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Modern Tunneling 
 
 With Special Reference to 
 Mine and Water- Supply 
 ===== Tunnels : 
 
 DAVID W. BRUNTON 
 
 AND 
 
 JOHN A. DAVIS 
 
 FIRST EDITION 
 FIRST THOUSAND 
 
 NEW YORK 
 
 JOHN WILEY & SONS 
 
 London: CHAPMAN & HALL, Limited 
 
 1914 
 
,■2.2 
 
 Copyright, 1914 
 By DAVID W. BRUNTON and JOHN A. DAVIS 
 
 Ifl 
 
 )/|i/^n 
 
 /j 
 
 r" 
 
 PRESS OF THE PUBLISHERS PRINTING COMPANY, NEW YORK, U.S.A. 
 
 ^«C 21 1914 
 
 ©CI,A379180 
 
CONTENTS 
 
 PAGE 
 
 Chapter I. 
 
 Introduction 1—4 
 
 Purpose of book i 
 
 Scope of book 2 
 
 Acknowledgments 3 
 
 Chapter II. 
 
 The history of tunneling 5~34 
 
 Tunnels driven by hand drilling 12 
 
 Mining and water tunnels driven by machine drilling . . 19 
 
 Railway tunnels 24 
 
 Chapter III. 
 
 Modern mining and water tunnels 35"~52 
 
 Resume of data 35 
 
 Modern tunnels described in engineering magazines ... 49 
 Chapter IV. 
 
 Choice of power for tunnel w^ork 53—79 
 
 Sources of power 53 
 
 Production of power ' ... 54 
 
 Water power 54 
 
 Steam 58 
 
 Internal-combustion 58 
 
 Electric motors 64 
 
 Transmission of power 64 
 
 Choice of power 65 
 
 Duration of plant 65 
 
 Accessibility . 66 
 
 Cost of installation 66 
 
 Labor ' 74 
 
 Fuel consumption 74 
 
 Thermal efficiency 75 
 
 Purchase of current 76 
 
 Interest and depreciation 77 
 
 Conclusions 78 
 
 Chapter V. 
 
 Air compressors 80—110 
 
 Power required 81 
 
 Capacity 82 
 
 Types 85 
 
 Straight line 85 
 
 Duplex 88 
 
 Turbo-compressors 91 
 
 Comparisons 94 
 
IV CONTENTS 
 
 Chapter V. 
 
 Air compressors — (Continued) page 
 
 Regulation 97 
 
 Steam driven 97 
 
 Water driven 98 
 
 Electrically driven 99 
 
 Heat loi 
 
 Heat produced loi 
 
 Dangers of high temperatures loi 
 
 Removal of heat 102 
 
 Intercooling 104 
 
 Moisture 104 
 
 Accessories 106 
 
 Precoolers 106 
 
 Aftercooling 106 
 
 Air receivers 107 
 
 Drains ' . . . 108 
 
 Conclusions 109^ 
 
 Chapter VI. 
 
 Ventilation 1 11— 124 
 
 Machinery . ill 
 
 Direction of current 1 13 
 
 Capacity 115 
 
 Pressure .118 
 
 Size of pipe 121 
 
 Comparison of fans and blowers 122 
 
 Conclusion 123 
 
 Chapter VH.. 
 
 incidental surface equipment 125—129 
 
 Drill sharpening machines 125 
 
 Air meters 127 
 
 Chapter VH I. 
 
 Rock-driUing machines 130—162 
 
 Types 130 
 
 Pneum.atic drills 130 
 
 Hydraulic drills 138 
 
 Electric drills 141 
 
 Gasoline drills 147 
 
 Merits of each type 147 
 
 Pneumatic drills 147 
 
 Hydraulic drills 157 
 
 Electric drills 157 
 
 Choice of drills i6a 
 
 Chapter IX. 
 
 Haulage 163-180 
 
 Tunnel cars 163 
 
 Loading machines 170 
 
 Motive power I73 
 
 Dumping devices 17S 
 
CONTENTS V 
 
 Chapter X. page 
 
 Incidental underground equipment 181—209 
 
 Tunneling machines 181 
 
 List of tunneling machine patents 188 
 
 Illumination 201 
 
 Telephones 205 
 
 Incidentals 207 
 
 Chapter XL 
 
 Drilling methods . 208—235 
 
 Number of shifts 209 
 
 Mounting 212 
 
 Number of holes 218 
 
 Direction of holes 221 
 
 Depth of holes 229 
 
 Chapter XI L 
 
 Blasting 236—259 
 
 Ammunition 236 
 
 Loading 248 
 
 Firing 254 
 
 Storing 257 
 
 Thawing 258 
 
 Chapter XI I J. 
 
 Methods of mucking 260-269 
 
 Number of men 260 
 
 Positions of working 261 
 
 Handling cars 263 
 
 Use of steel plates 267 
 
 Chapter XIV. 
 
 Timbering 270—288 
 
 Materials 270 
 
 Types 273 
 
 Chapter XV. 
 
 Safety ' 289-327 
 
 Causes of accidents 290 
 
 Falls of roofs 290 
 
 Use of explosives 292 
 
 Premature explosions 296 
 
 Misfires 299 
 
 Suffocation by gases from explosives 303 
 
 Suffocation by gases from other sources 305 
 
 Haulage 309 
 
 Electricity 311 
 
 Fire 313 
 
 Water 315 
 
 Intoxication 318 
 
 Prevention of accidents 318 
 
 Precautions for the manager or superintendent . . .319 
 
 Precautions for the foreman 321 
 
 Precautions for the miner * . . 324 
 
CONTENTS 
 
 Chapter XVI. page 
 
 Cost of tunnel work 328—359 
 
 Coronado tunnel 329 
 
 Gunnison tunnel 331 
 
 Laramie-Poudre tunnel 332 
 
 Los Angeles Aqueduct . . . • 333 
 
 Ivucania tunnel 343 
 
 Marshall- Russell tunnel 344 
 
 Mission tunnel 345 
 
 Newhouse tunnel 346 
 
 Rawley tunnel 347 
 
 Roosevelt tunnel 348 
 
 Stihvell tunnel 352 
 
 Strawberry tunnel 353 
 
 Chapter XVII. 
 
 Bibliography ■. 360-419 
 
 Tunnel descriptions 360 
 
 Water power 369 
 
 Steam power 371 
 
 Internal-combustion power 373 
 
 Electric power 378 
 
 Com^pressed-air power , . . . . 380 
 
 Power transmission 381 
 
 Choice of power . 382 
 
 Power plant descriptions 382 
 
 Air compressors 385 
 
 Compression of air . 388 
 
 Compressed-air accessories 391 
 
 Ventilation 393 
 
 Air drills 394 
 
 Hydraulic drills 395 
 
 Electric drills 396 
 
 Drilling accessories 397 
 
 Haulage 398 
 
 Tunneling machines 401 
 
 Illumination 402 
 
 Methods of tunnel driving 402 
 
 Drilling methods 405 
 
 Blasting methods 406 
 
 Blasting supplies 408 
 
 Mucking 411 
 
 Timbering 411 
 
 Speed records 412 
 
 Safety and health 414 
 
 Costs 418 
 
 Chapter XVIII. 
 
 Appendix 421-426 
 
 Outline of tunnel data 421 
 
CHAPTER I 
 
 INTRODUCTION 
 
 PURPOSE OF BOOK 
 
 Up-to-date information concerning tunneling methods is 
 difficult to obtain. There are but few books on the subject, 
 and much of the material they contain, although it is very 
 interesting and valuable historically, is now obsolete. The 
 engineering periodicals, it is true, endeavor to keep abreast of 
 the times and there are several of which scarcely an issue ap- 
 pears without some article bearing upon tunnel work. But the 
 very multiplicity of these magazines prevents one from reading all 
 of them regularly, and the foreman or superintendent in charge 
 of a tunnel, or the mining engineer designing one, and especially 
 the business man financing the project, has no time for a labo- 
 rious search after scattered articles in order to determine the 
 present status of tunnel work. Then, too, knowledge of new 
 methods travels slowly. Inventions and improvements of 
 definite and practical value in mining as well as all the other 
 industries, and important discoveries in science, frequently 
 remain in the note-book of the investigator, or, as theses, are 
 buried in university Hbraries or may be published only in the 
 very locally distributed journals of small scientific societies. 
 In biology, the work of Mendel on heredity (whose experiments 
 in his cloister-garden are the foundation of a new conception 
 of the nature of living things on the part of biologists, which 
 bids fair to exert an influence not less than that associated with 
 the name of Darwin), although published locally by him in 1865, 
 remained unknown to the scientific world until its simultaneous 
 discovery by three independent workers in 1900. In astronomy, 
 the invention of the achromatic lens, without which the modern 
 telescope would not be possible, by John Dolland in 1758, was 
 antedated some twenty-five years by the investigations of Chester 
 Moore Hall. So also in tunneling, up-to-date methods and equip- 
 
 1 
 
2 MODERN TUNNELING 
 
 ment that are proving safe, efficient, and economical may be 
 totally unknown outside the district in which they originate. 
 This book is intended to supply, if possible, such data concerning 
 timneling methods in the United States, and to make suggestions 
 that, it is hoped, may result in a saving to the mining industry 
 of life, energy, and capital that would otherwise be expended for 
 inefficient or useless work. 
 
 In most of the pubhshed accounts of tunnel work, the writers 
 usually do not attempt to criticise the methods they are de- 
 scribing. It is customary for such articles to contain accurate 
 descriptions of equipment, various phases of working operations, 
 and occasionally figures showing the cost of the work, but rarely 
 do they include a discussion of the means for preser\ing the 
 health and Kfe of the employees, or data bearing upon the choice 
 and efficiency of equipment or an analysis of methods and costs. 
 As a result, the reader in drawing conclusions is dependent 
 wholly upon his own resources. In this volume, on the con- 
 trary, the making of such analyses will be a primary considera- 
 tion. It is desirable, nevertheless, in an impartial, disinterested 
 book of this character to use constructive rather than destruc- 
 tive criticism. For that reason emphasis will be placed upon 
 safe, efficient, and economical methods, and upon good points 
 of equipment, while bad practice and obsolete machinery will 
 be ignored except, perhaps, as examples of the inadvisable or as 
 they have some bearing historically. Thus the authors hope to 
 set forth a guide for future work rather than an unillumined 
 record of past or present achievement. 
 
 SCOPE OF BOOK 
 
 This book will be confined chiefly to tunnels and adits* 
 for mining purposes, such as drainage, transportation, or de- 
 velopment, but it will also include those which are used to carry 
 water for power, irrigation, or domestic use, in which the essential 
 
 * It has been suggested by prominent authorities that the word " tunnel " 
 be restricted to the designation of such nearly horizontal passageways as 
 extend completely through a mountain or hill from daylight to daylight, and 
 
INTRODUCTION 3 
 
 features are practically identical with mine tunnels. Tunnels 
 of this sort are generally driven through at least fairly hard rocks 
 in contrast to ordinary soil, quicksand, and other heavy material 
 of a treacherous nature, and they are practically never driven 
 through modern river-bed deposits. It will not be necessary, 
 therefore, to consider the special methods and equipment for 
 tunnel work in such materials. A distinction will be made be- 
 tween tunnels or adits for which the excavation is wholly or in 
 a large part in material containing no ore and those which follow 
 the vein through any irregularity in direction. As far as possible, 
 the discussion will be Hmited to the former, because in the latter 
 instance the methods employed in driving along a vein are 
 usually more akin to the distinctive operations for removing ore, 
 and are, therefore, not so apt to be good examples of tunnel 
 practice. 
 
 ACKNOWLEDGMENTS 
 
 In the preparation of this book valuable assistance has 
 been received from numerous sources. The writers are deeply 
 indebted to the officials of the New York Board of Water Supply, 
 of the Los Angeles Aqueduct, of the United States Reclamation 
 Service, and the Bureau of Mines, and to the officers, managers, 
 superintendents, and foremen at the different tunnels, for favors 
 granted, for information suppHed, often at no Httle inconvenience, 
 and, above all for that hearty co-operation which has been an 
 unfaiHng source of inspiration. Many thanks, also, are due the 
 
 the words "adit" and "drift" be used only for similar galleries which enter 
 from the surface and serve to drain a mine or furnish an exit from the work- 
 ings, but do not continue entirely through the hill. Such definition is eminent- 
 ly desirable from a strict technical viewpoint and would undoubtedly result 
 in a much to be desired precision of diction, but, although it was proposed 
 over thirty years ago and the suggestion has been repeated several times 
 since, it has been found difficult, if indeed possible, to establish it practically. 
 The American usage of referring to any horizontal gallery as a tunnel, without 
 considering its extent completely through a hill or not, is so firmly fixed in 
 our mining literature (being used by authors and editors alike), and among 
 practical mining men generally in this country, and is even embodied in the 
 United States mining laws, that the proposed restriction has been thought 
 scarcely justifiable in a practical work of this character. 
 
4 MODERN TUNNELING 
 
 manufacturers of equipment and materials used in tunnel work 
 for their promptness and courtesy in furnishing catalogues, 
 data of tests, and similar material, and in supplying photo- 
 graphs, blue-prints, and cuts, which have been of great assis- 
 tance in the preparation of many of the illustrations in this 
 volume. Obligation is also acknowledged for many valuable 
 suggestions obtained from articles in engineering periodicals 
 and from books on tunneHng and related subjects. 
 
CHAPTER II 
 THE HISTORY OF TUNNELING 
 
 The art of excavating underground passageways has been 
 known to mankind for many centuries. The ancient Egyptians 
 and Hindus employed it in the creation of many wonderful 
 subterranean temples and sepulchers in hard rock, and similar 
 monuments are found in the works of the Hebrews, Greeks, 
 Etruscans, Romans, Aztecs, and Peruvians — in fact, of all 
 ancient civilized peoples. 
 
 It is not surprising that the Egyptians, with their wonderful 
 knowledge of quarrying as well as many other useful arts, 
 should have been versed in methods of underground rock ex- 
 cavation. Remains of their work, some of which dates back 
 to 1500 B.C., may be found in the grottos of Samoun, the tombs 
 near Thebes and Memphis, the catacombs of Alexandria, and 
 the temples of Ipsamboul. A gigantic tomb has been found at 
 Abydos, which was cut in the solid rock during the Twelfth 
 Dynasty by Senwosri III.; also Rameses II., who is perhaps the 
 best-remembered personage of these ancient times, constructed, 
 either because of vanity or the great length of his reign, many 
 rock-cut temples, the grandest of which is probably that of Abu 
 Simbel. 
 
 The work was performed with hand tools, and the labor neces- 
 sary to have fashioned monuments of such magnitude and 
 grandeur must have been stupendous. For cutting granite 
 and other hard rock, the workmen used saws of copper which 
 were either fed with emery powder or were set with teeth of that 
 abrasive. A similar method was employed as early as the Fourth 
 Dynasty for circular holes which were drilled by a tube having 
 fixed teeth, or which was fed with emery powder. For removing 
 rock in a quarry or in a tunnel, grooves varying in width from 
 4 to 20 inches were made on four sides of a block, which was then 
 
 5 
 
b MODERN TUNNELING 
 
 broken out by the swelling action produced by soaking with 
 water a number of wooden wedges driven into these grooves. 
 
 The excavations in India probably number at least a thousand, 
 the majority of which are of Buddhist origin. They are usually 
 of two types — chapels and monasteries. The former consist of 
 a nave with a vaulted roof, separated from the side aisles by 
 columns, and containing a small chapel at the inner circular end. 
 The latter consist of a hall surrounded by a number of cells for 
 the residence of monks and ascetics. 
 
 Most of the Indian excavations are of much later date than 
 those in Egypt. The earHest, the Sudama, or Nigope, cave, was 
 constructed probably about 260 B.C.; the Lomas Rishi was built 
 about 200 B.C., and those of Nassick about 129 B.C. These 
 earlier caves imitated very closely contemporaneous timber- 
 roofed, temples, and for this reason the columns all slope inward, 
 copying with great fidelity of detail the rafter supports of the 
 wooden temples. In the KarH caves (about 78 B.C.) this feature 
 is absent; the columns of the nave are quite plumb and the per- 
 fection of architecture and ornamentation is unsurpassed by any 
 of the later Hindu rock-temples. The galleries and rooms of 
 the caves of EUora contain a total of nearly five miles of sub- 
 terranean work. Although the builders may possibly have 
 known of gunpowder, it was not used in the construction of these 
 tunnels, which, like all the preceding works, were accomplished 
 laboriously with hand tools and probably by slave labor. The 
 caves of Salsette belong to the sixth century a.d., while those at 
 Elephanta were constructed about 800 and the Gwalior temples 
 were excavated still later during the fifteenth century. 
 
 Modern archaeological investigation indicates that tunneling 
 was possibly known to the Minyae, an ancient Grecian people 
 dating back beyond 2000 B.C., whose cycle of myths includes, 
 among others, that of the Argonautic Expedition. A series of 
 shafts, sixteen in all, are to be seen near Lake Kopais in Boeotia, 
 which are supposed to have been constructed by these peoples 
 for the ventilation of an ancient drainage tunnel. The shafts 
 are 200 to 1,000 feet apart, 6 to 9 feet wide, and have a maxi- 
 mum depth of 100 feet. The tunnel was probably the enlarge- 
 
THE HISTORY OF TUNNELING 7 
 
 ment of a natural watercourse such as are commonly found in 
 similar calcareous rocks. Krates of Chalcis, a mining engineer 
 who Hved in the time of Alexander the Great, is credited his- 
 torically with an attempt to drain this lake by utilizing and 
 enlarging natural watercourses. 
 
 Although the exact date of the introduction of mining into 
 Attica, probably from the Orient, is unknown, it seems to have 
 been subsequent to the time of Solon (about 600 B.C.). By 489, 
 it is certain that the silver mines of Laurium were yielding a 
 highly satisfactory return, and at the instigation of Themis- 
 tocles, the net profits from them were applied by the Athenians 
 to the construction of a fleet, so that these mines no doubt con- 
 tributed largely to the prosperity and power of Athens. The 
 workings, approximately two thousand in all, consisted of shafts 
 and galleries in which the rocks were hewn out with hand tools 
 and brought to the surface on the backs of slaves. Air was 
 supplied to the large underground stopes or chambers by venti- 
 lating shafts about 6 feet square and from 65 to 400 feet deep. 
 
 Gold was mined in Macedonia and Thrace at least as early as 
 the fifth century B.C., and Herodotus mentions a tunnel in the 
 island of Samos built in the sixth century, which was 8 by 8 feet 
 in cross-section, and nearly a mile long. 
 
 The Aztecs were well acquainted with mining, and they 
 secured copper from the mountains of Zactollan, while the mines 
 of Tasco furnished silver, lead, and tin; and the extensive gal- 
 leries and other traces of their labor were of great assistance to 
 the early Spanish miners. With no knowledge of iron, although 
 iron ore was very abundant, their best tools were made of an 
 excellent substitute in the form of an alloy of copper and tin. 
 With tools of this bronze, they could- not only carve the hardest 
 metals, but with the aid of powdered siKca they could cut the 
 hardest minerals, such as quartz, amethyst, and even emerald. 
 
 Although the mines of the ancient Peruvians were little more 
 than caverns excavated in the steep sides of mountains, never- 
 theless they knew of the art of tunneling, as is shown by tunnels 
 of their aqueducts and by the extensive tunnel which they built 
 to drain Lake Coxamarco. They, too, had no knowledge of 
 
8 MODERN TUNNELING 
 
 iron, and their tools were made of an alloy of copper and tin, 
 which they probably discovered quite independently of the 
 Aztecs, whom they rivaled also in the cutting of gems. 
 
 The Romans, however, were undoubtedly the greatest tunnel- 
 builders of early history. They drove tunnels for passage, 
 drainage, water supply, and mining, not only in Italy, but wher- 
 ever their conquests led them, as is evidenced both by records 
 and by old workings left behind in the countries they dominated. 
 One hardly needs to mention the numerous aqueduct tunnels and 
 sewers of the ancient city of Rome, some of which are in use 
 to-day, attesting the abihty of the Romans in this branch of 
 engineering. Remains of their work, many of them remarkably 
 well preserved, have been found in France, Switzerland, Portu- 
 gal, Spain, Algiers, and even Constantinople. 
 
 Their tunnels were of no mean size. A road tunnel near 
 Naples constructed, according to Strabo, about ^6 B.C., was 
 approximately 4,000 feet long, 30 feet high, and 25 feet wide. 
 About 359 B.C., Lake Albanus, which lies about fifteen miles 
 southeast from Rome, was tapped for its supply of clear water 
 by a tunnel over a mile long, 8 feet high, and 5 feet wide. 
 Possibly the greatest Roman tunnel was' driven by the Emperor 
 Claudius to drain the overflow waters from Lake Fucinus, 
 which is situated about seventy-five miles nearly due east of 
 Rome and has no natural means of outlet. This tunnel, com- 
 pleted in 52 A.D., after eleven years' labor, is over three miles 
 long, and was designed to be 19 feet high and 9 feet wide; but 
 it appeared to have been even larger than this when, in 1862, 
 it was reopened to secure valuable land beneath the lake. 
 
 These works seem all the more marvelous when one considers 
 the primitive methods available at that time. Explosives were 
 unknown, and machinery was not then used in mining. Rock 
 openings were usually made by chipping, by channeling and 
 wedging, as in Egypt, or by cutting large grooves around the 
 block to be excavated, using hand tools made of iron, copper, 
 and bronze, although it is quite possible that for certain classes 
 of stone-cutting, diamonds or some similarly hard minerals were 
 employed in conjunction with primitive tube-drills and saws. 
 
THE HISTORY OF TUNNELING 
 
 These methods were often supplemented by fire-setting, a method 
 chiefly employed, however, in the large chambers or stopes, 
 and not well adapted for driving small tunnels. It consists 
 simply of heating the rock to a very high temperature and 
 quenching suddenly with water (or sometimes with vinegar in 
 calcareous rocks), producing shattering and disintegration be- 
 cause of sudden con- 
 traction. Many writ- 
 ers have described the 
 intense and fearful 
 sufferings of men en- 
 gaged in this work, 
 usually slaves and 
 prisoners of war who 
 perished by the thou- 
 sands — a fact, how- 
 ever, of little concern 
 to the ancient builders. 
 The value of Spain 
 as a storehouse of 
 precious metals, oft- 
 setting somewhat the 
 influence of Eastern 
 wealth, was well ap- 
 preciated by Roman 
 leaders, and an armed 
 force for the pro- 
 tection of the mines 
 was maintained there 
 constantly, in many 
 
 cases at the cost of serious political and financial embarrass- 
 ment at home. In southern Spain, where the numerous silver 
 and copper mines contained much water, Roman tunnels are 
 very common. They are remarkable for their small size, being 
 usually about 5 feet in height and, where timbered, from 
 i6>^ to 36 inches in width, a fairly typical one being shown in 
 Figure i. This adit, as far as explored, has a length of 1,850 
 
 Fig. I. 
 
 Section of an old Roman adit 
 in hard slate. 
 
10 
 
 MODERN TUNNELING 
 
 JL. 
 
 
 -i-i-i— 
 
 feet and a maximum depth of 183 feet. The timbered openings 
 are even smaller than this, a fair type of them being shown in 
 Figure 2, which gives the dimensions of the openings and the 
 timbers supporting it. The particular tunnel from which this 
 section was taken is 2,300 feet long and 
 has a maximum depth of 215 feet. 
 
 As nearly as can be ascertained to- 
 day from discoveries in them of various 
 objects of interest, including coins, it is 
 certain that these adits must have been 
 driven very early in the Christian era. 
 Toward the latter end of the period in 
 which these particular tunnels were used 
 by the Romans, attempts were made to 
 work the ore bodies below them by rais- 
 ing water from the lower stopes by 
 means of slave-operated water-wheels. 
 
 Since artificial ventilation by means 
 of blowers was at that time unknown, 
 like most of the Roman tunnels, these 
 were ventilated by shafts which were 
 spaced in the tunnel illustrated above 
 at about 25-meter intervals; in order, 
 also, to minimize the depth to which the 
 shafts were sunk, the tunnels corre- 
 sponded very nearly in their course to that of the valleys or 
 gulches above them, instead of being straight, as is the usual 
 modern practice. Like the adits, the ventilating shafts were 
 remarkably small. Where timbered, they were usually about 
 2 feet 10 inches square in the clear, and where the rock would 
 stand without timbering they were circular and generally did 
 not vary much from 2 feet 4 inches in diameter. 
 
 With the fall of the Western Empire, tunnel work in Europe 
 practically ceased for many centuries. Some excavations were 
 made, it is true, for tombs and the crypts of monasteries; and 
 underground passages leading to a secluded exit, to furnish the 
 occupants a means of escape in time of defeat, were a necessary 
 
 Fig. 2. Section of timbered 
 Roman adit. 
 
THE HISTORY OF TUNNELING 11 
 
 part of the equipment of each castle. Crude attempts at mining, 
 also, were practiced in Germany. The Teutonic tribes, whose 
 main occupation was warfare and who were savage, barbarous, 
 and essentially nomadic at the time of the conquests of Juhus 
 Caesar, had probably learned from the Romans the value of gold; 
 later, somewhat tempered and softened possibly by the civiliza- 
 tion they had destroyed, they began to search for precious 
 metals and to pursue other peaceful occupations. 
 
 During the Middle Ages tunneling was devoted almost exclu- 
 sively to the needs of war and was seldom employed for con- 
 structing aqueducts or other public works. There is, however, 
 a record of a road tunnel begun in 1450 by Anne of Lusignan. 
 It was intended to pierce the Alps at an elevation of nearly 
 six thousand feet, and afford better means of communication 
 between Nice and Genoa, but was never completed. Work 
 was subsequently resumed in 1782 by Victor Amadeus III., 
 but was finally abandoned twelve years later, after a total of 
 nearly eight thousand feet of tunnel had been constructed. 
 
 Although gunpowder in Europe, according to the consensus 
 of opinion, was probably invented early in the fourteenth 
 century and by the end of the sixteenth century was very com- 
 monly used in military operations for gunnery and for blowing 
 up fortifications, it was not appHed directly to mining or tunnel 
 operations during this period. Agricola's "Bergwerck Buch" * 
 (published by Basel in 1621), the third edition of "De Re 
 Metallica," pictures. the Roman methods and of hand work and 
 fire-setting as the usual means of mining at that time. 
 
 In the year 1613, Martin Weigel is said to have introduced 
 gunpowder into mining work. Gatschmann describes the use 
 of wooden plugs for tamping at this time, which were later 
 (about 1685) supplanted by clay. August Bayer ('^Das Geseg- 
 nete Markgrafenthum Meissen," 1732) and Henning Calvor 
 (" Nachrichten liber das Berg- und Maschinenwesen am Harze/^ 
 etc.) also confirm the date of 16 13 for the invention of drilling 
 and blasting, but Honemann and. Rossler make it fifteen or 
 
 * A complete English translation is now published. Hoover, H. C, and 
 Hoover, L. H., De Re Metallica, 637 pp., London, 1912. 
 
12 MODERN TUNNELING 
 
 twenty years later. Whatever may have been the date when 
 blasting was first used in mining, it is certain that the practice 
 had become fairly common by 1650, for powder is mentioned 
 as having been purchased for the Harz mines as early as 1634, 
 drill-holes are reported at Diillen, which bear the date of 1637, 
 and blasting is known to have been introduced into the Freiberg 
 district in 1643. 
 
 The use of gunpowder in mining gave a new impetus to that 
 industry which produced a large corps of men trained to over- 
 come the difficulties of underground drifting, and it is not sur- 
 prising therefore to note soon after an increased activity in 
 tunnel work for other purposes. The chief of these allied 
 interests was transportation, and in the eighteenth and early 
 part of the nineteenth centuries a large number of tunnels were 
 driven in connection with the canals, which, aside from wagon 
 roads, were the onl}^ highways at that time. Later the develop- 
 ment of steam railroads and the desirability of maintaining 
 level gradients created a still greater demand for tunnel con- 
 struction. A brief review will be given of the more important 
 tunnels constructed for these purposes, both abroad and at 
 home. 
 
 TUNNELS DRIVEN BY HAND-DRILLING 
 
 The first modern tunnel to be constructed for commercial 
 transportation was the Malpas tunnel on the Languedoc Canal 
 in France. It was 515 feet long, 22 feet wide, and 27 feet high, 
 and was built between 1679 and 1681 * by Riquet, a French 
 engineer. Although this tunnel showed that canals could be 
 constructed through country before thought impassable, further 
 advantage was not taken of this fact in France until nearly a 
 hundred years later, when the Rive de Gier tunnel (1,656 feet 
 long) was constructed on the Givors Canal in 1770, and the 
 Torcy tunnel (3,970 feet long) on the Center Canal was built 
 
 * The writers wish to acknowledge their especial indebtedness to Henry 
 S. Drinker, from whose monumental work on tunneling this and other valuable 
 information concerning the earlier history of tunnel driving has been ob- 
 tained. 
 
THE HISTORY OF TUNNELING 13 
 
 in 1787. The Tronquoy and the Riqueval tunnels on the 
 St. Quentin Canal were started in 1803 and the Noirou tunnel 
 (approximately 39,400 feet in length), on the same canal, was 
 begun in 1822. On the Bourgoyne Canal, the St. Aignan 
 tunnel was started in 1824, so that by the middle of the nine- 
 teenth century nearly twenty canal tunnels in France had 
 been constructed, having an aggregate length of nearly 93,500 
 feet. 
 
 The earliest transportation tunnel in England was the Hare- 
 castle, situated on the Grand Trunk Canal, which was begun in 
 1766 and opened for traffic in 1777. This tunnel was 8,640 feet 
 in length, 9 feet wide, and 12 feet high. There were originally 
 four other tunnels, but of shorter lengths, also on this canal. 
 The Harecastle tunnel was found to be too small to accom- 
 modate the traffic through it, and was replaced in 1824 by a 
 parallel tunnel, which was 16 feet high and 14 feet wide, 4 feet 
 9 inches of this width being used for a tow-path. The Sapperton 
 tunnel on the Thames-Medway Canal was started in 1783. It 
 was approximately 12,500 feet long, and six years were employed 
 in its construction. The next large canal tunnel in England 
 was the BKsworth (9,250 feet long), on the Grand Junction Canal, 
 which was started in 1798, and required seven years for its 
 completion. In 1856 there were over forty-five tunnels on the 
 various EngHsh canals, aggregating some 220,000 feet in length. 
 
 The first canal tunnel in the United States was the Auburn 
 tunnel at the Orwisburg Landing on the SchuylkiU Navigation 
 Canal. The tunnel (which was 450 feet long, 20 feet wide, and 
 18 feet high) was begun in 1818 and opened for trafiic in 182 1. 
 The hill it pierced was composed of red shale, and the highest 
 point was only forty feet above the top of the tunnel. The 
 tunnel was shortened in 1834-37 and again in 1845-6, and was 
 finally taken out altogether in 1855-6 by an open cut. The 
 "Summit Level," or Lebanon Tunnel on the Union Canal, begun 
 in 1824 and finished in 1826, was the second canal tunnel in this 
 country. It was originally 720 feet long, 18 feet wide, and 15 
 feet high, being driven through argillaceous slate at a total 
 cost of $30,464. It was followed by the "Conemaugh" and 
 
14 MODERN TUNNELING 
 
 "Grant's Hill" tunnels on the Western Division of the Pennsyl- 
 vania Canal (1827-30), the Paw-paw tunnel on the Chesapeake 
 and Ohio Canal (1836), and two tunnels on the Sandy and 
 Beaver Canal, Ohio (1836-38). 
 
 The first railroad tunnel of which we have any record was 
 the Terre Noire tunnel, near St. Etienne, France, on the Roanne- 
 Andrezieux horse railroad. This tunnel, which was begun in 
 1826, was 4,920 feet long, 9.8 feet wide, and 16.4 feet high. 
 Some fourteen other tunnels were built on the road from St. 
 Etienne to Lyons between 1826 and 1833. The first tunnels 
 on a railroad using steam locomotives were those on the Liver- 
 pool and Manchester Railway, constructed between 1826 and 
 1830. It was on this road that the famous trial between the 
 "Rocket," "Novelty," and "Sans Pareil" locomotives took 
 place in 1829. The following summary of early railroad tunnel- 
 building in Europe is quoted from Drinker's "Tunneling," 
 page 19. 
 
 '' Tunnels, of course, multiplied rapidly in England with the 
 extension of railways, and during the twelve or fifteen years 
 following the construction of the Liverpool and Manchester 
 Hne, there were a large number of tunnels built throughout 
 the kingdom, among them being the famous Kilsby, Box, and 
 Woodhead tunnels. The first tunnels on a steam railway in 
 France were those built on the St. Germain line in 1837. Sub- 
 quently, the ones on the Versailles, the Gard, and the Rouen 
 lines raised the total length of tunnels in France in 1845 ^^ 
 12,833 m. (42,105 feet). The report of the Corps des Ponts 
 et Chaussees on tunnels for 1856 shows at that date a total on 
 French railroads of 126 tunnels, of a total length of 65,106 
 meters. Among the noted early French tunnels may be cited 
 the Nerthe, Arschwiller, Rilly, La Motte, Lormont, and Alou- 
 ette. In Belgium, the Cimiptieh tunnel, built in 1835, on the 
 Xhemin de FEtat,' seems to have been the earliest. In 
 Germany (Prussia and other States) the earher lines were so 
 located as not to require much tunnel-work; and Oberau tunnel 
 (1839), on the Leipsic-Dresden hne, in Saxony, was the first. 
 In Austria, Rziha gives the Gumpoldskirch tunnel as the 
 
THE HISTORY OF TUNNELING 15 
 
 first. A tunnel at Eriebitz (perhaps the same), on the "North" 
 line, is mentioned in the Fonts et Chaussees Report (above 
 cited) as an early Austrian one. In 1856 there were some fifty 
 tunnels in Austria of a total length of 13,522 meters. In Italy, 
 the Naples-Castelamare line, opened in 1840, had several tun- 
 nels. In 1856, the total Italian tunnels amounted to 10,181 
 metres; the Bologna-Pistoja line is especially remarkable for its 
 semi-subterranean character. Among the early Swiss tunnels, 
 especially to be noted is the Hauenstein, commenced in 1853 
 and finished in 1858.'' 
 
 The first railway tunnel in the United States was constructed 
 on the Allegheny Portage Railroad in Pennsylvania, between 
 1 83 1 and 1833. The tunnel (which was driven through slate) 
 was 901 feet long, 25 feet wide by 21 feet high, and was lined 
 throughout with masonry 18 inches thick. It was followed by 
 the Black Rock tunnel (1835-183 7) on the Philadelphia and 
 Reading Railroad, and the Elizabeth town tunnel (183 5-1 83 8), 
 on what is now the Pennsylvania Railroad; after this time, 
 railroad- tunnel construction became so general that by 1850 
 as many as forty-eight tunnels had been completed on American 
 railways. 
 
 Among the early European mining tunnels driven with gun- 
 powder and hand-drilling, mention should be made of the Tiefe 
 Georg and the Rothschonberger Stollen in Saxony, the Joseph 
 11. Stollen at Schemnitz, Hungary, and the Ernst August Stollen, 
 which was later driven under the Tiefe Georg. A number of 
 tunnels, of which the Taillades tunnel was the most important, 
 were also driven in connection with the Marseilles Aqueduct 
 during this period. 
 
 The Tiefe Georg Stollen* was driven between 1777 and 1799. 
 The total length of the main tunnel is 34,529 feet; its various 
 branches aggregate 25,319 feet more, and yet this immense 
 undertaking, driven entirely by hand, was carried out to obtain 
 a drainage depth of only 460 feet. It passed through graywacke 
 for nearly the entire distance. 
 
 * Drinker, p. 351. 
 
16 MODERN TUNNELING 
 
 Work was commenced on the Joseph II. Stollen, Schem- 
 nitz, Hungary,* in 1782, but owing to various interruptions the 
 tunnel was not completed until 1878. The portal is at Wornitz, 
 on the left bank of the River Gran, about ten miles west of 
 Schemnitz. The tunnel is 10.27 miles long, 9 feet 10 inches high, 
 and 5 feet 3 inches in width, and its cost was $4,860,000. It is 
 used entirely for mine drainage and the annual saving in pirnip- 
 ing amounts to over $75,000. 
 
 The Rothschonberger Stollen f was driven for the purpose of 
 draining the mines of Freiberg, Saxony, and was commenced 
 in 1844 3-nd completed April 12, 1877. The tunnel starts in the 
 Triebisch Valley at Rothschonberg, about 12 kilometers above 
 Meissen on the Elbe. Its length on the line of the original loca- 
 tion to Halsbriicke was 42,662 feet, but as completed to a con- 
 nection with the Himmelfahrt, including its branches, had a 
 total length of 95,149 and a depth below the Anna Stollen of 
 308 feet. Hand-drilling and black powder were used down to 
 the end of 1875, when Burleigh drills were introduced. The 
 work was carried on by the State, and perhaps no better example 
 of the inefficiency of governmental control over industrial enter- 
 prises could be cited than the record of this work. The tunnel 
 was nine feet square and was driven from eighteen headings, 
 yet thirty-three years were required for its completion, the 
 average rate of progress in each of the headings being only about 
 15 feet per month. 
 
 The Ernst August Stollen J was driven below the Tiefe 
 Georg Stollen in 1851-1864. The main tunnel is about 34,218 
 feet long, but the entire length of the adit and its branches is 
 74,452 feet, all driven in rock similar to that in the Georg 
 Stollen quoted above. The tunnel is 11 feet high and 5^ feet 
 wide, driven on a grade of 35.6 feet to the mile. Hand-drilling 
 and black powder were used and, working seven-hour shifts, 
 the rate of progress was fifty feet per month; four-hour shifts 
 
 * Wochenschrift des QEsterreichischen Ingenieur- und Architekten-Ver- 
 eines, 1886, p. 284. 
 
 t Raymond, Trans. A. I. M. E., Vol. VI, pp. 542-558 (1877-1878). 
 J Drinker, p. 351. 
 
Fig. 3. Starting a tunnel by hand-drilling. 
 
18 • MODERN TUNNELING 
 
 increased the rate of progress to 78.7 feet per month, and by 
 crowding the miners to the Hmit during the last three weeks 
 they made 75 feet, or at the rate of 107 feet per month. 
 
 Some idea of the importance the early German miners 
 attached to drainage may be gathered from the fact that this 
 colossal enterprise only gave them an increased drainage depth 
 of 315 feet. 
 
 The Taillades tunnel * on the Marseilles aqueduct was begun 
 in January, 1839, and compl'eted at the close of 1846. It was 
 driven from fourteen shafts, and in their construction so much 
 water was encountered that the work of sinking them was very 
 difficult and at times seemed almost impossible. It was finally 
 necessary to install at one of the shafts a steam engine of 100 
 horse-power in order to remove the water, which amounted to 
 3,300 gallons per hour. The cost of sinking the shafts was ap- 
 proximately $40 per foot, while the tunnel itself cost approxi- 
 mately $37 per foot, or, including the cost of the shafts, $48.50 
 per foot. The Assassin tunnel on the same project was some- 
 what less difficult and cost but $25.50 per foot for 11,400 feet, 
 while the Notre Dame tunnel, which was lined with masonry 
 for its entire length of 11,500 feet, cost $32.50 per foot. 
 
 The first large mining tunnel in the United States was com- 
 menced as early as 1824. This was the ''Hacklebernie'^ tunnel 
 near Mauch Chunk, Pennsylvania, and it was driven by hand- 
 drilling and with black powder. When work on it was stopped 
 in 1827, it had penetrated 790 feet through hard conglomerate, 
 making an opening 16 feet wide by 8 feet high. Work in it was 
 resumed once more in 1846 and the tunnel was extended to a 
 length of 2,000 feet. 
 
 The invention of machines to do the work of rock-drilling, 
 which occurred almost simultaneously with the discovery of 
 high explosives, gave another great impulse to tunnel-driving. 
 The first extensive utilization of these aids was in the con- 
 struction of the Mt. Cenis tunnel in Europe and the Hoosac 
 
 * "M. de Mont. Richer et le Canal de Marseille." Felix Martin. Paris, 
 1878. Gallet et Braud. 
 
THE HISTORY OF TUNNELING 19 
 
 and Sutro tunnels in this country. The success attained with 
 them soon led to further activity in tunneling, not only for rail- 
 roads but in connection with mining, drainage, and water supply 
 as well — an activity culminating in the immense amount of such 
 work undertaken within the last ten or fifteen years. 
 
 The following table gives in chronological order some of the 
 more important events connected with these two wonderful 
 improvements. 
 
 A SHORT CHRONOLOGICAL HISTORY OF HIGH EXPLOSIVES 
 AND ROCK-DRILLS* 
 
 1847. Sobrero discovered nitroglycerine. 
 
 1849. J- J- Couch, of Philadelphia, patented on March 29 the first 
 
 percussion rock-drill. 
 1851. J. W. Fowle, of Philadelphia, patented on March ii the first 
 
 direct-action percussion-drill. 
 1854. Schumann invented his percussion-drill at Freiberg. 
 1857. Schumann drills used in Freiberg mines. 
 1857. Sommeiller invented a rock-drill for use at Mt. Cenis. 
 1 86 1. January i, Sommeiller improved drills commenced work in 
 
 the Mt. Cenis tunnel. 
 1863. Nobel first applied nitroglycerine as a blasting agent. 
 
 1865. Gun-cotton tried at the Hoosac tunnel by Thomas Doane, 
 
 chief engineer. 
 
 1866. Nitroglycerine tried with great success at the Hoosac tunnel 
 
 by T. P. Shaffner. 
 1866- Burleigh drills tried and proved to be a success at the Hoosac 
 tunnel. 
 
 1867. Nobel invented dynamite. 
 
 1868. Dynamite patented in America by Nobel. 
 
 MINING AND WATER TUNNELS DRIVEN BY 
 MACHINE-DRILLING 
 
 The idea of draining the mines of Virginia City by a deep 
 tunnel was first broached in the spring of i860, when Mr. 
 Adolph Sutro began negotiations with the mines, the State, and 
 
 * Drinker, pp. 54-55. 
 
20 
 
 MODERN TUNNELING 
 
 finally with the Federal Government for contracts, concessions, 
 etc. Actual work was first commenced at the portal of the 
 tunnel in Carson Valley, three and one-half miles from Dayton, 
 on October 19, 1869. The work was carried on by hand until 
 September, 1872, when diamond-drilKng was begun and experi- 
 mented with, more or less unsuccessfully; in 1874, Burleigh 
 drills were introduced, operated by compressed air generated in 
 
 Fig. 4. Driving a modern tunnel with machine-drills. 
 
 a compressor made by the Societe John Cockerill, of Seraing, 
 Belgium^. The tunnel was completed July 18, 1878, when the 
 Savage vein was cut 20,000 feet from the portal and 1,922 feet 
 below its outcrop. The tunnel, inside of the timbers, was 10 
 feet high by 14 feet wide, divided into two passageways by a 
 central row of posts. The rate of progress varied greatly, rang- 
 ing from 19 to 417 feet per month, the average monthly rate 
 from start to finish being 192.3 feet.* 
 
 * Report Commissioners Sutro Tunnel, and Drinker, pp. 337-350. 
 
THE HISTORY OF TUNNELING 21 
 
 The Tequiquac tunnel, which now forms the most important 
 link in the drainage system of the valley of Mexico, was com- 
 menced during the reign of the Emperor Maximilian. The 
 work was stopped, however, at the fall of the Empire and was 
 not resumed until 1885 ; even then the want of funds prevented 
 any material progress until March, 1888. 
 
 This tunnel is six and a quarter miles in length, driven through 
 a mass of sand, mud, and soft calcareous sandstone. It is brick- 
 lined throughout, the section ovoid, with an extreme width of 
 13 feet 9 inches and a height of 14 feet and has a gradient 
 of I foot in 1,388. The calculated flow is 450 feet per 
 second, or 200,000 gallons per minute. At first the headings 
 were driven in the center, but they were soon forced to 
 adopt the bottom heading system. The greatest completed 
 tunnel advance in any one month was 182 feet and the 
 greatest distance that any single heading was driven in a calen- 
 dar month was 656 feet. (Trans. Am. Soc. C. E., Vol. XXXII, 
 pp. 171-267.) 
 
 The Kelty tunnel on the Glasgow Water Works System is 
 2.6 miles in length and 9 feet square. Work was commenced in 
 June, 1887, ^^^ completed in December, 1889; driving was 
 carried on from each portal and both ways from the bottom of 
 two shafts. The average rate of progress in each heading was 
 4.5 feet per day. The rocks encountered varied from soft shale 
 to hard conglomerate. 
 
 The Shoshone tunnel, 1906-1910, is owned by the Central 
 Colorado Power Company, and its intake portal is located on the 
 Rio Grande River, twelve miles above Glenwood Springs. It 
 is 12,453 feet long, 12 feet high, and 16 feet 8 inches wide, and 
 is driven for the entire distance through hard metamorphic 
 granite. 
 
 Where timber supports were necessary, vertical posts and a 
 three-piece arch were employed, all of which were afterward 
 completely covered by concrete Hning. Driving was carried 
 on from seven cross-cut adits, as well as from both intake and 
 discharge ends. 
 
22 
 
 MODERN TUNNELING 
 
 Cost of tunnel, not including concrete lining, was $927,653, 
 divided as follows: 
 
 Construction costs per linear foot of tunnel: 
 
 Test drifts $ 
 
 Drilling and blasting ■, 20 
 
 Trenching and grading floor i 
 
 Track work i 
 
 Mucking and loading 17 
 
 Hauling 2 
 
 Dumping and maintenance 2 
 
 Blasting supplies 8 
 
 Drill steel 2 
 
 Sharpening and repairing 4 
 
 Timbering, temporary and permanent 3 
 
 Light and wiring i 
 
 Ventilating 
 
 Pipe, air hose, and connections 
 
 Power drills 2 
 
 Hoists and trestles 
 
 Pumping 
 
 Sundries 
 
 Total construction costs $74 
 
 Overhead costs, including surveying, management, 
 office, etc 30 
 
 Total cost per linear foot $105 
 
 35 
 91 
 60 
 
 87 
 57 
 59 
 85 
 94 
 96 
 21 
 28 
 
 49 
 91 
 40 
 
 The Corbett tunnel, of the Shoshone Irrigation Project, 
 Wyoming, is approximately 17,000 feet in length, of the inverted 
 horseshoe type, having a cross-section about 100 feet in area. 
 The tunnel heads opposite the Corbett Station of the Chicago, 
 BurHngton & Quincy R. R., and its course is parallel to the 
 general direction of the Shoshone River, which at three places 
 was near enough to permit adits to be excavated from the faces 
 of the bluffs to the timnel, thus affording eight headings for 
 construction purposes. The contract for its excavation was 
 awarded on September 16, 1905, the price being $33 per Knear 
 foot. In August, 1906, however, the contractor defaulted after 
 having driven 5,219 feet of tunnel, and the work was taken over 
 
THE HISTORY OF TUNNELING 23 
 
 by the United States Reclamation Service. After doing con- 
 siderable retimbering the work was carried on without any 
 special difficulties until its completion in 1907. The material 
 excavated throughout the tunnel consisted of dry clay, loose 
 shales, and stratified sandstones of different degrees of hardness, 
 and it decomposed very rapidly upon exposure to the air, thus 
 requiring considerable timbering. 
 
 The Big Bend tunnel, owned by the Great Western Power 
 Co., is situated at Big Bend on the Feather River in Butte 
 County, Cal. The main portion of the tunnel, about three miles 
 in length, was driven by the Big Bend Mining Co., from 1883 
 to 1887, in order to divert the flow of the river across a narrow 
 neck of land and leave the bend dry, allowing the company to 
 work the gravels in its bed for gold. This tunnel was enlarged 
 from 12 feet high by 13 feet wide to 18 feet high by 14 feet wide, 
 and extended 3,400 feet by the present owners in 1907-1908. 
 The entire tunnel is driven through shale with the exception of 
 about 6,000 feet in the middle of the old tunnel, which is in 
 diorite. It is Hned with concrete about 29 inches thick, with 
 an allowable minimum of 6 inches on the arch and 4 inches on 
 the invert. 
 
 The Coquitlam tunnel, which is part of the hydro-electric 
 power system supplying Vancouver, B. C, and neighboring 
 towns, is 12,650 feet long and is driven through solid granite. 
 As originally designed it had a mean sectional area of 81 square 
 feet. Work of enlarging the tunnel so that it would have a 
 sectional area of 176 square feet was begun in November, 1908, 
 but was seriously handicapped by the necessity of opening the 
 tunnel frequently to maintain the supply of water in a storage 
 reservoir, but it was finally completed in March, 191 1. The 
 new tunnel is ovoid in cross-section with the point down and is 
 unlined. 
 
 The Big Creek tunnel, which is part of the system of the 
 Pacific Light and Power Corporation, is 22,000 feet long and 
 12 feet in diameter. It was driven from nine adits and two 
 portals, has a slope of 3.2 feet per 1,000, and will be used as a 
 pressure tunnel throughout, the static pressure at the upper 
 
24 MODERN TUNNELING 
 
 end being approximately 30 feet and at the lower end approxi- 
 mately 100 feet. The formation pierced was solid blue granite 
 throughout, except for an occasional faulted zone. These 
 were Hned with concrete, the aggregate length of such linings 
 being 2,000 feet. 
 
 RAILWAY TUNNELS 
 
 While this book is intended to deal chiefly with the con- 
 struction of mining tunnels, there is much that can be learned 
 from the study of tunnels driven for railroad purposes. Under 
 ordinary conditions the rate of progress in a railroad tunnel is 
 limited by the speed at which the advance heading can be driven, 
 and as these headings do not differ materially from mining 
 tunnels, the rates of progress which have been attained in them 
 are of great interest to the miner. A railroad- tunnel heading 
 must be driven to Kne and grade the same as a mining tunnel, and 
 while it is desirable to maintain a uniform width and height, 
 it is not absolutely necessary to do so, thus giving railway- 
 tunnel headings a slight advantage over mining tunnels in this 
 respect. On the other hand, the multifarious operations carried 
 on between the heading and the portal of a railroad tunnel, 
 even under the best possible organization, often obstruct tempo- 
 rarily transportation to and from the face; the continuity of the 
 work is sometimes interfered with by the shooting of the benches 
 back of the face; and even where all the holes in the benches 
 and headings are blasted together, it takes somewhat longer 
 to clear out the smoke from so many groups of shots than it 
 would in a mining tunnel from a single round in the heading. 
 On the whole, in similar rock and with equally good equipment 
 and organization, there should be little if any difference in the 
 speed attained in driving a mining-tunnel or a railway tunnel- 
 heading, because, although the conditions for rapid progress are 
 not exactly identical, the opportunities are practically equal. 
 The history of the more important railway tunnels of the world 
 also shows forcibly the rapid increase in the rates of driving and 
 the lessening of the cost of construction since the introduction 
 of rock-drills and high explosives. 
 
THE HISTORY OF TUNNELING 
 
 25 
 
 PROGRESS AND COST OF SOME FAMOUS RAILWAY TUNNELS 
 
 
 Construction 
 Period 
 
 Length, 
 
 Miles 
 
 Duration 
 Boring, 
 Months 
 
 Avg. Daily 
 
 Progress 
 
 in Headings, 
 
 Feet 
 
 Cost per 
 Linear 
 Foot 
 
 Mt. Cenis 
 
 1857-1870 
 1858-1874 
 1872-1882 
 1880-1883 
 1 898-1 905 
 1906-1911 
 
 7-97 
 4-75 
 9.26 
 6.2 
 12.4 
 9-3 
 
 157 
 
 *88 
 
 78 
 54 
 
 3.0* 
 6.2 
 
 13-6 
 
 , I3.69t 
 
 14.2 J 
 
 $356.00 
 398.00 
 231.00 
 162.30 
 239.40 
 211.00 
 
 Hoosac 
 
 St. Gothard 
 
 Arlberg 
 
 Simplon 
 
 Loetschberg 
 
 * Average east and west headings, 1 865-1 873. 
 
 t Allowing only for days on which drilling was carried on, advance was 
 17.45 feet per day. 
 
 I Average for last 30 months, 17.1 feet. 
 
 The Mt. Cenis tunnel was driven through the northern spur 
 of the Cottic Alps to afford direct connection between the 
 French and Italian railway systems. Work was begun on 
 August 18, 1857, and the French and Itahan headings met on 
 December 25, 1870. The length of the tunnel as completed 
 was 42,157 feet and the cost $15,000,000, or $356 per linear 
 foot. Its greatest depth below the surface was 5,275 feet, 
 where the rock temperature was 85° F. The Sommeiller rock- 
 drill, operated by compressed air, was first used in this tunnel 
 January 12, 186 1, or five years before the introduction of air- 
 drills into the Hoosac tunnel in the United States. The rate 
 of progress varied greatly with the rock encountered; the total 
 time consumed in driving being thirteen years and one month, 
 or an average daily progress in each heading of 4.4 feet.§ 
 
 One of the most important early tunnels driven in the United 
 States was the Hoosac, on the line of the Troy & Greenfield 
 Railway. The project first came under consideration in 1825, 
 but actual work was not commenced until 1858. Hand-drilling 
 was employed until October 31, 1866, when Burleigh rock-drills 
 were first introduced; two months later nitroglycerine was 
 substituted for black powder, and the net result of these two most 
 important improvements was greatly to increase the rate of 
 driving. To be sure, many disheartening delays and interrup- 
 
 § Drinker, pp. 354-357. Vernon-Harcourt, Pro. Inst. C. E., Vol. XCV» 
 pp. 249-261. 
 
26 MODERN TUNNELING 
 
 tions occurred, due chiefly to failure of the earHer type of drilling 
 machines and to change of engineers and contractors, but in 
 March, 1869, a contract was let to the Shanly Brothers, of 
 Toronto, who completed the work on December 22, 1874. 
 
 The tunnel had a total length of 4>^ miles and was driven 
 throughout the greater part of that distance in mica-schist. 
 The maximum speed attained in a single heading was 184 feet 
 in one month of twenty-six working days, and the average speed 
 in the east and west headings for the last six months was 4.2 
 feet per day. The cost was $10,000,000, or $398 per Hnear foot.* 
 
 The great undertaking of driving the St. Gothard tunnel was 
 rendered possible through a joint treaty made by Germany, 
 France, and Italy, and on May 7, 1872, a contract for the tunnel 
 was let to M. Favre, of Genoa, who gave a bond for $1,600,000 
 for the successful completion of the work within a period of 
 eight years. The tunnel is 48,887 feet, or 9.26 miles, in length, 
 driven for the most part through various kinds of schist. After 
 testing a number of drills, a final selection was made of Ferroux 
 drills for the north side and McKean for the south side. The 
 average rate of progress in the headings was 186 feet per month. 
 In 1880 one of the headings passed through a zone of softened 
 feldspar, which, under the weight of the superincumbent rock, 
 squeezed into the tunnel with such force that granite walls and 
 arches 6 feet 7 inches in thickness were required to hold it in 
 place. The maximum rock temperature encountered was 88° F., 
 at a point 5,575 feet below the surface. The headings met 
 February 29, 1880, but the tunnel was not completed until 1882, 
 nearly two years after the time called for in the original con- 
 tract. The total cost was $11,300,000, or $231 per linear foot.f 
 
 The success of the Mt. Cenis and St. Gothard timnels, coupled 
 with the desire of the Austrian Government to have a railway 
 route to France which would not pass through Germany or 
 Italy, led to the construction of the Arlberg railway, which runs 
 from Innsbruck, in the Tyrol, to Bludenz, near the Swiss frontier, 
 
 * Drinker, pp. 315-337- 
 
 t Drinker, pp. 359-370. Vernon-Harcourt, Pro. Inst. C. E., Vol. XCV, 
 pp. 261-268. 
 
 1 
 
THE HISTORY OF TUNNELING 27 
 
 a distance of eighty-five miles, piercing the Arlberg range about 
 twenty miles from Bludenz by a tunnel over six miles long. 
 In the selection of the machinery and in planning the work, 
 advantage was taken of the experience gained in the Mt. Cenis 
 and St. Gothard tunnels. In consequence of this, the results 
 obtained were as much in advance of the St. Gothard as the 
 operations in that tunnel had been an improvement on those 
 employed in the Mt. Cenis. The driving of this tunnel was 
 commenced in July, 1880, and the headings met on November 
 13, 1883. The average rate of progress was thus nearly two 
 miles per year. The greatest temperature of the rock was 
 64° F. at a point 2,295 ^^^^ below the surface. The Ferroux 
 percussion drill, operated by compressed air, was employed in 
 the eastern heading, and the Brandt rotary drill, worked by 
 water pressure, in the western. The Ferroux drills drove 17,355 
 feet and the Brandt drills 14,880 feet, a difference of 2,475 ^^^t 
 in favor of the former. This variation was due more to the 
 dissimilarity of the rock in the east and west headings than to 
 any difference in the efficiency of the drills themselves, as is 
 shown by the following figures, the average daily advance of the 
 two drills being as follows: 
 
 Ferroux 
 
 Brandt 
 
 Year 
 
 13.5 ft. 
 17.2 " 
 17.85 " 
 
 9.5 ft. 
 I5.I " 
 
 17.82 " 
 
 In 1881 
 In 1882 
 In the io>^ months of 1883 
 
 These figures show that as the nature of the rock became 
 similar when the faces approached each other, the efficiency of the 
 Brandt drill was practically the same as the Ferroux. The 
 Brandt drill was much more cheaply operated than the other, 
 and it necessitated the use of only seven miners in the heading 
 as against twelve with the Ferroux. 
 
 The total length of the tunnel was 32,235 feet and its cost 
 was $5,877,684, or $182.30 per linear foot.* 
 
 * Vernon-Harcourt, Pro. Inst. C. E., Vol. XCV, pp. 268-271. Charton, 
 "Le Genie Civil," Vol. VI, 1885, pp. 3-18. 
 
28 MODERN TUNNELING 
 
 The Simplon tunnel consists of two parallel, single-track 
 railway tunnels, 56 feet from center to center, driven from 
 Brigue, Switzerland, to Iselle, Italy, a distance of 12.4 miles. 
 
 Operations commenced at Brigue November 22, 1898, and 
 at Iselle December 21, 1898. The headings met February 24, 
 1905, but the tunnel was not completed and ready for use 
 until January 25, 1906. Brandt rotary hydraulic drills were 
 employed in both headings and the average rate of heading 
 advance was 13.69 feet per diem, although when conditions were 
 favorable speeds of 16 feet per day in the Italian end and 20 to 
 21 feet in the Swiss end were readily attained. The rock was 
 principally gneiss, with occasional beds of slate, granite, and 
 marble. 
 
 When operating in hard rock, the cycle of operations was as 
 follows : 
 
 Bringing up and adjusting drills 20 minutes 
 
 - Drilling iM~2>^ hours 
 
 Charging and firing 15 minutes 
 
 Mucking 2 hours 
 
 More serious difficulties were encountered in driving this 
 tunnel than any which have yet been undertaken. SwelHng 
 ground was extremely common, and in places the pressure was 
 so great that the roof and sides could only be held in place by 
 steel I-beams, with the spaces between rammed with rapid-setting 
 concrete. A portion of the tunnel where the pressure was the 
 greatest is said to have cost $1,620 per Hnear foot. Many 
 springs were encountered, and the volumes of cold water flowing 
 into the tunnel amounted at times to 17,000 gallons per minute. 
 Near the center of the tunnel large springs of hot water were 
 encountered, amounting in all to 4,330 gallons per minute, one 
 spring alone giving 1,400 gallons per minute at 116° F. At 
 first it seemed that the high temperatures engendered would 
 effectually prevent further advance, but by bringing both cold 
 water and cold air into the headings in sufficient volumes, the 
 temperature was reduced to a point where it was possible to 
 resume work, although it took six months to drive the last 800 
 
THE HISTORY OF TUNNELING 29 
 
 feet. The rapid average rate of progres,s maintained in the 
 Simplon tunnel, in spite of the difficulties encountered, was due 
 to superb equipment and an organization so efficient that 648 
 men and 29 horses at the Swiss end and 496 men and 16 horses 
 at the Italian end were advantageously employed. 
 
 Notwithstanding the care that was taken in ventilation and 
 the precautions adopted for the health and safety of the work- 
 men, sixty men were killed during the progress of the work. The 
 total cost of tunnel was $15,700,000, or $239.40 per linear foot.* 
 
 The Loetschberg tunnel was driven through the Bernese 
 Alps in Switzerland and forms the last link in the railway sys- 
 tem connecting the city of Berne with the village of Brigue at 
 the north end of the Simplon tunnel. The desirability of con- 
 necting the Bernese Oberland with the Rhone Valley was dis- 
 cussed as early as 1866 and the present location of the tunnel 
 was first proposed in 1889. 
 
 The railway begins at Frutigen in the Bernese Oberland, 
 about 32.5 miles from the north portal; 50.5 per cent of this 
 length is on horizontal curves. There are about twelve short 
 tunnels on the line, aggregating 16,000 feet in length, one of 
 which is a spiral tunnel 5,460 feet long, with a 985-foot radius. 
 The main tunnel is 47,678 feet long and was first planned to be 
 run on a tangent, but a serious cave 1.6 miles from the north 
 portal, which killed 25 men and filled up 5,900 feet of tunnel, 
 compelled the abandonment of the original line and the adoption 
 of a curved tunnel to pass around the immense, peaty, mud-filled 
 fissure which the heading had tapped. 
 
 At the south end Ingersoll-Rand air drills and compressors 
 were used, while in the north end Myers drills and compressors 
 were adopted. Transportation in the tunnel was handled by 
 compressed-air locomotives running on 30-inch gauge tracks. 
 From four to six drills were employed in each heading, mounted 
 on a horizontal bar, which was carried on a carriage, thus neces- 
 sitating mucking out after firing before drilling could be com- 
 menced in the face. For the last thirty months of driving, the 
 
 * Trans. A. I. M. E., Vol. XLII, pp. 441-446. Fox, Pro. Inst. C. E.,. 
 Vol. CLXXIII, pp. 61-83. 
 
30 MODERN TUNNELING 
 
 average rate of progress in the south heading was 15.8 feet per 
 day, and in the north end, where the driving was much easier, 
 18.6 feet per day. On the north side, when the heading was in 
 limestone, it was advanced 5,623 feet in six months, or an 
 average rate of 30.8 feet per day.* 
 
 The Busk-Ivanhoe tunnel, on the Colorado Midland Railway 
 between Leadville and Glenwood Springs, is 9,394 feet long, and 
 has an altitude of 10,810 feet at Busk and at Ivanhoe 10,944 feet, 
 making it the third highest railway tunnel in the world. It 
 is driven almost the entire distance in metamorphic granite 
 with some softened shear zones which gave considerable trouble 
 in both driving and timbering. The tunnel cost $1,250,000, 
 and thirty men were killed in the progress of the work.j 
 
 The Severn tunnel (i 873-1 887), which is on the line of the 
 Great Western Railway in England, and passes under the estu- 
 ary of the Severn River, has a length of 4.35 miles and traverses 
 a great variety of strata consisting of conglomerate, limestone, 
 carboniferous beds, sandstone, marl, and sand. The most 
 serious difficulty encountered in driving was the great volume of 
 water coming into the tunnel, not so much from the estuary 
 above as from a huge spring on the land side. Several ineffectual 
 attempts were made to bulkhead this spring, but before the work 
 could be successfully carried on, it was necessary to erect an 
 immense pumping plant with a capacity of 45,000 gallons per 
 minute, but the maximum amount pumped for any considerable 
 period did not exceed 20,000 gallons per minute.t 
 
 The Totley tunnel, on the Dore & Chinley Railway, England, 
 is 3.53 miles in length, and is on the line between Sheffield and 
 Manchester. Work ^was commenced in 1888 and the completed 
 tunnel was ready for traffic in September, 1893. It is driven 
 almost entirely through carbonaceous black shale which con- 
 tained some strata of sandstone and grit. The progress of the 
 work was greatly impeded by heavy inrushes of water, some- 
 
 * Saunders, Trans. A. I. M. E., Vol. XLII, pp. 446-469. Bonnin, La 
 Nature, Paris, 1909, Vol. XXXVII, pp. 147-157. 
 '\ Engineering News, August 25, 1872. 
 JVernon-Harcourt, Pro. Inst. C. E., Vol. CXXI, pp. 305-308. 
 
THE HISTORY OF TUNNELING 31 
 
 times carrying vast quantities of sand and silt. For a time the 
 discharge from the Padley heading amounted to 5,000 gallons 
 per minute. At first the water was carried out of the tunnel 
 in 12-inch pipes, but as these proved insufficient and liable to 
 clog with sand, the headings were closed up with watertight 
 bulkheads and center drains carried in from the portal. This 
 work took six weeks, during which time the pressure behind one 
 of the dams rose to 155 pounds per square inch.* 
 
 The Aspen tunnel on the Union Pacific Railway between 
 Cheyenne and Ogden, although only 5,900 feet in length, is 
 interesting on account of the obstacles encountered in driving, 
 the difficulty of holding back the swelling ground, and the fact 
 that mechanical loading of the broken rock was successfully 
 employed in both headings. The tunnel was driven through 
 carbonaceous shale containing an occasional stratum of yellow 
 sandstone dipping 20° to 30° to the east, while the course of the 
 tunnel was a little south of west. The opening is 22 feet 6 inches 
 high and 17 feet wide in the clear, timbered with 12 by 12-inch 
 timbers with vertical posts capped with a seven-segment circular 
 arch. These timber sets were spaced 2 feet apart, i foot apart, 
 or close together, as the weight of the ground demanded. On 
 a portion of the tunnel, walls of solid 12 by 12-inch timbers 
 would not stand the rock pressure, and the timbers were replaced 
 by 1 2 -inch steel I beams, which were sometimes buckled side- 
 ways before the concrete filling could be rammed in place. 
 
 Small steam shovels of ^-cubic yard bucket capacity, and 
 operated by compressed air, were employed for loading cars in 
 the headings, and effected a great saving in both time and 
 expense.! 
 
 Arthur's Pass tunnel, South Island, New Zealand, sometimes 
 known as the Otiro, is on the line of the New Zealand Govern- 
 ment Railway which connects Christchurch on the east with 
 Greymouth on the west coast, and pierces the crest of the South- 
 ern Alps for a distance of 5H miles. Work began in May, 1898, 
 and the contract called for the completion of the work in a 
 
 *Rickard, Pro. Inst. C. E., Vol. CXVI, pp. 1 17-138. 
 f Hardesty, Engineering News, March 6, 1902. 
 
32 
 
 MODERN TUNNELING 
 
 period of five years; price $5,000,000. Tunnel haulage was at 
 first attempted with eight-ton benzine locomotives, but they 
 were discarded on account of uncertain action and the annoying 
 fumes, and electric locomotives were substituted.* 
 
 PARTIAL LIST OF NOTED RAILROAD TUNNELS f 
 
 Name of Tunnel 
 
 Country 
 
 Length 
 
 Summit level 
 
 Opened for 
 traffic 
 
 Simplon 
 
 St. Gothard 
 
 Loetschberg 
 
 Mont Cenis 
 
 Arlberg 
 
 Ricken 
 
 Tauern 
 
 Ronco 
 
 Tenda 
 
 Hauenstein Base 
 Karawanken . . . . 
 
 Somport 
 
 Jungfrau 
 
 Borgallo 
 
 Hoosac 
 
 Severn 
 
 Marianopoli 
 
 Turchino 
 
 Grenchenberg . . . 
 
 Wocheiner 
 
 Mont d'Or 
 
 Albula 
 
 Totley 
 
 Peloritana 
 
 Gravehals 
 
 Puymorens 
 
 Standedge 
 
 Woodhead 
 
 Bosruck 
 
 La Nerthe 
 
 Biblo 
 
 Kaiser Wilhelm, 
 Echarneaux. . . . , 
 
 Blaisy 
 
 Cascade 
 
 Sodbury 
 
 Switzerland- 1 taly 
 Switzerland- 1 taly 
 
 Switzerland 
 
 France-Italy. . . . 
 
 Austria 
 
 Switzerland 
 
 Austria 
 
 Italy 
 
 Italy 
 
 Switzerland 
 
 Austria 
 
 France-Spain .... 
 
 Switzerland 
 
 Italy 
 
 United States. . . 
 England-Wales. . 
 
 Sicily 
 
 Italy 
 
 Switzerland 
 
 Austria 
 
 France-Switzerl ' nd 
 Switzerland .... 
 
 England 
 
 Sicily 
 
 Norway 
 
 France-Spain. . . 
 
 England 
 
 England 
 
 Austria 
 
 France 
 
 Italy 
 
 Germany 
 
 France 
 
 France 
 
 United States. . 
 England 
 
 Feet 
 
 65,734 
 49,212 
 47,685 
 42,150 
 32,892 
 28,230 
 28,038 
 27,231 
 26,568 
 26,400 
 26,169 
 25,656 
 23,622 
 23,220 
 
 23,175 
 23,028 
 
 22,453 
 21,150 
 21,120 
 20,781 
 20,025 
 19,290 
 18,690 
 17,898 
 17,388 
 16,791 
 16,020 
 15,879 
 15,639 
 15,303 
 13,907 
 13,767 
 13,620 
 13,530 
 13,413 
 13,299 
 
 Feet 
 2,313 
 
 3,788 
 
 4,077 
 4,248 
 4,300 
 650 
 4,020 
 
 3,260 
 
 11,220 
 
 1,787 
 1,761 
 
 6,133 
 
 2,844 
 
 2,405 
 
 1906 
 
 1882 
 
 1913 
 
 1871 
 1885 
 1910 
 1909 
 1888 
 1899 
 
 1 
 1906 
 
 X 
 I9I2 
 
 1887 
 1876 
 1886 
 
 1900 
 
 I 
 
 1909 
 
 % 
 
 1903 
 1893 
 
 1885 
 1909 
 
 X 
 1850 
 
 1845 
 
 1906 
 
 1879 
 1895 
 
 1903 
 
 * Gavin, Engineering News, May 9, 19 12. 
 
 t Abstract from The Engineer, November 28, 1913, p. 561-2, with a few 
 additions from other sources. 
 J Under construction 1 9 13- 1 4. 
 
THE HISTORY OF TUNNELING 
 
 33 
 
 PARTIAL LIST OF NOTED RAILROAD TUNNELS— (Continued) 
 
 Name of Tunnel 
 
 Country 
 
 Length 
 
 Opened for 
 traffic 
 
 Credo 
 
 Vizzavona 
 
 Khojak 
 
 Suram 
 
 Disley 
 
 Col de St. Michel 
 
 Bramhope 
 
 Festinog 
 
 Cowburn 
 
 Meudon 
 
 Giovo 
 
 Col des Loges. . . 
 
 Cremolina 
 
 Stampede 
 
 Cairasca 
 
 Busk-Ivanhoe. . . 
 
 Caldera 
 
 Hauenstein 
 
 Beacon Hill 
 
 Transandine .... 
 
 France 
 
 Corsica 
 
 Baluchistan 
 
 Caucasus 
 
 England 
 
 France 
 
 England 
 
 Wales 
 
 England 
 
 France 
 
 Italy 
 
 Switzerland 
 
 Italy 
 
 United States. . . 
 
 Italy 
 
 United States . . , 
 
 Peru 
 
 Switzerland 
 
 China 
 
 Chile-Argentina . 
 
 Feet 
 12,960 
 12,894 
 12,867 
 12,810 
 11,598 
 11,430 
 11,262 
 11,178 
 11,106 
 10,962 
 10,695 
 10,560 
 10,514 
 9,850 
 9,840 
 
 9,394 
 9,240 
 8,910 
 7,212 
 6,933 
 
 Feet 
 2,791 
 
 1,890 
 3,200 
 
 10,944 
 15,775 
 
 10,500 
 
 1889 
 1892 
 
 1895 
 1902 
 1901 
 1849 
 1879 
 1893 
 1900 
 
 1906 
 
 1893 
 
 1910 
 1911 
 
 The following is a list of some of the more important Japanese 
 tunnels. 
 
 Tsudo adit. Ashio Mine, driven September, 1885-October, 1896, 
 II feet high, 13 feet wide, and 10,000 feet long. Located on the 
 bank of Watarase River. This tunnel is furnished with double- 
 track electric railway, and has seven shafts, each installed with 
 electric hoist. The mine contauis an aggregate length of more 
 than 600,000 feet of levels and winzes. 
 
 Omodani Mine. Ono District. Has five levels, aggregating 58,380 
 feet in length; the longest having a length of 12,110 feet, while 
 the drainage adit is 10,850 feet long. 
 
 Yoshioka Mine. Kawakami District. Mine opened by eight levels 
 and crosscuts, totaling 134,281 feet, the main adit being 39,193 
 feet in length. 
 
 Okawamae adit. This adit is for draining the Kusakina Mine, 
 Niigataken, and has a length of 10,000 feet. 
 
 Sosuido tunnel* of Sado Mine, Island of Sado, 11,000 feet long. 
 
 Sosuido adit.* This adit is to drain the Innai Silver Mines, and is 
 8 feet high, 10 feet wide, and 7,800 feet long. 
 
 Nagara Yama tunnel. (No. if Lake Biwa Canal, near Kyoto.) 
 
 * Sosuido means "Drainage level." 
 
 t There are two Lake Biwa Canals, the first executed in 18 
 the second 1909-1911. 
 
 -1890, and 
 
34 MODERN TUNNELING 
 
 Executed in 1886-1890, 14 feet high, 16 feet wide, and 8,040 feet 
 
 long. Rock of slate and sandstone chiefly. 
 N agar a Yama tunnel. (No. 2* Lake Biwa Canal, near Kyoto.) 
 
 Executed in 1909-1911, 13^ feet high, 13 feet wide, and 8,826 
 
 feet long. Rock slate chiefly. 
 Kamuriki Railway tunnel. Shinano District. Executed in 1896- 
 
 1900. 16^ feet high, 15 feet wide, and the length is 8,712 feet. 
 
 Hard rock. 
 Kohotoke Railway tunnel. Kai District. (Imperial Government 
 
 R.R.,in line from Tokyo to Kofu.) Executed in 1897-1900, i6}4 
 
 feet high, 15 feet wide, and 8,356 feet long. Clay rock chiefly. 
 Sasago Railway tunnel. Kai District. (Imperial Government R.R. 
 
 in line from Tokyo to Kofu.) Executed in 1896-1902, i6>^ feet 
 
 high and 15 feet wide. The length is 15,280 feet, being the 
 
 largest railway tunnel (in one length) completed in Japan. Soft 
 
 rock. 
 Ikoma Yama tunnel. "t (Kyoto & Nara Electric Ry.) 17 feet io>^ 
 
 inches high, 22 feet iK inches wide, and 11,088 feet long. 
 Dokuritsu 2^^X tunnel. Mt. Ari R.R., Formosa. (Just completed.) 
 
 From Kagi Entrance A to Ari Entrance B, three miles, and the 
 
 length of the tunnels in that section i mile and 23 chains and 77 
 
 links. The dimensions of the tunnels are in accordance with the 
 
 regular construction gauge of the Imperial Government Railways. 
 Daishi Tsudo. (No. 4 tunnel.) Beshi Copper Mines, lyo District, 
 
 14 feet high, 16 feet wide, and 18,000 feet long. Rock, palaeozoic 
 
 chlorite, and mica schist. 
 
 * There are two Lake Biwa Canals, the first executed in 1 886-1 890, and the 
 second 1909-1911. 
 
 t Yama in this table means altitude or mountain. 
 
 t 2^^ means the same as Yama, only in Chinese pronunciation. 
 
CHAPTER III 
 
 MODERN MINING AND WATER TUNNELS 
 
 RESUME OF DATA 
 
 The following paragraphs contain brief descriptions arranged 
 alphabetically of tunnels and adits visited in the special field 
 work upon which this book is based. In their examination, 
 complete information was obtained, wherever possible, concerning 
 surface and underground equipment, provisions for the safety of 
 the men, the use of explosives, and the methods employed in 
 driving, with regard to efficiency, cost, and other similar data 
 bearing upon the problem. (See Appendix, page 421.) It is 
 impossible, because of lack of space, to reproduce all of this 
 some information here, but the following paragraphs convey 
 briefly idea as to the main features of the different tunnels. 
 
 Burleigh tunnel: Silver Plume, Colorado. Purpose, njine 
 drainage and development. Length, 3,000 feet. Cross-section, 
 rectangular, 6 feet wide by 7 feet high. Rock, granite and gneiss. 
 Power, steam. Ventilation, exhaust fan, 10- and 12-inch pipe. 
 Drills, Burleigh drills used in 1869 (first use of machine drills 
 in an American tunnel) ; Ingersoll-Rand and Leyner drills used 
 in driving last 2,800 feet. Mounting, vertical colimins. One 
 shift per day. Two drillers, two helpers, and three muckers per 
 shift. Horse haulage, one-ton cars. Sixty-per-cent gelatine 
 dynamite. No timbering. Average monthly progress, 100 feet. 
 Approximate cost per Hnear foot, $20. Started in 1869 and 
 driven 200 feet while testing Burleigh drills; extended later to 
 3,000 feet for mine drainage. 
 
 Carter tunnel: Ohio City, Colorado. Purpose, mine drainage 
 and transportation. Length, 6,600 feet. Cross-section, rect- 
 angular with arched roof, 5.5 feet wide by 7.5 feet high. Rock, 
 gneiss. Power, hydraulic and hydro-electric. Ventilation, ex- 
 haust blower, lo-inch pipe. Two Leyner drills mounted on ver- 
 
 35 
 
36 
 
 MODERN TUNNELING 
 
 tical columns. One drilling and two mucking shifts daily. Two 
 drillers, one helper, and two muckers per shift. Horse haulage, 
 2i-cubic-foot cars. Forty-per-cent and eighty-per-cent gelatine 
 dynamite, 8 pounds per cubic yard. One hundred feet timbered. 
 Approximate cost per linear foot, $io to $15. Started 1897; on 
 November i, 191 1, had driven 6,550 feet; part of intervening 
 time spent in drifting along laterals; three years shut down 
 entirely, and five years only three men at work. 
 
 Catskill Aqueduct: Ulster, Orange, Putnam, and Westchester 
 Counties, and New York City, New York. Length, see Hst of 
 various tunnels on this project given below. Cross-section, see 
 Figure 5. This aqueduct includes the following tunnels: 
 
 Fig. 5. Cross-sections of typical tunnels, Catskill Aqueduct. 
 
 Peak: Length, 3,470 feet. Rock, hard. Started, November, 
 1908; completed, November, 1909. 
 
 Rondout Siphon: Length, 23,608 feet. Cross-section, circular. 
 Rock, Onondaga limestone, Binnewater sandstone, Hudson 
 River shale, Esopus shale. High Falls shale, Shawangunk grit, 
 Hamilton and Marcellus shale, Helderburg limestone. Power, 
 steam. Ventilation, exhaust fan, 14- and 20-inch pipe. Four 
 Ingersoll-Rand drills in each heading. Mounting, vertical col- 
 umn. Two drilling and three mucking shifts per day. Four 
 drillers, four helpers, and ten muckers per shift. Mule haulage. 
 
MODERN MINING AND WATER TUNNELS 37 
 
 40-cubic-foot cars. Sixty-per-cent gelatine dynamite, 4 to 5 
 pounds per cubic yard of heading. Lined with concrete. Aver- 
 age monthly progress per heading, 220 feet. Started, March, 
 1909; completed, May, 191 1. 
 
 Bonticou: Length, 6,823 feet. Cross-section, horseshoe. 
 Rock, Hudson River shale. Started, November, 1908; com- 
 pleted, February, 191 1. 
 
 Wallkill Siphon: Length, 23,391 feet. Cross-section, circular. 
 Rock, Hudson River shale. Power, electricity, purchased. 
 Ventilation, fan, 12- and 14-inch pipe. Four Ingersoll-Rand or 
 SulHvan drills in each heading. Mounting, vertical column. 
 Three shifts per day. Four drillers, four helpers, and eight 
 muckers per shift. Electric haulage, 40-cubic-foot cars. Sixty- 
 per-cent gelatine dynamite, 4.3 to 4.6 pounds per cubic yard of 
 heading. Lined with concrete. Average monthly progress per 
 heading, 300 feet. Started, October, 1909; completed, Decem- 
 ber, 1910. 
 
 Moodna Siphon: Length, 25,200 feet. Cross-section, circular. 
 Rock, hard sandstone, granite, and Hudson River shale. Power, 
 steam. Ventilation, jet of compressed air in 12-inch pipe. Four 
 Ingersoll-Rand drills per heading. Moimting, vertical column. 
 Three shifts per day. Four drillers, four helpers, and ten 
 muckers per shift. Mule haulage, 40-cubic-foot cars. Seventy- 
 five-per-cent gelatine dynamite. Lined with concrete. Average 
 monthly progress per heading, 165 feet. Started, February, 
 1910; completed, June, 191 1. 
 
 Hudson Siphon: 1,100 feet below sea level. Length, 3,022 
 feet. Rock, granite. Started, December, 19 10; completed, 
 January, 191 2. 
 
 Breakneck: Length, 1,054 feet. Cross-section, horseshoe. 
 Rock, granite and gneiss. Started, December, 1910; com- 
 pleted, April, 191 1. 
 
 Bull Hill: Length, 5,365 feet. Rock, granite. Started, June, 
 1909; completed, January, 191 1. 
 
 Garrison: Length, 11,430 feet. Rock, hard gneiss. Started, 
 Jime, 1907; suspended, November, 1910, to April, 191 1; com- 
 pleted, 191 2. 
 
38 MODERN TUNNELING 
 
 Hunters Brook: Length, 6,150 feet. Cross-section, horseshoe. 
 Rock, schist of variable hardness. Started, September, 1909; 
 completed, 191 2. 
 
 Turkey Mountain: Length, 1,400 feet. Rock, Manhattan 
 schist. Started, October, 1909; completed, December, 1910. 
 
 Croton Lake: Length, 2,639 f^^t. Rock, Manhattan schist and 
 Fordham gneiss. Started, July, 19 10; completed, January, 191 2. 
 
 Croton: Length, 3,000 feet. Rock, Manhattan schist. Started, 
 August, 1909; completed, December, 191 1. 
 
 Chadeayin: Length, 700 feet. Rock, Manhattan schist. 
 Started, November, 1909; completed, September, 1910. 
 
 Millwood: Length, 4,750 feet. Rock, hard gneiss. Started, 
 May, 1 9 10; completed, 191 2. 
 
 Sarles: Length, 5,230 feet. Rock, hard gneiss and schist. 
 Started, February, 19 10; completed, 191 2. 
 
 . Harlem Railroad: Length, 1,100 feet. Rock, hard gneiss and 
 schist. Started, June, 1910; completed, January, 191 1. 
 
 Reynolds Hill: Length, 3,650 feet. Rock, schist. Started, 
 October, 19 10; completed, 191 2. 
 
 East View: Length, 5,388 feet. Rock, schist. Started, 
 April, 1910; completed, January, 191 2. 
 
 Elmsford: Length, 2,375 feet. Rock, soft schist. Started, 
 May, 191 1 ; completed, 191 2. 
 
 Yonkers Siphon: Length, 12,302 feet. Cross-section, circular. 
 Rock, Yonkers gneiss and granite. Power, electrical. No 
 ventilation supplied, except by opening compressed-air Kne. 
 Four IngersoU-Rand drills in each heading. Mounting, vertical 
 columns. Two drilling shifts and three mucking shifts per day. 
 Four drillers, four helpers, and eight to twelve muckers per 
 shift. Mule haulage, 40-cubic-foot cars. Sixty-per-cent gelatine 
 dynamite, 4 to 5 pounds per cubic yard of heading. Lined 
 with concrete. Average monthly progress per heading, 155 
 feet. Started, July, 1910; completed, July, 191 1. 
 
 Van Cortlandt Siphon: Length, 1,809 feet. Rock, Yonkers 
 gneiss. Started, July, 1910; completed, September, 191 1. 
 
 City tunnel: Length, 18. 11 miles. Rock, Fordham gneiss 
 and Manhattan schist. Started, December, 191 1; completed, 1914. 
 
MODERN MINING AND WATER TUNNELS 39 
 
 Central tunnel: Idaho Springs, Colorado. Purpose, mine 
 drainage and transportation. Length, 9,000 feet. Cross-section, 
 rectangular. Two thousand five hundred feet driven 12 
 feet wide by 8 feet high; the remainder 5 feet wide by 7 feet 
 high. Rock, Idaho Springs gneiss. Power, steam. Ventila- 
 tion, exhaust with blower through 19-inch pipe. Two Leyner 
 drills in the heading. Mounting, horizontal bar. One shift per 
 day. Two drillers, two helpers, and four muckers per shift. 
 Horse haulage, 30-cubic-foot cars. Forty-per-cent gelatine 
 dynamite, 5 to 7 pounds per cubic yard of heading. One hundred 
 feet timbered. Average monthly progress in the heading, 200 
 feet. 
 
 Coronado tunnel: Metcalf , Arizona. Purpose, mine develop- 
 ment and transportation. Length, 6,300 feet. Cross-section, 
 square, 9 by 9 feet. Rock, granite and porphyry. Power, steam 
 with crude oil as fuel. Ventilation, blow and exhaust with 
 pressure blower through a 12 -inch pipe. IngersoU-Rand and 
 Sullivan drills were used in the first half of the tunnel, Leyner- 
 IngersoU drills were used in the last half. Three shifts per 
 day. Two and three drillers, one helper, and four to six muckers 
 per shift. Mule haulage, "one-ton" cars. Sixty-per-cent and 
 loo-per-cent gelatine dynamite. Average monthly progress, 
 415 feet. Average cost per linear foot, $22.64. (See page 329.) 
 Started, Jime, 191 2; completed, August, 1913. 
 
 Gold Links tunnel: Ohio City, Colorado. Purpose, mine 
 drainage and transportation. Length, 3,900 feet. Cross-section, 
 rectangular with arched roof, 6 feet wide by 8 feet high. Rock, 
 gneiss, intruded granite, porphyry. Ventilation, exhaust with 
 fan through 15-inch pipe. One IngersoU-Rand drill. Mounting, 
 vertical column. Two shifts per day. One driller, one helper, 
 and two or three muckers per shift. Horse haulage, 25-cubic- 
 foot cars. Forty-per-cent gelatine dynamite, 5 to 6 pounds per 
 cubic yard of heading. Two hundred feet timbered. Average 
 monthly progress, 200 feet. Approximate cost per linear foot, 
 not including permanent equipment, $19. Started, May, 1906; 
 driven intermittently; completed, December, 191 2. 
 
 Gunnison tunnel: Montrose, Colorado. Purpose, irrigation. 
 
40 
 
 MODERN TUNNELING 
 
 Length, 30,645 feet. Cross-section, horseshoe, 10 feet wide, 12.5 
 feet high. Rock, chiefly metamorphosed granite, with some 
 water-bearing clay and gravel, some hard black shale, and a 
 zone of faulted and broken material. Power, steam. Ventila- 
 tion, blow and exhaust with blower through 15-inch pipe. Four 
 Sullivan drills per heading (Leyner drills also tried). Mounting, 
 vertical column for Sullivan drills; horizontal bar for Leyner 
 drills. Three shifts per day. Four drillers, four helpers, and 
 five to eight muckers per shift. Electric haulage, 35- and 54- 
 cubic-foot cars. Sixty- and 40-per-cent gelatine dynamite. 
 5.5 pounds per cubic yard of heading. Fourteen thousand five 
 hundred feet timbered. Average monthly progress per heading, 
 250 feet. Cost per linear foot of tunnel, $70.66. Started, 
 January, 1905; completed, July, 1909. 
 
 Laramie-Poudre tunnel: Larimer County, Colorado. Purpose, 
 irrigation. Length, 11,300 feet. Cross-section, rectangular, 
 9.5 feet wide by 7.5 feet high. Rock, close-grained granite. 
 Power, hydraulic and hydro-electric. Ventilation, exhaust 
 with blower through 14-inch and 15-inch pipe. Three Leyner 
 drills in the heading. Mounting, horizontal bar. Three shifts 
 per day. Three drillers, two helpers, and six muckers per shift. 
 Mule haulage, i6-cubic-foot cars. Sixty- and loo-per-cent. 
 gelatine dynamite, 3.9 to 4.9 pounds per cubic yard of heading. 
 Six hundred and thirty feet timbered. Average monthly 
 progress per heading, 509 feet. Cost per linear foot of tunnel, 
 $39.54. Started, December, 1909; completed, July, 191 1. 
 
 Lausanne tunnel: Mauch Chunk, Pennsylvania. Purpose, 
 mine drainage. Length, 20,000 feet. Cross-section, arched 
 roof, 12 feet wide by 8 feet high. Rock, shale, conglomerate, 
 slate, and anthracite coal. Power, steam. Ventilation, blow 
 with fan through two 16-inch pipes. Two Ingersoll-Rand 
 drills in the heading. Moimting, vertical coliunns. Three 
 shifts per day. Two drillers, two helpers, and four to five 
 muckers per shift. Electric haulage, 78-cubic-foot cars. Sixty- 
 per-cent gelatine dynamite. Average monthly progress per 
 heading, 340 feet. Cost per linear foot of tunnel, $19. Started, 
 July, 1906; completed, February, 191 2. 
 
MODERN MINING AND WATER TUNNELS 
 
 41 
 
 Los Angeles Aqueduct: Location, Inyo, Kern, and Los Angeles 
 Counties, California. Purpose, water supply, power, and irriga- 
 tion. Cross-section, see Figure 6. 
 
 Fig. 6. Cross-sections of typical tunnels, Los Angeles Aqueduct. 
 
 Little Lake and Grapevine Divisions: Power, electricity, pur- 
 chased from separate plant owned by the Aqueduct. Ventila- 
 
42 MODERN TUNNELING 
 
 tion, blow and exhaust with pressure blower through 12-inch 
 pipe. Two Leyner drills per heading. Mounting, horizontal 
 bar. One and two shifts on Little Lake Division; two shifts 
 per day on Grapevine Division. Two drillers, two helpers, and 
 five muckers per shift. Mule and electric haulage on Little 
 Lake Division; electric haulage on Grapevine Division, 32-cubic- 
 foot cars both Divisions. Forty-per-cent gelatine dynamite, 
 ^% pounds per cubic yard of heading, Grapevine Di\ision; 
 14,745 feet timbered on Little Lake Division; 1,500 feet 
 timbered on Grapevine Division. Started, 1909; completed, 
 
 1913- 
 
 Tunnel iB: Length, 1,918 feet. Rock, medium granite. 
 Started, June, 1909; completed, December, 1909. 
 
 Tunnel 2: Length, 1,739 feet. Rock, medium granite, very 
 wet. Started, May, 1909; completed, September, 1909. 
 
 Tunnel 2 A: Length, 1,322 feet. Rock, medium granite. 
 Started, May, 1909; completed, September, 1909. 
 
 Tunnel j: Length, 4,044 feet. Rock, north heading, medium 
 granite; south heading, variable granite, with pockets of CO2 
 gas. Started, March, 1909; completed, July, 191 1. 
 
 Tunnel 4: Length, 2,033 ^^^t. Rock, medium to hard granite. 
 Started, February, 1909; completed, November, 1909. 
 
 Tunnel 5; Length, 1,178 feet. Rock, medium to hard granite. 
 Started, February, 1909; completed, July, 1909. 
 
 Tunnel 6: Length, 411 feet. Rock, medium granite. Started, 
 February, 1909; completed, May, 1909. 
 
 Tunnel y: Length, 3,596 feet. Rock, variable, soft, and 
 swelling in parts. Started, March, 1909; completed, July, 
 1911. 
 
 Tunnel 8: Length, 2,560 feet. Rock, medium to hard, swelling 
 in parts. Started, November, 1909; completed, August, 191 1. 
 
 Tunnel g: Length, 3,506 feet. Rock, medium to hard granite. 
 Started, November, 1909; completed, February, 1911. 
 
 Tunnel 10: Length, 5,755 feet. Rock, medium granite. 
 Started, December, 1909; completed, August, 191 1. 
 
 Tunnel 10 A: Length, 5,961 feet. Rock, medium to hard 
 granite. Started, March, 1910; completed, December, 191 1. 
 
modern mining and water tunnels 43 
 
 Grapevine Division: 
 
 Tunnel 12: Length, 4,900 feet. Rock, hard granite. Started, 
 July, 1909; completed, May, 191 1. 
 
 Tunnel ij: Length, 1,958 feet. Rock, hard granite. Started, 
 May, 1909; completed, April, 1910. 
 
 Tunnel 14: Length, 859 feet. Rock, hard granite. Started, 
 April, 1909; completed, February, 1910. 
 
 Tunnel 15: Length, 895 feet. Rock, hard granite. Started, 
 May, 1909; completed, December, 1909. 
 
 Tunnel 16: Length, 2,723 feet. Rock, hard granite. Started, 
 April, 1909; completed, February, 19 10. 
 
 Tunnel I /": Length, 2,, 022 iect. Rock, hard granite. Started, 
 March, 1909; completed, November, 19 10. 
 
 Tunnel if/2: Length, 1,364 feet. Rock, hard granite. Started, 
 January, 1910; completed, November, 1910. 
 
 Tunnel 17 A: Length, 5,330 feet. Rock, hard granite. Started, 
 January, 19 10; completed, February, 191 2. 
 
 Tunnel 17 B: Length, 9,220 feet. Started, March, 1910; 
 completed, 191 2. 
 Elizabeth Lake Division: 
 
 Elizabeth Lake tunnel: Length, 26,860 feet. Cross-section, 
 "rectangular with arched roof, 12.3 feet high by 12.75 feet wide. 
 Rock, medium to hard granite. Power, electricity. Ventilation, 
 blow and exhaust with blower through 18-inch pipe. Three 
 Leyner drills in each heading. Mounting, horizontal bar. Three 
 shifts per day. Three drillers, three helpers, and nine muckers 
 per shift. Electric haulage, 32-cubic-foot cars. Forty-per-cent 
 gelatine dynamite, 5 to 6 pounds per cubic yard of heading. 
 Sixteen thousand four hundred feet timbered. Average monthly 
 progress per heading, 350 feet. Cost per linear foot of timnel, 
 $40.50. Started, October, 1907; completed, February, 191 1. 
 
 Lucania tunnel: Idaho Springs, Colorado. Purpose, mine 
 development and transportation. Length, 6,385 feet. Cross- 
 section, 8 feet square. Rock, hard granite. Power, purchased 
 electricity. Ventilation, exhaust with blower through 18-inch 
 and 19-inch pipe. Three Leyner drills in the heading. Mount- 
 
44 
 
 MODERN TUNNELING 
 
 ing, vertical column. One shift per day. Three drillers, two 
 helpers, and three muckers per shift. Horse haulage, 22-cubic- 
 foot cars. Fifty-per-cent gelatine dynamite, 8 to 9 pounds per 
 cubic yard of heading. No timbering. Average monthly prog- 
 ress, 125 feet. Cost per linear foot of tunnel, $23.06. Started, 
 1 901; driven intermittently; completed, 191 1. 
 
 Marshall-Russell tunnel: Empire, Colorado. Purpose, mine 
 drainage, development, mining, and transportation. Length, 
 6,400 feet. Cross-section, rectangular, 8 feet wide by 9 feet high. 
 Rock, granite and gneiss. Power, purchased electricity with 
 auxiliary hydrauHc plant. Ventilation, exhaust with fan through 
 12-inch and 13-inch pipe. Two Leyner drills in the heading. 
 Mounting, vertical column. One shift per day. Two drillers, 
 two helpers, and four muckers per shift. Horse haulage, 28- and 
 25-cubic-foot cars. Forty- and 80-per-cent gelatine dynamite. 
 One hundred and fifty feet timbered. Average monthly progress, 
 i6o'feet. Cost per linear foot of tunnel, $18.88. Started, 1901; 
 driven intermittently; completed, 191 1. 
 
 Mission tunnel: Santa Barbara, CaHfornia. Purpose, water 
 supply. Length, 19,560 feet. Cross-section, trapezoid, 4.5 feet 
 wide at the top, 6 feet wide at the base, and 7 feet high. Rock, 
 shale, slate, and hard sandstone. Power, purchased electricity. 
 Ventilation, blow and exhaust with blower through lo-inch pipe. 
 One Leyner drill in the heading. Mounting, horizontal bar. 
 Three shifts per day. One driller, one helper, and four muckers 
 per shift. Electrical haulage, 22-cubic-foot cars. Forty- and 
 60-per-cent gelatine dynamite, 6 to 8 pounds per cubic yard of 
 heading. Five hundred and sixty feet timbered. Average 
 monthly progress, 210 feet. Cost per Hnear foot of tunnel, $19.91. 
 Completed, 191 2. 
 
 Newhouse tunnel: Idaho Springs, Colorado. Purpose, drain- 
 age and transportation. Length, 22,000 feet. Cross-section, 8 
 feet square. Rock, Idaho Springs gneiss. Power, purchased 
 electricity. Ventilation, exhaust with pressure blower through 
 18-inch pipe. Two and three Leyner drills in the heading. 
 Mounting, horizontal bar and vertical column at different times. 
 One and two drill shifts per day. Two and three drillers, two 
 
MODERN MINING AND WATER TUNNELS 45 
 
 helpers, and three muckers per shift. Electric haulage, 57- and 
 35-cubic-foot cars. Forty- and loo-per-cent gelatine dynamite. 
 One thousand feet timbered. Started, 1893; driven intermit- 
 tently; completed, November, 19 10. 
 
 Nisqually tunnel: Alder, Washington. Purpose, hydro- 
 electric power for City of Tacoma. Length, 10,000 feet. Cross- 
 section, rectangular with arched roof, g}4 feet wide by 11 feet 
 high. Rock, rhyolite. Power, hydrauHc and hydro-electric. 
 Ventilation, exhaust with fan through 14-inch pipe. Two 
 Ingersoll-Rand drills at the headworks end, two Leyner drills at 
 the discharge end. Mounting, horizontal bar. Two drilling 
 shifts and three mucking shifts per day. Two drillers, two help- 
 ers, and four muckers per shift. Electric haulage, 27-cubic-foot 
 cars. For ty-per- cent gelatine dynamite. Practically no timber- 
 ing. Average monthly progress per heading, 300 feet. Approxi- 
 mate cost per Hnear foot of tunnel, not including permanent 
 equipment, $15 to $20. Started, 1910; completed, 191 2. 
 
 Ontario tunnel: Park City, Utah. Purpose, mine drainage. 
 Length, 24,000 feet. Cross-section, trapezoid, 5 feet wide at the 
 base, 4 feet wide at the top, 7^^ feet high. Rock, porphyry, 
 granite, quartzite, and limestone. Started, July 25, 1908; sus- 
 pended for several periods of from one to fourteen months; still 
 unfinished. 
 
 Rawley tunnel: Bonanza, Colorado. Purpose, mine drainage 
 and development. Length, 6,235 feet. Cross-section, trapezoid, 
 8 feet wide at the base, 7 feet wide at the top, 7 feet high. Rock, 
 andesite. Power, steam, wood fuel. Ventilation, exhaust with 
 pressure blower through 12 -inch and 13 -inch pipe. Two Leyner 
 drills in the heading. Mounting, horizontal bar. Two and three 
 shifts per day. Two drillers, two helpers, and three muckers per 
 shift. Horse haulage, 17-cubic-foot cars. Forty- and 60-per-cent 
 gelatine dynamite, 6 pounds per cubic yard of heading. One 
 thousand six hundred and eighteen feet timbered. Average 
 monthly progress, 350 feet. Cost per linear foot of tunnel, 
 $19.88. Started, May, 191 1; completed, October, 191 2. 
 
 Raymond tunnel: Ohio City, Colorado. Purpose, mine drain- 
 age and development. Length, 3,200 feet. Cross-section, 9 feet 
 
46 
 
 MODERN TUNNELING 
 
 square. Rock, granite and gneiss. Power, steam. Ventilation, 
 blow and exhaust with blower through 14-inch pipe. Three 
 Leyner drills in the heading. Mo\mting, horizontal bar. One 
 shift per day. Three drillers, two helpers, and two to three 
 muckers per shift. Horse haulage, 32-cubic-foot cars. Forty- 
 and 60-per-cent gelatine dynamite, 3 to 4 pounds per cubic yard 
 of heading. One hundred feet timbered. Average monthly 
 
 Fig. 7. Cross-section, Roosevelt Tunnel. 
 
 progress, 200 feet. Approximate cost per linear foot of tunnel, 
 $15. Started, 1903; driven intermittently; completed, 1912. 
 Roosevelt tunnel: Cripple Creek, Colorado. Purpose, mine 
 drainage. Length, 15,700 feet. Cross-section, see Figure 7. 
 Rock, Pike's Peak granite. Power, purchased electricity. Ven- 
 tilation, exhaust with pressure blower through 16-inch and 17- 
 inch pipe. Two and three Le3mer drills in the heading. Mount- 
 ing, horizontal bar. Three shifts per day. Three drillers, two 
 helpers, and four muckers per shift. Mule haulage, i6-cubic- 
 foot cars. Sixty- and loo-per-cent gelatine dynamite. No tim- 
 bering. Average monthly progress per heading, 285 feet. Cost 
 per linear foot of tunnel, $27.27. Started, February, 1908; com- 
 pleted, November, 1910. 
 
MODERN MINING AND WATER TUNNELS 47 
 
 Sheparcfs Pass tunnel: Oakland, California. Purpose, elec- 
 tric railway. Length, 3,000 feet. Rock, shale. Power, elec- 
 tricity. Ventilation, fan. Three or four Ingersoll-Rand drills 
 per heading. Horizontal bar mounting. One shift per day. 
 Three to four drillers and helpers, four to six muckers (per head- 
 ing) per shift. Electric haulage. Forty-per-cent gelatine 
 dynamite. All timbered, ground very heavy. Average 
 monthly progress, 160 to 175 feet. Started, 1911; completed, 
 
 1913- 
 
 Siwatch tunnel: Leadville, Colorado. Purpose, development. 
 Length, 5,000 feet. Cross-section, rectangular, 6 feet wide by 
 7.5 feet high. Rock, granite. Power, purchased electricity. Ven- 
 tilation, exhaust with pressure blower through lo-inch pipe. 
 Two Waugh stoping drills in the heading. Mounting, horizontal 
 bar. Two shifts per day. Tw^o drillers, no helpers, and two to 
 three muckers per shift. Electric haulage, 33-cubic-foot cars. 
 Forty-per-cent gelatine dynamite. Six hundred feet timbered. 
 Driven intermittently; not yet completed. 
 
 Snake Creek tunnel: Heber, Utah. Purpose, mine drainage 
 and development. Length, 14,000 feet. Cross-section, rectan- 
 gular, 9.5 feet \\ide by 6.5 feet high. Rock, diabase. Power, 
 purchased electricity. Ventilation, exhaust with pressure blower 
 through 16-inch pipe. Two Sullivan drills in the heading. 
 Mounting, horizontal bar. Two shifts per day. Two drillers, 
 two helpers, and three muckers per shift. Horse haulage, 20- 
 cubic-foot cars. Forty- and 60-per-cent gelatine dynamite, 7 
 pounds per cubic yard of heading. Three hundred and fifty 
 feet timbered. Average monthly progress, 250 feet. Started, 
 May, 1 9 10; driven intermittently; not yet completed. 
 
 Stilwell tunnel: Telluride, Colorado. Purpose, mine drainage • 
 and development. Length, 2,600 feet. Cross-section, 7 feet 
 square. Rock, conglomerate and andesite. Power, purchased 
 electricity. Ventilation, exhaust with fan through lo-inch pipe. 
 Two Ingersoll-Sergeant drills in the heading. Mounting, vertical 
 column. One shift per day. Two drillers, two helpers, and three 
 muckers per shift. Horse haulage, 22-cubic-foot cars. Forty-per- 
 cent gelatine dynamite, 8 to 10 pounds per cubic yard of heading. 
 
48 MODERN TUNNELING 
 
 No timbering. Average monthly progress, 150 feet. Cost per 
 linear foot of tunnel, $23.38. Started, 1901; driven intermit- 
 tently; completed, 1906. 
 
 Strawberry tunnel: Wasatch County, Utah. Purpose, irri- 
 gation. Length, 19,100 feet. Cross-section, arched roof, 8 feet 
 wide, gyi feet high. Rock, shale and sandstone. Power, elec- 
 tric. Ventilation, exhaust with pressure blower through 14-inch 
 pipe. Two Sullivan drills in the heading. Mounting, vertical 
 column. Three shifts per day. Two drillers, two helpers, and 
 six muckers per shift. Electric haulage, 47-cubic-foot cars, 
 Forty-per-cent gelatine dynamite, 5 to 6 pounds per cubic yard 
 heading. Two thousand five hundred feet timbered. Average 
 monthly progress, 300 feet. Cost per linear foot of tunnel, $36. 78, 
 Started, 1906; completed, 191 2. 
 
 Utah Metals tunnel: Tooele, Utah. Purpose, transportation. 
 Length, 11,780 feet. Cross-section, rectangular, 10 feet wide by 
 8 feet high. Rock, quartzite. Power, hydraulic. Ventilation, 
 exhaust with fan through 12-inch pipe. Two Ingersoll-Rand 
 drills in the heading. Mounting, horizontal bar. Two shifts per 
 day. Two drillers, two helpers, and four muckers per shift. 
 Electric haulage, 32-cubic-foot cars. Forty- and 60-per-cent gel- 
 atine dynamite, 4 to 5 pounds per cubic yard of heading. Five 
 hundred feet timbered. Average monthly progress, 250 feet. 
 Approximate cost per linear foot of tunnel, $15. Started, 1906; 
 driven intermittently; not yet completed. 
 
 Yak tunnel: Leadville, Colorado. Purpose, transportation 
 and development. Length, 23,800 feet. Cross-section, 7 feet 
 square. Rock, sandstone, limestone, shale, porphyry, and 
 granite. Power, electric. No ventilation suppKed, except by 
 opening compressed-air line. Two Ingersoll-Rand drills in the 
 heading. Mounting, horizontal bar. Three shifts per day. Two 
 drillers, two helpers, and two muckers per shift. Electric haul- 
 age, 30-cubic-foot cars. Forty per cent, gelatine dynamite, 4 to 
 5 pounds per cubic yard of heading. Eight thousand feet tim- 
 bered. Average monthly progress, 200 feet. Approximate cost 
 per linear foot of tunnel, $20. Started, 1886; driven intermit- 
 tently; completed, 19 10. 
 
 i 
 
MODERN MINING AND WATER TUNNELS 49 
 
 MODERN TUNNELS DESCRIBED IN ENGINEERING 
 MAGAZINES 
 
 The following tables are comparable with those above, and 
 give practically similar information concerning certain tunnels 
 which were not examined in the field, but which are quite fully 
 described in engineering periodicals. Although the information 
 contained in these various accounts is, perhaps, somewhat 
 less complete than similar data obtained at other tunnels 
 actually visited, nevertheless it is generally sufficient in each 
 case to convey a good idea of the main features of the 
 work done. 
 
 Buffalo Water Works tunnel: Buffalo, New York. Purpose, 
 water supply. Length, 6,575 feet. Cross-section, nearly rect- 
 angular, 15 feet wide by 15^ feet high. Rock, limestone. Power, 
 steam. Ventilation, tunnel driven under compressed air, no ven- 
 tilation used. Four Ingersoll-Sergeant drills in the heading. 
 Mounting, vertical column. Three shifts per day. Four drillers, 
 four helpers, and ten muckers per shift. Electric haulage, 27- 
 cubic-foot cars. Sixty-per-cent gelatine dynamite, 4.8 pounds 
 per cubic yard of heading. Average monthly progress, 235 feet. 
 Started, July, 1907; completed, April, 1910. Reference, Engin- 
 eering Record, June 25, 1910, page 802. 
 
 Chipeta adit: Ouray, Colorado. Purpose, mine development. 
 Length, 2,000 feet. Cross-section, 7.5 feet square. Power, steam. 
 No ventilation suppKed except by opening compressed-air line. 
 Two Ingersoll-Rand drills in the heading. Mounting, horizontal 
 bar. Two shifts per day. Two drillers, one helper, and four 
 muckers per shift. Mule haulage, 20-cubic-foot cars. Five to 6 
 pounds of explosive per cubic yard of heading. One hundred and 
 fifteen feet timbered. Average monthly progress per heading, 
 340 feet. Approximate cost per linear foot of tunnel, not includ- 
 ing permanent equipment, $12. Started, August, 1907; com- 
 pleted, March, 1908. Reference, Mining and Scientific Press, 
 July II, 1908, page 60. 
 
 Cornelius Gap tunnel: Near Portland, Oregon. Purpose, elec- 
 tric railway. Cross-section, arched roof, 17.5 feet wide by 22.5 
 
50 MODERN TUNNELING 
 
 feet high. Length, 4,100 feet. Rock, basalt. Reference, Engi- 
 neering News, June 29, 191 1, page 783. 
 
 Fort Williams Water tunnel: Fort Williams, Ontario. Pur- 
 pose, water supply. Length, 4,820 feet. Cross-section, rectan- 
 gular with arched roof, 5 feet wide, 6.5 feet high. Rock, basalt. 
 Power, electric. Ventilation, blow with fan through 15-inch 
 pipe. One Ingersoll-Rand drill in heading. Mounting, vertical 
 column. Two and three shifts per day. One driller, one helper, 
 and three muckers per shift. Eighteen-cubic-foot cars. Forty- 
 per cent, gelatine dynamite, 5 to 10 pounds per cubic yard of 
 heading. Lined with concrete. Average monthly progress per 
 heading, 85 feet. Cost per Hnear foot of tunnel, $27.89. Started, 
 May, 1907; completed. May, 1909. Reference, Engineering and 
 Contracting, May 25, 1910, page 472. 
 
 Grand Central tunnel: New York City. Purpose, sewer. 
 Length, 3,000 feet. Cross-section, circular, 8 feet in diameter. 
 Rock, gneiss. No ventilation supplied, except by opening com- 
 pressed-air Hne. Two and three Ingersoll-Rand and SulHvan 
 drills in the heading. Mountings vertical column. One shift per 
 day. Two and three drillers, two and three helpers, and two 
 muckers per shift. Used a J^-cubic-foot bucket on a fiat car. 
 Started, 1907; completed, 1908. Reieience, Engineering Record,. 
 April II, 1908, page 496. 
 
 Joker tunnel: Red Mountain, Colorado. Purpose, mine drain- 
 age and development. Length, 5,055 feet. Cross-section, rect- 
 angular, 12 feet wide, 11 feet high. Power, steam. Ventilation, 
 exhaust with fan through 15-inch pipe. Two and three Leyner 
 drills in the heading. Mounting, vertical column. One drill 
 shift and two mucking shifts per day. Two and three drillers, 
 two helpers, and four muckers per shift. Mule haulage, 30-cubic- 
 foot cars. Practically all timbered. Average monthly progress, 
 215 feet. Completed, 1907. Reference, Mines and Minerals, 
 May, 1907, page 470. 
 
 Kellogg tunnel: Wardner, Idaho. Purpose, mine development. 
 Length, 9,000 feet. Cross-section, arched roof, 9 feet wide and 
 1 1 feet high. Rock, quartzite. Reference, Mines and Minerals, 
 October, 1901, page 122. 
 
 ill 
 
MODERN MINING AND WATER TUNNELS 51 
 
 Mount Royal tunnel: Montreal, Canada. Purpose, railroad. 
 Length, 3.25 miles. Cross-section, rectangular with arched roof, 
 during construction 30.5 feet wide and 21.25 feet high, when 
 completed will be twin tubes each 13.5 feet wide and 14 feet high, 
 separated by an 18-inch wall of concrete. Rock, limestone and 
 volcanic breccia. Power, purchased electricity. Ventilation, 
 pressure blower. Three or four Sullivan water drills per heading. 
 Mounting, horizontal bar and special drill carriage. Three shifts 
 per day; four drillers, four helpers, and six muckers per shift. 
 Electric haulage. Sixty-per-cent gelatine dynamite. Average 
 progress in No. i heading, first eight months, 351 feet. Refer- 
 ences, Engineering and Mining Journal, July 26, 1913, pages 
 147-49; Mine and Quarry, August 1913, pages 730-39. 
 
 Northwest Water tunnel: Chicago, IlHnois. Purpose, water 
 supply. Length, 21,180 feet. Cross-section, horseshoe, area 
 equivalent to 14-foot circle. Rock, limestone. No ventilation 
 supplied, except by opening compressed-air Hne. Four Ingersoll- 
 Rand drills in the heading. Mounting, vertical column. Two 
 shifts per day. Four drillers, four helpers, and six muckers per 
 shift. Mule haulage, 22-cubic-foot cars. Average monthly 
 progress per heading, 400 feet. Reference, Engineering Record, 
 August 7, 1909, page 144. 
 
 Ophelia tunnel: Cripple Creek, Colorado. Purpose, mine 
 drainage and development. Length, 8,500 feet. Cross-section, 
 9 feet square. Rock, granite and breccia. Power, steam. Ven- 
 tilation, blow with pressure blower through 15-inch pipe. Two 
 SulKvan drills in the heading. Mounting, vertical column. 
 Three shifts per day. Two drillers, two helpers, and three 
 muckers per shift. Compressed air haulage. Average monthly 
 progress, 350 feet. Started, 1905; completed, 1907. Reference, 
 Mine and Quarry, May, 1907, page 118. 
 
 Roger^s Pass tunnel: Between Ross Peak and Beaver Mouth, 
 British Columbia. Purpose, railroad. Length, 25,900 feet. 
 Cross-section, rectangular with arched roof. Will be driven from 
 a center heading 14 feet wide and 8 feet high and from an auxil- 
 iary heading 30-50 feet to one side of the main heading, 8 feet 
 wide and 7 feet high. Rock, shale and quartzite. Power, steam. 
 
52 
 
 MODERN TUNNELING 
 
 Ventilation, pressure blower. Three Ingersoll-Leyner drills per 
 heading. Horizontal bar mounting. Three shifts per day. 
 Three drillers, two helpers, and four to six muckers per shift. 
 Mule haulage. Work on portal excavation started August, 19 13. 
 Reference, private communication to the authors. 
 
 Second Raton Hill tunnel: Raton Pass, Colorado. Purpose, 
 railway. Length, 2,790 feet. Cross-section, horseshoe, 22 feet 
 wide and 29 feet high. Rock, shale, sandstone, and a 3-foot bed 
 of soft coal. Reference, Engineering Record, April 4, 1908, page 
 461. 
 
 ^^SpiraV^ tunnels: Selkirk Moimtain, British Columbia. Pur- 
 pose, railway. Length, No. i, 3,200 feet; No. 2, 2,890 feet. 
 Cross-section, arched roof, 22 feet wide, 27 feet high. Rock, 
 Hmestone. Power, steam. Six and eight IngersoU-Rand drills 
 in the heading. Mounting, vertical colimin. Two shifts per day. 
 Six and eight drillers, six and eight helpers per shift. A Marion 
 shovel operated by compressed air used for mucking. Horse 
 haulage, 108-cubic-foot cars. All timbered. Average monthly 
 progress per heading, 105 feet. Started, January, 1908; com- 
 pleted, June, 1909. References, Engineering News, November 10, 
 1 9 10, page 512; Compressed Air Magazine, February, 191 1, page 
 5,931- 
 
CHAPTER IV 
 
 CHOICE OF POWER FOR TUNNEL WORK 
 
 SOURCES OF POWER 
 
 While the power for tunnel operations may be obtained from 
 various sources, in general practice at present it is produced 
 primarily from either steam or flowing water. Although, as far 
 as could be ascertained, the gas-producer used in connection with 
 internal-combustion engines has been installed at but one tunnel, 
 nevertheless it offers a third possibility as a source of power 
 which will have to be considered more and more seriously in the 
 design of future plants. It is true that in the early stages of its 
 development, when the principles governing its design, construc- 
 tion, and operation were not well understood, the gas-producer 
 was not reliable and acquired a bad reputation among tunnel 
 men, a situation augmented perhaps by the extravagant claims 
 of manufacturers or the overzealousness of salesmen. But within 
 the last few years, as its principles have become better known 
 through study and experiment, the gas-producer has developed 
 rapidly — so rapidly, in fact, that few people realize that it is 
 to-day as rehable and rugged a piece of apparatus as an ordinary 
 boiler, or that its consumption of fuel is only one-third as great, 
 or that the labor to operate it need not be one whit more skilled. 
 It is true that gasoKne engines are occasionally used to furnish 
 power in tunnel operations, but they have been confined either to 
 temporary plants or to small and isolated units of machinery. 
 In localities where petroleum is cheap, it is probable that an oil 
 engine of the Diesel type, with its wonderful fuel economy, 
 may be found the cheapest means of producing power. Elec- 
 tricity, especially where it is used at tunnel plants to operate 
 prime moving machinery, is sometimes considered a source of 
 power; but since the current so employed has to be generated 
 elsewhere, usually from steam or water, but possibly from pro- 
 
 53 
 
54 
 
 MODERN TUXXELIXG 
 
 ducer gas, petroleum, or gasoline, electricity is merely a conve- 
 nient form for transmitting power instead of a source. 
 
 PRODUCTION OF POWER 
 
 Water-power. — In tunneling the machines most frequently 
 employed for the utilization of water-power are of the impulse 
 type, similar to the Pelton wheel, illustrated in Figure 8. Such 
 
 Standard Pelton wheel. 
 
 a wheel is driven by the force of a stream of water issuing from 
 a nozle, acting against vanes or buckets on the circumference 
 of the wheel, and is well adapted for use with a relatively small 
 volume of water under high head. The efficiency of the machine 
 is dependent upon the way the vanes or buckets reverse the direc- 
 tion of the water discharged upon them; hence they usually 
 conform to a curve which is very carefully designed to avoid 
 loss of power through eddies and friction as the water strikes the 
 vane. There may be more than one nozle in order to obtain 
 greater power, or, if high rotative speed is desired, a small wheel 
 
CHOICE OF POWER FOR TUNNEL WORK 55 
 
 with multiple nozles may be substituted for a large one. In 
 order to obtain the best results, the peripheral speed of the cups 
 or vanes should be betweei; 42 and 48 per cent of the speed of 
 the water issuing from the nozle. Impulse wheels are manufac- 
 tured in many different designs, sizes, and speeds, adapted for 
 working under widely diverse conditions. Those observed at 
 the different tunnels examined were, as far as could be learned, 
 giving very satisfactory service. 
 
 The turbine wheel, in which the force of the water is made to 
 act through suitable guides upon all the vanes or blades simul- 
 taneously, affords another means of utilizing water-power and 
 may be designed for either high or low heads. Its use is limited, 
 however, especially with high heads, to locaKties where clear 
 water is available (as, for example, at Niagara Falls) because of 
 the destructive abrasive action of sand and grit upon the guides. 
 With low heads this action is not so marked. Since the source 
 of water-power in the vicinity of tunnels and adits is in most 
 cases to be found in streams furnishing high heads and which at 
 certain seasons of the year carry large amounts of sediment, the 
 use of turbine wheels for such plants is prohibitive unless large 
 setthng basins can be provided. 
 
 The hydraulic compressor, converting the energy of water 
 directly into compressed air, offers a third method for utiHzing 
 water-power. The earliest type operates upon the principle of 
 the hydraulic ram, in which a column of water is allowed to ac- 
 quire velocity and is then suddenly checked, developing intermit- 
 tently for a short space of time pressure much greater than that 
 due to the head of the column of water. This pressure is em- 
 ployed in compressing air. Sommeiller in about i860 designed a 
 machine of this type for use at the Mt. Cenis tunnel. Such 
 compressors require rather high heads and have low efficiency. 
 Although conditions might be such as to make the use of com- 
 pressors of this type desirable, the water-power they require can 
 generally be utihzed more advantageously in some other manner. 
 
 The hydraulic compressor recently developed by C. H. Taylor, 
 introducing air into a column of water and compressing it as they 
 fall together to the bottom of a shaft where the air is separated 
 
56 
 
 MODERN TUNNELING 
 
 and collected, is very efficient and requires only a small amount 
 of attention, although the cost of construction prohibits its use 
 except for installations much larger than those ordinarily re- 
 quired for tunnel work. The latest installation of this system, 
 which was completed in June, 1910, is situated at Ragged Chutes, 
 
 Fig. 9. Diagrammatic section through Taylor hydraulic compressor at 
 Cobalt. 
 
 on the Montreal River, and supplies air to the mining district 
 near Cobalt, Ontario. 
 
 At this plant, a concrete dam diverts water from the river, 
 above the rapids, to the tops of two circular shafts 8^ feet in 
 diameter, where, by means of suitable apparatus, a large quan- 
 tity of air is introduced into the water in the form of bubbles. 
 The mixed water and air descend the shafts (350 feet in depth) 
 and start through a passage 1,000 feet long. The passage as 
 shown in Figure 9 is so designed that the compressed air is 
 permitted to rise to the surface of the water and is collected. 
 
CHOICE OF POWER FOR TUNNEL WORK 57 
 
 partly along the top of the passage and partly in a large collecting 
 chamber which has been excavated near the end of the passage. 
 The waste water then rises 298 feet through a shaft 22 feet in 
 diameter and is discharged into the river below the rapids. 
 The air is drawn from the top of the chamber at a pressure of 
 120 pounds to the square inch and is transmitted by a 20-inch 
 main to the mines nine miles distant. The capacity of the 
 plant is the compression of 40,000 cubic feet of free air per 
 minute to 120 pounds per square inch. 
 
 The familiar overshot, breast, and undershot wheels are not 
 used to drive machinery for tunnel work, because of their large 
 size for the amount of power developed, as well as the trouble of 
 their maintenance. The overshot wheel utilizes the weight of 
 the water, chiefly, and is best suited for low heads. Its efficiency 
 is greatest when enough water is supplied to fill the buckets 
 completely. The breast wheel utilizes both the weight and the 
 velocity of the water, and its efiiciency is less, though it can be 
 used with even lower heads of water than the overshot wheel. 
 The undershot wheel uses only the velocity of the water, and has 
 the least efficiency of the three types, but it requires practically 
 no head. Its efficiency is at a maximum when the water is con- 
 fined laterally. 
 
 The following table, which is based upon actual results, 
 shows the efficiency of different types of water motors: 
 
 PERCENTAGE OF THEORETICAL HORSE-POWER REALIZED 
 BY VARIOUS WATER MOTORS 
 
 Impulse wheels 70-85% 
 
 Turbine wheels 75-85 
 
 Overshot wheels 60-65 
 
 Breast wheels 50-60 
 
 Undershot wheels 30-50 
 
 Results obtained at the testing flume of the Holyoke (Mass.) 
 Water Company, whose tests are taken as standard by American 
 engineers, show efficiencies for turbine wheels under favorable 
 conditions of over 90 per cent,* but this is unusual, the figures 
 
 * Trans. A. S. C. E., Vol. XLIV (1910), p. 322. 
 
58 MODERN TUNNELING 
 
 above being much nearer ordinary practice. The efi&ciency of 
 hydraulic compressors of the rarti type is about 30 to 40 per cent, 
 while the Taylor compressor at Cobalt is said to utilize at least 
 75 per cent of the theoretical power of the water. 
 
 Steam. — Steam engines are of two types, reciprocating and 
 turbine. In the reciprocating engine, power is developed by the 
 pressure and expansion of steam in a cylinder acting against a 
 moving piston. Such engines may be either simple or compound, 
 both forms being used in tunnel plants. In the former, the 
 total expansion of the steam and consequent reduction of press- 
 ure take place in one cyhnder, while in the latter only a portion 
 of the expansion takes place in the first cylinder, and the steam, 
 under somewhat reduced pressure, is expanded further in a 
 second cylinder, necessarily larger because of the lower pressure 
 of the steam. 
 
 The steam turbine is similar in principle to the water-wheel, 
 except that steam instead of water is the motive fluid. Owing 
 to their economy, small size per unit of power, and freedom 
 from vibration, their use is steadily increasing on both 
 land and sea. Modern steam turbines in sizes of 250 to 
 500 horse-power, with a steam pressure of 150 pounds and 
 a 28-inch vacuum, will develop a kilowatt-hour with a con- 
 sumption of from 18 to 20 pounds of steam. A recently published 
 series of shop tests on a 300-kilowatt Swiss condensing turbine 
 showed that with 112^ pounds of steam and a 96.6 per 
 cent, vacuum it was able to produce a kilowatt-hour with 16.1 
 pounds of steam. The difliculty of reducing the high rotative 
 speed of the turbine engine down to the restricted speed of 
 reciprocating machinery has prevented, until recently, the use of 
 turbine engines in tunnel installations; but, with the advent 
 of the turbo-compressor, we may expect to see them dividing 
 the field, or, perhaps, entirely displacing the cumbersome 
 reciprocating plants now in vogue. 
 
 Internal Combustion. — Internal-combustion engines devel- 
 op power from the pressure produced by the explosion or rapid 
 combustion (confined in a suitable cylinder) of a mixture con- 
 taining the proper proportions of air and a gasified fuel. The 
 
 ji 
 
CHOICE OF POWER FOR TUNNEL WORK 59 
 
 source of the fuel gas may be gasoline, kerosene distillate, or 
 even crude petroleum, or it may be generated from coal by dis- 
 tillation in a retort, or by a gas-producer, and the engines are 
 usually designated by the kind of fuel for which they are adapted, 
 as, for example, oil engines, gasoKne engines, or producer-gas 
 engines. As far as could be ascertained these latter two are 
 the only types now used in tunneling. -4 
 
 Although the gasoline engine has been developed with 
 wonderful rapidity during the last twenty-five years in con- 
 nection with the automobile industry, the use of engines of 
 this type for tunnel work has been confined to a very limited 
 field, viz., the operation of isolated or not easily accessible 
 machinery. As prime movers for tunnel plants of any magni- 
 tude they cannot compete, under most circumstances, with 
 machines using other forms of power, and, on this account, their 
 application has been confined either to enterprises small in 
 scope or to the temporary and early development stage of larger 
 projects, where they are sometimes installed to begin the work 
 at locations by nature inaccessible for non-portable units of 
 heavier machinery, pending the construction of a special road- 
 way or a transmission line. Most manufacturers of air com- 
 pressors have recently begun to supply air compressors directly 
 driven by internal combustion engines, although as yet only the 
 smaller sizes of gasoline engines are being used. With suitable 
 adaptations, the principle might be applied equally well to the 
 larger sizes using oil or gas as fuel. Within the last two years 
 gasoline engines have been successfully employed in locomotives 
 for haulage in coal mines, and there are now over one hundred of 
 them in operation. These machines are equally suitable for 
 tunneling operations, and will, no doubt, be used extensively 
 for this purpose in the near future. 
 
 The only use of producer-gas engines in tunnel work to date, 
 as far as could be learned, was at the power plant for the tunnel 
 under the Thames River recently completed connecting North 
 and South Woolwich. Since the tunnel was constructed under 
 compressed-air pressure, absolute reliability in the power plant 
 was required to avoid a stoppage of pressure which might 
 
60 MODERN TUNNELING 
 
 possibly result in serious damage to the tunnel. At this plant, 
 as described in The Engineer,^ three engines, each of 150 b. h. p. 
 when running at 180 revolutions per minute, were supplied 
 with gas from suction producers using Scotch anthracite coal, 
 and were connected to a central shaft which transmitted power 
 to four air compressors and four dynamos. The plant was 
 operated continuously from July, 19 10, imtil the end of Decem- 
 ber, 191 1, except during October and November, 1910, when 
 after the vertical shaft had been completed the plant was pur- 
 posely stopped while making preparations to start timneling. 
 Although it is not within the province of this report to 
 discuss the gas-producer in any detail, the following brief descrip- 
 tion is quoted from Bureau of Mines Bulletin 16: 
 
 "The simplest form of gas-producer for power-gas generation is a 
 vertical cylinder of iron or masonry, lined with fire-brick, having a 
 grate, near the bottom, an opening in the top for charging fuel, a 
 smaller opening near the top for the outlet of the gas, and one near the 
 bottom for the admission of air. Openings are also provided at 
 various heights on the sides, through which the interior may be 
 reached for poking the fuel bed, inspecting and cleaning the interior, 
 making repairs, and removing ashes. To prevent the entrance of air 
 except through the proper openings, which are covered by gas-tight 
 doors, the charging opening is generally a small chamber, guarded by 
 gas-tight doors at the bottom and top, which prevents the escape 
 of the gas and the ingress of air while the producer is being 
 recharged. 
 
 Simple gas-producers such as described above furnish uncleansed 
 gas, which contains so much dust and other foreign matter that it is 
 unsatisfactory for use, especially in gas engines. Power-gas pro- 
 ducers are therefore provided with apparatus for cleansing the gas, 
 known as scrubbers, through which the gas passes after lea\dng the 
 producer. The scrubber in its simplest form is a cylindricar chamber 
 filled with some porous material like coke or sha\ings, which is kept 
 constantly wet. The gas, in passing through this wet material, 
 leaves behind most of the solid and liquid impurities it contains. 
 
 In addition to the scrubber, many gas-producers have attach- 
 ments for preheating the air admitted for combustion, so that it 
 enters the fire at a temperature sufficiently high to prevent cooling 
 
 * The Engineer, London, January 12, 1912, p. 46: "Temporary Power 
 Plant for Woolwich Footway Tunnel," two pages illustrated. 
 
CHOICE OF POWER FOR TUNNEL WORK 61 
 
 of the fuel. Such attachments make use of the heat of the off-going 
 gases, and are called regenerators. 
 
 The form of producer in most general use for generating gas 
 for the development of power, especially in gas engines, is that supply- 
 ing gas directly to the engine, which draws the air and steam through 
 the fuel bed by means of the suction stroke of the piston. The 
 suction-producer, as it is termed, has been largely restricted to the use 
 of anthracite, coke, charcoal, and other fuels containing a low per- 
 centage of tarry compounds. When bituminous fuels are used these 
 tarry compounds are likely to be carried over with the fixed gases 
 into the engine and, condensing there, clog the valves, pipes, and other 
 working parts, despite scrubbing apparatus. Recent improvements 
 in methods of scrubbing, however, have so modified the older practice 
 as to make the use of fuels rich in volatiles comparatively free from 
 such accidents, and their use in the suction type of producer is in- 
 creasing. 
 
 The pressure gas-producer is so designed that the air and steam 
 necessary to develop the gas are forced into the fuel bed under enough 
 pressure to drive the gases generated through the fuel bed and scrub- 
 bing apparatus into a gas holder. The gas is thus generated indepen- 
 dently of the piston stroke of the engine, and may be thoroughly 
 cleansed of tars and ash before it is used. For this reason the pressure 
 type of gas-producer is well fitted for using bituminous coal, lignite, and 
 peat. The down-draught or inverted-draught gas-producer, in which 
 the heavier products of distillation are all decomposed and changed 
 into simple permanent gases, constitutes a third type. In power-gas 
 producers of this type the heated gases, rich in vaporized hydrocarbons, 
 tars, and heavy gases, are drawn by exhaust fans from the top of the 
 producer, where they accumulate above the freshly added fuel, down 
 through the fuel bed. In the fuel bed, by contact with the heated 
 carbon, they are converted into carbon monoxide and hydrogen, which, 
 after cleansing, can be either stored in receivers or used in engines." 
 
 The essential principles in the process of making gas in a 
 producer may be outlined very briefly as follows: In comparison 
 with steam-boiler practice, the fuel bed is very deep and con- 
 tains three zones — combustion, incandescence, and distillation. 
 A portion of the coal is burned in the combustion zone, where a 
 limited amount of air is supplied for this purpose, and the 
 resulting gases are passed through the remainder of the fuel 
 bed. In the incandescent zone the hot gases combine chemically 
 with some of the constituents of the glowing coal (unburnt 
 
62 
 
 MODERN TUNNELING 
 
 as yet, because of lack of air) and form new gases which have a 
 fuel value. These, together with the gases driven off from the 
 fresh coal by heat in the distillation zone, supply the fuel portion 
 of the mixture exploded in the engine. Steam is also employed 
 in most types of gas-producers because its introduction with the 
 air for combustion assists in the formation of gases of the right 
 composition. 
 
 For a more detailed discussion of this subject the reader 
 is referred to the bibliography accompanying this volume. 
 
 Although, as far as could be learned, oil engines of the Diesel 
 type have not yet been employed in tunnel power plants, their 
 marked success in other fields more than -warrants the dis- 
 cussion of the possibility of their use in tunnel work. The 
 essential feature which differentiates the Diesel machine from 
 other internal-combustion engines is the fact that instead of draw- 
 ing into the cylinder an explosive mixture containing a com- 
 bustible gas (such as producer-gas, gasohne vapor, kerosene, or 
 even crude petroleum previously volatilized by heat), and then 
 compressing this mixture and exploding it by means of an 
 electric spark or some other suitable device, the Diesel engine 
 compresses air alone, and when it is under its highest pressure 
 (approximately 300 pounds per square inch, which is much 
 greater than that usually attained in other types of internal 
 combustion engines) injects into the cyHnder a spray of finely 
 atomized oil. During the compression of the air to the required 
 pressure it will have reached a temperature of more than 1000° F., 
 more than sufficient to ignite the oil instantly without the use 
 of an electric spark, hot plate, or other similar device. 
 
 The chief advantage of the Diesel engine is economy of fuel. 
 It is a well-known fact that the rapidity and completeness of 
 any combustion are greatly increased by pressure; it is not 
 surprising, therefore, that under the higher pressures which 
 prevail in this machine better results can be obtained from a 
 smaller amount of oil. The extremely fine atomization of the 
 fuel due to the jet of compressed air (under a pressure of 300 
 to 500 pounds per square inch higher than that in the cylinder) 
 by which the oil is injected is undoubtedly another great con- 
 
CHOICE OF POWER FOR TUNNEL WORK 63 
 
 tributing factor. And again, since the scavenging of the exhaust 
 gases from the previous explosion is effected by air only, instead 
 of a mixture of air and fuel, as is the case in other types of internal- 
 combustion engines, there is no possibilijty of loss of fuel through 
 the exhaust valves during this process, a saving which is ex- 
 tremely important where the engines are designed for a two- 
 stroke cycle. 
 
 In addition to the advantage of fuel economy, however, 
 the Diesel engine does not require frequent cleaning, as is the 
 case with oil engines depending upon a hot plate or a similar 
 device for the ignition of the explosive mixture. It also dis- 
 penses with the carbureter, so necessary for the gasoHne engine, 
 and which is always a source of more or less trouble and annoy- 
 ance. And, in addition, since the mixture being compressed in 
 the cylinder of a Diesel engine is not an explosive one, allowance 
 does not have to be made in the design of the cyhnder and other 
 parts for undue stresses and strains which might result from a 
 premature ignition of the charge, caused, perhaps, by a glowing 
 piece of carbon on the cylinder wall or by a heated piston, 
 an occurrence which is not infrequent in other engines, as any 
 automobilist will testify. Although some provision can, of 
 course, be made for these shocks, their force and violence cannot 
 always be correctly foreseen or sufficient allowance made for 
 them, and there have been many instances of disastrous results 
 arising from premature ignitions in internal-combustion engines 
 of the usual types. 
 
 The principal disadvantage of the Diesel engine, on the other 
 hand, is that of high first cost, and this would prohibit its use for 
 tunnel work of short duration. The price of this machine has 
 recently been greatly reduced abroad, however, and it is certain 
 to be reduced in America, now that manufacturers in this 
 country are equipped with suitable apparatus and prepared to 
 execute the high class of workmanship required in its con- 
 struction, so that in the near future this drawback may dis- 
 appear. But even now, if the time required for the completion 
 of the work is to be long enough, or the amount of power to be 
 used is great enough to warrant a heavy initial outlay in order 
 
64 MODERN TUNNELING 
 
 to effect a saving in operating cost, the choice of a Diesel engine 
 should be seriously considered. 
 
 Electric Motors. — Electric motors may be designed either 
 for direct or alternating current. Where used as prime movers 
 at the tunnel plants visited they were of the second type only 
 and operated at comparatively low voltages, 440 volts being the 
 usual figure. Their power was generally transmitted to the 
 remainder of the machinery by means of belts, but at one or 
 two places on the New York Aqueduct, ^'direct-connected" 
 electric-driven air compressors were noticed. 
 
 TRANSMISSION OF POWER 
 
 Electricity, because of its economy and its freedom from 
 limiting distances, is the favored means for transmitting to a 
 tunnel the power generated at some remote station. It pos- 
 sesses one well-known disadvantage, that of occasional inter- 
 ruption, especially where distances are great and tension high, 
 because of unavoidable hindrance to service due to electrical 
 storms or other atmospheric agencies. On the other hand, 
 producer-gas transmission has possibilities which deserve to be 
 considered seriously in this connection. This form of conveying 
 power has been recently taken up from the realm of mere con- 
 jecture and demonstrated as a practical system, both in this 
 country, at Pittsburgh where natural gas is piped over distances 
 as great as 200 miles, and in England, where producer gas is 
 supplied to points within a radius of 160 miles, with trans- 
 mission losses even less than when electricity is used. In its 
 appKcation to tunnel operations, producer gas can be generated 
 in a plant conveniently situated on a railroad siding or some 
 other readily accessible place, and the power piped to internal- 
 combustion engines at the tunnel portal. 
 
 Where distances are comparatively short (that is, less than 
 five miles or so) electricity is rivaled by compressed air, and 
 the competition grows more keen as the length of the trans- 
 mission system decreases. This is possible because where 
 pneumatic drills are employed, compressed air, in spite of its 
 
 I 
 
CHOICE OF POWER FOR TUNNEL WORK 65 
 
 low efficiency and high cost, is necessary for their operation; 
 and even were electric transmission chosen, the power would 
 need to be converted ultimately into compressed air at the 
 tunnel. Hence it is the usual practice to produce the compressed 
 air at once, thus avoiding the extra machinery and the additional 
 operating losses of electric transmission. 
 
 CHOICE OF POWER 
 
 A number of factors enter into the choice of power for tun- 
 neling operations. To begin with, the plant is usually short 
 lived. Then, too, the influence of such local conditions as 
 accessibility, distance from a railroad, the availability of water- 
 power, etc., is strongly felt. Each method of deriving power 
 has also certain peculiarities which render it particularly adapt- 
 able to different conditions. Among these may be mentioned 
 the cost of installation, of labor, of fuel, of interest and deprecia- 
 tion, and other operating expenses. Aside from all this, it is 
 often necessary to decide between the production of power at 
 the plant or elsewhere and the purchase of power from an 
 established hydro-electric company. Some of these factors we 
 shall discuss briefly. 
 
 Duration of Plant. — At many tunnel power plants, in di- 
 rect contrast with those used in manufacturing, the equipment is 
 required only for the comparatively short time of actual tunnel 
 construction. Thus it becomes a delicate problem to determine 
 just how far one is justified in the purchase of machinery and 
 apparatus for utilizing all the various economies that may be 
 effected in the production of power. It is difficult to decide 
 whether it would not be better in the end to instaU less costly 
 machinery that would necessitate slightly higher expense in 
 operating and maintaining than to tie up extra capital in 
 equipment that would be of no further use when the tunnel is 
 completed. Of course, the shorter the probable life of the 
 plant the more would one be justified in such a course; although, 
 if the equipment can be transferred upon the completion of the 
 tunnel to other projects, this would so prolong its period of 
 
66 MODERN TUNNELING 
 
 usefulness that the original expenditure of capital could properly 
 and with true economy be greater. A notable instance of this 
 was observed on the Los Angeles Aqueduct, where as far as 
 possible, upon the completion of one of the numerous timnels, 
 the equipment was transferred and used in power plants at other 
 tunnels whose construction had not yet been begun. If a central 
 station is being considered, where a large amount of power is 
 to be generated, the purchase of apparatus from the main view- 
 point of economy in operation is again the far-sighted poKcy. 
 This was the case at the Rondout Siphon Tunnel, but at the 
 average mining tunnel or adit the converse is more often likely 
 to be true. 
 
 Accessibility. — Tunnels are often located at places very 
 difhcult of access. They may be so situated as to make the 
 installation of heavy machinery no easy matter, as, for example, 
 where the road from the nearest railroad is poor and the grade 
 very steep; or they may be at a great distance from the nearest 
 siding, so that if a form of power be chosen that requires coal, 
 the deHvery of this fuel is not only very costly, but also most 
 uncertain and difhcult in some seasons of the year. Such 
 conditions are favorable for the adoption of power transmission 
 in some form from a waterfall or rapid, if one be located near 
 enough, or, lacking these natural advantages, from a fuel plant 
 installed at some point more readily accessible. 
 
 Cost of Installation. — The cost of installing water-wheels 
 is entirely dependent upon local conditions, which are never twice 
 alike. Where high heads are available and the quantity of 
 water required is not large, it can be conveyed to the water- 
 wheel by small flumes or pipes which are comparatively inex- 
 pensive. For example, at the Carter tunnel (see Figure lo), with 
 an available head of 145 feet, a flume 16 by 48 inches inside 
 and 5,000 feet in length is sufficient to supply the 200 horse- 
 power developed. At the Laramie-Poudre tunnel, with a 
 static head of 268 feet, 400 horse-power was conveyed to the 
 tunnel plant by a wooden-stave 22-inch pipe line, 8,500 feet in 
 length. The Utah Metals tunnel secures water from two 
 sources: the first has a 700-foot head, using 2,500 feet of 12-inch, 
 
 ii 
 
CHOICE OF POWER FOR TUNNEL WORK 
 
 67 
 
 1,900 feet of lo-inch, and 100 feet of 8-inch spiral steel riveted 
 pipe, furnishing 170 horse-power; the second, with 750 foot 
 head, employs 2,000 feet of 12 -inch, 1,000 feet of 8-inch, 3,000 
 feet of 6-inch pipe in producing 55 horse-power. Where heads 
 are low, however, retaining dams are usually necessary. At 
 
 e ry^.;- 
 
 Fig. 10. View showing end of flume, mill, dump, and other surface features 
 at Carter tunnel. 
 
 best these are a costly expedient and their expense increases 
 enormously with their height. With low heads, larger flumes 
 are also required to convey the greater quantity of water. 
 At the Nisqually tunnel, illustrated in Figure 11, a low dam and 
 a wooden flume 6 by 8 feet in cross-section and 1,200 feet long 
 were used. The water was delivered to a turbine wheel under 
 an effective head of 29 feet which generates 1,000 horse-power. 
 One has only to consider some of the very expensive dams on the 
 
CHOICE OF POWER FOR TUNNEL WORK 69 
 
 larger rivers, furnishing power for manufacturing purposes, in 
 order to realize how great the cost of installation may be where 
 low heads only are utilized. It is fortunately true, however, 
 that where water-power is obtainable for tunnel work high 
 heads are usually available also, and the less expensive flumes 
 or pipe lines of moderate length can be utilized. 
 
 The cost of the machinery actually within a tunnel power- 
 house is greater for steam than for water-power or electricity; 
 but if, as should be done to make the figures truly comparable, 
 the cost of the dam and flume (or of the transmission Hne for 
 electricity) be taken into consideration, the advantage is usually 
 reversed. It is somewhat cheaper to install a steam plant than 
 one using producer gas and having engines of the same capacity, 
 but the difference is not great. R. H. Fernald,* after a study 
 of many tables of costs, applying to other uses, however, than 
 tunnel work, concludes that ''complete producer-gas installa- 
 tions for the larger plants, say from 4,000 to 5,000 horse-power, 
 cost about the same as those of first-class steam plants of the 
 same rating. With smaller installations the balance is prob- 
 ably in favor of the steam plant." Since it is not customary 
 in tunnel work to install machinery designed to effect all the 
 refinements of steam economy found in permanent plants, it is 
 probable that the first cost of the average steam plant for tunnel 
 work is less than those upon which Mr. Fernald's estimates 
 are based, in which case the comparison would be even more 
 favorable to steam. This is partly offset by the fact that the 
 price of gas-producers and engines is constantly being lowered, 
 and by the fact that the cost of actually placing the machinery 
 would be less for the gas-producer — considerably in some cases, 
 appreciably in all. 
 
 The initial expense of installing any of the various systems 
 for transmitting power is dependent upon two factors: (i) the 
 cost of the machinery required to produce the power, to convert 
 it into the form suitable for transmission, and to reconvert 
 it into the form adapted to the machines using it; and (2) the 
 
 * Bull. 9, B. of M., p. 31. 
 
70 MODERN TUNNELING 
 
 cost of the transmission line. Except for a slight increase in 
 capacity, to provide for losses in transmission, the factor of 
 machinery cost under any given conditions is independent of 
 the distance over which power is to be delivered, but the cost 
 of the line, as will become apparent later, increases considerably 
 faster than its length, other things being equal. If the power is 
 required ultimately for the operation of air drills, practically 
 the same size of compressor will be necessary whether electric, 
 air, or gas transmission is employed, and the cost of boiler, 
 engine, foundations, etc., in the case of electricity or air will 
 approximately balance the cost of the producer, engine, founda- 
 tions, etc., for gas. Air transmission would require practically 
 no other machinery than that just mentioned; but gas, on 
 the other hand, would need a blower of some sort to force it 
 through the line, while electricity would require, in addition, 
 a generator, motor, transformers, extra foundations, etc. A 
 list of the three forms of power transmission made, according 
 to increasing machinery-cost factor, would be air, gas, and 
 electricity. 
 
 The cost of an electric-transmission line may be divided into 
 three parts: first, the metallic part of the circuit; second, in- 
 sulating the conductor; and, third, erecting or installing the Hne. 
 Although a detailed discussion of this subject is beyond the 
 proper scope of this book, it can be shown that, for a stated 
 power loss and a given distance, the weight of the metalHc 
 conductor required to transmit a definite amount of power is 
 inversely proportional to the square of the voltage employed. 
 On the other hand, the cost of insulation increases rapidly with 
 the potential, and the cost of erection, compHcated by steel 
 towers, etc., is greatly augmented at high voltages. Thus the 
 economical transmission of a given amount of power for a 
 stated distance is limited by the maximum voltage which may 
 be used without the increased cost of installation and erection 
 destroying the saving in the cost of copper. 
 
 Any attempt to go into the complicated processes necessary 
 to ascertain the most advantageous voltage for a long distance- 
 transmission line would be out of place here; but, for the short 
 
CHOICE OF POWER FOR TUNNEL WORK 71 
 
 distances and small amounts of power commonly employed in 
 tunneling operations, the following rule of thumb will suiHce 
 to give a close approximation to the most carefully made calcula- 
 tions. Multiply the distance to be traversed in miles by i,ooo 
 and select the voltage of the nearest commercial size of trans- 
 former to this figure. The standard voltages of transformers 
 now in use are 220, 440, 660, 1,100, 2,200, 6,600, 11,000, 
 22,000, 33,000, 66,000. For instance, if the distance from the 
 power station to the tunnel plant is five miles, select a voltage of 
 6,600; if the distance is ten miles, a voltage of 11,000. Where the 
 distance falls midway between transformer steps, use the voltage 
 which will find most ready sale for the apparatus when the work 
 is completed. 
 
 Since there are certain difficulties in the construction of 
 direct-current generators for voltages higher than 600, alternat- 
 ing current is generally employed for transmission fines. This 
 form also possesses a very important additional advantage in 
 the ease with which it may be changed from low to high potential, 
 and vice versa. When high tension is employed in transmission 
 of electrical power, the voltage at the generating station is 
 usually comparatively low, and is "stepped up" by transformers 
 to the desired potential for the fine and is reduced again by 
 transformers at the timnel plant. 
 
 The following figures, which show the installation cost of an 
 electric-transmission fine for different voltages and distances, 
 assuming approximately 10 per cent drop in the fine, are based 
 upon data kindly furnished by the General Electric Co.* 
 
 I. 200 H.P. — I mile — 440 v., direct current. 
 
 Poles, cross-arms, insulators, and fittings (poles spaced 
 
 100 feet) $375 
 
 33,000 lbs. copper cable, 500,000 C. M. (four conductors 
 
 required), at i8J4 cents lb 6,025 
 
 Cost of erection 300 
 
 Total $6,700 
 
 * Freight, right of way, surveying, and engineering are not included in 
 these data. 
 
72 MODERN TUNNELING 
 
 2. 200 H.P. — I mile — ^440 v., 3-phase, 60-cycle, alternating 
 
 current. 
 Poles, cross-arms, insulators, and fittings (poles spaced 
 
 100 feet) $415 
 
 34,000 lbs. copper cable, 350,000 CM. (six conductors 
 
 required) at 17^^ cents 6,035 
 
 Cost of erection 375 
 
 Total. 
 
 825 
 
 3. 200 H.P. — I mile — 1,100 v., 3-phase, 60-cycle, alternating 
 
 current. 
 Poles, cross-arms, insulators, and fittings (poles spaced 
 
 125 feet) 
 
 5,100 lbs. copper cable, B. & S. No. o (three conductors 
 
 required) at 17% cents 905 
 
 Cost of erection 265 
 
 Six transformers, 1,100: 440 volts, with switches, etc., 
 
 .erected 2,900 
 
 Total $4,455 
 
 4. 200 H.P. — 5 miles — 1,100 v., 3-phase, 60-cycle, alternating 
 
 current. 
 Poles, cross-arms, insulators, and fittings (poles spaced 
 
 125 feet) $1,870 
 
 122,000 lbs. copper wire, B. &S. No. 000 (nine conductors 
 
 required) at 17^ cents 21,650 
 
 Cost of erection 1^580 
 
 Six transformers, 1,100: 440 v., with switches, etc., erected 2,900 
 
 Total $28,000 
 
 5. 200 H.P. — 5 miles — 6,600 v., 3-phase, 60-cycle, alternating 
 
 current. 
 Poles, cross-arms, insulators, and fittings (poles spaced 
 
 125 feet) $1,870 
 
 6,500 lbs. copper wire, B. & S. No. 6 (three conductors 
 
 required) at 17^ cents 1,150 
 
 Cost of erection , 1,080 
 
 Six transformers, 6,600: 440 v., with switches, etc., erected 3,700 
 
 Total $7,800 
 
CHOICE OF POWER FOR TUNNEL WORK 73 
 
 6. 200 H.P. — 25 miles — 6,600 v., 3-phase, 60 cycle, alter- 
 
 nating current. 
 Poles, cross arms, insulators, and fittings (poles spaced 
 
 125 feet) $9,350 
 
 103,000 lbs. copper wire, B. & S. No. i (three conductors 
 
 required) at 17^ cents 18,300 
 
 Cost of erection 5jI5o 
 
 Six transformers, 6,600: 440 v., with switches, etc., erected 3,700 
 
 Total $36,500 
 
 7. 200 H.P. — 25 miles — 22,000 v., 3-phase, 60 cycle, alter- 
 
 nating current. 
 Poles, cross arms, insulators, and fittings (poles spaced 
 
 125 feet) $9,900 
 
 33,000 lbs. copper wire, B. & S. No. 6 (three conductors 
 
 required) at 17^ cents 5, 860 
 
 Cost of erection 5,190 
 
 Six transformers, 22,000: 440 v., with switches, etc., erected 5,200 
 
 Total $26,150 
 
 The Pneumo-Electric Machine Co.* have estimated that if 
 compressed air were used to transmit 200 horse-power one mile, 
 allowing lo per cent, loss at So pounds pressure, an 8-inch pipe 
 would be required which, at $1.78 per foot, would cost $8,400. 
 Calculations show that in order to transmit the same amount of 
 power in the form of producer-gas containing 120 B. t. u. per 
 cubic foot, the required pipe would need to be only 4 inches in 
 diameter, costing, at 70 cents per foot, approximately $3,700. 
 To both these values should be added the expense of laying the 
 Hne, but this figure would be relatively small compared to the 
 cost of the pipe. 
 
 Where the power is ultimately required for use in air drills 
 and is to be transmitted only for short distances, compressed 
 air is the cheapest of the three methods as regards installation 
 cost, the higher machinery factor required by the other systems 
 more than balancing the expensive air pipe-line. The field for 
 producer-gas transmission (with its machinery factor sHghtly 
 
 * Mining and Scientific Press, May 14, 1910, p. 700. 
 
74 MODERN TUNNELING 
 
 greater than air yet less than electricity, and its line factor just 
 the reverse) lies in the medium distances — beyond the economical 
 range for air, but still too short to warrant the cost of the extra 
 electrical machinery. For long distances, on the other hand, 
 electric transmission at high tension is, of course, preeminent. 
 
 Labor. — Tunnel power plants are generally not large enough 
 to occupy the entire time of even one operator, hence it is impos- 
 sible to prevent their being over-manned. The amount of labor 
 required does not as a rule, therefore, seriously affect the choice 
 of power. At a tunnel plant using water-wheels, hydraulic air 
 compressors, or electric motors as prime movers, one man per 
 shift is sufHcient. Even then, as was the case at the Laramie- 
 Poudre tunnel, it is not unusual to make these 12-hour shifts, 
 thus requiring but two men per day; or, as at the Carter 
 tunnel, for a portion of his time the engineer is employed at other 
 work. If the results obtained from practice in other lines be 
 accepted, a producer-gas plant would require no more exacting 
 attention, it being not unusual for one man per shift to operate 
 plants which develop as high as 750 or 1,000 horse-power. A 
 similar steam plant, on the other hand, would require at least 
 two firemen in addition to the engineer. In larger steam installa- 
 tions the amount of labor required is naturally not so great in. 
 proportion to the horse-power produced. For example, at the 
 Rondout Siphon 8 men per 8-hour shift were able to operate 
 a steam plant rated at 4,000 horse-power and containing 10 air 
 compressors of 2,400 cubic feet capacity each. 
 
 Fuel Consumption. — If the charge for delivering it be in- 
 cluded in the price, at most tunnel plants the cost of fuel is high, 
 hence the amount of it required is of great importance. Steam 
 plants require much more coal than gas plants of the same size; 
 for although in large installations, with every means for effecting 
 thermal economies, steam plants may be operated with as httle as 
 two pounds of high-grade fuel per brake horse-power hour, in 
 small plants such as are used in tunnel work a fuel consumption 
 as low as three pounds would be exceptional, and four or five 
 pounds is more likely to be required. With producer-gas, on the 
 other hand, it has been repeatedly demonstrated that internal 
 
CHOICE OF POWER FOR TUNNEL WORK 75 
 
 combustion engines can be operated on less than one pound of coal 
 per brake horse-power hour, and at the best plants this figure 
 runs as low as three-fourths of a pound. The consumption at the 
 Woolwich tunnel plant during a test was .727 pound of Polmaise 
 Scotch anthracite per brake horse-power hour. The small inter- 
 nal combustion engine has also the additional noteworthy char- 
 acteristic of being decidedly efficient in small sizes. The gas 
 engine of 50-60 brake horse-power has but a very little greater 
 fuel consumption per horse-power than the large engines of 500 
 or 1,000 brake horse-power. The adoption of a producer-gas 
 plant also makes possible the utilization of the fine sizes of an- 
 thracite coal such as Nos. 1,2, and 3 buckwheat, which were for- 
 merly considered waste, but which are now being screened 
 and saved and may be procured at much less cost than the coal 
 used in most steam boilers. 
 
 Thermal Efficiency. — The comparatively high fuel con- 
 sumption of the steam-engine is due to its low thermal efficiency. 
 Although large and economically operated steam plants may real- 
 ize perhaps as high as 12 to 15 per cent, of the theoretical energy 
 contained in the coal, 5 per cent, is much nearer the value gener- 
 ally obtained in ordinary tunnel work. The following table shows 
 the distribution of the average heat losses for one year at a well- 
 conducted steam plant where the thermal efficiency at the fly- 
 wheel was 10 per cent. : 
 
 LOSS OF THEORETICAL HEAT ENERGY AT A 
 STEAM PLANT 
 
 Losses due to imperfect combustion, heat absorbed in 
 ashes, moisture, etc., heat in flue gases, radiation, etc. 25% 
 
 Loss due to latent heat in exhaust steam 60 
 
 Loss in steam pipes and auxiliaries 3 
 
 Loss due to friction in steam-engines 2 
 
 90% 
 
 The producer-gas engine, on the other hand, operates with a 
 much higher thermal efficiency, 20 to 30 per cent, being not un- 
 usual in actual practice. Recent exhaustive shop tests of a 
 number of first-class foreign-built producer-gas engines, ranging 
 
76 MODERN TUNNELING 
 
 in power from 70 to 120 horse-power, gave thermal efficiencies 
 at full load of from 31.3 per cent, to 34.9 per cent., and a coal 
 consumption of from .72 to .623 pounds per brake horse-power 
 hour. The following table, introduced for comparison, shows the 
 distribution of losses in a producer-gas plant operating with 
 similar economy to the steam plant above: 
 
 THERMAL LOSSES IN PRODUCER-GAS PLANT 
 
 Loss in gas-producer 15% 
 
 Loss in water jacket 21 
 
 Loss from radiation and friction 4 
 
 Loss in exhaust gases 35 
 
 75% 
 
 Purchase of Current. — If the Hne of an estabHshed electric 
 power company runs near enough to the tunnel plant, power is 
 often purchased in preference to generating it at the tunnel. In 
 such cases the price of current usually ranges from i^ to 2 
 cents per kilowatt hour. On the Los Angeles aqueduct the power 
 used at all the tunnel plants is obtained from a private trans- 
 mission Hne operated by a separate department of the aqueduct 
 organization, and a flat rate of 1.7 cents per kilowatt hour for 
 power is charged against each tunnel, which it is estimated is 
 sufficient to operate the system and eventually pay for its instal- 
 lation. At one of the tunnels in Colorado, a flat rate of $2.50 
 per horse-power month is charged, to which is added 1.3 cents 
 per kilowatt hour used. On a 24-hour day basis this is equiv- 
 alent to ij^ cents per kilowatt hour. At another tunnel in Colo- 
 rado, 2 cents per kilowatt hour is the price of current. At a 
 third, the power for the compressor costs $5.50 per horse-power 
 month, which is equivalent to i cent per kilowatt hour on a 
 24-hour day basis, but at the same tunnel 2 cents per kilowatt 
 hour is charged for the current used in the motor generator set 
 which operates the trolley system, making the average cost for 
 the total power used approximately iK cents. At one tunnel 
 plant using a very large amount of power, the current is said 
 to have cost but ]/?, cents per kilowatt hour, an exceptionally 
 
 I 
 
CHOICE OF POWER FOR TUNNEL WORK 77 
 
 low figure, but in this case other considerations were involved 
 which really made the cost of the electricity greater than 
 this. 
 
 The following schedule is used by a number of western hydro- 
 electric companies who claim that this method of making a charge 
 is "fair and rational." 
 
 Fixed Charge per Month per Horse- Power of 
 Maximum Demand 
 
 Energy Charge 
 
 For the first loo Horse-Power. . $3.25 
 
 For the next 400 Horse-Power. . 2.25 
 
 For the next 500 Horse-Power. . 1.75 
 
 For all additional Horse-Power . i .00 
 
 Add for all energy used as 
 shown by meter thirteen 
 mills per kilowatt hour for 
 the first 40,000 kilowatt 
 hours used each month, and 
 five mills per kilowatt hour 
 for all additional energy. 
 
 The maximum demand shall be determined by the company's 
 meters, disregarding starting peaks and those due to short 
 circuits or accidents to user's apparatus. 
 
 Interest and Depreciation. — The cost for interest per unit 
 of power is dependent upon the amount of capital invested, but 
 that for depreciation is somewhat more complicated. In the 
 case of water-power, a dam or a ditch would have but very little 
 salvage value after the completion of the tunnel; something 
 further might be realized from a pipe-line or flume and still more 
 from the machinery in the power-house, the total loss of capital 
 invested being the sum of these separate items. Hence the 
 charge for depreciation would depend upon the relation of the 
 different factors to the total cost of installation. A similar 
 analysis may be made for other means of producing power. Both 
 interest and depreciation charges are dependent also upon the 
 hourly use of the plant per day, it being evident that if the plant 
 were used 24 hours instead of 12 the same total cost for interest 
 and practically the same total loss by depreciation would be dis- 
 tributed over double the number of horse-power hours, and 
 hence be proportionally less. 
 
78 MODERN TUNNELING 
 
 CONCLUSIONS 
 
 In choosing the power to be used for tunnel plants, a water- 
 fall or rapid, if either is available, should be given primary con- 
 sideration. The chief arguments in favor of this source of power 
 are as follows: no fuel is required; the cost for attendance and 
 repairs is a minimum; it is comparatively reliable, hence 
 obviating losses due to interruptions of service. The one factor 
 which might prohibit its choice is the possibility of a high cost 
 of installation, with resulting large charge for interest and depre- 
 ciation per unit of power. This consideration, dependent entirely 
 upon local conditions, usually determines the adoption or rejec- 
 tion of a possible water-power plant. Again, where water-power 
 is not obtainable directly at the tunnel plant, if it can be secured 
 from a waterfall in the neighborhood, the essential factors re- 
 main the same with the exception that a means of transmitting 
 the power, such as air or electricity, must be chosen, and the cost 
 of the transmission system be included in the cost of installation. 
 Another possible means of obtaining the advantages of water- 
 power is to be found in the purchase of current from an estab- 
 lished hydro-electric company. Such a concern is in a position 
 to utilize a waterfall, too distant to warrant its development for 
 a single tunnel project, and by distributing a large amount of 
 powder among many permanent customers is enabled . to sell it I 
 
 very cheaply. In such case, to the price of the power should be 
 added the cost of attendance at the tunnel plant and the interest 
 and depreciation charges on the necessary equipment. Allow- 
 ance must be made for interruptions to service in long-distance 
 electrical transmission which are neither unusual nor avoidable. 
 
 The choice of machinery for utilizing water-power is also 
 largely governed by local conditions. Since high heads, for which 
 impulse-wheels are especially adapted, are generally to be found 
 where water-power is available for tunnel work, this type of 
 machine is properly chosen in most instances. Turbine wheels 
 may be used where the water is clear or can be settled in a 
 reservoir, but such conditions are not usually to be found at 
 tunnel power plants. The hydraulic compressor, although prac- 
 
CHOICE OF POWER FOR TUNNEL WORK 79 
 
 tically automatic and entailing but a small operating expense, 
 is so costly to install that it is scarcely to be considered except 
 for plants much larger than those usually designed for tunnels. 
 
 According to usual practice, a steam plant would be installed 
 if water-power were not available and electricity were not 
 purchasable. This is difficult to understand unless it be attrib- 
 uted to the supposed unreHability of the gas-producer. The 
 usual steam plant for tunnel purposes is, as has been shown, 
 very inefficient in its utilization of the energy of coal and has 
 a fuel consumption rarely less than 4 or 5 pounds per horse- 
 power hour. As regards cost of installation, the balance is 
 slightly in favor of steam, but not sufficiently so to overcome 
 the disadvantage of higher operating cost. 
 
 The producer-gas plant, on the other hand, is several times 
 more efficient in its utilization of heat energy, making possible 
 the production of a brake horse-power per hour in some instances 
 with as little as one pound of coal. With this plant it is also pos- 
 sible to utilize cheaper grades of fuel. The manufacturers of air 
 compressors have recently adapted their machines for use with 
 internal-combustion engines. It would seem, therefore, if a 
 plant using fuel were necessary, that the installation of a 
 producer-gas plant under most conditions were more desirable 
 than a steam plant. 
 
 As a means of transmitting power for any great distance 
 the balance is preponderantly in favor of electric transmission 
 at high tension. In tunnel work and over comparatively short 
 distances, compressed air is able to compete with it because 
 the air drills require this form of power for their operation. 
 When it is necessary to obtain power from coal there seems to 
 be a field for producer-gas transmission in the medium distances, 
 where the cost of the Hne and the power losses in transmission 
 prohibit the use of air, but where the cost of the extra electrical 
 machinery is still not warranted by the saving in cost of line. 
 
CHAPTER V 
 AIR COMPRESSORS 
 
 Although an air compressor is the machine invariably 
 chosen at tunnel plants to convert the power derived from 
 steam, water, electricity, or fuel gas into a form suitable for use in 
 pneumatic rock drills, many factors enter into the problem of its 
 selection. After the question of motive power and capacity, the 
 type of the compressor is, perhaps, the next thing to be consid- 
 ered. The methods of regulation under varying load likewise 
 deserve attention. And, finally, the devices and accessories for 
 preventing or neutralizing the effects of heat produced during 
 compression and for removing moisture from the air bear directly 
 upon our problem. 
 
 The most familiar types of air compressors consist essentially 
 of a cylinder in which air is subjected to pressure by a moving 
 piston. Automatic means are provided to insure the admittance 
 of free air and its delivery after compression, and the momentum 
 of a fly-wheel is required to equalize the irregular demands of 
 the piston for power. When steam or internal combustion 
 engines are the prime movers they are usually, though not neces- 
 sarily, incorporated with the compressor, the power and air 
 pistons being connected by a common piston rod or engine 
 shaft. Where water or electricity is employed, the power is 
 usually developed in separate motors and transmitted to the air 
 compressor by a belt, the fly-wheel of the compressor in this 
 case serving also as a pulley; but there has arisen lately a grow- 
 ing demand for the ''direct-connected" electrically driven 
 machine in which the electric motor forms an integral part of 
 the compressor, the armature serving as a fly-wheel. Such 
 machines are now supplied by all the leading manufacturers. 
 ''Direct-connected" water-power driven air compressors are 
 also obtainable in which the water-wheel carrying the buckets or 
 vanes performs the additional function of fly-wheel for the com- 
 
 80 
 
AIR COMPRESSORS 81 
 
 pressor. Air compressors of an entirely different type, operating 
 on the principle of the reverse turbine, have recently been placed 
 on the market. They are especially adapted to take advantage 
 of the high rotative speed of electric motors and steam turbines. 
 Although the Taylor hydraulic system is, strictly speaking, an 
 air compressor, it has been described somewhat in detail as a 
 means of utilizing water-power; since its use is ordinarily con- 
 fined to units too large for tunnel work, it will not be discussed 
 further. 
 
 POWER REQUIRED 
 
 Although the kind of motive power is generally predetermined, 
 in designing a given plant, by local conditions, the amount of 
 power required for this purpose is worthy of brief discussion. 
 E. A. Rix is authority for the statement* that, in compressing 
 air from atmospheric pressure to 90 or 95 pounds,! 20 brake horse- 
 power must be deKvered at the fly-wheel shaft of a reciprocating 
 compressor for every 100 cubic feet per minute of piston dis- 
 placement. This figure is deduced as the average result of a 
 number of tests of air-compressor plants, comparing the capa- 
 bilities of almost every kind of compressor with the actual 
 power required to operate them. He also states that the figures 
 given in trade catalogues for the amount of power required in 
 compressing air are usually somev/hat lower than this value, but 
 it must be explained that such figures are theoretical and do not 
 take into consideration the mechanical or volumetric efficiencies 
 of the compressor. The following tables are computed from the 
 catalogues of two leading manufacturers for a popular type of 
 compressor in each case and show the rated brake horse-power 
 per 100 cubic feet cylinder displacement, where the final gauge 
 pressure is 100 pounds. 
 
 * Address before the Mining Assoc, Univ. of Calif., February 19th, re- 
 printed Compressed Air Magazine, June, 1906, p. 4894. 
 
 t Throughout this book when air pressure is mentioned the figures given 
 will be those above atmosphere, i.e., gauge pressure. In many books the 
 pressures given are absolute, ix., the pressure above vacuum, while in European 
 works on the subject pressures are generally expressed in terms of atmospheres, 
 which in this country would be liable to create considerable confusion. 
 
82 
 
 MODERN TUNNELING 
 
 RELATION BETWEEN REQUIRED BRAKE HORSE-POWER AND 
 CAPACITY 
 
 Compressor A 
 
 Compressor B 
 
 
 Brake Horse-Power 
 
 
 Brake Horse-Power 
 
 
 Required for Each 
 
 
 Required for Each 
 
 Capacity Cu. Ft. 
 
 100 Cu. Ft. Dis- 
 
 Capacity Cu. Ft. 
 
 100 Cu. Ft. Dis- 
 
 per Minute 
 
 placement Com- 
 
 per Minute 
 
 placement Com- 
 
 
 pressing to 100 lbs. 
 
 
 pressmg to 100 lbs. 
 
 144 
 
 18.7 
 
 248 
 
 19-3 
 
 247 
 
 18.6 
 
 338 
 
 19 
 
 2 
 
 372 
 
 18.4 
 
 537 
 
 18 
 
 I 
 
 534 
 
 18.3 
 
 680 
 
 18 
 
 I 
 
 704 
 
 18. 1 
 
 873 
 
 18 
 
 
 
 1051 
 
 18.0 
 
 1056 
 
 18 
 
 
 
 1312 
 
 17.8 
 
 1188 
 
 18 
 
 
 
 1692 
 
 17.7 
 
 1414 
 
 17 
 
 9 
 
 2381 
 
 17.7 
 
 1845 
 
 17 
 
 9 
 
 It will be observed that these tables bear out the statement 
 made by Mr. Rix, and that even in spite of the increased final 
 pressure, the values are somewhat less than the one he proposes. 
 They also show that in machines of large capacity proportion- 
 ally less power is required. 
 
 The following table, based upon published figures, shows 
 the amount of power required or provided per loo cubic feet 
 of free air actually compressed at several turbo-compressor 
 installations : 
 
 POWER CONSUMPTION OF TURBO-COMPRESSORS 
 
 Pressure 
 
 Capacity in Cu. Ft. Free 
 Air per Minute 
 
 Rated H.P. of Motor or 
 Engine per 100 Cu. Ft. of 
 Free Air When Com- 
 pressing to Stated 
 Pressure 
 
 Actual H.P. Required in 
 
 Compressing 100 Cu. Ft. 
 
 of Free Air per Minute to 
 
 Stated Pressure 
 
 90 
 118 
 135 
 170 
 
 4,600 
 21,250 
 20,000 
 22,000 
 
 21.8 
 18.8 
 
 l8!2 
 
 17. 
 18.5 
 
 CAPACITY 
 
 The capacity of compressors is rated in free air,* and in 
 reciprocating machines is equally based upon speed and piston 
 displacement — that is to say, the number of cubic feet of cyl- 
 inder space swept by the piston each minute at the given speed. 
 
 *Free air is air at 14.7 lbs. pressure (atmospheric), and at a temperature 
 of 60° F. 
 
 i 
 
AIR COMPRESSORS 
 
 83 
 
 This is not, however, the actual capacity, because there are 
 unavoidable losses in volume due to clearance, piston speed, 
 leakage, and expansion, the sum of which may amount to as 
 much as 30 per cent, of the rated capacity in a single-stage 
 compressor at 100 pounds pressure. The capacity of turbo- 
 compressors is based on the amount of free air drawn into the 
 intake per minute. Although some of the more carefully designed 
 reciprocating compressors may give a volumetric efficiency as 
 high as 90 per cent., for compressors such as are customarily 
 employed in power plants for tunnels 80 per cent, is more likely 
 to be nearer the figure. While the tables shown in manufacturers^ 
 catalogues of air drills are in the main fairly accurate for new 
 drills, the air consumption is often greatly augmented as the 
 parts become worn. Provision must be made also for leakage in 
 the pipe line and for the air required by drill sharpeners, black- 
 smith forges, and an extra small drill which is sometimes used for 
 blocking and trimming. It is therefore most desirable to have the 
 air compressors, as based upon catalogue rating, considerably 
 oversized, and in tunnel practice this usually ranges from 100 to 
 150 per cent. The following table shows a comparison between 
 the rated compressor capacity and the catalogue air consump- 
 tion for the drills employed in the heading at several tunnels : 
 
 RELATION BETWEEN COMPRESSOR CAPACITY AND AIR CON- 
 SUMPTION OF DRILLS 
 
 Carter 
 
 Laramie-Poudre . 
 Elizabeth Lake . , 
 
 Lucania , 
 
 Marshall-Russell 
 
 Mission , 
 
 Rawley , 
 
 Snake Creek . . . . 
 Strawberry 
 
 Compressor Cata- 
 logue Values 
 
 Speed 
 r.p.m. 
 
 150 
 165 
 160 
 130 
 175 
 190 
 
 175 
 165 
 175 
 
 Capacity 
 Cu. Ft. 
 per Min. 
 
 602 
 736 
 
 544 
 487 
 247 
 427 
 680 
 427 
 
 Heading 
 
 Air Consumption 
 
 from Catalogue 
 
 Cu. Ft. per Minute 
 
 230 at 9,000 elev. 
 
 250 ' 
 
 ' 8,000 " 
 
 185 ' 
 
 ' 3,000 " 
 
 250 ' 
 
 ' 8,000 " 
 
 200 ' 
 
 ' 8,000 " 
 
 100 ' 
 
 ' 1,200 " 
 
 190 ' 
 
 ' 10,000 " 
 
 300 ' 
 
 ' 6,000 " 
 
 300 
 
 ' 7,000 " 
 
 Oversize 
 of Com- 
 pressor* 
 
 280% 
 
 140 
 
 300 
 
 120 
 
 140 
 
 120 
 125 
 40 
 
 ^ Not including drill sharpeners, forges, or leakage in pipe lines. 
 
84 MODERN TUNNELING 
 
 The decrease in effective capacity of the compressor caused 
 by leakage in pipe lines is in many cases not fully realized, and 
 steps are not taken either to determine the amoimt of this 
 waste or to prevent it. Where the compressed-air lines are con- 
 structed with great care and covered so as to protect them from 
 accident or from extremes of temperature, the loss by leakage 
 may be slight or almost negligible; but where they are not well 
 built or where they remain uncovered, the lines on the surface 
 are exposed to injury from numerous causes — not the least of 
 which being diurnal and seasonal variation in temperature — 
 and those imderground are apt to be struck by falHng rock, 
 derailed cars, etc. In such cases the leakage is likely to be a 
 very considerable item, and the greatest care should be taken to 
 test the lines at short intervals to ascertain the amount of loss 
 in order that whatever is necessary may be done to stop it. 
 Where reciprocating compressors are used, driven either by steam- 
 or water-power, it is an easy matter to ascertain the amount of 
 leakage by simply closing all of the outlet pipes from the Hne 
 and noting the number of strokes per minute necessary to main- 
 tain the desired pressure; but where turbo-compressors are used, 
 unless a very careful table has been compiled showing the output 
 at different speeds and pressures, the leakage can best be ascer- . 
 tained by stopping the compressor when the receiver and Hnes 
 are filled, allowing the pressure to drop to 50 per cent., let us 
 say, then starting up the machine and noting the length of time 
 required to bring up the pressure to the original point. While 
 this does not give exact results, still it will furnish a useful, if 
 not exactly correct, index to the rate at which the compressed 
 air is escaping. Such a method of ascertaining the amount of 
 leakage is so simple that it would seem that it ought to be in 
 general use; but unfortunately it appears to be the habit of 
 workmen, especially of the "chain gang," to assume that all air 
 lines are much more free from leaks than they really are. A few 
 years ago at one of the large mines in the West which operated 
 a great number of drills, drill sharpeners, and pumps by com- 
 pressed air, it was found impossible to maintain the required 
 pressure, and bids for a new and expensive compressor were 
 
AIR COMPRESSORS 
 
 85 
 
 called for, when it occurred to the management to test the 
 pipe lines by the method above indicated, and it was discovered 
 that 1,100 horse-power were required to supply the loss by leak- 
 age. In this case the ''chain gang," instead of the machine 
 shop, ''got busy," and in a week the leakage was stopped and 
 the waste of air reduced to such a point that, instead of buying 
 another compressor, one of the largest machines was shut down. 
 
 TYPES 
 Reciprocating air compressors may be divided into two 
 general types: " straight-hne " (sometimes called "tandem") 
 and duplex. Either of them may be single stage where the air 
 reaches its final pressure in one cyhnder, or multi-stage where 
 only a portion of the compression takes place in the first cyhnder 
 and is' finally completed in a second, third, or even fourth 
 cylinder. 
 
 Straight-line 
 
 In the tandem compressor, if it be driven by steam or an 
 internal combustion engine, the power and air cylinders are 
 placed tandem-fashion along a common piston rod, and the 
 
 Fig. 12. Section through a single-stage straight-line compressor in which the 
 power cylinder is an internal combustion engine using gasoline fuel. 
 
 power is thus applied in a straight Hne. (See Figures 12 to 14.) 
 The fly-wheels, of which there are usually two, may be at either 
 
MODERN TUNNELING 
 
 end or between the cylinders and are connected to the piston 
 rod by a cross head and ordinary connecting rods. If it be driven 
 
 Fig. 15. Single-stage, power-driven compressor. 
 
 by electricity or water, practically the only change is the omission 
 of the power cylinder. (See Figures 15 and 16.) 
 
 Duplex 
 
 A duplex compressor consists of two tandem compressors 
 placed side by side, ha\ing a fly-wheel between them on a com- 
 
 FiG. 16. Belt-driven, straight-line, two-stage compressor. 
 
 mon shaft. The two sides are connected to the fly-wheel shaft by 
 cranks set at 90° so that when one side is encountering maximum 
 resistance, the other is working under the Hghtest load. There 
 are many different combinations possible with the duplex type. 
 The steam cyHnders * may or may not be compounded (see 
 
 * Internal combustion engines have not as yet been applied to this type 
 of compressor. 
 
Fig. 17. Duplex, simple-steam, two-stage air compressor. 
 
a 
 
AIR COMPRESSORS 
 
 91 
 
 Figures 17 and 18), and the air cylinders may be single, or 
 multi-stage. (See Figures 17 and 18.) Again the steam 
 cyUnders may be omitted and the power transmitted to the 
 
 Fig. 19. Duplex, belt-driven, two-stage air compressor. 
 
 machine by a belt (see Figure 19) or by a directly connected 
 motor. (See Figure 20.) 
 
 Turbo-compressors 
 
 The turbo-compressor operates upon the principle of a re- 
 versed turbine in which air, instead of water or steam, is the 
 fluid acted upon, and it consists essentially of a revolving im- 
 peller (not unhke that of some forms of centrifugal fans) sv.r- 
 rounded by a set of stationary discharge vanes supported in a 
 suitable casing (see Figure 21). It is the function of the discharge 
 vanes to recover the major portion of the energy which exists 
 in the air as velocity upon leaving the impeller, and which is 
 roughly almost one-half of the total energy supplied from the 
 driving machine, by converting this velocity into available press- 
 
AIR COMPRESSORS 
 
 ure. In the centrifugal fan, 
 there being no such vanes, this 
 energy is lost as heat produced 
 by eddies and friction, hence it 
 is not difficult to see the rea- 
 sons for the higher efficiency of 
 the new machine. Single-stage 
 turbo - compressors are em- 
 ployed chiefly in connection 
 with blast furnaces, cupolas, 
 etc., and could be used for 
 mine ventilation; but where a 
 high pressure is required, such 
 as that needed for the opera- 
 tion of rock drills and other 
 pneumatic machinery, a num- 
 ber of impeller units are 
 mounted on a common shaft 
 operating in series within a 
 common casing, the air upon 
 leaving the first set of dis- 
 charge vanes being conducted 
 to the intake of the second 
 impeller, and so on. Com- 
 pressors producing 170 pounds 
 pressure and having as many 
 as 29 stages have been con- 
 structed, but where so many 
 stages are employed the im- 
 pellers are usually mounted in 
 groups of from four to ten. 
 
 The manufacture of turbo- 
 compressors is just beginning 
 in this country, but they have 
 been in use for several years in 
 Germany, where their design 
 and manufacture have already 
 
94 MODERN TUNNELING 
 
 reached a high degree of perfection. The first large machine of 
 this kind was built in 1909 for the Reden mines near Swar- 
 brucken. It is driven by 1,000-horse-power, mixed pressure, 
 steam turbine at 4,200 revolutions per minute, and compresses 
 4,600 cubic feet of free air per minute to a gauge pressure of 90 
 pounds to the square inch. Quite recently, six motor-driven 
 compressors of this kind were built in Germany for the Rand 
 mines in South Africa. Each of these six machines is operated 
 by two 2,000-horse-power synchronous motors running at 3,000 
 revolutions per minute. The compressors have a rated capacity 
 of 21,250 cubic feet of free air per minute at 68° F. to 118 pounds 
 pressure per square inch. In a test, when compressing 23,750 
 cubic feet of free air per minute to 100 pounds pressure, the 
 energy of consumption per hundred cubic feet of free air was 17 
 horse-power and the highest isothermal efficiency obtained was 
 67.04 per cent. The first large compressor built in this country 
 went into service in May, 191 1, and has been in continuous oper- 
 ation ever since. This machine (figure 22) is driven by a steam 
 turbine at 4,700 revolutions per minute and has a capacity of 
 3,500 cubic feet of free air per minute delivered at a pressure of 
 105 pounds per square inch. 
 
 It is of course not possible, nor is it within the proper scope 
 of this volume, to describe all the numerous makes of air compres- 
 sors; for such material the reader is referred to the trade cat- 
 alogues issued by the various manufacturers, who will be glad 
 to supply this information, and whose experts are prepared to 
 render any assistance possible in the selection of a compressor. 
 
 COMPARISONS 
 
 The chief advantages of the straight-line compressor are 
 that it is strong, simple, compact, and easily installed. It is 
 usually self-contained, being mounted on a single bed plate, 
 and requires relatively inexpensive foundations. The frictional 
 losses in a good machine of this type are not large and, at or near 
 full load with moderate pressures, it may have a fairly good power 
 economy. These features make it advantageous for less access- 
 ible plants or those of a more or less temporary character. 
 
 I 
 
Fig. 22. Turbo-compressors. 
 
96 MODERN TUNNELING 
 
 A great advantage of the duplex type, on the other hand, is 
 the facility with which either steam or air cylinders may be 
 "compounded" without increasing materially the number of 
 parts. This makes it possible for the duplex type to take 
 advantage of the great saving in power resulting from com- 
 pound steam cylinders, as well as the economy resulting from 
 two-stage air compression. Practical experience with the two 
 types of machines fully confirms the theoretical investigations 
 of their comparative efficiency, and carefully conducted tests 
 extending over long periods of time have estabhshed the eco- 
 nomical superiority of the duplex type. In this type, also, if 
 properly designed, the mechanical losses through friction, etc., 
 are but Httle greater, if any, than in the straight-line compressor, 
 and it is much more easily regulated under varying loads. Most 
 manufacturers are now making duplex compressors with a sub- 
 stantial sub-base, giving the machines a strength and rigidity 
 comparable with the other type, reducing the expense of foun- 
 dations, thus meeting some of the conditions which have until 
 recently been so much in favor of the straight-line type. The 
 result is that, with perhaps a half-dozen exceptions, the air com- 
 pressors at tunnel plants examined were of the duplex type. 
 
 The entire absence of valves, reciprocating parts, and sliding 
 friction in turbo-compressors, together with their freedom from 
 vibration, their high capacity in proportion to weight and to 
 floor space occupied, and their abihty to take advantage of the 
 high rotative speeds of electric motors and steam turbines, are 
 certain to bring these new aspirants for engineering favor into 
 general use. Using live steam, condensing or non-condensing 
 turbine-engine turbo-compressor units are quite able to compete 
 successfully with the very highest grades of reciprocating-engine 
 compressor plants, and they can be operated successfully with 
 exhaust steam from engines, pumps, or other apparatus, which 
 forms one of the cheapest possible sources of power — because in 
 utilizing steam which would otherwise go to waste, practically 
 free fuel is obtained. Another advantage, and one that might 
 easily be overlooked, is the fact that it practically eliminates 
 the danger of explosions in air receivers and pipe lines. In piston 
 
AIR COMPRESSORS 97 
 
 compressors lubrication must be supplied to the inside of the 
 cylinder in order to protect it from the friction of the sliding 
 piston; there is, therefore, every opportunity for the oil (which 
 becomes finely divided in this process) to commingle with the 
 air as it is being compressed and to be carried with it into the 
 receiver. But with the turbo-compressor the only surfaces re- 
 quiring lubrication are those of the bearings to which the air 
 being compressed has no access. When an electric motor or water- 
 wheel is the source of power, the ease with which the turbo- 
 compressor may be connected to either of them, thereby avoid- 
 ing all loss due to speed reduction and friction, renders this a 
 most desirable combination. The turbo-compressor is readily 
 adapted to automatic control and may be regulated for the 
 delivery of a constant volume or constant pressure as required. 
 Its efficiency is maintained over a wide range of load within a 
 few per cent, of the maximum, and the efficiency does not decrease 
 with continued ser\dce. There is, therefore, every reason to 
 expect that turbo-compressors will come into general use in the 
 near future. 
 
 REGULATION 
 
 Steam Driven 
 
 Although, when steam driven, a change in load with any 
 type of machine results in a variation of speed, this works more 
 to the disadvantage of the straight-line compressor, especially 
 with high air and steam pressure, because this t}3)e will not run 
 satisfactorily at low speeds, the momentum of the fly-wheel 
 not being sufficient to carry it past dead centers. To avoid stop- 
 page, either the steam cut-off must be lengthened (in which case 
 there is a loss of steam as the machine speeds up under increasing 
 load) or there must be a fixed Hmit below which the steam is not 
 decreased, and when the demand for compressed air falls below 
 that supplied regularly by the machine the excess must be per- 
 mitted to escape through a safety valve. Both of these cases 
 entail loss of power. For this reason the straight-line compressor 
 cannot operate economically much below the Hmit of 40 per cent, 
 of full load. 
 
98 MODERN TUNNELING 
 
 In this matter of regulation the duplex, steam-driven machine 
 has an unquestioned advantage over the straight-line machine. 
 The quartered cranks, in addition to minimizing strains and 
 reducing extremes, enable one cyhnder to come to the help of the 
 other just at the time when that help is most beneficial, and, a 
 quarter of a revolution later, the favor is returned. There can 
 be no dead center, and the machine will run so slowly as hardly 
 to turn over if the compressed air in the receiver is not being 
 drawn upon, and will speed up rapidly as there is an increased 
 demand for air, doing it without any change in the cut-off. The 
 duplex machine, therefore, has the same steam economy over 
 the full range of load, without any loss of compressed air at the 
 safety valve. 
 
 With the turbo-compressor when steam-turbine driven, the 
 regulation is merely a matter of controlling the amount of steam 
 admitted to the turbine. 
 
 Water Driven 
 
 The regulation of compressors driven by impulse wheels may 
 be accompHshed by several methods, among which may be men- 
 tioned the deflecting nozzle, the needle nozzle, and the cut-off. 
 The deflecting nozzle is provided with a ball and socket joint 
 and is controlled by air receiver pressure in such a manner that 
 a portion of the stream of water may be shifted on or off the 
 buckets of the wheel, thus increasing or decreasing the amount 
 of power developed to correspond with varying loads. A steel 
 plate may be made to accompHsh the same effect by deflecting 
 the stream of water, the nozzle in this case remaining stationary. 
 The needle nozzle is merely a discharge valve in which a conical 
 needle is inserted or withdrawn from an orifice, thus diminishing 
 or increasing the amount of water passing through. The cut-off 
 also regulates the water quantity by a change in the discharge 
 area, produced by the shifting of a plate which fits tightly over 
 the nozzle tip. The deflecting devices are capable of controlling 
 rapid variations in power demand, but are, of course, wasteful of 
 water, while just the reverse is true of the other types. At tunnel 
 plants, however, water economy is rarely an essential consider- 
 
AIR COMPRESSORS 99 
 
 ation while variations in load are frequent and sudden; the de- 
 flecting devices are therefore most suitable. 
 
 Electrically Driven 
 
 The volume of air compressed in any reciprocating machine 
 varies with the number of strokes per minute made by the 
 piston; in the turbine compressor it is dependent upon the rota- 
 tive speed. In electrically driven reciprocating compressors, 
 whether directly connected or belted to a motor, the speed is 
 necessarily reasonably constant and cannot be varied to meet 
 fluctuating demands for air; and since economy obviously for- 
 bids the discharge of excess compressed air through a safety 
 valve, "unloaders" must be provided to overcome the difliculty. 
 
 Unloaders .—The more common method is to limit the amount 
 of air admitted to the machine. This type of unloader consists 
 of a valve in the free-air intake pipe controlled by the pressure 
 in the air receiver, which throttles the admission of air when the 
 load is light, and allows more of it to enter when the demand for 
 air increases. This device may be employed successfully with 
 turbo-compressors, but with reciprocating machines it never- 
 theless has its drawback, because when running with a partially 
 throttled inlet, the smaller amount of air drawn into the cylinder 
 is rarefied and on the return stroke of the piston is consequently 
 compressed through a greater range of pressure, giving rise to 
 higher temperatures than ordinary and they may reach unsafe 
 limits, especially where the terminal pressures are great. This 
 is not so important with turbo-compressors because the temper- 
 atures never become so high as they do in reciprocating machines. 
 
 On some piston compressors an unloader of almost an ex- 
 actly opposite type is employed and consists of a device for 
 holding the intake valves open whenever the air pressure reaches 
 a predetermined point. 
 
 In one type of unloader for reciprocating machines the excess 
 air is forced automatically into clearance tanks, the process 
 being controlled by a predetermined receiver air pressure. Fig- 
 ure 23 gives a diagrammatic representation of this device. Under 
 normal full load the controller is inoperative, but when working 
 
100 
 
 MODERN TUNNELING 
 
 at partial capacity a portion of the compressed air is forced 'into 
 the tanks instead of going through the discharge valve, thus 
 reducing the output of the compressor. On the return stroke 
 this air expands, returning its stored energy to the piston. There 
 are eight tanks in all, and four equal and successive unloading 
 stages are possible by throwing in respectively two, four, 
 six, or all of the tanks. The regulation is said to be unaccom- 
 panied by shock due to sudden variations in load, and heating 
 
 Fig. 23. Diagrammatic cut of clearance controller. 
 
 caused by the compression of rarefied air is avoided — in fact, 
 since there is a slight radiation from the clearance tanks, the air 
 is probably returned to the cylinder slightly cooler than when 
 it left. 
 
 Another method of unloading is by holding open the discharge 
 valves of the compressor, permitting compressed air instead of 
 free air to fill the cylinder as the piston retreats, and thus bal- 
 ancing the pressure on both sides of the piston. Although this 
 unloads the compressor completely, it has a very serious draw- 
 back. As the load is resumed the balance of pressure is dis- 
 turbed, one side of the piston being subjected to something less 
 
AIR COMPRESSORS 101 
 
 than atmospheric pressure, while the opposite side is exposed to 
 the full pressure of air in the receiver, the difference in pressure 
 being thrown on the piston instantly and maintained throughout 
 the entire stroke. As a result, serious strains are placed upon 
 the structure of the compressor which prohibit the use of this 
 unloader except in the smaller sizes. Still another type releases 
 the partially compressed air during its passage from the low- to 
 the high-pressure cylinders, but little can be said for this method 
 except that it is not quite so wasteful as releasing high-pressure 
 air. 
 
 HEAT 
 
 Heat Produced 
 
 Heat is produced during the compression of air and the rise 
 in temperature is largely dependent upon the difference between 
 the initial and final pressure. For instance, if air at 60° F. be 
 compressed in a single stroke from atmospheric pressure to 
 100 pounds gauge, the temperature attained would be 485° F., 
 assuming no loss by radiation during the process. On the other 
 hand, under the same conditions, if the final pressure were but 
 25 pounds gauge, the air would be heated only to 233° F., and if 
 it were then cooled again to 60° and further compressed from 
 25 pounds to 100 pounds gauge the final temperature would 
 approximately be 250° F. The effect of the increase in tempera- 
 ture is to cause the air to expand to a larger volume, and hence 
 more work is required to compress it. If the air could be used 
 at once to operate a motor, before any of the heat escapes through 
 radiation, etc., this work could be obtained again from the air; 
 but since in mining work the heat is almost without exception 
 entirely dissipated in the pipe Hne before the air reaches the 
 drills, the production of heat during compression entails a serious 
 loss of power. 
 
 Dangers of High Temperatures 
 
 Aside from the item of power waste, the temperature reached 
 during compression has an important bearing on the question of 
 
102 MODERN TUNNELING 
 
 explosions in air lines. It can readily be imagined that if the dis- 
 charge valves are not working properly and some of the highly 
 heated compressed air is allowed to re-enter the cyHnder with 
 the fresh intake air, compression may begin at a temperature 
 much higher than normal, in which case, even with two-stage 
 machines, the final temperature of the compressed air may be 
 gradually built up from 250° to 500°, 600°, or .even higher. It 
 is often sufficiently high to volatilize lubricating oil, the vapors 
 of which, mingling with the air, may be in proper amount to 
 form an explosive mixture. If the temperature then becomes 
 high enough to ignite this mixture, an explosion inevitably 
 results. There have been numerous instances where this has 
 actually occurred. 
 
 Removal oe Heat 
 
 The ideal way to prevent the evil effects of heat would be 
 to devise some means of removing it from the air as fast as 
 produced during compression. Such a course is unfortunately 
 impossible of attainment in practice, but various means have 
 been invented which partly accomplish the result. A familiar 
 one is to surround the cylinder with a jacket of cooHng water, 
 the piston also being sometimes cooled in this way. But when 
 one considers that air is a very poor conductor of heat and that 
 at the time when it is hottest it occupies but the minimum 
 volume in one end of the cylinder, and even then but for a short 
 space of time, it will readily be seen that this method cannot 
 be very effective. In some modern compressors the inlet 
 valves are placed in the piston and the discharge valves in the 
 ends of the cylinders instead of in the heads, thus permitting 
 the latter to be fully water-jacketed, a practice which is to be 
 most highly commended. As water-jacketing is the only means 
 used to cool the air during single-stage compression, it is not 
 surprising that such machines are not economical of power. 
 
 In two-stage compressors, however, a portion of the heat is 
 actually removed during compression. The air is only partially 
 compressed in the first cyHnder, perhaps to 25 pounds gauge, 
 and the heat produced is practically all removed during the 
 
AIR COMPRESSORS lOS 
 
 passage of the air through an intercooler in its way to the 
 second cylinder, where the final pressure, of perhaps loo pounds, 
 is attained. By removing the heat in the inter-cooler, the 
 temperature of the air is kept much lower than with single-stage 
 compression, hence there is less expansion of the air to be over- 
 come, resulting in a consequent saving of power. In a properly 
 designed two-stage machine compressing to loo pounds gauge, 
 this saving of power is approximately 13 per cent., and it increases 
 
 . with the higher terminal pressures. If the pressure is less than 
 80 pounds, the saving is hardly great enough to be a serious 
 consideration and single-stage machines are customarily em- 
 
 'ployed in such cases, but for pressures higher than 100 pounds 
 two-stage compression is imperative, because of the high temper- 
 atures that are otherwise produced. As shown by the following 
 table, the pressure ordinarily employed in tunnel plants ranges 
 from 80-120 pounds, averaging about 100 pounds. 
 
 Compressed Air Pressures at Different Tunnel Plants 
 
 Carter 112 Marshall-Russell no Roosevelt no 
 
 Central 120 Mission 100 Siwatch 80 
 
 Gold Links. .... 100 Moodna 95-100 Snake Creek. ... no 
 
 Gunnison 90 Newhouse no Stilwell 100 
 
 Laramie-Poudre 120 Nisqually 90-95 Strawberry 85 
 
 Mauch Chunk.. . 100 Rawley 100 Utah Metals. ... no 
 
 Los Angeles Raymond 90 Walkill. ....... no 
 
 Aqueduct 100 Rondout 100 Yak 90 
 
 Lucania 115 
 
 Because of the many stages required with turbo-compressors 
 when dehvering air for use in drilling, the difference between the 
 pressures of the air on entering and leaving any one stage is 
 extremely small compared with that of two-stage reciprocating 
 machines. Hence the resulting increase of temperature in any 
 one step is not great, and it is possible to remove the compara- 
 tively small amount of heat generated effectively by the use of 
 a suitably designed water-jacket. Some idea of the efficiency 
 obtainable with such a cooling system may be had from the 
 fact that the air delivered into the receiver at 105 pounds 
 
104 
 
 MODERN TUNNELING 
 
 pressure from the turbo-compressor illustrated in Figure 22, 
 page 95, has a temperature of only 120° F. 
 
 Intercooling 
 
 The efficiency of two-stage compression is largely dependent 
 upon the intercooler. It is an essential part of this type of 
 machine, and usually consists of a shell, generally cylindrical in 
 shape, containing a number of pipes, similar to those in a tubular 
 boiler, through which cold water is made to circulate. See 
 Figure 24. The heated air from the low-pressure cylinder enters 
 
 Water 
 outlet 
 pipe. 
 
 Connection for 
 high-pressure 
 air cylinder 
 
 Connection foe 
 low-pressure 
 air cylinder 
 
 Fig. 24. Typical Intercooler. 
 
 near one end, passes through the nest of tubes, its passage being 
 obstructed by baffle plates to insure the maximum contact 
 between air and cooHng surface, and is dehvered at much lower 
 temperature to the high-pressure cyHnder at the other end. 
 The success of the intercooler depends upon several considera- 
 tions. In order that the least dependence need be placed upon 
 the heat conductivity of the air itself, which is notably poor, the 
 intercooler must subdivide the air completely, and insure that 
 the maximum amount of it is thrown in contact with the cooling 
 surfaces. This is accomplished by properly spaced water- tubes 
 and baffle plates. At the same time the cross-section of the 
 cooler must not be too small, in which case the velocity of the 
 air past the cooling surface would be so great that sufficient 
 time would not be allowed for the water to absorb all the heat. 
 
AIR COMPRESSORS 105 
 
 It is very desirable also to have the water and air flow in opposite 
 directions in order that the final cooKng of the air may be effected 
 by the entering, and consequently the coldest, water. Theoreti- 
 cally, the cooling surface should be sufiicient to absorb all the 
 heat in the air passed over it, reducing the temperature to the 
 point at which the air entered the low-pressure cyHnder, but 
 due possibly to mechanical difficulties, even in good practice, 
 intercoolers usually fail to do this within five or ten degrees, 
 while even 30 or 40 degrees are not unusual. 
 
 Moisture 
 
 The intercooler assists also in removing water from the air. 
 Normal atmosphere always contains at least some water vapor, 
 but for any combination of relative volume and absolute temper- 
 ature, air is incapable of absorbing more than a certain amount 
 of water vapor. This maximum at 60° F, and 14.7 pounds 
 pressure is .0137 ounce, while under the same pressure and at 
 32° F., air can hold but .0046 ounce and at 0° F. but .0011 
 ounce. In the air compressor both of these factors of volume 
 and temperature are suddenly and violently disturbed. The 
 water vapor in the air would be released were it not for the fact 
 that as the volume is reduced (a process which would ordinarily 
 decrease the capacity of the air for moisture) the temperature 
 is greatly raised at the same time, increasing the water-carrying 
 capacity of the air; the increase in capacity for moisture, caused 
 by the high temperature, being greater than the decrease due 
 to reduced volume and no water is precipitated. But as the 
 air passes through the intercooler the temperature is lowered 
 greatly without a corresponding increase in volume, and the 
 air is forced to give up its water. It is precipitated in such a 
 finely divided state, however, that it requires some time to 
 settle; for that reason only a portion of it can be collected in the 
 intercooler and drawn off through drains provided for that 
 purpose, the remainder being swept along with the air to the 
 higher-pressure cylinder and revaporized by the temperature 
 there attained. 
 
106 MODERN TUNNELING 
 
 ACCESSORIES 
 
 Precoolers 
 
 CooKng the air before its admission into the air compressor 
 also assists in removing some water from it, and there are a 
 number of devices for this purpose. One precooler described 
 in the Engineering and Mining Journal * is a home-made affair 
 consisting simply of a number of odd pipes set between two 
 wooden boxes. The pipes are wrapped with cloth and water is 
 arranged to drip on them constantly, so that the air is cooled 
 by evaporation as it is drawn through them from one box to 
 the other on its way to the compressor intake. At a plant in 
 Johannesburg the air for the compressors is obtained through a 
 subway leading to the center of a building with air-tight roof 
 and floors, and with walls consisting of constantly wetted cocoa 
 matting. At another plant a similar structure was used in which 
 the sides and roof were covered with burlap both inside and out. 
 A cooler of this type also filters dust and grit which might seri- 
 ously injure the cylinder or piston of the compressor, and can- 
 not be too strongly recommended in dusty situations. Pre- 
 cooKng the air also increases the capacity of the compressor, 
 because the cooler air occupies less space than when it is heated, 
 hence a larger actual amount of air will be drawn into the 
 cylinder and compressed at each stroke. 
 
 After-cooling 
 
 The after-cooler, t although it is not generally employed in 
 tunnel plants, by cooling the air at once after it comes from the 
 high-pressure cylinder, also precipitates some of the water vapor, 
 but at the same time it reduces the volume of the air and practi- 
 cally eliminates the danger of explosion in the air Hne. Although 
 the air gives up its water vapor in the cooler because of the de- 
 
 * November 27, 1909, p. 1081. 
 
 t In design and principle the after-cooler is practically the same as an 
 intercooler, and it is usually placed between the compressor and the air 
 receiver. 
 
AIR COMPRESSORS 107 
 
 crease in temperature, it is usually in so finely divided a state 
 that all of it does not at once fall out, part being swept along with 
 the air and deposited both in the air receiver and in the pipe Hne. 
 There should, therefore, be provision for draining this water at 
 some low point. The amount of the reduction in volume is 
 somewhat speculative and probably not a serious consideration. 
 
 Air Receivers 
 
 The air receiver,* according to the popular notion, is supposed 
 to perform the functions of storing, cooling, and drying air, 
 together with equalizing irregularities in its production and use, 
 but it is more than probable that in actual practice it accom- 
 plishes these results, with the exception perhaps of the last one, 
 very inefi&ciently. When one takes into consideration the fact 
 that the receiver ordinarily installed in tunnel plants rarely has 
 a capacity greater than one minute's run of the compressor, it 
 will be seen that it cannot possibly furnish any great amount of 
 storage space. Then, too, since the air in the receiver is being 
 renewed each minute when the compressor is in operation the 
 velocity of the air through the receiver must be enough to pre- 
 vent any great amount of cooling. There will, of course, be some 
 radiation of heat from the air near the shell, but this is small 
 compared to the heat in the mass of the air in the center of the 
 receiver, so that the air leaves with a temperature but slightly 
 lowered, if at all, below that at which it entered. And further- 
 more, since there is practically no cooKng of the air, there can 
 be no great precipitation of water vapor. As a matter of fact 
 this is the case in practice, for, although most air receivers are 
 provided with a drain of some sort, only a ridiculously small 
 amount of water is ever drawn off. On the other hand, instead 
 of cooling, the air receivers have actually in some instances 
 become combustion chambers. Oil and grease in time collect on 
 the inside of the shell and may become ignited if the tempera- 
 ture of the air becomes high enough. Together with the pipe 
 
 * The air receiver consists simply of a cylindrical shell of steel provided with 
 inlet and outlet pipes and usually a safety valve. 
 
108 MODERN TUNNELING 
 
 line, which storage space may be considered as an auxiliary, the 
 receiver does assist greatly, however, in equalizing the pulsations 
 not only of the air delivered from the compressor but also of 
 that used by the drills, and in this way it reduces strain on the 
 structure of the compressor. By regulating the flow, it does not 
 permit the air to attain a high velocity in the pipes even irregu- 
 larly, and hence power is saved since the friction losses increase 
 greatly with the velocity. To secure the maximum benefit from 
 this factor, a second receiver is often installed as near as possible 
 to the place where the air is to be used. In this case the second 
 receiver assists materially in maintaining a steadier air pressure 
 at the drills. A tubular boiler, which it is often possible to buy 
 cheaply at second-hand, makes an excellent receiver and a very 
 efficient cooler. With a vertical tubular boiler it is only neces- 
 sary to remove the fire and ash doors to provide for ventilation, 
 while a horizontal tubular boiler should be placed on an incline 
 sufficiently steep to insure a rapid draft of outside air through 
 the flues. 
 
 Drains 
 
 Since practically the entire cooling of the air after leaving 
 the compressor takes place in the pipe line, it is here that most 
 of the water is precipitated and causes serious inconvenience in 
 several ways. During cold weather, through continued deposi- 
 tion and freezing, the pipe line may become closed altogether or 
 so restricted as to cause serious drop in pressure or loss of power. 
 Or the water getting into the exhaust from the drills not 
 uncommonly prevents their operation through freezing at the 
 low temperature of the expanded air. The obvious remedy is 
 to remove the water, which is done by draining the low places 
 in the line where the water collects. This can be accomplished 
 automatically by the use of any good float design steam trap, 
 but where the pipe is exposed to low temperatures the trap 
 should be placed in a small pit or otherwise protected to prevent 
 freezing. Where necessary, further provision for the elimination 
 of moisture from the compressed air and water from the pipes 
 
AIR COMPRESSORS 109 
 
 can be had by placing in the Hne any high-class standard steam 
 separator, fitted with an automatic trap as described above. 
 
 CONCLUSIONS 
 
 In conclusion, let us sum up briefly the factors which enter 
 into the problem of selecting an air compressor. The power 
 required for both reciprocating and turbine machines is approx- 
 imately 1 8 to 20 brake horse-power for every loo cubic feet of 
 free air compressed to loo pounds gauge. The values given in 
 trade catalogues for reciprocating compressors are generally a 
 little below this figure, but it is a safe one to use in estimates. 
 Such compressors ordinarily have a volumetric efficiency of 
 approximately 80 per cent., and since they are rated on the 
 basis of free air and since it is necessary to make allowance for 
 loss due to clearance, etc., provision for increased air con- 
 sumption above the catalogue rating for drills as they become 
 worn, and for that used in sharpening machines and forges, 
 must also be made with either reciprocating or turbine machines, 
 and it is advisable to select an air compressor considerably over- 
 size. In practice the amount of oversize, based upon drills 
 only, ordinarily ranges from 100 to 150 per cent. Of the two 
 types of reciprocating compressors the duplex is preferable to 
 the straight Hne (in spite of the latter's simphcity and easier 
 installation) beca,use of the former's more economical and 
 efficient use of power and the faciHty of its regulation, especially 
 w^hen steam driven and with high pressures. Since the air pressure 
 at tunnel plants is rarely below 80 pounds, and in three out of 
 every four it is 100 pounds or greater, two-stage compression 
 is desirable because of its economy of power, if not indeed 
 imperative because of the air temperatures that might other- 
 wise be attained. Although the manufacture of turbo-compres- 
 sors is just beginning in this country, they possess a number of 
 advantages, especially for use with steam turbines and other 
 rotary engines operating at high speeds, which will doubtless 
 lead to their more general use in the future. Their development 
 should therefore be closely watched. Steam-driven compressors 
 
no MODERN TUNNELING 
 
 are regulated by varying their speed; but since in some power- 
 driven machines the speed is necessarily constant, other means, 
 of which the throttle inlet and the clearance controllers are the 
 two most used, must be provided for that purpose. Heat is 
 produced during compression and by expanding the air causes 
 loss of power. Some of this loss is obviated in two-stage compres- 
 sion by removing the heat during its passage through an inter- 
 cooler between the cylinders. The numerous stages in the 
 turbine machine enable this heat to be removed effectively by 
 water-jacketing in this type of compressor. Another evil attrib- 
 utable to this heat is the danger from the explosion of volatilized 
 lubricating oils; but in the turbine machine this danger is elim- 
 inated because there are no sliding surfaces to require lubrica- 
 tion. Among the accessories which are designed to prevent or 
 neutralize the effects of heat in piston machines are the pre- 
 cooler, the intercooler, the after-cooler, and the air receiver. 
 The last mentioned also equalizes the pulsations of the air and 
 reduces friction losses. These devices assist, too, in freeing the 
 air from water, which often causes serious inconvenience. The 
 major portion of the water is deposited in the pipe line, however, 
 where provision must be made for its removal. 
 
CHAPTER VI 
 
 VENTILATION 
 MACHINERY 
 
 Either blowers or fans are employed ordinarily for ventilat- 
 ing tunnels and adits. In machines of the first type, a certain 
 amount of air is trapped every revolution between the impellers 
 and the enclosing casing, and has no means of escape (to omit 
 from consideration a small amount of leakage) except through 
 the exhaust pipe (see Figure 25). For this reason they are 
 
 Fig. 25. 
 
 Diagrammatic cross-sections illustrating the action of pressure 
 blowers. 
 
 often styled "pressure" blowers and "positive blast" machines. 
 Figure 26 shows one of these blowers in operation on the Los 
 Angeles aqueduct. 
 
 Where fans are employed in tunnel ventilation they are, 
 almost without exception, centrifugal — the familiar propeller 
 form similar to the ordinary desk fan being rarely used. In the 
 centrifugal fan the air enters near the center, traveling iii a 
 direction approximately parallel to the axis of the shaft, and is 
 forced by the centrifugal action of the rapidly revolving blades 
 toward their periphery, where it is collected and discharged. 
 There are many modifications of this design, with the intention 
 of preventing loss of efficiency through friction as the air strikes 
 
 111 
 
112 
 
 MODERN TUNNELING 
 
 the back plate and changes direction, or to prevent eddies, etc., 
 due to the greater density of the air at that point caused by its 
 momentum upon entering the fan. 
 
 Turbo-compressors in which, by the adoption of one or two 
 or even several stages, air can be delivered at any required 
 pressure, have been employed as blowers for blast-furnace and 
 foundry work at a number of places. The capacities of those 
 manufactured for this purpose thus far are too great for the 
 requirements of tunnel work, but their greater efhciency as 
 
 Fig. 26. Ventilating blower used on Los Angeles Aqueduct. 
 
 compared with centrifugal fans and the possibiKty of designing 
 them to secure any required pressure mil doubtless soon lead 
 to their being made in sizes suitable for tunnel work, where 
 they should have a large field. 
 
 At one tunnel a certain amount of vitiated air was removed 
 from the heading by the use of a jet of highly compressed air 
 which was directed into the ventilating pipe; but this method, 
 in addition to being expensive, is inadequate as well, and is, 
 therefore, not to be advised, except as a temporary expedient 
 and for short distances. On short levels and cross-cuts, how- 
 ever, or on larger work pending the installation of more expensive 
 and efncient machinery, jet blowers can often be used to good 
 
VENTILATION 
 
 113^ 
 
 advantage. They can be operated by either compressed air 
 or water under pressure, and, while far from being as efficient 
 as the mechanical types of ventilating machinery, will in many 
 cases perform an extremely useful function. Jet blowers can 
 frequently be used with good results to move large volumes 
 of air for short distances against low frictional resistances, and 
 their extreme economy in jSirst cost makes them an excellent 
 accessory in preliminary work. 
 
 DIRECTION OF CURRENT 
 
 The fan or blower ordinarily installed for tunnel work may 
 be made, by a proper adjustment of the .^ventilating pipe, to 
 exhaust the air from or deHver it to the heading. One of the 
 chief advantages of the first method is that the dangerous gases 
 and smoke produced in blasting are promptly removed from 
 
 Fig. 27. 
 
 Arrangement of gates and pipe for changing direction of 
 ventilating current. 
 
 the tunnel, and it is therefore unnecessary for the workmen 
 to pass through a thick bank of smoke which would otherwise 
 travel very slowly to the portal. On the other hand, when fresh 
 air is blown in, it passes very much faster through the pipe and is 
 cooler and fresher than if it had worked it-s way slowly in through 
 
114 
 
 MODERN TUNNELING 
 
 the tunnel or adit and become heated from contact with the 
 walls and contaminated by odors from the track; the men, 
 therefore, feel more comfortable and are able to do better work 
 when this method is employed. The advantages of both methods, 
 however, may be readily obtained by an arrangement of pipes 
 similar in principle to the one shown in Figure 27, which permits 
 the air to be exhausted for a few minutes after blasting, by 
 opening gates a and h and closing c and d (assuming the 
 current through the fan or blower to be in the direction of the 
 arrow), while at other times, by reversing this arrangement, air 
 may be forced into the heading. The following table shows the 
 direction of the air current at various tunnels visited, from which 
 it may be seen that, almost without exception, it is customary to 
 exhaust the smoke, after blasting at least, although at many places 
 the ventilating current is reversed at other times. This arrange- 
 ment is reported as giving excellent results, and its use is strongly 
 recommended. 
 
 DIRECTION OF AIR CURRENT AT VARIOUS TUNNELS 
 
 Tunnel 
 
 I 
 
 Ordinarily 
 
 After Shooting 
 
 Carter 
 
 Central 
 
 Gold Links 
 
 Gunnison, East Portal 
 Gunnison, West Portal 
 Laramie-Poudre , . . . . 
 
 Lausanne 
 
 Los Angeles Aqueduct, 
 
 Elizabeth Lake 
 
 Little Lake 
 
 Grapevine 
 
 Lucania 
 
 Marshall-Russel 
 
 Mission 
 
 Newhouse 
 
 Nisqually 
 
 Rawley 
 
 Raymond 
 
 Rondout 
 
 Roosevelt 
 
 Siwatch 
 
 Snake Creek 
 
 Stilwell 
 
 Strawberry 
 
 Utah Metals 
 
 Walkill 
 
 Yak 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Blast 
 
 Exhaust 
 
 Blast 
 
 Blast 
 
 Blast 
 
 Blast 
 
 Exhaust 
 
 Exhaust 
 
 Blast 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust (Intermittently) 
 
 Blast 
 
 Blast 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Blast 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust for two hours 
 
 Exhaust 
 
 Blast 
 
 Exhaust 20-25 minutes 
 
 Exhaust for one hour 
 
 Exhaust ^2 to I hour 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust ^ to I hour 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust for two hours 
 
 Exhaust "for a while" 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
 Exhaust 
 
VENTILATION 115 
 
 CAPACITY 
 
 There is unfortunately no authbritative rule for determining 
 the amount of air needed to renew that vitiated by the respira- 
 tion of men and animals working in tunnels. For coal mines 
 many States have provided a legal minimum which ranges from 
 IOC to 300 cubic feet per minute for each man and from 300 
 to 600 cubic feet for each animal. These figures, however, 
 have practically no bearing on tunnel work, because in coal mines 
 a much larger volume of air than that actually needed by the 
 men must be supplied in order to dilute and render harmless the 
 inflammable and dangerous gases given off from the coal. In 
 many States the laws provide that even these requirements must 
 be increased at the discretion of the mine inspector. Condi- 
 tions in metal mines, on the other hand, are more closely akin 
 to those in tunnels, but, unfortunately, wherever any legislation 
 exists at all it merely stipulates that the ventilation must be 
 ''adequate." 
 
 Robert H. Richards considers that the following air quantities 
 are sufficient for proper ventilation in metal mining work:* 
 
 Per light, i cubic foot per minute. 
 Per man, 25 cubic feet per minute. 
 Per animal, 75 cubic feet per minute. 
 
 The Mining Regulations Committee of the Transvaal, on the 
 other hand, provide (for metal mines) a minimum of 70 cubic 
 feet per man per minute.t When a person is sitting in repose 
 as in a theater or meeting-hall, 20 cubic feet of fresh air per 
 minute is considered adequate provision by engineers making a 
 specialty of ventilation, but much larger quantities are of course 
 required when working. The following table giving the results 
 of a test, conducted by Bernhardt Draeger,J shows the amount 
 of air breathed in the first minute after performing various 
 kinds of work. 
 
 *" Mining Notes." Richards, Robt. H., Vol. II, p. 142. Thos. Todd, 
 Boston, 1905. 
 
 t Eng. and Min. Jour., November 5, 19 10, p. 899. 
 X Gliickauf, 1904, No. 42. 
 
116 
 
 MODERN TUNNELING 
 
 QUANTITY OF AIR ACTUALLY BREATHED IN FIRST MINUTE 
 AFTER EXERTION 
 
 Kind of Work 
 
 Subject 
 A 
 
 Subject 
 B 
 
 Subject 
 C 
 
 Average 
 
 Sitting 10 minutes 
 
 Walking 270 yards 
 
 Marching 550 yards 
 
 Running 270 yards .... 
 Rolling barrel weigh- 
 ing y^ cwt 
 
 Running 550 yards .... 
 
 Race, 270 yards 
 
 Time of race .... 
 
 8.5 liters 
 10.5 " 
 14-3 " 
 30. 
 
 38. 
 38. 
 52. 
 40 sees. 
 
 8 . 25 liters 
 II. 3 " 
 17-5 " 
 30. 
 
 33- 
 42. 
 61. 
 42 sees. 
 
 9 . o liters 
 II. 7 " 
 130 " 
 30. " 
 
 40-5 " 
 38. " 
 59- " 
 42 sees. 
 
 58 liters* 
 2 " 
 9 " 
 
 * I liter = 0.0353 cu. ft. 
 
 These figures give the amount of pure air actually exhaled and 
 inhaled, but of course, in order that the products of respiration 
 may be diluted sufficiently for the air in the confined space of 
 a tunnel to be kept pure, a much larger quantity than this must 
 be supplied. Assuming that 20 cubic feet is sufficient for a 
 man at rest, and applying the ratio deduced from Draeger's 
 table, it would appear that the following volumes of air should 
 be supplied for ventilation if the same exercise were undertaken 
 in a small room or in a tunnel : 
 
 Ventilation Required When Exercising in a Restricted Space 
 
 Sitting, 20 cubic feet per minute. 
 Walking, 26 cubic feet per minute. 
 Marching, 35 cubic feet per minute. 
 Running, 70-90 cubic feet per minute. 
 Rolling barrel, 85 cubic feet per minute. 
 Race, 130 cubic feet per minute. 
 
 Although some members of the tunnel crew, such as the shovelers, 
 ordinarily work as hard as men running or rolling a barrel, 
 the work of the drillers as a rule more closely approximates 
 the exertions required in walking; so, taking everything into 
 consideration, it would seem that 75 cubic feet per minute 
 should be adequate provision for tunnel ventilation, as far as 
 the requirements of human respiration are concerned. Assum- 
 ing that an animal requires two to three times the air needed 
 for a person, on this basis 150 to 200 cubic feet per minute 
 
VENTILATION 117 
 
 should be furnished each of them. At mine tunnels where any 
 attempt is made for even moderate progress, from 8 to 15 men, 
 and possibly two animals, are employed in or near the heading. 
 Under these conditions 600 to 1,500 cubic feet of fresh air per 
 minute would be required for purposes of respiration. It is 
 true that some air is furnished by the exhaust from the drills, 
 but their action is intermittent and the supply never adequate, 
 so that much dependence cannot be placed upon it; on the 
 whole, it is much better simply to ignore this possible source 
 when deciding upon the capacity of ventilating machinery. 
 
 Although the above capacity is sufficient for ordinary require- 
 ments, a much greater, and indeed the maximum, demand for 
 ventilation occurs immediately after blasting, when it is obvi- 
 ously important to remove the gas and smoke quickly so that 
 the men may resume work with the least loss of time. The 
 volume to be removed depends largely upon the amount of 
 explosive employed; for customary charges under normal con- 
 ditions it would probably not vary greatly from 60,000 cubic 
 feet, the average result of practical experience at tunnels where 
 information bearing on this question was obtainable. It is 
 true that ordinarily the air is seldom contaminated by the blast 
 for more than 150 feet from the face, which in a heading of 
 70 square feet cross-section would have a volume of but 10,500 
 cubic feet, and it might appear that the removal of this amount 
 of bad air would clear the tunnel. Such might be the case 
 provided the smoke could be removed instantly, but this is of 
 course not attainable in practice. The readiness with which 
 gases become diffused must be taken into consideration, es- 
 pecially in this case, since it is customary, immediately after 
 blasting, to turn a jet of highly compressed air into the heading. 
 Such a practice is necessary because, to avoid injury from 
 flying rock, the ventilating pipe rarely extends nearer the breast 
 than 100 feet, so to remove the gases they must be forced out 
 of the extreme end of the tunnel into the influence of the suction 
 of the ventilating pipe. The result is that as a portion of the 
 bad air is removed its place is occupied by fresh air, which quickly 
 becomes contaminated, and it is necessary, therefore, to remove 
 
118 MODERN TUNNELING 
 
 nearly six times the amount of foul air to clear the tunnel. In 
 order to be considered good practice, under ordinary conditions 
 this should be done in fifteen minutes, requiring an exhauster 
 capable of removing 4,000 cubic feet per minute. 
 
 This capacity, however, is necessary for only a few minutes 
 after blasting. It is desirable therefore to have the fan or blower 
 so arranged that it can exhaust for a short time at full load and 
 then be run at a lower speed and supply the heading with the 
 smaller volume needed for respiration. Such was the case at 
 the Laramie-Poudre tunnel, where the exhauster was directly 
 connected to a water-wheel and commonly removed approxi- 
 mately 1,300 cubic feet running at 100 r. p. m. But immediately 
 after blasting the blower was speeded up to 300 r. p. m. when it 
 exhausted nearly 3,900 cubic feet per minute, clearing the 
 heading usually in 15 to 20 minutes. 
 
 At the Rawley tunnel an attempt was made to secure 
 the same result by operating the blower intermittently at 
 or near full load. Although the operation of the blower or 
 fan at full load for one-third of the time supplies the heading 
 with an equal amount of air as when running at one-third 
 capacity all the time, different results are obtained in practice. 
 The purity of the air is not maintained so nearly constant with 
 the intermittent system, and since the starting and stopping 
 of the blower are usually dependent upon some man, they are 
 apt to be forgotten or neglected. This method of ventilating, 
 therefore, cannot be commended. 
 
 PRESSURE 
 
 It is, of course, essential that the required amount of air be 
 actually delivered to, or removed from, the heading; to do this, 
 pressure is necessary in order to overcome the frictional resist- 
 ance to the flow of air in the pipe. This pressure must be 
 generated by the fan or blower and may be either positive, 
 when forcing air in, or negative, when exhausting it; in either 
 case the amount required depends upon the quantity of air 
 passed and the size and length of pipe. Although the relations 
 between these several factors are somewhat complicated, they 
 
VENTILATION 
 
 119 
 
 are shown in the following formula advocated by George S. 
 Hicks, Jr.: 
 
 \ I g 
 
 Where q = quantity of air in cubic feet per minute. 
 
 d = diameter of pipe in inches. 
 
 P = absolute initial pressure in pounds per square 
 inch. 
 
 / = length of pipe in feet. 
 
 g = specific gravity of gas referred to air as unity. 
 From which we obtain by transposing: 
 
 -<■■ 
 
 Where p 
 
 ' — \ 216.10 + 
 P 
 
 qH 
 
 14.7 
 
 2000 d^ 
 
 14 . 7, or the required pressure in pounds pei 
 square inch, 
 
 It must be borne in mind that the formula is theoretical 
 and does not take into consideration leakage, the extra friction 
 due to elbows in the pipe, etc., but it is said to be based on 
 good general practice for air and gas transmission and to give 
 fairly satisfactory results. The following table, calculated from 
 the formula, shows the pressure, in pounds per square inch, 
 required to pass air through various sizes and lengths of pipe, 
 assuming its quantity to be 4,000 cubic feet per minute (the value 
 derived above as a suitable maximum capacity for a ventilating 
 blower or fan). 
 
 Loss OF Pressure, in Pounds per Square Inch, When Forcing 4,000 
 Cubic Feet of Air per Minute Through Various Lengths and 
 Sizes of Ventilating Pipe 
 
 Diameter 
 of pipe, 
 
 
 
 
 Length of Pipe in Feet 
 
 
 
 
 
 
 in 
 inches 
 
 1,000 
 
 2,000 
 
 3.000 
 
 4,000 
 
 3.000 
 
 6,000 
 
 8,000 
 
 10,000 
 
 12,000 
 
 14,000 
 
 6 
 
 8 
 
 10 
 
 12 
 
 14 
 
 16 
 
 18 
 
 :20 
 
 20.2 
 
 6.75 
 2.52 
 1.06 
 0.50 
 0.26 
 0.14 
 0.085 
 
 iiis' 
 
 4.69 
 2.05 
 0.98 
 0.51 
 0.29 
 0.17 
 
 6^65 
 2.90 
 
 1-45 
 0.76 
 
 0.43 
 0.25 
 
 8*45 
 3-87 
 1.90 
 1.02 
 0.58 
 0.34 
 
 10. 1 
 4.71 
 2.32 
 125 
 0.70 
 0.42 
 
 5-52 
 2.77 
 1.48 
 0.84 
 0.50 
 
 7 
 3 
 
 I 
 I 
 
 
 06 
 60 
 95 
 II 
 67 
 
 8 
 
 4 
 2 
 
 I 
 
 
 63 
 40 
 40 
 
 38 
 83 
 
 9 
 
 5 
 2 
 
 I 
 
 
 87 
 16 
 
 84 
 64 
 99 
 
 5 90 
 3 27 
 1.89 
 115 
 
120 
 
 MODERN TUNNELING 
 
 If the pressure cannot be increased to correspond with the 
 length of pipe, the volume of air delivered is diminished (the 
 size of the pipe remaining the same). This is illustrated in the 
 following table in which a maximum pressure (P — 14.7) of one 
 pound per square inch is assumed. 
 
 Maximum Air Capacities in Cubic Feet per Minute of Pipes of 
 Different Sizes and Lengths When the Initial Pressure Is One 
 Pound per Square Inch 
 
 Diameter 
 
 Length of Pipe in Feet 
 
 of pipe, in 
 inches 
 
 1,000 
 
 2,000 
 
 3.000 
 
 4,000 
 
 5,000 
 
 6,000 
 
 8,000 
 
 10,000 
 
 12,000 
 
 14,000 
 
 6 
 
 8 
 
 10 
 
 12 
 
 14 
 
 16 
 
 18 
 
 20 
 
 685 
 I410 
 2465 
 3890 
 5720 
 
 7985 
 10,720 
 13,950 
 
 485 
 1000 
 
 1745 
 2750 
 
 4045 
 5645 
 7580 
 9865 
 
 '815 
 1425 
 2245 
 3300 
 4610 
 6190 
 8055 
 
 705 
 1235 
 1945 
 2860 
 3990 
 5360 
 6975 
 
 630 
 1 105 
 1740 
 2560 
 3570 
 
 4795 
 6240 
 
 575 
 1005 
 1590 
 2335 
 3260 
 
 4375 
 5695 
 
 870 
 
 1375 
 2020 
 2825 
 3790 
 4930 
 
 780 
 1230 
 1810 
 2525 
 3390 
 4410 
 
 710 
 1125 
 1650 
 2305 
 3095 
 4025 
 
 660 
 1040 
 1530 
 2135 
 2865 
 3730 
 
 The following table shows the calculated pressure required 
 to overcome frictional resistance in passing a volume of air 
 
 Pressure Required to Force Amount of Air Equivalent to Catalogue 
 Rating of Ventilating Machine to Proposed Length of Tunnel 
 Through Pipe Chosen 
 
 Carter 
 
 Central 
 
 Laramie-Poudre 
 
 Los Angeles Aqueduct: 
 
 Elizabeth Lake 
 
 Little Lake 
 
 Grape- Vine 
 
 Lucania 
 
 Marshall-Russel 
 
 Mission 
 
 Nisqually 
 
 Rawley 
 
 Roosevelt 
 
 Siwatch 
 
 Snake Creek 
 
 Strawberry 
 
 Utah Metals 
 
 Rated 
 
 capacity, 
 
 cu. ft. per 
 
 minute 
 
 1560 
 5540 
 3900 
 
 6350 
 2500 
 2500 
 3120 
 4160 
 2500 
 2400 
 2500 
 4800 
 1560 
 4650 
 4000 
 
 Diameter 
 vent. 
 . pipe, 
 inches 
 
 15 
 19 
 
 I4>^ 
 18 
 
 i8>^ 
 
 I2>^ 
 
 10 
 
 14 
 
 12K 
 
 i6>^ 
 
 10 
 
 16 
 
 14 
 12 
 
 Stated length 
 of vent, pipe 
 when tunnel 
 is completed 
 
 7600 
 9500 
 9200 
 
 13000 
 3000* 
 1500* 
 12000 
 1 1000 
 
 13000 
 5000 
 
 6200 
 
 15700 
 5000 
 
 14000 
 19000 
 II 800 
 
 Pressure 
 
 required, 
 
 in lbs. per 
 
 sq. in. 
 
 0.41 
 
 1-93 
 3-34 
 
 4.14 
 1.23 
 0.63 
 0.87 
 8.30 
 
 10.25 
 0.87 
 2.02 
 4-38 
 1.94 
 4.27 
 750 
 
 13-24 
 
 * This division contains a number of tunnels. The distance given is the maximum. 
 
VENTILATION 121 
 
 equal to the rated capacity of the ventilation machine, through 
 pipes of the sizes adopted, to the headings of some of the tunnels 
 visited in the field work. 
 
 It will be observed in these examples that the pressures 
 needed ordinarily range from i to 5 pounds, 2 pounds being 
 roughly the average. At two of the tunnels in this Hst, in order 
 to secure the extra pressure required to furnish sufficient ventila- 
 tion, it was necessary to use a ''booster," as it is called; that is, 
 to install a second machine some distance within the tunnel 
 and by operating both together virtually doubling the pressure 
 otherwise attainable. At the Mission tunnel, the booster was 
 situated near the 5,500-foot station. At the Strawberry, 
 both machines had been placed in the tunnel at the time of 
 examination, the first one at 4,000 feet and the second at 11,000 
 feet. Two other tunnels had not penetrated far enough at the 
 time visited to require such additional equipment, but doubtless 
 extra provision for obtaining pressure will become necessary 
 with continued progress. 
 
 SIZE OF PIPE 
 
 The necessity for high pressures (and hence the use of boost- 
 ers) may be obviated in large measure by the choice of ventilating 
 pipe having diameters of sufficient size. The difference between 
 a 1 2 -inch and an 18-inch pipe often exerts a great influence on 
 the ventilation of the heading, but even aside from added cost, 
 indiscriminate enlargement is undesirable, every inch of space 
 in the average tunnel being jealously required for other purposes. 
 
 By transposing formula (i) we obtain 
 
 =^ 
 
 (fig 
 
 2000 (P2_ 14.72) 
 
 which gives the necessary diameter of the pipe in terms of the 
 other variables. The following table shows a number of solu- 
 tions of this formula (assuming again .that g = 4,000 cubic feet 
 per minute to be passed) and from it may be found the proper 
 size of pipe for use with various pressures and distances. 
 
122 
 
 MODERN TUNNELING 
 
 Diameter of Pipe in Inches, Required in Order to Deliver 4,000 Cubic 
 Feet of Air per Minute with Different Initial Pressures and for 
 Various Distances 
 
 
 
 
 
 Length of ] 
 
 Pipe in 
 
 Feet 
 
 
 
 
 Pressure 
 
 
 
 
 
 
 
 
 
 
 
 
 1,000 
 
 2,000 
 
 3,000 
 
 4,000 
 
 5,000 
 
 6,000 
 
 8,000 
 
 10,000 
 
 12,000 
 
 14,000 
 
 I oz. 
 
 2li< 
 
 24K 
 
 
 
 
 
 
 
 
 
 2 " 
 
 18K 
 
 2I>< 
 
 23 
 
 24>< 
 
 
 
 
 
 
 
 3 " 
 
 17 
 
 19^ 
 
 21X 
 
 22 >^ 
 
 23K 
 
 24H 
 
 
 
 
 
 4 " 
 
 ley^ 
 
 i8>^ 
 
 20 
 
 21^ 
 
 22X 
 
 23 
 
 24K 
 
 
 
 
 5 " 
 
 15'A 
 
 17^ 
 
 19K 
 
 20X 
 
 2I>< 
 
 22 
 
 23K 
 
 24>^ 
 
 
 
 6 " 
 
 15 
 
 17 
 
 i8>^ 
 
 I9K 
 
 20K 
 
 21^ 
 
 22K 
 
 23>^ 
 
 24^ 
 
 
 8 " 
 
 '4 , 
 
 16^ 
 
 17'A 
 
 18K 
 
 19^ 
 
 20 
 
 21X 
 
 22X 
 
 23 
 
 23H 
 
 10 " 
 
 I3>< 
 
 I5>< 
 
 16H 
 
 I7K 
 
 i8>^ 
 
 I9X 
 
 20K 
 
 21^ 
 
 22 
 
 22^ 
 
 12 " 
 
 12^" 
 
 14^ 
 
 16 
 
 17 
 
 17K 
 
 i8>^ 
 
 I9>^ 
 
 20K 
 
 21K 
 
 21K 
 
 I lb. 
 
 I2>< 
 
 14 
 
 i5>< 
 
 16 
 
 1634 
 
 i7>^ 
 
 i8>^ 
 
 19K 
 
 20 
 
 20H 
 
 i>^ " 
 
 iiy^ 
 
 13 
 
 14 
 
 14^ 
 
 I5>^ 
 
 16 
 
 17 
 
 17^ 
 
 i8>^ 
 
 19 
 
 2 
 
 I0J4 
 
 12X 
 
 13^ 
 
 14 
 
 14^ 
 
 15 
 
 16 
 
 1634 
 
 i7'A 
 
 17K 
 
 3 
 
 9H 
 
 iiX 
 
 12 
 
 12^ 
 
 13^ 
 
 13^ 
 
 14^ 
 
 15X 
 
 15H 
 
 ley 
 
 4 
 
 9 
 
 loK 
 
 iiX 
 
 12 
 
 I2>^ 
 
 13 
 
 13H 
 
 I4>^ 
 
 15 
 
 15H 
 
 5 
 
 8K 
 
 10 
 
 10^ 
 
 IlK 
 
 IlK 
 
 12J4 
 
 13 
 
 13^ 
 
 14 
 
 14K 
 
 6 
 
 8X 
 
 9>^ 
 
 I0>< 
 
 II 
 
 11^ 
 
 IIK 
 
 I2>^ 
 
 13 
 
 I3>^ 
 
 14 
 
 8 " 
 
 7^ 
 
 9 
 
 9^ 
 
 IO>< 
 
 loH 
 
 iiX 
 
 II>< 
 
 12X 
 
 12^ 
 
 13A 
 
 COMPARISON OF FANS AND BLOWERS 
 
 Within certain limits, the speed at which fans are operated 
 determines the volume of air delivered and the pressure gen- 
 erated, but these machines are incapable of producing pressures 
 much greater than i]4 pounds per square inch, and many of them 
 are limited to 8, or even 5, ounces. Therefore, as the frictional 
 resistance against which air is to be forced or exhausted becomes 
 greater through increasing lengths of pipe, the pressure generated 
 in the fan must be increased (by greater speed) to the maximum 
 Umit at which the fan may be operated, and after that is passed, 
 the volume of air delivered necessarily becomes diminished. The 
 blower, on the other hand, is capable of much higher pressures, 
 8 pounds per square inch being easily attainable, while with 
 some makes 15 pounds is possible, and in tunnel work where 
 distances are, as a rule, great, the ability to deliver air against 
 high resistance is an important consideration in favor of the 
 blower. It operates also at a much lower speed when delivering 
 the same volume of air against an equal pressure (i : 10 is con- 
 
VENTILATION 123 
 
 sidered a fair ratio), and this lessens the wear and tear upon 
 belts and machinery. Because of its higher pressure, the blower 
 makes it possible to choose a smaller diameter of pipe, a factor 
 worthy of consideration, since not only the initial cost, but also 
 the space occupied, must be taken into consideration. The first 
 cost of the fan, on the other hand, is less than that of the blower, 
 and to economize room and obviate the wear on the belt it may 
 be connected directly to electric motors, the greater cost of 
 low-speed motors tending to prevent this possibility with a blower. 
 
 CONCLUSION 
 
 In most cases a machine of the blower type, capable of high 
 pressure, is better adapted for tunnel ventilation where resist- 
 ances are apt to be great. For best results the ventilating pipe 
 should be so arranged that the direction of the air current may 
 be alternated at will, exhausting for a short time after shooting, 
 and blowing for the remainder of the time. The blower should 
 be adjusted to operate at two capacities: a lower one supplying 
 <5oo to 1,500 cubic feet per minute as determined by the number 
 of men and animals, and a higher one capable of exhausting 
 approximately 4,000 cubic feet per minute, which would make it 
 possible, under ordinary conditions, for the men to resume work 
 in the heading about fifteen minutes after shooting. The press- 
 ure generated in the blower must be properly adjusted to the 
 size of the pipe and the length of the tunnel in order that the 
 determined volume of air shall be actually delivered to or removed 
 from the heading. The pipe chosen should be of such size that 
 only a moderate pressure at the blower is required, at the same 
 time due consideration being accorded such items as cost of 
 pipe, and the space such pipe must occupy. 
 
 Turbo-compressors, however, which are especially suited for 
 high rotative speeds of electric motors, making it easily possible 
 to connect the two directly without loss due to speed reduction, 
 which are capable of maintaining a high efficiency (nearly double 
 that of the centrifugal fan and fully equal to, if not greater 
 than, that of the blower) even after long service, and which may 
 
124 MODERN TUNNELING 
 
 be designed by using a proper number of stages to deliver air 
 against any given resistance, will deserve serious consideration, 
 as soon as they are made in suitable sizes, as a possible choice 
 for ventilation machinery. 
 
CHAPTER VII 
 
 INCIDENTAL SURFACE EQUIPMENT 
 
 In connection with the blacksmith and repair shops, mention 
 should be made of the drill-sharpening machine and the com- 
 pressed-air meter. The use of the former is quite common, 
 being employed at a majority of the tunnels visited; but the 
 latter, so far as could be learned, has been used only in one or 
 two places, although there appears to be a field for its employ- 
 ment in tunnel plants. 
 
 DRILL-SHARPENING MACHINES 
 
 Several t3^es of drill-sharpening machines are used in the 
 United States, each consisting essentially of a frame on which 
 two cylinders are mounted (one vertically, the other horizon- 
 tally), each containing a reciprocating piston. Compressed air 
 is employed as the motive power, the consumption ranging from 
 30 to 100 cubic feet per minute at 85 to 100 pounds pressure, 
 according to figures given by the manufacturers. Some device 
 is necessary to hold the drill steel firmly in place. The sharp- 
 ening is accomplished by means of suitable dies or dollies, which 
 are either attached to or struck by the proper piston and mold 
 the hot steel into the desired shape. The piston and die acting 
 vertically is used for drawing out the corners of a broken or a 
 very dull bit, or swaging out the grooves between the points, or 
 insuring that the bit is of the required gauge, while the horizontal 
 one sharpens the cutting edges. With a suitable set of dies, the 
 machine may be used also for the construction of new bits from 
 ordinary drill steel. 
 
 The use of a sharpening machine results in some saving of 
 labor cost, for but one operator is required, who need not even 
 
 125 
 
126 MODERN TUNNELING 
 
 be high-priced. Such a man can ordinarily turn out several 
 times the work of a skilled blacksmith and helper sharpening 
 bits by hand. One manufacturer claims that his machine, when 
 handled by an expert, is capable of sharpening 250 drills per 
 hour, but he states also that half that number, under normal 
 conditions, is good work. With another type, the capacity is 
 given as 60 to 100 sharpened drills per hour. The lowest of 
 these figures is more than ample for the usual requirements of 
 tunnel work since, according to figures obtained at tunnels 
 visited, the number of drills ordinarily sharpened ranges from 
 100 to 200 per day, although in hard ground as many as 400 
 were used. 
 
 The labor saved in the blacksmith shop is only a minor 
 consideration, however, for the real superiority of the machine 
 over hand-sharpening lies in its ability to turn out perfect bits. 
 Since the progress in tunnel-driving is often largely determined 
 by the time required to drill a round of holes, this important 
 part of the work deserves careful attention. It has been demon- 
 strated repeatedly by practical epcperience that on comparing 
 the cutting qualities of a machine bit with one sharpened by 
 hand there is a marked difference in favor of the former. This 
 is due to the fact that the bits come from the machine true to 
 gauge, thus greatly reducing the danger of binding or sticking 
 in the hole; there is, therefore, less delay in drilling and a smaller 
 loss of time from this cause for the driller and helper (or perhaps 
 the entire crew), and there is less likelihood of '^ost'^ holes. 
 Then, too, the bits being correctly shaped and properly sharp- 
 ened, they not only ^' stand up" better and stay sharp longer, 
 but they also drill faster, and it is not necessary for the drill 
 crew to change steel so often, thus reducing another source of 
 delay. The use of drill-sharpening machines at the ordinary 
 tunnel plant is, therefore, strongly recommended not only for 
 its saving of time and labor both in the blacksmith shop and 
 in the heading, but also for its ability to make bits whose superior 
 drilling qualities will easily pay, because of additional pro- * 
 gress, a handsome return upon the money invested in the 
 machine. 
 
INCrDENTAL SURFACE EQUIPMENT 127 
 
 AIR METERS 
 
 Air meters are of various types, depending upon differences 
 in principle and design. In one of them the volume of air is 
 measured by causing it to impinge consecutively upon a number 
 of turbine wheels mounted on a common shaft which is con- 
 nected with a registering device by a properly designed master 
 gear. The machine is caHbrated to read in cubic feet per 
 minute of free air and is claimed by the manufacturer to give 
 accurate measurements of air under varying pressures. A 
 second type operates upon the principle that, with a uniform 
 difference of pressure on both sides of an orifice and a constant 
 initial pressure and temperature, the quantity of air passed 
 is proportional to the size of the orifice. In this machine the 
 difference in pressure on the two sides of the diaphragm is 
 kept uniform by the constant weight of a taper plug which 
 closes the orifice until the difference in pressure is sufficient 
 to raise the plug and support it. The taper is so designed that 
 the amount of air passed through the orifice is directly propor- 
 tional to the rise of the valve, and this movement is multiplied 
 and transmitted to a needle which records it upon a moving 
 sheet of paper, thus aft'ording a means of measuring the volume 
 of air passed. A third type consists in a device for determining 
 the pressure due to the velocity of the flow of air in a pipe (which 
 is proportional to the amount of air passed if the temperature 
 and initial pressure are constant) and transmitting that pressure 
 to one arm of a U-tube filled with mercury. The tube is bal- 
 anced on knife-edges, and since the pressure causes a flow of 
 mercury to the other arm, the balance is disturbed and the 
 tube is deflected, the amount of deflection being commensu- 
 rable with the flow of air. This is transmitted by levers 
 to a recording needle. In a fourth type, although only a 
 proportional volume ranging from ys oi i per cent, to 8 per 
 cent, is actually measured, the recording device registers in 
 terms of the full loo per cent, volume. 
 
 Any of these meters may be used to determine the amount 
 of compressed air delivered to a purchaser. Their most im- 
 
128 MODERN TUNNELING 
 
 portant use, as far as tunnel work is concerned, is in determining 
 the amount of air used by rock drills. It is weU known that all 
 pneumatic rock drills show an increased air consumption (which 
 is less in some than in others, to be sure, but appreciable in all) 
 caused by leakage, etc., as the various parts become worn 
 through use. This fact is quickly discovered in practice and 
 a large nimiber of actual tests bear out the statement that after 
 six months' or a year's steady use of the ordinary rock drill, 
 the amount of this loss will range from 20 to 40 per cent. This 
 additional air is not only expensive to compress, but, what is of 
 more importance, the efficiency of the drilling machine is lowered 
 at the same time, and the man behind it is unable to do as 
 much effective work, thus entailing further loss. If the drill 
 repair man has to guess at the air consumption, it is very diffi- 
 cult for him, even though he is an expert mechanic, to send a 
 drill from the repair shop back to the heading that will do as 
 good work as when it was new. But if the shop is provided 
 with some means of determining the air required by the drill, 
 he is much better able to remedy the defects and make the 
 proper repairs. This results in a saving of expensive power 
 and increases the efficiency of the drill and the amount of work 
 done by the driller. It is very desirable also to keep a record 
 every time the drill leaves the repair shop, not only of the cost 
 of repairs, but also of its present air consumption, in order that 
 upon its next return a comparison may be made with the last 
 record, as well as with the nominal air requirements. By such 
 a course necessary repairs may be made, if the air consimiption is 
 excessive, that would perhaps have been unsuspected otherwise, 
 while at the same time the manager may keep an accurate 
 statement of drill repairs and inefficient drills may be weeded 
 out. The following sample gives a rough outline of such a 
 system:* 
 
 DRILL RECORD 
 
 Tool Piston drill Maker Size 2% inches 
 
 Purchased 2/1 /lo Serial No. 123,456 Shop No. 12 
 
 Normal air consumption, 90 cu. ft. per min. at 75-80 lbs. 
 
 * By courtesy of the Excelsior Drill and Mfg. Co. 
 
INCIDENTAL SURFACE EQUIPMENT 
 
 129 
 
 Date 
 
 Air Consumption 
 
 Pressure 
 
 Repairs 
 
 2/24/10 
 
 94 
 
 76 
 
 2 side rods 
 
 3/10/10 
 
 99 
 
 78 
 
 2 pawl springs 
 I leather cup 
 I chuck bolt 
 I chuck key 
 
 5/10/10 
 
 128* 
 
 75 
 
 I air chest and valve* 
 
 back to 
 
 96 
 
 
 2 piston rings 
 
 ^ Excessive air consumption corrected by repairs indicated. 
 
CHAPTER VIII 
 
 ROCK-DRILLING MACHINES 
 TYPES 
 
 As a rule, rock-drilling machines are classified primarily 
 according to the motive power by which they are operated. 
 The great majority of those used in tunnels are of the pneumatic 
 type, but hydraulic and electric drills have been employed. For 
 surface work, steam is sometimes substituted for compressed air 
 by making a few minor alterations in pneumatic drills, and 
 machines using gasoline power are also to be found on the 
 market; but the difficulty with the former in disposing of ex- 
 haust steam and with the latter the products of combustion, 
 prevent any extensive use of these types underground. The 
 following paragraphs describe some of the principal features of 
 the various rock drills employed in tunnel work. 
 
 Pneumatic Drills 
 
 The pneumatic rock drill consists essentially of a cylinder 
 containing a piston or a hammer which is reciprocated by the 
 proper admission, application, and release of compressed air. 
 In the piston type of air drill, a drill steel provided with cutting 
 edges is alternately made to strike and recede from the rock by 
 the movement of the piston to which the steel is firmly attached. 
 In the hammer drill, the steel does not reciprocate, but is held 
 loosely against the rock to which it merely transmits blows 
 received from a moving hammer. (See Figure 28.) Piston 
 drills are, almost without exception, mounted in a shell or cradle 
 which may be attached to some rigid support while the drill is in 
 operation, but which is easily removed when necessary; a screw 
 thread is provided also, permitting the drill to be fed forward 
 in the shell as the hole grows deeper. In some types of hammer 
 
 130 
 
ROCK -DRILLING MACHINES 
 
 131 
 
 i 
 
 drills, especially those used 
 for sloping and trimming, 
 the shell is omitted and 
 the drill either is held in 
 the hand or is provided 
 with a telescoping feed, 
 operated automatically by 
 compressed air. In either 
 type, some device is re- 
 quired to rotate the drill 
 steel in order that the cut- 
 ting edges of the bit may 
 not strike repeatedly in 
 exactly the same place. In 
 cradle-mounted drills this 
 is generally accomplished 
 by a mechanism (consisting 
 of rifle-bar, ratchet, and 
 pawls) which is arranged 
 to turn the piston or ham- 
 mer, this in turn rotating 
 the chuck holding the drill. 
 Where the telescoping feed 
 is employed it is necessary 
 to rotate the entire machine 
 by hand. Figure 29 shows 
 a section through a piston 
 pneumatic rock drill and 
 gives a list of the princi- 
 pal parts. 
 
 Pneumatic drills are 
 often differentiated by the 
 method employed in con- 
 trolling the admission of 
 air to the cylinders. This 
 may be accom_plished by 
 
 tappet, air-thrown, or aux- Fig- 28. Section through a hammer drill. 
 
132 
 
 MODERN TUNNELING 
 
 iliary valves, or the air supply may be regulated directly by the 
 movement of the piston or hammer itself. 
 
 The action of the tappet valve is illustrated in Figure 30, 
 which shows a section through a drill equipped with the same. 
 As the piston in operation moves from the position shown in 
 
 Fig. 29. Section through a piston rock drill. 
 
 I, Cylinder; 2, Air chest; 3, Inlet port; 4, Exhaust port; 5, Reverse 
 ports; 6, Valve; 7, Valve bushing; 8, Buffer; 9, Check nut; 10, Top head; 
 II, Oil chamber; 12, Ratchet ring; 13, Rifle bar; 14, Ratchet; 15, Plug; 
 16, Feed nut; 17, Lock washer; 18, Check nut; 19, Washer; 20, Feed 
 handle; 21, Yoke; 22, Feed, screw; 23, Shell; 24, Trunnion; 25, Lower head; 
 26, Clamp bolt; 2"], Bushing; 28, Gland; 29, Packing; 30, Piston; 31, Clamp 
 bolt; 32, Chuck bushing; 33, Chuck button; 34, Piston rings; 35, Cylinder 
 ports. 
 
 the cut toward the lower end of the cylinder, the crank end of 
 the tappet rises, while the other end drops into the depression 
 of the piston, thus producing a slight rotation around the tappet 
 pin, which is sufficient to move the sHde valve. This admits 
 live air against the lower end of the piston, at the same time 
 connecting the upper end of the cyhnder with the exhaust pipe. 
 The piston, therefore, starts in the other direction, and a similar, 
 but reverse, process takes place. 
 
 The operation of the air-thrown valve is somewhat more 
 complicated than the tappet, but by referring to Figure 29, 
 which shows a section of a drill equipped with the usual 
 form of air- thrown valve, the action is shown to be as follows: 
 The piston is indicated as just starting on the down stroke, the 
 valve being so placed that live air is entering the top cylinder 
 port (35) from the air inlet port (3) by way of the connecting 
 passages indicated by dotted lines, while at the same time the 
 
ROCK-DRILLING MACHINES 
 
 133 
 
 front of the cylinder is connected with the exhaust (4) by the 
 lower cylinder-port and its air-ways. The upper end of the 
 ''spool" of the valve 
 is connected with the 
 lower end of the 
 cylinder — and hence 
 with the exhaust — 
 by the reverse port 
 (5) (shown unshaded 
 in the illustration). 
 As soon as the piston 
 in its travel uncovers 
 the other reverse 
 port (5) (shown by 
 dotted lines), pres- 
 sure from the upper 
 end of the cyHnder 
 will be transmitted 
 to the lower end of 
 the spool and throw 
 it against the upper 
 end of the valve chest, 
 and this will alternate 
 the connection of the 
 ports for live air and 
 exhaust, thus revers- 
 ing the piston. A 
 similar process is then 
 repeated on the up- 
 stroke. 
 
 In a recent modi- 
 fication of the usual 
 air- thrown valve the 
 spool is replaced by 
 a cylindrical shaft 
 carrying two flat 
 wings, which some- 
 
 FiG. 30. Section of a tappet valve drill. 
 
134 
 
 MODERN TUNNELING 
 
 what resemble those of a butterfly. The operation of this 
 valve is illustrated somewhat diagrammatically in Figures 31, 
 32, and ^2>- In Figure 31 the piston F is represented as about 
 
 S- Supply 
 
 Front End 
 of Cylinder 
 
 Fig. 31. 
 
 S-Supply 
 
 Fig. 32. 
 
 S -Supply 
 
 Fig. 33. 
 Figs. 31, 32, and 33. Action of butterfly valve. 
 
 to Start on the forward stroke. The valve is thrown so that live 
 air is permitted to enter through the supply ports S, S2, and SS2, 
 while the spent air in the front end of the cylinder is exhausting 
 through the ports EEi, Ei, and the exhaust E. As soon as the 
 piston in its forward movement uncovers the exhaust port EE2, 
 live air will pass through EE2 to E2, and its pressure on the 
 valve at this point will balance its pressure on the opposite wing 
 
ROCK-DRILLING MACHINES 
 
 135 
 
 of the valve facing 
 port 52. The valve 
 will then be in equilib- 
 rium, but will be held 
 stationary with the 
 ports S2 and Ei open 
 because of the impact 
 of the air opposite S2. 
 Near the end of the 
 stroke, however, the 
 piston closes the ex- 
 haust port EEi, and 
 in passing from EEi 
 to Fi it compresses 
 the air which is trap- 
 ped in the clearance 
 space at the end of 
 the cylinder. This 
 cushion pressure, 
 communicated 
 through the cyhnder 
 ports SSi to Si, is 
 sufficient to throw the 
 balanced valve to the 
 position shown in 
 Figure 33. Live air 
 is then admitted, 
 through 5 1 and SSi, 
 the exhaust ports ££2 
 are opened, and the 
 piston starts on the 
 return stroke. 
 
 One form of aux- 
 iliary valve used on 
 a well-known piston 
 drill is described as a 
 mechanism in which 
 
 Fig. 34. 
 
 Section through a tappet auxiliary 
 valve drill. 
 
136 
 
 MODERN TUNNELING 
 
 the strains, shocks, and jars to which the tappet or rocker is 
 subjected are transferred from the main valve, with its vital and 
 delicate functions, to a smaller auxihary valve weighing only a 
 few ounces, especially designed to withstand the service. This 
 drill is illustrated in Figure 34. 
 
 When the drill is in operation, one end or other of the auxiliary 
 valve projects slightly into the cylinder, and is thrown by the 
 piston in its travel. The movement is perfectly free and very 
 short — only enough to uncover a small port and release pressure 
 from one end of the main valve, which is at once thrown by 
 the resulting unbalanced pressure, opening wide the main port 
 and admitting compressed air to the other end of the piston for 
 
 Fig. 35. Section through a steel-ball auxiliary valve. 
 
 the return stroke. The auxiliary valve is simply '' a trigger which 
 releases the main valve." 
 
 In another form of auxiliary valve, the main air-thrown 
 spool is controlled by two auxiliary valves consisting of steel 
 balls which are positively actuated by the movements of the 
 piston. See Figure 35. In this figure the piston A is repre- 
 sented as having just started on the down stroke. Compressed 
 air is entering the upper end of the cylinder through the port G 
 and the spent air in the lower end is escaping through the port H 
 and the exhaust chamber /. At the end of the stroke the ball C 
 will drop on its seat and the ball D will be raised, thus allowing 
 the air in the end of the valve chest at F to exhaust past D 
 through the port between the upper and lower balls. The un- 
 
ROCK-DRILLING MACHINES 
 
 137 
 
 balanced pressure thus produced throws the valve to the other 
 end of the chest, which reverses the connections between the 
 cylinder chambers and the inlet and exhaust ports. The piston 
 therefore starts on the return stroke and a similar but reverse 
 process takes place. 
 
 The valveiess air-regulating mechanism, in which the move- 
 ment of the piston itself covers and uncovers various ports, is 
 employed almost exclusively on drills used for stoping only. 
 Although rarely chosen for tunnel work, a brief description of 
 this method of regulating air supply is warranted by its extensive 
 
 Fig. 37. 
 
 Figs. 36 and 37. Cross-sections through valveiess drill. 
 
 use in its own field. The principle of operation is illustrated in 
 Figures 36 and 37, which are two cross-sections through the 
 cylinder of one make of valveiess drill. In Figure 2)^, air under 
 pressure enters from the feed cylinder through the port a and 
 passes to the front of the piston, where it exerts pressure at all 
 times. The piston is forced back until the port e (Figure 37) is 
 uncovered, when compressed air passes through the port / and 
 exerts pressure on the top of the piston. Since the area of this 
 face is greater than the striking end, the piston starts forward. 
 Live air is shut off when the port e is closed, but the piston is 
 pressed forward by the expansion of the air until the exhaust 
 port b is opened just as the blow is struck on the drill steel. 
 
138 
 
 MODERN TUNNELING 
 
 Hydraulic Drills 
 
 The best known hydraulic rock drill is, perhaps, one of the 
 rotary type developed for use in the Simplon tunnel, which 
 consisted essentially of a hollow steel tube armed with teeth 
 which were held firmly against the rock by hydraulic pressure 
 while at the same time the tube was slowly revolved by a water- 
 driven motor. Although, as far as could be ascertained, it has 
 
 SECTION" A-A 
 
 Fig. 38. Rotary hydraulic rock drill. 
 
 never been used for tunnel work in the United States, the intro- 
 duction of the following description (see Figure 38), as given by 
 PreUni,* we consider warranted by its historically interesting 
 foreign achievements: 
 
 "This rotary motion is given by a twin-cylinder single-acting 
 hydraulic motor (e), the two pistons, of 2^ inches stroke, acting re- 
 
 " Tunneling," page 103. 
 
ROCK-DRILLING MACHINES 139 
 
 ciprocally as valves. The cranks are fixed at an angle of 90° to 
 each other on the shaft, which carries a worm-gearing with a worm- 
 wheel iq), mounted upon the shell (r) of the hollow ram (i), and 
 this shell in turn engages the ram by a long feather, leaving it free 
 to slide axially to or from the face of the rock. The average speed 
 of the motor is 150 revolutions to 200 revolutions per minute, the 
 maximum speed being 300 revolutions per minute. . . . The press- 
 ure on the drill is exerted by a cyHnder and hollow ram (i), which 
 revolves about the differential piston (s), which is fixed to the envel- 
 ope holding the shell (r). This envelope is rigidly connected to the 
 bedplate of the motor, and, by means of the vertical hinge and pin 
 (t), is held by the clamp (F) embracing the rack-bar. When water 
 is admitted to the space in front of the differential piston the ram 
 carrying the drilling-tool is thrust forward, and when admitted to the 
 annular space behind the piston, the ram recedes, withdrawing the 
 tool from the blast-hole. The drill proper is a hollow tube of tough 
 steel 2^ inches in external diameter, armed with three or four sharp 
 and hardened teeth, and makes from five to ten revolutions per minute, 
 according to the nature of the rock. When the ram has reached the 
 end of its stroke of 2 feet 2^ inches, the tool is quickly withdrawn 
 from the hole and unscrewed from the ram; an extension rod is then 
 screwed into the tool and into the ram, and the boring is continued, 
 additional lengths being added as the tool grinds forward; each 
 change of tool or rod takes about 15 seconds to 25 seconds to perform. 
 The extension rods are forged steel tubes, fitted with four-threaded 
 screws, and having the same external diameter as the drill. They 
 are made in standard lengths of 2 feet 8 inches, i foot 10 inches, and 
 11^ inches. The total weight of the drilling-machine is 264 pounds, 
 and that of the rack-bar when full of water is 308 pounds. The ex- 
 haust water from the two motor cyHnders escapes through a tube 
 in the center of the ram and along the bore of the extension rods and 
 drill, thereby scouring away the debris and keeping the drill cool; 
 any superfluous water finds an exit through a hose below the motors, 
 and thence away down the heading. The distributor, already men- 
 tioned, supplies each boring-machine and the rack-bar with hydrauKc 
 pressure from the mains, with which connection is effected by means 
 of flexible or articulated pipe connections, allowing freedom in all 
 directions. The area of the piston for advancing the tool is 153^ 
 square inches, which under a pressure of 1,470 pounds per square inch 
 gives a pressure of over 10 tons on the tool, while for withdrawing the 
 tool 2}^ tons is available." 
 
 A recently invented percussion hydraulic drill is described 
 
140 
 
 MODERN TUNNELING 
 
 fully in the Engineer,^ from which Figures 39 and 40 and the fol- 
 lowing brief abstract are taken: 
 
 The drill consists essentially of a cylinder, in which is a piston C, 
 free to move, while at the other end of the cylinder is a flap valve 
 D, which is kept open by a spring. The interior of the cylinder is in 
 
 BoTts for attaching..^ 
 to drill post _H~ 
 
 Fig. 39. Hydraulic percussion rock drill. 
 
 communication with a ''striking tube" F G, at the end F of which 
 is an air vessel. When the valve E is opened, water flows through the 
 apparatus, out past the valve D, into the waste pipe E. The rush 
 of water past the valves causes the pressure on the under side to be 
 less than the pressure on the upper side, where the velocity is less. . . . 
 . . . When the velocity attains a certain value the difference of 
 pressure is sufficient to close the valve, and the column of water in 
 
 FrDm Mftixks p 
 
 Fig. 40. Section through striking tube, hydraulic percussion rock drill. 
 
 the striking tube is suddenly stopped. The kinetic energy of the 
 water in the tube is communicated to the piston C, which is impelled 
 forward with high velocity, and the drill which is at the end of it 
 strikes a heavy blow on the stone or rock being bored. 
 
 The pressure in the interior of the cylinder is diminished by the 
 moving out of the piston C, . . . enough for the valve to open. 
 Water then streams through the open valve. The piston is meanwhile 
 being brought back to its original position by springs, but before 
 
 * " New Hydraulic Rock-boring Dv'iW," the Engineer (London), January 
 7, 19 10, page 24; 2 >^ cols, illustration. 
 
ROCK-DRILLING MACHINES 141 
 
 it is right back . . . the valve D closes, and the direction of motion 
 is reversed by the hydraulic shock. The drill then strikes another 
 blow as before. The actual apparatus is shown in section and plan 
 in Figure 39, which is roughly to scale, the overall length being 
 about 4 feet. 
 
 The actual magnitude of the blow depends primarily upon (i) the 
 weight of the striking column; (2) the velocity of the water when the 
 valve closes; and (3) the weight of the chisel and boring bar. 
 
 The velocity of the column is fixed by the velocity at the valve 
 required to produce the necessary difference of pressure to close the 
 valve, i.e., it is fixed by the stiffness of the spring controUing the 
 valve. The rapidity of the blows is limited by the fact that after 
 each blow the striking column is brought to rest, and it must be accel- 
 erated to the requisite velocity before the valve will close. The 
 rapidity of working depends, therefore, upon the pressure which is 
 urging the column forward, i.e., it depends on the pressure in the 
 supply mains. The actual magnitude of the blow is said to be un- 
 affected by the varying pressure in the mains, and to depend only 
 on the weight of the striking column and the strength of the spring 
 controlHng the valve. The inventor claims that machines of the 
 type described strike from twenty to thirty blows per second, while 
 the maximum speed of percussion machines of existing types is from 
 three to five strokes per second. 
 
 One of these machines has recently undergone a series of tests 
 at the Millbank Pumping Station of the London HydrauHc Power 
 Company. The pressure used was 450 pounds per square inch. . . . 
 The tests were carried out on a block of hard Portland stone. The 
 diameter of the drill used was 2 }i inches, and on an average progress 
 was made in the stone at the rate of io>^ inches per minute. This 
 is equivalent to the removal of 46 cubic inches of stone per minute. 
 The drills stood up to the work so well that after holes aggregating 
 about 25 feet in depth had been drilled, it was not necessary to do 
 anything to the edge. A stream of water plays on the chisel the whole 
 time, and serves the threefold purpose of keeping the chisel cool, 
 of rinsing the bore-hole, and of allaying the dust. 
 
 Electric Drills 
 
 An electric rock drill consists primarily of an electric motor 
 and a means of applying the power developed in it to the work 
 of drilling rock. In some machines the motor is mounted directly 
 upon the drill frame, but in others it is removed a short distance 
 and connected to the drill by a flexible shaft, or some similar 
 
142 MODERN TUNNELING 
 
 device for transmitting power. Provision must also be made 
 for preventing the shocks and jars developed by the impact of 
 the drill steel upon the rock from being transmitted back to the 
 motor, which is a machine incapable of operating for any length 
 of time under such conditions. In many of the earlier models, 
 springs or cushions of some elastic material such as rubber were 
 used for this purpose. These devices failed to give satisfaction 
 either because of inability to do the work required or because 
 of excessive wear, breakage, and annoyance. In two or three of 
 the early models, an ingenious attempt was made to avoid these 
 troubles by taking advantage of the fact that if an electric cur- 
 rent is passed through a spiral coil of wire, a suitably placed bar 
 of soft iron will be drawn into it. By providing two such coils 
 or solenoids and causing the current to flow through them 
 alternately, an iron piston carrying a drill steel was made ta 
 reciprocate between them. In order to have the blow sufficiently 
 smashing to be effective, however, a prohibitive weight of copper 
 wire was needed for the solenoids. To-day practically all elec- 
 tric drills use compressed air in some manner to cushion the reac- 
 tion of the blow, — a medium possessing the very desirable 
 characteristic of extreme elasticity and at the same time not 
 affected by wear and tear. In one machine, however, a hammer 
 is made to strike the end of the drill steel by centrifugal force, 
 the rebound giving the necessary flexibility. 
 
 One of the successful electrically driven rock drills that has 
 been on the market for over five years is illustrated in Figure 41. 
 In this machine the drill piston is reciprocated -by alternating 
 pulsations of compressed air, created by a double-cyhnder air 
 compressor driven by a standard electric motor. Two short 
 lengths of hose connect the air compressor to the drill, each 
 running from one of the compressor cyhnders to opposite ends 
 of the driU cylinder. The air in the system, which acts as an 
 unwearing cushion between the pulsator and the drill, is never 
 exhausted, but is simply used over and over. The drill is very 
 simple — merely a cylinder containing a piston and rotating 
 device — and valves, chest, side rods, buffers, and springs are 
 omitted, while the compressor has neither valves nor water 
 
 n 
 
ROCK-DRILLING MACHINES 
 
 143 
 
 jackets. The motor may be designed for either direct or alter- 
 nating current as desired, and it is mounted with the compressor 
 on a wheeled truck for easy handling. 
 
 A second air-cushioned electric drill of the piston type, but 
 
 Fig. 41. Electrically driven rock drill, shown partly in section. 
 
 one in which the motor is mounted directly on the drill frame, is 
 illustrated in Figure 42. In this drill the motor M, which can be 
 readily detached from the rest of the machine whenever it is 
 
 Fig. 42. Section through an air-cushioned piston electric drill. 
 
 necessary to move the drill to a new set-up, etc., is connected 
 by reducing gears to a crank shaft S, which drives a connecting 
 rod R. This is attached and gives a reciprocating motion to a 
 cylinder C, which sHdes in suitable guides and contains a piston 
 
144 MODERN TUNNELING 
 
 P, provided with a chuck for holding a drill steel. As the cylinder 
 moves forward, air is compressed in the chamber B behind the 
 piston and makes the piston move forward, which causes the 
 drill bit to strike the rock. During the return stroke of the 
 cylinder, the compression of air in the other chamber F brings 
 the piston back again with it. Rotation is secured by means of a 
 standard spiral nut and ratchet. Details of the feed screw, the 
 carriage, and other features are shown in the illustration. 
 
 In an electrically driven air-cushioned rock drill of the 
 hammer type (Figure 43), power is transmitted by suitable gears 
 and cranks from the motor to a piston and causes it to recipro- 
 cate in an air cylinder. The same cylinder contains at its other 
 end a hammer, which, however, is in no manner directly connected 
 with the piston. As the latter starts on the down stroke it 
 compresses the air in the space between it and the hammer, 
 which is projected forward until it strikes the end of the drill 
 steel. Just as it does so it releases the compressed air by un- 
 covering an exhaust port controlled by a poppet valve. When 
 the piston starts on the return stroke the exhaust valve closes 
 and a partial vacuum is created which pulls the hammer toward 
 the piston. The latter in its travel uncovers an inlet port, also 
 poppet controlled, admitting new air, which destroys the vacuum. 
 . The momentum of the hammer would cause it to strike the piston, 
 which again starts on the down stroke were it not for the compres- 
 sion of this air entrapped by the closing of the poppet valve as 
 soon as the vacuum is destroyed. The drill steel is rotated by the 
 motor through a shaft, gearing, and a ratchet. Hollow steel is 
 used through which water is forced to the cutting edge by a 
 small pump supplied with the drill; but if water under pressure 
 is already available, however, the pump may be disconnected. 
 Another feature of this drill is the automatic chuck which is 
 adapted for using steel as it comes in the bar, thus obviating 
 the necessity of forging shanks. 
 
 A fourth electric drill, also having an air-cushioned hammer, 
 is illustrated in Figure 44. In this drill as the yoke A moves 
 forward, the piston B compresses the air in the chamber C, 
 forcing the cylindrical hammer D against the anvil block £, 
 
146 
 
 MODERN TUNNELING 
 
 which transmits the blow to the drill steel at F. On the return 
 stroke of the piston, the compression of air in the chamber G 
 brings the hammer back in readiness for another blow. Hollow 
 
 Fig. 44. 
 
 Sectional view of an electrically operated air-cushioned hammer 
 drill. 
 
 steel is employed through which water is forced by a small 
 pump whose plunger reciprocates with the drill piston. 
 
 So far as could be learned, the only electric drill in service 
 to-day which does not use an air cushion is the one illustrated 
 
 Fig. 45. 
 
 Electric revolving hammer drill with motor and part of casing 
 removed. 
 
 in Figure 45. In the illustration will be seen the two hammers 
 which, although free to slide in their sockets in the revolving 
 disk, are thrown out by centrifugal force and strike the anvil 
 
ROCK-DRILLING MACHINES 147 
 
 block, which transmits the blows to the drill steel. The steel, 
 which is held in a chuck rotated by a worm gear as indicated, is 
 of the auger type, the spirals acting in the capacity of conveyor 
 for removing broken rock from the hole. 
 
 Gasoline Drills 
 
 Since the difficulty of disposing of the waste products of com- 
 bustion, which are not only hot and disagreeable but also 
 contain gases injurious to the health of the workmen, makes the 
 gasoline drill hardly suitable for service undergroimd, and since 
 as far as could be learned they have never been used in tunnel 
 work, their design and construction will not be discussed here. 
 A description of one of these machines having two explosion 
 cylinders may be found, however, in the Engineering and Mining 
 Journal for November 21, 1908, page 1,008; in the Engineering 
 News for November 26, 1908, page 575, and in the Mining and 
 Scientific Press for December 19, 1908, page 852. Another drill, 
 one of English manufacture, in which a cam, driven by a gasoKne 
 engine, trips a spring-actuated piston, was described in the 
 Engineer (London) for September 30, 1910, and in the Engineer- 
 ing News for November 17, 1910, page 538. 
 
 MERITS OF EACH TYPE 
 Pneumatic Drills 
 
 The chief advantage of the pneumatic rock drill is its ability 
 to withstand rough usage and still perform efficient service. 
 The work of a rock drill is done necessarily under conditions that 
 would quickly destroy almost any other type of machinery. 
 It is subjected to constant and severe vibration when in oper- 
 ation, for although it is usually held firmly and securely, still 
 it cannot be mounted rigidly. Lubrication, when supplied at 
 all, is often administered in large doses most irregularly, and it 
 is impossible to prevent sand and grit from getting into the 
 machine, thus adding greatly to the wear and tear. In many 
 cases, men who operate it have no conception of its construction, 
 and ignorantly subject it to shocks and strains for which it was 
 
148 MODERN TUNNELING 
 
 never designed, their first impulse when things go wrong being 
 to seize a sledge-hammer and hit the machine in the most con- 
 venient place. All drill runners, of course, do not belong to this 
 type, but the description fits a much too large percentage of them. 
 Everything considered, the rock drill must be capable of being 
 operated under the most adverse conditions. This necessitates 
 the elimination of all unsuccessful details, the rejection of com- 
 pKcated parts that are not absolutely essential, the determination 
 of the proper size and strength of those remaining, and the 
 selection of materials having the proper stability and wearing 
 quahties. This can be accompHshed in any machine only after 
 patient development and experiment, and it is but natural that 
 the pneumatic drill, which has been undergoing such a process 
 for more than fifty years, should be able better to cope with 
 these conditions and to operate more steadily with fewer inter- 
 ruptions and a lower cost for repairing broken or worn parts 
 than any of the newer types. 
 
 Among other advantages of the pneumatic drill may be 
 mentioned the facts that it furnishes a certain amount of venti- 
 lation, that it does away with the introduction underground of 
 electricity at comparatively high voltages (which is oftentimes 
 a source of danger), and that it does not require pipes strong 
 enough to withstand the pressures needed for the rotary 
 hydrauHc drill. The air drill, however, should not be relied 
 upon for ventilation, because, in the first place, the supply 
 of air is intermittent, being arrested while the drill is stopped 
 for the purpose of changing steel or moving it into position for 
 a new hole, etc. ; in the second place, the drills are not in oper- 
 ation immediately after the blast — the time when ventilation 
 is most needed — although it is true that the use of pneumatic 
 drills makes it possible to direct a jet of compressed air into 
 the heading at this time to assist in removing the smoke; and, 
 iinally, there are on record cases in which the exhaust from 
 the drills not only did not deliver fresh air but even filled the 
 heading with carbon dioxide and other dangerous gases produced 
 by combustion of oil and grease in the receiver, resulting, in 
 one instance at least, fatally for several men. Again, at tunnels 
 
ROCK-DRILLING MACHINES 149 
 
 using electric haulage the adoption of electric drills would 
 simply add a little to a danger already present rather than intro- 
 duce a new one, and in such cases the advantage of the air drill 
 in this respect is not so important. 
 
 The most important disadvantage of the pneumatic drill, 
 on the other hand, is its well-known lack of power economy. 
 Since, as stated by E. A. Rix,* "the tables set forth in the 
 trades catalogues for the consumption of standard piston rock 
 drills are fairly accurate," let us determine from them the 
 power required for rock drills by using his estimate of 20 b. h. p. 
 per 100 cubic feet of free air per minute. The lowest figure 
 given for any type of rock drill used at the tunnels examined 
 for this report is 65 cubic feet per minute at 100 pounds press- 
 ure, while drills using as much as 150 and even 175 cubic feet 
 were very numerous. On this basis, then, without making 
 allowance for loss of power through friction in the pipes or leak- 
 age in the machines when they become worn, pneumatic drills 
 require the application of from 13 to 35 brake horse-power at 
 the compressor during the time the machine is operating. Al- 
 though the rotary hydrauKc drill employed in the Simplon 
 tunnel required as much as 13 horse-power f (exactly the min- 
 imwoci figure just deduced for air drills) it is by comparing the 
 power used in air drills with even the maximimi of 6 horse-power 
 for electric drills, many of which run on less than 2, however, 
 that the large difference in power consumption is revealed. 
 
 Comparing the different types of pneumatic drills used in 
 tunneling, the piston machine has somewhat the advantage 
 over the hammer type as regards reliabihty and as regards effi- 
 ciency in drilKng holes vertically or nearly vertically downward. 
 This reliabihty may be attributed without doubt to its simpler 
 construction. It does not contain any mechanism for intro- 
 ducing a water spray through a hollow drill steel, it is not 
 troubled by crystallization of metal parts from the repeated 
 
 * Address before the Mining Association, University of California, Feb- 
 ruary 19, 1908. 
 
 t Comstock, Chas. W.: "Great Tunnels of the World." Proc. Colo. 
 Sci. Society., Vol. VIII., p. 363. 
 
150 MODERN TUNNELING 
 
 shocks of rapid blows, and it has a much greater range of feed. 
 This last item is a feature of importance when tho machine is 
 handled by an inexperienced operator, giving as it does greater 
 latitude before the piston begins to strike the front head. These 
 considerations make the piston drill more nearly fool-proof, 
 and hence better adapted to use by ordinary drill runners — 
 especially those in the Eastern States, who, as a rule, are neither 
 as intelligent nor as careful as those in the West. Complexity 
 of construction should not be confused, however, with the num- 
 ber of parts; for if this were taken as the standard, and every 
 screw, bolt, or nut counted separately, it could be shown that 
 the hammer drill is the simpler machine. 
 
 The greater eflSciency in drilling holes which point downward 
 was clearly brought out in the recent extensive drill competition 
 in the Transvaal, according to the committee conducting the 
 test, who reported that one of the main reasons for the better 
 showing made by the piston drills underground was the fact 
 that practically all of the holes drilled there were pointed down- 
 ward. This is substantiated in several instances at tunnels 
 in this country in which the excavation is accompKshed by the 
 heading and bench method; in such cases the piston drill is 
 reported to have given better satisfaction in drilling the vertical 
 holes required for the removal of the bench. 
 
 The principal advantages of the hammer drill, of the type 
 used in tunneling, are a somewhat lower air consumption and a 
 greater speed in drilling holes that are horizontal or nearly so, 
 and especially those pointing slightly upward, such as are 
 necessary under the ordinary methods in driving tunnel headings. 
 In hammer drills the air consumption, and hence the amount of 
 power required, varies from 65 to 100 cubic feet per minute at 
 100 pounds pressure (catalogue rating at sea level) as compared 
 with 125 to 175 cubic feet for piston drills. The rate of drilling is 
 of course largely dependent upon the character of rock penetrated, 
 but by observation of the table below (in which it will be seen 
 that piston drills, even in shale and sandstone, rarely drilled 
 over 10 feet per hour, while the hammer drills in granite and 
 other hard rock rarely fell below that figure, 15 and even 20 feet 
 
ROCK-DRILLING MACHINES 
 
 151 
 
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152 MODERN TUNNELING 
 
 being not uncommon) the general statement seems warranted 
 that the hammer t3^e has the greater speed in drilling the holes 
 required in tunnel headings. 
 
 It is difficult to determine just how much of this greater 
 speed is due to the manner of attack, the water feature, the 
 greater ease and speed in replacing a dull steel with a sharp 
 one, or to the non-reciprocating drill steel, but there is httle doubt 
 that all these factors enter i^nto the result. The piston machine 
 when attacking the rock strikes comparatively slow, heavy, 
 smashing blows that soon dull the cutting edges of the bit, 
 especially if the rock be hard, after which, until the steel is 
 changed, the penetration must be accompHshed by crushing. 
 Conversely, the more frequent blows of the hammer type, being 
 lighter, do not dull the bit so quickly and the penetration is 
 effected by a chipping action which is speedier as well as more 
 economical of power. The apphcation of water through a hollow 
 steel to the face of the drill hole, in addition to cooHng the drill 
 bit and preserving the temper of its cutting edges, affords a 
 positive means of removing the cuttings promptly from the 
 front of the bit. This not only prevents the recutting and grind- 
 ing of material already broken, with a consequent saving of 
 power, but increases the efficiency of the machine, since it enables 
 the drill bit always to strike an uncushioned blow on ^'Hve" rock. 
 Hammer drills having the water feature, however, are said to 
 make a poor showing when drilling vertical holes. This is 
 doubtless due to the fact that the velocity of the rising current 
 of water in the drill hole is not sufficient to prevent the rock 
 grains from settHng against it to the bottom of the hole and 
 interfering with the work of the drill. The plunger action of 
 the piston drill, on the other hand, while it is probably no more 
 efficient in actually removing the rock grains, keeps them stirred 
 up enough partly to obviate the difficulty. Any one who has 
 experienced the trouble and delay of changing steels with the 
 usual chuck in piston drills will appreciate the saving in time 
 and energy resulting from the use of a chuck into which the drill 
 needs only to be inserted. Since in the hammer drill the steel 
 does not reciprocate, the elimination of friction against the sides 
 
ROCK-DEILLING MACHINES 153 
 
 of the drill hole effects a considerable saving of power and prevents 
 a retardation of the blow, even though, as has been argued, it is 
 partly offset by the loss of power in heating the hammer and drill 
 end and in overcoming the inertia of the steel. An additional 
 advantage of a non-reciprocating drill steel is the fact that it 
 may be held against the rock at any desired point and a drill 
 hole started wherever necessary without loss of time — a feature 
 especially important where the face of rock is oblique to the drill. 
 
 The weights of hammer drills range from 115 to 170 pounds, 
 while the piston machines used in tunneling at the time the field 
 examination was being made for this volume weighed from 
 280 to 400 pounds, and the dimensions of the former were ap- 
 proximately four-fifths of the latter. This gave the hammer 
 machines an appreciable advantage over the piston drills because 
 they were lighter, smaller, and more easily handled in a restricted 
 space. The shorter length of the hammer machine also made it 
 possible to start the cut holes nearer the sides of the tunnel, thus 
 securing a wider angle between each pair with a consequent 
 increase in the chances of breaking the full length of the round of 
 holes. Since that time, however, the leading manufacturers of 
 drills in the United States have produced and are marketing 
 piston drills that compare closely with the hammer machines 
 in size, weight, and ease of handling, thus reducing these ad- 
 vantages in favor of the hammer drill. 
 
 Piston and hammer drills employed in tunneling are ap- 
 parently on an equal footing to-day as regards cost of drill 
 repair parts, although until quite recently the former had some- 
 what the advantage. From September, 1905, to March, 1906, 
 hammer drills were employed at the Gunnison tunnel with a 
 drill repair cost per machine of 13 cents per foot of hole drilled; 
 but when piston drills were substituted the repairs were reduced 
 to 3 cents per foot.* Two years later (September, 1907, to August, 
 1908), in driving the last 3,000 feet of the Yak tunnel, the cost 
 
 * In addition to the cost of materials, these figures include also a charge 
 for the labor of the machinist making the repairs, which is not embraced in 
 any of the values which follow. This fact must be considered in making; 
 comparisons. 
 
154 
 
 MODERN TUNNELING 
 
 of materials only for repairs to the hammer drills employed was 
 but i^ cents, approximately, per foot of hole. At the Marshall- 
 Russell tunnel, where hammer drills were employed, the average 
 cost of drill repairs from June, 1908, to June, 191 1, was but i^ 
 cents per foot drilled. Piston machines were used at the 
 Strawberry tunnel from January, 1909, to September, 191 1, 
 the cost for repairs being nearly 2^ cents per foot drilled. 
 On the Little Lake Division of the Los Angeles Aqueduct, where 
 hammer drills were employed from July, 1909, to May, 191 1, 
 the average cost of drill repair materials as shown by the table 
 was but 24 cents per foot of tunnel excavated. Since each 
 of the two machines in the heading drills approximately 8 feet 
 of hole for every foot of tunnel excavated, the cost per machine 
 per foot of hole is i^ cents. 
 
 COST OF REPAIRS FOR HAMMER AIR DRILLS. LITTLE LAKE 
 
 DIVISION, LOS ANGELES AQUEDUCT. JULY, 1909, TO 
 
 MAY, 191 1 
 
 Tunnel 
 
 Tunnel Excavated, 
 linear feet 
 
 Total Cost of Drill 
 
 Repairs 
 
 Cost of Drill Repairs 
 per foot of tunnel 
 
 iB South 
 
 2 North 
 
 2 South 
 
 2A North 
 
 2A South 
 
 3 North 
 
 3 South 
 
 4 North 
 
 4 South 
 
 7 North 
 
 7 South 
 
 8 North 
 
 8 South 
 
 9 North 
 
 9 South 
 
 10 North 
 
 10 South 
 
 loA North 
 
 loA South 
 
 1,030 
 926 
 419 
 460 
 
 375 
 
 864 
 
 2,149 
 
 448 
 
 725 
 1,911 
 1 ,024 
 
 225 
 1,334 
 
 777 
 2,479 
 2,626 
 1,776 
 1,373 
 1,756 
 
 $160.59 
 180.72 
 
 6475 
 46.28 
 
 55-50 
 113.60 
 505.01 
 
 67.03 
 215.48 
 399.70 
 493.46 
 146.56 
 530.52 
 230.51 
 404.94 
 585.78 
 577.24 
 303.06 
 359.27 
 
 $0 
 
 156 
 195 
 154 
 10 
 
 148 
 131 
 235 
 149 
 
 297 
 
 209 
 
 482 
 
 651 
 398 
 297 
 163 
 223 
 325 
 
 221 
 
 204 
 
 Average $0.24 
 
 For 1 9 10 and the first half of 191 1 the repair cost of hammer 
 drills at the Carter tunnel was 2 cents per foot of hole. At the 
 Lucania tunnel, the repairs cost }4 cent per foot drilled. 
 
ROCK-DRILLING MACHINES 155 
 
 but the hammer drills had been in use only one month. 
 The hammer drills at the Rawley tunnel were new also, the 
 repairs from May, 191 1, to October, 191 2, averaging 1.9 
 cents per foot of hole. These figures, which are based upon 
 estimates furnished by managers or others in charge at the 
 various tunnels, do not pretend to more than approximate 
 accuracy; but they give a basis for comparison such as has been 
 hitherto unattainable, although in making such comparisons the 
 type of rock must of course be duly considered. 
 
 In spite of the development of other types of valve mechanism 
 for air drills, the tappet valve, which was one of the pioneers 
 in the field, possesses advantages which still keep it in demand 
 for use on piston drills intended for certain kinds of work. Since 
 it is unaffected by condensed moisture, which greatly interferes 
 with the action of some other types, it is especially adapted 
 for use with steam or with air containing a large amount of water 
 vapor. Its distinctive advantage, however, is that its movement 
 is positive; if the piston makes a stroke the valve must be 
 thrown, hence there is no uncertainty in the action of the drill, 
 no ''fluttering." 
 
 The tappet drill is at a disadvantage when working in ground 
 that will not permit of the use of a full stroke, because it is 
 necessary for the piston to travel far enough to throw the valve, 
 and hence too short a stroke is not possible. Then, too, as it is 
 impossible to prevent some air being trapped in front of the 
 piston and compressed after the valve is thrown, it strikes a 
 cushioned blow. This is not always a disadvantage; in elastic 
 and "springy" rock an uncushioned blow will not give the best 
 cutting effect, while in- sticky material compression assists the 
 piston in starting on the return stroke. The tappet is subject 
 to strains and wear which necessitate specially hardened material, 
 not only in the tappet itself but in the bearing surfaces of the 
 piston. 
 
 Under conditions that require a snappy, vicious blow with 
 high air pressure, the ordinary air-thrown valve gives the best 
 results. This feature makes it particularly appHcable to hammer 
 drills in which, because of the small size and weight of the ham- 
 
156 MODERN TUNNELING 
 
 mer, it is essential that there shall be no cushioning of the blow, 
 and it is customarily employed on such of these machines as are 
 not of the valveless type. When used with piston drills, the 
 air- thrown valve permits a variable stroke; it renders possible 
 at will a change in length of piston travel and force of blow. The 
 short stroke and Hght blow possible with this type of drill make 
 it easy to start a hole or to drill through seamy rock. After 
 the hole is under way, or if the rock is solid, a full stroke is used 
 to get the best efhciency from the machine. The air-thrown 
 type of valve is not positive in its action, however, and is apt 
 to be somewhat sluggish with air or steam containing much 
 water. It is claimed for the butterfly type that it avoids this 
 difficulty, as well as most of the troubles caused by freezing, and 
 that it has a positive and at the same time a flexible action 
 which permits of much higher speed than other valves. 
 
 The auxiliary valve is designed to combine the advantages, 
 of the tappet and the air-thrown valves while avoiding their 
 defects. The lightness of the tappet auxiliary is said to prevent 
 the injury or retardation of the piston and also to obviate the 
 rapid wear of rings, piston, and cylinders caused by crowding 
 against the opposite cylinder wall due to an unbalanced tappet 
 not readily moved. A drill equipped with this type of valve has 
 a wide variation of stroke and delivers an uncushioned blow. 
 The main advantage of the steel ball auxihary valve is the great 
 resistance to wear and the cheapness of replacing the wearing 
 parts. It is claimed for this valve that it assures a positive action 
 of the drill without sticking or fluttering, and yet possesses the 
 necessary flexibility. 
 
 The valveless method of regulating admission and exhaust 
 has the advantage of simplicity and lighter weight due to the 
 elimination of the valve and valve chest. It also uses air ex- 
 pansively, and this should result in economy of power. It 
 strikes a cushioned blow, however, thus reducing the drilling 
 power where the rock is hard and tough; but for medium rocks 
 and especially with high air pressure the difference is said to be 
 less pronounced because the lighter and more rapid blows chip 
 rather than pulverize the rock and enable the drill to penetrate 
 
"ROCK-DRILLING MACHINES 157 
 
 readily. One real disadvantage is the fact that as the cylinder 
 becomes worn there is a leakage of air past the piston, thus 
 increasing the air consumption and interfering with the accurate 
 working of the drill. 
 
 Hydraulic Drills 
 
 Among the advantages of the rotary hydraulic drill 
 used at the Simplon tunnel should be mentioned the fact 
 that the power was delivered to the cutting edge without the 
 shocks, jars, and strains due to percussion, thus eliminating 
 one source of wear and tear. The machine also utilized a very 
 high percentage of the power stored in the motive fluid, its 
 efficiency being given by one authority as 70 per cent. Again, 
 by passing a portion of the waste water down the boring tube, 
 chips and debris were promptly removed from the cutting edge, 
 thus insuring the maximum boring power. On the other hand, 
 the pressure required for operating this drill was enormous, 
 ranging from 450 to 1,200 pounds per square inch according to 
 one writer, and 1,470 pounds according to another. In any case 
 the piping necessary to transmit the water under such high 
 pressures must have been most expensive to install and main- 
 tain. The drill also required extremely heavy and rigid mount- 
 ings to withstand the back pressure; these made it cumbersome 
 and hard to move so that it could not be easily placed for a new 
 hole. 
 
 The percussion type of hydrauhc rock drill cannot as yet be 
 said to have been demonstrated to be a practical success. It is 
 an interesting possibility, however; because, hke the hydraulic 
 ram, it utihzes the shock that occurs in pipes at every stoppage 
 of ,a moving column of water. 
 
 Electric Drills 
 
 Among the advantages claimed for the pulsator type of 
 electric drill are saving of power, rapid drilHng speed, simpler 
 construction, and less trouble with fitchered drills. The motors 
 which are used to operate the pulsator require, according to the 
 size of drill, from 3 to 5 horse-power — a very small amount when 
 
158 MODERN TUNNELING 
 
 compared with the necessities of the ordinary pneumatic drill. 
 Although it is true that the cost of power used by a drill is not the 
 only item which determines its efhciency, such a marked differ- 
 ence in power consumption must necessarily exert a great 
 influence. This fact holds especially in the case in hand, since 
 it is claimed and apparently well substantiated by actual results 
 that this machine is fully up to the drilKng speed of any corre- 
 sponding standard air rock drill and has practically the same 
 cost for wages and fixed charges. The pulsator type also 
 ehminates many parts, such as valves, springs, side rods, etc., 
 which are sources of trouble and unrehability in other rock 
 drills. It is able, moreover, to strike a very heavy blow because 
 the pressure of air back of the piston is greatest just at the time 
 of impact; and should the drill steel become caught in the hole 
 from any cause the machine does not cease running, as is the case 
 with air drills, but the pulsator continues to exert several hun- 
 dred alternate pulls and pushes on the drill steel per minute; 
 these in most instances are sufficient to loosen the drill at once, 
 consequently saving considerable time and trouble. 
 
 On the other hand, the combined drill and pulsator are 
 cumbersome and occupy a large space, every inch of which is 
 precious in the tunnel heading — a disadvantage that increases 
 directly with the number of drills needed for the work. For 
 tunnel work it is necessary either to place the truck and pulsator 
 upon the muck pile — a feat consuming extra time and energy 
 and a position where it is subject to damage and breakage if the 
 muck is being removed simultaneously with the drilling — or 
 one must wait until the tunnel is cleared of debris before starting 
 to drill, a procedure which is prohibitive if speed in driving is 
 required. But under circumstances where there is no particu- 
 lar haste or in mining work where drilling and mucking are 
 alternated, this disadvantage is not so serious. 
 
 The piston electric drill described on page 143 does away with 
 the need of a pulsator, truck, and connecting hose, thus making a 
 compact machine and one more comparable with an air drill. 
 It is, however, quite heavy (weighing 490 pounds with the 
 motor attached and 350 pounds without it, and is somewhat 
 
ROCK-DRILLING MACHINES 159 
 
 difficult to handle and move in a small heading. It has a marked 
 advantage over air drills in power economy, operating as it does 
 on 4 horse-power, and actual results show that its drilling speed 
 is fully up to that of standard piston pneumatic drills. At 
 the Elmsford tunnel of the Catskill Aqueduct these drills are 
 reported to have attained a speed of loo feet in six to eight 
 hours when drilling in a comparatively soft mica schist, but in 
 the harder Fordham gneiss of the city tunnel the rate was but 
 60 feet per shift (eight hours). This drill is still in the process of 
 development, in which it is necessary to correct the small defects 
 that always appear in any newly designed machine when put 
 to actual use, but the results attained with it in one portion 
 of the city tunnel, Catskill Aqueduct, .were very encouraging. 
 One of the machines is reported to have operated there for more 
 than five weeks, drilling over 4,000 feet of holes with none but 
 minor repairs, such as pawl springs, etc. 
 
 The weight of the air-cushioned hammer drill and motor 
 described on page 144 is about 150 pounds less than that of an 
 electric piston drill and motor. With the motor removed, 
 although it weighs more than a pneumatic hammer drill, it is 
 but Httle heavier than a piston air drill of corresponding capacity. 
 Its power consumption is rated at 2]/^ horse-power and in the 
 tests on the Catskill Aqueduct 6 to 8 feet per hour was the aver- 
 age drilling speed attained in ordinary work, including delays. 
 This speed will undoubtedly be increased as the delays from 
 breakdowns become less frequent. The drill was still being 
 tried out and in the process of being perfected at the time of 
 examination, so no data could be obtained as to its reliability. 
 
 The other air-cushioned hammer drill (see page 144) has been 
 employed in several mines in Colorado, where, according to the 
 testimonials, it is performing creditable service. 
 
 The average power consumption of the rotary hammer 
 drill (see page 146) is about i kilowatt per hour (i>i horse- 
 power). They were employed on the Elmsford contract of the 
 Catskill Aqueduct and were reported as particularly efficient 
 in comparatively soft rock, drilling at times as high as 100 feet 
 per machine in an eight-hour shift. 
 
160 MODERN TUNNELING 
 
 CHOICE OF DRILL 
 
 The factors to be considered in the selection of a rock drill 
 for tunnel work are, on the one hand, the cost of power, of at- 
 tendance, of maintenance and fixed charges, and, on the other, 
 the rate of drilling, the best drill being the one which combines 
 all these factors in such a way as to develop the greatest drilling 
 speed for the least cost. The power cost should include not 
 only the actual power at the tunnel plant (with its charge for 
 labor, fuel, interest, and depreciation), but all losses in genera- 
 tion, in transmission, and utilization in the drill. The wages of the 
 drill-runners and all helpers required are just as much an item 
 of operating cost as the charge for power. The cost for main- 
 tenance includes the cost of repair parts for the drill and the 
 charge for the time of the machinist, together with the cost of 
 sharpening drill steel. The fixed charges should include interest 
 and depreciation on the cost of the drills and a proportion of the 
 administrative expenses. The rate of drilling, on the other hand, 
 should not be based upon the speed of penetration while the drill 
 is actually hitting the rock, but should include all delays caused 
 by the drill, such as loss of time in preparing the set-up, 
 in shifting position to new holes, in changing drill steels, and 
 any other interruptions properly chargeable against the 
 machine. 
 
 Applying these specifications to the various rock-drilling 
 machines, the hammer pneumatic drill is apparently the one best 
 adapted for use under ordinary conditions in driving mine adits 
 and tunnels. To be sure, its power consumption is more than 
 that for electric drills, but it is about equal to the hydraulic and 
 is less than the piston air drill. In the matter of attendance it 
 has somewhat the advantage. Most of the piston air and the 
 electric types usually require at least two men to operate each 
 drill — a drill-runner and a helper — and the hydraulic machine 
 requires five men.* With the hammer drill a runner is necessary, 
 of course, but one helper often is able to attend to two drills 
 
 * Prelini, "Tunneling," p. 105. 
 
ROCK-DRILLING MACHINES 161 
 
 or two helpers to three machines. We have just seen that there 
 is practically no difference between the piston and hammer air 
 drills as to repair cost. The multipKcity of parts in the rotary 
 hydraulic machine, however, is said to have been a source of 
 much trouble in this respect. Theoretically the hammer drills 
 do not dull the steel so rapidly, and hence should have an ad- 
 vantage in this respect. Practically this is not an important 
 difference because under ordinary conditions the blacksmith 
 is rarely overtaxed, and hence the extra labor of sharpening a few 
 bits more or less is not noticeable on the cost report. The fixed 
 charges are such a smaU portion of the total cost of drilling that 
 any discrepancy in them is rarely, if ever, large enough actually 
 to decide the question. The rate of drilling is really the 
 greatest factor in favor of the hammer type ordinarily 
 used in tunnels. Not only does it penetrate faster when ac- 
 tually drilhng, but, since its reciprocating parts are Hghter 
 and its vibration less than that of a piston machine, it can be 
 employed with a lighter set-up, with a saving of time. Then, 
 too, its abiHty to start a hole at any desired point and to 
 drill rapidly holes that point upward enables it to be used ad- 
 vantageously on a horizontal bar with a saving of the one-half 
 to one and one-half hours which are required to remove the 
 debris before setting up the vertical column used almost without 
 exception in tunnel headings for piston air drills. The hammer 
 drill saves not only time in changing drill steels but energy as 
 well, as any one who has wrestled with the ordinary piston 
 chuck can testify. 
 
 For large tunnels excavated by the heading and bench 
 method and in which a large number of holes are drilled down- 
 ward, or perhaps at other places where, because of acidity in the 
 mine water or some other reason, the water feature of the 
 hammer drill would be unsatisfactory, or for other work than 
 tunnehng, the piston pneumatic drill would doubtless give 
 equally if not more satisfactory results. Or if speed is not 
 especially required and the drilling and mucking shifts can be 
 alternated, the pulsator electric drill with its large power economy 
 might prove the most efficient. And again, if the self-contained 
 
162 MODERN TUNNELING 
 
 electric drills continue to be improved as they have been recently, 
 their greater economy of power will without doubt soon out- 
 weigh their lower drilling speed and present higher maintenance 
 charges, especially at such places where electricity is readily 
 available. On this account their development should be closely 
 watched. 
 
CHAPTER IX 
 HAULAGE 
 
 TUNNEL CARS 
 
 Most students of tunneling methods concede that an essen- 
 tial, and possibly the chief, feature of the problem is the rapid 
 removal of debris produced in blasting; but it is commonly not 
 so well recognized that the speed with which this may be ac- 
 compKshed is greatly influenced by the size of the tunnel-car. 
 Large cars, even when empty, are heavy and cumbersome, but 
 when full of rock they can be handled only with the greatest 
 difficulty. To remove such a car from the heading and replace 
 it with an empty one requires either several extra men to assist 
 in the work or a horse or mule must be provided for the purpose. 
 In the first instance men must be called upon who might other- 
 wise be making arrangements for the rapid loading of the next 
 car or doing any of the many things that make for speed and 
 economy; while in the second, omitting altogether from consider- 
 ation the cost and maintenance of the mule, delays and loss of 
 time cannot be prevented. In addition to being unwieldy, 
 large cars occupy a greater proportion of the actual space in the 
 heading, constricted enough at best, thus preventing the shovel- 
 ers from working to the best advantage; the added height involves 
 a waste of energy because each shovelful of rock must be hfted 
 a greater distance, making it impossible for the men to handle 
 sufficient material in a given time. With large cars it is neces- 
 sary to maintain a switch or siding near the end of the tunnel 
 in order to permit the empty cars to pass the loaded ones, and 
 time and labor must be expended frequently in relocating the 
 switch nearer the heading to keep pace with the tunnel advance. 
 The smaller car, on the other hand, when empty can be tipped 
 off to one side out of the way and replaced easily when needed, 
 thus giving a clear track for a loaded car and obviating the 
 
 163 
 
164 
 
 MODERN TUNNELING 
 
 necessity for a switch. In case of derailment, an occurrence 
 by no means rare in practice because of the poor condition of 
 most tunnel tracks, the large car, even when empty, is harder to 
 replace, and w^hen full it is sometimes necessary to unload all the 
 material in order to get the car back on the track. It is true 
 that a larger number of the smaller cars, each of which occasions 
 some delay in its arrival and departure, are necessary to remove 
 
 Fig. 46. Elevation of tunnel car used in the east end 
 of the Gunnison tunnel. 
 
 the same amount of debris, but the authors are of the opinion, 
 based upon a study of actual conditions at a large number of 
 tunnels, that with proper organization greater progress is at- 
 tainable by using smaller cars, the size preferred being from 15 
 to 25 cubic feet capacity. The tendency at many American 
 tunnels is toward the use of cars much larger than this, especially 
 where electric haulage is employed; but the use of large cars, 
 when analyzed, has been shown to be a handicap rather than an 
 advantage even in those tunnels equipped with them where 
 creditable progress has been made. 
 
 In design, the cars at a majority of the tunnels visited 
 follow the standard mining types with tilting bodies, but at a 
 few of them other types were employed to meet special condi- 
 tions. A car with a side-dumping, tilting-box body was used in 
 
165 
 
 the west end of the Gunnison tunnel. End-dumping cars are 
 similar to this except that the hinge is transverse instead of lon- 
 gitudinal and the door is situated at the end instead of the side. 
 The car used at the Laramie-Poudre tunnel, which is illustrated 
 in Figures 48, 49, and 50, was of the turn-table type, which per- 
 mitted dumping from both sides of the track as well as between 
 the rails. As the system of car handling in the headings at this 
 tunnel necessitated throwing all of the cars over on their sides 
 once (and nine- tenths of them twice) on each trip, the connec- 
 tions between the trucks and bodies of the cars were carefully 
 planned and made unusually strong. The turn-tables were fitted 
 with two concentric rings (Figures 49 and 50), and the locking 
 mechanism for securing the bodies to the trucks was so designed 
 
 O 
 
 Fig. 47. End view of tunnel car. 
 
 that when the releasing lever was fastened in place the cars were 
 as rigid as if the bodies were riveted to the axles. A car of the 
 rocker t3^e (see Figure 51) was used with very satisfactory results 
 in the tunnels of the Los Angeles Aqueduct. At the Nisqually 
 tunnel a similar car, but one with a slightly different locking 
 
Fig. 48. Elevation of tunnel car used in Laramie-Poudre tunnel. 
 
 Fig. 49. End view of tunnel car. 
 

 i !: \VS 
 
 
 
 Comprefision-spring ^~~^ 
 drawhead cast steel "^I? 
 
 Fig. 50. Plan of tunnel car. 
 
 Fig. 51. Rocker dump tunnel car used on Los Angeles Aqueduct. 
 
168 
 
 MODERN TUNNELING 
 
 device, was employed. (See Figures 52 and 53.) In order to 
 obviate the tilting body, the car at the Utah Metals tunnel was 
 constructed with the floor permanently incHned toward the side 
 
 Fig. 52. Tunnel car used at Nisqually tunnel. 
 
 Fig. 53. Method of dumping tunnel car. 
 
 door, while at the Carter tunnel a car of the gable type was used, 
 in which the floor slopes away from the center toward doors on 
 each side of the body. At the east end of the Gunnison tunnel 
 
169 
 
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170 
 
 MODERN TUNNELING 
 
 (see Figures 46 and 47, pages 164 and 165) a simple open box 
 car with the body bolted directly to the truck was employed, and 
 similar cars are now in use in the Strawberry and Newhouse 
 tunnels. Although this car is ideal from the viewpoint of sim- 
 plicity, it requires special equipment for dumping because the 
 entire car must be turned completely over. The table on page 
 169 contains suggestive data concerning the cars used in tunnels 
 and adits in the United States. 
 
 LOADING MACHINES 
 
 Many attempts have been made to utilize machinery for 
 loading tunnel cars. In several of the larger tunnels intended 
 for railway purposes, power shovels similar to those used in grad- 
 ing or in open-cut mining have been very successfully used in 
 
 Fig. 54. 
 
 "Mucking machine" at the Hummingbird tunnel, 
 Burke, Idaho. 
 
 removing the broken rock of the bench after blasting. In such 
 cases the ordinary steam shovel is generally employed, making 
 a few minor alterations so that it can be operated by compressed 
 
HAULAGE 171 
 
 air. Power shovels operated by compressed air are also employed 
 in some of the mines in the Joplin, Missouri, district. 
 
 The "mucking machine" illustrated in Figure 54 was used 
 successfully during the excavation of the Hummingbird tunnel, 
 at Burke, Idaho. Its principal feature is an oscillating trough 
 or shovel armed with teeth and driven by a compressed-air 
 piston in such a manner that the forward stroke is appreciably 
 faster than the return. When in operation the teeth rest upon 
 a steel plate under the muck pile, and as the shovel is fed forward 
 the broken rock is forced by the jerky motion backward along 
 the trough and discharged upon a belt conveyer which dehvers 
 it to an ordinary mine car at the rear. The entire machine is 
 mounted upon a wheeled truck or framework and is fed forward 
 by a second compressed-air piston connected with a cross-bar 
 which can be jacked against the sides of the tunnel. It is 
 essential that the area of this piston be smaller than the one 
 which drives the shovel; for then, if the latter encounters a 
 boulder or other obstruction too solid for it to dislodge, the 
 entire machine can move forward and back with the stroke of 
 the larger piston. By this means the machine is not only 
 prevented from injury before the obstruction can be removed, 
 but in many cases it will work the boulder aside without any 
 assistance. One man is required to operate the machine, and two 
 more are needed to tram the car to and from the end of the 
 conveyer and to shovel the rock out of the corners of the tunnel 
 into the trough, for the machine does not swing from side to 
 side, but merely cuts a swath down the center of the tunnel, 
 and hence leaves a certain amount of material piled on each side 
 of it. The machine is reported to have reduced the time re- 
 quired to clean the tunnel from 6 to 2^ hours and to have made 
 it possible to increase the speed of driving quite materially. 
 
 The shoveling machine illustrated in Figure 55 is very 
 ingenious and closely simulates the actions of a man shoveling. 
 At the front is a scoop or shovel, armed with teeth, which is 
 pushed under the broken rock and raised by the action of a 
 chain-driven crank, so that the material is dumped into a hopper 
 just back of the shovel. The hopper in turn travels a short 
 
172 MODERN TUNNELING 
 
 distance, tilts up, and dumps the rock on a belt conveyer which 
 delivers it to cars at the rear. The machine was employed ad- 
 vantageously during the excavation of a portion of the Catskill 
 Aqueduct directly under New York City. In this work six 
 men were employed with the machine; one to operate it, three 
 
 i 7<y/:>e rVn, 3 
 
 Fig. 55. Shoveling machine. 
 
 to pick down the muck pile in front, and two to handle cars in 
 the rear, as compared with the usual crew of fourteen men when 
 mucking by hand. The power consumption was 25 to 30 kilo- 
 watts per shift. The machine would pick up a rock that 
 ordinarily would take three men to put over the side of a car 30 
 inches high and a car holding 35 cubic feet could be loaded in 
 2>^ minutes. 
 
 A power loader of a somewhat different type was introduced 
 in the excavation of the bench at the Yonkers Siphon. It 
 consisted of a chain-and-bucket conveyer, similar to that used 
 in mill elevators and on some gold dredges, which delivered the 
 material to a hopper, whence it was carried to the tunnel car by 
 a flat endless belt. 
 
 Owing to the hardness of the rock and the prevalence of huge 
 boulders, weighing sometimes over a ton and necessitating 
 frequent stops for repairs, this machine was unable to compete 
 satisfactorily with hand loading underground. When operating 
 on the surface, however, loading rock for use in concrete con- 
 struction it is said to have given excellent satisfaction. The 
 
HAULAGE 173 
 
 material was taken from the dump pile produced in excavating 
 the heading of the tunnel in which the rock was broken more 
 uniformly into smaller fragments than the material produced 
 in blasting the bench. It should be mentioned, however, that 
 the size of this machine precludes its use without considerable 
 modification in a small tunnel or heading. 
 
 MOTIVE POWER 
 
 In practically all tunnels of any length in the United States, 
 either animals or electric motors have been or are employed to 
 haul the tunnel cars. In Europe, notably at the Simplon and 
 Loetschburg tunnels, compressed-air locomotives were used 
 successfully. But although those machines are employed to 
 some extent in this country in mining and industrial work, they 
 have failed to give satisfaction at tunnels where they have 
 been tried, chiefly because of the cost of high-pressure air, the 
 maintenance of charging stations, the time lost in charging, etc. 
 Many mines also are equipped with cable haulage ; but because of 
 the constantly increasing length of haul as the heading advances, 
 the use of this system in tunnel work requires such frequent 
 delays and loss of time in extending the cable system that it is 
 hardly suited for tunnel practice. Gasoline locomotives, on the 
 other hand, which have recently proved most successful for coal 
 mining, are in most particulars especially well adapted for tunnel 
 work and deserve equal consideration with animals and electric 
 motors as a means of tunnel haulage. 
 
 The principal advantage of animal haulage is the smaller 
 cost of installation; what is more, it requires no special intelli- 
 gence on the part of the driver, and the abihty of the animals 
 to step across the track at the tunnel headings obviates the 
 necessity of a switch. On the other hand, the costs of main- 
 tenance and operation for animal haulage not only are high, 
 but these factors go steadily on whether the animal is working 
 or not and are influenced but shghtly if at all by the amount 
 of tonnage handled. For these reasons animals are not economi- 
 cal for use in long tunnels because the saving in installation 
 expense is soon destroyed by the increased operating costs. 
 
174 MODERN TUNNELING 
 
 Then, too, the odors arising from the track are offensive and 
 disagreeable when animals are employed and their respiration 
 vitiates the underground atmosphere, necessitating more ample 
 ventilation. As far as efficiency is concerned, there is httle if 
 any difference between horses and mules, although the latter 
 are considered by some to be the sturdier animals. Mules, 
 however, are better fitted for work in low tunnels because they 
 are usually somewhat smaller than horses and, being less nervous, 
 do not throw their heads violently up and back when anything 
 touches their ears. 
 
 Electric mine locomotives may be divided into two classes: 
 those operated from a trolley system and those obtaining their 
 electrical current from a storage battery. The former are so 
 famihar as hardly to require description. They generally consist 
 of two motors, ruggedly constructed to withstand rough usage 
 and protected from dust and moisture, mounted upon a cast-iron 
 or structural steel frame which also carries the trolley, controller, 
 rheostat, and other accessories. The sides of the frame may be 
 placed either inside or outside of the wheels. In the latter 
 type more space is available for the motors and other equipment 
 and the various parts of the machine are more readily accessible. 
 The inside type, on the other hand, has a smaller over-all width 
 and is therefore more suitable for narrow tunnels. The storage 
 battery locomotive is similar in most respects to the trolley 
 machine, except that provision must be made for carrying the 
 necessary batteries. In most cases the batteries are carried 
 directly upon the motor itself, but the locomotive installed at the 
 Central tunnel is somewhat unique in that the batteries are 
 placed upon a separate battery car or tender. When the 
 machine is handling cars in this tunnel it obtains its current 
 from the battery; upon reaching the tunnel mouth, the tender is 
 left on a side track, where it is accessible for recharging, and a 
 trolley, with which the locomotive is also equipped, is employed 
 for switching. 
 
 Electric locomotives are compact and simple in construction 
 and do not emit smoke, gas, or disagreeable odors. They are 
 more rapid and are capable of hauling a much greater load than 
 
HAULAGE 
 
 175 
 
 either a horse or a mule, while the cost of the power used is not 
 nearly so great as the cost of forage. -But, on the other hand, 
 they require the installation of extra machinery in the power 
 plant, an expensive trolley-wire or a troublesome storage battery, 
 and the road-bed and track must not only be heavier in con- 
 struction, but usually the rails must be bonded to make them 
 good electrical conductors. The disadvantage of the cost of the 
 extra electrical machinery is of course partly offset by the fact 
 that it can be utilized also to operate the ventilating machin- 
 ery and to furnish illumination for the tunnel. The use of 
 trolley wires in the restricted tunnel space, however, introduces 
 the grave danger of serious and perhaps fatal injury to persons 
 accidentally or ignorantly coming in contact with them. 
 
 GasoKne locomotives consist essentially of a frame, as a rule 
 of cast-iron, upon which are mounted the gasoline engine (usually 
 
 
 i 
 
 Fig. 56. Gasoline mine locomotive. 
 
 4-cylinder), the necessary transmission system containing gears 
 and clutches, together with the carbureter, magneto, cooKng 
 system, and other accessories. In external appearance (see 
 Figures 56 and 57) they are not unlike the electric locomotives 
 
176 
 
 MODERN TUNNELING 
 
 described above. Two forward and two reverse speeds are 
 usually provided in the machines manufactured in this country, 
 the lower one of 3, 4, or 5 miles per hour, and a higher speed 
 double that of the lower. The draw-bar pull ranges from 1,000 
 to 4,000 pounds, according to the size of the locomotive. In 
 
 Fig. 57. Gasoline mine engine. 
 
 some of the machines the exhaust gases from the engine are 
 passed through a tank containing a solution of calcium chloride, 
 which cools the gases and is said to remove all offensive odors 
 from them. In a German-made machine the exhaust gases are 
 sprayed with water to produce the same effect. 
 
 The gasoHne locomotive combines most of the advantages 
 of both electric and animal haulage. It is self-contained and 
 independent of a central station or any other outside source of 
 power, needing nothing but a track. It is fully as rapid as the 
 electric motor ordinarily used in tunnels and is capable of 
 handling an equal load. The fuel for a gasoline locomotive can 
 be obtained readily in almost any locality, and the machine does 
 not consume fuel when it is not running, a matter of great 
 importance in tunnel work, where interruptions occupy a neces- 
 sarily large percentage of the time. Another advantage, although 
 perhaps not so important for tunnel work, is the fact that the 
 haulage system may be expanded by the addition of extra 
 units without alteration in the power plant, hence the possibility 
 of such future changes need not be considered in the design of 
 the power plant. The following table, based upon replies from 
 
HAULAGE 
 
 177 
 
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178 MODERN TUNNELING 
 
 operators and users of gasoline locomotives received in answer 
 to inquiries sent out by the Bureau of Mines, in 191 2, shows 
 the cost of haulage with these machines. 
 
 Practically the only disadvantage of the gasoline locomotive 
 is the amount of carbon-dioxide given off in the exhaust from 
 the engine, but this can be eliminated by proper and adequate 
 ventilation. When the machine is properly regulated the 
 amount of carbon dioxide should not exceed 2% to 5 cubic 
 feet, depending on the size of the engine. If this were confined 
 in a small unventilated space the air would soon become unfit 
 for breathing, but since the greater part of the time the motor 
 is traveling back and forth in the tunnel and since a large 
 volume of air is, or at a properly organized tunnel should be, 
 suppHed by the ventilating blower, the exhaust gases from the 
 engine are quickly diluted to harmlessness. It is essential, 
 however, that the blower be arranged to deliver the air to the 
 heading through the ventilating pipe rather than through 
 the tunnel, in order that the air may reach the workmen as 
 pure as possible, and it would doubtless be necessary to run the 
 blower somewhat nearer its capacity. But even were it operated 
 at full load, the added cost of doing so would be more than repaid 
 by the saving effected by the gasoHne haulage. 
 
 DUMPING DEVICES 
 
 The box cars used at the Strawberry tunnel were dumped 
 by an electrically driven stiff-leg derrick. The hook in the 
 derrick block carried a bail which engaged trunnions, one at 
 each end of the car. The trunnions were placed in such a way 
 that when an empty car was picked up by the bail the weight 
 of the running gear would be sufficient to hold the car upright, 
 but if the car was loaded its center of gravity would be above 
 the trunnions. A spring-actuated pin, situated in one leg of the 
 bail and engaging a hole in the car body above the trunnion, pre- 
 vented the car from overturning until it was swung out over the 
 place where the rock was to be deposited, when by pulling a 
 rope the attendant could disengage the pin and permit the car 
 to turn over and deposit its contents. It would then auto- 
 
HAULAGE 179 
 
 matically right itself and could be swung back on the track. 
 The derrick was mounted on wheels so that it could more easily 
 be moved ahead, but this was necessary only at intervals of 
 three to six months. 
 
 Among the advantages claimed for this system of dumping 
 is the fact that it could be operated by the train crew, the motor- 
 man running the hoist and the brakeman adjusting the bail, thus 
 saving the labor of a dumping gang. Then, too, it gave a much 
 larger dumping area with a consequent saving of the time which 
 wdth the ordinary mine car is lost in shifting tracks, etc. But 
 this was offset in part by the settKng of the dump, and on this 
 account the moving of the derrick was accompKshed with great 
 difficulty. It is probable that some of this annoyance could 
 be avoided at a future installation by using very wide wheels 
 similar to the type used on roller trucks for moving houses. 
 But the derrick is expensive, costing when erected at the tunnel 
 approximately $3,600, of which hardly more than $1,500 could be 
 realized from its sale after the completion of the work; for this 
 reason its use must extend over a considerable length of time in 
 order that the saving in wages may repay the original cost. 
 
 At the Newhouse tunnel the loaded cars were run into a 
 cyHndrical steel framework having rails at the bottom and a set 
 of angle-iron guides at the top with just enough clearance space 
 between them to hold the car firmly. The entire apparatus was 
 then revolved by an electric motor imtil overturned, empt3dng 
 the contents of the car, and it was then righted by continued 
 revolution and the car removed. Although used here only for 
 ore cars, the material falling into a bin for shipment, it offers 
 a satisfactory and reasonably inexpensive means of dumping the 
 more durable soHd body and truck cars, and could doubtless be 
 applied to tunnel dumps by the use of a light trestle or similar 
 structure. 
 
 Almost any of the various cradle dumps frequently used at 
 coal mines can readily be adapted to tunnel work by mounting 
 upon a stout frame of logs or large timbers, which could be 
 pushed forward along the top of the rock pile as necessity arose. 
 By this means it is possible to eliminate hinges and turn-tables 
 
180 MODERN TUNNELING 
 
 between the body and the truck of the car, thus simplifying 
 and strengthening its construction. One of these cradle-dumps 
 was used at the Lausanne tunnel. It was not expensive and 
 saved a considerable amount of time in dumping cars and in 
 keeping the rock pile in proper condition. It was pushed 
 forward by the motor every two or three days, requiring but a 
 few minutes for the operation. A similar dumping device is 
 used at the Cameron mine, Walsenberg, Colorado. It has the 
 added advantage of being mounted on a turn-table, thus giving 
 nearly double the top width of dump attainable with ordinary 
 cradle devices. As described in Mines and Minerals,"^ the 
 dump consists essentially of three plates of one-eighth inch 
 iron 3 by 4 feet in size. To the top plate are bolted a pair of mine 
 rails with the ends bent up into horns. This upper plate re- 
 volves on a mine car axle, the bearings for which are supported 
 upon a mine rail and bolted to the middle plate. A piece of 
 channel iron is bolted to the middle plate and upon it the dumper 
 falls back after a load of rock has been discharged. The upper 
 plates as a unit revolve upon the two annular pieces of iron, 
 2 2 inches in diameter. The king-pin is i inch in diameter, and the 
 plates, where it passes through them, are reinforced by a piece 
 of J/2- by 3 -inch bar iron. The lower plate is supported by four 
 short lengths of 12 -pound mine rail. 
 
 * October, 1911, p. 158. 
 
CHAPTER X 
 INCIDENTAL UNDERGROUND EQUIPMENT 
 
 TUNNELING MACHINES 
 
 Although tunnels have been constructed for mine drainage, 
 irrigation, and supplying water to cities for thousands of years, 
 they were so few in number during ancient times and constructed 
 at such irregular intervals that there was no great incentive to 
 improve upon the methods ordinarily employed in driving them. 
 With the advent of the steam railroad, however, it was soon 
 realized that the desirability of maintaining easy gradients 
 would necessitate the driving of many tunnels, and the active 
 minds of inventors were immediately directed toward the prob- 
 lem of making a machine which would do this work more or less 
 automatically. 
 
 The first tunneling machine of which any record could be 
 found was constructed at Boston in 185 1 for use in the Hoosac 
 tunnel. It weighed 70 tons and was designed to cut a circular 
 groove in the face of the tunnel, 13 inches wide and 24 inches in 
 depth, by means of revolving cutters. The trial of this 
 machine in the tunnel proved unsuccessful, and only a distance 
 of 10 feet was cut with it before it was abandoned. In 1853 
 the Talbot tunneling machine, which was designed to make an 
 annular cut 1 7 feet in diameter and leave a cylindrical core to be 
 removed by blasting, was tested near Harlem, New York, but 
 also proved unsuccessful. Later a smaller machine was con- 
 structed, adapted to cut an 8-foot annular groove; this, while 
 it was less unwieldy than its predecessor, also proved a com- 
 plete failure after $25,000 had been expended upon it. Although 
 numerous machines constructed upon almost every conceivable 
 principle have been experimented with since 1853, the entire 
 disappearance of most of them from sight, and almost from 
 history, tells only too clearly that the problems of driving 
 
 181 
 
182 MODERN TUNNELING 
 
 through hard rock have been too difficult for the machines to 
 overcome successfully. 
 
 It is not safe to predict from this, however, that a tunneling 
 machine will not, or cannot, be constructed to perform this 
 work in the future because, difficult as the problem of designing 
 such a machine appears, the obstacles in the path are no greater 
 than they have been in scores of other instances where slow and 
 costly manual methods have been superseded by less expensive 
 and more expeditious mechanical processes. The invention of 
 some new rock-cutting device, or the material improvement of 
 some of those now known, may simplify the problem to such an 
 extent that the construction of a successful tunneling machine 
 wiU be rendered comparatively easy. Further encouragement 
 is also to be found in the fact that there have been two machines, 
 designed for driving in the soft chalk formation underlying the 
 EngKsh Channel, that have done practical effective work. 
 
 The first of these is generally known as the Beaumont machine, 
 because, although invented by Major English, it was developed 
 and operated by Major Beaumont, of the English Army. This 
 machine, which was not completed until 1883 (although patented 
 as early as 1864), during a series of tests drove an aggregate of 
 more than 6,000 feet of cyKndrical tunnel 6^ feet in diameter. 
 The maximum rate of progress attained was 81 feet per day, or 
 40 inches per hour. During the final test an average of 50^ 
 feet per day was maintained for fifty-three consecutive days. 
 The machine was afterward tested in the Mersey tunnel at Liv- 
 erpool, where it made an average speed of 30 feet in twenty-four 
 hours in soft red sandstone and a maximum of 40 feet per diem. 
 As the Beaumont machine can be used only in soft rock, a 
 description of its mechanism is hardly necessary here, but its 
 record shows what can be accomplished in mechanical tunneling 
 by a machine carefully designed for the work it is intended to 
 perform. 
 
 The first patent on the B run ton timneling machine was 
 issued July 21, 1868; since then a number of patents have been 
 granted for different improvements. While this machine, like 
 the Beaumont, was designed primarily for driving in the chalk 
 
INCIDENTAL UNDERGROUND EQUIPMENT 183 
 
 formation under the English Channel, it was the direct out- 
 growth of the investigations and improvements on stone-cutting 
 tools by the B run ton and Trier Engineering Company. The 
 success of their stone-dressing machinery, now so largely used 
 in this country and Europe,' is due in a great measure to the 
 perfection of the peculiar cutting tool which was employed in 
 the tunneling machine, and which is described fully in an article 
 on "Modern Stone- Working Machinery," by M. Powis Bale, 
 in Fielden^s Magazine for August, 1900, from which the following 
 quotation is taken: 
 
 ''The cutters are of steel and circular in shape, somewhat after 
 the form of a saucer, and have a rolling motion when in action, con- 
 sequently the great friction resulting from dead pressure is done 
 away with, the cutters having what might be termed a rolling wedge 
 action. This system of rolling cutters was patented some years 
 ago by Messrs. Brunton and Trier, and the pith of the invention may 
 be said to consist in giving the circular cutters a determinate motion 
 on their own axis, at the same time they are carried around in a circle, 
 their cutting edges describing a circular path and the rates of cutter 
 rotation and movement around the circle being so adjusted relatively 
 one to the other that the cutting edge rolls in a slowly advancing cir- 
 cular path." 
 
 The pressure of the sharp wheel against the rock causes the 
 latter to spring off the side of the cut in the form of spawls, 
 very much on the same principle as a sharp-edged wheel-tire will 
 throw a line of chips when passing over a sheet of ice. As there 
 is no percussion, the machine works steadily and quietly, even on 
 the hardest rock, and the durabiHty of the cutting disks is some- 
 thing phenomenal. 
 
 Good descriptions of the Bnmton timneling machine may 
 be found in the following: 
 
 Drinker's ''Tunneling," pages 191-194. 
 Zwick's "Neuere Tunnelbauten," page 68, with cuts. 
 Johnson, Wm.: "Brunton's Heading Machine," Proc. Chester- 
 field and Derbyshire Engineers, October 2, 1875. 
 Engineering, Vol. VII, page 355, May 28, 1869. 
 
 The machine was thoroughly tested out on both sides of the 
 Channel, where it drilled an aggregate of approximately 8,000 
 
184 MODERN TUNNELING 
 
 feet, and it was found that a seven-foot machine would bore a 
 tunnel and load the cuttings on dump cars at the rate of 30 
 inches per hour. Several thousand feet of tunnel were also 
 driven with this machine in somewhat harder rock, but before it 
 could be fully developed and placed upon the market further 
 progress was stopped by the unfortunate death of the inventor. 
 
 Any future tunneling machine, to be successful in hard 
 rock, will have to be simple, durable, not Hable to derangement, 
 easily guided and controlled, and with all parts readily accessible 
 for removal, adjustment, and repairs. It must be so designed 
 as to permit the automatic removal and loading of the cuttings 
 and at the same time afford free access to the face even when 
 it is in operation. All actuating machinery and bearings must 
 be completely housed and protected from mud and water and 
 the framework so constructed that it will not be thrown out of 
 alignment or its advance checked by openings or softened 
 places in the rock. It must also permit of easy removal to and 
 from the immediate face of the tunnel. Viewed in the light 
 of present development, this seems a difficult problem, but the 
 invention of some new cutting device or material improvement 
 in some of those now known may so simplify the task that the 
 construction of a successful tunneling machine for hard rock will 
 be rendered comparatively easy. This has been the course of 
 invention in numberless instances, and we have every reason to 
 expect that here, as elsewhere, history will repeat itself. The 
 simple device of putting an eye in the point of a needle made 
 the sewing machine possible; the breech-loading gun was a com- 
 plete failure xmtil the brass cartridge was invented; and not even 
 the genius of a Langley or a Wright could construct a flying 
 machine until the internal-combustion engine had reached its 
 proper development. 
 
 At present, and during the last four or five years, inventors 
 are and have been unusually active in this Hne of work, and 
 there are several machines which are in the course of construction 
 or are being experimented upon with the view of perfecting and 
 correcting their mechanical details. The following are descrip- 
 tions of some of the more prominent : 
 
INCIDENTAL UNDERGROUND EQUIPMENT 185 
 
 The tunneling machine which is being developed by Mr. 0. 
 O. App, of the Terry, Tench and Proctor Tunneling Machine 
 Company, consists essentially of a rotating head with four arms, 
 each of which carries four specially designed pneumatic hammer 
 drills, so arranged that practically the entire face of the tunnel 
 is covered at each revolution of the head. The drills carry a 
 flat wedge-shaped bit and are arranged so that the action of the 
 hammer is stopped automatically whenever the pressure of the 
 bit against the rock is less than a predetermined amount, thus 
 preventing damage to the drill whenever a tool breaks or a 
 crack or seam in the rock is encountered. The drill bits are held 
 against the rock at a definite angle, and in their operation they 
 chip or flake away the rock instead of attempting to pulverize 
 it. The head is provided with a flange and shield so arranged 
 that the cuttings are Hfted from the bottom of the bore and 
 discharged upon a belt conveyer which in turn delivers them 
 to the tunnel cars at the rear. Air is supplied to the drills 
 through the center of the rotating shaft which carries the head. 
 The entire machine is mounted upon wheels to faciHtate its 
 movement in the tunnel. 
 
 The Bennett tunneling machine consists of a battery of forty- 
 six pneumatic hammer drills mounted in a rectangular head, 
 arranged so that it can be given a vertical as well as a transverse 
 motion, and thus be able to drill a tunnel of any desired size. 
 The head is held rigid while the machines are running, and after 
 the face of the tunnel has been drilled full of holes the head is 
 backed away from the face and the cellular shell remaining 
 between the holes is then broken down with hammers. Experi- 
 ments are now being carried on with this type of machine in a 
 rock heading near Golden, Colorado. 
 
 The International Tunnehng Machine Company's machine 
 is manufactured under the Fowler patents, and consists of a 
 narrow swinging rectangular cutting head, the full size of the 
 tunnel, carrying a battery of forty-one rock drills. These drills 
 are so placed as slightly to overlap each other's path as the 
 cutting head swings from side to side, by which means the 
 entire face is cut away. This permits the continuous operation 
 
186 MODERN TUNNELING 
 
 of the machine, so long as it is in working order, instead of inter- 
 mittent attack as is necessary with the Bennett type of machine. 
 
 A full-sized machine was built in 1909 at the Davis Iron 
 Works in Denver, but, aside from some experimental cutting 
 on a huge block of concrete, nothing was ever done with it, and 
 it is now housed in the shop yard. 
 
 The Karns machine is in principle a large reciprocating rock 
 drill with a cutting head the full size of the tunnel. In the 
 latest machine this head is six feet in diameter and contains 
 forty-one cutter blades made of tool steel, each i inch thick, 
 5 inches wide, and of various lengths. Points like saw teeth 
 are machined on one edge and the other edge is fastened in the 
 face of the head. The reciprocating parts of the machine weigh 
 seven and a half tons and make about 140 strokes per minute 
 of seven inches each. The head is rotated slightly on each 
 return stroke. The machine uses 2,000 cubic feet of air per 
 minute.' One runner, one helper, two muckers, one engineer, 
 and a fireman are needed to run the machine, and a blacksmith 
 and helper are required, one shift in three. 
 
 The Retallack & Redfield tunneling machine, now under con- 
 struction at the Vulcan Iron Works in Denver, is intended to bore 
 an eight-foot cylindrical tunnel. A machine of this size carries 
 twenty-eight percussion drills, symmetrically arranged on a 
 revolving head, each drill having 3 >^ -inch pistons, carrying i^- 
 inch steel bits with the regular cruciform cutting face 6 inches 
 in diameter, so shaped that the twenty-eight drills in one revolu- 
 tion cover and cut away the entire face. Behind the drills, 
 immediately surrounding the cyHnders which actuate them, is a 
 steel tube about 6 feet in length and 7 feet 5 inches in diameter, 
 or 7 inches less than the bore. The outside of this shell is sur- 
 rounded by three-inch flanges arranged as a worm conveyer 
 to force the cuttings back from the face. The rear end of this 
 tube carries two small, pivoted, self-loading buckets or skips, 
 which are filled at the lower part of their travel and emptied 
 at the upper where they are inverted by a trip, discharging 
 their contents on an endless rubber belt which carries the cuttings 
 rearward and drops them into a car. 
 
INCIDENTAL UNDERGROUND EQUIPMENT 187 
 
 The Sigafoos tunneling machine is practically a horizontal 
 stamp mill, the stamps being thrown forward by coiled springs 
 and drawn back by a revolving cam. In practice ten heads are 
 employed and the stamps, instead of being flat, carry an equip- 
 ment of hardened steel faces designed to operate with as great a 
 cutting effect as possible. To prevent the steel from heating 
 and losing its temper, the entire face is sprayed with water, 
 which not only lowers the temperature, but allays the dust 
 and assists materially in removing the cuttings. 
 
 Although a number of experimental machines have been 
 built, all of the details of construction are not yet perfected. 
 The American Rotary TunneKng Machine Co. is now ex- 
 perimenting with an eight-foot machine near Georgetown, 
 Colorado. 
 
 One of the great obstacles encountered by legitimate in- 
 vestigators in this field has been the difficulty of obtaining funds; 
 for with the tunneling machine as well as with any other new 
 and complicated machine built to operate under difficulties 
 and strains which cannot be measured in advance, costly ex- 
 perimental work is necessary in its development and process of 
 perfection. It must be remembered that machines of the size 
 and strength to cut the entire face of the tunnel in a single opera- 
 tion are of necessity costly, and their maintenance during the 
 trial stages is extremely expensive. For this reason, success 
 can hardly be hoped for unless the inventor, or the company 
 back of him, is in a position to command very considerable 
 amounts of money. But the failure of one badly designed and 
 inadequately financed machine after another, and the sus- 
 picions which have been aroused in the minds of possible in- 
 vestors by the untruthful and flamboyant ^'literature" which 
 has been issued by too many alleged tunnel-machine companies 
 in their efforts to "work the public," have caused most people 
 to look upon machines of this kind with extreme distrust, much 
 of which is indeed just, for even a casual scrutiny of the claims 
 of many of these concerns shows clearly that they are in reaHty 
 fit subjects for investigation by the postal authorities. 
 
 The following paragraphs contain a list of patents issued 
 
188 MODERN TUNNELING 
 
 in the United States for tunneling machines in hard rock, ar- 
 ranged in the order of seniority. With each patent is given a 
 condensed description of the "objects of the invention" or the 
 '^patent claim." At the time the examination was made the 
 Patent Office was rearranging this class of inventions, and 
 therefore, although every effort was made to have the list com- 
 plete, it is possible that one or two inventions may not have been 
 included in it. 
 
 List of Tunneling Machine Patents 
 
 E. Talbot Stone-Boring Machine, U. S. Patent No. 9,774^ 
 patented June 7, 1853. 
 
 Description not available, but Patent Office drawings 
 show a machine adapted to boring a cylindrical tunnel with 
 rotating disk cutters. Two pairs of disks are used, carried 
 on a revolving head supported by a large hollow horizontal 
 shaft. This head is intended to be slowly revolved by a 
 worm-driven spur gear, and through the hollow shaft is 
 carried a jointed connecting rod by means of which the 
 cutting disks are traversed across the face of the revolving 
 head so that all portions of the heading are subject to the 
 cutting action of the disks. The machine is quite crude 
 in its design, and it is plainly apparent that it had not 
 passed the experimental stage. 
 
 Charles Wilson, Springfield, Massachusetts, U. S. Patent 
 No. 14,483, patented March 18, 1856. 
 
 Claims: Invention "consists in so arranging, constructing, 
 and fitting the parts of a revolving cutter wheel that the 
 cutters are gradually forced forward with a very slow motion, 
 while the wheel carrying the rolling disks, or cutters, receives 
 a compound motion, the one motion a revolution on its 
 shaft, which is at right angles to the axis of the tunnel being 
 bored, and the other motion a gradual rotation of said 
 cutter-wheel and parts carrying the same on the fine of axis, 
 or general direction of said tunnel. These two motions, in 
 addition to the very slow forward feeding motion produced 
 
INCIDENTAL UNDERGROUND EQUIPMENT 189 
 
 by the rolling cutters, causes the gradual removal of the rock, 
 or other substance, at the semi-spherical end of the tunnel." 
 Charles Wilson, Springfield, Massachusetts, U. S. Patent 
 No. 17,650, patented June 23, 1857. 
 
 ''The plan adopted in this method of tunneling is to 
 bore a single ring and a central hole. By means of a charge 
 of gunpowder, afterward placed in the central hole and ex- 
 ploded, the rock intervening between the central hole and 
 circular groove is detached." 
 
 Claim: ''Forming grooves in stone, or other mineral 
 substances, by means of rolling disk cutters on axes set in 
 alternate directions and arranging a series of rolling disk 
 cutters revolving in such a manner as to cut a deep annular 
 groove into the rock." 
 F. E. B. Beaumont, England (English Patent No. 1,904), 
 patented July 30, 1864. 
 I "Gang of cutters; supplementary valve; tappet and 
 
 Ij annular projection; hand feed; rotation automatic by worm 
 
 and feather." 
 Thales Lindsley, Rock Island, Illinois, U. S. Patent No. 55,514, 
 patented June 12, 1866. 
 I Machine devised, "first, to cut circular concentric channels 
 
 I in vertical planes of rock and thus form circular concentric 
 
 I rings in the heading; second, to disrupt these concentric 
 
 rings of rock and thus prepare them for removal; third, to 
 detach the fragments of the disrupted rings and deliver them 
 for transportation," etc. 
 Edward M. Troth, New York, New York, U. S. Patent No. 
 66,422, patented July 2, 1867. 
 
 A reciprocating head carrying a number of drills arranged 
 to vary the stroke. This head turns slowly, cutting a 
 number of concentric grooves in the face. The rings of rock 
 remaining behind are broken off by wedges. 
 Richard C. M. Lovell, Covington, Kentucky, U. S. Patent 
 No. 67,323, patented July 30, 1867. 
 
 This is a chipping machine, the chisels being operated 
 alternately by their respective engines, the leading chisel 
 
190 MODERN TUNNELING 
 
 cutting half the depth and the following one completing 
 the cut, and being reversed and changed in cutting back; 
 the motor is operated by either steam or compressed air 
 conducted to the engine by pipes from the exterior of the 
 shaft or drift, etc. 
 
 John D. Brunton, London, England, U. S. Patent No. 80,056, 
 patented July 21, 1868. 
 
 Patent claim: "The use of an apparatus for excavating 
 tunnels, galleries, or adits, wherein one or more cutting 
 disks are caused to revolve on their axis, or axes, such 
 axis, or axes, revolving around a center which also revolves 
 around another fixed center." 
 
 Edward Alfred Cooper, Westminster, England (English patent 
 No. 1,612), patented June 20, 1871. 
 
 Claim: ''The cutting of grooves, or chases, in stone or 
 rock by the action of a series of chisels or jumpers, each 
 worked by compressed air or steam acting in a separate 
 cylinder and moved along its groove or chase, and all»advance 
 as the grooves or chases are deepened." 
 
 Allexey W. Von Schmidt, San Francisco, CaKfornia, U. S. 
 Patent No. 127,125, patented May 21, 1872. 
 
 Claim: "In combination with a cyHndrical drumhead 
 arranged to rotate on its axis, a series of rotary diamond- 
 pointed drills mounted on the periphery of the drumhead." 
 By this means an annular groove the size of the tunnel is 
 cut in the rock to a depth of about two feet, when the 
 machine is backed out and the central core removed by 
 blasting. These diamond-pointed drills are cooled by a 
 stream of water sprayed into the annular groove. 
 
 Frederick Bernard Doering, Trefriw, North Wales, England, 
 English Patent No. 4,160, September 27, 1881. 
 
 "A tunnehng machine on which is mounted by means of 
 brackets, or otherwise, a series of rock-boring machines 
 or drills, say four, more or less, around a central boring 
 machine or drill, each carried at the end of an arm, prefer- 
 ably consisting of a strong steel tube. This steel tube, 
 which is accurately turned on its outer face, is supported 
 
INCIDENTAL UNDERGROUND EQUIPMENT 191 
 
 by one, two, or more accurately bored castings which are 
 carried on a strong framework mounted on wheels. The 
 boring machines or drills may be fitted with cross-heads 
 carrying chisels, or they may have a single chisel attached 
 with or without a cross-head. The drills strike and rotate 
 a portion of the circle with each stroke in the usual manner." 
 
 Thomas English, Hawley, Kent, England, U. S. Patent No. 
 307,278, patented October 28, 1884. 
 
 "Invention relates to a machine for boring a circular 
 tunnel by means of a boring head which consists of a strong 
 boss having two arms projecting radially from it, each arm 
 having a number of cutters fixed in front of it, each cutter 
 being a bevel-edge disk fixed to the holder so that it can 
 be turned partly around when one part becomes blunted. 
 Jets of water from small nozzles play on the cutters to 
 prevent them from heating." 
 
 Henry S. Craven, Irvington, New York, U. S. Patent No. 
 307,379, patented October 28, 1884. 
 
 This patent "relates to that class of machines which 
 employ a drill or combination of drills constructed to cut 
 or bore an annular groove the full size of the contemplated 
 tunnel, leaving a cylindrical mass of rock at the end of the 
 bore to be blasted out by a charge of explosives introduced 
 in the central hole." 
 
 Robert Dalzell, Waddington, New York, U. S. Patent No. 
 332,592, patented December 15, 1885. 
 
 Claims: "In a rock-drilling machine the combination 
 of a suitable frame carrying a rotating or oscillating tubular 
 shaft having near its forward end a series of laterally radiat- 
 ing arms, having adjustably screwed to their outer ends 
 one or more reciprocating or rotary drills with mechanism 
 for operating the same both simultaneously or separately." 
 
 F. 0. Brown, New York, New York, U. S. Patent No. 340,759, 
 patented April 27, 1886. 
 
 Patent claims: "A shell made in the shape and size of 
 the required tunnel, provided with an air-tight cross parti- 
 tion having manholes closed by plates in the tube, a 
 
192 MODERN TUNNELING 
 
 central worm-boring mechanism, and a steam pipe passing 
 through the airtight partition in the tube." 
 Reginald Stanley, Nuneaton, England, U. S. Patent No. 
 414,893, patented November 12, 1889. 
 
 Claim: "In a tunneling machine the combination of a 
 frame carried on central tandem wheels working on the 
 floor of the tunnel, a central threaded shaft carried by said 
 frame and driving wheel working on said shaft, radial arms 
 and horizontal arms on one end of said shaft and provided 
 with cutters and scrapers depended for forming an annular 
 groove around the face of the tunnel," etc. 
 
 Reginald Stanley afterward devised numerous improve- 
 ments on this machine which were patented June 14, 1892; 
 May 9, 1893; August 29, 1893; August 11, 1894; and Febru- 
 ary 16, 1897. 
 Frederick Dunschede, Essenberg, Germany, U. S. Patent 
 No. 507,891, patented October 31, 1893. 
 
 "Invention consists of an apparatus by means of which 
 an annular groove and a central blasting hole are bored into 
 the rock so that, on inserting into said central hole an 
 explosive and exploding the same therein, the rock or other 
 material forming the core between the central blasting 
 hole and the circumferential cut will be smashed and 
 blown away." 
 Jonas L. Mitchell, Chicago, Illinois, U. S. Patent No. 537,899, 
 patented April 23, 1895. 
 
 Claim: "In a tunneling machine, the combination of a 
 tunnel-forming cutter consisting of a tubular cutter head, 
 a main frame having guides therein, and of a diameter 
 adequate to enter the tunnel formed by the cutter, a carriage 
 sliding in said guides and lying in the transverse planes 
 of the bed," etc. 
 Harry Byrne, Chicago, Illinois, U. S. Patent No. 545,675, 
 patented Spetember 3, 1895. 
 
 Patent claims: "In a rock- tunneling apparatus, the 
 combination of an upright supporting frame, having a 
 marginal frame corresponding with that of the tunnel and a 
 
INCIDENTAL UNDERGROUND EQUIPMENT 193 
 
 series of traveling percussion channeling machines arranged 
 to travel on the outer surface of said frame; a flexible 
 connection attaching the entire series of machines together 
 and causing same to travel in unison, and means for operating 
 said flexible connection." 
 
 Archie LE Bailey, Philipsburg, Pennsylvania, U. S. Patent 
 No. 640,621, patented January 2, 1900. 
 
 Patent claims: "In a mining machine, the combination 
 with a bed, the carriage, two reciprocating cutters, each 
 forming a separate curve, and means for simultaneously 
 reciprocating said cutters in opposite directions, whereby 
 they balance the machine laterally, of a drill mounted on 
 each side of the carriage and forming an aperture at the 
 end of the kerf." 
 
 John E. Ennis, Chicago, Illinois, U. S. Patent No. 690,137, 
 patented December 31, 1901. 
 
 Claims: "A tunneling machine having a digger mechanism, 
 including a plow movable in a circular sweep, means for 
 imparting said sweep movement to the plow, and simul- 
 taneously forcing forward in a spiral direction, and means 
 for automatically shifting movements of the plow and 
 causing it to travel from the perimeter of the machine 
 inward, or from the axis of the machine outward, during 
 its sweep movement." 
 
 Pedro Unanue, City of Mexico, Mexico, U. S. Patent No. 
 732,326, patented June 30, 1903. 
 
 Claims: ''In a tunnehng machine, the combination of 
 a ram-head provided with a series of rammers having their 
 rods incHned to the ram-head in and toward the direction 
 of revolution of the ram-head, together with an inclination 
 from the axis of revolution of the ram-head, and means for 
 rotating and feeding said ram-head," etc. 
 
 John Prue Karns, Cripple Creek, Colorado, U. S. Patent No. 
 744,763, patented November 24, 1903. 
 
 Claims: "The combination with a tunneling machine of 
 a revoluble drill support comprising a plurality of ring 
 and spoke members, each having grooved forward faces. 
 
194 MODERN TUNNELING 
 
 drills, or cutters, having their base portions adapted to said 
 grooves, each of the drills or cutters having a rearwardly 
 projecting stem extending through an opening in the support, 
 and means for locking said stems to said support." 
 
 Other patents issued to Mr. Karns on this machine are 
 as follows: 
 
 No. 957,687, May 10, 1910, for improvements in machine 
 structure, particularly for the front bearing of the cutter- 
 head shaft. 
 
 No. 977,955, December 6, 19 10, for improvements in the 
 cutter-head tool-carrying spider. 
 
 No. 1,023,654, April 16, 191 2, improvements on the 
 structural form and mechanical arrangement of said machine. 
 Chester T. Drake, Chicago, Illinois, U. S. Patent No. 747,869, 
 patented December 22, 1903. 
 
 Claims: ''In an excavating machine, the combination of 
 a shaft provided on its end with a cutter, mechanism for 
 revolving the shaft, mechanism for giving shaft and cutter 
 an orbital revolution, and adjustable mechanism for varying 
 orbit described." 
 Alva D. Lee, of Brookline, and Francis J. E. Nelson, Jr,, of 
 East Boston, Massachusetts, U. S. Patent No. 874,603, 
 patented December 24, 1907. 
 
 Claim: ''In a rock-drilling machine, the combination 
 of an annular face plate provided with a pluraKty of de- 
 pressions in its face, means for rotating said plate and a 
 plurality of cutters secured in said depressions, with their 
 axes radial to the axis of said plate and at different dis- 
 tances from said center, thereby effecting in the revolution of 
 said plate a cutting from the central opening to the outer 
 periphery of said plate," etc. 
 Silas A. Knowles and Walter E. Carr, Idaho Springs, 
 Colorado, U. S. Patent No. 875,082, patented December 31, 
 1907. 
 
 Claim: "In a timneling machine, a narrow rectangular 
 reciprocating cutter head of the full height of the tunnel 
 to be driven, provided with vertically and parallely ar- 
 
INCIDENTAL UNDERGROUND EQUIPMENT 195 
 
 ranged rows of chisel-shaped drill bits having angular 
 bases, means for securing said drill bits to said cutter 
 head, said cutter head having slideway slots therethrough, 
 a supporting guide arm having forward terminal arms 
 which project into slideway slots on which said cutter head 
 is reciprocally mounted," etc. 
 
 William J. Hammond, Jr., Pittsburgh, Pennsylvania, U. S. 
 Patent No. 885,044, patented April 21, 1908. 
 
 Claim: "In a tunneling machine, a rotary head having 
 a series of diametrically arranged reciprocating hammers 
 and separated from each other by distances slightly less 
 than the hammers, whereby the entire breast of the tunnel 
 may be disintegrated by the rotation of the head and the 
 reciprocation of the hammers." 
 
 George Allen Fowler, Georgetown, Colorado, U. S. Patent 
 No. 891,473, patented June 23, 1908. 
 
 "Invention is directed to the production of a pneumatic 
 mining machine for a pluraKty of thrust-actuated drills 
 adapted particularly to tunnel or driving operations in 
 which the drills are carried by a pivoted block, which, in 
 its cutting operations, is automatically caused to travel 
 back and forth, reducing the wall of the breast to an arc 
 of a circle to give clearance to the sides of the machine." 
 
 Olan S. Proctor, Denver, Colorado, U. S. Patent No. 900,950, 
 patented October 13, 1908. Assigned to the Terry, Tench 
 & Proctor TunneHng Machine Company. 
 
 Claim: "In a rotary tunnehng machine, the combination 
 of a supporting frame, a tubular shaft revolubly mounted 
 on said frame, a rotary cutter head secured to one end of 
 said tubular shaft, a pluraKty of operative rock-drilling 
 engines arranged to cut the breast area of a circular tunnel, 
 said cutter head having ports leading from said tubular 
 shaft to said rock-drilling engines, means, including a 
 motor, for rotating said tubular shaft and cutter head, 
 means for connecting the opposite end of said tubular 
 shaft to a supply of suitable drilKng engine actuating fluid, 
 a muck-catching cylinder on said supporting frame sur- 
 
196 MODERN TUNNELING 
 
 rounding said cutter head, and means for conveying the 
 muck from said cutter head and cylinder to the opposite 
 end of said supporting frame from said cutter head." 
 
 Russell B. Sigafoos, Denver, Colorado, U. S. Patent No. 
 901,392, patented October 20, 1908. 
 
 ''The objects of this invention are: First, to provide 
 a rotary tunnel machine adapted to automatically feed 
 into the breast of a tunnel as fast as it cuts into rock, and 
 to automatically feed forward and backward. Second, 
 to equip it with a plurality of reciprocating cutter heads, 
 each provided with a plurality of independent rock-cutting 
 lips. Third, to provide a plurality of reciprocating rotary 
 cutter heads adapted to strike spirally twisting blows. 
 Fourth, to provide discharge jets of water throughout the 
 circumference of the rock-cutting area. Fifth, to provide 
 the machine with a plurality of independent rotating and 
 spirally striking cutter heads arranged and adapted to 
 permit any one or predetermined number of said cutter 
 heads to be adjusted to strike blows at differential force. 
 Sixth, to provide an automatic adjustable feeding 
 mechanism that will feed the machine forward in any 
 predetermined curved path as it cuts its way into the 
 rock." 
 
 Joseph Retallack, Denver, Colorado, U. S. Patent No. 906,741, 
 patented December 15, 1908. 
 
 This machine is especially designed for driving tunnels 
 or drifts through rock, and it comprises, in general, ''a 
 revoluble tool head which may be idly rotated or fed forward 
 or backward at pleasure. The head carries a large number 
 of independently actuated rock drills which attack the face 
 of the rock as the head is rotated. The head is carried by 
 a threaded shaft that is hollow from end to end and serves 
 as a duct for the passage of the air or other fluid to actuate 
 the drills." Provision is also made for introducing water 
 at the drilling point and for automatically gathering up and 
 conveying away the fragments of rock as the tunneling 
 operation proceeds. 
 
INCIDENTAL UNDERGROUND EQUIPMENT 197 
 
 Charles A. Case, New York, New York, U. S. Patent No. 
 910,500, patented June 28, 1909. 
 
 ''This invention relates to means for disintegrating rock 
 and other materials by suddenly changing their temper- 
 ature, and then by concussion, hammering, or rasping, 
 effecting their disintegration." 
 
 Edward T. Terry, New York, New York, U. S. Patent No. 
 917,974, patented April 13, 1909. 
 
 ''The primary object of this machine is to cut a tunnel 
 through rock without the necessity of blasting. '^ . . . 
 "The drill head consists of nine gangs of drills of such size 
 and location that in their rotary motion they cover substan- 
 tially the whole face of the tunnel, while the cutting action 
 is produced by a rapid reciprocation of the separate heads." 
 
 Louis Franklin Sleade, Denver, Colorado, U. S. Patent No. 
 945,623, patented January 4, 1910. 
 
 Claim: '^A tunneling machine comprising a revoluble 
 cutter head, an electric motor for rotating said cutter 
 head, an internal combustion engine for maintaining a 
 reciprocating motion of the said cutter head in a forward 
 direction, and means for connecting said electric motor 
 with said internal combustion engine, imparting a returning 
 movement to the cutter head." 
 
 George R. Bennett, Denver, Colorado, U. S. Patent No. 
 958,952, patented May 24, 1910. 
 
 Claim: "A tunneling machine comprising, in combination 
 , with a suitable support, a battery of rock drills, means for 
 presenting said battery to a working face, means for pro- 
 jecting said drills of said battery in said face, and means 
 for automatically moving said battery laterally after each 
 projection of said drills. 
 
 "A tunneling machine comprising, in combination with a 
 suitable support, a battery of rock drills, means for im- 
 parting a series of rectilinear movements to said battery, 
 and means for automatically performing said movements, 
 in progressive cycles, each cycle comprising a longitudinal, 
 lateral, and vertical movement." 
 
198 MODERN TUNNELING 
 
 William R. Collins, Georgetown, Colorado, U. S. Patent 
 No. 973,107, patented October 18, 1910. 
 
 ^'Invention provides a machine having a cutting head 
 which will leave an uncut rock core, thereby saving a certain 
 amount of expensive rock drilling, and further to provide 
 an improved arrangement of chipping or cutting drills 
 whereby the recoil of the drills will be counteracted and 
 the cutting head balanced." 
 
 On August 8, 191 1, Mr. Collins obtained U. S. Patent 
 No. 1,000,075 for certain mechanical improvements on 
 this machine. 
 Aron G. Seberg and Edwin G. Seberg, Racine, Wisconsin, 
 U. S. Patent No. 976,703, patented November 22, 1910. 
 
 Claim: "In a drilHng machine, the combination with a 
 wheel, of shields yieldingly mounted in said wheel, drills 
 slidably mounted in said shields, means to force said drills 
 beyond the outer ends of said shields, and means to rotate 
 said wheel. 
 
 ''In a drilHng machine, the combination with a rotating 
 sleeve, of a wheel for said sleeve adapted to rotate there- 
 with, a supporting axle around which said wheel revolves, 
 means to rotate said wheel, a plurality of drills carried 
 by said wheel, and rotating means adapted to force said 
 drills outwardly and enter the same into an object." 
 Franklin M. Iler, Denver, Colorado, U. S. Patent No. 986,293, 
 patented March 7, 191 1. 
 
 Claim: ''In a rock-driUing machine, the combination 
 with a suitable frame, of a hollow rotatable shaft, carried 
 by said frame, divergent, rigid, hollow arm constituting a 
 continuation of said hollow shaft and projecting therefrom 
 at an angle, means for supporting fluid-operated drills by 
 said arms in various adjusted positions at different points, 
 and means for connecting the inlet ports of said drills with 
 the interior of said arms." 
 
 Mr. Iler has also patented, for use with his machine, a 
 special drill bit which consists of a hollow tube about 7 inches 
 in length, 3^ inches external diameter, and i^ inches 
 
INCIDENTAL UNDERGROUND EQUIPMENT 199 
 
 internal diameter. This tube is of cast iron or soft steel, and 
 in it are embedded a number of rods about yi. inch in diam- 
 eter of exceedingly hard alloy steel. The soft material 
 wears away much more rapidly than the hard, thus forming 
 a chipping tool which can be used without sharpening until 
 it is worn out. 
 George A. Fowler, Denver, Colorado, U. S. Patent No. 996,842, 
 patented July 4, 191 1. 
 
 Invention ''provides a suitable frame mounted on wheels, 
 said frame being provided at its forward end with a drill 
 head provided with a plurality of fluid-operated drills, 
 said head being pivo tally mounted on the frame and adapted 
 to swing from side to side in the arc of a circle, upon a 
 vertical axis, means being provided for admitting fluid 
 under pressure to said drills, and for automatically swinging 
 said head from side to side and for manually moving said 
 machine forward against the breast of the tunnel." 
 Robert Te^iple, Denver, Colorado, U. S. Patent No. 1,001,903, 
 patented August 29, 191 1. 
 
 ''Invention provides a machine for cutting tunnels 
 through rock or other materials, the cutter of which will 
 be reciprocating and simultaneously moved transversely 
 to its direction of reciprocation, thereby cutting a tunnel 
 of greater cross-section than the machine." 
 
 Claim: "In a rock-cutting apparatus, the combination 
 with a transversely extending head, of a plurahty of cutters 
 mounted thereon, means for reciprocating said head, and 
 means for simultaneously moving the same in complete 
 cycles over a substantially circular path adjacent to the 
 surface worked upon and eccentric to the said head." 
 John Nels Back, Seattle, Washington, U. S. Patent No. 
 1,011,712, patented December 12, 191 1. 
 
 Claim: "A tunnel-excavating machine comprising an 
 outer frame, traction wheels under said outer frame, an 
 inner frame movable with relation to said outer frame, a 
 head beam, a carrier slidably mounted upon said head 
 beam, a shovel mounted in said carrier, means for sliding the 
 
200 MODERN TUNNELING " 
 
 carrier, means for moving said inner frame, and toggle- 
 joint braces to prevent movement of said outer 
 frame." 
 
 Edward O'Toole, Gary, West Virginia, U. S. Patent No. 
 1,011,955, patented December 19, 191 1. 
 
 Claim: "In an excavating machine, the combination of 
 a frame, a pair of rotary pick-armed cutter heads mounted 
 on parallel shafts therein, and geared to rotate in unison 
 from a common source of power, said frame movable upon 
 a bed-plate, and in movement causing the shafts of said 
 cutter heads to move transversely in their common plane, 
 said bed-plate provided with a passage for excavated 
 material, and with an intake extending beneath the path 
 of movement of said cutter heads." 
 
 Henry F. Sutton, Salt Lake City, Utah, U. S. Patent No. 
 1,025,029, patented April 30, 1912. 
 
 "Object of invention is to subject the rock alternately 
 to the action of opposite extremes of temperature, it having 
 been found that when rock is first heated and then sud- 
 denly chilled it becomes softened or partially disintegrated 
 so as to be easily removed by hand or by pneumatic tools 
 or the like." 
 
 Claim: "Apparatus for tunneling rock, including a 
 hollow head having a mixing chamber therein, said head 
 having a working face formed with a plurahty of minute 
 apertures, means for pivotally supporting the head close 
 to the surface to be acted upon, means for directing fuel 
 into the head, valves for controlling the passage of fuel 
 through said means, and means for directing air under 
 pressure into the head." 
 
 Adolph F. Walther, Oakland, California, U. S. Patent No. 
 1,026,335, patented May 14, 1912. 
 
 Claim: "A tunneling apparatus comprising a plurality 
 of main frames, detachable braced supports for holding said 
 frames in a tunnel, a frame movable longitudinally in said 
 plurahty of frames, a rotary shaft and head mounted in 
 said frame, radial bars provided with cutters mounted 
 
INCIDENTAL UNDERGROUND EQUIPMENT 201 
 
 on said rotary head, and mechanism for operating said 
 rotary head and cutter bars." 
 
 L. H. Rogers, New York, New York, U. S. Patent No. 1,039,809, 
 patented October i, 191 2. 
 
 Claim: "The combination of a central frame, a hollow 
 shaft journaled in the frame, means to conduct a fluid to 
 the interior of said shaft, a front head fastened to said 
 shaft, grinding wheels journaled on said head, motors 
 connected to the wheels carried on the head, means to 
 conduct the fluid from said shaft to said motors, a rear 
 frame slidably connected to the shaft, a cylinder encircling 
 said shaft and fastened to the rear frame, a piston in the 
 cyHnder connected to said shaft, and means to lead a 
 compressed fluid on either side of the piston." 
 
 W. F. WiTTiCH, Erie, Pennsylvania, U. S. Patent No. 1,043,185, 
 patented November 5, 191 2. 
 
 Invention utilizes "a rotating head in which is mounted 
 a series of cutters actuated, preferably, independent of 
 the head, so that the head may be advanced slowly or 
 rapidly, depending on the material being operated upon, 
 and the cutters given a speed which will assure the greatest 
 efficiency. In the preferred form of the machine, also, 
 the head is separated from the driving parts of the mechan- 
 isms, so that the machine may be utiHzed and rapidly 
 advanced where there is considerable leakage through the 
 walls. The invention also contemplates a suitable mount- 
 ing, or frame, for carrying the working parts, taking away 
 the muck, and driving the several parts." 
 
 ILLUMINATION 
 
 With few exceptions, illumination for tunnels and adits in 
 the United States at the present time is furnished by electricity, 
 acetylene gas, or candles. The smoky open-flame miner's 
 oil-lamp is occasionally used in tunnels situated in the 
 coal-mining districts, and, of course, under conditions which 
 prohibit the use of an open flame, safety lamps must be em- 
 ployed. When acetylene gas is employed it is usually generated 
 
202 
 
 MODERN TUNNELING 
 
 in portable lamps, but during the work on the water conduit 
 for Washington, D. C, in 1899, this gas was manufactured at 
 a plant on the surface and carried by pipes underground where 
 it was burned in jets at regular intervals. Coal gas was simi- 
 larly employed at the Mt. Cenis tunnel, which was started in 
 1857 and opened for traffic in 1872. The following table, how- 
 ever, shows the present practice with regard to means of illumi- 
 nation. 
 
 MEANS OF ILLUMINATION AT VARIOUS TUNNELS 
 
 Tunnels 
 
 Illumination 
 
 Buffalo Water 
 
 Electric lamps. 
 
 Carter 
 
 Acetylene lamps and candles. 
 
 Catskill Aqueduct 
 
 Central 
 
 Electric lamps at intervals and usually a cluster 
 
 of lamps in the headings. 
 Acetylene lamps. 
 
 Fort Williams 
 
 Electric lamps (16 c.p.) every 75 feet and one 
 
 32 c.p. in heading 
 Candles. 
 
 Gold Links 
 
 Gunnison 
 
 Electric lamps. Cluster in heading and candles. 
 
 Electric lamps. 
 
 Acetylene lamps for drillers, candles for muckers. 
 
 Miners' oil lamps and safety lamps. 
 
 Electric lamps and candles. 
 
 Acetylene lamps. 
 
 Joker 
 
 Laramie- Poudre 
 
 Lausanne 
 
 Los Angeles Aqueduct .... 
 Lucania 
 
 Marshall-Russell 
 
 Acetylene lamps. 
 
 Pviission 
 
 Electric lamps every 200 feet, cluster in head- 
 
 Newhouse 
 
 ing, candles. 
 Electric lamps at stations, acetylene lamps in 
 
 Nisqually 
 
 heading. 
 Electric lamps every 75 feet, cluster in heading. 
 
 Ophelia 
 
 Candles. 
 
 Raymond 
 
 Electric lamps every 200 feet, cluster in heading. 
 
 Acetylene lamps. 
 
 Electric lamps. 
 
 Electric lamps every 200 feet and candles. 
 
 Acetylene lamps. 
 
 Electric lamps in heading, candles. 
 
 Electric lamps every 135 feet, cluster in heading. 
 
 Electric lamp at switch, acetylene lamps in 
 
 Rawley 
 
 Roosevelt 
 
 Siwatch 
 
 Snake Creek 
 
 Stilwell 
 
 Strawberry 
 
 Utah Metals 
 
 Yak 
 
 heading. 
 Electric lamps. 
 
 
 
 Neither candles nor the open-flame oil lamp can be recom- 
 mended as a means of Kghting a tunnel or adit during con- 
 struction. Practically everything that can be said in their favor 
 is that they require a much smaller initial outlay than electricity 
 
INCIDENTAL UNDERGROUND EQUIPMENT 203 
 
 or acetylene, yet they are more expensive per unit of light than 
 either acetylene or electricity, consume a greater amount of 
 oxygen, and give off a correspondingly greater amount of noxious 
 gases. Candles not only do not give enough Kght, but what they 
 do supply is flickering and unsteady unless there are no drafts, 
 and since they are quickly extinguished by the exhaust blasts 
 from air drills they cannot be placed to Kght properly the work 
 of the drillers; hence the efficiency of a high-priced drillman 
 is greatly reduced. Candles are often wasted or dropped into 
 the muck-pile, an item of loss which may amount to a consider- 
 able sum in the long run. The open-flame oil lamp cannot be 
 prevented from giving off soot and smoke which obscure and dim 
 the Hght thrown on the work, while the soot collecting in the 
 miner's throat and lungs irritates the mucous membranes and 
 renders them easily susceptible to disease. 
 
 Electric incandescent lamps possess a number of advantages 
 for tunnel work. They give a brilliant and steady Hght — one 
 that is not affected by drafts and neither pollutes the air with 
 soot nor \dtiates it by consuming the oxygen. By combining 
 several of them in a cluster, plenty of light in the heading is 
 obtained for the drillers and shovelers, tending toward efi&ciency. 
 To offset this advantage, however, the fact remains that unless 
 they are used in connection with electric locomotives, drills, 
 or similar machinery, the cost of lamp installation is almost 
 prohibitive; even with the electric appKances in use the extra 
 wiring and the lamps themselves are expensive, while the latter 
 are subject to considerable loss through breakage. Electric 
 hghts are also at a disadvantage because they are not easily 
 portable and the removal and replacement of bulbs and wires 
 in the heading before and after blasting compHcate an already 
 involved situation. Moreover, this means of illumination is 
 uncertain, especially in wet tunnels, because the chance oc- 
 currence of a short circuit through moisture, accident, or care- 
 lessness throws the entire work in darkness, and if other means 
 of lighting are not at hand, stops all work until the trouble 
 can be remedied. Again, whereas the use of electricity under 
 ground is always attended with some danger, this is especially 
 
204 MODERN TUNNELING 
 
 true in the case of lighting appliances; the supposition is that 
 the wires are protected, but the rough usage to which they are 
 subjected soon destroys insulation, rendering persons who 
 handle them (as they must do frequently) subject to severe 
 shock. 
 
 One is tempted to say that the ideal means of tunnel illu- 
 mination is found in the portable acetylene lamp, combining 
 as it does the advantages of other illuminants while avoiding 
 most of their defects. It may be obtained on the market 
 to-day in a number of different designs and sizes adapted for 
 practically every kind of work; the one most generally observed 
 at the tunnels visited was about the size of an ordinary can 
 of fruit and capable of burning for from eight to ten hours on one 
 charge of carbide and water. Although too large for use on a 
 cap, it was provided with a hook so that it could be suspended 
 from any convenient place. Lamps suitable for wearing on an 
 ordinary miner's cap are obtainable and these lights will burn 
 for two or three hours without recharging, an operation which 
 can be done easily in two or three minutes. The initial ex- 
 pense of an acetylene lamp is not high and it furnishes the 
 brightest known artificial Hght used for underground work, 
 with the possible exception of the electric arc, consuming the 
 while only one-fifth as much oxygen as candles. The lamps are 
 ordinarily provided with a reflector, which not only concentrates 
 the light upon the work where it is needed, but shields the flame 
 from drafts so that it will burn steadily unless placed directly 
 in front of the exhaust from an air drill. Extensive use in 
 some of the larger mining companies in this country has shown 
 that the cost of the carbide is much less than either oil or candles 
 and the use of acetylene lamps practically cuts the cost of light 
 in half. At the Saginaw mine, Menominee Range, Michigan, 
 the cost is reported as only two cents per shift of ten hours. 
 Such lamps require practically no attention, are completely 
 portable, and are not subject to breakage as are incandescent 
 lamps. By giving the workman plenty of light his efficiency 
 is not only increased, but he is better able to see and guard 
 against the dangers of underground work, such as an insecure 
 
INCIDENTAL UNDERGROUND EQUIPMENT 205 
 
 roof, an unexploded stick of dynamite in the muck-pile, or any 
 other of the many dangers to which he is at all times exposed. 
 
 TELEPHONES 
 
 Although it has been repeatedly stated in newspaper's, 
 engineering periodicals, and even by State legislatures, that 
 every mine should be provided with a telephone system, the 
 importance of telephones in tunnel work cannot be too often 
 reiterated, not alone because of the greater safety they insure, 
 but on the ground of efficiency and economy as well. The 
 sources of accident in tunnel work are too numerous to mention 
 — falls of roof, caves, premature or delayed explosions, water, 
 and noxious gases being some of the more common. When an 
 accident occurs in a tunnel that is equipped with a telephone 
 system, not only can assistance be summoned quickly, but 
 provision can be made beforehand for the care of injured men 
 when they reach the surface; if professional help can be sum- 
 moned 'and due preparation made while the men are still on the 
 way from the heading, invaluable time is saved; for there have been, 
 and doubtless will be in the future, many such instances where 
 prompt medical attention has decided the question of life or 
 death. Then, too, failure to obtain a proper round of holes 
 in the given time, difficulty in blasting them to the full depth, 
 or any of the many problems that commonly arise in tunnel- 
 driving, call for a decision on the part of the foreman as to the 
 method of procedure. Ordinarily the man entrusted with this 
 position is capable of meeting such conditions as they arise, 
 but it stands to reason that the work of the shift will be more 
 efficient if the foreman can be in touch constantly with the 
 mine superintendent and when in doubt receive suggestions and 
 advice from the more experienced man's better judgment. 
 Delay can be avoided in good part if the tunnel is equipped 
 with a telephone, because the necessity that involves sending 
 for fresh materials, tools, powder, etc., can either be foreseen 
 and provided for promptly from the outside without the loss of 
 a man from the heading crew, or when unexpected emergencies 
 arise, only half the usual time is necessary to obtain the needed 
 
206 MODERN TUNNELING 
 
 supplies. It does not require many suspensions of work by the 
 men in the heading, waiting while one of their number walks to 
 the portal and back, to pay for the entire installation of such 
 equipment. Causes of accident and delay cannot always be 
 foreseen, it is true, but they can bo met promptly and further 
 damage to men and property can be prevented by the use of the 
 telephone; that these advantages are appreciated is shown by 
 the fact that a majority of the tunnels and adits examined 
 in the field were so equipped. 
 
 The type of telephone-equipment should be carefully chosen, 
 because every telephone is not suited for underground use. 
 For use in tunnels it must be water-proof, dust-proof, and, since 
 to be useful it must be placed as near the heading as possible, 
 it must be designed to withstand the frequently recurring con- 
 cussions of blasting. The most successful types of mine tele- 
 phones meet these conditions by placing the mechanism in a 
 heavy metal casing, in such a way that the essential parts shall 
 be instantly accessible upon opening the outer door, but shall be 
 tightly sealed when it is closed. The more dehcate mechanism 
 is guarded further by an inner door, also of iron, and the wires 
 are protected so that water cannot enter the casing. The bells 
 must necessarily be placed outside, but they are protected by a 
 metal hood, which, however, does not prevent their being heard 
 for a considerable distance. 
 
 The telephone line for tunnel work is somewhat simpler than 
 a similar line on the surface, because no poles are required and the 
 wires can be strung from ordinary glass or china insulators 
 fastened to plugs in the roof or to Kght cross-timbers. Common 
 bare iron wire can be used, but much better results are obtain- 
 able where rubber-covered wire is employed, and for the same 
 reason a full metallic circuit is desirable, although the telephone 
 may be operated with only one wire by using a ground connec- 
 tion for the return. But since the usefulness of a telephone 
 system is measured entirely by its rehabihty, the best is in the 
 end by far the cheapest. 
 
 It is not desirable to place the telephone nearer the heading 
 than several hundred feet, not only because of the concussion, 
 
INCIDENTAL UNDERGROUND EQUIPMENT 207 
 
 but also because of the noise. While this arrangement is con- 
 venient for any one in the tunnel desiring to call up the ofhce, 
 it makes it more difficult and sometimes even impossible to secure 
 any response to a call originating on the surface. To obviate 
 this difficulty, the use of an extension loud-ringing call-bell 
 is recommended, which, if placed behind a jutting rock or in some 
 similar protected position, apprises the foreman at the heading 
 instantly of any call at the telephone. Such a bell should be 
 connected with the telephone circuit by a flexible insulated 
 cable mounted upon a reel in such a way that the bell may be 
 advanced regularly to keep pace with the tunnel progress and 
 need never be further than two hundred feet from the heading. 
 When the cable is extended to full length, perhaps i,ooo feet, 
 the telephone should be advanced to a point as near the heading 
 as possible and the extra cable reeled up once more. 
 
 INCIDENTALS 
 
 Among the many devices used to save time and promote 
 efficiency underground, those of the simplest are the hose sup- 
 porter and the drill rack, both of which can be made readily 
 by any tunnel blacksmith. The former consists merely of two 
 telescoping pieces of iron pipe, the length of each being about 
 three-fourths of the width of the tunnel. In operation the hose 
 is placed over the pipes, which are then extended until their 
 pointed ends fit into convenient niches on either side of the 
 tunnel near the roof; the pipes are clamped into position firmly 
 by a threaded key which is provided for this purpose. By 
 using two or three of these spreaders the hose are kept clear 
 of the shoveler, who is thus saved no little trouble and annoy- 
 ance and is able to work to better advantage. The latter device 
 is simply a rack for separating different lengths of drill steel. 
 A satisfactory form consists of an A frame made of 4-inch by 
 4-inch timbers, into which iron pegs are driven at convenient 
 intervals. The segregation of the sharp drill steels on this rack 
 enables the helper to pick out the proper length with assurance 
 and dispatch. 
 
CHAPTER XI 
 
 DRILLING METHODS 
 
 The discussion of methods of tunnel construction in this and 
 following chapters will be restricted chiefly to those employed 
 where the entire cross-section is excavated in one operation. The 
 majority of tunnels and adits driven for mining work, and many 
 tunnels intended for irrigation and water supply, are small enough 
 to be driven in this manner; but in the construction of the larger 
 undertakings, such as are required for railroad or similar purposes, 
 it is customary to drive a pilot tunnel or heading, as it is some- 
 times called — although the term is also employed to designate the 
 advancing end of any tunnel — in front of the main body of the 
 work which then consists in enlarging the smaller excavation to 
 full size. The latter method, in addition to lowering the average 
 cost of the entire work, since the process of enlarging is much 
 easier and less expensive than that of driving the heading, also 
 gives a valuable preHminary insight into the conditions which 
 must be encountered later by the main tunnel, and enables the 
 constructor to anticipate emergencies and make provision for 
 them in his plans, thus aiding to prevent accidents and loss. 
 Since, however, the scope of this bulletin is to be confined chiefly 
 to mine adits and small tunnels, a discussion of the various phases 
 of the ''heading and bench" system cannot be treated here as 
 such, although the methods used in excavating in one operation 
 the entire section of a small tunnel are in most cases applicable 
 to the driving of headings for larger tunnels. Local conditions 
 at each project necessarily modify methods to such an extent that 
 it is impossible to make a general analysis to fit all cases, but the 
 discussion is intended to bring out some of the more important 
 features of the methods employed in the various operations 
 
 208 
 
DRILLING 209 
 
 of drilling, blasting, mucking, and timbering, as they are applied 
 to the driving of mine adits and tunnels. 
 
 NUMBER OF SHIFTS 
 
 One of the chief advantages claimed for the single drill 
 shift per day method is economy. By having, the debris cleared 
 from the heading by the shoveHng crew at a separate time, the 
 drill men upon reaching the face are enabled to start immediately 
 to work setting up the machines and preparing to drill the ground; 
 there is therefore no waste of time or labor on the part of these 
 men or the helpers in shoveHng out debris preparatory to mount- 
 ing the drills. This method is especially economical when 
 vertical columns are employed. During the process of driUing 
 the operators and their helpers are not interfered with or hin- 
 dered in any way by the shoveHng crew, and there is therefore a 
 saving of that loss of motion which can hardly be prevented 
 when two crews are working simultaneously in the heading. 
 Moreover, since there is no delay in getting started, it is ordinarily 
 possible to complete the round of holes within the allotted time, 
 and even if this cannot be done plenty of extra time is available 
 without delaying the following shift. The drilHng and mucking 
 shifts can be distributed so that there is no loss of time and 
 wages while the men are waiting for smoke and gases produced 
 in blasting to be removed from the tunnel — a matter of cardinal 
 importance where the provisions for ventilation are inadequate. 
 These considerations all go to support the contention that the 
 actual excavation cost per foot of tunnel is lower with this method 
 than with other systems. 
 
 On the other hand, by employing a single drill shift the daily 
 progress in driving the tunnel is necessarily limited to the advance 
 gained from the one attack, and therefore the completion of 
 the work must inevitably be delayed. Most tunnels are prac- 
 tically worthless until completed. If their construction is not 
 pushed as rapidly as possible, not only is the capital invested in 
 the equipment, tools, etc., securely tied up much longer than 
 necessary and the cost for interest and the depreciation charges 
 proportionally increased, but there is also a delay in the reaHza- 
 
210 MODERN TUNNELING 
 
 tion of the benefits to be derived from the tunnel, which in most 
 cases is more than sufficient to offset any saving in excavation 
 cost. For example, if an adit is being driven to drain a mine, 
 the extraction of additional ore below water level is greatly 
 delayed; or if the adit is intended to lower the cost of trans- 
 porting the ore to the surface, the loss on the additional tonnage 
 handled in the old way, owing to the delay in its completion, 
 should be charged against this system of operation. Similarly 
 with an irrigation tunnel, the entire season's crops may be lost 
 from the longer time required to complete the tunnel if it is 
 excavated by the one-shift method. Then again, the cost for 
 administration and many other of the fixed charges are operative 
 during the period of construction, independent of the number 
 of shifts per day, and since the daily progress increases with 
 the additional attacks per day, the proportionate charge against 
 each foot of tunnel driven will be smallest when the greatest 
 number of shifts are employed. Although, owing to a saving 
 of the time and wages of workmen, there is an apparent economy 
 in the cost of excavation by the one-shift method, when factors 
 which reach deeper are considered, it will be found in most cases 
 that the real and ultimate cost of the tunnel will be lowered by 
 methods which make directly for speedier completion. 
 
 Greater progress is undoubtedly attained with two shifts 
 per day than with one, and if the work is properly organized 
 there need be but little added excavation cost. It is the usual 
 custom with this system to have the shovelers start work some- 
 what in advance of the drillers, and to work first at removing 
 the broken rock directly at the face to make it possible for the 
 drillers to set up their machines promptly. At some adits and 
 tunnels where two drill shifts were used, the drilling and mucking 
 took place simultaneously, the drillers themselves attending 
 to the work of clearing out for the set-up. Of these two methods 
 the former is preferable, not only because it economizes the 
 time and exertion of higher-priced men, but also because the 
 length of time when both crews are at work together in the 
 heading — and consequently the inevitable amount of inter- 
 ference and interruption — is thereby lessened. At a few places 
 
DRILLING 211 
 
 three crews of shovelers were required to remove the rock 
 broken by two driUing attacks. This system is obviously ex- 
 pensive because the cost of the extra shovelers must be charged 
 against a footage but slightly, if indeed at all, increased by their 
 efforts, and it entails, for two of the three shifts, the disadvantage 
 of simultaneous work just mentioned; it is therefore not desir- 
 able. When it must be resorted to it may usually be taken as an 
 indication that a change which would permit its discontinuance 
 should be made either in the length of the holes drilled and 
 blasted or in some of the other methods of work. 
 
 The consensus of usage at tunnels and adits where the best 
 results in driving hav^ been achieved, both in this country 
 and abroad, leads to the conclusion, however, that the three- 
 shift system of attack is the most desirable. This method has a 
 number of opponents who charge against it four chief disad- 
 vantages: (i) that time is lost on the part of the drill men in 
 getting the machines set up and in operation; (2) that the 
 greater number of men crowded in the restricted space of the 
 heading are in one another's way, and therefore unable to work 
 to the best advantage; (3) that the men must be paid for time 
 wasted in waiting for the smoke and gases produced in blasting 
 to be cleared from the heading; (4) that the system makes 
 no provision for delays due to adverse conditions. As will 
 be pointed out shortly, the time consumed in setting the 
 machines up can be made neghgible by the use of suitable 
 methods of mounting and by properly directing and blasting 
 the round of holes. A certain amount of crowding is, of 
 course, unavoidable, but it is more than ofF^et by the gain in 
 efficiency from the various incentives which can result only 
 from the three-shift method. To begin with, the shovelers have 
 constantly before them the necessity of removing the waste rock 
 before the drillers have finished their work, and are therefore 
 unconsciously speeded up by the competition. At the same 
 time the drill men endeavor to have their holes finished by the 
 time the tunnel is cleared in order that no delay may be attributed 
 directly to them. And both crews are inspired to better work by 
 the knowledge that a competing shift is to follow immediately 
 
212 MODERN TUNNELING 
 
 upon their heels, taking their places and performing similar 
 work. Then, too, after the holes are drilled the extra men 
 from the shoveHng crew are of great assistance in taking down 
 the machines and removing them, together with the mountings, 
 hose, tools, and other articles that must be taken to a place of 
 safety during blasting. As to the time wasted in clearing the 
 tunnel of smoke, if it is properly and adequately equipped with 
 ventilating apparatus this operation should require Kttle more 
 than fifteen minutes — just long enough for the men to eat their 
 lunches, which time would have to be lost at any rate. Delays 
 of course cannot always be prevented, but the men are encour- 
 aged by rivalry to reduce these to the minimum, knowing that 
 their work is to be compared with that of the shift to follow. 
 These answers to the various objections are in no sense theories, 
 but are deductions from actual observation and a study of con- 
 ditions as they existed at tunnels and adits where some of the 
 most efficient work in this country was being performed. 
 
 The ideal results of the three-shift method, to be sure, are 
 obtained only through perfected organization and good man- 
 agement, but they utterly disprove the contention that efficient 
 work is not possible under those conditions. That it is capable 
 of the most rapid progress has never been gainsaid, and with 
 proper handling the actual cost of excavation per tunnel-foot 
 need be but little if at all greater than with other methods; while, 
 as has been shown, in most cases the system affording greater 
 speed is within Hmits ultimately the more economical one. For 
 these reasons, unless the conditions are indeed exceptional, the 
 employment of three drilHng shifts per day is recommended, 
 and the discussion of other phases of tunnehng methods which 
 follow will, unless otherwise noted, be predicated upon the 
 assumption that three drilUng shifts are being employed. 
 
 MOUNTING 
 
 American tunnel practice is almost equally divided between 
 the horizontal-bar and the vertical-column methods of drill 
 mounting. The former consists essentially of an iron pipe, 
 4 to 6 inches in diameter, a little shorter than the average width 
 
DRILLING 213 
 
 of the heading, and provided mth a soHd head at one end and a 
 jackscrew with a capstan head at the other. The latter, which 
 is rarely employed with more than two drilling attacks per day, 
 is usually provided with a yoke and two jackscrews at one end, 
 and its length is somewhat less than the height rather than the 
 width of the heading. In several notable European tunnels a 
 drill carriage was employed, however, so that a discussion of 
 this method of drill mounting should not be omitted. 
 
 The system employed with horizontal cross-bar method of 
 mounting rock drills can perhaps be best illustrated by a descrip- 
 tion of the procedure at the Laramie-Poudre tunnel. As soon 
 after the blasting as ventilation permitted (ordinarily ten to 
 fifteen minutes), the workmen returned to the face from a posi- 
 tion of safety 1,500 to 2,000 feet away, bringing with them an 
 ordinary tunnel car containing the cross-bar, drilHng machines, 
 tools, hose, etCi The three drillers, with the assistance 
 of the foreman, first removed any loose rocks from the 
 roof or walls which might fall later and possibly cause injury. 
 This accomplished, they next cleared a space in the top of the 
 rock pile, for two or three feet back from the face of the tunnel 
 and perhaps four or five feet from the roof, in order that they 
 might have room to work when drilKng. Because of methods 
 of blasting especially employed for this purpose, the rock pile 
 usually occupied but a small part of this space, so that ordinarily 
 but Httle work was required to clear it out. In the mean time, 
 the helpers were expected to unload -the bar and machines 
 from the car, placing them on the rock pile conveniently at hand, 
 and to connect the hose to the air and water mains. As soon 
 as a proper space was cleared out, the bar was picked up by 
 the drillers and helpers and held in position transversely across 
 the tunnel at a measured distance from the face and roof, as 
 directed by the foreman, where it was blocked, wedged, and 
 finally screwed as tightly as possible in place. The drill men 
 then placed the machines upon the bar and started drilhng as 
 soon as the helpers completed connecting the hose to the drills. 
 The necessary holes having been drilled from this position of 
 the bar, and the waste rock having been removed in the mean 
 
214 MODERN TUNNELING 
 
 time by the shovelers (an operation which was carried on simul- 
 taneously with drilHng and which ordinarily was accomplished 
 before the drillers had finished), the machines were taken off, 
 the bar was lowered and set up again about eighteen to twenty- 
 four inches from the floor, the drills were replaced, and one or 
 two holes were drilled by each machine from this position of the 
 bar. The machines and the bar were then placed in a tunnel 
 car and removed from the heading during the blasting. This 
 method, sometimes slightly modified, was used at several other 
 tunnels and adits with almost equally good results. 
 
 The procedure with the vertical-column method of mounting 
 is similar to this in some respects, but there are also some im- 
 portant distinctions aside from that of upright position. Owing 
 to the vibration produced by the drills, neither method of 
 mounting will give satisfaction unless the bar is firmly jacked 
 against soKd rock. The amount of vibration is intensified 
 and the need of a substantial foundation is much greater in the 
 case of the vertical column, because the drills are usually mounted 
 on cross-arms projecting from the columns at right angles, 
 thus affording a leverage for any movement of the drill. It is 
 therefore necessary to remove all of the waste rock from the 
 space immediately in front of the face of the tunnel prior to 
 drilling in order that the foot of the column may rest upon the 
 soKd floor, which, at the two or three tunnels where this method 
 was employed with the three-shift system, caused considerable 
 delay even under normal conditions. But in the majority of 
 places where this method of mounting was employed not more 
 than two drilhng attacks were attempted per day, and the extra 
 work of clearing away was performed by the crew of shovelers 
 before the drillers started work. 
 
 The best results with the carriage mounting for drills were 
 obtained during the construction of the Loetschberg tunnel 
 through the Bernese Alps. In the first type of carriage em- 
 ployed there, the horizontal bar carrying the drills was mounted 
 at the end of a steel beam which was pivoted to a truck and 
 counterbalanced at the other end by a heavy weight. Before 
 this carriage could be brought sufficiently near to the face. 
 
DRILLING 215 
 
 even with the long beam, for the cross-bar to be jacked in posi- 
 tion, it was necessary to clear quite a large passageway through 
 the center of the rock pile down to the floor. In doing this, 
 part of the material was carried away, and the remainder piled 
 on either side of the tunnel to be carried away during drilHng. 
 When the passage was finished, however, the carriage, with the 
 cross-bar and drills mounted upon it and extending longitudinally, 
 was quickly rolled to the face, the bar swung around and 
 jacked into position, and the drills were at once started to 
 work. 
 
 This carriage was superseded by one which abohshed the 
 counterbalanced beam and carried the drill bar directly upon 
 a short post mounted on the truck. With this device practically 
 all of the broken rock had to be removed from the heading before 
 the carriage was brought to the face, after which, however, the 
 drills started promptly at work. 
 
 One of the most important factors to be considered in choosing 
 a method of mounting for tunnel work is the time required to get 
 the drills in operation after blasting, including not only the 
 actual time employed in setting up the necessary apparatus, but 
 also the time consumed in the preparatory work of clearing 
 away debris. The time spent in waiting for the smoke to clear 
 is of course independent of the method of mounting, and can 
 therefore be ignored in this connection. With the horizontal- 
 bar system used at the Laramie-Poudre tunnel, the time normally 
 employed in mucking back was rarely more than fifteen to twenty 
 minutes. Jacking the bar in place occupied from five to ten 
 minutes, and attaching the drills and making the water and air 
 connections usually required from ten to fifteen minutes. The 
 entire operation thus consumed under ordinary conditions from 
 thirty to forty-five minutes, but it was not at all unusual, where 
 circumstances were favorable, for the drills to be in operation 
 within twenty or twenty-five minutes from the time the drill 
 men reached the heading. At other tunnels and adits using 
 this system the time required for similar work was reported as 
 from thirty to sixty minutes. Owing to the much greater 
 amount of material to be cleared out when the vertical-column 
 
216 MODERN TUNNELING 
 
 method is employed, the time consumed in getting the drills in 
 position to start work at adits and tunnjels where the three- 
 shift system was used ordinarily ranged from two and a half 
 to four hours, and even under the most favorable circumstances 
 was rarely less than two hours. The time spent in the Loetsch- 
 berg tunnel in removing the waste rock was approximately one 
 and a half hours with the first type of carriage used and from 
 one and a half to three hours with the later model ; but in order 
 to accomplish this, nearly twice as many men were employed at 
 the work as are usually found in American tunnel headings. 
 After the Loetschberg tunnel was cleared of the necessary 
 amount of debris, however, the machines could ordinarily be 
 started in from five to ten minutes. 
 
 Aside from the question of the time consumed in clearing, 
 the amount of waste to be removed has another bearing on the 
 problem of choosing a mounting. In order that there may be 
 no delay in getting the drills at work, usually the attempt is not 
 made to remove the waste rock entirely from the heading before 
 the mountings are set up, much of it being merely shoveled to 
 one side and removed later. This prehminary work is often 
 performed by the drill men, especially with the three-shift 
 system; and where (as in the case of the vertical-column method) 
 there is a great deal of it to be done, by the time the men have 
 the machines set up and are ready to start drilling they are pretty 
 well tired out and consequently cannot work so rapidly and 
 efiiciently in drilHng the required holes. Even if the work is 
 performed by the regular shoveling crew, these men certainly 
 are not stimulated by the knowledge that they are performing 
 dead work and that every shovelful handled in clearing back 
 must be moved again later. This disadvantage obtains not only 
 in the three-shift system, but in many cases in which two shifts 
 are employed, and the shoveHng crew start ahead of the drill 
 men and commence work clearing away the face for a vertical 
 column set-up. The horizontal-bar and, to a lesser degree, the 
 drill-carriage methods have the advantage of requiring a much 
 smaller proportion of duplicated work. 
 
 The adaptabihty of the mounting for the work required of 
 
DRILLING 217 
 
 it after the drills are in operation is another factor to be reckoned 
 with. The advocates of the vertical-column method claim 
 that it enables the holes to be placed to better advantage, and 
 this is quite truly the case where piston drills are employed. 
 But hammer drills mounted on a horizontal bar can place the 
 holes just as effectively, if not more so. But with either type 
 of machine the drill carriage is badly handicapped. It was 
 discovered with those used in the Loetschberg tunnel — and the 
 same disadvantage was experienced at an adit in this country 
 where a similar drill carriage was tried and soon abandoned — 
 that it was impossible to point the inclined holes in such a way 
 as to secure the maximum efficiency from the explosive used. 
 Therefore, in order to make the holes break to the bottom it 
 was necessary to use heavier charges of explosive, and the holes 
 were not drilled as deeply as they might otherwise have been. 
 The shallower holes made it necessary to spend a greater per- 
 centage of the day's labor in the unproductive preparatory work 
 of setting up and tearing down the drills, and increased the 
 opportunities for delays in blasting. Then, too, it is impossible 
 with one set-up of a horizontal bar, such as was used in the 
 carriage method of mounting, to make the holes near the bottom 
 of the tunnel sufficiently horizontal to secure an even floor, 
 necessitating trimming and causing trouble in maintaining the 
 proper tunnel grade. 
 
 The fact must not be overlooked, however, that with the 
 carriage method drills are subject to less wear and tear because 
 they are kept on the bar continually and are not thrown around 
 on the floor and muck-pile. When this is permitted the drills 
 are apt to become filled with sand, grit, etc., and because of 
 friction and abrasion, the cost of repairs is increased. Nor 
 should the facility in changing to a new hole possessed by the 
 horizontal bar and the drill carriage be disregarded. When 
 these methods of mounting are employed, all that is necessary 
 in starting a new hole is to slide the drill along the bar and 
 clamp it in place, but with the vertical column not only the 
 machine, but the cross-bar as well, requires adjusting; since the 
 adjustment is a vertical instead of a horizontal one, the entire 
 
218 MODERN TUNNELING 
 
 weight of both drill and cross-arm must be Hfted or sustained 
 at nearly every change. 
 
 Taking, then, all of these factors into consideration, the 
 horizontal bar proves to be the method of mounting drills best 
 adapted for tunnel work. Its use enables the drills to be put in 
 operation with the least loss of time and by the smallest number 
 of men. It requires the rehandling of the minimum amount 
 of waste rock, so that the drill men are not fatigued before they 
 start drilling or the shovelers disheartened by dead work. It 
 permits directing the holes in such a way that the maximum 
 strength of the explosive is utihzed, drilHng deeply so that 
 too great a portion of the time need not be spent in preparatory 
 work, and placing the holes to insure the breaking of the roof 
 and floor smoothly and at the desired grade. It is especially 
 adapted for use with the more rapid-drilling hammer machines 
 and lends itself readily to removal when necessary. In common 
 with the vertical type it is subject to the danger of allowing 
 grit to become lodged in the machines, but this can be partially 
 prevented by care in handhng. These considerations render 
 the use of the horizontal bar highly desirable where an efhcient 
 method of mounting drills for tunnel work is desired. 
 
 NUMBER OF HOLES 
 
 Any determination of the proper number of holes to be used 
 in driving a tunnel or adit of a given size is dependent upon 
 several factors. A large number of holes in which a greater 
 charge of explosive may be placed expedite the operations of 
 driving, because the heavier blast tends to hurl the rock farther 
 away from the face, and thus not only saves time in setting 
 up the machines, but also gives the shovelers more room and 
 enables them to work to better advantage on more widely 
 scattered material. But, at the same time, holes that are not 
 strictly a necessity entail an extra expense not only for the 
 explosive used in them, but also for the time required in drilHng. 
 This is especially true in those cases in which the drilling work 
 requires more time than the operation of removing the rock, 
 and hence any extra holes would delay both crews. If the proper 
 
DRILLING 
 
 219 
 
 
 
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 lO o o 
 
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 1^ c i 
 
 
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 ^ w en ^ 
 
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 ta 
 
 <n 
 
 ^ <V (U 
 
 2 .ti .ti "2 In 
 
 c 2 2 c <u 
 
 -^ 2|J3^2JS^ 
 
 
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 oj oj <i; I— I "^ ^_ 
 
 3 rt"^^ 
 
 
220 
 
 MODERN TUNNELING 
 
 
 O C^ 
 
 
 ir> 
 
 
 h 
 
 Is 
 
 : 1 1 
 
 :vo o 
 
 
 «"■* : : : : 
 
 • 
 
 >. 
 
 
 
 hH \D 
 
 
 S-3 
 
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 00 
 
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 : : : 00 CO ' 
 
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 01 
 
 ^S o c *J 
 
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 m 
 
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 l^ij"^ rn bi043 tfi+j 0-l-> N-<-> C 
 
 iz; o P^ c^ Cii "cT^ cr. c^c^ c>o ::) >^ 
 
DRILLING 221 
 
 number of holes is being used, the major portion of the rock 
 should be broken into fragments small enough to be shoveled 
 readily, although an occasional boulder, because of the relaxa- 
 tion it affords the workman from the steady grind of shoveling, 
 is said to expedite rather than retard the speed with which the 
 spoil can be loaded into the tunnel cars. 
 
 The central factor and starting point, however, in a just 
 determination of this question is undoubtedly the physical 
 character of the rock being penetrated, which is never twice 
 alike in different localities, and it is generally necessary to experi- 
 ment at first in order to discover what number of holes will 
 indeed produce the best results. Generally speaking, igneous 
 rocks require more holes than sedimentary rocks, but there are 
 wide divergences in both classes. The holes must be more 
 closely spaced for a tough rock that is close-grained and massive 
 than for one that is brittle and easily shattered, even though it 
 may be harder and more difficult to drill. Bedding or joint 
 planes or joint cracks are of great assistance, and a rock in which 
 they occur will be more easily broken and hence require fewer 
 holes. The preceding table shows the number of drill holes used 
 in American tunnels penetrating different classes of rock. 
 
 DIRECTION OF HOLES 
 
 Chiefly because of the great influence of local conditions, the 
 arrangement of drill holes is rarely identical at any two tunneling 
 projects. For reasons to be explained later, however, it is cus- 
 tomary to drill a part of the holes (called the ''cut" or ''cut 
 holes") in such a manner that when blasted they will first remove 
 a core of rock from the solid face of the heading, thus decreasing 
 the work to be done by the remaining holes. Practically all of 
 the various means of arranging drill holes in the headings of 
 American tunnels may be summarized as follows into three main 
 types, according to the kind of cut employed. 
 
 The wedge or "V" cut is the one most commonly employed 
 in tunnehng operations in this country. It consists essentially 
 of several pairs of holes directed toward each other from opposite 
 sides of the heading in such a manner that when properly charged 
 
222 MODERN TUNNELING 
 
 and exploded they will break out a wedge-shaped core of rock 
 usually extending from the roof to the floor of the tunnel. Figure 
 58 shows a typical wedge-cut round similar to the one employed 
 in driving the Buffalo Water tunnel. Holes numbered i to 8 
 comprise the cut and were blasted simultaneously by electricity, 
 while 9 to 14 are the side holes, and were next fired together, 
 and 15 to 18 are the back or dry holes and were exploded last. 
 Such a round must necessarily be changed somewhat where the 
 heading is arched or semicircular. Figure 59 illustrates such 
 a round, similar to those used in driving the heading of the 
 large siphons on the Catskill Aqueduct. In this case holes i 
 to 6, comprising the cut, were blasted together, followed by 
 holes 7 to 12, which were called rehevers, and finally by 13 to 
 22, which were called trimming holes. 
 
 Either vertical columns, as was the case in the two examples 
 just cited, or a horizontal bar may be used to mount the machines 
 when drilling this type of round, but where the majority of the 
 holes are to be drilled from one position of a horizontal bar the 
 location of the holes must necessarily be somewhat modified, 
 although the general arrangement still remains a wedge-cut 
 round. Figure 60 shows such an arrangement, similar to the 
 one employed at the Laramie-Poudre tunnel. Holes Nos. i and 
 2 were called short-cut holes, Nos. 3 to 6 long cuts, Nos. 7, 
 8, 9, 10, 19, and 20 relievers, 11 to 14 sides, 15 to 18 backs, and 
 Nos. 21 to 23 lifters, the numbering indicating the order of 
 blasting. The lifters, and two rehevers (Nos. 19 and 20) which 
 were used only in hard ground, were the only holes drilled from 
 the lower position of the bar. Three machines were employed in- 
 drilling this round, and the following table (page 224) shows 
 the holes drilled by each and the order of drilHng (lettering 
 the machines A, B, and C from left to right when facing 
 the heading). 
 
 A somewhat similar round was used with a horizontal bar 
 at the Rawley tunnel, and there are, of course, many other 
 variations of the V-cut arrangement of holes, but these figures 
 illustrate the principles underlying the more common ones 
 employed in tunnels and adits in this country. 
 
Fig. 58. Wedge-cut round of holes. 
 
 Fig. 59. Modified wedge-cut round for arched heading. 
 
 Fig. 60. Wedge-cut round drilled from a horizontal bar. 
 
224 
 
 MODERN TUNNELING 
 
 ORDER OF DRILLING FOR EACH MACHINE AT LARAMIE-POUDRE 
 TUNNEL 
 
 Machine A 
 
 Drill-hole 
 numbered 
 
 Machine B 
 
 Drill-hole 
 numbered 
 
 Machine C 
 
 Drill-hole 
 numbered 
 
 f I 
 o 2 
 
 1 3 
 
 1 * 
 
 a 5 
 
 § 7 
 
 17 
 II 
 
 5 
 
 13 
 
 7 
 
 I 
 
 19 
 
 I 
 2 
 
 3 
 
 4 
 5 
 
 i6 
 
 10 
 
 15 
 9 
 3 
 
 I 
 2 
 
 3 
 4 
 5 
 6 
 
 7 
 
 l8 
 12 
 
 6 
 
 14 
 
 8 
 
 2 
 20 
 
 Lower 
 position 
 
 00 
 
 22 
 
 6 
 
 21 
 
 8 
 
 23 
 
 The second general type of cut frequently employed will be 
 designated as the pyramid cut, consisting usually of four cut 
 holes drilled in such a manner that they meet, or nearly meet, 
 at or near a common point — generally near the axis of the tunnel 
 — and when properly blasted they remove a more or less pyra- 
 midal core. Figure 6i shows a round of this type similar to the 
 one employed at the Yak tunnel, in which the cut holes numbered 
 
 I were blasted simultaneously, 
 followed by the remaining holes 
 in the order indicated. In most 
 of the instances observed by the 
 authors, the pyramid cut has 
 been employed with vertical col- 
 umns, but it can be drilled just 
 as efhciently with the horizontal 
 bar by drilling two or possibly 
 three holes with each machine 
 from the lower set up. Figure 62 
 shows such a round. 
 
 The third type is the bottom 
 
 or draw cut which was employed 
 
 at several places visited, the one at the Carter tunnel illustrated 
 
 in Figure 63 being typical. The holes were blasted in the order 
 
 indicated, Nos. i to 3 comprising the cut. 
 
 Fig. 61. 
 
 Pyramid-cut round 
 of holes. 
 
Fig. 62. Pyramid-cut round for use with 
 horizontal bar mounting. 
 
 Fig. 63. Bottom-cut round of holes. 
 
226 MODERN TUNNELING 
 
 It can easily be proved theoretically that where a bore hole 
 is drilled in a homogeneous mass of rock the maximum efficiency 
 can be obtained from a suitable charge of explosive placed in it 
 when the line of least resistance (by which is meant the shortest 
 distance from the charge to a free surface of the rock) is at 
 right angles to the axis of the bore hole, and that the minimum 
 efficiency will be obtained when the two are coincident. And 
 practically, although a homogeneous rock is a rarity and hence 
 the actual results will be influenced quantitatively somewhat 
 by the various features of rock texture such as joints, cracks, 
 fault fissures, bedding planes, etc., the results have been found to 
 agree in the main with the theoretical deductions. It is obvious, 
 therefore, that in the heading of a tunnel or adit where but one 
 free face can be obtained, it is impossible to drill and blast a 
 single hole in such a manner that the maximum efficiency can 
 be obtained from it. But by drilling a number of holes arranged 
 according to any of the preceding systems, and blasting the 
 cut first so as to create more free surface, much better results 
 can be obtained from the holes which remain. It is for this reason 
 that the position and direction of the holes comprising the 
 cut are generally considered the most important feature of the 
 work, the spacing of the remaining holes being admittedly 
 merely a question of having them sufficiently close together to 
 break the rock into fragments of the required size for facile 
 handling. 
 
 When the wedge or V-cut is employed, the several pairs of 
 holes should be placed close enough together for them to be of 
 some mutual assistance. This is especially true when the entire 
 cut is exploded simultaneously. What this distance shall be 
 is controlled almost entirely (as in the determination of the 
 proper number of holes) by the character of the rock, its tex- 
 ture, toughness, the presence of cracks and bedding planes, etc. 
 Its determination is often made by the foreman in charge, and 
 if he is a man of wide experience, satisfactory results may follow; 
 but the general efficiency of the work will often be increased 
 greatly if experiments are made at the outset to determine just 
 what combination will give the best results for the particular 
 
DRILLING 227 
 
 rock being encountered. It follows, of course, that such experi- 
 ments should be repeated whenever a marked change in the 
 nature of the rock is observed. 
 
 In order that the line of least resistance may approximate as 
 closely as possible the perpendicular to the axis of the drill hole, 
 the angle between opposite holes in the cut should be as large 
 as can be obtained with any given dfepth of round. From this 
 it follows that the drill holes should start as near as possible to 
 the opposite sides of the heading; but obviously the full width 
 of the heading cannot be utilized because provision must be 
 made for the feed screw and crank of the drill, which usually 
 extend three to four feet from the face. This works especially 
 to the disadvantage of narrow headings, because in them a 
 greater proportion of the actual width must be sacrificed for 
 this purpose. But with broad headings the marked advantage 
 of a wide angle is easily secured and possibly offers an explana- 
 tion of the popularity of the wedge-cut system in such cases. 
 
 Of even greater importance than the necessity of securing 
 a wide angle between opposite holes is that of drilling them so 
 that they meet, or at least bottom near enough to one another 
 to be detonated simultaneously by the one first to explode. 
 Owing to mechanical reasons, the width of the drill bit, and hence 
 the size of the hole, must be decreased with each successive 
 change of steel, and as a result the hole is necessarily smallest at 
 its bottom end — the place where the explosive is most needed 
 and where it is extremely desirable that the hole should be as 
 large as possible. Omitting from consideration the expedient 
 of chambering (that is, the enlargement of the bottom of the 
 hole by the explosion of a small primary charge before loading 
 it with the main portion of the explosive) which consumes en- 
 tirely too much time to be considered for rapid tunnel driving, 
 the defect can be overcome to a surprisingly large degree by the 
 simple resort of connecting the drill holes, which concentrates 
 the explosive at the point of the ''V." When fuse firing is 
 employed, it is extremely essential that the holes be so directed 
 that they are intercommunicating (or so nearly so that both 
 holes will detonate together) or the desired effect will not be 
 
228 MODERN TUNNELING 
 
 gained, but when electric firing is employed direct connection; 
 although very desirable, is not so absolutely essential. 
 
 But in addition to the mere concentration of explosive thus 
 secured, the combined efficiency of the two charges is much 
 greater than when they are exploded separately. Assuming, 
 again, that the holes are drilled in homogeneous rock and that 
 they make equal angles with the shortest line from their junction 
 to the free face, if both are loaded with identical charges of 
 explosive and detonated simultaneously, their maximum break- 
 ing effect will be exerted along the resultant of their combined 
 forces, which in this theoretical case coincides with the shortest 
 distance to the free face (the line of least resistance). Practi- 
 cally, of course, this will be somewhat modified; but it is a 
 well-established fact that where the ground is tough and difficult 
 to break, much better results are obtained when the cut holes 
 are directed and drilled to intersect; although, unfortunately, 
 this is not widely known, as evidenced by the too great number 
 of cases observed in which no attempt was made to connect the 
 cut holes. 
 
 Practically the same conditions prevail with the pyramid 
 cut. The number of holes comprising it may vary from three 
 to six or even eight, according to the nature of the ground; 
 and the proper number can best be determined by experiment. 
 It is just as necessary to drill the holes with the widest possible 
 angle between them, and it is even more essential that they meet 
 in a common point, because one of the main advantages of this 
 cut is the concentration of a greater amount of explosive at the 
 narrow apex of the core of rock to be removed. All these advan- 
 tages are thrown away if the charges of explosive in the different 
 cut holes are not detonated simultaneously. 
 
 The bottom cut, as it is usually drilled in practice, although 
 it often enables the attainment of a wider angle between the axis 
 of the drill hole and the line of least resistance, disregards entirely 
 the important advantage to be obtained from connecting drill 
 holes, and this circumstance, in the opinion of the authors, should 
 be sufficient to prevent its use under any but exceptional condi- 
 tions. For mine adits, however, whose excavation must of neces- 
 
DRILLING 229 
 
 sity provide sufficient head room but whose lateral extent is 
 limited, in which it would be impracticable, if indeed possible, 
 because of the narrowness of the heading, to drill an effective 
 wedge, or a pyramid-cut round, the bottom cut furnishes the 
 only solution of the difficulty. In this event it is recommended 
 that the cut holes be drilled from as near the top of the heading 
 as possible, and directed in such a manner that they will connect 
 with holes that are usually considered lifters, and that both 
 be detonated together. 
 
 DEPTH OF HOLES 
 
 During the past four or five years there has been some differ- 
 ence of opinion among students of the problems of tunnel driving 
 as to the proper depth for drill holes in tunnel headings. In 
 view of some of the remarkable results attained in driving the 
 Simplon and Loetschberg tunnels, where, as is admitted by 
 every one, the holes were much shallower than those in American 
 practice, the question has been raised whether the holes in tunnels 
 of this country are not drilled too deep. Numerous tables have 
 been prepared in support of this argument, in which it appears 
 that at most of the European tunnels the progress is much 
 greater (in some cases more than double) than that of tunnels 
 in America. But at the same time, consideration is not always 
 given the fact that in many instances these records are in their 
 nature in no wise comparable; for in Europe, at the majority 
 of tunnels thus cited, the work was conducted throughout the 
 entire twenty-four hours of each day, while in America in many 
 instances but two (and indeed in some only one) shifts were 
 employed daily. Then again, the nature of the rock exerts an 
 all-important influence upon progress, and in many cases this 
 has been to the advantage of the European tunnels. A notable 
 example of the influence of the rock encountered is found at the 
 Loetschberg tunnel, where the same methods and practically the 
 same equipment were employed at the different ends, the one at 
 north end working in limestone, and the other in the south end 
 in gneiss and schist. The progress attained at the south end 
 was much less than that of the north, and in some months the 
 
230 MODERN TUNNELING 
 
 progress in the north end was nearly double that of the south. 
 Other considerations also, especially the amount of labor and 
 the cost of driving, enter into the problem in such a manner 
 as to make it impossible to say (when everything is taken into 
 account) that the greater speed in European tunnels is due solely 
 to the use of extremely shallow holes. That in many instances 
 the holes in American tunnel headings are too deep, however, 
 is equally impossible of denial, and for these reasons a discussion 
 of the factors which enter into the determination of the proper 
 depth of holes is extremely desirable. 
 
 One of the chief advantages arising from the use of shallow 
 rounds is (when the holes are properly directed) the increased 
 efficiency obtainable from a given charge of explosive; for, since 
 the width of the heading is for all practical purposes constant, the 
 angle between the Hne of least resistance and the axis of the 
 bore-hole becomes a function of the depth of round, the width 
 of the angle increasing with shallow holes. This advantage 
 obtains especially with the wedge cut and with the pyramid cut, 
 and it should be a fundamental consideration with the bottom- 
 cut method of drilling the holes. Strangely enough, however, 
 in the Loetschberg and the Simplon tunnels, which are so often 
 cited as examples of the ''highly desirable" European practice 
 of using shallow holes, this advantage was almost, if not entirely, 
 thrown away, because the holes were drilled in vertical rows 
 and were nearly parallel to the bore of the tunnel. In such a 
 case the line of least resistance and the axis of the bore-hole are 
 nearly coincident — a condition which results in the production 
 of the least possible efficiency from the charge of explosive ; and 
 it cannot be gainsaid even by the advocates of this method that 
 a much greater quantity of explosive than is usual in American 
 practice was required to break the same amount of rock. Ii 
 to this is added the fact that such a system utterly ignores the 
 advantage to be obtained from connected drill holes by the con- 
 centration of explosive at the apex of the core of rock to be 
 removed, there is strong ground for rational suspicion that the 
 extreme shallowness of the holes used in these tunnels was adopted 
 from necessity rather than from desirability; because with this 
 
DRILLING 231 
 
 system of drilling and directing the holes the difficulty of blasting out 
 the rock with deeper rounds could not fail to be greatly increased. 
 
 Among other advantages of the use of reasonably shallow 
 holes may be mentioned the fact that such a method allows that 
 the holes be of larger diameter at their further end, increasing 
 their capacity for explosive and enabling its concentration at the 
 point where it is most needed. This is one of the chief factors 
 which makes even possible the European practice of employing 
 extremely shallow holes, but it can hardly be denied that in this 
 case much more effective results in blasting might be accom- 
 plished by a change in the direction of the cut-holes. Besides, 
 since, in America at least, the holes are rarely charged with 
 explosive to their full extent, the mass of rock between the ends 
 of the charges of explosive in the different holes and the free 
 face of the heading (which can be considered as a measure of the 
 amount of resistance to be overcome) is not so great with the 
 shallow holes. This fact, or the customary use of relatively 
 heavier charges in shallow holes, may explain, perhaps, why in 
 such cases the major portion of the rock is usually thrown 
 farther down the tunnel instead of being piled high immediately 
 in front of the new face, with the double advantage of making 
 it easier to load the rock and saving time in getting the drills 
 mounted. It is fairly well estabhshed, also, that the rock tends 
 to break into smaller fragments where shallow holes are em- 
 ployed. And again, where deep holes are not employed the same 
 care in starting them exactly at a given point is not required, 
 nor is it necessary to direct them with such great accuracy — 
 although, of course, the need of connecting the cut holes must 
 not be overlooked. 
 
 The principal and very serious disadvantage in using the 
 shallow-hole round, on the other hand, and one that it is impos- 
 sible to avoid, is the fact that in order to secure the same daily 
 advance a proportionately greater number of drilling attacks 
 must be made. This results in a waste of time in drilling; for 
 it is possible under ordinary circumstances to drill one hole of a 
 given depth more rapidly than two holes of the same aggregate 
 footage because of the time lost in changing to a new position, 
 
232 MODERN TUNNELING 
 
 Starting, etc. But even granting that the difference in drilling 
 time (perhaps because it is too small, or because in either 
 case the drilHng can be completed before the heading can be 
 cleared of debris) is not an appreciable factor, each extra drilling 
 attack required to secure the same progress causes a correspond- 
 ing loss of time in loading and blasting the holes, in waiting for 
 the smoke and gases to be removed, in clearing the debris from 
 immediately in front of the face, and in setting up the drills, all 
 of which is ordinarily dead work and cannot be avoided. This 
 was seriously felt at the Loetschberg tunnel, because in the 
 endeavor to compensate for it, it was necessary to employ four 
 drills in the heading (6 feet x lo feet) ; and as a result the holes 
 had to be drilled nearly straight, with disadvantages already 
 described, because otherwise the drills in the center interfered 
 seriously with the operation of those at the side. 
 
 On the other hand, where the holes are too deep, as is some- 
 times the case in America, the angle between the cut-holes may 
 be so narrow and the mass of rock in front of the charge of 
 explosive may be so great that it will be impossible for the cuts 
 to break bottom on the first blast and thus the entire round is 
 spoiled. The usual remedy in such cases is to blast the cuts 
 separately and not to fire the remainder of the round until it 
 has been ascertained by inspection that the proper depth has 
 been reached by the cut-holes. A certain amount of delay can- 
 not be avoided when this method is employed, even if the holes 
 break to the end, for it is never possible to return to the breast 
 for such inspection immediately after the cuts have been deton- 
 ated. But when the cut-holes fail to break, the delay is greatly 
 increased because the remaining portions must be cleaned out, 
 reloaded, and fired, with an additional delay in waiting for the 
 smoke to clear. 
 
 This system v/as used at one of the Colorado tunnels, which 
 at the time of first examination was being driven through some 
 very tough rock, employing a round of holes slightly deeper 
 than the average width of the heading. Holes of this depth had 
 given satisfactory results in the somewhat more frangible ground 
 previously penetrated, the round being drilled and blasted in an. 
 
DRILLING 23S 
 
 eight-hour shift without difficulty; but upon striking the harder 
 rock it became necessary to blast the cuts separately, and more 
 often than not to reload and shoot them for the second and 
 occasionally for the third time, the cycle being lengthened to 
 about ten hours, while several times at least fourteen hours 
 were needed. If three drilling shifts had been employed at the 
 time, such a condition would have been fatal; but since but two 
 attacks were being made the difference was not so noticeable, 
 though even in this case the cost of the extra explosives required 
 and the overtime wages of the men added a considerable amount 
 to the expense of the tunnel work. Shortly after the first 
 examination of this tunnel by the authors, however, the depth of 
 the rounds was reduced to about 75 per cent, of the width 
 of the heading. This made it unnecessary to load and shoot 
 the cuts separately, and instead of getting two seven-and-one-half- 
 foot rounds in from twenty to twenty- two hours, by working 
 three eight-hour shifts it was possible to drill and blast four, and 
 sometimes five, five-foot rounds per day, thus increasing the daily 
 tunnel progress from fifteen to nearly twenty-three feet with but 
 a very small extra cost for labor. The consumption of explosive 
 which was a very considerable item with the old system was also 
 decreased fully 25 per cent., and the total cost of the tunnel per 
 foot was greatly reduced. 
 
 The disadvantage of too deep holes was strikingly brought 
 out in the construction of the Laramie-Poudre tunnel. During 
 the first part of the work a ten-foot round was drilled in a head- 
 ing gyi feet wide, but the round was later changed to one of 7 
 feet in depth with much better results. To be more specific, 
 during the seven months from April i, 19 10, to October 31, 19 10, 
 at the east end of the tunnel, 3,171 feet were driven, an average 
 of 453 feet per month, using a ten-foot round; but during the 
 next 8Vs months, from November i, 1910, to July 24, 1911, 
 when the tunnel holed through, 4,798 feet were driven, or an 
 average of 545 feet, with a seven-foot round. This is an increase 
 of over 20 per cent., in spite of the fact that the higher speed 
 was made when the work was at a greater distance from the 
 portal; and, since there was no essential change in method, 
 
234 MODERN TUNNELING 
 
 equipment, or in the character of the rock penetrated, it is attrib- 
 utable solely to the use of shallower holes. When the ten-foot 
 holes were employed to secure an advancexnent of S}4 to 9 feet, 
 it was unusual to be able to drill and blast more than two rounds 
 in twenty-four hours, and oftentimes not so many, as the aver- 
 age of i4>^ feet daily testifies; but with the seven-foot round 
 not only could three attacks be made, advancing on an average 
 6}4 feet per attack, but a comfortable margin of time was left 
 to provide for delays and under favorable conditions this extra 
 time meant extra footage. Thus in March, 191 1, the American 
 hard-rock record of 653 feet, or over twenty-one feet per day, 
 was established. This advantage of being able to complete an 
 entire cycle of operations during a single shift should be given 
 the weight in the problem it deserves. If crews of men could be 
 found who would work as well without rivalry and without special 
 incentive to push the work, it might be perfectly feasible to 
 choose a depth of round that would require ten, or even twelve, 
 hours to put it in; but under the present working conditions, 
 where it is necessary to have some accurate measure of the work 
 performed by each crew, a round is required for which the entire 
 cycle can be completed during a single shift, with a sufficient 
 margin of safety to provide for any ordinary delay. 
 
 It is, of course, impossible to set any definite standard or 
 guide for the proper depth of hole which will be applicable to 
 all cases. There are too many variables influencing the result. 
 The proper depth can only be and must be determined by experi- 
 ment in each individual case. But from an extended examination 
 of American practice, investigating carefully the results obtained 
 from the methods employed, from a careful analysis of European 
 practice as far as could be found in pubHshed accounts, and 
 from a study of all the available modern authorities, the authors 
 are of the opinion that for the majority of cases the proper 
 depth of drill-hole, the one which most equitably balances the 
 advantages and disadvantages inseparable from the problem 
 will be found after careful experiment to be a depth from 60 to 
 80 per cent, of the width of the tunnel heading. The following 
 table gives an analysis of American practice in this respect: 
 
DRILLING 
 
 235 
 
 JO 
 
 
 c)^0 
 
 
 4) ci 
 
 
 
 
 
 
 
 
 c Si c 
 
 
 
 
 
 
 
 
 
 
 rt G o 
 
 Gneiss 
 
 Basalt 
 
 Granite and gneiss 
 
 Altered granite 
 
 Close-grained gran 
 Conglomerate shal 
 Hard granite 
 Granite and gneiss 
 Shale and slate 
 Sandstone 
 
 Gneiss 
 
 Rhyolite 
 
 Sedimentary 
 
 Granite 
 Andesite 
 
 Gneiss and granite 
 Hard granite 
 Granite 
 Diabase 
 Limestone 
 Conglomerate and 
 Limestone, sandstc 
 Quartzite 
 Limestone, sandst 
 granite 
 
 r^oo 00 oooo t^>oio^o o^^^^^oo ONt^r^uoo on^oo Ovo "OO OvO'O^O'^ 
 
 §§1-3 
 
 >-0 O-Q 
 
 r^oo 00 o 00 vo t^ lo lo^o ON r^ t^oo om^ r^ lovo onvo oo ovo io»oovoovo -^ 
 
 
 ^ :^ X ^ X 'i 
 
 o <N ooooo^^ r^ooooo ONOooooooo o i^cnh i^ lo^o (n ^ t^'O lo j ^ 
 
 lO lO rh -^ rt- 'rh lO lOO O (N ON (N 00 00 lO lOOO On fC ON t^ On O ^ OnvO t^OO O t^ 
 
 00 t^ 00 00 00 00 r^o 00^ hHvooooo oni^ r^oo > 
 
 O On r^ ONvo r^vo o r^o oo r^ 
 
 bO O 
 
 a; 0) 0) (u oj'S c'(-*(^ E 
 
 . G O biObuObjObiOtiOO tuObflbfibflO H 
 
 bjObiObiObiObjOO O bXjbCbjObjObioC <- ^ _ _ 
 
 — j rt 52 
 
 pauu 
 
 =3 O 
 oj O 
 
 oi3 ^ 
 
 
 
 2^-rt 
 
CHAPTER XII 
 BLASTING 
 
 AMMUNITION 
 
 To be suitable for use in tunnel work, as distinguished from 
 surface blasting operations, an explosive should not produce any 
 great amount of poisonous gases and should not easily, if at 
 all, be affected by moisture. In common with other usages, a sub- 
 stance is required here that is stable in composition and not 
 rapidly deteriorated by frequent changes of temperature or other 
 causes; it must not, as, for example, is the case with liquid 
 nitroglycerine, be so sensitive to shock that safe transportation 
 and handhng are wellnigh impossible. Although under some 
 circumstances, especially in tunnels that are not wet, an explo- 
 sive called ammonia dynamite can be and is employed on rare 
 occasions, the one which best fulfills the necessary requirements 
 and the one which is almost universally used in tunnel work is 
 known as gelatine dynamite. 
 
 Gelatine dynamite is a combination of a certain amount of 
 blasting gelatine (varying according to the strength desired) and 
 a suitable absorbent. The former is made by adding a small 
 percentage of gun-cotton (nitrocellulose) to liquid nitroglycerin, 
 thus producing a jelly-like mass that has greater explosive qual- 
 ities than either of its constituents, but which is much less sen- 
 sitive to shock than nitroglycerine. The absorbent is usually 
 some combustible material (wood pulp is frequently employed) 
 to which has been added a sufficient amount of sodium nitrate to 
 supply the necessary oxygen for its combustion. By the use of 
 such a combustible absorbent, instead of the inert one formerly 
 employed with straight nitroglycerine dynamite, the gases gener- 
 ated by the burning of the wood pulp add to the volume pro- 
 duced by the detonation of the explosive constituent, and the 
 extra heat generated in this combustion adds greatly to the 
 
 236 
 
237 
 
 total intensity of the reaction. Ammonia dynamites, which 
 are a somewhat more recent discovery, consist of a combina- 
 tion of ammonium nitrate and nitroglycerine absorbed in a so- 
 called ^'dope" similar to that just described. The following 
 tables * show typical compositions of commercial samples of these 
 two kinds of dynamite: 
 
 GELATINE DYNAMITE 
 
 
 
 
 
 Strength 
 
 
 
 
 Ingredient 
 
 
 
 
 
 
 
 
 
 30% 
 
 35% 
 
 40% 
 
 50% 
 
 55% 
 
 60% 
 
 70% 
 
 Nitroglycerine. . . 
 Nitro-cellulose . . 
 
 230 
 0.7 
 
 28.0 
 0.9 
 
 330 
 1.0 
 
 42.0 
 
 1-5 
 
 46.0 
 1-7 
 
 50.0 
 1-9 
 
 60.0 
 2.4 
 
 Sodium nitrate . . 
 Combustible 
 
 62.3 
 
 58.1 
 
 52.0 
 
 45-5 
 
 42.3 
 
 38.1 
 
 29.6 
 
 materials! 
 
 Calcium 
 
 130 
 
 12.0 
 
 130 
 
 10. 
 
 9.0 
 
 9.0 
 
 7.0 
 
 carbonate .... 
 
 I.O 
 
 1.0 
 
 1.0 
 
 1.0 
 
 1.0 
 
 1.0 
 
 1.0 
 
 t Wood pulp used with 60 and 70 per cent, strength; sulphur, flour, wood 
 pulpj and sometimes resin used in other grades. 
 
 AMMONIA DYNAMITE 
 
 Ingredient 
 
 
 
 Strength 
 
 
 
 30% 
 
 35% 
 
 40% 
 
 50% 
 
 60% 
 
 Nitroglycerine 
 
 15 
 
 51 
 
 18 
 
 20 
 
 15 
 
 48 
 16 
 
 I 
 
 22 
 20 
 42 
 
 15 
 
 I 
 
 27 
 25 
 36 
 II 
 
 I 
 
 35 
 30 
 
 24 
 10 
 
 I 
 
 Ammonium nitrate 
 
 Sodium nitrate 
 
 Combustible materials! 
 
 Calcium carbonate or zmc oxide . . 
 
 t Wood pulp, flour, and sulphur. 
 
 For further discussion of the nature and composition of 
 explosives, which is hardly within the province of this book, the 
 reader is referred to various publications of the Bureau of Mines; 
 they may be had upon application to the Director, Bureau of 
 Mines, Washington, D. C. 
 
 The harmful gases usually resulting from dynamite are 
 carbon dioxide and carbon monoxide. Although the former will 
 
 *From a paper by C. T. Hall before American Institute Chemical Engi- 
 neers, Washington, D. C. Meeting December 20, 191 1. 
 
238 
 
 MODERN TUNNELING 
 
 not support respiration, and when present in sufficient amount 
 may cause unconsciousness and even death from strangulation, 
 it has no very injurious effects when sufficiently diluted. The 
 latter, however, is not only exceedingly dangerous, but its 
 effects are also cumulative ; indeed if air containing even a very 
 small amount of it is breathed for any length of time, serious 
 and often fatal results will follow. The fact that gelatine 
 d>Tiamite (with the possible exception of ammonia dynamite, 
 which approaches it very closely in this respect) produces under 
 proper conditions the least amount of carbon monoxide is one 
 of its chief advantages for use in tunnel work. Even with this 
 explosive, however, if the cap is not strong enough to cause a 
 complete detonation, and even more especially when the dynamite 
 burns rather than explodes, much greater amounts of carbon 
 monoxide are formed ; in addition there are many other harmful 
 gases produced, among which may be mentioned the dangerous 
 peroxide of nitrogen and hydrogen sulphide, the former of wliich 
 is especially virulent. 
 
 The following table shows the results of tests conducted by 
 the Bureau of Mines concerning the kind and amounts of gases 
 produced by the detonation of samples of various kinds of 
 commercial dynamites. In making the tests a charge of 200 
 grams (approximately 7 ounces) in the original wrapper was 
 exploded in a Bichel pressure-bomb and the gaseous products 
 retained and analyzed: 
 
 GASEOUS PRODUCTS FROM EXPLOSIVES 
 
 Kind of explosive 
 
 1 
 
 1 C! 
 
 II 
 
 27.4 
 
 
 19.2 
 
 
 39-5 
 
 41 
 
 45-5 
 
 5-4 
 
 28.4 
 
 8.7 
 
 
 40% straight nitro- 
 glycerine dynamite. 
 
 60% straight nitro- 
 glycerine dynamite. 
 
 40% strength gelatine 
 dynamite 
 
 40% strength am- 
 monia dynamite. . . 
 
 FFF black blasting 
 powder (300 grs.) . . 
 
 27-3 
 
 26.9 
 
 0.0 
 
 18.0 
 
 22.2 
 
 34-6 
 
 0.0 
 
 23.2 
 
 50.8 
 
 30 
 
 0.0 
 
 1.8 
 
 41.4 
 
 3-8 
 
 0.0 
 
 31 
 
 49 7 
 
 10.8 
 
 0.0 
 
 1.8 
 
 0.4 
 
 0.8 
 0.8 
 0.8 
 0.6 
 
BLASTING 239 
 
 A further distinctive feature of gelatine dynamite, winning 
 for it the advantage over ammonia dynamite for most tunnel 
 work, consists in its practically waterproof quality, a condition 
 largely due to the insolubility of the blasting gelatine which 
 can be freely immersed in water with but httle if any of it dis- 
 solving. Ammonia dynamite, on the other hand, being hygro- 
 scopic, has a great affinity for moisture and hence not only 
 cannot be used in wet work (or even in damp work when it is 
 necessary to spKt the original paraffined paper covering), but 
 greater care must be used in selecting a dry place for storing it. 
 
 Gelatine dynamite is somewhat less sensitive to direct shocks 
 than other dynamites, and unlike them the sensitiveness does not 
 increase with the strength; much stronger detonators must 
 therefore be used even with the higher grades in order to insure 
 complete detonation. This fact is often not sufficiently ap- 
 preciated by practical mining men, many of whom are not 
 aware of the greater ultimate economy obtainable if the more 
 powerful, although somewhat higher-priced, detonators are used 
 with gelatine dynamites. 
 
 The strength of nitroglycerine dynamites as they are made 
 to-day is generally rated according to the percentage of their 
 nitroglycerine content, in spite of the fact that both the volume 
 of gases and the temperature (and hence the disruptive force) 
 are augmented somewhat by the combustion of the absorbent 
 material. Although 40 per cent, is the strength most generally 
 employed, they may be obtained in the following grades : 15, 17, 
 20, 25, 30, 33, 35, 40, 45, 50, 60, 70, 75, and 80 per cent. In 
 the ammonia dynamites a portion of the nitroglycerine is re- 
 placed by ammonia nitrate, but, as will be seen from the table 
 on page 237, the rated strength of this dynamite is nearly the 
 sum of the percentages of these two constituents. Ammonia 
 dynamite is prepared in the same grades as nitroglycerine 
 dynamite, between 25 and 60 per cent. Owing to the strength 
 of the blasting gelatine being greater than either of its constitu- 
 ents, the rated strength of gelatine dynamite is somewhat greater 
 than the percentage of its explosive element. The usual grades of 
 this dynamite correspond to those of nitroglycerine dynamite 
 
240 MODERN TUNNELING 
 
 between 35 and 80 per cent., but it may also be procured in 
 *'ioo per cent." strength. 
 
 The proper grade for use at any particular tunnel must be 
 determined solely by local conditions. Such widely divergent 
 results are obtained at different localities when using the same 
 grade of explosive and in rock which, as far as can be deter- 
 mined from its physical appearance and structure, is identical, 
 that it is impossible to be dogmatic even with minute knowl- 
 edge of local details. Generally speaking, however, a tough, 
 close-grained, igneous rock will require a stronger explosive, 
 while a sedimentary rock, or an igneous rock that has been 
 altered and weathered, or perhaps shattered and broken, can 
 be blasted just as effectively with a lower grade of dynamite. 
 A notable example of the use of an extremely high-grade ex- 
 plosive is that of the Roosevelt tunnel, where in the tough, 
 close-grained. Pike's Peak granite "100 per cent." gelatine 
 dynamite was required before satisfactory results were obtained. 
 This is reported to have been the first ''100 per cent." dynamite 
 put to use in tunnel work. In all cases it is advisable to ex- 
 periment at the beginning of the work with explosives of different 
 strengths in order to determine which grade is best suited for 
 the particular rock being penetrated, and it is, of course, obvious 
 that similar experiments should be repeated whenever, owing 
 perhaps to a change in the character of the rock, the dynamite 
 used fails to give satisfactory results. 
 
 The practice of loading the bottom portion of the hole with 
 80 and even 100 per cent, dynamite and using 40 or 60 per cent, 
 in the remainder is not now uncommon, especially in tunnels 
 and adits in the Western States. It has the advantage of pro- 
 ducing a greater disruptive force at the bottom of the hole, where 
 such force is most needed, and at the same time it reduces some- 
 what the cost of explosives, especially when an excessive amount 
 of lower-grade dynamite had hitherto been required. There is 
 entailed, of course, the trouble of handling two different kinds 
 of dynamite, not only in the heading but in the thawing-house 
 as well. Although in some cases where this procedure was tried 
 the same results might possibly be achieved by the use of shorter 
 
BLASTING 
 
 241 
 
 rounds, an alteration in the type of cut, or some other change in 
 method, still it is a very useful practice, especially for exceed- 
 ingly hard, tough rock. 
 
 The following table shows the grades of dynamite employed 
 at various tunnels: 
 
 DYNAMITE USED AT VARIOUS TUNNELS 
 
 Carter 
 
 Catskill Aqueduct: 
 
 Rondout 
 
 Wallkill 
 
 Moodna 
 
 Central 
 
 Gold Links 
 
 Gunnison 
 
 Laramie-Poudre 
 
 Lausanne 
 
 Los Angeles Aqueduct 
 Little Lake 
 
 Grapevine 
 
 Elizabeth Lake .... 
 
 Lucania 
 
 Marshall-Russell .... 
 
 Mission 
 
 Newhouse 
 
 Nisqually 
 
 Rawley 
 
 Raymond 
 
 Roosevelt 
 
 Siwatch , 
 
 Snake Creek , 
 
 Stilwell 
 
 Strawberry 
 
 Utah Metals 
 
 Yak 
 
 Gelatine 
 
 Gelatine 
 Gelatine 
 Gelatine 
 Gelatine 
 Gelatine 
 Gelatine 
 Gelatine 
 
 Gelatine 
 
 Gelatine 
 
 Ammonia 
 
 Gelatine 
 Gelatine 
 Gelatine 
 Gelatine 
 Gelatine 
 
 Gelatine 
 Gelatine 
 
 Gelatine 
 Gelatine 
 Gelatine 
 Gelatine 
 
 Gelatine 
 Gelatine 
 Gelatine 
 Gelatine 
 
 40 
 
 60 
 60 
 
 75 
 40 
 40 
 40 and 60 
 60 
 
 60 
 
 40 
 
 40 
 
 40 
 
 50 
 40 and 80 
 40 and 60 
 
 40 
 
 40 
 40 and 60 
 
 40 and 60 
 
 40, 60 and 100 
 
 40 
 
 40 
 
 40 
 
 40 
 
 40 and 60 
 
 40 
 
 Some 80% 
 
 A small amount of 60% 
 Mostly 60% 
 Some 100% with the 
 60% in cut holes 
 
 Some 25% and some 
 
 60% 
 Some 60% and 75% 
 
 gelatine 
 Tried 60% & 70% also 
 
 80% also 
 
 100% with 40% in cut 
 holes occasionally 
 
 60% in cut holes and 
 lifters 
 
 Some 35% and some 
 60% 
 
 It is obviously impossible to make any set rule for the deter- 
 mination of the proper amount of explosive to be employed in 
 tunnel work, without special reference to given conditions. There 
 are entirely too many variable factors, governed solely by local 
 conditions, which control the fitness of quality and quantity, and 
 
242 MODERN TUNNELING 
 
 which cannot be foreseen. Various writers have derived from 
 theoretical considerations formulas for the calculation of the 
 proper charge of explosive for a blast hole, but the application 
 of these rules is limited to other types of blasting, such as quarry- 
 ing or general mining, and they are not suited to the practical 
 and actual conditions of tunnel work. For this, the determi- 
 nation of the proper amount of explosive is often left to the 
 judgment of the foreman in charge, who, if he be widely ex- 
 perienced, can often produce excellent results; but the proper 
 amount can best be ascertained by a series of experiments in 
 which the effects produced by different quantities of explosive 
 are studied and compared. 
 
 It is very essential, however, that the charge of explosive 
 be large enough. If it is too small and the cut-holes fail to break 
 bottom, or the rest of the holes do not blast out their full share 
 of rock,, it will be necessary to reload the remaining portion of 
 them; this procedure not only requires fully as much explosive 
 as if the holes had been properly charged in the first place, 
 but also occasions a loss of time and footage, both of which 
 are most expensive. For this reason, in a number of tunnels, 
 it was customary to load the cut-holes nearly to the collar. 
 Although this is perhaps extreme, as far as insuring that the 
 cut-holes break bottom is concerned, the extra dynamite helps 
 to shatter the rock in finer fragments, thus making it easier 
 for the shovelers to handle. Also, since no tamping is usually 
 employed in such cases, a certain amount of the explosive prob- 
 ably acts in that capacity and increases the efficiency of the 
 remainder of the charge. The very common practice of loading 
 the lifters entirely full has a very different object in view — 
 that of throwing the major portion of the debris some distance 
 away from the new face of the heading, thus making it easier 
 for the drill-men to get their machines at work promptly, and 
 by scattering the rock over a greater area the shovelers can 
 attack it to better advantage. ' Such a practice is highly to be 
 commended. 
 
 Data as to the exact amount of explosive actually employed 
 in practice are difficult to obtain, chiefly because at many places 
 
BLASTING 243 
 
 an accurate record of powder consumption is not kept; but 
 figures were secured wherever possible at the tunnels visited. At 
 the Gunnison tunnel an average of nearly 30 pounds of 40 per 
 cent, and 60 pounds of 60 per cent, gelatine dynamite were 
 employed per round. This is equivalent to approximately 5.5 
 pounds per cubic yard excavated. In driving the south heading of 
 the Elizabeth Lake tunnel, the average for 1909 was 32.09 
 pounds * of explosive per foot of tunnel, which is equivalent to 
 6 pounds per cubic yard. This figure, however, includes the 
 dynamite used in trimming, hence it is somewhat higher than 
 the amount actually needed in driving. At the Rondout Siphon, 
 175 to 200 pounds per round were required to drive an average 
 of 10 feet,t with a heading of approximately 120 square feet 
 area — which is equivalent to 3.9 to 4.5 pounds per cubic yard 
 of rock excavated. 
 
 In advancing the heading of the Buffalo Water tunnel, 4.8 
 pounds of 60 per cent, dynamite were required per cubic yard. 
 At the Laramie-Poudre tunnel, the powder consumption per cubic 
 yard for March, 191 1, was 3.9 pounds; for April, 4.7 pounds, and 
 for May, 4.9 pounds. The average on the Little Lake Division 
 of the Los Angeles Aqueduct for May, 191 1, was 4.5 pounds per 
 cubic yard. At the Wallkill Siphon the average powder con- 
 sumption per cubic yard ranged from 4.3 to 4.6 pounds. At 
 the Yonkers Siphon the powder consumption was approximately 
 4.5 pounds per cubic yard excavated. 
 
 The figures for the explosive used in the Simplon and the 
 Loetschberg tunnels are somewhat higher. At the Simplon 
 tunnel the charge was 6.5 pounds per cubic yard,t while at 
 the Loetschberg tunnel the charge per round to secure an average 
 advance in the 6.5 by ten-foot heading of approximately 3.5 
 feet was 53 to 57 pounds. § This is equivalent to 6.5 to 7 pounds 
 per cubic yard. 
 
 * Mines and Minerals, September, 1910, p. 102: "The Elizabeth Lake 
 Tunnel," C. W. Aston. 
 
 1[ Engineering Record, January i, 1910, p. 26: "Progress on the Rondout 
 Pressure Tunnel," J. P. Hogan. 
 
 t Saunders, W. L., Trans. Am. Inst. Min. Eng., July, 1911, p. 515. 
 
 § Saunders, W. L., loc. cit. 
 
244 MODERN TUNNELING 
 
 The usual means of firing blasting charges, especially in 
 tunnels and adits in the Western States, is by the use of a safety 
 fuse. The term safety fuse originated from the fact that when 
 properly used under working conditions this fuse burns at a 
 uniform rate and does not flash or explode, as was often the case 
 with the means employed for igniting blasting charges previous 
 to its invention; but the term is somewhat misleading, because 
 this fuse is not, nor has it ever seriously been claimed to be, 
 safe for use in gaseous coal mines. The fuse used for tunnel work 
 is universally of the waterproof type, composed of a core of 
 gunpowder surrounded by various layers of waterproofing ma- 
 terial. In one sample, examined by the Bureau of Mines, "the 
 core consists of a powder train and one white cotton thread; 
 the inner covering consists of ten hemp threads; the inner- 
 middle covering consists of five fine cotton threads impregnated 
 with an asphaltic composition; the middle covering and the 
 middle-outer covering each consists of a S/s-inch cotton tape 
 impregnated with an asphaltic composition, and the outer cov- 
 ering consists of a K-inch cotton tape covered with whiting. 
 Each covering of tape is wrapped in reverse order." * 
 
 In other samples the hemp threads of the inner covering 
 are replaced by cotton threads impregnated with sodium sili- 
 cate; the inner middle covering is often omitted; the asphalt 
 composition of the middle covering is replaced by gutta percha; 
 the middle outer covering is also omitted, and intervowen 
 cotton threads are substituted for tape in the outer covering. 
 The weight of powder in different types of waterproof fuse 
 varies from 50 to 220 grains per foot, the majority of which 
 is finely granulated, and will pass through a 60-mesh sieve. 
 
 Under ordinary conditions a safety-fuse burns at a uniform 
 rate, with a variation rarely greater than 10 per cent., fast or 
 slow. In European countries the normal rate is approximately 
 thirty seconds per foot. According to tests conducted by the 
 Bureau of Mines on fourteen samples of triple tape fuse pur- 
 chased for the Isthmian Canal the average rate was determined 
 
 * United States Bureau of Mines, Technical Paper 7, p. 7. 
 
BLASTING 
 
 245 
 
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246 MODERN TUNNELING 
 
 as 26 seconds per foot for three-foot lengths and 24.5 per foot 
 for fifty-foot lengths. This rate is much slower than that of 
 the fuse commonly employed in Western tunnel work, forty to 
 forty-five seconds per foot being the customary rate of burning 
 for fuse used there, although these figures are not the results of 
 tests. Such a test was made at the Strawberry tunnel, however, 
 with the results shown in table on page 245. 
 
 Experiments conducted by the Bureau of Mines * prove 
 conclusively, however, that the normal rate of burning of fuse is 
 greatly changed by a number of conditions. Excess of pressure 
 greatly accelerates it, and if the gases are sufficiently confined 
 the increase may be as great as 300 to 400 per cent. Although 
 as great an increase as this would rarely be obtained in practice, 
 the use of tamping which is too tightly packed or which is 
 impervious to the escaping gases may produce sufficient pressure 
 to increase greatly the rate at which the fuse burns. When fuse 
 is exposed to low temperature for a short time the rate is slightly 
 increased, but if it be stored at temperatures below freezing 
 and handled before being warmed, cracks are apt to result in 
 the waterproof composition which will permit the gas to escape, 
 and thus, reducing the normal pressure, retard the speed of the 
 fuse. Storage at high temperatures, however, causes a marked 
 retardation which is apt to cause delayed shots and misfires, 
 and fuse should, therefore, never be stored near boilers or other 
 places where the temperature is high. Moisture seriously im- 
 pairs the efficiency of fuse which should be carefully protected 
 from it. Although the train of powder is covered with a water- 
 proof covering throughout its length, the powder exposed at the 
 end readily absorbs moisture and the cotton or hemp threads 
 in the center act in the capacity of sponges, so that the fuse for 
 a foot or so from the end may be impregnated with moisture. 
 When the fuse is Kghted, this water is driven ahead of the fire 
 in the form of steam and delays the burning of the fuse, and, if 
 there is enough of it, sometimes becomes concentrated and 
 extinguishes the fuse entirely. Although twisting and bending 
 
 * Technical Paper No. 6. 
 
BLASTING 
 
 247 
 
 apparently have but little effect upon the rate of burning, 
 mechanical injury, such as pounding or crushing by falling 
 rock, and abrasion such as might result from the tamping 
 stick when consolidating the charge, greatly increase the rate. 
 The results of these experiments show most conclusively that 
 the greatest care should be taken in the storage and han- 
 dling of fuse to prevent accidents from premature or delayed 
 explosions. 
 
 Detonators or blasting caps consist of a copper cylinder 
 closed at one end and about the diameter of an ordinary lead 
 pencil, into which is packed some dry mercury fulminate and 
 potassium chlorate. When used with a safety fuse, the end 
 of the fuse is inserted in the open end of the copper cylinder, 
 which is then crimped around the fuse by the use of suitable 
 pliers. Under no conditions 
 should anything but the proper 
 tool be used for this purpose, be- 
 cause the fulminate of mercury is 
 extremely sensitive to very slight 
 shocks, and there is sufficient 
 strength in a single detonator to 
 produce disastrous results if dis- 
 charged accidentally. In some 
 tunnels, more especially those in 
 the Eastern States, the detona- 
 tors are ignited directly by an 
 electric current. For this purpose, 
 special electric detonators are re- 
 quired in which the fuse is re- 
 placed by two suitably insulated 
 copper wires joined at the inside 
 end by a bridge of fine platinum 
 or other high-resistance wire 
 capable of becoming incandes- 
 cent during the passage of an 
 
 electric current; these are inserted in an ordinary detonator 
 into which some gun-cotton has previously been placed. Caps 
 
 Gun Cotton c 
 
 Mercury Pulminate 
 
 (loose) 
 
 Fig, 64. Section through an 
 electric detonator. 
 
248 MODERN TUNNELING 
 
 prepared in this manner are called electric detonators and may 
 be secured from the manufacturers with wires of varying 
 lengths, as required. 
 
 Figure 64 shows the component parts of one of these 
 detonators. 
 
 The strength of detonators is determined by the weight of 
 mercury fulminate they contain, and they are generally desig- 
 nated as triple X, quadruple X, etc. 
 
 The following table shows the weights of charge used in the 
 different grades: 
 
 WEIGHTS OF DETONATOR CHARGES 
 
 Commercial Grades Weight of charge in grains 
 
 3 X — or triple 8.3 
 
 4 X — or quadruple 10 . o 
 
 5 X — or quintuple 12.3 
 
 6 X — or sextuple 15.4 
 
 7 X — or No. 20 23 . 1 
 
 8 X — or No. 30 30 • 9 
 
 WEIGHTS OF ELECTRIC DETONATOR CHARGES 
 
 Commercial Grades Weight of charge in grains 
 
 Single strength 12.3 
 
 Double strength 15.4 
 
 Triple strength 23.1 
 
 Quadruple strength 30 . 9 
 
 The detonator chosen for blasting in tunnel work should be 
 strong enough to produce complete detonation. With straight 
 nitroglycerine dynamite 3 X caps were considered heavy enough, 
 but with gelatine dynamite it is necessary to use much stronger 
 ones because this dynamite is not nearly so sensitive (which 
 makes it, of course, safer to handle). The jelly-like mass of 
 the gelatine dynamite also has a tendency to retard the explosive 
 wave as it passes along the bore-hole, and therefore requires a 
 much stronger initial explosion to carry the wave with the 
 same force through the entire length of the charge. The leading 
 manufacturers all recommend nothing weaker than 6 X caps 
 
BLASTING 249 
 
 for gelatine d3mamite. Although 5 X caps have given results 
 which were thought to be sufficiently satisfactory at some 
 tunnels, at others, where a change was made to those of greater 
 strength, the universal experience has been that the better 
 results more than warranted the change, the common report 
 being that ''it pays." It is, therefore, here recommended that 
 nothing weaker than 6 X detonators (or double-strength electric 
 detonators) be used with gelatine dynamite, which is practically 
 the only kind employed in tunnel work. In addition to the 
 more effective results produced by the higher-strength caps, the 
 composition of the gases is greatly changed when detonation 
 is not complete, and unsuspected and dangerous constituents 
 may result. As we have seen, with complete detonation the 
 gases are mainly carbon dioxide and nitrogen, with, perhaps, a 
 small amount of carbon monoxide. With incomplete detonation 
 a much greater percentage of dangerous carbon monoxide is 
 formed from the nitroglycerine, and, in addition, the toxic 
 peroxides of nitrogen are produced in larger or smaller amounts, 
 according to varying degrees of completeness of the reaction. 
 
 LOADING 
 
 There has been much discussion lately regarding the proper 
 position for the primer (as the particular cartridge of dynamite 
 containing the detonator is called) when loading a blast hole; 
 some arguing that it should be the last cartridge to be placed 
 in position, while others claim the only proper place for it is 
 at or near the bottom of the hole. One of the more common 
 arguments for placing it at the top instead of the bottom of the 
 hole is the fact that by so doing one removes the danger of 
 igniting the dynamite from the side-spitting of the fuse, in which 
 case not only is the full efficiency of the explosive not obtained, 
 but the resulting gases are much more virulent and dangerous. 
 For it is obvious that when the fire in the fuse is compelled to 
 travel past the full length of the charge, the danger of the flame 
 bursting through the waterproof covering and igniting the dyna- 
 mite is a rather serious matter. We are informed, however, by 
 an expert connected with one of the leading explosives manufac- 
 
250 MODERN TUNNELING 
 
 turing companies, that gelatine dynamites (which, as we have 
 seen, are the kind generally used in tunneling) are less liable 
 to be deflagrated in this manner than any of the others. The 
 objection (which, however, is not apphcable when electric de- 
 tonators are used) is worthy of serious consideration when safety 
 fuse is employed. 
 
 A second argument in favor of placing the cartridge last is 
 the fact that the dynamite charge is much more apt to be packed 
 firmly, thus eliminating air spaces which decrease the effective- 
 ness of the explosive. For when the primer is the first or the 
 second cartridge in the hole, the remaining cartridges, and 
 especially the one immediately following, cannot properly be 
 pressed in place with safety, and air spaces are quite likely to 
 be left. This, of course, applies equally to charges detonated 
 by safety fuse or electricity. 
 
 A third argument, and one that seems to have been over- 
 looked in the recent discussion, is the fact that the detonation 
 of a charge of dynamite in a bore-hole takes place in a series 
 of steps which follow one another with almost inconceivable 
 rapidity, but which are nevertheless distinct. The first of 
 these is the explosion of the cap, which in turn detonates the 
 dynamite in the primer and causes what may be termed the 
 primary explosion, which in turn is communicated to the re- 
 mainder of the charge. Although, by employing a strong cap 
 the amount of dynamite detonated in the primary explosion 
 can be greatly increased, it can never be large enough to disrupt 
 the rock completely, the greater force of the secondary explosion 
 being required for this purpose. If, then, the cartridge contain- 
 ing the detonator is placed at the bottom of the hole and fired, 
 the primary explosion consumes the dynamite ineffectually at 
 the bottom of the hole where the full force of the blast should 
 be used; consequently, there is much greater danger of losing 
 the last eight or ten inches of the round, with a consequent 
 decrease in daily advance. It is also claimed that in placing the 
 primer at the bottom, the explosion of the detonator tends to 
 force a certain amount of the charge from the hole; this, how- 
 ever, is debatable. But if the primer is placed at the top, the 
 
BLASTING 251 
 
 primary explosion does not destroy explosive that is essential 
 and the full strength is developed from the remaining portion of 
 the explosive, except in so far as it is influenced by the hindrance 
 to the explosive wave caused by the use of gelatine dynamite 
 previously referred to. And again, by placing the primer at the 
 top, during the primary explosion a certain amount of pressure 
 is developed and the remainder of the charge is, therefore, deto- 
 nated under that greater pressure, hence its effectiveness is 
 increased. This applies particularly where tamping is employed, 
 and it requires only two or three inches of clay tamping to pro- 
 duce the results. If clay is not used, an extra stick of dynamite 
 placed on top of the primer, which acts partly in the same 
 capacity, is of great assistance. 
 
 On the other hand, it is claimed that when the primer is 
 placed on top of the charge the collar of the hole is apt to be 
 knocked off by the explosion of a neighboring charge. There is 
 some question as to whether this really would happen, but if it 
 did it would be a very strong indication either that the hole 
 was misplaced or that it was too heavily loaded; for, as some 
 one has said, "Certainly the collar of a hole is no place for 
 dynamite." And as to the objection that when the primer is 
 placed at the top the fuse is liable to be torn out by flying rocks, 
 the remedy is a very simple one — that of coiling the fuse care- 
 fully close up to the hole. And finally, if the wave does not 
 travel with enough force to the bottom of the hole, the matter 
 can be remedied by the use of a strong detonator, or by employ- 
 ing a higher grade of explosive, which would have the double 
 effect of producing a greater primary explosion and of lessening 
 the length of the charge, since less explosive would be required. 
 
 It is clearly recognized by the authors that, in some sec- 
 tions of the country at least, the practical miners are accustomed 
 to place the primer at the bottom. But it does not necessarily 
 follow that a practice is correct because the miners so consider 
 it, for many of them also think that dynamite exerts a greater 
 influence downward than in any other direction. Therefore in 
 view of the several considerations outhned above, it would 
 appear that the primer should be placed near the top of the charge. 
 
252 MODERN TUNNELING 
 
 The use of tamping in tunnel work is also a mooted question. 
 Where low explosives, such as blasting powder having a slow rate 
 of explosion, are employed, tamping is of course absolutely essen- 
 tial in order to confine the gases long enough for their full strength 
 to become effective. But with dynamite whose detonation is 
 extremely rapid, almost instantaneous, it is believed by many 
 persons that tamping is not required, and this belief seems to 
 be warranted by the actual experience that good results can 
 be obtained without its use. A possible explanation for this is 
 the fact that in tunnel work the holes are generally overloaded, 
 and hence the pressure produced by the extra few inches of dyna- 
 mite charge tends to confine the gases generated by the remain- 
 ing and effective part of the charge, which is of course also the 
 function of tamping. Another probable reason is that the inertia 
 of the column of air in the bore-hole acts as a partial substitute 
 for tamping of some more solid material. This can be demon- 
 strated by exploding dynamite lying uncovered upon some 
 flat surface in the open, and it is this fact, doubtless, that has 
 given rise to the belief that dynamite exerts more force down- 
 ward than in any other direction. It is unanimously admitted, 
 however, by experts who have studied the subject, that better 
 results can be secured from any properly loaded hole when more 
 substantial tamping is employed. The amount required depends, 
 of course, upon the rate of detonation of the explosive. With 
 black blasting powder it may be necessary to fill nearly all the 
 remaining portion of the hole in order that the tamping may not 
 be forced out before the reaction is complete and the full strength 
 of the gases produced; but with ordinary charges of gelatine 
 dynamite from two to six inches of well-packed clay will in most 
 cases be fully sufficient. 
 
 The use of tamping in tunnel work has several disadvantages 
 which, in the opinion of many, if indeed not a majority, of tunnel 
 men, more than counterbalance any gain in efficiency of explosive 
 from its use. In the first place, it causes delay in loading the holes 
 at a time when every minute is precious. Again, the majority of 
 miners and especially those in the Western States, are strongly 
 biased against it, and any one who has tried to overcome one of 
 
BLASTING 253 
 
 their prejudices will appreciate the difficulty that would be expe- 
 rienced in getting them to use the tamping. While, of course, if 
 tamping, were absolutely essential to good results, mere prejudice 
 on the part of any one should not be allowed to stand in the 
 way of its adoption, still, as this is not the case, the wishes of 
 the miners are usually deferred to. But a more serious disadvan- 
 tage of the use of clay or similar material for tamping is the 
 danger attendant upon its removal in case of a missed hole. This 
 is a prolific source of accident. But if the tamping consists of 
 an extra stick of dynamite, as is usually the case in tunnel work, 
 the simple insertion of a primer on top of the unexploded charge 
 is all that is needed to prepare the hole for re-firing. For these 
 reasons, then, although tamping is essential in a bore-hole that 
 is not overloaded, for tunnel work in which it is customary to 
 use more rather than less ''powder" than is required, it is not 
 so necessary that clay, sand, or similar tamping be employed. 
 
 Among other things to be considered in connection with the 
 loading of a blast hole is the necessity of having the dynamite 
 properly thawed. This is required, not only by due regard for 
 the safety of the men (which alone should be more than sufficient) , 
 but also because frozen dynamite cannot be properly packed in 
 the hole, and air spaces cannot, therefore, be avoided, nor is the 
 full force of frozen dynamite developed upon detonation, hence 
 there is a decided loss in effectiveness. It is also very desir- 
 able that the cartridges correspond as closely as possible in diam- 
 eter to the size of the drill hole, and that the paper shall be slit 
 (carefully, of course) along the side with a sharp knife just before 
 they are placed in the hole. This enables the explosive to con- 
 form to any irregularities in the shape of the hole. The position 
 of the detonator in the priming cartridge also deserves attention. 
 Experiments have shown that the maximum force from a deto- 
 nator is developed in the direction of its length. For this reason 
 the detonator should be inserted into the end of the cartridge 
 and not obliquely in one side, as is often the case in tunnel 
 practice. Nor should the fuse project into or be laced through 
 the cartridge because of danger of setting fire to the cartridge, 
 instead of detonating it properly with the cap. 
 
254 MODERN TUNNELING 
 
 FIRING 
 
 When the number of holes to be fired is large, the work of 
 lighting the fuses is generally done by two men, but when there 
 are but few holes in the round, one man is sufficient. When two 
 men do this work it is customary for each man to light the fuse 
 of a corresponding hole (for example, opposite cut holes, etc.), at 
 the same time, each calling out the hole as he lights it. The actual 
 ignition of the fuse (which should be closely coiled and the free end 
 split for one-half to three-fourths of an inch to expose the powder 
 train) is accompHshed in various ways. At some places a candle 
 is used, and at others an acetylene lamp. The much better prac- 
 tice, however, is to use a ''spitter," as it is called, consisting of a 
 short piece of fuse which has been slashed and partially severed 
 at regular intervals of perhaps one-half of an inch, and the powder 
 train exposed. When the end of such a spitter is ignited the fire 
 travels along it and as it reaches one of the cuts it spits violently 
 out of the side, which if directed toward a fuse is almost certain 
 to ignite it properly. Each fuse should be ignited separately, 
 instead of bunching several of them, and attempting to ignite 
 them all at once, as is unfortunately sometimes done. When it 
 is necessary to protect the ends of the fuse from water by cover- 
 ing it with anything convenient, an empty powder box is fre- 
 quently employed. 
 
 In extremely wet tunnels it is sometimes necessary to use a 
 fuse igniter. One form of igniter that has given excellent results 
 at a number of places where tried consists of a short cylinder 
 of celluloid of the same diameter as the outside of standard 
 fuse, which is closed at one end, and contains a small amount of 
 gunpowder or some similar explosive substance. The other end 
 is slipped over the free end of the fuse which, instead of being 
 split, is cut square, and the igniter fits the fuse tightly enough 
 to be held in place by friction. When being lighted the igniter 
 is, of course, protected from any falKng water, and the celluloid 
 is set on fire by a candle or some other flame; since it is unaf- 
 fected by mere dampness, it burns until the powder charge is 
 reached, when a flash takes place which seldom fails to start the 
 
BLASTING 255 
 
 fuse. These igniters are not expensive, and are exceedingly 
 useful in wet work. 
 
 When ordinary electric detonators are employed, the only 
 operations required are those of connecting the wires and passing 
 a current through them by closing an electric-Kght circuit, or 
 by generating a current in a so-called ''battery," which consists 
 of a hand-operated magneto or dynamo. In this case, all the 
 holes so connected are exploded simultaneously, and this is the 
 chief and most serious disadvantage of electric firing for tunnel 
 work. As we have seen, the blasting in tunnel headings, to 
 be effective, must take place in several steps; the cuts first, 
 followed by the reHevers, backs, sides, and Kfters. Therefore, 
 with electric blasting, although it has the advantage of shooting 
 the cuts simultaneously, it is necessary for some one to return 
 to the heading and connect up the wires leading to the charges 
 in the holes to be fired in each of the succeeding steps; and as 
 it always requires a certain amount of time in order to permit 
 the smoke to clear, and oftentimes no little shoveling is required 
 to uncover wires which have been buried by a previous round, 
 it takes much longer to blast a round in this manner. 
 
 Manufacturers of blasting suppHes are trying to perfect a 
 delay-action detonator, in order to overcome this defect. This 
 resembles ordinary electric detonators, except that the platinum 
 bridge does not ignite the mercury fulminate directly, but sets 
 fire to a short train of gunpowder inside of the cap, which 
 requires an appreciable, although short time, in burning before 
 it reaches the detonating portion. By making the powder train 
 of two different lengths, two delays are obtained which, if used 
 in connection with a detonator not containing a powder train, 
 enables the blasting to be performed in three stages from a single 
 connection of the wires and from but one closure of an electric 
 current. When using these devices in tunnel work an instan- 
 taneous detonator is usually placed in the cut holes, a "first 
 delay" in the reHevers, and the "second delay" in the remaining 
 holes. It is unfortunate that these detonators have not as yet 
 been perfected for more than two delays, and this has un- 
 doubtedly prevented their more extensive use for blasting tun- 
 
•256 MODERN TUNNELING 
 
 nel headings. For this work, three stages will hardly give satis- 
 factory results, because a fourth stage is essential for the Hfters, 
 whose function it is to throw the material broken by the other 
 holes from the immediate front of the new face; and with the 
 horizontal-bar mounting a fifth step is also desirable in order to 
 permit one Hfter to go off after the others and throw the material 
 away from the side of the tunnel where the capstan end of the 
 bar is to be placed, thus to afford plenty of room for the operation 
 of the jack bar and permit it to be screwed tightly in place. 
 
 There is, however, now upon the market an electric fuse 
 which will permit of the blasting being conducted in almost any 
 number of steps that may be required. It consists, as does the 
 ordinary electric detonator, of a platinum wire bridge enclosed 
 in a metal cyhnder by a waterproof composition. In the other 
 end of the cylinder (which, instead of being closed and containing 
 mercury fulminate, is left open) a short section of ordinary 
 safety fuse is inserted, crimped in place, and the joint water- 
 proofed. After an ordinary blasting detonator has been placed 
 upon the other end of this piece of fuse and an electric current 
 is passed through the copper wires leading to the platinum 
 bridge, the fuse takes fire and burns until it ignites the detona- 
 tor. By cutting off different lengths from these pieces of fuse 
 before inserting them in the blasting caps, any desired number 
 of delays may be obtained from one connection of the wires and 
 one closure of the electric current. This device, therefore, 
 overcomes the one great disadvantage of electric firing. 
 
 Chief among the advantages of electric firing is the certainty 
 of detonating all of the cut-holes simultaneously. Although, of 
 course, if two holes are connected they will explode as one, it is 
 impossible to make several pairs of cut-holes, in a wedge cut, 
 for example, explode together when fuse firing is employed. 
 There will always be enough variation in the rate of burning 
 of the fuse to prevent it, no matter how exactly the lengths of 
 the fuses are cut. But when the cut-ht)les are detonated simul- 
 taneously, as can be done with electric firing, each can assist 
 the other with a resulting increased effectiveness from the 
 explosive. It is, of course, true that even with electric delay- 
 
BLASTING 257 
 
 action detonations, holes fired on the first and second delay can- 
 not be made to detonate absolutely simultaneously, and even 
 less so with the electric fuse just described; but this is not so 
 essential, since the work of the succeeding holes does not approx- 
 imate that of the cuts. 
 
 Another advantage is the absence of smoke and dangerous 
 gases caused by the burning of fuse. A large percentage of these 
 gases is carbon monoxide, as is shown by the following analysis 
 of gases obtained from burning fuse.* 
 
 ANALYSIS OF GASES PRODUCED BY BURNING OF FUSE 
 
 (A. L. Hyde, Analyst) 
 
 Hydrogen sulphide , 0.8 
 
 Carbon dioxide 32.7 
 
 Oxygen 1.4 
 
 Carbon monoxide 23.4 
 
 Hydrocarbons 4.1 
 
 Nitrogen 23 . 8 
 
 Hydrogen 13.8 
 
 STORING 
 
 The place used for the storage of explosives should be sub- 
 stantially constructed, well ventilated, protected as much as 
 possible from fire or hghtning, and should be kept locked to 
 prevent the entrance of children or irresponsible persons. At 
 mines or quarries the ideal magazine is, of course, one of cement 
 or of brick, but at most tunnels where the work is usually of a 
 more or less temporary character, the cost of such a building is 
 not always justified, and the dynamite is stored usually in a 
 short drift in the side of the hill or in a log house. Where neither 
 of these can be obtained, a frame house will answer the purpose, 
 although of course not so well. But when it is used, it should 
 always be covered with corrugated iron or some similar fireproof 
 material, and care should be taken to remove any small sticks 
 
 * Bureau of Mines, Technical Paper 6. 
 
258 MODERN TUNNELING 
 
 and grass from immediately around it. Where considerable 
 amounts are to be stored, the magazine should be located at 
 some distance from the rest of the work, but in any case the 
 powder should not be kept near enough to the tunnel buildings 
 to cause serious damage to them or to the persons working in 
 them in the event of an accidental explosion. Obviously, dyna- 
 mite should not be stored at all near a dwelHng. 
 
 More than one kind of explosive, as, for example, black blasting 
 powder and dynamite, should not be stored together, but there 
 is no particular objection to the storage of different grades of the 
 same kind of dynamite in the same building, except the possibiKty 
 of confusion which might result from such a practice. Detona- 
 tors, either plain or electric, and fuse should under no circum- 
 stances be stored in the same building with dynamite, nor 
 should the operation of placing caps on safety fuse be conducted 
 at or near the magazine or thaw-house. Tools should never be 
 permitted inside of the magazine, nor should the boxes of dyna- 
 mite be opened there. The floor of the magazine should always 
 be constructed of wood, and it should always be kept free from 
 grit and dirt. 
 
 THAWING 
 
 Most dynamite freezes at a temperature of 45° to 50° F., and 
 it is therefore necessary to thaw it before it can be used. In 
 tunnel work this is generally accompHshed by spreading it out 
 on shelves in a warm room or small building, separate and pref- 
 erably somewhat removed from the main magazine. Where the 
 power for the tunnel work is derived from a steam plant, the 
 waste steam is very often used to heat the thaw-house. In this 
 case, however, it is very essential that the coils be boxed or 
 screened in such a way that it will be impossible for a stick of 
 dynamite to fall upon the pipe, for, becoming ignited from the 
 heat, a serious explosion might result. Nor should the pipes 
 be so placed that any nitroglycerine exuding from the cartridges 
 can fall upon them. Since the thaw-houses are generally insu- 
 lated from the cold by having double walls or by banking earth 
 high against the sides (and hence a great deal of heat is not 
 
BLASTING 259 
 
 required to keep them warm), where electricity is available, a 
 cluster of incandescent bulbs is often used for this purpose with 
 good results. At other tunnels a special heater was observed, 
 which was composed of one or more coils of iron or other high- 
 resistance wire stretched between insulators on a suitable frame- 
 work, usually of wood. When a heater of this type is employed 
 it is much more essential that it be protected from the danger 
 of a stick of dynamite lodging upon the wires because they are 
 generally much hotter than steam coils (a red glow being not 
 uncommon), and hence there is much greater danger of explosion 
 from this source. 
 
 At one of the tunnels visited, however, where otherwise the 
 conditions from the viewpoint of safety were excellent, an 
 unprotected heater of this type was employed, and when comment 
 was made upon the fact that there was no protection, it was 
 stated that this condition was intentional. The reason given for 
 such a course was that any person entering the thaw-house was 
 supposed to turn off the current by means of a switch provided 
 for that purpose, and that the knowledge that the coil was not 
 protected would make the men more careful in seeing that this 
 was done. Such reasoning is all right as far as it goes, but it 
 does not provide for the contingency of a stick of powder falling 
 off the shelves when no one is in the building (although it is 
 granted that this is not so likely to happen as the other); nor, 
 since the wires do not cool off instantly, is it safe in the thaw- 
 house for some little time even after the wires have been dis- 
 connected. Taken in connection with the fact that this par- 
 ticular thaw-house was but a short distance from the tunnel 
 portal, that it had no lock, and that all timber and other tunnel 
 suppHes had to be hauled past it, the situation should have been 
 marked, in the language of insurance, ''extra hazardous." It is, 
 indeed, truly marvelous that it did not occasion some accident 
 during the period of its use. Needless to remark, such a thaw- 
 house and means of heating it are decidedly to be avoided. 
 
CHAPTER XIII 
 METHODS OF MUCKING 
 
 NUMBER OF MEN 
 
 The number of men in the crew which removes the rock 
 broken in blasting exerts a very important influence upon the 
 speed at which the tunnel can be advanced. Where the vertical 
 column or the drill carriage is employed and the remainder of 
 the work cannot proceed until the heading is cleared, every 
 minute saved at this work can be transmuted directly into 
 progress; and while, with the horizontal-bar system, nearly all 
 of the mucking is done simultaneously with the drilHng and 
 the heading can ordinarily be cleared by the time the drillers 
 have finished the upper round of holes, still if the crew of shov- 
 elers is not large enough to accomplish this promptly, the delay 
 is fully as serious. In any event, it is very essential for rapid prog- 
 ress that the muck be removed as speedily as possible, as there 
 are always a great number of little things to be done by the 
 shovelers, even after the main work of loading the debris has 
 been accomplished, for which there cannot be too much reserve 
 time. Further, it is obvious that the removal of the muck in 
 the shortest space can be accomplished only by a nice adjust- 
 ment to conditions and the employment of the exact number of 
 laborers proper for the purpose; for it must be remembered that 
 the space in the tunnel heading is most restricted, and if too many 
 men attempt to work there simultaneously, they will seriously 
 interfere with one another, more than offsetting any possible 
 gain from the employment of the extra men, while if too few men 
 are at work it will be impossible for them to remove the debris 
 in the time allowable. An analysis of the most satisfactory prac- 
 tice at a number of tunnels shows that, under the conditions 
 which prevail in the heading, a man shoveling requires from 
 two and a half to three feet of floor space. That is, for a tunnel 
 ten feet wide, not more than four shovelers should be used 
 
 260 
 
METHODS OF MUCKING 261 
 
 simultaneously, while not more than two men can work to advan- 
 tage side by side in a six-foot heading. In addition to these, how- 
 ever, it is very desirable to have a man or two at work picking 
 down the rock pile in front of the shovelers, loosening boulders, 
 assisting in the handling of the cars, or doing any of the many 
 other things that make for speed in loading the muck. Accord- 
 ingly, at tunnels from six to ten feet. in width, the proper number 
 of men in the mucking crew ranges from three to eight. 
 
 At the Loetschberg and other of the European tunnels two 
 sets of muckers were employed, one of which would rest while 
 the other was engaged in loading the car. This course was 
 thought to be conducive to greater speed, because the men could 
 work much harder for the few minutes it took to load a car if 
 they had an equal time to rest during the loading of the next 
 one. There is but httle if any doubt that this is true or that 
 the heading can be cleared sooner when such a method is used, 
 but because of the higher cost of labor in this country, especially 
 in the Western States, it is greatly to be questioned whether the 
 gain would be sufhcient to make such procedure profitable. At 
 the Loetschberg tunnel the shovelers received a daily wage of 
 80 cents * as compared with the % or $3.50 for Kke work in the 
 western part of the United States, so that a double crew of but 
 five shovelers (similar to those of the Loetschberg tunnel) would 
 entail in this country an extra cost of from $15 to $17.50 per 
 sliift, as compared with $4 in Europe. Since the advance per 
 shift in America rarely exceeds 7.5 feet, the extra cost of the 
 double-crew system would amount to at least $2 per foot of tun- 
 nel driven. This would be justified only if it obviated a corre- 
 sponding burden of delay, although even in that event the ques- 
 tion could properly be raised whether a change or adjustment 
 in some other phase of the work was not the better solution and 
 desideratum. 
 
 POSITIONS OF WORKING 
 
 The advantage of giving the men a rest from the grind of 
 steady shoveling can be obtained, however, without the necessity 
 
 ♦Saunders, W. L.: Bull. A. I. M. E., July, 191 1, p. 532. 
 
262 MODERN TUNNELING 
 
 of extra laborers, by changing their positions regularly, according 
 to the system in use at several of the tunnels visited while secur- 
 ing the material for this book. At the Laramie-Poudre tunnel, 
 where one of the best examples of this method was observed, the 
 six muckers worked according to the following cycle of opera- 
 tions: As soon as a car (i) was filled with waste, two shovelers, 
 who will be designated as A and B, took it at once to the rear, 
 while two other shovelers, C and D, jumped to an empty car 
 (2) near by (which had previously been thrown off the track on 
 its side), set it upright on the track, and pushed it into a position 
 to be filled. In the mean time, the remaining men, E and F, 
 stopped picking down the rock pile, took the shovels left by A and 
 B, and started at once to assist C and D in filling car 2. Another 
 car (3) was then brought up by A and B as near as possible to 
 the car (2) being filled, and thrown off the track on its side in 
 the position formerly occupied by the second car. These men 
 then picked down the rock pile for the other four during the 
 remainder of the time consumed in loading car 2. When filled, 
 this car was removed by C and D, while E and F set up the third 
 car and filled it with the assistance of A and B. The fourth empty 
 car was meanwhile brought up by C and D, who then took their 
 turn at picking down, and the cycle was completed when E and 
 F took the third loaded car to the rear, returning with another 
 empty and then resumed their original position on the muck 
 pile. It will be seen that by this method every man spent at 
 least one-third of the time in tramming or picking down the rock 
 pile, either of which was easier work than that of shoveling and 
 amounted virtually to a rest which, although perhaps not so 
 complete as if no work at all had been done during that period, 
 was still sufficient to relieve greatly the hard monotony of 
 shoveling. 
 
 The regularity and mechanical exactness of procedure with 
 this system are still more important advantages. Each man soon 
 learns precisely what is expected of him for each step of the 
 operation, and hence there is absolutely no confusion, no lost 
 motion. There is rarely any occasion for the foreman to give 
 an order to the men except under unusual circumstances, and in 
 
METHODS OF MUCKING 263 
 
 consequence he does not acquire the habit of shouting at the 
 men constantly, an unfortunate phase of this work only too 
 noticeable at some of the tunnels visited; nor, on the other hand, 
 do they form the time-wasteful habit of running to him for 
 guidance at every minor contingency that arises. The statement 
 that the little things make for success is not claimed as original, 
 but it can nowhere apply better than in planning the utmost 
 work attainable in the limited space of a tunnel heading; indeed, 
 this seeming detail of eliminated friction and confusion warrants 
 and deserves the most serious consideration. 
 
 In addition to advantages in organization, the speed attain- 
 able with this method leaves little, if indeed anything, to be de- 
 sired. Cars of 1 6 cubic feet capacity were filled at the Laramie- 
 Poudre tunnel ordinarily in three or four minutes, and on one 
 occasion (which, however, was somewhat exceptional, as the 
 men reahzed that they were being timed) but one minute and 
 thirty seconds were needed. At the Rawley tunnel, where a 
 similar system was used with but four muckers, twenty-five cars 
 having a capacity of 17 cubic feet were filled in exactly two hours, 
 and on a different shift twenty cars were loaded in one hour and 
 forty-five minutes. These figures are from an accurately timed 
 record kept by one of the authors. The usual time required for 
 mucking at the Rawley tunnel is not far from the average of 
 these figures (which also include all ordinary delay incident 
 to making the cars up into trains), a value somewhat less than 
 six minutes per cubic yard of rock loaded. This does not suffer 
 by comparison with the Loetschberg tunnel, where five minutes 
 were required to fill a cubic-meter car (35.5 cubic feet) * by a 
 crew of ten men, with an extra minute to remove it when full 
 and replace it with an empty one. 
 
 HANDLING CARS 
 
 The method of handhng the tunnel cars is still another detail 
 of consequence in the operation of mucking. One of the most 
 common arrangements is to have them trammed from the face 
 
 * Saunders, W. L.: Bull. A. I. M. E., July, 191 1, p. 535. 
 
264 MODERN TUNNELING 
 
 by hand to a siding or switch where they are made up into trains 
 and hauled to the portal by whatever means are provided for 
 that purpose. This system, however, possesses some disadvan- 
 tages. The switch must be moved frequently at no little expense 
 and trouble in order to keep pace with the tunnel advance or 
 else it will soon be so far from the face that it is practically worth- 
 less. There is considerable loss of time while the loaded cars are 
 being removed and the empty ones are being brought to the face, 
 which it is impossible to avoid; even though every effort be 
 made to reduce this time to the minimum, the switch cannot 
 well be located nearer than loo feet from the face, while in prac- 
 tice 300 to 500 feet is more apt to be the actual distance. More- 
 over, the full car must be taken usually by hand the entire dis- 
 tance to the switch before the "empty" can pass it; when this 
 system is employed, heavy cars, almost without exception, are 
 used (for reasons we shall show later), and, on this account, to 
 move them any distance by hand entails a heavy drain upon 
 the exertions of the mucking crew. 
 
 At some tunnels this difficulty was obviated by extending 
 two tracks all the way to the face and loading cars on each one 
 alternately. Even this is not entirely satisfactory, because it 
 requires the extra labor and trouble of laying two tracks instead 
 of one, which must be done after the tunnel is cleared of debris 
 and before the new round is fired, and is therefore very apt to 
 cause a serious delay in the whole work, especially if the shovelers 
 are a httle late in clearing the heading. In addition, the need 
 for keeping the switch as close as possible to the face is not so 
 apparent with this method as with the first, and hence this most 
 necessary work is apt to be neglected. In that event a large 
 amount of time will be wasted in the course of a shift by the 
 men tramming the cars an extra distance. And, of course, it 
 only partially obviates the danger of derailments to the cars in 
 crossing the switches, which is often a notable cause of lost 
 time and trouble. 
 
 At one tunnel the necessity for a double track was avoided 
 by covering the entire floor of the heading with steel plates for 
 about thirty or forty feet back from the face. The cars to be 
 
METHODS OF MUCKING 265 
 
 loaded could easily be jumped from the track on to the first of 
 these plates and rolled as near the rock pile as necessary, and 
 when one car was full an empty one could be shunted around it 
 without difficulty and placed in position for loading while the 
 full one was being rolled back upon the track and trammed to the 
 siding when the trains were made up. Such a method is simple 
 and effective, and except for the work of moving the siding ahead 
 requires but Httle extra labor; most of the plates are needed in 
 any event for the men to shovel from, so that the work of adding 
 one or two more would scarcely be noticed. This procedure is 
 recommended where for some reason it is necessary to employ 
 cars of large capacity. 
 
 But in most cases, as was pointed out in the section on 
 haulage equipment (see page 163), it is much better to use cars 
 of smallet capacity; then the empty ones are tipped off the track 
 to allow the full ones to pass and can be righted when needed 
 and placed back easily by two men, thus avoiding all the com- 
 pHcations and extra work arising from the use of a siding or 
 switch. The smaller cars are also easier to load, for since they 
 do not occupy so much space in the tunnel heading there is more 
 room for the shovelers to work; also, the sides of the smaller cars 
 being lower, each shovelful of rock does not have to be lifted so 
 high in order to get it into the car, saving both time and energy. 
 They are likewise easier to handle in case of a derailment, and 
 since fewer men are required for tramming them out of the head- 
 ing when full, a larger percentage of the time of the shoveling 
 crew can be spent in the actual process of loading. 
 
 When the smaller cars are used, however, the work of handhng 
 them must be thoroughly systematized in order to prevent waste 
 of time through avoidable delays. Although similar to that in 
 use at a number of the tunnels examined, the system employed 
 at the Rawley tunnel was perhaps more carefully worked out 
 in all the details than were any of the others. Upon arrival at 
 the heading, the empty cars were pulled as near as possible to 
 the full cars waiting to be removed, which at this juncture 
 ordinarily stood on the track some 75 or 100 feet from the face 
 of the tunnel. The mule was then detached from the empty 
 
266 MODERN TUNNELING 
 
 *' trip " and used to pull the full cars back to the one being loaded, 
 usually the last one of the previous empty trip; or if they had all 
 been loaded the full cars were pulled back as near the face as 
 possible. The empty cars were then hauled up to the full ones 
 and tipped off the track on their sides out of the way. All of 
 this work was performed by the mule-driver alone, except when 
 the shovelers had completed the loading of the empty cars, in 
 which case they assisted wherever possible in order to expedite 
 matters. After seeing that the cars of the full trip were properly 
 coupled up, the driver then started with them for the dump 
 and the muckers took the two empty cars nearest the portal, set 
 them on the track, and trammed them to the face where one car 
 was again tipped off on its side while the other was being loaded. 
 Unless the mule-driver was delayed in getting to the heading so 
 that he did not arrive before all of the cars of the previous trip 
 were filled (an event not of frequent occurrence, however), 
 the operation of getting the loaded trip out of the heading and 
 an empty car again in position to be loaded, rarely occupied more 
 than from three to five minutes. The remainder of the cycle was 
 similar to that just described for the Laramie-Poudre tunnel, 
 each full car being trammed a short distance beyond the last one 
 of the empty trip, which was then taken up to the face and 
 thrown on its side ready for use without delay when 
 needed. 
 
 To recapitulate, then, the chief advantages of this system 
 are: (i) it does away with a switch near the heading; (2) the 
 cars do not have to be trammed any great distance by 
 hand — only a little more than the length of one trip — and the 
 distance is constant and does not vary with the tunnel advance; 
 (3) the minimum time is consumed in getting the full car out 
 of the way and replacing it with an empty one, and (4) very 
 little time is lost in making up the trains to be hauled to the 
 dump. It cannot of course be used satisfactorily unless the 
 cars are small enough to be handled easily by two men, but this is 
 a matter which can be provided for in purchasing the equip- 
 ment and, as has been shown, the smaller car has other ad- 
 vantages which make it very desirable for tunnel work. A 
 
METHODS OF MUCKING 267 
 
 system similar to the one outlined, modified of course to fit 
 local conditions, is highly recommended for future tunnel work. 
 
 USE OF STEEL PLATES 
 
 The use of steel floor plates from which to shovel rock broken 
 by the blast has become so general that mention of this feature 
 of mucking should hardly be necessary. The authors were 
 much surprised, however, to find at one or two tunnels, where 
 otherwise there was httle left to be desired in the fine of organiza- 
 tion and equipment, that the muck was being shoveled without 
 the use of plates. Even the most cursory study of this work, 
 noting the efforts of the men in pushing the shovels into the rock- 
 pile along the uneven surface of the bottom of the tunnel and 
 comparing the time required to load a car with the results at 
 other tunnels where steel sheets were in use, soon made it evident 
 that large quantities of both energy and time were being wasted 
 needlessly. 
 
 At one tunnel the plates were not used because it was neces- 
 sary to excavate the floor on a curve instead of making it flat, 
 as is usually the case, though even here plates could have been 
 employed by leaving a portion of the waste material in the 
 bottom of the tunnel to form a flat surface upon which the 
 sheets might have been placed. Upon inquiry at another tunnel 
 the following reasons were given for their non-use: (i) The 
 muck was so sticky that it would not be at all easier to shovel 
 from the plates than from the rock-pile; (2) it was impossible to 
 prevent the sheets from becoming bent, twisted, and jumbled 
 up with the muck when the holes in the bench were blasted; and, 
 (3) it was a great deal of trouble to lay them in position before 
 blasting and to handle them during the work of mucking. 
 
 Now, while it should be admitted in all candor that the 
 stickiness of the muck in this instance made it difficult to handle 
 under any conditions, there is no good reason to suppose that 
 shoveling from a plate would have been more arduous than from 
 the pile — quite the reverse. The second objection is somewhat 
 more serious; for it is true, especially with heavy blasts, that 
 the sheets are sometimes caught up and twisted by the explo- 
 
268 MODERN TUNNELING 
 
 sion and occasionally hurled for considerable distances down 
 the tunnel. Where the plates are properly covered with waste 
 rock from the previous round before blasting, however, such 
 occurrences are so extremely rare as to be neghgible, and this is 
 ordinarily the remedy for such difhculty. But at the particular 
 tunnel under discussion the trouble was somewhat different. 
 It was being driven with a heading nearly square, and this was 
 followed at a distance of eight to ten feet by a bench three to 
 four feet high. The holes in the bench were drilled from the 
 same set-up as those in the heading, and they "looked" down and 
 away from the heading and hence toward and slightly under the 
 position that would have been occupied by the steel sheets. It 
 is not surprising that with this arrangement a great amount of 
 difficulty should have been experienced in keeping the plates 
 down during the short time they were tried. The objection in 
 this instance should not have been taken to the steel sheets, but 
 to the design of the tunnel itself, which was being driven consid- 
 erably higher than it was wide, but would have served every 
 purpose required of it equally well if the dimensions had been 
 reversed. Such a change would not only have obviated the sheet 
 trouble, but would also have made it easier to drive in other 
 respects. Aside from this, the tunnel was not high enough to 
 warrant the removal of the material in two operations, as was 
 being done at the time it was visited. Since then, however, the 
 bench was abandoned, all of the material being excavated at 
 once, which made it possible for the mucking to be done without 
 difficulty from steel plates. 
 
 The third criticism is entirely a question of economy and can 
 best be met by inquiring whether it is not better for the muckers 
 to spend fifteen or twenty minutes while the drillers are loading 
 the holes, and possibly as much more time during the mucking, 
 in doing work that will save itself several times over. For it 
 cannot be denied, and has been proved time and again, that a 
 man can work to much better advantage and handle more rock 
 during a given time if he shovels from a smooth surface. And this 
 is only what is to be expected when one realizes that in so doing 
 he encounters but very httle resistance other than friction in 
 
METHODS OF MUCKING 269 
 
 pushing the shovel home, and is therefore able to secure a shov- 
 elful with the minimum expenditure of energy and in the shortest 
 time. But when shoveling from the pile, the shovel can rarely 
 be pushed more than an inch or two without encountering 
 a piece of rock too big to be shoved aside (although the effort 
 is usually made to do so), and there must, therefore, be a distinct 
 stop while the shovel, with any load upon it, is Kfted clear of 
 the obstruction, only, in all probability, to encounter another 
 one almost immediately. It is not surprising, therefore, to find 
 •that the experience at a large majority of tunnels leads to the 
 conclusion that steel plates for shoveling are among the chief 
 economies. 
 
CHAPTER XIV 
 
 TIMBERING 
 
 MATERIALS 
 
 When the rock through which a tunnel is driven does not 
 possess sufficient strength and rigidity to carry the weight of 
 the superincumbent mass, artificial supports for the roof, sides^ 
 and sometimes for the bottom are necessary to prevent the rock 
 from falHng, crumbling, or squeezing into the excavation. These 
 supports may be timber, brick, stone, metal, or concrete. Because 
 of its cheapness and availability in many mining districts, and 
 the ease with which it can be cut to the required sizes and shapes 
 and placed in position, the first of these is the one most generally 
 employed; and even where masonry or concrete Kning is called 
 for in the specifications of the completed tunnel, timber is almost 
 always used as a temporary support until the more permanent 
 material can take its place. 
 
 In most underground situations seasoned timber is prefer- 
 able to green because it is better able to resist decay; and the 
 bark should invariably be removed from round logs, as the 
 space between it and the wood affords an excellent breeding-place 
 for many forms of wood-destroying insects, while the bark itself 
 collects moisture and thus encourages the growth of fungi which 
 are the chief wood-destroying agents. Round timbers when 
 properly peeled and seasoned are more durable than square 
 timbers cut from a similar log of the same size and age, because 
 the corners of the latter are especially Hable to decay. In young 
 and small timber, such as is generally used for mining work, 
 the outer half of the log is usually sap wood containing starch, 
 sugars, proteids, and other soluble organic compounds, the foods 
 upon which decay-producing fungi thrive, and which are practi- 
 cally wanting in the heart wood. In the process of squaring up, 
 where, as is usually the case, the attempt is made to secure the 
 largest possible square timber from a given log, the corners 
 
 270 
 
TIMBERING 271 
 
 consist largely of this easily infected sap-wood and are accordingly 
 most liable to conditions bringing about quick rotting. It is 
 not surprising, therefore, to find in moist underground workings 
 where square timbers have been in place for three or four years 
 that the corners of the timbers have decayed to such an extent 
 that they can be pried off down to the heart wood with a miner's 
 candlestick or any other sharp instrument. It is, of course, 
 true that the outer portion of a round log also consists of sap- 
 wood, but the exposed surface has not been injured or bruised 
 by the saw. 
 
 While round timbers deteriorate much more slowly than 
 square, they are not so easily handled in the tunnel, and they are 
 also harder to align properly; it is also much more difficult to 
 reinforce them by the ordinary false sets or pieces. Where 
 timber must be transported long distances the greater weight 
 of the round sticks (especially where the logs are truncated 
 cones — or ''churn-shaped," as the miners say — instead of being 
 nearly cylindrical), the freight costs become prohibitive and 
 square timbers must be used. Under these conditions the 
 saving in transportation charges will often pay for some type of 
 preservative treatment to be appHed to the timbers before being 
 placed underground. 
 
 The best method of checking the growth of fungi, and by so 
 doing increasing the durabihty of timber, is to poison the source of 
 their food supply, and although there have been many processes 
 invented for this purpose, most of those in use to-day depend 
 upon the injection of either zinc chloride or creosote. The 
 former cannot be used advantageously in wet situations, how- 
 ever; for since it is soluble in water it would soon be leached 
 out, leaving the timber just as susceptible to attack as before. 
 But when creosote has been properly appKed it cannot be 
 washed out, no matter how much water passes over the timber, 
 and for this reason it is the preservative generally employed in 
 mining and tunnel work. It is, however, somewhat more costly 
 than the former, and since it is a hquid, the transportation 
 charges are considerably higher, while the zinc chloride can be 
 shipped in bulk. 
 
272 MODERN TUNNELING 
 
 Creosote can be applied as a surface coating by painting 
 with a brush or simple immersion in a tank, or the log can be 
 more deeply impregnated with the preservative by one of the 
 more complicated processes involving heat, pressure, or vacuum. 
 Although painting is the least efhcient method, it has the ad- 
 vantage of cheapness, and if carefully done will give fairly 
 satisfactory results. While dipping or simple immersion results 
 in but little if any greater penetration of the preservative, it 
 insures a more certain filling and coating of the cracks, checks, 
 and other imperfections of the log and thereby affords better 
 immunity from decay. It is also in most cases cheaper than 
 painting because it is more economical of labor, it being easier 
 to run a number of sets of timber through a vat on some form 
 of mechanical conveyer than to paint the same number by 
 hand. For either method the timber must be fully dried and 
 seasoned beforehand, otherwise cracks in the v/ood due to the 
 evaporation of the moisture will break the protective covering, 
 which is only a thin one at best, and thus give the fungi access 
 to the interior of the stick. It is perhaps unnecessary to add that 
 these, as well as any of the other treatments, should not be given 
 the timbers until after they have been cut to form, so that the 
 eiids and the mortise openings may be coated as well as the sides. 
 
 Where the extra cost of a more thorough impregnation is 
 warranted, the "Betheir^ process is widely employed for timbers 
 that are to be placed in wet situations. By this treatment the 
 timber is for several hours given a bath of Hve steam at perhaps 
 twenty pounds pressure, after which it is subjected to a vacuum 
 for three or four hours more, when creosote, heated to a tem- 
 perature of approximately i6o° F., is appKed under pressure 
 until the desired amount of the preservative is forced into the 
 wood. " Burnettizing " is a process practically identical with 
 this, except that zinc chloride is used in place of creosote. There 
 are also a number of methods less frequently employed which are 
 designed to effect economy in the amount of chemical required, 
 and which differ chiefly in the manner of its apphcation. In 
 one or two of them the interior of the timber is impregnated 
 with the less expensive zinc chloride which is in turn protected 
 
TIMBERING 273' 
 
 from the action of water by treating the outer zone with creosote. 
 A more complete discussion of processes than can well be in- 
 cluded in this book may be found in Forest Service Bulletins 
 78, "Wood Preservation in the United States," and 107, "The 
 Preservation of Mine Timbers." 
 
 For permanent tunnel hnings, brick and stone were formerly 
 the chief materials employed and most of the older tunnels both 
 in tliis country and abroad are lined in this manner. Such hnings 
 are expensive, however, and require a higher class of labor to 
 place them in position than does concrete, their modern sub- 
 stitute, nor do they afford the same imperviousness. Although 
 metal beams and posts are sometimes employed advantageously 
 as roof supports in the main entries and gangways of coal mines, 
 high cost prevents their use except for this or work of similar 
 importance. The best modern material for permanent linings is 
 undoubtedly concrete; and although its employment in this 
 work has thus far been restricted chiefly to railroad, irrigation, 
 or water-supply tunnels, its use in practically every important 
 mining tunnel where a permanent lining is necessary must 
 almost certainly follow. 
 
 TYPES* 
 
 The simplest forms of roof support are of course a post, or 
 single timber supported by a "hitch" or recess in the side wall. 
 Where the sides of the tunnel are not strong enough to afford a 
 hitch, the ends of the cap are supported by posts; and if the 
 floor will not bear the weight of the posts, a sill is placed for 
 them to rest upon. Figure 65 illustrates such a four-piece set 
 appKed to as small a tunnel as it is usually advisable to excavate. 
 
 * As tunnels and adits for the purpose covered by this book are rarely 
 too large to be driven as a single heading, the many complicated and ingenious 
 systems of timbering which are used in driving large railway tunnels, either 
 with multiple headings or single heading and bench work, need not be 
 considered here. For a discussion of these methods the reader is referred to 
 the monumental work of Drinker ("Tunneling, Explosive Compounds, and 
 Rock Drills," Drinker, Henry S., New York, Wiley & Sons) ; to Prelini ('* Tun- 
 neling," Prelini, Charles, New York, Van Nostrand); Stauffer ("Modern 
 Tunnel Practice," Stauffer, David McNeely, New York, Engineering News), 
 and the publications of the Civil and Mining Engineering Societies. 
 
274 
 
 MODERN TUNNELING 
 
 The timbers are 8 inches by 8 inches, and instead of partially 
 beveling them to withstand side pressure the posts are held 
 apart by a 2 -inch by 8-inch plank spiked to the cap. Figure 66 
 
 Fig. 65. Four-piece set of timbers for a small tunnel. 
 
 Fig. 66. Four-piece set for a tunnel of a convenient size. 
 
 illustrates a very common form of timbering designed for a 
 tunnel of a convenient size for driving where a single track is 
 all that is required. The timbers are 10 inches by 10 inches and 
 the joint between the cap and the posts is beveled at the corners 
 
TIMBERING 
 
 275 
 
 SO that the timbers can easily resist horizontal or vertical pressure 
 without splitting. If hea\der ground is encountered than can be 
 held with this set, the posts and cap can be made of 12-inch by 
 
 Fig. 67. Arrangement of timbering providing a 
 manway at one side of the tunnel 
 
 Fig. 68. Timbering for a wet tunnel. 
 
 1 2-inch timbers, with 8-inch by 12-inch sills, and 8-inch by 8-inch 
 collar '^braces," as they are commonly called. 
 
276 
 
 MODERN TUNNELING 
 
 In single-track tunnels where there is considerable traffic, it 
 is often advisable to have the opening wide enough to give room 
 for a manway and the ventilating pipe on one side and the car 
 tracks on the other, as shown in Figure 67. Or if the tunnel has 
 to carry a considerable volume of water, the design shown in 
 
 Fig. 69. Timbering for a tunnel producing a large volume of water. 
 
 Figure 68 has been used in many instances and has given excel- 
 lent satisfaction, notwithstanding the fact that both the opening 
 and the timbers are unsymmetrical. The 6-inch by 6-inch sill, 
 which also forms the rail tie, is not notched into the post on the 
 right side, but is merely held in place by a 2-inch by lo-inch plank 
 spiked to the face of the post, the upper end of the plank being 
 recessed for a depth of 4 inches to receive the sill. Where 
 even larger volumes of water have to be provided for, the arrange- 
 ment illustrated in Figure 69 has given very good results at a 
 number of places where it has been tried. The amount of water 
 and the grade of the tunnel, of course, determine the proper 
 
TIMBERING 
 
 277 
 
 depth of the drain. The sill is supported by planks spiked to 
 the posts, as in the preceding case. 
 
 Where the roof pressure becomes too great to be carried by a 
 horizontal cap, what is known as the ''arch set" is usually em- 
 ployed. Figure 70 shows the design of such a set for a tunnel 
 
 \^"m 
 
 Fig. 70. Arch set for a 
 small tunnel. 
 
 Fig. 71. Arch set with 
 vertical posts. 
 
 7 feet 6 inches high by 6 feet wide on the sills. The timbers are 
 
 8 inches square and the collar braces 4 inches by 6 inches. In- 
 stead of placing the braces on the outer edges of the timbers, as 
 is done on square sets where they can be sHpped in from the 
 outside, the collar braces on arch sets should be mortised into 
 the face of the timbers in a central position, bisected by the 
 joint, as shown in the illustration. By this means the bevel 
 pieces forming the arch, being much more difficult to hold in 
 place while being blocked than are square sets, are prevented by 
 the braces from slipping. If more room is required in the upper 
 portion of the tunnel than is given in this design, vertical posts 
 are often used (see Figure 71), a substitution which not only 
 increases the width of the tunnel at the shoulders but calls for 
 all timber cuts at an angle of 30°, making the sides and the top 
 pieces of the arch interchangeable. Figure 72 illustrates the 
 arch system of timbering as employed in medium heavy ground 
 for a tunnel 8 feet in width by 7 feet 6 inches in height, which is 
 
278 
 
 MODERN TUNNELING 
 
 about the minimum size for a double-track tunnel. If the walls 
 of a tunnel are sufficiently firm to stand without timbers and 
 only the roof requires support, the arrangement shown in Figure 
 73 can often be used to advantage. This system makes a care- 
 
 <^'^8'* 
 
 Fig. 72. Arch set for a double-track tunnel. 
 
 Fig. 73. Arch roof 
 support and hitch. 
 
 Fig. 74. Inverted arch set 
 for swelling ground. 
 
 fully constructed footing for the arch timbers necessary, but 
 hitch-cutting with a modern hand pneumatic drill is compara- 
 tively a cheap operation, the cost of which will be repaid many 
 
TIMBERING 
 
 279 
 
 times by the saving in timbers and in the smaller amount of 
 rock to be excavated. 
 
 Swelling or creeping ground results from the exposure of cer- 
 tain rocks to the air, whereby they undergo chemical change 
 and increase in volume so that the excavation not only closes in 
 from the sides and roof but swells up from the floor as well. 
 Under such conditions it is sometimes necessary to design the 
 timbers as shown in Figure 74, where the drain box and the 
 track are protected by an inverted arch. Where 12-inch by 12- 
 inch timbers in this form will not resist the squeeze at the usual 
 distance of 4 feet between centers it is customary to close 
 them up until they have sufficient resistance to withstand the 
 pressure. Occasionally, however, zones of rock are encountered 
 that cannot be held even by this expedient, in which case the 
 timbers can be kept from breaking by placing the sets about 
 3 or 4 inches apart; then, whenever the pressure becomes too 
 
 Fig. 75. Octagonal set of tunnel timbers. 
 
 great, it can be reduced by removing with a long-bladed pick 
 whatever decomposed rock is in line with the open spaces, 
 4 or 5 inches back from the timbers. Swelling ground is usually 
 so soft that this can be done without much trouble, and it is 
 neither a difficult nor an expensive matter to keep a wood- 
 hned tunnel open until it can be lined conveniently with concrete, 
 which, by preventing access of air to the rock, will remove 
 
280 
 
 MODERN TUNNELING 
 
 much of the difficulty. The octagonal set (see Figure 75) offers 
 another means of holding such heavy ground, and it is often advis- 
 able to follow it up with concrete in front of and between the 
 timbers as shown on the left side of the illustration. To insure 
 the safety of the tunnel after the timbers have decayed, the sets 
 should not be spaced less than 12 inches apart, while 15 to 18 
 
 Fig. 76. Timbering for loose ground. 
 
 inches is still safer, since the wider opening gives room for a 
 stronger rib of concrete between the timbers. The above is 
 an exceedingly easy section to handle, and, where the flow of 
 water is not too great for the drainage area underneath, nothing 
 better could be adopted. All the pieces in this timber set are 
 exact duplicates, and this is a great convenience not only in 
 framing, but also in storage and erection. 
 
 An entirely different problem from swelling ground, and one 
 temporarily much more difficult to handle, is often encountered 
 where adits or tunnels have to be driven through shear zones, 
 caved ground, or loose crushed material which will not stand 
 overhead without being supported as fast as it is opened. One 
 of the oldest designs for driving through areas of this description 
 is shown in Figure 76, where each alternate set carries a double 
 cap. This arrangement is siniple, easily operated, and very sat- 
 isfactory where the material in the roof or sides does not bring 
 too much pressure on the spiling.* The method possesses, 
 
 * Where the lining of a tunnel can easily be placed in position it is usually 
 known as lagging, but where it has to be sharpened to a chisel-shaped end 
 and driven into position it is called spiling or forepoling. 
 
TIMBERING 
 
 281 
 
 however, two grave disadvantages: it requires two different sets 
 of timbers, and the spiling used must be long enough to cover 
 both sets. This latter difficulty, where the overhead material is 
 heavy, sometimes proves serious, as it is often difficult to drive 
 spiling across one space, to say nothing of two. 
 
 Under such conditions, the tail-block system, illustrated in 
 Figure 77, is generally employed. Since the timber sets are all 
 
 Fig. ']']. Tail-block system of timbering. 
 
 the same size, it avoids one disadvantage of the preceding case, nor 
 do the sets differ in any particular from those used with ordinary 
 lagging. It offers, however, but little improvement in the 
 matter of driving the spiling in place. To be sure, the spiling 
 does not have to cover two sets, but where the ground is heavy 
 the great pressure brought upon the tail-block by a comparatively 
 small amount of rock resting over the spihng as it is being 
 driven forward creates an amount of friction which, added to the 
 resistance in front of the spile, makes driving exceedingly difficult 
 even with the heaviest sledges that can be used. Even if the 
 greatest care be taken, the back end of the spile is often broomed 
 and spHt by the heavy pounding required. This can be obviated 
 in part by capping the back end of the spile with an iron shoe, and 
 a heavy piston drill is sometimes employed to do the pounding. 
 Where the ground over the tunnel is very much shattered and 
 weak, making the continued hammering on the spiUng dangerous, 
 it is safer to force the spiling slowly forward with Hght jack 
 screws, and thus avoid the jarring effect of sledges. 
 
282 
 
 MODERN TUNNELING 
 
 When an opening has to be driven for any considerable 
 distance through soft material requiring immediate support, 
 the work can be expedited greatly by the use of what is known 
 throughout the West as the swinging false-set, illustrated in 
 Figure 78. Like many other inventions, this system was the 
 child of necessity and was first used in the Cowenhoven tunnel, 
 at Aspen, Colorado, where the overlying rock brought so much 
 pressure on the spiles that it was almost impossible to drive 
 
 Fig. 78. Swinging false-set for loose ground. 
 
 them forward with an eighteen-pound sledge. With this 
 method no tail-blocks are employed, nor need the spiling be 
 driven across two sets of timbers as in Figure 76. The weight 
 on the front end of the spiling is carried directly on the swinging 
 false-set, and the spiling can be driven into place with a quarter 
 of the hammering necessary under the tail-block system. As 
 will be seen by inspection of the longitudinal section, the posts of 
 the swinging false-set rest and rotate on the sill of the permanent 
 set and when first erected occupy the position shown by the 
 dotted lines. They carry a circular steel cap b, which supports 
 the front end of the spile a, so that the only pressure to be 
 overcome in driving is that of the rock immediately above and 
 in front of the spile, and it is consequently much easier to drive 
 it forward than in the tail-block system, where a weight of 100 
 pounds on the front of the spile would easily cause a pressure of 
 five times that amount on its supports. As the spiling is driven 
 forward the turn-buckle c is slowly unscrewed, allowing the 
 
TIMBERING 283 
 
 swinging false-set to fall forward and carry the point of the spiling 
 in a nearly horizontal Hne. When all of the spiles have been 
 driven home and the supporting block d is placed under them, 
 the turn-buckle c is unscrewed still further, permitting the 
 hanging rods to be unhooked from the eye-bolts and the false- 
 set advanced to a new position, one set farther ahead. The 
 system requires that the timbers for at least five or six sets from 
 the face shall be bolted together in very much the same manner 
 as hanging-bolts are used in placing shaft timbers; this, however, 
 is a direct advantage rather than the reverse, for by bolting the 
 timbers together and screwing them tight against the braces, 
 they can be placed in position much more easily and quickly. 
 Further, the timbers are held together so firmly that if hard 
 ground is encountered in any part of the face, much heavier 
 charges of explosives can be used than if they were held in place 
 merely with blocks and wedges. The swinging false-set works 
 equally well with square or arched sets, but where the latter are 
 used the collar braces should be shifted from their normal 
 position on the center hne of the timbers, as shown in Figures 70, 
 71, 72, and 74, to the outer end of the joints to make room for 
 the greatest possible width of spiKng; by this means the angle 
 gap can be reduced to a minimum and the length of the 
 ^'lacing," correspondingly reduced. 
 
 In driving a heading where the character of the rock neces- 
 sitates timbering close to the face, care must be taken thoroughly 
 to brace and block the front sets before firing. Where the roof 
 ''breaks high" and there is any possibiHty of large masses 
 dropping out of it, the space between the lagging and roof must 
 be completely filled either with waste or blocking, otherwise a 
 large piece of rock may drop from the roof and pass completely 
 through the lagging, and thus endanger the lives of the men 
 below. Timbering close to the face always diminishes the 
 rate of progress by compelling the use of shallower holes and 
 lighter charges. An excellent plan to permit of heavier rounds 
 under these conditions is to keep the last six or eight sets of 
 timbers firm and tight up against their collar braces by the use 
 of tie bolts. These should be provided with center hooks to 
 
284 MODERN TUNNELING 
 
 permit of their ready removal, on the same plan as the hanging 
 bolts which have so long been successfully used in shaft sinking. 
 Only six or eight sets of bolts are required, those from the rear 
 being moved forward and used in the face. This system of 
 tying the sets together has been found to be equally advantageous 
 in horizontal and in vertical driving. 
 
 The tunnel shield, such as is generally employed with or 
 without compressed air for piercing subaqueous river-bed 
 deposits, affords another solution of the problem of driving 
 through soft ground. While in the matter of speed, safety, and 
 economy the modern shield leaves little to be desired, it has one 
 great drawback — the initial cost of the installation — which prac- 
 tically bars it from use for the narrow zones or small areas of 
 running ground usually encountered by the class of tunnels we 
 are considering in this book. 
 
 The system of timbering employed at the north end of the 
 Elizabeth Lake tunnel of the Los Angeles Aqueduct is of especial 
 interest because of the ingenious and extremely effective means 
 employed to drive through a comparatively hard rock which, 
 however, was so shattered and broken that it could not be trusted 
 to stand even temporarily without support; in addition, the 
 speed and efl&ciency with which the timbering was placed in 
 position were notable, enabling as they did the north end of the 
 tunnel to progress practically as fast as the south, although in 
 the latter but very Httle timbering was required. The following 
 description is taken, with some condensation and re-arrangement, 
 from an article by R. L. Herrick, in Mines and Minerals for 
 October, 1910. 
 
 The main tunnel, , which was approximately 12 by 12 feet, 
 was preceded by a short pilot heading having dimensions of 
 approximately 8 feet by 8 feet, in which the roof was supported 
 by ''false" timbering. Assuming for convenience the time of 
 inspection to have been at the end of a shift with the drills re- 
 moved from the breast preparatory to blasting the round, the 
 position of the timbers would have been somewhat similar to 
 that shown in Figure 79 (a), which represents a short timbered 
 section of the full-sized tunnel and the horizontal timbers used 
 
TIMBERING 
 
 285 
 
 temporarily in supporting the roof of the pilot heading. The 
 posts of the permanent sets were 8-inch by 8-inch square timbers, 
 8 feet 6 inches in length; and in the figure they are spaced longi- 
 tudinally at eight-foot intervals, although in practice they were 
 often set irregularly, depending upon the weight of the roof. 
 
 SECTION A-B SECTION C-D SECTION E-P 
 
 Fig. 79. System of timbering at Elizabeth Lake tunnel. 
 
 The width between the posts was 10 feet 2 inches in the clear, 
 while the tunnel was broken as nearly as possible to a width of 
 12 feet. The collar braces were ordinarily 2-inch by 6-inch planks 
 whose ends were supported either by wedges or timber-ends 
 spiked to the set. The false posts in the heading were later used 
 
286 MODERN TUNNELING 
 
 as pennanent posts for the full-sized tunnel, and as one end of 
 them was beveled to carry pieces of the permanent arch, these 
 beveled ends were placed next the floor in the heading, while 
 their squared ends supported the temporary caps, which likewise 
 consisted of timbers already cut to form and which were later 
 used as permanent posts. In this way there was no handling of 
 heavy timbers not intended for permanent use. Just before 
 blasting, the false timbers were carefully braced and wedged to 
 the roof as tightly as possible, as shown in Figure 79 (b). 
 
 As soon as possible after the blasting the timber-men went 
 back to the heading to shore up the new roof temporarily from 
 the top of the rock pile. For this purpose, two horizontal 
 timbers, supported from the broken rock close to the side walls 
 and having transverse timbers and blocking resting upon them 
 as shown in Figure (c), were placed by the timber crew, an 
 operation which interfered but little with the work of the muckers 
 shoveling back from the face to allow the placing of the drills. 
 The debris was next removed down to solid bottom to permit 
 the setting of false posts which, when capped, then carried the 
 weight of the roof. 
 
 Timbering the tunnel during the enlargement to full size 
 was not a difficult operation. Starting at the last permanent 
 set and proceeding toward the face, new permanent posts (shown 
 in a, Figure 79) were placed in position as fast as the section was 
 widened by picking down the side walls. Transverse spreader 
 timbers, shown in section CD, Figure 79, were then placed be- 
 tween these posts with their bottoms 14 inches below the joint 
 and resting on timber ends spiked to the posts. Across these 
 spreaders were laid two tiers of two-inch plank, forming a floor 
 4 inches thick. This floor was some 2 or 3 inches below the 
 bottoms of the caps resting on the false posts, so that it was 
 easily laid while the false sets continued to hold the roof. Work- 
 ing from the end of this floor, the wedges and blocking trans- 
 mitting the roof weight to the false set were next carefully 
 knocked out and the shattered roof picked down on the floor, 
 from which it was later dropped into cars. By placing the 
 permanent posts a foot or so in advance of the false posts as in 
 
TIMBERING 287 
 
 a, Figure 79, the arch timbers of the permanent sets could be 
 put in position as soon as the roof was sufficiently removed. 
 Lagging and wedging quickly followed, so that the roof was 
 supported by the permanent sets shortly after the removal of 
 the false blocking. 
 
 Although lining a mining tunnel with concrete is not, strictly 
 speaking, a type of timbering, both have the same function — 
 that of supporting the roof and walls. In this work the concrete 
 is usually placed in the openings between the timbers and for 
 a few inches in front of them, which, where the sets are not spaced 
 too closely together, is generally sufficient, even though later 
 decay of the wood results in a corresponding weak spot in the 
 lining. This defect can be avoided, however, by the use of posts 
 and caps made of reinforced concrete in place of wood, a practice 
 which has been recently introduced and which is finding great 
 favor wherever its added expense is warranted. The concrete 
 posts and caps are made outside of the tunnel in a mold which 
 gives them the identical form of the wooden pieces they displace; 
 and by proper reinforcement they can be made equal, if not 
 superior, to timbers in strength, a strength which is practically 
 permanent. 
 
 In water-supply tunnels a concrete lining performs the 
 additional function of obviating eddies and friction against the 
 otherwise irregular walls, and for this reason such tunnels are 
 generally lined throughout, irrespective of the needs of the roof 
 for support. On the Los Angeles Aqueduct the tunnel lining 
 was generally at least 8 inches in thickness where the tunnel was 
 not timbered, although an occasional rock projecting into the 
 concrete was not removed unless it came within 4 inches of the 
 inside finished surface of the lining. In timbered ground, con- 
 crete was placed between the timbers and for a minimum dis- 
 tance of 4 inches in front of them. The inverted siphons of the 
 Catskill Aqueduct were lined with concrete which was ordinarily 
 2 feet thick, but solid rock was permitted to project without 
 removal to within 10 inches of the interior surface. Owing to 
 the great hydrostatic head, sometimes as high as 700 feet, to 
 which these linings were to be subjected, every piece of timber 
 
288 
 
 MODERN TUNNELING 
 
 was removed before the concrete was put in place, and where 
 it was necessary to support the roof during the time the concrete 
 was setting, steel roof supports were designed and placed for this 
 purpose. 
 
 At the Snake Creek tunnel (where a zone of swelling ground 
 was encountered which resisted all efforts to hold it in the ordi- 
 nary way, the strongest timbers that could be obtained being 
 
 IQajuigulaT mesh sraseen, -weigbit 106 potmds per 100 sqnare feefi 
 
 tficftal thickness (S£ 
 concrete 12" 
 
 s^^^^^^^jil^}^ 2'six-Tiole splice,- 
 
 ;/.vc^^<?;.:l;iii*s4i;s--:il f^'bolts. EishplatQ 
 
 cross section 2,% 
 
 square inches each. 
 
 !gulation railroad 
 £oux=hole fishplate 
 
 Fig. 8o. Reinforced concrete lining at Snake Creek tunnel. 
 
 crushed and broken in less than a month's time) a concrete 
 lining reinforced with steel rails was installed. The accompany- 
 ing illustration of this Hning is practically self-explanatory, but 
 a complete description of it may be found in the Engineering 
 Record for May 25, 191 2. Where large volumes of water have 
 to be carried through ground extremely difficult to hold, this 
 design seems excellent, although its cost would be prohibitive 
 for anything except important tunnels draining large areas of 
 well-developed ground. 
 
CHAPTER XV 
 SAFETY 
 
 Data collected by the Bureau of Mines show that an average 
 of nearly four men for each i,ooo employed in and about the metal 
 mines of the United States were killed during the year 191 1, as 
 compared with 3.8 per 1,000 in coal mining during the same 
 period. Although complete figures for accidents in tunnel 
 driving cannot be obtained, a study of such data as it was pos- 
 sible to collect indicates that the number of deaths per year per 
 thousand men employed has been somewhat greater than the 
 above figures, the result obtained by averaging data extending 
 over periods of from one to ten years for sixteen representative 
 tunnels being 4.7 deaths per year per 1,000 men employed. 
 In addition to the men killed outright, nearly four times as 
 many more have been seriously injured, or perhaps maimed for 
 Hfe, and almost thirteen times as many sKghtly injured by acci- 
 dents in tunnel work. By far the largest portion of these deaths 
 and injuries were caused by falling ore or rock from the roof or 
 walls of the tunnels, but the careless use of explosives, haulage, 
 electricity, and other causes have each claimed their quota 
 of casualties. 
 
 Are these accidents preventable? Not entirely, because there 
 are some elements of danger impossible to eliminate and inherent 
 in the work of driving tunnels; such, for example, as the danger 
 from some unforeseen falls of roof, from the derailment of tunnel 
 cars, or the certain risk when handling even the safest explosives 
 by the most approved methods. But it is equally true that much 
 of the present mortality and injury is the result of ignorance or 
 gross carelessness, and can be avoided. When, for instance, a 
 man sees fit to thaw frozen dynamite in a frying pan or by a 
 candle flame, there is nothing accidental about the explosion 
 which ensues, except, indeed, the fact that a man so ignorant or 
 
 289 
 
290 MODERN TUNNELING 
 
 reckless should have been entrusted with so dangerous a sub- 
 stance! Nor is the responsibility for accidents entirely on the 
 part of the miner. The manager and his representatives are in 
 many cases either ignorant of the precautions which should be 
 taken for the safety of the men under them, or most negligent in 
 seeing that they are properly and consistently carried out. The 
 following paragraphs are written, therefore, in the hope that, by 
 bringing these matters once more squarely to the attention of 
 the men interested, much of the needless death and suffering 
 may be prevented. 
 
 CAUSES OF ACCIDENTS 
 Falls oe Roofs 
 
 There are many causes which combine to make falls of rock 
 from the roof by far the greatest source of danger in tunnel work, 
 but perhaps the chief of these is the common practice of greatly 
 overloading the holes with explosives. Extremely heavy charges 
 shatter and crack rock which would ordinarily stand without 
 any danger of falling, and render it extremely dangerous to the 
 men working underneath. Of course, it is essential to efficient 
 work in tunnel driving that the blast should completely ^' break 
 bottom" without any necessity for a second loading and firing; 
 still every foreman and superintendent should see to it that the 
 very smallest amount of dynamite that will do the required work 
 is employed in the holes near the roof. Economy of explosive 
 demands tliis, all other considerations aside; but the dangers, 
 also, of the heavier charges should be thoroughly appreciated by 
 the superintendent and, when such charges seem imperative, 
 extra vigilance should be exercised and extra precautions taken 
 along other lines for the safety of the men. 
 
 Another proKfic source of accident is the fact that men will 
 sometimes return to the tunnel face, after shooting a round, 
 without thoroughly testing the new roof just exposed by the 
 blast. It should be the duty of every man employed in the 
 tunnel to examine the roof under which he must work, and 
 especially in that part of the tunnel newly exposed after shoot- 
 
SAFETY 29'1 
 
 ing; the foreman, upon reaching the heading after the blast, 
 should at once detail one or two men (or as many as prove 
 necessary) to clean down thoroughly all the loose pieces of over- 
 head rock. Fortunately, this is done regularly at all well- 
 organized tunnels, and it is a practice that cannot be too highly 
 recommended for universal use. 
 
 It must be admitted that there are times when even ex- 
 perienced men beheve the roof to be sound, when suddenly 
 and without warning a large block crashes into the tunnel. 
 This, if anything, will be claimed as a purely accidental occurrence, 
 yet even the danger from such a rock (which may have been 
 perfectly sohd when first exposed, but had become loosened 
 by the concussion of subsequent blasting) is, in many cases, 
 overlooked because of the lack of illumination in which all 
 tunnel work must be done, and might have been discovered in 
 time if there had been a systematic and regular examination of 
 the entire roof of the tunnel. As some one has pointedly ob- 
 served, ''The fall of a slab of rock weighing anything less than 
 one ton should at once be charged to carelessness." 
 
 It should be said in this connection that the ''sound" of 
 the roof is not a proper criterion of its safety, since there are 
 on record numerous cases in which the sound of the roof was 
 satisfactory and showed apparently solid rock even to very ex- 
 perienced men, but in which a big block or boulder was actually 
 loose. The better method of testing the roof — one used by many 
 large mining companies and recommended by the Bureau 
 of Mines — is to strike it with a pick or a heavy stick, at the 
 same time touching the doubtful piece with the free hand. If 
 any vibration is felt, the rock is unsafe and should be taken down 
 or supported at once. If the roof is too high to reach with the 
 hand, a stick should be held against the doubtful piece while it 
 is being struck, and if it is loose the vibration can be felt through 
 the stick. 
 
 Prompt and adequate timbering is extremely important. 
 But timbering is a laborious process, and it either takes the men 
 of the tunnel crew from their regular work or it requires extra 
 men. Even in the latter event the extra men add to the confu- 
 
292 MODERN TUNNELING 
 
 sion in the heading; and since their work is done simultaneously 
 with the other work of the tunnel, it seriously hinders either the 
 drillers or the shovelers, or both. Hence it has become recog- 
 nized among tunnel men that in most cases timbering seriously 
 impedes the progress of driving, and therefore, although it may 
 be well understood that the roof is dangerous, there is almost 
 always a tendency on the part of those responsible to delay 
 timbering as long as possible. Perhaps the American willingness 
 to 'Hake a chance" — a trait particularly noticeable in our 
 Western States — ^may be a contributing cause; but the fact 
 remains that the work of timbering is too often delayed until a 
 so-called "accident" brings the necessity forcibly and unavoid- 
 ably to the front. It is impossible to urge too strongly that all 
 necessary timbering be done promptly, that it cannot be done too 
 soon, and that any delay seriously jeopardizes the Hves and limbs 
 of the. men who have to work under a roof improperly supported. 
 
 It is true that in many tunnels the weight of the roof or 
 pressure against the walls has been too great even for the strongest 
 and heaviest timbering, and while this cannot always be pre- 
 vented, it may often be alleviated by means discussed in the 
 chapter on timbering. But the important thing to consider 
 in these cases, from the viewpoint of safety, is the fact that 
 actual failure of the timbers and caving of supported ground 
 rarely come without warning. Either the timbers will at least 
 be bent quite appreciably before they break, or, as is usually 
 the case, they will crack and splinter and so give unmistakable 
 warning to the miner that the time is approaching when they 
 will collapse. The only way in which accidents can occur in 
 such cases is by carelessness or negligence in heeding the danger 
 signal. It may be said in this connection that, other things 
 being equal, timber which has a fiber that will spht, crack, or 
 spKnter out, rather than that which has a fiber that will break 
 off short under a transverse strain, is on this account more 
 desirable for such work. 
 
 Falls of rock are also caused by cars becoming derailed and 
 knocking out the supporting timbers under a heavy or loose 
 portion of the roof, allowing this material to fall and kill or 
 
SAFETY 293 
 
 injure any men who happen to be underneath. Such accidents 
 are in many cases unavoidable because of the difficulty in 
 preventing derailments. Owing to the lack of illumination, it is 
 usually impossible to see whether the track ahead is clear, and 
 it is therefore necessary to run more or less blindly and assume 
 that nothing has fallen upon the track since the last trip; besides, 
 the mere work of keeping the road-bed of a tunnel track in such 
 shape that its unevenness would no longer cause the cars to 
 jump off would be enormous. The only way, therefore, to 
 lessen these accidents (which are fortunately not so numerous 
 as those from other causes) is to keep the track in as good a 
 condition as possible and to use all reasonable watchfulness 
 and caution in tramming. 
 
 Use of Explosives 
 
 Next in importance as a cause of injury in tunnel work is 
 the careless, reckless, improper, or ignorant use (or rather 
 misuse) of explosives. Such accidents are of various kinds, 
 the most frequent being those arising from handling, storing, 
 and thawing dynamite, from premature blasts, from misfires, 
 or from suffocation by gases from explosives. 
 
 PRECAUTIONS 
 
 While the following Hst, which has been compiled from a 
 number of sources, does not pretend to be complete, it is given 
 here in the hope that it may once more repeat some of the pre- 
 cautions to be observed in the handling and use, not of dyna- 
 mite alone, but of the accessories of blasting as well. 
 
 Handling: 
 
 Don't forget the nature of explosives, but remember that 
 with proper care they can be handled with comparative safety. 
 
 Don't smoke while handfing explosives, and don't handle 
 explosives near an open fight. 
 
 Don't shoot into explosives with a rifle or pistol, either in 
 or out of a magazine. 
 
294 MODERN TUNNELING 
 
 Don't attempt to manufacture any kind of an explosive 
 except under the supervision and direction of a trustworthy 
 person who is skilled in the art. Many serious accidents, 
 which have destroyed lives or inflicted injury on persons and 
 property, have been caused by such attempts. 
 
 Don't carry blasting caps or electric detonators in the clothing. 
 
 Don't tap or otherwise investigate a blasting cap or electric 
 detonator. 
 
 Don't attempt to take blasting caps from the box by inserting 
 a wire, nail, or other sharp instrument. 
 
 Don't try to withdraw the wires from an electric detonator. 
 
 Storing: 
 
 Don't leave explosives in a wet or damp place. They should 
 be kept in a suitable, dry place, under lock and key, and where 
 children or irresponsible persons cannot get at them. 
 
 Don't store dynamite boxes on end, as this increases the 
 danger of nitroglycerine leakage from the cartridges. 
 
 Don't store or handle explosives near a residence. 
 
 Don't open packages of explosives in a magazine. 
 
 Don't open dynamite boxes with a nail-puller or powder 
 cans with a pick-axe. 
 
 Don't store or transport detonators and explosives together. 
 
 Don't store fuse in a hot place, as this will dry it out so that 
 imcoiling will break it. 
 
 Don't keep electric detonators, blasting machines, or blasting 
 caps in a damp place. 
 
 Don't allow priming (the placing of a blasting cap or electric 
 detonator in dynamite) to be done in a thawing-house or magazine. 
 
 Thawing: 
 
 Don't use frozen or chilled explosives. Most dynamite 
 freezes at a temperature between 45° F. and 50° F. 
 
 Don't thaw dynamite on heated stoves, rocks, sand, bricks, 
 or metal, or in an oven, and don't thaw dynamite in front of, 
 near, or over a steam boiler or fire of any kind. 
 
 Don't take dynamite into or near a blacksmith shop or near 
 a forge. 
 
SAFETY 295 
 
 Don't put dynamite on shelves or anything else directly over 
 steam or hot- water pipes, or other heated metal surface. 
 
 Don't cut or break a dynamite cartridge while it is frozen, 
 and don't rub a cartridge of dynamite in the hands to complete 
 thawing. 
 
 Don't heat a thawing-house with pipes containing steam 
 under pressure. 
 
 Don't place a ''hot-water thawer" over a fire, and never put 
 dynamite directly into hot water or allow it to come in contact 
 with steam. 
 
 Loading: 
 
 Don't allow thawed dynamite to remain exposed to low 
 temperature before using it. If it freezes before it is used, it 
 must be thawed again. 
 
 Don't fasten a blasting cap to the fuse with the teeth or 
 by flattening it with a knife; use a cap crimper. The ordinary 
 cap contains enough fulminate of mercury to blow a man's 
 head or hand to pieces. 
 
 Don't "lace" fuse through dynamite cartridges. This 
 practice is frequently responsible for the burning of the charge. 
 
 Don't explode a charge to chamber a hole and then immedi- 
 ately reload it, as the bore-hole will be hot and the second charge 
 may explode prematurely. 
 
 Don't force a primer into a bore-hole. 
 
 Don't do tamping with iron or steel bars or tools. Use only 
 a wooden tamping stick with no metal parts. 
 
 Don't handle fuse carelessly in cold weather, for when it is 
 cold it is stiff and breaks easily. 
 
 Don't cut the fuse short to save time. It is dangerous 
 economy. 
 
 Don't worry along with old broken leading wire or connecting 
 wire. A new supply will not cost much and will pay for itself 
 many times over. 
 
 Firing: 
 
 Don't explode a charge before every one is well beyond the 
 
296 MODERN TUNNELING 
 
 danger line and protected from flying debris. Protect the supply 
 of explosives also from this source of accident. 
 
 Don't hurry in seeking an explanation for the failure of a 
 charge to explode. 
 
 Don't drill, bore, or pick out a charge which has failed to 
 explode. Drill and charge another bore-hole at least two feet 
 from the missed one. 
 
 Premature Explosions ' 
 
 It is very often difficult to determine just what are the 
 causes of any particular premature explosion, because in such 
 cases the persons responsible for the explosion rarely survive 
 to tell the tale, and even eye-witnesses are scarce; but careless- 
 ness in handHng the dynamite in the heading is no doubt the 
 most potent factor. In many cases the so-called accident does 
 not result from the first instance of carelessness or of reckless- 
 ness, but is the disastrous cKmax of a series of practices that 
 have become habitual, so that persons knowing the common 
 disregard for dynamite on the part of the men who handled it 
 and were killed are able to draw very accurate conclusions 
 as to the probable cause of the "accident." As an example of 
 this, we cite the case of two men who were accustomed to throw 
 sticks of dynamite to each other along the tunnel, over dis- 
 tances of fifteen or twenty feet, especially if visitors with "nerves" 
 were present. But even at other times, perhaps because of 
 long familiarity with dynamite and hence a contempt or dis- 
 regard of its great dangerousness, the sticks were thrown to 
 each other rather than have the trouble to walk the few inter- 
 vening feet. The practice was finally stopped, however, as far 
 as these two personally were concerned, by a disastrous ex- 
 plosion in which they were blown almost to atoms, and which 
 (judging from the subsequent appearance of the tunnel) was 
 probably caused by the detonation of a stick falling near the 
 full supply for the entire round. 
 
 Another cause of premature explosions is the practice of 
 carrying dynamite to the face of the tunnel in a box or sack 
 
SAFETY 297 
 
 and dropping it quite roughly to the ground at the end of the 
 journey. This contempt is also bred, no doubt, by famiharity. 
 It is true that oftentimes gelatine dynamite is not so sensitive 
 to direct shocks as one might imagine, and that many times 
 it will stand very rough usage without detonation; but in other 
 cases, and there are very many of them on record, serious ex- 
 plosions have ensued when the care in handling might almost 
 be called extreme. It is therefore neither safe nor advisable 
 to rely in any degree whatsoever upon the ''inertness" of 
 dynamite, but at all times great care should be exercised in 
 handling it, if not out of regard for one's own security, then 
 for the sake of the lives and safety of fellow workmen. Nor 
 is it possible to condemn too strongly the practice of carrying 
 the denotators or the primers (sticks of dynamite containing a 
 detonator and a fuse) in the same bundle with the rest of the 
 supply of explosive for the round. They should always be 
 brought in separately and should under no circumstances be 
 placed in the same box, or even near together, after reaching 
 the heading. Many serious accidents have resulted through 
 disregard of this rule. 
 
 A certain amount of risk must always attend the loading of 
 a bore-hole with dynamite, especially during the insertion of 
 the primer, but much of the danger which often needlessly ac- 
 companies this work can be minimized or avoided by care 
 and caution in its performance. It is, of course, essential to 
 efficiency that there shall be no air spaces in the charge of ex- 
 plosive when it is finally ready for detonation, and in order to 
 insure this the dynamite must be rammed down so that it fiUs 
 all the unequal spaces in the bore-hole; but the packing should 
 always be done by pressure rather than impact, for some miners 
 use a tamping bar as if it were a javeKn. But even when pressing 
 down the charge, great care must be taken that too much force 
 is not employed, especially when a cartridge seems to stick in a 
 hole; for should it become suddenly loosened, the miner might 
 not be able to recover himself in time to prevent its being rammed 
 hard against the bottom, with diastrous results. Anything 
 more than light pressure should never be given the primer, and 
 
298 MODERN TUNNELING 
 
 under no circumstances should it or the succeeding cartridge 
 be struck a blow with the rod. 
 
 Irregularity in the rate at which fuse burns is also a cause 
 of premature explosions. Different makes and brands of fuse 
 burn at greatly varying rates and a miner accustomed to a 
 slow-burning fuse will perhaps not realize the necessity of cutting 
 the faster fuse longer, so that he may have time enough to reach 
 a place of safety before the detonation takes place. But there 
 are several causes which may produce variations in the burning 
 rate even of the same brand of fuse. For example, experiments 
 conducted by the Bureau of Mines * show that mere confinement 
 in a closed vessel is sufhcient to cause a fuse to burn three or 
 four times faster than its normal rate. It is true that under ordi- 
 nary conditions of mining variations of this magnitude are not 
 apt to be reached, but irregularities of 20 per cent, or even 30 
 per cent, are quite possible, and in long bore-holes in which a 
 quantity of tamping is used, and especially if it be of a type 
 impervious to the escape of the gases (such as closely packed 
 wet clay), the variation may be much greater. Therefore, 
 where such tamping is used, the rate of burning may be increased 
 to a dangerous extent, unless due allowance be made for this 
 extra speed. But even more important is the effect produced by 
 mechanical injury, which is more apt to be a common occurrence. 
 Mere bending of fuse (if it is in proper condition for use), such 
 as might result from coiling it near the collar of the hole to 
 prevent its being struck by flying rock from other blasts, or 
 even placing it with some force within the hole, has but Httle 
 if any effect upon the fuse; but abrasion, blows, or too great 
 pressure produce serious variations in its rate of burning and 
 in some cases may even cause it to burn almost instantaneously. 
 It is therefore essential that none but fuse in good condition 
 ever be brought into the heading, and that care be taken while 
 it is there to see that it is not injured by rocks or tools falHng 
 upon it, and that it is not abraded or otherwise injured with the 
 tamping bar while the hole is being loaded. 
 
 Mention must be made of the apparently obvious danger of 
 
 * Technical Paper 6. 
 
SAFETY 299 
 
 reloading a bore-hole before it has had time to cool off sufficiently 
 from a previous blast. In tunnel work this applies particularly 
 to the ''guns," as they are called — the ends of holes that have 
 not broken to the bottom with the first explosion — and accidents, 
 either through carelessness in not examining the holes or a desire 
 for haste overcoming better judgment, have been caused by 
 too early reloading of these guns after the first blast. 
 
 Misfires 
 
 Many deaths and injuries are caused by the subsequent 
 detonation of a charge of dynamite which failed to explode at 
 the proper time, though misfires do not mean accidents unless 
 the unexploded dynamite is detonated unexpectedly in some 
 way. Sometimes this is done by drilHng into it during prepar- 
 ations for the next round, or by striking it on the muck pile 
 where it has been thrown by the blast from a neighboring hole, 
 or perhaps by the sudden explosion of a delayed shot from a fuse 
 that has long been smoldering. 
 
 A large portion of these misfires can be traced directly to 
 some injury to the fuse. The insertion of the primer into the 
 hole, fuse-end first, often causes a crack in the fuse at the sharp 
 bend thus produced (and the danger of cracking it in this way 
 is especially great when the fuse is cold or the hole is full of 
 cold water), or sudden and rough uncoiling of the fuse in cold 
 weather will usually cause it to break. It is therefore obvious 
 that cold fuse should not be bent, twisted, or roughly handled. 
 It is claimed by some persons that misfires are caused through 
 the fuse being cut off ahead of the fire in it by the explosion of a 
 neighboring hole, so that consequently the charge of dynamite 
 fails to explode. There is some question whether this really 
 happens or not; but if it does, it is a pretty strong argument that 
 the hole in question was probably misplaced, for if it was properly 
 located, only in rare instances, if ever, would enough of the hole 
 be shot away to cut off the fuse ahead of the fire. It is also 
 claimed, and with somewhat more reason, that the fuse is apt 
 to be torn out by flying rocks from the explosion of other holes, 
 but this can be largely obviated if the fuse is properly coiled, as 
 
300 MODERN TUNNELING 
 
 it should be, close to the mouth of the hole before it is 
 ''spit." 
 
 The failure of a fuse properly to ignite a detonator is often 
 caused by improper storage. When the asphalt water-proofing 
 composition used in some fuses gets too hot, it becomes viscid 
 and agglomerates the powder grains in the core of the fuse, and 
 thus delays, and in some cases actually prevents, the fuse 
 from burning. Experiments conducted by the Bureau of 
 Mines * indicate that prolonged exposure at a temperature of 
 60° Centigrade is sufficient to cause a marked retardation in 
 the rate of burning. It follows, therefore, that fuse should not 
 be stored near boilers, steam pipes, or other sources of heat, 
 where the temperature is apt to be high. The effect of cold is 
 likewise deleterious, for it renders the asphalt composition 
 brittle and Kable to crack, and these cracks either decrease the 
 rate of. burning by permitting the gas from the powder core to 
 escape more readily than usual, or, if they are large enough, they 
 may stop the travel of the fire entirely. The fuse should be 
 carefully protected from moisture during storage; for, with 
 water-proof fuse of the type almost universally employed in 
 tunnehng, if the dampness once gets into the powder train it is 
 very difficult to get it out. As the fuse burns, this moisture is 
 driven ahead of the fire in the form of steam, and even if it 
 does not thus accumulate in sufficient quantity to quench the 
 fire in the fuse, enough of it may be driven into the detonator 
 to prevent its ignition and thus cause a misfire. 
 
 Misfires originate in many cases from improperly prepared 
 primers. Before inserting the fuse into the detonator, an inch 
 or two should be cut off and thrown away, for gunpowder 
 (which forms the core of the fuse) being somewhat hygroscopic, 
 the end of the fuse may have gathered sufficient moisture to 
 quench the burning powder or prevent the ignition of the cap; 
 this cut should be made with a sharp cutting tool squarely 
 across the fuse, for if cut diagonally the point may curl over 
 the end of the fuse when inserted in the detonator and thus 
 prevent the spit of the powder train from reaching the gun- 
 * Technical Paper 6. 
 
SAFETY 301 
 
 cotton (or the mercury fulminate) in the cap, causing a misfire. 
 Care should also be taken that the powder grains in the end 
 of the fuse do not leak out after the fuse is cut, for this would 
 tend to weaken the force of the spit into the detonator and might 
 prevent its ignition. The free end of the cap should be carefully 
 crimped around the fuse with a proper crimping tool, so that it 
 will be tight enough to hold the detonator and the fuse together 
 and keep out moisture, but the crimping should not be tight 
 enough to cut off the powder train in the fuse. This is par- 
 ticularly liable to happen when a narrow crimping tool is em- 
 ployed, which presses a very narrow groove in the detonator 
 and the underlying fuse. There are tools on the market which 
 have a crimping face of at least a quarter of an inch, and the 
 extra purchase price of several of these tools would be no more 
 than the cost of the explosive wasted by a single misfire, to say 
 nothing at all about the possible loss of Hfe that might arise 
 from it. It is of course obvious that the teeth or a knife should 
 never be used for crimping; for, as we have said, there is enough 
 explosive in an ordinary detonator to blow a man's head or 
 hand to pieces. After crimping, the detonator should be buried 
 in the end of the stick of dynamite with its axis parallel to that 
 of the stick, and the top of the detonator should be flush with the 
 top of the dynamite; for if the cap is buried deeper, the explosive 
 is Hable to become ignited from the side-spitting of the fuse 
 before it is properly exploded by the detonator, which not 
 only destroys the efficiency of the explosive, but causes a larger 
 amount of gases, especially those most dangerous to the men 
 who must breathe them. It is also important to use a detonator 
 of sufficient strength. Although 3 X caps were considered 
 strong enough for straight nitroglycerine dynamite, the less 
 sensitive gelatine dynamite requires a much stronger detonator 
 to explode it properly. For this reason nothing weaker than 
 5 X caps should ever be used with gelatine dynamite and the 
 universal experience is that better results have been obtained 
 where a change has been made to an even stronger detonator. 
 These insure the complete detonation of the explosive and 
 thus produce only a minimum amount of dangerous gases. 
 
302 MODERN TUNNELING 
 
 It is very difficult to count the explosions during blasting 
 and be sure that the charges have all been detonated, so that 
 it is not always possible to determine whether or not there has 
 been a misfire. For this reason the face, or as much of it as is 
 not covered by the debris resulting from the blast, should at 
 once be inspected for evidences of missed holes, and it should 
 be carefully watched during the removal of the muck. If a 
 missed hole is discovered, under no circumstances should an 
 attempt be made to pick out the material. If no tamping has 
 been used, as is usually the case in tunneling, a stick of dynamite 
 containing a detonator should be inserted in the hole and exploded 
 at once; if tamping has been employed, another hole should be 
 drilled and blasted at least two feet from the missed one. In 
 picking down the muck pile the pick should be handled as if it 
 were a hoe and not Hke a sledge hammer; i.e., the material should 
 be pulled or scraped down and never struck violently with the 
 point of the pick. In this way, should there happen to be a piece 
 of unexploded dynamite in the debris, there is much less danger 
 of an explosion resulting from it, with a corresponding injury 
 and loss of fife. The importance of this precaution cannot 
 be too strongly emphasized. Should a piece of dynamite be 
 discovered in the muck, it should be removed carefully and 
 handed to the foreman, who should at once take it to a safe 
 place, and the most extreme care should be used if a piece of 
 fuse accompanies it or is discovered near it, for this would 
 indicate that an unexploded detonator may possibly still be 
 inside of the stick of dynamite, the danger of which is obvious. 
 Under no circumstances should a new hole be started in the 
 remnants of a former hole that has ever held dynamite; for 
 although the inference is always, of course, that the dynamite 
 has been detonated, still there remains a chance that this might 
 not have occurred — a chance not so slight as might ordinarily 
 be supposed, to judge from the number of accidents traceable 
 to this source. And even if a rod is used to test the hole, it 
 might encounter a small rock and, by thus seeming to show the 
 bottom of the hole, fail to reveal the dynamite beneath. 
 
SAFETY 303 
 
 Suffocation by Gases from Explosives 
 
 Suffocation from the gases produced by explosives is a common 
 source of injury in tunnel work. Cases of this kind are familiar 
 to most miners; it is usually called "powder headache" in its 
 mild form and produces Httle more than temporary incon- 
 venience, but in severe cases it has been known to produce death 
 within a very short time. In the chapter on blasting it has 
 already been explained that the harmful gases resulting from 
 the complete detonation of dynamite under normal conditions 
 are usually carbon dioxide and carbon monoxide; that although 
 the former will not support respiration, and when present in 
 sufficient quantities may cause unconsciousness and even death, 
 it has no very injurious effects when sufficiently diluted; that the 
 latter is exceedingly dangerous and even small amounts of it 
 may prove fatal if breathed for a sufficient length of time. It 
 is this gas which probably causes the familiar symptoms after 
 a dose of "powder smoke." By a reference to the table on page 
 238 it will be seen that gelatine dynamite, the type ahnost uni- 
 versally used in tunnel work, under proper conditions generates 
 a comparatively small amount of the more dangerous gas. 
 Experiments conducted by the Bureau of Mines indicate that 
 even this can be obviated by a shght modification in the chemical 
 composition of the gelatine dynamite. But even if such a 
 dynamite is not completely detonated (either through the use of 
 too weak a detonator or for any other cause), and especially 
 when it burns rather than explodes, a much greater amount of 
 monoxide is formed and, in addition, a number of other harmful 
 gases are developed, among which may be mentioned the danger- 
 ous peroxide of nitrogen. It is therefore essential that deton- 
 ators of sufficient strength be employed to explode the dynamite 
 completely, and that every precaution be taken to prevent the 
 dynamite from taking fire through the side-spitting of the fuse 
 or in any other manner. 
 
 The deadhness of the gases resulting from explosives im- 
 properly detonated may be illustrated by describing one oc- 
 currence which is known to have cost nine lives. A study of 
 
304 MODERN TUNNELING 
 
 the attendant circumstances, as described in a communication 
 to the writers, indicates that the explosive, or a large portion 
 of it at least, must have burned rather than detonated. Gelatine 
 dynamite was employed and the charge was even smaller than 
 previous blasts of which the men had inhaled the fumes with- 
 out serious effects, but in this case the fumes are described by 
 the men as having been brownish-yellow rather than the usual 
 grayish or bluish-white. After igniting the blast the men retired 
 about 500 feet to wait for the smoke to clear, and while they 
 were waiting the smoke drifted slowly over them, and then, 
 owing to some change in the current, drifted slowly back again. 
 The men soon felt the usual symptoms of carbon monoxide 
 poisoning — slight choking, nausea, profuse perspiration, and 
 headache — ^but they all revived upon reaching the open air 
 about an hour and a half after the blast was fired. Within a 
 short time, however (and in one case before the man could walk 
 to the bunk-house), the men began to cough up bloody mucus 
 and exhibit other symptoms of nitrogen-peroxide poisoning, 
 and in less than three days nine of the thirteen men who had 
 been in the tunnel and exposed to the fumes had died. The 
 four who escaped were either not exposed to the gas for the full 
 time, or else found some other source of air supply which served 
 partly to dilute the gases ; but some of these men, as well as those 
 who went in with the motor to bring the men out, were ill for 
 days and even months after the catastrophe. A full discussion 
 of the customary symptoms that accompany poisoning from 
 nitrogen peroxide and carbon monoxide, and their comparison 
 with the symptoms exhibited by the men, will be found in the 
 April, 191 1, number of Colorado Medicine, and it is the opinion 
 of physicians who have studied this case that many swift deaths 
 among miners, formerly diagnosed as pneumonia, may really 
 have been caused by the inhalation of gases from burning 
 dynamite. 
 
SAFETY 305 
 
 Suffocation by Gases and Other Sources 
 
 Although the chief source of any carbon monoxide that is 
 liable to be encountered in tunnel work is usually to be found 
 in the dynamite employed, there have been cases in which this 
 dangerous gas was generated by the combustion of oil and 
 grease in the air-receiver and transmitted to the heading by the 
 compressed-air pipe. The causes of such combustion have been 
 fully discussed in the chapter on air compressors, so that it 
 need merely be mentioned here that the ignition of accumulated 
 oil and grease is generally due to faulty valves in the compressor. 
 These permit leakage back into the cylinder of the warm com- 
 pressed air, which, upon being recompressed, becomes still hotter, 
 so that after a time the temperature of the air in the receiver 
 may be built up far beyond the ignition point of the lubricant 
 employed. If an explosion does not then ensue, the oil on the 
 sides and bottom of the receiver will burn and produce carbon 
 dioxide or carbon monoxide, as the case may be, either of which 
 jeopardizes the safety of the miner in the lieading. It is, there- 
 fore, necessary to inspect the valves of the compressor regu- 
 larly; what is more, dependence should never be placed on 
 the compressed-air Kne for tunnel ventilation. 
 
 There are a number of tunnels in which natural deposits of 
 gas have been encountered, the two kinds most frequently found 
 being carbon dioxide and hydrocarbon gases. The former is, of 
 course, chiefly dangerous because of the possibility of the men 
 being overcome by suffocation, but this can largely be obviated 
 by sufficient ventilation, although sometimes at a considerable 
 additional expense. As an instance in point, one of the tunnels 
 on the Los Angeles Aqueduct might be mentioned, in which 
 currents of carbon dioxide were encountered in a series of crevices 
 across a zone about 150 feet wide. In order to make it possible 
 for the men to work in the tunnel, this zone and 300 feet on 
 each side of it were tightly sealed with concrete; in addition, it 
 was found necessary to leave an annular space back of the con- 
 crete in the center of the gas zone, to which a blower was con- 
 nected that constantly exhausted the gas during the driving of 
 
306 MODERN TUNNELING 
 
 the tunnel, while an additional blower forced in fresh air to the 
 men. When either of these machines ceased operating, it was 
 necessary for the men to get out of the tunnel as fast as possible, 
 but as long as they were kept running the air was sufficiently 
 pure. 
 
 The chief danger from hydrocarbon gases lies in their explo- 
 sibiHty, but they are so commonly met with in coal mining that 
 precautions to be taken in their presence are fairly well known. 
 A rather unique method of dealing with this problem, however, 
 — a method which is well worth a description — was employed in 
 one of the tunnels examined by the writers. 
 
 The gas was encountered in a zone approximately 2,300 feet 
 in extent, through about 500 feet of which oil could be distilled 
 from the rocks, although it did not flow of itself. The gas was 
 highly explosive and had an odor of kerosene or gasoline rather 
 than that of crude petroleum. The largest quantities of it came 
 into the tunnel immediately after blasting, from the rock broken 
 by each new round, and the maximum accumulation was approx- 
 imately 30,000 cubic feet. There appeared to have been no 
 particular seepages in the gaseous zone, but rather an unknown 
 quantity ahead of the work that had always to be reckoned with. 
 Since the gas was highly explosive, extra precautions had to be 
 taken for the safety of the men at work. The mere restriction 
 of permitting no open-flame lamps and requiring safety lamps 
 in the tunnel was not considered sufficient here, although that 
 is the usual practice in coal mines where similar gases are encoun- 
 tered, because the very nature of the rock was such as to cause 
 sparks from a pick or from the starting of a drill hole, and such 
 sparks were thought to be sufficient to ignite the gas and produce 
 an explosion. The expedient adopted was to explode the accu- 
 mulation after each blast and to burn any new gas as fast as it 
 appeared in the tunnel during the remainder of the work. 
 
 For this purpose the tunnel was wired from the portal to the 
 heading with a 5 50- volt circuit, into which were introduced at 
 intervals of about 200 feet, throughout the entire gas-bearing 
 section, a number of arcing devices. Any ordinary street arc 
 lamp could have been adapted for this work, provided that the 
 
SAFETY 307 
 
 carbons were not exposed for more than two inches; otherwise 
 the concussion from ordinary blasting, as well as from the gas 
 explosions, would have broken them. The use of one soft and 
 one hard carbon was found to give the best results. This system 
 was operated as follows: 
 
 Immediately after blasting, a fire boss and his helper took 
 charge of the tunnel. Waiting thirty minutes after the blast 
 was fired, they turned a current of electricity through the arc 
 line by means of a switch at the portal. Since the arcs were 
 purposely placed in series, in order to make certain that if any 
 one of them burned they must all necessarily do likewise, an 
 ammeter at the control switch showed whether or not they 
 had lighted. If such was the case, an explosion, which sometimes 
 would be a severe one, generally ensued. But whether this 
 happened or not, the switch was always opened for fifteen minutes 
 and then closed a second time as an added precaution, although 
 a second explosion never resulted from this operation. With 
 the line dead once more, the two men carrying safety lamps 
 then proceeded to a protected station approximately half-way 
 to the heading, where they again sent a current through the arcs. 
 A few explosions resulted from this practice, but they were un- 
 usual rather than customary. After having made this test, the 
 fire boss and his helper then proceeded to the heading, testing 
 the entire tunnel for gas by means of the safety lamps they 
 carried. They would ordinarily find an accumulation of gas in 
 the heading, extending back a distance of 125 to 150 feet, because 
 the nearest arc could not be placed much nearer to the heading 
 than the greater of these distances on account of the danger 
 of the carbons being broken by the concussion from the blasting. 
 The fire boss would then take an arc which was kept 150 feet 
 from the face and which was attached to the circuit by an 
 armored cable, and place it over the muck pile, when the two 
 men returned again to the midway station and once more 
 closed the circuit and ignited the remaining gas. Then, and 
 then only, and with all the arcs burning, they returned to the 
 heading and placed torches as near the roof as possible at inter- 
 vals of about 150 feet throughout the gaseous section. These 
 
308 MODERN TUNNELING 
 
 torches were lighted from the arcs, and the men were not per- 
 mitted to light them in any other way, or indeed to carry any 
 other means of Hghting them into the tunnel, thus insuring 
 that there should be open fire in the heading before the torches 
 were Hghted. By this time all the seepages that were strong 
 enough to support a steady flame would have been lighted and 
 would be burning, while the gas that came from pockets that 
 could not sustain a flame would be ignited by the torches before 
 it could accumulate in any quantity. The fire crew then returned 
 to the mid-station, where they extinguished a red light and 
 lighted a white one, indicating that the tunnel was safe for the 
 incoming crew, for no one but these two men was allowed in 
 the tunnel beyond this point unless the red fight was out and a 
 particular white one was burning.* The fire crew were allowed 
 four hours for this work, although it did not ordinarily take them 
 so long. 
 
 The working crew, upon reaching the heading, ordinarily 
 found the muck pile too hot to handle, if, indeed, it was not 
 actually in flames, for it burned usually for from one-half to 
 two hours after each blast, while once, at least, it burned for four- 
 teen hours. After it had been cooled sufficiently by streams of 
 both air and water, the machines were set up and the round of 
 holes drilled in the regular manner. Any gas that developed 
 during the drilfing of a hole was lighted as soon as the hole was 
 completed, and if sufficiently strong to support a flame, it would 
 burn until the end of the shift, and at one time as many as six 
 out of eight holes on the top round were burning fike blow-torches, 
 giving flames six to eighteen inches in length. When the round 
 was finished, the holes had to be cooled before loading. This 
 was accompKshed by turning water and air lines through ordi- 
 nary blow-pipes, both into the holes and over the face of the tun- 
 nel. The flames were, of course, extinguished by this process, 
 and as soon as the gas had accumulated in the tunnel sufficiently 
 to become apparent in a safety lamp placed near the roof, about 
 thirty feet from the heading, it was ignited by a torch, and the 
 
 * To obviate danger through any accidental extinguishing of the red light 
 without the knowledge of the fire crew, and before the tunnel was safe. 
 
SAFETY 309 
 
 resulting flames were at once put out again by air and water. 
 This process was continued until the holes were cool, when 
 they were at once loaded as rapidly as possible, and fired, the 
 fuses, in doing so, being always Hghted from near the bottom of 
 the tunnel. 
 
 Although the fact that there were no accidents in driving 
 through the gas-bearing zone after the installation of the "safety 
 arcs" shows that this system was efficacious in this particular 
 instance, it is not one that can be recommended unqualifiedly 
 for general use. In the opinion of engineers who have made a 
 special study of the question of safety in mining, the use of 
 anything but safety lamps, or their equivalent, in mines or 
 tunnels where explosive gases are known to exist, is never with- 
 out risk, while the practice of burning the gases as fast as they 
 make their appearance is in itself extremely hazardous. Indeed, 
 the fact that no disastrous explosion occurred under this system 
 seemed to them remarkable. Aside from this, it is obvious 
 that long delays were necessary before the men could start to 
 work, and even after they had reached the heading, the heat 
 must have greatly decreased their possible efficiency. A less 
 dangerous method of handhng a similar situation, and one that 
 would probably prove more economical in the end if everything 
 were taken into consideration, would be the installation of a 
 ventilating system large enough to dilute to harmlessness several 
 times the amount of gases ordinarily encountered, combined with 
 the absolute prohibition of any but safety lamps in the tunnel, 
 and the firing of all blasts by electricity. 
 
 Haulage 
 
 A large proportion of the injuries attributed to tramming 
 is caused by the practice of riding on the cars, and especially 
 upon the loaded ones. When riding upon the top of a full trip, 
 a man is always in danger of a serious injury at every low place 
 in the roof, and if he is riding between the cars (or any place 
 but the rear end) he is Hable to be jarred from his foothold and 
 dragged under the cars, while he has little chance of escape in 
 case of derailment. A certain risk of derailment is unavoidable 
 
310 MODERN TUNNELING 
 
 in tunnel work, partly because of the insufficient illumination 
 under which tramming is generally carried on, and partly 
 because of the difficulty, almost the impossibility, of keeping 
 the road-bed in good condition or the track clear of small obstruc- 
 tions. Even when riding upon empty cars there is serious risk 
 whenever the miner sits upon the ends or sides and allows his 
 feet to hang over; the safest way is to sit inside of the car and 
 to crouch low enough to avoid being struck by any jutting place 
 in the roof. The driver, or ^'mule skinner," is often compelled 
 to ride upon a loaded trip and sometimes at the front end of 
 the train in order to be near the animal he is driving, but the extra 
 hazard of this position should be fully realized and extra pre- 
 cautions taken. The practice observed on the part of some 
 drivers, of riding with one foot on the bumper and the other 
 on the chain by which the mule is attached to the first car of the 
 trip, the danger of which is obvious, cannot be too strongly con- 
 demned, and it should be made cause for the instant dismissal 
 of any driver caught doing it. It ought not to be necessary to 
 mention the danger of attempting to jump on or off a moving 
 trip of cars, because the chances in such a case of a man missing 
 his footing and being caught or dragged under the cars, or of 
 breaking an ankle or leg in the uncertain hght, should be so 
 clearly seen that no one ought to consider the risk worth taking; 
 but the number of injuries arising from this cause shows only 
 too well that this precaution is habitually disregarded. 
 
 Great care is necessary during, the operation of placing a 
 derailed car back upon the track. It is very easy for a miner 
 to strain or otherwise injure himself if he attempts to do this 
 without getting some one to assist him. Also in handling a 
 derailed car that is full of rock there is danger of block or crow- 
 bar sHpping and allowing the car to drop suddenly on the miner's 
 foot or hand, if indeed it does not topple over completely and 
 crush him against the side of the tunnel. 
 
 Failure to allow sufficient room to a passing trip of cars is 
 also a frequent source of injury. Before going into a strange 
 tunnel the miner (or any one else for that matter), if he is not 
 accompanied by some one familiar with the tunnel, should always 
 
• SAFETY 311 
 
 ascertain upon which side of the track there is the most room, 
 and in meeting a passing trip should always give an animal 
 pulling it all the space possible, to avoid being tramped on or 
 kicked by the horse or mule or being caught between the cars 
 and the walls of the tunnel. It is also advisable to hide any hght 
 when meeting a horse or mule, for there are some animals that 
 are afraid, especially of the high-powered acetylene lamps that 
 are coming to be used almost entirely in tunnel work; they will 
 balk when coming toward one and cause a serious mix-up, 
 since the cars behind cannot always be stopped at once. Respect- 
 ful attention in a tunnel, as on the surface, should always be 
 given the heels of animals whether moving or at rest, and it is 
 best to speak to them when approaching from behind, for many 
 serious injuries have been caused by passing too close to nervous 
 animals without warning. The driver also, when turning a horse 
 or mule around in a heading, should watch carefully to see that 
 he is not stepped on; inane as this advice sounds, many really 
 serious accidents have resulted from just this simple cause. 
 
 Electricity 
 
 An examination of reports of electrical accidents in tunnel 
 work shows that in the majority of cases the shocks were caused 
 by the trolley wire. This is not surprising when one considers 
 the many factors which unite to make electricity especially 
 dangerous underground. In the first place, the earth is almost 
 always used to complete the return circuit, and therefore, if the 
 miner inadvertently touches any portion of electrical apparatus 
 that is charged with current, and if he is not well insulated 
 from the ground, he will certainly get a shock the intensity of 
 which depends upon the voltage or pressure of the electric current 
 and the incompleteness of his insulation from the earth. It 
 is to be expected that the trolley wire should be the chief source 
 of electrical shocks, for it carries a current sometimes as high as 
 600 volts without any insulating or protecting covering what- 
 soever and generally without a guard or shield of any sort, 
 while it is usually placed less than a man's height from the 
 floor and has a rail beneath it to form a return circuit even 
 
312 MODERN TUNNELING 
 
 better than the earth. Then, too, tunnels are generally damp 
 or wet, so that a man is rarely well insulated from the ground; 
 the light at best is poor and one cannot always see the wire as he 
 approaches it, while the space is so restricted that a man in 
 walking in and out must keep his head close to the wire when, 
 at the same time, the most of his attention must needs be given 
 to the question of footing. Then, too, when climbing into 
 or riding in cars, which in tunnel work are almost always of 
 metal and furnish excellent electrical connection with the rails, 
 one's head must pass close to the live wire. The carr3dng of 
 metal tools, such as crow-bars or drill steel (although picks and 
 shovels are equally hazardous if the wooden handles are wet), 
 is also the cause of many shocks through their accidental contact 
 with the trolley, and this is especially liable to happen if such 
 tools are carried on the shoulder. It is therefore important, 
 when walking in a tunnel where a trolley wire is installed, con- 
 stantly to bear its existence in mind and take every precaution 
 to avoid contact with it by hand, wet clothing, or tools. 
 
 In addition to the trolley wire, there are in tunnel work 
 other sources from which electrical shocks may be received. 
 Wherever the heading is illuminated by electricity, the Hghts 
 are usually grouped in a cluster and connected to the main 
 circuit by means of a flexible cable, so that they can be easily 
 removed to prevent breakage during blasting. The wires of 
 the cable are, of course, insulated in such cases, but owing to 
 the rough usage they receive, it very often happens that the 
 insulation is damaged or scraped off, leaving the bare wire 
 exposed. Even if the injury is not severe, it is often sufficient 
 to permit a considerable leakage of current from which a person 
 handling the cable may receive a severe shock. Such wires are 
 the more dangerous because, supposing them to be protected, 
 one is more apt to handle them carelessly. The men who 
 remove these wires preparatory to blasting, and replace them 
 afterward or otherwise adjust them, should examine them 
 closely and not touch any place where the insulation has become 
 damaged. Shocks are also caused by motors, transformers, 
 or other pieces of electrical equipment which are supposed to be 
 
SAFETY 313 
 
 safe, but which may have become charged with current, or in 
 the adjusting or repairing of switches and other similar devices, 
 parts of which are known to be alive, but which are touched 
 accidentally in the course of the work. In handling apparatus 
 of this sort, a workman should carefully insulate or' otherwise 
 protect himself from the current and should try to handle the 
 apparatus in such a manner that any involuntary muscular 
 reaction from a shock will throw him clear of its live parts 
 rather than bring him in closer contact with them. Although 
 electric locomotives are usually in such perfect contact with the 
 rails that a person touching any accidentally charged part of the 
 frame will rarely receive a shock, there are times (as, for ex- 
 ample, when there is a considerable amount of dirt or sand on 
 the rails) when the locomotive is almost completely insulated 
 from them; in such a case any one coming in contact with a Hve 
 portion of the frame or of the draw-bar, or even with one of 
 the cars coupled to the locomotive, may receive a severe shock 
 which is apt to be all the more serious because it is unexpected. 
 For this reason the touching of such equipment should be 
 avoided when not actually necessary. 
 
 Mention should be made here of the immediate steps to be 
 taken in case a man has received a severe electric shock and is 
 perhaps lying unconscious and apparently dead from its effects; 
 for it is often possible by prompt treatment to revive and restore 
 a man in this condition when otherwise he might fail to recover 
 consciousness. The best methods suggested for such cases may 
 be found in Miners' Circular 5, published by the Bureau of 
 Mines, a copy of which may be obtained free upon application 
 to the Director, Bureau of Mines, Washington, D. C. 
 
 Fire 
 The chief danger to the men in a tunnel from fire is the 
 possibility of the buildings at the surface becoming ignited. 
 These structures are, of course, subject to the same causes of 
 fire as ordinary buildings, such as the careless handhng of matches 
 or lights, spontaneous combustion of oily waste wherever it is 
 allowed to accumulate, or the short-circuiting of electrical wires,. 
 
314 MODERN TUNNELING 
 
 not to mention the risk of forest fires in heavily timbered regions. 
 At a large majority of tunnels now being driven, the blacksmith 
 shop, the store room, the boiler house, or other buildings, are 
 situated much closer than the 200 feet which should separate 
 them from the tunnel portal, and in many districts, especially 
 where the winter snowfall is heavy, they are directly connected 
 with the tunnel by snow-sheds usually constructed of wood. At 
 such tunnels, also, other means of exit than the portal are seldom 
 provided, so that in case of fire in these buildings men are penned 
 up in the tunnel and, in the customary absence of a fire door, 
 they are in serious danger of suffocation from the gases and 
 smoke produced by the conflagration. It is, therefore, essential, 
 and in some States it is fortunately required by law, that in all 
 tunnels where combustible structures must be erected nearer 
 to the portal than 200 feet, there should be a separate exit at 
 least 200 feet away, and a fireproof door should be provided in 
 the tunnel that can be closed from a distance. At the same 
 time a sufficient water supply should always be maintained to 
 put out an incipient fire, and hydrants with a coiled i^-inch 
 hose and a nozzle should be placed not less than 40 feet and 
 not more than 100 feet from each building or group of buildings. 
 Although most tunnels are themselves practically fireproof 
 (except where timbered), and hence underground fires in tunnel 
 work are not common, it is, nevertheless, important even here 
 to guard against the dangers of fire. Whenever underground 
 fires do occur in tunnels, they usually start in some small way, 
 either from candles or lamps being placed too near the posts or 
 caps of a timber set, or from throwing a match or the coals 
 from a pipe into a pile of rubbish, hay, or other combustible 
 material which may in turn ignite the timbering. Although 
 such fires can usually be extinguished at once and before any 
 great damage or injury has resulted, if their presence is dis- 
 covered soon enough and if means are at hand for that purpose, 
 it is much better to prevent the ignition by obviating causes. 
 Therefore, combustible rubbish should not be allowed to accumu- 
 late in the tunnel and any supply of hay for the use of mules or 
 horses underground should be carefully confined in a bin pro- 
 
SAFETY 315 
 
 vided for that purpose, while open Hghts or smoking should not 
 be permitted in their neighborhood. Candles or torches should 
 never be left burning near timbers, while the practice of wedging 
 a lighted candle between two nails driven into a post should be 
 cause for the instant dismissal of the guilty persons. 
 
 Water 
 
 Water under pressure is another source of danger in tunnel 
 work, and men are hurt in jumping back to avoid the rocks and 
 other debris often carried with it, or are perhaps buried under 
 an accompanying rush of mud and sand. A good example of 
 this may be found in the records of a foreign railway tunnel, 
 where a cleft filled with water, sand, and gravel was encountered 
 and the ensuing sudden and violent inburst of these materials 
 filled up more than a mile of the tunnel in a very few minutes, 
 burying twenty-five workmen and their tools beyond all hope 
 of recovery. A somewhat similar occurrence in one of our 
 American tunnels, although fortunately with less fatal results, 
 was likewise due to water. The tunnel caved in at a point about 
 4,000 feet from the heading, but the men working there were 
 warned in time to escape, although they had barely reached 
 safety before the tunnel became entirely closed. When this 
 happened, the mass of rock, composed chiefly of soft clay and 
 running shale impervious to water, cut off the main flow in the 
 tunnel, which was approximately 2,700 gallons per minute. As 
 soon as the portion of the tunnel between the cave and the 
 heading became filled with water, the full pressure of the head 
 in the mountain over the tunnel was exerted against the dam, 
 forcing it down the tunnel until the pressure was relieved. The 
 additional length of the debris then offered greater resistance 
 and remained stationary until the pressure had again accumu- 
 lated enough to move it, and this process was repeated until 
 440 feet of tunnel had been filled. Several attempts were made 
 at first to relieve the pressure by inserting a section of venti- 
 lating pipe at the top of the dam; but after several men had 
 narrowly escaped burial by the rush of mud as the dam moved 
 forward, this scheme Was abandoned and the tunnel was sealed 
 
316 MODERN TUNNELING 
 
 up by a concrete bulkhead, the men being protected by a tempor- 
 ary bulkhead of wood during the construction of the permanent 
 one. 
 
 In driving through limestone and dolomite it is not unusual 
 for a tunnel heading to tap immense caves filled with water, 
 mud, and sand. In such cases the volume of the fluid mass 
 flowing into the tunnel is determined by the size of the opening, 
 while its velocity is proportionate to the head. Under a pressure 
 of 300 or 400 feet the cutting action of the rock particles and sand 
 carried by the water soon enlarges even a drill-hole to a size 
 that permits the filling up of the heading in an incredibly short 
 course of time. When a round of shots breaks into a cave of this 
 kind, the heading and perhaps the completed tunnel for a distance 
 of hundreds and sometimes even thousands of feet back from the 
 face may be filled so fast that the escape of the workmen would 
 be impossible if they were in the face. Fortunately, however, 
 at the time of greatest danger, viz., shot firing, the men are 
 always out of the heading. 
 
 When an underground cave or reservoir filled with water, 
 mud, sand, and loose rock is tapped in a tunnel heading one of 
 two things, occurs : generally the cave or reservoir empties itself 
 completely into the tunnel and, after the flow is over, the solid 
 matter which the flood leaves behind can easily be shoveled up 
 and hauled out; but it sometimes happens that the volume of 
 soHds is so great that the tunnel is completely choked up before 
 the reservoir is emptied. In these cases, when the flow of water 
 ceases, the men are usually set to work cleaning up the material 
 with which the tunnel has been filled, but when this cleaning-up 
 process advances sufficiently to weaken the dam which is holding 
 back the flood, a new outburst occurs and, because the passage- 
 ways have already been opened, the second outbreak is often 
 more violent and dangerous than the first. If this operation 
 were repeated often enough, the cave or reservoir would of 
 course be drained and the heading be regained, but in many 
 instances the operation of attempting to regain the heading has 
 been found so dangerous that it has been abandoned and a 
 curved tunnel put in to pass around the danger point. 
 
SATETY 317 
 
 In the Cowenhoven tunnel, when the heading was in dolomite, 
 caves of this kind, filled with water and dolomite sand, were fre- 
 quently encountered, and it was no uncommon thing to have the 
 tunnel completely filled for hundreds of feet back from the 
 face after a round of shots. As soon as the water from the 
 cave which had been tapped drained off, the mud and sand 
 were easily loaded up and work in the face was resumed. On 
 one occasion an immense . cave of this kind was tapped by a 
 drill-hole in a long cross-cut which was being driven from 
 the tunnel to the Delia S. Mine, which, under the pressure 
 and cutting action already described, enlarged so rapidly 
 that the men fled from the face and, a few seconds after, the 
 opening enlarged to a size which permitted the filling of the 
 tunnel with such rapidity that the tunnel cars were hurled 
 back and flattened against the posts. Several unsuccessful 
 attempts were made to regain this face, which finally had to be 
 bulkheaded and the tunnel run around it, as at the Loetschberg 
 tunnel. 
 
 In the 1,200-foot level of the Free Silver mine, which was 
 likewise run through dolomite, numerous caves were also en- 
 countered, but fortunately, while they must have extended to 
 great heights, their horizontal cross-section was very much less 
 than that of the caves 1,200 feet above. When these reservoirs 
 were tapped with a drill-hole the water would spout out with 
 such velocity that it was impossible to stay in the face, and in 
 a short time the opening would be worn to a size which some- 
 times increased the amount of water to be handled by the pumps 
 to 3,000 and even 4,000 gallons per minute. At first the noise 
 from the inrushing volume of water was exceedingly terrifying 
 to the men, but "familiarity breeds contempt," and in a short 
 time whenever a cave of this kind was tapped the men simply 
 joined hands to assist each other in maintaining their footing 
 and waded back with the torrent the same as they would do 
 in crossing an extremely rapid stream. Many narrow escapes 
 occurred, but, owing to the precautions taken by the manage- 
 ment and workmen, no serious accidents occurred during any 
 of these inrushes. 
 
318 modern tunneling 
 
 Intoxication 
 
 Although few accidents in tunnel work are traced directly 
 to intoxication, the extent to which it contributes to many 
 mishaps that are ascribed to other causes is perhaps too little 
 appreciated. The fact that a man who has put an enemy 
 into his mouth to steal away his brains is much more likely 
 to be careless or negligent of his own safety and the Hves of the 
 men around him is so well established as to need no emphasis. 
 Even a sHght degree of intoxication, that might be allowable 
 if the work had to be done on the surface, is dangerous under- 
 ground, where it is very apt to be greatly aggravated either by 
 . the lack of fresh air or by the heat, either of which is common 
 in tunnel headings. Therefore it is essential that a man in such 
 a condition should not be permitted underground and, if dis- 
 covered there, should be immediately sent out of the tunnel 
 by the foreman, while repeated offenses should result automatic- 
 ally in dismissal. 
 
 PREVENTION OF ACCIDENTS 
 
 In discussing the prevention of accidents in tunnel work 
 little is to be gained by saying that the manager or the foreman 
 or the miner is solely to blame for their occurrence. The greater 
 responsibihty lying, as ever, with those who have the broader 
 vision, the manager or the superintendent is in duty bound to 
 see that the place where the men are to work shaU be made as 
 safe as possible and to insist that they, themselves, exercise the 
 greatest care and caution in conducting their work. Then, again, 
 accidents are costly, not only of life and limb, but usually from 
 a financial viewpoint; for in many cases they either seriously 
 hinder the work or cause it to be shut down altogether for 
 months at a time, as, for instance, after a fire, or flood, or cave-in 
 — catastrophes which in many cases could have been prevented, 
 if even but ordinary precautions had been taken beforehand. 
 So, both from the humanitarian and from the economic point 
 of view, safety should come first, and the business of making the 
 
SAPETY 319 
 
 tunnel safe for the men to work in should be considered more 
 important than the driving of extra footage per month. Upon 
 the foreman falls the responsibihty of carrying out the man- 
 ager's orders, of seeing that the men are instructed in the 
 proper precautions to be taken, and that these are constantly and 
 consistently exercised, and, if necessary, of discharging either 
 temporarily or permanently any man who wilfully or habit- 
 ually disregards them. As for the miner, whose business is shown 
 by statistics to be a hazardous one at best, it is only through 
 the most extreme care on the part of each man, not only for his 
 own welfare but for the safety of his co-workers, that he can 
 hope to escape from the dangers that surround him. Each one 
 has his share, therefore, of the responsibihty, and it is only by 
 co-operation between all parties concerned that any progress 
 can be made toward the prevention and reduction of the 
 fatahties and the injuries now encountered in tunnel driving. 
 Since it is impossible to reiterate too often the methods of 
 obviating accidents, the following paragraphs are written 
 directly for the parties most concerned, in the hope of 
 bringing home to them once again some of the more important 
 preventive measures. 
 
 Precautions for the Manager or Superintendent 
 
 Insist that necessary timbering be done at once and always 
 keep an adequate supply of lumber at hand for this purpose, so 
 that no delay may ensue from the lack of it. See that the min- 
 imimi amount of explosive is used (in order to prevent unneces- 
 sary shattering of roof and walls) and inaugurate a systematic 
 and regular examination of the roof to insure the removal of all 
 loose pieces at once. Have all bent or breaking timber promptly 
 replaced by new posts or caps. 
 
 Provide suitable magazines and thaw-houses for explosives.* 
 
 Do not permit any disregard of the proper precautions in 
 
 handling, storing, or using explosives, such as are listed on 
 
 * Specifications for such buildings recommended by the Bureau of Mines 
 are to be found in Technical Paper i8, which may be had free on application 
 to the Director, Bureau of Mines, Washington, D. C. 
 
:320 MODERN TUNNELING 
 
 pages 293-96, and see that each man is provided with a copy 
 of these or similar precautions.* Do not permit the transporta- 
 tion of detonators or primers to the heading in the same bundle 
 with the remaining supply of explosive for the blast. Have 
 careful tests of the burning rate of the fuse made periodically, 
 especially whenever a different brand of fuse is purchased, and 
 warn the men of any discovered irregularity. Destroy any 
 damaged fuse at once. Do not store fuse near any source of 
 heat. Prohibit the reloading of a bore-hole before it has had 
 time to cool from a previous blast. Give the men proper tools 
 and have them instructed in the correct way to prepare a primer 
 and see that these instructions are obeyed. Do not purchase 
 caps weaker than 5 X for use with gelatine dynamite. See that 
 the proper precautions are taken whenever a missed hole or 
 evidences of one are discovered. 
 
 Institute a regular and frequent inspection of the valves on 
 the air compressor and insist that any defective valve be promptly 
 and properly repaired, even at the cost of a possible shut-down, 
 that there may be no explosion of gas or burning of grease in 
 the receiver or pipe-line to produce harmful gases and jeopardize 
 the safety of the men at the heading. Do not delay the installa- 
 tion of adequate auxiliary ventilating equipment when natural 
 deposits of harmful gases are encountered in the tunnel, and 
 this is particularly important when such gases are of an explosive 
 nature. In the latter instance, none but safety lamps or their 
 equivalent should be permitted underground. 
 
 Prohibit the men's riding on loaded trips and, whenever 
 possible, provide for their use special cars either propelled by 
 hand or drawn by a motor. Do not permit them to jump on or 
 off moving cars, nor the drivers to ''ride the chain." Tell all 
 new men the proper side of the tunnel to take when meeting a 
 trip, and caution them to shield any bright light when so doing. 
 
 If there is a trolley wire or other electrical apparatus in the 
 tunnel, caution the men against its danger, and do not allow 
 
 * A Miners' Circular containing these precautions may be obtained free 
 from the Director, Bureau of Mines, Washington, D. C, by forwarding the 
 names and addresses of the men for whom it is desired. 
 
SAFETY 321 
 
 them to carry tools on their shoulders when passing in or out. 
 See that the cables or wires leading to any temporary or movable 
 cluster of lights in the heading are kept in good repair. Instruct 
 the men, and especially the foremen, in the proper methods of 
 resuscitation in case of electrical shock. 
 
 Prohibit the accumulation of combustible rubbish anywhere 
 in the vicinity of buildings or timbering and see that the supply 
 of hay is properly confined to prevent danger from fire. Do not 
 construct any wooden buildings nearer than 200 feet from the 
 mouth of the tunnel, unless such are absolutely necessary, in 
 which case provide a separate exit from the tunnel at least 200 
 feet away, with a fire door so arranged that it may be closed 
 from a distance. In either event, provide an adequate water 
 supply, with hydrants and hoses, at suitable distances from the 
 several buildings. 
 
 Exercise great precaution when driving toward a place where 
 a flow of water is Hkely to be encountered that might carry 
 with it a rush of mud, sand, gravel, or other debris, and take 
 immediate steps for the safety of the men as soon as such a flow 
 is struck. 
 
 Prohibit the drinking of intoxicating liquors on property 
 controlled by the tunnel company, institute a system of inspec- 
 tion to prevent any intoxicated man from working in the tunnel, 
 and discharge habitual transgressors of this rule. 
 
 Precautions for the Foreman 
 
 Insist that the least amount of dynamite required for the 
 work shall be used in loading the top holes. Do not go yourself 
 or permit the men to return to the face after blasting, without 
 examining the new roof, and upon arriving at the heading detail 
 immediately as many men as may be required to clean the roof 
 before any other work is attempted under it. Never fail when 
 passing in or out of the tunnel to inspect the roof, testing any 
 doubtful piece for possible vibration. See that any loose piece 
 of rock is either pulled down at once or properly supported, and 
 never take any chances by postponing the work of timbering, no 
 matter how pressing other matters may be, because a few 
 
322 MODERN TUNNELING 
 
 minutes' delay in timbering may cost several lives. Have any 
 timbers showing the effects of too great pressure properly 
 relieved as soon as they begin to fail. When timbering is neces- 
 sary close to the face, see that the front sets are thoroughly 
 braced and blocked before firing. When the roof ''breaks 
 high" fill the space between the lagging and the roof with broken 
 rock or blocking to prevent a large rock from crashing through 
 the lagging upon the men beneath. 
 
 See that the men read the precautions to be taken in handling 
 explosives, or have a copy read to them. Do not permit any 
 instance of careless or reckless handling of explosives to go 
 unchallenged and do not fail to discharge men for the first grave 
 offense of this character. Never permit a man to handle dyna- 
 mite recklessly, either for the purpose of scaring some one or 
 for any other reason. See that the detonators and primers are 
 transported to the heading in separate boxes from the rest of 
 the supply and that they are not placed side by side after arriv- 
 ing. Insist that proper care be used in loading holes and that 
 the tamping be done by pressure rather than by impact. Never 
 allow anything but wooden bars to be used for this purpose. 
 Do not permit a bore-hole to be loaded before it has had sufficient 
 time to cool completely from the previous blast. 
 
 Warn the men of any change in the rate of burning of fuse. 
 See that they do not mutilate it by rough handhng or that it is 
 not cracked or broken by placing the primer in the hole fuse-end 
 first, or by uncoiling the fuse roughly in cold weather. Do 
 not use fuse that has been stored or kept near a boiler, steam- 
 pipe, or other source of heat, or that has been exposed to moisture. 
 See that the fuse is properly coiled close to the hole before 
 blasting, in order that it may not be torn out by blasts from a 
 neighboring hole. Instruct the men in the proper way to 
 prepare a primer. See that the fuse is cut squarely; that an 
 inch or so of it is discarded; that the grains of powder do not 
 leak out of the end that is inserted into the detonator; that the 
 crimping is done carefully with the proper tool; that the detona- 
 tor is not buried too deeply in the dynamite, and that caps 
 of sufficient strength are used. 
 
SAFETY 323 
 
 Always count the holes as they are blasted, and never fail 
 to inspect the new face for evidences of missed holes. See that 
 any such are detonated properly as soon as they are discovered, 
 even at the possible cost of some delay. Insist that the shovel- 
 ers use their picks properly when picking down the muck pile. 
 Keep a close watch for any unexploded dynamite in the muck, 
 and have the men do likewise; when such is found, remove it 
 carefully to a place of safety and be particularly cautious when a 
 piece of fuse accompanies it. Never start a new hole in the 
 remains of one that has ever held dynamite. 
 
 When the presence of any amount of dangerous gases, either 
 from explosives or from natural sources, is suspected, see that 
 the men are supplied with fresh air either by opening the com- 
 pressed-air line or by breaking into the ventilating pipe, if the 
 current is in the right direction. Do not willingly remain 
 or permit the men to remain in any atmosphere that will not 
 support a candle-flame, because there is no way to tell how bad 
 it may be getting after the light becomes extinguished, although 
 a man can exist for some time in such an atmosphere. See 
 that the men do not use anything but safety lamps or their 
 equivalent in tunnels where explosive gases are encountered, 
 and do not permit any means of striking an open light to be 
 carried into such a tunnel. 
 
 Have the track and road-bed kept in as good condition as 
 possible in order to lessen the risk of derailments. Do not 
 permit men to ride upon loaded trains unless it is absolutely 
 necessary, and in such cases warn them carefully as to the risk 
 being taken. Even when the men are riding in empty cars, 
 insist that they keep their feet and hands inside the car and 
 that they watch carefully for low places in the roof. Never 
 fail to discharge any driver caught '' riding the chain." See 
 that the men give an approaching train of cars plenty of room, 
 and, if animals are used to draw them, see that the men hide 
 their lights when the animals approach. 
 
 Warn the men of the danger from the trolley wire. Familiar- 
 ize yourself with the proper means of resuscitation after an 
 electrical shock. See that the men are not permitted to carry 
 
324 MODERN TUNNELING 
 
 on their shoulders tools or other instruments that are con- 
 ductors of electricity. Inspect regularly any cables or wires 
 for carrying electricity to Hghts in the heading, or any others 
 that have to be moved frequently, and see that all worn parts 
 are covered with insulating material or replaced if necessary. 
 Do not permit the men to ride on electric locomotives. 
 
 See that no piles of combustible rubbish are allowed to 
 accumulate underground, and do not permit the use of candles 
 or torches in the vicinity of hay or other inflammable sub- 
 stances. Do not fail to discharge any men guilty of leaving 
 candles or torches burning near timbers, and especially of 
 wedging a candle between two nails driven into a post. 
 
 Exercise special precautions when approaching a place 
 where an inrush of water is to be expected. 
 
 Be particularly cautious about drunkenness. Note the men 
 when coming on shift and do not permit even slightly intoxicated 
 men underground; if such a man is discovered in the tunnel, 
 send him to the surface at once. Discharge those who are 
 habitual offenders in this respect. 
 
 Precautions for the Min-er 
 
 Do not return to the face of the tunnel without testing the 
 newly exposed roof for loose rocks, and if any such are discovered 
 either clean them down yourself or report them to the foreman. 
 Form the habit of carefully examining the roof as you pass in 
 and out of the tunnel, testing doubtful places for vibration; call 
 the foreman's attention at once to any ground that you think 
 should be timbered or to any timbers that need relieving to 
 prevent their breaking. 
 
 If you are called upon to use dynamite, do so with great care, 
 observing the precautions outlined in previous paragraphs. 
 Never attempt to scare any one by reckless handling of explo- 
 sives, and never treat dynamite with roughness or rely in any 
 other manner upon its not exploding. Never place or carry 
 detonators or primers and the rest of the supply of dynamite for 
 the round in the same box or bundle. If it is your duty to assist 
 in the loading of the holes, do this with care, using pressure 
 
SAFETY 325 
 
 rather than a blow to tamp the powder in the hole, and always be 
 careful not to use too much force in pushing it. 
 
 Inquire as to the rate at which the fuse burns, especially when 
 a new brand is being tried, and see that the fuse is cut long 
 enough to give you and your companions time to reach a place 
 of safety. Protect the fuse from mechanical injury, such as 
 scraping, blows, or too great pressure either from falling rocks 
 or from the bar when tamping the hole; never use a fuse that 
 has been thus damaged. Never reload a bore-hole before it 
 has had time to cool. Do not use fuse that you know has 
 been stored near a boiler, steam pipes, or other source of heat, 
 or one that has been exposed to moisture. If you prepare 
 the primer, see that an inch or so is cut squarely from the end 
 of the fuse before it is put into the detonator; that no powder 
 runs out of the end of the fuse during this process; and that 
 the detonator is properly crimped around the fuse. Under 
 no circumstances use anything but the regular crimping tool 
 for this purpose. 
 
 Always inspect each new face for evidences of a misfire, and 
 if one is discovered, call the foreman's attention to it immedi- 
 ately, so that he may have it detonated. Never attempt to 
 pick out the material from such a hole; either explode it with a 
 primer, or, if this cannot be done, drill and fire another hole at 
 least two feet away. Use great care in removing any unexploded 
 dynamite from the muck pile and be especially cautious if a 
 piece of fuse is discovered near it, for this may show that there 
 still is a detonator in the cartridge. Never handle a pick like a 
 sledge hammer; pull or scrape the material down rather than 
 strike it with the pick. Do not start a new hole in the remnants 
 of a former one that has ever held dynamite, for there is always 
 a chance that it may not have been detonated. 
 
 Whenever you feel that you are inhaling fumes from dyna- 
 mite that has burned, or any other harmful gases, try to get tO' 
 fresh air as soon as possible; the quickest way to do this is of tern 
 to open the compressed-air Hne, or to break down the ventilating:, 
 pipe if you know that the current is in the right direction. Nevec 
 use anything but a safety lamp or its equivalent in a tunnel 
 
326 MODERN TUNNELING 
 
 where explosive gases are known to exist, and do not carry any 
 other means of striking a light into such a tunnel. 
 
 Never attempt to ride upon a full car or a loaded trip; and 
 when riding in an empty car see that your feet and hands are 
 well inside and your head is low enough to clear the roof at all 
 places. Learn which side of the tunnel has the most room and 
 always take all of it you can when a trip of cars approaches. If 
 it is drawn by an animal, hide any bright light you may be 
 carrying. If it is your duty to drive a horse or mule or to run a 
 locomotive, try to do everything possible to prevent derailments; 
 report any places where the track or road-bed is in bad condition. 
 Remember that the front end of the trip is the most dangerous 
 place you can occupy, so that if this is necessary, you must take 
 extra care; never under any circumstances ride with one foot on 
 the chain by which the cars are being pulled. Take care that 
 the animal does not step on you or kick you, and speak to him 
 before approaching him from the rear. In placing a derailed 
 loaded car back upon the rails, take care not to strain or other- 
 wise injure yourself in so doing; keep your feet and hands in a 
 safe position and see that the car does not topple over and crush 
 you against the sides of the tunnel. 
 
 Bear constantly in mind that the trolley wire is dangerous, 
 and that you must pass within a few inches of it when going in 
 and out of the tunnel, often when your attention must be given 
 to your footing. This is especially true when you climb into cars. 
 Never carry on your shoulders, when in a tunnel where there is a 
 trolley wire, tools or drill steel or anything else that is of metal 
 or wet. Do not handle any electrical equipment unnecessarily, 
 nor ride on electric locomotives. Never cause any one to receive 
 an electric shock; it is never possible to foretell its results. If it 
 is your duty to repair electrical apparatus, see that you are prop- 
 erly insulated, or that the current is cut off and cannot be turned 
 on without your knowledge; keep your hands and body in such 
 a position that a recoil from an accidental shock will throw you 
 clear of any charged part of the apparatus. In removing and 
 replacing the temporary cluster of electric Hghts in the heading, 
 be careful not to touch any bare or injured place in the wires and 
 
SAFETY 327 
 
 call the foreman's attention to any damaged place you may 
 discover. Familiarize yourself with the methods of reviving a 
 person injured by electric shock, and put them into practice as 
 soon as possible, whenever necessity occurs. 
 
 Do not smoke or throw a lighted match near any pile of inflam- 
 mable rubbish either in a building or near timbering, and do not 
 carry a candle or a torqh near any piles of hay. Never wedge a 
 candle between two nails on a post or other piece of timber; 
 many disastrous mine fires have started in just this way. 
 
 Never take a drink of liquor before or during working hours, 
 and do not hesitate to report any man you see doing so or who is 
 in an intoxicated condition; your safety and perhaps your life 
 may be sacrificed to his carelessness when under the influence 
 of Hquor. 
 
CHAPTER XVI 
 COST OF TUNNEL WORK 
 
 From the viewpoint of publicity, the cost of tunneling is per- 
 haps the most neglected feature of the work. Although the last 
 ten or fifteen years have witnessed a very considerable amount 
 of tunnel driving, and there is presumably a large amount of 
 cost data in existence, and although the articles describing 
 methods, equipment, and other features of many of these tunnels 
 have been numerous, only very few data regarding the cost 
 of the work, which is a very practical means by which the 
 efficacy of methods and equipment can be measured, have 
 found their way into the ordinary channels of publicity — the 
 engineering periodicals. This is possibly due in part to the 
 prejudice entertained by some contractors and tunnel men 
 against a pubHcation of their cost data; in other cases the men 
 actually do not know what the work has cost them, aside per- 
 haps from the difference between their bank account at the 
 beginning and at the end of the job; while others possibly are 
 unwilling to go to the trouble (for it does involve extra labor) 
 of preparing such matter for the magazines or other pubHca- 
 tions. 
 
 In an attempt to remedy this condition somewhat, there are 
 set forth on the following pages as complete and accurate data 
 as could be obtained, showing the cost of various phases of 
 tunnel work at a number of different tunnels. Although the 
 writers have not had the advantage of auditing the books from 
 which these figures were taken, and hence cannot vouch per- 
 sonally for the absolute accuracy of the figures, the data were 
 in all cases secured from persons in charge or those who were in a 
 position to know what the work actually cost. Accompanying 
 the figures is a brief list of the more important features of the 
 tunnel, without which it is impossible to make even an ap- 
 proximate comparison between any two pieces of tunnel work. 
 
 328 
 
COST OF TUNNEL WORK 
 
 329 
 
 CORONADO TUNNEL 
 
 Location: Metcalf, Arizona. 
 
 Purpose: Mine development and transportation. 
 
 Cross section: Square. 
 
 Size: 9 by 9 feet. 
 
 Length: 6,300 feet. 
 
 Rock: Granite and porphyry. 
 
 Type of power: Steam, with crude oil as fuel 
 
 Ventilation: Pressure blower. 
 
 Size of ventilating pipe: 12 inches. 
 
 Drills: 3 pneumatic piston drills for the first half of the tunnel, 
 
 3 pneumatic hammer drills for the last half. 
 Mounting of drills : Horizontal bar. 
 
 Number of holes per round: 21 in granite, 17 in porphyry. 
 Average depth of round: 6 feet. 
 
 Number of drillers and helpers per shift: 3 drillers, i helper. 
 Number of drill shifts per day: 3. 
 
 Explosives: 60 per cent, and 100 per cent, gelatine dynamite. 
 Number of muckers per shift: 4 to 6. 
 Number of mucking shifts per day: 3. 
 Type of haulage: Mules. 
 
 Maximum progress in any calendar month: 606 feet, June, 1913. 
 Average monthly progress: Approximately 415 feet. 
 
 COST OF DRIVING CORONADO TUNNEL 
 
 Footage 
 
 Supplies 
 
 June, 1912 . . . 
 
 July 
 
 August 
 
 September . . . 
 
 October 
 
 November. . . 
 December . . . 
 
 January, 19 13 
 February .... 
 
 March 
 
 April 
 
 May 
 
 June 
 
 July 
 
 August 
 
 Average . . . 
 
 117 
 340 
 531 
 303 
 345 
 290 
 328 
 
 295 
 312 
 
 505 
 442 
 420 
 606 
 573 
 392 
 
 $12.60 
 10.43 
 9.60 
 
 13-95 
 14.82 
 16.46 
 1473 
 
 18.04 
 16.24 
 13.28 
 14.07 
 15.61 
 
 12.35 
 12.32 
 12.36 
 
 $16.44 
 
 545 
 3.62 
 
 7-65 
 
 7-65 
 
 11.78 
 
 10.87 
 
 17.78 
 12.00 
 8.51 
 9-05 
 10.38 
 903 
 9-52 
 6.16 
 
 $29.04 
 15.88 
 13.22 
 21.60 
 22.47 
 28.24 
 25.60 
 
 35-82 
 28.24 
 
 21.79 
 23.12 
 
 25-99 
 21.30 
 21.84 
 18.52 
 
 $22.64 
 
330 MODERN TUNNELING 
 
 DETAILED COSTS, CORONADO TUNNEL 
 5,799 Feet 
 
 Labor ^°^^ P^"" ^°°^ 
 
 ^^"^"^ of Tunnel 
 
 Machine men $2 . 918 
 
 Mucking 3.399 
 
 Tramming and dumping i . 001 
 
 Power-house o • 79i 
 
 Track and temporary timbering 0.485 
 
 Tool-dressing o . 461 
 
 Supervision o . 334 
 
 Repairs to equipment 0.625 
 
 Equipment installation i . 740 
 
 General o . 756 
 
 Totallabor $13,512 $13,512 
 
 Supplies 
 
 Explosives $2 . 820 
 
 Fuel oil 2 . 280 
 
 Drill parts 0.612 
 
 Stock feed o. 185 
 
 Water o . 195 
 
 Temporary timber o . 330 
 
 Candles and carbide o . 150 
 
 Car repair parts o. 095 
 
 Electrical supplies o . 143 
 
 Blacksmith coal o . 100 
 
 Lubricants o . 158 
 
 Iron, sheet steel, etc 0.123 
 
 Belting, hose, etc o. 127 
 
 Building material o . 148 
 
 Drill steel o. 290 
 
 Miscellaneous 0.357 
 
 Total supplies $8. 124 $8. 124 
 
 Depreciation 
 
 Machine drills (50%) $0. 274 
 
 Track material (25%) o. 240 
 
 Pipe and fittings (50%) 0.388 
 
 Drill-sharpener (25%) 0.039 
 
 Pumps (25%) o.oii 
 
COST OF TUNNEL WORK 331 
 
 Depreciation 
 
 Motors and blowers (25%) $0,030 
 
 Compressor (5%) 0.013 
 
 Boilers (5%) 0.013 
 
 Total depreciation $1 . 008 $1 . 008 
 
 Total average cost of tunnel $22 . 64 
 
 GUNNISON TUNNEL 
 
 Location: Montrose, Colorado. 
 
 Purpose: Irrigation and reclamation. 
 
 Cross-section: Horse-shoe. 
 
 Size: 10 feet wide at the bottom; 10 feet 6 inches wide at the spring 
 
 line; 10 feet high at the spring line; 12 feet 4 inches high at the 
 
 center of the arch. 
 Length: 30,645 feet. 
 Rock: Chiefly metamorphosed granite with some water-bearing clay 
 
 and gravel, some hard black shale, and a zone of faulted and broken 
 
 material. 
 Type of power: Steam. 
 Ventilator: Pressure blower. 
 Size of ventilating pipe: 17 inches. 
 
 Drills: Pneumatic, hammer at first, four drills in the heading; pneu- 
 matic, piston to finish, four drills in the heading. 
 Mounting of drills: Horizontal bar for the hammer drills; vertical 
 
 columns for the piston drills. 
 Number of holes per round: 20 to 24 in the heading (approximately 
 
 one-half of the tunnel). 
 Average depth of round: 6 to 7 feet. 
 
 Number of drillers and helpers per shift: 4 drillers and 2 helpers. 
 Number of drill shifts per day: 3. 
 
 Explosive: 60 per cent, gelatin dynamite, with some 40 per cent. 
 Number of muckers per shift: 5 to 8. 
 Number of mucking shifts per day: 3. 
 Type of haulage: Electric. 
 Wages: Drillers, $3.50 and $4.00; helpers, $3.00 and $3.50; muckers, 
 
 $2.50 and $3.00; blacksmiths, $3.50 and $4.00; motormen, $3.00; 
 
 brakemen, $2.50 and $3.00; power engineers, $4.00. 
 Maximum progress in any calendar month : 449 feet. 
 Average monthly progress: 250 feet, approximately. 
 
332 MODERN TUNNELING 
 
 COST OF DRIVING THE GUNNISON TUNNEL 
 
 Cost per Foot 
 of Tunnel 
 
 10,019 f^^t driven by undercut heading and subsequent 
 
 enlargement $87 . 23 
 
 20,626 feet driven by top heading and bench 62 . 18 
 
 Average cost of excavation of entire tunnel $70 . 66 
 
 These costs include all labor, all materials, all repairs, all power, 
 depreciation figured as 100 per cent, on all equipment, with a pro- 
 portionate charge for general (supervisory) and miscellaneous ex- 
 penses of the entire reclamation project. 
 
 LARAMIE-POUDRE TUNNEL 
 
 Location: Home, Colorado. 
 
 Purpose: Irrigation. 
 
 Cross-section: Rectangular. 
 
 Size: 9>^ feet wide by 7>^ feet high. 
 
 Length: 11,306 feet. 
 
 Rock: Close-grained red and gray granite. 
 
 Type of power: Hydraulic at the east end, electric at the west. 
 
 Ventilator: Pressure blower. 
 
 Size of ventilating pipe: 14 and 15 inches. 
 
 Drills: 3, pneumatic hammer. 
 
 Mounting of drills : Horizontal bar. 
 
 Niunber of holes per round: 21 to 23. 
 
 Average depth of round: 10 feet at first; 7 to 8 feet later. 
 
 Number of drillers and helpers per shift: 3 drillers, 2 helpers. 
 
 Number of drill shifts per day: 3. 
 
 Explosive: 60 per cent, gelatine dynamite, with some 100 per cent, in 
 the cut holes. 
 
 Number of muckers per shift: 6. 
 
 Number of mucking shifts per day: 3. 
 
 Type of haulage: Mules. 
 
 Wages: Drillers, $4.50; helpers, $4.00; muckers, $3.50; blacksmiths, 
 $5.00; drivers, $4.50; dumpmen, $3.50. 
 
 Maximum progress in any calendar month: 653 feet, March, 191 1. 
 
 Average monthly progress: 509 feet (for the 16 months when complete 
 plant operated). 
 
 Special features: Inaccessibility; the tunnel was located about 60 
 miles from the nearest railroad siding and the roads were moun- 
 tainous and very steep in places. 
 
COST OF TUNNEL WORK 333 
 
 COST OF DRIVING THE LARAMIE-POUDRE TUNNEL 
 11,306 Feet 
 
 Per Foot of 
 Tunnel 
 
 Superintendents and foremen $1 
 
 Drilling 4 
 
 Mucking and loading 4 
 
 Tramming and dumping 4 
 
 Track and pipe 
 
 Power house 
 
 Blacksmithing 
 
 Repairs 
 
 Bonus to workmen i 
 
 Maintenance of camps, buildings, and fuel 
 
 Machinery repairs 
 
 Air drills and parts i 
 
 Picks, shovels, and steel 
 
 Explosives 4 
 
 Lamps and candles 
 
 Oil and waste 
 
 Blacksmith supplies 
 
 Liability insurance 
 
 Office suppUes, telephone, and bookkeeping 
 
 $29 
 Permanent equipment (less approx. 10 per cent, salvage) .... 9 
 
 50 
 47 
 92 
 
 63 
 47 
 35 
 84 
 47 
 75 
 62 
 12 
 
 33 
 84 
 
 50 
 42 
 
 38 
 53 
 81 
 86 
 
 $39-54 
 
 The permanent equipment included power plant, camp buildings 
 and furnishing, pipes, rails, etc. 
 
 LOS ANGELES AQUEDUCT 
 Little Lake Division, Tunnels i to ioa 
 
 Location: Inyo County, California. 
 
 Purpose: Water supply, power, and irrigation. 
 
 Cross-section: See Figure 6, p. 41. 
 
 Size: See Figure 6, p. 41. 
 
 Type of power: Electric power purchased at a nominal cost per kilo- 
 watt-hour from a hydrauUc plant constructed and owned by the 
 acqueduct. 
 
 Ventilators: Pressure blowers. 
 
334 MODERN TUNNELING 
 
 Size of ventilating pipe : 1 2 inches. 
 
 Drills: Pneumatic hammer, usually 2 in each heading. 
 
 Mounting of drills : Horizontal bar. 
 
 Number of holes per round: Usually 14 to 16. 
 
 Average depth of round: 6 to 10 feet. 
 
 Number of drillers and helpers per shift: 2 drillers and 2 helpers. 
 
 Number of drill shifts per day: Usually i, but sometimes 2. 
 
 Explosive: 40 per cent, gelatine dynamite, with some 20 per cent, and 
 
 some 60 per cent. Ammonia dynamite also tried. 
 Number of muckers per shift: Usually 5. 
 Number of mucking shifts per day: i usually, but 2 when 2 drill-shifts 
 
 were employed. 
 Type of haulage: Tunnels i to 3N, mules; tunnels 3S to 10 AN, 
 
 electric; tunnel loAS, mules. 
 Wages: Drillers and helpers, $3.00; muckers, $2.50; blacksmiths, 
 
 $4.00; helpers, $2.50; motormen, $2.75; dumpmen, $2.50. 
 
 COST OF DRIVING TUNNEL i-B-S, 1,341 FEET 
 
 Driven through medium hard granite at an average speed of 225 
 feet per month* 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation $915 
 
 Engineering .18 
 
 Adit proportion .28 
 
 Permanent equipment (estimated) 2.35 
 
 Timbering (857 feet) i . 02 
 
 $12.98 
 
 In this tunnel, as in all of the tunnels of this division and of the 
 Grapevine division, the cost of excavation includes the wages of the 
 following: Shift foremen, drillers, helpers, muckers, motormen or 
 mule drivers, dumpmen, blacksmiths and helpers, machinists, elec- 
 tricians (part), and power engineers. 
 
 It also includes the cost of the following suppHes: Powder, fuse, 
 caps, candles, light globes, machine oil, blacksmith suppHes and fuel, 
 and machinists' supplies. 
 
 It also includes the cost of power and of repairs for power, haulage, 
 compressor, and ventilating machinery. 
 
 ''Engineering" includes the cost of giving line and grade, etc. 
 
 * The average speed given is computed on the basis of one heading per 
 month. 
 
COST OF TUNNEL WORK 335 
 
 "Adit proportion" is a proportionate charge per foot of tunnel 
 to defray the cost of an adit from the surface to the tunnel line. 
 
 ''Permanent equipment " costs were not segregated for each tunnel, 
 but were compiled for the whole division, so that the charge repre- 
 sents a proportionate charge per foot for the entire division cost, 
 without salvage, of the following: Trolley and light Hnes, including 
 freight and cost of installation; pressure air lines with freight and in- 
 stallation; ventilating lines with freight and installation; water lines 
 with freight and installation; mine locomotives and cars, picks, 
 shovels, drills and drill-sharpeners, with repairs for the last four items. 
 
 COST OF DRIVING TUNNEL 2, 1,739 FEET 
 Driven through medium granite, but very wet, at an average speed of 
 
 170 feet per month. Cost per Foot 
 
 ' ^ of Tunnel 
 
 Excavation $8 
 
 Engineering 
 
 Adit proportion 
 
 Permanent equipment 2 
 
 Timbering (1,590 feet) 3 
 
 81 
 19 
 34 
 35 
 28 
 
 $14-97 
 
 COST OF DRIVING TUNNEL 2-A, 1,322 FEET 
 Driven through mediimi granite at an average speed of 150 feet 
 
 per month. Cost per Foot 
 
 ^ of Tunnel 
 
 Excavation $8 . 05 
 
 Engineering 
 
 Adit proportion 
 
 Permanent equipment 2 
 
 Timbering (1,322 feet) 2 
 
 $13.41 
 
 COST OF DRIVING TUNNEL 3-N, 1,148 FEET 
 Driven through medium hard granite at an average speed of 150 
 
 feet per month. Cost per Foot 
 
 ^ of Tunnel 
 
 Excavation $10 . 00 
 
 Engineering 23 
 
 Adit proportion 51 
 
 Permanent equipment 2.35 
 
 Timbering (956 feet) 2 .44 
 
 $15-53 
 
336 MODERN TUNNELING 
 
 COST OF DRIVING TUNNEL 3-S, 1,358 FEET 
 
 Driven through granite of variable hardness, and containing pockets 
 of carbon dioxide gas, at an average speed of 155 feet per month. 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation $12.38 
 
 Engineering 28 
 
 Adit proportion 16 
 
 Permanent equipment 2.35 
 
 Timbering (1,244 f^^t) 3 . 28 
 
 $18.45 
 
 COST OF DRIVING TUNNEL 3 COMPLETE (3 N AND 3 S) 
 4,044 FEET 
 
 Driven through decomposed granite of medium hardness, dissected 
 by .slips and talcose planes requiring timber where ground was 
 wet, and also containing pockets of carbon dioxide gas, making 
 work difficult and requiring extra provisions for ventilation. 
 Average speed, 140 feet per month. 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation $12.67 
 
 Engineering 24 
 
 Adit proportion 35 
 
 Permanent equipment 2.35 
 
 Timbering (3,570 feet) 2.71 
 
 $18.32 
 
 COST OF DRIVING TUNNEL 4, 2,033 FEET 
 
 Driven through medium to hard granite at an average speed of 145 
 feet per month 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation $12.00 
 
 Engineering 24 
 
 Adit proportion 16 
 
 Permanent equipment 2.35 
 
 Timbering (1,705 feet) 2.16 
 
 $16.91 
 
COST OF TUNNEL WORK 337 
 
 COST OF DRIVING TUNNEL 5, 1,178 FEET 
 
 Driven through medium to very hard granite at an average speed 
 of 1 20 feet per month 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation $11.10 
 
 Engineering 21 
 
 Adit proportion 08 
 
 Permanent equipment 2.35 
 
 Timbering (916 feet) i . 83 
 
 $15-57 
 
 COST OF DRIVING TUNNEL 7, 3,596 FEET 
 
 Driven through basic biotite granite of variable hardness at an 
 average speed of 140 feet per month 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation $13 • 55 
 
 Engineering 27 
 
 Adit proportion 13 
 
 Permanent equipment 2.35 
 
 Timbering (2,609 ^^^t) 3 . 60 
 
 $19.90 
 
 COST OF DRIVING TUNNEL 8-S, 1,334 FEET 
 
 Driven through medium to hard granite at an average speed of 135 
 feet per month 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation $12.82 
 
 Engineering 19 
 
 Adit proportion 18 
 
 Permanent equipment 2.35 
 
 Timbering (126 feet) 39 
 
 $15.93 
 
338 MODERN TUNNELING 
 
 COST OF DRIVING TUNNEL 9, 3,506 FEET 
 
 Driven through medium to hard granite at an average speed of 195 
 feet per month cost per Foot 
 
 of Tunnel 
 
 Excavation $12.19 
 
 Engineering 18 
 
 Adit proportion 07 
 
 Permanent equipment 2.35 
 
 Timbering (305 feet) 29 
 
 $15.08 
 
 COST OF DRIVING TUNNEL 10, 5,657 FEET 
 
 Driven through medium to hard granite at an average speed of 
 200 feet per month cost per Foot 
 
 of Tunnel 
 
 Excavation $13 . 50 
 
 Engineering 19 
 
 Permanent equipment , 2.35 
 
 Timbering (194 feet) 11 
 
 $16 
 
 15 
 
 COST OF DRIVING TUNNEL lo-A-N, 1,496 FEET 
 
 Driven through medium to hard granite at an average speed of 165 
 feet per month cost per Foot 
 
 of Tunnel 
 
 Excavation $13 . 02 
 
 Engineering 13 
 
 Permanent equipment 2.35 
 
 Timbering (24 feet) 78 
 
 $16.28 
 
 COST OF DRIVING TUNNEL lo-A-S, 2,200 FEET 
 
 Driven through medium to hard granite at an average speed of 200. 
 feet per month cost per Foot 
 
 of Tunnel 
 
 Excavation $12.37 
 
 Engineering 20 
 
 Permanent equipment 2.35 
 
 Timbering (215 feet) i . 15 
 
 $16.07 
 
COST OF TUNNEL WORK 339 
 
 Grapevine Division, Tunnels 12 to 17-B 
 Location: Kern County, California. 
 Purpose: Water supply, power, and irrigation. 
 Cross-section: See Figure 6, p. 41. 
 Size: See Figure 6, p. 41. 
 
 Type of power: Electric power purchased from aqueduct plant. 
 Ventilators : Pressure blowers. 
 Size of ventilating pipe: 12 inches. 
 Drills: Pneumatic hammer, usually 2 in each heading. 
 Mounting of drills: Horizontal bar. 
 Niunber of holes per round: Usually 18 to 20. 
 Average depth of round: 6 to 8 feet. 
 
 Number of drillers and helpers per shift: 2 drillers and 2 helpers. 
 Number of drill shifts per day: Usually 2. 
 Explosive: 40 per cent, ammonia dynamite, but 60 per cent, and 75 
 
 per cent, gelatine dynamite were employed in hard ground. 
 Number of muckers per shift: 4 or 5. 
 Number of mucking shifts per day: Usually 2. 
 Type of haulage: Electric after the first 400 to 500 feet. 
 Wages: Drillers and helpers, $3.00; muckers, $2.50; blacksmiths, 
 
 $4.00; helpers, $2.50; motormen, $2.75; dump men, $2,50. 
 
 COST OF DRIVING TUNNEL 12, 4,900 FEET 
 Driven through hard granite at an average speed of 185 feet per 
 
 month Cost per Foot 
 
 of Tunnel 
 
 Excavation* ...$22.10 
 
 Engineering* 32 
 
 Permanent equipment 2 . 25 
 
 Timbering (90 feet) 08 
 
 $24.75 
 
 COST OF DRIVING TUNNEL 13, 1,525 FEET 
 Driven through hard granite at an average speed of 130 feet per 
 
 month Cost per Foot 
 
 of Tunnel 
 
 Excavation $20 . 60 
 
 Engineering 10 
 
 Permanent equipment 2.25 
 
 Adit proportion 37 
 
 $23.32 
 
 * These items include the same costs as for the Little Lake division, see 
 page 334- 
 
340 MODERN TUNNELING 
 
 COST OF DRIVING TUNNEL 14, 859 FEET 
 
 Cost per Foot 
 of Tunnel 
 
 70 
 
 Excavation $22 
 
 Engineering 
 
 Permanent equipment 2 
 
 Adit proportion 
 
 Timbering (22 feet) 
 
 $25.96 
 
 COST OF DRIVING TUNNEL 15, 895 FEET 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation $23 . 28 
 
 Engineering 11 
 
 Permanent equipment 2.25 
 
 Adit proportion 2.42 
 
 $28.06 
 
 COST OF DRIVING TUNNEL 16, 2,723 FEET 
 
 Driven through hard granite at an average speed of 145 feet per 
 
 month 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation $20. 07 
 
 Engineering 17 
 
 Permanent equipment 2.25 
 
 Adit proportion 55 
 
 Timbering (18 feet) 04 
 
 $23.08 
 
 COST OF DRIVING TUNNEL 17, 3,024 FEET 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation ^ $20 . 47 
 
 Engineering 21 
 
 Permanent equipment 2.25 
 
 Timbering (142 feet) 22 
 
 $23-15 
 
COST OF TUNNEL WORK 341 
 
 COST OF DRIVING TUNNEL 173^, 1,345 FEET 
 Driven through medium to hard granite at an average speed of 
 225 feet per month 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation $19 . 56 
 
 Engineering 31 
 
 Permanent equipment 2.25 
 
 $22.12 
 
 COST OF DRIVING TUNNEL 17-A, 3,275 FEET 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation $18 . 70 
 
 Engineering 17 
 
 Permanent equipment 2.25 
 
 Timbering (441 feet) i . 18 
 
 $22.30 
 
 COST OF DRIVING TUNNEL 17-B, 4,915 FEET 
 
 Cost per Foot 
 of Tunnel 
 
 Excavation $21 . 09 
 
 Engineering 21 
 
 Permanent equipment 2.25 
 
 Timbering (163 feet) i . 90 
 
 I25.45 
 
 Elizabeth Lake Division, 
 ELIZABETH TUNNEL 
 Location: Los Angeles County, California. 
 Purpose: Water supply, power, and irrigation. 
 Cross-section: See Figure 6, p. 41. 
 Size: See Figure 6, p. 41. 
 Length: 26,870 feet. 
 
 Type of power : Electric power purchased from aqueduct plant. 
 Ventilator: Pressure blower. 
 Size of ventilating pipe: 18 inches. 
 
 Drills: Pneumatic hammer, 3 in the south heading and 2 in the north. 
 Mounting of drills: Horizontal bar. 
 
 Number of holes per roimd: 25 in the south heading; 16 in the north 
 heading. 
 
342 MODERN TUNNELING 
 
 Average depth of round: 8 to lo feet. 
 
 Number of drillers and helpers per shift: 2 drillers and 2 helpers at 
 
 the north end; 3 drillers and 3 helpers at the south end. 
 Number of drill shifts per day: 3. 
 
 Explosive: 40 per cent, and 60 per cent, gelatine dynamite. ' 
 Number of muckers per shift: 6. 
 Number of mucking shifts per day: 3. 
 Type of haulage: Electric. 
 Wages: Drillers and helpers, $3.00; muckers, $2.50; blacksmiths, 
 
 $4.00; helpers, $2.50; motormen, $2.75; dumpmen, $2.50. 
 Maximum progress in any calendar month: 604 feet, April, 1910. 
 Average monthly progress per heading: 350 feet per month. 
 
 COST OF DRIVING THE NORTH HEADING, ELIZABETH TUNNEL 
 Driven through altered granite requiring much timbering* 
 
 13,370 feet Cost per Foot 
 
 of Tunnel 
 
 Drilling and blasting $11 
 
 "Mucking and tramming 11 
 
 Engineering and superintendence i 
 
 Drainage 
 
 Ventilation 
 
 Light and power 5 
 
 Timbering (13,031 feet) 8 
 
 Cost of auxiliary shaft 
 
 Permanent equipment (full charge, no salvage — 
 estimated) 3 
 
 25 
 70 
 
 27 
 
 45 
 22 
 
 55 
 48 
 93 
 
 70 
 
 $43-55 
 
 COST OF DRIVING THE SOUTH HEADING, ELIZABETH TUNNEL 
 Driven through mediiun to hard granite requiring but little timbering* 
 
 I ^ , cjOO feet Cost per Foot 
 
 ^'^ of Tunnel 
 
 Drilling and blasting $14 . 65 
 
 Mucking and tramming 1 1 . 10 
 
 Engineering and superintendence 86 
 
 Drainage 17 
 
 Ventilation 41 
 
 Light and power 4 . 93 
 
 Permanent equipment (without salvage — es- 
 timated) 3 . 70 
 
 Timbering (3,424 feet) 2 . 19 
 
 $38.01 
 
COST OF TUNNEL WORK 343 
 
 LUCANIA TUNNEL 
 
 Location: Idaho Springs, Colorado. 
 
 Purpose: Mine development and transportation. 
 
 Cross-section: Square. 
 
 Size: 8 feet by 8 feet. 
 
 Length: 6,385 feet. 
 
 Rock: Hard granite. 
 
 Type of power : Purchased electric current- 
 
 Ventilator: Pressure blower. 
 
 Size of ventilating pipe: 18 and 19 inches. 
 
 Drills: Pneumatic hammer, 3 in the heading. 
 
 Mounting of drills : Vertical coliunns. 
 
 Niunber of holes per roimd: 25. 
 
 Average depth of round: 8 to 9 feet. 
 
 Nimiber of drillers and helpers per shift: 3 drillers and 2 helpers. 
 
 Nimiber of drilling shifts per day: i. 
 
 Explosive: 50 per cent, gelatine dynamite. 
 
 Niunber of muckers per shift: 3. 
 
 Number of mucking shifts per day: i. 
 
 Type of haulage: Horses. 
 
 Wages: Head driller, $5.00; drillers, I4.00; nipper, $3.50; boss mucker, 
 
 $5.00; muckers, $4.00; drivers, $4.00; power engineers, $4.00; 
 
 blacksmith, $5.00. 
 Maximiun progress in any calendar month: 263 feet, September, 191 1. 
 Average monthly progress: 125 feet per month for the first 4,800 
 
 feet; 240 feet per month for the last 1,575 feet. 
 
 AVERAGE COST OF DRIVING THE LUCANIA TUNNEL 
 
 First 4,800 feet 
 
 Cost per Foot 
 of Tunnel 
 
 Labor $8.86 
 
 Powder 7 . 86 
 
 Fuse and caps 17 
 
 Candles and oil 21 
 
 Horse feed and shoeing 18 
 
 Power 1 , 64 
 
 Repairs 14 
 
 Timnel equipment 2.75 
 
 Siurface plant 1.25 
 
 $23.06 
 
344 MODERN TUNNELING • 
 
 "Tunnel equipment" includes the cost of materials and installa- 
 tion of the pressure air line, the ventilating line, rails, ties and fittings, 
 and the drainage ditch. 
 
 "Surface plant" includes buildings, compressor, blower, trans- 
 formers, motors, and drill-sharpener. 
 
 AVERAGE COST OF DRIVING THE LAST 1,575 FEET 
 
 The contractor received $21.50 per foot to cover the cost of labor, 
 powder, fuse, caps, candles, oil, horse feed and shoeing, power and 
 repairs, and the installation of the tunnel equipment. 
 
 MARSHALL-RUSSELL TUNNEL 
 
 Location: Empire, Colorado. 
 
 Purpose: Mine drainage, development, and transportation. 
 
 Cross-section: Square. 
 
 Size: 8 feet by 8 feet. 
 
 Length: 11,000 feet projected; 6,700 feet driven, January i, 1913. 
 
 Rock: Granite and gneiss. 
 
 Type of power: Purchased electric current; also a small auxiliary 
 
 hydraulic plant. 
 Ventilator: Fan. 
 
 Size of ventilating pipe: 12 and 13 inches. 
 Drills: 2, pneumatic hammer. 
 Mounting of drills: Vertical columns. 
 Number of holes per round: 18 to 20. 
 Average depth of round: 9 to 10 feet. 
 
 Number of drillers and helpers per shift : 2 drillers and 2 helpers. 
 Number of drill shifts per day: i. 
 
 Explosive : 40 per cent, gelatine dynamite with some 80 per cent. 
 Number of muckers per shift: 4. 
 Number of mucking shifts per day: i. 
 Type of haulage : Horses. 
 Wages: Drillers, $4.00; helpers, $3.00; blacksmiths, $4.00; helpers, 
 
 $3.00; muckers, $3.25; trammers, $3.75; dumpmen, $3.25; power 
 
 engineer, $3.50; shooters, $3.25. 
 Maximiun progress for any calendar month: 187 feet, June, 1909. 
 Average monthly progress: 125 feet. 
 
COST OF TUNNEL WORK 345- 
 
 COST OF DRIVING THE MARSHALL-RUSSELL TUNNEL 
 6,700 Feet 
 
 Cost per Foot 
 of Tunnel 
 
 Labor $9-37 
 
 Powder, fuse, caps, and blacksmith coal 3 . 35 
 
 Drills, steel, and repairs (less 30 per cent, salvage) i . 34 
 
 Power 1 . 41 
 
 Permahent equipment and general expense (less 
 
 30 per cent, salvage on permanent equipment) 3 .41 
 
 $18.88 
 
 MISSION TUNNEL 
 
 Location: Santa Barbara, California. 
 
 Purpose: Water supply. 
 
 Cross-section: Trapezoid. 
 
 Size: 6 feet wide at the base; 4^^ feet wide at the top; 7 feet high. 
 
 Length: 19,560 feet. 
 
 Rock: Shale, slate, and hard sandstone. 
 
 Ventilator: Pressure blower. 
 
 Size of ventilating pipe: icinches. 
 
 Drills: i, pneumatic hammer. 
 
 Mounting of drills: Horizontal bar. 
 
 Number of holes per round: 12 to 14. 
 
 Average depth of round: 7 to 8 feet. 
 
 Number of drillers and helpers per shift: i. 
 
 Number of drilling shifts per day: 3. 
 
 Explosive: 40 per cent, and 60 per cent, gelatine dynamite. 
 
 Number of muckers per shift: 4. 
 
 Number of mucking shifts per day: 3. 
 
 Type of haulage: Electric. 
 
 Wages: Drillers, $3.50; helpers, $3.00; muckers, $2.75; blacksmiths, 
 
 $4.00; helper, $3.00; motormen, $2.75; dumpmen, $2.50; power 
 
 engineers, $2.75. 
 Maximiun progress in any calendar month: 414 feet, February, 1911. 
 Average monthly progress: 210 feet. 
 
346 MODERN TUNNELING 
 
 COST OF DRIVING THE SOUTH PORTAL, MISSION TUNNEL 
 
 May, 1909, to September, 191 1 
 5,515 Feet 
 
 Cost per Foot 
 of Tunnel 
 
 Administration* $1 . 14 
 
 Labor 9.20 
 
 Power 2.12 
 
 Explosives i . 97 
 
 Timbering (563 feet) 30 
 
 Track and pipe 1.22 
 
 Miscellaneous suppliesf 2 . 46 
 
 Drill parts (including steel) 1.02 
 
 Bonus 48 
 
 $19.91 
 NEWHOUSE TUNNEL 
 
 Location: Idaho Springs, Colorado. 
 
 Purpose: Drainage and transportation. 
 
 Cross-section: Square. 
 
 Size: 8 feet by 8 feet. 
 
 Length: 22,000 feet. 
 
 Rock: Idaho Springs gneiss. 
 
 Type of power: Purchased electric current. 
 
 Ventilator: Pressure blower. 
 
 Size of ventilating pipe: 18 inches. 
 
 Drills: Pneumatic hammer. 
 
 Mounting of drills: Vertical column. 
 
 Number of holes per round: 14 to 22. 
 
 Number of drill shifts per day: i and 2. 
 
 Explosive: 40 per cent, gelatine dynamite, with some 100 per cent. 
 
 in the cut holes. 
 Number of muckers per shift: 3. 
 Number of mucking shifts per day: i and 2. 
 Type of haulage: Electric. 
 Wages: Drillers, $4.00 to $4.50; helpers, $3.25 to $4.00; muckers, 
 
 $3.50; motormen, $3.50; dumpmen, $3.00; blacksmiths, $3.50 to 
 
 $4.50; helpers, $3.00. 
 
 * Includes superintendence, office supplies, and general charges, 
 t Includes candles, light globes, shovels, picks, blacksmiths' supplies and 
 fuel, and machinists' supplies. 
 
COST OF TUNNEL WORK 
 COST OF DRIVING THE NEWHOUSE TUNNEL 
 
 347 
 
 
 Jan. to Aug. 
 
 1909 
 
 2,233 feet 
 
 Sept. to Dec. 
 
 1909 
 
 1,098 feet 
 
 April to Aug. 
 
 1910 
 
 693 feet 
 
 Labor 
 
 $6.72 
 
 4.15 
 
 •39 
 
 1.49 
 1.99 
 1-57 
 
 1.50 
 
 1.74 
 .79 
 
 $6.98 
 
 3.52 
 
 .36 
 
 1.47 
 2.16 
 2.61 
 
 2.74 
 
 1.78 
 .80 
 
 $11.73 
 
 4.57 
 
 •44 
 
 2.22 
 
 2 82 
 
 Explosives 
 
 Fuse and caps 
 
 Transportation of broken 
 
 rock 
 
 Power. ... 
 
 Blacksmithing 
 
 2.00 
 
 Use of drills, repairs, and 
 steel 
 
 2.86 
 
 Equipment, ties, rails, pipe, 
 etc 
 
 2.19 
 1.85 
 
 Sundries 
 
 
 
 $20.34 
 
 $22.42 
 
 $30.68 
 
 RAWLEY TUNNEL 
 
 Location: Bonanza, Colorado. 
 
 Purpose: Mine drainage and development. 
 
 Cross-section: Trapezoidal. 
 
 Size: 8 feet wide at the base; 7 feet wide at the top; 7 feet high. 
 
 Length: 6,235 feet. 
 
 Rock: Tough hard andesite. 
 
 Type of power: Steam with wood for fuel. 
 
 Ventilator: Pressure blower. 
 
 Size of ventilating pipe: 12 and 13 inches. 
 
 Drills: 2, pneumatic hammer. 
 
 Moimting of drills: Horizontal bar. 
 
 Number of holes per round: 23 to 25. 
 
 Average depth of round: 8 to 9 feet at first; 5 to 6 feet later. 
 
 Number of drillers and helpers per shift: 2 drillers and 2 helpers. 
 
 Number of drill shifts per day: 2 at first; 3 later. 
 
 Explosive: 40 per cent, and 60 per cent, gelatine dynamite (in the 
 
 proportion of about 2 to i). 
 Number of muckers per shift: 4. 
 Number of mucking shifts per day: 2 and 3. 
 T)^e of haulage: Horses and mules. 
 Wages: Drillers, $4.50; helpers, $3.75; muckers, $3.50; blacksmiths, 
 
 $4.50; drivers, $4.50; power engineers, $4.00. 
 Maximum progress in any calendar month: 585 feet, July, 1912. 
 Average monthly progress: Approximately 350 feet. 
 
348 MODERN TUNNELING 
 
 COST OF DRIVING RAWLEY TUNNEL 
 6,235 Feet * 
 
 Cost per Foot 
 of Tunnel 
 
 Drilling and firing $5.25 
 
 Mucking 2.16 
 
 Tramming i . 13 
 
 Track and pipe 44 
 
 Miscellaneous underground expenses i . 44 
 
 Power plant 2 . 50 
 
 Blacksmithing 73 
 
 Miscellaneous surface work . 83 
 
 General expenses i . 98 
 
 Permanent plant 3-24 
 
 Timbering (1,618 feet) i . 18 
 
 Boarding-house, debit balance 04 
 
 $20.92 
 Credit by salvage on permanent plant i.ii 
 
 $19.81 
 
 "Drilling and firing" includes labor, powder, fuse, caps, supplies^ 
 and repairs. ''Mucking," "tramming," and "track and pipe" in- 
 clude labor and supplies. "Miscellaneous underground expenses "^ 
 includes wages of foremen, underground telephone, etc. "Power 
 plant" includes labor, supplies, and fuel. "Blacksmithing" and 
 "Miscellaneous surface work" include labor and supplies. "General 
 expenses" include salaries, office supplies, telephone, etc. "Per- 
 manent plant" includes machinery and buildings, with labor of 
 installation, steel rails, permanent supplies, and repairs. "Timbering" 
 includes labor and supplies. The salvage on the permanent plant 
 is approximately 50 per cent, on salable articles, such as machinery, 
 rails, cars, etc. 
 
 ROOSEVELT TUNNEL 
 
 Location: Cripple Creek, Colorado. 
 
 Purpose: Mine drainage. 
 
 Cross-section: Rectangular, with large ditch at the side. 
 
 Size: 10 feet wide by 6 feet high. 
 
 * A more detailed statement of the cost of this tunnel may be found in 
 Trans. Am. Inst. Mining Engineers, February meeting, 1913. 
 
COST OF TUNNEL WORK 349 
 
 Length: 15,700 feet. 
 
 Rock: Pike's Peak granite, chiefly. 
 
 Type of power: Purchased electric current. 
 
 Ventilator: Pressure blower. 
 
 Size of ventilating pipe: 16 and 17 inches. 
 
 Drills: 3, pneumatic hammer. 
 
 Moimting of drills: Horizontal bar. 
 
 Number of holes per round: 24, usually. 
 
 Average depth of round: 6 to 7 feet. 
 
 Number of drillers and helpers per shift: 3 drillers; 2 helpers. 
 
 Number of drill shifts per day: 3. 
 
 Explosive: 40 per cent., 60 per cent., and some 100 per cent, gelatine 
 dynamite. 
 
 Number of muckers per shift : 4, usually. 
 
 Number of mucking shifts per day: 3. 
 
 Type of haulage : Horses and mules. 
 
 Wages: Drillers, $5.00; helpers, $4.00; muckers, $3.50; power en- 
 gineer, $4.00; blacksmith, $5.00; helper, $3.50; dumpman, $3.50; 
 drivers, inside, $5.00; outside, $4.00. 
 
 Maximum progress in any calendar month: 435 feet, portal heading, 
 January, 1909. 
 
 Average monthly progress: Portal heading, 300 feet; shaft headings, 
 270 feet; all headings, 285 feet. 
 
 COST OF DRIVING ROOSEVELT TUNNEL 
 
 Total cost of portal work $111,980.06 
 
 Contractor's percentage 11,404.88 
 
 Cost of shaft headings 262,126 . 55 
 
 Total cost of tunnel $385,511 .49 
 
 Number of feet driven 14,167 
 
 Average cost per foot 27.21 
 
 COST OF DRIVING THE PORTAL HEADING 
 
 Month Footage Cost per Foot 
 
 Feb. and March, 1908 514 $22 . 690 
 
 April 262 30 . 970 
 
 May 268 26 . 760 
 
 June 187 35010 
 
 July 203 29 . 600 
 
 August 300 21 . 760 
 
 September 351 19.600 
 
 October 287 23 . 000 
 
350 
 
 MODERN TUNNELING 
 
 COST OF DRIVING THE PORTAL HEADING— ConHnued 
 
 Month Footage Cost per Foot 
 
 November 360 21 . 120 
 
 December 334 18 . 350 
 
 January, 1909 435 16 . 410 
 
 February 290 22 . 206 
 
 March 340 21 . 745 
 
 April 316 21 . 266 
 
 May 402 18 . 762 
 
 June (8 days) 62 40. 600 
 
 COST OF DRIVING SHAFT HEADINGS 
 
 Month 
 
 October, 1908 
 
 November 
 
 December 
 
 January, 1909 
 
 February 
 
 March 
 
 April 
 
 May 
 
 June 
 
 July 
 
 August 
 
 September 
 
 October 
 
 November 
 
 December 
 
 January, 1910 
 
 February 
 
 March 
 
 April 
 
 May 
 
 June 
 
 July 
 
 August 
 
 September 
 
 October 
 
 November 
 
 Footage 
 
 (2 headings) 49 
 
 141 
 177 
 261 
 601 
 
 639 
 670 
 
 552 
 498 
 
 (i heading) 319 
 
 410 
 
 355 
 
 380 
 
 298 
 
 251 
 
 282 
 
 259 
 
 344 
 
 376 
 
 393 
 
 373 
 
 350 
 
 372 
 
 342 
 
 372 
 
 192 
 
 Cost per Foot 
 $105.52 
 44.38 
 40.11 
 24.06 
 23.70 
 26.256 
 25.02 
 28,34 
 
 27-375 
 
 32.871 
 
 27.747 
 
 32.40 
 
 28.178 
 
 34.20 
 
 35-153 
 28.82 
 30.636 
 27.62 
 
 25-313 
 24-856 
 26.616 
 25.247 
 25.029 
 
 28.45 
 
 27.361 
 
 27.786 
 
COST OF TUNNEL WORK 351 
 
 TYPICAL DISTRIBUTION OF EXPENSES 
 
 Portal heading, Jxily, 1908 
 203 Feet 
 
 Cost per Foot 
 of Tunnel 
 
 Machinery and repairs $0.61 
 
 Air drills and parts 99 
 
 Picks, shovels, and steel i . 90 
 
 Ditch men i . 09 
 
 Explosives 6 . 90 
 
 Candles 36 
 
 Oil and waste 09 
 
 Electric power 2 . 06 
 
 Blacksmith suppHes 09 
 
 General expense 16 
 
 LiabiHty insurance 17 
 
 Lumber ties and wedges 01 
 
 Horses and feed .01 
 
 Compressor men i . 79 
 
 Drillers and helpers 4.21 
 
 Blacksmiths and helpers 3 . 43 
 
 Muckers and drivers 4. 11 
 
 Foremen i . 50 
 
 Bookkeeper .12 
 
 $29.60 
 TYPICAL DISTRIBUTION OF EXPENSES 
 
 Shaft heading, February, 19 10 
 259 Feet 
 
 Cost per Foot 
 of Tunnel 
 
 Maintenance of buildings, tents, etc $0. 096 
 
 Machinery and repairs i • 158 
 
 Air drills and parts i . 930 
 
 Shovels, picks, and steel i . 930 
 
 Pipe and fittings 193 
 
 Ditch men i . 480 
 
 Explosives 5 • 032 
 
 Lamps and candles 217 
 
 Oil and waste 252 
 
 Electric power 2 . 440 
 
 Blacksmith supplies 150 
 
352 MODERN TUNNELING 
 
 TYPICAL DISTRIBUTION OF EXPENSES^ Continued 
 
 Cost per Foot 
 of Tunnel 
 
 Liability insurance 213 
 
 General expense 342 
 
 Lumber, ties, and wedges 119 
 
 Horses and feed 324 
 
 Machine men and helpers 4 . 050 
 
 Muckers 3 . 065 
 
 Blacksmiths and helpers i .362 
 
 Engineers i , 300 
 
 Pipe and track men 675 
 
 Drivers and dumpmen 2.355 
 
 Foremen i . 753 
 
 Mine telephone . 008 
 
 Bookkeeper 193 
 
 $30-636 
 
 STILWELL TUNNEL 
 
 Location: Telluride, Colorado. 
 
 Purpose: Mine drainage and developmen 
 
 Cross-section: Square with ditch at side. 
 
 Size: 7 feet by 7 feet. 
 
 Length: 2,950 feet. 
 
 Rock: Conglomerate and andesite. 
 
 Type of power: Purchased electric current. 
 
 Ventilator: Fan. 
 
 Size of ventilating pipe: 10 inch. 
 
 Drills: Started with electric drills. Finished with pneumatic piston 
 
 drills, using 2 in the heading. 
 Mounting of drills: Vertical columns. 
 Number of holes per round: 16. 
 Average depth of round: 6 to 6}^ feet. 
 
 Number of drillers and helpers per shift: 2 drillers and 2 helpers. 
 Number of drill shifts per day: i. 
 Explosive: 40 per cent, gelatine dynamite. 
 Number of muckers per shift: 3. 
 Number of mucking shifts per day: i. 
 Type of haulage: Horses. 
 Wages: Drillers, $4.50; helpers, $4.00; muckers and trammers, $3.50; 
 
 blacksmith, $4.50. 
 Maximum progress in any calendar month: 170 feet, August, 1904. 
 Average monthly progress: 150 feet (last 10 months). 
 
COST OF TUNNEL WORK 
 
 353 
 
 COST OF 
 
 DRIVING THE STILWELL 
 
 TUNNEL 
 
 Fiscal Year 
 
 Footage 
 
 Cost per Foot 
 of Tunnel 
 
 1900-01 
 
 12 feet 
 
 $23.88 
 
 1901-02 
 
 490 " 
 
 22.98 
 
 1902-03 
 
 377 " 
 
 27.94 
 
 1903-04 
 
 702 '' 
 
 21.69 
 
 1904-05 
 
 1,077 " 
 
 21.19 
 
 1905-06 
 
 292 " 
 
 30-37 
 
 2,950 feet Average. $23. 38 
 
 These costs include all labor, supplies, repairs, powder, fuse, caps, 
 candles, tools, lubricants, and general expenses, and the total value 
 of the electric drill plant with which the tunnel was started and the 
 total value of the air drill plant which succeeded it, together with 
 tunnel buildings, pipe, rails, and the ventilator, with no credit for 
 salvage on any of this permanent equipment. 
 
 The fiscal year dated from September 30. 
 
 The tunnel was driven in 1901-02-03 with electric drills and the 
 high cost for 1905-06 was due to station cutting where the tunnel was 
 double size. 
 
 STRAWBERRY TUNNEL 
 
 Location : Utah and Wasatch counties, Utah. 
 
 Purpose: Irrigation and reclamation. 
 
 Cross-section: Straight bottom and walls, with arched roof. 
 
 Size : 8 feet wide by g}^ feet high. 
 
 Length: 19,100 feet. 
 
 Rock: Limestone with interbedded sandstone, and sandstone with 
 interbedded shale. 
 
 Type of power: Electric power generated in a hydraulic plant operated 
 in connection with the tunnel. Distance of transmission from 
 west portal to power-house, approximately 23 miles. 
 
 Ventilator: Pressure blower. 
 
 Size of ventilating pipe: 14 inches. 
 
 Drills: Piston pneumatic, usually 2 in the heading. 
 
 Mounting of drills: Vertical columns. 
 
 Number of holes per round: 16 to 18. 
 
 Number of drillers and helpers per shift: 2 drillers and 2 helpers. 
 
 Number of drill shifts per day: 3. 
 
 Explosive: 40 per cent, gelatine dynamite. 
 
 Number of muckers per shift: 6. 
 
 Number of mucking shifts per day: 3. 
 
354 
 
 MODERN TUNNELING 
 
 Type of haulage: Electric after first 2,000 feet. 
 
 Wages: Drillers, $3.50; helpers, $3.25; muckers, $2.75; motormen, 
 
 $3.25; brakemen, $2.75; blacksmiths, $4.00; helpers, $2.75. 
 Maximum progress in any calendar month: 500 feet, November, 19 10. 
 Average monthly progress: 320 feet per heading. 
 
 COST OF DRIVING THE STRAWBERRY TUNNEL 
 
 West heading, previous to 1909 1613 feet 
 
 " " during 1909 3892 " 
 
 " " during 1 9 10 5021 " 
 
 " " during 1911 3491 " 
 
 " " January to July, 191 2.. . 2382 " 
 
 East " Oct., 191 1, to July, 1912. 2682 " 
 
 Average for 19,081 feet 
 
 Cost per Foot 
 of Tunnel 
 
 $60 
 
 05 
 
 S3 
 
 58 
 
 30 
 
 56 
 
 41 
 
 52 
 
 36 
 
 79 
 
 33 
 
 04 
 
 I36 
 
 78 
 
 DETAILED COST OF DRIVING THE STRAWBERRY TUNNEL, 
 
 WEST HEADING, FOR THE YEAR 1909: 3,892 Feet 
 
 T oKr»r'« " Cost per Foot 
 
 ■l^a'DOr. of Tunnel 
 
 Engineering 
 
 Superintendence 
 
 Shift bosses i 
 
 Time-keepers 
 
 Drillmen and helpers 3 
 
 Miners (for hand work, trimming, etc.) 
 
 Muckers 2 
 
 Track and dumpmen 
 
 Mule drivers 
 
 Motormen and brakemen 
 
 Electricians and blowermen 
 
 Disabled employees 
 
 Timber men 
 
 Miscellaneous 
 
 Materials: 
 
 Powder, fuse, caps, etc $3 
 
 Lumber 
 
 Oils, candles, etc 
 
 Ventilating pipe 
 
 Track, including ties 
 
 Pressure air pipe 
 
 Drill repair parts (including hose) 
 
 Miscellaneous 
 
 49 
 73 
 22 
 
 36 
 15 
 23 
 96 
 
 74 
 39 
 44 
 07 
 
 19 
 22 
 40 
 
 08 
 29 
 22 
 
 64 
 68 
 40 
 18 
 19 
 
 In. 59 
 
 5-68 
 
COST OF TUNNEL WORK 355 
 
 Repairs: ^ ^ Cost per Foot 
 
 Machine shop expense (including labor and ^^ Tunnel 
 suppUes) $o . 93 
 
 Blacksmith shop expense (including labor and 
 
 supplies) 1.22 
 
 $2.15 
 
 Power (all purposes) 7.65 
 
 Depreciation: 
 
 Haulage equipment * $0 . 09 
 
 General equipment i . 00 
 
 1 . 09 
 
 General expense $3 . 96 
 
 Camp expense i . 21 
 
 Corral expense 25 
 
 5-42 
 
 Total $33.58 
 
 ''General expense" includes a proportionate charge for the ex- 
 penses of the Provo office, such as salaries, stationery, telephone, and 
 supplies; also a proportionate charge for the expenses of the Wash- 
 ington, the Chicago, and the Supervising Engineer's offices. The 
 Provo office covers approximately 68 per cent, of this charge, the 
 Washington office 23 per cent., the Chicago office 2 per cent., and 
 the Supervising Engineer's office 7 per cent. 
 
 DETAILED COST OF DRIVING THE STRAWBERRY TUNNEL, 
 WEST HEADING, FOR THE YEAR 19 10: 5,021 Feet 
 
 T ^ K^T. . Cost per Foot 
 
 LaDOr. of Tunnel 
 
 Engineering $0.61 
 
 Superintendence 60 
 
 Shift bosses 1.25 
 
 Time-keepers 22 
 
 Drillmen and helpers 2 . 85 
 
 Miners 28 
 
 Muckers 2 . 93 
 
 Track and dumpmen 71 
 
 Motormen and brakemen i . 49 
 
 Electricians and blowermen 13 
 
 Disabled employees 16 
 
 Timber men 28 
 
 Miscellaneous 07 
 
 $11.58 
 
356 
 
 MODERN TUNNELING 
 
 Materials: 
 
 Powder, fuse, caps, etc 
 
 Lumber 
 
 Oils, candles, etc 
 
 Ventilating pipe 
 
 Track, including ties 
 
 Pressure air pipe 
 
 Drill repair parts (including hose) . 
 Miscellaneous 
 
 Cost per Foot 
 of Tunnel 
 
 52 
 
 22 
 20 
 65 
 
 74 
 
 28 
 24 
 07 
 
 Repairs: 
 Machine shop expense (including labor and 
 
 supplies) $0 . 90 
 
 Blacksmith shop expense (including labor and 
 
 supplies) 1 . 23 
 
 Power (all purposes) . 
 
 Depreciation: 
 
 Haulage equipment $0 . 20 
 
 General equipment i . 00 
 
 General expense $3.32 
 
 Camp expense 63 
 
 Corral expense .08 
 
 Total. 
 
 $5.92 
 
 2.13 
 
 570 
 
 4.03 
 
 $30.56 
 
 DETAILED COST OF DRIVING THE STRAWBERRY TUNNEL, 
 WEST HEADING, FOR THE YEAR 191 1: 3,419 Feet 
 
 T « U^,. . Cost per Foot 
 
 J^aDOr. of Tunnel 
 
 Engineering $0 . 45 
 
 Superintendence 82 
 
 Shift bosses 1.65 
 
 Time-keepers 38 
 
 Drillmen and helpers 4.07 
 
 Miners 37 
 
 Muckers 5.13 
 
COST OF TUNNEL WORK 357 
 
 Cost per Foot 
 of Tunnel 
 
 Track and dumpmen $2 . oo 
 
 Motormen and brakemen 1.87 
 
 Electricians and blowermen .08 
 
 Disabled employees 48 
 
 Timber men 1.72 
 
 Miscellaneous 05 
 
 $19.07 
 
 Materials: 
 
 Powder, fuse, caps, etc $2 . 61 
 
 Limiber 80 
 
 Oils, candles, etc 43 
 
 Ventilating pipe 77 
 
 Track, including ties 1.52 
 
 Pressure air pipe 36 
 
 Drill repair parts (including hose) 34 
 
 Miscellaneous 25 
 
 Repairs: 
 Machine shop expense (including labor and 
 
 supplies) $2.16 
 
 Blacksmith shop expense (including labor and 
 suppHes) 1 . 54 
 
 7.08 
 
 3-70 
 
 Power (all purposes) 5 . 20 
 
 Depreciation: 
 
 Haulage equipment $1 . 85 
 
 General equipment 50 
 
 2.35 
 
 General expense $3 . 00 
 
 Camp expense i . 10 
 
 Corral expense 02 
 
 4.12 
 
 Total $41.52 
 
358 
 
 MODERN TUNNELING 
 
 DETAILED COST OF DRIVING THE STRAWBERRY TUNNEL, 
 WEST HEADING, JANUARY TO JULY, 1912: 2,382 Feet 
 
 Labor: 
 
 Cost per Foot 
 of Tunnel 
 
 Engineering $0 
 
 Superintendence 
 
 Shift bosses i 
 
 Time-keepers 
 
 Drillmen and helpers 3 
 
 Miners 
 
 Muckers -. 4 
 
 Track and dumpmen i 
 
 Motormen and brakemen i 
 
 Electricians and blowermen 
 
 Disabled employees 
 
 Timber men 2 
 
 36 
 56 
 08 
 26 
 08 
 43 
 95 
 55 
 33 
 18 
 48 
 59 
 
 Materials: 
 
 Powder, fuse, caps, etc $2.72 
 
 Lumber 2.13 
 
 Oils, candles, etc .32 
 
 Ventilating pipe 70 
 
 Track, including ties i • 51 
 
 Pressure air pipe 30 
 
 Drill repair parts (including hose) .32 
 
 Miscellaneous 39 
 
 $16.85 
 
 Repairs: 
 
 Machine shop (including labor and supphes) $1.39 
 
 Blacksmith shop (including labor and supplies).. . 1.02 
 
 Power (all purposes) 
 
 Depreciation: 
 
 Haulage equipment $2 . 20 
 
 General equipment 50 
 
 General expense $1 . 90 
 
 Camp expense 79 
 
 8-39 
 
 2.41 
 
 3-75 
 
 2.70 
 
 2.69 
 
 Total. 
 
 $36.79 
 
COST OF TUNNEL WORK 
 
 359 
 
 DETAILED COST OF DRIVING THE STRAWBERRY TUNNEL, 
 EAST HEADING, OCTOBER, 1911, to JULY 1912: 2,682 Feet 
 
 T 1 Cost per Foot 
 
 -Labor: of Tunnel 
 
 Engineering $0 . 49 
 
 Superintendence 77 
 
 Shift bosses 1.36 
 
 Time-keepers 31 
 
 Drillmen and helpers 3.62 
 
 Muckers 4 . 03 
 
 Track and dumpmen 2 . 00 
 
 Mule drivers 89 
 
 Timber men i . 80 
 
 Electricians and blowermen 30 
 
 Disabled employees 09 
 
 Miscellaneous 21 
 
 $15-87 
 
 Materials: 
 
 Powder, fuse, caps, etc I2 . 67 
 
 Lumber 93 
 
 Oils, candles, etc 36 
 
 Ventilating pipe 45 
 
 Track, including ties 56 
 
 Pressure air pipe 12 
 
 Drill repair parts (including hose) 38 
 
 Miscellaneous 21 
 
 Repairs : 
 
 Machine shop expense (labor and supplies) $0.62 
 
 Blacksmith shop expense (labor and supplies) 65 
 
 Power (all purposes) . 
 
 5-68 
 
 1.27 
 3.21 
 
 Depreciation : 
 
 Haulage equipment $0 . 47 
 
 General equipment 1.02 
 
 General expenses $1 . 86 
 
 Camp expenses 1.35 
 
 Corral expenses 95 
 
 Pumping (labor and material) . 
 Total 
 
 1.49 
 
 4.16 
 1.36 
 
 $33-04 
 
CHAPTER XVII 
 BIBLIOGRAPHY 
 
 The following is a selected bibliography of tunneling and related 
 subjects arranged by topics in chronological order. 
 
 TUNNEL DESCRIPTIONS 
 
 Raymond, R. W., ''The Rothschonberger Stollen/' Trans. A. L 
 M. E., Vol. VI, p. 542, 1877. Full description of this 
 famous old tunnel, giving its purpose, length, grade, cost, 
 method of driving, rate of progress, etc. 
 
 Anon., " Data of Tunnel Work, European,'' Min, Sci. Press, Vol. 
 XL VIII, pp. 306-322-338. May 3, 1884, contains a descrip- 
 tion of the Brandt drill and a table showing the monthly 
 progress on the Arlberg tunnel. May loth gives more 
 details of the drilling results. Bonus described. Also 
 gives description of the use of the Brandt drill at the Son- 
 stein and other places. May 17, 1884, work of the 
 Brandt drill in the Pfaffensprung tunnel. Concludes with 
 a statement of the advantages of the Brandt drill. 
 
 Charton, a. Pierre, " Arlberg Tunnel," Proc. Inst. Civ. Engrs., 
 Vol. LXXX, p. 382, 1885, 4 pages. Concise description of 
 this tunnel, the method of driving, ventilation, and costs. 
 
 Trevellini, Luigi, " The Carrito Cocullo Tunnel," Proc. Inst. 
 Civ. Engrs., Vol. LXXXII, p. 412, 1885. Description of 
 the tunnel followed by the rates of driving Mt. Cenis, St. 
 Gothard, Arlberg, Laveno, and Carrito tunnels. 
 
 W. H. E., "The Longest Tunnel in the World," Proc. Inst. Civ. 
 Engrs., Vol. LXXXVII, p. 496, 1886. A short description 
 of the mining tunnel at Schemnitz, in Hungary, which was 
 completed in 1878 and has a length of 10.27 miles. Cost of 
 tunnel, $4,860,000. 
 
 Anon., *'A Long Tunnel Completed," Min. Sci. Press, Vol. LII, 
 pp. 273-276, 4 cols., illus., Apr. 24, 1886. Describes the work 
 at the Big Bend tunnel which was driven to divert the 
 
 360 
 
BIBLIOGBAPHY 361 
 
 waters of the Feather River and make it possible to secure 
 the placer gold on the river bed at Big Bend. 
 
 Searles, W. H., " The Westpoint Tunnel," Proc. Inst. Civ. Engrs., 
 Vol. XCVI, p. 414, 1889. Description of the tunnel, method 
 of construction, cave, and method of recovery. 
 
 EspiNOSA, Luis, "Tequiquiac Tunnel," Proc. Inst. Civ. Engrs. j 
 Vol. CXXVI, p. 426, 1896. Description of a tunnel 5.9 
 miles long to drain the valley in which the City of Mexico 
 is situated. 
 
 Hay, David H., and Maurice Fitzmaurice, "The Blackwell 
 Tunnel," Proc. Inst. Civ. Engrs., Vol. CXXX, p. 50, 1897, 
 48 pages. Full description of this tunnel, together with a 
 discussion by the members of the institution. 
 
 Clauss, H., "The Simplon Tunnel," Proc. Inst. Civ. Engrs., Vol. 
 CXXXVII, p. 474, 1899. Condensed description of the 
 tunnel, giving grades, lengths, etc. 
 
 House, F. E., "North Bessemer Tunnel," Proc. Eng. Soc, West 
 Pa., Vol. XV, p. 238, June, 1899, 12 pages, 4 illus. Near 
 Carnegie Steel Works at Bessemer, Pa. Tunnel is 2,900 feet 
 long, 21.5 high in center of arch, and 26 wide. Av. speed, 
 four feet per day. Air operated shovels for bench. 
 
 Anon., "The Simplon Tunnel," Cassiers, Vol. XVH, p. 179, 
 Jan., 1900, 12 pages, illustrated with photos. More or less 
 popular account of this tunnel. 
 
 Body, John B., "The Draining of the Valley of Mexico," Proc. 
 Inst. Civ. Engrs., Vol. CXLIII, p. 286, 1901, 8 pages. De- 
 scription of the valley and review of attempts to drain it. 
 Gives full particulars of the work on the approaches to the 
 tunnel, together with a short description of the tunnel itself. 
 
 Rogers, A. E., "The Location and Construction of Railway 
 Tunnels with particulars of some recent work," Proc. Inst. 
 Civ. Engrs., Vol. CXLVI, p. 191, 1901, 10 pages. Treats 
 principally of English practice and covers the field indicated 
 by the title. 
 
 Hough, Ulysses B., "The Kellogg Tunnel," Min. and Min., 
 p. 122, Oct., 1 90 1. Describes the methods used in driving 
 this tunnel in Idaho. 
 
362 MODERN TUNNELING 
 
 Clapp, a. W., "The Aspen Tunnel," E. M, /., Vol. LXXIII, 
 p. 519, Apr. 12, 1902, 3>^ columns. Describes some of the 
 difficulties in the U. P. R. R. tunnel, Wyoming. Use of 
 steam shovel noted. 
 
 Bain, H. F., "Driving the Newhouse Tunnel," E. M. /., p. 552, 
 Apr. 19, 1902, 6 columns, illustrated. Describes the methods, 
 equipment, and costs of this work. 
 
 Wilson, W. B., "The Cripple Creek Drainage Tunnel," Min. 
 Set. Press, Vol. LXXXVI, p. 36, 3 cols., p. 336, i col., and 
 Vol. LXXXVII, p. 130, H cols. Describes the El Paso 
 Drain Tunnel. 
 
 HoBLER, George A., "Tunnels on the Cairns Railway, Queens- 
 land, AustraHa," Proc. Inst. Civ. Engrs., Vol. CLII, p. 221, 
 1903. Portion of a paper on the construction of the moun- 
 tain portion of this railway. Gives methods of driving, an 
 illustrated description of timbering, etc. 
 
 Anon., "The Simplon Tunnel," Min. and Min., Vol. XX, p. 390, 
 }4 col. Note concerning the use of parallel headings in 
 this tunnel and the use of the Brandt hydrauUc drill. 
 
 Anon., "Katterat and Nordal Tunnels, on the Ofot Railway, 
 Sweden," Proc. Inst. Civ. Engrs., Vol. CLVI, p. 450, 1904. 
 Description of the hydro-electric power plant, air mains, 
 drills, methods of driving, etc. 
 
 Anon., "The Drainage Tunnel in Mining," Min. Sci. Press, Vol. 
 LXXXIX, p. 203, Sept. 24, 1904, I col. editorial. Dis- 
 cusses the drainage of 'mines by tunnels and mentions sev- 
 eral examples. 
 
 Trench, E. F. C, "Alfreton Second Tunnel," Proc. Inst. Civ. 
 Engrs., Vol. CLXI, p. 116, 1905, 9 pages. Descriptions of 
 methods of driving, drainage, ventilation, etc. 
 
 Brunton, D. W., ''Drainage of the Cripple Creek District," 
 E. M. J., Vol. LXXX, p. 818, 12 cols. Report of the Con- 
 sulting Engineer as to the feasibility of the project and the 
 methods to be employed. 
 
 Anon., "Simplon Tunnel," Min. Sci. Press, Vol. XCI, p. 399, 
 Dec. 9, 1905, 2 cols. 
 
 Ripley, G. C, and others, "The Newhouse Tunnel," Min. and 
 
BIBLIOGRAPHY 363 
 
 Min.^ Vol. XXVII, p. 36, Aug., 1906, 5 cols., p. 72, 5>^ cols. 
 Describes the equipment and discusses the methods employed 
 and the cost of driving. 
 
 Herrick, R. L., "The Joker Drainage Tunnel,'* Jfm. and Min.y 
 Vol. XXVII, p. 470, 1906, 8^ cols., 6 illus. Description of 
 methods and equipment. 
 
 Haupt, L. M., "Great Tunnels," Cassiers, p. 175, Dec, 1906, 
 3 cols. Mentions several great tunnels both in this country 
 and abroad. 
 
 HiLDAGE, H. T., "Mining Operations in New York and Vicin- 
 ity," Trans. A. I. M. E., Vol. XXXVIII, p. 360, 1907, 
 37 pages. A very complete description of the tunnels in 
 the neighborhood of New York City, with methods of 
 driving them. 
 
 Pressel, Dr. K., "Works of the Simplon Tunnel," Proc. InsL 
 Civ. Engrs.j Vol. CLXVII, p. 411, 1907. A short review of 
 a number of articles published in the Swiss scientific papers, 
 bringing the history of the undertaking down to the open- 
 ing of the tunnel for traffic. 
 
 Fox, Francis, "The Simplon Tunnel," Proc. Inst. Civ. Engrs.y 
 Vol. CLXXV, p. 61, 1907, 50 pages, illus. A most complete 
 and comprehensive description of the tunnel, methods of 
 driving, plans adopted to overcome the difficulties encoun- 
 tered, costs, etc. 
 
 DiNSMORE, W. P. J., "Western Practice in Tunnel Driving," 
 Mine and Quarry, p. 1 18, May, 1907, 5 pages, illus. Describes 
 the equipment and methods used in driving the Ophelia 
 tunnel. Cripple Creek, Col. 
 
 Anon., "The Commercial Aspects of Present and Proposed 
 Alpine R. R. Tunnels," Editorial, Eng. News, p. 613, Dec. 5, 
 1907, 3 pages, with excellent map, showing sixteen tunnels 
 in the Alps. 
 
 CoMSTOCK, Chas. W., "Great Tunnels of the World," Colo. Sci, 
 Sac, Vol. VIII, p. 363-386, Dec. 7, 1907. Discusses tem- 
 perature and pressure in deep tunnels. Describes the Mt. 
 Cenis, the Hoosac, the St. Gothard, and the Simplon 
 tunnels. 
 
364 MODERN TUNNELING 
 
 Anon., "Preliminary Work on the Los Angeles Aqueduct," Eng. 
 Rec, p. 144, Feb. 8, 1908, 3K pages, illus. Describes scheme 
 of aqueduct and work done up to Jan. i, 1908. Describes 
 power plants for supplying aqueduct. Describes equipment 
 for Elizabeth tunnel. 
 
 Anon., ''The Second Raton Hill Tunnel of the A. T. and Santa 
 Fe Railway," Eng. Rec, p. 461, Apr. 4, 1908, 7 cols, illus. 
 Describes the methods and equipment used in this work. 
 
 Anon., "A Private Sewer in Rock Excavation," Eng. Rec, 
 p. 496, Apr. II, 1908, 8 cols., illus. Describes construction of 
 a six-foot sewer draining submerged yards of the new Grand 
 Central station. New York. 
 
 RiDGEWAY, RoBT., ' ' Sub-surf ace Investigations on the Catskill 
 Aqueduct," Eng. Rec, p. 522, Apr. 18, 1908, 8 cols., illus., 
 and Eng. Rec, p. 557, Apr. 25, 1908, 8 cols., illus. Describes 
 preliminary explorative investigations. Abstract of a paper 
 before municipal engineers, New York City. 
 
 DiNSMORE, W. P. J., ''The Second Raton Hill Tunnel of the 
 Atchison, Topeka and Santa Fe Railway," Mine and Quarry, 
 p. 225, June, 1908, 10 cols., 5 illus. Describes the methods 
 and equipment used in this work. 
 
 BuNCE, Walter H., "Tunnel Driving at Low Cost," Min. Sci. 
 Press, p. 60, July 11, 1908. Discusses the equipment, meth- 
 ods, and costs of driving the Chipeta Adit at Ouray, Col. 
 
 DiNSMORE, W. P. J., "Western Practice in Tunnel Driving," 
 Min. and Met. Journal, Aug. 7, 1908, 3 pages, illus. Plan of 
 work, arrangement of holes, handling of waste rock, and 
 other important points in the driving of the OpheHa Tunnel 
 in the Cripple Creek district, Col. 
 
 Aims, Walter L, "Methods Employed in Driving Alpine Tun- 
 nels, The Loetschberg," Eng. News, p. 746, Dec. 31, 1908, 
 and also Comp. Air Mag., p. 5163, Feb., 1909. Description 
 of methods and equipment. 
 
 Anon., "Harvesting Tunnel, Norwegian State Railways," Proc 
 Inst. Civ. Engrs., Vol. CLXXVI, p. 353, 1909. Short de- 
 scription giving length, cost, time required to drive, etc. 
 
 BoNNiN, R., "The Loetschberg Tunnel," Proc Inst. Civ. Engrs., 
 
BIBLIOGRAPHY 365 
 
 Vol. CLXXVII, p. 310, 1909. Short description giving 
 methods of driving and difficulties encountered in the work. 
 Describes the inrush of peaty material which swamped the 
 working and drowned twenty-five men. 
 
 Young, Henry A., ''Methods of Tunnel Work and Cost Data 
 on an Irrigation Project," Eng. News, p. 128, Feb. 4, 1909. 
 Concerning three small tunnels in Montana. 
 
 Anon., ''The Roosevelt Tunnel," Min. and Min., p. 387, Apr., 
 1909, 9^ cols., 6 illus. Describes some of the difficulties 
 encountered in this work and the methods employed to 
 meet them. 
 
 Chadwick, L. R., "Driving the Mauch Chunk Tunnel," Mine 
 and Quarry, p. 304, June, 1909, 3 pages, illus. Describes some 
 of the methods used in driving this tunnel. 
 
 Anon., "Progress of the Northwest Water Tunnel in Chicago," 
 Eng. Rec, p. 144, Aug. 7, 1909. Description of the tunnel 
 and the methods used in driving it. 
 
 McCoNNELL, I. W., "The Gunnison Tunnel of the Uncompaghre 
 Valley Project, U. S. R. S.," Eng. Rec, p. 228, Aug. 28, 1909, 
 15 cols., illus. Describes the methods and equipment em- 
 ployed in the construction of this tunnel. 
 
 DiNSMORE, W. P. J., "The Gunnison Tunnel," Mine and Quarry, 
 p. 315, Sept., 1909, 6 pages, illus. Describes the work of 
 enlarging the heading to full size, and some of the difficulties 
 encountered during the progress of the tunnel. 
 
 Heinly, B. a., "The Longest Aqueduct in the World," Outlook, 
 Vol. XCIII, pp. 215-220, Sept. 25, 1909. Good non- 
 technical account of the Los Angeles aqueduct. 
 
 Bagg, Rufus M., Jr., "Roosevelt Deep Drainage Tunnel, Col.," 
 E. M. J., p. 1061, Nov. 27, 1909, 2 pages, illus. 
 
 Bain, H. F., "Tunnel Driving in Colorado," Min. Sci. 
 Press, Dec. 4, 1909, pp. 733-47. Describes the methods 
 used in driving the Newhouse, Roosevelt, and Gunnison 
 tunnels. 
 
 Anon., "Proposed Delivery System of the Catskill Water Sup- 
 ply," Eng. Rec, Dec. 11, 1909, 1,500 words. Plan, profile, 
 and description of the system. 
 
366 MODERN TUNNELING 
 
 McCoNNELL, I. W., "Gunnison Tunnel, Uncompahgre Valley 
 Irrigation System," Proc. Inst. Civ. Engrs., Vol. CLXXIX, 
 p. 381, 1910. A short description of the Gunnison tunnel, 
 giving length, size, etc. 
 
 Bagg, Rufus M., "Tunnel Driving in Colorado," Proc. InsL 
 Civ. Engrs., Vol. CLXXX, p. 362, 1910. Description of the 
 method of driving the Roosevelt deep drainage tunnel at 
 Cripple Creek. 
 
 Jacobs, Chas. M., "The Hudson River Tunnels on the Hudson 
 and Manhattan Railway, Proc. Inst. Civ. Engrs., Vol. 
 CLXXXI, p. 169, 1910. A very complete and compre- 
 hensive description of these tunnels, followed by a discus- 
 sion by the members, covering d>^ pages. 
 
 Anon., "The New Buffalo Water Works Tunnel," Proc. Inst. Civ. 
 Engrs., Vol. CLXXXH, p. 340, 1910. Short description of 
 the concrete-lined tunnel, 10,845 ^^^^ ^^^Zi under Lake Erie. 
 
 WiGGiN, Thos. H., "The Design of Pressure Tunnels of the 
 Catskill Aqueduct," Eng. Rec, Jan. 29, 1910. Describing 
 deep concrete-hned tunnels which are to be subjected to 
 hydrostatic pressure. 
 
 Anon., "Walkill Pressure Timnel," Eng. Rec, p. 45c, Apr. 2, 
 1910. Describes the preliminary investigations and the 
 equipment installed for this work. 
 
 Anon., "The Hunters Brook Tunnel Construction," Eng. Rec, 
 p. 454, Apr. 2, 1 9 10. Describes the equipment and methods 
 employed in this work. 
 
 Anon., "Tunnels in Being and Tunnels to Come," Sci. Amer., 
 Apr. 23, 1910, 1,200 words. Discusses length, elevation, 
 cost, etc., of famous mountain tunnels. 
 
 Hancock, H. S., Jr., "Method and Cost of Constructing a 
 Water-Supply Tunnel Through Rock by Day Labor, and 
 Costs of Supplementary Structures," Engng. Contng., May 
 25, 1910, 6/i pages, illus. Discusses the choice of power 
 and describes the equipment and methods used in driving 
 a water-supply tunnel for Fort Williams, Ont. 
 
 Anon., "Report on the Proposed Board of Water-Supply Pressure 
 Tunnel beneath New York City," Eng. News, p. 655, June 2, 
 
BIBLIOGRAPHY 367 
 
 1 910, 4,000 words. Brief historical account of the project, 
 with presentation of estimates and discussion of this and 
 other distribution plans. 
 
 Lavis, F., ''The New Buffalo Water Works Tunnel," Eng. Rec, 
 p. 802, June 25, 1910. Description of methods of driving 
 and lining a hard-rock tunnel under compressed air. 
 
 Anon., "Laramie-Poudre Tunnel," Eng. Rec, p. ii, July 2, 1910, 
 3 cols., illus. Description of work on Laramie tunnel. 
 
 Herrick, R. L., ''Tunneling on the Los Angeles Aqueduct," 
 Min. and Min.j p. no, Oct., 1910, approx. 8 pages. Re- 
 printed in Leyner Bull., 1026. Describes the methods used 
 and gives figures showing the cost of the work. 
 
 Dodge, S. D., and Wm. B. Hake, "The Hudson River Siphon 
 Crossing of the Catskill Aqueduct," Eng. Rec, p. 414, Oct. 
 8, 1910, and p. 435, Oct. 15, 1910. Abstract given before 
 mining engineers. New York, describing preHminary investi- 
 gations and sinking of shafts. 
 
 HuLSART, C. Raymond, "Excavation of the Walkill Pressure 
 Tunnel," Eng. News, ^. /^o6, Oct. 20, 1910, 15 cols., 10 illus. 
 Describes the methods and equipment used in driving this 
 tunnel. 
 
 Anon., "Driving Spiral Tunnels on the Can. Pac. Ry.," Eng. 
 News, p. 512, Nov. 10, 1 9 10, and also Comp. Air Mag.,. 
 p. 5931, Feb., 1911, 6% cols., 5 illus. Illustrated descrip- 
 tion of this work. 
 
 Palmer, Leroy A., "Utah Metals Company Tunnel," Mines and 
 Minerals, p. 296, Dec, 1910, 3 cols., illus. Description of 
 methods and equipment for driving tunnel which is intended 
 for transportation of ores from Bingham to smelter at Tooele. 
 
 G. H. S., "Tunnels of Switzerland," Proc Inst. Civ. Engrs., Vol. 
 CLXXXIV, p. 369, 191 1. List of the 415 tunnels in Swit- 
 zerland, giving their length and elevation. 
 
 WiLGUS, Wm. John, "The Detroit River Tunnel," Proc Inst. 
 Civ. Engrs., Vol. CLXXXV, p. 2, 191 1. Comprehensive and 
 complete description of the Detroit River tunnel, followed by 
 a discussion of this paper by the members present. 
 
 Coy, B. G., "The Laramie-Poudre Tunnel," Eng. Rec, Jan. 14^ 
 
368 MODERN TUNNELING 
 
 191 1. Reprinted in Leyner Bulletin 1029. Description of 
 methods used in driving this tunnel. 
 
 Lytel, J. L., ''The Strawberry Tunnel, U. S. R. S./' Eng, Rec, 
 p. 433, Apr. 22, 1911, 8 cols., illus. Describes methods, 
 equipment, and cost of driving this tunnel. 
 
 Doll, M. G., "Strawberry Valley Tunnel of the Strawberry Val- 
 ley Irrigation Project of Utah," Mine and Quarry, p. 483, 
 May, 191 1, II pages, illus. Describes the methods and 
 equipment and gives some figures showing the cost of this 
 work. 
 
 Anon., "Joining the Headings of the Loetschberg Tunnel," Eng. 
 Rec, p. 491, May 6, 191 1. Contains a brief discussion of 
 the methods used in driving this tunnel. 
 
 Flynn, Alfred D., "Rondout Pressure Tunnel of the Catskill 
 Aqueduct," Eng. News, p. 654, June i, 191 1, 7 pages, pro- 
 fusely illustrated. Describes the tunnel chiefly from the 
 point of view of design. 
 
 Zalinski, Ed. R., "Driving the Strawberry Tunnel," E. M. J., 
 p. 1 1 53, June 10, 191 1, 2 pages, illus. A description of the 
 equipment and routine adopted by the U. S. R. S. in driving 
 a four-mile concrete-lined tunnel for irrigation water for 
 Utah Valley. 
 
 Hardesty, W. p., "CorneHus Gap Tunnel, United Rys. Co., 
 near Portland, Oregon," Eng. News, p. 783, June 29, 191 1, 
 2 cols, illus. Brief description of the methods and equipment. 
 
 Saunders, W. L., "Tunnel Driving in the Alps," Bull. Am. Inst. 
 Min. Engrs., No. 55, p. 507, July, 191 1, 32 pages, illus. 
 Describes and discusses the methods and equipment em- 
 ployed in driving the Simplon and the Loetschberg Tunnels. 
 
 Anon., "Newton Pressure Tunnel of the Metropolitan Water 
 Works, Boston," Eng. Rec, Oct. 28, 1911. Description of 
 a concrete-lined water-way in rock, with short section of 
 80-inch, mortar-lined and concrete-covered steel pipe at 
 each end. 
 
 Anon., "Work in the Snake Creek Tunnel," Min. Sci. Press, 
 p. 108, Jan. 13, 191 2. A brief description of some of the 
 methods used in this work. 
 
BIBLIOGRAPHY 369 
 
 Anon., "Notes in Driving the Elizabeth Lake Tunnel/' Eng. Rec.y 
 p. 72, Jan. 20, 191 2, 2 cols. An abstract from the annual 
 report of the chief engineer of Los Angeles aqueduct for the 
 year ending June 30, 1911, describing several interesting 
 features of the work. 
 
 Anon., "A Tunnel Street," Municipal Journal, p. 199, Feb. 8, 
 191 2, 4 cols., illus. Proposed tunnel in upper part of New 
 York City to provide access to subway. Concrete lining. 
 Provision for removing seepage water. White cement finish. 
 Electric hghting. Unit contract prices. 
 
 Coy, Burgis G., ''The Laramie-Poudre Tunnel," Proceedings oj 
 Amer. Soc. of Civ. Engrs., p. 217, March, 1912, 14 pages, 13 
 illus. Description of the equipment and methods of driving. 
 
 Brunton, D. W., ''Notes on the Laramie Tunnel," Bui. No. 64, 
 Amer. Inst. Min. Engrs., p. 357, Apr., 191 2, and also abstract 
 in Engng. and Min. Wld., p. 959, May 4, 191 2. Describes 
 the equipment and methods used at this tunnel. 
 
 Gavin, W. H., "Arthur's Pass Tunnel," Eng. News, p. 870, 
 May 9, 191 2. A description of a five-mile railway timnel in 
 New Zealand. 
 
 Russell, Will C, "Driving a Long Adit at Bonanza, Col.," 
 Eng. and Min. Jour., p. 272, Feb. i, 1913. An adit, 7 x 8 ft. 
 in the clear, was driven 6,235 feet, for drainage, exploration, 
 and working, at a cost of $19.87 per foot. Two machines 
 on cross-bars were used. The adit was completed in seven- 
 teen months and two days. 
 
 WATER-POWER 
 
 Gray, J. W., "Useful Hydraulic Data," Min. Sci. Press, Vol. 
 LXXVI, p. 179, 1897, 4K cols. Abstract of a paper in New 
 Zealand Mines report by Alex. Aitken, Mgr. Govt. Water, 
 Kumara, New Zealand. Power of water. Friction in pipes 
 and channels, carrying capacity of pipes and channels, 
 capacity of sluices. 
 
 WooDBRiDGE, D. E., "The HydrauHc Compressed Air Power 
 Plant at the Victoria Mine (Mich.)," £. If./., p. 125, Jan. 19, 
 
370 MODERN TUNNELING 
 
 1907. An illustrated article describing an installation of 
 the Taylor system. The tested efficiency of this plant is 
 given as 82 per cent. 
 
 Edit., ''The Utilization of Small Water Powers," Editorial, Eng, 
 Rec, p. 247, Sept. 7, 1907. Discusses the development of 
 comparatively small streams. 
 
 Anon., ''Efficiency of Hydraulic Air Compression," E. M. J., 
 p. 228, Aug. I, 1908, 3 cols., illus. Abstract of article in 
 Gluckauf for March 14, 1908, by O. Bernstein. Contains a 
 description of a hydraulic compressor installed in one of 
 the mines at Clausthal, together with tests of its efficiency. 
 
 Stewart, Sylvester, "Water Power from Streams of Moderate 
 Fall," Cassier^s Mag., p. 470, Sept., 1909, 9 cols., 8 illus. Dis- 
 cusses the possibilities for power development with low 
 dams. 
 
 McFarlane, Geo. C, "Compressing Air by Water," Min. Sci. 
 Press, p. 281, Feb. 19, 1 910, 2 cols., illus. Discusses ways of 
 using water-power which is so often available in mining 
 districts for the compression of air, and describes several 
 devices for doing this. 
 
 Koester, Frank, "A General Review of the Hydro-electric 
 Engineering Practice," Engr. Mag,, 5 articles: Introduc- 
 tion, Dams, p. 24, April, 19 10; Head Races, Pressure Pipes^ 
 Penstocks, p. 176, May, 19 10; Turbines and Mechanical 
 Equipment of Power Plant, p. 340, June, 19 10; Electrical 
 Equipment, p. 494, July, 19 10; High Tension Transmission, 
 p. 659, Aug., 1910. 
 
 Anon., "Taylor Hydraulic Air Compressor (Cobalt)," Comp. Air 
 Mag., p. 5675, June, 1910, (i% cols. Description taken from 
 an article in Mines and Minerals, by C. H. Taylor. 
 
 Gray, Alex., "Power Plants of the Cobalt District, Ontario," 
 The Min. World, p. 131, July 23, 1910, ii/^ cols., 10 illus. 
 
 Coy, B. G., "The Laramie-Poudre Tunnel," Eng. Rec, Jan. 14, 
 1911,4 cols., illus. Contains a description of the water-power 
 plant used in driving this tunnel. 
 
 VON ScHON, H., "The Most Resourceful Utilization of Water 
 Power," Eng. Mag., p. 69, April, 191 1, 21 cols., 5 illus. 
 
BIBLIOGR.APHY 371 
 
 Bateman, G. C, 'Xobalt Hydraulic Company," E. M. J., p. 998, 
 Nov. 18, 191 1, 1,000 words. Description of a Taylor 
 compressor in which the air is drawn into a falling column 
 of water. Compressed air is sold at 25 cents per 1,000 cu. ft. 
 at 120 lbs. pressure. 
 
 Coy, B. G., ''The Laramie-Poudre Tunnel," Proc. Am. Soc. Civ. 
 Engrs., p. 217, March, 191 2. Contains a description of the 
 water-power plant at this tunnel. 
 
 Smith, Cecil B., "Power Plants for Mines in the Cobalt Dis- 
 trict," Min. and Eng. World, p. 503, March 2, 191 2, 3^^ cols., 
 2 illus. Description of water-power plants furnishing power 
 to the Cobalt camp. 
 
 Brunton, D. W., "Notes on the Laramie-Poudre Tunnel," 
 Trans. Am. Inst. Min. Engrs., p. 357, April, 191 2, also 
 abstract in Min. and Engng. World, p. 959, May 5, 191 2. 
 Contains a description of the water-power plant at this 
 tunnel. 
 
 STEAM POWER ' 
 
 Webber, Wm. 0., "Comparative Costs of Gasoline, Gas, Steam, 
 and Electricity for Small Powers," Eng. News, p. 159, Aug. 
 15, 1907, 2>^ cols., tables. Gives itemized cost tables for 
 2, 6, 10, and 20 horse-power plants. 
 
 Anon., "The Second Raton Hill Tunnel of the Atchison, Topeka 
 and Santa Fe Ry.," Eng. Rec, p. 461, April 4, 1908. Con- 
 tains a description of the steam-power plant for this tunnel. 
 
 Anon., "Steam vs. Compressed Air in Mining (Coal)," Comp. Air 
 Mag., p. 5174, Feb., 1909, i col. Compressed air is much 
 better than steam for pumping, coal cutting, etc., in mines. 
 
 Anon., "The Compressed Air Plant for the Rondout Siphon," 
 Eng. Rec, p. 490, April 10, 1909, 4^ cols., illus., also Comp. 
 Air Mag. (reprint), p. 5291, June, 1909, 7 cols., illus. 
 
 Anon.,"Compressed Air in Construction Work," Eng. Rec, p. 179, 
 Aug. 14, 1909, 4 cols. Discusses the advantages of com- 
 pressed air over steam for the operation of drills, pumps, 
 etc., in construction work. 
 
 McCoNNELL, I. W., "The Gunnison Tunnel of the Uncompaghre 
 
372 MODERN TUNNELING 
 
 Valley Project, U. S. R. S.," Eng. Rec.^ p. 228, Aug. 28, 1909, 
 15 cols., illus. Contains a description of the steam-power 
 plants used in this work. 
 
 Chance, T. M., ''Costs of a Gas Engine and of a Combined 
 Steam Plant," Eng. Rec, p. 273, Sept. 4, 1909, 7 cols., 4 illus. 
 Power economy of gas engine is greater than steam, but its 
 first cost and difficulty of operation are also greater. A 
 corresponding plant using low-pressure turbines and high- 
 economy CorKss engines solves the problem in many places. 
 
 Anon., "Cost of Power for Various Industries," Eng. Rec, p. 711, 
 Dec. 25, 1909. Review of paper before the Boston Society 
 of Civil Engineers, by Chas. T. Main. Concerns steam 
 power for textile mills, under varying conditions, assuming 
 that it is ultimately converted into electricity. 
 
 Webb, Rich. L., "Cost of Producing Compressed Air at a Cana- 
 dian Mining Camp," Can. Min. Jour., p. 102, Feb. 15, 1910, 
 20 cols., 10 tables. Results of tests on two steam-driven air 
 compressors. 
 
 Haight, H. v., "Steam Driven Air Compressors in Cobalt," 
 Can. Min. Jour., p. 209, April i, 1910, 3^ cols. Discussion 
 of the paper by Rich. L. Webb, Can. Min. Jour., Feb. 15, 
 1910, p. 102. 
 
 Anon., "The Hunters Brook Tunnel Construction," Eng. Rec, 
 p. 454, April 2, 1910. Contains a description of the steam- 
 power plant for this tunnel. 
 
 Anon., "Cost of Power Production in Small Steam Plants," Eng. 
 Rec, p. 570, April 30, 1910. Discusses the cost of steam- 
 electric power in small stations. 
 
 Anon., "The Moodna Pressure Tunnel of the Catskill Aqueduct 
 (Power Plant)," Eng. Rec, p. 731, June 4, 19 10. Descrip- 
 tion of the two power plants used to furnish the compressed 
 air used in driving this tunnel. 
 
 Anon., "Driving Spiral Tunnels on the Can. Pac. Ry.," Eng, 
 News, p. 512, Nov. 10, 1 9 10, 6 cols., 5 illus. Contains a de- 
 scription of the steam-power plant for this work. 
 
 Anon., "Exhaust Steam Turbines at Mines," Min. and Min., 
 p. 371, Jan., 1912, 5 pages, illus. Abstract of a paper before 
 
BIBLIOGRAPHY 373 
 
 Australasian Inst. Min. Engrs., June, 191 1. Describes use 
 of turbine engines to utilize exhaust steam from various 
 engines of a mine plant. 
 CiARK, S. M., ''The Fuel Cost of Making Steam," The Isolated 
 Plant, p. 129, April, 191 2, 12 cols., 3 illus. Discusses the 
 means of judging and comparing coal. 
 
 INTERNAL-COMBUSTION POWER 
 
 Webber, Wm. 0., ''Comparative Costs of Gasoline, Gas, Steam, 
 and Electricity for Small Powers," Eng. News, p. 159, Aug. 
 15, 1907, 2}4 cols., tables. Gives itemized cost tables for 2, 
 6, 10, and 20 horse-power plants. 
 
 Thwaite, B. H., "The Blast Furnace as a Center of Power Pro- 
 duction," Cassier's Mag., p. 23, Nov., 1903, 36 cols., 15 illus. 
 
 Adams, E. T., "The Development of the Large Gas Engine in 
 America," Cassier^s Mag., p. 41, Nov., 1907, 22 cols., 15 illus. 
 Development of gas engine supplied with gas from blast 
 furnace. 
 
 Humphrey, H. A., "By-product Recovery Gas-producer Plants," 
 Gassier^ s Mag., p. 55, Nov., 1907, 17 cols., 11 illus. Mr. 
 Humphrey treats of the recovery of such a valuable com- 
 mercial article as sulphate of ammonia from the waste of 
 the gas-producer, showing the success which has been 
 attained by Dr. Ludwig Mond and his associates. 
 
 BiBBiNS, J. R., "Recent AppHcations of Gas Power," Gassier^ s 
 Mag., p. 147, Nov., 1907, 13 cols., 9 illus. Discusses the 
 recent installations of producer-gas plants in this country, 
 showing the amount of power so used and the sizes of the 
 plants. 
 
 Rowan, F. J., "The Suction Gas Producers," Gassier^ s Mag., 
 p. 174, Nov., 1907, 48^^ cols., 24 iUus. 
 
 Harvey, Elbert A., "Power Gas from Bituminous Coal," Gas- 
 sier^s Mag., p. 199, Nov., 1907, 14 cols., 8 illus. States that 
 the bituminous gas-producer is no longer an experiment, 
 and describes several such producers which will give satis- 
 factory service. 
 
 RoBSON, Philip W., "Power Gas-producers, their Design and 
 
374 MODERN TUNNELING 
 
 Application," published by Edward Arnold, London, Eng., 
 1908, 247 pages, 105 illus. 
 
 Fernald R. H., ''Producer-gas Power Plant in the United 
 States," Cassier^s Mag., p. 582, Feb., 1908, 13 cols. 
 
 Anon., "Test of a Small Gas-producer Plant," Eng. Rec, p. 375, 
 March 28, 1908, 2^ cols. Describes the 15 horse-power 
 plant of the Weber Wagon Works, Chicago, and gives the 
 results of tests. 
 
 Barbezat, Alfred, "Recent Developments in the Gas Turbine," 
 Gassier^ s Mag., p. 617, April, 1908, 6 cols., 3 illus. 
 
 Anon., "The Loomis-Pettibone Gas-generating System," Gas- 
 sier^ s Mag., p. 685, April, 1908, 2 cols. A discussion of the 
 principles underlying this system for use with bituminous coal. 
 
 Anon., "A Producer-gas Power Plant," Eng. Rec, p. 478, April 4, 
 1908. A brief reference to a test of a 600 horse-power pro- 
 ducer-gas plant at the works of David Rowan & Co., at 
 Glasgow. 
 
 Lewis, W. Y., "The Carbon Monoxide Gas-producer," Gassier' s 
 Mag., p. 223, July, 1908, i8J^ cols. Discusses the advan- 
 tages of a straight carbon monoxide gas-producer as devel- 
 oped at the Phoenix Tube Mill plant in Long Island City. 
 
 Anon., "The Suction Gas-producer Plant at the Shops of Fair- 
 banks, Morse & Co.," Eng. Rec, Sept. 5, 1908. Description 
 of this plant, giving also results of tests. 
 
 White, T. L., "The Rehabihty of the Gas-producer Plant," 
 Gassier' s Mag., Oct., 1908, 5^ pages. Describes a test made 
 upon a small gas-producer plant, and discusses gas plants 
 from a point of view of reliability as compared with other 
 plants. 
 
 Burt, T. W., "The Suction Gas-producer," Gassier' s Mag., 
 p. 124, June, 1909, II pages. Description of the theory and 
 design of the suction gas-producer with drawings of four 
 important types. 
 
 Anon., "Test of a Double Zone Bituminous Gas-producer," Eng. 
 News,^. 13, July i, 1909, 7 cols., 4 illus. Results of experi- 
 mental work at the plant of the Westinghouse Machine Co., 
 at East Pittsburgh. 
 
BIBLIOGRAPHY 375 
 
 Atkinson, A. S., "Gas Engines for Mining Purposes," Min. 
 Set. Press, p. 300, Aug. 28, 1909, 3X cols. Discusses the 
 advantages of gas engines for mining power plants, showing 
 some of their advantages over steam and electricity. 
 
 Chance, T. M., 'Xosts of a Steam Engine and of a Combined 
 Steam Plant," Eng. Rec, p. 273, Sept. 4, 1909, 7 cols., 4 illus. 
 Power economy of gas engine is greater than steam, but its 
 first cost and difficulty of operation are also greater. A cor- 
 responding plant using low-pressure turbines and high- 
 economy Corliss engines solves the problem in many places. 
 
 Gradenwitz, Dr. Alfred, "A New Gas-producer for Low 
 Grade Fuel," Power and the Engineer, p. 653, Oct. 19, 1909, 
 3^^ cols., 3 illus. Discusses a gas-producer designed to oper- 
 ate upon anthracite, coke, and smoke-chamber dust and 
 other rubbish, giving figures showing the consumption of 
 these materials per horse-power hour. 
 
 SuPLEE, Henry H., ''The Explosion Gas Turbine," Gassier' s 
 Mag., p. 79, Nov., 1909, 6 cols., 2 illus. Describes an experi- 
 mental explosion gas turbine of 2 horse-power as developed 
 by M. Karavodine in Paris. 
 
 Anon., ''Tests of a Suction Gas-producer," Univ. of 111. Bull. 50, 
 90 pages, illus. and tables. Reviews theory of gas-producer, 
 explaining object of tests, methods of experimenting, giving 
 results and conclusions. 
 
 Fernald, R. H., "Features of Producer-gas Power-plant Devel- 
 opment in Europe," (U. S.) Bureau of Mines Bulletin 4, 1910, 
 27 pages, 4 plates, 7 figs. Briefly summarizes some features 
 of gas-producer practice with particular reference to the use 
 of low-grade fuels. 
 
 Miller, J. C, "Power Gas and Gas-producer," published by 
 Popular Mechanics Co., Chicago, 111., 1910, 184 pages. 
 
 Clement, J. K., L. H. Adams, and C. N. Haskins, "Essential 
 Factors in the Formation of Producer-gas," (U. S.) Bureau 
 of Mines, Bulletin y, 191 1, 58 pages, i plate, 16 figs. De- 
 scribes laboratory experiments bearing on the rate of forma- 
 tion of carbon monoxide at high temperatures and the 
 effect of temperature on the rate of formation and the 
 
376 MODERN TUNNELING 
 
 composition of water gas. Indicates how the results of the 
 tests apply to the operation of boiler furnaces and gas- 
 producers. 
 
 Fernald, R. H., and C. D. Smith, '^ Resume of Producer-gas 
 Investigations," Oct. i, 1904, to June 30, 1910, (U. S.) 
 Bureau of Mines, Bulletin ij, 191 1, 393 pages, 12 plates, 250 
 figs. Summarizes the results of producer-gas investigations 
 at the Government fuel- testing plants. Incidentally dis- 
 cusses gas-producer development in this country and in 
 Europe. Is intended especially for mechanical engineers 
 and power-plant officials interested in gas-producer design 
 and in the operation of gas-producers on the coals available 
 at different points in the United States. 
 
 Davis, C. A., ''The Uses of Peat for Fuel and Other Purposes," 
 (U. S.) Bureau of Mines, Bulletin 16, 191 1, 214 pages, i plate, 
 I fig. Summarizes recent developments in the utilization 
 of peat. Treats of the origin and formation of peat, its fuel 
 value, and the manufacture of peat fuel. Also summarizes 
 progress in utilizing peat for other purposes. 
 
 Smith, C. D., J. K. Clement, and H. A. Grine, "Incidental 
 Problems in Gas-producer Tests," (U. S.) Bureau of Mines, 
 Bulletin ji, 29 pages, 8 figs. Considers the factors affecting 
 the proper length of gas-producer tests and the differences 
 in temperatures at different points in the fuel bed. Reprint 
 of the (U. S.) Geol. Survey Bulletin jgj. 
 
 Strong, R. M., ''Commercial Deductions from Comparisons of 
 GasoHne and Alcohol Tests of Internal-combustion Engines," 
 (U. S.) Bureau of Mines, Bulletin j2, 38 pages. Summarizes 
 deductions based on 2,000 tests of gasoKne and alcohol. 
 Reprint of (U. S.) Geol. Survey Bulletin jg2. 
 
 WiTZ, A., "The Use of Gas Engines in Central Stations (L'Em- 
 ploi des moteurs a gaz dans les stations centrales d'electri- 
 cite)," Genie Civil, No. 28,861 D.,Nov. 11, 191 1, 5,600 words. 
 Discussion of the feasibiHty of the use of gas, and results 
 of some of the tests made. 
 
 Meriam, J. B., "The Relative Economy of Gas Engines and 
 Other Sources of Power," Jour. Cleveland Engng. Soc., p. 121, 
 
BIBLIOGRAPHY 377 
 
 Dec, 191 1, 2,200 words, illus. Discusses the advantages and 
 disadvantages of oil and gas engines in plants of moderate 
 size and gives examples of recent installations. 
 
 Anon., ''New Bituminous Gas-producer," Iron Age, Dec. 14, 
 1911, 1,200 words, illus. Illustrates and describes the Nor- 
 densson furnace gas-producer. 
 
 Weil, J. A., ''Producer-gas," Mech. Engr.,p. 755, Dec. 15, 1911, 
 3,000 words. Discusses the proper design of plant. 
 
 Strong, R. M., and Lauson Stone, "Comparative Fuel Values 
 of GasoKne and Denatured Alcohol in Internal- Combustion 
 Engines," (U. S.) Bureau of Mines, Bulletin 4j, 191 2, 243 
 pages, 3 plates, 32 figs. A detailed statement of the results 
 of 2,000 tests made to determine the comparative value of 
 the two fuels for use in internal-combustion engines. Is a 
 technical report, written for mechanical engineers and per- 
 sons interested in the utiHzation of liquid fuels. 
 
 Fernald, R. H., "The Status of the Gas-producer and the 
 Internal-combustion Engine in the UtiKzation of Fuels," 
 (U. S.) Bureau of Mines, Technical Paper g, 191 2, 42 pages, 
 6 figs. Relates the progress in the appHcation of the gas- 
 producer to commercial uses, and in the development of 
 gas power. 
 
 Anon., "An English Wood Refuse Suction Gas-producer," Sci, 
 Amer., p. 3, Supplement No. 1879, Jan. 6, 191 2, i col. 
 Describes the machine and discusses its advantages. 
 
 Anon., "Temporary Power Plant for the Woolwich Footway 
 Tunnel," Engineer (London), p. 46, Jan. 12, 191 2, 2 pages, 
 illus. Description of a plant using suction gas-producers as 
 a source of motive power to operate the air-compressors for 
 a tunnel under the Thames driven under compressed 
 air. 
 
 Anon., "The Gas Power Field for 191 1, a Review of the 
 Past Year," Sci. Amer., p. 58, Supplement No. 1,882, Jan. 
 27, 191 2, 6 cols. Paper read before the Gas Power Section 
 of the American Association of Mechanical Engineers. 
 
 Anon., "The Bituminous Gas Engine in South Africa," The En- 
 gineer, p. 258, March 8, 191 2, 4 cols., 3 photos. Describes 
 
378 MODERN TUNNELING 
 
 the producer and gives results of its use at the Groenfontein 
 tin mines in the Transvaal. 
 
 Percy, Paul C./' Combination Power and Ice Plant," Power, 
 p. 418, March 26, 191 2, 8 illus. Describes a plant using 
 wood-refuse gas-producers as prime movers and gives results 
 of tests. 
 
 Anon., '' What is the Diesel Engine? " Eng. News, pp. 654-6, 
 April 4, 191 2, 6^4 cols. An excellent recitation in non- 
 technical language of the principles upon which this machine 
 operates. 
 
 Chorlton, Alan E. L., " Gas Engines for Collieries," Coal 
 Age, pp. 876-9, April 13, 191 2, 5 illus. Gas engines are 
 being largely used at British colHeries for the generation 
 of power. The gas is generated either in producers or in 
 coke ovens. Producers can be sometimes made to yield 
 such products from by-products, where the fuel is of low 
 grade, that even without using the gas produced, the in- 
 stallation will justify its erection. (Paper read before Mid- 
 land Institute of Mining, Civil, and Mechanical Engineers.) 
 
 Diesel, Rudolph, '' The Present Status of the Diesel Engine 
 in Europe," Jour. Am. Soc. Mech. Engrs., June, 191 2, 40 
 pages, 50 illus. 
 
 Garland, C. M., '' Bituminous Coal Producers for Vower,^^ J our. 
 Am. Soc. Mech. Engrs., p. 833, June, 1912, 20 pages, 2 
 illus. Describes the apparatus and general arrangement 
 of bituminous-coal producers as designed for power. Dis- 
 cusses also the efhciency of the plant, composition of the 
 gas, and operating costs. 
 
 ELECTRIC POWER 
 
 ScHAEFER, E. F., '' Compressed Air vs. Electricity," Min. and 
 Min., p. 425, April, 1906, 2% cols. Discusses the advantages 
 of compressed air over electricity for mining purposes. 
 
 Webber, Wm. O., '' Comparative Costs of Gasoline, Gas, Steam, 
 and Electricity for Small Powers," Eng. News, p. 159, Aug. 
 15, 1907, 2^ cols., tables. Gives itemized cost tables 
 for 2, 6, 10, and 20 horse-power plants. 
 
BIBLIOGRAPHY 379 
 
 Kerr, E. W., '' Power and Power Transmission," 1908, 366 
 pages. Published by John Wiley & Sons, New York City. 
 
 , " Electric Power Costs in Small Station," Eng. Rec.^ p. 
 
 30, Jan. 9, 1909, i^ cols. Discusses the power costs 
 at several small towns near Boston, Mass. 
 
 Spellmire, W. p., " The Use of Electricity as Applied to Coal 
 Mining," E. M. /., p. 507, March 6, 1909. Discusses the 
 advantages of electricity as a source of power for coal- 
 mining plants. 
 
 Anon., " Cost of Power for Various Industries," Eng. Rec, p. 711, 
 Dec. 25, 1909. Review of paper before the Boston Society 
 of Civil Engineers, by Chas. T. Main. Concerns steam 
 power for textile mills under varying conditions, assuming 
 that it was ultimately converted into electricity. 
 
 KoESTER, Frank, '' A General Review of the Hydro-electric 
 Engineering Practice," Engr. Mag., 5 articles: Introduction, 
 Dams, p. 24, April, 1910; Head Races, Pressure Pipes, 
 Penstocks, p. 176, May, 1910; Turbines and Mechanical 
 Equipment of Power Plant, p. 340, June, 1910; Electrical 
 Equipment, p. 494, July, 1910; and High Tension Trans- 
 mission, p. 659, Aug., 1910. 
 
 Anon., '' Cost of Power Production in Small Steam Plants," £w^. 
 Rec, p. 570, April 30, 1910. Discusses the cost of steani- 
 electric power in small stations. 
 
 Anon., '' Cost of Power Transmission, Electricity vs. Compressed 
 Air," Min. Sci. Press, p. 700, May 14, 1910, yi col. Esti- 
 mates prepared by the Pneumelectric Machine Co., for 
 the cost of delivering 200 horse-power one mile by com- 
 pressed air and electricity (direct current, 250 volts). 
 
 Anon., " Methods and Costs of Constructing a Water Supply 
 Tunnel," Engng. Contng., p. 472, May 25, 1910, 6 cols., 6 
 illus. Describes the electrically driven power plant for 
 this work near Ft. WilHams, Ont. 
 
 Anon., " Electricity in the Construction of the Los Angeles 
 Aqueduct," Eng. Rec, July 16, 1910, 6 cols., illus. De- 
 scribes central generating station and cost of trans- 
 mission line. 
 
380 MODERN TUNNELING 
 
 HuLSART, C. R., '' Excavation of the Wallkill Pressure Tunnel, 
 Catskill Aqueduct/' Eng. News, p. 406, Oct. 20, 1910, 15 
 cols., 10 illus. Contains a description of the electrically 
 driven power plant for this work. 
 
 Yerbury, H. E., '' Electricity as AppHed to Modern Tunnel 
 Work," Proc. Inst. Civ. Engrs., Vol. CLXXXIII, p. 296, 
 191 1, 8 pages. Discusses the application of electricity to 
 tunnehng work; giving description of power station, tunnel 
 equipment, tunnel driving, etc. 
 
 Edit., " High Tension Line Problems," Editorial Eng. Rec, p. 
 289, March 18, 191 1. Discusses some of the difficulties 
 connected with high-tension electric hues. 
 
 Knowlton, H. S., '' Developing Electrical Energy from the 
 Los Angeles Aqueduct," Elec. World, p. 301, Feb. 10, 191 2, 
 12 cols., illus. Plans for establishing a large hydro-electric 
 system in connection with the creation of a new water 
 supply. . Electrical energy will be sold as a by-product 
 of a $23,000,000 water system. Maximum delivery 90,000 
 kilowatts into city of Los Angeles. Extensive use of 
 electricity in aqueduct construction. 
 
 COMPRESSED AIR POWER 
 
 ScHAEEER, E. F., ''Compressed Air vs. Electricity," Min. and 
 Min., p. 425, April, 1906, 2% cols. Discusses the advantages 
 of compressed air over electricity for mining purposes. 
 
 Gray, Alex., ''Compressed Air for Mining in Cobalt District," 
 Min. Wld., p. 877, Dec. 12, 1908, 6>^ cols., 2 illus. Factors 
 influencing the supply of air for mines. Marked increase 
 in steam and gas-producer plants in last four years. Cost 
 of compressing air. Taylor hydrauHc air-compressor system. 
 
 Anon., ''Steam vs. Compressed Air in Mining" (Coal), Comp. Air 
 Mag., p. 5174, Feb., 1909, i col. Compressed air is much 
 better than steam for pumping, coal cutting, etc., in mines. 
 
 Anon., ''Compressed Air in Construction Work," Eng. Rec, p. 
 179, Aug. 14, 1909, 4 cols. Discusses the advantages of 
 compressed air over steam for the operation of drills, 
 pumps, etc., in construction work. 
 
BIBLIOGRAPHY 381 
 
 Anon., "Cost of Power Transmission: Electricity vs. Compressed 
 Air," Min. Sci. Press, p. 700, May 14, 1910. Estimates 
 prepared by the Pneumelectric Machine Co. for the cost of 
 delivering 200 horse-power one mile by compressed air and 
 electricity (direct current, 250 V.). 
 
 ViLLETARD, H., "Application of Compressed Air in Tunnels 
 (Applications de Fair comprime a la perforation des grands 
 sou terrains)," Tech. Mod., Nov., 191 1, 2,500 words, illus. 
 With particular reference to large European railway tunnels. 
 
 POWER TRANSMISSION 
 
 LucKE, Charles E., "Power Transmission by Producer-gas," 
 Cassier's Mag., p. 210, Nov., 1907, 6 cols. Discusses 
 the advantages of producer-gas as a means of power 
 transmission. 
 
 Richards, Frank, "Compressed Air Leakage," Comp. Air Mag., 
 p. 4717, Jan., 1908, 2>^ cols. Examples where pipe did 
 not leak. 
 
 Smith, C. A., "Power Transmission," Cassier's Mag., p. 275, 
 July, 1908, loK cols. A comparative study of the merits 
 of gas and electricity. 
 
 Emerson, Harrison Dexter, "Long-Distance Gas Transmis- 
 sion," Cassier^s Mag., p. 275, May, 1910, 2 cols., 4 illus. 
 Facts connected with the long-distance pumping of natural 
 gas through pipe lines from the fields of Pennsylvania and 
 West Virginia. 
 
 Anon., "Cost of Power Transmission: Electricity vs. Compressed 
 Air," if m. Sci. Press, p. 700, May 14, 1910, yi col. Estimates 
 prepared by the Pneumelectric Machine Co., for the cost of 
 delivering 200 horse-power one mile by compressed air and 
 electricity (direct current, 250 volts). 
 
 Edit., "High Tension Line Problems," Eng. Rec, p. 289, 
 March 18, 191 1. Editorial discusses some of the difficulties 
 connected with high-tension electric Hues. 
 
 Richards, Frank, "Draining Compressed Air," Comp. Air Mag., 
 p. 5997, April, 191 1, 4 cols. Abstract of article in Eng, Rec.j 
 Feb. 18, 191 1, p. 203. 
 
382 MODERN TUNNELING 
 
 Edit., ''Freezing up of Compressed Air Lines," Comp. Air Mag., 
 
 p. 6017, April, 191 1, 2 cols. Editorial. 
 MacIntire, H., ''Power from Compressed Air," Power, Nov. 7, 
 
 1911, 1,550 words; also Comp. Air Mag., p. 6259, Dec, 1911. 
 
 Discusses air transmission in pipe lines and developing 
 
 power from an air system. 
 Anon., "Proportion of Air Mains and Branches," E. M. /., 
 
 p. 1027, Nov. 25, 191 1. A table showing diameters 
 
 of branches that can be supplied by mains of certain 
 
 sizes. 
 Anon., "Power from Compressed Air," Amer. Mech., Nov. 30, 
 
 191 1, 1,200 words. Considers the transmission of power by 
 
 an air system; the economy and appHcations. 
 
 CHOICE OF POWER 
 
 Webber, Wm. 0., "Comparative Costs of Gasoline, Gas, Steam, 
 and Electricity for Small Power," Eng. News, p. 159, Aug. 
 15, 1907, 2^ cols., tables. Gives itemized cost tables for 
 2, 6, 10, and 20 horse-power plants. 
 
 Moses, Percival R., "Power Plant Waste," Cassier's Mag., 
 p. 497, Oct., 1909, 16 cols.; p. 12, Nov., 1909, 13 cols.; 
 p. 320, Feb., 1910, 13 cols. A series of articles dealing with 
 waste in power plants and the means of preventing it. 
 
 Anon., "Methods and Costs of Constructing a Water Supply 
 Tunnel through Rock," Engng. Contng., p. 472, May 25, 
 1910, 6 cols., illus. Discusses the choice of motive power for 
 this work near Fort WilHams, Ont., electricity being chosen. 
 
 POWER PLANT DESCRIPTIONS 
 
 Anon., "Preliminary Work on the Los Angeles Aqueduct," Eng. 
 Rec, p. 144, Feb. 8, 1908. Contains a description of the 
 electric power plant for supplying power to the aqueduct 
 work. 
 
 Anon., "Test of a Small Gas-producer Plant," Eng. Rec, p. 375, 
 March 28, 1908, 2>^ cols. Describes test of 15 horse-power 
 plant of the Weber Wagon Works, Chicago, 111. 
 
BIBLIOGRAPHY 383 
 
 Anon., ''The Second Raton Hill Tunnel of the Atchison, Topeka 
 and Santa Fe Railway," Eng. Rec, p. 461, April 4, 1908. 
 Contains a description of the power plant for this tunnel. 
 
 Anon., ''The Suction Gas-producer Plant at the Shops of Fair- 
 banks, Morse & Co.," Eng. Rec, Sept. 5, 1908. Description 
 of this plant, giving also results of tests. 
 
 Anon., "The Compressed Air Plant for the Rondout Siphon," 
 Eng. Rec, p. 490, April 10, 1909, 4K cols., illus., and also in 
 Comp. Air Mag., p. 5391, June, 1909, 7 cols., illus. Descrip- 
 tion of a compressed-air plant of 24,000 cubic feet capacity 
 for the Rondout Siphon tunnel of the Catskill Aqueduct. 
 
 McCoNNELL, I. W., "The Gunnison Tunnel of the Uncom- 
 paghre Valley Project, U. S. R. S.," Eng. Rec, p. 228, Aug. 
 28, 1909, 15 cols., illus. Contains a description of the steam- 
 power plants used in this work. 
 
 Atkinson, A. S., "Gas Engines for Mining Purposes," Min. Sci. 
 Press, p. 300, Aug. 28, 1909. Contains a brief description 
 of the gas-engine power plant for the Powell Duffryn 
 ColHeries in South Wales. 
 
 Moses, Percival R., "Power Plant Waste," Gassier' s Mag., p. 
 497, Oct., 1909, 13 cols. The last of a series of three articles 
 dealing with this subject. In this number several specific 
 examples are given, showing the defects and preventable 
 waste and the remedial methods therefor. 
 
 Anon., "Wallkill Pressure Tunnel," Eng. Rec, p. 450, April 2, 
 1 9 10. Contains a description of the power plant installed 
 for this work. 
 
 Anon., "The Hunters Brook Tunnel Construction," Eng. Rec, 
 p. 454, April 2, 1910. Contains a description of the power 
 plant for this tunnel. 
 
 Anon., "Cost of Power Production in Small Steam Plants," p. 
 570, Eng. Rec, April 30, 19 10. Discusses the cost of steam- 
 electric power in small stations and describes four examples. 
 
 Anon., "Methods and Costs of Constructing a Water Supply 
 TmhhqI,''' Engng. Contng.,p. 472, May 25, 1910, 6 cols., 6 illus. 
 Describes the electrically driven power plant for this work 
 near Fort WilHams, Ont. 
 
384 MODERN TUNNELING 
 
 Anon., "The Moodna Pressure Tunnel of the Catskill Aqueduct 
 (Power Plants)/' Eng. Rec, p. 731, June 4, 1910. Descrip- 
 tion of the two power plants used to furnish the compressed 
 air used in driving this tunnel. 
 
 HuLSART, C. R., ''Excavation of the Wallkill Pressure Tunnel, 
 Catskill Aqueduct," Eng. News, p. 406, Oct. 20, 19 10, 15 
 cols., ID illus. Contains a description of the electrically 
 driven power plant for this work. 
 
 Anon., *' Driving Spiral Tunnels on the Canadian Pacific Rail- 
 way," Eng. News, p. 512, Nov. 10, 1910, 6 cols., 5 illus. 
 Contains a description of the steam-power plant for this 
 work. 
 
 Palmer, Leroy A., ''Utah Metals Company Tunnel," Min. and 
 Min.j p. 296, Dec, 1910. Contains a description of the 
 water-power plant at this tunnel. 
 
 Coy, B. G., "The Laramie-Poudre Tunnel," Eng. Rec, Jan. 14, 
 191 1, 4 cols., illus. Contains a description of the water- 
 power plant used in driving this tunnel. 
 
 Lytel, J. L., "The Strawberry Tunnel, U. S. R. S.," Eng. Rec, 
 p. 433, April 22, 191 1. Contains a description of the power 
 plant for this project. 
 
 Anon., "Temporary Power Plant for Woolwich Footway Tun- 
 nel," Engineer (London), p. 46, Jan. 12, 1912, 2 pages, illus. 
 Description of a plant using suction gas-producers as a 
 source of motive power to operate the air-compressors for a 
 tunnel under the Thames, driven under compressed air. 
 
 Coy, B. G., "The Laramie-Poudre Tunnel," Proc. Am. Soc. Civ. 
 Engrs., p. 217, March, 191 2. Contains a description of the 
 water-power plant at this tunnel. 
 
 Smith, Cecil B., "Power Plants for the Mines in the Cobalt 
 District," Min. and Engr. World, p. 503, March 2, 191 2, 
 3^ cols., 2 illus. Description of water-power plants furnish- 
 ing power to the Cobalt camp. 
 
 Anon., "The Bituminous Gas Engine in South Africa," The Engi- 
 neer, p. 258, March 8, 191 2, 4 cols., 3 photos. Contains a 
 description of a bituminous producer plant at the tin mines 
 on the Groenfontein farm in the Transvaal. 
 
BIBLIOGRAPHY 385 
 
 Brunton, D. W., "Notes on the Laramie-Poudre Tunnel," 
 Trans. Am. Inst. Min. Engrs., p. 357, April, 191 2; also 
 abstract in Engng. and Min. World, p. 959, May 4, 191 2. 
 Contains a description of the water-power plant at this 
 tunnel. 
 
 AIR COMPRESSORS 
 
 WiGHTMAN,L. I., "Electrically Driven Air Compressors for Metal 
 Mining Purposes," Comp. Air Mag,, p. 3054, Aug., 1904, 
 io>^ pages, illus. 
 
 , "The Air Power Plant of the Modern Mine," Min. Mag., 
 
 p. 357, Nov., 1905, 20 cols. Discusses the advantages 
 and disadvantages of different types of air compressors. 
 
 , " Compressed Air, its Production, Transmission, and 
 
 AppUcation," Proc. Eng. Soc. West Penna., Vol. XXII, 
 p. 197, June, 1906, 42% pages. A detailed discussion of 
 the problems encountered in air compression, including 
 stage compression, cooling devices, types of compressors, 
 and receivers. 
 
 Cone, J. D., "Selection of Proper Air Compressor," Min. and 
 Min., Vol. XXVII, p. loi, Oct., 1906, 6% cols., 6 illus. 
 Economic and mechanical considerations influencing the 
 purchase. 
 
 WooDBRiDGE^, D. E., "The Hydraulic Compressed Air Power 
 Plant at the Victoria Mine (Mich.)," E. M. J., p. 125, 
 Jan. 19, 1907, 5 pages, illus. Description of the Taylor 
 system. Tested efficiency, 82 per cent. 
 
 Hart, J. H., "Compressed Air in Mining," E. M. /., Vol. 
 LXXXIII, p. 855, 1907, 2V2, cols., illus. Describes principle 
 of the Taylor air compressor and suggests a simple applica- 
 tion of it for use in mine shaft. 
 
 Halsey, F. a., "A New Development in Air Compressors," 
 E. M. J., Vol. LXXXIV, p. 397, Aug. 31, 1907, 11 cols., illus. 
 A constant speed electrically operated, variable delivery air 
 compressor that automatically varies the delivery to meet 
 fluctuating demand. 
 
 Anon., "Efficiency of HydrauHc Air Compression," £. M. J., 
 p. 228, Aug. I, 1908. Abstract of article in GlUckauf, March 
 
386 MODERN TUNNELING 
 
 14, 1908, by p. Bernstein. Contains a description of a 
 hydraulic compressor installed at one of the mines at 
 Clausthal, together with tests of its efficiency. 
 
 Brown, C. Vessey, ^'Air Compressors," Cassier^s Mag., p. 511, 
 Oct., 1908, 27 pages. Discusses the important features in 
 the design of air compressors, and describes a number of 
 types and makes. 
 
 Anon., "Rock Excavation with a Portable Air Compressor Out- 
 fit," Eng. Rec, p. 25, Jan. 2, 1909, 3 cols., illus. Describes 
 and discusses portable gasohne compressor. 
 
 Anon., "High Pressure Gas Transmission," Comp. Air Mag.y 
 p. 5306, June, 1909, 3 cols. Describes a compressor used 
 in pumping the gas for high-pressure transmission. 
 
 Webb, Rich. L., "Cost of Producing Compressed Air at a 
 Canadian Mining Camp," Can. Min. Jour., p. 102, Feb. 15, 
 1910, 20 cols., 10 tables. Results of tests on two steam- 
 driven air compressors. 
 
 McFarlane, Geo. C, " Compressing Air by Water," p. 281, Min. 
 Sci. Press, Feb. 19, 1910, 2 cols., illus. Contains descriptions 
 of several devices for converting the water-power, which is 
 so often available in mining districts, into compressed air. 
 
 Anon., "Taylor HydrauKc Air Compressor (Cobalt)," Comp. 
 Air Mag., p. 5675, June, 1910, 6^ cols. Description taken 
 from an article in Mines and Minerals, by C. H. Taylor. 
 
 Rice, Rich. H., "Commercial Application of the Turbo-compres- 
 sor," Proc. Am. Soc. Mech. Engrs., p. 303, 1911, 12 pages, 
 
 6 illus. Describes a turbo-compressor for blast-furnace work 
 and its automatic governing mechanism. Gives data upon 
 the sizes, capacity, and performance of the compressor. 
 
 Bateman, G. C, "Cobalt HydrauKc Company," E. M. J., p. 
 998, Nov. 18, 191 1, 1,000 words. Description of a Taylor 
 compressor in which the air is drawn into a falling column 
 of water. Compressed air is sold at 25 cents per 1,000 cubic 
 feet at 120 pounds pressure. 
 
 LowENSTEiN, L. C, "Centrifugal Compressors," series of arti- 
 cles in the Gen, Elec. Review, p. 136, March, 191 2, 8 pages, 
 
 7 illus. : theoretical discussion of the principles of the cent- 
 
BIBLIOGRAPHY 387 
 
 rifugal compressor and the factors that influence efficient 
 operation; p. 185, April, 1912, 11 pages, 14 iUus. Describes 
 the application of centrifugal compressors to various kinds 
 of work; p. 317, May, 191 2, 8 pages, 7 illus. Discusses the 
 rating of centrifugal compressors and the amount of power 
 required for their operation. 
 
 Anon., ''Free-Piston Internal- Combustion Air- Compressor," 
 Engineering, p. 285, March i, 1912, 2^ cols., 3 illus. Descrip- 
 tion of a machine recently developed by Signor Matricardi, 
 Palanza, Italy, in which a heavy piston is propelled from 
 one end of a cylinder to the other, and during its motion 
 compresses air in front of it. 
 
 Sibley, Robert, ''Power Computation of Rotary Air Compres- 
 sors," Jour. Elec. Power and Gas, p. 270, March 23, 191 2, 
 4^ cols., 3 illus. An elementary discussion of the theoretical 
 computation of power required in rotary air compression. 
 
 LowENSTEiN, L. C, "The Centrifugal Compressor in the Man- 
 ufacture of Gas," Am. Gas Light Jour., p. 204, March 25, 
 191 2, 10 cols., 6 illus. Describes and discusses the principles 
 of operation of turbo-compressors. Describes an automatic 
 governing device in detail and cites a number of examples 
 of the use of turbo-compressors. 
 
 Anon., "Turbo-compressors in Practical Service," Iron Age, 
 April 4, 191 2, 4 cols., 2 illus. Discusses the commercial 
 promise of turbo-compressors and blowers and the efficiency 
 of the different means of driving them. Also cites several 
 installations. 
 
 WiGHTMAN, L. L, "The Compressed Air Plant for Use at Mines," 
 Min. and Eng. World, p. 757, April 6, 191 2, 4 cols. Dis- 
 cusses the advantages and disadvantages of different types 
 of air compressors, together with the difficulties encoun- 
 tered with pipe lines. 
 
 Davy, Norman, "The Gas Turbine," The Engineer (London), 
 p. 421, April 26, 1912, 7 cols., 4 illus. The fifth of a series of 
 articles on the gas turbine and contains a description of 
 turbo-compressors as one of the accessory machines required 
 with the gas turbine. 
 
388 MODERN TUNNELING 
 
 Stone, S. R., ''Increasing the Efficiency of Air Compressors," 
 Min. and Eng. World, p. 1039, May 18, 191 2. Discusses 
 the means of preventing losses in air compression due to 
 heat, clearance, and rarefaction. 
 
 HoLDSWORTH, F. D., "Volumetric Efficiency of Air Compres- 
 sors," E. M. J., p. 1028, May 25, 1912, 4 cols., i illus. Dis- 
 cusses the unavoidable losses in air compression. Describes 
 an apparatus for measuring the quantity of air delivered 
 by the machine, which is the only way to secure an accurate 
 determination of its efficiency. 
 
 Anon., ''Turbo Blowers and Compressors," The Engineer (Lon- 
 don), p. 578, May 31, 1912, 2}4 cols., 4 illus. Describes a 
 20-stage machine installed at Manchester and discusses the 
 advantages of turbo-compressors. 
 
 Anon., "Turbo Blowers and Turbo-compressors," Iron and Coal 
 Trades Rev., p. 874, May 31, 191 2, 5^ cols., 10 illus. Gives 
 results of tests of a single-stage rotary blower and illustrates 
 several turbo-blowers and compressors. 
 
 COMPRESSION OF AIR 
 
 Hiscox, Gardner D., '' Compressed Air and Its Application," 
 
 800 pages, 535 illus. Published by Norman W. Henley & 
 
 Co., New York, 1901. 
 Saunders, W. L., ''Compressed Air Information, 1903," 1165 
 
 pages, 490 illus. PubKshed by Compressed Air Mag.j New 
 
 York, 1903. 
 Saunders, W. L., " Notes on Accidents Due to Combustion 
 
 within Air Compressors," jE. M. J., p. 554, April 11, 1903. 
 
 Discusses the occurrence of accidents and the means for 
 
 their prevention. 
 Anon., ''Air Compression at High Altitudes," Min. and Min., 
 
 Vol. XX, p. 324, 1903, i}i cols. 
 GoFFE, E., " Causes of Explosions in Air Compressors," E. M. /., 
 
 p. 686, April 28, 1904, 4K cols. An elaborate discussion 
 
 of the causes of air explosions. Concludes that the chief 
 
 one is probably the accumulation of dust which absorbs 
 
BIBLIOGRAPHY 389 
 
 oil and when heated by the compressed air gives off explosive 
 gases. 
 
 Gow, Alexander M., " Ignitions and Explosions in the Discharge 
 Pipes and Receivers of Air Compressors," Eng, News, p. 
 220, March, 1905, 2^ cols. Detailed results of an elaborate 
 study of the causes of air-receiver explosions, with recom- 
 mendations as to means of preventing them in the future. 
 
 WiGHTMAN, L. I., "Compressed Air: Its Production, Trans- 
 mission, and Application," Proc. Eng. Soc. West Pa., Vol. 
 XXII, p. 197, June, 1906, 42>^ pages. A detailed dis- 
 cussion of the problems encountered in air compression, 
 including stage compression, cooKng devices, types of 
 compressors and receivers. 
 
 Cone, J. D., '' Selection of Proper Air Compressor," Min. and 
 Min.j p. loi, Oct., 1906, 6% cols., 6 illus. Discusses the econ- 
 omic and mechanical considerations influencing the purchase. 
 
 Peele, Robert, '^ Compressed- Air Plant for Mines," published 
 by John Wiley & Sons, New York, 1908, 320 pages, 
 112 illus. 
 
 Brinsmade, Robt. B., " High vs. Low Pressure for Compressed 
 Air in Mines," E, M. /., p. 161, Jan. 18, 1908, 3>^ cols., 
 illus. Contains a discussion of the effects of heat during 
 compression, together with the devices for its removal. 
 
 Redfield, S. B., " Imperfect Intercooling and Efficiency of 
 Compression," Comp. Air Mag., p. 4887, June, 1908, 11 
 cols., illus. Discusses relation of cooling to efficiency. 
 
 Rix, E. A., " Compressed Air Calculations," Comp. Air Mag., 
 p. 4894, June, 1908, 10 cols. Paper read before the Mining 
 Association of the University of California. Discusses 
 calculations for design of compressed-air plants, to be used 
 for a definite purpose, giving methods of procedure in cal- 
 culating sizes, etc., of equipment. 
 
 Anon., *' EjQBiciency of Hydraulic Air Compression," E. M. J., p. 
 228, Aug. I, 1908, 3 cols., illus. Abstract of article in 
 Gliickauf, March 14, 1908, by P. Bernstein. Contains a 
 description of a hydrauHc compressor installed in one of the 
 mines at Clausthal, together with tests of its efficiency. 
 
390 MODERN TUNNELING 
 
 Burgess, J. A., '' Explosion in Compressed-Air Main/' Min. Set. 
 Press, p. 731, Nov. 28, 1908, 3>^ cols., letter to the editor, 
 and also Comp. Air Mag., p. 5186, Feb., 1909. Describes 
 an explosion at the Tonopah Mining Co., discusses the 
 probable causes, and gives the precautions being taken to 
 guard against a similar occurrence. 
 
 Richards, Frank, '' Probable Cause of Compressor Explosions,'' 
 Comp. Air Mag., p. 5250, April, 1909, 2 cols. 
 
 Redfield, Snowden B., " Compressed Air Calculation Short 
 Cuts," E. M. J., p. 1 163, Dec. 11, 1909. A chart by which 
 M.E.P. and H.P. may be determined without formulae 
 having fractional exponents, together with explanations 
 of its use. 
 
 Webb, Richard L., '' Cost of Producing Compressed Air at a 
 Canadian Mining Camp," Can. Min. Jour., p. 102, Feb. 
 15, 1910, 20 cols., 10 tables. 
 
 McFarlane, Geo. C, '' Compressing Air by Water," Min. Sci. 
 Press, p. 281, Feb. 19, 1910, 2 cols., illus. Discusses ways 
 of utilizing water power which is so often available in 
 mining districts for the compression of air and describes 
 several devices for doing this. 
 
 Anon., " Air Compressor Accidents in the Transvaal," Eng. 
 News, p. 301, March 17, 19 10, 2 cols. Discusses the probable 
 cause of several explosions and gives the precautions taken 
 to prevent their recurrence. 
 
 Haight, H. v., '' Steam-Driven Air Compressors in Cobalt," Caw. 
 Min. Jour., p. 209, April i, 19 10, 3^ cols. Discussion ot 
 the paper by Richard Webb, Can. Min. Jour., Feb. 15, 
 1910, p. 102. 
 
 Redfield, S. B., ''Efficiency of Compressed Air," Comp. A.ir 
 Mag., p. 5656, May, 1910, 3 cols. Abstract of article from 
 American Machinist, discussing the work done in compressing 
 air. 
 
 Anon., " The Energy of Compressed Air," Comp. Air Mag., p. 
 5775, Sept., 1 9 10, 2>H cols. Theoretical discussion of the 
 energy employed in compressing air and the ways it is 
 dissipated as heat. Taken from the American Machinist. 
 
BIBLIOGRAPHY 391 
 
 Anon., '' Compressed Air Efficiencies," Comp. Air Mag.y p. 5877, 
 Dec, 1910, 3K cols. Discusses the efficiency of com- 
 pressed air, especially when used in a rock drill. 
 
 Saunders, W. L., '' Compressed Air Explosions,'' E. M. /., p. 
 713, April 8, 191 1, also in Comp. Air Mag., p. 6028, May, 
 191 1, 4 cols. Discussion of possible causes and means of 
 prevention. 
 
 Matthews, F. E., '^ Air Cooling and Moisture Precipitation," 
 Comp. Air Mag., p. 6201, Oct., 191 1, 3 cols., i table. Dis- 
 cusses the effect of moisture in the air upon the difficulty 
 of cooling it. Gives a table showing the amount of moisture 
 in the air at different temperatures and degrees of saturation. 
 
 Rix, E. A., '' Operation of Air Compressors," Min. Sci. Press, 
 p. 13, Jan. 6, 191 2. Describes some of the main causes of 
 loss in air compressors and suggests remedies for such as 
 are not inherent in the design. 
 
 Stone, S. R., '' Increasing the Efficiency of Air Compressors," 
 Min. and Engng. World, p. 1039, May 18, 191 2. Discusses 
 the means of preventing losses of air compression due to 
 heat, clearance, and rarefaction. 
 
 HoLDSWORTH, F. D., " Volumctric Efficiency of Air Com- 
 pressors," E. M. J., p. 1028, May 25, 1912, 4 cols., 
 I illus. Discusses the unavoidable losses in air compression. 
 Describes an apparatus for measuring the quantity of air 
 delivered by the machine, which is the only way to secure 
 an accurate determination of its efficiency. 
 
 Affelder, Wm. L., '' Air Compressor Explosions," Min. and 
 Min., p. 651, June, 1912, 2^4 cols., i illus. Some unique 
 data upon the initial temperature of an air-compressor 
 explosion furnished by a recording thermometer. 
 
 COMPRESSED AIR ACCESSORIES 
 
 WiGHTMAN,L.I.,'' Compressed Air: Its Production, Transmission, 
 and Application," Proc. Eng. Soc. West Penna., Vol. XXII, 
 p. 197, June, 1906, 42>^ pages. A detailed discussion of 
 the problems encountered in air compression, including 
 
392 MODERN TUNNELING 
 
 stage compression, cooling devices, types of compressors 
 and receivers. 
 
 Brinsmade, Robert B., " High vs. Low Pressure for Compressed 
 Air in Mines," E. M. /., p. i6i, Jan. i8, 1908, 3K cols., illus. 
 Contains discussions of the functions of intercoolers, re- 
 heaters, and air receivers. 
 
 Edit., '' For the After Cooler," Comp. Air Mag., p. 5185, Feb., 
 1909, i^ cols. Editorial discusses the value of the after- 
 cooler in the prevention of compressed-air explosions. 
 
 Anon., " Air Receivers," Comp. Air Mag., p. 5302, June, 1909, 4 
 cols. Discusses the important functions of an air receiver. 
 
 Richards, Frank, '' Air-Receiver Practice," Comp. Air Mag., 
 p. 5419, Oct., 1909, 7 cols., illus. Discusses the functions 
 and efficiency of air receivers. 
 
 Anon., " Tunnel Used for Compressed- Air Storage," Comp. Air 
 Mag., p. 5443, Oct., 1909, 2 cols. Describes the use of an 
 old cross-cut as an air receiver, giving a storage capacity 
 equal to the output of the compressor for twenty- three 
 minutes. 
 
 Anon., '' Compressor Pre-Cooler," E. M. /., p. 1081, Nov. 27, 
 1909. Describes a simple, home-made pre-cooler consisting 
 of a number of odd pipes kept constantly wet. 
 
 Anon., "Compressor Pre-Cooler," £. If./., p. 550, Sept. 17, 1910. 
 Describes a pre-cooler consisting of a subway leading to a 
 building having walls and floor of cocoa matting. 
 
 Richards, Frank, " Things Worth While in Compressed Air," 
 Comp. Air Mag., p. 6059, June, 191 1, 14 cols., illus. 
 Describes economical devices in use at the Rondout and 
 Yonkers compressors plants, including after-coolers, drains, 
 re-heaters, intake filters. 
 
 Jones, J. W., " The Inter-Cooler in Stage Compression," Comp. 
 Air Mag., p. 6100, July, 191 1, 7 cols., illus. Abstract of 
 an article in Machinery describing and giving the functions 
 of inter-coolers. 
 
 Richards, Frank, " Development in Compressed Air Power 
 Storage," p. 6199, Comp. Air Mag., Oct., 191 1, 4 cols. De- 
 scribes a means of maintaining constant pressure in a 
 
BIBLIOGRAPHY 393 
 
 receiver, although volume of air is changing, by use of water- 
 stand pipe. 
 
 Richards, " The Disappointing Air Receiver," Comp. Air Mag., 
 p. 621 1, Oct., 1911,4 cols. Some of the things an air receiver 
 is popularly supposed to do but which it fails to do. 
 
 Anon., "A Novel Device for Re-heating Compressed Air for Use 
 in Rock Drills," Engng. and Contng., p. 542, Nov. 22, 191 1, 
 3 cols., 2 illus. Describes an automatic re-heating device 
 using vaporized liquid fuel. 
 
 Bateman, C. G., " Electric Heater for Air-Line Drains," E. M, 
 /., p. 831, April 27, 1912, 2 cols., I illus. Description and 
 drawing of an electric heater used to prevent the freezing 
 of the drains in the pipe line of the British Canadian Power 
 Co. (Cobalt District). 
 
 Anon., '' Unloading Device for Air Compressors," The Engineer 
 (London), p. 542, May 24, 1912, 2 cols., 2 illus. Describes 
 a device which, when the compressor is not working at 
 full load, permits a portion of the air being compressed in 
 the cylinder to flow back to the atmosphere or the inter- 
 cooler, as the case may be. 
 
 VENTILATION 
 
 Thrikell, E. W., "Adequate Ventilation," Min. and Min., p. 
 
 245, Jan., 1898, 4^ cols. Abstract of a paper before the 
 
 Midland Inst. Min., Civ. and Mech. Engrs. Discusses 
 
 the ventilation required in mines and the influence of gases 
 
 on men and lamps. 
 Churchill, C. S., '' Ventilation of Tunnels," The Engineer 
 
 (London), Vol. LXXVIII, p. 799, 15 cols. 
 Anon., " Improved Methods in Mine Ventilation," E. M. /., p. 
 
 1059, Nov. 28, 1908. Discusses the use of centrifugal fans 
 
 in mine ventilation. 
 Fitch, Thos. W., Jr., " Mine Resistance," West Va, Coal Min. 
 
 Inst., June 7, 19 10. Discusses the calculation of mine 
 
 resistance and gives a number of tables showing the friction 
 
 in air- ways. 
 
394 MODERN TUNNELING 
 
 AIR DRILLS 
 
 Anon., '' Burleigh s Pneumatic Rock Drill/' E. M. J., Vol. 
 VIII, p. 129, I col. 
 
 Anon., ''Air Consumption of Rock Drills," E.M.J.,p. 648, Oct. 6, 
 1906, ^ col. Gives figures for the air consumption of drills 
 at 80 pounds pressure. 
 
 Davies, W. a. T., " Mining Hard Ground," E. M. /., p. 779, 
 Oct. 27, 1905, 8 cols., illus. Abstract of ^'The Science of 
 Economically Mining Hard Ground Rock with Percussion 
 Rock Drills and Compressed Air." Trans. Australasian 
 Inst. Min. Engrs., Vol. II, No. 4, April, 1906. 
 
 Sinclair, H.L.,'' Development of an Air Hammer Drill," E. If./., 
 p. 714, April 13, 1907, 8 cols. Discusses some of the diffi- 
 culties experienced with the early types of hammer drills 
 and the modifications made to meet them. 
 
 Patterson, Samuel K., ''Air Drills and Their Efficiency," Min. 
 Sci. Press, p. 467, Oct. 3, 1908, 2^ cols. Describes briefly 
 several types of drills and outlines the methods to be used 
 in determining their efficiency. 
 
 Weston, Eustace M., " Ways of Improving Piston and Hammer 
 Drills," E. M.J.J p. 549, March 13, 1909. Recommendations 
 for improving the efficiency of drills based upon the recent 
 South African Drill Competition. 
 
 LiPPiNCOTT, J. B., " Comparative Tests of Large and Small 
 Hammer Rock Drills," Eng. News, p. 449, April 22, 1909, 
 2 cols., tables. Give the results of tests made on the 
 Los Angeles Aqueduct. 
 
 Weston, Eustace M., " Surface Trials in Rand Stope Drill 
 Competition," E. M. /., p. 998, May 15, 1909. Descrip- 
 tion of the tests, giving a Hst of the competing drills and 
 some conclusions based on the surface trials. 
 
 Anon., " Ray Consolidated Mines (Arizona)," Min. and Min., 
 July, 1909. Contains a discussion of the drilKng equipment 
 and methods used in these mines. 
 
 Anon., " Hammer Drills for Small Sewer Work," Comp.Air Mag., 
 p. 5464, Nov., 1909, 5 cols. Abstract from Eng. News of 
 description of sewer construction at Bloomington, 111. 
 
BIBLIOGRAPHY 395 
 
 Anon., "Air Hammer Drills," Comp.Air Mag., p. 5539, Jan., 1910, 
 
 I col. Discusses the merits of air hammer drills. 
 Edit., '' Respect the Rock Drill," Comp. Air Mag., p. 5633, April, 
 
 1 9 10, Editorial. Some requirements for a good rock drill. 
 Saunders, W. L., '' The History of the Rock Drill," E. M. /., 
 
 p. 12, July 2, 1910, and also Comp. Air Mag., p. 5679, June, 
 
 1 9 10. Brief history of pneumatic rock drill. 
 HiRSCHBERG, Chas. A., '' History of the Water Leyner Drill," 
 
 Min. Sci. Press, p. 596, Oct. 29, 19 10, i col. 
 Dana, Richard T., and W. L. Saunders, " Rock Drilling," John 
 
 Wiley & Sons, New York, 191 1, 300 pages, 125 illus. 
 Harding, J. E., " Piston or Hammer Drills," Comp. Air Mag., 
 
 p. 5886, Dec, 1910, 3/^ cols. Discusses the advantages 
 
 and disadvantages of the two types of drill. 
 Marriott, Hugh F., '' Mining in the Transvaal in 1910," 
 
 E. M. J., p. 80, Jan. 7, 191 1, 10 cols. Contains a brief 
 
 discussion of the stope drill competition. 
 Anon., " Transvaal Stope Drill Competition," E. M. /., p. 163, 
 
 Jan. 21, 191 1, 6 cols. Abstract of official report. 
 Gordon, W. D., '^ The Transvaal Stope Drill Competition," 
 
 E. M. J., p. 356, Feb. 18, 191 1, 4K cols. Comments on 
 
 the report of the committee in charge, with a reply by the 
 
 editor of E. M. J. 
 Anon.," A Comparative Test for Air Drills " Coal Age, p. 842-3, 
 
 April 6, 191 2, 3 cols., i illus. Describes a convenient 
 
 method of testing the air consumption of drills. 
 
 HYDRAULIC DRILLS 
 
 Anon., " Data of Tunnel Work in Europe," Min. Sci. Press, Vol. 
 XLVIII, pp. 306, 322, 338, 1884. Contains a discussion of 
 the advantages of the Brandt hydrauHc drill with a de- 
 scription of its use at several European tunnels. 
 
 Talbot, F. A., ''The Walski HydrauHc Rock Drill," E. M. J., 
 p. 1278, June 18, 1910, and also Comp. Air Mag., p. 5582, 
 March, 19 10, 6 cols. Describes a rock drill which utilizes 
 water hammer effect produced when a moving column of 
 water is suddenly stopped. 
 
396 MODERN TUNNELING 
 
 ELECTRIC DRILLS 
 
 Anon., '' Meissner Electric Rock Drill/' E. M. J., p. 759, Dec. 24, 
 1898. This drill had a separate electric motor connected 
 with the drill by a flexible shaft. 
 
 Anon., " Low Cost Tunneling with Electric Drills," E. M. J. 
 p. 759, April 20, 1905, }4 col. Cost of driving 10 x 10 
 tunnel in diorite where electric drills were used during Sept., 
 Oct., and Nov., 1904. 
 
 Palmer, Granville E., '' Comparative Merits of Air and Electric 
 Drills," E. M. /., Aug. 18, 1906. Gives disadvantages of 
 electric drills. 
 
 Barnes, H. B., *' Air Drills vs. Electric Drills," E. M. /., p. 503, 
 Sept. 15, 1906, 2>^ cols. Describes briefly and discusses 
 the merits of several types of electric drills as compared 
 with air driUs. 
 
 Chase, Chas. A., " Electric vs. Air DriUs," E. M. /., p. 552, Sept. 
 22, 1906, i^ cols. Gives the results from the use of electric 
 drills in the Stilwell tunnel and in the Liberty Bell Mine. 
 
 Richards, Frank, " The Piston Action of the Electric Air DriU," 
 E. M. /., p. 699, Oct. 13, 1906, 5 cols., 2 illus. Illustrates 
 and describes the action of the ^'Electric Air" driU. 
 
 Anon., "Two Electric Drill Records with Costs," Comp. Air 
 Mag., p. 5300, 2 cols. Drilling in slate, sandstone, and 
 limestone with ^'Electric Air" drill. 
 
 Gradenwitz, a., '' A Novel Rock Drill," E. M. /., p. 1181, June 
 12, 1909. Describes a German electric drill having the motor 
 connected directly with the drill. 
 
 Anon., '' Fort Wayne Rock Drill," Min. Sci. Press, p. 548, April 
 5, 191 1, lyi cols., iflus. Illustrated description of a rotary 
 hammer electrically driven rock drill. 
 
 Hutchinson, R. W., Jr., " Modification of Mining Methods by 
 Electric Machinery," Eng. Mag., p. 592, July, 191 1, iiK 
 cols., 4 iUus. Discusses the development of the electric 
 drill and describes several types which are giving satis- 
 faction at the present time. 
 
BIBLIOGRAPHY 397 
 
 GASOLINE DRILLS 
 Anon., "A GasoUne-Driven Rock Drill/' E. M, /., Vol. LXXIX, 
 
 p. 827, 1905, 2 cols., illus. 
 
 Anon., " The Scott Gasoline Rock Drill," E. M.J., p. 1008, Nov. 
 21, 1908. Also Min. Sci. Press, p. 852, Dec. 19, 1908, and 
 Eng. News, p. 575, Nov. 26, 1908. Brief description of a 
 two-cycle gasoline rock drill. 
 
 Anon., " An English Gasoline Rock Drill," Eng. News, p. 538, 
 Nov. 17, 1910, and also Compressed Air Mag., p. 5873, 
 Dec, 1910, I col., illus. Illustrated description. 
 
 DRILLING ACCESSORIES 
 
 O'RouRKE, D. J., *' The Proper Shape for Rock Drill Bits," Mine 
 and Quarry, p. 220, June, 1908, 8 cols., 10 illus. 
 
 FiCHTEL, C. L. C.,'' Calumet and Hecla Drill Sharpening Device," 
 E. M. J., May 29, 1909, 1,200 words, illus. Illustrated 
 description of plant that handles 4,000 drills daily. 
 
 DE Gennes, M., '' Selection and Use of Bits for Power Drills," 
 E. M. J., p. 1183, June 12, 1909, 1,500 words. Discusses 
 the different types and effect of size, shape, and cutting edge 
 on the results. 
 
 JUDD, Edw. K., '' Design of Bits for Power Drills," E. M. /., 
 p. 1220, Dec. 18, 1909. Discussion and comment on M. 
 de Gennes' article in E. M. J., June 12, 1909. 
 
 Weston, E. M., '' Ejecting Sludge from Drill-Holes," E. M. /., 
 p. 799, April 22, 191 1, I col., illus. Describes a method of 
 cleaning holes by utilizing the plunger action of piston 
 drills to force the sludge back through a hollow drill steel and 
 out through a vent in the side of the steel near the chuck. 
 
 McDonald, P. B., " DrilHng with Double Screw Columns," 
 E. M. J., p. 1049, ^^y 27, 191 1, I col. Discusses the 
 advantages of the vertical column over the horizontal 
 bar mounting for drills. 
 
 Anon., " Long Column Arms in Tunnels," Mine and Quarry, p. 
 540, Aug., 191 1, 1 col., illus. Describes the use of long arms 
 on columns in tunnels of circular or oval cross-section. 
 
 Blackburn, Ward," Notes on the Design of Drill Bits," E. M. J., 
 
398 MODERN TUNNELING 
 
 p. 927, May, 191 2, 5 cols., illus. An article on the proper 
 shape of drill bits. Advocates the use of sharpening 
 machines. 
 
 HAULAGE 
 
 Clarke, W. B.,'' Electric Mine Locomotives,'' Min. andMin., p. 
 389, April, 1 90 1, 5>^ cols., illus. Discusses things to be 
 observed in choosing, operating, and caring for mine loco- 
 motives. 
 
 Clarke, W. B.,'' Electric Mine Haulage," Min. and Min., p. 252, 
 Jan., 1902, 4>^ cols., illus. Discusses design of electric 
 motor equipment. 
 
 Anon., " Electric Haulage in Metal Mines," E. M. /., Vol. 
 LXXVn, p. 324, 1904, 3 cols. 
 
 Clarke, W. B., " Electric Mine Haulage," Min. Mag., p. 269, 
 Oct., 1904, 14 cols., illus. First practical electric locomo- 
 tive built in 1887 still in use in 1904. Describes some of 
 the advantages of electric haulage and some of the more 
 famihar types. 
 
 Anon., '' Mine Car Running Gear," E.if ./.,p.938. May 18, 1905, 
 tyi cols., illus. Discusses the design of running gears for 
 mine cars. 
 
 SOLIER, A., '' Electric Traction in the Simplon Tunnel," Proc. 
 Inst. Civ. Engrs., Vol. CLXVI, p. 465, 1906. Descrip- 
 tion of the electric traction system adopted in the Simplon 
 tunnel. 
 
 Norman, Fred, '' Advantages of Electric Haulage," Min. and 
 Min., p. 383, March, 1908, 3 cols. Abstract of a paper read 
 before the Y. M. C. A. Mining Inst, at Dubois, Pa., July, 
 1907. Compares electricity with rope haulage, compressed 
 air, and steam. 
 
 DeWolf, E. C, ^' Haulage System at the Yak Tunnel," Min. and 
 Met. Jour., June 26, 1908, 2/i pages. A description of 
 the method of handHng ore and waste at the Yak tunnel. 
 
 FooTE, Arthur B., ^* Dumping Waste with Locomotive Train," 
 E. M. J., p. 711, Oct. 10, 1908. Describes a plow which 
 could be attached at the end of a train of dump cars and 
 push the rock over the edge of the dump when pulled by 
 
BIBLIOGRAPHY 399 
 
 the locomotive, thus obviating the need of shifting the 
 track so frequently. 
 
 SiNNiBALDi, Paolo/' Electric Traction and the Simplon Tunnel," 
 Proc. Inst. Civ. Engrs., Vol. CLXXVIII, p. 439, 1909. 
 Description of the electric traction plant used in and about 
 the tunnel. 
 
 Anon., " Cost of Compressed Air Haulage," Min. and Min., p. 
 518, June, 1909, K col. Gives results obtained with com- 
 pressed-air haulage at an industrial plant where the longest 
 run is 2,400 feet. 
 
 Johnson, J. E., Jr., ''An Improved Type of Mine Car Wheel," 
 E. M. /., p. 1 180, June 12, 1909. Advocates tight-and- 
 loose wheel construction. 
 
 Perkins, F. C, " Electric Storage Battery Mining Locomotives," 
 Min. Wld., p. 597, Sept. 18, 1909, i page, illus. Describes 
 a German storage-battery mine locomotive. 
 
 Saunders, W. L., " Compressed Air in Mines — Underground 
 Haulage," E. M. J., p. 500, March 5, 1910, and also Comp. 
 Air Mag., p. 5579, March, 19 10. Discussion of a portion 
 of D. W. Brun ton's paper on Mining and Metallurgy in the 
 United States, in Bull. A.I.M. E., j/, 1910. 
 
 Anon., ^'Internal Combustion Locomotives in Mines and for 
 Surface Haulage," Petrol Rev., May 21, 1910, lyi cols., illus., 
 and also Gas Power, p. 16, June, 1912, 3 cols., i^ pages, illus. 
 Describes and gives some of the advantages of an English 
 gasoline locomotive. 
 
 Anon., "Gasoline Mine Locomotives," Min. and Min., p. 30, 
 Aug., 1910, iK pages, 3 cols., 3 illus. Discusses the advan- 
 tages and disadvantages of gasoline locomotives, and de- 
 scribes a German type. 
 
 Anon., ''Gasoline Locomotives for Mine Use," Min. and Min., 
 p. 542, April I, 191 1. Results of the use of a gasoHne loco- 
 motive at the Midvalley Coal Co. mines, giving a table of 
 costs. 
 
 Sylvester, Geo. E., "Gasoline Motor Haulage," Min. and Min., 
 p. 629, May, 191 1. Describes and gives results of the use 
 of a gasoline locomotive in the mines of the Roane Iron Co., 
 at Rockwood, Tenn. 
 
400 MODERN TUNNELING 
 
 Anon., ''Gasoline Motors for Mines," E. M. /., p. 292, May 20, 
 191 1, 2 cols. Discusses some of the advantages of gasoline 
 mine locomotives. 
 
 Kenner, Alvin R., "Mine Tracks," E. M. /., p. 1047, May 27, 
 191 1. Discusses the laying of mine tracks and describes a 
 method of extending rails near breast. 
 
 Spahr, Jacob, "Rock Dump at Cokedale," p. 48, Min. and Min., 
 Aug., 191 1. Illustrates and describes a rock dump con- 
 sisting of a platform 22 feet long, carrying rails, pivoted at 
 one end and having under the other end a wheel which 
 , travels on a curved rail with a radius of 22 feet. 
 
 Simmons, Jesse, "Gasoline Mine Locomotive," E. M. /., p. 652, 
 Sept. 30, 191 1, 2 cols., I illus. Description of mine locomo- 
 tive for use in Trojan Mine, Portland (Black Hills). 
 
 Anon., "Rock Dump at Cameron Mine, Walsenburg, Colo.," Min. 
 and Min., p. 158, Oct., 191 1. Describes a swinging rock 
 dump. 
 
 Anon., "Fireless Locomotives," Sci. Am.Supp., p. 388, Dec. 16, 
 
 191 1, Discusses locomotives using superheated water in 
 place of a coal fire and their possibihties for mining work. 
 
 Barnes, H. B., "Storage Battery Mine Locomotive," E. M. /., 
 p. 1278, Dec. 30, 191 1, and also in Elec. Review and Western 
 Electrician, p. 52, Jan. 6, 191 2. Description of storage 
 battery mine locomotives recently installed at Big Five 
 tunnel, Idaho Springs. 
 
 Anon., "Testing GasoHne Mine Locomotives," Min. and Min., 
 p. 341, Jan., 1912, i}^ cols., illus. Description of testing 
 plant for gasoHne mine locomotives. 
 
 Anon., "Motor Trucks for HauHng Blasted Rock from City 
 Aqueduct Tunnel, New York," Engr. Rec, p. 351, March 20, 
 
 191 2, ^ col., 3 illus. A two-mile haul from shaft to dump 
 on Contract 65 required facilities for rapid transportation 
 of large loads through city streets. Gives the costs of this 
 work. 
 
 Van Brussel, J. B., "The Otto Internal Combustion Locomo- 
 tive," E. M. J., p. 657, March 30, 191 2, i}4 cols., i illus. 
 Description of a German gasoline locomotive. 
 
BIBLIOGRAPHY 401 
 
 King, A. F., ''Use of Gasoline Motors in Coal Mines," Coal and 
 Coke Operator^ p. 355, June 6, 191 2, 2 cols. Describes and 
 discusses the advantages and disadvantages of gasoline loco- 
 motives for use in coal mines. 
 
 Perkins, Frank C, "Gasoline Locomotives for Underground 
 Haulage," Engng. and Min. Wld., p. 1251, June 15, 191 2, 
 3 cols., I illus. Discusses some of the advantages of gasoline 
 locomotives for underground haulage. 
 
 TUNNELING MACHINES 
 
 Anon., "New Boring Machines for Tunneling," E. M. J., p. 969, 
 Nov. 23, 1907, 7 cols. Discusses three types of tunneling 
 machines, giving their defects. 
 
 Bancroft, Geo. J., "A History of the Tunnel Boring Machine," 
 Mining Science, Vol. LVIII, July-Dec, 1908, p. 65, 3^ 
 pages, illus.; p. 85, 3 pages, illus.; p. 106, 2}^ pages, illus.; 
 p. 125, 2^ pages, illus.; p. 145, 2 pages, illus.; p. 165, i^ 
 pages, illus. 
 
 Everest, H. A., "Tunnel Machines," Min. and Met. Jour., 
 p. 4, Sept. 5, 1908, 5 pages, illus. Thesis, Col. School of Mines; 
 an elaborate study of tunnel machines. Gives dates of pat- 
 ents and results of experiments with the various machines. 
 
 HosKiNS, A. J., "Brunton Tunnel Machine," Min. and Met. 
 Jour., p. II, Sept. 5, 1908. Part of an article on recent 
 progress in tunneling machines, and gives a short description 
 of the Brunton Tunneling Machine and the work accom- 
 plished with it. 
 
 Herrick, R. L., "Karns Tunneling Machine," Min. and Min., 
 p. no, Oct., 1908, 2}4 cols., illus. Contains a general descrip- 
 tion of the machine and gives the results of a test run made 
 with it near Denver. 
 
 Anon., "Machine for Boring Rock Tunnels," Eng. News, p. 556, 
 Nov. 19, 1908, 3 cols., illus. Description of one type of tun- 
 neling machine. 
 
 Tyssowski, John, "Trial of a Tunnel Boring Machine," Proc. 
 Inst. Civ. Engrs., England, Vol. CLXXVIII, p. 411, 1909. 
 
402 MODERN TUNNELING 
 
 Description of a test of the Terry, Tench & Proctor tunnel- 
 ing machine at New York, June, 1910. 
 
 Saunders, W. L., ''Driving Headings in Rock Tunnels," Bull. 
 A. I. M. £., p. 337, Feb., 1909, 25 pages. Discusses 
 methods of tunnel driving, with special reference to Euro- 
 pean practice. Contains also brief descriptions of several 
 tunneling machines. 
 
 Tyssowski, John, ''Practical Test of a Tunnel Machine," E. M. 
 /., p. 1296, June 26, 1909, illus. Describes the attempt to 
 use a tunneling machine in connection with the excavation 
 for the New York Central Railway Station. Describes the 
 machine. 
 
 Walton, Philip R., "Great Augers to Bore Holes in Moun- 
 tains," Tech. Wld., p. 709, Feb., 1912, 4 cols., illus. Popular 
 description of one type of tunneHng machine. 
 
 ILLUMINATION 
 
 Morrison, A. Cressy, ''Acetylene Lamps," Comp. Air Mag., p. 
 5180, Feb., 1909, 2 cols. 
 
 Grimshaw, Robert, '' Importance of Acetylene in Mine Opera- 
 tions," Min. Wld., p. 779, Oct. 16, 1909, 2K pages, illus. 
 Describes German practice as abstracted from an article 
 by R. Penkert, '' Kohle und Erz." 
 
 METHODS OF TUNNEL DRR^ING 
 
 See also Tunnel Descriptions. 
 
 Bowie, August J., ^' Tunnels Used in HydrauHc Mining," Trans. 
 
 A. I. M. E., Vol. VI, 1877. Portion of an article on hydraulic 
 
 mining in California; discusses the selection of tunnel sites, 
 
 grades, costs, methods of driving, timbering, etc., in gravel. 
 Drinker, Henry S., "Tunneling, Explosive Compounds, and 
 
 Rock Drills," published by John Wiley & Sons, New York, 
 
 1878, 1025 pages, 1085 illus., several plates. 
 Foster, C. Le Neve, "A Text Book of Ore and Stone Mining," 
 
 published by Charles Grifhn & Co., London, 1901, 730 pages^ 
 
 715 illus. 
 
BIBLIOGRAPHY 403 
 
 Brunton, D. W./' The Opening of Mines by Tunnels," E. M. J., 
 Vol. LXXI, p. 147, Feb. 2, 1901, 2% cols. Discusses the 
 drainage of mines by tunnels, with some suggestions as to 
 the methods of driving. 
 
 Prelini, Charles, ''Tunneling," pubhshed by Van Nostrand, 
 New York, 1902, 307 pages, 150 illus 
 
 Foster, C. Le Neve, ''The Elements of Mining and Quarrying," 
 published by Charles Grifhn & Company, London, 1903, 
 300 pages, 280 illus. 
 
 Gillette, H. P., "Rock Excavation, Methods and Cost," 
 published by M. C. Clark, New York, 1904, 370 pages, 
 56 illus. 
 
 Staufeer, David McNeely, "Modern Tunneling Practice," 
 published by Eng. News, New York, 1906, 300 pages, 138 illus. 
 
 Adkinson, Henry M., ''Advancing the Hot Time Lateral of 
 the Newhouse Tunnel," E. M. /., p. 758, Oct. 17, 1908, 
 Description of the methods used in this work. 
 
 Edit., '' Speed in Small Drifts," E. M. /., p. 773, Oct. 17, 1908. 
 Editorial discusses methods to be used in driving tunnels 
 and drifts where speed is sought. 
 
 Saunders, W. L., " Driving Headings in Rock Tunnels," Btdl. 
 A. I. M. E., p. 337, Feb., 1909, 25 pages, illus. Dis- 
 cusses methods of tunnel driving, with special reference 
 to European practice. Contains also brief description 
 of several tunneling machines. 
 
 Hogan, John P., '' Progress on the Rondout Pressure Tunnel," 
 Eng. Rec, p. 26, Jan. i, 1910. Describes the methods 
 employed on the Rondout Siphon in making the record 
 run of 488 feet during Nov., 1909. 
 
 H. R. S., "Freezing Ground in Tunnel Operations," Proc. 
 Inst. Civ. Engrs., Vol. CLXXX, p. 361, 1910. A short 
 description of driving through an unusually difficult piece 
 of ground in the city of Paris by the freezing method. 
 
 Hennings, F., "Long Railway Tunnels in the Alps," Proc. 
 Inst. Civ. Engrs., Vol. CLXXXI, p. 506, 19 10. A short 
 but comprehensive review of the author's opinions on 
 construction and operation of Alpine tunnels. 
 
404 MODERN TUNNELING 
 
 Saunders, W. L., " Our Best Rock Tunnel Record," Eng. Rec, 
 p. 87, Jan. 15, 1910. Discussion of the methods used in 
 making a record drive on the Rondout Siphon and a com- 
 parison of them with European practice. 
 
 HoLLiNGSWORTH, C. H., '' Rock Tunncl Records/' Eng. Rec, 
 p. 797, June 18, 1 9 10. Comment on the methods used at 
 the Loetschberg tunnel and a comparsion of them with 
 those at the Buffalo Water tunnel. 
 
 Saunders, W. L., " Rock Tunnel Records," Eng. Rec, p. 224, 
 Aug. 27, 1 9 10. Comparison of the methods employed in 
 driving the Buffalo Water tunnel and the Loetschberg 
 tunnel. 
 
 Aston, C. W., ''The EHzabeth Tunnel (Methods)," Min. and 
 Min., p. 102, Sept., 1910, 6 pages, 4 illus., 4 tables. De- 
 tailed description of the methods employed in this work. 
 
 Anon., " TunneHng Record on the Catskill Aqueduct," Eng. Rec, 
 p. 441, Oct. 15, 1910. Discusses the methods employed 
 in making a record run (Sept., 19 10, 523 feet) on the Wallkill 
 Siphon. 
 
 Lauschli, E., " Short vs. Long Headings in Tunnel Driving," 
 Eng. News, p. 661, Dec. 15, 1910, i}4 cols. Discusses, 
 the advantages of driving long headings. 
 
 Anon., " The Top Heading and the Bottom Heading Method of 
 Attack in Tunnel Construction," Comp. Air Mag., p. 5942, 
 Feb., 191 1, 3 cols. Discusses the merits of the two systems. 
 
 Becker, Arnold, '' Bottom Heading Driving on the Hunter 
 Brook Tunnel," Eng. Rec, Sept. 2^,, 191 1, 3,600 words. 
 Also Comp. Air Mag., p. 6224, Nov., 191 1. Describes 
 and discusses the advantages of the methods used in driving 
 this tunnel. 
 
 Anon., '' Comparison of Speed of DriUing the Laramie-Poudre 
 Tunnel with Recent European Tunnel Records," Engng. 
 Contng., p. 630, June 5, 191 2, 6% cols. Abstract from Proc. 
 Am. Soc. Civ. Engrs., Vol. XXXVHI, p. 707, 1912, of a 
 discussion by W. L. Saunders of B. G. Coy's paper on the 
 Laramie Tunnel. Compares methods employed. 
 
BIBLIOGRAPHY 405 
 
 DRILLING METHODS 
 Bain, H. F., '^Driving the Newhouse Tunnel/' E. if. /., p. 552, 
 
 April 19, 1902. Contains a description of the methods of 
 
 drilling employed in this work. 
 DiNSMORE, W. P. J., "Western Practice in Tunnel Driving," 
 
 Mine and Quarry, p. 118, May, 1907. Contains a discussion 
 
 of the methods of drilling used in the Ophelia tunnel. 
 McFarlane, Geo. C, ''Notes on Machine Rock Drilling," Min. 
 
 Science, p. 291, Oct. 8, 1908, 3 cols. Gives a number of 
 
 experiences in the use of rock drills and includes some data 
 
 taken from actual practice concerning means of expediting 
 
 this work. 
 Aims, Walter L, ''Methods Employed in Driving Alpine Tun- 
 nels, the Loetschberg," Eng, News, p. 746, Dec. 31, 1908. 
 
 Contains a description of the methods of drilling with a 
 
 drill carriage. 
 Anon., "The Roosevelt Tunnel," Min. and Min., p. 837, April, 
 
 1909. Contains a description of the drilling methods used 
 
 in driving this tunnel. 
 Anon., "Ray Consolidated Mines (Arizona)," Min. and Min., 
 
 July, 1909. Contains a discussion of the drilling equipment 
 
 and methods used in these mines. 
 Lavis, F., "The New Buffalo Water Works Tunnel," Eng. Rec, 
 
 p. 802, June 25, 1 9 10. Contains a description of the methods 
 
 employed in drilling. 
 HuLSART, C. R., "Excavation of the Walkill Pressure Tunnel," 
 
 Eng. News, p. 406, Oct. 20, 1910. Contains a discussion of 
 
 the methods of drilling employed in this work. 
 Saunders, W. L., "Shallow vs. Deep Holes in Headings," Comp. 
 
 Air Mag., p. 5995. A discussion of the factors that enter 
 
 into the determination of the depth of holes. Compares 
 
 American and European practice. 
 Doll, M. G., "Strawberry Valley Tunnel of the Strawberry 
 
 Valley Irrigation Project of Utah," Mine and Quarry, p. 483, 
 
 May, 191 1. Contains a description of the methods of 
 
 drilling in driving this tunnel. 
 McDonald, P. B., "Drilling with Double Screw Columns," 
 
406 MODERN TUNNELING 
 
 E. M, /., p. 1049, May 27, 191 1, i col. Discusses the ad- 
 vantages of the vertical column over the horizontal bar 
 mounting for drills. 
 
 Saunders, W. L., "Tunnel Driving in the Alps," Bull. Am. Inst. 
 Min. Engrs., No. 55, p. 507, July, 191 1. Contains a discus- 
 sion of drilling methods with a drill carriage at the Loetsch- 
 berg tunnel. 
 
 Anon., "Long Column Arms in Tunnels," Mine and Quarry , p. 
 540, Aug., 191 1, I coL, illus. Describes the use of long 
 arms on columns in tunnels of circular or oval cross-section. 
 
 Coy, B. G., "The Laramie-Poudre Tunnel," Proc. Am. Soc. Civ. 
 Engrs., p. 217, March, 1912. Contains a description of 
 the methods of drilling used at this tunnel. 
 
 Anon., "A Remarkable Bore-hole," Coal Age, p. 778, March 23, 
 191 2, lyi cols., I illus. Describes and illustrates a method 
 of drilling a bore-hole to tap an old working containing 
 water under 287 pounds pressure. 
 
 Brunton, D. W., "Notes on the Laramie Tunnel," Bull. Am. 
 Inst. Min. Engrs., No. 64, p. 357, April, 1912. Contains a 
 discussion of the methods of drilling used in driving this 
 tunnel. 
 
 BLASTING METHODS 
 
 Daw, Albert W., and C. W., "The Blasting of Rock in Mines, 
 Quarries, Tunnels, etc.," published by E. and F. N. Spon, 
 London, 1898, 264 pages, 90 illus., 19 tables. 
 
 Walke, Willoughby, "Lectures on Explosives," Wiley & Sons, 
 New York, 1902, 425 pages. 
 
 Anon., "Loading a Hole with Dynamite," E. M. J., p. 491, 
 March 7, 1907, i col. Discusses mistakes commonly made 
 in loading a hole and the methods of avoiding them. 
 
 Stovall, D. H., "Position and Direction of Holes for Blasting," 
 Ores and Metals, p. i, April 5, 1907. Discusses the greater 
 importance of the location than the number of holes, and 
 shows how the arrangement is determined by the character 
 of the ground. 
 
 Turner, H. L., "Loading Blast Holes," E. M. J., p. 433, Aug. 
 
BIBLIOGRAPHY 407 
 
 29, 1908. Discusses the preparation of the primer and its 
 
 position in the hole. 
 Bell, Robt. N., "A Selective Electric Fuse Spitting Device/' 
 
 E. M. /., p. 528, Sept. 12, 1908, illus. Description of 
 
 electric firing board. 
 Anon., ''Loading Blast Holes," E. M. /., p. 918, Nov. 7, 1908. 
 
 Gives reasons for placing the primer at the bottom of the 
 
 hole. 
 Hay, J. K., ''Loading Blast Holes," E. M. /., p. 971, Nov. 14, 
 
 1908. Gives reasons for placing the primer at the top of 
 
 the charge. 
 Colburn, E. a., Jr., "Loading Blast Holes," E. M. /., p. 11 11, 
 
 Dec. 5, 1908. Gives reasons for placing the primer at the 
 
 bottom of the hole. 
 McFarlane, Geo. C, "Loading Blast Holes and Driving Small 
 
 Drifts," E. M. /., p. 225, Jan. 23, 1909. Discusses the 
 
 position of the primer, the use of tamping, and describes a 
 
 device to remove the tamping from a missed hole. 
 Anon., "Details of Blasting Operations," Comp. Air Mag., p. 
 
 5464, Nov., 1909, i^ cols. Description for the layman of 
 
 blasting methods. 
 Thomas, H. Musson, "The Theory of Blasting with High Explo- 
 sives," E. M. J., p. 352, Aug. 21, 1909. Discussion of 
 
 blasting in stopes on the Rand. 
 Walker, Sidney F., "Firing Shots in Mines by Electricity," 
 
 E. M. J., p. 228, Jan. 22, 1910. A discussion of the causes 
 
 leading to misfires and suggestions with respect to the 
 
 selection of electric fuses. 
 HosTER, M. T., "Preparations for Blasting," E. M. /., p. 1006, 
 
 May 14, 1910. Discusses cutting the fuse, crimping primers, 
 
 loading the -hole, and spitting the fuse. 
 Semple, Clarence C., "Where the Primer Should Go," £. M. /., 
 
 p. 441, March 2, 19 12, 4 cols. Gives reasons for placing 
 
 the primer at the top of the charge. 
 Brown, H. S., "Where Should the Primer Go?" E. M. /., p. 
 
 533, March 16, 191 2, i col. Gives reasons for placing the 
 
 primer in the bottom of the hole. 
 
408 MODERN TUNNELING 
 
 Semple, Clarence C, ''Where Should the Primer Go?" March 
 23, 19 1 2, I col. Reply to the contention of H. S. Brown 
 {E. M. /., March 16, 191 2, p. 533) that the primer should 
 be placed at the bottom of the hole. 
 
 Barbour, Percy E., ''Where Should the Primer Go?" E. M. /., 
 p. 825, April 27, 191 2, 3 cols. Sums up the recent discussion 
 on this subject, quotes from various contributors, and 
 concludes that the primer should always be placed last in 
 drill holes, and that wherever there is a valid argument 
 against putting it there, there are still stronger arguments 
 for doing so. 
 
 Anon., "Don'ts Governing Handling of Explosives in Mines," 
 Min. and Eng. Wld., p. 915, April 27, 191 2, i col. Rules of 
 the Oliver Mining Co. for employees. Twenty-five "don^ts." 
 
 BLASTING SUPPLIES 
 
 Oliver, Roland L., "Detonating Caps for Blasting," E. M, J., 
 p. 682, Oct. 13, 1906, 12)/^ cols., 15 illus. Discusses the 
 choice of proper strength of caps and the various ways of 
 preparing the primer. 
 
 Anon., "Blasting Gelatine," Min. and Min., p. 282, Jan., 1909. 
 Discusses the use of "100 per cent, strength" gelatine 
 dynamite at the Roosevelt tunnel. 
 
 CuLLEN, Wm., "Gases from High Explosives," p. 297, Min. Sci. 
 Press, Aug. 28, 1909, 4 cols. Discusses the results obtained 
 from a study of the gases given off from the gelatine dyna- 
 mite used in Rand mines. 
 
 Edit., "Gases from Explosives and Mine Economy," Min. Sci. 
 Press, p. 272, Aug. 28, 1909, ij^ cols. Editorial comment 
 on Mr. CuUen's article on page 297 of the same issue. 
 
 Hodges, A. L., "Principles and Composition of Explosives," 
 Min. Wld., p. 501, Sept. 4, 1909, 2 pages. Describes and 
 gives the composition of different kinds of explosives. 
 
 Anon., "The Necessity for Strong Detonators," E. M. J., p. 498, 
 Sept. 10, 1 9 10. Discusses the advantages from the use of 
 strong detonators. 
 
 Anon., "Explosives for Tunneling," Min. and Min., p. 159, Oct. 
 
BIBLIOGRAPHY 40^ 
 
 1910, 2% cols., 2 illus. Discusses the factors to be consid- 
 ered in the selection of an explosive for tunneling. 
 
 Anon., ''Circuit Tester for Blasting," E. M. /., p. 1195, Dec. 17, 
 1910, and also Min. Sci. Press, p. 543, Oct. 22, 1910. De- 
 scribes a galvanometer for testing a blasting circuit before 
 firing. 
 
 Hall, Clarence, W. 0. Snelling, and S. P. Howell, (U. S.) 
 Bureau of Mines Bulletin ij, "Investigations of Explosives 
 Used in Coal Mining," with a chapter on the ''Natural Gas 
 Used at Pittsburgh," by G. A. Burrell, and an introduc- 
 tion by C. E. MuNROE, 191 1, 197 pages, 7 plates, and 5 figs. 
 Is intended especially for explosive chemists, but contains 
 information of interest to all persons who have occasion to 
 supervise the purchase or use of large quantities of explo- 
 sives. Discusses the thermo-chemistry of explosives and the 
 equipment and methods used by the Bureau of Mines in 
 testing explosives. 
 
 MuNROE, C. E., and Clarence Hall, "A Primer on Explosives 
 for Coal Miners," (U. S.) Bureau of Mines Bulletin ij, 
 61 pages, 10 plates, 12 figs. Discusses combustion and ex- 
 plosion, the composition of explosives, the handling and use 
 of explosives and of squibs, fuse, and detonators, and con- 
 cludes with notes on the safe shipment and storage of explo- 
 sives, and the requirements of permissible explosives. 
 Reprint of (U. S.) Geol. Survey Bulletin 42 ^.^ 
 
 Brinsmade, R. B., "Explosives Used in Mining," Comp. Air 
 Mag., p. 6076, June, 191 1, 6 cols. Discusses the nature of 
 explosives used in mining, and some of the factors influenc- 
 ing their choice. 
 
 RuTLEDGE, J. J., and Clarence Hall, "The Use of Permissible 
 Explosives," (U. S.) Bureau of Mines Bulletin 10, 19 12, 34 
 pages, 5 plates, 4 figs. Discusses the manner in which per- 
 missible explosives can be used to best advantage in blasting 
 coal. Is intended especially for coal miners and mine 
 officials. 
 
 Hall, Clarence, and S. P. Howell, "The Selection of Explo- 
 sives Used in Engineering and Mining Operations," (U. S.) 
 
410 MODERN TUNNELING 
 
 Bureau of Mines Bulletin 48, 191 2, 50 pages, 3 plates, 7 figs. 
 States the characteristics of different classes of explosives 
 and sets forth the results of tests showing the suitability of 
 explosives for different kinds of blasting. The pamphlet is 
 written for the information of all persons interested in the 
 use of explosives for blasting rock. 
 
 Snelling, W. O., and W. C. Cope, ''The Rate of Burning of 
 Fuse as Influenced by Temperature and Pressure," (U. S.) 
 Bureau of Mines Technical Paper 6, 191 2, 28 pages. Dis- 
 cusses the composition of fuse used by miners and the 
 effects of differences of pressure, temperature, etc., on the 
 normal rate of burning. 
 
 Hall, Clarence, and S. P. Howell, "Investigations of Fuse 
 and Miners' Squibs," (U. S.) Bureau of Mines Technical 
 Paper 7, 191 2, 19 pages. Discusses the essential features 
 of squibs and miners' fuse, and gives the results of various 
 tests. The salient features of specifications adopted for the 
 purchase of fuse for use on the Canal Zone, and suggestions 
 regarding the transportation and use of fuse are given. 
 
 Snelling, W. 0., and Clarence Hall, ''The Effect of Stem- 
 ming on the Efficiency of Explosives," (U. S.) Bureau of 
 Mines Technical Paper 17, 191 2, 20 pages, 11 figs. The gain 
 in efficiency by the use of stemming was demonstrated by 
 firing small charges of explosives in bore-holes in lead 
 blocks. The pamphlet is of interest to all persons who use 
 explosives for blasting coal or rock. 
 
 Hall, Clarence, and S. P. Howell, "Magazines and Thaw- 
 houses for Explosives," (U. S.) Bureau of Mines Technical 
 Paper 18, 191 2, 34 pages, i plate, 5 figs. Describes a mag- 
 azine and a thaw-house, each constructed of cement mortar, 
 and gives the quantity of material required for construction. 
 Points out the features essential for safe storage of explosives. 
 Is of interest to persons who supervise the storage and use 
 of large quantities of explosives. 
 
 Anon., "Hydraulic Cartridge for Mining," Sci. Amer., p. 364, 
 April 20, 191 2, iK cols. Describes a cartridge which 
 expands by hydraulic pressure and is very useful for break- 
 
BIBLIOGRAPHY 411 
 
 ing rock where it is essential that no shocks be imparted to 
 the surroundings. 
 
 MUCKING 
 
 PoLHEMUS, J. H., "Automatic Steam Shovel for Underground 
 Work," Min. and Min., p. 575, July, 1909, 2 cols., illus.; and 
 also E. M, /., p. 1056, Nov. 28, 1908, 2 cols., illus. Describes 
 a steam shovel operating with compressed air in the mines 
 of the Am. Zinc & Smelting Co., Carterville, Mo. 
 
 Herrick, R. L., "Mucking Problems in Tunnels," Min. and 
 Min., Vol. XXX, p. i, Sept., 1909, i page, illus. 
 
 HuLSART, C. R., "Excavation of the Wallkill Pressure Tunnel," 
 Eng. News, p. 406, Oct. 20, 1910. Contains a description 
 of the methods of mucking employed in this work. 
 
 Doll, M. G., "Strawberry Valley Tunnel of the Strawberry Val- 
 ley Irrigation Project of Utah," Mine and Quarry, p. 483, 
 May, 191 1. Contains a description of a stiff-leg derrick 
 used for dumping muck cars on this project. 
 
 Rice, Claude T., "The Use of Long- and Short-handled 
 Shovels," E. M. J., p. 155, Jan. 20, 191 2, 3 cols. Discusses 
 the merits of each type of shovel for mucking work. 
 
 TIMBERING 
 
 Sanders, W. E., Bernard McDonald, N. W. Parlee, and 
 others, "Mine Timbering," published by Hill, New York, 
 
 1907, 175 pages, 140 illus. 
 
 Meen, J. G., "The Bracing of Tunnels and Trenches, with Prac- 
 tical Formulae for Earth Pressures," Proc. Am. Soc. Civ. 
 Engrs., Vol. XXXIII, p. 559, 1908, 60 pages. 
 
 Crane, W. R., "Notes on the Use of Concrete in Mines," Con- 
 crete and Constructional Engineering Mag., p. 39, March, 
 
 1908, 6 pages, 7 illus. 
 
 VON Emperger, Fritz, "Notes on the Use of Concrete in Mines," 
 Concrete and Constructional Engineering, p. 134, May, 1908, 
 7 pages, 12 illus. 
 
 Crane, W. R., "The Use of Concrete for Mine Supports," Con- 
 crete and Constructional Engineering, p. 172, July, 1909, 
 II pages, 12 illus. 
 
412 MODERN TUNNELING 
 
 Fleming, W. S., ''Selection and Framing of Timber/' Eng. Min, 
 Jour,, Aug. 28, 1909, yi page showing cuts. 
 
 Anon., ''Method of Making Water-tight by Grouting the Yon- 
 kers Pressure Siphon of the Catskill Aqueduct," Engng. 
 Con., Feb. 9, 1910, 1,500 words. Description of grouting 
 machine, giving dimensional drawings and method of using 
 in grouting the Yonkers Siphon. 
 
 Humes, James, "False Set for Spiling Ground," E. M. /., p. 698, 
 April 2, 1 9 10, 3 cols., illus. Describes swinging false set 
 pivoted at the center of the post. 
 
 Herrick, R. L., "Tunneling on the Los Angeles Aqueduct," 
 Min. and Min., Oct., 1910. Contains an excellent descrip- 
 tion of the methods of timbering used in the north end of 
 the Elizabeth Lake tunnel. 
 
 Rice, Geo. S., "Some Special Uses of Concrete in Mining," 
 Cement, p. 432, Jan., 1911, 12 cols. 
 
 Young. Geo. J., "Driving in Loose Ground," E. M. J., p. 161, 
 Jan. 21, 191 1, lyi cols. Describes methods used on the 
 Comstock Lode. 
 
 Parrish, K. C, "Comparative Strength of Several Styles of 
 Framed Timber Sets," E. M. J., p. 208, Jan. 28, 191 1, 
 2 cols., illus. 
 
 Anon., "Methods of Handling Running and Swelling Ground," 
 Min. Eng. Wld., Dec. 9, 191 1. Describes customary prac- 
 tice of timbering tunnels. 
 
 ZiPSER, M. E., "Tunnel Lining, Catskill Aqueduct," Eng. News^ 
 p. 820, May 2, 191 2, 28 cols., 11 illus. A detailed descrip- 
 tion of the methods of lining with concrete the tunnels on 
 the Catskill Aqueduct of both the grade and the pressure 
 or siphon types. 
 
 McKLay, Guy R., "Lining a Tunnel in Swelling Rock," Eng. Rec, 
 p. 565, May 25, 191 2. Describes a concrete lining, reinforced 
 by steel rails, placed in the Snake Creek tunnel. 
 SPEED RECORDS 
 
 Anon., "Mount Cenis Tunnel," E. M. J., Vol. IX, p. 344, ^ coL 
 Contains a tabulation of the monthly progress on the 
 Mount Cenis tunnel for the year 1869. 
 
BIBLIOGRAPHY 413 
 
 Anon., '^ Rapid Tunnel Work," Min. Set. Press, Vol. XL VI, p. 
 241, April 7, 1883, >^ col. 
 
 Anon., ''Tunnel Work," Min. Sci. Press, Vol. LI, p. 292, Oct. 31, 
 1885, H col. Notice of record drive in Big Bend Tunnel, 
 405 feet, in Sept., 1885, due to good drills and good 
 ventilation. 
 
 Anon., "Big Bend Tunnel," Min. Sci. Press, Vol. LII, p. 237, 
 April 10, 1886, }i col. 
 
 Anon., ''Records in Rock Tunneling," Eng. News,p.:^jj, April 2, 
 1908, 2}i cols. Contains a compilation of the maximum rates 
 of progress at a number of American and European tunnels. 
 
 Anon., "Rates of Progress of C. M. and St. P. Tunnel through 
 Bitter Root Mountains, Montana," Eng. News, p. 9, July 2, 
 1908, I col. Gives the progress on this work for March, 
 April, and May, '1908. 
 
 LiPPiNCOTT, J. B., "A New Record Established in Driving 
 Hard Rock Tunnels," Eng. News, p. 570, Nov. 19, 1908, 
 2 cols. At the Elizabeth Lake tunnel, Oct., 1908, 466 feet. 
 Contains also a short Hst of other tunnel records. 
 
 Anon., "Records of Driving Rock Tunnels and Some Comments 
 on the High Cost of the Elizabeth Tunnel," Engr. -Contract- 
 ing, p. 393, Dec. 9, 1908, 3% cols. Contains a compilation 
 of tunnel records both American and European. 
 
 Herrick, R. L., "Tunnel Driving Records," Min. and Min., 
 p. 422, April, 1909, 8^2 cols. Discusses the factors that 
 make for rapid tunnel work and contains a compilation of 
 tunnel records. 
 
 Saunders, W. L., "European Tunnel Driving Records up to 
 Feb., 1909," Trans. A. I. M. E., Vol. XL, p. 439, 1910. 
 Contained in an article on driving headings in rock tunnels. 
 
 , "American Tunnel Driving Records up to Feb., 1909," 
 
 Trans. A. I. M. E., Vol. XL, p. 437, 1910. In an article on 
 driving headings in rock tunnels. 
 
 Anon., " Uncomparable Records," Comp. Air Mag., p. 5537, Jan., 
 1910, i>^ cols. Discusses the futility of attempting to 
 compare different records of tunnel progress without con- 
 sidering all the factors that influence them. 
 
414 MODERN TUNNELING 
 
 SAFETY AND HEALTH 
 
 Carter, T. L., ''Miners' Phthisis," E. M. /., Vol. LXXV, p. 474, 
 March 27, 1903, 4 cols. Describes prevalence of miners' 
 phthisis, which materially shortens life of miners. Gives 
 dust and oil (vaporized) as causes; powder gas, a possibility; 
 and suggests free use of water as a preventive. 
 
 Saunders, W. L., ''Notes on Accidents Due to Combustion 
 Within Air Compressors," E. M. J., p. 554, Apr. 11, 1903. 
 Discusses the occurrence of accidents and the means for 
 their prevention. 
 
 Cullen, Wm., "Miners' Phthisis, and Dust in Mines," E. M. /., 
 p. 633, Apr. 25, 1903. Discusses dust in mines as one of the 
 chief causes of this disease, and describes the methods used 
 to prevent it. 
 
 Anon., "Danger in the Cut-Off Hole," Min. and Sci. Press, Vol. 
 LXXXVI, p. 405, June 27, 1903, i col. Describes danger 
 of the cut-off hole, especially in shaft-sinking. 
 
 Hoffman, Fred. L., '' Fatal Accidents in Metal Mining," 
 E. M. /., Vol. LXXVn, 1904, p. 79, 4 cols., p. 119, 3K 
 cols. Statistics and discussion of causes of death. 
 
 GoFFE, E., '* Causes of Explosions in Air Compressors," E. M. /., 
 p. 686, April 28, 1904, 4K cols. An elaborate discussion 
 of the causes of air explosions. Concludes that the chief 
 one is probably the accumulation of dust which absorbs 
 oil and when heated by the compressed air gives off ex- 
 plosive gases. 
 
 Edit., '' Prevention, Miners' Phthisis," Editorial, E. M. /., 
 Vol. LXXVIH, p. 91, July 21, 1904, i}4 cols. Mentions 
 competition conducted by Transvaal Chamber of Mines 
 for best methods of preventing miners' phthisis. Atomizer 
 and water-drill reported favorably. Atomizer produces 
 supersaturated atmosphere. Water lays dust at point of 
 production. 
 
 Edit., " Miners' Phthisis," Min. and Min., p. 21, August, 1904, 
 i^ cols. Editorial upon the investigation by the British 
 Government into the causes of this disease. 
 
BIBLIOGRAPHY 415 
 
 Gow, Alex. M., '^ Ignitions and Explosions in the Discharge 
 Pipes and Receivers of Air Compress/' Eng. News, p. 220, 
 March, 1905, 2% cols. Detailed results of an elaborate 
 study of the causes of air-receiver explosions, with recom- 
 mendations as to means of preventing them in the future. 
 
 Anon., '' The Miner's Responsibility for Accidents," Min. Mag., 
 Vol. XIII, p. 223, lyi cols. 
 
 Haldane, J. S., and R. A. Thomas, '^ The Causes and Prevention 
 of Miners' Phthisis," Trans. Inst. Min. and Met., Vol. XIII, 
 
 P- 379. 1903-4. 
 
 Burgess, J. A., '' Explosion in a Compressed-Air Main," Min. 
 Set. Press, p. 731, November 28, 1908, and Comp. Air Mag., 
 p. 5186, Feb., 1909. Describes an explosion at the Tono- 
 pah Mining Co., and discusses the probable causes and 
 gives the precautions being taken to guard against a similar 
 future occurrence. 
 
 Anon., '' Prevention of Mine Accidents," E. M. J., p. 1088, Dec. 5, 
 1908, 7 pages. Report of Committee of Am. Mining Con- 
 gress to investigate laws relating to metal-mining. 
 
 Edit., '' For the After Cooler," Comp. Air Mag., p. 5185, Feb., 
 1909, 1% cols. Editorial discusses the value of the after- 
 cooler in the prevention of compressed-air explosions. 
 
 Anon., " A Pipe Explosion and a Runaway Compressor," Comp. 
 Air Mag., p. 5188, Feb., 1909, i col. Describes a pipe 
 explosion, which caused the compressor to run away and 
 burst the fly-wheel. 
 
 Richards, Frank, '' Probable Cause of Compressor Explosions,'^ 
 Comp. Air Mag., p. 5250, April, 1909, 2 cols. 
 
 , '^ Flames in Compressed- Air Pipes," C6>w^. Air Mag., -p. 
 
 5378, Aug., 1909, I col. Discussion of the causes of flames 
 in compressed-air pipes. 
 
 Bell, Robt. N., " Some 'Don'ts' for Explosives and Blasting," 
 E. M. J., Vol. LXXXVI, p. 1281, Dec. 2s, 1909, i col. 
 
 MuNROE, C. E., and Clarence Hall, '' A Primer on Explosives 
 for Coal Miners," (U. S.) Bureau of Mines Bulletin 17, 
 pp. 61, ro pis., 12 figs. Discusses combustion and explosion, 
 the composition of explosives, the handling and use of 
 
416 MODERN TUNNELING 
 
 explosives and squibs, fuse and detonators, and concludes 
 with notes on the safe shipment and storage of explosives 
 and the requirements of permissible explosives. Reprint 
 of United States Geological Survey Bulletin 42^. 
 Anon., " Accidents at Metal Mines," Mines and Methods^ Jan., 
 
 1910, pp. 10., illus. 
 
 Hoffman, Fred'k L., ^' Fatal Accidents in American Metal 
 Mines," E. M, J., p. 511, March 5, 1910. Gives statistics 
 and discusses the need for legislation. 
 
 Anon., ^' Air Compressor Accidents in the Transvaal," Eng. News, 
 p. 301, March 17, 1910, 2 cols. Discusses the probable 
 causes of several explosions and gives the precautions taken 
 to prevent their recurrence. 
 
 Wilson, H. M., and A. H. Fay, " First National Mine-Safety 
 Demonstration, Pittsburgh, Pa.," (U. S.) Bureau of Mines 
 Bulletin 44, with a chapter on " The Explosion at the Ex- 
 perimental Mine," by G. S. Rice, pp. 75, 191 2, 8 pis., 4 figs. 
 Describes the various exhibits at this demonstration; gives 
 the addresses made and the names of the prominent visitors. 
 Presents a summary of the investigations conducted at the 
 Pittsburgh experiment station of the Bureau of Mines. 
 
 Clark, H. H., '' The Electrical Section of the Bureau of Mines, 
 Its Purpose and Equipment," (U. S.) Bureau of Mines, 
 Technical Paper 4, 12 pp., 191 1. Briefly describes equip- 
 ment for testing electrical mining machinery, and some of 
 the tests that have been made. 
 
 Clark, H. H., W. D. Roberts, L. C. Ilsley, and H. F. 
 Randolph, " Electrical Accidents in Mines, Their Causes 
 and Prevention," (U. S.) Bureau of Mines, Miners^ Circu- 
 lar 5, 10 pp., 191 1, 3 pis. Presents suggestions as to 
 measures that mine foremen, mine electricians, and miners 
 should take to prevent electrical accidents. Also gives 
 directions for the treatment of shock. 
 
 Saunders, W. L.,'' Compressed Air Explosions, "E. M. /., p. 713, 
 April 8, 191 1, and also in Comp. Air Mag., p. 6028, May, 
 
 191 1. Discusses their possible causes and means of 
 prevention. 
 
BIBLIOGRAPHY 417 
 
 GooDALE, Stephen L., "Underground Safety Appliances," Min. 
 and Min., Oct., 191 1. Illustrates and describes devices 
 employed and scheme of working with reference to the mine 
 of H. C. Frick Coke Co. 
 
 Harrison, Geo. B., ''Accidents in Mines Caused by Fall of 
 Ground," Iron and Coal Trades Rev., Nov. 17, 191 1. Dis- 
 cusses methods for reducing such accidents. 
 
 Snelling, W. O., and W. C. Cope, "The Rate of Burning of 
 Fuse as Influenced by Temperature and Pressure," (U. S.) 
 Bureau of Mines, Technical Paper 6, 28 pages, 191 2. Dis- 
 cusses the composition of fuse used by miners and the 
 effects of differences of pressure, temperature, etc., on the 
 normal rate of burning. 
 
 Hall, Clarence, and S. P. Howell, "Investigation of Fuse 
 and Miners' Squibs," (U. S.) Bureau of Mines, Technical 
 Paper 7, 191 2, 19 pages. Discusses the essential features of 
 squibs and miners' fuse and gives the results of various tests. 
 The salient features of specifications adopted for the pur- 
 chase of fuse for use on the Canal Zone and suggestions 
 regarding the transportation and use of fuse are given. 
 
 Hall, Clarence, and S. P. Howell, "Magazines and Thaw- 
 houses for Explosives," (U. S.) Bureau of Mines, Technical 
 Paper 18, 34 pages, 191 2, i pi., 5 figs. Describes a maga- 
 zine and a thaw-house, each constructed of cement mortar, 
 and gives the quantity of material required for construction. 
 Points out the features essential for safe storage of explosives. 
 Is of interest to persons who supervise the storage and use 
 of large quantities of explosives. 
 
 Clark, H. H., "The Factor of Safety in Mine Electrical Instal- 
 lations," (U. S.) Bureau of Mines, Technical Paper ig, 191 2, 
 14 pages. The author points out the factors that tend to 
 make electrical installations less safe in mines than above 
 ground, and gives some general directions regarding the 
 adoption and maintenance of a high factor of safety. 
 
 Rice, G. S., "Mine Fires, a Preliminary Study," (U. S.) Bureau 
 of Mines, Technical Paper 24, 191 2, 50 pages, i fig. A com- 
 prehensive summary of the causes of fires in mines and the 
 
418 MODERN TUNNELING 
 
 equipment and methods to be used for preventing and 
 extinguishing such fires. The pamphlet is addressed chiefly 
 to mine owners and mine ofiicials. 
 
 Rice, G. S., "Accidents from Falls of Roof and Coal/' (U. S.) 
 Bureau of Mines, Miners^ Circular g, 191 2, 16 pages. Calls 
 attention to the high death rate from roof falls in the coal 
 mines of the United States and the need of constant watch- 
 fulness by miners and mine foremen. 
 
 Paul, J. W., "Mine Fires and How to Fight Them," (U. S.) 
 Bureau of Mines, Miners' Circular 10, 191 2, 14 pages. Tells 
 what the coal miner can do to prevent fires, and how incip- 
 ient fires can be extinguished. 
 
 Jones, L. M., "Accidents from Mine Cars and Locomotives," 
 (U. S.) Bureau of Mines, Miners' Circular 11, 191 2, 16 pages. 
 Gives precautions that should be followed in traveling haul- 
 age roads, and in handling mine cars. 
 
 Anon., " Miners' Phthisis," So. Afric. Min. Jour., p. 153, March 30, 
 191 2, i>^ cols. The first of a series of several abstracts from 
 the official report of the Medical Commission's findings in 
 their investigation of this disease. 
 
 Affelder, Wm. L., "Air Compressor Explosions," Min. and Min., 
 p. 651, June, 191 2, 2% cols., i illus. Some unique data upon 
 the initial temperature of an air-compressor explosion fur- 
 nished by a recording thermometer. 
 
 COSTS 
 
 Ralston, W. 0.,"Cost of Tunneling at the Melones Mine, Cala- 
 veras County, Cal.," Trans. A. I. M. E., Vol. XXVIII, 
 p. 547, 1898. Gives description of the equipment, method 
 of operating, and the cost of driving at the Melones 
 Mine. 
 
 Bain, H. F., "Driving the Newhouse Tunnel," E. M. /., p. 552, 
 April 19, 1902. Contains a statement of the costs of this 
 work for the year ending Aug. 31, 1900. 
 
 Bunce, Walter H., "Tunnel Driving at Low Cost," Min. Sci. 
 Press, p. 60, July 11, 1908. Discusses the cost of driving the 
 Chipeta Adit at Ouray, Col. 
 
BIBLIOGRAPHY 419 
 
 Richards, C. H., ''Some Detail Tunnel Costs in No. 7 of the 
 Los Angeles Aqueduct," Eng. News, p. 542, Nov. 18, 1909, 
 2 cols., tables. 
 
 Hancock, H. S., Jr., "Method and Cost of Constructing a 
 Water Supply Tunnel through Rock by Day Labor," Engng.- 
 Contng., May 25, 1910. Contains figures showing the cost 
 of this work. 
 
 Anon., "Some Published Costs of Tunnel Work in the Los 
 Angeles Aqueduct," Engng.-Contng., June i, 1910, 2^ pages, 
 illus. 
 
 Herrick, R. L., "Tunneling on the Los Angeles Aqueduct," Min. 
 and Min., Oct., 1910. Contains much information concern- 
 ing the cost of tunneling on this project. 
 
 Oke, a. Livingstone, "Standards of Work," E. M. /., p. 302, 
 Aug. 13, 1910. Discusses the necessity of knowing all the 
 factors that enter into each case before comparing two 
 projects as to the amount of work performed, the kind of 
 labor, and what is considered the standard of work for that 
 particular class in that locality. 
 
 Anon., "Bonus System on the Los Angeles Aqueduct," Min. and 
 Min., p. 679, June, 191 2, 5 cols., illus. Discusses the rules 
 of operation, the method of computing bonus, footage, and 
 the earnings of the men. 
 
 Lavis, F., "The New Buffalo Water Works Tunnel," Eng. Rec, 
 p. 802, June 25, 1 9 10. Contains a schedule of the wages 
 paid during the construction of this tunnel. 
 
 Lauschli, E., "Hard Rock Tunneling," Eng. Rec, p. 719, Dec. 
 17, 1 9 10. Gives a list of the wages paid on the Loetschberg 
 tunnel work. 
 
 Collins, Glenville A., "Efficiency of Engineering Applied to 
 Mining," Min. and Engr. Wld., pages 869-70, April 20, 
 191 2, 4 cols. Discusses the ways and means of applying 
 "scientific management" to mining work. 
 
\y 
 
APPENDIX 
 
 OUTLINE OF TUNNEL DATA 
 
 The following outline is intended to cover the more im- 
 portant features to be considered in making a tunnel examina- 
 tion: 
 
 General: 
 
 Name of company operating. 
 
 Head office. 
 
 Officials. 
 
 Consulting engineer. 
 
 Field superintendent. 
 
 Names and officials of former companies. 
 
 Superintendent of each. 
 
 Dates of starting, etc. 
 
 Tunnel: 
 Size. 
 Form. 
 Length. 
 
 Elevation of portal. 
 Character of rock. 
 Grade. 
 
 Size and shape of water drain. 
 St3^1e of timbering where necessary. 
 Amount of timbering. 
 
 Power Plant: 
 
 Description and arrangement. 
 
 Sizes of machinery. 
 
 Cost of plant. 
 
 Efficiency. 
 
 Cost of power. 
 
 Compressors: 
 Make. 
 Size. 
 Speed. 
 
 421 
 
422 MODERN TUNNELING 
 
 Rated capacity. 
 
 Actual capacity. 
 
 Efficiency. 
 
 Repairs. 
 
 Length and size of delivery pipe. 
 
 Arrangements for removing water in air. 
 
 Ventilation: 
 
 Make of fan or blower. 
 
 Size. 
 
 Speed. 
 
 Amomit of pressure or vacuum. v 
 
 Rated capacity. 
 
 Actual capacity. 
 
 Efficiency. 
 
 Repairs. 
 
 Size of ventilating pipe. 
 
 Thickness of metal. 
 
 Method of jointing. 
 
 Length of sections. 
 
 Where carried in tunnel. 
 
 Distance of end of pipe from face of tunnel. 
 
 Direction of air current. 
 
 Length of time required to clear after each round of shots. 
 
 Drilling: 
 Make. 
 Size. 
 
 Number of drills in face. 
 Cost of repairs. 
 Method of mounting. 
 Air pressure at drills. 
 Air consumption. 
 
 Number, depth, and direction of holes in each round. 
 Rate of drilUng. 
 
 Brand, size, and form of steel used. 
 Durability of same. 
 Method of sharpening. 
 Number sharpened per day. 
 Number of drill shifts per day. 
 Number of drillers and helpers. 
 
 Time required in setting up drills, in driUing the round, and in 
 taking down drills. 
 
APPENDIX 423 
 
 Blasting: 
 
 Make of explosives. 
 
 Brand. 
 
 Size of sticks. 
 
 Strength. 
 
 Method of loading. 
 
 Tamping. 
 
 Method of firing. 
 
 Size of wire, make of battery, precautions against short circuits 
 
 if electric firing is used. 
 Speed of fuse. 
 Method of igniting same. 
 Order of firing. 
 
 Method of making primers, and size of detonators. 
 Their position in the holes. 
 
 Time required to clean out holes, load, and shoot. 
 Temperature of rock at the face. 
 Temperature of dynamite when placed in the hole. 
 Amount of rock broken per pound of explosive. 
 Arrangements for storing explosives. 
 Arrangements for thawing explosives. 
 
 Mucking: 
 
 Number of mucking shifts per day. 
 
 Number of muckers. 
 
 Position in which they work. 
 
 Size and form of shovels used. 
 
 Is shoveling done from tunnel floor, planks, or steel plate ? 
 
 Method of handling cars in heading. 
 
 Time of loading each car. 
 
 Time of mucking for each round. 
 
 Tramming: 
 
 Horses, mules, electricity, or compressed air. 
 
 Gauge of tracks. 
 
 Weight of rail. 
 
 Arrangement of switches in tunnel and at face. 
 
 Dimensions of cars. 
 
 Capacity of cars. 
 
 Type of cars. 
 
 Arrangements for facilitating dumping. 
 
 Design, size, and material in wheels. 
 
 Method of oiling. 
 
424 MODERN TUNNELING 
 
 Method of coupling. 
 
 Brakes. 
 
 Repairs. 
 
 Durability. 
 
 Wages: 
 
 Division of labor for entire work. 
 For each individual shift. 
 Class of men employed. 
 Wages paid each. 
 Details of bonus if offered. 
 
 Speed: 
 
 Per shift. 
 
 Twenty-four hours. 
 
 Month. 
 
 Observations on contributing causes. 
 
 Cost: 
 Labor: 
 
 Engineering. 
 
 Superintendence . 
 
 Shift foremen. 
 
 Bookkeepers. 
 
 Time-keepers. 
 
 Drillers. 
 
 Helpers. 
 
 Muckers. 
 
 Motormen. 
 
 Mule drivers. 
 
 Dump men. 
 
 Blacksmiths. 
 
 Helpers. 
 
 Machinists. 
 
 Electricians. 
 
 Power engineers. 
 
 Track men. 
 
 Carpenters. 
 
 Tram men. 
 
 Any others, stating nature of duties. 
 
 Materials: 
 Powder. 
 
 Fuse. 
 
APPENDIX 425 
 
 Materials (Continued): 
 Caps. 
 Candles. 
 Carbide. 
 Light globes. 
 Timber- 
 Lumber. 
 Ties. 
 Track. 
 
 Ventilating pipe. 
 Pressure air pipe. 
 Water pipe. 
 Hose. 
 
 Machine oil. 
 Shovels. 
 Picks. 
 
 Steel for drills. 
 Blacksmiths' supplies. 
 Blacksmiths' fuel. 
 Machinists' supplies. 
 Horse feed. 
 Miscellaneous. 
 
 Repairs: 
 
 Power machinery. 
 
 Haulage equipment. 
 
 Compressors. 
 
 Ventilating machinery. 
 
 Other machinery. 
 
 Drills. 
 
 Pipe. 
 
 Track. 
 
 Electric line. 
 
 Telephone. 
 
 Buildings. 
 
 Picks and shovels. 
 
 Miscellaneous. 
 
 Power, not including labor, repairs, or depreciation: 
 For drilHng. 
 Tramming. 
 Ventilating. 
 Miscellaneous. 
 
426 MODERN TUNNELING 
 
 Depreciation: 
 Power machinery. 
 Haulage equipment. 
 Compressors. 
 Ventilating machinery. 
 Other machinery. 
 Drills. 
 Pipe Unes. 
 Track. 
 Electric line. 
 Telephone. 
 Buildings. 
 Miscellaneous. 
 
 General expenses. 
 
 Miscellaneous expenses, stating nature. 
 
 Illumination: 
 Permanent. 
 Hand. 
 
 Signaling: 
 
 Electric bell. 
 Mine telephone. 
 Other methods. 
 
 Special Difficulties: 
 Water. 
 Bad air. 
 Loose ground. 
 Poisonous gases. 
 Inaccessibility. 
 Excessive freight rates. 
 Any others, stating nature. 
 
 Conclusions: 
 
 Observations, commendations, and criticisms of methods em- 
 ployed. 
 
INDEX 
 
 PAGE 
 
 Accessibility of tunnel, influence of, on choice of power 66 
 
 Accidents, electrical, causes of 311 
 
 prevention of 313. 321, 324, 326 
 
 from explosives, causes of 293-304 
 
 prevention of 293-304, 319, 322, 325 
 
 from roof falls, causes of 290-292 
 
 prevention of 290-292, 319, 321, 324 
 
 in tunneling, frequency of . . 289 
 
 haulage, causes of 309 
 
 prevention of 309, 320, 323, 326 
 
 Acetylene, advantages of 204 
 
 cost of 204 
 
 use of, in tunneling 201, 204 
 
 Adit, definition of 2 
 
 Aftercooler, for air compressors, purpose of 106 
 
 Agricola, on mining 11 
 
 Air, compressed, consumed by drills 83 
 
 cooling of 102 
 
 danger from high temperatures in loi, 107 
 
 for transmitting power 64 
 
 losses of 83 
 
 See also Compressed air 
 
 Air compression, dangers of high temperatures produced during loi 
 
 heat produced during loi 
 
 moisture produced during 105 
 
 Air compressors, aftercooler for, purpose of 106 
 
 air receivers for, purpose of 107 
 
 belt driven, straight-line, two-stage type, figure showing 88 
 
 capacity of, loss of, causes of 83, 84 
 
 rating of 82 
 
 and power required by 82 
 
 cause of explosions in 102 
 
 direct-connected, electrically driven, duplex, two-stage type, fig- 
 ure showing 92 
 
 duplex, features of 88 
 
 duplex, compound-steam, two-stage type, figure showing 90 
 
 duplex, simple-steam, two-stage type, figure showing 89 
 
 efficiency of 109 
 
 features of 80 
 
 heat losses in 102 
 
 intercooler for 104 
 
 427 
 
428 INDEX 
 
 page: 
 
 Air compressors, power required by 82 
 
 power requirements of 109 
 
 precoolers for, need of 106 
 
 production of harmful gases in 305 
 
 proper size of, determination of 82, 83 
 
 regulation of, methods used for 97-100 
 
 relative merits of types of 94-97 
 
 selection of, factors determining 80, 94, 109 
 
 Air compressors, single-stage, power-driven type, figure showing 88 
 
 single-stage, tandem type, figure showing . , . . , 86 
 
 straight line, features of 85-88 
 
 straight-line type, figure showing 87 
 
 turbine type, power required by ; . . 82 
 
 types of 80, 85, 94, 96 
 
 unloaders for 99 
 
 volumetric efficiency of 83 
 
 Air consumed by man at work 116 
 
 Air drills, advantages of ^ 147, 148 
 
 air thrown valve type, merits of 155 
 
 auxiliary valve type, merits of 156 
 
 bar mounting for 212 
 
 column mounting for 212 
 
 cost of repairs for 153, 154 
 
 features of 130 
 
 hammer type, merits of 160 
 
 piston type, figure showing 132, 133, 134, 137 
 
 merits of _. 149 
 
 selection of, factors influencing 160, 161 
 
 tappet valve type, merits of 155 
 
 types of 130 
 
 valveless, features of 137 
 
 figure showing 137 
 
 merits of 156 
 
 valves for 131-136 
 
 ventilation supplied by 148 
 
 Air, for ventilation, quantity needed 115-118 
 
 pressure of 1 19-12 1 
 
 Air meters, types of 127, 128 
 
 Air pipe lines, drain* for, need of 108 
 
 leakage in, methods of determining . . 84 
 
 precautions in construction of 84 
 
 Air receiver, functions of 107, 108 
 
 Air required, by man for breathing, table showing 116 
 
 for ventilation of timnels 1 15, 116 
 
 Air-thrown valve rock drill, features of 132 
 
 merits of 155 
 
 Air transmission, size of pipe required for 121, 122 
 
 Ammonia dynamite, See Dynamite 
 
INDEX 429 
 
 PAGE* 
 
 Animals, accidents from, causes of 311 
 
 amount of air required by 115 
 
 for tunnel haulage, merits of 173 
 
 Anne of Lusignan, early tunnel started by 11 
 
 Arch sets, arrangement of timber in 277, 278 
 
 Arlberg tunnel (Austria), cost of 25 
 
 features of 26 
 
 progress of 25 
 
 Arthur's Pass tunnel, (New Zealand) mention of 31 
 
 Aspen tunnel (Wyoming), mention of 31 
 
 Assassin tunnel (France), cost of . 18 
 
 Auburn tunnel (Penn.), mention of 13 
 
 Austria, early railway tunnels in 14 
 
 Auxiliary valve rock drill, features of 135, 136 
 
 merits of 1 56 
 
 Aztecs, tunneling by ; 7 
 
 B 
 
 Bar mounting for drills 212 
 
 Bennett tunneling machine, features of 185 
 
 Bethell process for preserving timber 272 
 
 Bibliography 361-419 
 
 air drills 394 
 
 air compressors 385 
 
 blasting methods 406 
 
 blasting supplies 408 
 
 choice of power 382 
 
 compressed-air accessories 391 
 
 compressed-air power 380 
 
 compression of air 388 
 
 costs 418 
 
 drilling accessories 397 
 
 drilling methods 405 
 
 electric drills 396 
 
 electric power 378 
 
 gasoline drills 397 
 
 haulage 398 
 
 hydraulic drills 395 
 
 illumination 402 
 
 internal-combustion power 373 
 
 methods of tunnel driving 402 
 
 mucking 411 
 
 power-plant descriptions 382 
 
 power transmission 381 
 
 safety and health 414 
 
 speed records 412 
 
 steam power 371 
 
430 INDEX 
 
 PAGE 
 
 Bibliography, timbering 411 
 
 tunnel descriptions 360 
 
 tunneling machines 401 
 
 ventilation 393 
 
 water-power 369 
 
 Big Bend tunnel (Calif.), features of 23 
 
 Big Creek tunnel (Calif.), mention of 23 
 
 Black Rock tunnel (Pa.), mention of 15 
 
 Blast-holes, arrangement of , 221 
 
 chambering of 227 
 
 charging of 240, 249-251 
 
 depth of 229-235 
 
 at various tunnels, table showing , 235 
 
 method of firing 122 
 
 number of 219 
 
 placing of 22 1-229 
 
 position of primer in 249-251 
 
 Blasting cap. See Detonator 
 
 Blasting powder, black, gaseous products of 238 
 
 Blasts,- effectiveness of, factors affecting 227 
 
 Blisworth tunnel (England), mention of 13 
 
 Blowers, comparison with fans for ventilation 122 
 
 pressure, figure showing iii 
 
 relative merits of ill, 122 
 
 Bonticou tunnel, Catskill Aqueduct, features of 37 
 
 Bottom cut, arrangement of holes in 224, 228 
 
 description of 224 
 
 figure showing 225 
 
 Buffalo Water tunnel (N. Y.), blast holes in, arrangement of 222 
 
 depth of 235 
 
 cars used in 169 
 
 features of 49 
 
 quantity of explosives used in 243 
 
 wedge cut at, figure showing 223 
 
 Buildings, surface, fire in, danger of 313 
 
 Bureau of Mines, officials of, acknowledgments to 3 
 
 Burleigh drills, use of, in Hoosac tunnel 25 
 
 Burleigh tunnel (Colo.) 35 
 
 features of blast holes in 219 
 
 Burnettizing timber, method of 272 
 
 Busk-Ivanhoe tunnel (Colo.), details of 30 
 
 C 
 
 Call bell, for underground telephones 207 
 
 Canal tunnels, American 13 
 
 English 13 
 
 French 12 
 
INDEX 431 
 
 PAGE 
 
 Candles, dangers in use of 203, 315 
 
 for illumination, merits of 203 
 
 Cap, blasting, See Detonator 
 
 Capacity of ventilating pipe, table showing 12a 
 
 Carbon dioxide, flows of, in Los Angeles Aqueduct 305 
 
 from gasoline locomotives, method of handling 178 
 
 in rocks, dangers from encountering 305 
 
 properties of 303 
 
 Carriage mounting for drills, merits of 214, 217 
 
 Cars, tunnel, derailments of, delays from 292 
 
 desirable features of 163, 265 
 
 handling of, method of 262-265 
 
 size of 163. 
 
 Carter tunnel (Colo.), air pressures used at 103. 
 
 blast holes used in heading of 219 
 
 blast holes in, depth of 235, 
 
 bottom cut in, figure showing 225 
 
 cars used at, features of 169 
 
 consumption of air by drills in 83 
 
 cost of drill repairs at 154. 
 
 direction of air current in 114. 
 
 drilling speed at 151 
 
 features of 35 
 
 grade of dynamite used at 241 
 
 power plant at, water supply for 66 
 
 pressure required for ventilating current I2Q 
 
 system of lighting in 202 
 
 Catskill Aqueduct tunnels (N. Y.), cars used at, features of 169 
 
 depth of blast holes in 235 
 
 features of 36 
 
 grade of dynamite used in 241 
 
 quantity of explosives used 243. 
 
 siphons of, linings of 287 
 
 speed of drilling in 151 
 
 system of lighting in 202 
 
 Caved ground, timbering for 280 
 
 Caves, water-filled, danger from 316 
 
 Central power stations, economy of 66 
 
 Central tunnel (Colo.), air pressures used at 103 
 
 cars used at, features of 169 
 
 depth of blast holes in 235 
 
 direction of air current in 114. 
 
 drilling speed at 151 
 
 features of 39 
 
 grade of dynamite used in 241 
 
 pressure required for ventilation current at 120 
 
 system of lighting at 202 
 
 Chambering of blast holes, comment on 227 
 
432 
 
 PAGE 
 
 Chipeta adit (Colo.), blast holes in face of 219 
 
 cars used at, features of . . 169 
 
 features of 49 
 
 Choice of power for tunnel work, factors governing 65 
 
 Column mounting for drills, merits of 213-216 
 
 Comparison of fans and blowers for ventilation 122 
 
 Compressed air, meters for, value of 127 
 
 pipe lines, drains for 108 
 
 leakage in, method of testing for 84 
 
 power transmission by 64 
 
 removal of moisture from 105 
 
 thermal losses in loi 
 
 transmission of, cost of 70, 73 
 
 use of, for ventilation 148, 305 
 
 working pressure of 103 
 
 See also, Air, compressed 
 
 Compressed air locomotives, use of 173 
 
 Compressors, See Air compressors 
 
 Conemaugh tunnel (Pa.), mention of i^ 14 
 
 Consumption of fuel, influence of, on choice of power 74 
 
 Coquitlam tunnel (B. C), mention of 23 
 
 Corbett tunnel (Wyo.), features of 22 
 
 Cornelius Gap tunnel (Ore.), car used at 169 
 
 features of 49 
 
 Coronado tunnel (Ariz.), cost of driving 329 
 
 features of 39 
 
 Cost of railway tunnels 25 . 
 
 Cost of tunneling 328-359 
 
 See also various tunnels named 
 
 Cowenhoven tunnel (Colo.), caves in 317 
 
 timbering in, method of 282 
 
 Creosote, use of, for preserving timber 271, 272 
 
 Crimping tool, for explosives, use of 301 
 
 •Current, electric, purchased, as source of power 76 
 
 D 
 
 Delia S. mine (Colo.), cave in, flow of water from 317 
 
 Depreciation, charges for 77 
 
 Depth of drill holes 229 
 
 at various tunnels, table showing 235 
 
 Detonator, amount of explosives contained in, table showing 248 
 
 definition of 247 
 
 delay-action, features of 255 
 
 electric, figure showing 247 
 
 grades of, rating of 248 
 
 ignition of 247 
 
 position of, in primer 3^0 
 
INDEX 433 
 
 PAGE 
 
 Detonator, proper use of , 300 
 
 strength of 301 
 
 Diesel engine, advantages of 63 
 
 as a source of power 53 
 
 characteristics of 62 
 
 Direction of holes in tunnel headings 221 
 
 Direction of ventilating current, factors influencing. 113 
 
 Drift, definition of 3 
 
 Drains for compressed air pipe lines, need of 108 
 
 Drill, See Air drill. Rock drill 
 
 Drill holes, depth of, at various tunnels, table showing 235 
 
 determination of 229 
 
 shallow, merits of 231 
 
 See also Blast holes 
 
 Drill mountings, adaptability of various types 217 
 
 amount of mucking required with various types 215 
 
 choice of 218 
 
 horizontal bar, method of using 213 
 
 vertical column, merits of 214 
 
 Drill sharpening machines, advantages of 125 
 
 capacity of 126 
 
 types of 125 
 
 Drill shifts per day, single, merits of •. 209 
 
 three, merits of 211 
 
 two, merits of 210 
 
 Drilling operations, cycle of in Simplon tunnel 28 
 
 Drilling, single shift system of 209 
 
 speed at various tunnels, table showing 151 
 
 three-shift system of 211 
 
 two-shift system of 210 
 
 Drilling machines. See Air drills. Rock drills 
 
 Drills, racks for, advantages in using 207 
 
 Drinker, H. S., on early history of explosives and rock drills 19 
 
 on early railway tunnels 14 
 
 Drivers, precautions to be taken by 310 
 
 Drunkenness, See Intoxication 
 
 Dump, cradle, description of 180 
 
 for cars, types of 178 
 
 Dumping, derrick for, use of 179 
 
 Dumping device, cradle, use of 179 
 
 revolving, use of 179 
 
 types of 178-180 
 
 Dynamite, ammonia, composition of 237 
 
 gaseous products of 238 
 
 amount of, used at various tunnels 243 
 
 burning of, noxious gases from 303, 304 
 
 prevention of 303 
 
 charging of 295, 297 
 
434 INDEX 
 
 PAGE 
 
 Dynamite, detonation of 250 
 
 for tunneling, selection of 240 
 
 gases from 237, 249 
 
 gelatin, advantages of 239 
 
 composition of 236 
 
 gaseous products of 238, 303 
 
 rating of strength of 239 
 
 strength of detonators for 301 
 
 handling of, precautions in 293, 296, 322 
 
 misfires of 299 
 
 premature explosions of 296 
 
 proper method of storing of 257 
 
 proper method of thawing of 258 
 
 proper strength of detonators for 301 
 
 storing of 257 
 
 precautions in 294 
 
 thawing of, need of ^ 253 
 
 precautions in 294 
 
 ,use of, care in 324 
 
 E 
 
 Efficiency, maximum obtainable from blast hole 226 
 
 thermal, influence of on choice of power 75 
 
 volumetric, of air compressors 83 
 
 Egyptians, stone-cutting tools of 5 
 
 tunnels driven by 5 
 
 Electricity, accidents from, causes of 311 
 
 prevention of 321, 323, 326 
 
 cost of 76 
 
 purchased, as source of power 76 
 
 transmission of, best voltages for 71 
 
 cost of 70, 71 
 
 method of 71 
 
 Electric detonator, figure showing 247 
 
 Electric drill, durability of 159 
 
 merits of I57~i59 
 
 types of 141-147, 157 
 
 Electric lamp, advantages of 203 
 
 Electric locomotives, shocks from, precautions against 313 
 
 use of 174 
 
 Electric motors, types of 64 
 
 Electric power, advantages of 64 
 
 Electric voltages, best for transmission lines, determination of 71 
 
 Elizabeth Lake tunnel (Calif.), consumption of air by drills in 83 
 
 cost of driving 342 
 
 features of 43 
 
 quantities of explosives used in 243, 
 
INDEX 435 
 
 PAGE 
 
 Elizabeth lake tunnel, timbering in 284 
 
 timbering in, figure showing 285 
 
 Elizabethtown tunnel (Pa.), mention of 15 
 
 England, early railway tunnels in 14 
 
 English Charmel, tunnel under, use of tunneling machines in 183 
 
 Ernst August Stollen (Germany), details of 16 
 
 Exits, separate, need of 314 
 
 Explosive, accidents from use of 293 
 
 precautions against 293-303 
 
 charge of, determination of 241 
 
 choice of detonators for 249 
 
 chronology of 19 
 
 excessive charges of, dangers from 290 
 
 firing of, precautions in 295 
 
 gaseous products from , 238, 303 
 
 handling of, precautions in 293, 296, 322 
 
 high, burning of, cause of 303 
 
 high, proper strength of detonator for 301 
 
 methods of loading 249 
 
 misfires of, causes of 299 
 
 proper method of thawing of 258 
 
 proper method of storing of 257 
 
 premature explosions of 296 
 
 rating of strength of 239 
 
 risks in loading , 297 
 
 selection of, factors determining 236, 239 
 
 sensitiveness of 297 
 
 slitting of cartridges of 253 
 
 storing of, precautions in 294, 257 
 
 thawing of, methods 258 
 
 thawing of, necessity for 253 
 
 thawing of, precautions in 294 
 
 use of, precautions in 293-295, 322, 324 
 
 use of two grades of, at headings 240 
 
 work of, factors affecting 226 
 
 F 
 
 Falls of roof, causes of 290 
 
 False set, see Timbering 
 
 Fans, comparison with blowers for ventilation 122 
 
 Fans, ventilating, use of 1 1 1 , 1 22 
 
 Fatalities in tunneling, rate of 289 
 
 Fernald, R. H., on cost of producer-gas plants 69 
 
 Ferroux drills, results with, at Arlberg tunnel 27 
 
 Fires in tunnels, causes of 314 
 
 dangers from 314 
 
 danger from, avoidance of 314, 321, 324, 327 
 
43^ INDEX 
 
 PAGE 
 
 Fire setting, method of excavation 9 
 
 Firing blasts, methods of 254 
 
 Foreman, suggestions for 321 
 
 Forepoling, definition of 280 
 
 Fort WiUiams tunnel (Ontario), blast holes in face of 219 
 
 depth of blast holes in 235 
 
 drilling speed at 151 
 
 features of cars used at 169 
 
 system of lighting at 202 
 
 Fowler, tunneling machine, features of 185 
 
 France, early railway tunnels in 12, 14 
 
 Free Silver mine (Colo.), rushes of water in 317 
 
 Freiberg district (Germany), early use of powder in 12 
 
 Fuel consumption, influence of, on choice of power . 74 
 
 Fuse, miner's, danger of lacing through cartridge . . 253 
 
 gases from burning of 257 
 
 handling of, precautions in 298, 299 
 
 method of lighting 254 
 
 rate of burning of 244-246 
 
 causes of variations in 246 
 
 selection of, importance of 300 
 
 storage of, precautions in 247, 299 
 
 Fuse igniter, description of 256 
 
 G 
 
 Gas engines, producer, as sources of power 59 
 
 Gas, from explosives, danger of : 303 
 
 harmful, precautions against 325 
 
 inflammable, at heading, method of burning 306 
 
 method of removing 309 
 
 See also Carbon dioxide, Carbon monoxide 
 
 Gas power, producer, selection of, conditions governing 76 
 
 Gas producer, as a source of power 53. 
 
 description of principles of 60, 61 
 
 Gasoline engine, advantages of 53, 59 
 
 as sources of power 59 
 
 Gasoline locomotives, advantages of 176 
 
 cost of haulage by 177 
 
 for haulage, cost of, table showing 177 
 
 use of 59, 176, 177 
 
 Gelatin dynamite. See Dynamite 
 
 Germany, early railway tunnels in 14 
 
 Gold Links tunnel (Colo.), air pressures used at 103 
 
 blast holes in 219 
 
 depth of 235 
 
 cars used at, features of 169 
 
 direction of air current in 114 
 
INDEX 437 
 
 PAGE 
 
 Gold Links tunnel (Colo.), drilling speed at 151 
 
 features of 39 
 
 grade of dynamite used in 241 
 
 system of lighting used in 202 
 
 Grand Central sewer (N. Y.), blast holes used in face of 219 
 
 cars used in 169 
 
 features of 50 
 
 Grant's Hill tunnel (Pa.), mention of 14 
 
 Greeks, early tunnels driven by 6 
 
 Gunnison tunnel (Colo.), air pressures used at. . : 103 
 
 blast holes, in face of 219 
 
 depth of 169 
 
 Gunnison tunnel (Colo.), cars used at, features of 169 
 
 cost of drill repairs at 153 
 
 cost of driving 331 
 
 depth of blast holes in 235 
 
 direction of air currents in 1 14 
 
 features of 39 
 
 . grade of dynamite used in 241 
 
 quantity of dynamite used in 243 
 
 system of lighting 202 
 
 Gunpowder, early use in tunneling 11 
 
 "Guns," in blasting, definition of 299 
 
 H 
 
 Hacklebernie tunnel (Pa.), mention of 18 
 
 Handling cars in tunnels 263 
 
 Harecastle tunnel (England), mention of 13 
 
 Harz mines (Germany), early use of gunpowder in 12 
 
 Haulage, by gasoline locomotive, cost of, table showing cars for 163-169 
 
 data concerning, table giving 169 
 
 figure showing 164, 165, 166, 167, 168 
 
 motive power for, choice of 173-178 
 
 use of animals for 1 73 
 
 use of compressed-air locomotive for 1 73 
 
 use of electric motors for 173 
 
 Haulage accidents, causes of 309 
 
 precautions against 320, 323, 326 
 
 Hay, storage of, in tunnel, danger of 315 
 
 Heading, advantages of three shifts at 211 
 
 railway tunnel, comparison with mining tunnel 24 
 
 timbering for 283 
 
 Heat produced during air compression loi 
 
 removal of 102 
 
 Heaters for thawing houses 259 
 
 Herrick, R. L., on Los Angeles Aqueduct 284 
 
 Hicks, G. S., Jr., air transmission, formula of 119 
 
 Hindus, caves excavated by 6 
 
438 INDEX 
 
 Hole, See Blast hole p^^,^ 
 
 Holes, direction of, in tunnel headings 221 
 
 number of, in tunnel headings 219 
 
 Hoosac tunnel (Mass.), details of 25 
 
 progress and cost of 25 
 
 tunneling machines tried at 181 
 
 use of air drills at 25 
 
 Horizontal bar mounting for drills, method of using 213 
 
 Hose, supports for, advantages of 207 
 
 Hummingbird tunnel (Idaho), mucking machine at, figure showing 170 
 
 Hydraulic compressor, as source of power 55 
 
 Taylor, details of 56 
 
 figure showing 56 
 
 use of, at Mt. Cenis tunnel 55 
 
 Hydraulic drills, features of ^ 138-141 
 
 merits of 156 
 
 Hydrocarbon gas, from rocks, burning of 306 
 
 in tunnels, dangers from 306 
 
 explosibility of 306 
 
 I 
 
 Illumination, means of, at various tunnels, table showing 202 
 
 Illumination of tunnels. See Lighting 
 
 Impulse wheels, water, regulation of 98 
 
 India, early excavations in 6 
 
 Installation cost, influence of, on choice of power 66 
 
 Insulation of electric conductors, need of close inspection of 312 
 
 Intercooler, construction of 104 
 
 figure showing 104 
 
 need of 104 
 
 Interest on capital invested, charge for 77 
 
 Internal-combustion engines, as sources of power 59 
 
 efficiency of small sizes of 75, 7^ 
 
 Intoxication, as cause of accidents 318 
 
 J 
 
 Japanese tunnels, list of 33 
 
 Joker tunnel (Colo.), blast holes in, arrangement of 219 
 
 depth of 235 
 
 drilling speed at 151 
 
 features of 50 
 
 system of lighting 202 
 
 Joseph II Stollen, mention of 16 
 
 K 
 
 Karns tunneling machine, features of 186 
 
 Kellogg tunnel (Idaho), features of 50 
 
 Kelty tunnel (Scotland), features of 21 
 
INDEX 439 
 
 L PAGE 
 
 Labor required, Influence of, on choice of power 74 
 
 Lagging, definition of 280 
 
 Lake Albanus (Italy), early drainage tunnel for 8 ^ 
 
 Lake Coxamarco (Peru), early drainage tunnel for 7 
 
 Lake Fucinus (Italy), early drainage tunnel for 8 
 
 Lamps, acetylene, merits of 204 
 
 electric, merits of 203 
 
 oil, open flame, use of 202 
 
 Laramie Poudre tunnel (Colo.), blast holes in, arrangement of 219 
 
 depth of 235 
 
 order of 224 
 
 cars used in, features of 169 
 
 figure showing 166, 176 
 
 consumption of air by drills 83 
 
 cost of driving 332 
 
 direction of air current in 114 
 
 drilling speed at 151 
 
 exhauster used at 118 
 
 features of 40 
 
 grade of dynamite used in 241 
 
 lengths of shifts at 74 
 
 mounting of drills at 213 
 
 mucking, manner of 262 
 
 power plant, at water-supply for 66 
 
 pressure required for ventilation 120 
 
 quantity of explosives used in 243 
 
 speed of driving 233 
 
 system of lighting 202 
 
 Larium (Greece) tunnels, in silver mines of 7 
 
 Lausanne tunnel (Pa.), blast holes in, arrangement of 219 
 
 depth of 235 
 
 cars used at, features of 169 
 
 direction of air current in 114 
 
 dump used at 180 
 
 features of 40 
 
 grade of dynamite used in 241 
 
 system of lighting in 202 
 
 Leakage in compressed air pipe line, method of testing for 84 
 
 Lebanon tunnel (Pa.), mention of 13 
 
 Life of power plant, influence of, on choice of power 65 
 
 Lighting of tunnels, method of 201 
 
 List of Japanese tunnels 33 
 
 of noted railway tunnels, table giving 32 
 
 of patents for tunneling machines 188-201 
 
 Loading blast-holes, precautions in 295 
 
 Loading machines, figure showing 170, 172 
 
 types of 170-173 
 
440 INDEX 
 
 PAGE 
 
 Loetschberg tunnel (Switzerland), carriage mounting for drills 214 
 
 details of 29 
 
 drills employed at 29 
 
 number of muckers employed in 261 
 
 progress and cost of 25 
 
 quantity of explosives used 243 
 
 speed of mucking in 216, 263 
 
 Los Angeles Aqueduct (Calif.), air pressure used in 103 
 
 blast holes in 219 
 
 carbon dioxide encountered in 305 
 
 cars used at 169 
 
 figure showing 167 
 
 cost of drill repairs at 154 
 
 cost of driving tunnels of 333-342 
 
 cost of electric power for 76 
 
 direction of air current in , 114 
 
 drilling speed in 152 
 
 features of 41 
 
 grade of dynamite used in 241 
 
 lining of, thickness of 287 
 
 officials of, acknowledgment to 3 
 
 pressure of ventilation current 120 
 
 system of lighting 202 
 
 use of equipment in 66 
 
 Lucania tunnel (Colo.), air pressure used at. 103 
 
 cars used at, features of . 169 
 
 consumption of air by drills in 83 - 
 
 cost of drill repairs at 154 
 
 cost of driving 343 
 
 depth of blast holes in 235 
 
 direction of air current in 114 
 
 drilling speed in 151 
 
 features of , .' 43 
 
 grade of dynamite used in 241 
 
 pressure of ventilation current 120 
 
 system of lighting 202 
 
 Machinery for ventilation, selection of, factors determining 123 
 
 Malpas tunnel (France), mention of . : 12 
 
 Manager, suggestions to 319 
 
 Marshall- Russell tunnel (Colo.), air pressure used at 103 
 
 blast holes in, arrangement of 219 
 
 depth of 235 
 
 cars used in, features of 169 
 
 consumption of air by drills 83 
 
 cost of drill repairs at 154 
 
 cost of driving 344 
 
 direction of air current in 114 
 
 drilling speed at 151 
 
INDEX 441 
 
 PAGE 
 
 Marshall-Russell tunnel, features of 44 
 
 grade of dynamite used in 241 
 
 pressure of ventilation current 120 
 
 system of lightin g, 202 
 
 Mauch Chunk tunnel (Pa.), air pressure used at 103 
 
 Means of lighting at various tunnels, table showing 202 
 
 Metres for compressed air, usefulness of 121 
 
 Mine tunnels, features of 2 
 
 Miner, suggestions to 324. 
 
 Misfires, causes of 299 
 
 precautions following 302, 325 
 
 Mission tunnel (Calif.), air pressure used at 103 
 
 blast holes in, depth of , 235 
 
 cars used at, features of . 169 
 
 consumption of air by drills in 83 
 
 cost of driving 345 
 
 direction of air current in 114 
 
 features of 44 
 
 grade of dynamite used in 241 
 
 pressure required for ventilation 120 
 
 speed of drilling 151 
 
 system of lighting 202 
 
 Moisture produced during air compression 105 
 
 Moodna Siphon, Catskill Aqueduct (N. Y.), features of 37 
 
 Motive power for tunnel haulage, choice of 173-178 
 
 Mount Cenis tunnel (France), progress and cost of 25 
 
 use of air drill at 25 
 
 use of hydraulic compressor at 55 
 
 Mount Royal tunnel (Canada), details of 51 
 
 Mountings for drills, adaptability of various types 217 
 
 amount of mucking required with 215 
 
 choice of 218 
 
 horizontal bar, method of using 213 
 
 vertical column, merits of 214 
 
 Muck, danger from explosives in 302 
 
 picking of, proper method of 302 
 
 Mucking, conditions affecting speed of 260 
 
 importance of system in 262 
 
 number ot men for 261 
 
 positions of men for 261 
 
 speed attainable in 216, 263 
 
 use of steel plates in 267 
 
 Mucking machine, figure showing 170 
 
 N 
 
 Naples, Italy, Roman tunnel near 8 
 
 New York Boai'd of Water Supply, acknowledgments to 3 
 
442 INDEX 
 
 PAGE 
 
 Newhouse tunnel (Colo.), air pressure used at 103 
 
 blast holes in, depth of 235 
 
 order of 219 
 
 cars used at, features of 169 
 
 cost of driving 346 
 
 direction of air current in 114 
 
 drilling speed at 151 
 
 dumping of cars at 179 
 
 features of 44 
 
 grade of dynamite used in 241 
 
 system of lighting 202 
 
 Nisqually tunnel (Wash.), air pressure used at 103 
 
 blast holes in, depth of 235 
 
 order of 219 
 
 cars used at, features of 169 
 
 direction of air current in 114 
 
 drilling speed at 151 
 
 grade of dynamite used in 241 
 
 power plant of, water-supply for 67 
 
 • pressure of ventilating current 120 
 
 system of lighting 202 
 
 Nitrogen peroxide, deadliness of 304 
 
 Nitroglycerine, invention of 19 
 
 use of, in tunnels 19, 25 
 
 Nitroglycerine dynamite, gaseous products of 238 
 
 rating of strength of 239 
 
 Northwest tunnel (111.), blast holes in, depth of 235 
 
 order of 220 
 
 features of 51 
 
 Noted railway tunnels, table giving list of 32 
 
 Notre Dame tunnel (France), cost of 18 
 
 Number of holes in tunnel headings, table showing 219 
 
 O 
 
 Oil engines, as sources of power 53 
 
 Ontario tunnel (Utah), features of 45 
 
 Ophelia tunnel (Colo.), blast holes in, depth of 235 
 
 order of 220 
 
 drilling speed at 151 
 
 features of 51 
 
 system of lighting 202 
 
 P 
 
 Patents for tunneling machines, list of 188-201 
 
 Pawpaw tunnel (Md.), mention of 14 
 
 Pelton wheel, figure showing 54 
 
 proper speed for 55 
 
INDEX 443 
 
 PAGE 
 
 Peruvians, ancient mines and tunnels of 7 
 
 Pipe for ventilation, size of 121 
 
 Pipe lines, compressed air, leakage in, method of testing for 84 
 
 Positions of men for mucking 261 
 
 Powder headache, cause of 303 
 
 Powder smoke, removal of, air required for 117 
 
 Power, for tunneling, sources of 53 
 
 gas producer, selection of, conditions governing 76 
 
 Power, most suitable, selection of 64, 65 
 
 Power plant, cost of machinery for 66 
 
 depreciation of, charge for ']'] 
 
 fuel consumption of 74 
 
 labor requirements of 74 
 
 life of, influence of, on choice of power 65 
 
 most economical equipment for 65 
 
 producer gas for 69 
 
 steam, efficiency of 75 
 
 types of 53, 78-80 
 
 Power transmission, cost of 64, 70 
 
 electricity for 79 
 
 means of 64 
 
 Precoolers for air compressors, need of 106 
 
 Pressure of ventilating current 1 18-120 
 
 formula for determining 119 
 
 table showing 119 
 
 Pressure, loss of, in ventilating pipe 1 19 
 
 Primers, handling of 297 
 
 preparation of 301 
 
 proper place of, in charge 249 
 
 Producer gas, advantages of 64 
 
 transmission of, cost of pipe for 73 
 
 possible distance of 64 
 
 Producer-gas engines, as sources of power 59 
 
 use of in Thames River tunnel (England) 60 
 
 Producer-gas plant, selection of, conditions determining 79 
 
 thermal efficiency of 76 
 
 Producer-gas power, selection of, conditions governing 76 
 
 Progress of railway tunnels, table showing 25 
 
 Purchased current, as source of power 76 
 
 Pyramid cut, figure showing 224 
 
 most effective arrangement of holes in 228 
 
 R 
 
 Ragged Chutes (Ontario), hydraulic compressor at 56 
 
 Railway tunnels, cost of 25 
 
 details of 32 
 
 early 14 
 
444 INDEX 
 
 PAGET 
 
 Railway tunnels, noted, table giving list of 32 
 
 progress and cost of, table showing 25 
 
 Rand mine (So. Africa) , large turbo-compressors at 94 
 
 Rawley tunnel (Colo.), air pressure used at 103 
 
 blast holes in, depth of 235 
 
 order of 220 
 
 cars used at, features of 169 
 
 consumption of air by drills in 83 
 
 cost of driving 347 
 
 drilling speed at 151 
 
 features of 45. 
 
 grade of dynamite used in 241 
 
 handling of cars at 265 
 
 speed of mucking at 1-. 263 
 
 system of lighting at 202 
 
 ventilation current at 114, 118, 120 
 
 blast holes in, depth of 235 
 
 Raymond tunnel (Colo.), air pressures used at 103 
 
 order of 220 
 
 car used at, features of ^ 169 
 
 direction of air current in 1 14 
 
 drilling speed at . , 151 
 
 grade of dynamite used in 241 
 
 system of lighting 202 
 
 Regulation, of air compressors , 97-100 
 
 of water wheels 98 
 
 Removal of heat produced during air compression 102 
 
 Retallack and Redfield tunneling machine, features of 186 
 
 Rix, E. A., on compressed-air calculations 81, 149 
 
 Rock-cutting tools, ancient 5 
 
 Rock drills, air, air consumption of 149 
 
 auxiliary valve for, merits of 156 
 
 merits of 147 
 
 piston type 149, 153 
 
 figure showing 132, 133, 135 
 
 valves for, merits of 132-136 
 
 figures showing 131-136 
 
 valveless, features of 137 
 
 figure showing 137 
 
 carriage mounting for 214 
 
 choice of, factors determining i60' 
 
 comparison of different types 147-160 
 
 early use of 18 
 
 electric, advantages of I57 
 
 durability of 159 
 
 features of 141 
 
 figure showing I43» I45> 146 
 
 power consumption of I59 
 
INDEX 445 
 
 PAGE 
 
 Rock drills, electric, types of 158, 159 
 
 piston, advantages of 158 
 
 gasoline, disadvantages of 147 
 
 hammer type, advantages of 150 
 
 hydraulic, features of 138, 157 
 
 figure showing 138 
 
 types of 138, 157 
 
 mounting of 212 
 
 selection of, factors influencing 160, 161 
 
 types of 130 
 
 comparison of 160 
 
 use of, in mine tunnels. See tunnels named in railway 
 
 tunnels 25, 27, 28, 29 
 
 Roger's Pass tunnel (B. C), features of 51 
 
 Romans, rock-cutting tools of 8 
 
 tunnels driven by 8 
 
 Rondout Siphon tunnel (N. Y.), air pressure used at 103 
 
 blast holes in, depth of 235 
 
 order of 220 
 
 cars used at, features of 169 
 
 direction of air current 1 14. 
 
 drilling speed at 151 
 
 features of 36 
 
 grade of dynamite used in 241 
 
 power plant at, labor requirements of 74 
 
 quantity of explosives used in 243 
 
 use of central power station at 66 
 
 Roof, inspection of, need of care in 321 
 
 sound of, significance of 291 
 
 testing of, importance of 291 
 
 methods for '. 291 , 324 
 
 Roosevelt tunnel (Colo.), air pressure used at 103 
 
 blast holes in, depth of 235 
 
 order of 220 
 
 car used at, features of 169 
 
 cost of driving 348 
 
 direction of air current in 114 
 
 features of 46 
 
 grade of dynamite used in 241 
 
 pressure of ventilating current at 120 
 
 system of lighting 202 
 
 Rotschonberger Stollen (Germany), details of 16 
 
 S 
 
 Saint Gothard tunnel (Switzerland), details of 26 
 
 progress and cost of 25 
 
 Samos (Greece), long mine tunnel at 7 
 
446 INDEX 
 
 PAGE 
 
 Sapperton tunnel (England), mention of 13 
 
 Second Raton Hill tunnel (N. M.), features of 52 
 
 Selection of ventilating machinery, factors determining 123 
 
 Severn tunnel (England), details of 30 
 
 Sharpening machines, drill, types of 125 
 
 Shear zones, timbering for 280 
 
 Shepard's Pass tunnel (Calif.), features of 47 
 
 Shield for mine tunnels, use of 284 
 
 Shock, electrical, danger from 311 
 
 Shoshone tunnel (Colo.), cost of 22 
 
 features of 21 
 
 Shovelers, space required by 260 
 
 use of steel plates for 267 
 
 Sigafoos tunneling machine, features of 187 
 
 Simplon tunnel (Switzerland), details of 28 
 
 flow of water in 28 
 
 hydraulic drill used at, features of 138 
 
 figure showing , 138 
 
 progress and cost of 25 
 
 quantity of explosives used in 243 
 
 rock drill used at, features of 157 
 
 Single drill shift per day, merits of 209 
 
 Siwatch tunnel (Colo.), air pressure used at 103 
 
 blast holes in, arrangement of 220 
 
 depth of 235 
 
 car used at, features of 169 
 
 direction of air current in 1 14 
 
 drilling speed at 151 
 
 features of 47 
 
 grade of dynamite used in 241 
 
 pressure of ventilating current at 120 
 
 system of lighting 202 
 
 Size of tunnel cars 163 
 
 Size of ventilating pipe, formula for determining 121 
 
 table showing 122 
 
 Snake Creek tunnel (Utah), air pressure used at 103 
 
 blast holes in, depth of 235 
 
 order of 220 
 
 car used at, features of 169 
 
 concrete lining of, figure showing 288 
 
 consumption of air by drills in 83 
 
 direction of air current in 1 14 
 
 drilling speed at 151 
 
 features of 47 
 
 grade of dynamite used in 241 
 
 pressure of ventilating current 120 
 
 system of lighting 202 
 
 Sommeiller, hydraulic compressor designed by 55 
 
INDEX 447 
 
 PAGE 
 
 Spain, ancient tunnels and mines in 9 
 
 ventilation of ancient tunnels in 10 
 
 Spiling, definition of 280 
 
 Spiral tunnels (B. C), blast holes in, depth of 235 
 
 order of 220 
 
 features of ^2 
 
 Spitter, definition of 254 
 
 Steam engine, thermal efficiency of 75 
 
 types of 58 
 
 Steam power, selection of, conditions governing 76 
 
 Steam turbine, advantages of 58 
 
 efficiency of 58 
 
 features of 58 
 
 Steel plates, use of, in loading cars 264, 267 
 
 Stilwell tunnel (Colo.), air pressure used at 103 
 
 blast holes in, arrangement of 220 
 
 depth of 235 
 
 car used at, features of 169 
 
 cost of driving 352 
 
 direction of air current in 1 14 
 
 drilling speed at 151 
 
 features of 47 
 
 grade of dynamite used in 241 
 
 system of lighting in 202 
 
 Stoping drills, features of 137 
 
 figure showing 137 
 
 Storage battery locomotive, use of 174 
 
 Storing of explosives, proper method of , 257 
 
 Strawberry tunnel (Utah), air pressure used at 103 
 
 blast holes in, arrangement of 220 
 
 depth of 235 
 
 car used at, features of 169 
 
 consumption of air by drills in 83 
 
 cost of drill repairs at 154 
 
 cost of driving 353-359 
 
 direction of air current in 1 14 
 
 drilling speed at 151 
 
 dumping of cars at 178 
 
 features of 48 
 
 grade of dynamite used in 241 
 
 pressure of ventilating current at 120 
 
 system of lighting 202 
 
 Superintendent, suggestions to 319 
 
 Sutro tunnel (Nev.), features of 19 
 
 Swelling ground, timbering for 279 
 
 T 
 
 Tailblock system, timbering for 281 
 
 Taillades tunnel (France), mention of 18 
 
44^ INDEX 
 
 PAGE 
 
 Talbot tunneling machine, mention of i8i 
 
 Tamping, early use of, in tunneling 1 1 
 
 in tunnel work, merits of 252 
 
 proper amount of 252 
 
 proper method of 297 
 
 reasons for using 252 
 
 Tamping bar, proper use of 297 
 
 Tappet valve rock drill, features of 132 
 
 merits of 155 
 
 Telephone, installation of 205 
 
 type of, selection of 206 
 
 use of, reasons for 205 
 
 Temperatures, high, produced during air compression, dangers of loi 
 
 Terry, Tench and Proctor, tunneling machine of, features of 185 
 
 Tequiquac tunnel (Mexico), details of 21 
 
 Terre- noire tunnel (France), mention of 14 
 
 Thawing of explosives, proper method of 258 
 
 Thaw houses, construction of 258 
 
 heating of 259 
 
 Thermal efficiency, influence of, on choice of power 75 
 
 Tiefe Georg Stollen (Germany), details of 15 
 
 Timber, for roof support, advantages of 270 
 
 preparation of 270 
 
 preservative treatment of 270-273 
 
 seasoned, advantages of 270 
 
 selection of 292 
 
 square versus round, choice of 271 
 
 Timbering, adequate importance of 292 
 
 arrangement of, in tunnel 273-278 
 
 delay in, danger of 292 
 
 for wet tunnels, figure showing 275, 276 
 
 swinging false set system of 282 
 
 materials for 270 
 
 of heading, m.ethod of 283 
 
 of swelling ground, method of 279 
 
 tail-block system of 281 
 
 Torches, danger in use of 314 
 
 Totley tunnel (England), details of 30 
 
 Tramming, dangers in 309, 310 
 
 Transmission of power, means of 64 
 
 Transvaal, ventilation requirements in 115 
 
 Trolley wires, danger from 311 
 
 Tsude Adit (Japan) , mention of 33 
 
 Tunnel, definition of 2 
 
 Tunnel cars, data concerning, table giving 169 
 
 figure showing 164-168 
 
 types of 164-170 
 
 Tunnel headings, direction of holes in 221 
 
INDEX 449 
 
 PAGE 
 
 Tunnel headings, number of holes in, table showing 219 
 
 Tunneling machines, features of 181 
 
 patents for, list of 188-201 
 
 requirements of 184 
 
 types of 185-187 
 
 use of, in English Channel tunnel 183 
 
 Turbine- wheels, as sources of power 55 
 
 efficiency of 57 
 
 features of 55 
 
 steam, efficiency of 58 
 
 features of 58 
 
 Turbo-compressors, advantages of . 109 
 
 effectiveness of 92 
 
 features of 9i~93 
 
 figure showing 95 
 
 power required by 82 
 
 section through, figure showing 93 
 
 use of, for ventilation 112 
 
 U 
 
 United States Reclamation Service, officials of, acknowledgments to 3 
 
 United States, early railway tunnels in 14 
 
 Unloaders for air compressors, use of 99 
 
 Utah Metals tunnel (Utah), air pressure used at 103 
 
 blast holes in, depth of 235 
 
 order of 220 
 
 car used at, features of 169 
 
 direction of air current in 1 14 
 
 drilling speed at 151 
 
 features of 48 
 
 grade of dynamite used in 241 
 
 power plant of, water supply for 66 
 
 pressure of ventilating current 120 
 
 system of lighting 202 
 
 V 
 
 V-cut, arrangement of holes in 226 
 
 Valveless air drills, merits of 156 
 
 Valve, butterfly, figure showing 134 
 
 merits of 1 56 
 
 tappet, advantages of 155 
 
 Ventilating current, air needed for 115, 116 
 
 arrangement of pipes for, figure showing 113 
 
 direction of, factors influencing 113 
 
 machinery for 1 1 1 
 
 pressure of 118, 119 
 
 size of pipe line for 121, 122 
 
450 INDEX 
 
 PAGE 
 
 Ventilating machinery, selection of, factors determining 123 
 
 Ventilating pipe, capacity of, table showing 120 
 
 Ventilation, of ancient tunnels 10 
 
 of tunnels, air required for 115, 116 
 
 Vertical column mounting for drills, merits of 214 
 
 Volumetric efficiency of air compressors 83 
 
 Wallkill Siphon tunnel (N. Y.), air pressure used at 103 
 
 blast holes in, depth of 235 
 
 order of 220 
 
 car used at, features of 169 
 
 direction of air current in 114 
 
 drilling speed at 151 
 
 grade of dynamite used in 241 
 
 quantity of explosives used in 243 
 
 Water, rushes of, danger from ,. 315 
 
 for fire protection, need of 314 
 
 Water power, selection of, conditions determining 78 
 
 Water wheels, cost of installation of 66 
 
 - efficiency of 57 
 
 impulse type, regulation of 98 
 
 turbine type, details of 55 
 
 use of 55 
 
 Wedge cut, description of 221 
 
 figure showing , 223 
 
 Woolwich tunnel (England), power plant of, fuel consumption of ...... . 75 
 
 use of gas-producers at 50 
 
 Y 
 
 Yak tunnel (Colo.), air pressure at 103 
 
 blast holes in, depth of 235 
 
 order of 220 
 
 car used at, features of 169 
 
 cost of drill repairs at ". 153 
 
 direction of air current in 1 14 
 
 features of . . 48 
 
 grade of dynamite used in 241 
 
 pyramid cut in, figure showing 224 
 
 Yonkers Siphon tunnel (N. Y.), features of 38 
 
 Z 
 
 Zinc chloride as timber preservative 271 
 
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