IRLF 
 
 
 
 
 
 
 I 
 
 
1 
 
 REESE LIBRARY 
 
 UNIVERSITY OF CALIFORNIA. 
 
 Received 
 Accessions No. 
 
 .Vie// ,\v> 
 
. 
 
 
A TREATISE 
 
 PRACTICAL AND THEORETICAL 
 
 MINE VENTILATION. 
 
 BY 
 
 EUGENE B. WILSON, 
 
 INSTRUCTOR IN DRIFTON INDUSTRIAL SCHOOL FOR MINERS 
 AND MECHANICS. 
 
 NEW YORK : 
 
 JOHN WILEY & SONS, 
 15 ASTOR PLACE. 
 
 1887. 
 
COPYRIGHT, 1884, 
 BY EUGENE B. WILSON. 
 
 JFranfeltn 
 
 RAND, AVERY, ANC COMPANY, 
 BOSTON. 
 
PREFACE. 
 
 THE author, aware of the interest manifested by miners 
 in this subject, which is so intimately connected with their 
 daily employment, has endeavored to deal with ventilation 
 in such a manner that no one with a fair knowledge of the 
 English language and of arithmetic need despair of thor- 
 oughly mastering it. 
 
 Knowing that the miner possesses but a comparatively 
 small stock of words, and is not an adept in algebraic for- 
 mulas, the writer has taken a different position from the 
 standard works on the subject, endeavoring to do away with 
 abstruse language, and such highly mathematical formulas 
 as are only calculated for well-educated engineers. In 
 order that the text may be more readily followed, each arti- 
 cle is illustrated b}' an example. From the number of fatal 
 explosions which have taken place within the past eighteen 
 months, it is evident that either managers are ignorant of 
 the laws of ventilation, or else negligent in providing methods 
 
 iii 
 
IV PREFACE. 
 
 in conformity with those laws. If the latter is the case, they 
 are the more blamable ; as ignorance of the subject, even at 
 this time, may be excusable, but negligence can never be. 
 There are many practical hints given for engineers, who, 
 owing to lack of time, have been unable to keep as well 
 informed on this subject as they may have wished to do : 
 also many useful memoranda, and tables for saving time and 
 labor when dealing with questions relating to ventilation, 
 will be found in this little volume. 
 
 The author would also state, that this book is intended for 
 miners, and not for engineers ; but at the same time it is 
 believed that it will be found useful to many engineers. 
 
 In hopes of showing how men's lives may be lengthened, 
 and preserved from the dangers that lurk in improperly ven- 
 tilated mines, this work has been written, and is now offered 
 to the class most interested, by their friend and well-wisher, 
 
 E. B. W. 
 
 DRIFTON, PENN., une, 1884. 
 
CONTENTS. 
 
 CHAPTER I. 
 
 PAGE. 
 
 1. Atmosphere. Specific Gravity of Gases . 1 
 
 2. Nitrogen 5 
 
 3. Oxygen 7 
 
 4. Carbonic Acid. Black-Damp 9 
 
 5. Carbonic Oxide. White-Damp 12 
 
 6. Sulphuretted Hydrogen 13 
 
 7. Marsh-Gas. Fire-Damp 14 
 
 8. Expansion of Gases 19 
 
 9. Falling Bodies 22 
 
 CHAPTER II. 
 
 10. Natural Ventilation 23 
 
 11. Motive-Column. Head of Air 25 
 
 12. Variation of Temperature, Effects of .... 27 
 
 CHAPTER III. 
 
 13. Safety-Lamps 29 
 
 14. Comparison of Safety-Lamps and their Efficiency . 37 
 
 14a. Detection of Fire-Damp 39 
 
 v 
 
IV PREFACE. 
 
 in conformity with those laws. If the latter is the ease, they 
 are the more blamable ; as ignorance of the subject, even at 
 this time, may be excusable, but negligence can never be. 
 There are many practical hints given for engineers, who, 
 owing to lack of time, have been unable to keep as well 
 informed on this subject as they may have wished to do : 
 also many useful memoranda, and tables for saving time and 
 labor when dealing with questions relating to ventilation, 
 will be found in this little volume. 
 
 The author would also state, that this book is intended for 
 miners, and not for engineers ; but at the same time it is 
 believed that it will be found useful to many engineers. 
 
 In hopes of showing how men's lives may be lengthened, 
 and preserved from the dangers that lurk in improperly ven- 
 tilated mines, this work has been written, and is now offered 
 to the class most interested, by their friend and well-wisher, 
 
 E. B. W. 
 
 DRIFTON, PENN., "ane, 1884. 
 
CONTENTS. 
 
 CHAPTER I. 
 
 PAGE. 
 
 1. Atmosphere. Specific Gravity of Gases 1 
 
 2. Nitrogen 5 
 
 3. Oxygen 7 
 
 4. Carbonic Acid. Black-Damp 9 
 
 5. Carbonic Oxide. White-Damp 12 
 
 6. Sulphuretted Hydrogen 13 
 
 7. Marsh-Gas. Fire-Damp 14 
 
 8. Expansion of Gases 19 
 
 9. Falling Bodies 22 
 
 CHAPTER II. 
 
 10. Natural Ventilation 23 
 
 11. Motive-Column. Head of Air 25 
 
 12. Variation of Temperature, Effects of .... 27 
 
 CHAPTER III. 
 
 13. Safety-Lamps 29 
 
 14. Comparison of Safety-Lamps and their Efficiency . 37 
 
 14a. Detection of Fire-Damp 39 
 
 v 
 
VI CONTENTS. 
 
 CHAPTER IV. 
 
 PAGE. 
 
 15. Physical Properties of Air in Motion .... 40 
 
 16. Perimeter, Area, etc., denned 42 
 
 17. Friction of Air in Airways 43 
 
 la Water-Gauge 43 
 
 19. Co-efficient of Friction 47 
 
 20. Pressure 49 
 
 21. Pressure, continued 50 
 
 CHAPTER V. 
 
 22. Laws of Pressure, and Friction of Air in Mines, with 
 
 Problems illustrating the Same 53 
 
 CHAPTER VI. 
 
 23. Laws regulating the Quantity of Air flowing through 
 
 Mines 59 
 
 24. Problems illustrating above Laws 61 
 
 25. Water Gauge and Pressure 67 
 
 CHAPTER VII. 
 
 26. Ventilation of Single Pits or Drifts 69 
 
 27. Ventilation of Mines with Two Orifices ... 72 
 
 23. Doors and Eegulators 73 
 
 CHAPTER VIII. 
 
 29. Splitting the Air 76 
 
 30. Explanation of Splits 77 
 
CONTENTS. Vll 
 
 PAGE. 
 
 31. Advantages of Splits 79 
 
 32. Area of Airways 85 
 
 33. Problem on splitting the Air 86 
 
 CHAPTER IX. 
 
 34. Quantity of Air necessary for a Mine .... 88 
 
 35. Prevention of Explosions .92 
 
 36. Efficient Ventilation 96 
 
 CHAPTER X. . 
 
 37. Air Measurements 97 
 
 38. Method of Procedure 101 
 
 39. Barometer , 103 
 
 CHAPTER XI. 
 
 40. History of Mechanical Ventilators .... 109 
 
 41. Fans 112 
 
 42. GuibalFan 115 
 
 43. Comparative Economy between Furnace and Fan Venti- 
 lation . 117 
 
 44. Formulas 121 
 
 45. Problems 124 
 
 46. Quantity of Air necessary per Man .... 128 
 
 47. Treatment of Asphyxiated Persons 130 
 
/^::. 
 
 fJVERSlTY 
 
 MINE VENTILATION. 
 
 CHAPTER I. 
 
 1. THE atmosphere is composed of nitrogen and 
 oxygen, with a trace of carbonic-acid gas. 
 
 These three gases, essential to the existence of all ani- 
 rnal and vegetable life, when taken separately will not 
 support life. A mechanical mixture of these gases, in 
 the proportion of four parts of nitrogen to one part of 
 oxygen, is the air we breathe; which, if mixed with 
 deleterious gases (or, as we say, impure), will cause 
 serious physical disorders, and not unfrequently pre- 
 mature death. Carbonic- acid gas rarely exceeds one 
 part in sixteen hundred of pure air ; being present in 
 the atmosphere, so say our best chemists, in the ratio of 
 four parts in ten thousand. The term " atmosphere " 
 designates that immense expanse or ocean of gaseous 
 matter which envelops or surrounds our earth, com- 
 monly called u air." It is supposed that this atinos- 
 
Z MINE VENTILATION. 1 
 
 phere is forty-five miles thick about the earth : which, 
 however, is merely supposition, as the height has not 
 as yet been computed with accuracy, although it has 
 been proven that Mariotte's law is conformed to by 
 the gases which constitute the air ; their density vary- 
 ing according to the pressure. 
 
 That the atmosphere varies in pressure was recog- 
 nized at an early period: even the Florentine pump- 
 makers were acquainted with the fact that water could 
 not be raised by suction from a depth of more than 
 thirty to thirty-three feet. 
 
 Galileo explained this phenomenon, and clearly 
 demonstrated that the pressure of the atmosphere was 
 equal to the weight of thirty-three feet of water. 
 
 Torricelli argued from this, that, if the atmosphere 
 would support thirty-three feet of water, it would not 
 support more than thirty inches of mercury; as mercury 
 is about fourteen times heavier than water. The result 
 of Torricelli's investigations and experiments gave us 
 the instrument known as the barometer, by means of 
 which we can measure the density of the atmosphere, 
 which is on an average equal to the weight of a column 
 of mercury thirty inches in height at sea-level. The 
 temperature of the atmosphere is not the same through- 
 out: it becomes colder as we ascend; hence on the top 
 of high mountains we find snow the year round. 
 
1. MINE VENTILATION. 3 
 
 \ 
 
 That air has weight may be shown by the following 
 experiment. Take a vessel whose capacity, say, is 100 
 cubic inches, exhaust it of air, and then weigh it. Let 
 it now be filled with dry air at the ordinary tempera- 
 ture and pressure, then weighed again. Upon second 
 weighing it is found to be 31,074 grains heavier than 
 at the first. As the weight of the atmosphere will 
 sustain a column of mercury whose ba"se is one inch 
 square, and whose height is thirty inches, it must press 
 down with a weight equal to the weight of the mercury 
 of the above dimensions to balance it. The weight of 
 this mercury is 14.7225 pounds, and hence the atmos- 
 phere has a weight or pressure equal to 14.7 on each 
 square inch of surface exposed to it. 
 
 Air is taken as the standard of comparison for all 
 gases and vapors. The chemical composition of air in 
 its natural state is given by Dr. Frankland as follows: 
 
 Oxygen 20.61 
 
 Xitrogen 77.95 
 
 Carbonic acid * . . .04 
 
 Moisture. 1.40 
 
 100.00 
 Dry air is composed of 
 
 Per cent by weight. Per cent by vol. 
 
 Nitrogen 77 79 
 
 Oxygen 23 21 
 
 100 100 
 
MINE VENTILATION. 
 
 1- 
 
 The specific gravity of the gases in the following 
 table was determined experimentally by De la Roche 
 and Berad, who took air as the standard for gases. 
 
 TABLE I. 
 
 NAME OF GAS. 
 
 Symbols. 
 
 Specific gravity. 
 
 AtrnospliGi'6 
 
 N 4 O 
 
 1 0000 
 
 Hydrogen . 
 
 H 
 
 0692 
 
 
 H 2 O 
 
 0.6210 
 
 Olefiant eras 
 
 C 9 H 
 
 9672 
 
 Carbonic oxide . . . 
 
 CO 
 
 09674 
 
 
 N 
 
 0.9713 
 
 Nitric oxide 
 
 NO 
 
 1.0390 
 
 Oxygen . .... 
 
 o 
 
 1 1056 
 
 Nitrous oxide 
 
 N 2 O 
 
 1 5250 
 
 Carbonic acid 
 
 CO. 2 
 
 1.5290 
 
 Sulphurous acid 
 
 S0 2 
 
 2.470 
 
 Manner of finding the weight of a gas compared 
 with that of air is illustrated by the following problem. 
 Example. If 1,000 cubic feet of air weigh 80.728 
 pounds when the temperature is 32 and the barometer 
 30", what will 1,000 cubic feet of nitrogen weigh under 
 the same conditions? 
 
 Solution. From the table we find the density of 
 nitrogen to be 0.9713 when air is one : hence we have 
 the proportion 1 : 0.9713 = 80.728 : Ans., or 78.415 + 
 pounds. 
 
2. MINE VENTILATION. 5 
 
 2. The miner lias to deal with several gases, espe- 
 cially the coal-miner. It is therefore imperative that 
 he should know the composition of these gases, so as 
 to be able to distinguish them. To this end, therefore, 
 a brief synopsis of some of the gases so often met with 
 in mines, together with their properties, is here inserted. 
 
 Nitrogen. 
 Symbol, N. Equivalent, 14. Specific gravity, 0.9713. 
 
 The name signifies nitre-maker. It constitutes about 
 four-fifths of the atmosphere, and enters into a great 
 variety of combinations. Nitrogen is somewhat lighter 
 than air; a cubic foot of the gas weighing 0.0784167 
 pounds, while a cubic foot of air weighs 0.080728 
 pounds. Nitrogen may be obtained by burning the 
 oxygen from a confined portion of air. It is incapable 
 of sustaining combustion or animal life : not that it has 
 positive poisonous properties ; but flame is extinguished, 
 and animals smother, for want of oxygen. It is best 
 characterized by its passiveness ; as it has very little 
 affinity or attraction for other elements, and upon the 
 slightest provocation will free itself if possible. For 
 instance, it may be induced to combine with iodine, 
 and form " nitric iodide," a black, insoluble powder, 
 which will explode if moved, jarred, or even touched 
 with a feather. It enters into the composition of gun- 
 
6 MINE VENTILATION. 2. 
 
 powder, nitro-gtycerine, and dynamite. With oxygen 
 it forms five distinct compounds : 
 
 a, Nitrous oxide, N 2 O. 
 6, Nitric oxide, NO. 
 
 c, Nitrous anhydride, N 2 O 3 . 
 
 d, Nitrogen peroxide, NO 2 . 
 
 e, Nitric anhydride, N 2 O 5 . 
 
 #, Nitrous oxide, or nitrogen sub-oxide, when pure, 
 may be respired for a few minutes with impunity. When 
 inhaled in large quantities, it produces a lively intoxi- 
 cation, accompanied with violent laughter: whence it 
 derives the name of " laughing-gas." 
 
 5, Nitric oxide, or nitrogen protoxide, may be pre- 
 pared by treating copper filings, or turnings, with nitric 
 acid. The gas obtained in this manner is colorless and 
 transparent : in contact with air or oxygen, it produces 
 deep-red fumes. 
 
 e, Nitrous anhydride is an obscure body, and forms, 
 with the elements of water, an acid known as " nitrous 
 acid." 
 
 d, Nitrogen peroxide is the chief constituent of the 
 deep-red fumes noticed when nitrogen protoxide is 
 brought in contact with air. 
 
 e. Nitric anhj'dride is a very unstable, white, solid 
 compound, decomposing spontaneously into nitrogen 
 peroxide and oxygen. When treated with water, it 
 forms nitric acid. 
 
3. MINE VENTILATION". 7 
 
 Oxygen. 
 Symbol, O. Equivalent, 16, Specific gravity, 1.1056. 
 
 3. Oxygen forms one-fifth part of the atmosphere. 
 It is transparent and colorless, not to be distinguished 
 by its aspect or smell from atmospheric air. It is the 
 most widely diffused of all the elements, forming about 
 one-third of the solid crust of the globe. It unites 
 with all the other elements to form compounds, which 
 are sometimes gaseous, sometimes solid, sometimes 
 liquid. The name signifies acid-former; and, with one 
 exception, oxygen enters into the combination of acids. 
 All the ordinary phenomena of fire and light which we 
 daily witness depend upon the union of the body burned 
 with the oxygen of the air : in fact, the term " oxida- 
 tion" may, for all ordinary purposes, be regarded as 
 synonymous with "combustion." 
 
 Faraday has roughly estimated that the amount of 
 oxygen required daily to supply the lungs of the human 
 race is at least one thousand millions of pounds; that 
 required for the respiration of the lower animals is at 
 least twice as much as this; while the always active 
 process of decay requires certainly no less than four 
 times as much. Faraday also estimates that one thou- 
 sand millions of pounds are sufficient to sustain all the 
 artificial fires lighted by man, from the camp-fire of 
 
8 MINE VENTILATION. 3. 
 
 the savage to the roaring blaze of the blast-furnace, or 
 the raging flames of a grand conflagration. 
 
 Amount of Oxygen required Daily. 
 
 Pounds. 
 
 Whole population 1,000,000,000 
 
 Animals 2,000,000,000 
 
 Combustion and fermentation 1,000,000,000 
 
 Decay and other processes 4,000,000,000 
 
 Total amount of oxygen required daily . . . 8,000,000,000 
 
 These figures are inconceivable ; and, when we reduce 
 the oxygen consumed to tons, we fail to grasp it, as it 
 is no less than 3,571,428 tons. 
 
 Although the consumption of oxygen is so great, yet 
 there is no fear of its being exhausted ; as, at the present 
 rate of consumption, there is enough to last nine hun- 
 dred thousand years. Oxygen is the active principle 
 of the atmosphere. It devours every thing with which 
 it can unite : it corrodes metals, decays fruits, promotes 
 combustion, and is a prime necessity for health. 
 
 The body is a stove, in which fuel is burned ; the 
 chemical action being the same as in any other stove. 
 We take into our lungs air, and give out a poisonous 
 gas, carbonic-acid, the waste products of the com- 
 bustion of our bodies. From this we may learn how 
 important a factor oxygen is for health, and how neces- 
 sary it is that we have plenty of fresh, pure air, if we 
 
4. MINE VENTILATION. 
 
 wish to be free from disease. One man breathes into 
 his lungs at each inspiration about 230 cubic inches of 
 air, or one gallon. In the delicate cells of the lungs 
 the air gives up its oxygen to the blood, receiving, in 
 turn, carbonic acid and water, foul with waste matter 
 which the blood has picked up in its circulation through 
 the body. Should we rebreathe it into our lungs, the 
 blood will leave the lungs, not bearing invigorating 
 oxygen, but refuse matter to obstruct the whole system. 
 Without oxygen the muscles become inactive, the 
 heart acts slowly, food is undigested, brain is clogged, 
 and at last such fatal results as were manifested in the 
 " Black Hole of Calcutta " implore us not to be stingy 
 or afraid of "God's blessing," pure air. 
 
 4. Having examined slightly the constituent parts 
 of the atmosphere, let us briefly examine the principal 
 gases met with in coal-mining. 
 
 Carbonic -Acid Cras. 
 Symbol, CO 2 . Equivalent, 22. Specific gravity, 1.53. 
 
 One cubic foot of the gas at 32 F., and barometer at 
 30", weighs 0.12845 of a pound. 
 
 This gas is composed of carbon and oxygen. Miners 
 have given it several names, such as " sty the," " choke- 
 damp," "black-damp," and "after-damp." This gas is 
 
10 MINE VENTILATION. 4. 
 
 always produced when compounds containing carbon 
 are burnt in air or- oxygen. It may be produced by 
 treating limestone or marble with hydrochloric or 
 sulphuric acids. The occluded gases in all coal con- 
 tain carbonic acid. Carbonic acid is considered poison- 
 ous, on account of the many deaths which have resulted 
 from burning charcoal and carbonaceous materials in 
 places where there was a deficiency of ventilation, and 
 by reason of the fatal nature of after-damp of explo- 
 sions in coal-mines. Its specific gravity is 1.524; so 
 that it is a little more than one and a half times as 
 heavy as air. It lodges near the floor of places in which 
 it is evolved when little more than mutual diffusion is 
 going on. Owing to its great density, it may be poured 
 from one vessel to another. It is the only gas, except 
 nitrogen, which is evolved by most bituminous coals ; 
 and, when it is given off in quantity, active ventilation 
 is required to carry it off. 
 
 Le Blanc, and many other chemists, affirm that air con- 
 taining more than five parts in a thousand is injurious 
 to breathe. Mr. J. W. Thomas of England, while not 
 asserting that it is not injurious, says, that "in levels 
 and seams of semi-bituminous and bituminous coals in 
 South Wales, in part or wholly worked to the dip, with 
 scanty ventilation in some particular spots, through the 
 non-completion of air-splits, or conveyances, men often 
 
4. MINE VENTILATION. 
 
 work in an atmosphere containing from two to five per 
 cent of this gas for hours." Be that as it may, the sys- 
 tem, uninspired by the energizing oxygen, is sensitive 
 to cold. The pale cheek, the lustreless eye, the languid 
 step, shortness of breath, speak but too plainly of oxygen 
 starvation. "In such a soil, catarrh, scrofula, miners' 
 asthma, and consumption run riot." 
 
 Miners call the carbonic acid produced" by the explo- 
 sion of fire-damp, "after-damp." They fear it almost 
 as much as fire-damp, as it instantly destroys the lives 
 of all who may have escaped the flames of the explo- 
 sion. This property of carbonic acid, of choking or 
 smothering, has of late years been made use of for 
 putting out fires in coal-mines. In one case, an Eng- 
 lish mine which had been burning twenty years was 
 smothered by pouring into it eight billion cubic feet of 
 carbonic acid, and then closing it up for one month. 
 At the end of the month the mine was opened, and 
 found to be ready for the resumption of labor. 
 
 When found alone in a mine, carbonic acid is not 
 considered as dangerous as fire-damp, since it will not 
 burn. Carbonic acid, at the ordinary temperature and 
 pressure, is a gas. It solidifies when subjected to great 
 pressure ; but, as soon as the pressure is removed, it 
 returns to the gaseous state : therefore the term " car- 
 bonic acid " is applied as well to the gas as to the acid. 
 
12 MINE VENTILATION. 5. 
 
 Carbonic Oxide. 
 Symbol, CO. Equivalent, 14. Specific gravity, 0.9674. 
 
 5. One cubic foot of the gas at 32 F., and barometer 
 of 30", weighs 0.078305 of a pound. 
 
 This gas is sometimes called "white-damp." From 
 experiments made by Dr. Meyer and J. W. Thomas, it 
 was found, that, during every explosion, large quanti- 
 ties of this gas were formed, and that the fatal effects 
 of the after-damp are in a great measure due to its 
 presence. Carbonic oxide is an odorless and colorless 
 gas, incapable of supporting the combustion of other 
 bodies, but is itself an inflammable gas. It possesses 
 very poisonous properties, which act powerfully on the 
 blood and nervous system, producing, when inhaled in 
 very small quantities, a most unpleasant sensation, fol- 
 lowed quickly by headache, and disinclination to move, 
 prostration and inactivity : if continued to be breathed, 
 asphyxia follows, and death soon results. Air contain- 
 ing only one-half per cent of this gas would prove fatal, 
 if inspired for any length of time. Mr. Thomas advo- 
 cates oxygen and induced artificial breathing, for those 
 who are overcome by this gas, in preference to the 
 administration of alcoholic stimulants. 
 
6. MINE VENTILATION. 13 
 
 The composition of carbonic oxide is, 
 
 By weight. By volume. 
 
 Carbon 42.86 1 
 
 Oxygen 57.14 1 
 
 100.00 2 
 
 This gas is narcotic, and, when breathed in a concen- 
 trated form, would produce no pain, the body passing 
 instantly into a state of coma. Whatever position the 
 victim assumed, in that position he would be found 
 dead, unless moved by some other means. u Carbonic 
 acid, and the nitrogen left after an explosion, would 
 be fatal in their effects ; but very often men have suc- 
 cumbed to supposed after-damp, while their lamps 
 burned well. The presence of carbonic acid and nitro- 
 gen will not account for the result or phenomena." 
 
 SULPHUKETTED HYDROGEN. 
 
 Symbol, SH 2 . Equivalent, 17. Specific gravity, 1.178. 
 
 6. One cubic foot of the gas at 32 F. and barometer 
 of 30", weighs 0.09492 of a pound. 
 
 This gas, although not common, is met with some- 
 times in mines. It is colorless, but -easily distinguished 
 by its peculiar smell, that of rotten eggs. It may 
 be prepared by treating sulphide of iron with dilute 
 sulphuric acid. The composition of sulphuretted hydro- 
 gen is, 
 
14 MINE VENTILATION. 7 
 
 By weight. By atcras. 
 
 Sulphur 94.12 1 
 
 Hydrogen 5.88 2 
 
 100.00 3 
 
 When mixed with oxygen, it will explode if ignited. 
 When inhaled in a pure state, it is a powerful narcotic 
 poison, and produces fainting and asphyxia when pres- 
 ent in very small proportions of the atmosphere. It 
 appears to be probable that the gas is generated in 
 small quantities in old worked-out mines. Some claim 
 that it is formed by the decomposition of pyrites in old 
 workings ; others, that it is not formed in this manner, 
 but by the decomposition of props and timber standing 
 in water, by breaking up the sulphate of lime, and 
 assimilating its oxygen, while sulphur seizes upon the 
 Imlrogen of the wood to form sulphuretted hydrogen. 
 This gas is also known as hydrosulphuric and sulphuric 
 acid gas. 
 
 MARSH-GAS. 
 Symbol, CH 4 . Equivalent, 8. Specific gravity, 0.55314. 
 
 7. One cubic foot of this gas, at 32 F. and barome- 
 ter of 30", weighs 0.044665 of a pound. 
 
 It is known by several names, proto-carburetted hy- 
 drogen, light carburetted hydrogen, hydride of methyl, 
 fire-damp. Marsh-gas, however, is better known to 
 
7. MINE VENTILATION. 15 
 
 miners as " fire-damp/' It is colorless, tasteless, odor- 
 less, when pure, burning with a yellowish flame. It is 
 formed in swamps and marshy places by the decom- 
 position of vegetable matter, and may be seen bubbling 
 up through the water when the mud is stirred beneath. 
 Marsh-gas is found in such quantities in some places, 
 that it is used for lighting towns, and. evaporating 
 brine. In the oil-regions it frequently bufsts forth with 
 explosive violence, throwing the oil high in the air when 
 the drill nears it. Coal-gas contains about thirty-eight 
 per cent of marsh-gas. When marsh-gas is evolved 
 in the shape of " blowers," it constitutes about ninety- 
 six per cent of the total volume. Blowers sometimes 
 assume enormous dimensions, and have been conveyed 
 from the workings to the surface by means of pipes, 
 and utilized. Marsh-gas is not poisonous. Sir H. Davy, 
 of safety-lamp fame, was the first to experiment on this 
 gas. He found, that, when mixed with three and a half 
 times its volume of air, it did not explode ; with five 
 and a half times its volume, it exploded slightly ; and, 
 when mixed with eight or nine volumes of air, the force 
 of explosion was greatest. When there is a deficiency 
 of ventilation, the fire-damp is said to rise to the upper 
 portion or top of a gallery, and there remain, because 
 of its being lighter than air. It is also said that car- 
 bonic acid, being heavier than air, lodges on the "floor" 
 
16 MINE VENTILATION. 7 
 
 or " thill " of a mine. Mr. Thomas, in his book on 
 "Mines, Gases, and Ventilation," says, "This impres- 
 sion is erroneous; and while not denying that fire-damp 
 is often found in larger quantities near the roof, and 
 carbonic acid in larger quantities near the floor, these 
 positions do not prove that they have lodged there, nor 
 is it so : on the contrary, marsh-gas is always diffusing 
 in every direction ; and it is only in those places where 
 the gas is evolved in greater quantity than will diffuse, 
 or become carried away by the ventilation, that accu- 
 mulation takes place. These erroneous ideas in refer- 
 ence to marsh-gas arose from the fact that it is found 
 in the crevices and holes, and near the roof, of coal- 
 mines." The explanation of this is very simple. The 
 fact of portions of top-rock falling, and the squeezing-in 
 or lowering of the top throughout the whole worked 
 portion above the coal, affords communication with, it 
 may be, some rider or un worked seam of coal above, 
 with the receding working-face, or with crevices which 
 are in communication with stores of fire-damp extend- 
 ing to considerable distances. Now, the pressure of 
 the atmosphere being the same on all sides, the gas in 
 the fissures and cracks in the top are subjected to that 
 pressure externally, so that air finds no outlet through 
 these cracks, and the diffusion which takes place is 
 simply " natural " or mutual diffusion. 
 
7. MINE VENTILATION. 17 
 
 The fire-damp issuing into these cracks, etc., encoun- 
 ters the same pressure as if issuing direct into the air- 
 current; so that it would find its way downwards by 
 virtue of the extra force of pressure of the imprisoned 
 gas into the top of the holes, goaves, or receptacles in 
 the top-rock, and it would be more likely to escape or 
 find an exit in these places, or come in contact with the 
 ventilating current here, owing to the fact that more 
 easy communication is afforded by the dislocation and 
 partial disintegration of the top caused by a fall, 
 followed by a partial .opening-up of the surrounding 
 mass. The fire-damp, therefore, instead of accumulating 
 and lodging at the roof of the gallery by virtue of its 
 lesser density, is forced downwards until it finds its way 
 into the holes and other receptacles, and is continually 
 fed from above. 
 
 "When marsh-gas escapes from the floor, and makes 
 its appearance in quantity near the roof, it shows 
 deficiency of ventilation, or a strong outpour of gas; 
 but even then, if there is any ventilation at all, it will 
 be largely mixed with air." 
 
 The reason that fire-damp is in the form of an explo- 
 sive mixture in holes in the top, is because it is fed 
 more quickly from above than it is able to diffuse ; the 
 ventilating current not affecting it to a very great 
 extent. 
 
18 MINE VENTILATION. 7. 
 
 Let the lines below represent a gallery from which 
 some of the top has fallen. F is the floor, RR the roof, 
 and H the hole caused by the fall. If a lamp be raised 
 about halfway between R and F, an explosive mixture 
 may be encountered ; but, if the lamp is held near the 
 
 cracks in RR, not a trace of gas will be indicated by it, 
 provided there is sufficient ventilation. Gradually stop 
 the ventilating current, so that the air scarcely travels, 
 and then apply the lamp, and the fire-damp issuing from 
 the cracks may be detected. Active ventilation sweeps 
 away all the gas which escapes from cracks in the line 
 of the top rock or roof; but as the current can find no 
 outlet through the hole at H, and encounters a press- 
 ure equal or superior to that along the roof, it travels 
 onward, heedless of any gas situated out of the line 
 RR. When fire-damp accumulates near the roof or 
 top line of a gallery or heading, it indicates that the 
 gas is given off in greater quantity than can be carried 
 off by the ventilation ; and, where any such accumula- 
 tion takes place, there must be either a deficiency of 
 ventilation, or an unusual inpour of gas. 
 
8. MINE VENTILATION.. 19 
 
 EXPANSION OF GASES. 
 
 8. One of the chief characteristics of any gas is its 
 expansive property. To calculate the expansion of any 
 volume of air, the starting-point must always be taken 
 at on Fahrenheit's scale ; for air at that temperature 
 will expand ? -J- 9 of its volume for every degree of heat 
 added. Therefore 459 cubic feet of air at will be- 
 come 460 cubic feet at 1 F. 
 
 Careful experiments show that 459 cubic feet of air 
 at F. weigh 39.76 pounds, when the pressure is 30 
 inches of mercury of the density due to 32, a press- 
 ure equal to 14.7 pounds per square inch ; but, when 
 the pressure is one inch, it weighs only ^ part of this, 
 or 1.3253 pounds. To find the weight of a cubic foot 
 of air at any temperature or height of the barometer, let 
 
 B = height of the barometer in inches, 
 t = temperature by Fahrenheit's thermometer ; 
 
 then 
 
 1.3253 X B 
 
 (1) 
 
 459 + t 
 
 Problem. What is the weight of a cubic foot of air, 
 the temperature of which is 96, under a barometric 
 pressure of 29.5 inches of mercury? 
 
 By substituting 29.5 in formula 1 for B, and 96 for 
 
20 .MINE VENTILATION. 8. 
 
 f, and then performing the operations indicated, we 
 have 
 
 1.3253 x 29.5 A , 
 
 W = = 0.07044 pound 
 
 459 + 96 
 
 as the weight of a cubic foot of air under the above 
 conditions. 
 
 The following table has been made out to facilitate 
 calculations. It gives the weight of 100 cubic feet of 
 air in pounds at different barometrical pressures. 
 
8. 
 
 MINE VENTILATION. 
 TABLE II. 
 
 21 
 
 
 III 
 
 d % 
 
 to 
 
 II, 
 
 to 
 
 2 
 
 .2 " 
 
 111 5 .' 
 
 aT 
 
 1 * 
 
 o .S 8 
 
 g .S 8 
 
 O.S8 
 
 g .2 53 
 
 ^ - a of 
 
 -.-j 
 2 ^3 
 
 o^ 1 
 
 *** 
 
 M 
 
 *s * 
 
 s2 J 
 
 S *~ v "S 
 |g|| 
 
 8,-g 
 
 1 1 
 
 111 
 
 
 
 tj) :* fl> 
 
 .SP * 
 
 111 
 
 |l|l 
 
 
 ^ M -0 
 
 * 
 
 ^o 
 
 ^-0 
 
 ^ t-. "O 
 
 g T3 
 
 30 
 
 7.857 
 
 7.993 
 
 8.129 
 
 8.265 
 
 8.400 
 
 0.136 
 
 32 
 
 7.826 
 
 7.961 
 
 8.096 
 
 8.231 
 
 8.366 
 
 0.135 
 
 42 
 
 7.670 
 
 7.802 
 
 7.934 
 
 8.066 
 
 8.198 
 
 0.132 
 
 52 
 
 7.519 
 
 7.649 
 
 7.779 
 
 7.909 
 
 8.039 
 
 0.130 
 
 62 
 
 7.375 
 
 7.502 
 
 7.629 
 
 7.756 
 
 7.883 
 
 0.127 
 
 72 
 
 7.236 
 
 7.361 
 
 7.486 
 
 7.611 
 
 7.736 
 
 0.125 
 
 82 
 
 7.103 
 
 7.225 
 
 7.347 
 
 7.471 
 
 7.593 
 
 0.122 
 
 92 
 
 6.974 
 
 7.094 
 
 7.214 
 
 7.334 
 
 7.454 
 
 0.120 
 
 102 
 
 6.849 
 
 6.968 
 
 7.085 
 
 7.204 
 
 7.323 
 
 0.119 
 
 112 
 
 6.729 
 
 6.845 
 
 6.961 
 
 7.077 
 
 7.193 
 
 0.116 
 
 122 
 
 6.614 
 
 6.728 
 
 6.842 
 
 6.956 
 
 7.070 
 
 0.114 
 
 132 
 
 6.502 
 
 6.614 
 
 6.726 
 
 6.838 
 
 6.950 
 
 0.112 
 
 142 
 
 6.394 
 
 6.504 
 
 6.614 
 
 6.728 
 
 6.834 
 
 0.110 
 
 152 
 
 6.289 
 
 6.397 
 
 6.506 
 
 6.614 
 
 6.722 
 
 0.108 
 
 162 
 
 6.188 
 
 6.294 
 
 6.401 
 
 6.508 
 
 6.614 
 
 0.106 
 
 172 
 
 6.089 
 
 6.-195 
 
 6.300 
 
 6.405 
 
 6.509 
 
 0.104 
 
 182 
 
 5.995 
 
 6.098 
 
 6.201 
 
 6.304 
 
 6.408 
 
 0.103 
 
 192 
 
 5.903 
 
 6.004 
 
 6.106 
 
 6.208 
 
 6.309 
 
 0.101 
 
 202 
 
 5.813 
 
 5.913 
 
 6.014 
 
 6.114 
 
 6.214 
 
 0.100 
 
 212 
 
 5.726 
 
 5.825 
 
 5.924 
 
 6.023 
 
 6.122 
 
 0.099 
 
 222 
 
 5.642 
 
 5.739 
 
 5.837 
 
 5.934 
 
 6.032 
 
 0.097 
 
 232 
 
 5.561 
 
 5.657 
 
 5.753 
 
 5.843 
 
 5.939 
 
 0.096 
 
 242 
 
 5.481 
 
 5.576 
 
 5.671 
 
 5.765 
 
 5.861 
 
 0.095 
 
 252 
 
 5.404 
 
 5.497 
 
 5.591 
 
 5.684 
 
 5.777 
 
 0.093 
 
 262 
 
 5.329 
 
 5.421 
 
 5.513 
 
 5.605 
 
 5.697 
 
 0.092 
 
 272 
 
 5.256 
 
 5.347 
 
 5.438 
 
 5.527 
 
 5.618 
 
 0.091 
 
 282 
 
 5.185 
 
 5.275 
 
 5.364 
 
 5.453 
 
 5.542 
 
 0.089 
 
 292 
 
 5.117 
 
 5.205 
 
 5.293 
 
 5.381 
 
 5.469 
 
 0.088 
 
 302 
 
 5.049 
 
 5.136 
 
 5.223 
 
 5.310 
 
 5.397 
 
 0.087 
 
22 MINE VENTILATION. 9. 
 
 9. As we have seen, air has weight, and therefore 
 becomes subject to the " physical laws " that govern 
 liquids and falling bodies; i.e., air is acted on by gravity 
 in the same manner as a solid. 
 
 Let li = the distance fallen through in feet. 
 
 v = the velocity acquired at the end of the fall, in 
 
 feet per second. 
 g = the distance in feet which an unresisted gravitat- 
 
 ing body falls in the first second of time ; 
 
 which distance has been found by experiment 
 
 to be 16 T \ feet near the earth's surface. 
 
 Since a body falls 16.08' in one second, it gains a 
 velocity of 32.16' at the end of the first second: hence 
 we have 
 
 (2) v = V/V* = 8.0208 \fh. 
 
 In this equation h represents the he.cessary height, in 
 feet, of a vertical air-column which will produce by its 
 weight a velocity equal to v. If this velocity be repre- 
 sented in feet per minute, we shall have 
 
 (3) v = 8.020SV^ X 60 = 481.2^, 
 
 and 
 
 tf _v*_ 
 
 ~ (481. 2) 2 ~ 231,600' 
 
10. 
 
 MINE VENTILATION. 
 
 23 
 
 These formulae (2), (3), and (4) are only theoreti- 
 cally true as regards air in mines, the pressure or head 
 of air-column required being from ten to twenty times 
 as much in order to overcome the friction and resist- 
 ance of airways, etc., in underground workings ; and, 
 were it not for these resistances, very small pressure 
 would suffice to produce great velocity. 
 
 CHAPTER II. 
 
 NATURAL VENTILATION. 
 
 10. MOTION in air is caused by pressure, or differ- 
 ence of pressure. When air becomes heated, it ascends, 
 because it assumes a larger volume ; 
 and, as the same volume of cold air 
 is heavier, it pushes the warmer A 
 up, or out of its place. This phe- 
 nomenon in the open air gives rise 
 to winds and breezes, which vary 
 in intensit}', according as the cool 
 air takes the place of the warm air, rapidly or slowly. 
 
 Suppose we have two shafts (connected, as in the 
 above figure) of equal depths, the air in them having 
 
24 MINE VENTILATION. 10. 
 
 the same temperature and density throughout. If no 
 artificial means be used to cause a movement in either 
 direction, down one, and up the other, the air will 
 be in equilibrium, and be stagnant. If the tops of the 
 shafts be not of the same height, as AB, the air AE, if 
 of the same density and temperature, would have the 
 same effect as if the shaft rose to E, and remain in 
 equilibrium. Suppose, now, that the external air is of 
 lower temperature than the air in the shafts, and the 
 column AB lower in temperature than CD, a movement 
 of the air then takes place from A towards C. On the 
 contrary, if the external air be warmer than that of 
 the shafts, the shaft AB will be the upcast, and circu- 
 lation will be from to A> on account of the heavier 
 column of air CD. 
 
 This is the principle upon which furnaces are em- 
 ployed to ventilate mines. They are placed at the 
 bottom, or near the bottom, of the upcast shaft. The 
 heat given off by them raises the temperature of the air, 
 which expands ? -J-g part of its volume for each degree 
 of heat added, and hence becomes lighter. The cooler 
 air of the downcast shaft is now able, owing to its 
 greater density, to fall down the shaft, and push the 
 air of the mine into the upcast, which becomes, in turn, 
 heated by the furnace. Let us take an example to see 
 in what manner this difference in density will cause 
 
11. MINE VENTILATION. 25 
 
 ventilation. Suppose the two shafts to be of equal 
 depth, say 900 feet, and suppose the barometer to stand 
 at 29 inches ; also let the temperature in the downcast 
 be assumed to be 42, and that of the upcast 72. 
 From the table on p. 21, we find that 100 cubic feet of 
 air at 42 weigh 7.67 pounds : therefore 900 cubic feet 
 weigh 9 times as much, or 69.030 pounds. Again : we 
 find 100 cubic feet of air at 72 weigh 7.236 pounds, 
 and hence 900 cubic feet weigh 65.124 pounds. The 
 difference between these weights will give the pressure 
 that would cause circulation. 
 
 Pounds. 
 
 900 cubic feet at 42 = 69.030 
 900 cubic feet at 72 - 65.124 
 
 Difference in weight 3.906 
 
 This pressure in the open air would produce a velocity 
 of wind between twenty-five and thirty miles per hour. 
 
 11. The " motive-column" is a "head of air" of such 
 a height that it will equal the difference between the 
 weight of the downcast and upcast columns of air. 
 
 Let M = the motive-column, or head of air, 
 D = the depth of the upcast in feet, 
 t the temperature of the upcast in degrees, 
 l l = the temperature of the downcast in degrees, 
 
28 MINE VENTILATION. 11. 
 
 then, 
 
 M ^ D X 459* + ^ 
 
 Problem. Find the motive-column which would pro- 
 duce a pressure of 3.906 pounds when the upcast has 
 a depth of 900 feet and a temperature of 72^ and the 
 downcast has the same deptli and a temperature of 42. 
 
 Substituting in formula 5 we have 
 
 as the length of the motive-column. 
 
 The height of a column of this air, one foot in area, 
 weighing one pound, may be found by dividing the 
 motive-column by the pressure per square foot; thus: 
 
 53.8922 
 "3790 6" : 
 
 The relative diameters of the shafts make no differ- 
 ence upon the total pressure, so far as the considera- 
 tions regarding ventilation are concerned. This is 
 termed " the pneumatic paradox ; " for if we have one 
 square foot area for a downcast, and an upcast of ten 
 square feet, the pressure on each square foot of upcast 
 will be the same as on the one square foot of the down- 
 cast, provided there is no friction. 
 
12. MINE VENTILATION. 27 
 
 When calculating the weight of the motive-column, 
 we must bear in mind that it is not the total amount 
 of air, or the total number of cubic feet, that we seek, 
 but the length of an air-column which has for its base 
 one square foot, and which weighs a certain amount 
 for each cubic foot in height. 
 
 12. The temperature of the atmosphere varies at 
 different seasons of the vear. This variation causes 
 considerable increase and decrease in the ventilation 
 of mines. To illustrate this, suppose we have a mine 
 900 feet deep, what will be the ventilating pressure, 
 when the temperature in the downcast is, on an aver- 
 age, 42, and in the upcast 202, the barometer being 
 30" on an average in the two shafts, which are equal 
 in length? 
 
 Pounds. 
 
 900 cubic feet of air at 42 F. = 71.406 
 900 cubic feet of air at 202 F. = 54.126 
 
 Difference in weigbt . . .17.280 
 
 Suppose, now, the temperature of the downcast to 
 be raised to 82 F., then 
 
 Pounds. 
 
 900 cubic feet of air at 82 F. = 66.123 
 900 cubic feet of air at 202 F. = 54.126 
 
 Difference in weight . . . .11.997 
 
28 MINE VENTILATION. 12 
 
 17.280 11.997 5.283 pounds of the total pressure 
 lost by this change of temperature. As the tempera- 
 ture does not change so much as 40, in a short time it 
 will not have so marked an effect upon the ventilation 
 of mines : still, an increase of power will be required 
 during the summer months in order to keep the venti- 
 lation uniform during the year. 
 
 From the above, it may be seen that natural ventila- 
 tion may be more during the winter than during the 
 summer months. Where furnaces or steam-jets are 
 employed to produce ventilation, the longer the upcast, 
 the better; as the longer upright column of light air 
 gives rise to a brisker ventilation. For this reason, 
 furnaces should not be used in shallow pits. 
 
 When coal is worked at a dip, the effect of natural 
 ventilation is very complicated ; and in many instances 
 there will be little benefit derived therefrom at any 
 season of the year, owing to the tendency of the heated 
 air to ascend against the down current. Natural venti- 
 lation is not a help to artificial ventilation, but often is 
 of very great hinderance to a fan, on account of the 
 vacillating atmospheric changes. On this account, 
 therefore, the inlet and outlet should be as nearly as 
 practicable on the same level. High winds, directed by 
 hills, blowing against the exhaust duct of a fan, greatly 
 impede its action. 
 
13. 
 
 MINE VENTILATION. 
 
 29 
 
 TABLE III. 
 
 VELOCITY AND POWER OF WINDS (SMEATON). 
 
 Velocity. 
 Miles per hour. 
 
 Perpendicular force on 
 one square foot, in 
 pounds avoirdupois. 
 
 Common appellation of such 
 winds. 
 
 1 
 
 .005 
 
 Hardly perceptible. 
 
 4 
 
 5 
 
 .079) 
 .123 J 
 
 Gentle wind. 
 
 10 
 15 
 
 .492 / 
 1.107 f 
 
 Pleasant breeze. 
 
 20 
 25 
 
 1.968 1 
 3.075 ] 
 
 Very brisk. 
 
 30 
 35 
 
 4.429 ) 
 6.027 f 
 
 High wind. 
 
 40 
 
 7.873 
 
 Very high. 
 
 50 
 
 12.300 
 
 Storm. 
 
 60 
 
 17.715 
 
 Great storm. 
 
 80 
 
 3K490 
 
 Hurricane. 
 
 100 
 
 49.200 
 
 Violent hurricane. 
 
 CHAPTER III. 
 
 SAFETY-LAMPS. 
 
 13. IN the year 1814 Mr. Buddie, an Englishman, 
 read a paper before a society formed for preventing 
 accidents in coal-mines, illustrating the various modes 
 employed in the ventilation of collieries by plans and 
 sections. 
 
 At that time the only light used in coal-mines was 
 
30 MINE VENTILATION. 13. 
 
 the candle made of sheep or ox tallow, the latter being 
 considered the better. 
 
 When the air in the mine became mixed with inflam- 
 mable gas, the mode of determining its existence and 
 degree of inflammability was described by Mr. Buddie 
 as follows : 
 
 " In the first place the candle, called by the colliers 
 'the low,' is trimmed; that is, the liquid fat is wiped 
 off, the wick snuffed short, and carefully cleansed of red 
 cinders, so that the flame may burn as purely as possi- 
 ble. The candle, being thus prepared, is holden be- 
 tween the fingers and thumb of the one hand ; and the 
 palm of the other hand is placed between the e} r e of 
 the observer and the flame, so that nothing but the 
 spire of the flame can be seen, as it gradually towers 
 over the upper margin of the hand. The observation 
 is generally commenced near the floor of the mine, and 
 the light and hand are gently raised upwards till the 
 true state of the circulating current is ascertained. 
 The first indication of the presence of inflammable air 
 is a slight tinge of blue, a bluish-gray color, shooting 
 up from the top of the spire of the candle, and termi- 
 nating in a fine extended point. This spire increases 
 in size, and receives a deeper tinge of blue, as it rises, 
 through an increased proportion of inflammable gas, 
 till it reaches the firing-point. The experienced collier 
 
13. MINE VENTILATION. 31 
 
 knows all the gradations of shew (as it is called), and 
 seldom fires the inflammable gas, except in cases of 
 sudden discharge." 
 
 When the air was highly charged with inflammable 
 gas, the steel mill was resorted to. It consisted of a 
 steel wheel, to which was applied a piece of flint when 
 it was turned rapidly, thus throwing off a continuous 
 succession of sparks, the light of whioh was rather 
 uncertain: however, it was a substitute. But as it re- 
 quired one man to work the mill for every man cutting 
 coal, mining became too expensive ; and only those por- 
 tions of the mine were worked where a sufficient cur- 
 rent of air could be brought to bear upon the gas to 
 dilute it sufficiently to allow of candles being used. 
 
 In 1814 Dr. Clanny produced a lamp by which a 
 light could be used in an inflammable mixture of gas 
 with impunity. The insulation of the flame was accom- 
 plished by means of water ; and, although the first lamp 
 which was produced, it was too complicated and cum- 
 brous for general use. 
 
 In 1815 at the same time, but in distant localities 
 Mr. George Stephenson and Sir Humphry Davy both 
 produced lamps which insulated lights in inflammable 
 mixtures of fire-damp without exploding the gas exter- 
 nally. These productions have been of the utmost 
 importance in coal-mining, and consequently to the 
 commercial interests of the country generally. 
 
32 MINE VENTILATION. 13. 
 
 Mr. Stephenson reasoned, that "if a lamp could be 
 made to contain the burnt air above the flame, and to 
 permit the fire-damp to come in below in a small quan- 
 tity, to be burned as it came in, the burnt air would 
 prevent the passing of the explosion upwards ; and the 
 velocity of the current of the air from below would 
 also prevent it passing downwards." He accordingly 
 constructed a lamp of tin, with a hole in the bottom to 
 admit the air to the flame, and a top perforated with 
 holes. By experiments with this lamp he discovered 
 the true principles of the safety-lamp. 
 
 Sir H. Davy, at about the same time, communicated 
 with a friend that he had "discovered that explosive 
 mixtures of mine-damp will not pass through small 
 apertures or tubes, and that if a lamp or lantern be 
 made air-tight on the sides, and furnished with aper- 
 tures to admit the air, it will not communicate flame 
 to the outward atmosphere." He subsequently found 
 that "iron-wire gauze, composed of wires from one- 
 fortieth to one-sixtieth of an inch in diameter, and 
 containing twenty-eight wires, or seven hundred and 
 eighty-four apertures to the inch, was safe under all 
 circumstances." 
 
 The process by which Mr. Davy arrived at the above 
 conclusion is given by himself in a small work " On 
 the Safety-Lamp for Coal-Mines, with some Researches 
 
13. MINE VENTILATION. 33 
 
 on Flame : " " In reasoning upon the various phenom- 
 ena brought about by my various experiments, it oc- 
 curred to me, as considerable heat was required for 
 the inflammation of the fire-damp, and as it produced, in 
 burning, a comparatively small degree of heat, that 
 the effect of carbonic acid or azote, and of the sur- 
 faces of the small tubes in preventing its explosion, 
 depends upon their cooling powers, or their lowering 
 the temperature of the exploding-mixture so much that, 
 it was no longer sufficient for its continuous inflamma- 
 tion." 
 
 Mr. Stephenson's lamp has been much improved. It 
 consists of a glass cylinder above the lamp, covered by 
 a cylinder of wire gauze ; and, instead of air passing 
 through the perforated plate, it passes through the 
 meshes of the gauze (Fig. 1). 
 
 The Davy lamp differs from the Stephenson, inasmuch 
 as the former admits air through the meshes of the 
 wire on all sides : consequently, when immersed in an 
 inflammable mixture, the whole cylinder becomes filled 
 with flame, and ultimately the wires become red-hot. 
 Yet they radiate sufficient heat to keep the temperature 
 of the wires below that required for the passage of 
 flame through the meshes, and the lamp continues to 
 burn with safety if kept in a still atmosphere. 
 
 Stephenson's lamp, on the contrary, only admits air 
 
34 
 
 MINE VENTILATION. 
 
 13. 
 
 through a few meshes, the glass globe preventing the 
 entry of any air or gas from the sides : therefore only 
 a small proportion of gas can enter the interior of the 
 
 FIG. 1. 
 
 FIG. 2. 
 
 FIG. 3. 
 
 lamp : hence, never being filled with flame, the wires of 
 the gauze remain uninjured. 
 
 Upon these principles, various modifications have been 
 made to these lamps, until they now number a hundred 
 
 or more. 
 
13. 
 
 MINE VENTILATION. 
 
 The Clannj lamp consists of a cylinder of glass around 
 the flame, and a wire-gauze top. A better light is pro- 
 duced by this combination (Fig. 2). The figures show 
 the different lamps, with permutation-lock capable of 
 
 FIG. 4. 
 
 FIG. 5. 
 
 many thousand changes, so that no one but the fire-boss 
 can unlock the lamps. 
 
 The Mueseler lamp, used in Belgium, has a glass 
 cylinder for the light, and a gauze top (Fig. 4). There 
 
36 MINE VENTILATION. 13. 
 
 is a copper chimney to carry off the smoke of the burner, 
 and to force the air downward between the glass cylin- 
 der and the chimney upon the flame of the burner, 
 admitting the air through the gauze at the top. 
 
 The Boty lamp has a glass cylinder with a gauze top, 
 but the air is admitted through a perforated copper ring 
 at the bottom of the lamp. 
 
 The Eloin lamp has a glass cylinder, admitting air 
 through wire gauze near the bottom of the lamp, which 
 is thrown against the burner by a thin copper cap. No 
 other air enters the lamp, and consequently it is easily 
 extinguished. Many lamps are constructed to give in- 
 creased light by using glass globes. The Hall lamp, 
 with diaphoretic lens, is the most noteworthy, on 
 account of its construction. 
 
 The Williamson double safety-lamp is a Clanny and 
 Boty lamp combined (Fig. 5). 
 
 The illuminating power of the various lamps in most 
 common use has been given as below; the standard 
 being a wax candle, six to the pound : 
 
 Candle-power. 
 
 Davy lamp (gauze) . . . . . . . .8 
 
 Stephenson, or Georgie 1S 
 
 Upton and Roberts 24| 
 
 Clanny (glass) 4J 
 
 Parish (gauze) 2| 
 
 Mueseler's (glass) . . . . . . . 3-J 
 
 Davy (without gauze) 2 
 
14. MINE VENTILATION. 37 
 
 14. The South Shields Committee considered the 
 Davy absolutely unsafe. 
 
 Mr. Darlington came to the same conclusion, and in 
 answer to the question, " Is it not a fact that dust 
 will fly off in sparks, and that one spark would create 
 an explosion ? " said, " There are very many instances 
 of accidents taking place that we could attribute to 
 nothing else." 
 
 Experiments made by Mr. N. Wood at Killingworth 
 Colliery, in 1853, to ascertain at what velocity the flame 
 may be passed in an explosive mixture of fire-damp, 
 were as follows: 
 
 Davy lamp when moving 13' per second. 
 
 Clanny lamp went out at IT per second. 
 
 Boty lamp passed flame when moving at 15' per second. 
 
 Hall lamp did not pass flame at 13' per second. 
 
 Stephenson lamp was extinguished at less than 13' per second. 
 
 Eloin lamp went out as soon as it was filled with gas. 
 
 Upton and Roberts lamp went out as soon as it was filled with gas. 
 
 The Belgium Commission, appointed by the king in 
 1868, observed, that " the Davy and Deputy lamps, 
 when exposed for two minutes to an explosive mixture 
 of air and lighting-gas, moving at a velocity of 4.264' 
 per second, do not pass the flame through the gauze ; but, 
 when the velocity reaches or surpasses 7.38', the explo- 
 sion is, always produced on the outside, save in cases of 
 
88 MINE VENTILATION". 14. 
 
 extinction by asphyxia, caused by the admission of a 
 large quantity of gas. It was also noticed that explo- 
 sion takes place after from five to ten seconds when 
 the velocity is 9.84', and after from two to five seconds 
 when the speed is 19.68'. 
 
 " With the Mueseler lamp, out of a one hundred and 
 fifteen experiments, there were twenty-one cases of com- 
 plete extinction at a velocity of 19.68' per second. 
 
 " The Morison lamp was considered of very compli- 
 cated construction, and as giving a very bad light in 
 stagnant air. Out of eleven experiments at a velocity 
 of 19.68' per second, these lamps caused neither exte- 
 rior explosions, nor any inflammation of gas in the 
 exterior cylinder. 
 
 " Rapid currents of air are dangerous when their 
 action manifests itself by the crushing of the flame 
 upon the wicks : indeed, the relative security of the 
 Mueseler lamp does not depend alone on the smallness 
 of the section of the chimney at the top, or on its 
 height, but rests essentially in the regularity of the 
 draught." 
 
 The North of England Institute of Mining Engi- 
 neers, which has been so instrumental in the further- 
 ance of mining .knowledge, appointed a committee, who 
 rendered in their report the following concerning the 
 velocity at which the various lamps would explode : 
 
14 a. MINE VENTILATION. 89 
 
 Per second. 
 
 Davy, without shield 8' 
 
 Davy, with shield 12' 
 
 Clanny 9' 
 
 Stephenson 9' 
 
 Mueseler 8' 
 
 This rather conflicts with the Belgium Report, as 
 they claim the Mueseler lamp passes flame as easily 
 as the Davy. 
 
 14 a. Fire-damp may be detected by the aid of a 
 Davy or other safety-lamp. The following, taken from 
 the Galloway Royal Society's Journal of 1876, gives the 
 various appearances of the lamp-flame when brought 
 in contact with air mixed with fire-damp : 
 
 "The wick of the lamp, having been carefully 
 trimmed, was drawn down until the flame presented 
 the appearance of a small blue hemisphere about one- 
 eighth of an inch high, one-quarter inch diameter at 
 the base, and having a conical speck of yellow in the 
 middle near the top. 
 
 "A mixture of 1 part of marsh-gas with 16 parts of 
 air gave a voluminous waving, spindle-shaped blue cap 
 3|" high. 
 
 " 1 part of marsh-gas with 18 parts of air gave a cap 
 2" high, which burned more steadily. 
 
 " 1 part of marsh-gas with 20 parts of air gave a cap 
 
40 MINE VENTILATION. 15. 
 
 1-^g" high, with nearly parallel sides to about two-thirds 
 of its height, and then tapered to a point at the top. 
 
 "1 part of marsh-gas with 25 parts of air gave a 
 conical cap from % to " high. 
 
 "1 part of marsh-gas with 30 parts of air gave a 
 conical cap f" high. 
 
 "1 part of marsh-gas with 40 parts of air gave a 
 conical cap |" high. 
 
 "1 part of marsh-gas with 50 parts of air gave a 
 faint cap J" high, the top having the appearance of 
 having been broken off. 
 
 "With 1 part of marsh-gas and 60 parts of air, it 
 was hardly possible to distinguish any thing above the 
 small oil-flame." 
 
 CHAPTER IV. 
 
 PHYSICAL PROPERTIES OF AIR IN MOTION. 
 
 15. WIND is air in motion ; and, as air is matter, it 
 is subject to the laws which govern matter. No particle 
 of matter possesses within itself the power of changing 
 its existing state of motion or rest. When a body is at 
 rest, a force is required to put it in motion ; and, when 
 once put in motion, it would continue to move on for- 
 
15. MINE VENTILATION. 41 
 
 ever if a force of some kind were not opposed to it to 
 arrest its movement. This passive property of air is 
 called its inertia, and may be defined as opposition 
 to change, either from motion to rest, or vice versa. If 
 the air, then, had no inertia, it would not require force 
 to give it motion, nor could it require momentum. 
 The sailing of ships, the windmill, the tornado, are 
 familiar examples of the power of moving air, and, con- 
 sequently, proofs of its inertia. In order to pass air 
 through a mine, certain force must be expended ; and 
 this force is what we are now about to examine. It 
 involves a consideration of the resistances to be over- 
 come, such as area of the airways, obstructions in the 
 airways, and the friction against the walls or sides of 
 the airways. When air travels the galleries of a mine, 
 it rubs against all the exposed surfaces. This rubbing 
 gives rise to the resistance called "friction." 
 
 Friction of air in mines is so great, that, out of every 
 ten parts of power employed for the ventilation of a 
 mine, about nine of the ten are used in overcoming the 
 resistance to ventilation. As the air journeys through 
 the mines from the downcast to the upcast, it not only 
 meets the rubbing-surface, or sides, but often encoun- 
 ters short turns, brattices, etc., which adds greatly to 
 the total resistance to be overcome. 
 
 In turning sharp corners, the air strikes square 
 
42 MINE VENTILATION. 16. 
 
 against the face, and rebounds; thus hindering the 
 progress of the air following, which, in turn, goes 
 through the same operation, and hinders the air follow- 
 ing it. It is therefore preferable to have well-rounded 
 bends of large radius, as they produce little resistance 
 in comparison with elbows or square bends. The con- 
 sideration of the movements of air in mines or confined 
 passages involves its density, the area, length, and pe- 
 rimeter of the airways, also the velocity with which the 
 air travels. 
 
 16. To find the perimeter of an airway, we must add 
 together the bounding-lines. The perimeter of a square 
 airway 6' X 6' is therefore 6 + 6 + 6 + 6 = 24'. The 
 perimeter of a circle is its circumference, and is 3.1416 
 times its diameter: hence the perimeter of an airway 
 six feet in diameter is 18.8496'. The sectional area of an 
 airway is found by multiplying its height by its width. 
 Thus the area of an airway 5' X 6' is 30 square feet. 
 The rubbing-surface is found by multiplying the perime- 
 eter by the length of the airway. 
 
 Problem. What is the rubbing-surface of an airway 
 500' long, with an area of & X 6'? 
 
 Solution. 6 + 6 + 6 + 6 = 24'; then 24' X 500 = 
 12,000 square feet. Am. 
 
 As friction increases according to the rubbing-surface, 
 
18. MINE VENTILATION. 43 
 
 so will it increase or decrease according to the bounding- 
 lines or perimeter of the airway. From this it becomes 
 evident that the form which has the least perimeter 
 will have the least rubbing-surface. Above, it was 
 shown that a circular airway had less perimeter than 
 a square airway of the same diameter; and hence, if 
 the two airways have the same length, the circular will 
 have less rubbing-surface. 
 
 17. In large airways the friction will be less than in 
 smaller airways the sum of whose areas 
 
 are equal to the area of the large airway. 
 
 Let us suppose an airway twelve feet ~ 
 square in section : its area will be 144 
 
 square feet, and its perimeter 12 -{- 12 I 
 
 + 12 + 12 = 48'. 
 
 Let us now take three smaller airways, two 6' X 6' in 
 section, and one 6' X 12' in section. The aggregate areas 
 of the three airways will be 36 -j- 36 + 72 = 144 square 
 feet : the sum of the perimeters will be 24 -J- 24 + 36 
 = 84'. Hence we see, that, while the large airway has 
 the same area as the aggregated smaller airways, its 
 perimeter is much smaller than the aggregate perime- 
 ters of the lesser airways. 
 
 18. The force used to overcome the resistances 
 
44 MINE VENTILATION. la 
 
 offered to the passage of air in mines is estimated in 
 pounds to the square foot, and may be expressed as so 
 much head of air, motive-column, or water-gauge. The 
 motive-column has already been treated of, so our atten- 
 tion may be given to the water-gauge. The water- 
 gauge is an instrument used to measure the dynamic 
 force of a current of air. It consists of a U-shaped 
 tube of equal area throughout. The arms are about six 
 inches long, provided with a scale divided into inches 
 and fractional parts of an inch, so that the difference 
 between the height of the water in one arm of the tube 
 and that of the other may be measured. One arm is 
 placed in connection with the air passing in the mine, 
 while the other is open to the air away from the mine. 
 The difference in water-level will indicate the drag, or 
 the resistance to the air in the mine. In some gauges, 
 oil is substituted for water. They are made in differ- 
 ent shapes ; but the principle is the same in all. The 
 weight of one cubic foot of water at 62 F. and 30" 
 barometrical pressure is 62.32102 pounds avoirdupois: 
 62.32102 -4- 1728 = 0.036 pound is the weight of one 
 cubic inch of water. When the gauge measures one 
 inch, the pressure is 0.036 X 144 = 5.184, or 5.2 pounds 
 (nearly) to the square foot. 
 
 Example. Suppose a water-gauge read 0.4", what 
 pressure would it indicate? 
 
 0.036 x 0.4 x 144 = 2.0734 pounds to the square foot. 
 
18. MINE VENTILATION. 45 
 
 This gauge may be used to show the force of a cur- 
 rent produced by a fan or by a furnace, and hence is 
 very useful as a check to the furnace-man. As it tells 
 the amount of resistance to the air in the air-courses, 
 their state or condition may be inferred. If the pressure 
 per square foot exerted by the motive-column be known, 
 the height of the motive-column may be determined. 
 
 Problem. Suppose the temperature of the motive- 
 column be 62 F., and the water-gauge reads 0.4", what 
 is the length of such motive-column ? 
 
 Solution. 100 cubic feet of air at 62, barometer 
 30", weigh 7.629 pounds. 1 cubic foot of air at 62, 
 barometer 30", weighs 0.07629 pounds. The pressure 
 per square foot as indicated by 0.4" water-gauge is 
 0.036 X 0.4 X 144 = 2.0736 pounds. Dividing the 
 pressure per square foot by the weight of a cubic foot 
 
 2 0736 
 
 of air gives ' = 27.28' as the length of the motive- 
 column in feet. 
 
 When the height of the motive-column is known, we 
 may find the velocity of the air in feet per second 
 which the motive-column will produce. 
 
 Problem. Suppose the motive-column be 27.25' in 
 height, what velocity per second will it produce? A 
 body falling, acted "upon by gravity, would, according 
 to Eq, 2, attain a velocity represented by 8.02V/i; or 
 
46 
 
 MINE VENTILATION. 
 
 18 
 
 substituting the value of h, which in this case is 27.25', 
 we have 8.02^27.25 = 42' per second. 
 
 TABLE IV. 
 WATER-GAUGE. 
 
 
 
 Length of mo- 
 
 
 Water-gauge 
 in inches. 
 
 Pressure in pounds 
 per square foot. 
 P= 0.036 x W.G. X144. 
 
 tive-column in 
 feet at 62 F. 
 P 
 
 Velocity of the air in 
 feet per second due 
 to motive-column. 
 
 
 
 0.0763- 
 
 F-8WA. 
 
 0.1 
 
 0.5184 
 
 6.79 
 
 20.8921 
 
 0.2 
 
 1.0368 
 
 13.58 
 
 29.5938 
 
 0.3 
 
 1.5552 
 
 20.37 
 
 36.1702 
 
 0.4 
 
 2.0736 
 
 27.16 
 
 40.7416 
 
 0.5 
 
 2.5920 
 
 33.95 
 
 45.3130 
 
 0.6 
 
 3.1104 
 
 40.74 
 
 51.1676 
 
 0.7 
 
 3.6288 
 
 47.53 
 
 55.2578 
 
 0.8 
 
 4.1472 
 
 54.32 
 
 58.5460 
 
 0.9 
 
 4.6656 
 
 61.11 
 
 60.6262 
 
 1.0 
 
 5.1840 
 
 67.90 
 
 66.0046 
 
 1.1 
 
 5.7024 
 
 74.69 
 
 69.2928 
 
 1.2 
 
 6.2228 
 
 81.48 
 
 72.3404 
 
 .3 
 
 6.7392 
 
 88.27 
 
 75.2376 
 
 .4 
 
 7.2576 
 
 95.06 
 
 78.1950 
 
 .5 
 
 7.7760 
 
 101.85 
 
 80.9218 
 
 .6 
 
 8.2944 
 
 108.64 
 
 83.5684 
 
 .7 
 
 8.8128 
 
 115.43 
 
 86.0546 
 
 1.8 
 
 9.3312 
 
 122.22 
 
 88.6210 
 
 1.9 
 
 9.8496 
 
 129.01 
 
 90.7062 
 
 2.0 
 
 10.3680 
 
 135.80 
 
 93.1122 
 
 3.0 
 
 15.5520 
 
 203.70 
 
 114.3652 
 
 4.0 
 
 20.7260 
 
 271.60 
 
 132.1696 
 
 5.0 
 
 25.9200 
 
 339.50 
 
 147.9690 
 
 6.0 
 
 31.1040 
 
 407.40 
 
 161.8436 
 
 7.0 
 
 36.2880 
 
 475.30 
 
 174.8360 
 
19. MINE VENTILATION. 47 
 
 Table IV. gives the comparative height of the water- 
 gauge and air-column at a temperature of 62 F., with 
 pressure in pounds per square foot, and the theoretical 
 velocity of air due to this pressure. This table, it must 
 be remembered, is only theoretically true, on account 
 of the enormous power required to overcome friction 
 to the passage of air in an airway: hence, in prac- 
 tice, from ten to twenty times this amount of motive- 
 column is required in order to produce the theoretical 
 velocity. 
 
 19. " Co-efficient of friction " is a term used to repre- 
 sent the constant resistance met with by air during its 
 journey through the mine. This resistance must be 
 overcome at each point, before the air can pass that 
 point. It varies, of course, under different conditions ; 
 but, the smoother the rubbing-surface, the less will be 
 this resistance. This co-efficient cannot be determined 
 with any degree of certainty except by actual experi- 
 ment ; and even then experimenters differ in the exact 
 amount, because of the different conditions under which 
 the experiments were made. Sir John Atkinson, after 
 comparing the results of a number of experimenters, 
 took an average between their results, and used, as 
 the co-efficient, 0.26881 feet of air-column of the same 
 density as the flowing air. He appears to remain in 
 
48 MINE VENTILATION. J 19. 
 
 doubt whether the mere change of temperature does or 
 does not affect the co-efficient of resistance. As it is 
 now taken for granted that it is not influenced by change 
 of temperature (although it probably is), we may, for 
 a velocity of 1,000 cubic feet per minute, consider the 
 friction equal to an air-column 0.26881 feet in height, of 
 the same density as the flowing air. This air-column is 
 equal to a pressure of 0.0217 pound per square foot of 
 area of section with air at 32. 
 
 Oi2 6881 = 0.0217 pound per square foot. 
 
 459 32 
 
 When we consider the air-column, we may use the 
 co-efficient 0.26881; afterwards, if we desire, we may 
 reduce the height of the air-column thus found to 
 pounds per square foot, as above. 
 
 We may shorten this work, however, by using 0.0217 
 pound per square foot of area for every square foot' of 
 rubbing-surface exposed to the air-current, at a velocity 
 of 1,000 feet per minute, or 0.0000000217 pound for a 
 velocity of 1 foot per minute. 
 
 We must also bear in mind, that, while we use h in 
 the following formulas for the air-column which by its 
 weight will produce pressure, we use 0.0217 to find the 
 pressure, P, direct, considering all air in passing to have 
 the same co-efficient, viz., 0.0217. 
 
20. 
 
 :,IINE VENTILATION. 
 
 49 
 
 Mr. Thomas and several other writers consider this 
 co-efficient as much too large: be that as it may, we 
 can see at present no reason why it should be rejected, 
 until the experiments already referred to approach 
 more nearly to each other in their results. The co- 
 efficients in practice can never be the same in different 
 mines ; but they may approach each other by making 
 the airways as smooth, and free from obstructions, as 
 possible. 
 
 PRESSURE. 
 
 20. Some of the formulas relating to the friction 
 of air in mines, adopted by Mr. Atkinson in his book 
 on " Mine Ventilation," will be retained in this treatise, 
 so that any one studying this book will better under- 
 stand his method of reasoning. 
 
 Let h = motive-column in feet. 
 
 p = pressure per square foot due to weight of h. 
 
 a = sectional area in square feet. 
 
 Jc = co-efficient of friction = 0.0217 pounds per square 
 foot of area of section for a velocity of 1000 
 feet per minute with air at 32. It is to he 
 taken in the same terms or unit as p is taken in. 
 
 s = rubbing-surface. 
 
 v = the velocity of the air in thousandths of feet per 
 minute, 1000 feet per minute being taken as 
 the unit of velocity. 
 
50 MINE VENTILATION. 21. 
 
 The total pressure is found by the formula 
 
 (6) pa = Jcsv 12 
 
 which, expressed in words, gives us the following rule : 
 To find the total pressure due to the friction of air 
 passing through an airway, multiply the co-efficient of 
 friction by the rubbing-surface, and the product by the 
 square of the velocity ; or, pressure being known, mul- 
 tiply the pressure per square foot by the area of the 
 airway. 
 
 21. To find the pressure per square foot, 
 
 Tcsv* 
 
 (7) P= , 
 
 divide the total pressure by the area of the airway. 
 
 By the clearing of fractions, division, and other alge- 
 braical operations, we may find formulas which corre- 
 spond to rubbing-surface and velocity, and also find the 
 co-efficient of friction. These formulas embrace only 
 pressure due to friction, and not that due to the crea- 
 tion of velocity: hence they will be more correct for 
 long than for short airways. The symbols in these 
 formulas are so connected with each other, that, when 
 a sufficient number of them are known, those unknown 
 may be found. To show the application of these for- 
 
21. MINE VENTILATION. 51 
 
 mulas, suppose we have an airway 8' X T', 2,000 feet 
 long, with the air travelling at the rate of 15 feet per 
 second through it. What is the resistance due to fric- 
 tion, or the motive-column required to overcome friction 
 in the airway ? 
 
 a = 8x7 = 56 square feet. 
 & = 0.26681. 
 
 s= 8 + 8 + 74-7 = 30 x 2000 = 60000 square feet. 
 v 2 = 15 x 60 = 900' per minute, or 0.9 of 1000 feet per 
 minute, which squared is equal 0.81. 
 
 Substituting the numerical values of these symbols 
 
 iii (T), 
 
 _ 0.26881 X 60000 X 0.81 _ ^^ 
 
 56 
 
 of air-column as the pressure required to overcome the 
 friction, and produce circulation. Taking the air at 
 62 F., one cubic foot, with the barometer at 30 inches, 
 would weigh 0.0763 of a pound. If we now multiply this 
 motive-column by the weight of a cubic foot of the air 
 it is composed of, and divide the product by 5.2 pounds, 
 the pressure per square foot when the water-gauge 
 is one inch, we may find the water-gauge due to this 
 pressure, and also the pressure on each square foot. 
 
 0.0763 X 233.288 
 
 5.2 
 
 = 3.42" water-gauge, 
 
52 MINE VENTILATION. 21. 
 
 The pressure per square foot is 17.7 pounds. From 
 tliis we may obtain a formula for water-gauge. 
 
 ksv 2 
 
 The same result may be obtained by multiplying the 
 length of the motive-column by the weight of a cubic 
 foot of air of the same density, thus obtaining the 
 pressure direct without first finding the water-gauge. 
 
 The quantity of air passing may be found by multi- 
 plying the velocity in feet per minute by the area of 
 airway in square feet, or 
 
 u 
 
 (9) <} = = - 
 
 The u in the last equation represents units of work, 
 foot-pounds applied to circulate the air. 
 
 (10) u = Q X p = vpa = HP x 33000. 
 
 The HP in the last formula stands for horse-power of 
 ventilation. 
 
 u 
 
 33000 ~ 33000' 
 
22. MINE VENTILATION. 53 
 
 When we represent the length of an airway by Z, the 
 rubbing-surface by s, the perimeter by 0, we have 
 
 (12) s = o X I. 
 
 (13) - 1 = . 
 
 CHAPTER V. 
 
 THE LAWS AFFECTING AIE, IN MINES. 
 
 22. THE laws affecting the circulation of air through 
 mines or confined passages, such as gangways, etc., 
 have been ascertained principally by such eminent men 
 as Magnus, Regnault, Gay-Lussac, Daubisson, Peclet, 
 and others, and are as follows : 
 
 1. The volume assumed by a given weight of air is 
 inversely proportional to the pressure on each unit of 
 surface under which it exists, so long as the tempera- 
 ture remains unaltered. Consequently, if we take a 
 cubic foot of air under a pressure of five pounds, it will 
 only be one-half a cubic foot under a pressure of ten 
 
54 MINE VENTILATION. 22 
 
 pounds, and one-third of a cubic foot under a pressure 
 of fifteen pounds. 
 
 2. When the pressure is constant, the volume is 
 uniformly increased in the ratio of ^J^ part for each 
 additional degree of heat, Fahrenheit's scale. 
 
 3. When air is discharged through orifices offering 
 no sensible frictional resistance, the result is sixty-five 
 per cent of the quantity due to the velocity multiplied 
 by the area in case of a thin plate ; ninety-three per 
 cent in case of a short cylindrical tube ; and ninety-five 
 per cent when the tube is conical, and the area taken 
 from the small end. This contraction of the flowing 
 air, which is similar to that which takes place when 
 water is discharged through pipes under the same con- 
 ditions, has the effect of reducing the quantity dis- 
 charged in a given time below that which would be due 
 to the velocity, if it existed, over an area equal to that 
 of the orifice or tube. This contraction of the flowing 
 air is termed the " vena contracta." 
 
 4. When air is impelled through a confined passage, 
 the pressure or head of air-columri required for its pro- 
 pulsion is proportional to the square of the velocity; 
 so that to double this velocity there must be four times 
 the head ; to treble it, nine times the head ; etc. 
 
 (0) Ventilating pressure, jo, or ("head of air," or 
 "motive-column," reduced to pounds) total pressure, 
 
22. MINE VENTILATION. 55 
 
 pa or ha, and ventilating power, P, are separate and 
 distinct terms. Ventilating pressure, or simply pressure, 
 is the force applied to each square foot of area of sec- 
 tion to produce ventilation. That this pressure varies 
 as the square of the velocity, as stated above, may be 
 illustrated by the following : 
 
 Problem. When a mine is passing 20,000 cubic feet 
 of air per minute with a pressure of 2.6 pounds per 
 square foot, as indicated by 0.5-inch water-gauge, what 
 will be the pressure if the mine pass 40,000 cubic feet 
 per minute? This principle may be resolved simply 
 into finding a fourth proportional ; thus, 
 
 (20000) 2 : (40000) 2 ::p:? 
 
 (2) 2 : (4) 2 :: 2.6 : 10.4 pounds. Ans. 
 
 (5) The total pressure is the ventilating pressure, p, 
 multiplied by the area of section a of the airway in 
 square feet. Thus, if the sectional area of the above 
 airway were 64 square feet, and the pressure 0.5-inch 
 water-gauge, the total pressure would be pa = 64 X 
 2.6 166.4 pounds. 
 
 (tf) Ventilating power is power used to obtain ven- 
 tilating pressure. This power, P, varies as the cube of 
 the velocity of the air-current. By this we mean, that, 
 if we can circulate a quantity of air with 2 HP, we 
 
56 MINE VENTILATION. 22. 
 
 must use 8 HP if we wish to circulate a double quan- 
 tity. This, as can be readily seen, is a very important 
 factor in fiery mines ; as the engine working the fan or 
 the furnace may be called upon at any time to do 
 double and maybe threefold duty, in case blowers 
 or barometrical differences allow an unusual amount of 
 gas to be given off. 
 
 Problem. Suppose we have 20,000 cubic feet of air 
 passing with a water-gauge of 0.5 inches, equal to a 
 pressure of 2.6 pounds per square foot, what will be the 
 ventilating power, P, if we double the ventilation ? 
 
 Solution. 20,000 X 2.6 = units of work = 52,000 
 foot-pounds. As there are 33,000 foot-pounds in 1-horse 
 power, we have 
 
 u = 52000 p 
 
 ~ 33000 ~ 33000 ~ 
 
 Again: from 22 (a) we find that to double the quantity 
 we must employ four times the pressure : hence 
 
 P= 40000 x 2.6 X 4 = 416000 foot-pounds = u 
 and 
 
 _ __ 1 
 33000 33000 " 
 
 or eight times the power in the first case. 
 
 5. In airways of the same sectional area, the pressure 
 
22. 
 
 MINE VENTILATION. 
 
 57 
 
 required to propel air is proportional to the length of 
 the passage, or, in other words, there must be double 
 pressure for double distance. 
 
 Problem. Suppose we have an airway 2,000 feet 
 long, and another 4,000 feet long, of the same area; 
 the pressure being 2.6 pounds per square foot in the 
 shorter. What will be the pressure necessary to over- 
 come the resistance in the longer airway ? 
 
 2000: 4000:: 2.6:? 
 
 1:2:: 2.G : 5.2 pounds. Ans. 
 
 6. The pressure required to propel air through con- 
 fined passages is proportional to the perimeter of the 
 passages ; the length and other data remaining con- 
 stant. Thus, if we have an airway 4 feet square, and 
 another 8 feet square, with a pressure of 2.6 pounds 
 per square foot for the 4-foot airway, we shall have 
 5.2 pounds for the 8-foot airway, or 
 
 1:2::2.G:5.2. Ans. 
 
 7. The pressure required on each unit of surface, 
 square inch or square foot, to propel air through a con- 
 fined passage, is inversely proportional to the sectional 
 area of the passage, when all other things are equal ; 
 so that, the greater the area exposed to the pressure, 
 the less is the amount of pressure required for each 
 
58 MINE VENTILATION. 22. 
 
 unit of surface. This is of great importance in venti- 
 lation, as it allows of a greater quantity .of air passing 
 with the expenditure of less power than any other 
 means known. This principle is the one upon which 
 the splitting of air is reasoned. In the case of the 
 eight-foot and four-foot passages in (6), while the former 
 required double the amount of pressure for its double- 
 sized perimeter, that pressure would propel four times 
 the quantity: otherwise the same expenditure of power 
 on air in a four-foot passage would propel double the 
 quantity it would force through a two-foot passage, 
 or an equal quantity would be propelled by half the 
 power. The entire mass of moving air in an airway 
 may be considered as a column of water passing through 
 a pipe, exposing a certain amount of surface to resist- 
 ance, and hence requiring a fixed amount of pressure 
 acting upon its sectional area to overcome such resist- 
 ance when the velocity is constant: therefore, the 
 greater the area of section, the less the amount of 
 pressure requisite for each individual unit of such area 
 in order to make up the gross amount of such pressure 
 required. The steam-engine piston will require less 
 pressure per square inch to produce a given force as 
 the area of the piston is greater, and vice versa. Taking 
 the areas given in (6), we have the following propor- 
 tion : 
 
 64: 16:: 2.6: 0.65. Ans. 
 
23. 
 
 MINE VENTILATION. 
 
 59 
 
 8. The pressure required to overcome the frictional 
 resistances encountered by air in passing through a con- 
 fined passage has been found to vary with the nature 
 of the material composing the inner surface of the air- 
 way to which the moving air is exposed in its route, 
 as well as the mechanical state of its surface : in other 
 words, the smoother the rubbing-surface, the less the 
 resistance. 
 
 CHAPTER VI. 
 
 LAWS AFFECTING THE MOVEMENT OF AIR IN MINES, 
 CONTINUED. 
 
 23. 1. IN airways of the same sectional area, and 
 which only differ in length, " the volume and velocity 
 of air-currents are inversely proportional to the square 
 roots of the lengths." 
 
 Problem. When an airway 4' X 5' area, and length 
 of 4,000 feet, passes 20,000 cubic feet of air per minute, 
 what will another airway 1,000 feet in length, with the 
 same area and pressure, pass ? 
 
 1000 : V4000 :: 20000 : x 
 
 I : V3 :: 20000 : 40000 cubic feet. 
 
 Ans. 
 
60 MINE VENTILATION. 23. 
 
 Again : the velocity in the second airway will be 
 
 / , 20000 
 
 V/l 000:^4000::-^- :x 
 
 that is 
 
 V^I : V^I :: 1000 : a?, 
 or 
 
 1 : 2 :: 1000 : 2000' per minute. Ans. 
 
 That is, the volume and velocity in the 1,000-foot air- 
 way are twice the volume and velocity in the 4,000-foot 
 airway. 
 
 2. The volume passing through airways of similar 
 form but unequal size will be greater as the area of 
 section is greater, other data being the same ; or, the 
 pressure and other data remaining constant, the quan- 
 tity will be directly proportional to the areas : 
 
 a:A::v:V. 
 
 3. The volume passing, when areas and other data 
 are equal, is inversely proportional to the perimeter 
 of the sections of the airways. The circle passes the 
 greater quantity of two airways, one of which is a 
 square with a side equal to the diameter of the circle. 
 (See 16.) 
 
 4. The quantity or volume of air passing through an 
 airway varies as the square root of the rubbing-surface. 
 
24. 
 
 MINE VENTILATION. 
 
 61 
 
 L 
 
 5. Friction diminishes in proportion to the square 
 root of the velocity, and increases according to the 
 square of the velocity ; i.e., friction varies as the square 
 of the velocity. 
 
 6. Pressures are proportional to the squares, and the 
 powers are proportional to the cubes, of the quantities 
 of air passing through airways. 
 
 7. The quantity of air passing through airways of 
 different areas, other things being equal, is according 
 to the square root of the area multiplied by the area. 
 
 PROBLEMS TO ILLUSTRATE THE FOREGOING LAWS. 
 
 24. () If 20,000 cubic feet of air can be produced 
 in an airway of 60 feet area with a certain pressure, 
 how much air will the same pressure produce in an 
 airway of 30 feet area? 
 
 Assume the perimeters to be 32 feet for 60-foot air- 
 way, and 22 feet for 30-foot airway. Had the relation- 
 ship which existed between the perimeter and the area 
 of the larger airway been maintained in the smaller 
 airway, then the quantity of air flowing through the 
 latter would be directly proportional to its area (2), 
 pressure, etc., remaining constant. That is to say, the 
 ratio of the area to the perimeter of the larger airway is 
 as 60 to 32. In the smaller airway we have one-half the 
 area ; and, had the smaller perimeter been one-half 
 
62 MINE VENTILATION. 24. 
 
 the larger, then the ratio would have been unaltered, 
 and the quantity of air would have been one-half 
 also (3). But, instead of the smaller perimeter being 
 16 feet, it is 22 feet. Now, the problem resolves itself 
 simply into finding a fourth proportional ; and, bearing 
 in mind (4) that the quantity varies inversely as the 
 square root of the rubbing-surface, we have, 
 
 V/22 : V^Te :: 10000 cubic feet : x 
 .. x = 8528 cubic feet per minute. Ans. 
 
 In the above calculation the length of the airway 
 is taken as unity ; because any given length will be 
 a factor common to both terms of the first ratio, and 
 hence may be eliminated. 
 
 To prove this method of reasoning, we may work it 
 out according to Atkinson's method : 
 
 Taking the length of both airways as 1,000 feet, we 
 have, for the larger, 
 
 s = 32000 square feet. 
 
 20000 n _ ' 
 v = - = O.ooo 
 60 
 
 in thousandths of feet per minute. Substituting in 
 formula (7) 
 
 0-26881 x 32000 X (0.3 X 0.3) 
 
 a ~60 
 
 = 15.9295' of air-column. 
 
24. MINE VENTILATION. 63 
 
 For the smaller airway, 
 
 s = 20000, 
 and 
 
 15.9295 X 30 477.885 
 
 0.26881 X 20000 5913.82 
 
 = 0.0808082 
 
 .-. v = Y'0. 0808082 X 1000 = 284.27 feet per minute ; 
 
 and, as the quantity passing is found- by (9), 21, we 
 have 284.27' X 30 = 8528 cubic feet per minute. 
 
 Problem (>). Suppose, now, we take two airways 
 whose lengths are each 35 units, and which have the 
 same area ; the quantity of air passing through each 
 being 9,000 cubic feet. What will each circulate of the 
 total amount, if their lengths be in the ratio of 3 to 4 ? 
 
 Solution. From (1) and (4), 23, we deduce two 
 proportions, one for the longer, and one for the shorter 
 airway. Now, if these airways were in the ratio of 3 
 to 4 in length, then one would ,be 30 units and the 
 other 40 units in length, and the quantities of air which 
 would flow through them under the same conditions 
 may be computed thus : 
 
 For the longer airway 
 
 V/40:\/35:: 9000 : x 
 or 
 
 and 
 
 8 : ^56 : : 9000 : 8418. Ans. 
 
64 MINE VENTILATION. 24. 
 
 For the shorter airway 
 
 : ^35 :: 9000 : x, or 06 : ^7 :: 9000 : x 
 
 and hence 
 
 G : V^42 :: 9000 : 9721 cubic feet. Ans. 
 Total, 
 
 8418 + 9721 = 18139 cubic feet. 
 Proof, 
 
 03:^:: 8418: 9721 
 V/4:V^3:: 9721: 8418. 
 
 (e) Suppose we have two airways of the same sec- 
 tional areas and lengths, each passing 9,000 cubic feet 
 as before. Suppose each to have 4 units of lengths. If 
 one of these airways be shortened to unity, it will have 
 but J the rubbing-surface of its former length ; and the 
 volume of air will be, according to (1), found thus : 
 
 VI: 0::9000: 18000. 
 
 Again : let the length of one of the airways be in- 
 creased fourfold, then the volume of air will have four 
 times the rubbing-surface, and by (4) we have 
 
 VTG:V / 4::9000: 4500. 
 
 (The above illustrates in a striking manner the effect 
 that rubbing-surface has of diminishing the flow of air 
 through a gallery.) 
 
24. MINE VENTILATION. 
 
 The total volume will be 22,500 cubic feet ; and, not- 
 withstanding the rubbing-surface is more than doubled, 
 the volume is only increased by twenty-five per cent. 
 The pressure required to circulate the air under each 
 set of conditions is precisely the same ; for the smaller 
 rubbing-surface multiplied by the square of the highest 
 velocity is equal to the greater rubbing-surface mul- 
 tiplied by the square of the lower velocity ; thus 
 /9000\ 2 * onocnn A /4500\ 2 onoKAA 
 
 (w) x 4 = 202500 ' and (-W) x 16 = 202500 ' and 
 
 f - - j X 1 = 202500, if we assume the areas of the 
 
 above to be 40 square feet. 
 
 That the pressure remains the same may be shown 
 by Atkinson's method : 
 
 Let the above unit of length be assumed as 100 feet, 
 then equal airways are 400 feet in length ; and, if we 
 assume the area and perimeter to be respectively 25 
 and 20 feet, we may find the pressure, thus : 
 
 n . , 0.26881 x 400 X 20 X 0.1296 
 
 (1) h = - = 11.148 ft. head. 
 
 , v 7 0.26881 x 100 x 20 x 0.5184 
 
 (2) h = - -= 11.148 ft. head. 
 
 Zo 
 
 ,^ , 0.26881 x 1600 X 20 x 0.0324 
 
 (3) h = - -= 11.148ft. head. 
 
66 MINE VENTILATION. 24. 
 
 (c?) If, through two airways 6 feet square, 9,000 
 cubic feet of air flow per minute, and one of them be 
 altered in section to a circle (its area being unaltered), 
 then the quantity of air circulating may be computed, 
 thus : 
 
 V21.27 : Y^24 :: 9000 : 95GO. Ans. 
 
 The volume flowing through both airways would now 
 be 18,560 cubic feet ; but, in the event of this quantity 
 being reduced to 18,000 cubic feet, the circular airway 
 would have more flowing through it than the other. 
 
 (e) What volume of air would flow through an air- 
 way 5 feet square, if 6,000 cubic feet flow through an 
 airway 10 feet square, the pressure and length being 
 the same? 
 
 Solution. The volume varies as the square root of 
 the rubbing-surface ( 23, 4), and directly as the area 
 ( 23, 2) : hence we have a compound proportion, 
 
 SI'S-"-- 
 
 or 
 
 V/20 x 25 X 6000 
 
 x = - -f= - =1061 cubic feet. Ans. 
 V40 x 100 
 
 It may be reasoned thus: as the area was reduced one- 
 fourth, the resulting volume would be one-fourth also, 
 
25. MINE VENTILATION. 67 
 
 namely, 1,500 cubic feet ; but, instead of the perimeter 
 being reduced to one-fourth, that is, 10 feet, it is only 
 reduced to 20 feet. The volume may now be found, 
 thus : 
 
 or 
 
 V/2 : V^T : : 1500 : 1061 cubic feat. Ans. 
 
 (h) Suppose we have a pressure equivalent to 40 HP, 
 giving a circulation of 120,000 cubic feet per minute: 
 what quantity will a pressure equivalent to 32 HP 
 give ? From 23, 6, we have 
 
 ^40 : V32 : : 120000 : 111398 cu. ft. per minute. Ans. 
 
 Proof. (111398) 3 : (120000) 3 : : 32 : 40. Ans. 
 
 (i) Suppose we have a pressure equivalent to 32 
 pounds per square foot, circulating 107,350 cubic feet 
 per minute, what pressure will circulate 120,000 cubic 
 feet? 
 
 Solution. J107350)2 : (120000) 2 : : 32 : 40. Ans. 
 
 Proof. ^40:^32:: 120000 : 107350. Ans. 
 
 25. From the proof of the last problem we see that 
 air may be measured by the pressure, or, what amounts 
 to the same, the water-gauge, and we can say the quan- 
 
68 
 
 MINE VENTILATION. 
 
 25. 
 
 tity of air passing in a mine is according to the square 
 root of the water-gauge. 
 
 Problem. Suppose we have 30,000 cubic feet of air 
 passing when the water-gauge is 1.6 inches, what quan- 
 tity will pass with 2.5 inches of water-gauge ? 
 
 or 
 
 : : 30000 : x 
 
 1.2649 : 1.5811 : : 30000 : 37500 (nearly) cubic feet. 
 TABLE Y. 
 
 SQUARE ROOT OF WATER-GAUGE. 
 
 W. G. 
 
 JW.G. 
 
 W.G. 
 
 ^W.G. 
 
 W.G. 
 
 ^W.G. 
 
 0.1 
 
 0.3162 
 
 .2 
 
 1.0954 
 
 2.3 
 
 1.5165 
 
 0.2 
 
 0.4474 
 
 .3 
 
 1.1401 
 
 2.4 
 
 1.5491 
 
 0.3 
 
 0.5477 
 
 .4 
 
 1.1832 
 
 2.5 
 
 1.5811 
 
 0.4 
 
 0.6324 
 
 .5 
 
 1.2247 
 
 2.6 
 
 1.6144 
 
 0.5 
 
 0.7071 
 
 .6 
 
 1.2649 
 
 2.7 
 
 1.6431 
 
 0.6 
 
 0.7745 
 
 .7 
 
 1.3038 
 
 2.8 
 
 1.6733 
 
 0.7 
 
 0.8366 
 
 .8 
 
 1.3416 
 
 2.9 
 
 1.7029 
 
 0.8 
 
 0.8944 
 
 .9 
 
 1.3784 
 
 3.0 
 
 1.7320 
 
 0.9 
 
 0.9486 
 
 2.0 
 
 1.4142 
 
 3.5 
 
 1.8460 
 
 1.0 
 
 1.0000 
 
 2.1 
 
 1.4491 
 
 4.0 
 
 2.0000 
 
 1.1 
 
 1.0488 
 
 2.2 
 
 1.4832 
 
 4.5 
 
 2.1213 
 
26. MINE VENTILATION. 69 
 
 CHAPTER VII. 
 
 VENTILATION OF SINGLE PITS OR DRIFTS. 
 
 26. DURING the sinking of shafts, or driving of drifts, 
 the ventilation is caused by the diffusion of gases, and 
 by the temperature of the atmosphere or outer air and 
 that of the mine. It can hence only be temporary, 
 becoming insufficient as soon as certain variable and 
 often very small depth is attained, unless recourse be 
 had to some other means. The simplest mode of 
 attaining this end consists in dividing the pit by a 
 wooden brattice, so that the warm air may ascend one 
 side, while the cool air will descend the other. If 
 this does not produce circulation, it can generally be 
 attained by connecting one side of the brattice with 
 a high chimney, which, by establishing a difference 
 between the levels of the orifices, causes a natural 
 circulation of air. If compressed air or steam be used 
 for drills, or if pumps be suspended in the pit, the 
 chimney will be unnecessary. A fire may be placed at 
 the bottom of the pit to warm the air on one side the 
 brattice, or a small hand centrifugal fan be employed 
 to advantage. In drifts, the brattice is placed parallel 
 to the axis, and disposed in a horizontal or vertical 
 
70 MINE VENTILATION. 26. 
 
 plane as better suits the case. When placed in the 
 vertical plane, one of the compartments may be used 
 as a tramway and intake for the air : the other, com- 
 municating with the upcast pit, is used entirely as a 
 return. When, a horizontal brattice is used, it may be 
 at the feet or head of the workmen. 
 
 In this case the brattice is used to facilitate the 
 ventilation of drifts, and also the driving and sink- 
 ing of internal drifts, by putting the airway one side 
 of the brattice in communication with the downcast. 
 Within the last fifteen years, miners have superseded 
 this method, wherever practicable, by "brattice-cloth" 
 nailed to a series of props. The cloth is made imperme- 
 able to the air by being covered with tar, or dipped in a 
 solution of soda silicate. Treated in the latter manner, 
 it is rendered incombustible, as well as impermeable to 
 the air. Brattice-cloth is only used to secure temporary 
 ventilation, and should. never be permitted, except at 
 the face, or where it is subjected to constant scrutiny, as 
 it may decay ; and inattention to its repair or renewal 
 might cause serious accidents. Another method of 
 conducting air into drifts is by a continuous wooden 
 box. This box may be placed in any position where 
 it will be out of the way, with one of its extremities 
 connected with a chimney, if it be driven from the day ; 
 or with the return airway, if the sinking or drift be 
 
26. MINE VENTILATION. 71 
 
 made in the mine. Air-boxes, whose use is consistent 
 with economy, if of a great length, will not supply 
 sufficient volume of air, owing to the great absorption 
 of the " motive-column " by friction. Tubes are made 
 of other materials than wood, such as zinc, canvas, and 
 paper ; but they have never come into great demand. 
 These air-boxes or tubes may be used to convey fresh 
 air to the face of the workings, or return the foul air. 
 It is preferable to employ them for the first method, 
 rather than for the second; for more air is thrown 
 upon the face of the workings, because, when suction 
 is employed, the air will leak through the box before 
 it reaches the mouth of the box at the upcast, also the 
 contraction of the air-vein at the entry of the box must 
 be greater in the suction than in the forcing principle. 
 
 Again : the air will be purer when delivered to the 
 face fresh from the day, for by suction it must neces- 
 sarily bring to the face gases and foul air met with 
 along fts route. It is also evident that the diffusion of 
 fire-damp by the mechanical action of the air will be 
 better by the forcing-system. When the excavation 
 has attained the extreme point where air-boxes and 
 brattice act with sufficiency, we must replace these 
 modes of ventilation (purely temporary) by other more 
 perfect means, and, above all, not employ air-boxes in 
 order to drive winning-places, because the ventilation 
 
72 MINE VENTILATION. 27. 
 
 would be insufficient, owing to the length which would 
 be required ; and impure air would injure the miner's 
 health. 
 
 Again : should an explosion take place, the boxes 
 would be destroyed, ventilation stopped, and the after- 
 damp would spread through the workings, and cut off 
 all chance of escape to the uninjured, and all hope of 
 relief to the injured. As soon as the shaft wins the 
 coal, it should be connected with a neighboring shaft, 
 so as to produce a regular and continuous circulation 
 of air. This is usually effected by driving two ways, 
 forming a single conduit with two sides of the pit, so 
 that the air must pass around the face of the drift. 
 Sometimes a single drift is driven, divided by a brattice ; 
 sometimes two parallel drifts, separated by a wall of 
 coal, cut through or holed at equal distances by cross- 
 drifts or stentings, which are afterwards closed up, only 
 leaving the one nearest the face open. After communi- 
 cation is made, the brattice should be removed. * 
 
 MIXES WITH TWO ORIFICES. 
 
 27. A colliery, which, over a small area, has many 
 openings to the day of great sectional area but of little 
 length, requires little or no mechanical ventilation. 
 When the pits are less numerous, and the galleries are 
 longer, we should exercise great care in the distribution 
 
28. MINE VENTILATION. 73 
 
 of the air-current. Formerly all the galleries were 
 united so as to form one long and sinuous airway, of 
 which each extremity emptied into the atmosphere 
 directly, or into the pits. The air descended one of 
 these, traversing its whole length, and finally ascended 
 the upcast shaft. Places were stowed, and doors erect- 
 ed, so as to direct the air-current at various places. The 
 inconveniences of this system arose* from the length of 
 the air-course, which became so much more as the mine 
 developed, and which by the friction diminished the 
 volume of air. The current in some part of the mine 
 is pretty sure to meet with gases of some nature or 
 other, so that, if they be mephitic, the air will pass over 
 the workmen in the return, and injure their health ; 
 and, if the air has acquired sufficient inflammable gas, 
 the same workmen may explode it with their lamps. 
 In two collieries alone, where this system of ventilation 
 was adopted (Lundhill and Risca), three hundred and 
 twenty-nine lives were lost. The tendency of a current 
 of air is naturally to choose, in passing from point to 
 point, the nearest route, and that which has the largest 
 section. If allowed to pursue its own course, the air 
 will not always be renewed in galleries which require it. 
 
 28. To overcome this difficulty, doors and regulators 
 are employed ; the former to conduct the air where it 
 
74 MINE VENTILATION. 2a 
 
 is needed, the latter to cause a diminution of the vol- 
 ume of air in certain portions of the mine where only 
 a portion of the current is needed. Should permanent 
 stoppings be required for old ways or abandoned pas- 
 sages, they may consist of solid masonry, tightly stowed, 
 so as to leave no passage for a single thread of air : en 
 the contrary, they must be movable if the trams and 
 men pass along the gallery. For this purpose, recourse 
 is had to doors, which are usually placed in pairs, but 
 so far apart that one may be shut before the other is 
 opened. Regulators are employed to prevent more 
 than a required quantity of air from passing into 
 certain districts, and to cause the excess to pass into 
 other parts of the mine. They are simply sliding- 
 doors, whose open area may be increased or diminished 
 as required by circumstances, and which can be locked 
 fast at any area, the key, of course, being retained by 
 the boss. 
 
 (a) To illustrate these regulators, let us assume an 
 airway 5' X 5' passing 10,000 cubic feet of air per min- 
 ute : a regulator is put in, which contracts it to 20-foot 
 area. Find the quantity of air that will pass, power 
 and pressure remaining the same. 
 
 From 23, 5, we find that " the resistance increases 
 as the square of the velocity of the air-current," also 
 we know that sudden contraction of an airway will 
 
28. MINE VENTILATION. 75 
 
 cause diminution of the discharge; then, according to 
 23, 7, we have 
 
 V^25 X 25 : ^20 X 20 : : 10000 : 7152 cubic feet. Am. 
 
 (5) As we have regulated the discharge, and dimin- 
 ished the quantity, we may increase the discharge by 
 enlarging the airway. 
 
 Problem. What volume of air Would flow through 
 an airway 10 feet square, when 6,000 cubic feet per 
 minute flow through an airway 5 feet square, the press- 
 ure and length being the same ? 
 
 600 < *> or - = 33840. Ans. 
 
 o: V20 x 25 
 
 In the above case the area was enlarged four times. 
 The resulting volume would have been increased four 
 times also, viz., 24,000 cubic feet, had it not been that 
 the perimeter only increased to 40 feet instead of four 
 times its former size, or 80 feet. The volume may be 
 found thus : 
 
 V/80 : ^40 : : 24000 : 33840 cubic feet. Ans. 
 
76 MINE VENTILATION. 29. 
 
 CHAPTER VIII. 
 
 SPLITTING THE AIR-CURRENT. BUBBLE'S METHOD. 
 
 29. THE splitting of the air-current of a mine, when 
 not carried to extremes, is very advantageous, as it 
 secures a greater volume of air at the expense of the 
 same motive-power. The different divisions of a mine 
 are never equally developed; and, if proper care be not 
 taken, districts requiring the most air will receive only 
 a small portion, while other districts requiring but little 
 will receive large quantities. Common sense suggests, 
 that, of two developed districts of a mine, the more 
 developed of the two should receive the larger quantity 
 of air: the air should therefore be distributed in a sys- 
 tematic manner, basing the quantities for each district 
 on to the number of bends, extent of rubbing-surface, 
 and other resistances. This aim is attained, as men- 
 tioned above, by the "sliding shutter," which, being 
 placed so as to admit a small volume of air, causes 
 whatever excess there may be to pass into other parts 
 of the mine where the air is more needed. 
 
 It may happen that a u blower" of gas is met with, 
 which renders the air explosive in its district. When 
 it is perceived, the regulators should be immediately 
 
30. MINE VENTILATION. 77 
 
 opened, and a greater circulation produced, in order to 
 carry away the inflammable gas. During this time 
 work in the other districts need not necessarily be 
 stopped, unless it is found necessary to pass the whole 
 current through the dangerous district. 
 
 If the gases be given off in such quantities that an 
 explosion takes place before the miner perceives the 
 explosive state of the air, the workmen in the other 
 districts will be protected from the flame of the ex- 
 plosion, and the " after-damp " will only momentarily 
 check the current; and, if the return airways are of 
 large sectional area and no great length, the current 
 will scarcely be interrupted, save, perhaps, in the dis- 
 trict where the explosion occurred, the doors and regu- 
 lators of which have been destroyed. Where gas is 
 given off at several points in a mine, ventilated by a 
 single current, the aggregate amount may be suffi- 
 cient to render the current explosive, and cause an ac- 
 cident. 
 
 30. Either to increase the ventilating pressure, or to 
 lessen the extent of rubbing-surface exposed to the air 
 circulating in mines, is a very slow and costly manner 
 of increasing the amount of ventilation ; but by judi- 
 ciously dividing the current, and leading it into several 
 airways, the circulation will be much more active than 
 
78 MINE VENTILATION. 30. 
 
 if only one continuous current were used. Let us, as 
 an illustration, assume a mine divided into four equally 
 developed districts of the same area ; and also the same 
 mine arranged so as to form one continuous airway, 
 whose length will be four times greater than that of 
 one of the districts. Let a =. area, p = perimeter, 
 I = length, and Q =. quantity of air circulating; then 
 we have, as the value of the friction of the air, 
 
 plv*_pl Q* 
 
 v 
 
 a a a* 
 
 multiplied by a co-efficient to be determined by experi- 
 ment. In the first case, the airways may be considered 
 as a single airway, with a length /, a section 4a, and a 
 perimeter 4p : the equation then becomes 
 
 Secondly, the area and perimeter being a and /?, the 
 length will be 4Z, whose " drag " or resistances due to 
 friction, are expressed by 
 
 On dividing equation (a) by (b) we find (b) is -^ 
 of equation (a), i.e., the friction of (a) is ^ that of 
 
31. MINE VENTILATION. 79 
 
 (b) ; or we may say "that the resistance to the motion 
 of the air in a mine requires in a single current a 
 motive-force sixty-four times greater than when the 
 air is divided into four currents of the same sectional 
 area and aggregate length. 
 
 The same is true for bends and contractions that 
 require a motive-force equal to the -square of the vol- 
 ume of air circulating in each district. Thus, in the 
 
 first case, the volume of air was -^ the motive-force 
 
 4 
 
 Q2 
 
 required to overcome this resistance m X ^ ; m being 
 
 a numerical co-efficient depending upon the number of 
 bends or strictures. 
 
 In the second case, the volume Q must be multiplied 
 by a co-efficient, which, owing to the quadruple length 
 of the airway, must be equal to the sum of the four 
 co-efficients of each district, or 4m Q\ a value sixty-four 
 times the first. 
 
 31. By splitting the air-current, or leading it off from 
 the downcast into the different districts to be venti- 
 lated, we have two decided advantages over the old 
 method. In the first place, we obtain purer air for each 
 district ; for each split takes its fresh air directly from 
 the downcast. 
 
80 MINE VENTILATION. 31. 
 
 In the next place, we obtain more air by decreasing 
 the velocity. As the friction increases as the square 
 of the velocity, we lessen the friction by lessening the 
 velocity, and using the same power : we also decrease 
 the cost of ventilation more than by any known means 
 as yet. Were it not for the resistances of the shafts, 
 the results of splitting the air would be easily calcu- 
 lated. 
 
 Problem. To show the effect of splitting, without 
 considering the shaft resistances: suppose we have a 
 mine circulating 18,000 cubic feet per minute, and that 
 the area of the gallery is 25 feet, the length 1,000 feet. 
 What amount of air will circulate when the current is 
 split into two, three, four, and five equal divisions, the 
 pressure remaining constant? 
 
 The effect of splitting into two, three, four, and five 
 equal air-courses will be to double, treble, etc., the areas 
 without altering the rubbing-surface, because the area 
 after splitting is two, three, etc., times that of the ori- 
 ginal airway, although the rubbing-surface remains the 
 same ; and as the quantity may be found by the formula 
 
 (x) 9 
 
 we may substitute the values of the symbols, and find 
 the quantities of the various splits under consideration. 
 
31. MINE VENTILATION. 81 
 
 Since, however, in the above formula, p, &, and s remain 
 constant, and a varies, we may simplify the work by 
 eliminating them, and use ^a X a = q, which corre- 
 sponds to one of our former laws ; viz., " that the rela- 
 tive quantities will be according to the square root of 
 the area multiplied by the area, and then multiplied by 
 the original quantity flowing through the mine." The 
 pressure may be found thus : 
 
 ksv* 0.0217 X 20000 x (0.72) 2 
 p= - - = -r^~ = 8.999 pounds. 
 
 tt ZO 
 
 Using now formula (x) 
 
 9 x 50 
 g= V n.0000000217 x 20000 X 50 = 5091 
 
 9 x 75 
 q = ^ 0.0000000217 x 20000 X 75 = 93525 
 
 9 x 100 
 * = V 0.0000000217X20000 X 10 = 1440 
 
 9 X 125 X 125 = 200070. 
 
 1.0000000217 X 20000 
 
 The question may be worked, without reference to 
 the actual dimensions of the areas and rubbing-surfaces, 
 thus : 
 
82 MINE VENTILATION. 31. 
 
 V/T X 1:^2 X 2:: 18000: 50910 
 V^T X 1:^3 X 3:: 1.8000:93528 
 V^l X 1 : fi X 4 :: 18000 : 144000 
 VI X 1 : fi X 5 :: 18000 : 200070. 
 
 The difference between the two calculations is owing 
 to the treatment of the decimals, and assuming the 
 pressure more than it really is. 
 
 (>) There is a difference between splitting the air, 
 and adding an air-course of the same length and area. 
 In the above example the area was doubled while the 
 length remained unchanged ; but, if we were to add an 
 air-course of the same length and area, we would double 
 the rubbing-surface and the area. In fact, we cannot 
 call such an arrangement a split ; for, if both received 
 an equal volume of air, they would both have the same 
 pressure ; but that pressure would only be a small part 
 of what it was in the above example, first case, on 
 account of the increased area: therefore, instead of 
 increasing the quantity of air, we diminish it. 
 
 To illustrate this let a = 25 feet, s 24,000 feet in 
 an airway passing 15,000 cubic feet per minute: add 
 an airway of the same length and area, what quantity 
 will flow through each? Ans. 22,900 cubic feet. 
 
 The units of power necessary to circulate the above 
 quantity may be found by multiplying the pressure by 
 the quantity of air circulating per minute. 
 
31. MINE VENTILATION. 83 
 
 Jesv* ~ ~ 
 
 (z) u = x Q = p x Q. 
 
 With an additional airway of the same length, a and 
 s will be doubled ; and, as the velocity decreases as the 
 cube root of the power, we have the formula 
 
 to obtain the quantity of air in cubic feet circulating 
 per minute. 
 
 (<?) When we have splits of different lengths, and 
 wish to know the size of regulators so as to allow the 
 same quantity of air to each division, we may find them 
 when we know the size of the first regulator. 
 
 Problem. Suppose we have five different splits in 
 a mine, 200, 300, 400, 700, and 800 yards long respec- 
 tively, and the regulator placed at the entrance of the 
 200 yards' airway be 9 square feet. What will be 
 the area of the other regulators so as to allow the same 
 quantity of air to each split ? 
 
 V300-T- V 200 = 1-22404. 
 y/400-f- ^200 = 1.41421. 
 y/TOO-j. 0200= 1.87083. 
 V800 -h- 0^00 = 2.00000. 
 
84 MINE VENTILATION. 31. 
 
 This gives us the rate at which the friction increases 
 when compared with the first regulator ; and hence, if 
 we multiply each of the above quotients by 9 respec- 
 tively, it will give us the area of the required regula- 
 tors, thus : 
 
 1.22404 x 9 = 11.0' 
 1.41421 x 9 = 12.7' 
 1.87083 x 9 = 16.8' 
 2.00000 X 9 = 18'. 
 
 (d) Again : if we wish to divide a given quantity of 
 air so that it will be distributed, as it is needed, into 
 unequal quantities in different divisions of the mine, 
 we may do so in the following simple manner. 
 
 Problem. Suppose we have 50,000 cubic feet of air 
 to be distributed in five divisions, each to obtain respec- 
 tively 15,000, 12,000, 10,000, 7,000, and 6,000 cubic feet 
 per minute, to travel at a velocity of 5 feet per second ; 
 which velocity is sufficient to render any discharge of 
 fire-damp harmless, unless it happens to be a very excep- 
 tional case. 
 
 Taking the first case as an example, 15,000 cubic feet 
 to be distributed at a velocity of 5 feet per second, 
 
 5' x 60 300' per minute, 1 ^^ = 50 feet area, and 
 
 oOO 
 
 y/50 = 7.07 feet, size of the regulator necessary for 
 
32. MINE VENTILATION. 85 
 
 the first split. Proceeding in the same manner, the 
 regulators to admit the above quantities of air may be 
 found. 
 
 32. Airways are seldom of the same area in the same 
 mine, but are subject to the same pressure in ventila- 
 tion ; and, as each airway takes up its part of the press- 
 ure to overcome the resistances which the air encounters 
 while passing through it, we may find the pressure 
 necessary to overcome the resistances of the whole mine 
 by adding the several pressures, or the pressure for each 
 airway, together. If a mine be ventilated by a number 
 of airways of different areas and lengths, they must all 
 be considered as subject to one common pressure, and 
 the quantity of air passing in each may be found by the 
 formula, 
 
 This is derived from the formula q = v T- X ? in which 
 
 * ks 
 
 k and p are common factors for each airway, and hence 
 need not be considered. 
 
 Problem. Suppose we have three airways, A, B, 
 and C. A has an area of 30 square feet, and a rubbing- 
 surface of 66,000 feet. B has an area of 36 square feet, 
 
86 MINE VENTILATION. 33. 
 
 and a rubbing-surface of 96,000 feet. C has an area of 
 25 square feet, and a rubbing-surface of 40,000 feet. 
 What quantity of air will pass along each, if the total 
 quantity passing be 50,000 cubic feet per minute ? 
 
 For the sake of brevity, the rubbing-surfaces may be 
 reduced to the lowest whole numbers, and still remain 
 in the same proportion to each other by dividing by 
 2,000; then 
 
 A = Vli X 30 = 28.602 
 
 x 36 = 31.176 
 C = Vfj X 25 = 27.950 
 Total . . . 87.728 
 
 The proportional part passing in each airway may 
 now be found from the simple proportions : 
 
 A = 87.728 : 28.602 :: 50000 : 16301.5 cubic feet. 
 B = 87.728 : 31.176 :: 50000 : 17768.5 cubic feet. 
 C = 87.728 : 27.950 :: 50000 : 15930.0 cubic feet. 
 
 33. Find the quantity of air which will pass through 
 a mine of the dimensions as given in the following table, 
 with a total pressure of six pounds per square foot. 
 In this case, the upcast and downcast shafts are given. 
 A, B, C, and D are splits, subject to the same pressure. 
 We may assume any quantity of air we please say, 
 
33. 
 
 MINE VENTILATION. 
 
 87 
 
 50,000 cubic feet to pass through each division, and 
 then find the actual quantity which will pass under 
 six pounds' pressure. 
 
 Before we can do this, however, we must calculate 
 the pressure for the circulation of 50,000 cubic feet; 
 then, by adding the several pressures together, place 
 them in proportion, as shown in column vni. of the table. 
 
 TABLE VI. 
 
 
 i. 
 
 II. 
 
 in. 
 
 IV. 
 
 V. 
 
 VI. 
 
 VII. 
 
 VIII. 
 
 IX. 
 
 
 
 
 
 
 
 
 
 ; 
 
 i 
 
 
 
 
 
 8 
 
 
 >i ' 
 
 
 
 p >|Z* * 
 
 ^^ 
 
 
 
 
 
 1 
 
 . 
 
 
 S* 
 
 o^ 
 
 5 P x 
 
 
 
 
 o 
 
 3 
 00 
 
 bo 
 
 X 
 
 *1^ 
 
 ^.s| 
 
 =3^1 
 
 ^^S 
 
 M'-i* 
 
 
 N 
 
 t 
 
 a 
 
 3 
 
 ,0 
 
 3 
 
 
 ||| 
 
 ii * 
 
 111 
 
 a "o || 
 SS ex 
 
 o 
 
 
 QQ 
 
 * 
 
 PI 
 
 tf 
 
 
 
 
 * 
 
 <5 
 
 
 Upcast . 
 
 9X8 
 
 72 
 
 34 
 
 17000 
 
 
 50000 
 
 2.470 
 
 1.78 
 
 42400 
 
 Downcast 
 
 8X8 
 
 64 
 
 32 
 
 16000 
 
 
 
 50000 
 
 3.316 
 
 2.40 
 
 42400 
 
 A ... 
 
 7X7 
 
 49 
 
 28 
 
 42000 
 
 74.848 
 
 18115.51 
 
 
 
 15412 
 
 B . . . 
 C . . . 
 
 8X4 
 5X6 
 
 32 
 30 
 
 24 
 
 22 
 
 36000 
 22000 
 
 42.666 
 49.543 
 
 10326.5 1 
 
 2.542 
 
 1.82 
 
 8737 
 10146 
 
 D . . . 
 
 5X5 
 
 25 
 
 20 
 
 20000 
 
 39.528 
 
 9567 J 
 
 
 
 8105 
 
 Next, by the use of the formula q = y ^- X , we may 
 obtain the actual quantities. Columns vi. and vn. are 
 
88 MINE VENTILATION. 34. 
 
 obtained as shown by 32. The pressure passing 50,000 
 cubic feet, we find aggregates 8.328 pounds ; then 
 
 V8.328 : 05 :: 50000 : 42400 cubic feet 
 the actual quantity, as is shown by the table. 
 
 CHAPTER IX. 
 
 34. As yet no rule has been established as to the 
 quantity of air necessary for ventilating mines of dif- 
 ferent capacities: consequently, sometimes as much 
 air is sent into a mine employing two hundred persons 
 as there is into one in which twice that number are 
 constantly engaged. 
 
 Scientifically ventilated mines contain a certain allow- 
 ance of air for each person working under ground, as 
 well as for each light and horse ; also for various other 
 purposes. Some persons think they can determine in 
 a general manner the volume of air necessary for a mine, 
 basing it upon the following single element, the num- 
 ber of miners employed, and giving to them a greater 
 or less volume of air, varying with the presence or 
 absence of fire-damp. Let us see if this be correct, and, 
 to do so, assume that each workingman, exclusive of 
 
34. MINE VENTILATION. 89 
 
 horses and lights, requires one hundred cubic feet per 
 minute, taking as examples two mines equally de- 
 veloped, although, by reason of the nature of the coal- 
 seam and the mode of working, the tonnage hewn by 
 each man may be different, and only require sixty men 
 in the first mine, whilst the second requires a hundred 
 and fifty men. 
 
 The first, we will say, is from necessity wrought in 
 two workings 6' X 5'. The volume per man being 100 
 cubic feet, the total volume required is 6,000 cubic feet 
 per minute, which, divided by the area, 30 -(- 30 = 60 
 square feet, gives 100 feet per minute as the velocity of 
 the air. In the second case, one airway is required with 
 an area of 8' X & = 40 square feet. The total volume 
 circulating will be 100 X 150 = 15,000. cubic feet per 
 minute, and the velocity will be 377.5 feet per minute. 
 The first velocity will be insufficient to sweep away the 
 gas, and prevent the heating of the air ; while the other 
 is too great, and would incommode the workmen. Thus 
 a volume of air exclusively founded on the number of 
 men employed is incomplete. The extreme limits of 
 velocity which largely regulate the temperature, and 
 indirectly the capacity of the air for water-vapor must 
 be fixed. To do this, a record of the development of 
 the working ; the method of working ; the nature of the 
 seam ; the splits, if any, or, if not, the main current ; and 
 
90 MINE VENTILATION. 34. 
 
 the more or less abundant production of gases, must 
 be kept, as it is impossible to fix in a lump otherwise 
 the volume of air necessary for a fiery mine, where the 
 evolution varies in such great limits. On account of 
 the great complication of such calculations, no general 
 system can be established. " It appears, under the cir- 
 cumstances, to be indispensable to proceed by analogy, 
 by classing mines according to the more or less favora- 
 ble conditions for ventilation in which they are situated, 
 and to form groups, to the members of which a single 
 and absolute rule can be applied." 
 
 In some mines, of course, more air is required than 
 in others ; but, for sanitary purposes alone, 120 feet per 
 minute is quoted as the minimum for each man and 
 boy ; but, where gas is given off, twice that amount 
 should be allowed. No person should be allowed to 
 work in a stagnant atmosphere, while the working-places 
 and goaves where the gases congregate should have a 
 supply of air large enough to dilute and deprive them of 
 their power. In all excavations where air is renewed, 
 and in the galleries of mines in particular, carbonic-acid 
 gas is continually found in more or less quantity. The 
 ventilation should be sufficient to draw it constantly 
 away, and to keep that quantity which is mixed with 
 the air beneath that limit beyond which it would be- 
 come injurious to the workmen. 
 
34. MINE VENTILATION. 91 
 
 Mr. Richardson, who paid a great deal of attention 
 to the subject, estimated that the quantity of air re- 
 quired for vital chemical purposes for each person was 
 upwards of 1,000 cubic feet per hour. Of this, 84 
 cubic feet were for the breathing of each person ; 62.8 
 cubic feet, for displacing carbonic acid ; 258.4 cubic 
 feet, for diluting nitrogen ; and 27 cubic feet, for dis- 
 placing perspiration. In addition, 59.3 cubic feet should 
 be allowed for the combustion of each light, and 2585 
 cubic feet for one horse. This is not considered an 
 extravagant estimate ; and some hold that it is not 
 enough for diluting all the gases, nor for removing the 
 air after being breathed. 
 
 " By some modes of ventilation, there are contrivances 
 for enabling the men to breathe over and over again 
 the same air, and so accumulate nuisances ; and this is 
 more especially the case in mines which do not give 
 off fiery gases." Such things, however, should not be 
 tolerated at the present age in any district. There is 
 now no difficulty in providing air in sufficient quanti- 
 ties to dilute the gases given off in fiery mines, and so 
 render them harmless. Where the furnace is used for 
 'ventilation, it has been calculated that the cost of ven- 
 tilating the most difficult mines, and where there is a 
 large escape of gas, need not exceed an English penny 
 per day per man, a: id not half so much ill mines where 
 
92 MINE VENTILATION. 35. 
 
 little or no gas is given off. The cost of fan-ventilation 
 is not as great as the furnace, although the first cost 
 is larger. As before stated, enlargement of airways, 
 and judicious division of the current into several splits 
 (which should begin as near as possible to the down- 
 cast), will bring the air much purer and cooler to the 
 miners, and also greatly increase the ventilation. 
 
 PREVENTION OF COLLIERY EXPLOSIONS. 
 
 35. Much has been written and said upon this sub- 
 ject, yet every now and then the public is startled with 
 news of a recent explosion where numbers of lives have 
 been lost. The investigations which follow are not 
 always satisfactory, either to the families of the de- 
 ceased or the managers. Instances may be cited where 
 the injured have received the blame for the negli- 
 gences of either the manager or his " fire-boss." 
 
 There are laws in some of the States which require 
 the managers to allow each miner a certain quantity of 
 air. 1 Whenever there is " bad air," the miner should 
 inform the " mine-boss," and, in case the evil is not 
 speedily remedied, report the fact to the " mine-inspect- 
 or." JMiners should not neglect to do this, even if it" 
 costs them " their job ; " because they risk the lives of 
 
 1 See Sect. 7, Pennsylvania Mine Laws. 
 
35. MINE VENTILATION. 93 
 
 their fellow-miners as well as their own ; and, in case 
 of accident through any neglect on their part, the 
 law will hold them responsible. The first preventive 
 means which should be insisted upon is a really effi- 
 cient and " safe safety-lamp." Many of the so-called 
 safety-lamps are no safety-lamps at all : in fact, they 
 are apt "to lull the inexperienced into false se- 
 curity." Hundreds of miners imagine, that, if they 
 have a safety-lamp, they can work with impunity 
 in the most fiery veins, and can defy almost any 
 risk. " We all know how dangerous such false se- 
 curity must be, and how treacherous many of the 
 lamps have proven when a sudden 'blower' of gas 
 has been struck. Again : many of the lamps can be 
 picked by an ingenious collier, and the most disastrous 
 consequences have resulted from this tampering with 
 so-called safety-lamps. Whatever may be said to the 
 contrary, the mining-world still wants a really safe 
 safety-lamp, one which, while giving a good light, will 
 defy all tampering by the collier, and resist any amount 
 of explosive gas with which it may come in contact. 
 Until we have this, we may look in vain for any appre- 
 ciable decrease in the number of explosions in our fiery 
 pits, and the lives of our colliers will be more or less 
 in jeopardy." 
 
 Another provision, which should be enforced under 
 
04 MINE VENTILATION. 35. 
 
 every circumstance, is to prohibit the use of gunpowder 
 in all fiery, bituminous mines. Shot-firing has, in all 
 probability, to answer for more fatal casualties than 
 some are inclined to ascribe to it. This does not happen 
 so much in anthracite mines, from the fact that there 
 is scarcely any dust floating in the air when compared 
 with bituminous mines : however, we are not sure but 
 that it may apply in some instances even to them. 
 
 It is certain that people are maimed and burned by 
 blasting, at distances varying from ten to a hundred 
 and eighty yards, when there is no fire-damp present to 
 cause such destruction ; then, it is quite clear that this 
 results, either from the simple force and flame of the 
 shot on account of the weight of the charge, or from 
 this force and flame assisted by the rapid combustion 
 of coal-dust as it travels on its course, or from the force 
 and flame assisted by an instantaneous emission of gas, 
 in consequence of a partial vacuum being formed by 
 the rushing blast. With a view of testing these assump- 
 tions, careful experiments were made, a description of 
 which may be found in " Colliery Guardian," England, 
 p. 13, vol. xxxii., the summing-up of which is as fol- 
 lows : 
 
 " 1. The flame from a blown-out shot, unassisted by 
 gas or coal-dust, does not travel farther than five, or, 
 at the utmost, ten yards, entailing little or no danger. 
 
35. MINE VENTILATION. 95 
 
 "2. If coal-dust be present, even in a comparatively 
 damp mine, the flame may not travel fifty yards. That 
 in a dry mine of a high temperature this distance would 
 be greatly exceeded ; and since miners, as a rule, con- 
 sider themselves safe at from fifteen to twenty yards 
 from the point where the powder is used, a blown-out 
 shot under these circumstances is a source of great 
 danger. 
 
 " 3. That the violence of the blast from either gun- 
 powder or fire-damp is much increased when coal-dust 
 is present. 
 
 " 4. That, on any partial vacuum being formed in an 
 underground coal- working, fire-damp will instantly issue 
 in dangerous quantity ; and there are fairgrounds for 
 assuming that a shot blowing out in the face of a nar- 
 row heading, and setting coal-dust on fire in its course, 
 would, by its exhaustive action, produce such a vacuum, 
 and might cause a serious explosion in a mine practi- 
 cally clear of gas. 
 
 "5. Although no experiments have been made di- 
 rectly to test the result of coal-dust set on fire in air 
 heavily loaded with fire-damp, there is every likelihood 
 that such an occurrence would be attended with grave 
 consequences. 
 
 " 6. That it is desirable that any system of blasting 
 coal which entails heavy charges of gunpowder, and an 
 
96 MINE VENTILATION. 36. 
 
 unusual liability to ' shots blowing out,' such as blast- 
 ing without side-cutting, or nicking, or using improper 
 materials for stemming, should be discontinued. 
 
 " 7. A large body of flame, such as results from a very 
 heavy charge or from a blown-out shot, is required to 
 ignite coal-dust; that in blasting with charges not 
 exceeding twelve ounces, accompanied by the proper 
 preparation of holing and side-cutting, there is little 
 liability of this taking place. 
 
 " To discard all shot-firing means, in many mines, a 
 considerable increased cost in the working of coal. 
 But life is the first consideration, and the safety of the 
 collier should be the one great object of the proprietor 
 and manager. The opinion of the best mining engi- 
 neers is, that so long as shot-firing is allowed, even 
 under the most favorable circumstances, so long will 
 there be a certain amount of risk, while, in many cases 
 where the plan is adopted, it often leads to most seri- 
 ous and fatal consequences." 
 
 36. The third point, which should be earnestly con- 
 sidered, is efficient ventilation. There is no country 
 in the world where such facilities are offered for good 
 ventilation, because of the thick coal-seams ; yet in very 
 many instances managers appear to rely too much upon 
 this advantage, and fail to conduct the air properly in 
 
37. MINE VENTILATION. 97 
 
 its journey through the mines ; and there are some that 
 could not, although by law required, give the inspector 
 a design of their ventilation. Thus it is not at all to 
 be wondered at, when such gross negligence prevails, 
 that accidents now and then occur. The cheapest 
 method of obtaining more air is by splitting, and 
 mechanical means. 
 
 Enlarging the airways lessens the velocity, and is 
 another, though costlier, mode of obtaining more air: 
 in small seams it is, however, absolutely imperative. 
 
 CHAPTER X. 
 
 MEASUKING THE AIR. 
 
 37. To measure air travelling through mines, various 
 methods have been employed : those in most general 
 use may be classed under three heads ; viz., 
 
 () Travelling at the same velocity as the air-current, 
 and noting the distance passed over in a unit of time. 
 
 (5) Determining from observation the rate at which 
 small floating particles are carried along by the cur- 
 rent, and assuming their velocities to be identical with 
 that of the air-current itself. 
 
 (V) By the use of the anemometer, or other instru- 
 ments. 
 
98 MINE VENTILATION. 37. 
 
 (#) By the first method it is necessary to select as 
 regular an airway as possible, in which is measured a 
 length of from fifty to two hundred yards. This is 
 traversed in the same direction as the current, a candle 
 being held in the hand, whose flame must be kept ver- 
 tical. The time of walking the distance, which is the 
 same as the velocity of the air, is measured by a watch. 
 The mean of two or three experiments gives a rough 
 estimate of the velocity. 
 
 (5) By light bodies, such as down or powder-smoke, 
 and noting the time it takes for the particles to pass 
 from one point of the gallery to another. Under this 
 head may be classed measurements made by ammonia, 
 sulphuric-ether, etc. To measure air by volatile liquids, 
 small phials containing the liquid are broken at a cer- 
 tain place in the airway, and the time noted that it 
 takes to pass from this point of the gallery to another, 
 the distance between the two having been previously 
 ascertained. 
 
 By vapor-measurements Mr. Arnold constantly ob- 
 tained the same results. This method, so simple in 
 practice, is more exact than measuring by powder- 
 smoke, down, or other light substances. Mr. Arnold 
 considers it to be less subject to error than the best 
 anemometer yet invented. 
 
 On the other hand, others claim that the sense of 
 
37. MINE VENTILATION. 99 
 
 smell being more acute in one person than in another, 
 and different for the same persons at different times 
 it is impossible to measure the air as accurately as with 
 an instrument. 
 
 Many experiments made with anemometers show a 
 variation in their co-efficient at different velocities of 
 the air-current. M. Guibal, in order to suppress this 
 source of error, sought an approximate velocity ; then, 
 by using the co-efficient thus found, he made new ex- 
 periments, which would give the true co-efficients. 
 Two anemometers are required to do this : if they 
 agree, the measurement is correct ; if they do not, one 
 of the two is wrong, and it is then necessary to ascer- 
 tain which. 
 
 (G I ) Miners have long recognized the importance of 
 knowing the volume of air for all pressures of the atmos- 
 phere : hence they regularly measure the air traversing 
 all the main intakes in the returns and at certain 
 points in the various districts. Some use powder- 
 smoke ; but that test has been practically superseded 
 by the anemometer : however, whatever method is 
 employed, the measurements are, or should be, made at 
 certain prescribed times. There are many and vari- 
 ous instruments for measuring the velocity of the air, 
 among which may be mentioned Devillez's, Dickinson's, 
 Briam's, Robinson's, Casella's, and Casartelli's ane- 
 
100 MINE VENTILATION. 37. 
 
 mometers. Briam's is the one most generally used in 
 this country, and is a modification of Robinson's as 
 originally made for meteorological use. It consists of 
 a series of vanes, which revolve by the action of wind. 
 Each revohition is transmitted to dials by means of 
 wheels and pinions. These instruments are made of 
 various sizes, from four to twelve inches. The dials are 
 six in number, marked for feet, hundredths, thousandths, 
 etc. Whatever instrument is used, all that is required 
 to ascertain the velocity is to read the figures on the 
 respective dials before and after experiment, then to 
 subtract the first from the second ; to the remainder is 
 added a value corresponding to the constant friction, 
 and which will be found with the table that comes with 
 each instrument. 
 
 The special formula is of the form 
 
 F = ar + u 
 
 in which r equals the number of revolutions per minute, 
 a equals constant proportional to the number of linear 
 feet traversed by the air in a revolution, and u repre- 
 sents the losses due to friction. 
 
 For the anemometer generally used in Pennsylvania, 
 the correction is about thirty feet when the instrument 
 is new and clean ; but the dirt and grit, to which it is 
 
38. MINE VENTILATION. 101 
 
 more or less exposed, have, no doubt, a tendency to 
 increase the friction, or the correction in time. To de- 
 termine the amount of correction required, the instru- 
 ment is placed on a whirling table ; the anemometer 
 is whirled around by the table revolving ; the velocity 
 of the table is then compared with the indications of 
 the anemometer. 
 
 38. The method of procedure in Conducting experi- 
 ments to find the useful effect of fan-ventilation varies 
 materially from the ordinary method of ascertaining 
 the velocity of the air, because the revolutions of the 
 fan, the indicated power of the engine, water-gauge, 
 etc., must be considered. 
 
 The air is measured by the anemometer in the ven- 
 tilator-drift if possible. At the place of measurement, 
 strings or wires should be fixed so as to divide the drift 
 into, say, ten divisions of nearly equal area. The ane- 
 mometer should run at least one minute in each divis- 
 ion ; one minute interval should be taken for reading 
 the instrument, and moving it to the next division. 
 Simultaneously with the air-measurement, diagrams 
 should be taken from the engine at intervals of three 
 or five minutes. Each diagram should be accompanied 
 with an observation of the water-gauge, and the num- 
 ber of strokes per minute of the engine-piston. The 
 
102 MINE VENTILATION. 38. 
 
 usual working-speed should be adopted for the experi- 
 ment, and it should be maintained as uniformly as 
 possible throughout the trial. After completing the 
 drift-measurements, a second air-measurement should be 
 made, either in the intake or return airways, to check, 
 in some degree, the drift-measurement. To make these 
 check-measurements, move the anemometer uniformly 
 over the whole area of the airway, for, say, two min- 
 utes, repeating the observation twice to avoid error. 
 During these check-measurements, diagrams of engine, 
 and observations of speed and water-gauge, should be 
 taken, as in the first measurement. 
 
 The laws of Mariotte and Gay-Lussac may be applied 
 to correct the volume of air measured in the intake or 
 return airways to the condition of the ventilator-drift 
 at the surface ; namely, for pressure and temperature, 
 as follows : 
 
 Problem. Supposing the volume of air measured 
 at the intake to be 100,000 cubic feet per minute, the 
 required volume which it would occupy in the ventila- 
 tor-drift is found to be 107,900 cubic feet with the fol- 
 lowing conditions : 
 
 Barometer. Temperature. 
 
 Ventilator-drift 30.30" 60 F. 
 
 Intake airway 31.25" 37 F. 
 
 Neglecting any small increase of volume due to 
 
38. MINE VENTILATION. 103 
 
 evolution of gas, or absorption of aqueous vapor in 
 the mine, we have in the ventilator drift, 
 
 100000 x 81^ x (CO* +461) = 107900 cubic feet 
 30.30" X (37 4-461) 
 
 In order to find the amount of work which is ex 
 pended in producing ventilation, and what amount is- 
 lost in overcoming friction, it is necessary to use an 
 indicator, the diagram of which will -give us the effec- 
 tive horse-power, which differs from the nominal or 
 theoretical horse-power. 
 
 Problem. Find the per cent of power used by a 
 fan with the following data : 
 
 Area of piston 484 inches; stroke 2 feet; speed 60 
 revolutions, or 240 feet of piston per minute ; indicated 
 effective pressure on piston 20.89 pounds per square 
 inch ; then, 
 
 484 X 240 x 20.89 
 
 - = 73.54 horse-power engine. 
 ooOUO 
 
 The air in fan-drift measures 106,680 cubic feet per 
 minute. Water-gauge in fan-drift measures 2.8". Then 
 
 106680 x 2.80 x 5.2 
 
 Q A = 4/.06 horse-power m the air. 
 
 ooUUU 
 
 Therefore the per cent of power utilized will be 
 73.54 : 47.06 :: 100 : 64 per cent. Ans. 
 
1 04 MINE VENTILATION. 39. 
 
 THE BAROMETER. 
 
 39. It is supposed that Torricelli derived from Gali- 
 leo the definite conception of atmospheric pressure. 
 Pascal, however, was first to state that the mercurial 
 column decreased in length as we ascend. This ex- 
 periment was for the first time performed at Cler- 
 mont, on the top of the Puy de Dome, Sept. 19, 1648. 
 The barometer in its simplest form consists of a tube, 
 about thirty-four inches long, closed at the top. This 
 tube is filled with mercury, then inverted in a vessel 
 containing mercury. The atmospheric pressure on the 
 vessel of mercury will force the mercury up the tube, 
 or let it sink, according as that pressure is greater or 
 less. These risings and fallings are measured by means 
 of a scale. As mercury expands by heating, it follows 
 that a column of warm mercury exerts less pressure 
 than a column of the same height at a lower tempera- 
 ture. It is usual, on this account, to reduce the actual 
 height of the column to the height of a column of mer- 
 cury at the temperature of freezing water, which would 
 exert the same pressure. 
 
 The formula for this correction is 
 
 7* = h -hm(t- 32), 
 in which h = height of mercury at , h Q = height of 
 
39. MINE VENTILATION. 105 
 
 mercury at freezing-point, m co-efficient of expansion 
 of mercury per degree Fahrenheit = -ggVg- = 0.0001001. 
 
 When very exact readings are required, corrections 
 must be made for expansion of the scale by which the 
 height of the mercurial column is measured, also for 
 capillarity. 
 
 (a) The Aneroid Barometer is a thin metallic vessel 
 partially exhausted of air, and sealed : consequently it 
 will expand or diminish in size as the atmosphere is 
 lighter or heavier. This change in size, M. Vidi made 
 use of, and transmitted the movement to an index. 
 The Aneroid Barometer is a very convenient instru- 
 ment; as it is round, and of small compass. In the 
 second geological survey of Pennsylvania it was used, 
 to a great extent, for determining heights, and making 
 contours, in the anthracite coal-regions. Good Aneroid 
 Barometers are compensated for differences of tempera- 
 ture. 
 
 (5) Atmospheric pressure will, according to the con- 
 dition of the weather, vary from 28.5 to 31 inches of 
 mercurial column. When the barometer rises, the ther- 
 mometer usually falls, and vice versa. The discharge 
 of gas becomes greater when the barometer falls, be- 
 cause the atmospheric pressure which before kept the 
 gas pent up is lessened ; and hence, wherever the press- 
 ure of gas is strong enough to overcome the lessened 
 
106 MINE VENTILATION. 39. 
 
 atmospheric pressure, it escapes. The barometer is 
 useful, therefore, as it will give warning when an in- 
 creased discharge of gas will take place ; and hence 
 precautions may be taken to overcome it by increasing 
 the volume of air. 
 
 Sudden falling of the barometer is much more dan- 
 gerous than a gradual fall ; for in the first case more 
 gas will be given off in less time than in the second. 
 When the barometer is 27 inches, the pressure of the 
 atmosphere per square foot is 1,908.23 pounds ; at 28 
 inches, it is 1,978.90 pounds ; at 29 inches, it is 2,049.58 
 pounds; at 30 inches, it is 2,120.25 pounds; at 31 inches, 
 it is 2,190.93 pounds. 
 
 The following table will be found useful in order to 
 ascertain the pressure per square foot, or fractional part 
 of a foot, for a given height of the barometer. 
 
39. 
 
 MIKE VENTILATION. 
 
 107 
 
 TABLE VII. 
 PRESSURE OF AIR PER SQUARE FOOT. 
 
 Inches. 
 
 Pounds. 
 
 Inches. 
 
 Pounds. 
 
 Inches. 
 
 Pounds. 
 
 0.01 
 
 0.71 
 
 0.12 
 
 8.48 
 
 0.50 
 
 35.34 
 
 0.02 
 
 1.41 
 
 0.13 
 
 9.19 
 
 0.60 
 
 42.41 
 
 0.03 
 
 2.12 
 
 0.14 
 
 9.90 
 
 0.70 
 
 49.48 
 
 0.04 
 
 2.83 
 
 0.15 
 
 10.60 
 
 0.80 
 
 56.54 
 
 0.05 
 
 3.53 
 
 0.16 
 
 11.31 
 
 0.90 
 
 63.61 
 
 0.06 
 
 4.24 
 
 0.17 
 
 12.02 
 
 . 1.00 
 
 70.68 
 
 0.07 
 
 4.95 
 
 0.18 
 
 12.72 
 
 2.00 
 
 141.36 
 
 0.08 
 
 5.65 
 
 0.19 
 
 13.43 
 
 3.00 
 
 212.04 
 
 0.09 
 
 6.36 
 
 0.20 
 
 14.14 
 
 4.00 
 
 282.72 
 
 0.10 
 
 7.07 
 
 0.30 
 
 21.20 
 
 
 
 0.11 
 
 7.77 
 
 0.40 
 
 28.27 
 
 
 
 Problem. Require the amount, in cubic feet, of air 
 and gas that may be expected to be given off for 1,000 
 cubic feet of open space in the goaves, or other waste 
 places, by a falling of the barometer from 30.4 inches 
 to 28.75 inches. 
 
 The pressure at 30.4 inches = 2,148.52 pounds 
 The pressure at 28.75 inches = 2,031.91 pounds 
 
 Then, 
 or 
 
 Difference 116.61 pounds. 
 
 2,148.52 : 116.61 :: 1000 : 54.27, 
 30.40 : (30.40 - 28.75) :: 1000 : 54.27 
 
108 MINE VENTILATION. 39. 
 
 cubic feet of gas, which, theoretically, may be given 
 off by a reduction of pressure equal to that indicated 
 above. 
 
 Experience in the use of the barometer in mines has 
 shown that its indications are from one to three hours 
 behind what is actually taking place. On this account 
 it has been asserted that the barometer is not to be 
 relied upon to give warnings. According to the " Col- 
 liery Guardian," Jan. 31, 1883, the government issued 
 and sent out in England, during the year 1882, thirty- 
 two warnings, nineteen of which were justified by sub- 
 sequent events. Twelve were followed in three days 
 by explosions which caused one hundred and thirty -nine 
 deaths ; two were followed on the fifth day by explosions 
 causing forty-three deaths ; twenty-three lives were lost 
 on the sixth day after the warning showing that a 
 total of two hundred and five lives were lost in six days 
 from the issue of the warnings, while five lives were 
 lost on the day of the issue. 
 
 We have noticed, when there have been explosions 
 telegraphed from England, that, within a short time, 
 explosions have occurred in our American mines. This 
 warning should never be slighted, whether the explos- 
 ions are due to falling or rising barometer. These 
 teachings, we are aware, conflict with some of the late 
 writings on this point; but we are so convinced by 
 
40. MINE VENTILATION. 109 
 
 analogy that one of our very best warnings is the ba- 
 rometer, that we hope our own government will follow 
 England's Signal Service Bureau, and send our colliery 
 managers warnings. 
 
 CHAPTER XI. 
 
 CONCLUSION. 
 
 40. THE first method employed to ventilate mines 
 was, we believe, to agitate the air by shaking a cloth, 
 next, natural ventilation by means of upcast and down- 
 cast shafts. This method was followed from necessity 
 by the furnace ; and even to-day this latter method is 
 considered by some the best, on account of the liability 
 of mechanical ventilators to get out of order, and so 
 stop the current. The furnace is still used in many 
 mines, but is being gradually superseded by the me- 
 chanical means now at our command. It is, however, 
 more effective in deep mines than any thing as yet 
 employed , but it is just in this position that it is the 
 most dangerous, as, the deeper we descend, the more 
 gas we are likely to encounter. In shallow mines, espe- 
 cially if worked at a dip, the fan is the more economical 
 of the two systems. The steam-jet, at one time, was 
 
110 MINE VENTILATION. 40. 
 
 a rival of the furnace. This was followed by allow- 
 ing water to fall down the downcast ; but this system 
 proved inefficacious, as it did not provide enough change 
 of temperature, and the water had to be pumped back 
 again, in most cases, out of the mine. The mechanical 
 ventilators of late years have been numerous ; but, of 
 all the number, not one perfect one has been produced. 
 Guibal's Fan seems to be the favorite; and to him is 
 due the simplest, and, with his sliding shutter, the most 
 effective fan. Nixon made a ventilator on the air-pump 
 system, the immense piston of which goes backwards 
 and forwards on wheels. The air is received into a 
 chamber, and forced out by this piston : it works ex- 
 actly upon the same principle as a pump, drawing 
 the air from the mine by one set of valves, and then 
 forcing it out by another on the back movement of the 
 piston. 
 
 Mr. Struve constructed a machine upon a principle 
 similar to that of Mr. Nixon, using two large gas-tanks, 
 arranged with valves. These gasometers moved up 
 and down alternately in water, this means taking the 
 place of a piston. There are also centrifugal machines, 
 receiving the air at the centre, and throwing it off from 
 the ends of the blades : others are made on the wind- 
 mill plan, each blade, as it revolves, cutting out a defi- 
 nite portion of the air. The Champion Ventilator, 
 
40. MINE VENTILATION. Ill 
 
 the only really distinctive American ventilator, is so 
 arranged as to be used either as a forcing or exhaust- 
 ing fan. It is credited with very good results. Every 
 new fan which has been built of late has been declared 
 to give at least ten per cent more air for the same 
 amount of power than any fan previously invented. 
 This can hardly be believed, unless it has been proven 
 by placing the new fan in a position where some other 
 fan has been, with the conditions of the mine and the 
 power just the same. 
 
 Theoretical comparison of two fans at different mines 
 cannot give any thing like exact results, as the air- 
 ways and resistances will not be similar in the two 
 mines ; and, while one fan may be better than the other, 
 yet, in its position, it may be unable to cope with an 
 inferior adversary more favorably situated. A larger 
 water-gauge may be obtained in the fan-house than in 
 the airway leading to the fan: this is accounted for 
 by the fact that the fan offers more or less resistance to 
 the air, and slightly impedes its discharge. A perfect 
 fan should not do this, at least to any great extent. 
 Theoretically and practically the amount of ventilation 
 obtainable from furnace-action will depend upon the 
 difference in weight of two air-columns. An improper 
 consideration of this subject has led the enemies of 
 the furnace to state that there is a material difference 
 
112 MINE VENTILATION. 41. 
 
 between the action of furnace and fan ventilation ; the 
 former being likened to propulsion, the latter to trac- 
 tion. Were the air propelled, the power expended 
 would be applied to force the air down one of the 
 shafts, which the furnace does not do, but draws the 
 air down, expelling it in lighter form, the same as 
 the exhaust fan. 
 
 41. Suppose the exhaustion produced in a fan-drift 
 at 40 revolutions per minute of the fan averages about 
 1.25 inches of water-gauge, while at 60 revolutions of 
 the fan we have 2.8 inches water-gauge, a rise propor- 
 tional to the square of the speed. Since the vacuum 
 increases as the square of the number of revolutions 
 per minute, the quantity of air produced should be the 
 same per revolution at any speed where the conditions 
 are unchanged, for the volume of air varies as the 
 square root of the water-gauge ; i.e., the square root 
 of the lowest pressure bears the same relation to the 
 square root of the highest pressure as forty revolutions 
 bear to sixty revolutions per minute ; or 
 
 Therefore, if it were desirable to pass double the quan- 
 tity of air though a mine or drift where the existing 
 friction is equal to one inch of water-gauge, without 
 
41. MINE VENTILATION. 113 
 
 making any alteration in the underground arrange- 
 ments, the effect of the change would be to increase the 
 measure of resistance to four inches of water-gauge; 
 also the power required to overcome this friction would 
 be eight times that employed for the original quantity, 
 as, in addition to the friction being fourfold, the volume 
 of air is also doubled. In like manner, for three times 
 the quantity, we have nine times the resistance, and 
 require twenty seven times the power. 
 
 The following table is taken from Mr. R. Howe's 
 paper, printed in the Transactions of Chesterfield and 
 Derbyshire Institute of Engineers; the fan under con- 
 sideration being a Guibal. In the preparation of the 
 table, the following general principles are observed : 
 
 1st, The quantity of air increases in proportion to 
 the speed of the fan. 
 
 2d, The water-gauge increases proportionately to the 
 square of the number of revolutions of the fan. 
 
 3d, The horse-power in the air increases as the cube 
 of the quantity. 
 
 4th, The steam pressure in the cylinder is in propor- 
 tion to the square of the piston's speed. 
 
 5th, The horse-power of the engine is proportionate 
 to the cube of the number of revolutions per minute, 
 or to the cube of the volume of air. 
 
 Illustrations : 
 
114 MINE VENTILATION. 41. 
 
 1st, 25 rev. : 30 rev. : : 44450 : 53340 cubic feet of air. 
 2d, (25) 2 rev. : (30) 2 rev. : : 0.48 w.g. : O.G9+ or 0.7 w.g. 
 
 44450 x 0.48 x 5.2 
 
 3d, - = 34 horse-power in the air. 
 
 ooOOO 
 
 4th, (25) 2 : (30) 2 : : 3.G2 : 5.21+ pressure on piston. 
 5th, (25) 8 : (30) 8 : : 5.32 : 9.19 effective HP. of engine. 
 
 Assuming the quantity of air discharged for each 
 revolution of the fan to be 1,778 cubic feet, then, at 25 
 revolutions per minute, the number of cubic feet pass- 
 ing will be 
 
 25 X 1778 = 44450 cubic feet. 
 
 This does not always hold good when the number of 
 revolutions are greatly increased, from the fact that 
 the baffling of the air does not admit the water-gauge 
 to register correctly. " The theoretical quantity of a 
 fan at High Colliery was short, when compared with 
 the measurements, 3,048 cubic feet per minute." The 
 fan gave off 1,584 cubic feet per revolution: there- 
 fore the quantity that should have been delivered was 
 82,368 ; but from measurement 81,923 cubic feet were 
 delivered at 1.3 inches water-gauge. From the formula 
 
 it was found that while 
 
 X 82.36 = 99.665 cubic feet 
 
 l.o 
 
42. 
 
 MINE VENTILATION. 
 
 115 
 
 was all that the water-gauge called for, the measured 
 quantity was 102.713 cubic feet, making a difference in 
 the second case of 3.048 cubic feet per minute, as stated 
 above. 
 
 TABLE YIII. 
 GUIBAL FAJST. 
 
 II 
 
 & 
 | 
 
 || 
 
 3 
 
 gll 
 
 1 
 
 O go 
 
 Ed 
 
 Si 
 
 s 
 
 X 
 
 ~f 1 
 
 "o 
 u- 
 
 ll 
 
 P O 
 
 J: S *^ 
 
 4> 
 
 If 
 
 8 1 
 
 S 
 
 ~ s 
 
 111 
 
 is 
 
 S 2 a 
 
 JfcJ co P,O 
 
 || 
 
 * 
 
 
 
 o-" 
 
 B 
 
 W 
 
 w 
 
 25 
 
 0.48 
 
 44,450 
 
 3.40 
 
 3.62 
 
 5.32 
 
 30 
 
 0.70 
 
 53,340 
 
 5.88 
 
 5.22 
 
 9.19 
 
 35 
 
 0.95 
 
 62,230 
 
 9.29 
 
 7.11 
 
 14.59 
 
 40 
 
 1.24 
 
 71,120 
 
 13.94 
 
 9.28 
 
 21.78 
 
 45 
 
 1.57 
 
 80,110 
 
 19.85 
 
 11.75 
 
 31.02 
 
 50 
 
 1.94 
 
 88,900 
 
 27.23 
 
 14.50 
 
 42.55 
 
 55 
 
 2.35 
 
 97,790 
 
 36.25 
 
 17.55 
 
 56.64 
 
 60 
 
 2.80 
 
 106,680 
 
 47.06 
 
 20.89 
 
 73.54 
 
 65 
 
 3.28 
 
 115,570 
 
 59.84 
 
 24.51 
 
 93.50 
 
 70 
 
 3.81 
 
 124,460 
 
 74.34 
 
 28.43 
 
 116.77 
 
 75 
 
 4.37 
 
 133,350 
 
 91.93 
 
 32.64 
 
 143.63 
 
 80 
 
 4.98 
 
 142,240 
 
 111.57 
 
 37.13 
 
 174.31 
 
 85 
 
 5.62 
 
 151,130 
 
 133.82 
 
 41.93 
 
 209.08 
 
 90 
 
 6.30 
 
 160,020 
 
 158.85 
 
 47.00 
 
 248.20 
 
 95 
 
 7.02 
 
 168,910 
 
 186.83 
 
 52.37 
 
 291.90 
 
 300 
 
 7.77 
 
 177,800 
 
 217.90 
 
 58.03 
 
 340.46 
 
 42. The Guibal Fan belongs to that class of ventila- 
 tors called centrifugal, because of the air being thrown 
 
116 MINE VENTILATION. 42. 
 
 off at the tip of the blade tangent to the circumference 
 of the fan. There are probably more of these fans in 
 use than of any other kind : seemingly they have the 
 precedence among the best mining engineers, maybe 
 from their simplicity of construction, or from their non- 
 liability to get out of order. The committee of the 
 North of England Institute, appointed to determine 
 the useful effect of different fans, reported : 
 
 Per cent useful effect. 
 
 Struve 57.80 
 
 Guibal 52.95 
 
 Waddle 52.79 
 
 Schiele 49.27 
 
 Thus placing them nearly on a par with a displacement 
 machine in the van. Mr. Howe, in his experiments 
 quoted above, places the useful effect of the Guibal at 
 about sixty-four per cent. The fan is enclosed in a 
 house, the air being discharged through a chimney 
 which gradually expands towards the top. That there 
 is a certain amount of benefit derived from this chim- 
 ney has been proved by experiment, simply because by 
 its use there is a saving in final velocity by the oppor- 
 tunity it affords the air for expanding. The opening 
 for the discharge of the air is regulated by an adjustable 
 shutter. To find the most advantageous position for 
 this shutter, a series of experiments must be instituted. 
 
42. MINE VENTILATION. 117 
 
 First, the shutter is fixed at a certain point, then the 
 amount of air ascertained by measurement, as before 
 explained ; the shutter is now lowered and the meas- 
 urement again taken ; again the shutter is lowered and 
 the measurement taken. If, however, in the last posi- 
 tion, a less amount of useful effect is shown than in the 
 previous position, the shutter has been lowered beyond 
 its most useful position, and must be returned to the 
 second position. 
 
 The position of the shutter depends upon the speed 
 at which the fan runs. Should the shutter vibrate 
 when the speed is increased, it shows that the fan is 
 not working properly, and that the shutter needs regu- 
 lating. 
 
 A modification of the Guibal Fan is used in the an- 
 thracite regions, having, instead of the shutter, a spiral 
 casing, commencing at the orifice of discharge (throat), 
 and extending sometimes the whole .circumference, ac- 
 cording to the notion of the engineer. Whenever this 
 spiral casing is too short, thumping will take place. 
 The discharge is regulated at the throat by a short 
 shutter, or by nailing boards over the orifice. The 
 more recently built fans are made as large as forty-five 
 diameter, and have fire-proof casings of iron. 
 
118 MINE VENTILATION. 43. 
 
 COMPARATIVE ECONOMY OF FURNACE AND FAN 
 VENTILATION. 
 
 (FROM MB. R. HOWE'S PAPER.) 
 
 43. Suppose we have two furnace-pits, the first 260 
 feet deep, the second 655 feet deep. 
 
 To arrive at the horse-power of furnace-ventilation, 
 we must find the pressure producing it. 
 
 First, Barometer of the first pit, 30.3" ; temperature 
 of downcast, 55? ; of upcast, 240. The pressure, there- 
 fore, of the downcast in pounds per square foot, is 
 
 1.3253 x 30.3 26Q = 2() 312 dg> 
 
 459 + 55 
 
 The pressure of the upcast is 
 1.3253 X 30.3 
 
 459 -f 240 
 
 X 260 = 14.936 pounds. 
 
 20.312 14.936 = 5.376 pounds as the pressure per 
 square foot for ventilating pressure, and this pressure 
 will give us, say, 30,358 cubic feet of air, then the 
 horse-power will be 
 
 30358 x 5.376 
 
 - = 4.94 horse-power in the air. 
 
 ooUUU 
 
 Second, Mean barometer, 30.6"; temperature of down- 
 
43. MINE VENTILATION. 119 
 
 cast, 58; temperature of upcast, 117; then the press- 
 ure in pounds per square foot is, for downcast, 
 
 1.3253 X 30.6 655 = pou nds ; 
 
 459 + 58 
 
 for upcast, 
 
 1.3253 X 30.6 
 
 459 + 117 
 
 X 655 = 46.116 pounds. 
 
 Hence, for ventilating pressure, 51.379 46.116 = 5.263 
 pounds per square foot ; and this pressure gives 48,230 
 cubic feet of air |>er minute, which, reduced, gives us 
 7.69 as the horse-power in the air. 
 
 These two furnaces ventilated the Hollingwood pits. 
 The No. 1 furnace used 3 tons 12 hundred weight of 
 coal in 24 hours, or 68 pounds per hour per horse-power 
 in the air. No. 2 furnace used 3 tons 1 hundred weight 
 per day, or 37 pounds of coal per hour per horse-power 
 in the air. The two furnaces circulated 78,588 cubic 
 feet of air, with a horse-power of 12.63. 
 
 A Guibal Fan was afterwards substituted to take the 
 place of these furnaces, the ordinary speed of which 
 was sixty revolutions per minute. The average quan- 
 tity of air circulated at this speed was 106,680 cubic 
 feet; the pressure, 2.8 water-gauge, or 14.56 pounds per 
 square foot. 
 
120 
 
 MINE VENTILATION. 
 
 43. 
 
 Tabulated results of the above calculations show the 
 economy of fan over furnace ventilation. The wages 
 and price of coal are those regulated by the English 
 market at the time of the writing, reduced to United- 
 States money. 
 
 TABLE IX. 
 
 
 li 
 
 O 1 *" 
 
 8*1 
 
 *j 00 S 
 
 *Js 
 
 3 9 
 Soft 
 
 pi 
 
 DUE TO FAN. 
 
 cp 
 
 Decrease. 
 
 1. Cubic feet of air per minute . 
 2. Pressure in pounds per 
 square foot 
 
 78,588 
 5.304 
 12.63 
 $10.44 
 
 $0.82 
 
 49 
 
 106,680 
 14.56 
 47.06 
 $5.33 
 $0.12 
 
 10 
 
 28,092 
 9.256 
 34.43 
 
 $5.11 
 $0.70 
 
 39 
 
 3. Horse-power in air, in- 
 cluding shaft friction . . 
 4. Cost of fuel, wages, etc., for 
 
 5. Cost for 24 hours per horse- 
 power in the air .... 
 6. Pounds of coal consumed 
 per horse-power in the air 
 per hour 
 
 
 Amount saved in one year by fan 
 
 . . . . $2,120. 
 
 65 
 
 
APPENDICES. 
 
 APPENDIX. A. 
 
 FORMULAS.* 
 
 44. Let a = area of airway in square feet. 
 
 = perimeter of airway in feet. 
 
 1 = length of airway. 
 
 s = rubbing-surface in feet. 
 
 k = co-efficient of friction, 0.0217 of a pound 
 at a velocity of 1,000 feet per minute. 
 
 p = pressure in pounds per square foot of sec- 
 tional area. 
 
 v velocity of the air in feet per minute. 
 
 w = water-gauge. 
 
 q = quantity of air circulating, in cubic feet, per 
 minute. 
 
 u = units of work applied to circulate the air. 
 HP = horse- power of ventilation. 
 
 * From Mining Herald Almanac. 
 
122 MINE VENTILATION. 44. 
 
 Then the following formulas for friction of air in 
 mines may be deduced : 
 
 ksv 2 pa ksv~q ksv 3 u q q 
 p p u pv pv v ~ i~^' 
 
 k3/ 
 
 A 8 -i -_^___ 
 
 ~ kv' 2 ~ kv 8 ~ kv*~~ kv* 
 
 . pa u p iv5.2 
 
 v. K == -> ^= z = T) == 5 
 
 sv 2 sv* sv 2 sv 2 
 
 a a 
 
 ksv 2 u pa ksv* u 
 
 6. p = = -=-= = = 5.2w. 
 
 a q a q av 
 
 rj .. a * y *<y ic y F 
 
 ~pa~a~\ks~\ks ~~ V ks' 
 ksv 2 
 
 \na t 
 
 9. a = va = - = = ~- X a = ~ X a- 
 
 p p ks 
 
 10. u = qp = vpa = - = A:sv 8 = ^5.2^ = HP 
 
 X 33000. 
 
44. MINE VENTILATION. 123 
 
 U qp 
 
 11. HP = 
 
 33000 33000 
 
 12. ^=^ = fty^u 
 
 , , / u\* . u 
 
 14. pa = Jcsv 2 = ( t 8 / 7- ) X ks = 
 
 VV ksj v 
 
 " These formulas comprise the pressure due to resist- 
 ance, and not that necessary for final velocity: they 
 are, therefore, more correct for long than for short air- 
 ways. The pressure required for final velocity becomes 
 a smaller fraction of the whole drag as the airways 
 extend. If it be required to take into account the 
 pressure to create velocity, 
 
 A*9?)^ 7c^ f i) 
 
 Instead of using a = - , use =5. 
 
 p p-P 
 
 Instead of using pa = fcsv 2 , use a(p P) = Jcsv*. 
 
 ksv 2 ksv* JCSV* 
 
 Instead of using p , use p P = , or f- P. 
 
 a a a 
 
 Instead of using s = J^, use 7.^2 ' 
 
 4 fpv 4 /(P P) a 
 Instead of using v =y -JT-, use y - ^ 
 
124 MINE VENTILATION. 45. 
 
 APPENDIX B. 
 
 PKOBLEMS. 
 
 45. 1. What is the area of an airway 6 feet by 5 feet? 
 What is its perimeter ? a 30 ; o = 22. Ans. 
 
 2. What is the area of a shaft 14 feet diameter? 
 Rule. Diameter 2 X 0.7854. 153.98 + feet. Ans. 
 
 3. What is the perimeter of a shaft 16.5 feet diameter ? 
 Rule. Diameter X 3.1416. 58.83 + feet. Ans. 
 
 4. The long axis of an elliptical shaft is 14 feet, its 
 short axis 6 feet : what is its area ? 
 
 Rule. A XaX 0.7854. 65.9736 feet. Ans. 
 
 5. Find the perimeter of an elliptical shaft whose 
 axis A is 16 feet, and its axis a 8 feet. 
 
 A -\-a 
 
 Rule.- ~ 2 X 3.1416. 
 
 38.7 feet. Ans. 
 
 6. An air-course is 500 yards long, 6 feet high, and 
 7 feet wide : what is its area, perimeter, and rubbing- 
 surface ? 
 
 a = 42 ; o = 26 ; s = 39000 square feet. Ans. 
 
 7. What is the rubbing-surface of a shaft 15 feet 
 diameter, 1,200 feet deep ? 56548.8 feet. Ans. 
 
45. MINE VENTILATION. 125 
 
 8. In an airway 8 feet by 9 feet, when the current 
 has a velocity of 15 feet per second, what quantity of 
 air is passing per minute ? 
 
 Rule. aXvX 60". 64800 cubic feet. Ans. 
 
 9. When the water-gauge is 1.85 of an inch, what 
 pressure per square foot does it indicate ? 
 
 Rule. w X 5.2. 9.62 pounds. Ans. 
 
 10. When the quantity of air passing is 60,000 cubic 
 feet, with a water-gauge of 1.5 inches, what are the units 
 of work producing ventilation ? 
 
 Rule. u= pq. 468000 units. Ans. 
 
 11. What horse-power is there in 468,000 units of 
 work? 
 
 14.18. Ans. 
 
 12. The pressure producing ventilation is 7.8 pounds : 
 what is the water-gauge ? 
 
 P 
 Rule. w = -/-$ 1.5 inch. Ans. 
 
 O.ju 
 
 13. There are 50,000 cubic feet of air passing, having 
 a rubbing-surface 24,000 feet, and an area of 20 square 
 feet : what is the water-gauge ? 
 
 ksv 2 
 
 Rule. w = -^. 3.12 inches water-gauge* Ans. 
 5.2 
 
126 MINE VENTILATION. 45. 
 
 14. The rubbing-surface of an airway is 25,000 feet, 
 its area 25 square feet : what is its length ? 
 
 1250 feet. Ans. 
 
 15. What units of work are necessary to overcome 
 friction of an airway 6 feet by 6 feet, 1,000 feet long, 
 when the quantity passing is 7,200 feet per minute ? 
 
 v/ 
 
 Rule. u = - X <? 4166 units. Ans. 
 
 a 
 
 16. Let a = 36 ; * = 24,000, to find the value of 
 
 = 1.39. Ans. 
 
 a 
 
 17. With 0.9 of an inch water-gauge, 16,000 cubic 
 feet of air are passing : what quantity will pass when 
 there is a water-gauge of 1.6 inches ? 
 
 V^9 : vT6 : : 16000 : 21333 +. Ans. 
 
 18. With a fan and furnace combined, 46,706 cubic 
 feet are produced ; the furnace produces alone 4^,670 
 cubic feet: what will the fan produce by itself? 
 
 V46706 2 - 42670 2 = 18993. Ans. 
 
 19. If, with a water-gauge of 0.65 of an inch, 20,000 
 cubic feet of air are obtained, what height will the 
 water-gauge be when there is a quantity of 75,000 
 cubic feet of air passing ? 
 
 ^ = x .-. x 2 X w = 9.139. Ans. 
 
45. MINE VENTILATION. 127 
 
 20. How much must we increase the pressure to 
 double the quantity of air? 4 times. Am. 
 
 21. How much has the ventilating power to be in- 
 creased to treble the quantity of air ? 
 
 3 3 = 27 times. Ans. 
 
 22. If we obtain 25,000 cubic feet of air by 5-horse 
 power, what horse-power "will be required to circulate 
 60,000 cubic feet in the same mine ? 
 
 or q r : q : : V5 : \ Ans. 
 
 23. There are two air-courses through which a total 
 quantity of 100,000 cubic feet of air is passing; the 
 resistances of the airways are in the proportion of 4 
 to 1 : what quantity will pass along each? 
 
 V^l X 100000 100000 
 
 ,- . /- == 3 33333^ cubic feet for airway 
 
 having greater resistance. 
 
 \ll x'looooo 
 
 666661 cubic feet for airway having 
 
 only one-fourth the resistance. 
 
 24. Find the motive-column where the upcast and 
 downcast shafts are 540 feet deep, the temperature of 
 the upcast being 129, and that of the downcast 43. 
 
 JOQ _ 43 
 Rule. M=DX 459 . 43' 92 - 51 - Ans - 
 
128 MINE VENTILATION. 46 
 
 APPENDIX C. 
 
 46. THE quantity of air required per man for res- 
 piration has been variously estimated by the following 
 authorities : 
 
 " The volume of air contained in the lungs, accord- 
 ingly is 109 cubic inches ; after respiration, 60 cubic 
 inches remain in the chest ; total volume 170 cubic 
 inches. Amount of each inspiration has been differently 
 estimated, it is probably 16 to 20 cubic inches." ME. 
 GOODWIN. 
 
 "Men between five and six feet in height, after a 
 complete. inspiration, expel by force, on an average, 225 
 cubic inches at 60. This is called 'vital capacity of 
 the lungs.' ' - MR. HUTCHINSON. 
 
 " Assuming a man takes twenty breaths per minute, 
 each 40 cubic inches vitiates 28 cubic feet per hour. 
 Besides this, a quantity of vapor is emitted, which, 
 according to Dumas, amounts to 0.0836 of a pound of 
 water per hour, enough to saturate 7.1 pounds of air 
 at 60. And if we allow, that, to be healthful and pleas- 
 ant, the air should be only one-half saturated, we require 
 14.2 pounds of air, or 187 cubic feet, giving us a total of 
 215 cubic feet per hour, which happens to be the capa- 
 city of a 6-foot cube. This is the maximum quantity 
 
46. MINE VENTILATION. 129 
 
 necessary for clean, healthy persons. For prisons^ etc., 
 it should not be less than 350 cubic feet, and for hospi- 
 tals 1,000 cubic feet, per hour per head." - - MR. Box. 
 
 " A minimum of 100 cubic feet per minute for each 
 man and boy, for sanitary purposes alone." MR. HER- 
 BERT MACKWORTH. 
 
 "From 100 to 500 cubic feet per minute for each 
 collier, according to condition of the mine." MR. 
 HEDLEY. 
 
 "The minimum quantity of fresh air for the most 
 harmless of pits ought to be from 10,000 to 15,000 
 cubic feet per minute." MR. DUNN. 
 
 " In most fiery mines, an average of 600 cubic feet 
 per minute per collier is circulated, and nearly 200 cubic 
 feet per minute for each acre of waste." PROFESSOR 
 PHILLIPS. 
 
 " For all anthracite mines, nearly double the above 
 estimates (which are for bituminous mines) should be 
 allowed, because of the much greater volume of powder- 
 smoke, due to the large amount of blasting done." 
 THOMAS J. FOSTER. 
 
 The Mine Ventilation Act for the anthracite region 
 of Pennsylvania provides for 66 cubic feet of pure air 
 per minute for each man working. All authorities 
 agree in declaring this amount inadequate. 
 
130 
 
 MINE VENTILATION. 
 
 47. 
 
 
 . 
 
 1 
 
 1 
 
 jl 
 
 c a 
 
 ""9 
 
 
 
 
 y 
 
 "o 3 
 
 . 
 
 a ? ' 
 
 M 
 
 AUTHORITY. 
 
 eL 
 
 sl 
 
 3 
 
 oo 3 
 
 a *** 
 
 
 3 
 
 E* 
 
 Ijj 
 
 c ^-^ 
 
 ""g 
 
 
 bo 
 
 S 
 
 H ** 
 
 ^ 'O j_, 
 
 .2 -~^ s3 
 
 
 a 
 
 
 
 Si o w 
 
 
 
 
 o ~- 
 
 D ^ 
 
 o ft 
 
 g *Q P 
 
 
 * 
 
 to 
 
 
 
 ^ 
 
 Q 
 
 ( youth 
 
 21 
 
 15 
 
 11 
 
 0.33 
 
 315 
 
 Koscoe -J a( |ult. . . . 
 
 43 
 
 15 
 
 22 
 
 0.66 
 
 645 
 
 Atkinson 
 
 _ 
 
 _ 
 
 12 
 
 0.84 
 
 345 
 
 Colliery Pocket-Book . 
 
 _ 
 
 _ 
 
 16 
 
 0.54 
 
 480 
 
 Briston M. S. Lectures . 
 
 _ 
 
 _ 
 
 28 
 
 0.84 
 
 _ 
 
 Annales des Mines . . 
 
 - 
 
 - 
 
 33 
 
 1.00 
 
 - 
 
 Average 
 
 
 
 22 
 
 0.72 
 
 
 
 
 
 
 
 
 APPENDIX D. 
 
 ASPHYXIA. 
 
 47. THE miners are exposed to asphyxia when the 
 circulation of the air is not sufficiently active, and 
 when they imprudently penetrate into ancient and 
 abandoned workings, or wherever the air has not suffi- 
 cient oxygen. 
 
 The symptoms of asphyxia are sudden cessation of 
 the respiration, of the pulsations of the heart, and of the 
 action of the senses. The face is swollen and flushed; 
 
47. MINE VENTILATION. 131 
 
 the eyes protrude ; the features are distorted, and the 
 face often livid, etc. 
 
 It is necessary to succor an asphyxiated person with 
 the greatest promptitude, and to continue the remedies 
 as long as there is not a certainty of death. The best 
 and first remedy to employ, and in which the greatest 
 confidence has been and should be placed, is the re- 
 newal of the air necessary for respiration. As an 
 instance, let me cite the experience jof John Boyle and 
 his son at Yorktown, Penn., who were as near death as 
 men could be, and return to life. The men knew the 
 air was bad in their place (a pitching-breast) ; but the 
 necessities of life were superior to their discretion, and 
 they continued working until eleven A.M., when the 
 young man concluded he could stand it no longer, and, 
 in making his way from the face to the manway, was 
 overcome, and fell ere he reached it. Mr. Boyle, who 
 was also very weak, took hold of the boy, arid, between 
 pulling and lifting him over bowlders, succeeded, very 
 luckily, in reaching the manway ; but there he found 
 the air was still too heavy to support life. The exertion 
 and excitement in his endeavor to rescue his boy, and 
 take him down the narrow outlet, together with the 
 deadly gas, proved too much for him, and he. too, 
 fainted away, with the young man in his arms, both 
 becoming tangled fast between the timbers, foot-sills, 
 
132 MINE VENTILATION. 47. 
 
 and slabbing. At five o'clock in the afternoon, a com- 
 pany hand thought something was wrong because of 
 the Boyles remaining in the breast so long, without 
 coming down, and started up the manway after them, 
 and found them near the top, fast, and, as he thought, 
 dead. Aid was summoned, and the miners taken down. 
 The young man revived after reaching the gangway. 
 The father was taken home on a stretcher, and, with 
 much care and labor, was brought back to life. This 
 was a peculiar case. Had there been a larger quantity 
 of black-damp in the air, neither men would have sur- 
 vived; but there seems to have been enough oxygen 
 present to keep life in their bodies, while there was not 
 enough to allow of their keeping their senses. 
 
 While it is well enough to know the following meth- 
 ods for restoring asphyxiated persons, and to employ 
 them while waiting for the doctor, yet it is imperative 
 that a physician be summoned immediately. 
 
 The following short and clear instructions for the 
 recovery of suffocated persons are those issued by Napo- 
 leon, 1813, Tit. iii. Art. xv. 
 
 1. Remove the patient to pure air. 
 
 2. Undress, and bathe his body with cold water, par- 
 ticularly about the neck. 
 
 3. Endeavor to make him swallow, if it be possible, 
 cold water acidulated with vinegar. 
 
47. MINE VENTILATION. 133 
 
 4. Clysters should be given, two-thirds of cold water 
 and one-third of vinegar, to be followed with others, of 
 a strong solution of common salt, or senna and epsom 
 salts. 
 
 5. Attempts should be made to irritate the pituitary 
 membrane with the feather-end of a quill, which should 
 be gently moved in the nostrils of the patient ; or stimu- 
 late it with ammonia placed under the nose. 
 
 6. Introduce air into the lungs .by blowing with the 
 nozzle of a bellows into one of the nostrils, compress- 
 ing the other with the fingers. 
 
 7. If these means do not produce the effects expected, 
 the body of the asphyxiated person remaining warm 
 (as that generally occurs for a long time), it will be 
 necessary to have recourse to blood-letting, the neces- 
 sity of which is indicated by the redness of the face, 
 the swollen lips, and protruding eyes. The blood may 
 be taken from the jugular vein or foot. 
 
 8. As a last resource, an opening should be made in 
 the trachea, and a small pipe introduced, through which 
 the air may be applied by the aid of a small bellows. 
 These remedies should be promptly applied : as death 
 does not appear certain for a long time, they should be 
 only discontinued when it is clearly affirmed. 
 
 Although much more might be said about the hygiene 
 of mines, and many rules laid down for the miners and 
 
134 MINE VENTILATION. 47 
 
 bosses, yet that belongs clearly to another subject ; and 
 this would not have been inserted but for the frequency 
 with which such accidents happen, and from the neces- 
 sity of applying quick remedies. For further informa- 
 tion, see "Mine Foreman's Pocket-Book," issued by 
 T. J. Foster, Shenandoah, Penn. 
 
INDEX. 
 
 Accidents in mines, 73. 
 causes of, 96. 
 prevention of, 92. 
 decrease of, 93. 
 Acceleration of gravity, 22. 
 Action of choke-damp, 11. 
 of white-oamp, 12. 
 of fan and furnace, 112. 
 Adding airways, 82. 
 Adjustable fan-shutter, 116. 
 After-damp, 11. 
 Air, properties of, 1. 
 height of, 2. 
 weight of, 3. 
 analysis of, 3. 
 to find weight of, 19. 
 expansion of, 19. 
 motion of, 23. 
 boxes, 70. 
 return, 73. 
 stoppings, 74. 
 splitting, 76. 
 
 common pressure, in mines, 
 of, 85. 
 
 Air for sanitary purposes, 90. 
 measurements, 97. 
 quantity per horse, 91. 
 quantity per lamp, 91. 
 quantity per man, 128. 
 Airways, perimeter of, 42. 
 
 sectional area of, 42. 
 different lengths of, 59. 
 addition of, 85. 
 enlargement of, 92, 97. 
 Anemometers, 99. 
 
 varieties of, 99. 
 Aneroid barometer, 105. 
 Area, 42. 
 
 and quantity, 61. 
 Arnold, Mr., 98. 
 Asphyxia, treatment of, 130. 
 Atkinson, Sir John, 47, 49. 
 Atmosphere, thickness of, 1. 
 pressure of, 2. 
 variations of, 27. 
 Barometer, discovery of, 2. 
 
 correction for, 104. 
 use of. 106. 
 
136 
 
 INDEX. 
 
 Barometer, sudden fall, 106. 
 Belgium Commission, 37. 
 Bends in airways, 41, 79. 
 Berad, 4. 
 Black-damp, 9. 
 Black Hole of Calcutta, 9. 
 Blood, circulation of, 9. 
 Blowers, 15, 76. 
 Blown-out shots, 94. 
 Boty safety-lamp, 36. 
 Box, Mr., 129. 
 Brattice, wooden, 69. 
 
 cloth, 70. 
 
 Briam's anemometer, 100. 
 Buddie, Mr., 30, 76. 
 Candles in mines, 30. 
 Carbonic acid in atmosphere, 1. 
 
 exhaled, 8. 
 
 composition of, 9, 90. 
 
 diffusion of, 10. 
 
 properties of, 10. 
 
 sources of, 10. 
 
 fatal nature of, 11. 
 Carbonic oxide, 12. 
 
 fatal effects of, 13. 
 Centrifugal ventilators, 110, 115. 
 Changes of temperature, 28. 
 Champion ventilator, 111. 
 Chesterfield and Derbyshire Insti- 
 tute of Mining Engineers, 113. 
 Choke-damp, 9. 
 Circular airways, 43. 
 Clanny safety-lamp, 31. 
 Coal-dust in dry mines, 95. 
 
 Coal-dust explosions, 94. 
 Co-efficient of friction, 47. 
 "Colliery Guardian," 94. 
 Colliery warnings, 108. 
 Comparative economy of furnace 
 
 and fan, 117. 
 Comparison of fans, 111. 
 
 of air and gases, 4. 
 Composition of air, 3. 
 
 of black-damp, 9. 
 of white-damp, 12. 
 of sulphuretted hy- 
 drogen, 13. 
 of fire-damp, 14. 
 Compressed air in mines, 69. 
 Contractions in Airways, 97. 
 Correction for anemometer, 100. 
 
 for barometer, 104. 
 Cost of ventilation, 91, 118. 
 
 by fan, 92, 118. 
 by furnace, 92, 
 
 118. 
 
 Darlington's testimony, 37. 
 Davy's experiments, 15. 
 
 lamp, 32. 
 
 Daubisson, M., 53. 
 Defective ventilation, 10, 17, 73. 
 De la Roche, M., 4. 
 Deputy lamp, 37. 
 Design of ventilation, 97. 
 Detection of fire-damp with can- 
 dle, 30. 
 
 Detection of fire-damp with safety- 
 lamp, 39. 
 
INDEX. 
 
 137 
 
 Diagram of engine, 101. 
 Dip ventilation, 28. 
 Discharge through pipes, 54. 
 
 through thin plates, 54. 
 of gas, 95. 
 
 Distribution of air, 73, 84. 
 Division of air, 77. 
 Doors, 74. 
 Drag in mines, 44. 
 Drift measurements, 102. 
 
 ventilation, 69. 
 Dunn, Mr., 129. 
 Duty of miners, 92. 
 Economy of furnace and fan, 120. 
 
 of splits, 80. 
 
 Effective horse-power, 103. 
 Efficient ventilation, 96. 
 Efficiency of fan, 109. 
 
 of furnace, 109. 
 Eloin safety-lamp, 36. 
 Enlargement of airways, 92, 97. 
 Estimating air for mines, 88. 
 Expansion of gases, 19. 
 Experiments with anemometer, 99. 
 with fan and furnace, 
 
 117. 
 
 with fire-damp, 15. 
 with safety-lamps, 37, 
 
 38. 
 Explosions, 92. 
 
 indications of (theo- 
 ry), 108. 
 Face-airing, 71. 
 Fan, impediments to, 28. 
 
 Fan, hand, 69. 
 
 economy of, 92, 118. 
 drift, 103, 112. 
 Guibal, 115. 
 Waddle, 116. 
 useful effect of, 116. 
 sizes of, 117. 
 shutter, 117. 
 experiments, 119. 
 Faraday's estimates, 7. 
 Fire-damp, 14. 
 
 Davy on, 15. 
 discharges of, 16. 
 detection of, 39. 
 Fire-proof brattice-cloth, 70. 
 Force, estimation of, 44. 
 Formula for cubic foot of air, 
 
 20. 
 
 for total pressure, 50. 
 for pressure, 50. 
 for motive-column, 26, 51. 
 for water-gauge, 52. 
 for quantity, 52. 
 for units of work, 52. 
 for horse-power, 52. 
 Formulas, 49, 121. 
 Foster, T. J., 129. 
 Frankland, Dr., 3. 
 Free fall, 22. 
 Friction, 41. 
 
 and area, 43. 
 co-efficient of, 47. 
 to overcome, 44. 
 and pressure, 59. 
 
138 
 
 INDEX. 
 
 Friction and power, 55. 
 
 dependent on, 59. 
 and velocity, 61. 
 and water-gauge, 68, 112. 
 Furnace, principle of, 24. 
 position of, 24. 
 power of, 27. 
 economy of, 92, 118. 
 danger of, 109. 
 Galileo, 2. 
 Galloway Royal Society's Journal, 
 
 39. 
 
 Gases, specific gravity of, 4. 
 nitrogen, 5. 
 oxygen, 7. 
 carbonic acid, 9. 
 oxide, 12. 
 
 hydrogen sulphide, 14. 
 marsh-gas, 14. 
 hydrosulphuric-acid gas, 14. 
 proto - carburetted hydro- 
 gen, 14. 
 light carburetted hydrogen, 
 
 14. 
 
 hydride of methyl, 14. 
 expansion of, 19. 
 chief characteristics, 19. 
 Gay-Lussac, 53. 
 Goodwin, Mr., 128. 
 government warnings, 108. 
 Gravity, action of, 22. 
 Guibal, M., experiments of, 99. 
 fan experiments, 113. 
 fan, 115. 
 
 Guibal, M., fan in United States, 
 
 117. 
 
 chimney, 116. 
 Gunpowder, 94. 
 Gunpowder, charge of, 96. 
 
 use of, 96. 
 Hall's lamp, 36. 
 
 report, 94. 
 Hand fans, 69. 
 Head of air, 25. 
 Headings, 72. 
 Heart, action of, 9. 
 Heat of shafts, 24. 
 Hedley, Mr., 129. 
 Horse-power, 52. 
 
 effective, 103. 
 
 nominal, 103. 
 Hot air, 23. 
 Howe, R., 113. 
 Hutch inson, Mr., 128. 
 Hydrosulphuric-acid gas, 14. 
 Improvements in safety-lamps, 34. 
 Illuminating power of, 36. 
 Improvements in ventilation, 73. 
 
 in fans, 110. 
 
 Indicated horse-power, 101. 
 Indicator-cards, 103. 
 Inertia, 41. 
 Influence of air, 5. 
 Injustice to men, 96. 
 Inspectors, 92. 
 Irregular airways, 85. 
 Large airways, 92. 
 Laughing-gas, 6. 
 
INDEX. 
 
 139 
 
 Laws of air in mines, 53. 
 
 of ventilation, 92. 
 Le Blanc, 10. 
 Liability of miner, 93. 
 Limits of velocity, 89. 
 Lundhill, 73. 
 Lungs, action of, 8. 
 
 capacity, 130. 
 
 Measurements of air by anemome- 
 ter, 99. 
 fan, 101. 
 of air, 97. 
 
 Mackworth, H., 129. 
 Magnus, 53. 
 
 Managers' ignorance, 92. 
 Maps of ventilation, 4. 
 Mariotte's law, 2. 
 Marsh-gas, 15. 
 
 properties of, 15. 
 explosive mixtures, 15. 
 Mercury, weight of, 15. 
 Meyer, Dr., 12. 
 Miners' asthma, 11. 
 Mines with one orifice, 69. 
 with two orifices, 72. 
 Momentum, 41. 
 Morison safety-lamp, 38. 
 Motive-column, 25. 
 
 calculation of, 27. 
 Movement of air, 23, 43. 
 Mueseler lamp, 35. 
 Murphy fan, 111. 
 Natural ventilation, 23. 
 Nitrogen, 5. 
 
 Nitrogen compounds, 6. 
 Nixon ventilator, 110. 
 Nominal horse-power, 103. 
 North of England Institute, 38, 116. 
 Oxygen, 7. 
 
 necessity of, 8. 
 
 consumption of, 9. 
 
 starvation, 11. 
 Orifice of discharge, 54. 
 Parish safety-lamp, 36. 
 Peclet, 53. 
 
 Pennsylvania mine laws, 129. 
 Perimeter, 42. 
 Permanent stoppings, 74. 
 Phillips, Professor, 129. 
 Pneumatic paradox, 26. 
 Poisonous gases, 10, 12, 13. 
 Position of downcast, 24. 
 
 of fan, 28. 
 
 of upcast, 28. 
 
 of furnace, 24, 28. 
 Power of winds, 29. 
 
 increase of, 56. 
 ventilating, 55. 
 Pressure of air, 2, 85. 
 
 and water-gauge, 46. 
 
 total, 50. 
 
 per square foot, 50. 
 
 ventilating, 54. 
 
 defined, 55. 
 
 and length, 57. 
 
 and perimeter, 57. 
 
 and area, 58. 
 
 and friction, 59. 
 
140 
 
 INDEX. 
 
 Pressure and volume, 61. 
 Prevention of explosions, 92. 
 Problems, 124. 
 Properties of air, 40. 
 Proto-carburetted hydrogen, 14. 
 Quantity, formula for, 52. 
 and area, 61. 
 and development, 76. 
 for mines, 88. 
 Rebreathing air, 9, 91. 
 Regnault, 53. 
 Regulators, 74, 76. 
 
 to find size of, 83. 
 Reports of North of England Ins- 
 titute of Mining Engin- 
 eers, 38. 
 of Belgium Commission, 
 
 37. 
 
 of Chesterfield and Derby- 
 shire, 113. 
 of Mr. Hall, 94. 
 of N. Wood, 37. 
 Resistances to circulation, 23. 
 Richardson's estimate, 91. 
 Risca, 73. 
 Rubbing-surface, 42. 
 
 and friction, 47. 
 Safety-lamps, discovery of, 31. 
 improvements, 34. 
 varieties, 34, 93. 
 illuminating power 
 
 of, 36. 
 
 reports on, 37, 38. 
 use of, 39. 
 
 Scientific ventilation, 88. 
 Single air currents, 77. 
 Shaft, ventilation of, 24, 69. 
 
 temperature of, '24. 
 
 position of, 28. 
 Shot-firing, 96. 
 Sliding shutters, 76. 
 Specific gravity, 4. 
 Spiral fan casing, 117. 
 Splitting the current, 76. 
 
 advantages of, 79. 
 effect of, 82. 
 
 South Shields Committee, 37. 
 Steam- jets, 28, 109. 
 Steel mill, 31. 
 Stephenson, Sir George, 32. 
 
 lamp of, 32. 
 Stoppings, 74. 
 Struve ventilator, 110. 
 Stythe, 9. 
 
 Sulphuretted hydrogen, 13. 
 Sulphuric-acid gas, 14. 
 Sulphuric ether, 98. 
 Table for specific gravity, 4. 
 
 for weight of air, 21. 
 
 for velocity of winds, 29. 
 
 for water-gauge, 46. 
 
 for square root of water- 
 gauge, 68. 
 
 for air pressure, 107. 
 
 for Guibal fan experiments, 
 
 115. 
 
 Tarred brattice-cloth, 70. 
 Temperature, variation of, 2, 27. 
 
INDEX. 
 
 141 
 
 Temperature and friction, 48. 
 
 and barometer, 106. 
 Temporary ventilation, 70. 
 Thick seams, advantage of, 96. 
 Thomas, J. W., 10, 16, 49. 
 Throat of fan, 117. 
 Torricelli, 2. 
 Total pressure, 50. 
 Units of work, 52. 
 Upcast shafts, 24, 28. 
 Useful effect of air-boxes, 71. 
 of engines, 103. 
 of fan, 101, 116. 
 Velocity of air, 29. 
 
 theoretical, 23, 47. 
 and head, 47. 
 and pressure, 54. 
 and friction, 61. 
 Vena contracta, 54. 
 Ventilation, 23. 
 
 natural, 24, 69. 
 furnace, 24. 
 laws of, 53. 
 pressure of, 54. 
 power, 55, 103. 
 shaft, 69. 
 drift, 69. 
 
 cost of increasing, 77. 
 economy of, 88. 
 
 Ventilation, cost of 91. 
 
 of fiery mines, 90. 
 arrangements for, 91. 
 measurement of, 97. 
 mechanical, 110. 
 water-fall, 110. 
 Volume and pressure, 53, 61. 
 and length, 59. 
 and area, 60. 
 and perimeter, 60. 
 and rubbing-surface, 60. 
 Water-gauge, 44. 
 
 use of, 45. 
 as a check, 45. 
 and pressure, 46, 68. 
 formulas for, 52. 
 table of, 68. 
 and fans, 112. 
 Weight of mercury, 3. 
 
 of black-damp, 9. 
 of fire-damp, 14. 
 of air, 19. 
 of water, 44. 
 White-damp, 12. 
 Williamson's lamp, 36. 
 Winds an impediment, 28. 
 
 velocity and power of, 29. 
 Wood, Mr. N., 37. 
 
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