 
 Turcjuau dectector 
 
 Tut work 
 
 PA (.;!; 
 265 
 265 
 265 
 263 
 263 
 125 
 54 
 147 
 "5 
 171 
 
 97 
 93 
 94 
 
 49 
 
 105 
 104 
 1 06 
 119 
 62 
 182 
 
 121 
 I 2O 
 129 
 129 
 
 4 l 
 101 
 106 
 236 
 261 
 149 
 107 
 
 4i 
 118 
 
 145 
 170 
 101 
 
 Underlie of lodes. 
 
 PAGE 
 
 5 
 
 Valves 151 
 
 Valves, classification of 152 
 
 Van lead mine 289 
 
 Vanner, Frue 267, 269 
 
 Vanner, Liihrig 266 
 
 Varney pan 231 
 
 Veins and beds, distinction 
 
 between 20 
 
 Veins, bedded 
 
 Veins, contact 
 
 Veins, cross 
 
 Vein rilling, theory of .. 20 
 
 Veins, gash 
 
 Veins, lenticular 
 
 j Veins, rake 2 
 
 j Veins, true I 
 
 I Velocity of air 177 
 
 i Ventilation 163 
 
 Ven.tilation by towers 182 
 
 Ventilation by water 184 
 
 Ventilation, natural 174 
 
 Ventilation, wheels 202 
 
 Ventilation with steam 188 
 
 Ventilating machines 190 
 
 Ventilating pressure 189 
 
 Ventilators, general notes on. 203 
 
 Ventilators, efficiency of 207 
 
 Ventilative current, force of. 175 
 
 Victor drill 72 
 
 Volume and pressure 209 
 
 Waddle fan 200 
 
 Walling 116 
 
 Walling, cost of 109 
 
 Walling, levels 113 
 
 Wallaces theory 22 
 
 \Valls of ludc ' 12 
 
3*3 
 
 PAGE 
 
 Wall plates 104 
 
 Wash dirt 31 
 
 Washing ores 235 
 
 Water balance 146 
 
 Water cartridges 62 
 
 W 7 ater ejectors 157 
 
 Water, in bore holes 48 
 
 Water, memoranda on 143 
 
 Water, particles falling in ... 241 
 
 Water wheels 143 
 
 Water raising 149 
 
 Water trompe 184 
 
 Water wheels, power of 144 
 
 Weathering of coal 99 
 
 Wedging curb 106 
 
 Weight of material 5* 
 
 Werners theory 22 
 
 Wheeler pan 231 
 
 Wheels 119 
 
 White Powder 58 
 
 Width of lodes 4 
 
 Wind and ventilation 183 
 
 Winding 131 
 
 Winding, cost of 131, 146 
 
 Winding drum 135 
 
 Winding, examples of 141 
 
 Winding per hour 133 
 
 Winding, spead of 133 
 
 Winding, resistances to 132 
 
 PAGE 
 
 Windlass 145 
 
 Winstanley and Barker's coal 
 
 cutter ..'. 67 
 
 Wire tramways 129 
 
 Wood, cost of IIJ 
 
 Wood, decay of 114 
 
 Wood, preservation of 114 
 
 Wood, varieties of 113 
 
 Work by horses 124 
 
 Work by men 124 
 
 Working away from home ... 94 
 
 Working bordways 92 
 
 Working by pillars 90 
 
 Working horizontal slices ... 89 
 
 Working inclined seams 96 
 
 Working in slices 79 
 
 Working irregular deposits... 90 
 
 Working lodes 88. 
 
 Working on end 92 
 
 Working outwards 94 
 
 Working stratified deposits... 91 
 
 Working, systems of 83 
 
 Working thick seams 97 
 
 Working thin seams 91, 92 
 
 Working, vertical slices 90 
 
 Zone 8 
 
 Zwitter 34 
 

MINING, METALLURGY, ETC. 
 
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