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diff --git a/old/44502.txt b/old/44502.txt new file mode 100644 index 0000000..43acf18 --- /dev/null +++ b/old/44502.txt @@ -0,0 +1,9574 @@ +The Project Gutenberg EBook of Every-day Science: Volume VI. The Conquest +of Nature, by Henry Smith Williams and Edward Huntington Williams + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Every-day Science: Volume VI. The Conquest of Nature + +Author: Henry Smith Williams + Edward Huntington Williams + +Release Date: December 24, 2013 [EBook #44502] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK EVERY-DAY SCIENCE: VOL VI *** + + + + +Produced by Chris Curnow, John Campbell, Albert LAiszlA cubed +(bertzi) and the Online Distributed Proofreading Team at +http://www.pgdp.net (This file was produced from images +generously made available by The Internet Archive) + + + + + + + + + + TRANSCRIBER'S NOTES + + Italic text is denoted by _underscores_. + The oe ligature has been expanded to 'oe'. + Subscripts in chemical formulas are denoted by normal numbers; + for example CaC2. + + Obvious typographical and punctuation errors have been corrected + after careful comparison with other occurrences within the text + and consultation of external sources. + + More detail can be found at the end of the book. + + +[Illustration: A PRIMITIVE USE OF THE ANIMAL MACHINE THAT IS STILL IN +VOGUE IN MANY EUROPEAN COUNTRIES. + +(From the painting by J. Didier, in the _Musee du Luxembourg_, Paris.)] + + + + + EVERY-DAY SCIENCE + + BY + HENRY SMITH WILLIAMS, M.D., L.L.D. + + ASSISTED BY + EDWARD H. WILLIAMS, M.D. + + VOLUME VI + + THE CONQUEST OF NATURE + + ILLUSTRATED + + + NEW YORK AND LONDON + THE GOODHUE COMPANY + PUBLISHERS MDCCCCIX + + + + + Copyright, 1910, by THE GOODHUE CO. + + _All rights reserved_ + + + + +CONTENTS + + + CHAPTER I + + MAN AND NATURE + + The Conquest of Nature, p. 4--Man's use of Nature's gifts, p. + 6--Man the "tool-making animal," p. 7--Science and Civilization, + p. 8--Clothing and artificially heated dwellings of primitive man, + p. 10--Early domestication of animals, p. 11--Early development to + the time of gunpowder, p. 12--The coming of steam and electricity, + p. 15--Mechanical aids to the agriculturist, p. 19--The development + of scientific agriculture, p. 20--Difficulties of the early + manufacturer, p. 21--The development of modern manufacturing, p. + 24--The relation of work to human development, p. 25--The decline of + drudgery and the new era of labor-saving devices, p. 27. + + + CHAPTER II + + HOW WORK IS DONE + + Primitive man's use of the lever, p. 29--The use of the lever as + conceived by Archimedes, p. 21--Wheels and pulleys, p. 32--Other + means of transmitting power, p. 35--Inclined planes and derricks, p. + 37--The steam-scoop, p. 38--Friction, p. 39--Available sources of + energy, p. 41. + + + CHAPTER III + + THE ANIMAL MACHINE + + The oldest machine in existence, p. 43--The relation of muscle + to machinery, p. 44--How muscular energy is applied, p. 44--The + two types of muscles, p. 45--How the nerve-telegraph controls the + muscles, p. 47--The nature of muscular action, p. 49--Applications + of muscular energy, p. 52--The development of the knife and saw, p. + 53--The wheel and axle, p. 55--Modified levers, p. 57--Domesticated + animals, p. 59--Early application of horse-power, p. 60--The + horse-power as the standard of the world's work, p. 61. + + + CHAPTER IV + + THE WORK OF AIR AND WATER + + First use of sails for propelling boats, p. 62--The fire engine of + Ctesibius, p. 63--Suction and pressure as studied by the ancients, p. + 64--Studies of air pressure, p. 65--The striking demonstration of Von + Guericke, p. 66--The sailing chariot of Servinus, 1600 A.D., + p. 68--The development of the windmill, p. 69--The development of the + water-wheel, p. 70--The invention of the turbine, p. 72--Different + types of turbines, p. 73--Hydraulic power and its uses, p. 74--The + hydraulic elevator, p. 76--Recent water motors, p. 77. + + + CHAPTER V + + CAPTIVE MOLECULES: THE STORY OF THE STEAM ENGINE + + The development of the steam engine, p. 79--The manner in which + energy is generated by steam, p. 80--Action of cylinder and piston, + p. 81--Early attempts to utilize steam, p. 82--Beginnings of modern + discovery, p. 83--The "engine" of the Marquis of Worcester, p. + 84--Thomas Savery's steam pump, p. 85--Denis Papin invents the piston + engine, p. 88--Newcomen's improved engine, p. 89--The use of these + engines in collieries, p. 90--The wastefulness of such engines, p. + 92--The coming of James Watt, p. 93--Early experiments of Watt, p. + 95--The final success of Watt's experiments, p. 97--Some of his early + engines, p. 98--Rotary motion, p. 99--Watt's engine, "Old Bess," + p. 101--Final improvements and missed opportunities, p. 102--The + personality of James Watt, p. 107. + + + CHAPTER VI + + THE MASTER WORKER + + Improvements on Watt's engines, p. 110--Engines dispensing with the + walking beam, p. 111--The development of high-pressure engines, p. + 112--Advantages of the high-pressure engine, p. 114--How steam acts + in the high-pressure engine, p. 116--Compound engines, p. 117--Rotary + engines, p. 119--Turbine engines, p. 124--The _Turbinia_ and other + turbine boats, p. 125--The action of steam in the turbine engine, p. + 126--Advantages of the turbine engine, p. 127. + + + CHAPTER VII + + GAS AND OIL ENGINES + + Some early gas engines, p. 133--Dr. Stirling's hot-air engine, p. + 133--Ericsson's hot-air engines, p. 134--The first practical gas + engine, p. 135--The Otto gas engine, p. 136--Otto's improvement by + means of compressed gas, p. 138--The "Otto cycle," p. 139--Adaptation + of gas engines to automobiles, p. 140--Rapid increase in the use + of gas engines, p. 141--Defects of the older hot-air engines, p. + 145--Recent improvements and possibilities in the use of hot-air + engines, p. 146. + + + CHAPTER VIII + + THE SMALLEST WORKERS + + The relative size of atoms and electrons, p. 148--What is + electricity? p. 149--Franklin's one-fluid theory, p. 150--Modern + views, p. 153--Cathode rays and the X-ray, p. 156--How electricity + is developed, p. 159--The work of the dynamical current, p. + 162--Theories of electrical action, p. 165--Practical uses of + electricity, p. 168. + + + CHAPTER IX + + MAN'S NEWEST CO-LABORER: THE DYNAMO + + The mechanism of the dynamo, p. 173--The origin of the dynamo, p. + 176--The work of Ampere, Henry, and Faraday, p. 177--Perfecting the + dynamo, p. 178--A mysterious mechanism, p. 180--Curious relation + between magnetism and electricity as exemplified in the dynamo, p. + 182. + + + CHAPTER X + + NIAGARA IN HARNESS + + The volume of water at the falls, p. 184--The point at which + the falls are "harnessed," p. 185--Within the power-house, p. + 186--Penstocks and turbines, p. 188--A miraculous transformation + of energy, p. 189--Subterranean tail-races, p. 191--The effect on + the falls, p. 192--The transmission of power, p. 194--"Step-up" and + "step-down" transformers, p. 198. + + + CHAPTER XI + + THE BANISHMENT OF NIGHT + + Primitive torch and open lamp, p. 202--Tallow candle and perfected + lamp, p. 205--Gas lighting, p. 207--The incandescent gas mantle, p. + 208--Early gas mantles, p. 209--How the incandescent gas mantle is + made, p. 211--The introduction of acetylene gas, p. 212--Chemistry + of acetylene gas, p. 214--Practical gas-making, p. 215--The triumph + of electricity, p. 218--Davy and the first electric light, p. + 220--Helpful discoveries in electricity, p. 222--The Jablochkoff + candle, p. 223--Defects of the Jablochkoff candle, p. 225--The + improved arc light, p. 226--Edison and the incandescent lamp, p. + 228--Difficulties encountered in finding the proper material for + a practical filament, p. 230--"Parchmentized thread" filament, p. + 233--The tungsten lamp, p. 234--The mercury-vapor light of Peter + Cooper Hewitt, p. 236--Advantages and peculiarities of this light, p. + 240. + + + CHAPTER XII + + THE MINERAL DEPTHS + + Early mining methods, p. 242--Prospecting and locating mines, p. + 243--"Booming," p. 246--Conditions to be considered in mining, + p. 248--Dangerous gases in mines, p. 249--Artificial lights and + lighting, p. 251--Ventilation and drainage, p. 252--Electric + machinery in mining, p. 253--Electric drills, p. 254--Traction in + mining, p. 256--Various types of electric motors, p. 257--"Telphers," + p. 261--Electric mining pumps, p. 263--Some remarkable demonstrations + of durability of electric pumps, p. 265--Electricity in coal mining, + p. 266--Electric lighting in mines, p. 269. + + + CHAPTER XIII + + THE AGE OF STEEL + + Rapid growth of the iron industry in recent years, p. 271--The Lake + Superior mines, p. 272--Methods of mining, p. 273--"Open-pit" mining, + p. 274--Mining with the steam shovel, p. 276--From mine to furnace, + p. 278--Methods of transportation, p. 279--Vessels of special + construction, p. 281--The conversion of iron ore into iron and steel, + p. 283--Blast furnaces, p. 284--Poisonous gases and their effect + upon the workmen, p. 286--From pig iron to steel, p. 287--Modern + methods of producing pig iron, p. 288--The Bessemer converter, p. + 289--Sir Henry Bessemer, p. 291--The "Bessemer-Mushet" process, p. + 293--Open-hearth method, p. 294--Alloy steels, p. 295. + + + CHAPTER XIV + + SOME RECENT TRIUMPHS OF APPLIED SCIENCE + + The province of electro-chemistry, p. 298--Linking the laboratory + with the workshop, p. 299--Soda manufactories at Niagara Falls, p. + 300--Producing aluminum by the electrolytic process, p. 300--Old and + new methods compared, p. 301--Nitrogen from the air, p. 303--What + this discovery means to the food industries of the world, p. + 304--Prof. Birkeland's method, p. 307--Another method of nitrogen + fixation, p. 309--Cost of production, p. 312--Electrical energy, + p. 313--Production of high temperatures with the electric arc, p. + 314--The production of artificial diamonds by the explosion of + cordite, p. 315--Industrial problems of to-day and to-morrow, p. 316. + + + + +ILLUSTRATIONS + + + A PRIMITIVE USE OF THE ANIMAL MACHINE THAT IS + STILL IN VOGUE IN MANY EUROPEAN COUNTRIES _Frontispiece_ + + HORSE AND CATTLE POWER _Facing p._ 32 + + CRANES AND DERRICKS " 38 + + A BELGIAN MILK-WAGON " 56 + + TWO APPARATUSES FOR THE UTILIZATION OF ANIMAL + POWER " 60 + + WINDMILLS OF ANCIENT AND MODERN TYPES " 68 + + WATER WHEELS " 72 + + HYDRAULIC PRESS AND HYDRAULIC CAPSTAN " 76 + + THOMAS SAVERY'S STEAM ENGINE " 86 + + DIAGRAMS OF EARLY ATTEMPTS TO UTILIZE THE POWER + OF STEAM " 88 + + A MODEL OF THE NEWCOMEN ENGINE " 92 + + WATT'S EARLIEST TYPE OF PUMPING-ENGINE " 96 + + WATT'S ROTATIVE ENGINE " 100 + + JAMES WATT " 108 + + OLD IDEAS AND NEW APPLIED TO BOILER CONSTRUCTION " 114 + + COMPOUND ENGINES " 118 + + ROTARY ENGINES " 122 + + THE ORIGINAL PARSONS' TURBINE ENGINE AND THE RECORD-BREAKING + SHIP FOR WHICH IT IS RESPONSIBLE " 128 + + GAS AND OIL ENGINES " 136 + + AN ELECTRIC TRAIN AND THE DYNAMO THAT PROPELS IT " 174 + + WILDE'S SEPARATELY EXCITED DYNAMO " 178 + + THE EVOLUTION OF THE DYNAMO " 180 + + VIEW IN ONE OF THE POWER HOUSES AT NIAGARA " 186 + + ELECTRICAL TRANSFORMERS " 198 + + THOMAS A. EDISON AND THE DYNAMO THAT GENERATED + THE FIRST COMMERCIAL INCANDESCENT LIGHT " 228 + + A FLINT-AND-STEEL OUTFIT, AND A MINER'S STEEL MILL " 248 + + THE LOCOMOTIVE "PUFFING BILLY" AND A MODERN + COLLIERY TROLLEY " 258 + + + + +THE CONQUEST OF NATURE + + +In the earlier volumes we have been concerned with the growth of +knowledge. For the most part the scientific delvers whose efforts have +held our attention have been tacitly unmindful, or even explicitly +contemptuous, of the influence upon practical life of the phenomena to +the investigation of which they have devoted their lives. They were and +are obviously seekers of truth for the mere love of truth. + +But the phenomena of nature are not dissociated in fact, however +much we may attempt to localize and classify them. And so it chances +that even the most visionary devotee of abstract science is forever +being carried into fields of investigation trenching closely upon the +practicalities of every-day life. A Black investigating the laws of +heat is preparing the way explicitly, however unconsciously, for a Watt +with his perfected mechanism of the steam engine. + +Similarly a Davy working at the Royal Institution with his newly +invented batteries, and intent on the discovery of new elements and the +elucidation of new principles, is the direct forerunner of Jablochkoff, +Brush, and Edison with their commercial revolution in the production of +artificial light. + +Again Oersted and Faraday, earnestly seeking out the fundamental facts +as to the relations of electricity and magnetism, invent mechanisms +which, though they seem but laboratory toys, are the direct forerunners +of the modern dynamos that take so large a share in the world's work. + +In a word, all along the line there is the closest association +between what are commonly called the theoretical sciences and what +with only partial propriety are termed the applied sciences. The +linkage of one with the other must never be forgotten by anyone who +would truly apprehend the status of those practical sciences which +have revolutionized the civilization of the nineteenth and twentieth +centuries in its most manifest aspects. + +Nevertheless there is, to casual inspection, a somewhat radical +distinction between theoretical and practical aspects of science--just +as there are obvious differences between two sides of a shield. +And as the theoretical aspects of science have largely claimed our +attention hitherto, so its practical aspects will be explicitly +put forward in the pages that follow. In the present volume we are +concerned with those primitive applications of force through which +man early learned to add to his working efficiency, and with the +elaborate mechanisms--turbine wheels, steam engines, dynamos--through +which he has been enabled to multiply his powers until it is scarcely +exaggeration to say that he has made all Nature subservient to his +will. It is this view which justifies the title of the volume, which +might with equal propriety have been termed the Story of the World's +Work. + + + + +THE CONQUEST OF NATURE + + + + +I + +MAN AND NATURE + + +"Young men," said a wise physician in addressing a class of graduates +in medicine, "you are about to enter the battle of life. Note that I +say the 'battle' of life. Not a playground, but a battlefield is before +you. It is a hard contest--a battle royal. Make no mistake as to that. +Your studies here have furnished your equipment; now you must go forth +each to fight for himself." + +The same words might be said to every neophyte in whatever walk of +life. The pursuit of every trade, every profession is a battle--a +struggle for existence and for supremacy. Partly it is a battle against +fellow men; partly against the contending powers of Nature. The +physician meets rivalry from his brothers; but his chief battle is with +disease. In the creative and manufacturing fields which will chiefly +concern us in the following volumes, it is the powers of Nature that +furnish an ever-present antagonism. + +No stone can be lifted above another, to make the crudest wall or +dwelling, but Nature--represented by her power of gravitation--strives +at once to pull it down again. No structure is completed before the +elements are at work defacing it, preparing its slow but certain ruin. +Summer heat and winter cold expand and contract materials of every +kind; rain and wind wear and warp and twist; the oxygen of the air +gnaws into stone and iron alike;--in a word, all the elements are at +work undoing what man has accomplished. + + +THE STRUGGLE FOR EXISTENCE + +In the field of the agriculturist it is the same story. The earth which +brings forth its crop of unwholesome weeds so bountifully, resists +man's approaches when he strives to bring it under cultivation. Only by +the most careful attention can useful grains be made to grow where the +wildlings swarmed in profusion. Not only do wind and rain, blighting +heat and withering cold menace the crops; but weeds invade the fields, +the germs of fungoid pests lurk everywhere; and myriad insects attack +orchard and meadow and grain field in devastating legions. + +Similarly the beasts which were so rugged and resistant while in +the wild state, become tender and susceptible to disease when made +useful by domestication. Aforetime they roamed at large, braving every +temperature and thriving in all weathers. But now they must be housed +and cared for so tenderly that they become, as Thoreau said, the +keepers of men, rather than kept by men, so much more independent are +they than their alleged owners. Tender of constitution, domesticated +beasts must be housed, to protect them from the blasts in which of yore +their forebears revelled; and man must slave day in and day out to +prepare food to meet the requirements of their pampered appetites. + +He must struggle, too, to protect them from disease, and must care for +them in time of illness as sedulously as he cares for his own kith and +kin. Truly the ox is keeper of the man, and the seeming conquest that +man has wrought has cost him dear. + +But of course the story has another side. After all, Nature is not so +malevolent as at first glance she seems. She has opposed man at every +stage of his attempted progress; yet at the same time she has supplied +him all his weapons for waging war upon her. Her great power of +gravitation opposes every effort he makes; yet without that same power +he could do nothing--he could not walk or stay upon the earth even; and +no structure that he builds would hold in place for an instant. + +So, too, the wind that smites him and tears at his handiwork, may be +made to serve the purposes of turning his windmills and supplying him +with power. + +The water will serve a like purpose in turning his mills; and, changed +to steam with the aid of Nature's store of coal, will make his steam +engines and dynamos possible. Even the lightning he will harness and +make subject to his will in the telegraphic currents and dynamos. + +And in the fields, the grains which man struggles so arduously to +produce are after all no thing of his creating. They are only adopted +products of Nature, which he has striven to make serve his purpose by +growing them under artificial conditions. So, too, the domesticated +beasts are creatures that belong in the wilds and in distant lands. Man +has brought them, in defiance of Nature, to uncongenial climes, and +made them serve as workers and as food-suppliers where Nature alone +could not support them. Turn loose the cow and the horse to forage for +themselves here in the inhospitable north, and they would starve. They +survive because man helps them to combat the adverse conditions imposed +by Nature, yet no one of them could live for an hour were not the vital +capacities supplied by Nature still in control. + +Everywhere, then, it is the opposing of Nature, up to certain limits, +with the aid of Nature's own tools, that constitutes man's work in the +world. Just in proportion as he bends the elements to meet his needs, +transforms the plants and animals, defies and exceeds the limitations +of primeval Nature--just in proportion as he conquers Nature, in a +word, is he civilized. + +Barbaric man is called a child of Nature with full reason. He must +accept what Nature offers. But civilized man is the child grown to +adult stature, and able in a manner to control, to dominate--if you +please to conquer--the parent. + +If we were to seek the means by which developing man has gradually +achieved this conquest, we should find it in the single word, Tools; +that is to say, machines for utilizing the powers of Nature, and, as +it were, multiplying them for man's benefit. So unique is the capacity +that man exerts in this direction, that he has been described as +"the tool-making animal." The description is absolutely accurate; it +is inclusive and exclusive. No non-human animal makes any form of +implement to aid it in performing its daily work; and contrariwise +every human tribe, however low its stage of savagery, makes use of more +or less crude forms of implements. There must have been a time, to be +sure, when there existed a man so low in intelligence that he had not +put into execution the idea of making even the simplest tool. But the +period when such a man existed so vastly antedates all records that it +need not here concern us. For the purpose of classifying all existing +men, and all the tribes of men of which history and pre-historic +archaeology give us any record, the definition of man as the tool-making +animal is accurate and sufficient. + +At first thought it might seem that an equally comprehensive definition +might describe man as the working animal. But a moment's consideration +shows the fallacy of such a suggestion. Man is, to be sure, the animal +that works effectively, thanks to the implements with which he has +learned to provide himself; but he shares with all animate creatures +the task of laboring for his daily necessities. This is indeed a +work-a-day world, and no creature can live in it without taking +its share in that perpetual conflict which bodily necessities make +imperative. Most lower animals confine their work to the mere securing +of food, and to the construction of rude habitations. Some, indeed, +go a step farther and lay up stores of food, in chance burrows or +hollow trees; a few even manufacture relatively artistic and highly +effective receptacles, as illustrated by the honeycomb made by the +bees and their allies. Again, certain animals, of which the birds +are the best representatives, construct temporary structures for the +purpose of rearing their young that attain a relatively high degree of +artistic perfection. The Baltimore oriole weaves a cloth of vegetable +fibre that is certainly a wonderful texture to be made with the aid of +claws and bill alone. It may be doubted whether human hands, unaided by +implements, could duplicate it. But it is crude enough compared with +even the coarsest cloth which barbaric races manufacture with the aid +of implements. + +So it is with any comparison of animal work with the work of man, in +whatever field. The crudest human endeavor is superior to the best +non-human efforts; and the explanation is found always in the fact that +the ingenuity of man has enabled him to find artificial aids that add +to his power of manipulation. So large a share have these artificial +aids taken in man's evolution, that it has long been customary, in +studying the development of civilization, to make the use of various +types of implements a test of varying stages of human progress. + + +SCIENCE AND CIVILIZATION + +The student of primitive life assures us, basing his statements on the +archaeological records, that there was a time when the most advanced of +mankind had no tools made of better material than chipped stone. By +common consent that time is spoken of as the Rough Stone Age. + +We are told that then in the course of immeasurable centuries man +learned to polish his stone implements, doubtless by rubbing them +against another stone, or perhaps with the aid of sand, thus producing +a new type of implement which has given its name to the Age of Smooth +or Polished Stone. + +Then after other long centuries came a time when man had learned +to smelt the softer metals, and the new civilization which now +supplanted the old, and, thanks to the new implements, advanced upon it +immeasurably, is called the Age of Bronze. + +At last man learned to accomplish the wonderful feat of smelting the +intractable metal, iron, and in so doing produced implements harder, +sharper, and cheaper than his implements of bronze; and when this +crowning feat had been accomplished, the Age of Iron was ushered in. + +By common consent, students of the history of the evolution of society +accept these successive ages, each designated by the type of implements +with which the world's work was accomplished, as representing real and +definite stages of human progress, and as needing no better definition +than that supplied by the different types of implements. + +Could the archaeologist trace the stream of human progress still farther +back toward its source, he would find doubtless that there were several +great epochal inventions preceding the time of the Rough Stone Age, +each of which was in its way as definitive and as revolutionary in +its effects upon society, as these later inventions which we have just +named. To attempt to define them clearly is to enter the field of +uncertainty, but two or three conjectures may be hazarded that cannot +be very wide of the truth. + +It is clear, for example, that if we go back in imagination to the very +remotest ancestors of man that can be called human, we must suppose a +vast and revolutionary stage of progress to have been ushered in by the +first race of men that learned to make habitual use of the simplest +implement, such as a mere club. When man had learned to wield a club +and to throw a stone, and to use a stone held in the hand to break the +shell of a nut, he had attained a stage of culture which augured great +things for the future. Out of the idea of wielded club and hurled stone +were to grow in time the ideas of hammer and axe and spear and arrow. + +Then there came a time--no one dare guess how many thousands of years +later--when man learned to cover his body with the skin of an animal, +and thus to become in a measure freed from the thraldom of the weather. +He completed his enfranchisement by learning to avail himself of the +heat provided by an artificial fire. Equipped with these two marvelous +inventions he was able to extend the hitherto narrow bounds of his +dwelling-place, passing northward to the regions which at an earlier +stage of his development he dared not penetrate. Under stress of more +exhilarating climatic conditions, he developed new ideals and learned +to overcome new difficulties; developing both a material civilization +and the advanced mentality that is its counterpart, as he doubtless +never would have done had he remained subject to the more pampering +conditions of the tropics. + +The most important, perhaps, of the new things which he was taught +by the seemingly adverse conditions of an inhospitable climate, was +to provide for the needs of a wandering life and of varying seasons +by domesticating animals that could afford him an ever-present food +supply. In so doing he ceased to be a mere fisher and hunter, and +became a herdsman. One other step, and he had conceived the idea of +providing for himself a supply of vegetable foods, to take the place +of that which nature had provided so bountifully in his old home in +the tropics. When this idea was put into execution man became an +agriculturist, and had entered upon the high road to civilization. + +All these stages of progress had been entered upon prior to the time of +which the oldest known remains of the cave-dweller give us knowledge. +It were idle to conjecture the precise sequence in which these earliest +steps toward civilization were taken, and even more idle to conjecture +the length of time which elapsed between one step and its successor. +But all questions of precise sequence aside, it is clear that here were +four or five great ages succeeding one to another, that marked the +onward and upward progress of our primeval ancestor before he achieved +the stage of development that enabled him to leave permanent records of +his existence. And--what is particularly significant from our present +standpoint--it is equally clear that each of the great ages thus +vaguely outlined was dependent upon an achievement or an invention +that facilitated the carrying out of that scheme of never-ending work +which from first to last has been man's portion. How to labor more +efficiently, more productively; how to produce more of the necessaries +and of the luxuries that man's physical and mental being demands, +with less expenditure of toil--that from first to last has been the +ever-insistent problem. And the answer has been found always through +the development of some new species of mechanism, some new labor-saving +device, some ingenious manipulation of the powers of Nature. + +If, turning from the hypothetical period of our primitive ancestor, +we consider the sweep of secure and relatively recent history, we +shall find that precisely the same thing holds. If we contrast the +civilization of Old Egypt and Babylonia--the oldest civilizations of +which we have any secure record--with the civilization of to-day, we +shall find that the differences between the one and the other are such +as are due to new and improved methods of accomplishing the world's +work. + +Indeed, if we view the subject carefully, it will become more and +more evident that the only real progress that the historic period has +to show is such as has grown directly from the development of new +mechanical inventions. The more we study the ancient civilizations +the more we shall be struck with their marvelous resemblance, as +regards mental life, to the civilization of to-day. In their moral +and spiritual ideals, the ancient Egyptians were as brothers to the +modern Europeans. In philosophy, in art, in literature, the Age of +Pericles established standards that still remain unexcelled. In all the +subtleties of thought, we feel that the Greeks had reached intellectual +bounds that we have not been able to extend. + +But when, on the other hand, we consider the material civilization of +the two epochs, we find contrasts that are altogether startling. The +little world of the Greeks nestled about the Mediterranean, bounded +on every side at a distance of a few hundred leagues by a _terra +incognita_. The philosophers who had reached the confines of the +field of thought, had but the narrowest knowledge of the geography of +our globe. They traversed at best a few petty miles of its surface +on foot or in carts; and they navigated the Mediterranean Sea, or at +most coasted out a little way beyond the Pillars of Hercules in boats +chiefly propelled by oars. By dint of great industry they produced a +really astonishing number of books, but the production of each one was +a long and laborious task, and the aggregate number indited during +the Age of Pericles in all the world was perhaps not greater than an +afternoon's output of a modern printing press. + +In a word, these men of the classical period of antiquity, great as +were their mental, artistic, and moral achievements, were as children +in those matters of practical mechanics upon which the outward +evidences of civilization depend. Should we find a race of people +to-day in some hitherto unexplored portion of the earth--did such +unexplored portions still exist--living a life comparable to that +of the Age of Pericles, we should marvel no doubt at their artistic +achievements, while at the same time regarding them as scarcely better +than barbarians. Indeed this is more than unsupported hypothesis; +for has it not been difficult for the Western world to admit the +truly civilized condition of the Chinese, simply because that highly +intellectual race of Orientals has not kept abreast of the Occidental +changes in applied mechanics? Say what we will, this is the standard +which we of the Western world apply as the test of civilization. + +If, sweeping over in retrospect the history of the world since the time +when the Egyptian and Babylonian civilizations were at their height, +we attempt some such classification of the stages of progress as that +which we a moment ago applied to pre-historic times, we shall be led to +some rather startling conclusions. In the broadest view, it will appear +that the age which ushered in the historic period continued unbroken +by the advance of any great revolutionary invention throughout the +long centuries of pre-Christian antiquity, and well into the so-called +Middle Ages of our newer era. Then came the invention of gunpowder, or +at least its introduction to the Western world--since the Chinaman here +lays claim to vague centuries of precedence. Following hard upon the +introduction of gunpowder, with its capacity to add to the destructive +efficiency of man's most sinister form of labor, came a mechanism no +less epoch-making in a far different field--the printing press. + +But even these inventions, great as was their influence upon the +progress of civilization, can scarcely be considered, it seems to me, +as taking rank with the great epochal discoveries that gave their +names to the preceding ages. Nor can any invention of the sixteenth +or seventeenth century be hailed as really ushering in a new era. The +invention for which that honor was reserved was a development of the +eighteenth century; and did not come fully to its heritage until the +early days of the nineteenth century. The invention was the application +of steam to the purposes of mechanics. When this application was made, +as wide a gap was crossed as that which separated the Stone Age from +the Age of Metal; then the epoch in which the world was living when +history begins was brought to a close, and a new era, the Age of Steam, +was ushered in. + +Scarcely had the world begun to adjust itself to the new conditions of +the Age of Steam, when yet another power was made subservient to man's +needs, and the Age of Steam was supplemented, not to say supplanted, by +the Age of Electricity. Of course the new progressive movements did not +necessarily imply elimination of old conditions; they imply merely the +subordination of old powers to newer and better ones. Stone implements +by no means ceased to have utility at once when metal implements came +into vogue. Bronze long held its own against iron, and still has its +utility. And iron itself finds but an added sphere of usefulness in the +Age of Steam and Electricity. + +All great changes are relatively slow. It is only as we look back upon +them and view them in perspective that they seem cataclysmic. Gunpowder +did not at once supplant the crossbow, and the cannon was long held +to be inferior to the catapult. The printed book did not instantly +make its way against the work of the scribe. Neither did the steam +engine immediately supplant water power and the direct application of +human labor. But in each case the new invention virtually rang the +death knell of the old method from the hour of its inauguration, and +the end was no less sure because it was delayed. And it requires no +great powers of divination to foretell that in the coming age, the +electric dynamo driven by water power may take the place of the steam +engine. The Age of Steam may pass, with only at most a few generations +of domination. And it is within the possibilities that the Age of +Electricity will scarcely come into its own before it may be displaced +by an Age of Radio-Activity. To press that point, however, would be to +enter the field of prophecy, which is no part of my present purpose. + +All that I have wished to point out is that for some thousands of +years after man learned to make implements of iron, the industrial +world and the human civilization that depends upon it, pursued a +relatively static course, like a broad, sluggish current, with no +new revolutionary discovery to impel it into new channels; and that +then one revolutionary discovery succeeded another with bewildering +suddenness, so that we of the early days of the twentieth century +are farther removed, in an industrial way, from our forerunners of +two hundred years ago, than those children of the eighteenth century +were from the earliest civilization that ever developed on our globe. +Indeed, this startling contrast would still hold true, were we to +consider the newest era as compassing only the period of a single +life. There are men living to-day who were born in that epoch when +the steam engine was for the first time used to turn the wheels of +factories. There are many men who can well remember the first practical +application of steam to railway traffic. Hosts of men can remember when +the first commercial message was transmitted by electricity along a +wire. Even middle-aged men recall the first cable message that linked +the old world with the new. And the application of the dynamo to the +purposes of the world's work is an affair of but yesterday. + +The historian of the future, casting his eye back across the long +perspective of history, will find civilized man pursuing an even and +unbroken course across the ages from the time of the pyramids of Egypt +to about the time of the French Revolution. There will be no dearth +of incident to claim his attention in the way of wars and conquests, +and changing creeds, and the rise and fall of nations, each pursuing +virtually the same course of growth and decay as all the others. But +when he comes to the close of the eighteenth century, it will not be +the social paroxysm of a nation, or the meteoric career of a Napoleon +that will claim his attention so much as the introduction of that new +method of utilizing the powers of Nature which found its expression in +the mechanism called the steam engine. + +If the name of any individual stands out as the great and memorable one +of that epoch of transition, at which the static current of previous +civilization changed suddenly to a Niagara-current of progress, it will +be the name of the great scientific inventor, rather than that of the +great military conqueror--the name of James Watt, rather than that of +Napoleon. + +The military conqueror had his day of surpassing glory and departed, +to leave the world only a little worse than he found it. But the +mechanical inventor left a heritage that was to add day by day to the +wealth and happiness of humanity, supplying millions of artificial +hands, and making possible such beneficent improvements as no previous +age had dreamed of. Tasks that human hands had performed slowly, +laboriously, and inadequately, were now to be performed swiftly, with +ease, and well by the artificial hands provided with the aid of the new +power. Where carts drawn by horses had toiled slowly across the land, +and ships driven by the wind had drifted slowly through the waters, +massive trains of cars were to hurtle to the four corners of the earth +with inconceivable speed, and floating palaces were to course the +waters with almost equal defiance to the limitations of time and space. + +And then there came that still weirder conquest of time and space, +wrought by the electric current. The moment when man first spoke with +man from continent to continent in defiance of the oceans, marked +the dawning of that larger day when all mankind shall constitute one +brotherhood and all peoples but a single nation. Within a half century +the sun of that new day has risen well above the horizon, and far +sooner than even the optimist of to-day dare predict with certainty, it +seems destined to reach its zenith. + +But here again we verge upon the dangerous field of prophecy. Let +us turn from it and cast an eye back across the most wonderful of +centuries, contrasting the conditions of to-day in each of a half-dozen +fields of the world's work, with the conditions that obtained at the +close of the eighteenth century. Such a brief survey will show us +perhaps more vividly than we could otherwise be shown, how vast has +been the progress, how marvelous the development of civilization, in +the short decades that have elapsed since the coming of the Age of +Steam. + +Let us pay heed first to the world of the agriculturist. Could we +turn back to the days of our grandparents, we should find farming a +very different employment from what it is to-day. For the most part +the farmer operated but a few small fields; if he had thirty or forty +acres of ploughed land, he found ample employment for his capacities. +He ploughed his fields with the aid of either a yoke of oxen or a +team of horses; he sowed his grain by hand; he cultivated his corn +with a hoe; he reaped his oats and wheat with a cradle--a device but +one step removed from a sickle; he threshed his grain with a flail; +he ground such portion of it as he needed for his own use with the +aid of water power at a neighboring mill; and such portion of it as +he sold was transported to market, be it far or near, in wagons that +compassed twenty or thirty miles a day at best. As regards live stock, +each farmer raised a few cattle, sheep, and hogs, and butchered them +to supply his own needs, selling the residue to a local dealer who +supplied the non-agricultural portion of the neighborhood. Any live +stock intended for a distant market was driven on foot across the +country to its destination. Each town and city, therefore, drew almost +exclusively for its supply from the immediately surrounding country. + +To-day the small farmer has become almost obsolete, and the farms +of the eastern states that were the nation's chief source of supply +a century ago are largely allowed to lie fallow, it being no longer +possible to cultivate them profitably in competition with the rich +farm lands of the middle west. In that new home of agriculture, the +farm that does not comprise two or three hundred acres is considered +small; and large farms are those that number their acres by thousands. +The soil is turned by steam ploughs; the grain is sown with mechanical +seeders and planters; the corn is cultivated with a horse-drawn +machine, having blades that do the work of a dozen men; harvesters +drawn by three or four horses sweep over the fields and leave the grain +mechanically tied in bundles; the steam thresher places the grain in +sacks by hundreds of bushels a day; and this grain is hurried off in +steam cars to distant mills and yet more distant markets. + +Meantime the raising of live stock has become a special department, +with which the farmer who deals in cereals often has no concern. +The cattle roam over vast pastures and are herded in the winter for +fattening in great droves, and protected from the cold in barns +that, when contrasted with the sheds of the old-time farmer, seem +almost palatial. When in marketable condition, cattle are no longer +slaughtered at the farm, but are transported in cars to one of the +few great centres, chief of which are the stock yards of Chicago and +of Kansas City. At these centres, slaughter houses and meat-packing +houses of stupendous magnitude have been developed, capable of +handling millions of animals in a year. From these centres the meat is +transported in refrigerator cars to the seaboards, and in refrigerator +ships to all parts of the world. Beef that grew on the ranges of the +far west may thus be offered for sale in the markets of New England +villages, at a price that prohibits local competition. + +A more radical metamorphosis in agricultural conditions than all this +implies could not well be conceived. And when we recall once more that +the agricultural conditions that obtained at the beginning of the +nineteenth century were closely similar to those that obtained in each +successive age for a hundred preceding centuries, we shall gain a vivid +idea of the revolutionizing effects of new methods of work in the most +important of industries. It is little wonder that in this short time +the world has not solved to the satisfaction of the economists all the +new problems thus so suddenly developed. + +Turn now to the manufacturing world. In the days of our +great-grandparents almost every household was a miniature factory where +cotton and wool were spun and the products were woven into cloth. +It was not till toward the close of the eighteenth century--just at +the time when Watt was perfecting the steam engine--that Arkwright +developed the spinning-frame, and his successors elaborated the +machinery that made possible the manufacture of cloth in wholesale +quantities; and the nineteenth century was well under way before +the household production of cloth had been entirely supplanted by +factory production. It is nothing less than pitiful to contemplate in +imagination our great-great-grandmothers--and all their forebears of +the long centuries--drudging away day after day, year in and year out, +at the ceaseless task of spinning and weaving--only to produce, as the +output of a lifetime of labor, a quantity of cloth equivalent perhaps +to what our perfected machine, driven by steam, and manipulated by +a factory girl, produces each working hour of every day. Similarly, +carpets and quilts were of home manufacture; so were coats and dresses; +and shoes were at most the product of the local shoemaker around the +corner. + +In the kitchen, food was cooked over the coals of a great fireplace +or in the brick oven connected with that fireplace. Meat was supplied +from a neighboring farm; eggs were the product of the housewife's own +poultry yard; the son or daughter of the farmer milked the cow and +drove her to and from the pasture; the milk was "set" in pans in the +cellar--on a swinging shelf, preferably, to make it inaccessible to the +rats; and twice a week the cream was made into butter in a primitive +churn, the dasher of which was operated by the vigorous arm of the +housewife herself, or by the unwilling arms of some one of her numerous +progeny. + +To give variety to the dietary, fruits grown in the local garden +or orchard were preserved, each in its season, by the industrious +housewife, and stored away in the capacious cellar; where also might be +found the supply of home-grown potatoes, turnips, carrots, parsnips, +and cabbages to provide for the needs of the winter. Fuel to supply +the household needs, both for cooking and heating, was cut in the +neighboring woodland, and carefully corded in the door-yard, where it +provided most uncongenial employment for the youth of the family after +school hours and of a Saturday afternoon. + +The ashes produced when this wood was burned in the various fireplaces, +were not wasted, but were carefully deposited in barrels, from which +in due course lye was extracted by the simple process of pouring water +over the contents of the barrel. Meantime scraps of fat from the table +were collected throughout the winter and preserved with equal care; and +in due course on some leisure day in the springtime--heaven knows how a +leisure day was ever found in such a scheme of domestic economy!--the +lye drawn from the ash-barrels and the scraps of fat were put into a +gigantic kettle, underneath which a fire was kindled; with the result +that ultimately a supply of soft soap was provided the housewife, with +which her entire establishment, progeny included, could be kept in a +state of relative cleanness. + +The reader of these pages has but to cast his eye about him in the +household in which he lives, and contrast the conditions just depicted +with those of his every-day life, to realize what change has come over +the aspects of household economy in the course of a short century. +Nor need he be told in each of the various departments of which the +activities are here outlined, that the changes which he observes have +been due to the application of machinery in all the essential lines of +work in question. We need not pause to detail the multitudinous devices +for the economy of household labor which owe their origin to the same +agency. There still remains, to be sure, enough of drudgery in the task +of the housewife; yet her most strenuous day seems a mere playtime in +comparison with the average day of her maternal forebear of three or +four generations ago. + +But we must not here pause for further outlines of a subject which it +is the purpose of this and succeeding volumes to explicate in detail. +All our succeeding chapters will but make it more clear how marvelous +are the elaborations of method and of mechanism through which the +world's work of to-day is accomplished. We shall consider first the +mechanical principles that underlie work in general, passing on to +some of the principal methods of application through which the powers +of Nature are made available. We shall then take up in succession +the different fields of industry. We shall ask how the work of the +agriculturist is done in the modern world; how the multitudinous lines +of manufacture are carried out; how transportation is effected; we +shall examine the _modus operandi_ of the transmission of ideas; we +shall even consider that destructive form of labor which manifests +itself in the production of mechanisms of warfare. As we follow out the +stories of the all-essential industries we shall be led to realize more +fully perhaps than we have done before, the meaning of work in its +relations to human development; and in particular the meaning of modern +work, as carried out with the aid of modern mechanical contrivances, in +its relations to modern civilization. + +The full force of these relations may best be permitted to unfold +itself as the story proceeds. There is, however, one fundamental +principle which I would ask the reader to bear constantly in mind, as +an aid to the full appreciation of the importance of our subject. It +is that in considering the output of the worker we have constantly to +do with one form or another of property, and that property is the very +foundation-stone of civilization. "It is impossible," says Morgan, +in his work on Ancient Society, "to overestimate the influence of +property in the civilization of mankind. It was the power that brought +the Aryan and Semitic nations out of barbarism into civilization. +The growth of the idea of property in the human mind commenced in +feebleness and ended in becoming its master passion. Governments and +laws are instituted with primary reference to its creation, protection, +and enjoyment. It introduced human slavery in its production; and, +after the experience of several thousand years, it caused the +abolition of slavery upon the discovery that the freeman was a better +property-making machine." If, then, we recall that without labor there +is no property, we shall be in an attitude of mind to appreciate the +importance of our subject; we shall realize, somewhat beyond the bounds +of its more tangible and sordid relations, the essential dignity, the +fundamental importance--in a word, the true meaning--of Work. + +Undoubtedly there is a modern tendency to accept this view of the +dignity of physical labor. At any rate, we differ from the savage in +thinking it more fitting that man should toil than that his wife should +labor to support him--though it cannot be denied that even now the +number of physical toilers among women greatly exceeds the number of +such toilers among men. But in whatever measure we admit this attitude +of mind, there can be no question that it is exclusively a modern +attitude. Time out of mind, physical labor has been distasteful to +mankind, and it is a later development of philosophy that appreciates +the beneficence of the task so little relished. + +The barbarian forces his wife to do most of the work, and glories in +his own freedom. Early civilization kept conquered foes in thraldom, +developing an hereditary body of slaves, whose function it was to do +the physical work. + +The Hebrew explained the necessity for labor as a curse imposed upon +Father Adam and Mother Eve. Plato and Aristotle, voicing the spirit of +the Greeks, considered manual toil as degrading. + +To-day we hear much of the dignity of labor; but if we would avoid cant +we must admit that now--scarcely less than in all the olden days--the +physical toiler is such because he cannot help himself. Few indeed are +the manual laborers who know any other means of getting their daily +bread than that which they employ. The most strenuous advocates of the +strenuous life are not themselves tillers of the soil or workers in +factories or machine shops. + +The farm youth of intelligence does not remain a farmer; he goes to +the city, and we find him presently at the head of a railroad or a +bank, or practising law or medicine. The more intelligent laborer +becomes finally a foreman, and no longer handles the axe or sledge. We +should think it grotesque were we to see a man of intellectual power +obstinately following a pursuit that cost him habitual physical toil. +When now and then a Tolstoi offers an exception to this rule, we feel +that he is at least eccentric; and we may be excused the doubt whether +he would follow the manual task cheerfully if he did not know that he +could at any moment abandon it. It is because he knows that the world +understands him to be only a dilettante that he rejoices in his task. + +After all, then, judged by the modern practice, rather than by the +philosopher's precept, the old Hebrew and Greek ideas were not so +far wrong. Using the poetical language which was so native to them, +it might be said that the necessity for physical labor is a curse--a +disgrace. + +A partial explanation of this may be found in the fact that the most +uncongenial tasks are also the worst paid, while the congenial tasks +command the high emoluments. Generally speaking there is no distinction +between one laborer and another in the same field--except where the +eminently fair method of piece work can be employed. Even the skilled +laborer is usually paid by the day, and the amount he is to receive is +commonly fixed by a Union regardless of his efficiency as compared with +other laborers of the same class. And there is no possibility of his +receiving any such sums as the man who plans the work, but does nothing +with his own hands. + +It has always been so. Just as "those who think must govern those that +toil," so the thinker must command the high reward. Partly this is +because man, considered as a mere toiler, is so relatively inefficient +a worker. When he strives to work with his hands, his effort is but a +pitiful one; he can by no possibility compete (as regards mere quantity +of labor) with the ox and the horse. He is impatient of his own puerile +efforts. It is only when he brings the products of ingenuity to his +aid that he is able to show his superiority, and to justify his own +egotism. So it is that in every age he has striven to find means of +adding to his feeble powers of body through the use of his relatively +gigantic powers of mind. And in proportion as he thus is able to "make +his head work for his hands" as the saying goes, he verges toward the +heights of civilization. To accomplish this more and more fully has +ever been the task of science as applied to the industries. + +It will be our object in the ensuing chapters to inquire how far +science has accomplished the protean task thus set for it. We shall see +that much has been done; but that much still remains to be done. In +proportion as the problems are unsolved, science is reproached for its +shortcomings--and stimulated to new efforts. + +In proportion as labor has been minimized and production increased--in +just that proportion has science justified itself; and in the same +proportion has the Conquest of Nature been carried toward completion. + + + + +II + +HOW WORK IS DONE + + +The word energy implies capacity to do work. Work, considered in +the abstract, consists in the moving of particles of matter against +some opposing force, or in aid of previously acting forces. In the +last analysis, all energy manifests itself either as a push or as a +pull. But there is a modification of push and pull which is familiar +to everyone in practice under the name of prying. Illustrations may +be seen on every hand, as when a workman pries up a stone, or when +a housewife pries up a tack with the aid of a hammer. The principle +here involved is that of the lever--a principle which in its various +practical modifications is everywhere utilized in mechanics. Very +seldom indeed is the direct push or pull utilized; since the modified +push or pull, as represented by the lever in its various modifications +of pulley, ratchet-wheel, and the like, has long been known to meet the +needs of practical mechanics. + +The very earliest primitive man who came to use any implement whatever, +though it were only a broken stick, must have discovered the essential +principle of the lever, though it is hardly necessary to add that he +did not know his discovery by any such high-sounding title. What he +did know, from practical experience, was that with the aid of a stick +he could pry up stones or logs that were much too heavy to be lifted +without this aid. + +This practical knowledge no doubt sufficed for a vast number of +generations of men who used the lever habitually, without making +specific study of the relations between the force expended, the lengths +of the two ends of the lever, and the weight raised. Such specific +experiments were made, however, more than two thousand years ago by the +famous Syracusan, Archimedes. He discovered--or if some one else had +discovered it before him, he at least recorded and so gains the credit +of discovery--the specific laws of the lever, and he also pointed out +that levers, all acting on the same principle, may be different as to +their practical mechanism in three ways. + +First, the fulcrum may lie between the power and the weight, as in the +case of the balance with which we were just experimenting. This is +called a lever of the first class, and familiar illustrations of it are +furnished by the poker, steelyard, or a pair of scissors. The so-called +extensor muscles of the body--those for example, that cause the arm to +extend--act on the bones in such a way as to make them levers of this +first class. + +The second type of lever is that in which the weight lies between the +force and the fulcrum, as illustrated by the wheelbarrow, or by an +ordinary door. + +In the third class of levers the power is applied between weight and +fulcrum, as illustrated by a pair of tongs, the treadle of a lathe, +or by the flexor muscles of the arm, operating upon the bones of the +forearm. + +But in each case, let it be repeated, precisely the same principles are +involved, and the same simple law of the relations between positions +of power, weight, and fulcrum are maintained. The practical result +is always that a weight of indefinite size may be moved by a power +indefinitely long. If one arm of the lever is ten times as long as the +other, the power of one pound will lift or balance a ten-pound weight; +if the one arm is a thousand times as long as the other the power of +one pound will lift or balance a thousand pounds. If the long arm of +the lever could be made some millions of miles in length, the power +that a man could exert would balance the earth. + +How fully Archimedes realized the possibilities of the lever is +illustrated in the classical remark attributed to him, that, had he +but a fulcrum on which to place his lever, he could move the world. As +otherwise quoted, the remark of Archimedes was that, had he a place +on which to stand, he could move the world, a remark which even more +than the other illustrates the full and acute appreciation of the +laws of motion; since, as we have already pointed out, action and +reaction being equal, the most infinitesimal push must be considered as +disturbing even the largest body. + +Tremendous as is the pull of gravity by which the earth is held in +its orbit, yet the smallest push, steadily applied from the direction +of the sun, would suffice ultimately to disturb the stability of our +earth's motion, and to push it gradually through a spiral course +farther and farther away from its present line of elliptical flight. +Or if, on the other hand, the persistent force were applied from the +side opposite the sun, it would suffice ultimately to carry the earth +in a spiral course until it plunged into the sun itself. Indeed it has +been questioned in modern times whether it may not be possible that +precisely this latter effect is gradually being accomplished, through +the action of meteorites, some millions of which fall out of space into +the earth's atmosphere every day. If these meteorites were uniformly +distributed through space and flying in every direction, the fact that +the sun screens the earth from a certain number of them, would make +the average number falling on the side away from the sun greater, and +thus would in the course of ages produce the result just suggested. All +that could save our earth from such a fate would be the operation of +some counteracting force. Such a counteracting force is perhaps found +in solar radiation. It may be added that the distribution of meteorites +in space is probably too irregular to make their influence on the earth +predicable in the present state of science; but the principle involved +is no less sure. + + +WHEELS AND PULLEYS + +Returning from such theoretical applications of the principle of +motion, to the practicalities of every-day mechanisms, we must note +some of the applications through which the principle of the lever is +made available. Of these some of the most familiar are wheels, and the +various modifications of wheels utilized in pulleys and in cogged +and bevelled gearings. A moment's reflection will make it clear that +the wheel is a lever of the first class, of which the axle constitutes +the fulcrum. The spokes of the wheel being of equal length, weights +and forces applied to opposite ends of any diameter are, of course, +in equilibrium. It follows that when a wheel is adjusted so that a +rope may be run about it, constituting a simple pulley, a mechanism is +developed which gives no gain in power, but only enables the operator +to change the direction of application of power. In other words, pound +weights at either end of a rope passed about a simple pulley are +in equilibrium and will balance each other, and move through equal +distances in opposite directions. + +[Illustration: HORSE AND CATTLE POWER. + +The large picture shows a model of a familiar mechanism for utilizing +horse power. The small picture shows a similar apparatus in actual +operation, actuated by cattle, in contemporary Brittany.] + +If, however, two or more pulley wheels are connected, to make the +familiar apparatus of a compound pulley, we have accomplished by an +interesting mechanism a virtual application of the principle of the +long and short arm of the lever, and the relations between the weight +at the loose end of the rope and the weight attached to the block +which constitutes virtually the short end of the lever, may be varied +indefinitely, according to the number of pulley-wheels that are used. +A pound weight may be made to balance a thousand-pound weight; but, +of course, our familiar principle still holding, the pound weight +must move through a distance of a thousand feet in order to move +a thousand-pound weight through a distance of one foot. Familiar +illustrations of the application of this principle may be seen on every +hand; as when, for example, a piano or a safe is raised to the upper +window of a building by the efforts of men whose power, if directly +expended, would be altogether inefficient to stir the weight. + +The pulley was doubtless invented at a much later stage of human +progress than the simple lever. It was, however, well known to the +ancients. It was probably brought to its highest state of practical +perfection by Archimedes, whose experiments are famous through the +narrative of Plutarch. It will be recalled that Archimedes amazed +the Syracusan general by constructing an apparatus that enabled +him, sitting on shore, to drag a ponderous galley from the water. +Plutarch does not describe in detail the apparatus with which this +was accomplished, but it is obvious from his description of what took +place, that it must have been a system of pulleys. + +It will be observed that the pulley is a mechanism that enables the +user to transmit power to a distance. But this indeed is true in a +certain sense of every form of lever. Numberless other contrivances +are in use by which power is transmitted, through utilization of the +same principle of the lever, either through a short or through a +relatively long distance. A familiar illustration is the windlass, +which consists of a cylinder rotating on an axis propelled by a long +handle, a rope being wound about the cylinder. This is a lever of +the second class, the axis acting as fulcrum, and the rope operating +about the circumference of the cylinder typifying the weight, which +may be actually at a considerable distance, as in the case of the +old-fashioned well with its windlass and bucket, or of the simple form +of derrick sometimes called a sheerlegs. + + +OTHER MEANS OF TRANSMITTING POWER + +Power is transmitted directly from one part of a machine to another, +in the case of a great variety of machines, with the aid of cogged +gearing wheels of various sizes. The modifications of detail in the +application of these wheels may be almost infinite, but the principle +involved is always the same. The case of two wheels toothed about +the circumference, the teeth of the two wheels fitting into one +another, illustrates the principle involved. A consideration of the +mechanism will show that here we have virtually a lever fixed at both +ends, represented by the radii of the two wheels, the power being +applied through the axle of one wheel, and the weight, for purposes +of calculation, being represented by the pressure of the teeth of one +wheel upon those of the other. So this becomes a lever of the second +class, and the relations of power between the two wheels are easily +calculated from the relative lengths of the radii. If, for example, +one radius is twice as long as the other, the transmission of power +will be, obviously, in the proportion of two to one, and meantime the +distance traversed by the circumference of one wheel will be twice as +great as that traversed by the other. + +A modification of the toothed wheel is furnished by wheels which may be +separated by a considerable distance, and the circumferences of which +are connected by a belt or by a chain. The principle of action here +is precisely the same, the belt or chain serving merely as a means of +lengthening out our lever. The relative sizes of the wheels, and not +the length of the belt or chain, is the determining factor as regards +the relative forces required to make the wheels revolve. + +It is obvious all along, of course, since action and reaction +are equal, that all of the relations in question are reciprocal. +When, for example, we speak of a pound weight on the long end of a +lever balancing a ten-pound weight on the short end, it is equally +appropriate to speak of the ten-pound weight as balancing the one-pound +weight. Similarly, when power is applied to the lever, it may be +applied at either end. Ordinarily, to be sure, the power is applied +at the long end, since the object is to lift the heavy weight; but in +complicated machinery it quite as often happens that these conditions +are reversed, and then it becomes desirable to apply strong power to +the short end of the lever, in order that the relatively small weight +may be carried through the long distance. In the inter-relations of +gearing wheels, such conditions very frequently obtain, practical ends +being met by a series of wheels of different sizes. But the single +rule, already so often outlined, everywhere holds--wherever there is +gain of power there is loss of distance, and we can gain distance only +by losing power. The words gain and loss in this application are in a +sense misnomers, since, as we have already seen, gain and loss are only +apparent, but their convenience of application is obvious. + +A familiar case in which there is first loss of speed and gain of +power, and then gain of speed at the expense of power in the same +mechanism, is furnished by the bicycle, where (1) the crank shaft +turns the sprocket wheel that constitutes a lever of the second class +with gain of power; where (2) power is further augmented through +transmission from the relatively large sprocket wheel to the small +sprocket of the axle; and where (3) there is great loss of power and +corresponding gain of speed in transmitting the force from the small +sprocket wheel at the axle to the rubber rim of the bicycle proper, +this last transmission representing a lever of the third class. The net +gain of speed is tangibly represented by the difference in distance +traversed by the man's feet in revolving the pedals, and the actual +distance covered by the bicycle. + + +INCLINED PLANES AND DERRICKS + +A less obvious application of the principle of reciprocal equivalence +of distance and weight is furnished by the inclined plane, a familiar +mechanism with the aid of which a great gain of power is possible. The +inclined plane, like the lever, has been known from remotest antiquity. +Its utility was probably discovered by almost the earliest builders. +Diodorus Siculus tells us that the great pyramids of Egypt were +constructed with the aid of inclined planes, based on a foundation of +earth piled about the pyramids. Diodorus, living at a period removed by +some thousands of years from the day of the building of the pyramids, +may or may not have voiced and recorded an authentic tradition, but we +may well believe that the principle of the inclined plane was largely +drawn upon by the mechanics of old Egypt, as by later peoples. + +The law of the inclined plane is that in order to establish equilibrium +between two weights, the one must be to the other as the height of +the inclined plane is to its length. The steeper the inclined plane, +therefore, the less will be the gain in power; a mechanical principle +which familiar experience or the simplest experiment will readily +corroborate. + +In its elemental form the inclined plane is not used very largely in +modern machinery, but its modified form of the wedge and the screw have +more utility. The screw, indeed, which is obviously an inclined plane +adjusted spirally about a cylinder or a cone, is familiar to everyone, +and is constantly utilized in applying power. + +The crane or derrick furnishes a familiar but relatively elaborate +illustration of a mechanism for the transmission of power, in which +all the various devices hitherto referred to are combined, without the +introduction of any new principle. + +Derricks have been employed from a very early day. The battering-rams +of the ancient Egyptians and Babylonians, for example, were virtually +derricks; and no doubt the same people used the device in raising +stones to build their temples and city walls, and in putting into +position such massive sculptures as the obelisks of Egypt and the +monster graven bulls and lions of Nineveh and Babylon. + +[Illustration: CRANES AND DERRICKS. + +The upper figure shows a floating derrick, the lower right-hand figure +a combined derrick and weighing machine, and the lower left-hand figure +a so-called sheerlegs, which is a simple derrick and windlass operated +by hand or by steam power with the aid of compound pulleys.] + +The modern derrick, made of steel, and operated by steam or +electricity, capable of lifting tons, yet absolutely obedient to the +hand of the engineer, is a really wonderful piece of mechanism. A +steam-scoop, for example, excavating a gravel bank, seems almost +a thing of intelligence; as it gores into the bank scooping up +perhaps a half ton of earth, its upward sweeping head reminds one of +an angry bull. Then as it swings leisurely about and discharges its +load at just the right spot into an awaiting car, its hinged bottom +swings back and forth two or three times before closing, with curious +resemblance to the jaw of a dog; the similarity being heightened +by the square bull-dog-headed shape of the scoop itself. Yet this +remarkable contrivance, with all its massive steel beams and chains +and cog wheels, employs no other principles than the simple ones of +lever and pulley and inclined plane that we have just examined. The +power that must be applied to produce a given effect may be calculated +to a nicety. The capacities of the machine are fully predetermined +in advance of its actual construction. But of course this is equally +true of every other form of power-transmitter with which the modern +mechanical engineer has to deal. + + +FRICTION + +In making such calculations, however, there is an additional element +which the engineer must consider, but which we have hitherto +disregarded. In all methods of transmission of power, and indeed in all +cases of the contact of one substance with another, there is an element +of loss through friction. This is due to the fact that no substance +is smooth except in a relative sense. Even the most highly polished +glass or steel, when viewed under the microscope, presents a surface +covered with indentations and rugosities. This granular surface of +even seemingly smooth objects, is easily visualized through the analogy +of numberless substances that are visibly rough. Yet the vast practical +importance of this roughness is seldom considered by the casual +observer. In point of fact, were it not for the roughened surface of +all materials with which we come in contact, it would be impossible for +any animal or man to walk, nor could we hold anything in our hands. +Anyone who has attempted to handle a fish, particularly an eel, fresh +from the water, will recall the difficulty with which its slippery +surface was held; but it may not occur to everyone who has had this +experience that all other objects would similarly slip from the hand, +had their surfaces a similar smoothness. The slippery character of the +eel is, of course, due in large part to the relatively smooth surface +of its skin, but partly also to the lubricant with which it is covered. +Any substance may be rendered somewhat smoother by proper lubrication; +it is necessary, however, that the lubricant should be something +which is not absorbed by the substance. Thus, wood is given increased +friction by being moistened with oil, but, on the other hand, is made +slippery if covered with graphite, soap, or any other fatty substances +that it does not absorb. + +Recalling the more or less roughened surface of all objects, the source +of friction is readily understood. It depends upon the actual jutting +of the roughened surfaces, one upon the other. It virtually constitutes +a force acting in opposition to the motion of any two surfaces +upon each other. As between any different materials, under given +conditions, it varies with the pressure, in a definite and measurable +rate, which is spoken of as the coefficient of friction for the +particular substances. It is very much greater where the two substances +slide over one another than where the one rolls upon the other, as in +the case of the wheel. The latter illustrates what is called rolling +friction, and in practical mechanics it is used constantly to decrease +the loss--as, for example, in the wheels of wagons and cars. The use of +lubricants to decrease friction is equally familiar. Without them, as +everyone knows, it would be impossible to run any wheel continuously +upon an axle at high speed for more than a very brief period, owing +to the great heat developed through friction. Friction is indeed a +perpetual antagonist of the mechanician, and we shall see endless +illustrations of the methods he employs to minimize its influence. On +the other hand, we must recall that were it rendered absolutely _nil_, +his machinery would all be useless. The car wheel, for example, would +revolve indefinitely without stirring the train, were there absolutely +no friction between it and the rail. + + +AVAILABLE SOURCES OF ENERGY + +We have pointed out that every body whatever contains a certain store +of energy, but it has equally been called to our attention that, in +the main, these stores of energy are not available for practical use. +There are, however, various great natural repositories of energy upon +which man is able to draw. The chief of these are, first, the muscular +energy of man himself and of animals; second, the energy of air in +motion; third, the energy of water in motion or at an elevation; and +fourth, the molecular and atomic energies stored in coal, wood, and +other combustible materials. To these we should probably add the energy +of radio-active substances--a form of energy only recently discovered +and not as yet available on a large scale, but which may sometime +become so, when new supplies of radio-active materials have been +discovered. It will be the object of succeeding chapters to point out +the practical ways in which these various stores of energy are drawn +upon and made to do work for man's benefit. + + + + +III + +THE ANIMAL MACHINE + + +The muscular system is not only the oldest machine in existence, +but also the most complex. Moreover, it is otherwise entitled to +precedence, for even to-day, in this so-called age of steam and +electricity, the muscular system remains by far the most important of +all machines. In the United States alone there are some twenty million +horses doing work for man; and of course no machine of any sort is +ever put in motion or continues indefinitely in operation without +aid supplied by human muscles. All in all, then, it is impossible to +overestimate the importance of this muscular machine which is at once +the oldest and the most lasting of all systems of utilizing energy. + +The physical laws that govern the animal machine are precisely similar +to those that are applied to other mechanisms. All the laws that have +been called to our attention must therefore be understood as applying +fully to the muscular mechanism. But in addition to these the muscular +system has certain laws or methods of action of its own, some of which +are not very clearly understood. + +The prime mystery concerning the muscle is its wonderful property of +contracting. For practical purposes we may say that it has no other +property; the sole function of the muscle is to contract. It can, of +course, relax, also, to make ready for another contraction, but this +is the full extent of its activities. A microscopic examination of +the muscle shows that it is composed of minute fibres, each of which +on contraction swells up into a spindle shape. A mass of such fibres +aggregated together constitutes a muscle, and every muscle is attached +at either extremity, by means of a tendon, to a bone. Both extremities +of a muscle are never attached to the same bone--otherwise the muscle +would be absolutely useless. Usually there is only a single bone +between the two ends of a muscle, but in exceptional cases there may be +more. As a rule, the main body of a muscle lies along the bone to which +one end of it is attached, the other end of the muscle being attached +to the contiguous bone placed not far from the point. The first bone, +then, serves as a fulcrum on which the second bone moves as a lever, +and, as already pointed out, the familiar laws of the lever operate +here as fully as in the inanimate world. But a moment's reflection +will make it clear that the object effected by this mechanism is the +increase of motion with relative loss of energy. In other words, the +muscular force is applied to the short end of the lever, and a far +greater expenditure of force is required when the muscle contracts than +the power externally manifested would seem to indicate. + +A moment's consideration of the mechanism of the arm, having regard to +the biceps muscle which flexes the elbow, will make this clear. If a +weight is held in the hand it is perhaps twelve inches from the elbow. +If, while holding the weight, you will grasp the elbow with the other +hand, you will feel the point of attachment of the biceps, and discover +that it does not seem to be, roughly speaking, more than about an inch +from the joint. Obviously, then, if you are lifting a pound weight, the +actual equivalent of energy expended by the contracting biceps must +be twelve pounds. But, in the meantime, when the pound weight in your +hand moves through the space of one inch, the muscle has contracted by +one-twelfth of an inch; and you may sweep the weight through a distance +of two feet by utilizing the two-inch contraction, which represents +about the capacity of the muscle. + +A similar consideration of the muscles of the legs will show how the +muscular system which is susceptible of but trifling variation in size, +gives to the animal great locomotive power. With the aid of a series of +levers, represented by the bones of our thighs, legs, and feet, we are +able to stride along, covering three or four feet at each step, while +no set of the muscles that effect this propulsion varies in length by +more than two or three inches. It appears, then, that the muscular +system gives a marvelous illustration of capacity for storing energy in +a compact form and utilizing it for the development of motion. + + +THE TWO TYPES OF MUSCLES + +The muscles of animals and men alike are divided into two systems, +one called voluntary, the other involuntary. The voluntary muscles, +as their name implies, are subject to the influence of the will, +and under ordinary conditions contract in response to the voluntary +nervous impulses. Certain sets of them, indeed, as those having to +do with respiration, have developed a tendency to rhythmical action +through long use, and ordinarily perform their functions without +voluntary guidance. Their function may, however, become voluntary +when attention is directed toward it, and is then subject to the +action of the will within certain bounds. Should a voluntary attempt +be made, however, to prevent their action indefinitely, the so-called +reflex mechanism presently asserts itself. All of which may be easily +attested by anyone who will attempt to stop breathing. All systems of +voluntary muscles are subject to the influence of habit, and may assume +activities that are only partially recognized by consciousness. As an +illustration in point, the muscles involved in walking come, in the +case of every adult, to perform their function without direct guidance +of the will. Such was not the case, however, in the early stage of +their development, as the observation of any child learning to walk +will amply demonstrate. In the case of animals, however, even those +muscles are so under the impress of hereditary tendencies as to perform +their functions spontaneously almost from the moment of birth. These, +however, are physiological details that need not concern us here. It +suffices to recall that the voluntary muscles may be directed by the +will, and indeed are always under what may be termed subconscious +direction, even when the conscious attention is not directed to them. + +The strictly involuntary muscles, however, are placed absolutely beyond +control of the will. The most important of these muscles are those +that constitute the heart and the diaphragm, and that enter into the +substance of the walls of blood vessels, and of the abdominal organs. +It is obvious that the functioning of these important organs could not +advantageously be left to the direction of the will; and so, in the +long course of evolution they have learned, as it were, to take care +of themselves, and in so doing to take care of the organism, to the +life of which they are so absolutely essential. As the physiologist +views the matter, no organism could have developed which did not +correspondingly develop such involuntary action of the vital organs. +It will be seen that the involuntary muscles differ from the voluntary +muscles in that they are not connected with bones. Instead of being +thus attached to solid levers, they are annular in structure, and in +contracting virtually change the size of the ring which their substance +constitutes. Each fibre in contracting may be thought of as pulling +against other fibres, instead of against a bony surface, and the joint +action changes the size of the organ, as is obvious in the pulsing of +the heart. + +Though the rhythmical contractions of the involuntary muscles are +independent of voluntary control, it must not be supposed that they +are independent of the control of the central nervous mechanism. On +the contrary, the nerve supply sent out from the brain to the heart +and to the abdominal organs is as plentiful and as important as that +sent to the voluntary muscles. There is a centre in the brain scarcely +larger than the head of a pin, the destruction of which will cause the +heart instantly to cease beating forever. From this centre, then, and +from the other centres of the brain, impulses are constantly sent to +the involuntary muscles, which determine the rate of activity. Nor are +these centres absolutely independent of the seat of consciousness, as +anyone will admit who recalls the varied changes in the heart's action +under stress of varying emotions. + +That the voluntary muscles are controlled by the central nervous +mechanism needs no proof beyond the appeal to our personal experiences +of every moment. You desire some object that lies on the table in front +of you, and immediately your hand, thanks to the elaborate muscular +mechanism, reaches out and grasps it. And this act is but typical of +the thousand activities that make up our every-day life. Everyone is +aware that the channel of communication between the brain and the +muscular system is found in a system of nerves, which it is natural +now-a-days to liken to a system of telegraph wires. We speak of the +impulse generated in the brain as being transmitted along the nerves to +the muscle, causing that to contract. We are even able to measure the +speed of transfer of such an impulse. It is found to move with relative +slowness, compassing only about one hundred and twelve feet per second, +being in this regard very unlike the electric current with which it is +so often compared. But the precise nature of this impulse is unknown. +Its effect, however, is made tangible in the muscular contraction +which it is its sole purpose to produce. The essential influence of +the nerve impulse in the transaction is easily demonstrable; for if +the nerve cord is severed, as often happens in accidents, the muscle +supplied by that nerve immediately loses its power of voluntary +contraction. It becomes paralyzed, as the saying is. + + +THE NATURE OF MUSCULAR ACTION + +Paying heed, now, to the muscle itself, it must be freely admitted +that, in the last analysis, the activities of the substance are as +mysterious and as inexplicable as are those involved in the nervous +mechanism. It is easy to demonstrate that what we have just spoken +of as a muscle fibre consists in reality of a little tube of liquid +protoplasm, and that the change in shape of this protoplasm constitutes +the contraction of which we are all along speaking. But just what +molecular and atomic changes are involved in this change of form of the +protoplasm, we cannot say. We know that the power to contract is the +one universal attribute of living protoplasm. This power is equally +wonderful and equally inexplicable, whether manifested in the case +of the muscle cell or in the case of such a formless single-celled +creature as the amoeba. When we know more of molecular and atomic +force, we may perhaps be able to form a mental picture of what goes on +in the structure of protoplasm when it thus changes the shape of its +mass. Until then, we must be content to accept the fact as being the +vital one upon which all the movements of animate creatures depend. + +But if, here as elsewhere, the ultimate activities of molecules and +atoms lie beyond our ken, we may nevertheless gain an insight into +the nature of the substances involved. We know, for example, that the +chief constituents of all protoplasm are carbon, hydrogen, oxygen, and +nitrogen; and that with these main elements there are traces of various +other elements such as iron, sulphur, phosphorus, and sundry salts. +We know that when the muscle contracts some of these constituents +are disarranged through what is spoken of as chemical decomposition, +and that there results a change in the substance of the protoplasm, +accompanied by the excretion of a certain portion of its constituents, +and by the liberation of heat. Carbonic acid gas, for example, is +generated and is swept away from the muscular tissues in the ever +active bloodstreams, to be carried to the lungs and there expelled--it +being a noxious poison, fatal to life if retained in large quantities. +Equally noxious are other substances such as uric acid and its +compounds, which are also results of the breaking down of tissue that +attends muscular action. In a word, there is an incessant formation of +waste products, due to muscular activity, the removal of which requires +the constant service of the purifying streams of blood and of the +various excretory organs. + +But this constant outflow of waste products from the muscle +necessitates, of course, in accordance with the laws of the +conservation of matter and of energy, an equally constant supply +of new matter to take the place of the old. This supply of what is +virtually fuel to be consumed, enabling the muscle to perform its +work, is brought to the muscle through the streams of blood which flow +from the heart in the arterial channels, and in part also through the +lymphatic system. The blood itself gains its supply from the digestive +system and from the lungs. The digestive system supplies water, that +all-essential diluent, and a great variety of compounds elaborated into +the proper pabulum; while the vital function of the lungs is to supply +oxygen, which must be incessantly present in order that the combustion +which attends muscular activity may take place. What virtually happens +is that fuel is sent from the digestive system to be burned in the +muscular system, with the aid of oxygen brought from the lungs. + +In this view, the muscular apparatus is a species of heat engine. In +point of fact, it is a curiously delicate one as regards the range of +conditions within which it is able to act. The temperature of any given +organism is almost invariable; the human body, for example, maintains +an average temperature of 98-2/5 degrees, Fahrenheit. The range of +variation from this temperature in conditions of health is rarely +more than a fraction of a degree; and even under stress of the most +severe fever the temperature never rises more than about eight degrees +without a fatal result. That an organism which is producing heat in +such varying quantities through its varying muscular activities should +maintain such an equilibrium of temperature, would seem one of the most +marvelous of facts, were it not so familiar. + +The physical means by which the heat thus generated is rapidly given +off, on occasion, to meet the varying conditions of muscular activity, +is largely dependent upon the control of the blood supply, in which +involuntary muscles, similar to those of the heart, are concerned. +In times of great muscular activity, when the production of heat is +relatively enormous, the arterioles that supply the surface of the +body are rapidly dilated so that a preponderance of blood circulates +at the surface of the body, where it may readily radiate its heat into +space; the vast system of perspiratory ducts, with which the skin is +everywhere supplied, aiding enormously in facilitating this result, +through the secretion of a film of perspiration, which in evaporating +takes up large quantities of heat. + +The flushed, perspiring face of a person who has violently exercised +gives a familiar proof of these physiological changes; and the contrary +condition, in which the peripheral circulation is restricted, and in +which the pores are closed, is equally familiar. Moreover, the same +cutaneous mechanism is efficient in affording the organism protection +from the changes of external temperature; though the human machine, +thanks to the pampering influence of civilization, requires additional +protection in the form of clothing. + + +APPLICATIONS OF MUSCULAR ENERGY + +Having thus outlined the conditions under which the muscular machine +performs its work, we have now to consider briefly the external +mechanisms with the aid of which muscular energy is utilized. +Of course, the simplest application of this power, and the one +universally employed in the animal world is that in which a direct +push or pull is given to the substance, the position of which it +is desired to change. We have already pointed out that there is no +essential difference between pushing and pulling. The fact receives +another illustration in considering the muscular mechanism. We speak +of pushing when we propel something away from a body, of pulling when +we draw something toward it, yet, as we have just seen, each can be +accomplished merely through the contraction of a set of muscles, acting +on differently disposed levers. All the bodily activities are reducible +to such muscular contractions, and the diversified movements in which +the organism constantly indulges are merely due to the large number and +elaborate arrangement of the bony levers upon which these muscles are +operated. + +We may well suppose that the primitive man continued for a long +period of time to perform all such labors as he undertook without +the aid of any artificial mechanism; that is to say, without having +learned to gain any power beyond that which the natural levers +of his body provided. A brief observation of the actions of a +man performing any piece of manual labor will, however, quickly +demonstrate how ingeniously the bodily levers are employed, and how +by shifting positions the worker unconsciously makes the most of a +given expenditure of energy. By bending the arms and bringing them +close to the body, he is able to shorten his levers so that he can +lift a much greater weight than he could possibly raise with the arms +extended. On the other hand, with the extended arm he can strike a +much more powerful blow than with the shorter lever of the flexed +arm. But however ingenious the manipulation of the natural levers, a +full utilization of muscular energy is possible only when they are +supplemented with artificial aids, which constitute primitive pieces of +machinery. + +These aids are chiefly of three types, namely, inclined planes, +friction reducers, and levers. The use of the inclined plane was very +early discovered and put into practise in chipped implements, which +took the form of the wedge, in such modifications as axes, knives, and +spears of metal. All of these implements, it will be observed, consist +essentially of inclined planes, adapted for piercing relatively soft +tissues of wood or flesh, and hence serving purposes of the greatest +practical utility. + +The knife-blade is an extremely thin wedge, to be utilized by force of +pushing, without any great aid from acquired momentum. The hatchet, on +the other hand--and its modification the axe--has its blunter blade +fastened to a handle; that the principle of the wedge may be utilized +at the long end of a lever and with the momentum of a swinging blow. +Ages before anyone could have explained the principle involved in such +obscuring terms as that, the implement itself was in use for the same +purpose to which it is still applied. Indeed, there is probably no +other implement that has played a larger part in the history of human +industry. Even in the Rough Stone Age it was in full favor, and the +earliest metallurgists produced it in bronze and then in iron. The +blade of to-day is made of the best tempered steel, and the handle +or helve of hickory is given a slight curve that is an improvement on +the straight handle formerly employed; but on the whole it may be said +that the axe is a surviving primitive implement that has held its own +and demonstrated its utility in every generation since the dawn, not of +history only, but of barbarism, perhaps even of savagery. + +The saw, consisting essentially of a thin elongated blade, one ragged +or toothed edge, is a scarcely less primitive and an equally useful and +familiar application of the principle of the inclined plane--though it +requires a moment's reflection to see the manner of application. Each +tooth, however minute, is an inclined plane, calculated to slide over +the tissue of wood or stone or iron even, yet to tear at the tissue +with its point, and, with the power of numbers, ultimately wear it away. + + +THE WHEEL AND AXLE + +The primitive friction reducer, which continues in use to the present +day unmodified in principle, is the wheel revolving on an axle. +Doubtless man had reached a very high state of barbarism before he +invented such a wheel. The American Indian, for example, knew no +better method than to carry his heavy burdens on his shoulders, or +drag them along the ground, with at most a pair of parallel poles or +runners to modify the friction; every move representing a very wasteful +expenditure of energy. But the pre-historic man of the old world had +made the wonderful discovery that a wheel revolving on an axle vastly +reduces the friction between a weight and the earth, and thus enables +a man or a woman to convey a load that would be far beyond his or her +unaided powers. It is well to use both genders in this illustration, +since among primitive peoples it is usually the woman who is the bearer +of burdens. And indeed to this day one may see the women of Italy and +Germany bearing large burdens on their backs and heads, and dragging +carts about the streets, quite after the primitive method. + +The more one considers the mechanism, the more one must marvel at the +ingenuity of the pre-historic man who invented the wheel and axle. Its +utility is sufficiently obvious once the thing has been done. In point +of fact, it so enormously reduces the friction that a man may convey +ten times the burden with its aid that he can without it. But how was +the primitive man, with his small knowledge of mechanics, to predict +such a result? In point of fact, of course, he made no such prediction. +Doubtless his attention was first called to the utility of rolling +bodies by a chance observation of dragging a burden along a pebbly +beach, or over rolling stones. The observation of logs or round stones +rolling down a hill might also have stimulated the imagination of some +inventive genius. + +[Illustration: A BELGIAN MILK-WAGON. + +In many of the countries of Europe the dog plays an important part as +a beast of burden. Stringent laws are enforced in these countries to +prevent possible abuse or neglect of the animals.] + +Probably logs placed beneath heavy weights, such as are still employed +sometimes in moving houses, were utilized now and again for many +generations before the idea of a narrow section of a log adjusted on +an axis was evolved. But be that as it may, this idea was put into +practise before the historic period begins, and we find the earliest +civilized races of which we have record--those, namely, of Old Egypt +and of Old Babylonia--in full possession of the principle of the wheel +as applied to vehicles. Modern mechanics have, of course, improved the +mechanism as regards details, but the wheels depicted in Old Egyptian +and Babylonian inscriptions are curiously similar to the most modern +types. Indeed, the wheel is a striking illustration of a mechanism +which continued century after century to serve the purposes of the +practical worker, with seemingly no prospect of displacement. + + +MODIFIED LEVERS + +For the rest, the mechanisms which primitive man learned early to +use in adding to his working efficiency, and which are still used by +the hand laborer, are virtually all modifications of our familiar +type-implement, the lever. A moment's reflection will show that the +diversified purposes of the crowbar, hoe, shovel, hammer, drill, +chisel, are all accomplished with the aid of the same principles. +The crowbar, for example, enables man to regain the power which he +lost when his members were adapted to locomotion. His hands, left +to themselves, as we have already pointed out, give but inadequate +expression to the power of his muscles. But by grasping the long end of +such a lever as the crowbar, he is enabled to utilize his entire weight +in addition to his muscular strength, and, with the aid of this lever, +to lift many times his weight. + +The hoe, on the other hand, becomes virtually a lengthened arm, +enabling a very slight muscular motion to be transformed into the +long sweep of the implement, so that with small expenditure of energy +the desired work is accomplished. Similarly, the sledge and the axe +lengthen out the lever of the arms, so that great momentum is readily +acquired, and with the aid of inertia a relatively enormous force can +be applied. It will be observed that a laborer in raising a heavy +sledge brings the head of the implement near his body, thus shortening +the leverage and gaining power at the expense of speed; but extends his +arms to their full length as the sledge falls, having now the aid of +gravitation, to gain the full advantage of the long arm of the lever in +acquiring momentum. + +Even such elaborately modified implements as the treadmill and the +rowboat are operated on the principle of the lever. These also are +mechanisms that have come down to us from a high antiquity. Their +utility, however, has been greatly decreased in modern times, by +the substitution of more elaborate and economical mechanisms for +accomplishing their respective purposes. The treadmill, indeed--which +might be likened to an overshot waterwheel in which the human foot +supplied the place of the falling water in giving power--has become +obsolete, though a modification of it, to be driven by animal power, is +still sometimes used, as we shall see in a moment. + +All these are illustrations of mechanisms with the aid of which human +labor is made effective. They show the devices by which primitive man +used his ingenuity in making his muscular system a more effective +machine for the performance of work. But perhaps the most ingenious +feat of all which our primitive ancestor accomplished was in learning +to utilize the muscular energy of other animals. Of course the example +was always before him in the observed activity of the animals on every +side. Nevertheless, it was doubtless long before the idea suggested +itself, and probably longer still before it was put into practise, of +utilizing this almost inexhaustible natural supply of working energy. + + +DOMESTICATED ANIMALS + +The first animal domesticated is believed to have been the dog, and +this animal is still used, as everyone knows, as a beast of burden in +the far North, and in some European cities, particularly in those of +Germany. Subsequently the ox was domesticated, but it is probable that +for a vast period of time it was used for food purposes, rather than as +a beast of burden. And lastly the horse, the worker _par excellence_, +was made captive by some Asiatic tribes having the genius of invention, +and in due course this fleetest of carriers and most efficient of +draught animals was introduced into all civilized nations. + +Doubtless for a long time the energy of the horse was utilized in an +uneconomical way, through binding the burden on its back, or causing it +to drag the burden along the ground. But this is inferential, since, +as we have seen, the wheel was invented in pre-historic times, and at +the dawn of history we find the Babylonians driving harnessed horses +attached to wheeled vehicles. From that day to this the method of +using horse-power has not greatly changed. The vast majority of the +many millions of horses that are employed every day in helping on the +world's work, use their strength without gain or loss through leverage, +and with only the aid of rolling friction to increase their capacity as +beasts of burden. + +To a certain extent horse-power is still used with the aid of the +modified treadmill just referred to--consisting essentially of an +inclined plane of flexible mechanism made into an endless platform, +which the horse causes to revolve as he goes through the movements of +walking upon it. In agricultural districts this form of power is still +sometimes used to run threshing machines, cider mills, wood-saws, +and the like. Another application of horse-power to the same ends +is accomplished through harnessing a horse to a long lever like the +spoke of a wheel, fastened to an axis, which is made to revolve as the +horse walks about it. Several horses are sometimes hitched to such +a mechanism, which becomes then a wheel of several spokes. But this +mechanism, which was common enough in agricultural districts two or +three decades ago, has been practically superseded in recent years by +the perambulatory steam engine. + +[Illustration: TWO APPARATUSES FOR THE UTILIZATION OF ANIMAL POWER. + +The upper figure shows the type of portable horse-power machine used +for threshing grain in 1851. The lower figure is an inclined-plane +horse-gear. The horse stands on the sloping platform tied to the bar in +front, so that it is compelled to walk as the platform recedes.] + +It is obvious that the amount of work which a horse can accomplish +must vary greatly with the size and quality of the horse, and with the +particular method by which its energy is applied. For the purposes +of comparison, however, an arbitrary amount of work has been fixed +upon as constituting what is called a horse-power. This amount is the +equivalent of raising thirty-three thousand pounds of weight to the +height of one foot in one minute. It would be hard to say just why this +particular standard was fixed upon, since it certainly represents more +than the average capacity of a horse. It is, however, a standard which +long usage (it was first suggested by Watt, of steam-engine fame) has +rendered convenient, and one which the machinist refers to constantly +in speaking of the efficiency of the various types of artificial +machines. All questions of the exact legitimacy of this particular +standard aside, it was highly appropriate that the labor of the horse, +which has made up so large a share of the labor of the past, and which +is still so extensively utilized, should continue to be taken as the +measuring standard of the world's work. + + + + +IV + +THE WORK OF AIR AND WATER + + +The store of energy contained in the atmosphere and in the waters of +the globe is inexhaustible. Its amount is beyond all calculation; or if +it were vaguely calculated the figures would be quite incomprehensible +from their very magnitude. It is not, however, an altogether simple +matter to make this energy available for the purposes of useful work. +We find that throughout antiquity comparatively little use was made of +either wind or water in their application to machinery. + +Doubtless the earliest use of air as a motive power was through the +application of sails to boats. We know that the Phoenicians used a +simple form of sail, and no doubt their example was followed by all the +maritime peoples of subsequent periods. But the use of the sail even by +the Phoenicians was as a comparatively unimportant accessory to the +galaxies of oars, which formed the chief motive power. The elaboration +of sails of various types, adequate in extent to propel large ships, +and capable of being adjusted so as to take advantage of winds blowing +from almost any quarter, was a development of the Middle Ages. + +The possibilities of work with the aid of running water were also but +little understood by the ancients. In the days of slave labor it was +scarcely worth while to tax man's ingenuity to invent machines, since +so efficient a one was provided by nature. Yet the properties of both +air and water were studied by various mechanical philosophers, at the +head of whom were Archimedes, whose work has already been referred to, +and the famous Alexandrian, Ctesibius, whose investigations became +familiar through the publications of his pupil, Hero. + +Perhaps the most remarkable device invented by Ctesibius was a +fire-engine, consisting of an arrangement of valves constituting a +pump, and operating on the principle which is still in vogue. It is +known, however, that the Egyptians of a much earlier period used +buckets having valves in their bottoms, and these perhaps furnished the +foundation for the idea of Ctesibius. It is unnecessary to give details +of this fire-engine. It may be noted, however, that the principle of +the lever is the one employed in its operation to gain power. A valve +consists essentially of any simple hinged substance, arranged so that +it may rise or fall, alternately opening and closing an aperture. +A mere flap of leather, nailed on one edge, serves as a tolerably +effective valve. At least one of the valves used by Ctesibius was a +hinged piece of smooth metal. A piston fitted in a cylinder supplies +suction when the lever is raised, and pressure when it is compressed, +alternately opening the valve and closing the valve through which the +water enters the tube. Meantime a second valve alternating with the +first permits the water to enter the chamber containing air, which +through its elasticity and pressure equalizes the force of the stream +that is ejected from the chamber through the hose. + + +SUCTION AND PRESSURE + +In the construction of this and various other apparatus, Ctesibius and +Hero were led to make careful studies of the phenomena of suction. But +in this they were not alone, since numerous of their predecessors had +studied the subject, and such an apparatus as the surgeon's cupping +glass was familiarly known several centuries before the Christian era. +The cupping glass, as perhaps should be explained to the reader of the +present day--since the apparatus went out of vogue in ordinary medical +practise two or three generations ago--consists of a glass cup in which +the air is exhausted, so as to suck blood from any part of the surface +of a body to which it is applied. Hero describes a method of exhausting +air by which such suction may be facilitated. But neither he nor any +other philosopher of his period at all understood the real nature of +this suction, notwithstanding their perfect familiarity with numerous +of its phenomena. It was known, for example, that when a tube closed +at one end is filled with water and inverted with the open end beneath +the surface of the water, the water remains in the tube, although one +might naturally expect that it would obey the impulses of gravitation +and run out, leaving the tube empty. A familiar explanation of this and +allied phenomena throughout antiquity was found in the saying that +"Nature abhors a vacuum." This explanation, which of course amounts +to no explanation at all, is fairly illustrative of the method of +metaphysical word-juggling that served so largely among the earlier +philosophers in explanation of the mysteries of physical science. + +The real explanation of the phenomena of suction was not arrived +at until the revival of learning in the seventeenth century. Then +Torricelli, the pupil of Galileo, demonstrated that the word suction, +as commonly applied, had no proper application; and that the phenomena +hitherto ascribed to it were really due to the pressure of the +atmosphere. A vacuum is merely an enclosed space deprived of air, and +the "abhorrence" that Nature shows to such a space is due to the fact +that air has weight and presses in every direction, and hence tends +to invade every space to which it can gain access. It was presently +discovered that if the inverted tube in which the water stands was +made high enough, the water will no longer fill it, but will sink to a +certain level. The height at which it will stand is about thirty feet; +above that height a vacuum will be formed, which, for some reason, +Nature seems not to abhor. The reason is that the weight of any given +column of water about thirty feet in height is just balanced by the +weight of a corresponding column of atmosphere. The experiments that +gave the proof of this were made by the famous Englishman, Boyle. He +showed that if the heavy liquid, mercury, is used in place of water, +then the suspended column will be only about thirty inches in height. +The weight or pressure of the atmosphere at sea level, as measured by +these experiments, is about fifteen pounds to the square inch. + +Boyle's further experiments with the air and with other gases developed +the fact that the pressure exerted by any given quantity of gas is +proportional to the external pressure to which it is subjected, which, +after all, is only a special application of the law that action and +reaction are equal. The further fact was developed that under pressure +a gas decreases at a fixed rate in bulk. A general law, expressing +these facts in the phrase that density and elasticity vary inversely +with the pressure in a precise ratio, was developed by Boyle and the +Frenchman, Mariotte, independently, and bears the name of both of its +discoverers. No immediate application of the law to the practical +purposes of the worker was made, however, and it is only in recent +years that compressed air has been extensively employed as a motive +power. Even now it has not proved a great commercial success, because +other more economical methods of power production are available. In +particular cases, however, it has a certain utility, as a relatively +large available source of energy may be condensed into a very small +receptacle. + +A very striking experiment illustrating the pressure of the air was +made by a famous contemporary of Boyle and Mariotte, by the name of +Otto von Guericke. He connected an air pump with a large brass sphere, +composed of two hemispheres, the edges of which fitted smoothly, but +were not connected by any mechanism. Under ordinary conditions the +hemispheres would fall apart readily, but von Guericke proved, by +a famous public demonstration, that when the air was exhausted in +the sphere, teams of horses pulling in opposite directions on the +hemispheres could not separate them. This is famous as the experiment +of the Magdeburg spheres, and it is often repeated on a smaller scale +in the modern physical laboratory, to the astonishment of the tyro in +physical experiments. + +The first question that usually comes to the mind of anyone who has +personally witnessed such an experiment, is the question as to how +the human body can withstand the tremendous force to which it is +subjected by an atmosphere exerting a pressure of fifteen pounds on +every square inch of its surface. The explanation is found in the +uniform distribution of the pressure, the influence of which is thus +counteracted, and by the fact that the tissues themselves contain +everywhere a certain amount of air at the same pressure. The familiar +experiment of holding the hand over an exhausted glass cylinder--which +experiment is indeed but a modification of the use of the cupping +glass above referred to--illustrates very forcibly the insupportable +difficulties which the human body would encounter were not its entire +surface uniformly subjected to the atmospheric pressure. + + +AIR IN MOTION + +At about the time when the scientific experiments with the pressure of +gases were being made, practical studies of the effects of masses of +air in motion were undertaken by the Dutch philosopher, Servinus. The +use of the windmill in Holland as a means of generating power doubtless +suggested to Servinus the possibility of attaching a sail to a land +vehicle. He made the experiment, and in the year 1600 constructed a +sailing car which, propelled by the wind, traversed the land to a +considerable distance, on one occasion conveying a company of which +Prince Maurice of Orange was a member. But his experiments have seldom +been repeated, and indeed their lack of practical feasibility scarcely +needs demonstration. + +The utility of the wind, however, in generating the power in a +stationary mechanism is familiar to everyone. Windmills were +constructed at a comparatively early period, and notwithstanding all +the recent progress in the development of steam and electrical power, +this relatively primitive so-called prime mover still holds its own in +agricultural districts, particularly in its application to pumps. A +windmill consists of a series of inclined planes, each of which forms +one of the radii of a circle, or spokes of a wheel, to the axle of +which a gearing is adjusted by which the power generated is utilized. +The wheel is made to face the wind by the wind itself blowing against a +sort of rudder which projects from the axis. The wind blowing against +the inclined surfaces or vanes of the wheel causes each vane to move in +accordance with the law of component forces, thus revolving the wheel +as a whole. + +[Illustration: WINDMILLS OF ANCIENT AND MODERN TYPES. + +The smaller figures show Dutch windmills of the present day, many of +which are identical in structure with the windmills of the middle ages. +It will be seen that the sails can be furled when desired to put the +mill out of operation. In the mill of modern type (large figure) the +same effect is produced by slanting the slats of the wheel.] + +It has been affirmed that the Romans had windmills, but "the silence of +Vitruvius, Seneca, and Chrysostom, who have spoken of the advantages of +the wind, makes this opinion questionable." It has been supposed by +other writers that windmills were used in France in the sixth century, +while still others have maintained that this mechanism was unknown in +Europe until the time of the Crusades. All that is tolerably certain +is that in the twelfth century windmills were in use in France and +England. It is recorded that when they began to be somewhat common +Pope Celestine III. determined that the tithes of them belonged to the +clergy. + + +INHERENT DEFECTS OF THE WINDMILL + +The mediaeval European windmill was supplied with great sails of cloth, +and its picturesque appearance has been made familiar to everyone +through the famous tale of _Don Quixote_. The modern windmill, acting +on precisely the same principle, is a comparatively small affair, +comprising many vanes of metal, and constituting a far more practical +machine. The great defect of all windmills, however, is found in the +fact that of necessity they furnish such variable power, since the +force of the wind is incessantly changing. Worst of all, there may be +protracted periods of atmospheric calm, during which, of course, the +windmill ceases to have any utility whatever. This ineradicable defect +relegates the windmill to a subordinate place among prime movers, yet +on the other hand, its cheapness insures its employment for a long time +to come, and the industry of manufacturing windmills continues to be an +important one, particularly in the United States. + + +RUNNING WATER + +The aggregate amount of work accomplished with the aid of the wind is +but trifling, compared with that which is accomplished with the aid of +water. The supply of water is practically inexhaustible, and this fluid +being much more manageable than air, can be made a far more dependable +aid to the worker. Every stream, whatever its rate of flow, represents +an enormous store of potential energy. A cubic foot of water weighs +about sixty-two and a half pounds. The working capacity of any mass +of water is represented by one-half its weight into the square of its +velocity; or, stated otherwise, by its weight into the distance of its +fall. Now, since the interiors of the continents, where rivers find +their sources, are often elevated by some hundreds or even thousands +of feet, it follows that the working energy expended--and for the most +part wasted--by the aggregate water current of the world is beyond all +calculation. Meantime, however, a portion of the energy which in the +aggregate represents an enormous working power is utilized with the aid +of various types of water wheels. + +Watermills appear to have been introduced in the time of Mithridates, +Julius Caesar, and Cicero. Strabo informs us that there was a watermill +near the residence of Mithridates; and we learn from Pomponius Sabinus, +that the first mill seen at Rome was erected on the Tiber, a little +before the time of Augustus. That they existed in the time of Augustus +is obvious from the description given of them by Vitruvius, and the +epigram of Antipater, who is supposed to have lived in the time of +Cicero. But though mills driven by water were introduced at this early +period, yet public mills did not appear till the time of Honorius and +Arcadius. They were erected on three canals, which conveyed water to +the city, and the greater number of them lay under Mount Janiculum. +When the Goths besieged Rome in 536, and stopped the large aqueduct and +consequently the mills, Belisarius appears to have constructed, for the +first time, floating mills upon the Tiber. Mills driven by the tide +existed at Venice in the year 1046, or at least in 1078. + +The older types of water wheel are exceedingly simple in construction, +consisting merely of vertical wheels revolving on horizontal axes, +and so placed as to receive the weight or pressure of the water on +paddles or buckets at their circumference. The water might be allowed +to rush under the wheel, thus constituting an under-shot wheel; or +more commonly it flows from above, constituting an over-shot wheel. +Where the natural fall is not available, dams are employed to supply an +artificial fall. + +This primitive type of water wheel has been practically abandoned +within the last generation, its place having been taken by the much +more efficient type of wheel known as the turbine. This consists of +a wheel, usually adjusted on a vertical axis, and acting on what is +virtually the principle of a windmill. To gain a mental picture of the +turbine in its simplest form, one might imagine the propelling screw +of a steamship, placed horizontally in a tube, so that the water could +rush against its blades. The tiny windmills which children often make +by twisting pieces of paper illustrate the same principle. Of course, +in its developed form the turbine is somewhat elaborated, in the aim to +utilize as large a proportion of the energy of the falling water as is +possible; but the principle remains the same. + +The turbine wheel was invented by a Frenchman named Fourneyron, about +three-quarters of a century ago (1827), but its great popularity, in +America in particular, is a matter of the last twenty or thirty years. +To-day it has virtually supplanted every other type of water wheel. +To use any other is indeed a wasteful extravagance, as the perfected +turbine makes available more than eighty per cent. of the kinetic +energy of any mass of falling water. A turbine wheel two feet in +diameter is able to do the work of an enormous wheel of the old type. + +Turbine wheels are of several types, one operating in a closed tube to +which air has no access, and another in an open space in the presence +of air. The water may also be made to enter the turbine at the side +or from below, thus serving to support the weight of the mechanism--a +consideration of great importance in the case of such gigantic turbines +as those that are employed at Niagara Falls, which we shall have +occasion to examine in detail in a later chapter. + +[Illustration: WATER WHEELS. + +Fig. 1 shows a model of the so-called breast wheel, a familiar type of +water wheel that has been in use since the time of the Romans. Figs. +2 and 3 show similar wheels as used to-day in Belgium. Fig. 4 shows a +model of Fourneyron's turbine. This wheel was made in 1837, but the +original turbine was introduced by Fourneyron in 1827. The turbine +wheel has now almost supplanted the other forms of water wheel except +in rural districts.] + +The power generated by a revolution of the turbine wheel may, of +course, be utilized directly by belts or gearings attached to its +axle, or it may be transferred to a distance, with the aid of a +dynamo generating electricity. The latter possibility, which has only +recently been developed, and which we shall have occasion to examine +in detail in connection with our studies of the power at Niagara, gives +a new field of usefulness to the turbine wheel, and makes it probable +that this form of power will be vastly more used in the future than +it has been in the past. Indeed, it would not be surprising were it +ultimately to become the prime source of working energy as utilized in +every department of the world's work. + +Mr. Edward H. Sanborn, in an article on Motive Power Appliances in the +Twelfth Census Report of the United States, comments upon the recent +advances in the use of water wheels as follows: + +"One notable advance in turbine construction has been the production +of a type of wheel especially designed for operating under much higher +heads of water than were formerly considered feasible for wheels of +this type. Turbines are now built for heads ranging from 100 to 1,200 +feet, and quite a number of wheels are in operation under heads of from +100 to 200 feet. This is an encroachment upon the field occupied almost +exclusively by wheels variously known as the 'impulse,' 'impact,' +'tangential,' or 'jet' type, the principle of which is the impact of +a powerful jet of water from a small nozzle upon a series of buckets +mounted upon the periphery of a small wheel." + +"The impact water wheel," Mr. Sanborn continues, "has come largely +into use during the last ten years, principally in the far West, +where higher heads of water are available than can be found in other +parts of the country. With wheels of this type, exceedingly simple +in construction and of comparatively small cost, a large amount of +power is developed with great economy under the great heads that are +available. With the tremendous water pressure developed by heads of +1,000 feet and upward, which in many cases are used for this purpose, +wheels of small diameter develop an extraordinary amount of power. +To the original type of impact wheel which first led the field have +been added several styles embodying practically the same principle. +Considerable study has been given to the designing of buckets with a +view to securing free discharge and the avoidance of any disturbing +eddies, and important improvements have resulted from the thorough +investigation of the action of the water during, and subsequent to, +its impact on the buckets. The impact wheel has been adapted to a wide +range of service with great variation as to the conditions under which +it operates, wheels having been made in California from 30 inches to +30 feet in diameter, and to work under heads ranging from 35 to 2,100 +feet, and at speeds ranging from 65 to 1,100 revolutions per minute. A +number of wheels of this type have been built with capacities of not +less than 1,000 horse-power each." + + +HYDRAULIC POWER + +A few words should be said about the familiar method of transmitting +power with the aid of water, as illustrated by the hydrostatic press. +This does not indeed utilize the energy of the water itself, but it +enables the worker to transmit energy supplied from without, and to +gain an indefinite power to move weights through a short distance, +with the expenditure of very little working energy. The principle on +which the hydrostatic press is based is the one which was familiar to +the ancient philosophers under the name of the hydrostatic paradox. +It was observed that if a tube is connected with a closed receptacle, +such as a strong cask, and cask and tube are filled with water, the +cask will presently be burst by the pressure of the water, provided the +tube is raised to a height, even though the actual weight of water in +the tube be comparatively slight. A powerful cask, for example, may be +burst by the water poured into a slender pipe. The result seems indeed +paradoxical, and for a long time no explanation of it was forthcoming. +It remained for Servinus, whose horseless wagon is elsewhere noticed, +to discover that the water at any given level presses equally in all +directions, and that its pressure is proportionate to its depth, quite +regardless of its bulk. Then, supposing the tube in our experiment to +have a cross-section of one square inch, a pressure equal to that in +the tube would be transmitted to each square inch of the surface of the +cask; and the pressure might thus become enormous. + +If, instead of a tube lifted to a height, the same tube is connected +with a force pump operated with a lever--an apparatus similar to the +fire-engine of Ctesibius--it is obvious that precisely the same effect +may be produced; whatever pressure is developed in the piston of the +force pump, similar pressure will be transferred to a corresponding +area in the surface of the cask or receptacle with which the force pump +connects. In practise this principle is utilized, where great pressure +is desired, by making a receptacle with an enormous piston connecting +with the force pump just described. + +An indefinite power may thus be developed, the apparatus constituting +virtually a gigantic lever. But the principle of the equivalence of +weight and distance still holds, precisely as in an actual lever, +and while the pressure that may be exerted with slight expenditure +of energy is enormous, the distance through which this pressure acts +is correspondingly small. If, for example, the piston of the force +pump has an area of one square inch, while the piston of the press +has an area of several square feet, the pressure exerted will be +measured in tons, but the distance through which it is exerted will be +almost infinitesimal. The range of utility of the hydrostatic press +is, therefore, limited, but within its sphere, it is an incomparable +transmitter of energy. + +[Illustration: HYDRAULIC PRESS AND HYDRAULIC CAPSTAN. + +The upper figure shows Bramah's original hydraulic pump and press, +now preserved in the South Kensington Museum, London. The machine was +constructed in 1796 by Joseph Bramah to demonstrate the principle of +his hydraulic press. The discrepancy in size between the small lever +worked by hand and the enormous lever carrying a heavy weight gives a +vivid impression of the gain in power through the use of the apparatus. +The lower figure shows the hydraulic capstan used on many modern ships, +in which the same principle is utilized.] + +Moreover, it is possible to reverse the action of the hydraulic +apparatus so as to gain motion at the expense of power. A familiar type +of elevator is a case in point. The essential feature of the hydraulic +elevator consists of a ram attached to the bottom of the elevator and +extending down into a cylinder, slightly longer than the height to +which the elevator is to rise. The ram is fitting into a cylinder with +water-tight packing, or a cut leather valve. Water under high pressure +is admitted to the cylinder through the valve at the bottom, and the +pressure thus supplied pushes up the ram, carrying the elevator with +it, of course. Another valve allows the water to escape, so that ram +and elevator may descend, too rapid descent being prevented by the +partial balancing of ram and elevator with weights acting over pulleys. +The ram, to the end of which pressure is thus applied, need be but a +few inches in diameter. Water pressure is secured by bringing water +from an elevation. Such an elevator acts slowly, but is a very safe +and in many ways satisfactory mechanism. Such elevators are still used +extensively in Europe, but have been almost altogether displaced in +America by the electric elevator. + +The hydraulic elevator just described is virtually a water engine, the +ram acting as piston. A veritable engine, of small size, to perform +any species of mechanical work, may be constructed on precisely the +same principle, the piston in this case acting in a cylinder similar to +that of the ordinary steam engine. Such an engine operates slowly but +with great power. It has special utility where it is desirable to apply +power intermittently, as in various parts of a dockyard, or in handling +guns and ammunition on shipboard. In the former case in particular, +it is often inconvenient to use steam power, as steam sent from a +central boiler condenses in a way to interfere with its operation. In +such a case any number of small water-pressure engines may be operated +from a single tank where water is at a high elevation, or where the +requisite pressure is secured artificially. In the latter case, the +water is kept under pressure by a large piston or ram heavily weighted, +the entire receptacle being, of course, of water-tight construction +and adapted to withstand pressure. The pump that supplies the tank is +ordinarily made to work automatically, ceasing operation as soon as the +ram rises to the top of the receptacle, and beginning again whenever, +through use of water, the ram begins to descend. Such an apparatus is +called an accumulator. Such water engines have come into vogue only in +comparatively recent times, being suggested by the steam engine. As +already pointed out, their utility is restricted, yet the total number +of them in actual use to-day is large, and their share in the world's +work is not altogether inconsiderable. + + + + +V + +CAPTIVE MOLECULES: THE STORY OF THE STEAM ENGINE + + +We come now to that all-important transformer of power, the steam +engine. Everybody knows that steam is a state of water in which, +under the influence of heat, the molecules have broken away from the +mutual attraction of cohesion, and are flying about at inconceivable +speed, rebounding from one another after collision, in virtue of their +elasticity, exerting in the aggregate an enormous pressure in every +direction. It is this consideration of the intimate character of steam +that justifies the title of the present chapter; a title that has +further utility as drawing a contrast between the manner of working +with which we are now to be concerned, and the various types of workers +that we have previously considered. + +In speaking of the animal machine and of work accomplished by the air +and the water, we have been concerned primarily with masses of matter, +possessing and transmitting energy. Of course molecules--since they +make up the substance of all matter--could not be altogether ignored, +but in the main we have had to do with molar rather than with molecular +motion. Now, however, we are concerned with a mechanism in which the +molecular activities are directly concerned in performing work. + +Even in the aggregate the molecules make up a mere intangible gas, +which requires to be closely confined in order that its energy may be +made available. Once the molecules have performed their work, they +are so changed in their activities that they sink back, as it were, +exhausted, into a relatively quiescent state, which enables their +latent cohesive forces to reduce them again to the state of a liquid. +In a word, we are concerned with the manifestation of energy which +depends upon molecular activities in a way quite different from what +has been the case with any of the previously considered mechanisms. +The tangible manifestation of energy which we term heat is not merely +a condition of action and a by-product, as it was in the case of +the animal machine; it is the essential factor upon which all the +efficiency of the mechanism depends. + +It should perhaps be stated that this explanation of the action of +the steam engine is a comparatively modern scientific interpretation. +The earlier experimenters brought the steam engine to a high state of +efficiency, without having any such conception as this of the nature +of steam itself. For practical purposes it suffices to note that water +when heated takes the form of steam; that this steam has the property +of powerful and indefinite expansion; and thirdly, that when allowed to +escape from a state of pressure, sudden expansion of the steam cools it +sufficiently to cause the recondensation of part of its substance, thus +creating a vacuum. + +Stated in few words, the entire action of the steam depends upon these +simple mechanical principles. The principles are practically applied +by permitting the steam to enter the cylinder where it can act on +a piston, to which it gives the thrust that is transmitted to an +external mechanism by means of a rod attached to the piston. When the +piston has been driven to the end of the desired thrust, the valve is +opened automatically, permitting the steam to escape, thus producing a +vacuum, and insuring the return thrust of the piston, which is further +facilitated, ordinarily, by the admission of steam to the other side +of the piston. Practical operation of this mechanism is familiar to +everyone, though the marvel of its power and efficiency seems none the +less because of its familiarity. + +It is not too much to say that this relatively simple device, in its +first general application, marked one of the most important turning +points in the history of civilization. To its influence, more than to +any other single cause, must be ascribed the revolutionary change that +came over the character of practical life in the nineteenth century. +From prehistoric times till well toward the close of the eighteenth +century, there was scarcely any important change in carrying out the +world's work. And in the few generations that have since elapsed, the +entire aspect of the mechanical world has been changed, the working +efficiency of the individual has been largely increased; mechanical +tasks have become easy which hitherto were scarcely within the range of +human capacity. + +Before we go on to the detailed study of the machine which has produced +these remarkable results, it is desirable to make inquiry as to the +historical development of so important an invention. + +The practical steam engine in its modern form dates, as just mentioned, +from the latter part of the eighteenth century, and was perfected by +James Watt, who is commonly thought of as being its inventor. In point +of fact, however, the history of most inventions is duplicated here, as +on examination it appears that various forerunners of Watt had been on +the track of the steam engine, and some of them, indeed, had produced a +workable machine of no small degree of efficiency. + +The very earliest experiments were made away back in the Alexandrian +days in the second century before the Christian era, the experimenter +being the famous Hero, whose work in an allied field was referred to +in the preceding chapter. Hero produced--or at least described and so +is credited with producing, though the actual inventor may have been +Ctesibius--a little toy mechanism, in which a hollow ball was made to +revolve on an axis through the agency of steam, which escaped from +two bent tubes placed on opposite sides of the ball, their orifices +pointing in opposite directions. The apparatus had no practical +utility, but it sufficed to establish the principle that heat, acting +through the agency of steam, could be made to do mechanical work. Had +not the age of Hero been a time of mental stasis, it is highly probable +that the principle he had thus demonstrated would have been applied +to some more practical mechanism in succeeding generations. As it +was, however, nothing practical came of his experiment, and the steam +turbine engine was remembered only as a scientific toy. + +No other worker continued the experiments, so far as is known, until +the time of the great Italian, Leonardo da Vinci, who, late in the +fifteenth century, gave a new impulse to mechanical invention. Leonardo +experimented with steam, and succeeded in producing what was virtually +an explosion engine, by the agency of which a ball was propelled along +the earth. But this experiment also failed to have practical result. + + +BEGINNINGS OF MODERN DISCOVERY + +Such sporadic experiments as these have no sequential connection with +the story of the evolution of the steam engine. The experiments which +led directly on to practical achievements were not begun until the +seventeenth century. In the very first year of that century, an Italian +named Giovanni Battista della Porta published a treatise on pneumatics, +in which the idea of utilizing steam for the practical purpose of +raising water was expressly stated. The idea of this inventor was put +into effect in 1624 by a French engineer and mathematician, Solomon de +Caus. He invented two different machines, the first of which required a +spherical boiler having an internal tube reaching nearly to the bottom; +a fire beneath the boiler produced steam which would force the water in +the boiler to a height proportional to the pressure obtained. In the +other machine, steam is led from the boiler into the upper part of a +closed cistern containing water to be elevated. To the lower portion of +the cistern a delivery pipe was attached so that water was discharged +under a considerable pressure. This arrangement was precisely similar +to the apparatus employed by Hero of Alexandria in various of his +fountains, as regards the principle of expanding gas to propel water. +An important difference, however, consists in the fact that the +scheme of della Porta and of de Caus embodied the idea of generating +pressure with the aid of steam, whereas Hero had depended merely on the +expansive property of air compressed by the water itself. + +While these mechanisms contained the germ of an idea of vast +importance, the mechanisms themselves were of trivial utility. It is +not even clear whether their projectors had an idea of the properties +of the condensation of vapor, upon which the working of the practical +steam engine so largely depends. This idea, however, was probably +grasped about half a century later by an Englishman, Edward Somerset, +the celebrated Marquis of Worcester, who in 1663 described in his +_Century of Inventions_ an apparatus for raising water by the expansive +force of steam. His own account of his invention is as follows: + +"An admirable and most forcible way to drive up water by fire; not by +drawing or sucking it upwards, for that must be as the philosopher +calleth it, _intra sphaeram activitatis_, which is but at such a +distance. But this way hath no bounder, if the vessel be strong enough: +for I have taken a piece of whole cannon, whereof the end was burst, +and filled it three-quarters full of water, stopping and screwing up +the broken end, as also the touch-hole; and making a constant fire +under it, within twenty-four hours it burst and made a great crack; so +that having a way to make my vessels so that they are strengthened by +the force within them, and the one to fill after the other, I have seen +the water run like a constant stream, forty feet high: one vessel of +water, rarefied by fire, driveth up forty of cold water; and the man +that tends the work is but to turn two cocks, that one vessel of water +being consumed, another begins to force and refill with cold water, +and so successively; the fire being tended and kept constant, which +the self-same person may likewise abundantly perform in the interim, +between the necessity of turning the said cocks." + +It is unfortunate that the Marquis did not give a more elaborate +description of this remarkable contrivance. The fact that he treats it +so casually is sufficient evidence that he had no conception of the +possibilities of the mechanism; but, on the other hand, his description +suffices to prove that he had gained a clear notion of, and had +experimentally demonstrated, the tremendous power of expansion that +resides in steam. No example of his steam pump has been preserved, and +historians of the subject have been left in doubt as to some details +of its construction, and in particular as to whether it utilized the +principle of a vacuum created through condensation of the steam. + + +THOMAS SAVERY'S STEAM PUMP + +This principle was clearly grasped, however, by another Englishman, +Thomas Savery, a Cornish mine captain, who in 1698 secured a patent for +a steam engine to be applied to the raising of water, etc. A working +model of this machine was produced before the Royal Society in 1699. +The transactions of the Society contain the following: "June 14th, +1699, Mr. Savery entertained the Royal Society with showing a small +model of his engine for raising water by help of fire, which he set to +work before them: the experiment succeeded according to expectation, +and to their satisfaction." + +The following very clear description of Savery's engine is given in the +introduction to Beckmann's _History of Inventions_: + +"This engine, which was used for some time to a considerable extent for +raising water from mines, consisted of a strong iron vessel shaped like +an egg, with a tube or pipe at the bottom, which descended to the place +from which the water was to be drawn, and another at the top, which +ascended to the place to which it was to be elevated. This oval vessel +was filled with steam supplied from a boiler, by which the atmospheric +air was first blown out of it. When the air was thus expelled and +nothing but pure steam left in the vessel, the communication with the +boiler was cut off, and cold water poured on the external surface. The +steam within was thus condensed and a vacuum produced, and the water +drawn up from below in the usual way by suction. The oval vessel was +thus filled with water; a cock placed at the bottom of the lower pipe +was then closed, and steam was introduced from the boiler into the +oval vessel above the surface of the water. This steam being of high +pressure, forced the water up the ascending tube, from the top of +which it was discharged, and the oval vessel being thus refilled with +steam, the vacuum was again produced by condensation, and the same +process was repeated. By using two oval steam vessels, which would act +alternately--one drawing water from below, while the other was forcing +it upwards, an uninterrupted discharge of water was produced. Owing to +the danger of explosion, from the high pressure of the steam which was +used, and from the enormous waste of heat by unnecessary condensation, +these engines soon fell into disuse." + +[Illustration: THOMAS SAVERY'S STEAM ENGINE. + +The principle involved is that of the expansion of steam exerting a +propulsive force and its subsequent condensation to produce a vacuum. +These are the principles employed in the modern steam engine, but the +only use to which they were put in Savery's engine was the elevation of +water by suction.] + +This description makes it obvious that Savery had the clearest +conception of the production of a vacuum by the condensation of steam, +and of the utilization of the suction thus established (which suction, +as we know, is really due to the pressure of outside air) to accomplish +useful work. Savery also arranged this apparatus in duplicate, so that +one vessel was filling with water while the other was forcing water +to the delivery pipe. This is credited with being the first useful +apparatus for raising water by the combustion of fuel. There was a +great waste of steam, through imparting heat to the water, but the +feasibility of the all-important principle of accomplishing mechanical +labor with the aid of heat was at last demonstrated. + +As yet, however, the experimenters were not on the track of the +method by which power could be advantageously transferred to outside +machinery. An effort in quite another direction to accomplish this +had been made as early as 1629 by Giovanni Branca, an Italian +mathematician, who had proposed to obtain rotary motion by allowing +a jet of steam to blow against the vanes of a fan wheel, capable of +turning on an axis. In other words, he endeavored to utilize the +principle of the windmill, the steam taking the place of moving air. +The idea is of course perfectly feasible, being indeed virtually that +which is employed in the modern steam turbine; but to put the idea +into practise requires special detailed arrangements of steam jet and +vanes, which it is not strange the early inventor failed to discover. +His experiments appear not to have been followed up by any immediate +successor, and nothing practical came of them, nor was the principle +which he had attempted to utilize made available until long after a +form of steam engine utilizing another principle for the transmission +of power had been perfected. + + +DENIS PAPIN INVENTS THE PISTON ENGINE + +The principle in question was that of causing expanding steam to press +against a piston working tightly in a cylinder, a principle, in short, +with which everyone is familiar nowadays through its utilization in +the ordinary steam engine. The idea of making use of such a piston +appears to have originated with a Frenchman, Denis Papin, a scientific +worker, who, being banished from his own country, was established as +professor of mathematics at the University of Marburg. He conceived the +important idea of transmitting power by means of a piston as early as +1688, and about two years later added the idea of producing a vacuum in +a cylinder, by cooling the cylinder,--the latter idea being, as we have +just seen, the one which Savery put into effect. + +[Illustration: DIAGRAMS OF EARLY ATTEMPTS TO UTILIZE THE POWER OF +STEAM. GIOVANNI BRANCA 1629 GUILLAUME AMONTONS 1699 Two attempts +to give rotation to a mechanical apparatus through the action of +heated air or steam. Nothing practical came of either effort, but the +mechanisms depicted are of historical interest.] + +It will be noted that Papin's invention antedated that of Savery; to +the Frenchman, therefore, must be given the credit of hitting upon two +important principles which made feasible the modern steam engine. Papin +constructed a model consisting of a small cylinder in which a solid +piston worked. In the cylinder beneath the piston was placed a small +quantity of water, which, when the cylinder was heated, was turned +into steam, the elastic force of which raised the piston. The cylinder +was then cooled by removing the fire, when the steam condensed, thus +creating a vacuum in the cylinder, into which the piston was forced by +the pressure of the atmosphere. + +Such an apparatus seems crude enough, yet it incorporates the essential +principles, and required but the use of ingenuity in elaborating +details of the mechanism, to make a really efficient steam engine. +It would appear, however, that Papin was chiefly interested in the +theoretical, rather than in the really practical side of the question, +and there is no evidence of his having produced a working machine of +practical power, until after such machines worked by steam had been +constructed elsewhere. + + +THOMAS NEWCOMEN'S IMPROVED ENGINE + +As has happened so often in other fields, Englishmen were the first +to make practical use of the new ideas. In 1705 Thomas Newcomen, a +blacksmith or ironmonger, and John Cawley, a plumber and glazier, +patented their atmospheric engine, and five years later, in the year +1710, namely, Newcomen had on the market an engine which is described +in the _Report of the Department of Science and Arts of the South +Kensington Museum_, as "the first real pumping engine ever made." + +The same report describes the engine as "a vertical steam cylinder +provided with a piston connected at one end of the beam, having a +pivot or bearing in the middle of its length, and at the other end of +the beam pump rods for working the pump. The cylinder was surrounded +by a second cylinder or jacket, open at the top, and cold water could +be supplied to this outer cylinder at pleasure. The single or working +cylinder could be supplied with steam when desired from a boiler below +it. There was a drain pipe from the bottom of the working cylinder, +and one from the outer cylinder. For the working of the engine steam +was admitted to the working cylinder, so as to fill it and expel all +the air, the piston then being at the top, owing to the weight of the +pump rods being sufficient to lift it; then the steam was shut off and +the drain cocks closed and cold water admitted to the outer cylinder, +so that the steam in the working cylinder condensed, and, leaving a +partial vacuum of pressure of the atmosphere, forced the piston down +and drew up the pump rods, thus making a stroke of the pump. Then the +water was drawn off from the outer cylinder and steam admitted to the +working cylinder before allowing the piston to return to the top of its +stroke, ready for the next down stroke." + +It will be observed that this machine adopts the principle, with only +a change of mechanical details, of the Papin engine just described. A +later improvement made by Newcomen did away with the outer cylinder +for condensing the steam, employing instead an injection of cold water +into the working cylinder itself, thus enabling the engine to work more +quickly. It is said that the superiority of the internal condensing +arrangement was accidentally discovered through the improved working +of an engine that chanced to have an exceptionally leaky piston or +cylinder. Many engines were made on this plan and put into practical +use. + +Another important improvement was made by a connection from the beam +to the cocks or valves, so that the engine worked automatically, +whereas in the first place it had been necessary to have a boy or man +operate the valves,--a most awkward arrangement, in the light of modern +improvements. As the story is told, the duty of opening and closing +the regulating and condensing valves was intrusted to boys called +cock boys. It is said that one of these boys named Humphrey Potter +"wishing to join his comrades at play without exposing himself to the +consequences of suspending the performance of the engine, contrived, by +attaching strings of proper length to the levers which governed the two +cocks, to connect them with the beam, so that it should open and close +the cocks as it moved up and down with the most perfect regularity." + +This story has passed current for almost two centuries, and it has been +used to point many a useful moral. It seems almost a pity to disturb +so interesting a tradition, yet it must have occurred to more than one +iconoclast that the tale is almost too good to be true. And somewhat +recently it has been more than hinted that Desaguliers, with whom the +story originated, drew upon his imagination for it. A print is in +existence, made so long ago as 1719, representing an engine erected +by Newcomen at Dudley Castle, Staffordshire, in 1712, in which an +automatic valve gear is clearly shown, proving that the Newcomen engine +was worked automatically at this early period. That the admirable +story of the inventive youth, whose wits gave him leisure for play, +may not be altogether discredited, however, it should be added that +unquestionably some of the early engines had a hand-moved gear, and +that at least one such was still working in England after the middle of +the nineteenth century. It seems probable, then, that the very first +engines were without the automatic valve gear, and there is no inherent +reason why a quick-witted youth may not have been the first to discover +and remedy the defect. + +According to the Report of the Department of Science and Arts of +the South Kensington Museum: "The adoption of Newcomen's engine was +rapid, for, commencing in 1711 with the engine at Wolverhampton, of +twenty-three inch diameter and six foot stroke, they were in common use +in English collieries in 1725; and Smeaton found in 1767 that, in the +neighborhood of Newcastle alone there were fifty-seven at work, ranging +in size from twenty-eight inch to seventy-five inch cylinder diameter, +and giving collectively about twelve hundred horse-power. As Newcomen +obtained an evaporation of nearly eight pounds of water per pound of +coal, the increase of boiler efficiency since his time has necessarily +been but slight, although in other requisites of the steam generator +great improvements are noticeable." + +[Illustration: A MODEL OF THE NEWCOMEN ENGINE. + +This engine has particular interest not only because it was a practical +pumping engine, but also because it was while repairing an engine of +this type that Watt was led to the experiments that resulted in his +epoch-making discovery.] + + +THE COMING OF JAMES WATT + +The Newcomen engine had low working efficiency as compared with the +modern engine; nevertheless, some of these engines are still used in a +few collieries where waste coal is available, the pressure enabling the +steam to be generated in boilers unsafe for other purposes. The great +importance of the Newcomen engine, however, is historical; for it was +while engaged in repairing a model of one of these engines that James +Watt was led to invent his plan of condensing the steam, not in the +working cylinder itself, but in a separate vessel,--the principle upon +which such vast improvements in the steam engine were to depend. + +It is impossible to overestimate the importance of the work which Watt +accomplished in developing the steam engine. Fully to appreciate it, +we must understand that up to this time the steam engine had a very +limited sphere of usefulness. The Newcomen engine represented the +most developed form, as we have seen; and this, like the others that +it had so largely superseded, was employed solely for the pumping of +water. In the main, its use was confined to mines, which were often +rendered unworkable because of flooding. We have already seen that a +considerable number of engines were in use, yet their power in the +aggregate added but a trifle to man's working efficiency, and the work +that they did accomplish was done in a most uneconomical manner. Indeed +the amount of fuel required was so great as to prohibit their use in +many mines, which would have been valuable could a cheaper means have +been found of freeing them from water. Watt's inventions, as we shall +see, accomplished this end, as well as various others that were not +anticipated. + +It was through consideration of the wasteful manner of action of the +steam engine that Watt was led to give attention to the subject. +The great inventor was a young man at the University of Glasgow. He +had previously served an apprenticeship of one year with a maker of +philosophical instruments in London, but ill health had prevented him +from finishing his apprenticeship, and he had therefore been prohibited +from practising his would-be profession in Glasgow. Finally, however, +he had been permitted to work under the auspices of the University; +and in due course, as a part of his official duties, he was engaged +in repairing a model of the Newcomen engine. This incident is usually +mentioned as having determined the line of Watt's future activity. + +It should be recalled, however, that Watt had become a personal friend +of the celebrated Professor Black, the discoverer of latent heat, and +the foremost authority in the world, in this period, on the study of +pneumatics. Just what share Black had in developing Watt's idea, or +in directing his studies toward the expansive properties of steam, +it would perhaps be difficult to say. It is known, however, that the +subject was often under discussion; and the interest evinced in it by +Black is shown by the fact that he subsequently wrote a history of +Watt's inventions. + +It is never possible, perhaps, for even the inventor himself to re-live +the history of the growth of an idea in his own mind. Much less is it +possible for him to say precisely what share of his progress has been +due to chance suggestions of others. But it is interesting, at least, +to recall this association of Watt with the greatest experimenter of +his age in a closely allied field. Questions of suggestion aside, +it illustrates the technical quality of Watt's mind, making it +obvious that he was no mere ingenious mechanic, who stumbled upon his +invention. He was, in point of fact, a carefully trained scientific +experimenter, fully equipped with all the special knowledge of his time +in its application to the particular branch of pneumatics to which he +gave attention. + +The first and most obvious defect in the Newcomen engine was, as Watt +discovered, that the alternating cooling and heating of the cylinder +resulted in an unavoidable waste of energy. The apparatus worked, it +will be recalled, by the introduction of steam into a vertical cylinder +beneath the piston, the cylinder being open above the piston to admit +the air. The piston rod connected with a beam suspended in the middle, +which operated the pump, and which was weighted at one end in order +to facilitate the raising of the piston. The steam, introduced under +low pressure, scarcely more than counteracted the pressure of the air, +the raising of the piston being largely accomplished by the weight in +question. + +Of course the introduction of the steam heated the cylinder. In order +to condense the steam and produce a vacuum, water was injected, the +cylinder being thereby cooled. A vacuum being thus produced beneath +the cylinder, the pressure of the air from above thrust the cylinder +down, this being the actual working agent. It was for this reason +that the Newcomen engine was called, with much propriety, a pneumatic +engine. The action of the engine was very slow, and it was necessary to +employ a very large piston in order to gain a considerable power. + +The first idea that occurred to Watt in connection with the probable +improvement of this mechanism did not look to the alteration of any of +the general features of the structure, as regards size or arrangement +of cylinder, piston, or beam, or the essential principle upon which +the engine worked. His entire attention was fixed on the discovery +of a method by which the loss of heat through periodical cooling of +the cylinder could be avoided. We are told that he contemplated the +subject long, and experimented much, before he reached a satisfactory +solution. Naturally enough his attention was first directed toward the +cylinder itself. He queried whether the cylinder might not be made of +wood, which, through its poor conduction of heat, might better equalize +the temperature. Experiments in this direction, however, produced no +satisfactory result. + +[Illustration: WATT'S EARLIEST TYPE OF PUMPING ENGINE. + +The lower figure shows the ruins of Watt's famous engine "Old Bess." +The upper figure shows a reconstructed model of the "Old Bess" engine. +It will be noted that the walking beam is precisely of the Newcomen +type. In fact, the entire engine is obviously only a modification +of the Newcomen engine. It had, however, certain highly important +improvements, as described in the text.] + +Then at last an inspiration came to him. Why not connect the cylinder +with another receptacle, in which the condensation of the steam could +be effected? The idea was a brilliant one, but neither its originator +nor any other man of the period could possibly have realized its vast +and all-comprehending importance. For in that idea was contained the +germ of all the future of steam as a motive power. Indeed, it scarcely +suffices to speak of it as the germ merely; the thing itself was +there, requiring only the elaboration of details to bring it to +perfection. + +Watt immediately set to work to put his brilliant conception of the +separate condenser to the test of experiment. He connected the cylinder +of a Newcomen engine with a receptacle into which the steam could be +discharged after doing its work on the piston. The receptacle was +kept constantly cooled by a jet of water, this water and the water +of condensation, together with any air or uncondensed steam that +might remain in the receptacle, being constantly removed with the +aid of an air pump. The apparatus at once demonstrated its practical +efficiency,--and the modern steam engine had come into existence. + +It was in the year 1765, when Watt was twenty-nine years old, that he +made his first revolutionary experiment, but his first patents were +not taken out until 1769, by which time his engine had attained a +relatively high degree of perfection. In furthering his idea of keeping +the cylinder at an even temperature, he had provided a covering for it, +which might consist of wood or other poorly conducting material, or a +so-called jacket of steam--that is to say, a portion of steam admitted +into the closed chamber surrounding the cylinder. Moreover, the +cylinder had been closed at the top, and a portion of steam admitted +above the piston, to take the place of the atmosphere in producing the +down stroke. This steam above the piston, it should be explained, did +not connect with the condensing receptacle, so the engine was still +single-acting; that is to say it performed work only during one stroke +of the piston. A description of the mechanism at this stage of its +development may best be given in the words of the inventor himself, as +contained in his specifications in the application for patent on his +improvements in 1769. + +"My method of lessening the consumption of steam, and consequently +fuel, in fire-engines, consists of the following principles: + +"First, That vessel in which the powers of steam are to be employed to +work the engine, which is called the cylinder in common fire-engines, +and which I call the steam vessel, must, during the whole time the +engine is at work, be kept as hot as the steam that enters it; first +by enclosing it in a case of wood, or any other materials that +transmit heat slowly; secondly, by surrounding it with steam or other +heated bodies; and, thirdly, by suffering neither water nor any other +substance colder than the steam to enter or touch it during that time. + +"Secondly, In engines that are to be worked wholly or partially +by condensation of steam, the steam is to be condensed in vessels +distinct from the steam vessels or cylinders, although occasionally +communicating with them; these vessels I call condensers; and, whilst +the engines are working, these condensers ought at least to be kept as +cold as the air in the neighborhood of the engines, by application of +water or other cold bodies. + +"Thirdly, Whatever air or other elastic vapor is not condensed by the +cold of the condenser, and may impede the working of the engine, is to +be drawn out of the steam vessels or condensers by means of pumps, +wrought by the engines themselves, or otherwise. + +"Fourthly, I intend in many cases to employ the expansive force of +steam to press on the pistons, or whatever may be used instead of them, +in the same manner in which the pressure of the atmosphere is now +employed in common fire-engines. In cases where cold water can not be +had in plenty, the engines may be wrought by this force of steam only, +by discharging the steam into the air after it has done its office. + +"Sixthly, I intend in some cases to apply a degree of cold not capable +of reducing the steam to water, but of contracting it considerably, +so that the engines shall be worked by the alternate expansion and +contraction of the steam. + +"Lastly, Instead of using water to render the pistons and other parts +of the engine air-and steam-tight, I employ oils, wax, resinous bodies, +fat of animals, quicksilver and other metals in their fluid state." + + +ROTARY MOTION + +It must be understood that Watt's engine was at first used exclusively +as an apparatus for pumping. For some time there was no practical +attempt to apply the mechanism to any other purpose. That it might +be so applied, however, was soon manifest, in consideration of the +relative speed with which the piston now acted. It was not until 1781, +however, that Watt's second patent was taken out, in which devices are +described calculated to convert the reciprocating motion of the piston +into motion of rotation, in order that the engine might drive ordinary +machinery. + +It seems to be conceded that Watt was himself the originator of the +idea of making the application through the medium of a crank and +fly-wheel such as are now universally employed. But the year before +Watt took out his second patent, another inventor named James Picard +had patented this device of crank and connecting rod, having, it is +alleged, obtained the idea from a workman in Watt's employ. Whatever +be the truth as to this point, Picard's patent made it necessary for +Watt to find some alternative device, and after experimenting, he hit +upon the so-called sun and planet gearing, and henceforth this was used +on his rotary engines until the time for the expiration of Picard's +patent, after which the simpler and more satisfactory crank and +fly-wheel were adopted. + +In the meantime, Watt had associated himself with a business partner +named Boulton, under the firm name of Boulton and Watt. In 1776 a +special act of legislation extending the term of Watt's original patent +for a period of twenty-five years had been secured. All infringements +were vigorously prosecuted, and the inventor, it is gratifying to +reflect, shared fully in the monetary proceeds that accrued from his +invention. + +[Illustration: WATT'S ROTATIVE ENGINE. + +The lower figure shows the earliest type of mechanism through which +Watt applied his engine to other uses than that of pumping. The +so-called sun-and-planet gearing, through which rotary motion was +attained, is seen at the lower right-hand corner of the figure. The +upper figure shows a later and much improved type of the Watt engine, +in which the sun-and-planet gearing has been supplanted by a simple +crank.] + +Notwithstanding the early recognition of the possibility of securing +rotary motion with Watt's perfected Newcomen engine, it was long +before the full possibilities of the application of this principle +were realized, even by the most practical of machinists. Watt himself +apparently appreciated the possibilities no more fully than the +others, as the use of his famous engines "Beelzebub" and "Old Bess" +in the establishment of Boulton and Watt amply testifies. It appears +that Boulton had been an extensive manufacturer of ornamental metal +articles. To drive his machinery at Soho he employed two large water +wheels, twenty-four feet in diameter and six feet wide. These sufficed +for his purpose under ordinary conditions, but in dry weather from +six to ten horses were required to aid in driving the machinery. When +Watt's perfected engine was available, however, this was utilized to +pump water from the tail race back to the head race, that it might be +used over and over. "Old Bess" had a cylinder thirty-three inches in +diameter with seven-foot stroke, operating a pump twenty-four inches +in diameter; it therefore had remarkable efficiency as a pumping +apparatus. But of course it utilized, at best, only a portion of the +working energy contained in the steam; and the water wheels in turn +could utilize not more than fifty per cent. of the store of energy +which the pump transferred to the water in raising it. Therefore, such +use of the steam engine involved a most wasteful expenditure of energy. + +It was long, however, before the practical machinists could be made to +believe that the securing of direct rotary power from the piston could +be satisfactorily accomplished. It was only after the introduction of +higher speed and heavier fly-wheels, together with improved governors, +that the speed of rotation was so equalized as to meet satisfactorily +the requirements of the practical engineer, and ultimately to displace +the wasteful method of securing rotary motion indirectly through the +aid of pump and water wheel. It may be added, that the centrifugal +governor, with which modern engines are provided to regulate their +speed, was the invention of Watt himself. + + +FINAL IMPROVEMENTS AND MISSED OPPORTUNITIES + +In the year 1782 Watt took out patents which contained specifications +for the two additional improvements that constituted his final +contribution to the production of the steam engine. The first of these +provided for the connection of the cylinder chamber on each side of the +piston with the condenser, so that the engine became double acting. The +second introduced the very important principle,--from the standpoint of +economy in the use of steam--of shutting off the supply of steam from +the cylinder while the piston has only partially traversed its thrust, +and allowing the remainder of the thrust to be accomplished through +the expansion of the steam. The application of the first of these +principles obviously adds greatly to the efficiency of the engine, and +in practise it was found that the application of the second principle +produces a very great saving in steam, and thus adds materially to the +economical working of the engine. + +All of Watt's engines continued to make use of the walking beam +attached to the piston for the transmission of power; and engineers +were very slow indeed to recognize the fact that in many--in fact in +most--cases this contrivance may advantageously be done away with. The +recognition of this fact constitutes one of the three really important +advances that have been made in the steam engine since the time of +Watt. The other two advances consist of the utilization of steam under +high pressure, and of the introduction of the principle of the compound +engine. + +Neither of these ideas was unknown to Watt, since the utilization +of steam under high pressure was advocated by his contemporary, +Trevithick, while the compound engine was invented by another +contemporary named Hornblower. Perhaps the very fact that these rival +inventors put forward the ideas in question may have influenced Watt +to antagonize them; in particular since his firm came into legal +conflict with each of the other inventors. At any rate, Watt continued +to the end of his life to be an ardent advocate of low pressure for +the steam engine, and his firm even attempted to have laws passed +making it illegal--on the ground of danger to human life--to utilize +high-pressure steam, such as employed by Trevithick. + +Possibly the conservatism of increasing age may also have had its +share in rendering Watt antagonistic to the new ideas; for he was +similarly antagonistic to the idea of applying steam to the purposes +of locomotion. Trevithick, among others, had, as we shall see in due +course, made such application with astonishing success, producing +a steam automobile which traversed the highway successfully. In +his earlier years Watt had conceived the same idea, and had openly +expressed his opinion that the steam engine might be used for this +purpose. But late in life he was so antipathetic to the idea that he +is said to have put a clause in the lease of his house, providing that +no steam carriage should under any pretext be allowed to approach it. + +These incidents have importance as showing--as we shall see illustrated +again and again in other fields--the disastrous influence in retarding +progress that may be exercised by even the greatest of scientific +discoverers, when authority well earned in earlier years is exercised +in an unfortunate direction later in life. But such incidents as +these are inconsequential in determining the position among the +world's workers of the man who was almost solely responsible for the +transformation of the steam engine from an expensive and relatively +ineffective pumping apparatus, to the great central power that has ever +since moved the major part of the world's machinery. + + +THE SUPREME IMPORTANCE OF WATT + +It is speaking well within bounds to say that no other invention +within historical times has had so important an influence upon the +production of property--which, as we have seen, is the gauge of the +world's work--as this invention of the steam engine. We have followed +the history of that invention in some detail, because of its supreme +importance. To the reader who was not previously familiar with that +history, it may seem surprising that after a lapse of a little over +a century one name and one alone should be popularly remembered in +connection with the invention; whereas in point of fact various workers +had a share in the achievement, and the man whose name is remembered +was among the last to enter the field. We have seen that the steam +engine existed as a practical working machine several decades before +Watt made his first invention; and that what Watt really accomplished +was merely the perfecting of an apparatus which already had attained a +considerable measure of efficiency. + +There would seem, then, to be a certain lack of justice in ascribing +supreme importance to Watt in connection with the steam engine. Yet +this measure of injustice we shall find, as we examine the history of +various inventions, to be meted always by posterity in determining the +status of the men whom it is pleased to honor. One practical rule, and +one only, has always determined to whom the chief share of glory shall +be ascribed in connection with any useful invention. + +The question is never asked as to who was the originator of the idea, +or who made the first tentative efforts towards its utilization,--or, +if asked by the historical searcher, it is ignored by the generality of +mankind. + +So far as the public verdict, which in the last resort determines +fame, is concerned, the one question is, Who perfected the apparatus +so that it came to have general practical utility? It may be, and +indeed it usually is the case, that the man who first accomplished the +final elaboration of the idea, made but a comparatively slight advance +upon his predecessors; the early workers produced a machine that was +_almost_ a success; only some little flaw remained in their plans. Then +came the perfecter, who hit upon a device that would correct this last +defect,--and at last the mechanism, which hitherto had been only a +curiosity, became a practical working machine. + +In the case of the steam engine, it might be said that even a smaller +feat than this remained to be accomplished when Watt came upon the +scene; since the Newcomen engine was actually a practical working +apparatus. But the all-essential thing to remember is that this +Newcomen engine was used for a single purpose. It supplied power for +pumping water, and for nothing else. Neither did it have possibilities +much beyond this, until the all-essential modification was suggested by +Watt, of exhausting its steam into exterior space. + +This modification is in one sense a mere detail, yet it illustrates +once more the force of Michelangelo's famous declaration that trifles +make perfect; for when once it was tested, the whole practical +character of the steam engine was changed. From a wasteful consumer of +fuel, capable of running a pump at great expense, it became at once a +relatively economical user of energy, capable of performing almost any +manner of work. + +Needless to say, its possibilities in this direction were not +immediately realized, in theory or in practise; yet the conquest that +it made of almost the entire field of labor resulted in the most +rapid transformation of industrial conditions that the world has ever +experienced. After all, then, there is but little injustice in that +public verdict which remembers James Watt as the inventor, rather than +as the mere perfecter, of the steam engine. + + +THE PERSONALITY OF JAMES WATT + +The man who occupies this all-important position in the industrial +world demands a few more words as to his personality. His work we have +sufficiently considered, but before we pass on to the work of his +successors, it will be worth our while to learn something more of the +estimate placed upon the man himself. Let us quote, then, from some +records written by men who were of the same generation. + +"Independently of his great attainments in mechanics, Mr. Watt was +an extraordinary and in many respects a wonderful man. Perhaps no +individual in his age possessed so much, or remembered what he had read +so accurately and well. He had infinite quickness of apprehension, a +prodigious memory, and a certain rectifying and methodizing power of +understanding which extracted something precious out of all that was +presented to it. His stores of miscellaneous knowledge were immense, +and yet less astonishing than the command he had at all times over +them. It seemed as if every subject that was casually started in +conversation had been that which he had been last occupied in studying +and exhausting; such was the copiousness, the precision, and the +admirable clearness of the information which he poured out upon it +without effort or hesitation. Nor was this promptitude and compass of +knowledge confined, in any degree, to the studies connected with his +ordinary pursuits. + +"That he should have been minutely and extensively skilled in +chemistry, and the arts, and in most of the branches of physical +science, might, perhaps, have been conjectured; but it could not have +been inferred from his usual occupations, and probably is not generally +known, that he was curiously learned in many branches of antiquity, +metaphysics, medicine, and etymology, and perfectly at home in all +the details of architecture, music, and law. He was well acquainted, +too, with most of the modern languages, and familiar with their most +recent literature. Nor was it at all extraordinary to hear the great +mechanician and engineer detailing and expounding, for hours together, +the metaphysical theories of the German logicians, or criticizing the +measures or the matter of the German poetry. + +"It is needless to say, that with those vast resources, his +conversation was at all times rich and instructive in no ordinary +degree. But it was, if possible, still more pleasing than wise, and +had all the charms of familiarity, with all the substantial treasures +of knowledge. No man could be more social in his spirit, less assuming +or fastidious in his manners, or more kind and indulgent towards +all who approached him. His talk, too, though overflowing with +information, had no resemblance to lecturing, or solemn discoursing; +but, on the contrary, was full of colloquial spirit and pleasantry. +He had a certain quiet and grave humor, which ran through most of his +conversation, and a vein of temperate jocularity, which gave infinite +zest and effect to the condensed and inexhaustible information which +formed its main staple and characteristic. There was a little air of +affected testiness, and a tone of pretended rebuke and contradiction, +which he used towards his younger friends, that was always felt by +them as an endearing mark of his kindness and familiarity, and prized +accordingly, far beyond all the solemn compliments that proceeded from +the lips of authority. His voice was deep and powerful; though he +commonly spoke in a low and somewhat monotonous tone, which harmonized +admirably with the weight and brevity of his observations, and set off +to the greatest advantage the pleasant anecdotes which he delivered +with the same grave tone, and the same calm smile playing soberly on +his lips. + +[Illustration: JAMES WATT.] + +"There was nothing of effort, indeed, or of impatience, any more than +of pride or levity, in his demeanor; and there was a finer expression +of reposing strength, and mild self-possession in his manner, than we +ever recollect to have met with in any other person. He had in his +character the utmost abhorrence for all sorts of forwardness, parade, +and pretension; and indeed never failed to put all such impostors out +of countenance, by the manly plainness and honest intrepidity of his +language and deportment. + +"He was twice married, but has left no issue but one son, associated +with him in his business and studies, and two grandchildren by a +daughter who predeceased him. He was fellow of the Royal Societies both +of London and Edinburgh, and one of the few Englishmen who were elected +members of the National Institute of France. All men of learning and +of science were his cordial friends; and such was the influence of his +mild character, and perfect fairness and liberality, even upon the +pretender to these accomplishments, that he lived to disarm even envy +itself, and died, we verily believe, without a single enemy." + + + + +VI + +THE MASTER WORKER + + +We have already pointed out at some length that, in the hands of Watt, +the steam engine came at once to be a relatively perfect apparatus, and +that only three really important modifications have been applied to it +since the day of its great perfecter. These modifications, as already +named, are the doing away with the walking beam, the utilization of +high pressure steam, and the development of the compound engine. Each +of these developments requires a few words of explanation. + +The retention of the heavy walking beam for so long a time after the +steam engine of Watt had been applied to the various purposes of +machinery, illustrates the power of a pre-conceived idea. With the +Newcomen engine this beam was an essential, since it was necessary +to have a weight to assist in raising the piston. But with the +introduction of steam rather than air as the actual power to push the +piston, and in particular with the elaboration of the double-chamber +cylinder, with steam acting equally on either side of the piston, the +necessity for retaining this cumbersome contrivance no longer existed. +Yet we find all the engines made by Watt himself, and nearly all those +of his contemporaries, continuing to utilize this means of transmitting +the power of the piston. Even the road locomotive, as illustrated by +that first wonderful one of Trevithick's and such colliery locomotives +as "Puffing Billy" and "Locomotion," utilized the same plan. It was not +until almost a generation later that it became clear to the mechanics +that in many cases, indeed in most cases, this awkward means of +transmitting power was really a needlessly wasteful one, and that with +the aid of fly-wheel and crank-shaft the thrust of the piston might be +directly applied to the wheel it was destined to turn, quite as well as +through the intermediary channel of the additional lever. + +The utility of the beam has, indeed, still commended it for certain +purposes, notably for the propulsion of side-wheel steamers, such as +the familiar American ferryboat. But aside from such exceptional uses, +the beam has practically passed out of existence. + +There was no new principle involved in effecting this change. It was +merely another illustration of the familiar fact that it is difficult +to do things simply. As a rule, inventors fumble for a long time with +roundabout and complex ways of doing things, before a direct and simple +method occurs to them. In other words, the highest development often +passes from the complex to the simple, illustrating, as it were, an +oscillation in the great law of evolution. So in this case, even so +great an inventor as Watt failed to see the utility of doing away with +the cumbersome structure which his own invention had made no longer +a necessity, but rather a hindrance to the application of the steam +engine. However, a new generation, no longer under the thraldom of +the ideas of the great inventor, was enabled to make the change, +gradually, but in the end effectively. + + +HIGH-PRESSURE STEAM + +As regards the use of steam under high pressure, somewhat the same +remarks apply, so far as concerns the conservatism of mankind, and +the influence which a great mind exerts upon its generation. Just why +Watt should have conceived an antagonism to the idea of high-pressure +steam is not altogether clear. It has been suggested, indeed, that +this might have been due to the fact that a predecessor of Watt had +invented a high-pressure engine which did not use the principle of +condensation, but exhausted the steam into open space. As early as +1725, indeed, Leupold in his _Theatrum Machinarum_, had described +such a non-condensing engine, which, had it been made practically +useful, would have required a high pressure of steam. Partly through +the influence of this work, perhaps, there came to be an association +between the words high pressure and non-condensing, so that these terms +are considered to be virtually synonymous; and since Watt's great +contribution consisted of an application of the idea of condensation, +he was perhaps rendered antagonistic to the idea of high pressure, +through this psychological suggestion. In any event, the antagonism +unquestionably existed in his mind; though it has often enough been +pointed out that this seems the more curious since high-pressure steam +would so much better have facilitated the application of that other +famous idea of Watt, the use of the expansive property of steam. + +Curiously enough, however, the influence of Watt led to experiments +in high-pressure steam through an indirect channel. The contemporary +inventor, Trevithick, in connection with his partner, Bull, had made +direct-acting pumping engines with an inverted cylinder, fixed in line +with the pump rod, and actually dispensing with the beam. But as these +engines used a jet of cold water in the exhaust pipe to condense the +steam, Boulton and Watt brought suit successfully for infringement of +their patent, and thus prevented Trevithick from experimenting further +in that direction. He was obliged, therefore, to turn his attention to +a different method, and probably, in part at least, in this way was +led to introduce the non-condensing, relatively high-pressure engine. +This was used about the year 1800. At the same time somewhat similar +experiments were made by Oliver Evans in America. + +Both Trevithick and Evans applied their engines to the propulsion of +road vehicles; and Trevithick is credited with being the first man +who ran a steam locomotive on a track,--a feat which he accomplished +as early as the year 1804. We are not here concerned with the details +of this accomplishment, which will demand our attention in a later +chapter, when we come to discuss the entire subject of locomotive +transportation. But it is interesting to recall that the possibilities +of the steam engine were thus early realized, even though another +generation elapsed before they were finally demonstrated to the +satisfaction of the public. It is particularly interesting to note that +in his first locomotive engine, Trevithick allowed the steam exhaust +to escape into the funnel of the engine to increase the draught,--an +expedient which was so largely responsible for Stephenson's success +with his locomotive twenty years later, and which retains its utility +in the case of the most highly developed modern locomotive. + +Trevithick was, however, entirely subordinated by the great +influence of Watt, and the use of high pressure was in consequence +discountenanced by the leading mechanical engineers of England for some +decades. Meantime, in America, the initiative of Evans led to a much +earlier general use of high-pressure steam. In due course, however, the +advantages of steam under high pressure became evident to engineers +everywhere, and its conquest was finally complete. + +The essential feature of super-heated steam is that it contains, as +the name implies, an excess of heat beyond the quantity necessary to +produce mere vaporization, and that the amount of water represented +in this vapor is not the maximum possible under given conditions. In +other words, the vapor is not saturated. It has been already explained +that the amount of vapor that can be taken up in a given space under a +given pressure varies with the temperature of the space. Under normal +conditions, when a closed space exists above a liquid, evaporation +occurs from the surface of the liquid until the space is saturated, +and no further evaporation can occur so long as the temperature and +pressure are unchanged. If now the same space is heated to a higher +degree, more vapor will be taken up until again the point of saturation +is attained. But, obviously, if the space were disconnected with the +liquid, and then heated, it would acquire a capacity to take up more +vapor, and so long as this capacity was latent, the vapor present would +exist in a super-heated condition. + +[Illustration: OLD IDEAS AND NEW APPLIED TO BOILER CONSTRUCTION. + +The lower figure shows Robert Trevithick's famous boiler, used in +operating his locomotive about the year 1804. The original is preserved +in the South Kensington Museum, London. The upper figure shows a modern +tubular boiler, by way of contrast.] + +It will be understood from what has been said before, that with all +accessions of heat, the expansive power of the vapor is increased,--its +molecules becoming increasingly active; hence one of the very obvious +advantages of super-heated steam for the purpose of pushing a piston. +There are other advantages, however, which are not at first sight +so apparent, having to do with the properties of condensation. To +understand these, we must pay heed for a few moments to the changes +that take place in steam itself in the course of its passage through +the cylinder, where it performs its work upon the piston. + +Many of these changes were not fully understood by the earlier +experimenters, including Watt. Indeed the theory of the steam engine, +or rather the general theory of the heat engine, was not worked out +until the year 1824, when the Frenchman Carnot took the subject in +hand, and performed a series of classical experiments, which led to a +nearly complete theoretical exposition of the subject. It remained, +however, for the students of thermo-dynamics, about the middle of the +nineteenth century, with Clausius and Rankine at their head, to perfect +the theory of the steam engine, and the general subject of the mutual +relations of heat and mechanical work. + +We are not here concerned with any elaboration of details, but merely +with a few of the essential principles which enter practically into +the operation of the steam engine. It appears, then, that when steam +enters the cylinder and begins to thrust back the piston of the steam +engine, a portion of the steam is immediately condensed on the walls +of the cylinder, owing to the fact that previous condensation of steam +has cooled these walls to a certain extent. We have already pointed +out that Watt endeavored in his earlier experiments to overcome this +difficulty, by equalizing the temperature of the cylinder walls to the +greatest practicable extent. + +Notwithstanding his efforts, however, and those of numberless later +experimenters, it still remains true that under ordinary conditions, +particularly if steam enters the cylinder at the saturation point, +a very considerable condensation occurs. Indeed this may amount to +from thirty to fifty per cent. of the entire bulk of water contained +in the quantity of steam that enters the cylinder. This condensation +obviously militates against the expansive or working power of the +steam. But now as the steam expands, pushing forward the cylinder, it +becomes correspondingly rarefied, and immediately a portion of the +condensed steam becomes again vaporized, and in so doing it takes up +a certain amount of heat and renders it latent. This disadvantageous +cycle of molecular transformations is very much modified in the case of +super-heated steam, for the obvious reason that such steam may be very +much below the saturation point, and hence requires a very much greater +lowering of temperature in order to produce condensation of any portion +of its mass. Without elaborating details, it suffices to note that in +all highly efficient modern engines, steam is employed at a relatively +high pressure, and that sometimes this pressure becomes enormous. + + +COMPOUND ENGINES + +As to the compound engine, that also, as has been pointed out, was +invented by a contemporary of Watt, Jonathan Hornblower by name, whose +patent bears date of 1781. In Hornblower's engine, steam was first +admitted to a small cylinder, and then, after performing its work on +the piston, was allowed to escape, not into a condensing receptacle, +but into a larger cylinder where it performed further work upon another +piston. This was obviously an instance of the use of steam expansively, +and it has been pointed out that, in consequence, Hornblower was +the first to make use of this idea in practise, although it is said +that Watt's experiments had even at that time covered this field. +The application of the idea to the movement of the second cylinder, +however, appears to have been original with Hornblower. Certainly it +owed nothing to Watt, who refused to accept the idea, and continued +throughout his life to frown upon the compound engine. + +Nevertheless, the device had great utility, as subsequent experiments +were very fully to demonstrate. The compound engine was revived by +Woolf in 1804, and his name rather than Hornblower's is commonly +associated with it. The latter experimenter demonstrated that the +compound engine has two important merits as against the simple engine. +One of these is that the sum of the two forces exerted by the joint +action results in a more even and continuous pressure throughout the +cycle than could be accomplished by the action of a single cylinder. + +To understand this it must be recalled that when using the expansive +property of steam, the piston thrust could not possibly be uniform, +since the greatest pressure exerted by the steam would be exerted at +the moment before it was shut off from the boiler, and its pressure +must then decrease progressively, as it exerts more and more work upon +the piston and becomes more expanded, thus obviously retaining less +elastic energy. The operation of the fly-wheel largely compensates +this difference of pressure in practise, but it would be obviously +advantageous could the pressure be equalized; and, as just stated, the +compound engine tends to produce this result. + +The second, and perhaps the more important merit of the compound +engine is, that it is found in practise to keep the cylinders at a +more uniform temperature. A moment's reflection makes it clear why +this should be the case, since in a single-cylinder engine the exhaust +connects with the cool condenser, whereas in the compound engine the +exhaust from the first cylinder connects with the second cylinder at +only slightly lower temperature. + +In many modern engines a third cylinder and sometimes even a fourth +is added, constituting what are called respectively triple-expansion +and quadruple-expansion engines. The triple-expansion system is very +generally employed, especially where it is peculiarly desirable to +economize fuel, as, for example, in the case of ships. + +[Illustration: COMPOUND ENGINES. + +The lower figure illustrates the use of a modern compound engine, +directly operating the propeller shaft of a steamship. The middle +figure shows a similarly direct application of power to the axes of +paddle wheels. The upper figure shows the application of power through +a walking beam similar in principle to that of the original Newcomen +and Watt engines.] + + +ROTARY ENGINES + +All these improvements, it will be observed, have to do with details +that do not greatly modify the steam engine from the original type. The +cylinder with its closely fitting piston, as introduced in the Newcomen +engine, is retained and constitutes the essential mechanism through +which the energy of steam is transferred into mechanical energy. But +from a comparatively remote period the idea has prevailed that it might +be possible to utilize a different principle; that, in short, if the +steam instead of being made to press against a piston were allowed +to rush against fan-like blades, adjusted to an axle, it might cause +blades and axle to revolve, precisely as a windmill is made to revolve +by the pressure of the wind, or the turbine wheel by the pressure of +water. + +In a word, it has been believed that a turbine engine might be +constructed, which would utilize the energy of the steam as +advantageously as it is utilized in the piston engine, and at the same +time would communicate its power as a direct rotation, instead of as a +straight thrust that must be translated into a rotary motion by means +of a crank or other mechanism. + +In point of fact, James Watt himself invented such an engine, and +patented it in 1782, though there is no evidence that he ever +constructed even a working model. His patent specifications show "a +piston in the form of a closely-fitting radial arm, projecting from an +axial shaft in a cylinder. An abutment, arranged as a flap is hinged +near a recess in the side of the cylinder, and swings while remaining +in contact with the piston. Steam is admitted to the chamber on one +side of the flap, and so causes an unbalanced pressure upon the radial +arm." + +This arrangement has been re-invented several times. Essentially the +same principle is utilized by Joshua Routledge, whose name is well +known in connection with the engineer's slide-rule. A model of this +engine is preserved in the South Kensington Museum, and the apparatus +is described in the catalogue of the Museum as follows: + +"The piston revolves on a shaft passing through the centre of the +cylinder casing. The flap or valve hinged to the casing, with its free +end resting upon the piston, acts like the bottom of an ordinary engine +cylinder. The steam inlet port is on one side of the hinge, and the +exhaust port on the other. The admission of steam is controlled by a +side valve, actuated by an eccentric on the fly-wheel shaft, so that +the engine could work expansively, and the steam pressure resisting the +lifting of the flap would also be greatly reduced, so diminishing the +knock at this point, which, however, would always be a serious cause +of trouble. The exhaust steam passes down to a jet condenser, provided +with a supply of water from a containing tank, from which the injection +is admitted through a regulating valve. The air pump, which draws the +air and water from the condenser and discharges them through a pipe +passing out at the end of the tank, is a rotary machine constructed +like the engine and driven by spur gearing from the fly-wheel shaft. +Some efforts have been made to prevent leakage by forming grooves in +the sides of the revolving piston and filling them with soft packing." + +Sundry other rotary engines, some of them actual working models, are +to be seen at the South Kensington Museum. There is, for example, one +invented by the Rev. Patrick Bell, a gentleman otherwise known to fame +as one of the earliest inventors of a practical reaping machine. In +this apparatus, "A metal disc is secured to a horizontal axis carried +in bearings, and the lower half of the disc is enclosed by a chamber +of circular section having its axis a semi-circle. One end of this +chamber is closed and provided with a pipe through which steam enters, +the exhaust taking place through the open end. The disc is provided +with three holes, each fitted with a circular plate turning on an +axis radial to the disc, and these plates when set at right angles +to the disc become pistons in the lower enclosing chamber. Toothed +gearing is arranged to rotate these pistons into the plane of the disc +on leaving the cylinder and back again immediately after entering, +locking levers retaining them in position during the intervals. The +steam pressure upon these pistons forces the disc round, but the engine +is non-expansive, and although some provision for packing has been +made, the leakage must have been considerable and the wear and tear +excessive." + +It is stated that almost the same arrangement was proposed by Lord +Armstrong in 1838 as a water motor, and that a model subsequently +constructed gave over five horse-power at thirty revolutions per +minute, with an efficiency of ninety-five per cent. + +Another working model of a rotary engine shown at the Museum is one +loaned by Messrs. Fielding and Platt in 1888. "The action of this +engine depends upon the oscillating motion which the cross of a +universal joint has relative to the containing jaws when the system is +rotated. + +"Two shafts are set at an angle of 165 deg. to each other and connected +by a Hooke's joint; one serves as a pivot, the power being taken from +the other. Four curved pistons are arranged on the cross-piece, two +pointing towards one shaft and two towards the other, and on each +shaft or jaw are formed two curved steam cylinders in which the curved +pistons work. The steam enters and leaves the base of each cylinder +through ports in the shaft, which forms a cylindrical valve working in +the bearing as a seating. + +"On the revolution of the shafts the pistons reciprocate in their +cylinders in much the same way as in an ordinary engine, and the +valve arrangement is such that while each piston is receding from its +cylinder the steam pressure is driving it, and during the in-stroke +of each, its cylinder is in communication with the exhaust. There are +thus four single-acting cylinders making each a double stroke for one +revolution of the driving-shaft. The engine has no dead centres, and +has been at 1,000 revolutions per minute." + +[Illustration: ROTARY ENGINES. + +The three types of rotary engines here shown are similar in principle, +and none of them is of great practical value, though the upper figure +shows an engine that has met with a certain measure of commercial +success.] + +It is not necessary to describe other of the rotary engines that have +been made along more or less similar lines by numerous inventors, +models of which are for the most part, as in the case of those just +described, to be seen more commonly in museums than in practical +workshops. Reference may be made, however, to a rotary engine +which was invented by a Mr. Hoffman, of Buffalo, New York, about the +beginning of the twentieth century, an example of which was put into +actual operation in running the machinery of a shop in Buffalo, in 1905. + +This engine consists of a solid elliptical shaft of steel, fastened to +an axle at one side of its centre, which axis is also the shaft of the +cylinder, which revolves about the central ellipse in such a way that +at one part of the revolution the cylinder surface fits tightly against +the ellipse, while the opposite side of the cylinder supplies a free +chamber between the ellipse and the cylinder walls. Running the length +of the cylinder are two curved pieces of steel, like longitudinal +sections of a tube. These flanges are adjusted at opposite sides of +the cylinder and so arranged that their sides at all times press +against the ellipse, alternately retreating into the substance of the +cylinder, and coming out into the free chamber. Steam is admitted to +the free chamber through one end of the shaft of ellipse and cylinder +and exhausted through the other end. The pressure of the steam against +first one end and then the other of the flanges supplies the motive +power. This pressure acts always in one direction, and the entire +apparatus revolves, the cylinder, however, revolving more rapidly than +the central ellipse. + +For this engine the extravagant claim is made that there is no limit +to its speed of revolution, within the limit of resistance of steel +to centrifugal force. It has been estimated that a locomotive might +be made to run two hundred or three hundred miles an hour without +difficulty, with the Hoffman engine. Such estimates, however, are +theoretical, and it remains to be seen what the engine can do in +practise when applied to a variety of tasks, and what are its +limitations. Certainly the apparatus is at once ingenious and simple in +principle, and there is no obvious theoretical reason why it should not +have an important future. + + +TURBINE ENGINES + +Whatever the future may hold, however, it remains true that the first +practical solution of the problem of securing direct rotary motion from +the action of steam, on a really commercial scale, was solved with an +apparatus very different from any of those just described, the inventor +being an Englishman, Mr. C. A. Parsons, and the apparatus the steam +turbine, the first model of which he constructed in 1884, and which +began to attract general attention in the course of the ensuing decade. +Public interest was fully aroused in 1897, when Mr. Parson's boat, the +_Turbinia_, equipped with engines of this type, showed a trial speed +of 32-3/4 knots per hour, a speed never hitherto attained by any other +species of water craft. More recently, a torpedo boat, the _Viper_, +equipped with engines developing about ten thousand horse-power, +attained a speed of 35-1/2 knots. The success of these small boats led +to the equipment of large vessels with the turbine, and on April first, +1905, the first transatlantic liner propelled by this form of engine +steamed into the harbor of Halifax, Nova Scotia. + +This first ocean liner equipped with the turbine engine is called the +_Victorian_. She is a ship five hundred and forty feet long and sixty +feet wide, carrying fifteen hundred passengers. The _Victorian_ had +shown a speed of 19-1/2 knots an hour on her trial trip, and it had +been hoped that she would break the transatlantic record. On her first +trip, however, she encountered adverse winds and seas, and did not +attain great speed. Her performance was, however, considered entirely +satisfactory and creditable. + +In the ensuing half-decade several large ships were equipped with +engines of the same type, the most famous of these being the Cunard +liners, _Carmania_, _Lusitania_, and _Mauretania_. The two last-named +ships are sister craft, and they are the largest boats of any kind +hitherto constructed. The _Lusitania_ was first launched and she +entered immediately upon a record-breaking career, only to be surpassed +within a few months by the _Mauretania_, which soon acquired all +records for speed and endurance. + +Fuller details as to the performance of these vessels will be found in +another place. Here we are of course concerned with the Parsons turbine +engine itself rather than with its applications. + +This turbine engine constitutes the first really important departure +from the old-type steam engine, thus realizing the dream of the +seventeenth-century Italian, Branca, to which reference was made +above. Mr. Parsons' elaboration of the idea developed a good deal of +complexity as regards the number of parts involved, yet his engine +is of the utmost simplicity in principle. It consists of a large +number of series of small blades, each series arranged about a drum +which revolves. Between the rings of revolving blades are adjusted +corresponding rings of fixed blades, which project from the casing +to the cylinder, and by means of which the steam is regulated in +direction, so that it strikes at the proper angle against the revolving +blades of the turbine. + +In practise, three series of cylindrical drums are used, each +containing a large number of rings of blades of uniform size; but each +successive drum having longer blades, to accommodate the greater volume +of the expanding steam. The steam is fed against the first series of +blades in gusts, which may be varied in frequency and length to meet +the requirements of speed. After impinging on the first circle of +blades, the steam passes to the next under slightly reduced pressure, +and the pressure is thus successively stepped down from one set of +blades to another until it is ultimately reduced from say two hundred +pounds to the square inch, to one pound to the square inch before it +passes to the condenser and ceases to act. + +There is thus a fuller utilization of the kinetic energy of the gas, +through carrying it from high to low pressure, than is possible with +the old type of cylinder-and-piston engine. On the other hand, there is +a constant loss due to the fact that the blades of the turbine can not +fit with absolute tightness against the cylinder walls. The net result +is that the compound turbine, as at present developed, appears to have +about the same efficiency as the best engine of the old type. + +One capital advantage of the turbine is that it keeps the cylinder +walls at a more uniform temperature than is possible even with a +compound engine of the old type. Another advantage is that the power +of the turbine is applied directly to cause rotation of the shaft, +whereas no satisfactory means has ever been discovered hitherto of +making the action of the steam engine rotary, except with the somewhat +disadvantageous crank-shaft. This fact of adjustment of the turbine +blades to the revolving shaft seems to make this form of engine +particularly adapted to use in steamships. It is also highly adapted +to revolving the shaft of a dynamo, and has been largely applied to +this use. Needless to say, however, it may be applied to any other +form of machinery. It would be difficult at the present stage of +its development to predict the extent to which the turbine will +ultimately supersede the old type of engine. Its progress has already +been extraordinary, however, as an engineer pointed out in the London +_Times_ of August 14, 1907, in the following words: + +"When the steam turbine was introduced by Mr. Parsons some 25 years +ago, in the form of a little model, which is now in the South +Kensington Museum, and the rotor of which may easily be held stationary +by the hand against the full blast of the steam, who would have been +rash enough to predict, except perhaps the far-seeing inventor himself, +that a vessel 760 feet long, loaded to 37,000 tons displacement, +drawing 32 ft. 9 in. of water, and providing accommodation for 2,500 +people, could be propelled at a speed of 24.5 knots per hour, which it +is hoped she may maintain over the 3,000 miles of the Atlantic voyage? + +"From this small model, which will in time become as historic as the +_Rocket_ of Stephenson, and which is only some few inches in diameter, +the turbine has been developed gradually in size. The cylindrical +casings which take the place of the complicated machinery of the +piston engine in the engine room of the _Lusitania_ contain drums, +which in the high-pressure turbines are 8 feet in diameter and in the +low-pressure 11 ft. 8 in., and from which thousands of curved blades +project, the longest of which are 22 inches, and against which the +steam impinges in its course from the boiler to the condenser. + +"Not only has the steam turbine justified the confidence of those who +have labored so successfully in its development, but no other great +invention has proceeded from the laboratory stage to such an important +position in the engineering world in such a short space of time. This +would not have happened if some inherent drawback, such as lack of +economy in steam consumption, existed, and as the turbine has been +proved to be, for land purposes, very economical, there seems to be +no reason to doubt that marine turbines, working as they do at full +load almost continually, will show likewise that the coal bill is not +increased, but perhaps diminished by their use. + +"The records of the vibrations of the hull which were taken during the +trials by Schlick's instruments showed that the vertical vibration +was 60 per minute on the run, which was due to the propellers, and +which may be further modified. The horizontal vibration was almost +unnoticeable, while the behavior of the ship in the heavy seas she +encountered in her long-distance runs was good, the roll from side to +side having a period of 18 seconds. The great length of this ship and +the gyrostatic action of the heavy rotating masses of the machinery +ought to render her almost insensible to the heaviest Atlantic rollers; +certainly as far as pitching is concerned." + +[Illustration: THE ORIGINAL PARSON'S TURBINE ENGINE AND THE +RECORD-BREAKING SHIP FOR WHICH IT IS RESPONSIBLE. + +This small turbine engine, with which Mr. Parson's early experiments +were made in 1884, is preserved in the South Kensington Museum, London. +At the time when it was made it seemed scarcely more than a toy, and +engineers in general doubted that the principle it employed could ever +be made commercially available. Yet within the lifetime of its inventor +engines built on this model have come to be the most powerful of force +transmuters. The "Mauretania," the largest, and thanks to her turbine +engines the speediest, of ships, is here presented on the same page +with the little original turbine model, as illustrating vividly the +practical development of a seemingly visionary idea.] + +A more general comment upon the turbine engine, with particular +reference to its use in America, is made by Mr. Edward H. Sanborn in an +article on _Motive Power Appliances_, in the Twelfth Census Report of +the United States, Vol. X. part IV. + +"Apart from its demonstrated economy," says Mr. Sanborn, "other +important advantages are claimed for the steam turbine, some of which +are worthy of brief mention. + +"There is an obvious advantage in economy of space as compared with +the reciprocating engine. The largest steam turbine constructed in the +United States is one of 3,000 horse-power, which is installed in the +power house of the Hartford Electric Light Company, Hartford, Conn. The +total weight of this motor is 28,000 pounds, its length over all is 19 +feet 8 inches, and its greatest diameter six feet. With the generator +to which it is directly connected, it occupies a floor space of 33 feet +3 inches long by 8 feet 9 inches wide. + +"Friction is reduced to a minimum in the steam turbine, owing to the +absence of sliding parts and the small number of bearings. The absence +of internal lubrication is also an important consideration, especially +when it is desired to use condensers. + +"As there are no reciprocating parts in a steam turbine, and as a +perfect balance of its rotating parts is absolutely essential to its +successful operation, vibration is reduced to such a small element that +the simplest foundations will suffice, and it is safe to locate steam +turbines on upper floors of a factory if this be desirable or necessary. + +"The perfect balance of the moving parts and the extreme simplicity +of construction tend to minimize the wear and increase the life of a +turbine, and at the same time to reduce the chance of interruption +in its operation through derangement of, or damage to, any of its +essential parts. + +"Although hardly beyond the stage of its first advent in the +motive-power field, the steam turbine has met with much favor, and +there is promise of its wide use for the purposes to which it is +particularly adapted. At present, however, its uses are restricted to +service that is continuous and regular, its particular adaptability +being for the driving of electrical generators, pumps, ventilating +fans, and similar work, especially where starting under load is not +essential. + +"Steam turbines are now being built in the United States in all sizes +up to 3,000 horse-power. Their use abroad covers a longer period and +has become more general. The largest turbines thus far attempted +are those of the Metropolitan District Electric Traction Company, +of London, embracing four units of 10,000 horse-power each. Several +turbines of large size have been operated successfully in Germany." + +It should be added that the compound turbine wheel of Parsons is not +the only turbine wheel that has proved commercially valuable. There +is a turbine consisting of a single ring of revolving blades, the +invention of Dr. Gustav De Laval, which has proved itself capable of +competing with the old type of engine. To make this form of single +turbine operate satisfactorily, it is necessary to have steam under +high pressure, and to generate a very high speed of revolution. In +practice, the De Laval machines sometimes attain a speed of thirty +thousand revolutions per minute. This is a much higher rate of speed +than can advantageously be utilized directly in ordinary machinery, and +consequently the shaft of this machine is geared to another shaft in +such a way as to cause the second shaft to revolve much more slowly. + + + + +VII + +GAS AND OIL ENGINES + + +Just at the time when the type of piston-and-cylinder engine has thus +been challenged, it has chanced that a new motive power has been +applied to the old type of engine, through the medium of heated gas. +The idea of such utilization of a gas other than water vapor is by no +means new, but there have been practical difficulties in the way of the +construction of a commercial engine to make use of the expansive power +of ordinary gases. + +The principle involved is based on the familiar fact that a gas expands +on being heated and contracts when cool. Theoretically, then, all that +is necessary is to heat a portion of air confined in a cylinder, to +secure the advantage of its expansion, precisely as the expansion of +steam is utilized, by thrusting forward a piston. Such an apparatus +constitutes a so-called "caloric" or hot-air engine. As long ago +as the year 1807 Sir G. Cayley in England produced a motor of this +type, in which the heated air passed directly from the furnace to the +cylinder, where it did work while expanding until its pressure was not +greater than that of the atmosphere, when it was discharged. The chief +mechanical difficulty encountered resulted from the necessity for the +employment of very high temperatures; and for a long time the engine +had no great commercial utility. The idea was revived, however, about +three-quarters of a century later and an engine operated on Cayley's +principle was commercially introduced in England by Mr. Buckett. This +engine has a cold-air cylinder above the crank-shaft and a large +hot-air cylinder below, while the furnace is on one side enclosed in an +air-tight chamber. The fuel is supplied as required through a valve and +distributing cone arranged above the furnace and provided with an air +lock in which the fuel is stored. At about the time when this hot-air +engine was introduced, however, gas and oil engines of another and more +important type were developed, as we shall see in a moment. + +Meantime, an interesting effort to utilize the expansive property of +heated air was made by Dr. Stirling in 1826; his engine being one +in which heat was distributed by means of a displacer which moved +the mass of air to and fro between the hot and cold portions of the +apparatus. He also compressed the air before heating it, thus making a +distinct advance in the economy and compactness of the engine. From an +engineering standpoint his design has further interest in that it was +a practical attempt to construct an engine working on the principle +of the theoretically perfect heat engine, in which the cycle of +operations is closed, the same mass of air being used throughout. In +the theoretically perfect heat engine, it may be added, the cycle of +operations may be reversed, there being no loss of energy involved; but +in practice, of course, an engine cannot be constructed to meet this +ideal condition, as there is necessarily some loss through dissipation +of heat. Dr. Stirling's practical engine had its uses, but could not +compete with the steam engine in the general field of mechanical +operations to which that apparatus is applied. + +Another important practical experimenter in the construction of +hot-air engines was John Ericsson, who in 1824 constructed an engine +somewhat resembling the early one of Cayley, and in 1852 built caloric +engines on such a scale as to be adapted to the propulsion of ships. +Notwithstanding the genius of Ericsson, however, engines of this +type did not prove commercially successful on a large scale, and +in subsequent decades the hot-air motors constructed for practical +purposes seldom exceeded one horse-power. Such small engines as +these are comparatively efficient and absolutely safe, and they are +thoroughly adapted for such domestic purposes as light pumping. + +The great difficulty with all these engines operated with heated air +has been, as already suggested, that their efficiency of action is +limited by the difficulties incident to applying high temperatures +to large masses of the gas. There is, however, no objection to the +super-heating of small quantities of gas, and it was early suggested +that this might be accomplished by exploding a gaseous mixture +within a cylinder. It was observed by the experimenters of the +seventeenth century that an ordinary gun constitutes virtually an +internal-combustion engine; and such experimenters as the Dutchman +Huyghens, and the Frenchmen Hautefeuille and Papin, attempted to make +practical use of the power set free by the explosion of gunpowder, +their experiments being conducted about the years 1678 to 1689. +Their results, however, were not such as to give them other than an +historical interest. About a century later, in 1794, the Englishman +Robert Street suggested the use of inflammable gases as explosives, and +ever since that time there have been occasional experimenters along +that line. In 1823 Samuel Brown introduced a vacuum gas engine for +raising water by atmospheric pressure. The first fairly practical gas +engine, however, was that introduced by J. J. E. Lenoir, who in 1850 +proposed an engine working with a cycle resembling that of a steam +engine. His engine patented in 1860 proved to be a fairly successful +apparatus. This engine of Lenoir prepared the way for gas engines that +have since become so enormously important. Its method of action is this: + +"To start the engine, the fly-wheel is pulled round, thus moving the +piston, which draws into the cylinder a mixture of gas and air through +about half its stroke; the mixture is then exploded by an electric +spark, and propels the piston to the end of its stroke, the pressure +meanwhile falling, by cooling and expansion, to that of the atmosphere +when exhaust takes place. In the return stroke the process is repeated, +the action of the engine resembling that of the double-acting steam +engine, and having a one-stroke cycle. The cylinder and covers are +cooled by circulating water. The firing electricity was supplied by two +Bunsen batteries and an induction coil, the circuit being completed at +the right intervals by contact pieces on an insulating disc on the +crank-shaft; the ignition spark leaped across the space between two +wires carried about one-sixth of an inch apart in a porcelain holder." + +In 1865 Mons. P. Hugon patented an engine similar to that of Lenoir, +except that ignition was accomplished by an external flame instead of +by electricity. The ignition flame was carried to and fro in a cavity +inside a slide valve, moved by a cam so as to get a rapid cut-off, and +permanent lights were maintained at the ends of the valve to re-light +the flame-ports after each explosion. The gas was supplied to the +cylinder by rubber bellows, worked by an eccentric on the crank-shaft. +This engine could be operated satisfactorily, except as to cost, but +the heavy gas consumption made it uneconomical. + +An important improvement in this regard was introduced by the Germans, +Herrn. E. Langen and N. A. Otto, who under patents bearing date of +1866 introduced a so-called "free" piston arrangement--that is to say +an arrangement by which the piston depends for its action partly upon +the momentum of a fly-wheel. This principle had been proposed for a +gas engine as early as 1857, but the first machine to demonstrate its +feasibility was that of Langen and Otto. Their engine greatly decreased +the gas consumption and hence came to be regarded as the first +commercially successful gas engine. It was, however, noisy and limited +to small sizes. The cycle of operations of an engine of this type is +described as follows: + +[Illustration: GAS AND OIL ENGINES. + +Lower right-hand figure, a very early type of commercially successful +gas engine. It has a "free" piston, an arrangement that was first +proposed for a gas engine in 1857, but only brought into practical form +by Langen & Otto under their patent of 1866. Upper figure, the gas +engine patented by Lenoir in 1860, one of the very first practically +successful engines. Lower left-hand figure, a sectional view of a +modern gas engine of the type used as the motor of the automobile.] + +"(a) The piston is lifted about one-tenth of its travel by the momentum +of the fly-wheel, thus drawing in a charge of gas and air. + +"(b) The charge is ignited by flame carried in by a slide valve. + +"(c) Under the impulse of the explosion, the piston shoots upward +nearly to the top of the cylinder, the pressure in which falls by +expansion to about 4 lbs. absolute, while absorbing the energy of the +piston. + +"(d) The piston descends by its own weight and the atmospheric +pressure, and in doing so causes a roller-clutch on a spur-wheel +gearing with a rack on the piston-rod to engage, so that the fly-wheel +shaft shall be driven by the piston; during this down-stroke the +pressure increases from 4 lbs. absolute to that of the atmosphere, and +averages 7 lbs. per square inch effective throughout the stroke. + +"(e) When the piston is near the bottom of the cylinder, the pressure +rises above atmospheric, and the stroke is completed by the weight of +the piston and rack, and the products of combustion are expelled. + +"(f) The fly-wheel now continues running freely till its speed, as +determined by a centrifugal governor, falls below a certain limit when +a trip gear causes the piston to be lifted the short distance required +to recommence the cycle. + +"Ignition is performed by an external gas jet, near a pocket in the +slide valve by which the charge is admitted; this pocket carries flame +to the charge, thus igniting it without allowing any escape. The valve +also connects the interior of the cylinder with the exhaust pipe, +and a valve in the latter controlled by the governor throttles the +discharge, and so defers the next stroke until the speed has fallen +below normal. To run the engine empty about four explosions per minute +are necessary, and at full power 30 to 35 are made, so that about 28 +explosions per minute are available for useful work under the control +of the governor." + +The definitive improvement in this gas engine was introduced in 1876 +by Dr. N. A. Otto, when he compressed the explosive mixture in the +working cylinder before igniting it. This expedient--so all-important +in its results--had been suggested by William Barnett in 1838, but at +that time gas engines were not sufficiently developed to make use of +the idea. Now, however, Dr. Otto demonstrated that by compressing the +gas before exploding it a much more diluted mixture can be fired, and +that this gives a quieter explosion, and a more sustained pressure +during the working stroke, while as the engine runs at a high speed the +fly-wheel action is generally sufficient to correct the fluctuations +arising from there being but one explosion for four strokes of the +piston. + +In this perfected engine, then, the method of operation is as follows: + +The piston is pulled forward with the application of some outside +force, which in practice is supplied by the inertia of the fly-wheel, +or in starting the engine by the action of a crank with which every +user of an automobile is familiar. In being pulled forward, the piston +draws gas into the cylinder; as the piston returns, this gas is +compressed; the compressed gas, constituting an explosive mixture, is +then ignited by a piece of incandescent metal or by an electric spark; +the exploding gas expands, pushing the piston forward, this being the +only thrust during which work is done; the returning piston expels the +expanded gas, completing the cycle. Thus there are three ineffective +piston thrusts to one effective thrust. Nevertheless, the engine has +proved a useful one for many purposes. + +This so-called Otto cycle has been adopted in almost all gas and oil +engines, the later improvements being in the direction of still higher +compression, and in the substitution of lift for slide valves. There +has been a steady increase in the size and power of such engines, the +large ones usually introducing two or more working cylinders so as to +secure uniform driving. Cheap forms of gas have been employed such as +those made by decomposing water by incandescent fuel, and it has been +proved possible thus to operate gas-power plants on a commercial scale +in competition with the most economical steam installations. + +A practical modification of vast importance was introduced when it +was suggested that a volatile oil be employed to supply the gas for +operation in an internal combustion engine. There was no new principle +involved in this idea, and the Otto cycle was still employed as +before; but the use of the volatile oil--either a petroleum product +or alcohol--made possible the compact portable engine with which +everyone is nowadays familiar through its use in automobiles and +motor boats. The oil commonly used is gasoline which is supplied to +the cylinder through a so-called carburettor in which the vapors of +gasoline are combined with ordinary air to make an explosive mixture. +The introduction of this now familiar type of motor is to a large +extent due to Herr G. Daimler, who in 1884 brought out a light and +compact high-speed oil engine. About ten years later Messrs. Panhard +and Levassor devised the form of motor which has since been generally +adopted. Few other forms of mechanisms are better known to the general +public than the oil engine with its two, four, six, or even eight +cylinders, as used in the modern automobile. As everyone is aware, it +furnishes the favorite type of motor, combining extraordinary power +with relative lightness, and making it feasible to carry fuel for a +long journey in a receptacle of small compass. + +With the gas engines a complication arises precisely opposite to that +which is met with in the case of the cylinder of the steam engine--the +tendency, namely, to overheating of the cylinder. To obviate this it +is customary to have the cylinder surrounded by a water jacket, though +air cooling is used in certain types of machines. About fifty per cent. +of the total heat otherwise available is lost through this unavoidable +expedient. + +The rapid introduction of the gas engine in recent years suggests that +this type of engine may have a most important future. It has even +been predicted that within a few years most trans-Atlantic steamers +will be equipped with this type of engine, producing their own gas +in transit. It is possible, then, that through this medium the old +piston-and-cylinder engine may retain its supremacy, as against the +turbine. For the moment, at any rate, the gas engine is gaining +popularity, not merely in its application to the automobile, but for +numerous types of small stationary engines as well. + +In this connection it will be interesting to quote the report of the +Special Agent of the Twelfth Census of the United States, as showing +the status of gas engines and steam engines in the year 1902. + +"The decade between 1890 and 1900," he says, "was a period of marked +development in the use of gas engines, using that term to denote all +forms of internal combustible engines, in which the propelling force +is the explosion of gaseous or vaporous fuel in direct contact with +a piston within a closed cylinder. This group embraces those engines +using ordinary illuminating gas, natural gas, and gas made in special +producers installed as a part of the power plant, and also vaporised +gasoline or kerosene. This form of power for the first time is an item +of consequence in the returns of the present census, and the very large +increase in the horse-power in 1900 as compared with 1890 indicates the +growing popularity of this class of motive power. + +"In 1890 the number of gas engines in use in manufacturing plants +was not reported, but their total power amounted to only 8,930 +horse-power, or one-tenth of one per cent of the total power utilized +in manufacturing operations. In 1900, however, 14,884 gas engines were +reported, with a total of 143,850 horse-power, or 1.3 per cent of the +total power used for manufacturing purposes. This increase from 8,930 +horse-power to 143,850 horse-power, a gain of 134,920 horse-power, is +proportionately the largest increase in any form of primary power shown +by a comparison of the figures of the Eleventh and Twelfth censuses, +amounting to 1,510.9 per cent. + +"Within the past decade, and more particularly during the past +five years, there has been a marked increase in the use of this +power in industrial establishments for driving machinery, for +generating electricity, and for other kindred uses. At the same time, +internal-combustion engines have increased in popularity for uses apart +from manufacturing, and the amount of this kind of power in use for all +purposes in 1900 was, doubtless, very much larger than indicated by the +figures relating to manufacturing plants alone. + +"The average horse-power per gas engine in 1900 was 9.7 horse-power. +There are no available statistics upon which to base a comparison of +this average with the average for 1890, but it is doubtful if there +has been any very material change in ten years; for while gas engines +are built in much larger sizes than ever before, there has been also a +great increase in the number of small engines for various purposes. + +"The large increase in the use of internal-combustion engines has +been due to the rapid improvements that have been made in them, their +increased efficiency and economy, their decreased cost, and the wider +range of adaptability that has been made practicable. + +"Steam still continues to be preeminently the power of greatest +importance, and the census returns indicate that the proportion of +steam to the total of all powers has increased very largely in the past +thirty years. In 1870 steam furnished 1,215,711 horse-power, or 51.8 +per cent of a total of 2,346,142; in 1880 the amount of steam power +used was 2,185,458 horse-power out of a total of 3,410,837, or 64.1 per +cent; in 1890 out of an aggregate of 5,954,655 horse-power, 4,581,595, +or 76.9 per cent was steam; while in 1900 steam figured to the extent +of 8,742,416 horse-power, or 77.4 per cent, in a total of 11,300,081. +This increase in thirty years, from 51.8 per cent to 77.4 per cent of +the total power, shows how much more rapidly the use of steam power has +increased than other primary sources of power. + +"The tendency toward larger units in the use of steam power is shown +inadequately by the increase in the average horse-power per engine from +39 horse-power in 1880, to 51 horse-power in 1890, and 56 horse-power +in 1900. + +"The tendency toward great operations which has been such a conspicuous +feature of industrial progress during the past ten years, has shown +itself strikingly in the use of units of larger capacity in nearly +every form of machinery, and nowhere has this tendency been more marked +than in the motive power by which the machinery is driven. At the same +time there has been an increase in the use of small units, which tends +to destroy the true tendency in steam engineering in these statistics. +For example, a steam plant consisting of one or more units of several +thousand horse-power may also embrace a number of small engines of +only a few horse-power each, the use of which is necessitated by the +magnitude of the plant, for the operation of mechanical stokers, the +driving of draft fans, coal and ash conveyors, and other work requiring +power in small units. On this account the average horse-power of steam +engines in use at different census periods fails to afford a true +basis for measuring progress toward larger units during the past ten +years. + +"Developments of the past few years in the distribution of power by the +use of electric motors have served to accelerate the tendency toward +larger steam units and the elimination of small engines in large plants +and to change completely the conditions just described. For example: +In one of the largest power plants in the world, which is now being +installed, all the stokers, blowers, conveyors, and other auxiliary +machinery are to be driven by electric motors. Such rapidly changing +conditions tend to invalidate any comparisons of statistical averages +deduced from figures for periods even but a few years apart. + +"Comparison of two important industries will illustrate the foregoing. +The average horse-power of the steam engine used in the cotton mills of +the United States in 1890 was 198, and in 1900 it was 300. + +"In the iron and steel industry the average horse-power per engine in +1890 was 171, and in 1900 it was 235. In the cotton mills the use of +single large units of motive power, with few auxiliary engines of small +capacity, gives the largest horse-power per engine of any industry; +while in the iron and steel industry the average of the motive power +proper, although probably larger than in the manufacture of cotton +goods, is reduced by the large number of small engines which are used +for auxiliary purposes in every iron and steel plant." + +It will be understood that the object of exploding the mixed gases in +the oil engine is to produce sudden heating of the entire gas. There +is no reason whatever for introducing the gasoline beyond this. Could +a better method of heating air be devised, the oil might be entirely +dispensed with, and the safety of the apparatus enhanced, as well as +the economy of operation. Efforts have been made for fifty years to +construct a hot-air engine that would compete with steam successfully. +In the early fifties, as already noted, Ericsson showed the feasibility +of substituting hot air for steam, but although he constructed large +engines, their power was so slight that he was obliged to give up the +idea of competing with steam, and to use his engines for pumping where +very small power was required. + +The great difficulty was that it was not found practicable to heat +the air rapidly. All subsequent experimenters have met with the same +difficulty until somewhat recently. It is now claimed, however, that +a means has been found of rapidly heating the air, and it is even +predicted that the hot-air engine will in due course entirely supersede +the steam engine. Mr. G. Emil Hesse, in an article in _The American +Inventor_, for April 15, 1905, describes a Svea caloric engine as +having successfully solved the problem of rapidly heating air. The +methods consist in breaking up the air into thin layers and passing +it over hot plates, where it rapidly absorbs heat. It passes from the +heater to the power cylinder which resembles the cylinder of a steam +engine; thence after expanding and doing its work it is exhausted into +the atmosphere. Large engines may use the same air over and over again +under pressure of one hundred pounds per square inch, alternately +heating and cooling it. A six horse-power engine of this type is +said to have a cylinder four and one-half inches in diameter and a +stroke of four and seven-eighth inches, and makes four hundred and +fifty revolutions per minute. The heater is twenty inches in diameter, +sixteen inches long, and has a heating surface of sixty square feet. +The total weight of heater and engine complete is four hundred pounds +for a half horse-power Ericsson engine. + +"The Svea heater," says Mr. Hesse, "absorbs the heat as perfectly +as an ordinary steam boiler, and the heat-radiating surface of both +heater and engine is not larger than that of a steam plant of the same +power, thereby placing the two motors on the same basis, as far as the +utilization of the heat in the fuel itself is concerned. + +"The advantage which every hot-air engine has over the steam engine is +the amount of heat saved in the vaporization of the water. It is now +well known that one gas is as efficient as another for the conversion +of heat into power. Air and steam at 100 deg. C. are consequently on the +same footing and ready to be superheated. The amount of heat required +to bring the two gases to this temperature is, however, very different. + +"With an initial temperature of 10 deg. C. for both air and water, we find +that one kilogram of steam requires 90 + 537 = 627 thermal units, +and one kilogram of air 0.24 x 90 = 21.6 thermal units. Some heat is +recovered if the feed water is heated and the steam condensed, but +the difference is still so great as to altogether exclude steam as a +competitor, provided air can be as readily handled. + +"Having now the means to rapidly heat the air, the outlook for the +external-combustion engine is certainly very promising. + +"The saving of more than half the coal now used by the steam engine +will be of tremendous importance to the whole world." + +To what extent this optimistic prediction will be verified is a problem +for the future to decide. + + + + +VIII + +THE SMALLEST WORKERS + + +In our studies of the steam engine and gas engine we have been +concerned with workers of infinitesimal size. Yet, if we are to believe +the reports of the modern investigator, the molecules of steam or of +ignited gas are small only in a relative sense, and there is a legion +of workers compared with which the molecules are really gigantic in +size. These workers are the atoms, and the yet more minute particles +of which, according to the most recent theories, they are themselves +composed. + +These smallest conceivable particles, the constituents of the atoms, +are called electrons. They are a discovery of the physicists of the +most recent generation. According to the newest theories they account +for most--perhaps for all--of the inter-molecular and inter-atomic +forces; they are indeed the ultimate repositories of those stores of +energy which are known to be contained in all matter. The theories +are not quite as fully developed as could be wished, but it would +appear that these minutest particles, the electrons, are the essential +constituents of the familiar yet wonderful carrier of energy which +we term electricity. In considering the share of electricity in +the world's work, therefore, we shall do well at the outset to put +ourselves in touch with recent views as to the nature of this most +remarkable of workers. + +On every side in this modern world we are confronted by this strange +agent, electricity. The word stares us in the face on every printed +page. The thing itself is manifest in all departments of our every-day +life. You go to your business in an electric car; ascend to your +office in an electric elevator; utilize electric call-bells; receive +and transmit messages about the world and beneath the sea by electric +telegraph. Your doctor treats you with an electric battery. Your +dentist employs electric drills and electric furnaces. You ride in +electric cabs; eat food cooked on electric stoves; and read with the +aid of electric light. In a word, the manifestations of electricity are +so obvious on every side that there can be no challenge to the phrasing +which has christened this the Age of Electricity. + +But what, then, is this strange power that has produced all these +multifarious results? It would be hard to propound a scientific query +that has been more variously answered. Ever since the first primitive +man observed the strange effect produced by rubbing a piece of amber, +thoughtful minds must have striven to explain that effect. Ever since +the eighteenth-century scientist began his more elaborate studies of +electricity, theories in abundance have been propounded. And yet we +are not quite sure that even the science of to-day can give a correct +answer as to the nature of electricity. At the very least, however, it +is able to give some interesting suggestions which seem to show that +we are in a fair way to solve this world-old mystery. And, curiously +enough, the very newest explanations are not so very far away from +some eighteenth-century theories which for a long time were looked +at askance if not altogether discarded. In particular, the theory of +Benjamin Franklin, which considered electricity as an immaterial fluid +bearing certain curious relations to tangible matter, is found to serve +singularly well as an aid to the interpretation of the very newest +experiments. + + +FRANKLIN'S ONE-FLUID THEORY + +Such being the case, we must consider this theory of Franklin's +somewhat in detail. Perhaps we cannot do better than state the theory +in the words of the celebrated physicist, Dr. Thomas Young, as given +in his work on natural philosophy, published in 1807. By quoting from +this old work we shall make sure that we are not reading any modern +interpretations into the theory. "It is supposed," says Young, "that a +peculiar ethereal fluid pervades the pores, if not the actual substance +of the earth and of all other material bodies, passing through them +with more or less facility, according to their different powers of +conducting it; that particles of this fluid repel each other, and are +attracted by particles of common matter; that particles of common +matter also repel each other; and that these attractions and repulsions +are equal among themselves, and vary inversely as to squares of the +distances of the particles. The effects of this fluid are distinguished +from those of all other substances by an attractive or repulsive +quality, which it appears to communicate to different bodies, and +which differs in general from other attractions and repulsions by +its immediate diminution or cessation when the bodies, acting on +each other, come into contact, or are touched by other bodies.... In +general, a body is said to be electrified when it contains, either as +a whole or in any of its parts, more or less of the electric fluid +than is natural to it.... In this common neutral state of all bodies, +the electrical fluid, which is everywhere present, is so distributed +that the various forces hold each other exactly in equilibrium and +the separate results are destroyed, unless we choose to consider +gravitation itself as arising from a comparatively slight inequality +between the electrical attractions and repulsions." + +The salient and striking feature of this theory, it will be observed, +is that the electrical fluid, under normal conditions, is supposed to +be incorporated everywhere with the substance of every material in +the world. It will be observed that nothing whatever is postulated as +to the nature or properties of this fluid beyond the fact that its +particles repel each other and are attracted by the particles of common +matter; it being also postulated that the particles of common matter +likewise repel each other under normal conditions. + +At the time when Franklin propounded his theory, there was a rival +theory before the world, which has continued more or less popular ever +since, and which is known as the two-fluid theory of electricity. +According to this theory, there are two uncreated and indestructible +fluids which produce electrical effects. One fluid may be called +positive, the other negative. The particles of the positive fluid are +mutually repellent, as also are the particles of the negative fluid, +but, on the other hand, positive particles attract and are attracted by +negative particles. We need not further elaborate the details of this +two-fluid theory, because the best modern opinion considers it less +satisfactory than Franklin's one-fluid theory. Meantime, it will be +observed that the two theories have much in common; in particular they +agree in the essential feature of postulating an invisible something +which is not matter, and which has strange properties of attraction and +repulsion. + +These properties of attraction and repulsion constituted in the +early day the only known manifestations of electricity; and the same +properties continue to hold an important place in modern studies of +the subject. Electricity is so named simply because amber--the Latin +_electrum_--was the substance which, in the experience of the ancients, +showed most conspicuously the strange property of attracting small +bodies after being rubbed. Modern methods of developing electricity +are extremely diversified, and most of them are quite unsuggestive +of the rubbing of amber; yet nearly all the varied manifestations of +electricity are reducible, in the last analysis, to attractions and +repulsions among the particles of matter. + +As to the alleged immaterial fluids which, according to the theories +just mentioned, make up the real substance of electricity, it was +perfectly natural that they should be invented by the physicists of the +elder day. All the conceptions of the human mind are developed through +contact with the material world; and it is extremely difficult to get +away, even in theory, from tangible realities. When the rubbed amber +acquires the property of drawing the pith ball to it, we naturally +assume that some change has taken place in the condition of the amber; +and since the visible particles of amber appear to be unchanged--since +its color, weight, and friability are unmodified--it seems as if some +immaterial quality must have been added to, or taken from it. And it +was natural for the eighteenth-century physicist to think of this +immaterial something as a fluid, because he was accustomed to think of +light, heat, and magnetism as being also immaterial fluids. He did not +know, as we now do, that what we call heat is merely the manifestation +of varying "modes" of motion among the particles of matter, and that +what we call light is not a thing _sui generis_, but is merely our +recognition of waves of certain length in the all-pervading ether. +The wave theory of light had, indeed, been propounded here and +there by a philosopher, but the theory which regarded light as a +corpuscular emanation had the support of no less an authority than +Sir Isaac Newton, and he was a bold theorist that dared challenge it. +When Franklin propounded his theory of electricity, therefore, his +assumption of the immaterial fluid was thoroughly in accord with the +physical doctrines of the time. + + +MODERN VIEWS + +But about the beginning of the nineteenth century the doctrine +of imponderable fluids as applied to light and heat was actively +challenged by Young and Fresnel and by Count Rumford and Humphry Davy +and their followers, and in due course the new doctrines of light and +heat were thoroughly established. In the light of the new knowledge, +the theory of the electric fluid or fluids seemed, therefore, much +less plausible. Whereas the earlier physicists had merely disputed as +to whether we must assume the existence of two electrical fluids or +of only one, it now began to be questioned whether we need assume the +existence of any electrical fluid whatever. The physicists of about +the middle of the nineteenth century developed the wonderful doctrine +of conservation of energy, according to which one form of force may be +transformed into another, but without the possibility of adding to, or +subtracting from, the original sum total of energy in the universe. +It became evident that electrical force must conform to this law. +Finally, Clerk-Maxwell developed his wonderful electromagnetic theory, +according to which waves of light are of electrical origin. The work of +Maxwell was followed up by the German Hertz, whose experiments produced +those electromagnetic waves which, differing in no respect except in +their length from the waves of light, have become familiar to everyone +through their use in wireless telegraphy. All these experiments showed +a close relation between electrical phenomena, and the phenomena of +light and of radiant heat, and a long step seemed to be taken toward +the explanation of the nature of electricity. + +The new studies associated electricity with the ether, rather than with +the material substance of the electrified body. Many experiments seemed +to show that electricity in motion traverses chiefly the surface of +the conductor, and it came to be believed that the essential feature of +the "current" consists of a condition of strain or stress in the ether +surrounding a conductor, rather than of any change in the conductor +itself. This idea, which is still considered valid, has the merit of +doing away with the thought of action at a distance--the idea that was +so repugnant to the mind of Faraday. + +So far so good. But what determines the ether strain? There is +surely _something_ that is not matter and is not ether. What is this +something? The efforts of many of the most distinguished experimenters +have in recent years been directed toward the solution of that +question; and these efforts, thanks to the new methods and new +discoveries, have met with a considerable measure of success. I must +not attempt here to follow out the channels of discovery, but must +content myself with stating briefly the results. We shall have occasion +to consider some further details as to the methods in a later chapter. + +Briefly, then, it is now generally accepted, at least as a working +hypothesis, that every atom of matter--be it oxygen, hydrogen, gold, +iron, or what not--carries a charge of electricity, which is probably +responsible for all the phenomena that the atom manifests. This charge +of electricity may be positive or negative, or it may be neutral, by +which is meant that the positive and negative charges may just balance. +If the positive charge has definite carriers, these are unknown except +in association with the atom itself; but the negative charge, on the +other hand, is carried by minute particles to which the name electron +(or corpuscle) has been given, each of which is about one thousand +times smaller than a hydrogen atom, and each of which carries uniformly +a unit charge of negative electricity. + +Electrons are combined, in what may be called planetary systems, in the +substance of the atom; indeed, it is not certain that the atom consists +of anything else but such combinations of electrons, held together +by the inscrutable force of positive electricity. Some, at least, of +the electrons within the atom are violently active--perhaps whirling +in planetary orbits,--and from time to time one or more electrons may +escape from the atomic system. In thus escaping an electron takes away +its charge of negative electricity, and the previously neutral atom +becomes positively electrified. Meanwhile the free electron may hurtle +about with its charge of negative electricity, or may combine with some +neutral atom and thus give to that neutral atom a negative charge. +Under certain conditions myriads of these electrons, escaped thus from +their atomic systems, may exist in the free state. For example, the +so-called _beta_ (ss) rays of radium and its allies consist of such +electrons, which are being hurtled off into space with approximately +the speed of light. The cathode rays, of which we have heard so much in +recent years, also consist of free electrons. + +But, for that matter, all currents of electricity whatever, according +to this newest theory, consist simply of aggregations of free +electrons. According to theory, if the electrons are in uniform motion +they produce the phenomena of constant currents of electricity; if +they move non-uniformly they produce electromagnetic phenomena (for +example, the waves used in wireless telegraphy); if they move with +periodic motion they produce the waves of light. Meanwhile stationary +aggregations of electrons produce the so-called electrostatic +phenomena. All the various ether waves are thus believed to be produced +by changes in the motions of the electrons. A very sudden stoppage, +such as is produced when the cathode ray meets an impassable barrier, +produces the X-ray. + +With these explanations in mind, it will be obvious how closely this +newest interpretation of electricity corresponds in its general +features with the old one-fluid theory of Franklin. The efforts of +the present-day physicist have resulted essentially in an analysis of +Franklin's fluid, which gives to this fluid an atomic structure. The +new theory takes a step beyond the old in suggesting the idea that +the same particles which make up the electric fluid enter also into +the composition--perhaps are the sole physical constituents--of every +material substance as well. But while the new theory thus extends +the bounds of our vision, we must not claim that it fully solves the +mystery. We can visualize the ultimate constituent of electricity as +an electron one thousand times smaller than the hydrogen atom, which +has mass and inertia, and which possesses powers of attraction and +repulsion. But as to the actual nature of this ultimate particle we are +still in the dark. There are, however, some interesting theories as to +its character, which should claim at least incidental attention. + +We have all along spoken of the electron as an exceedingly minute +particle, stating indeed, that in actual size it is believed to be +about one thousand times smaller than the hydrogen atom, which hitherto +had been considered the smallest thing known to science. But we have +now to offer a seemingly paradoxical modification of this statement. +It is true that in _mass_ or weight the electron is a thousand times +smaller than the hydrogen atom, yet at the same time it may be +conceived that the limits of space which the electron occupies are +indefinitely large. In a word, it is conceived (by Professor J. J. +Thomson, who is the chief path-breaker in this field) that the electron +is in reality a sort of infinitesimal magnet, having two poles joined +by lines or tubes of magnetic force (the so-called Faraday tube), which +lines or tubes are of indefinite number and extent; precisely as, on +a large scale, our terrestrial globe is such a magnet supplied with +such an indefinite magnetic field. That the mass of the electron is so +infinitesimally small is explained on the assumption that this mass +is due to a certain amount of universal ether which is bound up with +the tubes where they are thickest; close to the point in space from +which they radiate, which point in space constitutes the focus of the +tangible electron. + +It will require some close thinking on the part of the reader to gain +a clear mental picture of this conception of the electron; but the +result is worth the effort. When you can clearly conceive all matter as +composed of electrons, each one of which cobwebs space with its system +of magnetic tubes, you will at least have a tangible picture in mind of +a possible explanation of the forces of cohesion and gravitation--in +fact, of all the observed cases of seeming action at a distance. If +at first blush the conception of space as filled with an interminable +meshwork of lines of force seems to involve us in a hopeless mental +tangle, it should be recalled that the existence of an infinity of such +magnetic lines joining the poles of the earth may be demonstrated at +any time by the observation of a compass, yet that these do not in any +way interfere with the play of other familiar forces. There is nothing +unthinkable, then, in the supposition that there are myriads of minor +magnetic centres exerting lesser degrees of force throughout the same +space. + +All that can be suggested as to the actual nature of the Faraday +tubes is that they perhaps represent a condition of the ether. This, +obviously, is heaping hypothesis upon hypothesis. Yet it should be +understood that the hypothesis of the magnetic electron as the basis of +matter, has received an amount of experimental support that has raised +it at least to the level of a working theory. Should that theory be +demonstrated to be true, we shall apparently be forced to conclude not +merely that electricity is present everywhere in nature, but that, in +the last analysis, there is absolutely no tangible thing other than +electricity in all the universe. + + +HOW ELECTRICITY IS DEVELOPED + +Turning from this very startling theoretical conclusion to the +practicalities, let us inquire how electricity--which apparently +exists, as it were, in embryo everywhere--can be made manifest. In so +doing we shall discover that there are varying types of electricity, +yet that these have a singular uniformity as to their essential +properties. As usually divided--and the classification answers +particularly well from the standpoint of the worker--electricity is +spoken of as either statical or dynamical. The words themselves are +suggestive of the essential difference between the two types. Statical +electricity produces very striking manifestations. We have already +spoken of it as theoretically due to the conditions of the electrons +at rest. It must be understood, however, that the statical electricity +will, if given opportunity, seek to escape from any given location to +another location, under certain conditions, somewhat as water which is +stored up in a reservoir will, when opportunity offers, flow down to a +lower level. The pent-up static electricity has, like the water in the +reservoir, a store of potential energy. The physicist speaks of it as +having high tension. In passing to a condition of lower tension, the +statical electricity may give up a large portion of its energy. + +If, for example, on a winter day in a cold climate, you walk briskly +along a wool carpet, the friction of your feet with the carpet +generates a store of statical electricity, which immediately passes +over the entire surface of your body. If now you touch another person +or a metal conductor, such as a steam radiator or a gas pipe, a +brilliant spark jumps from your finger, and you experience what is +spoken of as an electrical shock. If the day is very cold, and the air +consequently very dry, and if you will take pains to rub your feet +vigorously or slide along the carpet, you may light a gas jet with +the spark which will spring from your finger to the tip of the jet, +provided the latter is of metal or other conducting substance; and even +if you attempt to avoid the friction between your feet and the carpet +as much as possible, you may be constantly annoyed by receiving a shock +whenever you touch any conductor, since, in spite of your efforts, the +necessary amount of friction sufficed to generate a store of statical +electricity. + +An illustration of the development of this same form of electricity, +on a large scale, is supplied by the familiar statical machine, which +consists of a large circle of glass, so adjusted that it may be +revolved rapidly against a suitable friction producer. With such a +machine a powerful statical current is produced, capable of generating +a spark that may be many inches or even several feet in length,--a +veritable flash of lightning. It is with such a supply of electricity +conducted through a vacuum tube that the cathode ray and the Roentgen +ray are produced. + +Such effects as this suggest considerable capacity for doing work. +Yet in reality, notwithstanding the very sporadical character of the +result, the quantity of electricity involved in such a statical current +may be very slight indeed. Even a lightning flash is held to represent +a comparatively small amount of electricity. Faraday calculated that +the amount of electricity that could be generated from a single drop +of water, through chemical manipulation, would suffice to supply the +lightning for a fair-sized thunder-storm. Nevertheless the destructive +work that may be done by a flash of lightning may be considerable, as +everyone is aware. But, on the other hand, while the visible effect of +a stroke of lightning on a tree trunk, for example, makes it seem a +powerful agency, yet the actual capacity to do work--the power to move +considerable masses of matter--is extremely limited. The effect on a +tree trunk, it will be recalled, usually consists of nothing more than +the stripping off of a channel of bark. In other words, the working +energy contained in a seemingly powerful supply of statical electricity +commonly plays but an insignificant part. + +The working agent, and therefore the form of electricity which concerns +us in the present connection, is the dynamical current. This may be +generated in various ways, but in practice these are chiefly reducible +to two. One of these depends upon chemical action, the other upon the +inter-relations of mechanical motion and magnetic lines of force. A +common illustration of the former is supplied by the familiar voltaic +or galvanic battery. The electromagnetic form has been rendered +even more familiar in recent times by the dynamo. This newest and +most powerful of workers will claim our attention in detail in the +succeeding chapter. Our present consideration will be directed to the +older method of generating the electric current as represented by the +voltaic cell. + + +THE WORK OF THE DYNAMICAL CURRENT + +Let us draw our illustration from a familiar source. Even should your +household otherwise lack electrical appliances, you are sure to have +an electric call-bell. The generator of the electric current, which +is stored away in some out-of-the-way corner, is probably a small +so-called "dry-cell" which you could readily carry around in your +pocket; or it may consist of a receptacle holding a pint or two of +liquid in which some metal plates are immersed. Such an apparatus +seems scarcely more than a toy when we contrast it with the gigantic +dynamos of the power-house; yet, within the limits of its capacities, +one is as surely a generator of electricity as the other. If we are +to accept the latest theory, the electrical current which flows from +this tiny cell is precisely the same in kind as that which flows from +the five-thousand-horse-power dynamo. The difference is only one of +quantity. + +To understand the operation of this common household appliance we must +bear in mind two or three familiar experimental facts in reference +to the action of the voltaic cell. Briefly, such a cell consists of +two plates of metal--for example, one of copper and the other of +zinc--with a connecting medium, which is usually a liquid, but which +may be a piece of moistened cloth or blotting-paper. So long as the two +plates of metal are not otherwise connected there is no electricity in +evidence, but when the two are joined by any metal conductor, as, for +example, a piece of wire--thus, in common parlance, "completing the +circuit"--a current of electricity flows about this circuit, passing +from the first metal plate to the second, through the liquid and back +from the second plate to the first through the piece of wire. The wire +may be of any length. In the case of your call-bell, for example, the +wire circuit extends to your door, and is there broken, shutting off +the current. + +When you press the button you connect the broken ends of the wire, thus +closing the circuit, as the saying is, and the re-established current, +acting through a little electromagnet, rings the bell. In another case, +the wire may be hundreds of miles in length, to serve the purposes of +the telegrapher, who transmits his message by opening and closing the +circuit, precisely as you operate your door-bell. For long-distance +telegraphy, of course, large cells are required, and numbers of them +are linked together to give a cumulative effect, making a strong +current; but there is no new principle involved. + +The simplest study of this interesting mechanism makes it clear that +the cell is the apparatus primarily involved in generating the electric +current; yet it is equally obvious that the connecting wire plays an +important part, since, as we have seen, when the wire is broken there +is no current in evidence. Now, according to the electron theory, as +previously outlined, the electric current consists of an actual flow +along the wire of carriers of electricity which are unable to make +their way except where a course is provided for them by what is called +a conductor. Dry air, for example, is, under ordinary circumstances, +quite impervious to them. This means, then, that the electrons flow +freely along the wire when it is continuous, but that they are +powerless to proceed when the wire is cut. When you push the button of +your call-bell, therefore, you are virtually closing the switch which +enables the electrons to proceed on their interrupted journey. + + +THEORIES OF ELECTRICAL ACTION + +But all this, of course, leaves quite untouched the question of the +origin of the electrons themselves. That these go hurtling from one +plate or pole of the battery to the other, along the wire, we can +understand at least as a working theory; that, furthermore, the +electrons have their origin either in the metal plates or in the liquid +that connects them, seems equally obvious; but how shall we account for +their development? It is here that the chemist with his atomic theory +of matter comes to our aid. He assures us that all matter consists +in the last analysis of excessively minute particles, and that these +particles are perpetually in motion. They unite with one another to +form so-called molecules, but they are perpetually breaking away from +such unions, even though they re-establish them again. Such activities +of the atoms take place even in solids, but they are greatly enhanced +when any substance passes from the solid into the liquid state. + +When, for example, a lump of salt is dissolved in water, the atoms of +sodium and of chlorine which joined together make up the molecules of +salt are held in much looser bondage than they were while the salt +was in a dry or crystalline form. Could we magnify the infinitesimal +particles sufficiently to make them visible we should probably see +large numbers of the molecules being dissociated, the liberated atoms +moving about freely for an instant and then reuniting with other atoms. +Thus at any given instant our solution of salt would contain numerous +free _atoms_ of sodium and of chlorine, although we are justified in +thinking of this substance as a whole as composed of sodium-chlorine +_molecules_. It is only by thus visualizing the activity of the atoms +in a solution that we are able to provide even a thinkable hypothesis +as to the development of electricity in the voltaic cell. + +What puts us on the track of the explanation we are seeking is the +fact that the diverse atoms are known to have different electrical +properties. In our voltaic cell, for example, sodium atoms would +collect at one pole and chlorine atoms at the other. Humphry Davy +discovered this fact in the early days of electro-chemistry, just about +a century ago. He spoke of the sodium atom as electro-positive, and +of the chlorine atom as electro-negative, and he attempted to explain +all chemical affinity as merely due to the mutual attraction between +positively and negatively electrified atoms. The modern theorist goes +one step farther, and explains the negative properties of the chlorine +atom by assuming the presence of one negative electron or electricity +in excess of the neutralizing charge. The assumption is, that the +sodium atom has lost this negative electron and thus has become +positively electrified. The chlorine atom, harboring the fugitive +electron, becomes negatively electrified. Hence the two atoms are +attracted toward opposite poles of the cell. + +This disunion of atoms, be it understood, must be supposed to take +place in the case of any solution of common salt, whether it rests +in an ordinary cup or forms a part of the ocean. Here we have, then, +material for the generation of the electrical current, if some means +could be found to induce the chlorine atom to give up the surplus +electron which from time to time it carries. And this means is provided +when two pieces of metal of different kinds, united with a metal +conductor, are immersed in the liquid. Then it comes to pass that the +electrons associated with the chlorine atoms that chance to lie in +contact with one of these plates of metal, find in this metal an avenue +of escape. They rush off eagerly along the metal and the connecting +wire, and in so doing establish a current which acts--if we may venture +a graphic analogy from an allied field of physics--as a sort of +suction, attracting other chlorine atoms from the body of the liquid +against the metal plate that they also may discharge their electrons. +In other words, the electrical current passes through the liquid as +well as through the outside wire, thus completing the circuit. + +According to this theory, then, the electrical energy in evidence in +the current from the voltaic cell, is drawn from a store of potential +energy in the atoms of matter composing the liquid in the cell. In +practice, as is well known, the liquid used is one that affects one +of the metal poles more actively than the other, insuring vigorous +chemical activity. But the principle of atomic and electrical +dissociation just outlined is the one involved, according to theory, +in every voltaic cell, whatever the particular combination of metals +and liquids of which it is composed. It should be added, however, +that while we are thus supplied with a thinkable explanation of the +origin of this manifestation of electrical energy, no explanation is +forthcoming, here any more than in the case of the dynamo, as to why +the electrons rush off in a particular direction and thus establish an +electrical current. Perhaps we should recall that the very existence of +this current has at times been doubted. Quite recently, indeed, it has +been held that the seeming current consists merely of a condition of +strain or displacement of the ether. But we are here chiefly concerned +with the electron theory, according to which, as we have all along +noted, the seeming current is an actual current; the ether strain, if +such exists, being due to the passage of the electrons. + + +PRACTICAL USES OF ELECTRICITY + +Various effects of the current of electrons have been hinted at above. +Considered in detail, the possible ways in which these currents may be +utilized are multifarious. Yet, they may be all roughly classified into +three divisions as follows: + +First, cases in which the current of electricity is used to transmit +energy from one place to another, and reproduce it in the form of molar +motion. The dynamo, in its endless applications, illustrates one phase +of such transportation of energy; and the call-bell, the telegraph, +and the telephone represent another phase. In one case a relatively +large quantity of electricity is necessary, in the other case a small +quantity; but the principle involved--that of electric and magnetic +induction--is the same in each. + +The second method is that in which the current, generated by either +a dynamo or a battery of voltaic cells, is made to encounter a +relatively resistant medium in the course of its flow along the +conducting circuit. Such resistance leads to the production of active +vibrations among the particles of the resisting medium, producing the +phenomena of heat and, if the activity is sufficient, the phenomena of +light also. It will thus appear that in this class of cases, as in the +other, there is an actual re-transformation of electrical energy into +the energy of motion, only in this case the motion is that of molecules +and not of larger bodies. The principle is utilized in the electrical +heater, with which our electric street-cars are commonly provided, +and which is making its way in the household for purposes of general +heating and of cooking. It is utilized also in various factories, +where the very high degree of heat attainable with the electrical +furnace is employed to produce chemical dissociation and facilitate +chemical combinations. By this means, for example, a compound of +carbon and silicon, which is said to be the hardest known substance, +except the diamond, is produced in commercial quantities. A familiar +household illustration of the use of this principle is furnished by the +electric light. The carbon filament in the electric bulb furnishes such +resistance to the electric current that its particles are set violently +aquiver. Under ordinary conditions the oxygen of the air would +immediately unite with the carbon particles, volatilizing them, and +thus instantly destroying the filament; but the vacuum bulb excludes +the air, and thus gives relative permanency to the fragile thread. + +The third class of cases in which the electric current is commercially +utilized is that in which the transformations it effects are produced +in solutions comparable to those of the voltaic cell, the principles +involved being those pointed out in the earlier part of the present +chapter. By this means a metal may be deposited in a pure state upon +the surface of another metal made to act as a pole to the battery; as, +for example, when forks, spoons, and other utensils of cheap metals +are placed in a solution of a silver compound, and thus electroplated +with silver. To produce the powerful effects necessary in the various +commercial applications of this principle, the poles of the voltaic +cell--which cell may become in practice a large tank--are connected +with the current supplied by a dynamo. Various chemical plants at +Niagara utilize portions of the currents from the great generators +there in this way. Another familiar illustration of the principle is +furnished by the copper electroplates from which most modern books are +printed. + +It appears, then, that all the multifarious uses of electricity in +modern life are reducible to a few simple principles of action, just +as electricity itself is reduced, according to the analysis of the +modern physicist, to the activities of the elementary electron. There +is nothing anomalous in this, however, for in the last analysis the +mechanical principles involved in doing all the world's work are few +and relatively simple, however ingenious and relatively complex may be +the appliances through which these principles are made available. + + + + +IX + +MAN'S NEWEST CO-LABORER: THE DYNAMO + + +As you stand waiting for your train at elevated or subway station you +must have noticed the third rail. To outward appearance it is not +different from the other rails. It seems a mere inert piece of steel. +Yet you are well aware that a strange power abides there unseen--a +power that pulls the train, and that lurks in hiding to strike a +death-blow to any chance unfortunate whose foot or hand comes in +contact with the rail. As the heavy train dashes up, dragged by this +unseen power, probably you, in common with the rest of the world, have +been led to remark, "Is it not marvelous?" + +Marvelous it surely seems. Yet the cause of our astonishment is to be +sought in the relative newness of the phenomena rather than in the +nature of the phenomena themselves. At first glance it may seem that +the intangible character of the electrical power gives it a unique +claim on our wonderment. But a moment's reflection dispels this +illusion. After all, electricity is no more intangible than heat. +Neither the one nor the other can be seen or heard, but each alike may +be felt. Yet we observe without astonishment a locomotive propelled +by the power of heat--simply because the locomotive has become an old +story. Again, electricity is far less intangible than gravitation. +Not merely may electricity be felt, but it may be generated through +transformation of other forms of energy; it may be stored away and +measured; may be conducted at will through tortuous channels, or +obstructed in its flight by the intervention of non-conductors. But +gravitation submits to no such restrictions. It eludes all of our +senses, and it absolutely disregards all barriers. To its catholic +taste all substances are alike. It holds in bondage every particle of +matter in the universe, and can enforce its influence over every kind +of atom with an impartiality that is as astounding as it is inexorable. +Moreover, this weird force, gravitation, has thus far evaded all man's +efforts to classify or label it. No man has the slightest inkling as +to what gravitation really is. If, as you glance at these lines, you +should chance to release your hold and allow the volume to drop to the +floor, you will have performed a miracle which no scientist in the +world can even vaguely explain. + +As regards our electric train, then, the fact that it stands there +firmly, held fast to the rails by gravitation, is in reality as great +and as inexplicable a marvel as the fact that the electric current +gives it propulsion. Not only so, but the fact that the train goes +forward of its own inertia, as we say, for a time after the current +is shut off, presents to us yet another inexplicable marvel. It is a +fundamental property of matter, we say, when once in motion to continue +in motion until stopped by some counter-force; but that phrasing, +expressive though it be of a fact upon which so many physical phenomena +depend, is in no proper sense of the word an explanation. + +Once for all, then, there is nothing unique, nothing preternaturally +marvelous, about the phenomena of electricity. And indeed, it is +interesting to note how quickly we become accustomed to these +phenomena, and how little wonder they excite so soon as they cease +to be novel. Even imaginative people have long since ceased to give +thought to the trolley car; and within a week of the opening of New +York's subway the average man came to regard it as much as a matter of +course as if he had been accustomed to it from boyhood. + +And yet, in another sense of the word, the electric motor is a +wonderful contrivance. As an example of what man's ingenuity can +accomplish toward transforming the powers of nature and adapting them +to his own use, it is fully entitled to be called a marvel. Moreover, +in the last analysis, we are as helpless to explain the nature of +electricity as we are to explain the nature of gravitation. It is only +the proximal phenomena of the electric current that can be explained. +These phenomena, however, are full of interest. Let us examine them +somewhat in detail, allowing them to lead us back from electric train +to power-house and dynamo, and from dynamo as far toward the mystery of +electric energy as present-day science can guide us. + + +THE MECHANISM OF THE DYNAMO + +If we could look into the interior of a mechanism in connection with +the trucks beneath the car, we should find an apparatus consisting +essentially of coils of wire adjusted compactly about an axis, and +closely fitted between the poles of a powerful electromagnet. These +coils of wire constitute what is called an armature. When the current +is switched on it passes through this armature, as well as through the +electromagnet, and the mutual attractions and repulsions between the +magnetic poles and the electric current in the coils of wire, cause +the armature to revolve with such tremendous energy as to move the +train--the motion of its axis being transmitted to the axle of the +car-wheels by a simple gearing. + +All this is simple enough if we regard only the _how_ and not the _why_ +of the phenomena. Ignoring the _why_ for the moment, let us seek the +origin of the current which, by being conducted through the armature, +has produced the striking effect we have just witnessed. This current +reaches the car through an overhead or underground wire. All that is +essential is that some conducting medium, such as an iron rail, or +a copper wire, shall form an unbroken connection between the motor +apparatus and the central dynamo where the power is generated--the +return circuit being made either by another wire or by the ordinary +rails. + +The central dynamo in question will be found, if we visit the +power-house, to be a ponderous affair, suggestive to the untechnical +mind of impenetrable mysteries. Yet in reality it is a device +essentially the same in construction as the motor which drives +the train. That is to say, its unit of construction consists of a +wire-wound armature revolving on an axis and fitted between the +poles of an electromagnet. Here, however, the sequence of phenomena +is reversed, for the armature, instead of receiving a current of +electricity, is made to revolve by a belt adjusted to its axis and +driven by a steam engine. The wire coils of the armature thus made to +revolve cut across the so-called lines of magnetic force which connect +the two poles of the magnet, and in so doing generate a current of +induced electricity, which flows away to reach in due course the third +rail or the trolley-wire, and ultimately to propel the motor. + +[Illustration: Lower figure copyrighted by N. Y. Edison Co. + +AN ELECTRIC TRAIN AND THE DYNAMO THAT PROPELS IT. + +The lower figure gives an interior view of a power house of the +Manhattan Elevated Railway Company. The upper figure shows one of the +electric engines operating on the New York Central Lines just outside +of New York. The power is conveyed to the engine by a third rail +clearly shown in the picture.] + +It is hardly necessary to state that in actual practice this generating +dynamo is a complex structure. The armature is a complex series of +coils of wire; the electromagnets surrounding the armature are several +or many; and there is an elaborate system of so-called commutators +through which the currents of electricity--which would otherwise +oscillate as the revolving coil cuts the lines of magnetic force in +opposite directions--are made to flow in one direction. But details +aside, the foundation facts upon which everything depends are (1) that +a coil of wire when forced to move so that it cuts across the lines of +force in any magnetic field develops a so-called induced current of +electricity; and (2) that such an induced current possesses power of +magnetic attraction and repulsion. These facts were discovered more +than sixty years ago, and carefully studied by Michael Faraday, Joseph +Henry, and others. Faraday found that such an induced current could be +produced not merely with the aid of an iron magnet, but even by causing +a wire to cut the lines of force that everywhere connect the north and +south poles of the earth,--the earth being indeed, as William Gilbert +long ago demonstrated, veritably a gigantic magnet. Moreover, these +relations are reciprocal; so that if a wire through which a current +of electricity is passing is placed across a magnetic field, the wire +is impelled to move in a plane at right angles to the direction of the +lines of force. It is forcibly thrust aside. This side-thrust acting on +coils of wire is what produces the revolution of the armature of the +electric motor. + + +THE ORIGIN OF THE DYNAMO + +The very first studies that had to do with the mutual relations +of electricity and magnetism were made by Hans Christian Oersted, +the Dane, as early as 1815. He discovered that a magnetic needle +is influenced by the passage near it of a current of electricity, +demonstrating, therefore, that the electric current in some way invades +the medium surrounding any conductor along which it is passing. +Oersted's experiments were repeated, and some new phenomena observed by +the Frenchman Andre Marie Ampere and Dominique Francois Arago. Arago +constructed an interesting device, in which a metal disk was made to +revolve in the presence of a current of electricity; but neither he nor +anyone else at the time was able to explain the phenomenon. + +In 1824 an advance was made through the construction of the first +electric magnet by Sturgeon. Hitherto it had not been known that a +magnet could be made artificially, except by contact with a previously +existing magnet. Sturgeon showed that any core of iron may be rendered +magnetic if wound with a conducting wire, through which a current +of electricity is passed. The experiments thus inaugurated were +followed up in America by Joseph Henry of Albany who made enormous +electromagnets, capable of sustaining great weights. One of his +magnets, operated by a single cell, was able to lift six hundred and +fifty pounds of metal. + +It was this apparatus which was subsequently to make possible the +utilization of electricity as a working force, but as yet no one +suspected its possibilities in this direction. + +It remained for Michael Faraday, in 1831, to make the final +experiment which laid the secure foundation for the new science of +electrodynamics. Faraday constructed a tiny apparatus, consisting of a +magnet between the poles of which a metal disk was placed in such a way +that it could revolve on an axis, the disk being connected with a wire +conveying an electric current. + +The details as to this most ingenious mechanism need not be given here. +Suffice it that Faraday demonstrated the interrelations of magnetism +and electricity and the possibility of causing a metal disk to revolve +through this mutual interaction. In so doing he constructed the first +dynamo-electric machine. In his hands it was a mere laboratory toy, +but the principles involved were fully elaborated by the original +experimenter, and stated in precise language which modern investigators +have not been able to improve upon. + +Several decades elapsed after Faraday's initial experiment before the +phenomena of magneto-electricity were proved to have any considerable +commercial significance. A vast amount of ingenuity was required to +devise a mechanism which could advantageously utilize the principle +in question for commercial purposes. Indeed the early experimenters +did not at once get upon the right track, as their efforts were +influenced disadvantageously by an attempt to follow the principle of +the steam engine. Some interesting mechanisms were devised whereby the +motion of an armature in being drawn toward an electromagnet could be +translated into rotary motion through the use of crank-shafts and even +of beams, precisely comparable to those employed in the steam engine. +Such devices worked with a comparatively low degree of efficiency and +were totally abandoned so soon as the idea of getting rotary motion +directly from the magnet or armature was made feasible. The names of +Saxton, Clarke, Woolrich, Wheatstone, and Werner Siemens are intimately +connected with the early efforts at utilization of magneto-electric +power. The shuttle-wound armature of Siemens, invented in 1854, marked +an important progressive step. + + +PERFECTING THE DYNAMO + +The first separately excited dynamos were constructed by Dr. Henry +Wilde, F.R.S., between 1863 and 1865, and this invention paved the way +for rapid progress. In 1866-7 Varley, Siemens, Wheatstone, and Ladd +constructed machines with several iron electromagnets, self-excited, +which were described as dynamo-electric machines, a term afterward +contracted to dynamos. In 1867 Dr. Wilde improved the armature by +introducing several coils arranged around a cylinder; the current +from a few of the coils was rectified and used to excite the field +magnet, while the main current as given off by the rest of the coils +was taken off by ring-contacts, the machine being a self-exciting, +alternating-current dynamo. + +[Illustration: WILDE'S SEPARATELY EXCITED DYNAMO. + +Dr. Wilde invented and patented (1863-5) the first separately excited +dynamo, with which he demonstrated that the feeble current from a small +magneto-electric machine would, by the expenditure of mechanical power, +produce currents of great strength from a large dynamo.] + +The Italian, Picnotti, in 1864 invented a ring armature which, +although provided with teeth was wound with coils in such a way as to +obtain a very uniform current; but the practical introduction of the +continuous-current machines dates from 1870, when Gramme re-invented +the ring and gave it the form which is still in vogue. Von Alteneck in +1873 converted the Siemens shuttle armature along the same lines and so +introduced the drum arrangement which has since been very extensively +adopted. + +Thus through the efforts of a great number of workers the idea of +utilizing electromagnetic energy for the purposes of the practical +worker came to be a reality. Numberless machines have been made +differing only as to details that need not detain us here. Everyone +is familiar with sundry applications of the dynamo to the purposes of +to-day's applied science. It must be understood, of course, that the +amount of electricity generated in any dynamo is precisely measurable, +and that by no possibility could the energy thus developed exceed +the energy required to move the coils of wire. Were it otherwise the +great law of the conservation of energy would be overthrown. In actual +practice, of course, there is loss of energy in the transaction. The +current of electricity that flows from the very best dynamo represents +considerably less working power than is expended by the steam engine in +forcibly revolving the armature. In the early days of experiments the +loss was so great as to be commercially prohibitive. With the perfected +modern dynamo the loss is not greater than fifteen per cent; but even +this, it will be noted, makes electricity a relatively expensive power +as compared with steam,--except, indeed, where some natural power, like +the Falls of Niagara, can be utilized to drive the armature. + + +A MYSTERIOUS MECHANISM + +The efficiency of the modern dynamo is due largely to the fact that +when the poles of the magnet are made to face each other, the lines +of magnetic force passing between these poles are concentrated into a +narrow compass. With the ordinary bar magnet, as everyone is aware, +these lines of force circle out in every direction from the poles in +an almost infinite number of loops, all converging at the poles, and +becoming relatively separated at the equator in a manner which may be +graphically illustrated by the lines of longitude drawn on an ordinary +globe. + +It is obvious that with a magnet of such construction only a small +proportion of the lines of magnetic force could be utilized in +generating electricity. But, as already mentioned, when the magnet +is so curved that its poles face each other, the lines of force, +instead of widely diverging, pass from pole to pole almost in a direct +stream. The strength of this magnetic stream may be increased almost +indefinitely by winding the iron core of the magnet with the coil of +wire through which the electric current is passed, thus constituting +the electromagnet which has replaced the old permanent magnet in all +modern commercial dynamos. + +[Illustration: THE EVOLUTION OF THE DYNAMO. + +Fig. 1.--A small example of the original commercial form of the drum +armature machine, patented in 1873 by Dr. Werner Siemens and F. Von +Hefner Alteneck. The armature is a development of the Siemens shuttle +form of 1856, and gives a nearly continuous current. Fig. 2.--An early +experimental dynamo. Fig. 3.--Ferranti's original dynamo, patented in +1882-1883. The field magnets are stationary and consist of two sets +of electro-magnets each with 16 projecting pull pieces, between which +the armature revolves. Fig. 4.--The gigantic rotary converters of the +Manhattan Elevated Railway.] + +An electromagnet may be sufficiently powerful to lift tons of iron. +The force it exerts, therefore, is very tangible in its results. Yet +it seems mysterious, because so many substances are unaffected by it. +You may place your head, for example, between the poles of the most +powerful magnet without experiencing any sensation or being in any +obvious way affected. You may wave your hand across the lines of force +as freely as you may wave it anywhere else in space. Apparently nothing +is there. But were you to attempt to pass a dumb-bell or a bar of iron +across the same space, the unseen magnetic force would wrench it from +your grasp with a power so irresistible as to be awe-inspiring. + +Similarly, the armature, when its coils of wire are adjusted between +the poles of the magnet, is held in a vise-like grip by the invisible +but potent lines of magnetic force which tend to make it revolve. +It requires a tremendous expenditure of energy--supplied by the +steam-engine or by water power--to enable the coiled wires of the +generating armature to stem the current of magnetic force, which is +virtually what is done when the armature revolves in such a way as to +produce electrical energy. Part of the mechanical energy thus expended +is transformed into heat and dissipated into space; but the main +portion is carried off, as we have seen, through the coiled wires of +the armature in the form of what we term the current of electricity, to +be re-transformed in due course into the mechanical energy that moves +the car. + +It appears, then, that the phenomena of the electric dynamo depend upon +the curious relations that exist between magnetism and electricity. +Granted the essential facts of magneto-electric induction, all the +phenomena of the dynamo are explicable. But how explain these facts +themselves? Why is an electric current generated in a coil of wire +moving in a magnetic field? And why is a wire carrying a current of +electricity, when placed across a magnetic field, impelled to move at +right angles to the lines of magnetic force? No thoughtful person can +consider the subject without asking these questions. But as yet no +definitive answer is forthcoming. Some suggestive half-explanations, +based on an assumed condition of torsion or strain in the ether, have +been attempted, but they can hardly be called more than scientific +guesses. + +Meanwhile, it may be understood that the mutual relations of the +magnetic and electrical forces just referred to are not at all +dependent upon the manner in which the electric current is generated. +The magneto-electric motor may be operated as well with a chemical +battery as with such a mechanical generating dynamo as has just been +described. The storage-batteries which have been employed in some +street railways and those which propel the electric cabs about our +city streets furnish cases in point. The only reason these are not +more generally employed is that the storage battery has not yet been +perfected so that it can produce a large supply of electricity in +proportion to its weight, and produce it economically. + + + + +X + +NIAGARA IN HARNESS + + +"Harnessing Niagara"--the phrase has been a commonplace for a +generation; but until very recently indeed it was nothing more than a +phrase. Almost since the time when the Falls were first viewed by a +white man the idea of utilizing their powers has been dreamed of. But +until our own day--until the last decade--science had not shown a way +in which the great current could be economically shackled. A few puny +mill-wheels have indeed revolved for thirty years or so, but these +were of no greater significance than the thousands of others driven by +mountain streams or by the currents of ordinary rivers. But about a +decade ago the engineering skill of the world was placed in commission, +and to-day Niagara is fairly in harness. + +If you have ever seen Niagara--and who has not seen it?-you must have +been struck with the metamorphosis that comes over the stream about +half a mile above the falls. Above this point the river flows with a +smooth sluggish current. Only fifteen feet have the waters sunk in +their placid flowing since they left Lake Erie. But now in the course +of half a mile they are pitched down more than two hundred feet. If +you follow the stream toward this decline you shall see it undergo +a marvelous change. Of a sudden the placid waters seem to feel the +beckoning of a new impulse. Caught with the witchery of a new motion, +they go swirling ahead with unwonted lilt and plunge, calling out with +ribald voices that come to the ear in an inchoate chorus of strident, +high-pitched murmurings. Each wavelet seems eager to hurry on to the +full fruition of the cataract. It lashes with angry foam each chance +obstruction, and gurgles its disapproval in ever-changing measures. +Even to the most thoughtless observer the mighty current thus unchained +attests the sublimity of almost irresistible power. Could a mighty +mill-wheel be adjusted in that dizzy current, what labors might it +not perform? Five million tons of water rush down this decline each +hour, we are told; and the force that thus goes to waste is as if +three million unbridled horses exhausted their strength in ceaseless +plunging. This estimate may be only a guess, but it matters not whether +it be high or low; all estimates are futile, all comparisons inadequate +to convey even a vague conception of the majesty of power with which +the mighty waters rush on to their final plunge into the abysm. + +It is here, you might well suppose, where the appalling force of the +current is made so tangible, that man would place the fetters of his +harness, making the madcap current subject to his will. You will +perhaps more than half expect to see gigantic mechanisms of man's +construction built out over the rapids or across the face of the +cataract--so much has been said of aestheticism versus commercialism in +connection with the attempt to utilize Niagara's power. But whatever +your fears in this regard, they will not be realized. Inspect the +rapids and the falls as you may, you will see no evidence that man +has tampered with their pristine freedom. Subtler means have been +employed to tame the wild steed. The mad waves that go dashing down +the rapids are as free and untrammeled to-day as they were when the +wild Indian was the only witness of their tempestuous activity. Such +portions of the current as reach the rapids have full license to pass +on untrammeled, paying no toll to man. The water which is made to pay +tribute is drawn from the stream up there above the rapids, where it +lies placid and as yet unstirred by the beckoning incline. To see +Niagara in harness, then, you must leave the cataract and the rapids +and pass a full mile up the stream where the great river looks as calm +as the Hudson or the Mississippi, and where, under ordinary conditions, +not even the sound of the falls comes to your ear. + +Prosaic enough it seems to observe here nothing more startling than a +broad _cul de sac_ of stagnant water, like the beginning of a broad +canal, extending in for a few hundred yards only from the main stream; +its waters silent, currentless, seemingly impotent. This stagnant +pool, then, not the whirling current below, is to furnish the water +whose reserve force of energy of position is drawn upon to serve man's +greedy purpose. Coming from the rapids and cataract to this stagnant +canal, you seem to step from the realm of poetic beauty to the sordid +realities of the work-a-day world. Of a truth it would seem that +"harnessing Niagara" is but a far-fetched metaphor. + + +WITHIN THE POWER-HOUSE + +And yet if you will turn aside from the canal and enter one of the +long, low buildings that flank it on either side, you will soon be +made to feel that the metaphor was amply justified. Little as there +was exteriorly to suggest it, you are entering a fairyland of applied +science, and within these plain walls you shall witness evidences +of the ingenuity of man that should appeal scarcely less to your +imagination than the sight of the cataract itself in all its sublimity +of power. + +For within these walls, by a miracle of modern science, the potential +energy which resides in the water of the canal is transformed into +an electrical current which is sent out over a network of wires to +distant cities to perform a thousand necromantic tasks,--propelling a +street car in one place, effecting chemical decompositions in another; +turning the wheels of a factory here and lighting the streets of a city +there; in short, subserving the practical needs of man in devious and +wonderful ways. + +Even as you gazed disdainfully at the stagnant canal, its waters, +miraculously transformed, were propelling the trolley cars along the +brink of the cliff over there on the Canadian shore, and at the same +time were turning the wheels in many a factory in the distant city of +Buffalo. After all, then, the quiet pool of water was not so prosaic as +it seemed. + +As you stand in the building where this wonderful transformation of +power is effected, the noble simplicity of the vista heightens the +mystery. The most significant thing that strikes the eye is a row +of great mushroom-like affairs, for all the world like giant tops, +that stand spinning--and spinning. These great tops are about a dozen +feet in diameter. They are whirling, so we are told, at a rate of two +hundred and fifty revolutions per minute. Hour after hour they spin on, +never varying in speed, never faltering; day and night are alike to +them, and one day is like another. They are as ceaselessly active, as +unwearying as Niagara itself, whose power they symbolize; and, like the +great Falls, they murmur exultingly as they work. + +[Illustration: VIEW IN ONE OF THE POWER HOUSES AT NIAGARA. + +Each of the top-like dynamos generates 5000 horse-power.] + +The giant tops which thus seem to bid defiance to the laws of motion +are in reality electric dynamos, no different in principle from the +electric generators with which some visit to a street-car power-house +has doubtless made you familiar. The anomalous feature of these +dynamos--in addition to their size--is found in the fact that they +revolve on a vertical shaft which extends down into a hole in the earth +for more than a hundred feet, and at the other end of which is adjusted +a gigantic turbine water-wheel. Water from the canal is supplied this +great turbine wheel through a steel tube or penstock, seven feet in +diameter. As the turbine revolves under stress of this mighty column +of water, the long shaft revolves with it, thus turning the electric +generator at the other end of the shaft--the generator at which we +are looking, and which we have likened to a giant top--without the +interposition of any form of gearing whatever. + +To gain a vivid mental picture of the apparatus, we must take an +elevator and descend to the lower regions where the turbine wheel is +in operation. As we pass down and down, our eyes all the time fixed on +the vertical revolving shaft, which is visible through a network of +bars and gratings, it becomes increasingly obvious that to speak of +this shaft as standing in "a hole in the ground" is to do the situation +very scant justice. A much truer picture will be conceived if we think +of the entire power-house as a monster building, about two hundred feet +high, all but the top story being underground. What corresponds to +the ground floor of the ordinary building is located one hundred and +fifty feet below the earth's surface; and it is the top story which we +entered from the street level, thus precisely reversing the ordinary +conditions. + + +PENSTOCKS AND TURBINES + +As we descend now and reach at last the lowest floor of the building, +we step out into a long narrow room, the main surface of which is taken +up with a series of gigantic turnip-shaped mechanisms, each one having +a revolving shaft at its axis; while from its side projects outward and +then upward a seven-foot steel tube, for all the world like the funnel +of a steamship. This seeming funnel--technically termed a penstock--is +in reality the great tube through which the massive column of water +finds access to the turbine wheel, which of course is incased within +the turnip-shaped mechanism at its base. + +As you stand there beside this great steel mechanism a sense of +wonderment and of utter helplessness takes possession of you. As you +glance down the hall at this series of great water conduits, and +strain your eyes upward in the endeavor to follow the great funnel to +its very end, an oppressive sense of the irresistible weight of the +great column of water it supports comes to you, and you can scarcely +avoid a feeling of apprehension. Suppose one of the great tubes were to +burst?--we should all be drowned like rats in a hole. There is small +danger, to be sure, of such a contingency; but it is well worth while +to have stood thus away down here at the heart of the great power-house +to have gained an awed sense of what man can accomplish toward rivaling +the wonders of nature. To have stood an hour ago on the ice bridge at +the foot of the most tremendous cataract in the world, where Nature +exhausts her powers amidst the mad rush and roar of seething waters; +and now to stand beneath this other column of water which effects a no +less wonderful transformation of energy, serenely, silently,--is to +have run such a gamut of emotions as few other hours in all your life +can have in store for you. + + +A MIRACULOUS TRANSFORMATION OF ENERGY + +There are eleven of these great turbine mechanisms, each with a +supplying funnel of water and a revolving shaft extending upward to its +companion dynamo, in the room in which we stand. Energy representing +fifty-five thousand horse-power is incessantly transformed and made +available for man's use in the subterranean building in which we stand. +And there is not a pound of coal, not a lick of flame, not an atom +of steam involved in the transformation. There are no dust-grimed +laborers; there is no glare of furnace, no glow of heat, no stifling +odor of burning fuel;--there is only the restful hum of the machinery +that responds to the ceaseless flow of the silent and invisible waters. +Day and night the mighty river here pulls away at its turbine harness; +and man, having once adjusted that harness, may take his ease and enjoy +the fruits of his ingenuity. + +As we return now to the top of the building, we shall view the spinning +dynamos with renewed interest, and a few facts regarding their output +of energy may well claim our attention. In their principle of action, +as we have seen, all dynamos are alike,--depending upon the mutual +relations between the wire-wound armature and a magnetic field. In the +present case the magnets are made to revolve and the armatures are +stationary, but this is a mere detail. There is one feature of these +dynamos, however, which is of greater importance,--the fact namely that +they operate without commutators, and therefore produce alternating +currents. This fact has an important bearing upon the distribution of +the current. Each of the dynamos before us generates the equivalent +of five thousand horse-power of energy. There are eleven such dynamos +here before us; there are ten more in the power-house on the other +side of the canal, giving a total of one hundred and five thousand +horse-power for this single plant; and there are five such plants now +in existence or in course of construction to utilize the waters of +Niagara, three being on the Canadian shore. When in full operation the +aggregate output of these plants will be six or seven hundred thousand +horse-power. + + +SUBTERRANEAN TAIL-RACES + +As we step from the door of the power-house and stand again beside the +canal whose waters produce the wonderful effects we have witnessed +in imagination, one question remains to be answered: What becomes of +the water after it has passed through the turbine wheels down there +in the depths? The answer is simple: All the water from the various +turbines flows away into a great subterranean canal which passes down +beneath the city of Niagara Falls, and discharges finally at the level +of the rapids a few hundred yards below the Falls. The construction of +this subterranean canal would in itself have been considered a great +engineering feat a few decades ago; but of late years mountain tunnels, +such subterranean railways as the London "tube system" and tunnels +beneath rivers have robbed such structures of their mystery. It may be +added that another such subterranean canal, to serve as a tail-race for +one of the new Canadian plants, extends beneath the cataract itself, +discharging not far from the centre of the Horseshoe Falls. Another of +the power companies utilizes the water of the old surface canal which +extends to the brink of the gorge some distance below the Falls. Yet +another company on the Canadian side conveys water from far above the +rapids in a gigantic closed tube to the brink of the gorge just below +the Canadian Falls, above the point where their power-house is located. + +But the principle involved is everywhere the same. The idea is merely +to utilize the weight of falling water. The water of Niagara River +is of course no different from any other body of water of equal size. +It is merely that its unique position gives the engineer an easy +opportunity to utilize the potential energy that resides in any body +of water--or, for that matter, in any other physical substance--lying +at a high level. In due course, doubtless, other bodies of water, +such as mountain lakes and mountain streams will be similarly put +into electrical harness. The electrical feature is of course the one +that most appeals to the imagination. But it may be well to recall +that the ultimate source of all the power in question is gravitation. +People fond of philosophical gymnastics may reflect with interest that, +according to the newest theory, gravitation itself is, in the last +analysis, an electrical phenomenon--a reflection which, it will be +noted, leads the mind through a very curious cycle. + + +THE EFFECT ON THE FALLS + +Much solicitude has been expressed as to the possible effect, upon the +Falls themselves, of this withdrawal of water. For the present, it is +admitted, there is no visible effect; and to the casual observer it +may seem that almost any quantity of water the power-houses are likely +to need might be withdrawn without seriously marring the wonderful +cataract. But the statistics supplied by the power companies, taken in +connection with estimates as to the bulk of water that passes over the +Falls, do not support this optimistic view. Taking what seems to be a +reasonable estimate for a basis of computation it would appear that +when the power-houses now rapidly approaching completion are in full +operation, the total withdrawal of water from the stream will represent +a very appreciable fraction of its entire bulk--one-twenty-fifth at +the very least, perhaps as much as one-tenth. Such a diminution as +this will by no means ruin the Falls, yet it would seem as if it must +sensibly affect them, particularly at some places near Goat Island, +where the water flows at present in a very shallow stream. Be that as +it may, however, the power-houses are there, and it is probable that +their number will be added to as years go on. Whether commercialism or +aestheticism will win in the end, it remains for the legislators of the +future to decide. + +Meanwhile, it is gratifying to reflect that for the present the Falls +retain their pristine beauty, even though part of the water that is +their normal due is turned aside and made to do service for man in +another way. There is only one reason why the Falls have escaped +desecration so long as they have; that reason being the very practical +one that until quite recently man has not known how to utilize their +powers to advantage. The effort was indeed made, a full generation +ago, through the construction of the canal leading from the upper +river to the bluffs overlooking the gorge below the cataract. Here +a few mill-wheels were set whirling, and a tiny fraction of the +potential energy of the water was utilized. There was no mechanical +difficulty involved in the utilization of this power. Mill-wheels are +a familiar old-time device, and even the turbine wheel is modern only +in a relative sense of the word. And it must be understood that the +turbine water-wheel utilizes the greatest proportion of the power of +falling water of any contrivance as yet known to mechanics. It was +possible, then, to utilize the water of Niagara with full effectiveness +fifty years ago, so far as the direct action of the water-wheel upon +machinery near at hand was concerned. The sole difficulty lay in the +fact that only a small amount of machinery can be placed in any one +location. The real problem was not how to produce the power, but how to +transmit it to a distance. + + +THE TRANSMISSION OF POWER + +For fifty years mechanical engineers have looked enviously upon +unshackled Niagara, and have striven to solve the problem of +transmitting its power. It were easy enough to harness the great Fall, +but futile to do so, so long as the power generated must be used in the +immediate vicinity. So, many schemes for transmitting power were tried +one after another, and as often laid aside. There was one objection +to even the best of them--the cost. At one time it was thought that +compressed air might solve the problem. But repeated experiments did +not justify the hope. Then it was believed that the storage battery +might be made available. The storage battery, it might be explained, +does not really store electricity in the sense in which the Leyden +jar, for example, stores it. Rather is it to be likened to an ordinary +voltaic cell, the chemical ingredients of which have been rendered +active by the passage of the electric current. The active ingredients +of the storage battery are usually lead compounds, which through action +of the electric currents have been decomposed and placed in a state of +chemical instability. The dissociated molecule of the lead compound, +when permitted to reunite with the atoms with which it was formerly +associated, will give up electrical energy. + +Such a storage battery might readily be charged with electricity +generated at Niagara Falls. It might then be conveyed to any part of +the world, and, its poles being connected, the charge of electricity +would be made available. Such storage batteries are in common use +in connection with electric automobiles, as we have seen. But the +great difficulty is that they are enormously heavy in proportion to +the amount of electricity that they can generate; therefore, their +transportation is difficult and expensive. In practice it is cheaper +to produce electricity through the operation of a steam engine in a +distant city than to transmit the electricity with the aid of a storage +battery from Niagara. So the storage battery served as little as +compressed air to solve the engineer's problem. + +When the electric dynamo became a commercial success for such purposes +as the operation of trolley lines it seemed as if the Niagara problem +was on the verge of solution. And so, in point of fact, it really was, +though more time was required for it than at first seemed needed. The +power generated by the dynamo could, indeed, be transmitted along a +wire, but not without great loss. Sir William Siemens, in 1877, had +pointed out in connection with this very subject of the wasted power +of Niagara, that a thousand horse-power might be transmitted a distance +of, say, thirty miles over a copper rod three inches in diameter. But a +copper rod three inches in diameter is enormously expensive, and when +Siemens further stated that sixty per cent of the power involved would +be lost in transmission, it was obvious that the method was far too +wasteful to be commercially practicable. + +For a time the experimenters with the transmission of electricity +along a wire were on the wrong track. They were experimenting with a +continuous current which, as we have seen, is produced from an ordinary +dynamo with the aid of a commutator. But hosts of experiments finally +made it clear that this form of current, no matter how powerful it +might be, is unable to traverse considerable distance without great +loss, being frittered away in the form of heat. + +But the very term "continuous current" implies the existence of a +current that is not continuous. In point of fact, we have already +seen that a dynamo, if not supplied with a commutator, will produce +what is called an alternating current, and such a current has long +been known to possess properties peculiar to itself. It is, in +effect, an interrupted current, and it is sometimes spoken of as if +it really consisted of an alternation of currents which move first in +one direction and then in another. Such a conception is not really +justifiable. The more plausible explanation is that the alternating +current is one in which the electrons are not evenly distributed and +move with irregular motion. Perhaps we may think of the individual +electrons of such a current as oscillating in their flight, and, as +it were, boring their way into the resisting medium. In any event, +experience shows that such a current, under proper conditions, may be +able to traverse a conducting wire for a long distance with relatively +small loss. + +It must be understood, however, that the mere fact that a current +alternates is not in itself sufficient to make feasible its +transmission to a remote distance. To meet all the requirements a +current must be of very high voltage. This means, in so far as we +can represent the conditions of one form of energy in the terms of +another, that it shall be under high pressure. Fortunately a relatively +simple apparatus enables the electrician to transform a current from +low to high voltage without difficulty. And so at last the problem +of transmitting power to a distance of many miles has been solved. +Electrical currents representing thousands of horse-power are to-day +transmitted from Niagara Falls to the city of Buffalo over ordinary +wires, with a loss that is relatively insignificant. A plant is in +process of construction that will similarly transmit the power to +Toronto; and it is predicted that in the near future the powers of +Niagara will be drawn upon by the factories of cities even as far +distant as New York and Chicago. Practical difficulties still stand in +the way of such very distant transmission, to be sure, but these are +matters of detail, and are almost certain to be overcome in the near +future. + +All this being explained, it will be understood that the sole reason +why the new power-houses at Niagara generate electricity is that +electricity is the one readily transportable carrier of energy. We have +already explained that there is loss of energy when the steam engine +operates the dynamo. At Niagara, of course, no steam is involved; it +is the energy of falling water that is transformed into the energy of +the electrical current. Moreover, the revolving dynamo is attached to +the same shaft with the turbine water-wheel, so that there is no loss +through the interposition of gearing. Yet even so, the electric current +that flows from the dynamo represents somewhat less of energy than +the water current that flows into the turbine. This loss, however, is +compensated a thousandfold by the fact that the energy of the electric +current may now be distributed in obedience to man's will. + + +"STEP UP" AND "STEP DOWN" TRANSFORMERS + +The dynamos in operation at Niagara do not differ in principle from +those in the street-car power-house, except in the fact that they +are not supplied with commutators. We have seen that these dynamos +are of enormous size. Those already in operation generate five +thousand horse-power; others in process of construction will develop +ten thousand. The generator which produces this enormous current is +about eleven feet in diameter, and it makes two hundred and fifty +revolutions per minute. The armatures are so wound that the result is +an alternating current of electricity of twenty-two hundred volts. +This current represents, it has been said, raw material which is to +be variously transformed as it is supplied to different uses. To +factories near at hand, indeed, the current of twenty-two hundred +volts is supplied unchanged; but for more distant consumption it is +raised to ten thousand volts; and that portion which is sent away to +the factories of Buffalo and other equally distant places is raised to +twenty-two thousand volts. + +[Illustration: ELECTRICAL TRANSFORMERS. + +The upper figure shows Ferranti's experimental transformer built in +1888. It has a closed iron circuit, built up of thin strips filling the +interior of the coil and having their ends bent over and overlapping +outside. The lower figure shows a simple transformer known as +Sturgeon's induction coil. The middle figure gives a view of the series +of converters in the power house of the Manhattan Elevated Railway.] + +The transformation from a relatively low voltage to the high one +is effected by means of what is called a step-up transformer. This +is an apparatus which brings into play a principle of electric +induction not very different from that which was responsible for the +generation of the current of electricity in the dynamo. The principle +is that evidenced in the familiar laboratory apparatus known as the +Ruhmkorff coil. The transformer consists essentially of a primary +coil of relatively large wire, surrounded by, but insulated from, a +secondary coil of relatively fine wire. When the interrupted current +is sent through the primary coil of such an apparatus, an induced +counter-current is generated in the secondary coil. Of course there is +no gain in the actual quantity of electricity, but the voltage of the +current generated in the finer wire is greatly increased. For example, +as we have seen, the current that came from the dynamo at twenty-two +hundred volts is raised to ten thousand or twenty-two thousand volts. +These proportions may be varied indefinitely by varying the relative +sizes and lengths of the primary and secondary coils. + +How shall we picture to ourselves the actual change in the current +represented by this difference in voltage? We might prove, readily +enough, that the difference is a real one, since a wire carrying a +current of low voltage may be handled with impunity, while a similar +wire carrying a current of high voltage may not safely be touched. But +when we attempt to visualize the difference in the two currents we are +all at sea. We may suppose, of course, that electrons spread out over a +long stretch of the secondary coil must be more widely scattered. One +can conceive that the electrons, thus relatively unimpeded, may acquire +a momentum, and hence a penetrative power, which they retain after they +are crowded together in a straight conductor. But this suggestion at +best merely hazards a guess. + +Arrived at the other end of its journey, the current which travels +under this high voltage is retransformed into a low-voltage current +by means of an apparatus which simply reverses the conditions +of the step-up transformer, and which, therefore, is called a +step-down transformer. The electricity which came to Buffalo as a +twenty-two-thousand-volt current is thus reduced by any desired +amount before it is applied to the practical purposes for which it is +designed. It may, for example, be "stepped-down" to two thousand volts +to supply the main wires of an electric-lighting plant; and then again +"stepped-down" to two hundred volts to supply the electric lamps of an +individual house. + +Who that reads by the light of one of these electric lamps, let us say +in Buffalo, and realizes that he is reading by the transformed energy +of Niagara River, dare affirm that in our day there is nothing new +under the sun? + + + + +XI + +THE BANISHMENT OF NIGHT + + +One great fundamental advantage that man has won over the other +animals is that although by nature a diurnal animal he has made night +almost equally subject to his dominion through the use of artificial +light. He thus establishes an average day of sixteen or eighteen +hours in place of the twelve-hour day within which his activities +would otherwise be restricted. Of course this conquest of the night +began at an early stage of the human development, since a certain +familiarity with the uses of fire was attained long before man came out +of the ages of savagery. But when the transition had been made from +the primitive torch to the simplest type of lamp, there was for many +centuries a cessation of progress in this direction, and it remained +for comparatively recent generations to provide more efficient methods +of lighting. Indeed, the culminating achievements are matters which +make the most recent history. It is the purpose of the ensuing pages +to narrate the story of the successive practical achievements through +which man has been enabled virtually to turn night into day. + + +PRIMITIVE TORCH AND OPEN LAMP + +To moderns, in an age when even the time-honored gas jets and kerosene +lamps are regarded as obsolescent, that ancient form of illuminant, +the candle, seems about the most primitive form of light-producing +apparatus. In point of fact, however, the candle holds no such place +in the chronological order of lighting-device discovery, being a +relatively late innovation. Indeed, lamps of various kinds, even those +burning petroleum, were used thousands of years before the relatively +clean and effective candle was invented. + +The camp fires of primitive man must have suggested the use of a +fire-brand for lighting purposes almost as soon as the discovery of +fire itself; but the development of any means of lighting his caves or +rude huts, even in the form of torches, was probably a slow process. +For our earliest ancestors were not the nocturnal creatures their +descendants became early in the history of civilization. To them the +period of darkness was the time for sleeping, and their waking hours +were those between dawn and dusk. It was only when man had reached a +relatively high plane above the other members of the animal kingdom, +therefore, that he would wish to prolong the daylight, and then the use +of the torch made of some resinous wood would naturally suggest itself. + +Just when the ancient lamp was invented in the form of a vessel +filled with oil into which some kind of wick was dipped, cannot be +ascertained, but its invention certainly antedated the Christian Era +by several centuries. And it is equally certain that once this smoky, +foul-smelling lamp had been discovered, it remained in use, practically +without change or improvement, until the end of the twelfth century, +the date of the invention of the candle. Such lamps were used by the +Greeks and Romans, great quantities of them being still preserved. They +were simply shallow, saucer-like vessels for holding the oil, into +which the wick was laid, so arranged that the upper end rested against +the edge of the vessel. Here the oil burned and smoked, capillarity +supplying oil to the burning end of the wick, which was pulled up from +time to time as it became shortened by burning, either with pincers +made for the purpose, or perhaps more frequently by the ever useful +hairpin of the matron. + +As the thick wick did not allow the air to penetrate to burn the carbon +of the oil completely, a nauseous smoke was given off constantly which +was stifling when a draught of air prevented its escape through the +hole in the roof--the only chimney used by the Greeks. And since this +was the only kind of lamp known at the time, the palace of the Roman +Emperor and hut of the Roman peasant were necessarily alike in their +methods of lighting if in little else. The Emperor's lamps might be +modeled of gold and set with precious stones, while those of the +peasant were of rudely modeled clay; but each must have evoked, along +with its dim light, an unwholesome modicum of smoke and malodor. + +It was this form of lamp, practically unaltered except occasionally in +design, that remained in common use during the Middle Ages; and when, +at the close of the twelfth century, the "tallow candle" was invented, +that now despised device must have been almost as revolutionary in its +effect as the incandescent burner and the electric bulb were destined +to be in a more recent generation. It burned with dazzling brilliancy +in comparison with the oil lamp; it gave off no smoke and little smell; +it needed no care, and it occupied little space. Then for the first +time in the history of the world reasonably good house illumination +became possible. Several additional centuries elapsed, however, before +the idea was developed of placing a candle in a covered glass-sided +receptacle, to form a lantern or a street lamp. + +For generations the candle held supreme place, though its cost made it +something of a luxury; doubly so if wax was substituted for tallow in +its composition. But toward the close of the eighteenth century, when +the action of combustion had begun to be better understood, attempts +were made to improve the wicks and burners of oil lamps. In 1783, an +inventor named Leger, of Paris, produced a burner using a broad, flat, +ribbonlike wick in which practically every part of the oil supply was +brought into contact with the air, producing, therefore, a steady flame +relatively free from smoke. The flame, while broad, was extremely thin, +and its light was consequently radiated very unevenly. Portions of a +room lying in the direction of the long axis of the flame were but +poorly lighted. To overcome this difficulty, a curved form of burner +was adopted; and this led eventually to the invention of the circular +Argand burner, the prototype of the best modern lamp-burners. + + +TALLOW CANDLE AND PERFECTED OIL LAMP + +Stated in scientific terms, the problem of the ideal lamp-wick resolves +itself into a question of how to supply oxygen to every portion of +the flame in sufficient quantities to bring all the carbon particles +to a temperature at which they are luminous. It occurred to Argand +that this could be done by giving the wick a circular form like a +cylindrical tube, giving the air free access to the centre of the tube +as well as to its outer surface. In his lamp the reservoir of oil was +placed at a little distance from, and slightly above, the tube holding +the burner, connected with it by a small tube much as the tank of +the modern "student lamp" connects with the burner. In this manner a +fairly good lamp was produced,--a decided improvement over any made +heretofore,--and when, in 1765, Quinquet added a glass chimney to this +lamp a new epoch of artificial lighting was inaugurated. "This date is +of as much importance in artificial lighting as is 1789 in politics," +says one writer. "Between the ancient lamps and the lamps of Quinquet +there is as much difference as between the chimney-place of our parlors +and the fireplaces of our original Aryan ancestors, formed by a hole +dug in the ground in the centre of their cabins." + +A little later Carcel still further improved the Quinquet lamp by +adapting a clock movement that forced the oil to rise to the wick, +so that it was no longer necessary to have the burner and the +reservoir separated by a tube. This was still further improved upon +by substituting a spring for the clockwork, the result being a lamp +of great simplicity, yet one which gave such results that it replaced +the candle as a unit for measuring the illuminating power of different +sources of light. + +These various burners should not be confused with the modern burners of +the ordinary kerosene lamps. Mineral oils had not as yet come into use +for illuminating purposes, except as torches or in simple lamps like +those of the Romans, as refining processes had not been perfected, and +the smoke and odors from crude petroleum were absolutely intolerable in +closed rooms. + +Many other substances were tried in place of the heavy oils, such as +the volatile hydrocarbons and alcohols, but with no great success. +Early in the nineteenth century a lamp burning turpentine, under +the name of "camphine," was invented that gave a good light and was +smokeless; but like most others of its type, it was dangerous owing +to its liability to explode. And it was not until methods of refining +petroleum had been improved that "mineral-oil lamps"--the predecessors +of the modern type of lamps--came into use. + +The invention of this type of lamp was a relatively easy task--a +simple transition and adaptation as processes of refining the oil were +perfected. The principle of combustion was, of course, the same as in +the Argand type of lamps burning animal and vegetable oils; but mineral +oils are of such consistency that capillarity causes an abundant supply +of oil to rise in the wick, so that clockwork and spring devices, such +as were used in the Carcel lamps, could be dispensed with. + + +GAS LIGHTING + +While the rivalry between the candle and the new forms of lamps was at +its height, and just as the lamp was gaining complete supremacy, a new +method of artificial illumination was discovered that was destined to +eclipse all others for half a century, and then finally to succumb to a +still better form. As early as the beginning of the eighteenth century +the Rev. Joseph Clayton, in England, had made experiments in the +distillation of coal, producing a gas that was inflammable. A little +later Dr. Stephen Hales published his work on _Vegetable Staticks_, in +which he described the process of distilling coal in which a definite +amount of gas could be obtained from a given quantity of coal. + +No practical use was made of this discovery, however, until over +half a century later. But just at the close of the century a Scot, +William Murdoch, became interested in the possibilities of gases +as illuminants, and finally demonstrated that coal gas could be +put to practical use. In 1798, being employed in the workshops of +Boulton and Watt in Birmingham, he fitted up an apparatus in which he +manufactured gas, lighting the workshops by means of jets connected by +tubes with this primitive plant. Shortly after this, a Frenchman, M. +Lebon, lighted his house in Paris with gas distilled from wood, and +the Parisians soon became interested in the new illuminant. England +seems to have been the first country to use it extensively in public +buildings, however, the London Lyceum Theatre being lighted with gas +in 1803. By 1810 the great Gas-Light and Coke Company was formed, and +within the next five years gas street-lamps had become familiar objects +in the streets of London, and house illumination by this means a common +thing among the wealthier classes. + +In the early days of gas-lighting the results were frequently +disappointing, because no suitable and efficient type of burner had +been devised; but in 1820 Neilson of Glasgow discovered the principle +of the now familiar flat burner, of which more examples still remain +in use the world over than of all other kinds combined. Indeed, this +simple, but as we now regard it, inefficient burner, would probably +have remained the best-known type for many years longer than it did +had not the possibilities of lighting by electricity aroused persons +interested in the great gas-plants to the fact that the new illuminant +was jeopardizing their enormous investments; making it clear that they +must bestir themselves and improve their flat burners if they would +arrest disaster. To be sure, several modifications of the round Argand +burner had been introduced from time to time, some of them being a +distinct improvement over the flat burner, but these did not by any +means seriously compete with electric light. And it was not until the +incandescent mantle was perfected that gas as a brilliant illuminant +was able to make a stand against its new competitor. + + +THE INCANDESCENT GAS MANTLE + +It has been known almost since the beginnings of civilization that all +solids can be made to emit light when heated to certain temperatures. +Some substances were known to be peculiarly adapted to this purpose, +such as lumps of lime, and for many years the calcium light or +"lime-light" as it is popularly called, had been in use for special +purposes, and was the most intense light known. This light is made by +heating a block of lime to the highest practicable temperature by means +of a blast of oxygen and coal gas; but such lights were too complicated +and expensive for general purposes. It had been determined even as +early as the beginning of the nineteenth century, however, that the +high temperature necessary for producing this light was due in part at +least to the fact that such a large amount of material had to be raised +to incandescence. It was evident, therefore, that if a small amount +of some such substance as lime and magnesia could be spread out so as +to present a large surface in a small space, such as is represented +by basket-work, sufficient heat for making it incandescent might be +obtained from an ordinary gas-and-air blowpipe. + +Here then was the germ of the "mantle" idea; and such an apparatus, +known as the Clamond mantle, which was made of threads of calcined +magnesia, was shown at the Crystal Palace Exhibition, in London, in +1882. Curiously enough, this mantle and burner worked in an inverted +position, the mantle being suspended bottom upwards below the burner +through which the blast of gas was forced. The light given by this +mantle was most brilliant--little short of the older calcium light, +in fact--but the device itself was too complicated to be of service +for ordinary lighting purposes. The principle was correct, but the +construction of the mantle was defective. + +Meanwhile a German scientist, Dr. Auer von Welsbach, who had become +famous in the scientific world for his researches on rare metals, was +experimenting with certain oxides of different metals, and developing +a method of handling them that finally resulted in the perfected +incandescent burner in use at present. His process, which in theory at +least was not entirely original with him, was to dip an open fabric +of cotton into a solution of the nitrates of the metals to be used, +drying it, and converting the nitrates into oxides by burning; the +cotton fabric disappearing but leaving the skeleton of the oxide, which +retained its original shape. + +At the same time corresponding improvements were made in the type of +burner, which is quite as essential to success as the mantle itself. +It had been found that it was absolutely essential for such a burner +to give a practically non-luminous flame, as otherwise the deposit of +carbon particles will ruin the mantle. Two ways of obtaining this are +possible; one by mixing a certain quantity of air with the gas before +combustion, the other to burn the gas in so thin a flame that the air +permeates it freely. Several burners of both types were used at first, +but gradually the burners in which the air is mixed with the gas became +the more popular, and most of the incandescent burners now on the +market are of this type. + +In the construction of mantles at the present time, while the principle +of their use remains the same as that of the lime-light, lime itself +is not used, the oxides of certain other metals having proved better +adapted for the purpose. Thus the Welsbach patent of 1886 covered the +use of thoria, either alone or mixed with other substances such as +zirconia, alumina, magnesia, etc.; thoria being considered as having +a very high power of light emission. Later it was discovered that +pure thoria emits very little light by itself, although it possesses +a refractory nature that gives a stability to the mantle unequalled +by any other material as yet discovered. When combined with a small +trace of the oxides of certain rare metals, however, such as uranium, +terbium, or cerium, thoria mantles have a very high power of light +emission, most modern mantles being composed of about ninety-nine per +cent. thoria with one per cent. cerium. + +In the ordinary method of manufacturing such mantles, a cotton-net +cylinder about eight inches long, more or less according to the size +of mantle required, is made, one end being contracted by an asbestos +thread. A loop of the same material, or in some cases a platinum wire, +is fastened across the opening, to be used for suspending the mantle +when in use. The cotton-thread cylinder is soaked in a solution of +the nitrates of the metals thorium and cerium, and is then wrung out +to remove the excess, stretched on a conical mold, and dried. The +flame of an atmospheric burner being applied to the upper part at the +constricted position, the burning extends downward, converting the +nitrates into oxides, and removing the organic matter. Considerable +skill is required in this part of the process, as the regular shape of +the mantle is largely dependent upon the regularity of the burning. +As a finishing process a flame is applied to the inside of the mantle +after it has cooled, to remove all traces of carbon that may remain. + +The mantle is now ready for use, but is so fragile that it can scarcely +be touched without breaking, and such handling as would be necessary +for shipment would be out of the question. It is therefore strengthened +temporarily by being dipped into a mixture of collodion and castor oil, +which, when dry, forms a firm but elastic jacket surrounding all parts. +It is this collodion jacket that is burned away when the new mantle is +placed on the burner before the gas is turned on. + +Quite recently the method of manufacturing mantles used by Clamond has +been revived. In this method the cotton thread is dispensed with, the +thread used being made from a paste containing the mantle material +itself. The paste is placed in a proper receptacle the bottom of +which is perforated with minute openings, and subjected to pressure, +squeezing out the material in long filaments. When dry these are wound +on bobbins, and, after being treated by certain chemical processes, are +ready for weaving into mantles. It is claimed for mantles made on this +principle that they last much longer and retain their light-emitting +power more uniformly than mantles made by the older process. + + +THE INTRODUCTION OF ACETYLENE GAS + +When the incandescent mantle had been perfected so as to be an +economical as well an as efficient light-giver, the position of coal +gas as an illuminant seemed again secured against the encroachments +of its rivals, the arc and incandescent electric lights. But just at +this time another rival appeared in the field that not only menaced +the mantle lamp but the arc and incandescent light as well. Curiously +enough, this new rival, acetylene gas, had been brought into existence +commercially by the electric arc itself. For although it had been +known as a possible illuminant for many years, the calcium carbide for +producing it could not be manufactured economically until the advent of +the electric furnace, itself the outcome of Davy's arc light. + +Even as early as 1836 an English chemist had made the discovery that +one of the by-products of the manufacture of metallic potassium would +decompose water and evolve a gas containing acetylene; and this was +later observed independently from time to time by several chemists in +different countries. No importance was attached to these discoveries, +however, and nothing was done with acetylene as an illuminant until the +last decade of the nineteenth century. By this time electric furnaces +had come into general use, and it was while working with one of these +furnaces in 1892 that Mr. Thomas F. Wilson, in preparing metallic +calcium from a mixture of lime and coal, produced a peculiar mass of +dark-colored material, calcium carbide, which, when thrown into water, +evolved a gas with an extremely disagreeable odor. When lighted, this +gas burned with astonishing brilliancy, and, as its cost of production +was extremely small, the idea of utilizing it for illuminating was at +once conceived and put into practice. + +The secret of the cheap manufacture of the carbide lies in the +fact that the extremely high temperature required--about 4500 deg. +Fahrenheit--can be obtained economically in the electric furnace, +but not otherwise. Thus electricity created its own greatest rival +as an illuminant. It followed naturally that the ideal place for +manufacturing the carbide would be at the source of the cheapest supply +of electricity, and as the "harnessed" Niagara Falls represented the +cheapest source of electric supply, this place soon became the centre +of the carbide industry. Here the process of manufacture is carried out +on an enormous scale. In practice, lime and ground coke are thoroughly +mixed in the proportion of about fifty-six parts of lime to thirty-six +parts of coke. When this mixture has been subjected to the heat of the +electric furnace for a short time an ingot of pure calcium carbide is +formed, surrounded by a crust of less pure material. The ingot and +crust together represent sixty-four parts of the original ninety-two +parts of lime and coke, the remaining twenty-eight parts being +liberated as carbon-monoxide gas. + +Calcium carbide as produced by this process is a dark-brown crystalline +substance which may be heated to redness without danger or change. It +will not burn except when heated in oxygen, and will keep indefinitely +if sealed from the air. Chemically it consists of one atom of lime +combined with two atoms of carbon (CaC2); and to produce acetylene +gas, which is a combination of carbon and hydrogen (C2H2) it is +only necessary to bring it into contact with water, acetylene gas and +slaked lime being formed. One pound of pure carbide will produce five +and one half cubic feet of gas of greater illuminating power than +any other known gas. The flame is absolutely white and of blinding +brilliancy, giving a spectrum closely approximating that of sunlight. +The light is so strongly actinic that it is excellent for photography. + +Here was a gas that could be made in any desired quantities simply by +adding water to a substance costing only about three cents a pound; +its cost of production, therefore, representing only about one sixth +of the dollar-per-thousand-feet rate usually charged for illuminating +gas in our cities. It could be used in lamps and lanterns made with +special burners and with the simple mechanism of a small water tank +which allowed water to drip into a receptacle holding the carbide; +or--reversing the process--an apparatus that dropped pieces of carbide +into the water tanks. It was, in short, the cheapest illuminant known, +generated by an apparatus that was simplicity itself. + +There were, however, two defects in this gas: its odor was +intolerable--the "smell of decayed garlic," it has been aptly +called--and when mixed with air it was highly explosive. The first of +these defects could be overcome easily; when the burner consumed all +the gas there was no odor. The second, the explosive quality, presented +greater difficulties. These were emphasized and magnified by the number +of defective lamps that soon flooded the market, many of these being so +badly constructed that explosions were inevitable. As a result a strong +prejudice quickly arose against the gas, some countries passing laws +prohibiting its use. + +But further inquiry into the cause of the frequent disasters revealed +the fact that when the burner of a lamp was constructed so that the air +for combustion was supplied after the gas issued from the jet, there +was no danger of explosion. And as lamps carefully constructed on this +principle replaced the early ones of faulty construction, confidence +in acetylene was restored. Methods were devised for supplying the gas +for house-illumination like ordinary gas, and the occupants of country +houses were afforded a means of lighting their houses on a scale of +brilliancy hitherto unapproached, yet with economy and relative safety. + +It was found also that the brilliancy of the acetylene flame was of +such intensity that it could be used, like the electric arc light, as a +search-light. It thus furnished a simple means of supplying small boats +and vehicles with such lights, which they could not otherwise have +had. It also supplied army signal-corps with an apparatus for flashing +messages--an apparatus that was ideal on account of its simplicity and +small size. + +At the Pan-American Exhibition at Buffalo the various illuminating +exhibits were among the most conspicuous and attractive features. But +even amid the dazzling electrical displays the Acetylene Building was +a noteworthy object. "It was the most brilliantly and beautifully +lighted building in the grounds," declared one observer. "It sparkled +like a diamond, and was the admiration of all visitors. In it were +generators of all types--most of them supplying the gas for their own +exhibits--several being the latest exponents of the art, so simple that +they can be safely managed by unskilled labor; in fact, 'the brains are +in the machines,' and when the attendant has charged them with carbide +and filled them with water--given them food and drink--they will work +steadily until they need another meal." Indeed, these exhibits at the +Pan-American Exhibition demonstrated conclusively that acetylene gas +occupies a field by itself as a practical illuminant. + +At the same exposition a standard was established for good stationary +acetylene generators for house-lighting, and the fact that a large +number of generators fulfilled the requirements of the set of rules +laid down showed how thoroughly the problem of handling this gas has +been solved. Some of these rules used as tests are instructive to +anyone interested in the subject, and a few of them are given here. +They specified, for example, that-- + +"The carbide should be dropped into the water," the reverse process of +letting the water drip on the carbide, as was done in most of the early +generators, being condemned. "There must be no possibility of mixing +air with the acetylene gas. Construction must be such that an addition +to the charge of carbide can be made at any time without affecting the +lights. Generators must be entirely automatic in their action--that is +to say: after a generator has been charged, it must need no further +attention until the carbide has been entirely exhausted. The various +operations of discharging the refuse, filling with fresh water, +charging with carbide, and starting the generator must be so simple +that the generator can be tended by an unskilled workman without danger +of accident. When the lights are out, the generation of gas should +cease. The carbide should be fed automatically into the water in +proportion to the gas consumed." + +Perhaps the most significant thing, showing the stage of progress that +has been made in overcoming the danger of explosions from acetylene +gas, is that the use of generators meeting some such requirements as +the above is not prohibited by fire underwriters. This in itself is +very convincing evidence of their safety. + + +THE TRIUMPH OF ELECTRICITY + +Throughout the ages primitive man had had constantly before him two +sources of light other than that of the sun, moon, and stars. One +of these, the fire of ordinary combustion, he could understand and +utilize; the other, more powerful and more terrible, which flashed +across the heavens at times, he could not even vaguely understand, and, +naturally, did not attempt to utilize. But early in the seventeenth +century some scientific discoveries were made which, although their +destination was not even imagined at the time, pointed the way that +eventually led to man's imitating in the most striking manner Nature's +electrical illumination. + +About this time Otto von Guericke, the burgomaster-philosopher of +Magdeburg, in the course of his numerous experiments, had discovered +some of the properties of electricity, by rubbing a sulphur ball, and +among other things had noticed that when the ball was rubbed in a +darkened room, a faint glow of light was produced. He was aware, also, +that in some way this was connected with the generation of electricity, +but in what manner he had no conception. In the opening years of the +following century Francis Hauksbee obtained somewhat similar results +with glass globes and tubes, and made several important discoveries +as to the properties of electricity that stimulated an interest in +the subject among the philosophers of the time. Gray in England, and +Dufay in France, who became enthusiastic workers in the field, soon +established important facts regarding conduction and insulation, and +by the middle of the eighteenth century the production of an electric +spark had become a commonplace demonstration. + +But until this time it had not been demonstrated that this electric +spark was actual fire, although there was no disputing the fact that +it produced light. In 1744, however, this point was settled definitely +by the German, Christian Friedrich Ludolff, who projected a spark +from a rubbed glass rod upon the surface of a bowl of ether, causing +the liquid to burst into flame. A few years later Benjamin Franklin +demonstrated with his kite and key that lightning is a manifestation of +electricity. + +But neither the galvanic cell nor the dynamo had been invented at +that time, and there was no possibility of producing anything like a +sustained artificial light with the static electrical machines then +in use. It was not until the classic discovery of Galvani and the +resulting invention of the voltaic, or galvanic, cell shortly after, +that the electric light, in the sense of a sustained light, became +possible. And even then, as we shall see in a moment, such a light was +too expensive to be of any use commercially. + + +DAVY AND THE FIRST ELECTRIC LIGHT + +As soon as Volta's great invention was made known a new wave of +enthusiasm in the field of electricity swept over the world, for the +constant and relatively tractable current of the galvanic battery +suggested possibilities not conceivable with the older friction +machines. Batteries containing large numbers of cells were devised; one +having two thousand such elements being constructed for Sir Humphry +Davy at the Royal Institution, of London. By bringing two points of +carbon, representing the two poles of the battery, close together, Davy +caused a jet of flame to play between them--not a momentary spark, but +a continuous light--a true voltaic arc, like that seen in the modern +street-light to-day. + +"When pieces of charcoal about an inch long and one-sixth of an inch in +diameter were brought near each other (within the thirtieth or fortieth +of an inch)," wrote Davy in describing this experiment, "a bright +spark was produced, and more than half the volume of charcoal became +ignited to whiteness; and, by withdrawing the points from each other, a +constant discharge took place through the heated air, in a space equal +to at least four inches, producing a most brilliant ascending arch of +light, broad and conical in form in the middle. When any substance was +introduced into this arch, it instantly became ignited; platina melted +in it as readily as wax in a common candle; quartz, the sapphire, +magnesia, lime, all entered into fusion; fragments of diamond and +points of charcoal and plumbago seemed to evaporate in it, even when +the connection was made in the receiver of an air-pump; but there was +no evidence of their having previously undergone fusion. When the +communication between the points positively and negatively electrified +was made in the air rarefied in the receiver of the air-pump, the +distance at which the discharge took place increased as the exhaustion +was made; and when the atmosphere in the vessel supported only +one-fourth of an inch of mercury in the barometrical gauge, the sparks +passed through a space of nearly half an inch; and, by withdrawing the +points from each other, the discharge was made through six or seven +inches, producing a most brilliant coruscation of purple light; the +charcoal became intensely ignited, and some platina wire attached to +it fused with brilliant scintillations and fell in large globules upon +the plate of the pump. All the phenomena of chemical decomposition were +produced with intense rapidity by this combination." + +It will be seen from this that as far as the actual lighting-part of +Davy's apparatus was concerned, it was completely successful. But the +source of the current--the most essential part of the apparatus--was +such that even the wealthy could hardly afford to indulge in it as a +luxury. The initial cost of two thousand cells was only a small item of +expense compared with the cost of maintaining them in working order, +and paying skilled operators to care for them. So that for the moment +no practical results came from this demonstration, conclusive though +it was, and the introduction of a commercial electric light was of +necessity deferred until a cheaper method of generating electricity +should be discovered. + +This discovery was not made for another generation, but then, as +seems entirely fitting, it was made by Davy's successor and former +assistant at the Royal Institution, Sir Michael Faraday. His discovery +of electromagnetic induction in 1831 for the first time made possible +the electric dynamo, although still another generation passed before +this invention took practical form. In the meantime, however, the +magneto-electric machine of Nollet was used for generating an electric +current for illuminating purposes as early as 1863; and when finally +the dynamo-electric machine was produced by Gramme in 1870, engineers +and inventors had at their disposal everything necessary for producing +a practical electric illuminant. + +It must not be supposed, however, that inventors stood by patiently +with folded hands waiting for the coming of a machine that would +furnish them with an adequate current without attempting to produce +electric lamps. On the contrary, they were constantly wrestling with +the problem, in some instances being fairly successful, even before the +invention of the magneto-electric machine. Great advances had been made +in batteries and cell construction over the primitive cells of the time +of Davy, and for exhibition purposes, and even for lighting factories +and large buildings, fairly good electric lights had been used before +1863. + +The first practical application of electric lighting seems to have +been made in France in 1849. During the production of the opera "The +Prophet" the sun was to appear, and for this purpose an electric arc +light was used. The success of this effort--an artificial sun being +produced that seemed almost as dazzling to the astonished audience as +Old Sol himself--stimulated further efforts in the same direction. The +previous year W. E. Staite in England made experiments along similar +lines in the large hall of the hotel of Sunderland. He generated a +light "resembling the sun, or the light of day, and making candles +appear as obscure as they do by daylight," according to the _Times_ of +the following morning. The electric light was therefore proved to be a +practical illuminator, although it was not until the introduction of +the Gramme dynamo-electric machine that its great economic utility was +demonstrated. + + +THE JABLOCHKOFF CANDLE + +In Sir Humphry Davy's experiments with his arc light he was led to +believe that the light between the two points of carbon would be +produced even in an absolute vacuum, if it were possible to create one. +Several scientists at the time disputed this contention, and M. Masson, +Professor of Physics in the _Ecole Centrale des Arts et Manufactures_ +in Paris was particularly active in combatting the idea, maintaining +that the arc had the same cause as the electric spark--the transport +by electricity of the incandescent particles of the electrodes through +the atmosphere. It was certain, at any rate, that no light was produced +when the opposing carbons were brought into contact with each other, +or were, on the other hand, separated too widely; and since there +was a constant wearing away and shortening of the points, and thus +a constantly increasing space between them, the great difficulty in +making a practical lamp lay in regulating this distance automatically. +It was finally accomplished, however, by the invention of a Russian +officer, M. Jablochkoff, in 1876. The "Jablochkoff candle," as his +lamp was called, marked an epoch in the history of electric lighting. +One great merit of this invention was its simplicity, and while it +has long since gone out of use, having been superseded by still +simpler and better devices, it must always be recalled as an important +stepping-stone in the progress of artificial illumination. + +The name "candle" for Jablochkoff's lamp was suggested by the fact +that the two carbons were placed side by side, instead of point to +point, the light at the top thus suggesting a candle. Between these +two carbons, and extending their whole length except at the very tips, +was an insulating material that the arc could not pierce, but which +burned away at a rate commensurate with the shortening of the carbons. +In this manner the points were kept constantly at the proper distance +without regulating-machinery of any kind. This ingenious apparatus +had the additional advantage that it could be placed on any kind of a +bracket or chandelier that was properly wired, thus dispensing with the +cumbersome frames and machines of the point-to-point carbon arc lights +then being introduced. + +One difficulty at first encountered in using the Jablochkoff candle was +the starting of the voltaic arc. In doing this it was necessary that +contact be made between two carbon points, whether they lie parallel or +point to point, and the necessary slight separation for producing the +light effected later. To accomplish this Jablochkoff joined the tips of +the carbons of his candle with a thin strip of carbon, which quickly +burned away when the current was turned on, leaving the necessary space +between the points for the arc. + +There was one difficulty with the "candle" that seemed insurmountable +for a time--the wasting of the two carbons was unequal, as in any arc +light, the points thus gradually drawing apart until the passage of the +current was no longer possible. To overcome this the rapidly wasting +positive carbon was made double the thickness of its mate; but while +this answered fairly well the thinner negative carbon gradually became +heated by the increased resistance, and burned up too rapidly. The +difficulty was finally overcome by the simple expedient of alternating +the flow of the current, so that each carbon was alternately a +positive and a negative pole. As the magneto-electric machines then in +use produced alternating currents it was only necessary to use such +machines for generating the current to produce an equal destruction of +both carbons. + +The simplicity and excellence of the light of these "candles" brought +them at once into general popularity, not only in the large cities of +Europe, but in many out-of-the-way places. Greece, Portugal, and other +obscure European countries adopted them, and even Brazil, La Plata, +and Mexico installed many plants. But stranger still, they were soon +used for illuminating the palaces of the Shah of Persia and the King +of Cambodia, and a little later were introduced into the residence of +the savage King of Burma. In short, their use became universal almost +immediately. + + +THE IMPROVED ARC LIGHT + +About the time that Jablochkoff's candles were making such a sensation +in Europe, Charles F. Brush, of Cleveland, Ohio, invented an arc light +in which the carbons were set point to point, the distance being +maintained and the necessary feed produced automatically in much the +same manner as in the lamps used at present. Other inventions soon +followed, some of the lamps being regulated by clockwork, some by +electricity and magnetism. + +The advantage of this type of arc lamp over the candle type--an +advantage that led to its general adoption--was largely that of +efficiency, a far greater amount of light being obtainable from the +same expenditure of power by the point-to-point type of lamp. + +In this lamp it is necessary that the points of carbon shall come in +contact when the current is off, but be drawn apart a moment after the +current is turned on, and remain at this fixed distance. To accomplish +this, the lower carbon is usually made stationary, the feeding being +regulated by the position of the upper carbon. In the usual type of +modern lamp the passage of the current causes the points to separate +the required distance through the action of an electromagnet the coils +of which are traversed by the current. A clutch holds the carbon in +place, the position of this being also determined by an electromagnet. +The action is regulated by the difference in the resistance to the +passage of the current caused by the increase in the separation of the +points. + +In the older type of arc lamp it was necessary to "trim" the lights by +replacing the carbons every day; but recently lamps have been perfected +in which the carbons last from one hundred to one hundred and twenty +hours. In these the arc is enclosed in a glass globe which is made as +nearly air-tight as possible with the necessary feed devices. This +closed chamber is fitted with a valve opening outward, which allows +the air to be forced out by the heat of the lamp, but does not admit a +return current. In this manner a rarefied chamber is produced in which +the carbons are oxidized very slowly; yet there is no diminution in the +brilliancy of the light. + +Early in the history of electric lighting it became apparent that the +proper construction of the carbon electrodes was a highly important +item in the manufacture of a lighting apparatus. The value of carbons +depends largely upon their purity and freedom from ash in burning, and +it required a countless number of experiments to develop the highly +efficient carbons now in general use. Davy made use of pieces of wood +charcoal in his experiments, but these were too fragile to be of +practical value, even if their other qualities had been ideal. Later +experimenters tried various compounds, and in 1876 Carre in France +produced excellent carbons made of coke, lampblack, and syrup. From +these were developed the present carbons, usually made by mixing some +finely divided form of carbon, such as soot or lampblack made from +burning paraffin or tar, with gum or syrup to form a paste. Rods of +proper size and shape are made by forcing this paste through dies by +hydraulic pressure, subsequently baking them at a high temperature. +Sometimes they are given a coating of copper, a thin layer of the metal +being deposited upon them by electrolysis. + + +EDISON AND THE INCANDESCENT LAMP + +The familiar incandescent electric-light bulb seems such a simple +apparatus to-day, being nothing apparently but a small wire enclosed in +an ordinary glass bulb, that it is almost impossible to realize what +an enormous amount of money, energy, and that particular quality of +mentality which we call "genius" has been required to produce it. First +and foremost among the names of the men of genius who finally evolved +this lamp is that of Thomas A. Edison; and only second to this foremost +name are those of Swan, Lane-Fox, and Hiram Maxim. But Edison's name +must stand preeminent; and there are probably very few, even among +Europeans, who would attempt or wish to deny him the enviable place as +the actual perfecter of the incandescent-light bulb. + +[Illustration: THOMAS A. EDISON AND THE DYNAMO THAT GENERATED THE FIRST +COMMERCIAL ELECTRIC LIGHT.] + +It is said that Edison first conceived the idea of an incandescent +electric light while on a trip to the Rocky Mountains in company +with Draper, in 1878. Be this as it may, he certainly set to work +immediately after completing this journey, and never relaxed or ceased +his efforts until a practical incandescent lamp had been produced. His +idea was to perfect a lamp that would do everything that gas could do, +and more; a lamp that would give a clear, steady light, without odor, +or excessive heat such as was given by the arc lights--in short, a +household lamp. + +Early in his experiments he abandoned the voltaic arc, deciding that +a successful lamp must be one in which incandescence is produced by a +strong current in a conductor, the heat caused by the resistance to +the current producing the glow and light. But when search was made for +a suitable substance possessing the necessary properties to be the +incandescent material, the inventor was confronted by a vast array of +difficulties. It was of course essential that the substance must remain +incandescent without burning, and at the same time offer a resistance +to the passage of the current precisely such as would bring about +the heating that produced incandescence. It should be infusible even +under this high degree of heat, or otherwise it would soon disappear; +and it must not be readily oxidizable, or it would be destroyed as +by ordinary combustion. It should also be of material reducible to +a filament as fine as hair, but capable of preserving a rigid form. +These, among others, were the qualities to be considered in selecting +this apparently simple filament for the incandescent lamp. It was not a +task for the tyro, therefore, that Edison undertook when he began his +experiments for producing an "ideal lamp." + +The substance in nature that seemed to possess most of the necessary +qualities just enumerated was the metal platinum, and Edison began +at once experimenting with this. He made a small spiral of very fine +platinum wire, which he enclosed in a glass globe about the size of an +ordinary baseball. The two ends of the wires connected with outside +conducting wires, which were sealed into the base of the bulb. The air +in the bulb had to be exhausted and a vacuum maintained to diminish the +loss of heat and of electricity and to prevent the oxidation of the +platinum. But when the current was passed through the spiral wire in +this vacuum a peculiar change took place in the platinum itself. The +gases retained in the pores of the metal at once escaped, and the wire +took on such peculiar physical properties that it was supposed for a +time by some physicists that a new metal had been produced. The metal +acquired a very high degree of elasticity and became susceptible of a +high polish like silver, at the same time becoming almost as hard as +steel. It also acquired a greater calorific capacity so that it could +be made much more luminous without fusing. To diminish the loss of +heat the wire was coated with some metallic oxide, and the slope of +the spiral also aided in this as each turn of the spiral radiated heat +upon its neighbor, thus utilizing a certain amount that would otherwise +have been lost. But despite all this, Edison found, after tedious +experimenting, that platinum did not fulfil the requirements of a +practical filament for his lamp; it either melted or disintegrated in a +short time and became useless; and the other experimenters had met with +the same obstacles to its use, and were forced to the same conclusion. + +Some other substance must be found. The use of carbon for arc lights +and Edison's own experiments with carbon in his work on the telephone +naturally suggested this substance as a possibility. It is said that +this idea was brought forcibly to the inventor's attention by noticing +the delicate spiral of vegetable carbon left in his hand after using +a twisted bit of paper, one day, for lighting a cigar. This spiral of +carbon was, of course, too fragile to be of use in its ordinary form. +But it occurred to Edison that if a means of consolidating it could +be found, there was reason to hope that it would answer the purpose. +Experiments were begun at once, therefore, not only with processes of +consolidation but also with various kinds of paper, and neither effort +nor expense was spared to test every known variety of paper. Moreover, +many new varieties of paper were manufactured at great expense from +substances having peculiar fibres. One of these, made from a delicate +cotton grown on some little islands off South Carolina, gave a carbon +free from ash, and seemed to promise good results; but later it was +found that the current of electricity did not circulate through this +substance with sufficient regularity to get protracted and uniform +effects. Nevertheless, since many things pointed to this fibre carbon +as the ideal substance, Edison set about determining the cause of the +irregularity in the circulation of the current in the filament, and a +number of other experimenters soon became interested in the problem. + +It was soon determined that the arrangement of the fibres themselves +were directly responsible for the difficulty. In ordinary paper the +fibres are pressed together without any special arrangement, like wool +fibres in felting. In passing through such a substance, therefore, the +current cannot travel along a continuous fibre, but must jump from +fibre to fibre, "like a man crossing a brook on stepping-stones." Each +piece of fibre constitutes a lamp or miniature voltaic arc, so that the +current is no longer a continuous one; and the little interior sparks +thus generated quickly destroy the filament. This discovery made it +apparent that such an artificial, feltlike substance as paper could not +be made to answer the purpose, and Edison set about searching for some +natural substance having fibres sufficiently long to give the necessary +homogeneity for the passage of the current. + +For this purpose specimens of all the woods and fibre-substances of +all countries were examined. Special agents were sent to India, China, +Japan, South America, in quest of peculiar fibrous substances. The +various woods thus secured were despatched to the Edison plant at Menlo +Park and there carefully examined and tested. Without dwelling on the +endless details of this tedious task, it may be said at once that only +three substances out of all the mass withstood the tests reasonably +well. Of these, a species of Japanese bamboo was found to answer the +purpose best. Thus the practical incandescent lamp, which had cost so +much time, ingenuity, and money, came into existence, fulfilling the +expectation of the most sanguine dream of its inventor. + +In using these bamboo carbon filaments the original spiral form of +filament was abandoned, the now familiar elongated horseshoe being +adopted, as the carbon could not be bent into the tortuous shapes +possible with platinum. Later various modifications in the shape of the +filament were made, usually as adaptations to changes in the shape of +the bulbs. + +At the same time that Edison was succeeding with his bamboo carbon +filaments, J. W. Swan had been almost as successful with a filament +formed by treating cotton thread with sulphuric acid, thus producing a +"parchmentized thread," which was afterwards carbonized. A modification +of this process eventually supplanted the Edison bamboo filament; and +the filament now in common use--the successor of the "parchmentized +thread"--is made of a form of soluble cellulose prepared by dissolving +purified cotton wool in a solution of zinc chloride, and then pressing +the material out into long threads by pressing it through a die. + +The long thread so obtained is a semi-transparent substance, resembling +catgut, which when carbonized at a high temperature forms a very +elastic form of carbon filament. To prepare the filament the cellulose +threads are cut into the proper lengths, bent into horseshoe shape, +double loops, or any desired form, and then folded round carbon formers +and immersed in plumbago crucibles. On heating these crucibles to a +high temperature the organic matter of the filaments is destroyed, +the carbon filaments remaining. These filaments are then ready for +attachment to the platinum leading-in wires, which is accomplished +either by means of a carbon cement or by a carbon-depositing process. +They are then placed in the glass bulbs and the wires hermetically +sealed, after which the bulbs are exhausted, tested, fitted with the +familiar brass collars, and are ready for use. + +The combined discoveries of all experimenters had made it evident +that certain conditions were necessary to success, regardless of +the structure of the carbon filament. It was essential that the +vessel containing the filament should be entirely of glass; that the +current should be conveyed in and out this by means of platinum wires +hermetically sealed through the glass; and that the glass globe must +be as thoroughly exhausted as possible. This last requirement proved +a difficult one for a time, but by improved methods it finally became +possible to produce almost a perfect vacuum in the bulbs, with a +corresponding increase in the efficiency of the lamps. + + +THE TUNGSTEN LAMP + +For twenty years the carbon-filament lamp stood without a rival. +But meanwhile the science of chemistry was making rapid strides and +putting at the disposal of practical inventors many substances hitherto +unknown, or not available in commercial quantities. Among these were +three metals, osmium, tantalum, and tungsten, and these metals soon +menaced the apparently secure position of the highly satisfactory, +although expensive, Edison lamp. + +It will be recalled that the early experimenters had used two metals, +platinum and iridium, for lamp filaments; and that these two, although +unsatisfactory, were the only ones that had given even a promise +of success. But in 1898 Dr. Auer von Welsbach took out patents, and +in 1903 produced a lamp using an osmium filament. Its advent marked +the beginning of the return to metal-filament lamps, although the +lamp itself did not prove to be very satisfactory and was quickly +displaced by a lamp invented by Messrs. Siemens and Halske, having +a tantalum filament. On account of its ease to manufacture, its +brilliant light, and relatively low consumption of power, this lamp +gained great popularity at once, and for a single year was practically +without a rival. Then, in 1904, patents were taken out by Just and +Hanaman, Kuzel, and Welsbach, for lamps using filaments of tungsten, +and the superiority of these lamps over the tantalum lamps gave +them an immediate popularity never attained by either of the other +metal-filament lamps. + +Needless to say there is good ground for this popularity, which may be +explained by the simple statement that the tungsten lamp gives more +light with much less consumption of power per candle power than any of +its predecessors. Unlike the carbon filament, which projects in the +familiar elongated horse-shoe loop, or double loop, into the exhausted +bulb, the tungsten filament is wound on a frame, so that several +filaments (usually eight or more) are used for producing the light +in each bulb. The chief defect of this lamp is the fragility of the +filament, which breaks easily when subjected to mechanical vibration. +On the other hand, tungsten lamps can be used in places at a long +distance from the central generating plant, where the electric current +is too weak for carbon-filament lamps. + + +THE MERCURY-VAPOR LIGHT OF PETER COOPER HEWITT + +"On an evening in January, 1902, a great crowd was attracted to the +entrance of the Engineers' Club in New York city. Over the doorway +a narrow glass tube gleamed with a strange blue-green light of such +intensity that print was easily readable across the street, and yet +so softly radiant that one could look directly at it without the +sensation of blinding discomfort which accompanies nearly all brilliant +artificial lights. The hall within, where Mr. Hewitt was making the +first public announcement of his great discovery, was also illuminated +by the wonderful new tubes. The light was different from anything ever +seen before, grateful to the eyes, much like daylight, only giving the +face a curious, pale-green, unearthly appearance. The cause of this +phenomenon was soon evident; the tubes were seen to give forth all the +rays except red,--orange, yellow, green, blue, violet,--so that under +its illumination the room and the street without, the faces of the +spectators, the clothing of the women, lost all their shades of red; +indeed, changing the face of the world to a pale green-blue. + +"The extraordinary appearance of this lamp and its profound +significance as a scientific discovery at once awakened a wide +public interest, especially among electricians who best understood +its importance. Here was an entirely new sort of electric light. +The familiar incandescent lamp, though the best of all methods of +illumination, is also the most expensive. Mr. Hewitt's lamp, though +not yet adapted to all the purposes served by the Edison lamp, on +account of its peculiar color, produces eight times as much light with +the same amount of power. It is also practically indestructible, there +being no filament to burn out; and it requires no special wiring. By +means of this invention electricity, instead of being the most costly +means of illumination becomes the cheapest--cheaper even than kerosene. +No further explanation than this is necessary to show the enormous +importance of this invention." + +As just stated, the defect of the Edison incandescent lamp is its +cost, due to its utilizing only a small fraction of the power used +in producing the incandescence, and, of much less importance, the +relatively short life of the filament itself. Only about three per +cent. of the actual power is utilized by the light, the remaining +ninety-seven per cent. being absolutely wasted; and it was this +enormous waste of energy that first attracted the attention of Mr. +Hewitt, and led him to direct his energies to finding a substitute that +would be more economical. A large part of the waste in the Edison bulb +is known to be due to the conversion of the energy into useless heat, +instead of light, as shown by the heated glass. Mr. Hewitt attempted to +produce a light that would use up the power in light alone--to produce +a cool light, in short. + +Instead of directing his efforts to the solids, Mr. Hewitt turned his +attention to gaseous bodies, believing that an incandescent gas would +prove the more nearly ideal substance for a cool light. The field of +the passage of electricity through gases was by no means a virgin +one, but was nevertheless relatively unexplored: and Mr. Hewitt was, +therefore, for the most part obliged to depend upon his own researches +and experiments. In these experiments hundreds of gases were examined, +some of them giving encouraging results, but most of them presenting +insurmountable difficulties. Finally mercury vapor was tried, with the +result that the light just referred to was produced. + +The possibilities of mercury-vapor gas had long been vaguely +suspected--suspected, in fact, since the early days of electrical +investigation, two centuries before. The English philosopher, Francis +Hauksbee, as early as 1705 had shown that light could be produced by +passing air through mercury in an exhausted receiver. He had discovered +that when a blast of air was driven up against the sides of the glass +receiver, it appeared "all round like a body of fire, consisting of an +abundance of glowing globules," and continuing until the receiver was +about half full of air. Hauksbee called this his "mercurial fountain," +and although he was unable to account for the production of this +peculiar light, which he remarked "resembled lightning," he attributed +it to the action of electricity. + +Between Hauksbee's "mercurial fountain" and Hewitt's mercury-vapor +light, however, there is a wide gap, and, as it happened, this gap +is practically unbridged by intermediate experiments, for Mr. Hewitt +had never chanced to hear anything of Hauksbee's early experiments, +or of any of the tentative ones of later scientists. But this, on the +whole, may have been rather advantageous than otherwise, as, being +ignorant, he was perhaps in a more receptive state of mind than if +hampered by false or prejudicial conceptions. Be this as it may, he +began experimenting with mercury confined in a glass tube from which +the air had been exhausted, the mercury being vaporized either by +heating, or by a current of electricity. No results of any importance +came of his numerous experiments for a time, but at last he made the +all-important discovery that once the high resistance of the cold +mercury was overcome, a comparatively weak current would then be +conducted, producing a brilliant light from the glow of the mercury +vapor. Here, then, was the secret of the use of mercury vapor for +lighting--a powerful current of electricity for a fraction of a second +passed through the vapor to overcome the initial resistance, and then +the passage of an ordinary current to produce the light. + +In practice this apparent difficulty in overcoming the initial +resistance with a strong current is easily overcome by the use of a +"boosting coil," which supplies the strong current for an instant, and +is then shut off automatically, the ordinary current continuing for +producing the light. The mechanism is hardly more complex than that of +the ordinary incandescent light, but the current of ordinary strength +produces an illumination about eight times as intense as the ordinary +incandescent bulb of equal candle-power. + +The form of lamp used is that of a long, horizontal tube suspended +overhead in the room, a brilliant light being diffused, which, lacking +the red rays of ordinary lights, gives a bluish-green tone to objects, +and a particularly ghastly and unpleasant appearance to faces and +hands, as referred to a moment ago. In many ways this feature of the +light is really a peculiarity rather than a defect, and for practical +purposes in work requiring continued eye-strain the absence of the +red rays is frequently advantageous. In such close work as that of +pen-drawing, for example, some artists find it advantageous to use +globes filled with water tinted a faint green color, placed between +the lamps and their paper, the effect produced being somewhat the same +as that of the mercury-vapor light. For such work the absence of the +red rays of the Hewitt light would not be considered a defect; and in +workshops and offices where Mr. Hewitt's lamps are used the workmen +have become enthusiastic over them. + +On the other hand, the fact that the color-values of objects are so +completely changed makes this light objectionable for ordinary use; +so much so, in fact, that the inventor was led to take up the problem +of introducing red rays in some manner so as to produce a pure white +light. He has partly accomplished this by means of pink cloth colored +with rhodium thrown around the glass; but this causes a distinct loss +of brilliancy. + +The most natural method of introducing the red rays, it would seem, +would be to use globes of red glass; but a moment's reflection will +show that this would not solve the difficulty. Red glass does not +change light waves, but simply suppresses all but the red rays; and +since there are no red rays in the mercury-vapor light the result of +the red globe would be to suppress all the light. Obviously, therefore, +this apparently simple method does not solve the difficulty; but those +familiar with Mr. Hewitt's work will not be surprised any day to hear +that he has finally overcome all obstacles, and produced a perfectly +white light. In the meantime the relatively expensive arc light and +the incandescent bulb with its filament of carbon or metal hold +unchallenged supremacy in the commercial field. + + + + +XII + +THE MINERAL DEPTHS + + +Ages before the dawn of civilization, primitive man had learned to +extract certain ores and metals from the earth by subterranean mining. +Such nations as the Egyptians, for example, understood mining in most +of its phases, and worked their mines in practically the same manner as +all succeeding nations before the time of the introduction of the steam +engine. The early Britons were good miners and the products of their +mines were carried to the Orient by the Phoenicians many centuries +before the Christian era. The Romans were, of course, great miners, and +remains of the Roman mines are still in existence, particularly good +examples being found in Spain. + +Even the aborigines of North America possessed some knowledge of +mining, as attested by the ancient copper mines in the Lake Superior +region, although by the time of the discovery of America, and probably +many centuries before, the interloping races of Indians who had driven +out or exterminated the Lake Superior copper mines had forgotten the +art of mining, if indeed they had ever learned it. But the fact that +their predecessors had worked the copper mines is shown by the number +of stone mining implements found in the ancient excavations about Lake +Superior, these implements being found literally by cart loads in some +places. + +The great progress in mining methods, however, as in the case of most +other mechanical arts, began with the introduction of steam as a means +of utilizing energy; and another revolution is in rapid progress owing +to the perfection of electrical apparatus for furnishing power, heat, +and light. Methods of mining a hundred years ago were undoubtedly +somewhat in advance of the methods used by the ancients; but the +gap was not a wide one, and the progress made by decades after the +introduction of steam has been infinitely greater than the progress +made by centuries previous to that time. + +This progress, of course, applies to all kinds of mines and all phases +of mining; but steam and electricity are not alone responsible for +the great nineteenth-century progress. Geology, an unknown science +a century ago, has played a most active and important part; and +chemistry, whose birth as a science dates from the opening years of the +nineteenth century, is responsible for many of the great advances. + +Obviously a very important feature of any mine must be its location, +and the determination of this must always constitute the principal +hazard in practical mining. Prospecting, or exploring for suitable +mining sites, has been an important occupation for many years, and +has in fact become a scientific one recently. Formerly mines were +frequently stumbled upon by accident, but such accidental discoveries +are becoming less and less frequent. The prospector now draws largely +upon the knowledge of the scientist to aid him in his search. Geology, +for example, assists him in determining the region in which his mines +may be found, if it cannot actually point out the location for sinking +his shaft; and at least a rough knowledge of botany and chemistry +is an invaluable aid to him. It is obvious that it would be useless +to prospect for coal in a region where no strata of rocks formed +during the Carboniferous or coal-forming age are to be found within a +workable distance below the surface of the earth. The prospector must, +therefore, direct his efforts within "geological confines" if he would +hope to be successful, and in this he is now greatly aided by the +geological surveys which have been made of almost every region in the +United States and Europe. + +An example of what science has done in this direction was shown a few +years ago in a western American town during one of the "oil booms" +that excited so many communities at that time. In the neighborhood +of this town evidences of oil had been found from time to time--some +of them under peculiar and suspicious circumstances, to be sure--and +the members of the community were in an intense state of excitement +over the possibility of oil being found on their lands. Prices of land +jumped to fabulous figures, and the few land-owners that could be +induced to part with their farms became opulent by the transactions. An +"oil expert" appeared upon the scene about this time--just "happening +to drop in"--who declared, after an examination, that the entire region +abounded in oil. He backed up his assertion by offering to stake his +experience against the capital of a company which was formed at his +suggestion. Before any wells were actually started, however, a prudent +member of the company consulted the State geologist on the subject, +receiving the assurance that no oil would be found in the neighborhood. +Strangely enough the word of the man of science triumphed over that of +the "oil expert," and although some tentative borings were made on a +minor scale, no great amount of money was sunk. It developed afterwards +that the evidences of oil found from time to time had been the secret +work of the "expert." + +In general, prospecting for oil differs pretty radically from +prospecting for most other minerals. A very common way of locating an +ore-mine is by the nature of the out-crop,--that is, the broken edges +of strata of rocks protruding from hillsides, or tilted at an angle on +level areas. If the ore-bearing vein is harder than the surrounding +strata it will be found as a jutting edge, protruding beyond the +surface of the other layers of rocks which, being softer, are more +easily worn away. On the other hand, if this stratum is soft or +decomposable it will show as a depression, or "sag" as it is called. Of +course such protrusions and depressions may only be seen and examined +where the rocks themselves are exposed; vegetation, drift, and snow +preventing such observations. But the vegetation may in itself serve +as a guide to the experienced prospector in determining the location +of a mine, peculiar mineral conditions being conducive to the growth +of certain forms of vegetation, or to the arrangement of such growth. +Alterations in the color of the rocks on a hillside are also important +guides, as such discolorations frequently indicate that oxidizable +minerals are located above. + +In hilly or mountainous regions, where the underlying rocks are covered +with earth, portions of these surfaces are sometimes uncovered by the +method known as "booming." In using this method the prospector selects +a convenient depression near the top of a hill and builds a temporary +dam across the point corresponding to the lowest outlet. When snow and +rain have turned the basin so formed into a lake, the dam is burst +and the water rushing down the hillside cuts away the overlying dirt, +exposing the rocks beneath. This method is effective and inexpensive. + +The beds of streams, particularly those in hilly and mountainous +regions, are fertile fields for prospecting, particularly for precious +metals. Stones and pebbles found in the bed are likely to reveal the +ore-foundations along the course of the stream, and the shape of +these pebbles helps in determining the approximate location of such +foundations. An ore-bearing pebble, well worn and rounded, has probably +traveled some little distance from its original source, being rounded +and worn in its passage down the stream. On the other hand, if it is +still angular it has come a much shorter distance, and the prospector +will be guided accordingly in his search for the ore-vein. + +But prospecting is not limited to these simple surface methods. In +enterprises undertaken on a large scale, borings are frequently made +in regions where there are perhaps no specific surface indications. +In such regions a shaft may be sunk or a tunnel may be dug, and the +condition of the underlying strata thus definitely determined. This +last is, of course, a most expensive method, the simpler and more usual +way being that of making borings to certain depths. The difficulty with +such borings is that rich veins may be passed by the borer without +detection; or, on the other hand, a small vein happening to lie in the +same plane as the drill may give a wrong impression as to the extent of +the vein. + +One of the most satisfactory ways of making borings is by means of the +diamond drill. This drill is made in the form of a long metal tube, +the lower edge of which is made into a cutting implement by black +diamonds fixed in the edge of the metal. By rotating this tube a ring +is cut through the layers of rock, the solid cylinder or core of rock +remaining in the hollow centre of the drill. This can be removed from +time to time, the nature and thickness of the geological formation +through which the drill is passing being thus definitely determined. + + +CONDITIONS TO BE CONSIDERED IN MINING + +Three great problems always confront the mine operator--light, power, +and ventilation. Of these ventilation is the most important from the +workman's standpoint, although the problem of light is scarcely +less so. Obviously a cavity of the earth where hundreds of men are +constantly consuming the atmosphere and vitiating it, and where +thousands of lights are burning, would become like the black hole of +Calcutta in a few minutes if some means were not adopted to relieve +this condition. But besides this vitiation of the atmosphere caused by +the respiration of the men and the burning of lamps there are likely +to be accumulations of poisonous gases in mines, that are even more +dangerous. Of the two classes of dangerous gases--those that asphyxiate +and those that explode or burn--it may be said in a general way that +the suffocating or poisonous gases, such as carbonic acid, which is +known as black damp, or choke damp, are more likely to occur in ore +mines, while the explosive gases are found more frequently in coal +mines. + +Choke damp, which is a gas considerably heavier than the atmosphere, +is usually found near the bottom of mines, running along declines and +falling into holes in much the same manner as a liquid. It kills by +suffocation, and, as it will not support combustion, it may be detected +by lowering a lighted candle into a suspected cavity, the light being +extinguished at once if the gas is present. To rid the cavity of it, +forced ventilation is used where possible, the gas being scattered by +draughts of fresh air. If this is impracticable, and the cavity small, +the choke damp may be dipped out with buckets. + +But the problem of the mining engineer is not so much to rid cavities +of gas as to prevent its accumulation. In modern mining, with proper +ventilation and drainage, there is comparatively little danger of +extensive accumulation of this gas. + +[Illustration: A FLINT-AND-STEEL OUTFIT, AND A MINER'S STEEL MILL. + +The upper picture shows a flint-and-steel outfit, the implements for +lighting a fire before the days of matches. The lower picture shows a +miner's steel mill, which was used for giving light in mines before the +day of the safety-lamp. It consists of a steel disk which is rotated +rapidly against a piece of flint, producing a stream of sparks. It was +thought that such sparks would not ignite fire-damp--a belief which is +now known to be erroneous.] + +The danger from this choke damp, therefore, is one that concerns the +individual workman rather than large bodies of men or the structure of +the mine itself. With fire damp, however, the case is different, as an +explosion of this gas may destroy the mine itself and all the workmen +in it. It is, therefore, the most dreaded factor in mining, and is the +one to which more attention has been directed than to almost any other +problem. + +This fire damp is a mixture of carbonic oxide and marsh gas which, +being lighter than air, tends to rise to the upper part of the mines. +For this reason explosions are more likely to occur near the openings +of the mine, frequently entombing the workmen in a remote part of the +mine even when not actually killing them by the explosion. As this gas +is poisonous as well as explosive the miners who survive the explosion +may succumb eventually to suffocation. + +Previous to the year 1816 no means had been devised for averting the +explosions of fire damp except the uncertain one of watching the flame +of the candle with which the miner was working. On coming in contact +with air mildly contaminated with fire damp the candle flame takes +on a blue tint and assumes a peculiarly elongated shape which may be +instantly detected by a watchful workman. But miners were, and still +are, a proverbially careless class of men even where a matter of life +and death is concerned, and too frequently gave no heed to the warning +flame. But in 1816 Sir Humphrey Davy invented his safety lamp, a +device that has been the means of saving thousands of lives, and which +has not as yet been entirely supplanted by any modern invention. + +In making his numerous experiments, Davy had observed that iron-wire +gauze is such a good conductor of heat that a flame enclosed in +such gauze could not pass readily through meshes to ignite a gas on +the outside. He found by experiment that a considerable quantity of +explosive gas might be brought into contact with the gauze surrounding +a flame, and no explosion occur. At the same time this gas would give +warning of its presence by changing the color of the flame. When a +lamp was made with a surrounding gauze having seven hundred and eighty +meshes to the square inch, it was found to give sufficient light and +at the same time to be practically non-explosive in the presence of +ordinary quantities of gas. + +One would suppose that such a life-saving invention would have been +eagerly adopted by the men whose lives it protected; but, as a matter +of fact, owing to certain inconveniences of Davy's lamps, many miners +refused to use them until forced to do so by the mine-owners. One +of these disadvantages was that this safety lamp gave a poor light +overhead. This is particularly annoying to the miner, who wishes always +to watch the condition of the ceiling under which he is working. When +not under constant observation, therefore, a miner would frequently +remove the gauze of the lamp and work by the open flame, regardless +of consequences. Or again, he would sometimes forgetfully use the +flame for lighting his pipe. To overcome the possibility of such +forgetfulness or wilful disobedience, it was found necessary to equip +safety lamps with locking devices, so that the miner had no means of +access to the open flame of his lamp once it had been lighted. + +Since the time of the first Davy safety lamp there have been numerous +improvements in mechanical details, although the general principle +remains unchanged. One of these improvements is a device whereby the +lamp, when accidentally extinguished, may be relighted without opening +it, and without the use of matches. This is done by means of little +strips of paper containing patches of a fulminating substance which +is ignited by friction, working on the same principle as the paper +percussion caps used on toy pistols. + +But even the improved safety lamp seems likely to disappear from mines +within the next few years, now that electricity has come into such +general use. As yet, however, no satisfactory portable electric lamp +or lantern has been perfected, such lamps being as a rule too heavy, +expensive, and unreliable. Even if these defects were remedied, the +advantage would still lie with the Davy lamp, since the electric lamp, +being enclosed, cannot be used for the detection of fire damp. But +this advantage of the safety lamp is becoming less important, since +well-regulated mines are now more thoroughly ventilated, and the danger +from fire damp correspondingly lessened. + +In some Continental mines the experiment has been tried of constantly +consuming the fire damp, before it has had time to accumulate in +explosive quantities, by means of numerous open lights kept constantly +burning. This method is effective, but since the numerous lights +consume the precious oxygen of the air as well as the damp, the method +has never become popular. Obviously, then, the question of mine +ventilation is closely associated with that of lighting. + +Probably the simplest method of properly ventilating a mine is that of +having two openings at the surface, one on a much higher level than +the other if the mine is on a hillside, the lower one corresponding to +the lowest portion of the mine where possible. By such an arrangement +natural currents will be established, and may be controlled and +distributed through the mine by doors or permanent partitions, or aided +by fans. But of course only a comparatively small number of mines are +so situated that this system can be used. + +It is possible, of course, to ventilate a mine from a single shaft or +opening by use of double sets of pipes, one for admitting air and the +other for expelling it; but this system is obviously not an ideal one, +and is prohibited by law in most mining districts. Such laws usually +stipulate that there must be at least two openings situated at some +distance from each other. + +The older method of creating air currents was by means of furnaces, +but this method, while very effective, is expensive and dangerous. In +using this system a furnace is built near the outlet of the air shaft, +the combustion of the fuel creating the necessary draught. But in the +nature of things this furnace is a constant menace to the mine, besides +being an extremely wasteful expenditure of energy. The modern method +of ventilating is by means of rotary fans, the electric fan having +practically solved the problem. The air currents established by such +fans are controlled either by the doors in the passages, or by means of +auxiliary fans. In addition, jets of compressed air are sometimes used, +and have become very popular. + +Another important problem that constantly confronts the mining engineer +is that of drainage. Mines are, of course, great reservoirs for the +accumulation of water, which must be drained or pumped out continually; +and as the shafts are sunk deeper and deeper it becomes increasingly +difficult to raise the water to the surface. Special means and +machinery are employed for this purpose which will be considered more +in detail in a moment. + + +ELECTRIC MACHINERY IN MINING + +Electricity is, of course, the great revolutionary factor in modern +mining. There is scarcely a department of mining in which electric +power has not wrought revolutionary changes in recent years; and the +subject has become so important and so thoroughly specialized as to +"create a literature and a technology of its own." From the electric +drill, working hundreds of feet below the surface of the earth, to the +delicate testing-instruments in the laboratory of the assaying offices, +the effect of this electrical revolution is being felt progressively +more and more every year. + +Moreover, electricity, on account of its transmutability, has made +accessible many important mining sites hitherto unworkable. Rich mines +are now in operation on an economical basis which, thirty years ago, +were worthless on account of their isolation. When such mines were +situated in mountainous regions where there was no coal supply at hand +for creating steam power, and where the only available water power was +perhaps several miles away, operations on a paying basis were out of +the question before the era of electric power. + +At present, however, the question of distance of the seat of power +has been practically eliminated by the possibilities of electric +conduction. A stream, situated miles away, when harnessed to a turbine +and electric motors may afford a source of power more economical than +could be furnished a few years ago by a power plant supplied with +fuel at the very door of the mine. We need not enter into the details +of this transmission of power, however, since the subject has been +discussed in a general way in another place. Our subject here is +rather to deal with the application of electricity to certain mining +implements of special importance. + +One of the most useful acquisitions to the equipment of the modern +miner is a portable mechanical drill, which makes it possible for +him to dispense with the time-honored pick, hammer, and hand-drill. +But it is only recently that inventors have been able to produce +this implement. The great difficulty has lain in the fact that a +reciprocating motion, which is essential for certain kinds of drilling, +is not readily secured with electric power. The use of steam or +compressed air for operating such reciprocating drills presents no +mechanical difficulties, and the fact that power of this kind can be +transmitted long distances by the use of flexible tubes made such +drills popular for several years. But the cost of operating such drills +is so much greater than that of the new electric drills that they are +rapidly being replaced in mining work. + +The first attempts to produce an electric drill with a reciprocating +motion were so unsuccessful that inventors turned their attention to +perfecting some rotary device. This proved more successful, and rotary +drills, operating long augers and acting like ordinary wood-boring +machines, are now used extensively for certain kinds of drilling. The +more recent forms perform the same amount of work as the air drill, +with a consumption of about one-tenth the power. Moreover, none of +the energy is lost at high altitudes as in the case of air drills, +and they are not affected by low temperatures which sometimes render +the air drill inoperable. On the other hand, the air drill is a hardy +implement, capable of withstanding very rough usage, whereas the +electric drill is probably the more economical, as well as the more +convenient drill of the two. + +In certain kinds of mining, such as in the potash mines of Europe and +the coal mines of America, these electric drills operating their long +augers have been found particularly useful. The ordinary type of drill +is so arranged that it can be operated at any angle, vertically or +horizontally. The lighter forms are mounted on upright stands, with +screws at the ends for fastening to the floor and roof, although the +heavier types are sometimes mounted on trucks. The motor, which is +not much larger or heavier than an ordinary fan motor, is fastened to +the upright and is from four to six horse-power. This connects with a +flexible wire which transmits the power from the generating station, +frequently several miles away. The auger, which is about the largest +part of the machine and entirely out of proportion to the little motor +that drives it, is simply a long bar of steel, twisted spirally at the +cutting-end like an ordinary wood auger. + +From the workman's standpoint these rotary drills are infinitely +superior to reciprocating or percussion drills, where the constant +jarring of the machine, besides being extremely tiresome, sometimes +produces the serious disease known as neuritis. Various means have +been attempted to prevent this, such as by overcoming the jar in a +measure by flexible levers which do not transmit the vibrations to the +hands and arms; but such attempts are only partially successful, and +a certain amount of jarring cannot be avoided. In the rotary electric +drills there is none of this, the workmen simply controlling the drill +and the motor with levers, and receiving at most only a slight jar from +the vibrations of the auger. + + +TRACTION IN MINING + +In recent years electric traction engines for use in mines have been +rapidly replacing horse-and mule-power, and have become important +economic factors in mining operations. The pioneer of this type of +locomotive seems to have been one built by Mr. W. M. Schlessinger +for one of the collieries of the Pennsylvania Railroad about 1882, +and which has remained in active use ever since. The total weight of +this locomotive was five tons and it was equipped with thirty-two +horse-power electric motors. The current was supplied through a trolley +pole which took the current from a T-shaped rail placed above and at +one side of the track. The train hauled by this locomotive consisted of +fifteen cars, carrying from two to three tons of coal each. + +Following this first mining-locomotive a great number were quickly +produced. In Pennsylvania alone something like four hundred are now +in use, and in Illinois two million tons of coal were hauled in this +manner in twelve mines in 1901. It was estimated at the beginning of +the present century that some 3,000 electric locomotives specially +built for mining were in use in the United States alone. + +The earlier types of mining-locomotives were much higher and bulkier +than those of more recent construction, the motors being mounted above +the trucks and geared downward. Very soon, however, the "turtle-back" +or "terrapin-back" type was developed, with the motors brought close +to the ground, so that even quite a heavy locomotive might not be +much higher than the diameter of its driving-wheels. When these +queer-looking machines were boxed in so that even the wheels were +covered, they lost all resemblance to locomotives or vehicles of any +kind, appearing like low, rectangular metal boxes placed upon the car +tracks, that glided along the rails in some mysterious manner. The +presence of the trolley pole helped to dispel this illusion, but in +some instances this is wanting, the power being taken from a third rail. + +With these locomotives, some of them not more than two and a half +feet high, it was possible to haul trains even in very low and narrow +passages--much lower, in fact, than could be entered by the little +mules used in former years. This in itself was revolutionary in its +effects, as many thin veins were thus made workable. + +This type of low locomotive is the one that has come into general use +throughout the world. Such locomotives range in size from two to twenty +tons, with wheel gauges from a foot and a half wide to the standard +railway gauge of four feet, eight and a half inches. Locomotives +weighing more than twenty tons are not in general use on account of the +small size of the mine entrances. + +In the ordinary types the motorman sits in front, controlling the +locomotive with levers and mechanical brakes placed within easy reach, +but sunk as low as possible. As a rule, the motors are geared to the +truck axles, either inside or outside the locomotive frame. An overhead +copper wire supplies the current by contact with a grooved trolley +wheel mounted on the end of the regulation trolley pole. An electric +headlight is used, and the ordinary speed attained by the compact +motors is from six to ten miles an hour. + +The amount of work that can be performed by one of these little, +flat, box-like locomotives is entirely out of proportion to its size. +A 10-ton locomotive in a Pennsylvania mine hauled about 150,000 +tons of coal in a year at a cost of less than one-tenth of a cent per +ton for repairs. The usual train was made up of thirty-five cars, +each loaded with about 3,700 pounds of coal, which was hauled up a +three-per-cent grade. The cost of such haulage was only about 2.76 +cents per ton, as against 7.15 cents when hauled by mule-power. These +figures may be considered representative, as other mines show similar +results. + +[Illustration: THE LOCOMOTIVE "PUFFING BILLY" AND A MODERN COLLIERY +TROLLEY. + +This locomotive was constructed in 1813 at Wylam Colliery, England, +by William Hedley. It was entirely successful, and was in operation +for almost half a century, up to the time of its removal in 1862 to +the South Kensington Museum. The vertical cylinders and arrangement of +walking beams for transmitting power are particularly interesting. The +power was transmitted through cogged wheels to the rear axle, as is +done with modern automobiles.] + +A particular advantage has been gained by the use of electric +locomotives over older methods in the process of "gathering" the cars. +In many coal mines, even when the main hauling is done by electricity, +the gathering or collecting of cars from the working faces of the rooms +was formerly done either by mule-power or by hand. In some low-veined +mines, hand power alone was used, on account of the low roof. + +In such places, low, compressed-air locomotives were sometimes used; +but these were very expensive. These have now been very generally +replaced by "turtle-back" electric locomotives, operated at a distance +from the main trolley wire by means of long, flexible cables, so geared +that they can be paid out or coiled as desired. + +On the main line these locomotives take the current from the trolley +wire by means of the trolley pole, but when the place for gathering is +reached, the connection is made by means of the flexible cable, and the +trolley pole fastened down so as not to be in the way. This allows the +locomotive to push the little cars into the rooms far removed from the +main line, with passages too low and narrow to allow the use of the +trolley pole. By the time the last cars have been delivered the first +cars of the train have been filled, and the process of gathering may be +begun at once, and the loaded train made up for the return trip. With +such a locomotive two men can distribute and gather up from one hundred +to one hundred and twenty cars in an ordinary eight-hour working-day, +hauling from three hundred to three hundred and fifty tons of coal. + +In certain regions, a system of third-rail current-supply is used, this +rail being also a tooth rail with which a cog on the locomotive works +frictionally. For climbing steep grades this system of cogged rails has +many advantages over other systems. + +Another type of electric locomotive used in some mines is a +self-propelling or automobile one equipped with storage batteries. Such +locomotives do away with the inconvenience and dangers of contact rails +or trolley wires, but are heavy and expensive. A compromise locomotive, +particularly useful for gathering, is one equipped with both trolley +pole and storage batteries. This locomotive is so made that the storage +batteries are charged while it is running with the trolley connection, +so that no time is lost in the charging process. Such locomotives +have been found very satisfactory for many purposes, and but for the +imperfections common to all storage batteries would be ideal in many +ways. They can be worked over any improvised track, regardless of +distance, which is an advantage over the flexible-cable system where +distances are limited by the length of cable; and the first cost of +the battery is no more than the outlay on trolley wires and supports. +It is also claimed that the cost of maintenance is relatively low, but +it is doubtful if it equals the trolley or third-rail systems in this +respect. + +Closely allied to the systems of traction by electric locomotives, is +the modern electric telpherage system. Until quite recently the haulage +of ores and other raw materials used in mining, when done aerially, +has been by means of travelling rope or cable. When distances to be +travelled in this manner are short, such as across streams or valleys, +where no supports are used, the term "cableway" is generally applied; +but where the distance is so long that supports are necessary, the term +"tramway cable" is used. It is to these longer systems that electric +telpherage is particularly applicable. + +The advantage of such an electric system over the older method is +the same as the advantages of the trolley road over the cable, all +ropes and cables being stationary, the electric motor, or "telpher," +travelling along on one cable and taking its current by means of a +trolley pole from a wire above. For heavier work metal rails supported +between posts are employed in place of a flexible cable, and over such +systems loads of several tons can be hauled. + +Such an electric telpher system is used in one of the Cuban limestone +quarries, the telpher and cars travelling a long distance upon cables, +except at some of the curves, where solid rails are substituted, +hauling a load of a thousand pounds at a speed of from twelve to +fifteen miles an hour. The current comes from a distant source, and the +telpher is so arranged that it travels automatically when the current +is turned on, stopping when the current is cut off. This is quite a +common arrangement for smaller telphers, but in the larger ones a man +travels with the telpher and load, controlling the train just as in the +case of the ordinary trolley system. + +The various processes of hoisting in mines by electricity is closely +akin to that of traction, since, after all, "an elevator is virtually a +railway with a 100-per-cent grade." As such work is done spasmodically, +long periods of rest intervening between actual periods of work, a +great deal of energy is wasted by steam hoisting engines, where a +certain pressure of steam in the boiler must be maintained at all +times. For this reason electrical energy for hoisting has come rapidly +into popularity in recent years. "The throttling of steam to control +speed," said Mr. F. O. Blackwell in addressing the American Institute +of Mining Engineers, "the necessity for reversing the engine, the +variation in steam pressure, the absence of condensing apparatus, the +cooling and large clearance of cylinders, and the condensation and +leakage of steam pipes when doing no work, are all against the steam +hoisting engine. One of the largest hoisting engines in the world was +recently tested and found to take sixty pounds of steam per indicated +horse-power per hour. The electric motor, on the other hand, is ideal +for intermittent work. It wastes absolutely no energy when at rest, +there being no leakage or condensation. Its efficiency is high, from +one-quarter load to twice full load." + +There seems to be practically no difference as far as the element of +danger is concerned between steam and electric hoists. The difference +is largely one of economy. The importance of this is shown by the +recent comparisons in a gold mine which has replaced its steam +apparatus by electricity. In this mine the hoist moves through the +shaft at a rate of over twelve hundred feet per minute, elevating five +hundred tons of ore daily on double-decked cages. It is estimated that +this system shows an efficiency of 75 per cent, taking into account +losses of all kinds, with a resulting reduction of cost of from seven +to twenty dollars per horse-power per month. + +Results comparing very favorably with these have been obtained also +in some of the mines in Germany and Bohemia, where electricity has +been introduced extensively in mining. In one of these mines the daily +hoisting capacity is twenty-seven hundred tons from a depth of over +sixteen hundred feet, at a speed of over fifty-two feet per second. In +the Comstock mine, at Virginia City, Nev., electric hoists are used +which obtain their power from a plant situated on the Truchee River +thirty-two miles away. + + +ELECTRIC MINING PUMPS + +In pumping, which is always one of the important items in mining, the +use of electric power has been found quite as advantageous as in the +other fields of its application. No special features are embodied in +most of the types of mining pumps over the rotary and reciprocating +types used for ordinary purposes, except perhaps a type of pump known +as the sinking pump. This is a movable pump that can be easily lowered +from one place to another, and has proved to be a great time-saver over +steam or air pumps used for similar purposes. + +For some time the question of the durability of electric pumps was in +dispute, but developments in quite recent years seem to prove that, in +some instances at least, such pumps are practically indestructible. + +"The question of what would happen to an electric motor in a mine +if pumps and motors get flooded has often come up. From tests made +recently at the University of Liege, Belgium, it appears that a +suitably designed polyphase alternating-current motor of a type largely +used on the continent of Europe was completely submerged in water. +It was run for a quarter of an hour; it was then stopped and allowed +to remain submerged, under official seal, for twenty-four hours, at +the end of which time it was again run for a few minutes. It was next +removed from the water, again put under seal, and left to dry for +twenty-four hours. The insulation was then tested, and the motor was +found to be in perfect order. It would be hard to imagine a test more +severe than this. + +"As bearing upon this question it is interesting to note that among +the pumps in use around Johannesburg, South Africa, at the beginning +of the Anglo-Boer War, there were twelve of a well-known American +make, each of which was operated by a 50-horse-power induction motor +of American construction with three 15-kilowatt transformers. When the +mines were shut down, upon the breaking out of the war, the water +rose so rapidly that it was impossible to remove the pumps, motors, +transformers, etc., and consequently they remained under 500 to 1,000 +feet of water. Two and a half years later, when peace was declared in +South Africa, the water in the shaft was pumped out and the electrical +apparatus was removed to the surface. Three of the motors were stripped +and completely rewound, but to the general surprise of the experts the +condition of the insulation indicated that the rewinding might not be +absolutely necessary. Accordingly the other nine motors were thoroughly +dried in an oven and then soaked in oil. After this treatment they were +rigidly tested, proved to be all right, and were at once restored to +regular service in the mine. The transformers were treated in the same +manner as the motors, with equally gratifying results. + +"An interesting illustration of the flexibility and adaptability of +electric motors for pumping purposes is furnished by the Gneisenau +mine, near Dortmund, Germany, where a very large electric mining plant +was installed in 1903. In this instance the pump is located more than +1,200 feet below the surface, and the difficulties of installing the +apparatus were so great, on account of the small cross section of the +shaft, that it was necessary to build up the motor in the pumping +chamber, the material being transported through the wet shaft and the +winding of the coils being performed _in situ_. + +"An interesting use of the electric pump associated with the telephone +in connection with mining is noted by Mr. W. B. Clarke. In one coal +mine, where an electric pump is located in a worked-out portion of the +mine, the circuits are so arranged that the pump is started from the +power house, some distance away. Near the pump is placed a telephone +transmitter connected to a receiver in the power house. To start the +motors, or to ascertain whether the pumps are working properly, the +engineer merely listens at the telephone receiver, without leaving his +post." + + +ELECTRICITY IN COAL MINING + +In coal mining the effect of the use of electrical machinery has been +revolutionary in recent years, particularly in the development of +electric coal cutters. The old method of picking out coal by hand, +where the miner labored with the heavy pick, working in all manner of +cramped and dangerous positions, was supplanted a few years ago by +the "puncher" machine, worked by steam or compressed air. With these +machines the coal was picked out just as in the case of the hand +method, except that the energy was derived from some power other than +muscular. So that while these machines worked more rapidly than the +hand picks, they utilized the same general principle in applying their +energy. + +Within recent years, however, various coal-cutting machines have been +devised, with which the coal was actually cut, or sawed out, these +machines being peculiarly well adapted to using the electric current. +The most practical and popular form of machine is one in which the +sawing is done by an endless chain, the links of which are provided +with a cutting blade. These have been very generally replacing the +compressed-air or pick type of machine, and their popularity accounts +largely for the enormous increase in the use of coal-mining machinery +during the past decade. Thus in 1898 there were 2,622 coal-mining +machines in use in the United States. Four years later this number had +more than doubled, the increase being due largely to the adoption of +chain machines. + +Like electric locomotives, and for similar reasons, the coal-cutting +machines are low, broad, flat machines, from eighteen to twenty-eight +inches high. They rest upon a flat shoeboard that can be moved +easily along the face of the coal. An ordinary machine weighs in the +neighborhood of a ton, and requires two men to operate. The apparatus +is described briefly as follows: + +"On an outside frame, consisting of two steel channel bars and two +angle irons riveted to steel cross ties, rests a sliding frame +consisting of a heavy channel or centre rail, to which is bolted the +cutter head. The cutter head is made entirely of two milled steel +plates, which bolt together, forming the front guide for the cutter +chain. This chain, which is made of solid cast steel links connected +by drop forge straps, is carried around idlers or sprockets placed at +each end of the cutter head and along the chain guides at the side to +the rear of the machine, where it engages with and receives its power +from a third sprocket, under the motor. The electric motor, which is +of ironclad multipolar type, rests upon a steel carriage, which forms +the bearing for the main shaft.... A reversing switch is provided, so +that the truck can travel in either direction, and when the machine has +reached its stopping point, either forward or backward, it is checked +by an automatic cut-off. The return travel is made in about one-fourth +of the time required to make the cut." + +In veins of coal of a thickness from twenty-eight to thirty inches, +such a machine will cut about one hundred tons of coal in a day. The +cost of production with such machines has been estimated at about +sixty-three cents a ton, as against ninety cents as the cost of pick +mining in rooms,--a saving of about twenty-seven cents a ton. Since it +is estimated that for a cost of $10,000 an electrical equipment can +be installed capable of working four such machines besides affording +power for lighting, pumping, ventilation of the mine, etc., thus saving +something like $100 a day for the operator, the great popularity of +these machines is readily understood. + +After such a machine has been placed in position, a cut some four feet +wide, four or five inches high, and six feet deep can be made in five +minutes, with the expenditure of very little energy on the part of the +workmen. One of the largest cuttings ever recorded by one of these +machines is 1,700 square feet in nine and one-half hours, although this +may have been exceeded and not recorded. + +Among the several advantages claimed for the chain machine over the +older pick machines is the small amount of slack coal produced, and +the absence of the racking vibrations that exhaust the workmen, and, +like the air drills, sometimes cause serious diseases. On the other +hand the advocates of the pick machines point out that they can be +used in mines too narrow for the introduction of chain machines. They +show also that there is a constant element of danger from motor-driven +machines in mines where the quantity of gas present makes it necessary +to use safety lamps, on account of the sparking of the machines which +may produce explosions. Both these claims are valid, but apply only +to special cases, or to certain mines, and do not affect the general +popularity of the chain machines. + +There are several different types of chain cutting machines, such as +"long-wall machines," and "shearing machines," but these need not be +considered in detail here. The general principle upon which they work +is the same as the ordinary chain machine, the difference being in the +method of applying it for use in special situations. + + +ELECTRIC LIGHTING OF MINES + +For many obvious reasons the ideal light for mining purposes is one +in which the danger from the open flame is avoided, particularly in +well-ventilated mines, or mines under careful supervision, where the +danger from inflammable gases is slight. The incandescent electric +light, therefore, has become practically indispensable in modern +mining operations. For certain purposes and in certain locations where +an intense light is desirable and where there is no danger from +combustible gases, arc lights are used to a limited extent. But there +is constant danger from the open flame in using such lights, and also +from the connecting wires leading to them. Furthermore, such intense +light is not usually necessary in the narrow passages of the mine. + +To be sure, there is a certain element of danger even with incandescent +lights on account of the possibility of breakage of the globes, and of +short-circuiting where improper wiring has been done. To overcome as +much as possible the dangers from these sources, special precautions +are taken in wiring mines, and special bulbs are used. In general the +incandescent lamps as used in mining are made of stout round bulbs +of thick glass which are not likely to crack from the effects of +water dripping upon them while heated. As a further protection it is +customary to enclose the bulbs in wire cages. It is also customary to +use low-current lamps with a rather high voltage, although this must be +limited, as excessive voltage may in itself become a source of danger. + + + + +XIII + +THE AGE OF STEEL + + +The iron industry has of late years become more and more merged into +the steel industry, as steel has been gradually replacing the parent +metal in nearly every field of its former usefulness. Steel is so much +superior to iron for almost every purpose and the process of making +it has been so simplified by Bessemer's discovery that it may justly +be said that civilization has emerged from the Iron Age, and entered +the Age of Steel. While iron is mined more extensively now than at +any time in the history of the world, the ultimate object of most of +this mining is to produce material for manufacturing steel. We still +speak of boiler iron, railroad iron, iron ships, etc., but these names +are reminiscent, for in the construction of modern boilers and modern +ships, steel is used exclusively. In the past decade it is probable +that no railroad rails even for the smallest and cheapest of tracks +have been made of anything but steel. + +The last half of the nineteenth century has been one of triumph of +steel manufacture and production in America, and at the present time +the United States stands head and shoulders above any other nation in +this industry. In the middle of the century both Germany and England +were greater producers than America; but by the close of the century +the annual output in the United States was above fifteen million tons +as against England's ten and Germany's seven; and since 1900 this lead +has been greatly increased. The steel industry has become so great, in +fact, that it is "a sort of barometer of trade and national progress." + +The great advances in the quantity of steel produced have been made +possible by corresponding advances in methods of winning the iron ore +from the earth. Mining machinery has been revolutionized at least twice +during the last half century, first by improved machines driven by +steam, and again by electricity and compressed air. Ore is still mined +to a limited extent by men with picks and shovels, but these implements +now play so insignificant a part in the process that they cannot be +considered as important factors. Steam shovels, automatic loaders and +unloaders, dynamite and blasting powder, have taken the place of brawn +and muscle, which is now mostly expended in directing and guiding +mining machinery rather than in actually handling the ore. + + +THE LAKE SUPERIOR MINES + +At the present time the greatest iron-ore fields lie in the Lake +Superior region, and it is in this region that the greatest progress +in mining methods has been made in recent years. There are, of course, +extensive mines in other sections of the United States, but at least +three-quarters of all the iron produced in America comes from the +Lake Superior mines, and the systems of mining pursued there may be +considered as representative of the most advanced modern methods. + +Where the iron ore of these mines is found near the surface of the +earth, the great system of "open-pit" mining is practised; but as only +a relatively small portion of the ore is so situated, modifications +of older mining methods are still employed. Of these the three most +important are known as "overhead scooping," "caving," and "milling." + +In the overhead method a shaft is sunk into the earth to a depth of +several hundred feet, according to the depth of the ore, this shaft +being lined with timbers for support. From this shaft horizontal +tunnels are made in all directions in the ore deposits, and through +these tunnels the ore is conveyed to the shaft and thence to the +surface. As the ore is removed and the earth thus honeycombed in +all directions, supports of various kinds must be made to prevent +caving. For this purpose columns of the ore itself may be left, or +supports of masonry or wood or steel may be introduced. Under certain +circumstances, however, these supports are not employed, the earth +being allowed gradually to cave in at the surface as the ore is +removed, this being the method of mining known as "caving." + +Where the ore deposit occurs in a favorable hillside the "milling" +system is frequently employed. In working this system a large +horizontal tunnel, twenty or more feet in diameter, is dug into the +hillside. Perpendicular shafts are then sunk from the top of the hill, +connected with openings leading directly into the top of the main +horizontal shaft. By this arrangement the ore, when loosened in these +perpendicular shafts, falls directly into the bins placed for its +reception about the openings, or into the rows of cars in waiting to +receive it. In this method dynamite and powder take the place of hand +labor, the main mass of ore being dislodged and thrown into the shaft +by blasting, instead of by hand labor. + +But all these methods are overshadowed in magnitude by the great "open +pit" systems, where the ore is taken from the surface and handled +entirely by machinery, the only part played by the miner's pick being +that of assisting in loosing certain fragments so that they may be +more easily seized by the machines. Indeed, this system of mining +partakes of the nature of quarrying rather than that of mining in the +ordinary sense, the ore being scooped from the surface of the ground. +One naturally thinks of a mine as being subterranean; but in the great +open-pit mines in the Lake Superior region, which are the largest mines +in the world, all the mining is done at the surface of the earth. + +It should not be understood, however, that in such mines nature has +left the red iron ore exposed at the surface in any great quantities. +On the contrary, it is usually covered by a layer of earth ranging from +a yard to ten or more yards in depth, and this, of course, must be +removed before open-pit methods can be practised. Prospecting for such +deposits is therefore just as necessary as in cases where the deposit +is situated much deeper in the earth; and the business of prospecting +by "test pit" men is as important an industry as ever. + +When an available open-pit mine of sufficient extent has been located +the gigantic task of "stripping" or removing the overlying layer of +earth begins. Immense areas of land have been thus stripped in some of +these undertakings, no difficulties being considered insurmountable. +If a small river-bed lies in an unfavorable position, the course of +the river is changed regardless of expense. Farms and farm houses +are purchased and literally carted away, neither land nor houses +representing values worth considering when compared with the stratum +of ore beneath them. The single contract for stripping one area in the +Lake Superior region was let for a sum amounting to half a million +dollars. + +As soon as a sufficiently large area has been stripped, railroads are +constructed into the pit, steam shovels are run into place, and the +actual work of mining begins. Five shovels full make a car-load, and +under ordinary circumstances the five loads may be delivered in as many +minutes. + +The number of men required to manipulate one of these steam shovels is +from ten to twelve. The ore itself is frequently so hard that the scoop +of the shovel could not penetrate it until loosened and broken up, and +it is the business of the gang of workmen to do this and slide the ore +down within easy working distance of the shovel. This is mostly done +by blasting with dynamite and powder, little of the actual labor being +performed by hand. In blasting, a deep hole is first drilled into +the ore near the top of the embankment, and into this hole a stick of +dynamite is dropped and exploded. This enlarges the cavity sufficiently +so that a quantity of blasting powder may be poured in and set off, +tumbling the ore down within reach of the shovel. + +This ore is frequently almost as hard as iron itself, many of the +pieces thus dislodged being too large for convenient handling, either +by the steam shovel or in the chutes at the wharves, and must be still +further broken up. This is sometimes done by the men with picks; but +in mining on a large scale, where the deposit is all of a very hard +nature, crushing machines are used. + +In this manner the steam shovel is kept constantly supplied with ore +for the waiting train of cars. These trains are arranged on a track +running parallel with the track from which the steam shovel operates, +and at such a distance that the centre of the car will be directly +under the opening in the bottom of the shovel when it is swung around +on its crane. The engineer in charge of the locomotive drawing the +train stops it in a position so that the first shovelful of ore will +be dumped into the forward end of the first car. As each successive +shovelful is deposited, representing about one-fifth of a car-load, +the train is pulled or backed along the track about one-fifth of a +car-length. In this manner it is only necessary for the steam shovel to +be swung into the same position and dumped at the same point each time +to insure the proper loading of the cars. + +From what has been said it will be seen that in this open-pit mining +the steam engine and steam locomotive still play a conspicuous part; +but in the other forms of iron mining, electric or compressed-air +motors are used, as much better adapted for underground work. In +the Lake Superior region, where everything is done by the most +modern methods, the use of horses and mules for hauling purposes is +practically unknown. + +The cars used for hauling the ore are of peculiar construction. The +latest types are built of steel with a carrying capacity of fifty tons +of ore, and are so made that by simply knocking loose a few pins their +bottoms open and discharge the ore into the receiving bins on the +wharves, or into the chutes leading to the waiting boats. + +A perennial problem in iron mining, whether surface or subterranean, +just as in all other kinds of mining, is the removal of accumulations +of water, some of these mines filling at the rate of from twenty-five +to thirty thousand gallons an hour. But an equally important problem +is that of removing moisture from the ore itself. Obviously every +additional pound of moisture adds to the cost and difficulty in +handling, and inasmuch as this ore must be transported a distance of +something like a thousand miles, necessitating three or four handlings +in the process, the aggregate amount of wasted energy caused by each +ton of water is enormous. It has been found that at least ten per +cent of the moisture may be dried out of the ore before shipping, and +that the ore does not tend to absorb moisture again under ordinary +circumstances once it has been dried. This is of course of great +advantage where it is found necessary to store it in heaps some little +time before shipping. + + +FROM MINE TO FURNACE + +In most industries, particularly where the percentage of waste products +is large, it is found advantageous and economical to establish +factories as near the source of supply of raw material as possible. But +the iron ore mined in the Lake Superior region is transported something +like a thousand miles before being delivered to the factories. The +question naturally arises, Why is not the ore turned into pig iron or +steel ingots at once as near the mouths of the mines as possible, and +sent in this condensed form to the factories, thus saving more than +half the cost of transportation? The answer is simple: the coal mines +and steel factories lie in the East, one established by nature, the +other by man many years before iron ore was found in the Lake region. +And it is found just as cheap and easy to transport the iron to the +coal regions as it would be to transport the coal to the ore regions. +Furthermore, the factories in the neighborhood of Pittsburg and along +the southern shores of Lake Erie and Lake Ontario are near the great +centres of civilization, and are accessible the year round; while the +Lake Superior region is "frozen in" for at least three months in the +year. + +And so, in place of a great traffic of coal westward to the Lake +Superior regions, there is a great eastward traffic of ore, by rail and +water, passing from the mines to furnaces and factories a thousand +miles away. Indeed, this is probably the greatest and most remarkable +system of transportation in the world. Specially constructed trains, +wharves, boats, and machinery, used for this single purpose, and not +duplicated either in design or extent, make this stupendous enterprise +a unique, as well as a purely American one. + +The transportation begins with the train loads of ore that run from +the mines to the lake shore and out upon the wharves built to receive +them. These wharves are enormous structures, sometimes half a mile in +length, built up to about the height of the masts of ore boats. On the +sides and in the centres of these towering structures are huge bins for +holding the ore, these bins communicating directly with the holds of +the ore steamers tied up alongside. Four tracks are frequently laid on +the top of the wharves, and are so arranged that trains four abreast +can dump the ore into the bins, or waiting ships, at the same time. +If the bins are empty and boats waiting to receive a cargo, the ore +is discharged by long chutes into the holds from the cars. Otherwise +the bins are filled, the trains returning to the mines as quickly as +possible for fresh loads. + +The boats for receiving this cargo are of special design, many of +them differing very greatly in appearance from ordinary ocean liners +of corresponding size. This is particularly true of the "whale-backs" +which have little in common in appearance with ordinary steamers except +in the matter of funnels; and even these are misplaced sternwards to +a distance quite out of drawing with the length of the hull. Their +shape is that of the ordinary type of submarine boat--that is, +cigar-shaped--this effect being obtained by a curved deck completely +covering the place ordinarily occupied by a flat deck. A wheel-house, +like a battle-ship's conning-tower, is placed well forward, supported +on steel beams some distance above the curved deck for observation +purposes; and engines, boilers, and coal bunkers occupy a small space +in the stern. The boat, therefore, is mostly hold. + +But the "whale-backs" form only a small portion of the ore-fleet. The +ordinary type of boat conforms more nearly to the shape of ocean boats, +except that the bridge, wheel-house, and engines are located as in the +whale-backs. The bows of these boats are blunt, the desideratum in +such craft being hull-capacity rather than speed. For sea-worthiness +they are equal to any ocean boats, as the battering waves of Lake +Superior are quite as powerful and even more treacherous than those +of the Atlantic or Pacific. Some of these boats are five hundred feet +long, equal to all but the largest ocean vessels. Their coal-carrying +capacity is relatively small, since coaling stations are numerous at +various points on the journey, and every available inch of space is +utilized for the precious iron ore. + +In order to facilitate loading, the decks are literally honey-combed +with hatches, some boats having fifteen or sixteen openings extending +the width of the deck. By this arrangement the time of loading is +reduced to a matter of a few hours, as a dozen chutes, each discharging +several tons of ore per minute, soon fill the yawning compartments +with the necessary six, eight, or nine thousand tons, that make up the +cargo. + +Quite recently lake-navigators have learned, what rivermen have long +known, that cheap transportation may be effected on a large scale by +barges and towing. Before the outbreak of the Civil War forty years +ago, the Mississippi river swarmed with great cargo-carrying steamers, +employing armies of men and consuming enormous quantities of fuel. +But after the war the experiment was tried of hauling the cargoes on +barges towed by tug boats, and this proved to be so much cheaper that +the fleet of great river boats soon disappeared. In somewhat the same +way the barge has come into use of late years in the ore-traffic, and +the great ore-steamers now tow behind them one or two barges equal in +carrying capacity to themselves. In this way three ships' cargoes of +ore are transported a thousand miles by a score of men, a dozen on the +steamer and three or four on each of the barges. The barges themselves +are rigged as ships, and if necessary can shift for themselves by means +of sails attached to their stubby masts. But these are used only on +special and unusual occasions, as in case of accidental parting of the +hawsers during a storm. + +The problem of loading the ships at the ore wharves is a simple one as +compared with the equally important one of transferring the ore from +the hold to trains of cars in waiting at the eastern end of the water +route. For four handlings of the ore are necessary before it is finally +deposited in the furnaces in the east. The first of these is from the +mine to cars; the second from the cars to the boats; the third from the +boats to cars; and the fourth from the cars to the blast furnaces. + +For many years about the only hand work done in any of these processes +was that of transferring from the boats to the ore-trains, and even +here "automatic unloaders" are now rapidly supplanting the tedious hand +method. By the older methods a travelling crane, or swinging derrick, +dropped a bucket into the hold of the ore-vessel, where workmen +shovelled it full of the red ore. It was then lifted out by machinery +and the contents dumped into cars in much the same manner as that of +the steam shovel in the mines. Recently, however, a machine has been +perfected which scoops up the ore from the ship's hold and transfers +it to the cars without the aid of shovellers. The only human aid given +this gigantic machine is to guide it by means of controlling levers--to +furnish brains for it, in short--the "muscle" being furnished by steam +power. The great arm of this automatic unloader, resembling the sweep +of the old-fashioned well in principle, moves up and down, burying +the jaws of the shovel into the ore in the hold, and pulling them out +again filled with ore, with monotonous regularity, quickly emptying the +vessel under the guidance of half a dozen men, and performing the labor +of hundreds. + +Thus the last field of activity for the laborer and his shovel, in the +iron-ore industry, has been usurped by mechanical devices. From the +time the ore is taken from the mine until it appears as molten metal +from the furnaces, it is not touched except by mechanisms driven by +steam, compressed air, or electricity. And yet, so rapid is the growth +of the iron and steel industry that there is almost always a demand for +more workmen. + +For this reason, and perhaps because of the "American spirit" among +workmen, innovations in the way of labor-saving machinery are not +resisted among the mine laborers. The American workman seldom resists +or attacks machinery on the ground that it "throws him out of a job," +as does his English cousin. It would be unjust to attribute this +attitude to superior acumen on the part of the American workman, and it +is probably a difference in conditions and surroundings that accounts +for the diametrically opposite views held by laborers on the two sides +of the Atlantic. But after all, results must speak for themselves, and +the advantage all lies in favor of the progressive attitude of the +western laborer, if we may judge by the relative social status and +financial standing of European and American workmen. + + +THE CONVERSION OF IRON ORE INTO IRON AND STEEL + +Since steel is a compound substance composed essentially of two +elementary substances in varying proportions, it appears that the +name "steel," like wood, refers to a class of which there are several +varieties. This, of course, is the case, but for the moment we may +consider steel as a single substance composed chiefly of iron and +containing a certain percentage of carbon. In this respect it +resembles cast iron, steel having a smaller amount of carbon. Wrought +iron, on the other hand, contains no carbon at all, or at least only a +trace of it. But whatever the ultimate destiny of iron ore--whether it +is to become aristocratic manganese steel, or plebeian cast iron--it +must first pass through certain processes before being "converted." + +To extract the pure iron from the iron ore it is necessary to heat +the ore in a furnace containing a certain quantity of coal, coke, or +charcoal, and limestone. The furnaces used in this process are known +as blast-furnaces, and in these about one ton of iron is extracted for +every two tons of Lake Superior ore, one and a quarter tons of coke, +and half a ton of limestone used. These quantities are by no means +constant, of course, but they may be taken as representing roughly the +relative amounts of material that must be fed into the furnaces. + +Like everything else in the world of iron and steel, these +blast-furnaces have undergone revolutionary improvements during the +past quarter of a century. From being most dangerous and destructive +structures causing frightful loss of life and producing only about one +ton of iron a day for every man working about them, as formerly, they +have now become relatively harmless monsters, capable of turning out +six times that quantity of ore for each man employed. + +The older blast-furnace was a huge, chimney-like structure, perhaps a +hundred feet high, into which the ore, coal, and limestone were poured. +Most of the work about these furnaces was done by manual labor, or +at least manual labor was an active assistant to the machinery used +in manipulating the furnaces. The top of the furnace was closed in by +a great movable lid, or "bell," and the material for charging it was +hauled up the sides by elevators and dumped in at the top. About the +top of the furnace was constructed a staging upon which the workmen +stood, an elevator shaft connecting the staging with the ground. The +ore and other materials were brought to the foot of the shaft on cars +from which it was shovelled into peculiarly designed wheelbarrows, +trundled to the elevator, and hauled to the top. + +In order to dump the wheelbarrow loads into the furnaces it was +necessary to raise the bell. This was always dangerous, and frequently +resulted in the suffocation or injury of the workmen on the staging. +For when the bell was raised there was an escape of poisonous gases, +which might flare out in a sheet of flame, with the possibility of +burning or suffocating the workmen. The fumes from these gases, if +inhaled in small quantities, might simply cause coughing, hiccoughing, +or dizziness; but when inhaled in large quantities they struck down +a man like the fumes of chloroform, suffocating him in a few seconds +if he was not removed at once into a purer atmosphere. Indeed, the +likelihood of this was so great that at many of these furnaces a +special workman was detailed to take the position on the staging, well +out of range of the gas, his sole duty being to rescue any of the men +who might be overcome, and hurry them as quickly as possible down the +elevator shaft into the pure atmosphere below. It was not an uncommon +thing in the neighborhood of these older furnaces to see stretched +about on the ground at the base several workmen in various stages of +suffocation. Fortunately, by use of precautionary measures, fatal +accidents were rather unusual, the men being overcome only temporarily, +and usually recovering quickly and returning to work. + +But the poisonous gas coming from the top of the furnace was not the +only, nor the worst, danger constantly menacing the men on the staging. +Their greatest dread was the possibility of explosions occurring in the +furnace, which might hurl the bell into the air and deluge the upper +structure with molten metal. Against this possibility there was no +safeguard in the older furnaces, explosions occurring without warning +and frequently with terrible effects. But fortunately these older types +of furnaces are being rapidly replaced by the newer forms in which the +danger to life, at least from gas and explosions, is minimized. And +even in the older furnaces, improvements in the structure of the bell +and in methods of filling have greatly lessened the dangers. + +In the modern type of blast-furnace the work at the top formerly +performed by men on the staging is accomplished entirely by machinery. +The general appearance of these furnaces is that of huge iron pipes or +kettles mounted on several iron legs. The outer structure, or shaft, +is constructed of plate iron, but this is lined with fire brick of +considerable thickness, and may have a water jacket interposed between +these bricks and the shaft. About this large kettle are smaller +kettles of somewhat similar shape having pipes leading from their tops +to the larger structure. These smaller kettles are the "stoves" used in +producing the hot air for the furnace. + +The working capacity of some of these furnaces is in the neighborhood +of a thousand tons of iron a day, although the average furnace produces +only about half that quantity. The powerful machinery used for charging +these monster caldrons hauls the ore and other charging materials to +the top and dumps it in car-load lots. + +In the older methods of manufacturing steel, the contents of the +blast-furnaces were first drawn off into molds and allowed to cool +into what is known as pig-iron. It was then necessary to re-heat +this iron and treat it by the various methods for producing the kind +of steel desired. By the newer methods, however, time and money are +saved by converting the liquid iron from the blast-furnace directly +into steel without going through the transitional stage of cooling it +into pigs. Pigs of iron are still made in enormous quantities, to be +sure, but mostly for shipment to distant places or for stores as stock +material. For statistical purposes, however, the entire product of the +blast-furnace, whether liquid or solid, is known as "pig iron." + +The older method of removing the iron from the blast furnaces was by +tapping at the opening near the bottom, the stream of liquid iron being +allowed to flow into a connected series of sand molds, each mold being +about three feet long by three or four inches wide. The bottom of +these molds was flat but as the metal cooled in them the upper surface +became round in shape, assuming a fanciful resemblance to a pig's back. +In this molding a great amount of time was wasted in the slow process +of cooling, and a large expenditure of energy wasted in this handling +and re-handling of the metal. + +In modern smelting works, however, pigs are no longer cast in sand +molds, the molten metal from the furnace being discharged directly into +iron molds attached to an endless chain. These molds are long, narrow, +and shallow, having the general shape of sand molds. Each mold as it +passes beneath the opening in the furnace remains just long enough to +receive the requisite amount of metal to fill it, and then moves on to +a point where it is either sprayed with water, or cooled by actually +passing through a tank of water, emerging from this bath with the metal +sufficiently solidified so that it may be dropped into a waiting car at +the turning point of the endless chain. In this manner the charge from +the blast-furnace may be drawn, cooled, and converted into pigs, loaded +into cars, and hauled away without extra handlings or loss of time, the +whole process occupying practically no more time than the initial step +of tapping by the older method. + +Where the contents of the blast-furnace are to be converted into +steel at once, the molten metal is run off into movable tanks which +carry it directly to the steel furnaces. These tanks, holding perhaps +twenty tons of metal, are made of thick iron lined with fire brick, +and arranged on low, flat cars designed specially for the purpose. +These tanks are run under the spout of the furnace, filled with molten +metal, and drawn to the steel works, possibly five miles away. As a +rule, the distance is much less, but as far as the condition of the +metal is concerned distance seems to make little difference, as even +at the extreme distance there is no apparent cooling of the seething +mass. The intense heat given off by these trains necessitates specially +constructed cars, tracks, bridges, and crossings. + +The destination of this train load of iron pots is the "mixer"--a great +200-ton kettle in which the products from the various furnaces are +mixed and rendered uniform in quality. On the arrival of the train at +the mixer, Titanic machinery seizes the twenty-ton pots and dumps their +contents bodily into the glowing pool in the great crucible. Like the +filling process, this operation occupies only a few minutes. + +From the mixer the metal is poured out into ladles and transferred +immediately to the "converter"--the important development of Sir Henry +Bessemer's discovery that has made possible the modern steel industry. +This converter resembles in shape some of the old mortars used in the +American Civil War--barrel-shaped structures suspended vertically by +trunnions at the middle and having an opening at the top. Into this +opening at the top the metal from the mixer is poured and when the +converter has been sufficiently charged a blast of cooled air is blown +in at the bottom through the molten metal. This blast emerges at the +top as a long roaring flame, of a red color at first but gradually +changing into white, and then faint blue. These changes in color are +indicative of the changes that are taking place in the metal, and the +appearance of a certain shade of color indicates that the conversion +into steel is complete, and that it is time for shutting off the blast +of air. Any mistake in this matter--even the variation of thirty +seconds' time--means a loss of thousands of dollars in the quality of +steel produced. The man whose duty it is to determine this important +point, therefore, holds an exceptionally delicate and responsible +position, and receives pay accordingly. + +In deciding the exact moment when the blast shall be turned off, this +workman is guided entirely by the sense of sight. Mounted on a platform +commanding the best possible view of the mouth of the converter and +wearing green glass goggles of special construction, this man watches +the change of color in the flame until a certain shade is reached--a +shade that to the ordinary untrained observer does not differ in +appearance from that of a moment before--when he gives the signal to +shut off the blast. When this signal is given the contents of the +converter is no longer common-place cast iron, but steel, ready to be +molded into rails, boilers, or a thousand and one other useful things. + +The contents of the converter may now be drawn off as liquid steel into +molds of any desired shape and size, and when cooled will be ready for +shipment. But in the great steel factories the metal is not ordinarily +allowed to cool completely before being sent to the rolling mills, +being drawn off into molds placed along the surface of small, flat +cars. These molds are rectangular, ordinarily four or five feet high by +less than two feet in diameter. The metal is poured into openings in +the top of each mold, and allowed to cool, solidify, and to contract +enough to permit the outer casings of the molds to be pulled off by +machinery, leaving the glowing "ingots" of steel ready for molding by +machinery in the mills. + +The process just described is the one by which "Bessemer steel" is +made. There is another important process in use, the "open hearth" +method, which differs considerably from this; but before considering +this process something more should be said of the man whose discoveries +made possible the modern steel industry. + + +SIR HENRY BESSEMER + +In the history of the progress of science and invention some one great +name is usually pre-eminently associated with epoch-marking advances, +although there may be a cluster of important but minor associates. This +is true in the history of the modern steel industry, and the central +name here is that of Sir Henry Bessemer. + +Bessemer was born at Charlton, England, on Jan. 19, 1813. Always +of an inventive turn of mind, his attention was first directed to +improving the methods then in use for the manufacture of steel, while +experimenting with the manufacture of guns. After several years of +experimenting in his little iron works near London, he reached some +definite results which he announced to the British Association in 1856. +In this paper he described a process of converting cast iron into +steel by removing the excess of carbon in the molten metal by a blast +of air driven through it. This paper, in short, described the general +principles still employed in the Bessemer process of manufacturing +steel. And although the first simple process described by Bessemer has +been modified and supplemented in recent years, it was in this paper +that the process which placed steel upon the market as a comparatively +cheap, and infinitely superior, substitute for ordinary iron, was first +disclosed. + +This famous paper before the British Association aroused great interest +among the English ironmasters, and applications for licenses to use +the new process were made at once by several firms. But the success +attained by these firms was anything but satisfactory, although +Bessemer himself was soon able to manufacture an entirely satisfactory +product. The disappointed ironmasters, therefore, returned to the +earlier processes, the inventor himself being about the only practical +ironmaster who persisted in using it. + +Recognizing the defects in his process, Bessemer set about overcoming +them, and at the end of two years he had so succeeded in perfecting +his methods that his product, equal in every respect to that of the +older process, could be manufactured at a great saving of time and +money. But the ironmasters were now skeptical, and refused to be again +inveigled into applying for licenses. Bessemer, therefore, with the +aid of friends, erected extensive steel works of his own at Sheffield, +and began manufacturing steel in open competition with the other steel +operators. The price at which he was able to sell his product and +realize a profit was so much below the actual cost of manufacture by +the older process, that there was soon consternation in the ranks of +his rivals. For when it became known that the firm of Henry Bessemer & +Co. was selling steel at a price something like one hundred dollars a +ton less than the ordinary market price, there was but one thing left +for the ironmasters to do--surrender, and apply for licenses to be +allowed to use the new process. + +By this means, and through the profits of his own establishment, +Bessemer eventually amassed a well-earned fortune. Moreover, he was +honored in due course by a fellowship in the Royal Society, and +knighted by his government. + +One other name is usually associated with that of Bessemer in the +practical development of the inventor's original idea. That is the +name of Robert Mushet, and the "Bessemer-Mushet" process is still in +use. Mushet's improvement over Bessemer's original process was that +of adding a certain quantity of _spiegeleisen_, or iron containing +manganese, which, for some reason not well understood, simplifies the +process of steel making. Mushet, therefore, must be considered as the +discoverer of a useful, though not an absolutely essential, accessory +to the Bessemer process. + + +OPEN-HEARTH METHOD + +In the open-hearth method the metal from the blast-furnaces is not +sent to the converter, but is poured into oven-like structures built +of fire brick, and in these heated to a terrific temperature. This +heat has the same effect upon the metal as the blast of air in the +Bessemer converter, and this open-hearth process has become very +popular for manufacturing certain kinds of steel. While in the method +of application this process differs greatly from that of Bessemer, it +differs largely in the fact that the oxygen necessary to burn off the +carbonic oxide, silicon, etc., is made to play over the molten mass +instead of passing through it. + +It has been noted that the old type of blast-furnace gave off great +quantities of combustible gases which became waste products. Even gases +containing something like 20 or 25 per cent. of carbonic acid may be +highly inflammable, and thus an enormous quantity of valuable fuel +was constantly wasted. In some furnaces, to be sure, they were put to +practical use for heating the blast, but as the quantities given off +were greatly in excess of the amount necessary for this purpose, there +was a constant loss even with such furnaces. + +Quite recently it has been found that the gases can be used directly +in gas engines, developing three or four times as much energy in this +way as if they were used as fuel under ordinary steam boilers. These +engines are now used for operating the rolling-mill machinery, and the +machinery of shops adjoining the furnaces, which, however, must not be +situated at any very great distances from the furnaces. This accounts +partly for the grouping together of blast-furnaces, rolling mills, +and machine shops, the economical feature of this arrangement being +so great that segregated establishments find it next to impossible to +compete in the open market with such "communities" under the conditions +prevailing in the steel industry. + + +ALLOY STEELS + +The introduction of Krupp steel, or nickel, for armor plates, a few +years ago, called attention in a popular way to the fact that for +certain purposes pure steel--that is, iron plus a certain quantity of +carbon--was not as useful as an alloy of steel with some other metal. +An alloy was a great improvement over ordinary steel or iron plates +used in warfare; but in the more peaceful pursuits, as well as in +warfare, certain alloyed steels, such as chrome steel, tungsten steel, +and manganese steel play a very important part. + +Chrome steel, for example, in the form of projectiles, is the most +dreaded enemy of nickel-steel armor plates, because of the hardness +and elasticity of armor-piercing projectiles made of it. Such a +steel contains about two per cent. of chromium with about one or +two per cent. of carbon, which when suddenly cooled is extremely +hard and tough. This kind of steel and manganese steel are the best +guards against the burglar and safe-blower, as they resist even very +highly tempered and hardened drills. As this steel is relatively +cheap to manufacture, it is frequently used in the construction of +safes and burglar-proof gratings. For this purpose, however, it is +sometimes combined in alternate layers with soft wrought iron, the +steel resisting the point of the drill, while the iron furnishes the +necessary elasticity to resist the blows of the sledge. The bars used +in modern jails and prisons are often made in a similar manner of +alternate sheaths of iron and chrome steel. Against the time-honored +"hack-saw," the bugbear of prison officials for generations, such +bars an inch and a quarter in diameter offer an almost insurmountable +obstacle; and they are equally effective against a heavy sledge hammer. + +At least one case is recorded in which the use of these "composite" +bars resulted in a disastrous fire in a prison. A small blaze having +started in the basement of this prison, attempts to reach it with a +stream of water were defeated by the bars of the steel gratings at the +windows, which would not admit the nozzle of the hose. A corps of men +armed with hack-saws, crow-bars, and sledges attacked this grating, +which, if made of ordinary steel, could have been readily broken. But +against these composite bars they produced no appreciable effect. +Meanwhile the fire gained rapidly, threatening the building and its +eight hundred inmates, and was only checked after holes had been made +through fire-proof floors and ceilings for admitting the nozzle. + +Manganese steel is peculiar in becoming ductile by sudden cooling, and +brittle on cooling slowly--precisely the reverse of ordinary steel. It +contains about 1.50 per cent. of carbon, and about 12 per cent. of +manganese. If a small quantity of manganese, that is, 1 or 2 per cent., +is used the steel is very brittle, and becomes more so as greater +quantities of the manganese are used, up to about 5 per cent. From that +point, however, it becomes more ductile as the quantity of manganese +is increased, until at about 12 per cent. it reaches an ideal state. +When used for safes and money vaults this steel has one great advantage +over chrome steel--it is not affected by heat. By using a blow-pipe +and heating a limited area of steel, the burglar is able to "draw the +temper" of ordinary steel to a sufficient depth so that he can drill +a hole to admit a charge of dynamite; but manganese steel retains +its temper under the blow-pipe no matter how long it may be applied. +Against attacks of the sledge, however, it is probably inferior to +chrome steel. + +Like manganese steel, tungsten steel retains its temper even when +heated to high temperatures. For this reason it is used frequently in +making tools for metal-lathe work where thick slices of iron are to be +cut, as even at red heat such a tool continues to cut off metal chips +as readily as when kept at a lower temperature. This steel contains +from 6 to 10 per cent. of tungsten, a metallic element with which we +have previously made acquaintance in our studies of the incandescent +lamp. + + + + +XIV + +SOME RECENT TRIUMPHS OF APPLIED SCIENCE + + +Not long ago a little company of men met in a lecture hall of Columbia +University to discuss certain questions in applied science. It was +a small gathering, and its proceedings were so unspectacular as to +be esteemed worth only a few lines of newspaper space. The very +name--"Society of Electro-Chemistry"--seemed to mark it as having to do +with things that are caviar to the general. The name seems to smack of +fumes of the laboratory, far removed from the interests of the man in +the street. Yet Professor Chandler said in his address of welcome to +the members of the society, that though theirs was the very youngest +of scientific organizations, he could confidently predict for it a +future position outranking that of all its sister societies; and his +prediction was based on the belief that electro-chemistry is destined +to revolutionize vast and important departments of modern industry. A +majority of the heat-using methods of mechanics will owe their future +development to the new science. + +In a word, then, despite its repellent name, the society in question +has to do with affairs that are of the utmost importance to the man in +the street. Though its members may sometimes deal in occult formulas +and abstruse calculations, yet the final goal of their studies has to +do not with abstractions but with practicalities,--with the saving +of fuel, the smelting of metals, the manufacture of commodities. But +theory in the main must precede practice--the child creeps before it +walks. "The later developments of industrial chemistry," says Sir +William Ramsey, "owe their success entirely to the growth of chemical +theory; and it is obvious," he adds significantly, "that that nation +which possesses the most competent chemists, theoretical and practical, +is destined to succeed in the competition with other nations for +commercial supremacy and all its concomitant advantages." + +Fortunately this interdependence of science and industry is not a +mere matter of prophecy--for the future tense is never quite so +satisfying as the present. Vastly important changes have already +been accomplished; old industries have been revolutionized, and new +industries created. The commercial world of to-day owes vast debts to +the new science. Professor Chandler outlined the character of one or +two of these in the address just referred to. He cited in some detail, +for example, the difference between old methods and new in such an +industry as the manufacture of caustic soda. He painted a vivid word +picture of the distressing conditions under which soda was produced +in the old-time factories. Salt and sulphuric acid were combined to +produce sulphate of soda, which was mixed with lime and coal and heated +in a reverberatory furnace. Each phase of the process was laborious. +The workmen operating the furnaces sweltered all day long in an +almost unbearable atmosphere--stripped to the waist, dripping with +perspiration, sometimes overcome with heat. Their task was one of the +most trying to which a man could be subjected. + +But to-day, in such establishments as the soda manufactories at Niagara +Falls, all this is changed. A salt solution circulates continuously in +retorts where it can be acted upon by electricity supplied from dynamos +operated by the waters of the Niagara River. The workmen, comfortably +dressed and moving about in a normal temperature, have really nothing +to do but refill the retorts now and then and remove the finished +product. "It almost seems," Professor Chandler added with a smile, "as +if workmen ought to be glad to pay for the privilege of participating +in so pleasant an occupation. At all events it is, in all seriousness, +a pleasure for the visitor who knows nothing of old practices to +witness this triumph of a modern scientific method." + +Even more interesting, said Professor Chandler, are the processes +employed in the modern method of producing the metal aluminum by the +electrolytic process. The process is based on the discovery made +by Mr. Charles M. Hall while he was a student working in a college +laboratory, that the mineral cryolite will absorb alumina to the extent +of twenty-five per cent. of its bulk, as a sponge absorbs water. The +solution of this compound is then acted on by electricity, and the +aluminum is deposited as pure metal. A curiously interesting practical +detail of the process is based on the fact that pulverized coke remains +perfectly dry and rises to the surface when stirred into a crucible +containing the hot alumina solution: moreover, it rises to the surface +and remains there as a shield to protect the workmen against the heat +of the solution. It serves yet another purpose, as the powdered alumina +may be sifted upon it and left there to dry before being stirred into +the crucible. A most ingenious yet simple device tells the workman when +any particular crucible is in need of replenishing. A small, ordinary, +incandescent electric-light bulb is placed in circuit between the poles +that convey the electric current through the alumina solution. So long +as the crucible contains alumina, the bulb does not glow, because +twenty volts of electricity are required to make it incandescent, +whereas seven volts pass through the solution. But so soon as the +alumina becomes exhausted, resistance to the current rises in the +cryolite solution and, as it were, dams back the electric current +until it overflows into the wire at sufficient pressure to start the +signal lamp. Then it is necessary merely for a workman to stir into +the solution the dry alumina resting on the surface, along with the +coke that supports it. This, of course, reestablishes the electrolytic +process; the lamp goes out and the coke, unaffected by its bath, rises +to the surface to support a fresh supply of alumina. + +Such a process as this, contrasted with the usual methods of smelting +metals in fiercely heated furnaces, seems altogether wonderful. Here +a pure metal is extracted from the clayey earth of which it formed +a part, without being melted or subjected to any of the familiar +processes of the picturesque, but costly, laborious, and even +dangerous, blast-furnaces. There is no glare and roar of fires; there +are no showers of sparks; there is no gush of fiery streams of molten +metal. A silent and invisible electric current, generated by the fall +of distant waters, does the work more expeditiously, more efficiently, +and more cheaply than it could be done by any other method as yet +discovered. + +Fully to appreciate the importance of the method just outlined, we +must reflect that aluminum is a metal combining in some measure the +properties of silver, copper, and iron. It rivals copper as a conductor +of electricity; like silver it is white in color and little subject +to tarnishing; like iron it has great hardness and tensile strength. +True, it does not fully compete with the more familiar metals in their +respective fields; but it combines many valuable qualities in fair +degree; and it has an added property of extreme lightness that is all +its own. Add to this the fact that aluminum is extremely abundant +everywhere in nature--it is a constituent of nearly all soils and is +computed to form about the twelfth part of the entire crust of the +earth--whereas the other valuable metals are relatively rare, and it +will appear that aluminum must be destined to play an important part in +the mechanics of the future. There is every indication that the iron +beds will begin to give out at no immeasurably distant day; but the +supply of aluminum is absolutely inexhaustible. Until now there has +been no means known of extracting it cheaply from the clay of which +it forms so important a constituent. But at last electro-chemistry +has solved the problem; and aluminum is sure to take an important +place among the industrial metals, even should it fall short of +the preeminent position as "the metal of the future" that was once +prematurely predicted for it. + + +NITROGEN FROM THE AIR + +There is a curious suggestiveness about this finding of aluminum at our +very door, so to speak, some scores of centuries after the relatively +rare and inaccessible metals had been known and utilized by man. But +there is another yet more striking instance of an abundant element +which man needed, but knew not how to obtain until the science of our +own day solved the problem of making it available. This is the case of +the nitrogen of the air. As every one knows, this gas forms more than +three-fourths of the bulk of the atmosphere. But, unlike the other +chief constituent, oxygen, it is not directly available for the use of +plants and animals. Yet nitrogen is an absolutely essential constituent +of the tissues of every living organism, vegetable and animal. Any +living thing from which it is withheld must die of starvation, though +every other constituent of food be supplied without stint; and the fact +that the starving organism is bathed perpetually in an inexhaustible +sea of atmosphere chiefly composed of nitrogen would not abate by one +jot the certainty of its doom. + +To be made available as food for plants (and thus indirectly as food +for animals) nitrogen must be combined with some other element, to +form a soluble salt. But unfortunately the atoms of nitrogen are +very little prone to enter into such combinations; under all ordinary +conditions they prefer a celibate existence. In every thunder-storm, +however, a certain quantity of nitrogen is, through the agency +of lightning, made to combine with the hydrogen of dissociated +water-vapor, to form ammonia; and this ammonia, washed to the earth +dissolved in rain drops, will in due course combine with constituents +of the soil and become available as plant food. Once made captive +in this manner, the nitrogen atom may pass through many changes and +vicissitudes before it is again freed and returned to the atmosphere. +It may, for example, pass from the tissues of a plant to the tissues +of a herbivorous animal and thence to help make up the substance of a +carnivorous animal. As animal excreta or as residue of decaying flesh +it may return to the soil, to form the chief constituent of a guano +bed, or of a nitrate bed,--in which latter case it has combined with +lime or sodium to form a rocky stratum of the earth's crust that may +not be disturbed for untold ages. + +A moment's reflection on the conditions that govern vegetable and +animal life in a state of nature will make it clear that a soil once +supplied with soluble nitrates is likely to be replenished almost +perpetually through the decay of vegetation. But it is equally clear +that when the same soil is tilled by man, the balance of nature is +likely to be at once disturbed. Every pound of grain or of meat +shipped to a distant market removes a portion of nitrogen; and unless +the deficit is artificially supplied, the soil becomes presently +impoverished. + +But an artificial supply of nitrogen is not easily secured--though +something like twenty-five million tons of pure nitrogen are weighing +down impartially upon every square mile of the earth's surface. In the +midst of this tantalizing sea of plenty, the farmer has been obliged +to take his choice between seeing his land become yearly more and more +sterile and sending to far-off nitrate beds for material to take the +place of that removed by his successive crops. The most important of +the nitrate beds are situated in Chili, and have been in operation +since the year 1830. The draft upon these beds has increased enormously +in recent years, with the increasing needs of the world's population. +In the year 1870, for example, only 150,000 tons of nitrate were +shipped from the Chili beds; but in 1890 the annual output had grown +to 800,000 tons; and it now exceeds a million and a half. Conservative +estimates predict that at the present rate of increased output the +entire supply will be exhausted in less than twenty years. And for some +years back scientists and economists have been asking themselves, What +then? + +But now electro-chemistry has found an answer--even while the alarmists +were predicting dire disaster. Means have been found to extract the +nitrogen from the atmosphere, in a form available as plant food, and at +a cost that enables the new synthetic product to compete in the market +with the Chili nitrate. So all danger of a nitrogen famine is now at +an end,--and applied science has placed to its credit another triumph, +second to none, perhaps, among all its conquests. The author of this +truly remarkable feat is a Swedish scientist, Christian Birkeland +by name, Professor of Physics in the University of Christiania. His +experiments were begun only about the year 1903, and the practical +machinery for commercializing the results--in which enterprise +Professor Birkeland has had the co-operation of a practical engineer, +Mr. S. Eyde--is still in a sense in the experimental stage,--albeit +a large factory was put in successful operation in 1905 at Notodden, +Norway. + +Professor Birkeland has thus accomplished what many investigators in +various parts of the world have been striving after for years. The +significance of his accomplishment consists in the fact that he has +demonstrated the possibility of making nitrogen combine with oxygen in +large quantities and at a relatively low expense. The mere fact of the +combination, as a laboratory possibility, had been demonstrated in an +elder generation by Cavendish, and more recently by such workers as +Sir William Crookes, and Lord Rayleigh in England and Professors W. +Mutjmaan and H. Hofer in Germany. Moreover, the experiments of Messrs. +Bradley and Lovejoy, conducted on a commercial scale at Niagara Falls, +had seemed to give promise of a complete solution of the problem; +had, indeed, produced a nitrogen compound from the air in commercial +quantity, but not, unfortunately, at a cost that made competition +with the Chili nitrate possible. Equally unsuccessful in solving this +important part of the problem had been the experiments, conducted on a +large scale, of Professors Kowalski and Moscicki, at Freiburg. + +All these experimenters had adopted the same agent as the means of, so +to say, forcing the transformation--namely, electricity. The American +investigators employed a current of ten thousand volts; the German +workers carried the current to fifty thousand volts. The flame of the +electric arc thus produced ignited the nitrogen with which it came in +contact readily enough; but the difficulty was that it came in contact +with so little. Despite ingenious arrangements of multiple poles, the +burning-surface of the multiple arc remained so small in proportion to +the expenditure of energy that the cost of the operation far exceeded +the commercial value of the product. Such, at least, must be the +inference from the fact that the establishments in question did not +attain commercial success. + +The peculiarity of Professor Birkeland's method is based upon the +curious fact that when the electric arc is made to pass through a +magnetic field, its line of flame spreads out into a large disk--"like +a flaming sun." The sheet of flame thus produced represents no greater +expenditure of energy than the lightning flash of light that the same +current would produce outside the magnetic field; but it obviously +adds enormously to the arc-light surface that comes in contact with +the air, and hence in like proportion to the amount of nitrogen that +will be ignited. In point of fact, this burning of nitrogen takes +place so rapidly in laboratory experiments as to vitiate the air of +the room very quickly. In the commercial operation, with powerful +electro-magnets and a current of five thousand volts, operating, of +course, in closed chambers, the ratio between energy expended and +result achieved is highly satisfactory from a business standpoint, +and will doubtless become still more so as the apparatus is further +perfected. + +To the casual reader, unaccustomed to chemical methods, there may seem +a puzzle in the explanation just outlined. He may be disposed to say, +"You speak of the nitrogen as being ignited and burned; but if it is +burned and thus consumed, how can it be of service?" Such a thought +is natural enough to one who thinks of burning as applied to ordinary +fuel, which seems to disappear when it is burned. But, of course, even +the tyro in chemistry knows that the fuel has not really disappeared +except in a very crude visual sense; it has merely changed its form. +In the main its solid substance has become gaseous, but every atom of +it is still just as real, if not quite so tangible, as before; and the +chemist could, under proper conditions, collect and weigh and measure +the transformed gases, and even retransform them into solids. + +In the case of the atmospheric nitrogen, as in the case of ordinary +fuel, a burning "consists essentially in the union of nitrogen atoms +with atoms of oxygen." The province of the electric current is to +produce the high temperature at which alone such union will take place. +The portion of nitrogen that has been thus "burned" is still gaseous, +but is no longer in the state of pure nitrogen; its atoms are united +with oxygen atoms to form nitrous oxide gas. This gas, mixed with the +atmosphere in which it has been generated, may now be passed through a +reservoir of water, and the new gas combines with a portion of water +to form nitric acid, each molecule of which is a compound of one atom +of hydrogen, one atom of nitrogen, and three atoms of oxygen; and +nitric acid, as everyone knows, is a very active substance, as marked +in its eagerness to unite with other substances as pure nitrogen is in +its aloofness. + +In the commercial nitrogen-plant at Notodden, the transformed nitrogen +compound is brought into contact with a solution of milk of lime, +with the resulting formation of nitrate of lime (calcium nitrate), +a substance identical in composition--except that it is of greater +purity--with the product of the nitrate beds of Chili. Stored in closed +cans as a milky fluid, the transformed atmosphere is now ready for the +market. A certain amount of it will be used in other manufactories for +the production of various nitrogenous chemicals; but the bulk of it +will be shipped to agricultural districts to be spread over the soil as +fertilizer, and in due course to be absorbed into the tissues of plants +to form the food of animals and man. + + +ANOTHER METHOD OF NITROGEN FIXATION + +Just at the time when the Scandinavian experimenters were solving +the problem of securing nitrogen from the air, other experimenters +in Italy, operating along totally different lines, reached the same +important result. The process employed by these investigators is known +as the Frank and Caro process, and it bids fair to rival the Norwegian +method as a commercial enterprise. The process is described as +follows by an engineering correspondent of the London _Times_ in the +Engineering Supplement of that periodical for January 22, 1908: + +"This process is based upon the absorption of nitrogen by calcium +carbide, when this gas, in the pure form, is passed over the carbide +heated to a temperature of 1,100 degrees centigrade in retorts of +special form and design. The calcium carbide required as raw material +for the cyanamide manufacture is produced in the usual manner by +heating lime and coke to a temperature of 2,500 degrees centigrade in +electric furnaces of the resistance type. + +"The European patent rights of the Frank and Caro process have +been purchased by the Societa Generale per la Cianamide of Rome, +and the various subsidiary companies promoting the manufacture in +Italy, France, Switzerland, Norway, and elsewhere, are working under +arrangement with the parent company as regards sharing of profits. + +"The first large installation of a plant for carrying out this process +was erected at Piano d'Orta, in Central Italy, and was put into +operation in December, 1905. The power for this factory is developed +by an independent company, and is obtained by taking water from the +river Pescara and leading it to a point above the generating station +at Tramonti. A head of 90 feet, equivalent to 8,400 horse-power, is +here made available for the industries of the district. The power of +the cyanamide factory is transmitted a distance of 6-1/4 miles at 6,000 +volts. An aluminum and chemical works are also dependent upon the same +power station. + +"The Piano d'Orta works contains six furnaces for the manufacture of +cyanamide, each furnace containing five retorts for absorption of the +nitrogen by the carbide. A retort is capable of working off three +charges of 100 kilograms (220 pounds) of carbide per day of 24 hours, +the weight of the charge increasing to 125 kilograms by the nitrogen +absorbed. The present carbide consumption of the Piano d'Orta factory +is, therefore, at the rate of about 3,000 tons per annum, and the +output of calcium cyanamide is about 3,750 tons per annum. The company +controlling the manufacture at Piano d'Orta is named the _Societa +Italiana per la Fabbricazione di Prodotti Azotati_. Extensions of +the factory at this place to a capacity of 10,000 tons per annum are +already in progress. Another company is also planning the erection +of similar works at Fiume and at Sebenico, on the eastern borders +of the Adriatic Sea. The additional electric power required will be +obtained by carrying out the second portion of the power development +scheme on the river Pescara. A fall of 235 feet, equivalent to 22,000 +horse-power, is available at the new power station, which is being +erected at Piano d'Orta." + +After stating that companies to operate the Frank and Caro process have +been organized in France, in Switzerland, in Germany, in England, and +in America,--the last-named plant being at Muscle Shoals, Tennessee +River, in Northern Alabama--the writer continues: + +"These facts prove that the manufacture of the new nitrogenous manure +will soon be carried on in all the more important countries on +both sides of the Atlantic. If the financial results come up to the +promoter's expectations the industry in five years' time will have +become one of considerable magnitude. + +"A modification of the original process of some importance has been +suggested by Polzeniusz. This chemist has found that the addition of +fluorspar (CaF2) to the carbide reduces the temperature required +for the absorption process by 400 degrees centigrade, while it also +produces a less deliquescent finished material. + +"As regards cost of manufacture, no very reliable figures are yet +available, but the companies promoting the new manufacture are +regulating their sale prices by those of the two rival artificial +manures--ammonium sulphate and nitrate of soda. Calcium cyanamide is +now being sold in Germany at 1s. to 1s. 6d. (25 to 37 cents) per unit +of combined nitrogen cheaper than ammonium sulphate, and 3s. to 3s. 6d. +(75 to 87 cents) per unit cheaper than nitrate of soda. Whether the +manufacture will prove remunerative at this price of about L10 10s. +($102.50) per ton remains to be seen. It is evident that, as the raw +material of the cyanamide manufacture (calcium carbide) costs at least +L8 ($40) per ton to produce under the most favorable conditions, the +margin of profit will not be large, and that very efficient management +will be required to earn fair dividends on the capital sunk in the new +industry. + +"It must be noted, however, that the processes are new and are +doubtless capable of improvement as experience is gained in working +them; while, on the other hand, the competition of the two rival +artificial manures is likely to diminish as the years pass on. + +"The new industry is, therefore, likely to be a permanent addition to +the list of electro-metallurgical processes. But for the present its +success can only be expected in centres of very cheap water-power, as, +for instance, in those localities where the electric horse-power year +can be generated and transmitted to the cyanamide works at an inclusive +cost of L2 ($10) or under." + + +ELECTRICAL ENERGY AND HIGH TEMPERATURES + +It will be observed that the active instrumentality by which the +industrial feats thus far outlined have been accomplished, is that +weird conveyer of energy known as electricity. In the case of the +aluminum manufacture, electricity operated according to the strange +process of electrolysis, in virtue of which certain atoms of matter +move to one pole of a battery while other atoms move to the opposite +pole, thus effecting a separation--the result being, in the case in +question, the deposit of pure aluminum at the negative pole. In the +case of the nitrogen factories, however, the manner of operation of +the electric current is quite different. Electricity, as such, is not +really concerned in the matter; the efficiency of the current depends +solely upon the production of heat. For example, any other agency +that brought the atmosphere to a corresponding temperature would be +equally efficacious in igniting the nitrogen. But in actual practice, +for this particular purpose, no other known means of producing high +temperatures could at all compete with the electric arc. + +There are numerous other operations involving the employment of high +temperatures in which electricity is equally preeminent. It is feasible +with the electric arc to attain a temperature of about 3,600 degrees +centigrade--and even this might be exceeded were it not that carbon, +of which the electrodes are composed, volatilizes at that temperature. +Meantime, the highest attainable temperature with ordinary fuels in +the blast furnace is only about 1,800 degrees; and the oxy-hydrogen +flame is only about two hundred degrees higher. A mixture of oxygen and +acetylene, however, burns at a temperature almost equaling that of the +electric arc; and this flame, manipulated with the aid of a blowpipe, +offers a useful means of applying a high temperature locally, for such +processes as the welding of metals. The very highest temperatures yet +reached in laboratory or workshop, however, are due to the use of +explosive mixtures. Thus a mixture of the metal aluminum granulated, +and oxide of iron, when ignited by a fulminating powder, readjusts its +atoms to form oxide of aluminum and pure iron, and does this with such +fervor that a temperature of about three thousand degrees is reached, +the resulting iron being not merely melted but brought almost to the +boiling point. Practical advantage is taken of this reaction for the +repair of broken implements of iron or steel, the making of continuous +rails for trolleys, and the like. + +This reaction of aluminum and iron does not, to be sure, give a higher +temperature than the electric arc; but this culminating feat has been +achieved, in laboratory experiments, through the explosion of cordite +in closed steel chambers; the experimenters being the Englishmen Sir +Andrew Noble and Sir F. Abel. It is difficult to estimate accurately +the degree of heat and pressure attained in these experiments; but it +is believed that the temperature approximated 5,000 degrees centigrade, +while the pressure represented the almost inconceivable push of ninety +tons to the square inch. + +It may be of interest to explain that cordite is a form of smokeless +powder composed of gun cotton, nitroglycerine, and mineral jelly. No +doubt the extreme heat produced by its explosion is associated with +the suddenness of the reaction; corresponding to the efficiency as a +propellant that has led to the adoption of this powder for use in the +small arms of the British Army. No commercial use has yet been made +of cordite as a mere producer of heat; but there is an interesting +suggestion of possible future uses in the fact that crystals of diamond +have been found in the residue of the explosion chamber--microscopic +in size, to be sure, but veritable diamonds in miniature. Sir +William Crookes has suggested that, could the reaction be prolonged +sufficiently, "there is little doubt that the artificial formation of +diamonds would soon pass from the microscopic stage to a scale more +likely to satisfy the requirements of science, if not those of personal +adornment." + + +OTHER INDUSTRIAL PROBLEMS OF TO-DAY AND TO-MORROW + +In attempting to suggest the importance of science in its relation +to modern industries, I have thought it better to cite three or +four illustrative cases in some detail rather than to attempt a +comprehensive summary of the almost numberless lines of commercial +activity that have a similar origin and dependence. + +To attempt a full list of these would be virtually to give a catalogue +of mechanical industries. It may be well, however, to point out a few +familiar instances, in order to emphasize the economic importance of +the subject; and to suggest a few of the lines along which present-day +investigators are seeking further conquests. + +Very briefly, then, consider how the application of scientific +knowledge has changed the aspect of the productive industries. Thanks +to science, farming is no longer a haphazard trade. The up-to-date +farmer knows the chemical constitution of the soil; understands what +constituents are needed by particular crops and what fertilizing +methods to employ to keep his land from deteriorating. He knows how +to select good seed according to the teaching of heredity; how to +combat fungoid and insect pests by chemical means; how to meet the +encroachments of the army of weeds. In the orchard, he can tell by the +appearance of leaf and bark whether the soil needs more of nitrogen, +of potash, or of humus; he uses sprays as a surgeon uses antiseptics; +he introduces friendly insects to prey on insect pests; he irrigates +or surface-tills or grows cover crops in accordance with a good +understanding of the laws of capillarity as applied to water in the +earth's crust. In barnyard and dairy he applies a knowledge of the +chemistry of foods in his treatment of flock and herd; he ventilates +his stables that the stock may have an adequate supply of oxygen; he +milks his cows with a mechanical apparatus, extracts the cream with a +centrifugal "separator," and churns by steam or by electric power. + +In the affairs of manufacturer and transporter of commodities, methods +are no less revolutionary. Steam power and electric dynamo everywhere +hold sway; trolley and electric light and telephone have found their +way to the most distant hamlet; electricians and experimental chemists +are searching for new methods in the factories; artificial stone is +competing with the product of the quarries; artificial dyes have +sounded the doom of the madder and indigo industries. + +And yet it requires no great gift of prophecy to see that what has been +accomplished is only an earnest of what is to come in the not distant +future. In every direction eager experimenters are on the track of new +discoveries. Any day a chance observation may open new and important +fields of exploration, just as Hall's observation about the power +of cryolite to absorb aluminum pointed the way to the new aluminum +industry; and as Birkeland's chance observation of the electric arc in +a magnetic field unlocked the secret of the unresponsive nitrogen. It +will probably not be long, for example, before a way will be found to +produce electric light without heat--in imitation of the wonderful lamp +of the glow-worm. + +Then in due course we must learn to use fuel without the appalling +waste that at present seems unavoidable. A modern steam-engine makes +available only five to ten per cent. of the energy that the burning +fuel gives out as heat--the rest is dissipated without serving man the +slightest useful purpose. Moreover, the new studies in radio-activity +have taught us that every molecule of matter locks up among its +whirling atoms and corpuscles a store of energy compared with which +the energy of heat is but a bagatelle. It is estimated that a little +pea-sized fragment of radium has energy enough in store--could we +but learn to use it--to drive the largest steamship across the +ocean--taking the place of hundreds of tons of coal as now employed. +The mechanics of the future must learn how to unlock this treasury of +the molecule; how to get at these atomic and corpuscular forces, the +very existence of which was unknown to science until yesterday. The +generation that has learned that secret will look back upon the fuel +problems of our day somewhat as we regard the flint and steel and the +open fire of the barbarian. + +If problems of energy offer such alluring possibilities as this, +problems of matter are even more inspiring. The new synthetic chemistry +sets no bounds to its ambitions. It has succeeded in manufacturing +madder, indigo, and a multitude of minor compounds. It hopes some day +to manufacture rubber, starch, sugar--even albumen itself, the very +basis of life. Rubber is a relatively simple compound of hydrogen and +carbon; starch and sugar are composed of hydrogen, carbon, and oxygen; +albumen has the same constituents, plus nitrogen. The raw materials +for building up these substances lie everywhere about us in abundance. +A lump of coal, a glass of water, and a whiff of atmosphere contain +all the nutritive elements, could we properly mix them, of a loaf of +bread or a beefsteak. And science will never rest content until it has +learned how to make the combination. It is a long road to travel, even +from the relatively advanced standpoint of to-day; but sooner or later +science will surely travel it. + +And then--who can imagine, who dare predict, the social and economic +revolution that must follow? Our social and business life to-day +differs more widely from that of our grandfathers than theirs differed +from the life of the Egyptian and Babylonian of three thousand years +ago; but this gap is as ditch to canyon compared with the gap that +separates us from the life of that generation of our descendants which +shall have learned the secret of making food-stuffs from inorganic +matter in the laboratory and factory. It is a long road to travel, I +repeat; but modern science travels swiftly and with many short-cuts, +and it may reach this goal more quickly than any conservative dreamer +of to-day would dare to predict. + +All speed to the ambitious voyager! + + + + +APPENDIX + +REFERENCE LIST AND NOTES + + +CHAPTER I + +MAN AND NATURE + +For a general discussion of primitive conditions of labor and +prehistoric man's civilization, it will be of interest in connection +with this chapter to consult volume I., chapter I., which deals with +prehistoric science. The appendix notes on that chapter (vol. I., +pp. 302, 303) refer to some books which may be consulted for fuller +information along the same lines. + + +CHAPTER II + +HOW WORK IS DONE + +(p. 31). For study of Archimedes, giving a detailed account of his +discoveries, see vol. I., p. 196 _seq._ It will be of interest also to +review, in connection with this chapter, the story of the growth of +knowledge of mechanics in the time of Galileo, Descartes, and Newton as +told in the chapters entitled "Galileo and the New Physics," vol. II. +(p. 93 _seq._), and "The Success of Galileo in Physical Science," vol. +II., p. 204 _seq._ + + +CHAPTER III + +THE ANIMAL MACHINE + +For further insight into the activities of the animal machine, the +reader may refer to various chapters on the progress of physiology and +anatomy in earlier volumes. The following references will guide to the +accounts of the successive advances from the earliest time: + +Vol. I., pp. 194, 195 describe briefly the earlier anatomical studies +of the Alexandrian physicians, Herophilus and Erasistratus; and pp. +282, 283, outline the studies of the famous physician, Galen. + +Vol. II., "From Paracelsus to Harvey," in particular, p. 163 _seq._; +and chapters IV. (p. 173 _seq._) and V. (p. 202 _seq._) dealing with +the progress of anatomy and physiology in the eighteenth and nineteenth +centuries respectively. The chapter on "Experimental Psychology" (p. +245 _seq._) may also be consulted. + +Vol. V., chapter V., dealing with the Marine Biological Laboratory +at Naples (p. 113 _seq._) and chapter VI., "Ernst Haeckel and the +New Zoology" (p. 144 _seq._) present other aspects of physiological +problems. + + +CHAPTER IV + +THE WORK OF AIR AND WATER + +On page 63 reference is made to the work of the old Greeks, Archimedes +and Ctesibius. An account of Archimedes' discovery of the laws of +buoyancy of solids and liquids will be found in vol. I., p. 208. + +(p. 64). The machines of Ctesibius and Hero. See vol. I., p. 242 +_seq._, for a full account of these mechanisms. + +(p. 65). Toricelli, the pupil of Galileo, and his discovery of +atmospheric pressure. For a fuller account of his discovery and what +came of it see vol. II., p. 120 _seq._ + +(p. 66). Boyle's experiments on atmospheric pressure. See vol. II., p. +204 _seq._ + +(p. 66). Mariotte and Von Guericke. See vol. II., p. 210 _seq._ + +(p. 71). Roman mills. A scholarly discussion of the subject of Roman +mills, based on a comprehensive study of the references in classical +literature, is given in Beckmann's _History of Inventions_, London, +1846. + +(p. 73). Recent advances in water wheels. As stated in the text, the +quotation is from an article on _Motive Power Appliances_, by Mr. +Edward H. Sanborn, in the _Twelfth Census Report_ of the United States. + + +CHAPTER V + +CAPTIVE MOLECULES; THE STORY OF THE STEAM-ENGINE + +(p. 82). The experiments of Hero of Alexandria. For a full account of +the experiments see vol. I., pp. 249, 250. + +(p. 84). The Marquis of Worcester's steam engine. The original account +appeared, as stated, in the Marquis of Worcester's _Century of +Inventions_, published in 1663. + +(p. 92). Newcomen's engine. As stated in the text, the account of +Newcomen's engine is quoted from the report of the Department of +Science and Arts of the South Kensington Museum, now officially known +as the Victoria and Albert Museum. + +(pp. 107-109). James Watt. The characterization of Watt here given is +taken from an article in an early edition of the Edinburgh Encyclopaedia +published about the year 1815. + + +CHAPTER VI + +THE MASTER WORKER + +(p. 112). High-pressure steam. The work referred to is Leupold's +_Theatrum Machinarum_, 1725. + +(p. 122). Rotary Engines. The quotation is from the report of the +Victoria and Albert Museum above cited. + +(pp. 127, 128). Turbine engines. The quotation is from an anonymous +article in the London _Times_, August 14, 1907. + +(pp. 129, 130). Turbine engines. The quotation is from an article on +_Motive Power Appliances_ in the _Twelfth Census Report_ of the United +States, vol. X., part IV., by Mr. Edward H. Sanborn. + + +CHAPTER VII + +GAS AND OIL ENGINES + +(pp. 135, 136, 137). Gas engines. Quoted from the report of the +Victoria and Albert Museum above cited. + +(pp. 141-144). Gas engines and steam engines in the United States. +Quoted from the report of the Special Agents of the _Twelfth Census_ of +the United States, 1902. + +(pp. 146, 147). The Svea heater. From an article by Mr. G. Emil Hesse +in _The American Inventor_ for April 15, 1905. + + +CHAPTER VIII + +THE SMALLEST WORKERS + +In connection with this chapter the reader will do well to review +various earlier portions of the work outlining the general history of +the growth of knowledge of electricity and magnetism. For example: + +Vol. II., p. 111 _seq._, for an account of William Gilbert's study +of magnetism; pp. 213, 215 describing first electrical machine; and +chapter XIV., "The Progress of Electricity from Gilbert and Von +Guericke to Franklin," p. 259 _seq._ + +Vol. III., chapter VII., "The Modern Development of Electricity and +Magnetism," p. 229 _seq._ + +Vol. V., p. 92 _seq._, the section on Prof. J. J. Thompson and the +nature of electricity. + +Other chapters that may be advantageously reviewed in connection with +the present one are the following: + +Vol. III., chapter VI., "Modern Theories of Heat and Light," p. 206 +_seq._; chapter VIII., "The Conservation of Energy," p. 253 _seq._; and +chapter IX., "The Ether and Ponderable Matter," p. 283 _seq._ + + +CHAPTER IX + +MAN'S NEWEST CO-LABORER: THE DYNAMO + +The references just given for chapter VIII. apply equally here. + +The experiments of Oersted and Faraday are detailed in vol. III., p. +236 _seq._ + + +CHAPTER X + +NIAGARA IN HARNESS + +Same references as for chapters VIII. and IX. + + +CHAPTER XI + +THE BANISHMENT OF NIGHT + +(p. 221). Davy and the electric light. The quotation here given is +reproduced from vol. III., pp. 234, 235. The very great importance +and general interest of the subject seem to justify the repetition, +descriptive of this first electric light. Davy's original paper was +given at the Royal Institution in 1810. + +(p. 237). "Peter Cooper Hewitt--Inventor," by Ray Stannard Baker, in +_McClure's Magazine_, June, 1903, p. 172. + +In connection with the problem of color of the light emitted by Mr. +Hewitt's mercury-vapor tube, the chapter on "Newton and the Composition +of Light" (vol. II., p. 225 _seq._) may be consulted. Also "Modern +Theories of Heat and Light," vol. III., p. 206 _seq._ + + +CHAPTER XII + +THE MINERAL DEPTHS + +The chapter on "The Origin and Development of Modern Geology," vol. +III., p. 116 _seq._, may be read in connection with the allied subjects +here treated. + +In preparing the section on the use of electricity in mining, the +article by Thomas Commerford Martin, entitled _Electricity in Mining_, +in the United States _Census Report_ of 1905, has been freely drawn +upon. The quotations on pp. 262, 266, 268, and 270 are from that source. + + +CHAPTER XIII + +THE AGE OF STEEL + +See note under chapter XII. + + +CHAPTER XIV + +SOME RECENT TRIUMPHS OF APPLIED SCIENCE + +In connection with various portions of this chapter the reader will +find much that is of interest in the story of chemical development in +general as detailed in volume III., pp. 3-72 inclusive. + +Also various chapters on electricity as outlined under chapter VII. +above. + +(p. 310). Nitrogen from the air. The quotation is from the _Engineering +Supplement_ of the London _Times_, January 22, 1908. + + + + + TRANSCRIBER'S NOTES + + Italic text is denoted by _underscores_. + The oe ligature has been expanded to 'oe'. + Subscripts in chemical formulas are denoted by normal numbers; + for example CaC2. + + Obvious typographical and punctuation errors have been corrected + after careful comparison with other occurrences within the text + and consultation of external sources. + + Except for those changes noted below, inconsistent or archaic + spelling of a word or word-pair within the text has been retained. + For example: horseshoe horse-shoe; superheated super-heated; + intrusted; incased. + + p iii. 'Friction, p. 35' changed to 'Friction, p. 39'. + p iii. 'muscular action, p. 45' changed to '... action, p. 49'. + p iv. 'wind-mill' changed to 'windmill'. + p iv. 'Ctesibus' changed to 'Ctesibius'. + p 93. 'was done is' changed to 'was done in'. + p 114 (Illustration caption). 'Trevethick' changed to 'Trevithick'. + p 122. 'drlving' changed to 'driving'. + p 180 (Illustration caption). 'pull pieces' left unchanged (probably + meant to be 'pole pieces'). + p 191. 'Horsehoe' changed to 'Horseshoe'. + p 264. 'Liege' changed to 'Liege'. + p 299. 'repellant' changed to 'repellent'. + + + + + +End of the Project Gutenberg EBook of Every-day Science: Volume VI. 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