- 
 

FIRST 'GLIMPSB OF THE ELECTRIC LIGHT. 
 
THE 
 
 AGE OF ELECTRICITY 
 
 From Amber-Soul to Telephone 
 
 BY 
 
 PARK BENJAMIN, PH.D. 
 
 Ariel and all his quality." 
 
 The Tempest. 
 
 NEW YORK 
 CHARLES SCRIBNER'S SONS 
 
 1889 
 
COPYRIGHT, 1886, BY 
 CHARLES SCRIBNER'S SONS. 
 
 PRESS OF BERWICK & SMITH, 
 BOSTON, MASS. 
 
PREFACE. 
 
 THIS little work is not a technical treatise, nor is it 
 addressed in any wise to the professional electrician. It 
 is simply an effort to present the leading principles of 
 electrical science, their more important applications, and 
 of these last the stories, in a plain and, it is hoped, a 
 readable way. There are no formulas in the book. 
 Only such technical terms as have now made their way 
 into every-day use are employed ; and the more strictly 
 scientific branches of the subject, such as measurement, 
 testing, etc., are omitted altogether. 
 
 It is a singular fact, that probably not an electrical 
 invention of major importance has ever been made, but 
 that the honor of its origin has been claimed by more 
 than one person. There was a dispute over the Leyden- 
 jar, and a long and acrimonious, controversy about the 
 galvanic battery. Franklin's discovery of the identity 
 of lightning and electricity is still claimed for French 
 philosophers; the title of u the father of the telegraph'* 
 is given to Wheatstone in England, and to Morse in the 
 United States, although to neither of these inventors, but 
 to Joseph Henry, the lasting gratitude of the world be- 
 
 iii 
 
 136 
 
iv PEE FACE. 
 
 longs ; Dal Negro, McGawley, Page, and Henry have all 
 been named each as the first and only original inventor 
 of the electro-motor ; Davidson, Davenport, Lillie, Jacobi, 
 Page, and Hall are each credited with the invention of 
 the electric railway ; Page and Ruhmkorff dispute the 
 invention of the induction coil ; Jordan and Spenser, and 
 others beside, waged a bitter war over their respective 
 claims to the discovery of the electro-deposition of 
 metals. Plaute, as the inventor of the secondary bat- 
 tery, becomes deposed by the prior work of Ritter ; 
 Gramme finds his ring armature in the dynamo antici- 
 pated by Pacinotti. Professor Hughes had no sooner 
 announced his microphone than Mr. Edison claimed it. 
 Hjorth, Varley, Siemens, and Wheatstone share the 
 honor of originating the self-exciting dynamo. Contests 
 are still in existence over the incandescent electric lamp, 
 with Edison and Swan and Sawyer in the front. And as 
 for the present telephone war, the greatest conflict of 
 all, this is fast becoming not merely a question of 
 whether Reis or Drawbaugh or Gray or Bell or Dolbear, 
 or any other of the numerous claimants, was or was not 
 the inventor of the electrical transmission of speech, but 
 a national issue involving the rights of the people against 
 corporate monopoly, and perhaps also in some degree the 
 integrity of our patent system. 
 
 Where it has been necessary to deal with these disputed 
 matters, the author has endeavored to present the facts 
 without partisan bias. The reader will, no doubt, notice 
 that the names of many electrical inventors now celebrated 
 
PREFACE. V 
 
 are not mentioned, or but briefly referred to. This is 
 because their inventions when theirs are but improve- 
 ments in details remarkable rather for quantity than 
 quality ; or else require descriptions too technical for 
 these pages. 
 
 For the most part, all historical data have been gath- 
 ered from publications contemporary with the date of first 
 production of the several discoveries and inventions, and 
 in many cases from the original writings of the inventors 
 and discoverers themselves. As for sources of informa- 
 tion in general, the author can only say that there lie 
 before him, at this writing, the first book on electricity 
 ever written in the English language, Robert Boyle's 
 modest little pamphlet of 1675, and the latest numbers 
 of the electrical journals, fresh from the press ; and that 
 he has ranged throughout the whole field of electrical 
 literature anywhere and everywhere, in the most arbitrary 
 manner, between these limits. 
 
 In a few instances, however, it would be ungracious 
 to deny special credit : and therefore acknowledgment is 
 made for aid from Prof. S. P. Thomson's excellent " Ele- 
 mentary Lessons in Electricity and Magnetism," Mr. J. 
 H.Gordon's ''Treatise on Electric Lighting," Messrs. 
 Preece & Sivewright's "Telegraphy," and Prof. J. T. 
 Sprague's latest and best treatise on " Electricity," among 
 modern works ; and from Dr. Priestley's grand "History 
 of Electricity," among those of the last century. Free 
 use has been made of the files of "The Scientific Amer- 
 ican," of " The Journal of the Franklin Institute," and 
 
vi PREFACE. 
 
 the special electrical journals of this country; and of 
 those of " Engineering " and "The Mechanics' Maga- 
 zine," and electrical periodicals abroad. In the prepara- 
 tion of the chapter on Telegraphy, Mr. Alfred M. A. 
 Beale has rendered valuable assistance ; and several of 
 the engravings in the chapter on Galvanic Batteries have 
 been kindly supplied by Messrs. John Wiley & Sons, from 
 Niaudet's work on that subject. 
 
 NEW YORK, May 15, 1886. 
 
CONTENTS. 
 
 CHAPTER PAGE 
 
 I. THE MYTH OF THE AMBER SOUL .... 1 
 II. THE DISCOVERIES OF THE EARLY EXPERI- 
 MENTERS 7 
 
 III. THE CAGING OF THE LIGHTNING .... 15 
 
 IV. ELECTRICITY IN HARNESS 28 
 
 V. THE GALVANIC BATTERY, AND THE CONVERSION 
 
 OF CHEMICAL ENERGY INTO ELECTRICAL 
 
 ENERGY 35 
 
 VI. THE ELECTRO-MAGNET, AND THE CONVERSION OF 
 
 ELECTRICITY INTO MAGNETISM .... 68 
 VII. THE DYNAMO-ELECTRIC MACHINE, AND THE CON- 
 VERSION OF MAGNETISM AND MECHANICAL 
 MOTION INTO ELECTRICITY 88 
 
 VIII. THE ELECTRIC LIGHT. THE CONVERSION OF 
 
 ELECTRICAL ENERGY INTO HEAT AND LIGHT . 118 
 IX. ELECTRO-MOTORS, AND THE CONVERSION OF ELEC- 
 TRICAL ENERGY INTO MECHANICAL ENERGY . 152 
 X. ELECTROLYSIS. ELECTRO-METALLURGY AND THE 
 
 STORAGE-BATTERY 182 
 
 vU 
 
Vlll CONTENTS. 
 
 CHAPTEK PAGE 
 
 XI. THE ELECTRIC TELEGRAPH 208 
 
 XII. THE SPEAKING TELEPHONE 272 
 
 XIII. THE INDUCTION COIL, AND POWERFUL ELECTRIC 
 
 DISCHARGES 325 
 
 XIV. THE APPLICATIONS OF ELECTRICITY TO MEDICINE, 
 
 WAR, RAILWAYS, TIME, Music, ETC. . , 333 
 
THE AGE OF ELECTRICITY. 
 
THE AGE OF ELECTRICITY. 
 
 CHAPTER I. 
 
 THE MYTH OF THE AMBER SOUL. 
 
 SOME years ago, there was found in a tomb in Egypt an 
 alabaster vase, the sole contents of which were a few dry, 
 hard, and blackened seeds. These the discoverer brought 
 to England, and planted them in the rich loam of his 
 garden, more from curiosity than from any belief that 
 they actually would germinate. To his surprise, in due 
 time fresh young sprouts appeared which grew and flour- 
 ished ; and finally, in the harvest season, ears of wheat, 
 as many as fifteen or twenty from a single stalk, were 
 gathered. So it was proved that despite their having 
 been sealed in the ancient tomb for nearly three thousand 
 years, the seeds, to all appearances as lifeless as the huge 
 stones which surrounded them, had retained all their vi- 
 tality ; and we might imagine, that if, during these many 
 centuries, wheat had disappeared from among the earth's 
 products, it would have been possible in time from these 
 few grains to cause all the lands again to teem with golden 
 harvest. 
 
 A suggestive parallel exists between the history of the 
 wheat kernel shut up in the Egyptian tomb, and that 
 
 1 
 
2 THE AGE OF ELECTRICITY. 
 
 of a mere atom of human knowledge which for nearly 
 as long a period remained as unfruitful and buried in 
 the minds of men. Indeed, among all the wonders of 
 that strangest manifestation of the energy which pervades 
 all nature, and which we call electricity, there is nothing 
 more remarkable and more impressive than the growth of 
 the single, simple, and uncoordinated fact, namely, that 
 amber, when rubbed, behaves in a curious way, into the 
 great science which underlies the telegraph, the electric 
 light, and the telephone. 
 
 How rapid this growth has been, is within the remem- 
 brance of most of us. Of the vastness of its extent, we 
 have on all sides ocular proof. What farther progress 
 may be made, no one can predict. Conjecture too often 
 outstrips reason : impossibilities and impracticabilities be- 
 come confounded ; and each new advance only reveals a 
 new horizon, beyond which who knows what fields may 
 lie? 
 
 There is a familiar old Greek legend, which tells how 
 Phaethon, son of the Sun, once rashly undertook to drive 
 his father's chariot through the heavens. As the story 
 goes, the horses despised their driver, and refused to be 
 guided by him, so that the blazing chariot approached too 
 near the earth, and living things thereon were burned. 
 Then Jupiter, very wroth, hurled his thunderbolt, and 
 killed the charioteer. When his body, which fell to the 
 earth, was found by his sisters, the Heliades, they mourned 
 long and bitterly, until at last the Father of Gods, pitying 
 them, changed them into ever-sighing poplars, and their 
 tears into translucent amber. 
 
 And so, perhaps because of this legend, the Greeks 
 looked upon amber with superstitious reverence, and even 
 thought that it had a soul. For when it was rubbed, it 
 seemed to live, and to exercise an attraction upon other 
 
THE MYTH OF THE AMBEE SOUL. 3 
 
 things distant from it. They likened it to the magnet ; and 
 yet knew it to be different from the loadstone, for in the 
 latter the property of drawing other things to itself was 
 inherent, whereas amber could only be brought into life and 
 activity. It was easier to conceive how a natural body 
 might have its own peculiar properties, however incom- 
 prehensible, just as a tree might grow, than to ima- 
 gine how this strange substance, at one time inert, could be 
 brought to life by the same process which would restore 
 vitality to a limb benumbed by cold. Thus they specu- 
 lated upon an amber life, and an amber soul as its 
 essence. 
 
 In the light of our modern knowledge we might perhaps 
 trace farther the chain of ancient speculation. Jupiter's 
 thunderbolt was but another name for the lightning-stroke, 
 and the sequence of events following the tragedy resulted 
 in amber. From amber we can reproduce the lightning in 
 miniature ; so that by some stretch of the imagination 
 we might suppose that the Greeks had a crude concep- 
 tion of electrical storage, and traced the manifestations 
 derived from amber to imprisoned lightning. It is quite 
 certain, however, that those who were initiated in the 
 mystic rites of the ancients clearly understood many of 
 the principles of electricity and magnetism which have been 
 re-discovered within recent years. Professor Schweigger 
 considers that the Vestal fire was electrical, and points 
 out that the "twin fires from the electrical spark are 
 sketched in a very natural manner in the representations 
 of Castor and Pollux on ancient coins." So also it is 
 believed that the ancients knew of the therapeutic effects 
 of electrical currents, and the polarity of electricity and 
 magnetism. 
 
 Although these mysteries were jealously guarded from 
 public comprehension, and hence all knowledge of them 
 
4 THE AGE OF ELECTRICITY. 
 
 died with its possessors, Ennemoser in his History of 
 Magic says that "it was not forbidden to make known 
 every thing : some things were explained to the uniniti- 
 ated. For instance, the uninitiated were made acquainted 
 with amber, and with its property when rubbed." We 
 can conjecture that the uninitiated were thus favored be- 
 cause in any event they would be reasonably certain to 
 find out the phenomenon for themselves. Amber was 
 constantly worn as an amulet and in jewellery ; and the 
 friction of garments would produce sufficient excitation 
 to cause it to attract lint or other fine particles which 
 would dim its lustre, and so draw the wearer's atten- 
 tion. And of course, inasmuch as explanations natur- 
 ally would be sought, it perhaps suited the policy of the 
 magi to attribute the fact to the supernatural qualities of 
 the substance. It is remarkable, however, to note that 
 the knowledge of the electrical properties of amber sur- 
 vived for centuries, doubtless, because the whole world had 
 it, while the great mass of facts which the priests and magi 
 collected fell into utter oblivion ; and that this is exactly 
 the reverse of the conditions under which the great bulk of 
 learning which was handed down from antiquity through 
 the dark ages maintained its existence. The mediaeval 
 monks and scholars treasured their knowledge of natural 
 science while dwelling amid rude and barbarous peoples, 
 in order that it might be handed down to posterity. The 
 Greek and Egyptian priests, on the other hand, in the 
 midst of the most cultivated peoples that had ever lived, 
 surrounded their discoveries with every sort of misleading 
 myth, until finally they faded into oblivion. 
 
 As the world grew older, here and there in the writings 
 of the philosophers reference to this strange property of 
 amber appears. Thales (600 B.C.) mentions it, and, 
 being the earliest writer who has been found to do so, is 
 
THE MYTH OF THE AMBER SOUL. 5 
 
 too often credited with the discovery. Some three hun- 
 dred years later Theophrastus notes that another body, 
 called lyncurium, supposed to be either tourmaline, or 
 the hyacinth, which looks like amber, acts in like man- 
 ner ; and Pliny (B.C. 70) refers to the same. 
 
 Then there is a great gap of sixteen centuries, with 
 hardly a published word to show that all had not been for- 
 gotten. Beckmann quotes from an edition of John Sera- 
 piou, " Lib. de simplicibus medicinis," published in 1531, 
 a reference to a red stone, " Hager Albuzedi." found in 
 the East, " which when strongly rubbed against the hair of 
 the head attracts chaff as the magnet does iron ; " and per- 
 haps other references exist. The fact however, remained, 
 and was supposed to be peculiar to amber. No one 
 attempted to explain it. The superstition of the amber 
 soul faded and was forgotten. The phenomena which 
 Pliny called the "awful mysteries of nature" puzzled 
 men's souls ; yet to inquire into them suggested only 
 impiety. " A star," says Seneca, "settled on the lance 
 of Gylippus as he was sailing to Syracuse ; and spears 
 have seemed to be on fire in the Roman camp." "About 
 that time," Caesar records, " there was a very extraordinary 
 appearance in the army of Caesar. In the mouth of Feb- 
 ruary, about the second watch of the night, there suddenly 
 arose a thick cloud, followed by a shower of stones ; and 
 the same night, the points of the spears belonging to the 
 fifth legion seemed to take fire." Aristotle, Pliny, Oppian, 
 and Claudius were fully acquainted with the shocks pro- 
 duced by the torpedo. Eustathius, who lived in the fourth 
 century of the Christian era, says that a freedman of Tibe- 
 rius was cured of the gout by a shock from this fish ; the 
 first-known instance of the application of electricity to 
 medical purposes, and if authentic much more successful 
 than its application in modern times. The same authority 
 
6 THE AGE OF ELECTRICITY. 
 
 asserts that Wolimer, king of the Goths, was able to emit 
 sparks from his body. But all these were wonders beyond 
 human ken and control. The whole science lay in the 
 knowledge of the single fact, that excited amber attracted 
 certain light bodies. 
 
DISCOVERIES OF EAELY EXPERIMENTERS. 
 
 CHAPTER II. 
 
 THE DISCOVERIES OF THE EARLY EXPERIMENTERS. 
 
 IN the year 1GOO Dr. William Gilbert of London, a 
 surgeon to Queen Elizabeth, published his famous work 
 " De Magnete," and then made known that the attractive 
 property of amber, when rubbed, was not inherent to that 
 substance, but existed in some twenty other bodies, such as 
 the precious stones, glass, sealing-wax, sulphur, and resin. 
 Inasmuch as these all acted like amber, Gilbert called 
 them electrics; and he described the peculiar phenomenon 
 itself as electricity, deriving the term from the Greek 
 word for amber, elektron. It has recently been pointed 
 out, that the Elektra of the Homeric legends possesses 
 certain qualities that would tend to suggest that she is 
 the personification of lightning, and that the resemblance 
 between the names Elektra and elektron cannot be ac- 
 cidental. Whether, however, Gilbert was thus antici- 
 pated or not, is immaterial. The publication of his work 
 marks the true beginning of the progress of the science ; 
 and its immediate effect was to incite philosophers every- 
 where to efforts to extend his list of electrics. 
 
 Singularly enough, this remarkable treatise was severely 
 condemned by Bacon in the " Novum Organum." Not 
 content with singling it out for citation as a peculiarly 
 striking instance of inconclusive reasoning, and of truth 
 distorted by " preconceived fancies/' he elsewhere alludes 
 
8 THE AGE OF ELECTRICITY. 
 
 to the " electric energy concerning which Gilbert has told 
 so many fables." A century and a half later, as we shall 
 see, these " fables " assumed the form of realities. The 
 sweeping censure of so high an authority seems to have 
 produced its natural effect, and may have had much to do 
 in materially retarding the development of the infant 
 science. 
 
 To Gilbert's category, Cabaeus, an Italian Jesuit, added 
 the gums, white wax, and gypsum. Then Robert Boyle 
 got the first glimpse (it was no more) of the electric light, 
 by noting that a diamond when rubbed became luminous 
 in the dark. Then Otto von Guericke, burgomaster of 
 Magdeburg, and inventor of the air-pump, discovered that 
 electricity was manifested by repulsion as well as by at- 
 traction, and that a globe of sulphur after attracting a 
 feather repelled the same until the feather had again been 
 placed in contact with some other substance. 
 
 Guericke contrived an apparatus for rotating his sulphur 
 globe, and succeeded in obtaining sparks therefrom ; and 
 that was the real genesis of the electric light. By this 
 time the attention of the scientific world was aroused, 
 and other philosophers joined in the investigation of the 
 curious phenomena. Boyle, then contemporary with von 
 Guericke, proved that a suspended piece of rubbed am- 
 ber, which attracted other bodies to itself, was in turn 
 attracted by a body brought near it ; and he even went 
 so far as to maintain that an electrified body threw out 
 an invisible glutinous substance which laid hold of light 
 bodies, and, returning to the source from which it ema- 
 nated, carried them along with it. Sir Isaac Newton, by 
 rubbing a flat glass, caused light bodies to jump between 
 it and the table, and noticed that electric attraction was 
 thus transmitted through the glass. A sea-captain named 
 Grofton excited the dismay of mariners by asserting that 
 
DISCOVERIES OF EARLY EXPERIMENTERS. 9 
 
 a violent thunder-storm had reversed the polarity of the 
 compass-needles aboard his vessel. Dr. Wall, in 1708, 
 made experiments with large pieces of amber rubbed by 
 wool, and found that " a prodigious number of little crack- 
 lings " was produced, each accompanied by a flash of light. 
 " This light and crackling," says Dr. Wall, " seem in 
 some degree to represent thunder and lightning." 
 
 Probably every one has observed the peculiar crackling 
 which follows combing of the hair during dry, cold weather, 
 and the tendency of the " knotted and combined locks to 
 part" under the electrical excitement following the rub- 
 bing of the comb. 
 
 Robert Boyle appears to have discovered this ; and he 
 wrote in 1G75 this amusing description intended to be 
 perfectly serious and scientific of his original experi- 
 ment on "Locks (false) worn by two very Fair Ladies 
 that you know:" "For at some times I observed that 
 they could not keep their Locks from flying to their Cheeks 
 and (though neither of them made any use or had any 
 need of Painting) from sticking there. When one of these 
 Beauties first shew'd me this Experiment, I turn'd it into 
 a Complemental Raillery, as suspecting there might be 
 some trick in it, though I after saw the same thing happen 
 to others Locks too. But as she is no ordinary Virtuoso., 
 she very ingeniously remov'd my suspicions and (as I re- 
 quested) gave me leave to satisfie myself further by desir- 
 ing her to hold her warm hand at a convenient distance 
 from one of these Locks taken off and held in the air. For 
 as soon as she did this, the lower end of the Lock which 
 was free applied itself presently to her hand : which seemed 
 the most strange because so great a multitude of Hair 
 would not have been easily attracted by an ordinary 
 Electrical Body." 
 
 In this way, for more than a hundred and twenty years 
 
10 THE AGE OF ELECTRICITY. 
 
 after the publication of Gilbert's work, and at long inter- 
 vals, isolated phenomena were observed, and a fact here 
 and there gathered. A variety of curious theories had 
 been formulated. Cabseus, in the quaint language of 
 Robert Boyle, "thinks the drawing of light bodies by 
 Jet, Amber, etc., may be accounted for by supposing that 
 the steams that issue, or if I may so speak, sally, out of 
 Amber when heated by rubbing, discuss and expell the 
 neighbouring air ; " and that these " Electrical Steams . . . 
 shrinking back swiftly enough to the Amber do in their 
 returns bring along with them such light bodies as they 
 meet with in their way." Then there was the hypothesis 
 "proposed by that Ingenious Gentleman Sir Kenelm Digby, 
 and embraced by the very Learned Dr. Browne," that 
 " Rayes or Files of unctuous steams " were emitted, which 
 became cooled and condensed, and so "shrinking" back, 
 carried light bodies with them. Newton supposed that 
 the excited body emitted an elastic fluid which penetrated 
 glass ; and Gravesande and other writers maintained that 
 electricity was fire, which, being inherent to all bodies, 
 became manifest by friction. 
 
 In 1720 Stephen Gray, a Charterhouse pensioner, that 
 "most meritorious philosopher" as Tyndall calls him, 
 began a series of investigations which terminated only 
 when he died sixteen years later. 
 
 In 1729 Gray experimented with a glass tube stopped 
 by a cork. When the tube was rubbed, the cork attracted 
 light bodies. Gray states that he was "much surprised " 
 at this, and he "concluded that there was certainly an 
 attractive virtue communicated to the cork." " This," 
 says Professor Tyndall, " was the starting-point of our 
 knowledge of electric conduction ; ' ' and the same author- 
 ity gives the following account of Gray's most remarkable 
 experiment : 
 
DISCOVERIES OF EARLY EXPERIMENTERS. 11 
 
 "He suspended a long hempen line horizontally by 
 loops of pack-thread, but failed to transmit through it the 
 electric power. He then suspended it by loops of silk, 
 and succeeded in sending the ' attractive virtue ' through 
 seven hundred and sixty-five feet of thread. He at first 
 thought that the silk was effectual because it was thin ; 
 but on replacing a broken silk loop by a still thinner wire, 
 he obtained no action. Finally he came to the conclusion 
 that his loops were effectual, not because they were thin, 
 but because they were silk. This was the starting-point 
 of our knowledge of insulation." 
 
 Gray died in the midst of his work ; and the report of 
 his last experiments was dictated by him from his death- 
 bed, to the secretary of the Royal Society. 
 
 In 1733 Dufay, a French physicist, while experimenting 
 with an electrically excited body, found that a piece of 
 gold-leaf floating in the air was repelled if the excited 
 substance was glass, and attracted if the excited sub- 
 stance was resin. And hence he recognized two kinds of 
 electricity, which were for a long time known respectively 
 as vitreous and resinous. There is no such real distinc- 
 tion, because by changing the rubbing material the elec- 
 tricity of resin can be obtained upon glass, and vice versa. 
 But what we now know as plus or positive electricity is 
 that produced by rubbing glass with silk ; and negative 
 or minus electricity, that due to the rubbing of resin with 
 flannel. 
 
 The electrical apparatus of 1730 was, as may readily be 
 imagined, very crude. We reproduce from Dr. Grave- 
 sande's treatise of that date, the accompanying represen- 
 tation of an electrical machine of the period. It consists 
 simply of a glass globe G, supported on tubes which are 
 revolved by a belt from the - large pulley R, which is 
 rotated by the handle M. One of the tubes has an 
 
12 
 
 THE AGE OF ELECTRICITY. 
 
 open end, and is provided with a stop-cock E. Through 
 this tube the air can be exhausted from the interior of 
 
 Fig. 1. Electrical Machine of 1730. 
 
 the globe. Over the globe is an arch of brass wire from 
 which are suspended threads. The hand is used as a 
 
DISCOVERIES OF EARLY EXPERIMENTERS. 13 
 
 rubber, and the machine as shown is intended to demon- 
 strate the following experiment : 
 
 " Whirl the globe, and apply the hand, and immediately 
 the threads will be moved irregularly by the agitation of 
 the air ; but when the glass is heated by the attrition, all 
 the threads are directed toward the centre of the globe, 
 as may be seen in the figure ; and, if the hand be applied 
 a little on one side, or nearer the pole of the globe, 
 the threads will be directed toward that point of the axis 
 which is tinder the hand. If the air be drawn out of the 
 globe, this whole effect ceases." 
 
 This machine had a very disagreeable habit of explod- 
 ing by reason of the expansion of the air within the glass 
 globe, caused by the heating of the latter by friction. 
 
 We have already stated that Otto von Guericke made 
 his electrical machine from a globe of sulphur. For the 
 sulphur globe, Hawksbee and Winkler substituted the 
 glass globe represented in the engraving. The prime 
 conductor, at first a tin tube supported by resin or sus- 
 pended by silk, and nearly equal in importance to the 
 glass insulator which is to be excited, was not invented 
 until ten years after by Boze of Wittenberg (1741) ; and 
 Winkler of Leipsic suggested a fixed cushion instead of 
 the human hand as a rubber. Still later Gordon of Erfurt 
 substituted a glass cylinder for the globe; and in 1760 
 Planta introduced the circular plate of glass still used. 
 
 In the year 1745 a discovery was made, which in point 
 'of importance overshadowed every thing that had been 
 previously accomplished. And it seems as if the time 
 had come for some great advance. The electrical machine 
 had reached a form in which, with little variation, it has 
 since remained. Large pieces of electrical material had 
 been used to produce manifestations sufficiently potent to 
 suggest thunder and lightning ; and certain properties of 
 
14 THE AGE OF ELECTRICITY. 
 
 the electric fluid, or aura, or whatever it might be, had been 
 more or less perfectly recognized. Yet, after all, what 
 practical advantage to mankind had been gained ? Curious 
 things had been developed, as wonderful as any thing the 
 conjurers could do ; but beyond gratifying the natural 
 taste for the marvellous, and furnishing food for the 
 speculations and material for the lecture-room experi- 
 ments of a few philosophers, all that had been done had 
 added nothing, so far as then appeared, to. that knowledge 
 which directly contributes to human welfare. 
 
THE CAGING OF THE LIGHTNING. 15 
 
 CHAPTER III. 
 
 THE CAGING OF THE LIGHTNING. 
 
 ON Oct. 11, 1745, Dean von Kleist of the cathedral of 
 Camin, in Germany, made an experiment which on the 
 following 4th of November he describes in a letter to Dr. 
 Lieberkuhn of Berlin, in the following terms : 
 
 " When a nail or a piece of brass wire is put into a 
 small apothecaries' phial and electrified, remarkable effects 
 follow ; but the phial must be very dry and warm. I com- 
 monly rub it over beforehand with a finger on which I put 
 some powdered chalk. If a little mercury or a few drops 
 of spirits of wine be put into it, the experiment succeeds 
 the better. As soon as this phial and nail are removed 
 from the electrifying glass, or the prime conductor to 
 which it hath been exposed is taken away, it throws out 
 a pencil of flame so long that with this burning machine 
 in my hand I have taken about sixty steps in walking 
 about my room ; when it is electrified strongly I can take 
 it into another room, and then fire spirits of wine with it. 
 If while it is electrifying I put my finger or a piece of gold 
 which I hold in my hand to the nail, I receive a shock 
 which stuns my arms and shoulders." 
 
 This was the first announcement of the possibility of 
 accumulating electricity. 
 
 In the following year Cunseus of Leyden made substan- 
 tially the same discovery. It caused great wonder and 
 
16 THE AGE OF ELECTRICITY. 
 
 dread, which arose chiefly from the excited imagination. 
 Musscheubroek felt the shock, and declared in a letter to 
 a friend, that he would not take a second one for the crown 
 of France. Bleeding at the nose, ardent fever, a heavi- 
 ness of head which endured for days, were all ascribed to 
 the shock. Boze, on the other hand, seems to have coveted 
 electrical martyrdom ; for he is said to have expressed a 
 wish to die by the electric shock, " so that an account of 
 his death might furnish an article for the Memoirs of the 
 French Academy of Sciences." 
 
 Winkler, his coadjutor in the improvement of the elec- 
 trical machine, " suffered great convulsions through his 
 body," which " put his blood into agitation ; " and his wife, 
 who took the shock twice, was rendered so weak by it that 
 she could hardly walk. Nothing daunted, this adventur- 
 ous lady (who shall say whether from scientific interest or 
 feminine curiosity?) persisted in being shocked for the 
 third time ; and then her previous ailments were augmented 
 by the nosebleed. 
 
 After the philosophers had got through administering 
 shocks to themselves and to their immediate relatives, and 
 had recovered in some measure their mental as well as per- 
 sonal equilibrium, and it might equally well be added, 
 their moral balance, for as a matter of fact their reports 
 as to the force of the shock and its attendant disastrous 
 effects were all more or less grossly exaggerated, they 
 sot about seeing what this extraordinary discovery really 
 amounted to. What Von Kleist actually did was simply 
 to insert a nail through a cork into a phial into which he 
 poured a little mercury, spirits, or water. Why this sim- 
 ple contrivance should produce the observed effects, Von 
 Kleist did not know ; but Cunseus and the other Leyden 
 philosophers solved the problem, and in this way Von 
 Kleist's apparatus came to be known as the Leydeu-jar, 
 
THE CAGING OF THE LIGHTNING. 17 
 
 Subsequently the jar was constructed by Dr. Bevis in the 
 form shown in Fig. 2, which is that which it has ever since 
 had. In charging the jar, the outer coating, usually of tin- 
 foil, is connected with the earth ; 
 and the inner coating of the same 
 material, by means of the central 
 wire and knob, receives the sparks 
 from an electric machine. The 
 positive electricity from a glass 
 electrical machine, passing to the 
 inner coating, acts inductively 
 across the glass upon the outer Fig . 2 . 
 
 coating, and is supposed to at- 
 tract only its negative electricity, while the positive elec- 
 tricity there resident is repelled into the earth, with which 
 the outer coating is connected. In this way two opposite 
 and mutually attracting electricities are separated by the 
 glass. But if a path be provided by which these two 
 electricities can flow to one another, they will do so, and 
 the jar will be discharged. If the outer coating be grasped 
 with one hand, and the knuckle of the other hand be pre- 
 sented to the knob of the jar, the body will then form a 
 conducting path over which this flow can take place ; a 
 bright spark will pass between the knob and the knuckle, 
 with a sharp report ; and at the same moment a convulsive 
 "shock" will be communicated to the muscles of the 
 wrists, elbows, and shoulders. 
 
 In Von Kleist's apparatus, the water or mercury formed 
 the inner conducting coating, and his hand, grasping the 
 bottle, the outer coating which was thus connected to earth 
 through his body. When he touched the nail with his dis- 
 engaged hand, he completed the path between the inner 
 and outer coatings through his body, and thus received the 
 shock. 
 
18 THE AGE OF ELECTEIC1TY. 
 
 Scientists everywhere now began to investigate this 
 phenomenon. Graham caused a number of persons to lay 
 hold of the same metal plate, which was connected with 
 the outer coating of a charged Leyden-jar, and also to 
 grasp a rod by which the jar was discharged. The shock 
 divided itself equally among them. Abbe" Nollet procured 
 a detail of one hundred and eighty soldiers, stood them up 
 in a line, and sent shocks through the whole battalion, a 
 significant commentary on the strength of military disci- 
 pline, which could make ignorant men face manifestations 
 which disconcerted and agitated the philosophers them- 
 selves. But the monks outdid the soldiers : seven hundred 
 and fifty Carthusians formed a line 5,400 feet long, an iron 
 wire extending between each two persons ; when the abb6 
 caused the discharge, the entire company of ecclesiastics 
 "gave a sudden spring, and sustained the shock at the 
 same instant." Apparatus was constructed so that large 
 quantities of electricity could be accumulated, and results 
 hitherto unexpected were obtained. Dr. Watson made 
 experiments to discover through how great a distance the 
 electric shock could be propagated, and in 1747 conveyed 
 it across the River Thames at Westminster Bridge, and 
 finally concluded that " the velocity of the electric matter 
 in passing through a wire 12,276 feet in length is instan- 
 taneous." Other investigators killed small animals and 
 birds with powerful discharges from the Leyden-jar. 
 
 In 1745 Mr. Peter Collinson of the Royal Society sent 
 a jar to the Library Society of Philadelphia, with instruc- 
 tions how to use it. This fell into the hands of Benjamin 
 Franklin, who at once began a series of electrical ex- 
 periments. On March 28, 1747, Franklin began his 
 famous letters to Collinson, regarding which Priestley 
 says, " Nothing was ever written upon the subject of 
 electricity which was more generally read and admired in 
 
THE CAGING OF THE LIGHTNING. 19 
 
 all parts of Europe. It is not easy to say whether we 
 are most pleased with the simplicity and perspicuity with 
 which they are written, the modesty with which the author 
 proposes every hypothesis of his own, or the noble frank- 
 ness with which he relates his mistakes when they are 
 corrected by subsequent experiments." In these letters 
 he propounded the single-fluid theory of electricity, and 
 referred all electric phenomena to its accumulation in 
 bodies in quantities more than their natural share, or to 
 its being withdrawn from them so as to leave them minus 
 their proper portion. A body having more than its natural 
 quantity, he regarded as electrified positively, or plus; and 
 one having less, as electrified negatively or minus. On 
 this theory he explained the action of the Leyden-jar as 
 it has already been explained above ; and he conceived 
 the idea of connecting together a number of Leyden-jars, 
 the outer coating of each being connected to the outer 
 coating of the next succeeding one, and thus produced 
 his famous "cascade battery," in which the strength 
 of the shock was enormously increased. He also dis- 
 covered that the connecting coatings of the Le} 7 den-jar 
 "served only, like the armature of the loadstone, to unite 
 the forces of the several parts, and bring them at once to 
 any point desired ; ' ' and that the electricity in fact existed 
 only upon the glass. One of Franklin's letters to Collin- 
 son is celebrated for his quaintly humorous proposition 
 of an ; ' electric feast " to be held on the banks of the 
 Schuylkill. Whether this ever occurred, is questionable ; 
 but Franklin's description of it is well worth quoting. 
 " The hot weather coming on," he says, " when electrical 
 experiments are not so agreeable, it is proposed to put 
 an end to them for this season, somewhat humorously, 
 in a party of pleasure on the banks of the Schuylkill. 
 Spirits, at the same time, are to be fired by a spark sent 
 
20 THE AGE OF ELECTEICITY. 
 
 from side to side through the river without any other con- 
 ductor than the water ; an experiment which we some time 
 since performed to the amazement of many. A turkey 
 is to be killed for our dinner by the electric shock, and 
 roasted by the electric jack before a fire kindled by the 
 electric bottle; when the healths of all the famous elec- 
 tricians of .England. Holland, France, and Germany are 
 to be drunk in electrified bumpers, under a discharge of 
 guns from the electrical battery." If Franklin's proposal 
 bordered on the absurd or grotesque, it proves how near 
 the ridiculous in thought may be to the sublime ; for at 
 that same period he was formulating the speculations 
 which ultimately culminated in one of the most audacious 
 yet most brilliantly successful experiments ever made by 
 man. More than forty years before, Wall had compared 
 the crackling from his rubbed amber to thunder and light- 
 ning ; Nollet in France had not long before quaintly 
 said, " If any one should take upon him to prove from a 
 well-connected comparison of phenomena, that thunder is 
 in the hands of Nature what electricity is in ours, and 
 that the wonders which we now exhibit at our pleasure 
 are little imitations of these great effects which frighten 
 us ; I avow that this idea, if it was well supported, would 
 give me a great deal of pleasure." Meanwhile the facts 
 derived from experiment were rapidly multiplying, which 
 showed the similarity between the powerful sparks of the 
 Leyden battery and the lightning flash. The exag- 
 gerated accounts of Musschenbroek and others who had 
 received the shocks went to prove that increase in force 
 or strength would cause death. Experiments upon birds 
 and small animals did produce death as sudden as that 
 due to the lightning stroke. Franklin himself was twice 
 struck senseless by shocks ; and he afterwards sent the 
 discharge of two large jars through six robust men, who 
 
THE CAGING OF THE LIGHTNING. 21 
 
 fell to the ground, and got up again without knowing 
 what had happened, neither feeling nor hearing the dis- 
 charge. 
 
 While all these facts convinced Franklin of the identity 
 of lightning and electricity, they demonstrated at the 
 same time to him the imminent danger which must attend 
 any experiment which would serve as proof. One scarcely 
 knows which to admire most, the lucid reasoning wherein 
 he states his convictions to Collinson, or the cool courage 
 with which he faced not only possible death, but the 
 ridicule of the world, which would be heaped upon his 
 memory in event of failure. The result would brand him 
 as a madman and a suicide, or raise him to the topmost 
 pinnacle of human fame. The account given by Dr. 
 Stuber of Philadelphia, an intimate personal friend of 
 Franklin, and published in one of the earliest editions of 
 the works of the great philosopher, is as follows : 
 
 "The plan which he had originally proposed was to 
 erect on some high tower, or other elevated place, a sen- 
 try-box, from which should rise a pointed iron rod, insu- 
 lated by being fixed in a cake of resin. Electrified clouds 
 passing over this would, he conceived, impart to it a 
 portion of their electricity, which would be rendered evi- 
 dent to the senses by sparks being emitted when a key, 
 a knuckle, or other conductor was presented to it. Phila- 
 delphia at this time offered no opportunity of trying an 
 experiment of this kind. Whilst Franklin was waiting 
 for the erection of a spire, it occurred to him that he 
 might have more ready access to the region of clouds by 
 means of a common kite. He prepared one by attaching 
 two cross-sticks to a silk handkerchief, which would not 
 suffer so much from the rain as paper. To his upright 
 stick was fixed an iron point. The string was, as usual, 
 of hemp, except the lower end which was silk. Where 
 
22 THE AGE OF ELECTEICITY. 
 
 the hempen string terminated, a key was fastened. With 
 this apparatus, on the appearance of a thunder-gust ap- 
 proaching, he went into the common, accompanied by his 
 son, to whom alone he communicated his intentions, well 
 knowing the ridicule which, too generally for the interest 
 of science, awaits unsuccessful experiments in philosophy. 
 He placed himself under a shed to avoid the rain. His 
 kite was raised. A thunder-cloud passed over it. No 
 signs of electricity appeared. He almost despaired of 
 success, when suddenly he observed the loose fibres of his 
 string move toward an erect position. He now pressed 
 his knuckle to the key, and received a strong spark. How 
 exquisite must his sensations have been at this moment ! 
 On his experiment depended the fate of his theory. 
 Doubt and despair had begun to prevail, when the fact 
 was ascertained in so clear a manner, that even the most 
 incredulous could no longer withhold their assent. Re- 
 peated sparks were drawn from the key, a phial was 
 charged, a shock given, and all the experiments made 
 which are usually performed with electricity." And thus 
 the identity of lightning and electricity was proved. 
 
 Meanwhile, Franklin, in his letters to Collinson, had 
 already outlined his proposed experiments. Collinson 
 offered the letters to the Royal Society for publication, 
 but encountered a contemptuous refusal. The suggestion 
 that pointed rods would "probably draw the electrical 
 fire silently out of a cloud before it came nigh enough to 
 strike, and thereby secure us from that most sudden and 
 terrible mischief," was received with open derision. But 
 some years later the Royal Society elected Franklin an 
 honorary member, and decreed him their highest honor, 
 the Copley medal. Franklin's letters were, however, pub- 
 lished by Dr. Fothergitl. They went through five editions 
 in London, and attracted the attention of all Europe. 
 
THE CAGING OF THE LIGHTNING. 23 
 
 An incorrect French translation falling into the hands of 
 Buffon, that celebrated philosopher repeated the experi- 
 ments successfully, and commended them to his friend M. 
 d'Alibard. A report of the wonderful results reached 
 Louis XV., then King of France; and at his request 
 further experiments were undertaken. The notice of the 
 king now acted as a stimulus to the French scientists ; and 
 three of them, Buffon, De Lor, and D'Alibard, erected ap- 
 paratus for attracting the lightning at different localities. 
 It is a curious fact, that despite the eagerness of these 
 philosophers, each to outstrip the other in being the first 
 to obtain actual results, disappointment awaited them all. 
 D'Alibard employed an old soldier, named Coiffier, to 
 help build his apparatus, and subsequently to watch it. It 
 so happened that the long-expected thunder-storm came 
 along during D'Alibard's absence ; and Coiffier, who had 
 no idea of the danger of receiving the spark, determined 
 to experiment on his own account. Accordingly, he 
 mounted the insulated stool which had been prepared, 
 and presented a wire to D'Alibard's rod, obtaining a fine 
 spark, and then another. He at once called all his 
 neighbors, and some one ran in search of the parish 
 priest. The latter was seen making his way to the ap- 
 paratus in such undignified haste, that it was immediately 
 surmised that the daring Coiffier had fallen a victim to 
 his bold experiment ; and accordingly the good father 
 found himself the leader of a miscellaneous mob of vil- 
 lagers. Regardless of the pouring rain and hail, the 
 crowd surrounded the machine, and there in open-mouthed 
 wonder watched the priest himself draw sparks from the 
 rod. Both the clergyman and the soldier managed to get 
 lightly struck, so lightly, that, in their absorbed atten- 
 tion to the sparks, they scarcely noticed the occurrence 
 until afterwards, when each, feeling stinging pains in his 
 
24 THE AGE OF ELECTRICITY. 
 
 fore-arm, searched for the cause, and found bright red 
 stripes on the flesh just as if a few sound lashes had 
 been administered. It is very likely that the villagers 
 saw no good in these supernatural manifestations ; and 
 when they all perceived about the persons of the priest 
 and his companion the marked odor of the ozone gener- 
 ated, somewhat sulphurous in character, they were con- 
 firmed in their idea that the powers of the nether world 
 had been invoked. To Coiffier, however, remained the 
 honor of being the first to receive the spark. This was 
 on May 10, 1752, about a month before Franklin's fa- 
 mous experiment ; and, in many French works, priority as 
 the original discoverer is for this reason patriotically 
 claimed for D'Alibard. There is no doubt, however, that 
 D'Alibard obtained his instructions from Franklin's let- 
 ters, as he himself afterwards frankly admitted that he 
 merely followed the tiack which Franklin had pointed 
 out. 
 
 The European philosophers now remitted experiments 
 to find out how strong the shock of the Leyden-jar was, 
 and turned with increased enthusiasm to measuring the 
 power of the lightning stroke. And then the caged light- 
 ning found its first victim. In the engraving of the old 
 electrical machine, Fig. 1, there are shown a number of 
 threads which hang from a curved support over the glass 
 globe, and which are attracted by the globe when excited 
 so as to assume an inclined position. Professor Richmann 
 of St. Petersburg had constructed an " electrical gnomon " 
 on this same principle ; his idea being, to measure the 
 strength of the lightning discharge by observing the angle 
 of inclination assumed by a suspended thread electrified 
 thereby. He arranged on the roof of his house an iron 
 rod which he insulated from the adjacent part of the build- 
 ing ; and to this rod he fastened a chain which led down 
 
THE CAGING OF THE LIGHTNING. 25 
 
 into his laboratory, and was connected to an insulated 
 support from which hung his thread, the end of which 
 extended over a dial. Richmaim had invited an engraver 
 named Solokow to witness the working of the apparatus ; 
 and as a thunder-storm gathered, the two men eagerly 
 watched the movement of the thread. Suddenly a peal of 
 thunder of terrific loudness was heard. Richmaim bent 
 forward to observe his thread more closely ; and ' ' as he 
 stood in that posture, a great white and bluish fire ap- 
 peared between the rod of the electrometer and his head. 
 At the same time a sort of steam or vapor arose, which 
 entirely benumbed the engraver, and made him sink to the 
 ground." The apparatus was torn to pieces, the doors of 
 the room thrown down, and the house violently shaken. 
 Richmaim's wife, running into the room, found her hus- 
 band sitting on a chest which happened to be immediately 
 behind him. He was stone dead, bearing no mark beyond 
 a red spot on his forehead. His shoe was ripped open 
 and his waistcoat singed, showing that the deadly current 
 had passed through his body. Solokow was removed 
 insensible, but subsequently recovered. The luckless ex- 
 perimenter had forgotten to provide an earth connection 
 whereby the charge might have passed harmlessly to the 
 ground. In the absence of this, the enormous electro- 
 motive force of the current was sufficient to enable it to 
 leap over the interval of air between the electrometer and 
 Richmann's head, and so to be led through his body. 
 
 Of course there were not wanting emotional people to 
 draw all sorts of warnings from Richmann's fate. Frank- 
 lin's proposition to erect lightning-rods which would 
 convey the lightning to the ground, and so protect the 
 buildings to which they were attached, found abundant 
 opponents, who agreed with Abbe Nollet, that it was " as 
 impious to ward off Heaven's lightnings as for a child to 
 
26 THE AGE OF ELECTRICITY. 
 
 ward off the chastening rod of its father." Others, whose 
 religious scruples did not carry them quite so far, went to 
 the opposite extreme, and concluded that if there was any 
 impiety^ about lightning-rods, it lay in the fact that they 
 invited the u chastening rod/' and that it was madness 
 to u tempt Providence " in any such way. Nevertheless, 
 public opinion became settled, that whether lightning-rods 
 were impious because they opposed the decree of Provi- 
 dence, or suicidal because they induced Providence to 
 make decrees, the fact remained that they did .protect 
 buildings ; and as long as they did that, the theological 
 questions raised might be left to time for settlement. 
 Then the philosophers raised a new controversy as to 
 whether the conductors should be blunt or pointed ; Frank- 
 lin, Cavendish, and Watson advocating points, and Wilson 
 blunt ends. That wise monarch whose scientific acumen 
 stood nonplussed before the problem of how apples are 
 got into dumplings, graciously considered the question, be- 
 cause it affected his own royal abode, Buckingham Palace, 
 and, after much balancing of the pros and cons, reached 
 the sage conclusion that the pointed conductors ' ' were a 
 republican device calculated to injure his Majesty," 
 whereupon he ordered them removed from the palace, and 
 ball conductors substituted. The same public opinion 
 which ran counter to him when he tried rather fruitlessly 
 to repress, some years later, numerous other republican de- 
 vices calculated to injure his Majesty on the opposite side 
 of the Atlantic, asserted itself here. "The king's chan- 
 ging his pointed conductors for blunt ones," said Franklin, 
 " is a small matter to me. If I had a wish about them, 
 it would be that he would reject them altogether as in- 
 effectual. For it is only since he thought himself and 
 his family safe from the thunder of heaven, that he has 
 dared to use his own thunder in destroying his innocent 
 
THE CAGING OF THE LIGHTNING. 27 
 
 subjects." The logic of experiment, however, showed 
 the advantage of pointed conductors ; and people persisted 
 then in preferring them, as they have clone ever since. 
 
 We have now traced, though very briefly, the progress 
 of knowledge of electricity, from the germ of the science 
 which lay hidden for thousands of years in amber, like 
 the insects so often found in that substance, and yet 
 unlike them, for it possessed immortality, up to the first 
 practical application of that knowledge to human use and 
 benefit. The lightning had been caged. The mighty 
 force, which since the creation of mankind had aroused 
 but feelings of awe and terror, could now be confined and 
 examined, or diverted at will from its path of destruction. 
 The wise men of the eighteenth century had captured the 
 electrical Pegasus : it remained for the wiser men of 
 the nineteenth to yoke him to the plough. 
 
28 THE AGE OF ELECTRICITY. 
 
 CHAPTER IV. 
 
 ELECTRICITY IN HARNESS. 
 
 THE death of Richmann, and the potent effects of even 
 small discharges of electricity upon the human body, 
 caused, as may be well imagined, much speculation as to 
 the part which an electric discharge could be made to 
 take in curing the ills that flesh is heir to. The electric 
 machine was of course the only available means of artifi- 
 cially producing the current ; and the modern practitioner 
 can easily figure to himself the unhappy experiences of 
 patients who were subjected to its unregulated and power- 
 ful discharges. 
 
 Between those who sought to use electricity as a nos- 
 trum for the cure of all ailments, and those who investi- 
 gated its action physiologically, there was a wide difference. 
 Through the latter class of investigators many discoveries 
 of great value were made, and, finally, one of the utmost 
 importance. Beccaria and others meanwhile observed the 
 effects of the electric discharge upon the muscles, and had 
 noted that those of the leg of a cock were strongly con- 
 tracted when a shock passed through them. 
 
 In 1786 Luigi Galvani, medical lecturer at the Univer- 
 sity of Bologna, while engaged upon investigations similar 
 to those of Beccaria, prepared some frogs' legs, with the 
 object of observing whether any effect would be produced 
 upon them by the electricity of the atmosphere. To this 
 
ELECTRICITY IN HARNESS. 29 
 
 end, after carefully skinning the legs, he hung them upon 
 a hook which protruded from the railing of his balcony. 
 lie stood watching them for some time, but no results 
 showed themselves. Finally, disappointed, he lifted them 
 from the hook ; and then, while in the act of so doing, 
 he noticed to his astonishment that the very effects, the 
 peculiar muscular contractions, which he expected the 
 atmospheric electricity would cause, were taking place. 
 As it was evident that the surrounding atmosphere had 
 no part in the phenomenon, he at once sought for the 
 concealed cause ; and finally he found that the limbs con- 
 tracted whenever the iron railing touched their moist sur- 
 face, their contact meanwhile with the hook, which was of 
 copper, being still maintained. Conjecturing that the hook 
 and railing, of course,, as such, had nothing to do with the 
 matter, he made a metallic arc, formed of two pieces of 
 iron and copper ; and with this he soon found that it was 
 necessary simply to bring one metal into contact with a 
 nerve or with the end of the spine, and the other into 
 contact with a muscle of the leg, to produce immediately 
 muscular contractions. 
 
 Galvani came to the conclusion that the electricity of 
 which he had observed the effects resided in the muscles, 
 which received their supply from the nerves and blood ; 
 and in 1791 he published his celebrated work on the sub- 
 ject. If people believed that electricity was a valuable 
 remedy before this, they now began enthusiastically to 
 accept the shock as a universal panacea. Du Bois Rey- 
 mond says, that wherever frogs were to be found, and 
 where two different kinds of metal could be procured, 
 everybody was anxious to see the mangled limbs of frogs 
 brought to life in this wonderful way. The physiologists 
 believed that at length they -could realize their visions of 
 a vital power. The physicians whom Galvani had some- 
 
30 THE AGE OF ELECTRICITY. 
 
 what thoughtlessly led on with attempts to explain all 
 kinds of nervous diseases, as sciatica, tetanus, and epi- 
 lepsy, began to believe that no cure was impossible. 
 
 It is a curious circumstance in matters of invention, 
 that discoveries of the most important nature have been 
 frequently made by people, who, being unable to realize 
 their importance, have passed them by, leaving them to be 
 made over again by others. The electrical effects of dis- 
 similar metals upon animal substance had been observed 
 by Sulzer, a German investigator, some twenty-three years 
 before Galvani made his experiments. Sulzer applied the 
 two metals, one above and the other below the tongue, 
 and then on bringing them into contact perceived the 
 peculiar sour taste. He ascribed this sensation to some 
 vibratory motion, excited by the contact of the metals, 
 and communicated to the nerves of the tongue ; and then, 
 content with this loose and fanciful explanation, he an- 
 nounced the fact in 17G7, in a work entitled "The General 
 Theory of Pleasures," where it remained wholly unnoticed 
 until long after Galvani's discovery had aroused the atten- 
 tion of the world. Galvani's discovery was also to some 
 extent anticipated by Cotugno, a Neapolitan professor of 
 anatomy, who in 1786 published the curious statement 
 that one of his pupils, feeling a sharp pain in the lower 
 part of his leg, clapped his hand upon the spot, and 'cap- 
 tured a mouse which had bit him. The little animal, after 
 being killed, was made a subject for dissection. During 
 this proceeding the pupil " accidentally touched the dia- 
 phragmatic nerve with his scalpel, and then received a 
 shock strong enough to make him snatch away his hand." 
 Cotugno's report attracted considerable attention through- 
 out Italy, and, it is said, caused further investigations to 
 be made by Vassalli, who formulated the odd theory that 
 nature accumulates electricity in certain parts of animals, 
 
ELECTRICITY IN HARNESS. 31 
 
 and that they can draw upon this supply at will. It is 
 quite certain, however, that the work of both Cotugno and 
 Sulzer had been forgotten when Galvani's discovery was 
 made ; and the meagre suggestions published by them 
 detract nothing from the honor due the Bolognese philoso- 
 pher. But Galvani reaped neither profit nor glory in his 
 lifetime. The Cisalpine Republic ordered him to take a 
 certain oath entirely contrary to his political and religious 
 convictions, and, on his refusal, stripped him of his posi- 
 tions and titles. Thus reduced to poverty, he retired to 
 his brother's house, and, it is said, fell into a state of 
 lethargy, whence the tardy retraction by the Government 
 of its unjust decree failed to arouse him, and in which he 
 died. Only six years ago, Bologna erected a statue to his 
 memory, in one of her principal squares, and so made that 
 usual reparation of the public to unappreciated genius. 
 
 Some two years after Galvani's results and theories had 
 been published, Alessandro Volta, a professor in the Uni- 
 versity of Pavia, strongly opposed his deductions. 
 
 Volta was then one of the foremost electricians of the 
 day. He had invented the electrophorus and the electri- 
 cal condenser by which small charges of electricity were 
 accumulated. Volta maintained that Galvani's pretended 
 animal electricity was developed simply by 
 the contact of two different metals ; and 
 thus began a controversy which lasted long 
 after Galvani's death in 1798. Its outcome 
 was the invention of the voltaic pile, which 
 was contrived by Volta as a means of prov- 
 ing his theory. He soldered together two Fig. 3. Voita's 
 disks, one of copper (c) and one of zinc (z) . 
 Between these he placed circular pieces of woollen cloth 
 (/i), moistened with a solution of common salt or diluted 
 sulphuric acid. Several sets of disks thus arranged were 
 
32 THE AGE OF ELECTRICITY. 
 
 placed one above the other ; each pair of disks in the pile 
 was separated from the next pair by a moist conductor. 
 A pile composed of a number of such pairs of disks will 
 produce electricity enough to give quite a perceptible 
 shock, if the top and bottom disk, or wires connected 
 with them, be touched simultaneously with the moist 
 fingers. 
 
 Volta's next step was the invention of the cup form of 
 battery. He arranged a number of cups, filled either with 
 brine or dilute acid, into which dipped a number of com- 
 pound strips, half zinc and half copper ; the zinc portion 
 of one strip dipping into one cup, while the copper portion 
 dipped into the other. In each cup, therefore, there was 
 a copper plate and a zinc plate, separated by a conducting 
 fluid ; and this is in substance the voltaic cell of to-day. 
 
 In discussing the sources of electricity, we shall advert 
 to the theory and operation of this great invention which 
 marks the beginning of a new era in the progress of elec- 
 trical science. Even as Von Kleist and Franklin may be 
 said to have caged the lightning, so Volta tamed it. He 
 made electricity manageable. He reduced the infinite ra- 
 pidity of the lightning stroke to the comparatively slow 
 but enormously powerful current, which in the future was 
 destined to carry men's words from one end of the world 
 to the other, and to produce the dazzling light inferior 
 only to the solar ray ; and the recognition accorded him 
 might well have satisfied his highest ambition. In marked 
 contrast to the fate of the broken-hearted Galvani, it was 
 Volta's fortune to be called to Paris by Napoleon, then 
 nearing the zenith of his glory, in order to explain his 
 discoveries before the assembled philosophers of France. 
 The First Consul himself presided ; and when Volta's 
 demonstration was completed, it was Napoleon who pro- 
 posed that the rules of the Academy should be suspended, 
 
ELECTRICITY IN HARNESS, 33 
 
 and that the gold medal of the Institute immediately 
 should be awarded Volta in testimony of the gratitude of 
 the French nation. On the same day two thousand crowns 
 were sent to Volta from the national treasury ; and, as a 
 final and lasting honor, Napoleon founded the award of 
 an annual medal of the value of three thousand francs 
 for the best experiment in electricity, and a prize of sixty 
 thousand francs to him who should give electricity or 
 magnetism, by his researches, an impulse comparable to 
 that which it received from the discoveries of Franklin 
 and Volta. 
 
 And yet, singularly enough, we speak almost instinc- 
 tively of the galvanic, seldom of the voltaic, cell, as 
 if posterity had been guided by sympathy for the unfor- 
 tunate, rather than by a sense of justice to the favored, 
 discoverer. Such words as " galvanize" and "galvanic," 
 possessing even a figurative meaning, are in every-day 
 speech. Volta's name is embalmed only in the techni- 
 calities of the science. 
 
 Among those who had studied deepest into the phenom- 
 ena of galvanic electricity was Hans Christian Oersted, a 
 Danish physicist, and professor of physics in the University 
 of Copenhagen. Oersted's researches led him to suspect 
 the identity of magnetism and electricity, but for a long- 
 time no means of experimentally proving the fact revealed 
 itself. The expedient had been tried of placing the two 
 poles of a battery, as highly charged as possible, in a 
 parallel line with the poles of a magnetic needle, without 
 results. In one of the reports of the Smithsonian Insti- 
 tute, the story of his discovery is thus graphically told : 
 "Fortune, it might be said, ceased to be blind at the 
 moment when to Oersted was allotted the privilege of first 
 divining that it was not electricity in repose accumulated 
 at the two poles of a charged battery, but electricity in 
 
34 THE AGE OF ELECTRICITY. 
 
 movement along the conductor by which one of the poles 
 is discharged into the other, which would exert an action 
 on the magnetic needle. While thinking of this (it was 
 during the animation of a lecture before the assembled 
 pupils), Oersted announces to them what he is about to 
 try : he takes a magnetic needle, places it near the electric 
 battery, waits till the needle has arrived at a state of rest ; 
 then seizing the conjunctive wire traversed by the current 
 of the battery, he places it above the magnetic needle, 
 carefully avoiding any manner of collision. The needle 
 everyone plainly sees it the needle is at once in motion. 
 The question is resolved. Oersted has crowned, by a 
 great discovery, the labors of his whole precious life." 
 
 On July 21, 1820, the discovery was announced, that a 
 galvanic current passing through a wire placed horizontally 
 above and parallel to an ordinary compass-needle, will 
 cause that needle to sway on its axis to the east or west, 
 according to the direction of the current through the wire. 
 Oersted's discovery may be said to have pointed the way 
 to the great applications of electricity to human use ; for 
 it showed that energy in the form of electricity could be 
 converted into energy in the form of mechanical motion. 
 
 The discovery of the electro-magnet lay but a step be- 
 yond, a short step, and it was quickly taken. And 
 then opened the era of electricity at work, the era when 
 the discoverer too frequently finds his sole reward in the 
 applause of his compeers, and when the world lavishes its 
 honors and wealth upon the fortunate inventor. This is 
 the era in which we live. 
 
THE GALVANIC BATTERY. 35 
 
 CHAPTER V. 
 
 THE GALVANIC BATTERY, AND THE CONVERSION OP 
 CHEMICAL ENERGY INTO ELECTRICAL ENERGY. 
 
 WHAT is electricity? No one knows. It seems to be 
 one manifestation of the energy which fills the universe, 
 and which appears in a variety of other forms, such as 
 heat, light, magnetism, chemical affinity, mechanical 
 motion, etc. For the purposes of convenient thinking, it 
 is well to consider the electrical current as a fluid, because 
 it apparently follows certain laws of fluids. 
 
 In its usual form, the galvanic cell consists of any two 
 dissimilar conducting substances subjected to the action 
 of a third substance capable of chemically attacking but 
 one of them, or of attacking one. in less degree than the 
 other. There is a containing vessel, in which is placed a 
 liquid called the electrolyte ; and in this liquid are plunged 
 the two conducting substances, usually in solid form, which 
 are called the elements, one of which is attackable by the 
 liquid, and the other non-attackable or less attackable. 
 When the two conducting bodies are connected by a wire 
 of conducting material, then an electrical current will cir- 
 culate, and will proceed from the body that is attacked 
 to the body that is not attacked, by way of the liquid, 
 and thence back to the attacked body by the wire. The 
 path thus traversed by the Current is its circuit. If the 
 circuit is anywhere interrupted, the current stops. 
 
36 
 
 THE AGE OF ELECTRICITY. 
 
 Fig. 4. 
 
 The diagram (Fig. 4) will make this quite clear. Here 
 the wires are attached to the two bodies, immersed in a 
 liquid which will chemically attack one of them. The 
 current then circulates in the direction 
 of the arrow, from A the attacked body 
 to B the non-attacked body, and thence 
 back through the connecting wire. 
 
 Almost every branch of science now- 
 adays has its own language, made up 
 of its technical terms, which in time 
 become absorbed into general speech. 
 This is fast becoming the case with the 
 language of electricity. Amperes and 
 volts and ohms are no longer possessed 
 of meaning only to the initiated, but are taking their place 
 among such every-day standards as pounds and gallons 
 and inches. Although this little work makes no pretence 
 to be a treatise, it is believed that a plain statement of 
 some significations will be of service to the reader as a 
 help to a clearer comprehension of the applications of 
 electricity hereafter described. 
 
 If we run or walk, or saw wood or pump water, we are 
 conscious after a time of having exerted ourselves. We 
 have apparently expended certain of our bodily energy 
 in accomplishing something against an opposing force. 
 That is to say, we have done work. Before beginning 
 the task, we were conscious of an ability to undertake it. 
 At the end of the task, comes a sense of fatigue which 
 may be sufficiently strong to demonstrate our inability to 
 repeat the same labor until a period of rest and recupera- 
 tion intervenes. At the outset, therefore, we possess a 
 power, ability, or potential, to exert so much energy. 
 After the exertion, we have not this power, because we 
 have expended the energy in the form of bodily motions, 
 
THE GALVANIC BATTERY. 37 
 
 against the opposing forces of friction or gravity. As 
 we have already stated, electricity is simply one form of 
 energy, and when it is exerted against opposition it does 
 work. But, like ourselves, in order to do work, it must 
 acquire a certain condition. 
 
 If an athlete is about to enter into an exhausting con- 
 test, he trains himself to that end ; and by dint of exercise, 
 judicious fare, etc., he brings his muscles and other 
 organs into a condition competent to the great exertion 
 before him. His potential, his capacity to do the work, is 
 thus enhanced. And so in general, any sort of education, 
 whether mental or physical, simply has for its object the 
 raising of the potential of the brain or the muscles, to 
 accomplish certain ends. We have constantly before us 
 examples of natural forces under varying potential. A 
 hot iron must acquire a high temperature before it will burn 
 inflammable bodies, a still higher one that it may be welded, 
 and still higher that it may melt. Water must be carried 
 to a high elevation before, by its fall, it can turn a wheel. 
 The steam in a boiler must reach a certain pressure before 
 it can move the engine piston. And so also electricity, 
 before it can do work, must reach a certain condition, 
 analogous in some degree to temperature and pressure. 
 
 Suppose we had a tank of water at A (Fig. 5), elevated 
 above the ground. If we connect a pipe B to ife, the 
 water will run down. What determines the flow? Simply 
 the elevation of the water. Again, take two tanks, one 
 not as high as the other, but both higher than the ground. 
 The water of course flows from the highest one J., to the 
 lower one B, and so to the earth. The water flows from 
 A to B simply because of their difference in height ; 
 and this difference determines the flow of water from 
 one tank to the other, or from either tank to the 
 ground. Therefore we say of water, that its ability to 
 
38 
 
 THE AGE OF ELECTRICITY. 
 
 do work by exerting pressure (its potential) depends on 
 its elevation. 
 
 So of electricity. A body may be electrified up to a cer- 
 tain potential. For convenience the earth is considered as 
 of zero or no potential. Then, if by any material capable 
 of conducting electricity we connect the electrified body to 
 the earth, the conditions will be the same as in the case of 
 
 Fig. 5. 
 
 the tank of water (Fig. 5) : the electricity will flow from 
 the electrified body to the earth. Again, if a body electri- 
 fied to a high potential communicate with one electrified 
 to a low potential, then the electricity (as in the case of 
 the water between the tanks A and B in Fig. 5) will flow 
 from the body at high potential to the body at low potential. 
 There is a force which moves the electricity from one 
 
THE GALVANIC BATTERY. 39 
 
 point to another, analogous to the force of gravity which 
 makes water run down hill. That force is commonly 
 called electro-motive force, or, as it is sometimes termed, 
 electrical pressure. 
 
 We have said that work is energy exerted against an 
 opposing force, or, in other words, against a resistance. 
 This resistance, in the case of water, may be due to fric- 
 tion against the sides of a pipe, or to the opposition to 
 the flow offered by an interposed water-wheel which drives 
 machinery. Electricity in motion in the same way does 
 work, and that which opposes its motion is technically 
 called the resistance. 
 
 Certain bodies, as glass and India rubber, offer very 
 great resistance to the electric flow : these are known as 
 insulators. Others offer very little resistance, and these 
 are termed conductors. 
 
 In order to maintain a constant flow or current of elec- 
 tricity, there must, as we have seen, be a difference of 
 potential between two points between which a conductor 
 extends ; and this difference of potential must be kept up, 
 otherwise the current would simply equalize itself at both 
 points, just as water will rise to its own level and then 
 cease flowing. The current is urged along the conductor 
 by its electro-motive force, and it is opposed by whatever 
 resistance lies in its path. The greater the electro-motive 
 force in proportion to the resistance, the greater will be 
 the strength of the current ; or, to use the water analogy 
 again, the more gallons of water (for example) will flow 
 through the pipe in a given time. Conversely, the greater 
 the resistance, the more opposition the current will meet, 
 and hence the weaker it will be. 
 
 This simple relation of electro-motive force and resist- 
 ance is the fundamental law of electricity in motion, discov- 
 ered by Professor Ohm, a distinguished German physicist. 
 
40 THE AGE OF ELECTRICITY. 
 
 Consequently there ar,e three things about any electrical 
 current to be known : namely, its electro-motive force, or 
 pressure ; the resistance which it encounters ; and the 
 strength of the current, which depends upon these. 
 
 We measure steam or water pressure in pounds per 
 square inch, heat by thermometric degrees, distances by 
 feet and inches, and so on. Electro-motive force is meas- 
 ured in volts. A volt is very nearly the pressure yielded 
 by a certain standard galvanic cell, usually the Daniell 
 hereafter described. The term has also a very accurate 
 mathematical signification, which need not be discussed 
 here. 
 
 Resistance is measured in ohms. A column of mercury 
 one millimetre in cross section, and 106.2 centimetres in 
 length, has a resistance of one ohm ; but, for convenience, 
 it may be remembered that ordinary iron telegraph-wire 
 has a resistance of about 13 ohms to a mile. 
 
 An electrical current having an electro-motive force of 
 one volt, traversing a resistance of one ohm, is said to 
 have a strength of one ampere. 
 
 Here we diverge a little from the water analogy. If 
 we referred to water, we should say that water under so 
 many pounds pressure per inch, going through a pipe of 
 a certain diameter, is delivered at the rate of so many 
 gallons (for example) per minute. If we had some one 
 word which meant "gallons per minute," that would cor- 
 respond to ampere. When a current of one ampere 
 strength flows for one second, the quantity of electricity 
 delivered is called one coulomb. A current of the strength 
 of one-tenth ampere will not yield a quantity of electricity 
 equal to a coulomb until it has flowed ten seconds. 
 
 To recapitulate in briefer terms : Electro-motive force 
 means electrical pressure. Resistance has its obvious 
 meaning. Electro-motive force is not measured in pounds 
 
THE GALVANIC BATTERY. 41 
 
 per square inch like steam or water pressure, but in volts ; 
 and a volt is the pressure given by one standard cell. 
 
 Resistance is measured in ohms, and an ohm answers to 
 the resistance offered by four hundred and sixty feet of 
 ordinary telegraph-wire, approximately. Strength of cur- 
 rent is measured in amperes. Speaking of a water-wheel, 
 we say we need a current flowing at the rate of so many 
 gallons per minute to drive it. Speaking of an electric 
 lamp, we say we need a current of from one to fifty am- 
 peres to keep it glowing. The term "coulomb" is far 
 less employed in practice ; but it may be in the end most 
 familiar of all, for when the electric light comes into use 
 in dwellings, we shall pay for our electrical supply at so 
 much per thousand coulombs, for example, as we now pay 
 for gas at so much per thousand cubic feet. 
 
 To return now to the galvanic battery : It is not neces- 
 sary here to review the various theories suggested to 
 account for its behavior. These are all in the regular 
 treatises ; and whether the current be due to contact of 
 dissimilar substances, or to chemical action in the cell, 
 was a subject warmly discussed by the grandfathers of the 
 present generation. It is better for present purposes to 
 take the facts as we find them, and look upon the cell in 
 the light of what we see happening in it ; and, of these 
 happenings, the principal ones necessarily attend the de- 
 velopment of the current, and essential thereto is the 
 chemical action on one of the bodies, or so-called ele- 
 ments, therein. In fact, any chemical re-action which 
 occurs between conducting substances may be utilized to 
 generate electric currents. The chemical affinity both sup- 
 plies and measures exactly the electro-motive force. 
 
 There are some very curious but important facts now to 
 be noted about galvanic cells and their currents. The size 
 of the cell has nothing to do with the electrical pressure 
 
42 THE AGE OF ELECTRICITY. 
 
 yielded, the electro-motive force. A cell the size of 
 a percussion-cap will give just as high an electro-motive 
 force as a cell as big as the distributing reservoir in New- 
 York City. Electro-motive force, as we have stated, de- 
 pends on difference of potential ; difference of potential 
 exists in all dissimilar electrified bodies. Whether they 
 are large bodies or small ones, is beside the question ; just 
 as the fact that the pressure of water, due to its flow from 
 a reservoir to a plain beneath, is not influenced at all by 
 the area of the reservoir, but by the height of the water- 
 level above the plain. Water-pressure is the same per 
 foot of vertical height, no matter whether the column is at 
 its base a square inch or a square mile in area. The two 
 connecting bodies in the cell, when one is attackable and 
 attacked by the liquid, are at different potential : that of 
 the attacked body is the highest. The current then flows 
 to the non-attacked body through the conducting liquid, 
 and then back by the wire to the attacked body. The 
 constant chemical attack keeps the current flowing. A 
 current of water will flow from a high place to a low place 
 by gravity, but it will not flow up hill again unless work 
 is done to force it up. So, in a cell, the current will flow 
 from high potential to low potential, but not back again. 
 Work is required to send it back, and this the chemical 
 action supplies. 
 
 When we warm our houses, or drive a steam-engine, we 
 know that the amount of heat v;e get in the first case, or 
 power in the second, depends upon how much coal we 
 burn, other things being equal. The burning of coal is 
 simply the chemical action between the carbon of the fuel 
 and tne oxygen of the air. So, in a galvanic cell, we burn 
 the attacked element. As we convert coal into ashes of 
 no further use in the furnace, to produce heat, we convert 
 the zinc of the cell into another substance of no further 
 
THE GALVANIC BATTERY. 43 
 
 use in the cell to produce electricity. Through the steam 
 boiler and engine we can convert chemical action into 
 mechanical work, which we can apply to drive locomotives 
 or steamships or machinery. 
 
 The galvanic cell converts chemical action into elec- 
 tricity. The amount of work realized in one case, and 
 of electricity in the other, depends on the amount of fuel, 
 whether coal or zinc, consumed. If, then, in the galvanic 
 cell we burn twice as much zinc in a given time, we 
 shall have a current twice as strong. We can do this 
 by making the attacked body in the cell larger, so as to 
 expose double the area to the attack. 
 
 Hence it appears, that, while the size of the bodies in 
 the cell has no bearing on the pressure of the current, 
 it has a very material bearing on the strength of it. It 
 is, as we have said, so far as the pressure is concerned, 
 immaterial whether two water columns of the same height 
 press on bases of a square inch or a square mile in 
 area ; but the strength of the two currents, the gallons 
 flowing down per minute, will be enormously different. 
 Consequently, when we want high-pressure electricity, 
 we put into the cell bodies which are, or will be, of widely 
 different potential ; we look to the nature of the bodies. 
 When we want great strength of current, we look to their 
 dimensions. 
 
 In practice, however, we do not make huge cells, chiefly 
 because of their cumbrousness and difficulty to handle. 
 We can increase either the electro-motive force, or the 
 strength of the current, by using several cells of con- 
 venient size, and connecting them together differently. 
 Thus, in Fig. 6, each cell is supposed to give an electro- 
 motive force of one volt. If we connect the wire of the 
 attacked element in one cell to the unattacked element in 
 the next, and so on, we shall add together the several 
 
44 
 
 THE AGE OF ELECTRICITY. 
 
 electro-motive forces of each, and obtain an aggregate 
 pressure of four volts, while the strength of the current 
 
 Fig. 6. 
 
 will remain the same as that of one cell. If, however, we 
 connect all the attacked elements together by one wire, 
 
 Fig. 7. 
 
 and all the non-attacked elements together by another, as 
 in Fig. 7, then we shall really have quadrupled the size 
 of the elements ; and we shall have a 
 current four times as strong, while its 
 pressure will remain at one volt. 
 
 Take the water analogy again. Sup- 
 pose we start with a tank of water at the 
 level marked 1 in Fig. 8. Then the water 
 will flow out with a certain pressure, de- 
 pending on the elevation of the tank. So 
 in a given cell the current will flow out 
 with a given electro-motive force, depend- 
 ent on the materials of the cell. Let us 
 now elevate the tank to position 2, then 
 we have doubled the water pressure ; if 
 
 Fig. 8. 
 
 we carry it to the position 3, still higher, we may make 
 the pressure three times, and if to position 4, four times, 
 
THE GALVANIC BATTERY. 
 
 45 
 
 as great. We do the same thing electrically by adding 
 cells as shown in Fig. 6. The quantity of water or of 
 electricity yielded remains the same, but its pressure in- 
 creases. Suppose, however, that we start again with 
 our tank of water, which, however, contains say but ten 
 gallons, which it will discharge completely in a minute. 
 If we place beside it three other tanks of equal capacity, 
 and at the same elevation, each one will discharge ten 
 gallons a minute, or all together forty gallons a minute. 
 This is the parallel case to that of connecting the cells 
 as in Fig. 9. The pressure of water or electricity re- 
 
 Fig. 9. 
 
 mains the same ; but more water or electricity is dis- 
 charged in a given time. 
 
 Or, to put this in a more practical form, suppose we 
 have a pipe plenty large enough to carry all the water we 
 need, in a given time, to the top of a house, but find 
 the water will not come up. We increase the water press- 
 ure, and the water rises to the desired height. That is 
 the first case. Suppose, again, that we have a water- 
 wheel to turn, but only a little stream delivered, say, from 
 a small pipe, with great force. We increase the size of 
 the pipe, and get more water. That is the second case. 
 This makes the foregoing facts easy to remember. 
 
 When the current in a cell travels from the attacked 
 element to the non-attacked element, through the liquid in 
 the cell, it meets with resistance ; and so, also, when the 
 current travels around from the non-attacked element to 
 
46* 
 
 THE AGE OF ELECTRICITY. 
 
 Fig. 10. 
 
 the attacked element, by the wire outside the cell, it meets 
 with still further resistance. 
 
 Here, then, are two places where the current will meet 
 obstacles ; one inside the cell, and the 
 other outside of it. The resistance offered 
 by the liquid inside the cell is called the 
 internal resistance ; and that of the cir- 
 cuit outside the cell, the external resist- 
 ance, as illustrated in Fig. 10. 
 
 The external resistance we control. 
 It may be due to many miles of tele- 
 graph-wire, or to the coils of an electric 
 motor, or the filament of an electric lamp, 
 or to any other path which we provide for 
 the current, in traversing which it does the work we desire. 
 The internal resistance, however, is peculiar to the cell 
 itself ; and whatever work the current has to do to get 
 through this may be taken as wasted energy. Conse- 
 quently it is necessary to make the internal resistance of 
 the cell as small as possible ; and to do this there are 
 several ways. 
 
 It requires much less work to swim ten feet than twenty : 
 so in like manner, if we shorten the path of the current 
 through the liquid, it will have less liquid to go through, 
 and hence meet less resistance. Therefore we bring the 
 two solid bodies, or elements, in the cell, as near together 
 as possible without touching. 
 
 If, however, for any reason we find it impracticable or 
 undesirable thus to bring the plates close together, we can 
 leave the thickness of the intervening liquid as it is, but 
 increase the size (surface area) of the plates. Then more 
 of the attackable body will be attacked in a given time ; 
 and, as we have already seen, we shall have a stronger 
 current, which will more easily overcome the resistance. 
 
THE GALVANIC BATTERY. 47 
 
 In the first case, therefore, we actually diminish the 
 resistance by diminishing the thickness of the liquid, the 
 strength of the current remaining the same. In the second 
 
 & O 
 
 case, we neither increase nor diminish the resistance ; but 
 we augment the current strength, so that the obstacle is 
 more easily overcome. 
 
 It is very like journeying by railway from one place to 
 another. We can take a slow train by a short road, or a 
 fast train over a long road. 
 
 There is one more very important fact about the gal- 
 vanic cell, which is yet to be noticed. If we make a 
 simple cell, say of a plate of copper (the unattacked ele- 
 ment) , a plate of zinc (the attacked element) , and water, 
 we shall find, that after a very short time the electro- 
 motive force of the cell runs down, and that the current 
 very perceptibly weakens, or stops altogether. When this 
 happens, if we examine the copper plate carefully we shall 
 find it covered with minute bubbles of gas. This gas is 
 hydrogen, which in all cells, although generated at the 
 surface of contact of the attacking liquid and the attacked 
 element, nevertheless appears on the surface of the non- 
 attacked element. 
 
 This hydrogen is responsible for the weakening of our 
 cell : first, because it is a very bad conductor, and thus 
 opposes a high resistance to the current ; and, second, 
 because it may be itself attacked more readily than the 
 attackable element, so that a reverse current is set up, 
 flowing in the opposite direction to the one originally gen- 
 erated. When a cell thus becomes weakened, or rendered 
 inoperative, it is said to be polarized. It is therefore of 
 great importance to prevent this polarization ; because, no 
 matter how high the electro-motive force of the current at 
 the start, if the current is not- constant the battery is of 
 little value. 
 
-IS 
 
 777 /: AGE '>/'' i:Li:i r 
 
 We can now reeo<'iii/.e the 68ft6Htill] ('diidil ions of M o;oou 
 <r:ilv:inic cell ; :IIK| these MIT, 
 
 i. it should ha\e high electromotive force. 
 
 "2. It should have l>\\ internal resistance, so tint no 
 PIUTiiY should he wasted within I lie cell. 
 
 3. It should ejve a constant eiirrenl, :n:d Ilierefnre 
 pol:iri/:ilioii should he prevented in it. 
 
 Beyond these, MIT the further rci|uircmenls, that there 
 should heuoadion in the cell \vhcn the circuit is open; 
 lliMl it should emit n< di ^.\>< i -eeMhlc fumes; MIK|. liiiMlly, it 
 should he nuide of ehenp ;ind l.-istinu, iiiMtcriMls. No one 
 f.>iiu of cell fulfils :ill these conditions; hut, MS there MIT 
 verv IIIMIIV \Mrieties, it is possihle to select ccrhiin cells 
 MS especially :idMptcd to pnrliciilMr purposes. 
 
 <ol\:inic cells MTC usually dassilied with rc;v:m! to their 
 
 const I'licl ion. Mild lo Ihe dcpolMri/ino- Mjj,Tiit employed. 
 
 Thus (here MIT (I) ouc-lluid cells with no depolari/,ei\ 
 
 (J) one lluid cells with solitl dcpi.lai'i/ei' or li<|iii<l dcpolar- 
 
 i/cr, and ('.\ ) 1 \\ o lluid cells. 
 
 The simple cell of Volta, with ils 
 xinc :nd copper plates plunged in Mcid- 
 ulated water, is MII example of NIC lirsl 
 class. One of Ihe hcsi forms is I hat 
 kno\\n as Smce's hattcry, in which 
 the copper is repLaced hy platinum or 
 plaliui/.ed silver. The rou>li suri'Mce 
 of the platinum o'ives up Ihe hydro-ren 
 bubbles j :md so diminishes polari/.a- 
 tion. The ordinary arrangement of 
 Smee's cell is shown in l'ij. I I. The 
 plate of platinum or platini/.ed silver 
 is suspended from a wooden har whicn 
 
 sujtports two plates of amalgamated /.inc. Siue,le-lluid 
 lotteries of the al>o\e l\| v are siihjccl to three defects: 
 
n. \ /T/-: /,)". 
 
 49 
 
 (lirst) their electro-motive force is weakened by polariza- 
 tion, and they have (second) neither a constant current, 
 nor (third) a constant 
 
 To the second class of cells 
 above enumerated, belong the 
 well-known (In-net (liquid 
 depolarizer) and Lcclanche 
 (solid depolarizer) forms. 
 The Crenet cell (Fig. 12), 
 or. as it is sometimes called, 
 the bottle battery," con- 
 tains a plate of zinc sus- 
 pended between two plates 
 of carbon. The /ine is usu- 
 ally alllxed to a rod, so that 
 it can be conveniently raised 
 out of the solution when the 
 cell is not in use. The liquid 
 here contains bichromate of 
 
 potash, sulphuric acid, and water. This solution chemi- 
 cally acts upon the hydrogen bubbles, t,, destroy them 
 while they are in a nascent state. This cell has a 
 electro-motive force at the lu^inninir, and yield* a 
 fill current. 
 
 The Leclanche' cell, which is very much used on 
 telephone lines, and which is represented in Fiu;. 1;;, 
 contains a carbon plate, against which are fastened 
 by rubber bands blocks of solid auulomerate. composed 
 of black oxide of manganese, carbon, bisulphate of 
 potassium, and .mini lac. These agglomerate blocks act 
 as depolarizers. The zinc clement is in the form of a 
 rod. 
 
 Complete depolarization is obtained only in two-lluid 
 cells, which constitute the third class of battery above 
 
 Fig. 12. 
 
50 THE AGE OF ELECTRICITY. 
 
 noted. Of these the most prominent examples are the 
 Daniell and the Bnnsen. 
 
 The Daniell cell (Fig. 14) consists of a containiug- 
 vessel in which is placed a porous earthenware jar or cup. 
 Within the porous jar is a plate of amalgamated zinc, and 
 a dilute sulphuric acid. In the outer vessel is a plate of 
 
 Fig. 13. 
 
 copper ; the entire vessel is often itself made of that metal, 
 and the liquid here is a saturated solution of sulphate of 
 copper. When the circuit is closed, the zinc is attacked, 
 forming sulphate of zinc, and liberating hydrogen. Hut 
 this gas, in this cell, cannot as in other cells appear on the 
 copper plate ; because, in meeting the sulphate of copper, 
 
THE GALVANIC BATTERY. 
 
 51 
 
 the hydrogen combines with the sulphur to form sulphuric 
 acid, while the copper is deposited in the metallic state 
 on the copper plate. There is consequently no polariza- 
 
 Fig. 14. 
 
 tion, and the cell is constant ; but it has a high internal 
 resistance, and hence does not give a powerful current. 
 The gravity cell, based on the Daniell, is very widely used 
 
 Fig. 15. 
 
 for telegraphic purposes. Fig. 15 represents the Callaud 
 form, in which the zinc, in the form of a cylinder, is sus- 
 pended by hooks from the rim of the jar. The copper 
 
THE AGE OF ELECTRICITY. 
 
 Fig. 16. 
 
 element, a thin strip of rolled metal, rests on the bottom. 
 The solution of sulphate of copper is at the bottom of the 
 jar, and remains there because it is heavier than the sul- 
 phate of zinc solution which floats upon it. 
 
 Bunsen's battery is repre- 
 sented in Fig. 1G, and consists 
 of a glass vase V, in which is 
 placed a cylinder Z of amal- 
 gamated zinc, immersed in a 
 mixture of water and sulphuric 
 acid. Within the zinc cylinder 
 is a porous jar D of earthen- 
 ware, which contains a rod or 
 plate of carbon C immersed in 
 bichromate solution such as is 
 employed in the Grenet single- 
 fluid cell above described. 
 
 Of the different forms of batteries above enumerated, 
 the Daniell, for its constancy, is usually taken as the 
 standard. Taking its electro-motive force as unity, or 
 one volt, the electro-motive forces of the other cells men- 
 tioned are approximately as follows : 
 Smee, about .47 volt. 
 Leclanche, 1.48 volt. 
 Grenet, 2 volts. 
 Bun sen, 1.9 volt. 
 
 These forms are mentioned here merely as typical. 
 The actual number of different galvanic cells known to 
 electricians reaches into the hundreds. Experiment with 
 the hope of finding a cell which will be more constant, 
 of higher electro-motive force, or which will consume a 
 cheaper material than zinc, is constantly going forward. 
 
 As compared with the steam boiler, plus the engine and 
 the dynamo-electric machine, as a means of generating 
 
THE GALVANIC BATTERY. 53 
 
 electricity, the battery is most attractive. It costs but a 
 trifle to construct ; it needs no lire, and no attendance : 
 these are its advantages. On the other hand, zinc costs 
 twenty times as much as coal, and, other things being 
 equal, generates one-seventh the energy. 
 
 Yet we know that the consumption of zinc in the cell is 
 combustion, differing not essentially from the burning of 
 coal in the furnace. Why, we ask ourselves, from the 
 combustion of the expensive substance can we get a direct 
 current of electricit}', and not from the combustion of the 
 cheaper material? Wherever there is oxidation, there, in 
 some degree, an electric current is generated. But oxida- 
 tion in air is oxidation in the most perfect of electrical 
 insulators. The current will not travel from the attacked 
 body to a convenient conductor via the air, as it will via 
 water ; and so, up to the present time, we have found no 
 way of collecting the electricity which may be developed 
 in our grates and furnaces. 
 
 Why, then, if we can consume one oxidizable material 
 in the battery, cannot we consume another? If zinc, why 
 not carbon? In the Bunsen cell, and in a great many 
 others, carbon already enters into use as the non-attacked 
 element. Is it not possible to use with it some other sub- 
 stance, which the attacking material will not re-act upon 
 so readily as it will upon carbon ? Attempts in this direc- 
 tion have not been wanting. M. Jablochkoff has made a 
 cell in which one element is of coke, and the other of cast 
 iron. His liquid is melted nitrate of potash or nitrate of 
 soda. Here the coke, the carbon, is burned at the ex- 
 pense of the oxygen of the nitrate, while the cast iron 
 remains unattacked. Immense volumes of carbonic acid 
 are produced. The current yielded is powerful. But the 
 cell has no practical utility, save as a mile-post on a road 
 toward perhaps the most important electrical invention 
 
54 THE AGE OF ELECTRICITY. 
 
 that can be made ; namely, the consumption of carbon 
 directly in the battery, at low temperatures. 
 
 A curious improvement upon Jablochkoff's battery has 
 been contrived by M. Brard of La Rochelle, France, 
 which he calls an electro-generative combustible. It is, 
 in fact, a fuel which produces electricity ; or, rather, a 
 piece of prepared carbon, which when thrown into the lire 
 produces electricity by its combustion. Each so-called 
 slab is about six inches long by two inches wide and an 
 inch thick. It is composed of a prism of carbon, a prism 
 of nitrate of potash, and between these a plate of asbestos 
 which acts like the porous partition in ordinary cells. 
 The nitrate of potash is mixed with ashes to prevent too 
 rapid combustion and melting, and in this part of the slab 
 is embedded a sheet of copper which serves as one pole. 
 In the carbon are embedded several strips of brass or 
 copper which are connected to a single sheet, which forms 
 the other pole. It is necessary simply to throw the brick 
 into the fire, previously attaching wires to the poles, to 
 obtain a continuous current for an hour or two. The cur- 
 rent of a single slab will actuate an ordinary electric bell. 
 
 The galvanic battery, we have defined as an apparatus 
 for converting the energy of chemical affinity into electri- 
 cal energy. In most cases the force of chemical affinity 
 exerts itself as soon as the ingredients of the cell are put 
 together ; in others, as in the instance of the Jablochkoff 
 carbon nitrate-of-potash battery, the constituents of the 
 cell must be heated before the chemical re-actions can 
 occur. Of course, in the latter case, the resulting elec- 
 trical energy should represent not merely the energy of 
 chemical affinity, but also the heat energy employed in 
 setting free the latter. In fact, however, the energy pro- 
 duced is in no wise commensurate with the energy ex- 
 pended ; and all thermo-galvauic cells, so far as now 
 
THE GALVANIC BATTERY. 
 
 55 
 
 known, are exceedingly wasteful. The therm o-galvanic 
 cell should not be confounded with the thermo-electric cell 
 or thermo-pile. There is a broad distinction between them, 
 in that the thermo-galvanic cell converts heat energy into 
 electrical energy, through the medium of the energy of 
 chemical affinity ; while there is no perceptible chemical 
 re-action in the thermo-pile, and the heat applied is directly 
 converted into electricity. 
 
 The thermo-electric bat- 
 tery was discovered by 
 Professor Seebeck in 1821. 
 He soldered together 
 a piece of bismuth and a 
 piece of antimony, con- 
 nected their free ends to 
 a galva nometer which 
 would show when a cur- 
 rent passed, and then 
 heated a joint between the 
 metals. He found that 
 when the temperature of 
 
 the joint was greater than that of the remainder of the 
 circuit, a current traversed the circuit, apparently moving 
 from the bismuth to the antimony as shown in Fig. 17; 
 whereas, if the joint was cooler than the rest of the circuit, 
 then the current would move the other way. The electro- 
 motive force thus set up maintains a constant current so 
 long as the excess of temperature of the heated point is 
 kept up, heat being all the while absorbed in order to 
 maintain the energy of the current. 
 
 Curiously enough, just as the heating or the cooling of 
 the joint will produce a current in one or the other direc- 
 tion, so the passage of a current through the joint will 
 either heat or cool it. Thus, if a current be conducted 
 
 Fig. 17. 
 
56 THE AGE OF ELECTRICITY. 
 
 from bismuth to antimony, the joint is cooled ; if it be led 
 in the other direction, the joint is heated. This peculiar 
 phenomenon was discovered by Peltier in 1834, and is 
 known as the Peltier effect. Another remarkable effect 
 was discovered by Sir William Thompson. If a copper 
 wire be heated at one point, and cooled at another, a cur- 
 rent passing through the wire from the hot place to the 
 cool place will heat the wire. If the current goes the 
 other way, the wire will be cooled ; but if the wire be of 
 iron, then a current from the hot portion to the cold 
 portion causes cooling. 
 
 In constructing a thermo-electric pile, it is usual to join 
 a number of pairs of metal, as bismuth and antimony, in 
 series so bent that the alternate junctions can be heated 
 as shown in Fig. 17, at A A A, whilst the other set B B B 
 are kept cool. The various electro-motive forces then act 
 all in the same direction, and the current is increased in 
 proportion to the number of pairs of junctions. 
 
 Numerous experiments have been made on thermo-elec- 
 tric batteries, chiefly in France ; and with an apparatus of 
 six thousand elements, consuming some twenty-two pounds 
 of coke per hour, two arc lights, equal to between four 
 hundred and fifty and seven hundred and fifty candles, 
 have been maintained. The trouble with the thermo-pile 
 is its great waste ; the amount of energy utilized being 
 only between two and five per cent of that of the heat sup- 
 plied. Its best application is that made by Melloni, who 
 constructed many small pairs of antimony and bismuth in 
 a compact form for use as a thermometer. It is employed 
 with a sensitive galvanometer, and produces currents pro- 
 portional to the difference of temperature between the hot- 
 ter set of junctions on one face of the thermo-pile, and the 
 cooler set on the other face. If the hand, for instance, 
 be brought near on the one side, a current indicates its 
 
THE GALVANIC BATTERY. 57 
 
 radiant power ; or, if a piece of ice be brought near, a 
 current is also indicated, but moving in the opposite direc- 
 tion. In Professor Tyndall's admirable series of lectures 
 on " Heat as a Mode of Motion," this instrument is con- 
 stantly experimentally employed to show minute differ- 
 ences of temperature. It has been proposed to utilize the 
 waste heat of furnace-flues by surrounding them with 
 thermo-electric elements ; and the reverse process has also 
 been suggested, of making stoves the casing of which 
 generates electricity, while radiators diffuse the uncon- 
 verted heat for purposes of warmth. 
 
 In the preceding chapters we have seen that the dis- 
 charge of an electric machine or of a Leyden-jar is a min- 
 iature lightning flash. The discharge of a galvanic cell, 
 on the other hand, is continuous, and may flow over a 
 long period of time. The so-called static discharge may 
 be compared to the sudden explosion of dynamite ; the 
 so-called dynamic discharge or current, to the gradual 
 flow of steam or water. Both are electrical discharges, 
 and there is no inherent difference in the electricity mani- 
 fested ; although even to suppose such a difference in- 
 volves the conception of electricity as a corporeal thing, 
 like water, which is not proved. So-called static electri- 
 city is simply electricity of little strength, but of enormous 
 pressure. Dynamic or galvanic electricity has immense 
 strength, but little pressure. To borrow Professor Tyn- 
 dall's illustration : a cubic inch of air, if compressed with 
 sufficient power, may be able to rupture a very rigid en- 
 velope ; while a cubic yard of air, if not so compressed, 
 may exert but a feeble pressure upon the surface which 
 bounds it. Static or frictional electricity is in a con- 
 dition analogous to compressed air: its pressure, its 
 electro-motive force, is great. Galvanic or dynamic 
 electricity resembles the uncompressed air : there is a 
 
58 THE AGE OF ELECTRICITY. 
 
 great deal more of it, but its pressure is comparatively 
 minute. 
 
 The immense strength of current of the galvanic cell, 
 and consequent quantity of electricity yielded thereby, as 
 compared with the infinitesimal quantity and enormous 
 pressure of the static discharge, was illustrated in a 
 remarkable manner by Professor Faraday. As will be 
 explained hereafter, an electrical current when conducted 
 into water will decompose the same, tearing asunder the 
 hydrogen and oxygen molecules, and of course exerting 
 energy to effect this separation. The quantity-of current 
 necessary to decompose a grain of water is very small. 
 It measures 3.13 amperes ; and some idea of what it can 
 do will be obtained from the fact that it should keep a 
 platinum wire T J T of an inch in diameter red hot for three 
 and three-quarters minutes. In order to effect this same 
 decomposition by static electricity, there would be required 
 eight hundred thousand charges of fifteen large Leyden- 
 jars : each charge would be fully capable of killing a rat, 
 and if all of the charges could be accumulated into one, 
 the result would be a great flash of lightning. Faraday 
 estimated the electricity due to the chemical action of a 
 single grain of water on four grains of zinc to be equal 
 in quantity to that of a powerful thunder-storm. 
 
 By linking cells together, as has already been described, 
 we can increase the pressure of the galvanic current, and 
 make it more nearly approach that of the fractional or static 
 current. Professor Tyndall, however, states that it requires 
 a battery of more than a thousand cells to make the gal- 
 vanic current jump over an interval of air one-thousandth 
 of an inch in length. An electric machine of moderate 
 power, and furnished with a suitable conductor, is com- 
 petent to urge its current across an interval ten thousand 
 times as great as this. The magnetic needle will respond 
 
THE GALVANIC BATTERY. 59 
 
 to, and show by its deflection, the passage of an almost 
 infinitesimally small galvanic current ; but it is only by 
 the aid of arrangements for multiplying the effect that the 
 discharge of a large static electrical machine is enabled to 
 produce any deflection. With 11,000 cells, the aggregate 
 electro-motive force of which was 11,330 volts, Mr. War- 
 ren de la Rue succeeded in obtaining a spark but 0.62 inch 
 in length. On this basis, the electro-motive force of a 
 lightning flash a mile long should be over three and one- 
 half million volts. 
 
 We have already noted the fact, that wherever a chemi- 
 cal re-action exists between conducting substances, an 
 electric current is produced. This re-action in a great 
 many instances results from oxidation, the combining of 
 the oxygen of the liquid, usually with the substance of the 
 attacked element. 
 
 A very ingenious form of gas battery, invented by Sir 
 W. Grove, contains platinum elements in contact respec- 
 tively with hydrogen and oxygen gases. These elements 
 enter water ; and if they are joined by a wire, a current 
 apparently flows from the hydrogen, through the water 
 in which the ends of the elements enter, to the oxygen. 
 The hydrogen plays the part of a zinc plate, being 
 oxidized by the water ; and the hydrogen set free ap- 
 pears at the positive element (oxygen), and combines 
 with it. 
 
 Various cells have been devised with the object of 
 utilizing the oxygen of the air for depolarizing purposes. 
 Thus currents of air are sometimes pumped into the cell, 
 and against the plate on which the hydrogen is formed ; 
 and various cells have been devised, in which the polarized 
 plate is in the form of an endless belt, a wheel, or a series 
 of radial spokes. The wheel or- belt is revolved so as to 
 be partly in and partly out of the cell ; so that a portion 
 
60 THE AGE OF ELECTRICITY. 
 
 of it is always active while the remainder is in the air, the 
 hydrogen then escaping. 
 
 Jablochkoff's auto-accumulator is a cell remarkable for 
 its small size, light weight, low cost, and freedom from 
 deleterious fumes. It consists of a shallow vessel of hard 
 carbon, in which are placed scraps of metal, such us iron, 
 zinc, or sodium amalgam. Above the metal is a thickness 
 of sawdust, or a piece of coarse cloth, impregnated with 
 chloride of calcium. Upon the cloth are laid hollow sticks 
 of porous carbon. The whole forms a cell four inches 
 square and one inch high. The metal scraps and the 
 carbon vessel form a couple, the carbon being polarized 
 or charged with hydrogen. This carbon is in electrical 
 circuit with the upper porous carbons, which absorb oxy- 
 gen from the air. Thus we have two surfaces of carbon, 
 one charged with hydrogen and the other with oxygen ; 
 and these constitute the elements of the cell. As the cur- 
 rent flows, the oxygen and hydrogen generally combine ; 
 and the action continues until the supply of one or the 
 other of them is practically exhausted. Then, if the cir- 
 cuit be broken, a recuperative process immediately com- 
 mences : the hydrogen is evolved from the metal, and 
 attaches itself to the one carbon plate ; while the other 
 electrode fills its interstices again with oxygen, which will 
 be drawn out when the current commences to circulate. 
 And so the process goes on, action following rest, and 
 rest following action, as long as the supply of metal is not 
 exhausted, and there remains a small quantity of moisture 
 required for its oxidation. Five of these cells in series 
 will operate a five-candle-power lamp for an hour, the fila- 
 ment being still bright red at the end of that time. This 
 cell is believed to be of great promise as a means of sup- 
 plying current for domestic electric lighting. 
 
 Another curious atmospheric battery, devised by M. 
 
THE GALVANIC BATTERY. 61 
 
 Jablochkoff, consists simply of a small rod of sodium, 
 squeezed into contact with an amalgamated copper wire, 
 and flattened. This is wrapped in paper, and secured to 
 a plate of porous carbon. No liquid is used, the moisture 
 of the air settling on the oxidized surface of the sodium 
 being sufficient. 
 
 A battery which appears to be a decided step in the 
 direction of producing electricity from the oxidation of 
 coal, without the intervention of the steam-engine, was de- 
 vised in 1885 by Mr. J. A. Kendall, an English electrician. 
 Its operation is based upon the well-known phenomenon of 
 hydrogen passing through platinum at a red heat ; two 
 platinum plates being used as the poles, one exposed to 
 hydrogen, and the other to oxygen. These plates are 
 arranged in concentric tubes, closed at one end, and are 
 separated by a fluid medium of fused glass. Hydrogen 
 gas is continuously supplied to the inner platinum tube, 
 while the entire apparatus is maintained at a high tem- 
 perature by means of a furnace. The absorption of 
 hydrogen by the platinum is accompanied by electric gen- 
 eration, and the current is led away by wires connected to 
 the platinum tubes. The inventor has estimated that a 
 ton of coke used in heating the battery, including the 
 hydrogen-producer, will give at least three times the elec- 
 trical energy that would be produced by the same quantity 
 of coke used in working a steam-engine and dynamo. 
 
 There are a great many other forms of galvanic cell, 
 and new ones are constantly appearing. Most of them 
 are mere modifications of certain general types : others, 
 and especially those which involve novel modes of pre- 
 venting polarization, or which amount to real advances 
 in the direction of consuming carbon, or utilizing the oxy- 
 gen of the atmosphere, are of great scientific interest. 
 The subject is a most inviting one to inventors. 
 
62 THE AGE OF ELECTRICITY. 
 
 The battery of the future and it will be the greatest 
 of electrical wonders, when it is invented will simply 
 reproduce the Conditions existing in every household grate ; 
 that is, it will burn coal, by the aid of the air, to produce 
 electricity. At the present time, however, there are sev- 
 eral forms of battery which are worth noting as electrical 
 curiosities. One inventor boldly grasps the ocean, and 
 utilizes it as his conducting liquid. Of " earth batteries," 
 the globe we live on forms a part. These have been used 
 for driving clocks, and many people have supposed that 
 in some way electricity is drawn directly out of the ground. 
 Earth batteries, however, simply consist of plates of dif- 
 ferent metals, usually zinc and copper, which are buried 
 at a little distance apart in moist soil, the latter acting 
 like the liquid in an ordinary cell. They have a high 
 resistance, and low electro-motive force. The best place 
 for the zinc plate is under a stable, where saline liquids 
 permeate the ground. One inventor thought he had made 
 a tremendous discovery in recognizing that the lead water- 
 pipes and the iron gas-mains buried under city streets 
 constitute a huge earth battery, from which unlimited 
 electricity might be drawn to light the city. The fact that 
 a battery is there is true enough : but, unfortunately, the 
 attackable substance of the couple is the iron gas-main, 
 which would be surely consumed ; and, as the plan did 
 not contemplate any remuneration to gas-companies for 
 gas lost by leakage, it failed to come into practical use. 
 
 M. Duchemin has proposed to use the ocean as the 
 liquid in his battery, and submerge in the sea plates of 
 zinc and carbon attached to a floating body. The main 
 object of this battery was the preservation of the iron 
 hulls of vessels, or the iron buoys, from oxidation. Some 
 experiments were made on a small scale, which apparently 
 demonstrated that it was possible in this way to preserve 
 
THE GALVANIC BATTERY. 63 
 
 a surface of iron eighteen times larger than that of the 
 zinc electrode used. The investigations were interrupted 
 by the outbreak of the Franco-German war, and have not 
 been resumed. A somewhat similar idea was proposed 
 many years earlier, by Sir Humphry Davy, who suggested 
 the protection of the copper sheathing of vessels, by means 
 of a communicating sheet of zinc immersed in the sea. It 
 was found that an extent of zinc surface, one hundred 
 and fifty times less than that of the copper, was suffi- 
 cient to protect the latter ; but the plan was abandoned 
 for the reason that certain salts contained in the sea-water 
 were decomposed, and the resulting earthy oxides depos- 
 ited themselves on the copper, roughening the surface, 
 and rendering the same particularly inviting to barnacles, 
 which attached themselves in great numbers, and so ma- 
 terially impeded the speed of the vessel. 
 
 It may be mentioned here, that efforts have been made 
 of late years to remove barnacles from ships' bottoms by 
 powerful currents led to the copper from dynamo-electric 
 machines, thence passing to the water. The current 
 seriously incommoded the barnacles, which made such 
 efforts as lie within the limited capacity of the clam, to 
 get out of their shells ; but, Nature not having provided 
 them with suitable means for this purpose, they remained, 
 and submitted to the disturbance with their usual equa- 
 nimity, possibly cheered by the knowledge that on the 
 whole the experiment was a failure. 
 
 Probably the largest galvanic battery ever made is that 
 used in the Royal Institution in London. It consists of 
 14,400 cells of chloride of silver and zinc elements. It is 
 estimated that a lightning flash a mile long could be pro- 
 duced by 243 such batteries. 
 
 The battery which will last- the longest is the dry pile 
 devised by Zamboni. This consists of a number of paper 
 
64 THE AGE OF ELECTRICITY. 
 
 disks, coated with zinc foil on one side and with an oxide 
 of manganese on the other, piled upon one another, to the 
 number of many thousands, in a glass tube. The electro- 
 motive force is great, and a good pile will yield sparks. 
 The current is very weak, but it lasts an extraordinary 
 length of time. In the Clarendon Library at Oxford, 
 there is a pile, the poles of which are two metal bells ; 
 between them is hung a small brass ball, which, by oscil- 
 lating to and fro, slowly discharges the electricity. It 
 has been continuously ringing the bells for over forty 
 years. 
 
 One of the most curious alleged discoveries concerning 
 the galvanic battery was that of Mr. Arnold Crosse, who 
 in the early part of the present century announced the 
 extraordinary fact that living insects were generated in 
 the cell. He stated, that while endeavoring to deposit 
 crystals of silica on a lump of stone, by the agency of the 
 current, he noticed, after the experiment had continued 
 for a fortnight, whitish specks on the stone, which at the 
 end of the twenty-eighth day assumed the appearance of 
 insects, standing erect on the bristles which formed their 
 tails, and distinctly moving their legs. The experimenter 
 was greatly astonished. Instead of a mineral, for which 
 be had looked as the result of his experiment, he had 
 found an animal, alive and kicking. It was plain these 
 were no mere appearances ; for in a few days they de- 
 tached themselves from the stone, and began to move 
 about. They were, to be sure, not creatures of a very 
 inviting and attractive character ; for they belonged ap- 
 parently to the genus acarus, which includes some of the 
 most disagreeable parasites of the animal body. But they 
 continued to increase, and in the course of a few weeks 
 hundreds made their appearance. Crosse himself hesi- 
 tated to believe that spontaneous generation could attend 
 
THE GALVANIC BATTERY. 65 
 
 any action of electricity, and conjectured that bis cell was 
 simply a favorable place for tbe hatching of the ova of 
 the insects existing in the atmosphere. He and others at 
 the time made many experiments intended to preclude the 
 possibility of these ova being present, but the insects 
 continued to appear. The phenomenon made a great 
 sensation. Despite the fact of Crosse's own hesitancy 
 in asserting that he could produce life, others flatly main- 
 tained the possibility. At the opposite extreme, were 
 those who attacked Crosse for impiety. If he began by 
 creating animals by electrical power, no matter of how 
 inferior sort, who could tell where he might stop? He 
 was called a " disturber of the peace of families," and a 
 " reviler of religion." 
 
 The French Academy of Sciences, however, on receipt 
 of a phial of the mysterious insects, treated the whole 
 matter as unworthy of serious consideration ; and one 
 member individually pointed out that the means employed 
 by Crosse simply excited and favored the germination of 
 the ova which must have been present. Many years later 
 (1859), Professor Schulze in Germany repeated Crosse's 
 experiments, aided by more modern knowledge of minute 
 organisms, and modes of sterilization, and showed con- 
 clusively that none were generated. The controversy had 
 then continued for nearly half a century. 
 
 Among other remarkable ideas concerning the galvanic 
 battery, it has been suggested, that, wherever two flavors 
 are habitually formed in cooking and eating, the reason 
 why they mutually improve each other is because a certain 
 amount of electric action is set up between the sub- 
 stances employed to produce them. Mr. Edwin Smith, 
 M.A., has conducted quite an extended series of experi- 
 ments based on this theory ; and has used as elements in 
 a galvanic cell, pairs of eatables which generally go to- 
 
66 THE AGE OF ELECTRICITY. 
 
 gether, such as pepper and salt, coffee and sugar, almonds 
 and raisins. He states that he found a voltaic current, 
 more or less strong, excited in every instance, and that 
 bitters and sweets, pungents and salts, or bitters and 
 acids, generally appear to furnish true voltaic couples, 
 doubtless in consequence of the mutual action of some 
 alkaloid salt, and an acid or its equivalent. Mr. Smith 
 gives quite a long list of substances tested. Among his 
 couples are tea and sugar, raw potato and lemon- juice, 
 nutmeg and sugar, horse-radish and table salt, onion and 
 beet-root, vanilla and sugar, starch and iodine, and 
 tobacco and tartaric acid. The substance firs't named in 
 each couple takes the place of the zinc, or attacked 
 element, in the cell. 
 
 Mr. Smith suggests that the rationale of the right 
 blending of flavors " might be found partly, no doubt, 
 in chemistry, but partly also in galvanism." 
 
 One of the most curious batteries is that devised by 
 Sauer, which appears to act only in the sunlight. It 
 consists of a glass vessel containing a solution of table 
 salt and sulphate of copper in water ; within is a porous 
 cell containing mercury. One element is of platinum, 
 and is immersed in the mercury : the other is sulphide of 
 silver, and is placed in the salt solution. Both elements 
 are connected to a galvanometer. When the battery is 
 placed in the sunlight, the needle is deflected to a certain 
 point, and the sulphide of silver is found to be the negative 
 pole. The action of the battery depends on the effect of 
 the chloride of copper upon the mercury. Sub-chloride 
 is formed, and reduces the sulphide of silver ; but this 
 can take place only by the aid of sunlight. 
 
 For the heavy work of electric lighting, or the driving 
 of electro- motors, batteries are superseded by dynamo- 
 electric machines, for economical reasons already pointed 
 
THE GALVANIC BATTERY. 67 
 
 out; but where large expenditure of energy is not re- 
 quired, as in the telegraph and telephone, batteries find 
 a wide utilization. Ultimately they will displace the 
 dynamo, and in time the steam-boiler. To make them do 
 this, is the great electrical problem of the century. 
 
68 THE AGE OF ELECTRICITY. 
 
 CHAPTER VI. 
 
 THE ELECTRO-MAGNET, AND THE CONVERSION OF ELEC- 
 TRICITY INTO MAGNETISM. 
 
 THE tide of a great river moving to the sea is the 
 embodiment of mighty volume. The mountain stream, 
 albeit a mere thread of water leaping down from rock to 
 rock, conve} r s to us the idea of intense energy. The 
 volume of the river, the force of the torrent, unite in the 
 great cataract. All of these conditions find their parallels 
 in the electrical current. From the galvanic battery flows 
 the slow and steady river ; from the electric machine, 
 the swift but slender torrent ; and from the dynamo, the 
 Niagara. 
 
 And, as we have seen, the electrical current moving in 
 its path is governed by laws similar to those which control 
 water flowing in its channel. We can contract the area 
 of the conduit to diminish, or enlarge it to increase, the 
 flow. We can augment or decrease the pressure of either 
 water or electricity, and so send more or less through the 
 appointed path in a given time. 
 
 A step farther, and the analogy fails. Water acts 
 directly only upon objects in it or on it. It may float a 
 vessel, or turn a wheel, or break down barriers ; but the 
 mightiest flood cannot influence a grain of iron to move 
 one way or the other, if a few feet of air intervene. Sup- 
 pose a current of water did have all the properties of an 
 
THE ELECTRO-MAGNET. 69 
 
 electrical current : what might happen ? Perhaps, around 
 and above every stream, there would be a viewless atmos- 
 phere which we could not penetrate ; an atmosphere in 
 which the laws of gravity affecting iron and steel would 
 be set at naught, in which every iron bar would be a mag- 
 net placing itself across the flood, a most strange and 
 mysterious medium, in which things of iron and steel 
 would arrange themselves in curious cuives, whorls and 
 whirlpools and vortices of iron ; a field of strains and 
 stresses in something not the air yet in and with the air, 
 of lines of forces without breadth and unending. 
 
 This sounds fantastic when spoken of water. But it is 
 true of two natural phenomena, a conductor through 
 which an electrical current is passing, and the magnet. 
 Around the wire through which electricity is passing, and 
 in front of the poles of a magnet, exists this strange 
 aura ; not in imagination, but in fact, for we can make it 
 visible. 
 
 First, however, let us recall something about magnets 
 in general. 
 
 Ages ago, in Magnesia in Asia Minor, were found cer- 
 tain hard black stones which possessed the remarkable 
 property of attracting to themselves bits of iron and steel. 
 These the ancients called magnets, from the name of the 
 locality in which they were found. And as their behavior 
 was altogether incomprehensible, the ancients, in accord- 
 ance with their usual way of dealing with things which 
 they did not understand, disposed of the problem very 
 easily by ascribing the phenomenon to the supernatural 
 powers. It is a little odd, by the way, that pretty much 
 every thing which the ancients used to attribute to genii 
 and spirits because unintelligible is unhesitatingly as- 
 cribed by a large section of their posterity to "electri- 
 city ; " the mere mention of the word being quite sufficient 
 
70 THE AGE OF ELECTRICITY. 
 
 to account for any thing out of the common run. from 
 rheumatism to red sunsets. 
 
 The knowledge of the ancients about the magnet seems 
 to have stopped with the fact of its attractive power. The 
 Orientals, with characteristic largeness of imagination, 
 were not slow to conceive of the tremendous things which 
 huge magnets might do. Who does not remember the 
 story of the third calendar in the "Arabian Nights," 
 wherein the story-teller recounts the remarkable fate which 
 befell his ship ? 
 
 " A sailor from the mast-head gave notice that he saw 
 something which had the appearance of land, but looked 
 uncommonly black. The pilot, on this report, expressed 
 the utmost consternation. ' We are lost ! ' said he : ' the 
 tempest has driven us within the influence of the black 
 mountain, which is a rock of adamant, and at this lime 
 its attraction draws us toward it : to-morrow we shall 
 approach so near that the iron and nails will be drawn out 
 of the ship, which of course must fall to pieces ; and as 
 the mountain is entirely inaccessible, we must all perish/ 
 This account was too true. The next day, as we drew 
 near the mountain, the iron all flew out of the ship : it fell 
 to pieces, and the whole crew perished in my sight." 
 
 For a great many centuries, the world knew simply that 
 magnets would attract iron. Then somebody tradition 
 says the Chinese (which is convenient, because every- 
 body knows they were civilized ages ago, and if they did 
 not have modern improvements then, no one can dispute 
 to the contrary) hung up a magnet by a thread, and 
 discovered that it pointed north and south. After that it 
 was called the loadstone (leading stone), and the mari- 
 ner's compass came into existence. Now we know the 
 magnet as an ore of iron, miueralogically termed magnet- 
 ite, and chemically Fe 8 O 4 . 
 
THE ELECTEO-MAGNET. 71 
 
 This knowledge, however, useful as it is, has not pre- 
 vented people from trying to press the magnet into service 
 as a means of solving that long- vexed problem, of lifting 
 one's self over a fence by one's own boot-straps. Where- 
 fore they have invented or rather failed to invent 
 magnetic motors, not electro-magnetic motors, which 
 are quite another thing, but motors depending on the 
 constant attraction of permanent magnets. Every once 
 in a while, some one announces the accomplishment of 
 this feat, which primarily depends on cutting off the at- 
 traction of the magnet by causing the latter to move some- 
 thing in the way of a screen between its own pole and 
 the thing attracted. Unfortunately, magnetic attraction 
 refuses to be cut off in any such way. It is as stubborn in 
 this respect as the attraction of gravity, which it very 
 much resembles. 
 
 In that same famous work which began the modern 
 science of electricity in 1600, Dr. Gilbert's " De Mag- 
 nete," it was announced that the attractive power of 
 a magnet, when in elongated form, resides at the ends. 
 These, Gilbert called the poles ; and he also pointed out 
 that the intermediate region attracted iron-filings less 
 strongly, while midway between the poles there was no 
 attraction at all. Every magnet, large or small, has these 
 poles : they are inseparable. We may grind a magnet 
 into powder : every grain will be an independent magnet, 
 having its opposite poles. Furthermore, just as there ap- 
 pear to be two kinds of electricity, high potential and 
 low potential, or positive and negative, so these two poles 
 appear to have opposite characters ; one tending to move to 
 the north, the other to the south. Hence the poles are com- 
 monly called, respectively, the north and the south poles. 
 When the poles of two magnets are brought together, like 
 poles always repel, while unlike poles attract each other. 
 
72 THE AGE OF ELECTRICITY. 
 
 To Gilbert is due the distinction between magnets and 
 magnetic bodies. A magnetic body is a body capable of 
 being magnetized, such as a piece of iron. Either pole 
 of a magnet will attract a magnetic body ; but two mag- 
 nets will attract or repel each other, according as unlike 
 or like poles are presented. Gilbert also made the ex- 
 traordinary discovery that the earth is a huge magnet ; 
 that its poles coincide, nearly, with the geographical North 
 and South Poles ; and that therefore it causes the freely 
 suspended magnet which forms the compass needle to 
 place itself in a north-and-south position. 
 
 And now we reach a fact about magnets which is be- 
 wildering, because it tends to upset all our notions about 
 time. If we present a magnet to a bit of iron, we see the 
 iron attracted apparently instantly. We should be ready 
 to assert, by all the evidences of our senses, that abso- 
 lutely nothing could happen between the instant the mag- 
 net is presented and the instant the iron is attracted. Yet 
 something does happen. Before that magnet can attract 
 the iron, while the iron is yet distant from it, it must 
 alter the whole magnetic state of the iron mass. The 
 magnet must induce, on the end of the iron nearest it, a 
 pole of opposite name to the pole presented ; and at the 
 farther end of the iron, a pole of the same name. In 
 other words, it must convert the magnetic body into a 
 magnet. Having done that, it repels one end, and at- 
 tracts the other. But this is done before the attraction 
 begins ; but in what period of time we do not know, nor 
 could we form the faintest conception of its duration if 
 we did. 
 
 Why does a magnet act in this way? What is the mys- 
 terious atmosphere surrounding it, which makes it repel 
 or attract bodies, or convert other bodies into magnets? 
 There is a theory, a very learned one, which is al- 
 
THE ELECTRO-NAG NET. 73 
 
 together too deep for these pages, so it is left out ; but, 
 without going into that, we can see for ourselves the 
 effects of this atmosphere, in a very satisfactory way. 
 
 If we take an ordinary bar magnet, and place a piece 
 of paper or, better, glass over one of its poles, and 
 sprinkle finely sifted iron-filings on the glass, we shall see 
 these filings arrange themselves in curious curves, appar- 
 
 Fig. 19. 
 
 ently radiating from the pole, as in Fig. 18. If we sub- 
 stitute for the bar magnet a horse-shoe magnet, and place 
 the glass over both poles, we shall find that the lines 
 
74 
 
 THE AGE OF ELECTRICITY. 
 
 diverge nearly radially from each pole, and curve around 
 to meet the opposite pole, as in Fig. 19. If we take two 
 horse-shoe magnets, and place like poles facing each other, 
 
 then the filings curve away as if repelling each other, as in 
 Fig. 20 : on the other hand, if we bring opposite poles of 
 the magnets into proximity, then the filings curve around 
 from one pole to the other. The actual appearance of the 
 
 Fig. 21. 
 
 iron-filings 
 
 iron-filings is here shown, in Fig. 21. The 
 represented were dusted over glass plates supported on 
 the poles of the magnets ; and when they had assumed 
 
THE ELECTEO-MAGNET. 75 
 
 the positions clue to the magnetic influence, they were 
 fixed in place by an adhesive substance, and the plates 
 were used as photographic negatives, whence the engrav- 
 ings were produced. 
 
 Now, what does all this mean? Simply, that the mag- 
 net is telling its own story, writing it, in fact, for us to 
 read. We know perfectly well that iron-filings will no 
 more arrange themselves in rows or curves, of their own 
 volition, than books will place themselves in rows on 
 shelves ; and that there must be some force which tends 
 to place the filings in these lines. We notice also that the 
 curves are closer together near the poles, and, in fact, the 
 filings resemble a crowd of people massed around some 
 common object of interest : the crowd is thickest around 
 the object, and more scattering as the distance therefrom 
 increases. 
 
 It appears, therefore, that around the pole of a magnet 
 exists this strange atmosphere to which we have already 
 referred, a so-called "field of force," in which exist 
 strains and pulls and pushes as if a host of infinitesimal 
 beings were at work seizing upon the filings, and arran- 
 ging them to make them accommodate themselves to this 
 new condition of affairs. And the result of it all is, that 
 we recognize seeming lines of force radiating from the 
 pole. It is a wonderful atmosphere, that magnetic field. 
 We have only to move a piece of iron in it, in a peculiar 
 way, to make speech heard miles distant, or to produce 
 the light which is weaker only than the sun in power ; 
 and what still stranger things may yet be done, no one 
 knows. Meanwhile these lines of force, which we see 
 mapped for us by the iron-filings, have some singular 
 properties of their own. They never have a free end. 
 The finding of a free end to a magnetic line, and of the 
 place whence the rainbow rises, and the invention of a 
 
76 
 
 THE AGE OF ELECTRICITY. 
 
 magnetic motor, are all will-o'-the-wisps together. Every 
 magnetic line that starts gets somewhere. If apparently 
 curving from a north pole, it will end in a south pole, 
 perhaps the south pole of the same magnet, perhaps the 
 south pole of some other magnet, and perhaps in a south 
 pole induced by itself in a magnetic body. 
 
 There must be, 
 however, a magnet or 
 magnetic body ; and 
 Gilbert, the reader 
 will remember, not 
 tSih-er C/tit/vv ^~ Gilbert who wrote 
 "De Magnete," but 
 a later Gilbert who 
 wrote "Pinafore" 
 and ' ; Patience," 
 has very clearly de- 
 monstrated this in a 
 pathetic ballad about 
 a magnet which vainly attempted to attract a silver churn. 
 That magnet sent out no lines of force toward the silver 
 churn ; and perhaps it may be well to illustrate this sad 
 condition of affairs, just to fix the idea in our minds. No 
 lines of force in Fig. 22 go to the silver churn ; but if 
 the churn had been of iron, the result, as we see, would 
 have been very different, and then 
 
 " This magnetic 
 
 Peripatetic 
 Lover who lived to learn, 
 
 By no endeavor 
 
 Can magnet ever 
 Attract a silver churn," 
 
 Iron C/iur/v 
 
 Fig. 22. 
 
 might not have wasted his rejected fascinations. 
 
THE ELECTRO-MAGNET. 
 
 77 
 
 And this also, by the way, indicates the reason why the 
 officers of Atlantic steamers show so much uneasiness 
 when young ladies persist in bringing their sewing appara- 
 tus into the neighborhood of the compasses. The lines 
 of force from the north pole of a very sedate and responsi- 
 ble compass-needle may find easily a south pole in the 
 frivolous knitting or crochet needle, and, turning in the 
 direction of the latter, may lead the ship miles from her 
 course. 
 
 It has been said that a magnet, when it attracts a body 
 of magnetic material, first induces magnetism in the latter. 
 Thus by simply placing a piece of iron in a magnetic field, 
 and taking it out again, we can render that iron magnetic 
 or non-magnetic, as it is termed, by induction. If, how- 
 ever, we wish to render the metal permanently magnetic, 
 we can do so by rubbing it with a permanent magnet in a 
 peculiar way. 
 
 We have stated that in two instances in nature this 
 strange surrounding atmosphere is produced. We have 
 seen it proved by the behav- 
 ior of the iron-filings in the 
 neighborhood of the pole of 
 a magnet. It remains to de- 
 tect it around the conductor 
 of an electric current. This 
 is easily done. Take a piece 
 of card, or, better, a sheet of 
 glass, through which a hole 
 has been drilled, and pass the 
 wire through which the current 
 is moving, through the hole. 
 Then sprinkle iron-filings around the wire. The filings 
 will arrange themselves in a series of concentric circles, 
 just as if they were controlled by a whirlwind, around the 
 
 Fig. 23. 
 
78 
 
 THE AGE OF ELECTRICITY. 
 
 wire. This is beautifully represented in Fig. 23, which has 
 been prepared from a photograph. If the wire is carried 
 parallel to and across the glass plate as in Fig. 24, the 
 
 filings will arrange them- 
 selves in straight lines per- 
 pendicular to the direction 
 of the wire and at equal 
 distances from one another ; 
 and may be regarded as a 
 number of repetitions of 
 Fig. 23, strung upon a wire, 
 and looked at edgeways. 
 
 This is different from 
 
 F '9' 24 - what happens with the 
 
 magnet. Compare Figs. 18 and 23. 
 
 If we suppose the lines of force indicated by the iron- 
 filings to represent a wind 
 blowing, then a flag placed 
 near a magnet would stand 
 as in Fig. 25; whereas, ;,'^ 
 if the flag were placed near 
 the wire, it would stand as in Fig. 
 
 
 Fig. 25. 
 
 26. A suspended 
 magnetized needle would place it- 
 self in the same positions with ref- 
 erence to wire or magnet, under the 
 influence of the lines of force. 
 
 A wire conducting a current, 
 therefore, is surrounded by lines of 
 force like those surrounding the 
 natural magnet, but differently dis- 
 posed. Such a wire is, in fact, a 
 magnet. It will attract iron-filings ; 
 
 and they will cling to it as long as the current continues, 
 
 but drop off as soon as the current stops. 
 
THE ELECTRO-MAGNET. 
 
 79 
 
 Now, suppose we wind our conducting wire into a helix 
 or coil, as in Fig. 27. If the entire length of the wire is 
 surrounded by the whorl of lines of force, clearly a great 
 many of these lines will /. 
 
 converge in the space in- 
 side the coil, and we shall 
 have there a very strong or 
 concentrated field of force. 
 Into this field we can easily 
 insert an iron bar, which will then become very strongly 
 magnetized. That is, just as it would become a magnet 
 if placed in the field of another magnet, so now it 
 becomes a magnet when placed in the field of force of 
 the wire. 
 
 This is very perfectly illustrated in Fig. 28. Here the 
 wire is represented with a turn in it, and the lines are thus 
 
 Fig. 27. 
 
 
 
 Fig. 28. 
 
 Fig. 29. 
 
 perpendicular to the plane of the loop. The filings now 
 form themselves (as far as the plate will allow them) into 
 lines perpendicular to the plane of the paper, and there- 
 fore, as seen from above, appear simply as isolated dots 
 or points. Fig. 29 illustrates the lines of force brought 
 into play in the manner above described in the induction 
 
80 THE AGE OF ELECTRICITY. 
 
 of magnetism in an iron bar when an electric current is 
 sent through a wire coiled around it. It represents a 
 small electro-magnet, showing four turns of its coil. In 
 the actual experiment, the bar was a strip of ferrotype 
 iron, and the wire carrying the current was threaded 
 through the eight holes, four being on one side of the bar, 
 and four on the other. 
 
 The iron bar or core of an electro-magnet, as we have 
 said, temporarily behaves like a permanent magnet. It 
 has a magnetic field of its own, with endless lines of force, 
 and, in fact, is a permanent magnet as long as the 
 electrical current flows in the coil surrounding it. And 
 
 it is worth while to 
 repeat this very im- 
 portant distinction. 
 A permanent magnet 
 is always a magnet : 
 an electro-magnet is 
 not a magnet except 
 
 Fjg 30 when the electrical 
 
 current is passing 
 
 through its coil. It i3 a difficult thing, comparatively 
 speaking, either to convert a piece of iron into a per- 
 manent magnet, or to render a permanent magnet free 
 from magnetism. On the other hand, an electro-magnet 
 is energized or de-energized witli infinite rapidity, by 
 simply establishing or stopping the current in the coil. 
 The poles of a permanent magnet are fixed : those of an 
 electro-magnet depend upon the direction of the current, 
 Thus, in Fig. 3-0, supposing the inner shaded circle to rep- 
 resent the bar, or "core" of the magnet, if the current 
 moves in the coil represented by the outer circle in the 
 direction of the arrow in 1, that is, in the same direction 
 as the hands of a watch, the end of the core facing us is 
 
THE ELECTRO-MAGNET. 
 
 81 
 
 JElecti'o Miufiiet 
 
 Core 
 
 a south pole. If the current travelled the other way> as in 
 2, the same end of the bar would be a north pole. So 
 that we can not only make and unmake an electro-magnet, 
 b}^ establishing or breaking the current ; but we can 
 reverse the polarity of the magnet at will, by simply 
 reversing the direction of the current in the coil. 
 
 In Fig. ol is represented in diagram an electro-magnet 
 which communicates with a battery ; and a circuit-closing 
 key^ by manipulating which we can establish or interrupt 
 the current from the battery through the coil of the mag- 
 net. In front of the core hangs a piece of magnetic 
 metal, called the ar- 
 mature; and this is 
 held away from the 
 magnet by a coiled 
 spring fastened at its 
 opposite end to a 
 fixed post. In Fig. 
 31, the key is shown 
 raised ; no current ^ 
 then passes to the ^ 
 coil, and the bar is Fig. si. 
 
 not a magnet. 
 
 If, however, we press down the key, then the current 
 from the battery will instantly circulate through the coil ; 
 the core will become a magnet, and attract its armature ay 
 indicated by the dotted lines. If we break the circuit 
 again, the armature, no longer attracted, will be drawn 
 back by the spring ; and hence we can keep that armature 
 vibrating to and fro as often as we can make and break 
 the circuit. As the magnet may be quite strong, it may 
 attract its armature with much force, so that we can make 
 the armature drive mechanism. This is how the electro- 
 magnet converts electricity into mechanical motion in the 
 
82 
 
 THE AGE OF ELECTRICITY. 
 
 great majority of electrical devices, including the tele- 
 graph, the electro-motor, and the countless alarms and 
 kindred apparatus to some of which reference will here- 
 after be made. 
 
 There is still another way in which the electro-magnet 
 can vibrate its armature ; and that is by reversing the 
 
 polarity of the core, by 
 simply changing the 
 direction of flow of the 
 current. Suppose, in 
 Fig. 32, a current cir- 
 culated around the bar 
 
 N 
 
 Jlrniatwe 
 
 Fig. 32. 
 
 or core, in the direc- 
 tion of the arrow ; then 
 the right-hand end would be the north pole. If, instead 
 of suspending before our electro-magnet an armature of 
 magnetic material, we suspended an armature itself a 
 magnet, having north and south poles, as marked in the 
 diagram, then, when the nearest end of the electro-magnet 
 became north, the armature would be attracted, because 
 unlike magnetic poles would be opposed. But if we 
 reversed the current, as 
 
 8 
 
 Fig. 33. 
 
 shown in Fig. 33, then 
 like magnetic poles would 
 be opposed, and the arma- 
 ture would be repelled. 
 So that, by simply making 
 the current travel first in one way and then in the other, 
 we can set a magnet or polarized armature into vibra- 
 tion. If the armature were not polarized, of course the 
 changing of the current would have no effect on it ; 
 either pole of a magnet attracting a simple magnetic 
 body not itself a magnet. We shall find this contriv- 
 ance largely used in the various practical applications 
 
THE ELECTRO-MAGNET. 83 
 
 of electricity ; although perhaps to not so great an extent 
 as the first-mentioned arrangement,, with which, just as 
 the steam-engine can be controlled by throttling the steam, 
 so the magnet is controlled by throttling the current. 
 
 As we shall see farther on, electro-magnets can be made 
 to exert sufficient power to drive locomotives, and do other 
 heavy mechanical work : so that it is quite important to 
 know something as to how they acquire this. A magnet, 
 whether electrical or permanent, has no power of its own. 
 It can only exert whatever energy is put into it. It is 
 like a clock-spring : wind it up, and it drives the clock, 
 not by some inherent clock-driving capacity peculiar to 
 springs, like the inherent meat-roasting quality ascribed 
 by Martinus Scriblerus to roasting-jacks, but because 
 it has been wound up. When a body is rendered mag- 
 netic, whether by electricity, or by natural means, or by 
 rubbing, energy is imparted to it. When the magnet 
 exerts itself, it parts with some of that energy. If it 
 moves a heavy armature up to its pole, it may expend all 
 the energy it can exert, and will affect other bodies not 
 at all. If a permanent magnet thus draws its armature, 
 it can do no more until the armature is withdrawn. To 
 take away that armature, requires just as much force as 
 the magnet used in attracting it ; so that, by this action, 
 the energy expended by the magnet in attracting ,the 
 armature is restored to it. 
 
 To the electro-magnet, we impart power by the current. 
 The stronger the current, the stronger the magnet, up to a 
 certain point. Eventually, however, the iron of the core be- 
 comes " saturated," that is, it reaches a state when it can 
 apparently be no longer affected. If the current is kept con- 
 stant, and the magnet below saturation, then, the greater the 
 number of turns of wire applied, the stronger the magnet. 
 
 An electro-magnet is easily made of a central bar or 
 
84 
 
 THE AGE OF ELECTRICITY. 
 
 core of iron, around which the insulated wire is coiled like 
 a spool of thread. Usually the core is made in the form 
 of a horse-shoe, so that both poles may be applied to one 
 iron armature. The coil is then divided into two parts, as 
 shown in Fig. 34. In this engraving the magnet is rep- 
 resented as having attracted its armature, the plate 
 immediately beneath the coils, and is sustaining weights 
 
 Fig. 34. 
 
 on a platform dependent therefrom. An electro-magnet 
 was designed by Professor Joule, capable of supporting 
 in this way over a ton, and of exerting an attraction on 
 its armature of about two hundred pounds per square inch. 
 The Stevens Institute of Technology possesses one of 
 the largest electro-magnets in the world. It weighs about 
 sixteen hundred pounds, and has a lifting force of nearly 
 forty tons. 
 
THE ELECTRO-MAGNET. 85 
 
 It is generally believed that the effect of magnetizing 
 the iron core is to cause each particle of the iron to try 
 to set itself at right angles to the direction of the current 
 in the coil, just as Oersted's needle places itself at right 
 angles to the wire conveying a current. The result is, 
 that the irregularly shaped particles place themselves with 
 their longer axes parallel to the core ; and, as they all do 
 this, the core as a unit becomes longer and thinner. Of 
 course it is very hard to realize how this can happen in a 
 body as dense and hard as iron ; and so it is difficult to 
 imagine the vibration of the atoms when iron is heated, or 
 to conceive of the infinitesimal shortness of the paths over 
 which they must move. Still it is quite certain that this 
 is what does occur. By actual measurement a rod of iron 
 magnetized to saturation is found to have increased to the 
 extent of ^oVon f its length. And even if this change 
 is too small for our eyes to perceive, it is perfectly easy to 
 hear it ; for the core can be arranged not only so that it 
 will give out a very perceptible tick when magnetized, but, 
 if the current be sent from a telephone transmitter, it will 
 sing and talk, the sounds being produced simply by 
 changes in the bar itself. 
 
 There is hardly a parallel instance, in the history of 
 electricity, of a discovery being so rapidly turned to prac- 
 tical account as was that of Oersted. He performed- his 
 successful experiment in causing the free needle to be 
 moved by a current traversing a wire, as we have stated, 
 in the summer of 1820. Arago and Ampere, in France, 
 at once began investigations. By the end of the follow- 
 ing September, Arago announced that he had ascertained 
 that iron-filings were attracted "by the connecting-wire 
 of the battery, exactly as by a magnet," and that he had 
 magnetized a sewing-needle permanently by the galvanic 
 current. Ampere reported almost immediately, that a 
 
86 THE AGE OF ELECTRICITY. 
 
 spiral or helical arrangement of the galvanic conducting- 
 wire was most advantageous for magnetizing needles. 
 Early in November, he " perfectly imitated a magnet by a 
 helical galvanic conducting- wire." Four years later, Wil- 
 liam Sturgeon made the electro-magnet, using a core of 
 iron bent in horse-shoe form, coated with varnish, and sur- 
 rounded with a spiral coil of naked copper wire. Shortly 
 afterwards, Professor Joseph Henry made his famous 
 experiments at the Albany Academy, which revealed for 
 the first time the extraordinary power of the electro-mag- 
 net. Henry followed the plan, previously suggested by 
 Schweigger, of covering his wire, instead of merely putting 
 the insulating material around the coil as Sturgeon had 
 done. With a magnet wound with twenty-six strands of 
 copper bell-wire covered with cotton thread, the aggre- 
 gate length of the core being 728 feet he had suspended 
 nearly a ton weight. Afterwards, with a small horse-shoe 
 of round iron, one inch in length and six-tenths of an 
 inch in diameter, wound with but three feet of brass wire, 
 he raised a weight 420 times greater than that of the mag- 
 net itself. Sir Isaac Newton describes a lodestone weigh- 
 ing three grains, which he wore in a ring, and which is 
 said to have raised 746 grains, or 250 times its own weight. 
 This is the greatest recorded strength of any permanent 
 magnet. Natural magnets, or lodestones, are stronger 
 than those artificially made. The former usually carry a 
 load of about twenty times, while the latter are rarely able 
 to lift a mass exceeding five times, their own weight. 
 Within recent years, however, very powerful permanent 
 magnets, equal to the lifting of twenty-five times their 
 own weight, have been constructed by M. Jamin ; the 
 advantage being gained through the use of very thin leaves 
 of thoroughly magnetized steel, bound together to form 
 the magnet. 
 
 Let us sum up some of the strange phenomena thus 
 
THE ELECTRO-MAGNET. 87 
 
 far briefly outlined. We have seen that the electrical 
 current is competent to produce effects not merely in its 
 channel or conductor, like water turning a wheel, 
 but to influence bodies entirely outside of that channel. 
 It causes, around its conductor, a peculiar aura or atmos- 
 phere like that around the poles of a magnet, but differing 
 from the latter as a whirlwind differs from a steady gale. 
 It converts the conductor into a magnet, which, like other 
 magnets, is capable of influencing magnetic bodies to be- 
 come magnets. It also converts magnetic bodies, around 
 which the conductor is wound, into magnets ; and a bar of 
 iron in this way is given all the properties which it would 
 have were it normally and naturally a magnet, or piece of 
 lodestone. This is an electro-magnet. But the magnetic 
 state of this bar is controllable. It is a magnet, or not, 
 in accordance as we permit the current to flow, or inter- 
 rupt it. As a magnet, the bar has different poles, at 
 opposite ends ; but these poles change reciprocally in 
 accordance with the direction of the current. By making 
 and breaking the current, we can make the electro-magnet 
 attract and release alternately a piece of magnetic mate- 
 rial, placed in front of either of its poles, and called an 
 armature. If, however, the armature be itself a magnet, 
 then we can make the electro-magnet attract or release it 
 without breaking the current, but by simply changing the 
 direction of the current, this because, when the magnet 
 opposes an unlike pole to the adjacent pole of the arma- 
 ture, the latter will be attracted ; but when the magnet 
 presents a like pole, the armature will not be attracted, or, 
 if already attracted, will be released. 
 
 Why the magnet, and the conductor carrying a current, 
 produce this singular atmosphere ; why other bodies act 
 as they do in that atmosphere ; what the medium is which 
 carries this unknown force between the separated magnet 
 and armature, are all unsolved problems. 
 
88 THE AGE OF ELECTRICITY. 
 
 CHAPTER VII. 
 
 THE DYNAMO-ELECTRIC MACHINE, AND THE CONVERSION OF 
 MAGNETISM AND MECHANICAL MOTION INTO ELECTRICITY. 
 
 Is electricity magnetism ? or is magnetism electricity? 
 Are these phenomena two different forms of energy? or 
 are they phases merely of the same form? The last is 
 probably true. 
 
 By means of the electric current, a body capable of 
 being magnetized may be, as we have seen, converted 
 into a magnet. We have now to note even more extraor- 
 dinary results following the reverse of this ; namely, the 
 production of electrical currents by magnets. 
 
 In the fall of 1831, Professor Faraday announced that 
 from a magnet he had obtained electricity. On the 8th 
 of February, 1832, he entered in his note-book: "This 
 evening, at Woolwich, experimented with magnet, and 
 for the first time got the magnetic spark myself. Con- 
 nected ends of a helix into two general ends, and then 
 crossed the wires in such a way that a blow at a b would 
 open them a little. Then bringing a b against the poles 
 of a magnet, the ends were disjoined, and bright sparks 
 resulted. ' ' 
 
 Next day he repeated this experiment, and then, as was 
 his habit, invited some of his friends to see the new light. 
 He had a piece of soft iron, surrounded by coils of wire 
 insulated with calico and tied by common string. When 
 
THE DYNAMO-ELECTRIC MACHINE. 
 
 89 
 
 he touched the pole of a magnet with the soft iron, the 
 ends of the coil, as he says, opened a little, and a spark 
 passed between them. An electrical current had been 
 caused in the coil, and Herbert Mayo described it in the 
 following neat impromptu : 
 
 "Around the magnet, Faraday 
 Was sure that Volta's lightnings play; 
 
 But how to draw them from the wire ? 
 He drew a lesson from the heart : 
 "Tis when we meet, 'tis Vhen we part, 
 Breaks forth the electric fire." 
 
 Faraday's experiment is very easily repeated with the 
 aid of the little apparatus represented in Fig. 35. The 
 operator holds in one 
 hand an ordinary horse- 
 shoe magnet, and in the 
 other a bar of iron around 
 which is wound a little 
 coil of insulated copper 
 wire. On one end of 
 the coil is a small disk 
 of copper. The other 
 end is sharpened to a 
 point, and brought in 
 contact with the disk. 
 On placing the bar across 
 the poles of the magnet, 
 and then suddenly breaking contact, the point and the 
 disk become separated at the same time, and the spark 
 appears. 
 
 Some fifty years earlier, one of those intensely practical 
 individuals who see no outcome in the results of scientific 
 discovery unless the same can be immediately estimated 
 
 Fig. 35. 
 
90 THE AGE OF ELECTRICITY. 
 
 at a money value, rather superciliously asked Franklin 
 what use there was in the facts proved by certain of his 
 experiments. 
 
 44 What's the use of a baby? " the philosopher retorted. 
 
 Faraday's reply to those who saw nothing gained by the 
 development of the little spark, and who demanded its 
 utility, was equally sententious. "Endeavor to make it 
 useful," he said. He left to others the immediate work 
 of doing so. Some twenty-five years later, he saw that 
 tiny flash expanded into the magnificent blaze of the 
 famous South Foreland light-house. To-day it illuminates 
 the thoroughfares of the great cities of the civilized 
 world. 
 
 The first practical magneto-electric machine was con- 
 structed by M. Hippolyte Pixii of Paris, in September, 
 1832. His apparatus consisted of an ordinary horse-shoe 
 magnet, under the poles of which a powerful steel horse- 
 shoe was rotated by a shaft. On the steel horse-shoe was 
 coiled a wire ; and as the ends of the horse-shoe were moved 
 up to and removed from the poles of the magnet, electric 
 currents were produced in the coil. The best form of 
 this apparatus was probably that produced by Clarke 
 of London, in 1834. This is represented in Fig. 36. It 
 embodies a large permanent magnet AB, beside the poles 
 of which are rotated two pieces, or cores, of soft iron, 
 each encircled by a coil of fine wire, and mounted at the 
 ends of arms supported on a horizontal shaft ; the shaft 
 being rotated by turning the large belt-wheel by its handle. 
 When the coils are rotated in front of the magnet, cur- 
 rents are produced in them. The coils are connected to 
 separate metal plates on each side of the shaft, from 
 which plates the current is led, by springs touching them, 
 to binding-posts to which conducting-wires may be 
 attached. 
 
THE DYNAMO-ELECTRIC MACHINE. 
 
 91 
 
 It will be apparent that these machines are merely 
 convenient mechanical contrivances for doing just what 
 Faraday did in the little experiment first described in this 
 chapter. We have, however, by no means recognized all 
 that Faraday then discovered. 
 
 Fig. 36. 
 
 As we have seen, he determined that an electrical cur- 
 rent was produced in a closed coil of wire when a magnet 
 was brought up to the coil, or the reverse. The coil 
 might be moved in front of the pole of the magnet, as in 
 
92 
 
 THE AGE OF ELECTRICITY. 
 
 Fig. 87. 
 
 Clarke's machine above described ; or the magnet may be 
 moved up to or into the coil, as represented in Fig. 37. 
 In the latter case, the ends Jf' of the coil may be connected 
 with a galvanometer, which will 
 reveal the presence of the current. 
 It must not be understood that 
 the mere proximity of the magnet 
 to the coil produces any current, 
 for that is not the fact. It is the 
 motion of the coil to the magnet, 
 or of magnet to coil, which pro- 
 duces the current. The actual 
 mechanical work which we per- 
 form in moving either coil or mag- 
 net is converted into the other 
 form of energy which we call elec- 
 tricity. But how this is done, is not 
 easy to realize. We have seen that all around a magnet 
 exists the so-called field of force, and that magnetic 
 bodies become magnets on being simply placed therein. 
 Here, however, is a new property of that mysterious at- 
 mosphere. If a closed circuit is moved in that Held, a 
 current will traverse the wire ; or if the field itself, by 
 moving the magnet, 
 be brought nearer to 
 or farther from the 
 coil, the same thing 
 will happen. 
 
 It is necessary, 
 however, that the 
 motion should be 
 
 made in a certain way ; that is, so that, by reason of the 
 change of its position, either more or less of these singu- 
 lar endless lines of force which make up the magnetic 
 
THE DYNAMO-ELECTRIC MACHINE. 
 
 93 
 
 field shall pass through the coil. There are various ways 
 of doing this. We can move our coil from a place where 
 the lines of force are very numerous, as near the pole 
 of a magnet, to a place where they are not so numerous, 
 as indicated by the positions 1 and 2 of the ring in Fig. 
 
 Fig. 39. 
 
 Fig- 40. 
 
 38, or 1, 2, and 3, in Fig. 39. Or, we can turn the coil 
 on its axis, as in Fig. 40 ; in which case, fewer lines of 
 force will pass through it when it lies horizontal than when 
 it stands upright. Or, we can move the coil simply past 
 the pole, as in Fig. 41 ; the coil here travelling in the 
 
 direction of the arrow successively into the positions 1, 2, 
 3, so that it thus moves into and out of the field of the 
 magnet. If, however, the coil should be so moved that 
 the number of lines of force passing through it is not 
 changed, then no current would be produced in its con- 
 volutions. 
 
94 
 
 THE AGE OF ELECTRICITY. 
 
 We can easily imagine lines of force extending from the 
 pole B of the magnet in Fig. 37 ; and hence it will be 
 apparent that more or less of these lines will be cut, or, 
 rather, that more or less of them will enter the enclosing 
 coil, whether the magnet be moved into or out of the coil, 
 or, conversely, whether the coil be moved on and off the 
 magnet. 
 
 If, for the permanent magnet of Fig. 37, we substitute 
 an electro-magnet as in Fig. 42, the results will be the 
 
 same. The field of force now 
 produced at the pole or end of 
 the core resembles the field of 
 force of the natural magnet ; 
 and the same movements of 
 either coil or magnet, as de- 
 scribed with reference to the 
 preceding figure, will cause 
 currents in the large coil. 
 
 Fields of force, however, 
 exist not merely around the 
 poles of magnets, but around 
 wires conveying currents ; and 
 the properties of the atmos- 
 pheres, in either case, are simi- 
 lar. If this be true, then it 
 should follow, that if, in Fig. 42, we remove the magnet 
 bar altogether, and retain simply the wire coil, the current 
 circulating in that coil should produce around it a field 
 of force which should set up a current in another and 
 adjacent coil. This is the fact, and it forms a later dis- 
 covery by Faraday. 
 
 In Fig. 43, the small coil of wire connected with the 
 battery, and hence conveying a current, is introduced into 
 and removed from the large coil connected with the gal- 
 
 Fig. 42. 
 
THE DYNAMO-ELECTRIC MACHINE. 
 
 95 
 
 vanometer. Whenever this is done, the galvanometer 
 needle swings, proving the existence of a current in the 
 larger coil. 
 
 So far, we have dealt with moving bodies. A magnet, 
 permanent or electro, moved with reference to a closed 
 coil, produces in the latter a current. The coil, moved 
 with reference to the magnet, accomplishes a like result. 
 A coil of wire in which a current is flowing, moved with 
 reference to a closed coil in which there is no current, 
 
 Fig. 43. 
 
 causes a current in the latter : conversely, if the closed 
 coil be moved. In all of these cases, it is the energy of 
 motion, as we have stated, which causes the electrical 
 current. 
 
 There is, however, one instance where we can cause a 
 current in the closed coil, from the coil in which the cur- 
 rent is circulating, without moving either of the coils ; and 
 that is simply by starting and stopping the current. The 
 coils are placed in proximity, .as one within the other, and 
 so fixed. When there is no current in one coil, there is 
 
96 THE AGE OF ELECTEICITY. 
 
 of course no atmosphere of force to enter the other. The 
 instant the current is established, the atmosphere exists. 
 It comes into being, and affects the outer coil, for example, 
 the same as if the inner coil were moved into it. So, when 
 it disappears, the effect is as if the inner coil were moved 
 out. This is the principle of the inductorium, or induction 
 coil, which is fully described in another chapter. 
 
 To recapitulate, therefore : If we bring a closed coil of 
 wire into the strange magnetic atmosphere, we shall cause 
 a current in the coil. So when we take it out. So when 
 we move it from a dense to a thin part of the atmosphere, 
 or vice versa. And it makes no difference, in substance, 
 whether we bring the coil into the atmosphere, or move 
 the atmosphere (by moving the thing which it surrounds) 
 into proximity to the coil, or cause the atmosphere sud- 
 denly to come into existence around the coil. 
 
 Whatever happens is the result either of the coming 
 into or going out of existence, or of proximity, of the 
 magnetic atmosphere, with relation to the coil ; or of 
 changes in the position of the coil in that atmosphere. 
 To speak .of the coil enclosing more or less of the lines of 
 force, and the current in the coil attending the change, is 
 one convenient way of realizing what occurs. We can 
 express the same idea by saying, that, in order that the 
 coil may have a current in it, it must cut the lines of force 
 in its motion, that is, move across them. These theories 
 are, however, waning. The more modern view is, that the 
 molecules of the wire in the coil are in a condition of 
 equilibrium, liable to instant change ; and this occurs the 
 moment the particles enter the magnetic atmosphere, or 
 field of force, where they become subject to new strains 
 and stresses, which introduce new conditions of balance. 
 In effecting the necessary molecular changes, an expendi- 
 ture of energy is involved, which results in the current. 
 
THE DYNAMO-ELECTRIC MACHINE. 97 
 
 This theory has been very fully elaborated by Professor 
 Sprague. 
 
 Of course the three theories are, after all, only different 
 ways of saying the same thing. If a coil moves from one 
 part of the field to the other, so that more or less lines of 
 force pass through it, it must cut or pass across lines 
 of force in so moving ; and similarly, if, in order to have a 
 current caused in it, it must proceed from one part of the 
 field to another, in which the strains and stresses due to 
 the lines of force shall be different, it follows necessarily 
 that it must go to a place where different lines of force 
 (more or less) exist. 
 
 It is not necessary, however, to proceed farther into the 
 realm of theory. For present purposes it is sufficient to 
 recognize that there is a very broad distinction between 
 producing an electric current in a coil of wire by reason 
 of the actual motion of the coil in the magnetic field, or 
 of the field about the coil ; and by reason of the establish- 
 ment or change of strength in a magnetic field about a 
 stationary coil. In the one case, we convert the energy of 
 mechanical motion into electricity : in the other, the energy 
 of one current engenders another current. 
 
 With the apparatus wherein the character of the current 
 is changed by the induction of one stationary coil upon 
 another, we have nothing to do in this chapter. 
 
 We have frequently referred to the field of force which 
 surrounds the magnetic pole, or current-conducting wire, 
 as an atmosphere. This is a convenient way of thinking 
 of it ; but in fact it is nothing material or tangible, as the 
 air, for example, is which surrounds our earth. The same 
 effects are present, even when the most perfect vacuum 
 exists around the magnet ; so that it is probable that the 
 magnetic action is propagated through space, by move- 
 ments or pressure in the ether which is supposed to per- 
 
98 THE AGE OF ELECTRICITY. 
 
 vade the entire universe, to exist between the atoms of 
 all bodies, however solid, as an infinitely thin though jelly- 
 like medium. 
 
 One other important fact remains to be noted, before 
 we examine the construction of the machines which pro- 
 duce electricity ; and that is the changes in the direction of 
 movement of current in the coil. In referring to the elec- 
 tro-magnet, in the preceding chapter, we have found that 
 the poles of the magnet depend on the direction of the 
 current traversing the wire, and that we can reverse the 
 pole simply by reversing the direction of the current. 
 The direction of the current of a coil which is moving in 
 a magnetic field depends upon whether the coil is moving 
 from a place where it encloses more lines, to a place where 
 it encloses less lines, or the reverse. The current moves 
 in one direction in one case, in the opposite direction in 
 the other ; and we shall' presently see the effect of this 
 reversal in practice. 
 
 In the upper part of the Western Union Telegraph 
 Company's building in New York, there is a large room 
 in which are disposed tier upon tier of galvanic cells. 
 There is no clatter and rush of machinery, no noise except 
 such as rises from the busy street without, or comes from 
 the numberless telegraph-instruments in another part of 
 the building. Here are generated the electrical currents 
 which are to find their way over thousands of miles of 
 wire, and carry the messages of the great metropolis 
 throughout the country. 
 
 Not far from the telegraph-offices is the establishment 
 of one of the corporations which provide the electric 
 lights which now illuminate the city thoroughfares ; and 
 here are generated the currents which feed these miniature 
 suns. But now, instead of the perfect silence with which 
 
THE DYNAMO-ELECTRIC MACHINE. 99 
 
 the mighty forces of chemical affinity do their work in the 
 battery, there is the thunder of great engines, the roar of 
 the escaping steam, and the bewildering whirr of the huge 
 dynamos. The visitor is warned away from the wires : it 
 is death to touch them. Here and there are brilliant flashes 
 of light. An odd odor is in the air. But above all there 
 is motion, as driving, as headlong, as impetuous, as 
 unremitting, as that of the locomotive in its hurried 
 course. 
 
 As we become accustomed to the confusion and noise, 
 we find that the source of power is a steam boiler, and 
 that the steam drives a steam-engine, no different from 
 other steam-engines except that it is constructed to run 
 with especial steadiness and uniformity. The work of 
 this steam-engine is to turn the "dynamo; " and in and 
 by the dynamo, the electricity is produced. This is ob- 
 viously very unlike the production of the current by a 
 battery. There are no chemicals here, no zinc consumed. 
 The engine simply rotates the dynamo shaft ; and in the 
 wires leading from the machine the current circulates, and 
 goes to the lamps. 
 
 The idea will perhaps occur to us, that, inasmuch as 
 here is a machine which is rotated, and which produces 
 electricity, we perhaps have in the dynamo only some 
 more modern and improved form of the old frictional or 
 static machine, in which the glass or sulphur cylinder is 
 excited by rubbing. This is very wide of the truth. If 
 we could see into the dynamo, and it is quite possible 
 to do so, in some forms of the apparatus, we should at 
 once discover that the thing revolved does not rub against 
 any thing, but apparently turns freely in the air. We 
 should also notice that the revolving object is substantially 
 a solid mass ; that there is nothing moving inside of it. 
 On closer examination, we should find it to be a bundle 
 
100 THE AGE OF ELECTRICITY. 
 
 of wires ; and if we examined the mass of metal which 
 surrounds this rotating mass of wire, we should find that 
 the same was a magnet or perhaps several magnets. 
 
 We thus recognize the dynamo as a machine wherein 
 coils of wire are moved in a very intense magnetic field 
 produced by the encompassing magnets ; and, from what 
 has been before explained, we know that it is simply 
 requisite to dispose these coils so that they will be carried 
 through this field, embracing at times more and at times less 
 of the pervading lines of force, to cause in them currents of 
 electricity. This, however, is exactly what is done in the 
 old Clarke magneto machine, represented in Fig. 36 ; so 
 that there is no difference in principle between the dynamo 
 and the magneto-electric machine as an electrical generator. 
 
 But we shall further find, that in lieu of the perma- 
 nent magnet, for producing the field, the dynamo has an 
 electro-magnet ; and we have seen that the strength of 
 an electro-magnet is not a permanent and fixed quantity, 
 but, up to the point of so-called saturation, depends upon 
 the strength of the current in the coils surrounding its core. 
 In this way we can make immensely strong magnets, and, 
 consequently, immensely strong fields of force ; and, the 
 stronger the field, the more lines of force there are in 
 it. Hence if we rotate coils of wire through that field, they 
 will cut large numbers of lines of force ; and the conse- 
 quence of this is very strong currents produced in the coils. 
 And thus it becomes possible to obtain, from dynamo- 
 electric machines, currents of electricity far stronger and 
 more powerful than ever could be got from magneto- 
 electric machines. 
 
 Let us now analyze this mechanical generator of elec- 
 tricity a little more closely. The two principal parts of 
 the machine are the magnets which make the field of lines 
 of force, or the field-magnets, and the body which 
 
THE DYNAMO-ELECTRIC MACHINE. 
 
 101 
 
 r 
 Iron 
 
 Fig. 44. 
 
 revolves in that field. This body is called the armature ; 
 and it consists of a core or mass of magnetic metal, such 
 as iron, and the coils wound thereon. We have already 
 seen, that, when an armature of iron is placed before the 
 poles of a magnet, 
 the lines of force 
 will apparently run 
 into the armature. 
 Consequently, if we 
 place the coil which 
 is to receive and to 
 cut these lines of 
 force, on an iron 
 body, we place it on 
 something which will 
 apparently draw the 
 lines of force into the coil. If we made the support for the 
 coil of wood, for example, then very much fewer lines of 
 force would pass through the coil. This difference will be 
 clear from Figs. 44 and 45, which show the lines passing to 
 
 an iron armature, and the lines 
 unaffected by the wooden one. 
 Now let us see what happens 
 when a coil which, for con- 
 venience, we will represent by 
 a simple ring moves around 
 between two strong magnetic 
 poles. In Fig. 4G, these poles are represented at N and 
 S ; the ring is supposed to assume the several positions 
 represented. We are going to see a paradoxical state of 
 affairs, which will require some thought which the reader 
 can avoid, if he chooses, by skipping the next page or so, 
 and reading only the conclusion of the explanation. 
 The lines of force pass almost directly between the 
 
 N 
 
 Fig. 46. 
 
102 THE AGE OF ELECTRICITY. 
 
 poles, as represented by the dotted lines. Beginning at 
 the left, the ring at first stands nearly horizontal, so 
 that hardly any of the lines of force thread through it. 
 As it is carried upward and around, in the direction of 
 the arrow, toward a vertical position, the number of lines of 
 force passing through, however, increases ; and a current 
 is set up in the ring, in the direction of the small arrows. 
 As it moves farther, it receives more and more lines ; 
 and finally when it reaches the central point, marked by 
 the vertical dotted line, the number of lines passing 
 through reaches a maximum. Then the ring begins to 
 turn flat-ways again ; the lines passing through it now 
 commence to decrease in number, and the current in the 
 ring changes direction. The decrease in the lines goes 
 on until the ring becomes once more horizontal. Now the 
 ring enters the lower right-hand quadrant, and begins to 
 thread more lines of force. But here the current does 
 not appear to change direction. This is because we have 
 reversed the ring itself, and the lines of force are entering 
 the opposite side from that hitherto presented ; so that, 
 although we have an increase in the lines of force, the 
 current apparently continues in the same direction. This 
 state of affairs goes on until the ring passes the central 
 point, when the lines of force running through it begin to 
 decrease. This reverses the current in the ring, which 
 after passing through the left-hand lower quadrant reaches 
 its starting-point. 
 
 It is not particularly easy to understand this, chiefly 
 because it is necessary to bear in mind both the reversal 
 of the current and the reversal of the ring. The current 
 changes in space on passing the pole where the lines de- 
 crease or increase, so that there is no variation from the 
 law. But it does not change with reference to the ring. 
 This can be shown rather neatly in the following way : 
 
THE DYNAMO-ELECTRIC MACHINE. 103 
 
 Let the black circle of Fig. 47 represent the ring, with the 
 currents flowing in it in the direction of the arrows, 
 that is, in the direction in which the hands of a watch 
 move. Now let the reader hold this page up to the light, 
 and look at the figure from the rear of the page. It will 
 look like Fig. 48. According to the 
 arrows, the current will be moving op- 
 posite the hands of a watch, and in just 
 the reverse direction from before. That 
 comes from simply reversing the ring. 
 Suppose, however, that when we looked 
 at the ring reversed by ourselves, the 
 currents reversed simultaneously on 
 their own account : then, instead of the arrows appearing 
 as in Fig. 48, they would appear in the reverse direction as 
 in Fig. 49. But Fig. 49 is just the same as Fig. 47 , which, 
 as the geometry says, was to be proved. 
 
 The sum and substance of all this is, that, when the 
 coil is carried around in front of the poles, the current 
 produced in it reverses in direction every time it passes 
 the neutral line between the poles. 
 This is what electricians call an alter- 
 nating current ; and, while it is not 
 particularly important for the non-pro- 
 fessional reader to consider very deeply 
 why or how it thus alternates, it is of 
 48. some moment that the difference be- 
 
 tween what is meant by an alternating 
 current which is constantly changing its direction like 
 a pendulum, and a continuous direct current which flows 
 but in one way like a river, be understood. From the 
 difference in their capacity to produce either au alternat- 
 ing or a continuous direct current, dynamo and magneto 
 electric machines may be divided into two distinct classes. 
 
104 THE AGE OF ELECTRICITY. 
 
 Returning now to Fig. 46, it will be apparent, that, 
 if we arrange a number of coils around a circular disk, 
 and between the poles of a magnet, we shall get alter- 
 nating currents from each coil, and thus a succession of 
 rapid alternations as the coils move swiftly past the neutral 
 points between the poles. If we had but a single coil, 
 then, in addition to the current constantly changing direc- 
 tion, it would, while flowing, vary in strength. This dif- 
 ficulty we overcome, in a measure, by multiplying the coils 
 so that each shall be brought successively into operation, 
 the current beginning in one coil before it has ceased in 
 another. 
 
 Alternating currents are very useful in many cases, but 
 for most purposes we need a direct, 
 continuous flow. We find alternating 
 action in mechanical devices very useful 
 in pumps and steam-hammers ; but if a 
 locomotive, for example, could be moved 
 only a little way in one direction, and 
 then a little way in the other, it would 
 not be of much use to draw trains. 
 Yet this is how the piston in the locomotive-cylinder 
 travels ; and the piston, in turn, moves the whole great 
 machine. But the locomotive does not follow the to-and- 
 fro movement of the piston ; because, when that move- 
 ment reaches the wheels, it is converted into a uniform 
 rotary movement by the crank, which pushes the wheel 
 above the hub, and pulls it below, so that the wheel can 
 turn in one direction, and the engine goes straight ahead. 
 There is a little contrivance connected with alternating- 
 current machines, called a commutator, which does for the 
 alternating current about what the crank does for the alter- 
 nating steam-pressure. In its simplest form this is repre- 
 sented in Fig. 50, and it can be seen on a small scale in 
 
THE DYNAMO-ELECTEIC MACHINE. 105 
 
 the engraving of Clarke's magneto machine, Fig. 36 
 This consists of a simple piece of brass or copper tube, 
 slit longitudinally into two portions, and fixed upon the 
 axis of revolution of the armature so as to revolve with 
 it ; the two halves of the split tube being fixed upon a 
 small cylinder of ivory or other insulating material. One 
 half of the tube is attached to one end of the wire of the 
 coil, or, where there are several coils, to like ends of 
 the wires of all the coils, and the other half to the other 
 end or ends. Against the split tube are pressed two 
 springs or brushes, A A. 
 Suppose the armature 
 carrying the coil or coils 
 to be rotating in the direc- 
 tion indicated by the arrow 
 in the engraving. During 
 one half of the revolution 
 the current will flow to- 
 
 Fig. 50. 
 
 ward the commutator, and 
 
 during the other half the current will flow from it ; be- 
 cause, as we have seen, the current reverses during each 
 revolution of the coil. Now, as each end of the wire is 
 connected to a separate part of the commutator, it follows 
 that while the armature is passing one part of its revolu- 
 tion, say, the upper part, the current will flow to 
 the commutator plate which is uppermost ; and while the 
 armature is completing the other part of its revolution, 
 the current (reversed) will flow from the other, or lower, 
 commutator plate. Consequently each half of the split 
 tube will, as it passes over the top of its axis, deliver to 
 the upper contact spring or brush the current flowing into 
 it, while the lower contact brush will always (apparently) 
 be feeding the return currents back to the lower half of 
 the split commutator tube. So that, if we connected our 
 
106 
 
 THE AGE OF ELECTRICITY. 
 
 circuit wires to the two brushes, or springs, we should 
 have a continuous current flowing in the wire from the 
 upper brush to the lower one. 
 
 In general it may be stated, that, in all apparatus of the 
 alternating-current type, there are a number of coils placed 
 on the rim of a wheel which revolves, and is surrounded 
 by fixed magnets. Alternating currents that is, cur- 
 rents alternately in opposite directions are produced in 
 the coils, and are either used as alternating currents, or 
 
 N 
 
 Fig. 51. 
 
 are converted into direct currents by being passed through 
 a commutator before they go to the line wire. 
 
 There are two types of direct-current machines, known 
 after their inventors as the Gramme and the Siemens 
 forms. A simple diagram of the Gramme apparatus is 
 given in Fig. 51. The armature is a ring of soft iron, 
 around which the wire is wound in a continuous spiral, 
 forming a closed circuit. It revolves between two poles 
 of opposite names, the lines of force from which termi- 
 nate in the ring ; as shown in Fig. 52, which represents a 
 section made through Fig. 51 by a plane in the line NS 
 
THE DYNAMO-ELECTRIC MACHINE. 
 
 107 
 
 of Fig. 51 and at right angles to the plane of the paper. 
 As the ring revolves, these lines of force are cut by the 
 
 Fig. 52. 
 
 moving wires, and electro-motive forces are generated in 
 the two halves of the ring, in opposite directions, so 
 that they meet and op- 
 pose one another at the 
 neutral points JVP, as in 
 Fig. 53. As long as no 
 further connections are 
 made, no current is gener- 
 ated. If, however, the/y 
 points NP are connected 
 by a wire in circuit, through 
 a number of lamps, for ex- 
 ample, as in Fig. 54, then 
 a current will flow from 
 P to N. In order to col- fig. 63. 
 
 lect the currents from the 
 
 ring, a special device, called a collector, is employed. 
 This is usually made of a cylinder of wood or other 
 
108 
 
 THE AGE OF ELECTRICITY. 
 
 insulating material, upon which are placed longitudinally 
 a number of insulated metal strips. Each strip or bar is 
 connected by a wire to the part of the spiral coil imme- 
 diately opposite to it, as represented in Fig. 55. At the 
 points PN, where the opposite electro-motive forces diverge 
 and join again, two metal brushes rub against the strips ; 
 and with these brushes the external circuit is connected. 
 
 Fig. 54. 
 
 The second type of direct-current dynamo emplo} T s the 
 Siemens or drum armature, in which the coils of wire are 
 wound lengthways over a drum or spindle ; the wire being 
 carried along the drum parallel to its axis, across the end, 
 back along the drum on the side opposite, and so around 
 to the starting-point ; the separate turns, or groups of 
 turns, being spaced out at regular intervals all around the 
 
THE DYNAMO-ELECTRIC MACHINE. 
 
 109 
 
 Fig. 55. 
 
 drum. This method of winding is illustrated in Fig. 56. 
 In each of the wires, as it rises past the south pole, cur- 
 rents are generated which flow towards the front ; whilst 
 in the other half of 
 their revolution, in 
 descending past the 
 north pole, the cur- 
 rents generated in 
 them flow from the 
 front towards _ /y 
 the back. The 
 method of joining the 
 coils to the commuta- 
 tor bars insures that 
 the currents shall fol- 
 low one another, and 
 flow into the upper 
 contact brush. 
 
 We have now recognized the two principal types of 
 mechanical electrical generators, namely, the alternat- 
 ing-current apparatus and the direct-current apparatus ; 
 the difference being in the construction of the armature. 
 
 The magnets may 
 be either perma- 
 nent or electro, so 
 that the classifi- 
 cation applies to 
 either magneto or 
 dynamo electric 
 
 ~ ~ * x machines ; but in 
 
 fact all so far 
 
 described was invented some years before the modern 
 dynamo may be said to have begun its existence. 
 
 The Siemens armature was devised by Dr. C. W. Sie- 
 
110 THE AGE OF ELECTRICITY. 
 
 mens, in 1856 ; and the continuous-ring armature was con- 
 trived by Dr. Pacinotti of Florence, Italy, in 1860. The 
 compound multipolar armature dates back farther than 
 either. 
 
 In 1867 Mr. H. Wilde replaced the permanent field-mag- 
 nets by electro-magnets ; and these he excited by means 
 of a small separate magneto electric machine having 
 itself permanent steel magnets. This was a very ma- 
 terial improvement ; because the small magneto machine 
 utilized all its current in exciting the electro-magnets of 
 the larger apparatus, which thus were enabled to produce 
 a very intense field of force. Following this came the 
 quadruple yet independent discoveries of Hjorth, Varley, 
 Siemens, and Wheatstone, that there was no need of a 
 separate exciting machine, for the generator could be 
 made to excite itself. This is somewhat paradoxical at 
 first, but in reality not at all difficult to understand. It 
 is necessary, to begin with, that the field magnets should 
 have some little magnetism of their own. A very little is 
 quite sufficient. If they are magnetic at all, they have 
 a field of force ; and in the coils of an armature rotating 
 in that field, there is therefore produced a very weak 
 current. 
 
 Now suppose that the wire which constitutes the arma- 
 ture coil forms also the enveloping coil of the field-mag- 
 nets : then the current produced on the armature will 
 circulate around the field - magnets, and increase their 
 magnetism. Then, of course, their field of force will 
 become stronger, and so will the current in the arma- 
 ture ; and in this way the cycle will be completed. The 
 result is, that, in a few seconds after the armature is 
 set rotating, the field-magnets are magnetized to satura- 
 tion, or to as great a degree as they are capable of 
 reaching. This is called the dynamo electric machine ; 
 
THE DYNAMO-ELECTRIC MACHINE. 
 
 Ill 
 
 in centra-distinction to the apparatus already described, 
 wherein the magnets are permanent, or always of the 
 same strength. 
 
 When the dynamo is intended to produce alternating 
 currents, the separate-excitation system is employed. This 
 is illustrated in Fig. 57. A small separate magneto ma- 
 chine, not shown, energizes the large field-magnets S N 
 by circulating in the coil surrounding the same, as shown 
 
 Fig. 57. 
 
 Fig. 58. 
 
 by the arrows. The current produced by the dynamo, 
 whose magnets are thus excited, moves in a separate 
 circuit, as shown. 
 
 Fig. 58 represents- a self-exciting dynamo, on what is 
 termed the series system. Here the current, taken at one 
 of the brushes of the commutator, passes around the field- 
 magnets, and then through the main circuit, and so back 
 to the other brush. 
 
 Fig. 59 represents a self-exciting dynamo on the so- 
 
112 
 
 THE AGE OF ELECTRICITY. 
 
 called shunt system. In this arrangement, the current 
 is divided ; part going from the brushes around the mag- 
 nets by way of the thin line of wire, and part going by 
 the main line to the external circuit. 
 
 Various other arrangements of the circuit wires for ex- 
 citing the field-magnets in dynamos have been invented. 
 The foregoing are, however, the most important. 
 
 Inasmuch as the currents pro- 
 duced by a dynamo-electric gener- 
 
 L| _____ ator depend upon the cutting of 
 
 tj | \ the lines of the field of force by 
 
 the armature, it follows that it is 
 necessary, in order to obtain pow- 
 erful currents, to cause the arma- 
 ture coils to cut as many of these 
 lines as possible in the shortest 
 time. To this end, the armature is 
 made to rotate very rapidly, and 
 is given a large number of turns 
 of wire, or coils enclosing as much 
 area as possible. In order that the 
 current may not be wasted in over- 
 coming the resistance of the arma- 
 ture coils, these are made to offer as little resistance as 
 possible ; and, finally, as the number of lines of force 
 to be cut depends on the strength of the field of force, 
 the field-magnets are placed to concentrate the lines of 
 force as much as possible across the space where the 
 armature revolves. 
 
 There is an immense variety of forms of dynamo and 
 magneto electric apparatus ; and to review them, even in 
 the briefest manner, would far exceed our present limits. 
 Only a few typical machines are therefore given. 
 
 Fig. GO represents the De Meritens magneto-electric 
 
 Fig. 59. 
 
THE DYNAMO-ELECTRIC MACHINE. 
 
 113 
 
 machine. This contains one or more rings carrying coils 
 which revolve between the poles of powerful steel magnets. 
 As the wheel revolves, the polarities of the cores are con- 
 stantly reversed, and currents are therefore induced on 
 
 Fig. 60. 
 
 the wires. The ring is of light brass, and the coils are 
 wound upon iron cores. This is an example of an alter- 
 nating-current magneto machine. 
 
 An alternating-current dynamo is represented in the 
 
114 
 
 THE AGE OF ELECTRICITY. 
 
 Siemens machine shown in Fig. 61. This consists of 
 two fixed iron rings carrying electro-magnets, which are 
 excited by a small auxiliary direct-current machine. The 
 polarity of the magnets in each ring is alternately north 
 and south, and the polarity of each is opposite to that of 
 
 Fig. 61. 
 
 the magnet facing it on the other ring. Each magnet has 
 an extended flat pole plate, as shown. Between the two 
 rings of magnets, revolves a wheel partly of wood, partly 
 of metal, carrying in its circumference a number of coils 
 equal to the number of magnets in each ring. As the 
 wheel revolves, currents are induced in these coils in the 
 
THE DYNAMO-ELECTRIC MACHINE. 
 
 115 
 
 manner already explained. The currents are taken off by 
 springs. 
 
 The Brush machine belongs to the same general class 
 as the foregoing, but differs in the construction of its 
 armature, which consists of a wrought-irou ring, around 
 which the wire is wound in the hollow channels, as shown 
 in Figs. 62 and 63. The ring revolves between magnets 
 having extended pole pieces, the two opposed poles at the 
 same side of the ring being of the same name. 
 
 The Siemens machine represented in Fig. 64 has an 
 armature in the form of an 
 iron cylinder, around which 
 the wire is wound longitu- 
 dinally so that the wire is 
 parallel to the axis. The 
 collector consists of a num- 
 
 Fig. 62. 
 
 Fig. 63. 
 
 ber of strips of metal fixed on an insulating barrel. The 
 magnets are bars of wrought iron, straight at the ends and 
 curved in the middle. The current in the magnetizing-coils 
 has such directions that the whole of the curved portion of 
 the magnets at the top of the machine has one polarity, 
 and that at the bottom of the machine the opposite. The 
 outer ends of the upper and lower magnets, which are of 
 opposite polarities, are connected by yoke plates in the 
 usual way. 
 
116 
 
 THE AGE OF ELECTRICITY. 
 
 Fig. 65 represents a large Edison machine. The arma- 
 ture consists of a number of disks of thin iron plate, sep- 
 arated by paper, and grouped together to form a barrel 
 about three feet six inches in length. A number of cop- 
 per bars are laid on the circumference of this barrel, par- 
 allel to the axis. The diameter of the barrel outside the 
 bars is twenty-eight and a half inches. The bars are con- 
 nected so as to form a continuous circuit, analogous to 
 
 Fig. 64. 
 
 the longitudinally wound wire in the Siemens machine. 
 The whole armature revolves between the poles of a very 
 large electro-magnet ; these poles being immense blocks 
 of cast iron, which nearly meet, but are kept apart by the 
 brass distance pieces seen in the front of Fig. 65. The 
 lines of force from the magnets terminate in the central 
 iron barrel. The magnet coils are twelve in number, and 
 are each eight feet long. This machine will maintain 
 from a thousand to twelve hundred lamps of sixteen- 
 
Fig. 65. 
 
THE DYNAMO-ELECTRIC MACHINE. 117 
 
 candle power each. Its total weight is about twenty-five 
 tons. 
 
 The foregoing examples will suffice to give a general 
 idea of how dynamos are constructed. Of the two prin- 
 cipal types, those which give the direct current are the 
 best for general use. For electro-plating and other electro- 
 lytic operations, a direct current is, in fact, essential ; and 
 it is necessary, of course, to maintain the continuous mag- 
 netization of electro-magnets. 
 
 Alternating-current machines are simpler in construc- 
 tion ; and their current, as will be seen hereafter, is espe- 
 cially adapted to incandescent lamps. They cannot excite 
 their own magnets, nor can they drive existing electro- 
 motors. Good dynamo machines will return from seventy 
 to eighty per cent of the power expended in driving them, 
 in the form of electricity. This, however, refers to large 
 machines : small apparatus, intended to be driven by hand, 
 cannot be depended upon to utilize much over one-fifth of 
 the power ; and, in fact, it is better not to use the dynamo 
 on a small scale, but in such case to substitute permanent 
 magnets for the electro-magnets. One of the best forms 
 of machines of this class contains a Gramme ring arma- 
 ture, revolving between cast-iron pole pieces fitted with a 
 form of magnet devised by M. Jamin. The Jamin mag- 
 nets are exceedingly powerful, and are made of successive 
 layers of hoop-steel let into and riveted to the pole pieces. 
 
118 THE AGE OF ELECTRICITY. 
 
 CHAPTER VIII. 
 
 THE ELECTRIC LIGHT. THE CONVERSION OF ELECTRICAL 
 
 ENERGY INTO HEAT AND LIGHT. 
 
 WHEN a current of electricity flows along a wire, it is 
 opposed by the resistance of the wire ; just, for example, 
 as a current of water is retarded by its friction against 
 the pipe which encloses it. Every one knows that when 
 a body is rubbed against another body, friction results. 
 When there is friction, there is heat ; and when there is 
 much friction, the heat may become intense enough to set 
 either or both bodies on fire if they are of inflammable 
 material, or, if not inflammable, to cause them to glow or 
 become red or white hot. The ordinary friction-match is 
 an example of an inflammable body thus set on fire. The 
 line attached to a whaler's harpoon, after the whale is 
 struck, is dragged over the side of the boat so rapidly 
 that water must be poured on it to keep the wood rubbed 
 from being set on fire. The brake-shoes of a railway- 
 car, rubbing against the wheels when the brakes are put 
 down, cause, by their friction, brilliant streams of intensely 
 heated minute particles of iron. The journals of these 
 wheels, or of any machinery, become highly heated by 
 the rubbing friction when no lubricant is present. A 
 piece of iron pounded smartly with a hammer becomes 
 hot. The striking of a bullet or cannon-ball upon a mass 
 of iron is attended by intense heat produced at the place 
 
THE ELECTRIC LIGHT. 119 
 
 of impact, and a bright flash of light. We apply friction 
 to members of the body benumbed by cold, rubbing 
 our hands together to warm them. 
 
 Of course it should not be understood that there is 
 really mechanical friction between a current of electricity, 
 and the wire through which it passes. As has already 
 been explained, we speak of electricity as a thing, or 
 corporeal substance, merely for convenience' sake in talk- 
 ing about it. Its effect, however, in traversing a con- 
 ductor, resembles that which might follow the movement 
 of a body through that conductor, despite the apparent 
 solidity of the latter, in that the conductor becomes the 
 more heated as it offers more resistance to the flow. 
 Consequently, the more resistance there is, the more of 
 the energy of the current is expended in overcoming it ; 
 the more work is done at the place where it is overcome. 
 Just as the energy of the movement of the hand which 
 strikes a friction-match is converted into the heat which 
 raises the inflammable material to a condition when it 
 bursts into flame, so the energy of the seemingly moving 
 current in overcoming the obstacle offered by the wire 
 raises the temperature of the wire. If the wire is long 
 or thick, this elevation of temperature may be so much 
 distributed as not to be noticeable ; but if we make the 
 wire very thin, the heat produced may be sufficient to 
 cause it to become red hot or white hot and so dazzlingly 
 bright, or, if the wire is not of a refractory material, to 
 melt it. If, to illustrate, we connect the poles of a power- 
 ful galvanic battery with a short piece of fine platinum 
 wire, platinum because it will withstand a high tempera- 
 ture, we shall see the platinum become intensely hot 
 and glow. This is because the energy of the current, 
 opposed by the resistance of the very narrow path through 
 which it is driven, heats its channel. 
 
120 THE AGE OF ELECTRICITY. 
 
 As a fine red-hot wire will burn its way easily through 
 many substances, instruments containing such wires are 
 used in surgery for the performance of operations in 
 which the cautery of the wire attending its cutting action 
 is desirable ; and there have been devices proposed for 
 cutting timber and shearing sheep in the same way. In 
 these cases, the heat of the wire is utilized. 
 
 When the heat of a body of metal is greatly augmented, 
 it becomes intensely luminous, so much so, that it is 
 impossible to gaze upon molten steel in the furnace with- 
 out the aid of some means for protecting the eyes. The 
 sun itself is in this intensely heated and luminous state. 
 If we use a resisting body which will not melt, we can 
 raise its temperature so high by a strong electric current 
 that it will glow with a brilliancy which is exceeded only 
 by that of the sun ; and the luminosity so caused is 
 termed the electric light. 
 
 The electric light, therefore, is the direct application of 
 the heat produced by the energy of the electric current. 
 This energy is caused to overcome the resistance, usually, 
 of a short interval of highly resisting material, short 
 because it is advantageous to concentrate the heat, and so 
 have its utmost intensity in the smallest possible space. 
 
 The electric light is not produced from electricity. 
 This sounds paradoxical, but only so because of our false 
 thinking again of the current as a tangible thing. If we 
 start with a certain quantity of electricity, such, for 
 example, as is generated by the consumption of a given 
 amount of zinc in a battery, that same quantity will go 
 through its conductor, and may be, so to speak, gathered, 
 wholly regardless of whether it heats the conductor or 
 not. It makes no difference whether it goes straight from 
 the cell to an electro-plater's bath, where it may cause the 
 deposition of a certain amount of copper ; or whether, 
 
THE ELECTRIC LIGHT. 121 
 
 on its way thither, it heats an electric lamp : only it will 
 take longer to go through the circuit in the last case. If 
 we clammed a certain amount of water in a mill-pond, 
 with which to drive a water-wheel, we know perfectly well 
 that all the water will go through or over the wheel which 
 is driven by it. The wheel simply takes the energy of 
 the water. It does not consume the water itself. So in 
 the steam-engine. We heat water to make steam. We 
 use the energy thus imparted to it ; and after we are done 
 with the steam, it condenses back to water again. Of 
 course it all ciphers down to the fundamental law that the 
 matter and force in the universe are alike indestructible, 
 and that we can merely change them from one form to 
 another, without addition to or subtraction from the total 
 amount. This, however, is the deep water of science ; 
 and this chapter is about the electric light, and not the 
 abstractions of philosophy. 
 
 Whenever, then, an electric current meets resistance in 
 its passage, heat is developed. If a body intensely 
 charged with electricity approaches a non-electrified body, 
 then the current tends to pass from the former to the 
 latter. If the energy of the current can overcome the 
 resisting medium between the bodies, it will do so" ; and 
 in doing so, it will develop heat. Now, air is a substance 
 which offers the highest resistance to the current. Hence, 
 as we have seen, it requires electricity of enormous electro- 
 motive force to pass over a very small air interval. Thus 
 a cloud may become electrified very intensely ; and'when 
 it approaches a cloud oppositely electrified, or of lower 
 potential, then the current will force its way through the 
 intervening air. In overcoming that resistance, its energy 
 will be converted into heat and light. The flash thus 
 caused we call lightning ; and so the electric light existed 
 from the beginning. But think of the fate which would 
 
122 THE AGE OF ELECTRICITY. 
 
 have awaited the impious Roman or Greek, a couple of 
 thousand years ago, who should venture the prediction 
 that the streets of Rome or Athens would one day be lit 
 by Jupiter's thunderbolts, quietly blazing on the tops of 
 long poles ! 
 
 The first electric light produced by human agency was 
 obtained by Burgomaster Von Guericke, from his revolv- 
 ing sulphur globe. Priestley says that Robert Boyle got 
 " a glimpse of the electric light " before Von Guericke ; 
 
 Fig. 66. 
 
 "for he found that a curious diamond which Mr. Clayton 
 brought from Italy, gave light in the dark when it was 
 rubbed against any kind of stuff ; and he found that by 
 the same treatment it became electrical." 
 
 In Gravesande's "Mathematical Elements of Natural 
 Philosophy" (1731), appear the engravings Figs. 66 and 
 67, which are reproduced from that work in facsimile. 
 These represent the earliest methods of production of the 
 electric light, other than by the simple rubbing of amber 
 and like substances by hand. In Fig. 66 is shown a glass 
 globe which is to be " briskly whirl'd in a dark place, the 
 Hand all the while being held against it, to give it Attri- 
 
THE ELECTRIC LIGHT. 
 
 123 
 
 tion. If the Globe be exhausted of its Air, it will appear 
 all luminous within, but mostly so where the Hand touches 
 the Glass. But if the Globe has Air in it and being 
 whirl' d in the same Manner, the Hand be applied to it, 
 no Light appears, either in the inner or outer surface of 
 the Glass ; but Bodies at a 
 small distance from the Glass 
 (as for Example at a Quar- 
 ter of an Inch, or nearer) be- 
 come luminous ; and so only 
 those Farts of the Hand held 
 against the Glass, which 
 terminate or rather environ 
 the Parts that immediately 
 touch the Globe, are lumi- 
 nous." 
 
 Observe the reason : u that 
 Glass contains in it and has 
 about its surface a certain 
 Atmosphere which is excited 
 by Friction and put into Vi- 
 bratory Motion : the Fire 
 contained in the Glass is 
 expelled by the Action of 
 this Atmosphere, ' ' and ' ' this 
 Atmosphere and Fire is more 
 easily moved in a Place void 
 of Air." 
 
 Farther on, the author concludes that quicksilver con- 
 tains fire ; "for if mercury well cleaned be shak'd about 
 in an exhausted Glass it will appear luminous ; " and then 
 he suggests the apparatus represented in Fig. G7, which is 
 a bell-glass from which air has been exhausted, and into 
 which mercury is caused to spout by the pressure of the 
 
 Fig. 67. 
 
124 THE AGE OF ELECTRICITY. 
 
 external atmosphere. " The experiment must be made in 
 a dark place, and the mercury will appear luminous." 
 
 These experiments were devised by Hawksbee in 1709. 
 He called the mercury jet the "mercurial phosphorus," 
 and did not consider the glass as in any way concerned 
 in producing the light. "The greatest electric light Mr. 
 Hawkesbee produced," says Priestley, "was when he 
 enclosed one exhausted cylinder within another not ex- 
 hausted, and excited the outermost of them, putting them 
 both in motion. Whether their motions conspired or not, 
 he observed, made no difference. When the outer cylin- 
 der only was in motion, he says, the light was very con- 
 siderable, and spread itself over the surface of the inner 
 glass. What surprised him most was, that after both 
 glasses had been in motion some time, during which the 
 hand had been applied to the surface of the outer glass, 
 the motion of both ceasing, and no light at all appearing ; 
 if he did but bring his hand again near the surface of the 
 outer glass, there would be flashes of light, like lightning, 
 produced on the inner glass : as if, he says, the effluvia 
 from the outer glass had been pushed with more force 
 upon it by means of the approaching hand." 
 
 For a long time after Hawkesbee, no further experi- 
 ments on the electric light were made. In fact, the use 
 of the rotating globe machine was discontinued ; and to 
 this circumstance Priestley ascribes the slow progress 
 afterwards made in electrical discoveries. Meanwhile the 
 idea that the electric spark could be utilized as a light 
 did not seem to strike any one. The philosophers kept 
 getting shocks from different things, and discovering after- 
 wards that they were electrical. They obtained fine flashes 
 from cats, and pondered long over the problem of why 
 cats gave sparks; until one Waitz, having procured "a 
 dry dog," applied vehement friction to the unhappy aui- 
 
THE ELECTRIC LIGHT. 125 
 
 mal, and so found, not only that dogs gave sparks as well 
 as cats, but that these sparks were electrical. "This," 
 remarks Priestley in his most owlish manner, " had been 
 supposed, but was not accurately ascertained before." 
 One is tempted to ask why ; but Priestley vouchsafes no 
 further information. 
 
 It will be remembered, that in describing the extraor- 
 dinary effects of the shock of the Leyden-jar upon the 
 electricians of the period, when it was first produced, we 
 adverted to the exaggerations of these learned persons. 
 It is difficult to trace the history of electricity without 
 experiencing a sense of mild wonder as to whether there 
 is not, perhaps, some subtle influence of the mysterious 
 current exerted upon the moral faculties of those who 
 deal with it, or, rather, invent around it, which in- 
 duces them to view facts differently from most people. 
 And it is singular how this peculiar obliquity of vision 
 affects those who have to do with the electric light ; not 
 in these times (ns every one who precipitately sold his gas 
 stock during the electric-light scare of 1879-80 can tes- 
 tify), but, of course, a hundred years ago. 
 
 There was Boze of Wittenberg, who some time before 
 had wanted to die from the effects of a shock for the sake 
 of personal advertisement ; and who had discovered, by 
 the way, that water running from a vessel in drops would 
 escape in a constant stream when electrified, a valuable 
 idea long afterwards utilized by Sir William Thomson 
 in his siphon recorder. Boze was a most meritorious in- 
 vestigator, until he became entangled in an electric-light 
 scheme. He said that he gave light, not sparks of the 
 cat-and-dog order, but that he himself had only to be elec- 
 trified, and he would become a perfect illumination. He 
 called it a " beatification ; " and furthermore, with all the 
 vigor of the man who prophesies that by next Christmas 
 
126 TIIE AGE OF ELECTRICITY. 
 
 gas will be extinct in every dwelling in the land, he assev- 
 erated that a glory would form around his head, just like 
 the rings or miniature auroras represented by painters 
 about the heads of saints. It is all solemnly recorded in 
 4 ' Philosophical Transactions." Although the reader may 
 look in vain through that erudite work, for any reference 
 to the Boze Electric Light Company (limited), this re- 
 markable announcement to quote Priestley once more 
 " set all the electricians in Europe to work, and put them 
 to a great deal of expense." 
 
 Among these electricians was Dr. Watson ; who, having 
 failed to see why there should be such a thing as Boze 
 electricity any more than cat electricity or dry-dog electri- 
 city, or, in other words, disbelieving Boze's whole story, 
 caused himself to be electrified while perched on a huge 
 cake of pitch, just as Boze described. He candidly 
 admitted, that, so far as he was concerned,* he felt the 
 skin of his head tingle, and the rather disagreeable sensa- 
 tion of things creeping over him ; but despite his remain- 
 ing, with exemplary patience, several hours in the dark, 
 under these not wholly pleasant conditions, no truthful 
 person could be found who for a single moment would 
 admit that any light was visible. 
 
 It is perhaps as well that the argument which Watson 
 thereupon addressed to Boze is not set down. Ultimately, 
 however, Boze confessed that he had dressed himself in a 
 suit of metal armor covered with points, many of which 
 radiated from the helmet, and the sparks were produced 
 from these in the usual way (brush discharge) when a 
 strong charge was conducted to them. 
 
 There was a poetic justice in the penalty inflicted on 
 Boze. He claimed afterwards to have discovered that he 
 could invert the poles of a magnet "by electricity only, 
 to destroy their virtue, and restore it again." He did net 
 
THE ELECTRIC LIGHT. 127 
 
 describe his method : what it may have been, or how far 
 it may have foreshadowed the electro-magnet, no one 
 knows. He got no hearing, apparently, from the Royal 
 Society ; and his chronicler contemptuously remarks, that, 
 " considering that no person in England could succeed in 
 this attempt, and that we are now (17G9) able to do it but 
 imperfectly, it is hardly probable that he did it at all." 
 And that was the fate of the first philosopher who pre- 
 tended that he had an electric light which he did not have, 
 and who put the other philosophers u to a great deal of 
 expense." 
 
 In 1745 Mr. Gottfried Gummert of Biala, Poland, in 
 order to observe whether a tube from which the air was 
 exhausted would give light when it was electrified, as well 
 as when it was excited, presented one, some eight inches 
 in length and about a third of an inch in diameter, to the 
 electrified conductor of a machine. He was surprised to 
 find the light dart vividly the whole length of the tube. 
 This light in vacuo, Gummert proposed to make sse of 
 " in mines and places where common fires and other lights 
 cannot be had." This appears to have been the first 
 announcement of the discovery, that, by rarefying the 
 air, the discharging distance, or the space over which the 
 spark will pass, is augmented, while the discharge itself is 
 caused to pass silently. It is now known that every atten- 
 uated gas has its own color when traversed by the dis- 
 charge, and that the rosy color of the light seen when 
 rarefied air is used is due to the nitrogen of our atmos- 
 phere. The same color appears in the aurora borealis, 
 which has the same origin. Tubes containing attenuated 
 gas are called vacuum or Geissler tubes. Their light is 
 faint, and has not been practically applied as yet to illu- 
 minating purposes. Many. of the phenomena observed 
 with these tubes remain unexplained. 
 
128 THE AGE OF ELECTRICITY. 
 
 Referring to other modes of causing electric illumination, 
 Priestley, writing in 1769, says, "A variety of beautiful 
 appearances may be exhibited by means of the electrical 
 light, even in the open air if the room be dark. Brushes 
 of light from points electrified positively and not made 
 very sharp, or from the edges of metallic plates, diverge 
 in a very beautiful manner, and may be excited to a great 
 length by presenting to them a finger or the palm of the 
 hand." 
 
 The first voltaic pile was constructed in 1800. Eight 
 years later Humphry Davy obtained from the battery of 
 the Royal Institution, the first electric light produced by 
 the constant galvanic current. This battery consisted of 
 two thousand cells, arranged in two hundred porcelain 
 troughs. The fluid was a mixture of sixty parts of water 
 with one of nitric and one of sulphuric acid. The plates 
 were zinc and copper, square in form, and thirty-two 
 square inches in surface. " When pieces of charcoal," 
 says Davy, " about an inch long and one-sixth of an inch 
 in diameter, were brought near each other (within the 
 thirtieth or fortieth part of an inch) , a bright spark was 
 produced, and more than half the volume of the 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 at least to four 
 inches, producing a most brilliant ascending arch of light, 
 broad and conical in form in the middle." 
 
 Davy used pencils of common charcoal, which wasted 
 away rapidly ; and as no means of regulating the distance 
 between them had been devised, the light was of short 
 duration. For some thirty years, the production of the 
 voltaic arc remained an interesting though fruitless labora- 
 tory experiment. The power derived from available bat- 
 teries was weak ; their construction was expensive ; and 
 
THE ELECTRIC LIGHT. 129 
 
 these difficulties were added to the lack of proper carbons 
 and of controlling apparatus therefor. In 1836 Grove's, 
 and in 1842 Bunsen's, batteries were invented. In Grove's 
 cell the attacked electrode is zinc plunged in dilute sulphu- 
 ric acid, and contained in a porous jar ; in the outer vessel 
 is platinum immersed in nitric or nitro-sulphunc acid. 
 Bunsen's cell has already been described. Both of these 
 batteries give a high electro-motive force ; their currents 
 were therefore better adapted to overcome the resistance 
 of the carbons and the intervening air space than those of 
 any cells previously invented. 
 
 In 1844 Le*on Foucault replaced the slides of common 
 charcoal, used since Davy's time, with pieces of gas car- 
 bon, and employed the Bunsen cell as a current-generator. 
 He also contrived a means of regulating the lamp by hand. 
 With this apparatus M. Deleuil took photographs ; and in 
 French treatises he is often accorded the credit of being 
 the first person to use the electric light for such a purpose. 
 This, however, is not the fact. In November, 1840, Prof. 
 B. A. Silliman, jun., and Dr. W. H. Goode obtained "pho- 
 tographic impressions by galvanic light reflected from 
 the surface of a medallion to the iodized surface of a 
 daguerrotype plate," using the large battery of nine hun- 
 dred cells belonging to the laboratory of Yale College. 
 Two pictures were obtained : one ' ' made up of a blur or 
 spot produced by the light from the charcoal points, the 
 image of the retort-stand on which a medallion of white 
 plaster rested, and the image of the medallion;" the 
 other picture was of the medallion only. An interesting 
 account of this experiment was published in the Journal 
 of the Franklin Institute in 1843. 
 
 One evening in December, 1844, during a thick fog, the 
 people who were passing the Place de la Concorde in Paris 
 were astonished by suddenly finding that they could see 
 
130 THE AGE OF ELECTRICITY. 
 
 clearly, although the gas-lamps at a distance of a few yards 
 were invisible. A very intense light traversed the atmos- 
 phere, and illuminated even the remotest corners of the vast 
 square. This was an electric light, and the occurrence is 
 believed to mark the first illumination of a public thorough- 
 fare therewith. The Parisians were more than delighted 
 with the magnificence of the light. In rapid succession 
 electric lamps were established on the Pont Neuf to illu- 
 minate the Seine beneath, on the Arc de Triomphe, in the 
 court of the Palais Royal, and at the Porte St. Martin. 
 It was simply necessary for an inventor to allege that he 
 had a new form of lamp, to secure a public trial. With 
 characteristic ingenuity the scenic artists of the opera 
 seized upon the light as a means of introducing new and 
 startling effects into the mise en scene. Rossini's " Moses " 
 was put on the stage, on a scale of great magnificence ; 
 and the beams of the electric light were shed upon the 
 figure of the inspired prophet, investing him with a super- 
 natural radiance. In the final scene, the spectrum of the 
 light was used to imitate the rainbow. The Israelites 
 were grouped on the front of the stage ; while in the far 
 distance, the Egyptians, immersed in partial darkness, are 
 seen perishing in the waters. Moses, upon a high rock, 
 holds the tables of the Law. The light, gradually increas- 
 ing, represents the break of day ; at the same moment, as 
 the symbol of the new covenant, a rainbow appears. One 
 lamp was placed behind the rock in the foreground, and 
 its light concentrated upon the characters ; the rest of the 
 stage being in obscurity. The beam of a second lamp, 
 after dispersion by a prism, painted itself as a rainbow 
 upon the scene at the back. 
 
 The mode of producing the voltaic arc is quite simple. 
 The two rods of carbon are first placed in contact. The 
 
THE ELECTRIC LIGHT. 131 
 
 current then passes from one to the other ; and while it is 
 so passing, the rods are gradually separated. During this 
 action, the current heats the air, and also vaporizes a por- 
 tion of the conductor, so that the interval between the rods 
 becomes filled with carbon probably in a gaseous state. 
 This carbon vapor, while it conducts the current, offers a 
 high resistance. It becomes white hot. The plus carbon 
 
 or that from which the current flows is usually the 
 uppermost, and, being the more highly heated by the cur- 
 rent, burns away most rapidly : particles of this carbon are 
 carried off, and transferred to the negative carbon, which 
 thus assumes the form of a pointed cone, while the plus 
 carbon forms a hollow crater of intense brightness, and 
 acts as a sort of reflector to throw a large proportion of 
 the light downward. 
 
 The temperature of the arc is immensely high, and is 
 the most intense of all artificial sources of heat. " Plati- 
 num," wrote Davy, in the account which he has left of 
 his famous experiment, " was melted as readily as wax 
 in the flame of a common candle : quartz, the sapphire, 
 lime, magnesia, all entered into fusion." The diamond 
 
 a very refractory body when placed in the arc be- 
 comes white hot, swells out, fuses, and gradually trans- 
 forms into a black crumbling mass. Carbon itself has been 
 softened so that it can be easily bent and welded. The 
 temperature of the arc is estimated at about 8700 Fah. ; 
 but this is not settled. In point of brilliancy, it is rather 
 less than one-third as bright as the sun. Its characteristic 
 color is a bluish white ; the carbons giving a white light, 
 and the arc a bluish purple. The effect is rather ghastly, 
 owing to the excess of blue rays. The light may be pro- 
 duced not only in air, but also under the surface of water 
 and other non-conducting liquids, in oils, and in a vacuum ; 
 so that it appears to be due to the incandescence, and not 
 
132 THE AGE OF ELECTRICITY. 
 
 to the oxidation, of the carbon. The pressure of the 
 current required to maintain an arc one-tenth of an inch 
 in length is sixty volts, increasing quickly up to a quarter 
 of an inch, and after that at the rate of fifty-four volts 
 per inch. To supply such high pressure, obviously, a 
 large number of battery cells would be required, with 
 attendant large expense due to the consumption of zinc. 
 All the early arc lamps were thus supplied. 
 
 Inasmuch as the carbon rods slowly burn away, it is 
 necessary that one of them should be continuously fed 
 forward by suitable machinery, so as to keep the resist- 
 ance of the arc as constant as possible. Upon the uni- 
 form working of this feeding mechanism, greatly depends 
 the steadiness of the light. A great many different forms 
 of apparatus for this purpose exist. We shall therefore 
 refer to but a few of the most typical forms. 
 
 For street illumination, it is important that the lamp 
 should give a steady light. In construction it should be 
 not too heavy to be supported by an ordinary lamp-post, 
 and it is important that the mechanism should all be above 
 the lamp so that no shadows may be cast downward. 
 
 In the Brush lamp, the feed is actuated by gravity as 
 will be understood from the diagram of the lamp mechan- 
 ism (Fig. 69). The upper carbon A descends by its own 
 weight until it meets the lower one B. Then the current, 
 moving in the direction of the arrows, is established, and 
 passes between the carbons, and through the coil C of a 
 hollow electro-magnet. In this magnet is a soft iron, 
 plunger Z), which, when the magnet is excited, is drawn 
 upward. Through the intervention of a lever and an 
 ingenious annular clutch at E, surrounding the rod of the 
 upper carbon A like a washer, the upper carbon is lifted 
 away from the lower carbon, and thus the arc is established. 
 
 As the carbons burn away, the arc has a tendency to 
 
THE ELECTRIC LIGHT. 
 
 133 
 
 become longer ; and this, by reducing the strength of the 
 current, diminishes the supporting power of the coil C. 
 The latter then allows its plunger to descend, thus lower- 
 ing the carbon, and so shortening the arc until the proper 
 strength of the current is restored, when the rising of the 
 plunger once more holds the carbon in position. There is 
 also an ingenious contrivance whereby each lamp in a cir- 
 cuit is enabled to .control itself independently of the action 
 of all the others in the circuit. Ordinary Brush lamps 
 such as are used for street-lighting give a light equal to 
 that of about eight hundred candles ; but very large ap- 
 
 JJyncuno 
 
 Fig. 69. 
 
 paratus of this kind has been made, in which the carbons 
 are three and a half inches in diameter, giving a light 
 equal to that of a hundred and fifty thousand candles. 
 An ordinary Brush street-light such as is used in New- 
 York City is represented in Fig. 70. 
 
 The Siemens lamp depends on what is termed the differ- 
 ential principle, which is illustrated in the diagram, Fig. 
 71. Here the lower carbon B is stationary. The upper 
 carbon A is attached to the end of a rocking arm or lever 
 O, at the other end of which is a core D of soft iron. 
 
134 
 
 THE AGE OF ELECTRICITY. 
 
 This core enters two coils E and F, one above and the 
 other below the lever. The coil E offers a high resistance 
 to the current, because it is of fine wire. The coil jP, on 
 the other hand, is of thick wire, and offers little resistance. 
 The current, starting from the dynamo, goes by a wire 
 
 to the point G. It may 
 now take either of two 
 roads, through the coil 
 F, the lever C, and the 
 carbons AB, and so by the 
 wire //back to the dynamo, 
 thus completing the circuit ; 
 or it may pass through the 
 coil E, and thence by the 
 wire G to the wire /T, and 
 so to the dynamo, in this 
 case, not passing through 
 the carbons at all. Now, 
 the current having two pos- 
 sible paths will divide itself 
 through both, the most 
 current going through 
 the path which offers the 
 least resistance. If we 
 suppose that at the out- 
 set the carbons are wholly 
 separated, then there is a 
 very great resistance in 
 the first of the paths above noted : consequently the cur- 
 rent will flow around the other path. But in passing 
 through the coil E, it converts that coil into a magnet, 
 which draws up the core D; and when the core D is 
 drawn up, the outer end of the lever C moves down, and 
 thus the carbons are brought into contact. Then the 
 
 Fig. 70. 
 
THE ELECTRIC LIGHT. 
 
 135 
 
 current is free to pass through the carbons ; and it does 
 so until they become burned away, too widely separated, 
 and hence the space between them offers so much resist- 
 ance to the current that the latter again travels through 
 the coil E, and so causes the lever C to bring the carbons 
 nearer together again. When the current passes through 
 the coil F, which it does when supplying the carbons, this 
 coil also acts as a magnet to move the lever in the oppo- 
 site direction to that in which it is moved by the coil E. 
 The actions of the 
 two coils balance each 
 other when the resist- 
 ance of the arc is 
 uniform. 
 
 The two lamps 
 above described are 
 types of the two prin- 
 cipal systems in use. 
 The Brush lamp is 
 based on what is termed 
 the gravity plan, where- 
 in, as we have seen, 
 the weight of one carbon causes its approach to the other, 
 and the magnetism of the current acts against this to 
 separate the carbons. The Siemens lamp, on the other 
 hand, is constructed on the differential system ; the differ- 
 ence between the opposite actions of the two magnets 
 being utilized to control the carbon. 
 
 For light-house purposes, it is of course absolutely 
 necessary that the light shall never be extinguished for 
 an instant, and that the mechanism shall be very strong. 
 Expense, weight, and bulk are matters of no moment ; 
 and slight pulsations of the light are not a serious defect. 
 For this use, a comparatively old form of lamp, the 
 
 Dynamo 
 
 Fig. 71. 
 
136 THE AGE OF ELECTRICITY. 
 
 Serrin, is still employed. As the light must be kept in 
 the focus of the reflector, both carbons are fed forward ; 
 this being effected by clock-work mechanism actuated by 
 the weight of the upper carbon, so that, as the upper 
 carbon descends, the lower one rises to meet it. 
 
 Hitherto we have referred simply to the lamps which 
 are known as " arc lamps," and which, as has been seen, 
 depend upon the production of the voltaic arc between 
 the ends of separated carbon rods. These constitute one 
 principal class. Another class of electric lamp, of much 
 greater importance, for its applicability is far wider, 
 is the incandescent lamp, which consists of a thin fila- 
 ment or wire of carbon enclosed in a glass globe from 
 which the air has been exhausted. 
 
 The idea of using a body rendered incandescent by the 
 heating action of a current, as a means of illumination, 
 appears to have been first described by Mr. Frederic de 
 Moleyns, who in 1841 patented in England an electric 
 lamp in which a platinum wire enclosed in an exhausted 
 glass globe was to receive a shower of plumbago parti- 
 cles. There is nothing practicable about De Moleyns' 
 idea ; and it would doubtless have remained forever in 
 oblivion, had not the English writers on the subject found 
 De Moleyns' patent a convenient peg on which to hang a 
 claim that the incandescent electric lamp is a British in- 
 vention. The real inventor of the lamp appears to have 
 been J. W. Starr of Cincinnati, O. Starr used an ex- 
 hausted glass globe in which was a thin strip of graphite 
 held between two clamps affixed to a porcelain rod ; the 
 latter being suspended by a platinum wire sealed in the 
 globe. Starr died in 1847, but twenty-five years of age ; 
 a victim to overwork, and disappointment in his endeavors 
 to perfect this lamp and a magneto-electric machine to 
 drive it. It gave an excellent light. Starr was evidently 
 
THE ELECTRIC LIGHT. 137 
 
 a prophet without honor in his own country ; for his 
 endeavors to interest others in his invention met with 
 failure, and critics were not wanting who openly asserted 
 that he was simply invoking perpetual motion. This, 
 apparently, because he proposed to utilize a magneto- 
 electric machine to supply his lamp. "The Cincinnati 
 Advertiser" of Sept. 4, 1844, published a letter from a 
 correspondent who stated as follows : 
 
 " 1. That this light is magneto-electrical. 
 
 " 2. That it is produced by permanent magnets, which 
 may be increased to an indefinite extent. The apparatus 
 now finished by the inventors and discoverers in this case 
 will contain twenty magnets. 
 
 "3. That it supplies a light whose brilliancy is insup- 
 portable to the naked eye. 
 
 "4. That a tower of adequate height will enable a 
 light to be diffused all over Cincinnati, equal for practical 
 purposes to that of day. 
 
 "5. That this light, when once set in operation, will 
 continue to illuminate without one cent of additional 
 expense. 
 
 " 6, and lastly. That the inventors in this process have 
 nearly solved the long-sought problem, perpetual mo- 
 tion. ... I suppose this light will prove the greatest 
 discovery of modern times. It is needless to add how 
 much it gratifies me, that Cincinnati is the place, and two 
 of its native sons J. Milton Sanders and John Starr 
 the authors, of the discovery." 
 
 Starr appears thus to have been the first to suggest the 
 lighting of cities by electric lights 011 high towers. Shortly 
 afterwards, Mr. W. H. Weekes in England proposed sup- 
 plying lights thus elevated, from earth batteries formed 
 of huge plates of zinc and copper buried beneath the 
 structures. Several years before, he had suggested ele- 
 
138 THE AGE OF ELECTRICITY. 
 
 rating oxyhydrogen lights in the same way. On the 
 strength of that suggestion, the English journals, as 
 usual, claimed Starr's invention as British ; and when 
 Starr's patent appeared, in 1846, they insisted that it 
 was anticipated by De la Rive, who had employed coke 
 cylinders surrounded by rings of metal, between which 
 rings and cylinders the arc passed ; and by Grove, who 
 had used platinum spirals. Neither Grove nor De la 
 Rive enclosed an incandescent carbon rod in a globe ex- 
 hausted of air ; but a small difference of that sort did 
 not stand in the way of denying to an American the honor 
 and credit that was his due. It was carrying Sydney 
 Smith's sneering comment, " Who reads an American 
 book ? " a little farther by the habitual refusal to believe 
 that any thing good whatever could come out of the 
 Nazareth of the United States. 
 
 One of the most extraordinary claims to the honor 
 of the same invention was made not long ago, by M. de 
 Changy, who asserted that as far back as 1838 his friend 
 M. Jobard of Brussels suggested the idea that a small 
 carbon, employed as a conductor of a current in a vacuum, 
 would give an electric lamp with an intense fixed and 
 durable light. Acting on this suggestion, De Changy in- 
 vented several forms of lamps, using platinum spirals, and 
 even devised systems for the electric lighting of mines, 
 luminous buoys, submerged lamps for fishing, and nauti- 
 cal telegraphy by means of colored tubes containing the 
 incandescent wires. The whole matter was brought be- 
 fore the French Academy of Sciences ; and a commission, 
 of which M. Desprez was the chief, was appointed to 
 examine the invention. De Changy claimed to have suc- 
 ceeded at this time in arranging several lamps in one cir- 
 cuit, which could be lighted simultaneously in groups, or 
 separately without affecting the normal intensity of each. 
 
THE ELECTRIC LIGHT. 139 
 
 Desprez wrote for a detailed account of the invention ; 
 which was declined by Jobard, on the ground that the 
 exposure would affect a pending patent. Thereupon 
 Desprez with that singular fatuity concerning patents, 
 now happily confined to medical practitioners said that 
 De Changy evidently desired to make money out of his 
 invention, and so did not merit the name of savant, and 
 that the Academy had no further interest in his work. 
 This so disheartened De Changy, that he abandoned his 
 labors, and as a consequence, if his statements be cor- 
 rect, the incandescent light was lost to the world for 
 more than a quarter of a century. In that interval, how- 
 ever, the Academy changed its views. It decreed the 
 award of the Volta prize to Mr. Alexander Graham Bell, 
 upon his claim to the invention of the speaking telephone, 
 an instrument which has yet to be given freely to the 
 world. 
 
 The incandescent lamp which forms one of the great 
 classes of electric illuminating devices, as now constructed, 
 consists of a thin filament or wire of carbon enclosed in 
 a glass globe from which the air has been exhausted. 
 When a current of electricity of suitable strength passes 
 through the filament, it becomes white hot, or incandes- 
 cent, and so yields a light of from one to one hundred 
 candles, according to its surface, and for a given surface 
 according to the temperature to which it is raised. There 
 are many forms of incandescent lamps, differing mainly 
 in detail and more especially in the mode of preparing the 
 carbon filaments. New forms are constantly appearing. 
 In all of these, however, the filament is of vegetable fibre, 
 carbonized by heat. The ends of this filament are con- 
 nected to two platinum wires which pass through a neck 
 formed on the globe. These are melted into the glass 
 itself ; and platinum is chosen because it expands by heat 
 
140 THE AGE OF ELECTRICITY. 
 
 at about the same rate as the glass itself does, so that the 
 latter does Dot crack in cooling. The exhaustion of the 
 air in the globe must necessarily be as nearly perfect as 
 possible. Without the Sprengel air-pump, it would prob- 
 ably be impracticable to produce an efficient vacuum. 
 This pump consists of glass tubes, down which mercury 
 flows in a broken stream or in drops. Near the top of 
 the tubes are side openings connected to the chamber to 
 be exhausted. Air enters from this chamber, and, becom- 
 ing compressed between consecutive mercury drops, is 
 carried away ; and the process is repeated until the cham- 
 ber is completely exhausted. While the lamp is still at- 
 tached to the pump, a current of electricity is sent through 
 the filament, sufficient to raise it to a somewhat higher 
 degree of incandescence than will be used in actual work. 
 All the gas driven out of the carbon is at once removed 
 by the pump, and the lamp is sealed while the current is 
 still passing. 
 
 The incandescent lamps in most general use are respec- 
 tively those devised by Edison and Swan, and these may 
 be taken as typical. Mr. Edison's experiments upon the 
 materials and construction of incandescent lights are prob- 
 ably the most elaborate and far-reaching ever conducted. 
 On the other hand, it is doubtful whether any inventor 
 ever undertook an investigation more abundantly provided 
 with the means for carrying it to successful termination. 
 He began by studying conductors made of an alloy of 
 platinum and indium, and also of platinum alone ; but 
 found that the effect of incandescence upon the wires ex- 
 perimented upon was to produce, all over their surface, 
 innumerable cracks, and in a few hours these fissures 
 united, and the wire fell to pieces. With characteristic 
 ingenuity he contrived a way of heating the wires by a 
 current in vacuo so as actually to weld together the edges 
 
THE ELECTRIC LIGHT. 141 
 
 of these minute cracks ; and finally succeeded in producing 
 metals in a state such as had never been known before, 
 increasing their hardness and density to an extraordinary 
 degree, and raising their fusing- points so high that they 
 remained unaffected at temperatures at which most sub- 
 stances would be melted or consumed, and very many 
 would be converted into vapor. By his process he ren- 
 dered platinum wire competent to yield a light of twenty- 
 five standard candles ; while the same wire not treated 
 would give a light of not more than four candles before 
 it fused. 
 
 Ingenious as this discovery was, it did not solve the 
 problem. The inventor then turned his attention to car- 
 bon, that extraordinary substance which was already 
 playing the principal part in the operation of the speaking 
 telephone, the galvanic battery, and the voltaic arc light. 
 As usual, he carbonized about every thing within reach, 
 "cotton and linen thread, wood splints, paper coiled in 
 various ways, also lamp-black, plumbago, and carbon in 
 various forms," in his endeavor to make a carbon filament 
 or wire. Later on he settled upon paper, "Bristol 
 board," which he punched into narrow elliptical strips. 
 Finally he determined that the carbon should be purely 
 structural in character ; that is, its natural structure, cell- 
 ular or otherwise, should be preserved unaltered, and not 
 modified by any treatment " which tends to fill up the cells 
 or pores with unstrtictural carbon, or to increase its den- 
 sity, or alter its resistance." Farther on we shall see that 
 just the opposite view is taken by the inventor of the 
 Swan lamp ; and the curious fact is presented, of two 
 forms of the same apparatus, both fairly successful, yet 
 dependent on radically opposite deductions from experi- 
 ment. 
 
 The fibre now used in the Edison lamps is that of a 
 
142 
 
 THE AGE OF ELECTRICITY. 
 
 grass from South America, called ' ' monkey-bast ; ' ' each 
 blade of which is generally round, and composed of a 
 great number of elementary fibres held together by a nat- 
 ural cement or resin, which, carbonizing, locks all the ele- 
 mentary fibres together into a homogeneous filament. The 
 ordinary form of Edison lamp is represented in Fig. 72. 
 The ends of the carbon filament are connected to platinum 
 wires, and these are attached to a screw, and a sole plate 
 stamped from thin copper, and insulated from each other 
 by plaster-of-paris, which surrounds the 
 neck of the envelope, and forms a firm 
 and rigid attachment. The socket into 
 which this fitting screws is simply a 
 counterpart of the thread on the lamp. 
 
 In lieu of using a so-called structural 
 carbon, Mr. Swan in his lamp prefers a 
 filament as far as possible devoid of struc- 
 ture. He steeps a cotton thread in a solu- 
 tion of sulphuric acid and water until the 
 tissue is entirely destroyed, and a horny 
 homogeneous filament is produced, which 
 before carbonization is rendered uniform 
 in density by compression. Fig. 73 repre- 
 sents the present form of Swan lamp. 
 Tue filament is connected, as usual, to platinum wires, 
 which terminate outside the neck of the globe, in small 
 loops. The globe is entirely separate from the holder ; 
 the latter being of ebonite, provided with a screw plug 
 for attachment to the fixture. On the side of the holder 
 are binding posts for the connection of the circuit wires. 
 These posts communicate with platinum hooks, which 
 engage the loops of the globe wire. The neck of the 
 globe rests in a spiral spring, which steadies it, and at 
 the same time causes a slight strain on the hooks, so that 
 
 c ig. 72. 
 
THE ELECTRIC LIGHT. 
 
 143 
 
 the hooks and loops make a very excellent electrical joint. 
 The whole arrangement is about the neatest and most 
 elegant which has thus far been devised for the purpose. 
 The form of the Swan filament is distinctive, it being 
 shaped in a spiral. 
 
 M. Muthel, a German 
 inventor, has made an 
 incandescent lamp 
 which requires no vacu- 
 um in the globe. He 
 makes a wire of a mix- 
 ture of bodies which 
 are conductors and non- 
 conductors of electrici- 
 ty, in which fusion is 
 wholly overcome ; the 
 non-conducting sub- 
 stances preventing the 
 melting of the metallic 
 parts. It is supposed 
 that the electric spark 
 jumps, so to speak, 
 from one particle to 
 another, and in this 
 way causes a heating 
 of the other substances, 
 which, being brought 
 to incandescence, emit 
 a more intense light. 
 
 There are two ways of arranging electric lamps in order 
 to distribute the current to them. They can be placed 
 one after another in a single circuit or wire connecting the 
 two poles or brushes of the generator ; as shown in Fig. 74, 
 where M is the generator or machine, and LL the lamps. 
 
 Fig. 73. 
 
144 THE AGE OF ELECTRICITY. 
 
 In this case the current requires to have a high electro- 
 motive force in order to overcome the added resistances 
 of the whole number of lamps. Such a current is supplied 
 by the Brush generator or the peculiar form of Gramme 
 generator employed by Jablochkoff. The other way of 
 arranging the lamps is to connect them singly or in little 
 groups by cross wires between two main conductors joined 
 to the brushes of the generator, as shown at LL in Fig. 
 
 t, X) 
 
 
 
 "L L 
 
 
 
 M 
 
 f: 
 
 \ 
 
 Fig. 74. 
 
 75. Then the current, instead of traversing one lamp 
 after another, splits up between the lamps, part going 
 through one lamp or group, and part through another. 
 The resistance of any particular path or channel for the 
 current is in such a case not very great, and the electro- 
 motive force of the current need not be dangerously 
 high. It is on this plan that incandescent lamps are 
 generally arranged for domestic purposes, and the cur- 
 
 * 
 
 
 Fig. 75. 
 
 rents flowing in the wires about a house would of course 
 be harmless. These lamps can be mounted on an ordinary 
 chandelier. 
 
 There is still a third form of electric-light apparatus, 
 which, however, has not come into extended use. This 
 is known as the incandescence arc system. It is an inter- 
 mediate arrangement between the arc and the incandescent 
 lights. The illumination is produced by the passage of 
 
THE ELECTRIC LIGHT. 145 
 
 the electric current through a rod of carbon of a diameter 
 so small that its extremity becomes heated nearly to white- 
 ness. This is one of the oldest forms of electric light. 
 It was originally patented in England in 1846. 
 
 The " electric candle," so called, is a very re- 
 markable form of arc light which on its introduc- 
 tion in 1878 created great popular interest. It 
 probably did more to turn the attention of invent- 
 ors to the possibilities of improving the electric 
 light, after thirty years' neglect of the subject, 
 than any other recent invention, excepting proba- 
 bly the Gramme dynamo. It was originally in- 
 vented by M. Paul Jablochkoff, a Russian officer 
 of engineers ; and, as first produced, consisted of 
 two carbon rods fixed parallel to one another, a 
 slight distance apart, and separated by an insu- 
 lating medium which is consumed at the same rate 
 as the carbons themselves. As soon as the cur- 
 rent commences to pass, the voltaic arc plays 
 across the free ends of the carbons. The ad- 
 jacent insulating material becomes consumed, and 
 slowly uncovers the pair of carbons just as the 
 wax of a candle gradually uncovers the wick. 
 
 The usual form of Jablochkoff candle is repre- 
 sented in Fig. 76. There are two cylindrical 
 carbons about nine inches long by sixteen-hun- 
 dredths of an inch in diameter. The insulating 
 material between them is a mixture of sulphate of 
 lime and sulphate of barytes. As a candle will 
 last but for about two hours, it is necessary to ar- 
 range several of them in a holder, so that the total period 
 of lighting may range up to sixteen hours. Whatever may 
 be the number of candles to be lighted, one after another, 
 to afford a continuous light for a given time, it is neces- 
 
146 THE AGE OF ELECTRICITY. 
 
 sary to employ a device by which, as soon as one candle 
 has burnt out, the current feeding it shall be switched off 
 to the one adjacent. This is effected either by hand or 
 by the use of an automatic commutator. 
 
 The Soleil light stands midway between the electric 
 candle and the incandescence arc light. It has, however, 
 some remarkable characteristics peculiar to itself. A 
 block of refractory material, such as marble, lime, or 
 granite, has a cavity on one side, shaped like a truncated 
 cone, to the face of which penetrate the carbons, travers- 
 ing the mass through inclined cylindrical holes. When 
 the arc passes between the two points, it plays on the 
 face of the recess, heats it, and transforms it into a small 
 crater, whence the luminous rays escape in a conical beam. 
 The light is slightly golden in color. It consumes more 
 power than many arc lights, but is very durable and 
 simple. 
 
 When a conductor conveying a powerful electric current 
 is suddenly broken, a bright flash, called the extra spark, 
 appears at the point of separation. The extra spark will 
 appear, although the current is not sufficient to sustain an 
 arc of any appreciable length at the point of separation. 
 In order to obtain a continuous light from this spark, 
 Professors Thomson and Houston have devised an appara- 
 tus in which one or both of the carbon electrodes are 
 caused to vibrate to and from each other, so as to touch 
 momentarily at each vibration. These motions follow 
 each other at such a rate that the effect of the light pro- 
 duced is continuous ; for, as is well known, when flashes 
 of light follow one another at a rate greater than twenty- 
 five to thirty per second, the effect of an uninterrupted 
 glow is produced. 
 
 The applications of the electric light are very numerous. 
 The most extensive in point of magnitude which has been 
 
THE ELECTRIC LIGHT. 147 
 
 proposed is the establishment of an electric sun of eigh- 
 teen-million-candle power, on the summit of a tower 
 twelve hundred feet high, for the illumination of Paris. 
 For military use, the powerful beams of the arc light are 
 employed to illuminate fortifications under bombardment, 
 or reveal the approach of an enemy. Projectors have 
 been devised whereby the beam can be given a range of 
 eighty-six thousand feet. For submarine purposes, the 
 electric light is of great value : it has been employed in 
 removing sunken obstructions in the Suez Canal ; for 
 illuminating the sea depths, and so attracting deep-sea 
 fish ; and for lighting floating buoys. This last applica- 
 tion is of considerable ingenuity. By the motion of the 
 buoy, due to its rise and fall on the waves, air is com- 
 pressed within the buoy, which acts intermittently to drive 
 a dynamo, and also to sound a whistle. When the air 
 reaches a certain degree of compression, the dynamo 
 rotates, and the lamp glows brilliantly. On shipboard, arc 
 lamps are used for running lights, and also at the mast- 
 heads of steamers ; and incandescent lights illuminate 
 between decks. The steamship " Arizona," for example, 
 carries two dynamos capable of supplying six hundred 
 lights; and the Sound steamer " Pilgrim " is fitted with 
 nine hundred and twelve incandescent lamps. 
 
 It has been proposed to use a balloon filled with hydro- 
 gen, and containing inside an incandescent lamp, for sig- 
 nalling purposes ; the whole globe becoming illuminated 
 whenever the lamp glows. For lighting carriages, electric 
 lamps are arranged both inside and beside the coachman's 
 seat, and are conveniently fed by storage batteries. The 
 arc light forms an excellent head-light for locomotives ; 
 the jarring action of the vehicle being prevented by con- 
 trolling the carbons by hydraulic pressure. 
 
 Electric lights of immense power are used in light- 
 
148 THE AGE OF ELECTRICITY. 
 
 houses. The condensed beam of the great light at Souta 
 Point, England, is equal in power to eight hundred thou- 
 sand candles. The South Foreland lights, two in number, 
 are of one hundred and eighty thousand candle power 
 each. 
 
 The incandescent electric light has been found espe- 
 cially useful in coal-mines, where the fire-damp atmosphere 
 renders the presence of any exposed flame exceedingly 
 dangerous. 
 
 In medicine the electric light has been adapted with 
 various forms of carrying apparatus, whereby it is used 
 to illuminate the larynx, the stomach, and the 
 cavities of the mouth. Combined with a photo- 
 graphic camera, it allows of accurate photographs 
 being taken of diseased parts which the eye can- 
 not see. Its latest application is to the ophthal- 
 moscope. Fig. 77 represents one of the miniature 
 lamps used for surgical purposes. Water circu- 
 lates in the space between the lamp itself and an 
 outer glass tube, to keep the lamp cool enough to permit of 
 its introduction into the internal parts of the living body. 
 Miniature lamps have also been set in brooches and shirt- 
 studs, and made to form the petals of artificial flowers. 
 Sometimes they are incased in masses of colored glass cut 
 in facets to imitate jewels. 
 
 During the political campaign of 1884, as part of one 
 of the torchlight processions, quite a large body of men 
 marched with incandescent lamps on their heads. The 
 participants formed a hollow square, in the middle of 
 which was a large dynamo driven by a forty-horse-power 
 engine, these machines being on trucks. Steam was pro- 
 vided from the boiler of a large steam fire-engine. The 
 dynamo current was conducted through copper wires 
 through a rope some twelve hundred feet long. At inter- 
 
THE ELECTRIC LIGHT. 149 
 
 vals of five feet along the rope was an ordinary cut-out, 
 or lamp-receptacle, within which screwed a safety catch 
 carrying two wires which led up the sleeve of the person 
 holding the rope at that point, and through the back of 
 his helmet to a sixteen-candle-power incandescent lamp 
 on the top of it. Other lamps there were some three 
 hundred in all were distributed on the trucks and on the 
 harness of the horses. The effect was exceedingly bril- 
 liant and novel. 
 
 One of the comicalities of the electrical exposition of 
 1884, in Philadelphia, was a negro who distributed cards, 
 while wearing upon his helmet a very brilliant incandes- 
 cent light. Two wires led from the lamp, under his jacket, 
 down each leg, and terminated in copper disks fastened 
 to his boot-heels. Squares of copper of a suitable size 
 for him to stand naturally upon were placed at intervals 
 in the floor, and were electrically connected with the dy- 
 namo. Folks from the rural districts inquired cost, as 
 useful to have around the house. 
 
 For theatrical effects, the incandescent electric light in 
 its various forms is frequently employed. In a recent 
 performance of "Faust" in England, the actor personat- 
 ing Mephistopheles produced the most unearthly colors 
 on his countenance by means of small incandescent lights 
 contained in globes of various colored glass, fastened 
 beneath the visor of his cap. In the duel scene between 
 Faust and Valentine, in which Mephistopheles takes a 
 sinister part, whenever the sword of the demon crossed 
 that of Valentine, a continuous flash of fire appeared. 
 The combatants had a metal plate under foot, connected 
 with a battery ; and both Valentine and Mephistopheles 
 wore shoes provided with metal soles, which were con- 
 nected by a concealed wire with their sword-blades. The 
 continuous discharge of electricity was produced by the 
 
150 THE AGE OF ELECTRICITY. 
 
 saw-like edges of the weapons, each tooth giving off its 
 spark. For ballets and fair} 7 scenes, small incandescent 
 lamps are fastened on the heads of the performers, and 
 are supplied by storage batteries concealed on their per- 
 sons. In the aquatic circus in Paris, the great circular 
 tank of water, which replaces the usual ring, is illumi- 
 nated by submerged electric lamps. When all other lights 
 in the auditorium are extinguished, very novel and curious 
 effects are produced by swimmers, representing mermaids, 
 naiads, etc., moving about in the illuminated water. 
 
 A series of important experiments were conducted by 
 the late Sir William Siemens, upon the influence of the 
 electric light upon vegetation. He fitted up in his large 
 greenhouses two arc lamps, each capable of emitting a 
 light of about five thousand candle power. Among the 
 vegetables planted were pease, French beans, wheat, 
 barley, oats, cauliflowers, and a variety of berries and 
 flowering plants. It was found that the electric light was 
 capable of producing upon plants effects comparable to 
 those of solar radiation ; that chlorophyll was produced 
 by it, and that bloom, and fruit rich in aroma and color, 
 could be developed by its aid. The experiments also went 
 to prove that plants do not, as a rule, require a period of 
 rest during the twenty-four hours of the day, but make 
 increased and vigorous progress if subjected (in winter 
 time) to solar light during the day and to electric light 
 during the night. 
 
 Very beautiful effects can be produced by the aid of the 
 electric light when reflected from below into a jet of water. 
 By simply placing pieces of colored glass before the lamp, 
 the jets can be differently colored, so that the appearance 
 of a fountain of luminous jewels is caused. 
 
 It was for a long time believed that electric lights were 
 far inferior to oil or gas lights in their capacity to pene- 
 
THE ELECTRIC LIGHT. 151 
 
 trate fog. Recent investigations have shown, however, 
 that the advantage in favor of oil and gas is not more 
 than one per cent. 
 
 With regard to the energy consumed in electric lighting, 
 in Edison's incandescence system, one horse-power of work 
 yields from 99 to 189 candle power light ; in Swan's sys- 
 tem, about 150 candle power. With existing galvanic 
 batteries, the yearly cost of operating incandescent lamps 
 is about seven times as much as when the dynamo is em- 
 ployed. A good incandescent lamp will last from seven 
 hundred to a thousand hours. 
 
 Recent electric-lighting statistics show that at the pres- 
 ent time (1886) there are in the United States upwards of 
 ninety-five thousand arc and nearly two hundred and fifty 
 thousand incandescent lamps, distributed in over four hun- 
 dred cities and towns. Not less than seventy millions of 
 dollars is invested in the business of electric lighting in 
 this country alone. In Paris, in 1878, the cost to the city 
 was at the rate of twenty-nine cents per hour for a lamp 
 of from five hundred to seven hundred candle power. 
 The city of New York, at the present date, pays at the 
 rate of about six cents per hour for a lamp of two thou- 
 sand candle power. 
 
152 THE AGE OF ELECTRICITY. 
 
 CHAPTER IX. 
 
 ELECTRO-MOTORS, AND THE CONVERSION OF ELECTRICAL 
 ENERGY INTO MECHANICAL ENERGY. 
 
 THE electro-motor, or electro-magnetic engine, is an 
 engine driven by electricity ; or, more correctly, it is an 
 apparatus wherein electrical energy is converted into me- 
 chanical energy. Unscientifically defined, it is one of 
 those contrivances which appear especially to have been 
 "for man's illusion given." It has caused more waste 
 of time, more useless expenditure of money, and more 
 heart-breaking disappointments, than perhaps any other 
 single device evolved by human ingenuity. From the very 
 beginning, it has exercised an irresistible fascination upon 
 the inventive mind. Its possibilities were within easy 
 range of speculation, from the outset. That it might 
 prove a substitute for the steam-engine with its heat and 
 smoke and danger and waste, was apparent. A few 
 pounds of zinc, noiselessly consumed in the battery, would 
 replace the explosive boiler dependent upon coal only to 
 be obtained at an expense increasing as the supply dimin- 
 ished. The tremendous power exerted could be arrested, 
 or set in operation, or governed, by the touch of a child's 
 finger. It could be conveyed anywhere and everywhere, 
 by slender wires, to objects moving as well as stationary. 
 It could drive ships and locomotives, and all the machinery 
 of the world. In brief, as the power of falling water and 
 of the moving wind had supplanted the power of the horse, 
 
ELECTEO-MOTOES. 153 
 
 and as the power of steam in turn had taken the place of 
 the power of wind and water, so in the future electricity 
 would do the work of steam. All this was as plain fifty 
 years ago as it is now. It is far from being a delusion : 
 we are advancing toward its realization with wonderful 
 rapidity. But in that it all could be accomplished by the 
 ways and means of the third and fourth decades of this 
 century, lay the error, one that still is being repeated, 
 and always with the same result, loss and disappoint- 
 ment. 
 
 The idea of a machine to be driven by electrical power, 
 and capable of doing useful work, followed as a necessary 
 consequence upon the discovery of the immense attractive 
 strength of the electro-magnet. Why, it was argued, 
 should that ignis fatuus, that other form of the perpetual 
 motion, the cutting-off the magnetism of a permanent 
 magnet by a screen of something to be interposed by the 
 attraction of the magnet itself, be further sought, when 
 the electro-magnet could be made to exert its huge 
 strength, or be rendered powerless, instantly and at will, 
 by the mere contact or separation of the ends of a wire? 
 "When the current is established in its coil, the electro- 
 magnet attracts its armature : when the current is inter- 
 rupted, the armature is released to fall back into its 
 original position, or to lie retracted by a simple spring. 
 If the current is established and broken alternately, then 
 the armature will reciprocate to and fro like the piston of 
 a steam-engine ; and, like the piston, it may operate other 
 mechanism to produce rotaiy or any other form of motion. 
 
 The lazy boy who was set to work the valve of the old 
 engine, in order to let in steam at the proper time to move 
 the piston in the cylinder to and fro, found out that if he 
 attached the string wherewith he pulled open the valve, 
 to the moving machine, the latter would itself admit the 
 
154 THE AGE OF ELECTRICITY. 
 
 steam at the right intervals. The same idea, applied to 
 the electro-magnet and its armature, made the motor 
 automatic. When the armature is attracted, in moving 
 it may draw apart the ends of the wire whereby the cur- 
 rent is led to the magnet. Then the magnet will release 
 the armature. In falling back, the armature again brings 
 the ends of the conductor into contact. Then it will be 
 once more attracted. And thus it will go on vibrating to 
 and fro before the pole of the magnet, as long as the 
 supply of current is kept up. 
 
 This idea came to inventors all over the civilized world, 
 at about the same time. Electro-motors varying only in 
 details of construction appeared simultaneously in Eng- 
 land, France, Germany, Italy, and the United States. 
 Modern research has shown that probably the first ma- 
 chine was constructed by the Abbe" Salvatore dal Negro, 
 professor in the University of Padua, in 1830 ; although 
 the earliest published description of it appeared some two 
 or three years later. Dal Negro suspended a permanent 
 magnet between the poles of a horseshoe-shaped electro- 
 magnet, in the coils of which the current was alternately 
 reversed, so that the end of the suspended magnet was 
 first attracted and then repelled from side to side. By 
 means of a simple mechanism the swinging magnet turned 
 a wheel slowly and with little power. 
 
 Professor Joseph Henry, in this country, constructed 
 an exceedingly powerful electro-magnet, capable of lifting- 
 six or seven hundred pounds with a pint or two of liquid 
 and a battery of corresponding size ; nor did he desist 
 until, a short time after, he lifted thousands of pounds by 
 a battery of larger size, but still' very small. Subsequently 
 Henry constructed an electro-magnetic engine, having 
 a beam suspended in the centre which performed regular 
 vibrations in the manner of the beam of a steam-engine. 
 
ELECTRO-MO TORS 
 
 155 
 
 Bourbouze in France devised the remarkable machine 
 which is represented in Fig. 78. Here two electro- 
 magnet coils successively attract two pieces of soft iron ; 
 and each of these, placed at the extremities of an oscil- 
 lating beam, is drawn into the interior of the coil. When 
 the current passes into one coil, the iron armature, being 
 drawn down, causes the end of the beam to which it is 
 
 Fig. 78. 
 
 attached to descend : when the current passes into the 
 other coil, the other end of the beam goes down. The 
 beam in vibrating turns a crank, and so rotates the fly- 
 wheel. The battery is placed in the base of the machine, 
 and communicates witli a special piece of metal, the pur- 
 pose of which is to interrupt the current and throw it 
 alternately from one side to the other. This arrangement 
 is carried out simply by means of two small bits of iron, 
 separated by a plate of ivory. A metallic spring rests 
 
156 THE AGE OF ELECTRICITY. 
 
 upon the iron and ivory at the end and at the beginning 
 of its course, now on the first bit of iron, then on the 
 second, and so alternating ; and thus the current is led 
 first into one coil, and then into the other. 
 
 In all mechanical contrivances, where motion is rapidly 
 reversed, there is a great waste of power ; this because 
 the momentum of the moving part must be overcome 
 before the direction of motion can be changed. It was 
 soon found that this principle applied very cogently to 
 reciprocating electro-motors. 
 
 The first rotary electro-motor was described in "The 
 Mechanics' Magazine" of June, 1833. The apparatus 
 consisted of a bent electro- magnet, "an arc of iron 
 measuring about two-thirds of a circle, and supposed to 
 be armed with a helix of wire, and connected with a 
 galvanic battery." The armature was solid, and upon it 
 were fixed permanent magnets built of steel bars ; the 
 poles of the magnets being placed so that they would move 
 " all but in contact" with the poles of the arc magnet. 
 The communication is anonymously signed, but is of espe- 
 cial interest from the fact that the writer describes, with 
 great clearness, an apparatus which embodies every thing 
 that is essential to the construction of electro-motors of 
 the class to which it belongs, and includes features sub- 
 sequently patented over and over again as original with 
 numerous claimants to the invention. 
 
 In the fall of 1835 the Rev. Mr. McGawley exhibited 
 to the British Association a motor in which a pendulum 
 vibrated between two electro-magnets, the poles of which 
 were alternately reversed, so that first one magnet at- 
 tracted and the other repelled the pendulum, and vice 
 versa. This created considerable scientific interest, and 
 was pronounced the " best attempt yet made, of the many 
 schemes that had been proposed for producing motive 
 
EL ECTR O-MO TOR ft. 157 
 
 power by the electro-magnet." McGawley's invention, 
 like that of Dal Negro which it very much resembled, is 
 in fact of little value as an electro-magnetic engine ; but 
 it is of much historical importance for the reason that it 
 contained the first automatic circuit-breaker, wires dip- 
 ping alternately first into one cup of mercury and then 
 into another. This was subsequently patented in the 
 United States to Professor Page of Washington ; a pro- 
 ceeding difficult to understand, in view of the fact that 
 Page himself had written to Sir David Brewster, the 
 chairman managing a relief-fund for McGawley's heirs, 
 conceding in explicit terms the invention to McGawley. 
 The fortunes of Thomas Davenport with his electro- 
 motor constitute a curious chapter in the history of the 
 apparatus. Davenport was a country blacksmith, living 
 in Brandon, Vt. By accident he became possessed of one 
 of Henry's magnets, and by dint of hard work and per- 
 severance for he had no special education he con- 
 trived to master the principles involved. This was in 
 1833. By the summer of 1834 Davenport had invented 
 his rotary motor, which he subsequently patented in this 
 country in 1837. It was substantially like the apparatus 
 described by the anonymous writer in "The Mechanics' 
 Magazine" of 1833; except that the armature had elec- 
 tro-magnets instead of permanent magnets, and the field 
 magnet was a permanent magnet instead of an electro- 
 magnet, the apparently earlier contrivance being to this 
 extent reversed. Subsequently he suppressed permanent 
 magnets altogether, and used electro-magnets only, both 
 as field and armature. The machine worked well. It 
 was exhibited in Washington before the President, and 
 subsequently in Saratoga, whither great crowds of people 
 flocked to see it, and lost their heads over it. So did the 
 newspapers, scientific and unscientific. " The American 
 
158 THE AGE OF ELECTRICITY. 
 
 Journal of Science and Arts " concluded that the " power 
 generated by electro-magnetism may be indefinitely pro- 
 longed . . . and increased beyond any limit hitherto at- 
 tained." Davenport thought that a battery "as big as 
 a barrel " would drive the largest machinery, and that 
 ' ' half a barrel of blue vitriol and a hogshead or two of 
 water would send a ship from New York to Liverpool." 
 
 The American people seem to have contented them- 
 selves with purely mental speculation as to the future of 
 the machine, and to have declined pecuniary investment. 
 Consequently Davenport sent the apparatus to England. 
 It captivated John Bull at first sight. Abundant funds 
 were subscribed to build a u big machine," the invari- 
 able requirement, since time immemorial, of the investor 
 in new inventions. Accordingly one was constructed hav- 
 ing four huge electro-magnets aggregating in weight some 
 three hundred pounds. A battery " as big as a barrel" 
 was made to charge it. It had a cast-iron wheel six feet 
 in diameter, and weighing six hundred pounds, which 
 revolved at seventy-five turns a minute. 
 
 Among the scientific men who came to see this new 
 wonder, were Wheatstone (already famous for his inven- 
 tions in telegraphy), Daniell (equally renowned for his 
 invention of the Daniell battery), and Faraday, then in 
 the zenith of his fame as a discoverer. Wheatstone 
 praised the machine in glowing terms ; Daniell waxed 
 enthusiastic over it, and predicted the time when ships 
 would be run across the Atlantic with the aid of a few 
 sheets of zinc and a little acid, yea, not even acid, for 
 the waters of the ocean would supply its place. 
 
 Faraday came last of all. He looked at the huge wheel 
 flying around, with surprise ; and then fixed his gaze more 
 intently on the great spark which was given off every time 
 the current was broken, yielding enough light to illuminate 
 
ELECTRO-MOTORS. 159 
 
 brightly the whole room. The promoters of the machine 
 stood silent, expectantly waiting the verdict from the fore- 
 most scientific authority in the land. After a while, Fara- 
 day walked to the nearest corner, and picked up a broom. 
 Then he placed the handle on the periphery of the wheel, 
 and it was seen that under a slight pressure the speed 
 of the wheel became slower. He did not quite stop the 
 motion, but simply and without a word demonstrated how 
 easily this could be done. Then he called the promoters 
 aside into another room, and gently suggested that his 
 opinion, if made public, would greatly injure the sale of 
 the patent. The interested parties thought it wiser not to 
 press him for that opinion, and he left without giving it. 
 He had found, as others did later, that the power yielded 
 was wholly inadequate for practical use. 
 
 After this Davenport started a paper in New- York 
 City, called "The Electro-Magnet and Mechanics' Intelli- 
 gencer," the first number of which appeared on Jan. 18, 
 1840. He announced it as the first paper ever printed on 
 a press propelled by electro-magnetism. The public re- 
 garded the enterprise rather apathetically. In his second 
 issue, Davenport particularly requested "those who would 
 wish to advance the cause of philanthropy to come for- 
 ward and assist us in our experiment." Perhaps he failed 
 to make clear the connection between his newspaper and 
 the u cause of philanthropy;" or perhaps the public, 
 after three years excitement over his machine, had tired 
 of the subject: at all events, the paper ceased publica- 
 tion, and in the technical journals of the day no further 
 record of Davenport's motor appears. 
 
 One of the best of the early forms of rotary motor was 
 that devised in France by M. Froment, which is represented 
 in Fig. 79. Around the periphery of a skeleton drum are 
 arranged eight pieces of iron, which serve as armatures. 
 
160 
 
 THE AGE OF ELECTRICITY. 
 
 In the frame of the machine are fixed six couples of elec- 
 tro-magnets. (The two upper couples are omitted in the 
 engraving.) When the current is diverted into one of 
 these coils, one of the armatures is attracted, and is 
 moved to a position in front of the pole of the magnet. 
 The wheel is so turned over a certain distance. As soon, 
 
 however, as the armature has thus placed itself, the cur- 
 rent is thrown from the first coil into the next one, which 
 draws the armature to its pole in turn. As all six electro- 
 magnets act in this way, the wheel is continuously rotated. 
 The interest aroused by the exhibitions made by Daven- 
 port in London extended over all Europe ; and in the fall 
 of 1838 Professor Jacobi was invited by the Emperor of 
 
ELECTEO-MOTOES. 161 
 
 Russia to conduct experiments on a large scale, with the ob- 
 ject of determining the practicability of the electro-motor 
 for marine propulsion. Jacobi's vessel was a ten-oared 
 shallop, equipped with paddle-wheels, to which rotary 
 motion was communicated by an electro-magnetic engine. 
 In general there were ten or twelve persons on board ; and 
 the voyage, which was made on the River Neva, was con- 
 tinued for entire days. The difficulty of managing the 
 batteries, and the imperfect construction of the engine, 
 were sources of frequent interruption, which could not be 
 well remedied on the spot. After these difficulties were 
 in some degree removed, the professor gives, as a result 
 of his experiments, that a battery of twenty square feet 
 of platinum will produce a power equivalent to one horse, 
 but he hoped to be able to obtain the same power with 
 about half that amount of battery surface. The vessel 
 went at the rate of four miles per hour, which is certainly 
 more than was accomplished by the first little boat pro- 
 pelled by the power of steam. Jacobi's boat was 28 feet 
 long and 1\ feet in width, and drew 2f feet of water. 
 The machine, which occupied little space, was worked by 
 a battery of sixty-four pairs of platinum plates, each hav- 
 ing thirty-six square inches of surface, and charged, ac- 
 cording to the plan of Grove, with nitric and sulphuric 
 acid. The boat, with a party of twelve or fourteen . per- 
 sons on board, went against the stream at the rate of three 
 miles per hour. This experiment was tried in 1839, and 
 shows what great progress had been made in the period of 
 about one year ; for in 1838, when it was attempted to 
 propel the same boat by the same machine, a battery of 
 about five times the size was required. Jacobi's batteries 
 generated so much gas, that the fumes seriously discom- 
 moded the operators, and -at times compelled them to 
 abandon their experiments ; and even the spectators on 
 
162 THE AGE OF ELECTRICITY. 
 
 the banks were forced to retire when the wind blew in 
 their direction. 
 
 Jacobi wrote a letter, describing his results, to Faraday ; 
 and this, being published, elicited one from Professor 
 Forbes of King's College, Aberdeen, in which for the 
 first time the labors of Mr. Robert Davidson of that place 
 were brought to light. Davidson's most remarkable per- 
 formance was his locomotive. He used two batteries, 
 arranged at each end of his carriage, which energized a 
 number of large electro-magnets. On the wheel-axles 
 were large cylinders, on the peripheries of which were 
 fastened masses of iron. These masses were attracted 
 by the magnets ; and in this way the cylinders were re- 
 volved, so rotating the wheels. The carriage, Davidson 
 claimed, was once tested on the Edinburgh and Glasgow 
 Railway, where it ran at the rate of about four miles per 
 hour. It was sixteen feet in breadth, and weighed some 
 five tons. This report has always, as the newspapers say, 
 "lacked confirmation." 
 
 Davidson's experiments had, however, gone far to show 
 the disadvantages of carrying the batteries on the locomo- 
 tive. In the fall of 1845, "The Mechanics' Magazine " 
 published a letter signed " J. M.," which contained this 
 significant suggestion : 
 
 " Now, suppose we have a railway ten miles long, and 
 that at one terminus is placed an enormous stationary gal- 
 vanic battery, might we not make the rails themselves the 
 conducting lines of the battery? and, the wheels being so 
 arranged as to break the connection where required, a 
 rotating magnet might revolve by the electro-magnetism 
 thus communicated. . . . Perhaps some fertile brain may 
 take the hint, and bring forth soon the 4 electric rail- 
 way/ " 
 
 A fertile brain on this side of the Atlantic was already 
 
ELECTRO-MOTORS. 163 
 
 working on this idea ; and it was carried into practical 
 execution by Mr. John B. Lilly, who in 1846 exhibited in 
 Pittsburg, Penn., a model which was driven by a current 
 passing up one rail and down another, and through the 
 magnets on the car. "Heretofore," says "The Pitts- 
 burgh Journal" of the time, "the propelling power has 
 been used on the car itself : in this instance, however, the 
 power is in the rails ; and an engineer might remain in 
 one town , and with his battery send a locomotive and train 
 to any distance required." 
 
 Five years later Professor Page of Washington made a 
 trial trip, with an electro-magnetic locomotive, between 
 Bladensburg and Washington. It was claimed to be of 
 sixteen horse power, and was provided with a hundred 
 cells of Grove's nitric-acid battery, each having platinum 
 plates eleven inches square. It is stated that the progress 
 of the locomotive was at first so slow that a boy was en- 
 abled to keep pace with it for several hundred feet ; but 
 the speed was soon increased, and Bladensburg, five miles 
 and a quarter distant, was reached in thirt}'-nine minutes. 
 When within two miles of that place, the power of the 
 battery being fully up, the locomotive began to run on 
 nearly a level plane, at the rate of nineteen miles an hour. 
 This velocity was kept up for about a mile, when some of 
 the battery cells cracked, and their liquids became inter- 
 mixed. Considerable time was lost in stoppages ; but 
 the return trip was safely accomplished, the entire running 
 time being one minute less than two hours. It was found 
 on subsequent trials, that the least jolt, such as that caused 
 by the end of a rail a little above the level, threw the bat- 
 teries out of working order, and the result was a halt. 
 This defect, it is said, could not be overcome ; and Pro- 
 fessor Page reluctantly abandoned his endeavors. 
 
 In the same year Thomas Hall of Boston constructed 
 
164 THE AGE OF ELECTRICITY. 
 
 a small locomotive which ran on a track some twenty feet 
 long, and took the current from the rails, the wheels being 
 insulated. It has been claimed for Hall, that he utilized 
 not only a battery to supply his current, but also a dy- 
 namo-electric machine. 
 
 Some twenty-one years had now elapsed since the first 
 electro-motor Dal Negro's mere toy had been pro- 
 duced. In that period both forms of the machine, beam 
 and rotary, had been invented. It had been applied to 
 the propulsion of vessels and of locomotives ; the last 
 being operated by batteries carried by themselves, as is 
 the steam-boiler of the modern railway-engine, and by 
 batteries at a distance, which transmitted their current to 
 the motor through the rails. About all the principal adap- 
 tations of the electric engine had been made. It had 
 claimed the attention and labors of the most noted scien- 
 tists of the world. It had been backed by an emperor of 
 unlimited power, and capitalists representing unbounded 
 wealth had endeavored again and again to make it the 
 basis of successful enterprise. And yet when the success 
 of the electric telegraph, which had seemed far the greater 
 impracticability, aroused the wonder and admiration of 
 the world, the electric motor worked usefully for no man. 
 What was the reason? 
 
 As we have seen, the inventors of the early machines 
 found no trouble in making them go. The beams vibrated, 
 or the wheels spun around, fast enough to make people 
 with vague ideas about speed and power believe that 
 almost limitless energy could be got out of a pint pot. 
 The early inventors, and those who promoted their pro- 
 jects, are not the only persons chargeable with this delu- 
 sion. It exists yet, and crops out occasionally. In 1871 
 a New- Jersey discoverer asserted that he could make a 
 fifty-pound electro-magnet sustain a weight of one hundred 
 
ELECTRO-MOTORS. 165 
 
 and twenty tons with a battery of four Daniell's cells, 
 and drive a five-hundrecl-horse-power engine by the same 
 means, at an expense of but twenty cents a day. An 
 electro-magnetic engine company as usual was organ- 
 ized ; capital, three millions. The engine was to be ex- 
 hibited on the 4th of July year indefinite. Also as 
 usual there was an element of mystery introduced, in 
 the assertion that the battery was merely a connecting 
 link between the machine and some storehouse of mag- 
 netic energy, and therefore, that, while the battery was 
 apparently the source of power, it really was not ; bearing 
 a relation thereto, similar to that of a percussion-cap which 
 fires the charge which impels the cannon-shot. Public 
 interest in this great discovery or, rather, that section 
 of the public interest which is ignorant enough to give 
 such discoveries consideration was transferred two years 
 later to the Keely motor ; which was obviously of much 
 greater importance, because it did not even require the 
 pint pot wherefrom to obtain limitless power. 
 
 The great vicissitude which invariably came to promoters 
 of electro- magnetic engines driven by batteries, was the 
 discovery that they do not pay ; and no amount of glowing 
 anticipations in prospectuses could prevent stockholders 
 becoming painfully aware of this, in the end. It is much 
 cheaper besides far easier to take the mere fuel used 
 in extracting the zinc from its ore, and burn it under a 
 steam-boiler, to drive a steam-engine, and so obtain power 
 in that way, than to go through the roundabout process 
 of extracting the zinc, consuming it in a galvanic cell, 
 and so generating a current wherewith to drive a motor. 
 Zinc, as we have already pointed out, yields about one- 
 seventh the energy of coal, and costs about twenty times 
 as much. Merely comparing the energies derivable from 
 zinc and coal, a steam-engine should be about a hundred 
 
166 THE AGE OF ELECTRICITY. 
 
 and forty times more economical than an electro-motoi 
 driven by a battery. But the best steam-engine and boiler 
 can utilize no more than about two-ninths of the energy 
 of the burning coal ; all the rest being wasted. This 
 reduces the difference : it is " not so deep as a well, nor 
 so wide as a church-door, but 'tis enough," since it leaves 
 the motor some thirty times as expensive in the produc- 
 tion of power as the steam-engine. The efficiency of 
 the motor has no part in this question. The battery is the 
 hopelessly inefficient part of the system ; and it will 
 remain so, no matter how much the motor itself may 
 hereafter be improved. According to Professor Joule, 
 the cost of zinc expended in the Daniell battery, to main- 
 tain one horse power for twenty- four hours, would be 
 $6.25 ; in an ordinary steam-engine, the cost of the same 
 power for the same period would be about twenty-one 
 cents. From a "business" point of view, no further 
 argument is necessary to show why electro-motors driven 
 from galvanic batteries, as were all the early machines, 
 could find no place in the world's work. 
 
 While one set of investigators and inventors were study- 
 ing how to convert electricity into mechanical power, 
 another set, almost simultaneously, were endeavoring to 
 convert mechanical power into electricity. The researches 
 of these last culminated in the modern dynamo electric 
 machine. Now, the machines which generate electricity 
 from motion bear a strong resemblance, in point of gen- 
 eral construction, to those which generate motion from 
 electricity. Let us repeat one illustration already given, 
 to show this. 
 
 Fig. 80 we have already described as a hollow coil of 
 wire, the ends of which are connected to a galvanometer, 
 which shows by the movement of its needle whenever a 
 current circulates in that coil. Into that coil we insert 
 
ELECTRO-MOTORS. 
 
 167 
 
 a smaller coil, the ends of which are connected to a bat- 
 tery. We have seen, that, when the small coil is moved 
 to and fro inside the large one, then the galvanometer will 
 show that a current is being generated in the large coil. 
 We are thus converting the energy of the motion given 
 to the small coil, into electricity. 
 
 Now, let us simply reverse the arrangement of the 
 battery, connecting it to the ends of the large coil, remov- 
 ing the galvanometer. Let us also join the ends of the 
 
 Fig. 80. 
 
 small coil together. Then when the current passes through 
 the large coil, on holding the smaller coil in -the position 
 shown in the engraving we shall feel the large coil pull 
 the smaller one into it, release it when the current is 
 broken, and, if we draw out the small coil, on re-estab- 
 lishing the current it will be pulled back again, so moving 
 to and fro. Here the electricity circulating in the large 
 coil is converted into motion. 
 
 The same thing can be done with the arrangement rep- 
 resented in Fig. 81. We have seen, that, when the per- 
 
168 
 
 THE AGE OF ELECTRICITY. 
 
 manent magnet is moved into and out of the coil, a current 
 is caused in the latter. If the current be sent directly 
 through the coil in one direction, the magnet will be drawn 
 in : if in the opposite direction, it will not be attracted, 
 Or if, instead of the magnet, we use simply a piece of soft 
 iron, then, whenever the current is established, the iron 
 will be drawn inward, and when broken it will be free to 
 be moved out, as by a spring, for example. 
 
 If the foregoing be compared 
 with the engraving of Bourbouze's 
 electro-magnetic engine on p. 155, 
 it will be seen that that apparatus 
 depends exactly on the opeiation 
 last described. An electro-motor 
 is in fact a dynamo or magneto 
 electric machine reversed. If a 
 dynamo is rotated by mechanical 
 power, it will produce an electric 
 current. If an electric current be 
 conducted into a dynamo, its arma- 
 ture will be rotated. Good dynamo 
 machines, in fact, make the best 
 motors ; and the latter, like the dynamos, resolve them- 
 selves, as we have seen, into two types, distinguished by 
 the production of alternating and continuous currents in 
 the armature. There are, however, certain functional 
 differences between motors and dynamos, which require 
 to be met in different ways, and particularly in the pro- 
 portioning of the parts, and the relation of the field and 
 armature systems. These need not be discussed in detail 
 here. 
 
 As the dynamo machine became more and more efficient, 
 it became evident that here was a means of producing 
 electricity which could be used to drive a motor, as well 
 
 Fig. 81. 
 
ELECTEO-MOTOES. 169 
 
 as supply an electric lamp, and which would depend for 
 economy not upon zinc, but upon coal. And thus the 
 modern system of electro-motors, and the transmission of 
 power thereto at a distance, came into existence : and 
 of this the essentials are a heat engine steam or gas 
 to drive a dynamo, which supplies the current to a second 
 dynamo ; and this last converts the energy of the elec- 
 tricity, so supplied, into mechanical motion and work. 
 
 We know that the revolution of the armature of a 
 dynamo produces a current ; and that in large dynamos, 
 producing a very strong current, it is necessary to use 
 powerful engines to turn the armature. But if the circuit 
 in the armature is broken, no such power is required. It 
 is only when the current is being yielded, that hard work 
 must be done to rotate the armature ; and we therefore 
 say that this work has its equivalent in the electric current 
 which flows and in the heat which is caused in the circuit, 
 which is rendered visible by the incandescence of, for ex- 
 ample, an electric lamp placed therein. Now, whether the 
 armature of a dynamo be rotated directly by an engine, or 
 whether it be rotated by a current sent into the machine, 
 a new current will be produced. If the dynamo be turned 
 by the engine, this current will of course be the only one 
 in the circuit ; but if there is already a current existing 
 there, as when the dynamo is driven by electricity, then 
 the new current will be in the opposite direction to the 
 original one, and tend to diminish the latter. This makes 
 complications ; and the result, among other things, is a 
 quantity of mathematical calculation which, if printed 
 here, might perhaps make the non-professional reader 
 shut up this book in despair. 
 
 It will suffice, therefore, to say briefly, that, when the 
 speed of the electro-motor is increased, this back current 
 is also increased. If the motor be loaded so as to do 
 
170 THE AGE OF ELECTRICITY. 
 
 work by moving slowly against considerable forces, then 
 the back current will be small, and only a portion of the 
 energy of the current will be turned into useful work. If, 
 on the other hand, it be run rapidly so as to make con- 
 siderable back current, it will utilize a larger proportion of 
 the energy of the direct current, but can only be run fast 
 enough to do this if its load be very light. When a motor 
 is desired to do its work at the quickest possible rate, 
 it is best operated at such a speed that the supply current 
 is reduced to half its strength ; but when speed is not 
 necessary, a greater economic efficiency is attainable by 
 letting the machine do lighter work, and run faster, so 
 that the back current is nearly equal to the original current, 
 which is thereby reduced to a small fraction of its strength. 
 A Siemens dynamo-electric machine used as a motor can 
 attain an efficiency of over eighty-five per cent. A good 
 dynamo can turn eighty-five per cent of the mechanical 
 power it receives, into the energy of the electric current ; 
 and the electro-motor can convert back eighty-five per cent 
 of the current energy (or seventy-two per cent of the ori- 
 ginal power) into work, losses in the conductor and from 
 leakage being neglected. 
 
 The simplest form of electro-motor is that used on 
 electric bells. This consists of an electro-magnet which 
 moves a hammer backward and forward, alternately attract- 
 ing and releasing it. In Fig. 82, E is the electro-magnet, 
 and C the hammer. By touching the push-button P, 
 which is also shown enlarged in section, the circuit from 
 the battery L is completed, and a current flows along the 
 line and around the coils of the electro-magnet, which 
 attracts a small piece of soft iron attached to the lever $, 
 which terminates in the hammer C. The lever is itself 
 included in the circuit, the current entering it below and 
 quitting it by a contact-breaker A, consisting of a spring 
 
ELECTRO-MOTORS. 
 
 171 
 
 tipped with platinum, resting against the platinum tip of 
 a screw from which a return wire passes back to the bat- 
 tery. As soon as the lever S is attracted forward, the 
 circuit is broken at A by the spring moving away from 
 contact with the screw : hence the current stops, and the 
 electro-magnet ceases to attract the armature. The lever 
 and hammer therefore fall back again, establishing con- 
 tact at A, whereupon the hammer is once more attracted 
 forward, and so on. 
 
 Fig. 82. 
 
 The most important modern application of electro- 
 motors is to the driving of locomotives. The credit of 
 the first successful electrical railway is due to Dr. Werner 
 Siemens, who built in Berlin, in 1879, a narrow-gauge line, 
 laid down in a circle some nine hundred yards in length. 
 A train of three or four carriages was placed upon it ; 
 and on the first carriage a dynamo-electric machine was 
 fixed to the axle of one pair of wheels, in such a manner 
 as to rotate the wheels when the armature of the machine 
 was rotated by the passage of a current through its coils. 
 
172 
 
 THE AGE OF ELECTRICITY. 
 
 The rails were laid upon wooden sleepers, which, even in 
 wet weather, insulated the rails very well for this length of 
 line. A third rail ran between the other two, and it was by 
 this central conductor that the current was led from the 
 generating-machine placed at one terminus of the line. 
 The current was drawn from this rail to the armature of the 
 machine on the locomotive, by means of a brush of cop- 
 per wires ; and after traversing the coils of the armature, 
 it was led to the axle of the driving-wheels, which was 
 insulated from the body of the car, and thence by the 
 driving-wheels to the outer rails, and by them back to 
 
 the dynamo ma- 
 chine at the termi- 
 nus. Fig. 83 repre- 
 sents a section 
 through the loco- 
 motive, showing 
 the dynamo - elec- 
 tric machine 5, 
 and the central rail 
 JV, with the metal 
 brush for abducting 
 the current. 
 
 Between twenty and thirty persons could be accom- 
 modated on the train at a time, including the conductor, 
 who rode on the first carriage ; and during the course of 
 the summer no fewer than a hundred thousand were con- 
 veyed over the line at a speed of from fifteen to twenty 
 miles an hour. Crowded trains left the stations every 
 five or ten minutes, and a considerable sum was earned 
 in this way for the benefit of charitable institutions. 
 The locomotive was capable of exerting five horse-power ; 
 and instead of being fitted with a steam valve like a 
 locomotive to start or stop it, it was simply provided with 
 
 Fig. 83. 
 
ELECTRO-MOTORS. 173 
 
 a commutator for closing or opening the circuit of the 
 current. 
 
 On the Siemens railway at the Paris exhibition of Sep- 
 tember, 1881, a distance of over sixteen hundred feet was 
 traversed in a minute, which is at the rate of nearly 
 twenty miles per hour. 
 
 In this country, electric railways have in many locali- 
 ties replaced ordinary street-railway systems depending 
 on horses and dummy engines. At South Bend, Ind., 
 for example, two twenty-horse-power dynamos are driven 
 by a water-wheel, and supply current to one ten-horse- 
 power and three five-horse-power motors. The track is 
 laid with the ordinary flat rail, the rails being connected 
 by copper plates. The other part of the circuit consists 
 of a copper wire suspended above the track. From the 
 under side of this wire hangs a carriage fastened to a 
 flexible cable, passing to the inside of the car, where it 
 is in connection with the switches, the motor, etc. When 
 full current is turned on, the maximum speed of eight 
 miles per hour is attained, this being the highest rate of 
 travel allowable in the city limits. An electric railway 
 was constructed in the fall of 1885 at the New-Orleans 
 Exposition. Others are in successful operation in Balti- 
 more, Minneapolis, Montgomery (Ala.) ; and there are 
 probably few large cities in the country in which some 
 system of electric railway has not been projected. At 
 the date of writing (1886), experiments have for some 
 time been in progress with the object of substituting elec- 
 tric engines for the steam-engines on the elevated-railway 
 lines in the city of New York. On the Ninth-avenue 
 road, arrangements have been made to employ the form 
 of electric locomotive devised by Mr. Leo Daft. The 
 total weight of the machine as constructed is 8f tons. 
 The current is taken from the rails, which are insulated, 
 
174 THE AGE OF ELECTEICITY. 
 
 and is supplied by dynamos situated at a main station. 
 A third rail between the track rails is employed for the 
 return current, and contact is made with this by means of 
 a wheel which can be moved into or out of position. The 
 maximum gradient of the road is one of a hundred and 
 five feet to the mile. This has been surmounted with 
 ease, with fairly well loaded trains ; and an average 
 speed of twenty miles per hour has been attained. The 
 latest, as well as the most efficient electro-locomotive, is 
 that devised by Mr. F. J. Sprague. This, also, at the 
 present time, is being experimented upon on the elevated 
 railways of New- York City. To describe the construc- 
 tion of Mr. Sprague's apparatus, would necessitate much 
 technical detail not suited to these pages ; but the prac- 
 tical results which he has attained, especially in control of 
 speed, prevention of loss of power, and facility of stopping 
 and starting, renders his motor a decided and very meri- 
 torious advance in electric propulsion. 
 
 It is impossible to fix a limit to the possible speed of 
 electric locomotives ; but it is not improbable that eventu- 
 ally it will be found practicable to drive them at much 
 higher velocities than the steam-locomotive has ever at- 
 tained. The advantages of electricity over steam for 
 railway propulsion are so great as to render the former 
 almost an ideal prime motor. The locomotive itself is 
 virtually done away with, for in many cases the electric 
 motor can be placed under the car. As regards economy, 
 it has recently been pointed out that " the evaporation of 
 pounds of water to each pound of coal to make steam 
 in locomotive-boilers does not average over 3J pounds of 
 water, using the best grades of bituminous coal ; while 
 with stationary boilers, set to burn coal-screenings for 
 fuel, an evaporation of nine pounds of water to one 
 pound of fuel is made, and the reduction in cost of fuel 
 
ELECTRO-MOTORS. 175 
 
 is from one-third to one-half." The cost, therefore, of 
 making the electric power, is already greatly less than 
 that of generating steam-power in moving locomotives : 
 and when electricity comes to be supplied, as it eventually 
 will be, like gas and water, from great central generating 
 stations, to be used for all purposes, the expense of its 
 production will without doubt be still further lessened. 
 Add to the above advantages, freedom from smoke and 
 sparks, noiseless machinery and motion, and absolute con- 
 trol by the mere pressure of a finger, and one may predict 
 with every certainty that the electric steed will replace the 
 steam horse, as certainly as the latter did the horse of 
 flesh and blood. 
 
 Electric power is already sold from central stations, in 
 many places, just as steam-power is sold, with profit to 
 both seller and buyer. The price at present is about the 
 same as that for steam for small powers. In Boston, 
 steam is generated from coal-screenings, to drive the 
 engine which actuates the dynamos ; and the power is 
 transmitted all over the city, being used for running all 
 kinds of machinery, including sewing-machines, ventilator- 
 fans, printing-presses, elevators, etc. 
 
 It appears that ordinarily the loss in the process of con- 
 version of power into electricity, and transmitting power 
 from the dynamo to the receiver, amounts to from forty 
 to fifty per cent. "Electrical transmission," says a 
 recent writer, "has the unparalleled advantage of being 
 superior to the obstacle presented by distance. Then, 
 again, it operates its miracles in perfect silence and 
 repose. No force appears in the wire, such as appears in 
 shafting, in pipes with compressed air or water, in endless 
 chains or belts ; and in case of powerful currents, insula- 
 tion is easy. The conductor can be bent or shifted in any 
 way while transmitting many horse-power ; provided, of 
 
176 THE AGE OF ELECTRICITY. 
 
 course, its continuity be not interrupted. It can be car- 
 ried round the sharpest corners, through the most private 
 rooms, into places where no other transmitter or power 
 could possibly be taken. There is nothing to burst or 
 give away. In short, such a method of transmission is 
 the acme of dynamical science." 
 
 Electro-motors have been ingeniously adapted to the 
 driving of tricycles by Professors Ayrton and Perry. The 
 motor is suspended beneath a platform under the seat, 
 and is driven by several cells of storage-battery, which 
 are supported on a second and lower platform. The 
 machine has been driven at a speed of about six miles per 
 hour. 
 
 Electric launches have also been constructed. One 
 built by Messrs. Yarrow & Co., in 1883, measures forty 
 feet in length by six feet beam, and is capable of carry- 
 ing forty passengers. The motor is a Siemens machine, 
 driven by a storage-battery ; the weight of motor and bat- 
 teries being about two and a quarter tons. The speed of 
 the boat is about eight miles per hour. For the propul- 
 sion of ships' boats, electrical motors possess marked 
 advantages over steam-engines ; as an electric launch is 
 much more easily swung from a ship's davits than a steam- 
 launch, it has no fire to be put out in case of shipping 
 seas, and the machinery will work under water. 
 
 The application of an electric motor to the guiding of a 
 balloon has been made by M. Gaston Tissandier, with 
 fairly successful results. The balloon used was lenticular 
 in form. The motor was arranged in the car, and caused 
 to rotate a large propelling-fan. The current was obtained 
 from a number of bichromate-of-potash batteries. The 
 motor was so arranged that its speed might be varied from 
 sixty to a hundred and eighty revolutions per minute. 
 With the high speed, the forward motion of the balloon 
 
ELECTRO-MOTORS. 177 
 
 under the influence of its propeller was plainly observable, 
 and for a short period it maintained its place even against 
 a moderate breeze. It was also found possible to swerve 
 the balloon from the direction of the wind. 
 
 Telpherage is a name coined by the late Professor Flee- 
 ming Jenkin, to designate a system devised by him, by 
 which the transmission of vehicles by electricity to a dis- 
 tance is effected independently of any control exercised 
 from the vehicle. It is an aerial electrical railway, as at 
 present projected, in which the track is either a single or 
 double wire rope from which the carriages or skips are 
 suspended. The line is divided into sections, each a hun- 
 dred and twenty feet in length ; and each section is in- 
 sulated from its neighbor. A train is made up of a loco- 
 motive and a series of skips held at uniform intervals 
 apart by wooden poles extending from skip to skip. The 
 skips hang below the line from V-wheels supported by 
 arms which project out sideways so as to clear the sup- 
 ports at the posts : the motor or dynamo on the locomo- 
 tive is also below the line. The entire train is a hundred 
 and twenty feet in length, the same length as that of a 
 section. A wire connects one pole of the motor with the 
 leading- wheel of the train, and a second wire connects 
 the other pole with the trailing-wheel : the other wheels 
 are insulated from each other. Thus the train, wherever 
 it stands, bridges a gap separating the insulated from the 
 uninsulated section. The insulated sections are supplied 
 with electricity from a dynamo driven by a stationary 
 engine ; and the current passing from the insulated section 
 to the uninsulated section, through the motor, drives the 
 locomotive. This wilt be easily understood from the dia- 
 gram Fig. 84. Here one pole of the dynamo is connected 
 to the left-hand extremity of the conductor represented by 
 the continuous line ; the other pole being connected to the 
 
178 THE AGE OF ELECTRICITY. 
 
 uninsulated line shown dotted. M and ^/"represent two 
 trains. When these are in the position shown, it will be 
 evident that a portion of the dynamo current will go 
 through each train as indicated by the arrows ; and this 
 current passing through the motor in the locomotive sets 
 it in motion, and so propels the train. 
 
 Vhinmtdfad 
 
 Fig. 84. 
 
 Another arrangement, called the series system, is illus- 
 trated in the diagram Fig. 85. Here there is but a single 
 wire, on which the trains are supported ; this consisting of 
 a series of spans. The breaks between these spans are 
 normally kept closed by means of switches. Each switch 
 is opened automatically as soon as a train bridges it, so 
 
 Fig. 85. 
 
 that the current is thus caused to pass through the train, 
 and so keep it in motion. When a train has passed over 
 a break, the switch is automatically closed, so that the 
 continuity of the circuit through the wire is preserved. 
 
 Telpherage is as yet in its infancy, and, in fact, has not 
 been tried on a sufficiently extensive scale to determine 
 
ELECTRO-MO TOES. 
 
 179 
 
 even the most salient questions bearing upon its econom- 
 ical efficiency. So far as can be foreseen, the invention 
 
 bids fair to be of great practical value. Professor Jenkin 
 has pointed out that " wherever railways and canals do 
 not exist, telpher lines will provide the cheapest mode of 
 
180 THE AGE OF ELECTRICITY. 
 
 inland conveyance for all goods such as corn, coal, root- 
 crops, herrings, hides, etc., which can be conveniently sub- 
 divided into parcels of one, two, or three hundred weight. 
 In new colonies, the lines will often be cheaper to make 
 than roads, and will convey goods far more cheaply. In 
 war they will give a ready means of sending supplies 
 to the front. Moreover, wherever a telpher line exists, 
 power is thereby laid on ; and this power may be used for 
 other purposes than locomotion. A flexible wire attached 
 to the line will serve to drive a one, two, or three horse 
 engine, which may be used for any imaginable purpose, 
 such as digging, mowing, threshing, or sawing." Tel- 
 pher lines will also act as " feeders of great value to the 
 railways, extending into districts which could not support 
 the cost even of the lightest railway." Fig. 86, from a 
 photograph, represents Professor Jenkin's first line. The 
 buckets, or skips, weighed about three hundred pounds 
 each, the locomotive the same. Each skip carried as a 
 useful load about two hundred and fifty pounds. The 
 projected speed was five miles per hour, at which it was 
 estimated about ninety-two and a half tons hourly of 
 freight could be conveyed. 
 
 General Thayer, U.S.A., has devised a remarkable sys- 
 tem of war balloons, which are designed to travel upon 
 wires or light cables stretched across the country on ordi- 
 nary poles. The balloon itself is in the shape of a cir- 
 cular spindle, and supports a deck for the transport of 
 troops, cannon, etc. The electricity is generated at the 
 end of the line, and is conveyed along the wires to a motor 
 on the deck of the balloon. The motor drives the wheels 
 which impel the balloon along the cable. General Thayer 
 states that such a road could be built at the rate of from 
 three to four miles a day, at a cost of fifteen hundred dol- 
 lars per mile, and the speed attained might be from sixty 
 
ELECTRO-MOTORS. 181 
 
 to seventy miles per hour. The wire could be run across 
 country in a direct line, where it would be impossible to 
 build a railway. Men and ammunition could thus be 
 rapidly transported ; and, as an army advances into an 
 enemy's country, the balloon-way could be put up in its 
 rear, and thus establish a line of communication with its 
 base of supplies. 
 
182 THE AGE OF ELECTRICITY. 
 
 CHAPTER X. 
 
 ELECTROLYSIS. ELECTRO-METALLURGY AND THE STORAGE- 
 BATTERY. 
 
 IN the galvanic battery a chemical re-action takes place, 
 and the result is the production of an electric current. If, 
 conversely, we place in a decomposable liquid two con- 
 ducting bodies, and thus enable a current of electricity to 
 pass through the liquid, we shall find that the result is a 
 chemical decomposition. This decomposition by means 
 of the electric current is called electrolysis ; the liquid 
 decomposed is known as an electrolyte, and the two con- 
 ducting bodies are termed electrodes. In a galvanic cell, 
 a definite amount of chemical action evolves a current, 
 and transfers a certain quantity of electricity through the 
 circuit : so, conversely, a definite quantity of electricity, 
 in passing through an electrolytic cell, will perform a 
 definite amount of chemical work. An electrolytic cell 
 is, therefore, the converse of a voltaic cell. 
 
 The discovery of the decomposing effects of the electric 
 current was made by accident, and followed almost im- 
 mediately after the invention of Volta's pile. Volta 
 addressed a letter to Sir Joseph Banks, then President 
 of the Royal Society, on March 20, 1800, wherein he an- 
 nounced the discovery of his pile. The first portion only 
 of this letter, which described the construction of the ap- 
 paratus, was sent on the above date ; and the remainder 
 
ELECTROLYSIS. 183 
 
 followed during the succeeding month of June. Until the 
 latter date, the whole missive was not published ; but in 
 the meanwhile Sir Joseph Banks showed such parts as he 
 had received, to Mr. W. Nicholson and Mr. (afterwards 
 Sir) Anthony Carlisle. These two gentlemen at once con- 
 structed a pile composed of silver half-crown pieces, alter- 
 nated with equal disks of copper, and cloth soaked in 
 a weak solution of common salt. It so happened, that a 
 drop of water was used to make good the contact of the 
 conducting wire with a plate to which the electricity was 
 to be transmitted. In noticing this, Carlisle observed a 
 disengagement of gas from the water ; and Nicholson rec- 
 ognized the "odor of hydrogen " coming from it. They at 
 once took measures to determine the cause of this singular 
 
 Pile 
 
 Fig. 87. 
 
 effect ; and, using the first materials at hand, filled a piece 
 of glass tube with water, plugging both ends with cork, 
 and inserting through each cork a piece of brass wire, as 
 shown in Fig. 87. When the wires P and N were put in 
 communication with opposite ends of the pile, bubbles of 
 gas were evolved from the point of the wire by which the 
 current left the tube, and the end of the wire by which 
 the current entered became tarnished. The gas evolved 
 appeared on examination to be hydrogen ; and the tarnish 
 was found to proceed from the oxidation of the entrance, 
 or positive, wire. In order to prevent this oxidation of 
 the material of the wire itself, another apparatus was 
 made, in which platinum wires were used. Then gas was 
 evolved from both wires ; and this, ascending through the 
 
184 THE AGE OF ELECTRICITY. 
 
 water, was collected separately in two tubes. The con- 
 tents of the tubes being examined, hydrogen was found 
 in one, and oxygen in the other ; the two gases being 
 almost exactly in the proportions known to constitute 
 water. 
 
 In this way the decomposing power of the electric cur- 
 rent was established very shortly after the first knowledge 
 of Volta's invention had reached England. Of course, 
 experiments so remarkable attracted the attention of other 
 investigators. Cruickshank decomposed a variety of com- 
 pound substances, and found, that, as a consequence of 
 decomposition, the acids and oxygen always collected 
 around the positive wire, by which the current came in ; 
 and hydrogen, metals, and the alkalies, around the nega- 
 tive wire, by which the current went out. The pile as 
 Volta had made it became manifestly inadequate to the 
 production of the strong and uniform currents that were 
 needed ; and to meet this want Cruickshank devised his 
 well-known trough battery, in which zinc and copper 
 plates were fixed in vertical grooves, the liquid being in- 
 terposed between the successive pairs of plates. Cruick- 
 shank's battery, or modifications of it, are still in common 
 use. 
 
 Meanwhile, a young German chemist, Ritter of Jena, 
 had also independently discovered the electro-decomposi- 
 tion of water and saline compounds ; and, more than this, 
 he had found out that this singular decomposing power 
 could be transmitted through sulphuric acid, so that, if on 
 both sides of the acid there were water, oxygen and hydro- 
 gen would still be evolved from the wires clipping in the 
 water. It seemed, therefore, that one or the other of the 
 elements of water must have passed through the sulphuric 
 acid : for, clearly, if the water was decomposed at the 
 positive wire, where only oxygen appeared, the hydrogen 
 
ELECTROLYSIS. 185 
 
 must somehow get across to the negative wire ; while, if 
 the decomposition occurred at the negative wire, then 
 oxygen must also in some unexplained way cross over to 
 the positive wire. 
 
 This was the singular phenomenon which attracted the 
 notice of a scientific student who was then just com- 
 mencing the labors which earned for him an imperish- 
 able name. Humphry Davy wondered whether, if the 
 two wires were immersed each in a glass of pure water, 
 the gases would be produced. He tried it : nothing 
 happened. Then he put a finger of his right hand in 
 one glass, and a finger of his left hand in the other. 
 It was very extraordinary : then the gases appeared. 
 Next he got three people to stand in a row, hand in 
 hand, forming a chain between the glasses : still the 
 gases appeared. It was a simple experiment, the ex- 
 periments of most great thinkers are simple, but it 
 demonstrated conclusively, that, if any material princi- 
 ple passed between the wires, it must have been trans- 
 mitted through his body, or the bodies of all three 
 people who formed the line of communication between 
 the gases. 
 
 Then in October, 1800, began Davy's famous experi- 
 ments which stand and will stand forever as the founda- 
 tions of a great branch of electrical science. Beginning 
 upon the voltaic pile itself, he found that the chemical 
 changes in it were the cause of its electrical effects, and 
 that the action in a cell is similar to the decomposition of 
 water at the extreme wires of the pile ; that a battery 
 could be made of liquid elements with conducting-plates 
 of identical material placed in them. And then, branching 
 from the chemical to the calorific properties of the battery, 
 he constructed a huge apparatus whereby he fused wire, 
 and for the first time produced the electric arc between 
 
186 THE AGE OF ELECTRICITY. 
 
 carbon points. Brilliant as Davy's discoveries then were, 
 they were merely the prelude of others which startled the 
 world. 
 
 When water was first decomposed, it was noted that at 
 the positive electrode there were always present indica- 
 tions of an acid, while at the negative electrode an alkali 
 appeared. There were not wanting philosophers who 
 jumped to the conclusion that here were new things in 
 water, not known in anybody's philosophy. One wanted 
 to suppose an "electric acid," a neat example of the 
 art of explaining something which is not understood, by 
 giving a name to it. Another insisted that the acid and 
 alkali were ' ' generated ' ' out of the elements of the water 
 by voltaic action ; thus anticipating the later claims to 
 other singular things ' ' generated ' ' from water by the 
 inventor of the so-called Keely motor. One peculiarly 
 conscienceless individual announced that the most care- 
 fully distilled water nevertheless yielded "muriate of 
 soda." Why "muriate of soda," he failed to explain; 
 and some people, anxious to know about this, who called 
 at the address appended to his memoir, came back, 
 and said that nobody of the author's name lived there. 
 Altogether, although the fact of electro-decomposition 
 had been established, the subject as a w r hole was in a 
 state of confusion ; and it was to bring order but of 
 this chaos, that Davy resumed his investigations into 
 electro-chemistry. 
 
 The first thing he did was to explode thoroughly and elabo- 
 rately the notion that any thing but hydrogen and oxygen 
 could be got out of water ; provided the water was pure, and 
 such disturbing causes as acids and alkalies in the vessels 
 used were eliminated, not in the vessels in the sense of 
 contained in them, but in their substance, be it noted. 
 And from this singular circumstance, that the current 
 
ELECTROLYSIS. 
 
 187 
 
 was powerful enough to drag acids and alkalies out of 
 the very material of cups of agate and glass, grew the 
 idea that the same power might be brought to bear on 
 other bodies, and thus force from substances hitherto 
 considered simple and elementary, the secrets of their 
 complex composition. 
 
 Davy's first efforts were directed to potash. The alkali 
 liquefied by heat was placed on a platinum disk, which 
 was connected with the negative pole of a battery, while 
 a wire connected with the positive pole was applied to its 
 upper surface. At the upper surface there was a dis- 
 engagement of gas ; at the lower surface, small metallic 
 globules appeared, like mercury in appearance. Some of 
 these burned by contact 
 with air. The gas dis- 
 engaged at the positive 
 wire was oxygen ; and 
 the metal deposited was 
 the base of the alkali 
 afterwards called po- 
 tassium, thus for the 
 
 first time revealed. In like manner, from soda Davy pro- 
 duced the metal sodium ; and then from baryta, strontia, 
 lime, and magnesium, came barium, strontium, calcium, 
 and magnesium. Still more refractory materials were then 
 attacked ; and alumina, silica, zirconia, and glucinia 
 yielded silicium, aluminum, glucinium, and zirconium. 
 
 Davy not only found that the electric current was capa- 
 ble of decomposing compound bodies, but also of trans- 
 ferring or, if the term maybe permitted, of decanting 
 their constituents from one vessel to another. Some 
 of the results of his experiments were most singular. 
 Three cups were arranged as shown in Fig. 88 ; the posi- 
 tive wire entering the cup P, and the negative wire enter- 
 
 Fig. 88. 
 
188 THE AGE OF ELECTRICITY. 
 
 ing the cup N. I is an intermediate cup, between which 
 and the cups P and ^V extend strips of asbestos, A, which 
 act as siphons. The current then passed from the positive 
 wire through the liquid in cup P, thence by the asbestos 
 through the liquid in cup /, by the asbestos again to the 
 liquid in cup JV, and so out to the negative wire. The 
 negative cup jVwas filled with a solution of sulphate of 
 potash ; the centre cup, with water in which litmus had 
 been infused ; and the positive cup P contained simply 
 distilled water. When the current passed, the acid con- 
 stituent of the sulphate of potash should appear at the 
 positive pole P ; but, to get there, it obviously would 
 have to traverse the litmus solution in the middle cup /. 
 Now, litmus is a very delicate test for the presence of an 
 acid, inasmuch as, normally dark blue, it at once reddens 
 when acid is added to it ; and hence the passage of the 
 acid should thus be at once revealed. But, strange to say, 
 although the acid of the sulphate went over to the positive 
 pole, and actually through the litmus solution, no redden- 
 ing of the latter followed. If the acid thus seemingly 
 lost its power, in transit, to affect vegetable solutions, 
 what would happen if a strong alkali were put in the 
 middle cup? Would the acid and alkali instantly rush 
 together by reason of their affinity, as they had done since 
 the beginning of the world ? No : sulphuric acid went 
 directly through a solution of ammonia, without produ- 
 cing chemical change. Hydrochloric and nitric, strongest 
 of the acids, were driven through concentrated alkalies : 
 conversely, strong alkalies were passed through strong 
 acids. It seemed as if either alkali or acid, when in the 
 control of the current, was powerless until the current 
 had forced it to its destination. One exception appeared 
 to this rule : sulphuric acid could not be driven through 
 stroutia or baryta, nor the latter through sulphuric acid ; 
 
ELECTROLYSIS. 189 
 
 precipitation occurred in the middle cup. The result of 
 the affinity was, however, an insoluble substance ; and so 
 it was determined, that, wherever the element transmitted 
 forms, with the medium through which it passes, an 
 insoluble compound, the passage is stopped. But that in 
 other cases the transmission did go on, and the affinities 
 of the substances were suspended, was evident from the 
 fact, that, when the current was broken for a moment, 
 combination of acid molecules with the alkali through 
 which they were travelling instantly occurred. 
 
 In 1826 Nobili discovered, that when a current of elec- 
 tricity is passed into a solution of acetate of lead by 
 means of a plate of platinum, and out of it by means of a 
 platinum wire, rings of beautiful colors, caused by the for- 
 mation of thin films of peroxide of lead, appeared on the 
 platinum plate. These colors are very like those produced 
 on steel in tempering, and on the surface of molten lead, 
 which are due to a film of oxide overspreading the metal. 
 
 In another chapter we have alluded to the splendid 
 discoveries in magneto-electricity, made by Faraday in 
 1831. Three years later he supplemented these with 
 the investigations which established the laws of electro- 
 chemistry. He found that the amount of chemical action 
 in the cell is always proportional to the quantity of elec- 
 tricity passing through it ; and that the quantities of sub- 
 stances dissolved and set free by electrolysis are in definite 
 proportions by weight, and these proportions are identical 
 with the ordinary chemical equivalents of the substances. 
 From the first law we know that a current of a certain 
 strength will always liberate just so much hydrogen, for 
 example, from water, and will cause the solution of just 
 so much zinc in the cell whence the current is derived. 
 To illustrate the second law: nine grains of water, for 
 example, contain eight grains of oxygen and one grain 
 
190 
 
 THE AGE OF ELECTRICITY. 
 
 of hydrogen ; and hydrogen and oxygen always combine 
 in these proportions to form water. Now, if we tear 
 apart, so to speak, the constituents of water, we shall 
 always find eight grains of oxygen at the positive elec- 
 trode, and one grain of hydrogen at the negative electrode. 
 Why this happens, is not definitely proved ; but the gen- 
 erally accepted theory, that of Grothuss, is neatly illus- 
 trated in the accompanying engraving, Fig. 89, which 
 represents the case of hydrochloric acid, each molecule 
 of which is composed of one atom of hydrogen and one 
 atom of chlorine. The plate A is the positive electrode, 
 
 and the plate B the neg- 
 
 f-l \\ ative electrode. The 
 
 oval objects are sup- 
 posed to represent the 
 molecules ; the white 
 half of each represent- 
 ing chlorine, and the 
 dark half hydrogen. 
 The row marked 1 
 shows the molecules 
 distributed at random, as before the current passes. When 
 the current is established, the molecules arrange them- 
 selves in innumerable chains in which every molecule has 
 its constituent atoms pointing in a certain direction ; for, 
 as we see, all the chlorine atoms point to the positive plate 
 A, and all the hydrogen atoms to the negative plate B. 
 Now, if the current is strong enough, the chlorine half of 
 the molecule next the positive plate is divorced from its 
 wedlock with the hydrogen half. Atoms abhor celibacy. 
 They are polygamous or polyandrous to the last degree ; 
 but single-blessedness they will have none of if they can 
 help it. So, no sooner is the hydrogen atom off with the 
 old love, before it is immediately on with the new ; because 
 
 Fig. 89. 
 
ELECTROLYSIS. 191 
 
 it promptly appropriates the chlorine partner of its next 
 neighbor. The thus deserted hydrogen atom helps him- 
 self to his neighbor's consort in like manner ; and so on 
 through this singular chain, until at last there is a hydrogen 
 atom left solitary and alone at the negative plate, matching 
 the solitary chlorine atom at the positive plate, as in row 
 3. And so it looks as if all the chlorine atoms had some- 
 how made their way to one plate, and all the hydrogen 
 atoms to the other. Faraday called these apparently 
 migrating atoms ions ; and gave the name anode to the 
 positive plate, and cathode to the negative plate. Then 
 the ions which went to the anode were termed anions ; 
 and those which appeared at the cathode, cathions. 
 
 There was a grave and dignified professor once, who by 
 dint of much persuasion was induced to attend a dancing- 
 party. Among the complicated figures of the German, 
 there was one in which the several couples interchanged 
 partners until a single couple were left unmated. The 
 professor, who had regarded the proceedings hitherto 
 rather stoically, and with a somewhat bored expression, 
 suddenly brightened, and emitted a peculiar pleased 
 chuckle which the writer well knew from past experience 
 was of the same character as that which always followed 
 a neat bit of scientific demonstration, accompanied by a 
 muttered " Beautiful, ah, beautiful ! " 
 u Who, professor?" was asked. 
 "Who? Nobody. It's what they're doing." 
 " Oh, the German figure. Yes, it is rather " 
 "German figure? Oh, you mean Grothuss, of course. 
 But now, doesn't that doesn't this interchange of the 
 women beautifully beautifully illustrate his idea of the 
 migration of the ions? Eh? " 
 
 Two years after Faraday had made his discoveries, De 
 la Rue observed the singular fact, that in a peculiar form of 
 
192 THE AGE OF ELECTRICITY. 
 
 Daniell's battery the copper plate became covered with a coat- 
 ing of metallic copper, which took the exact impress of the 
 plate, even to the fine scratches upon it. In 1837 Dr. Gold- 
 ing Bird decomposed the chlorides of sodium, potassium, 
 and ammonium, and deposited their respective metals on a 
 negative pole of mercury, thus obtaining their amalgams. 
 
 It would have been almost a phenomenal occurrence if 
 the discovery soon to be made, and which ultimately be- 
 came of such great industrial importance, should have 
 failed to have more than a single claimant ; but the pro- 
 cess of electrotypiug differs from most other electrical 
 discoveries in that all the claimants appeared at once, and 
 did not come stringing along after the manner of their 
 kind, for years after some one, bolder than the others, had 
 announced his success. In 1839 Jacobi in St. Petersburg, 
 Spencer in Liverpool, and Jordan in London, described 
 independently a method of converting any line, however 
 fine, engraved on copper, into a relief, by galvanic pro- 
 cess, by depositing copper upon the engraved object. 
 Jacobi published his description in a newspaper ; Jor- 
 dan wrote a letter to the editor of "The Mechanics' 
 Magazine;" and Spencer, last of all, read a paper on 
 the subject before the Liverpool Polytechnic Society, 
 all in the same year. Their respective adherents argued 
 about their respective priority of invention, quite steadily 
 in the public prints, for the next three years, and inter- 
 mittently contradicted one another for some time after- 
 wards. Spencer wrote the best account of what he had 
 done, despite the fact that his opponents sneered at him 
 for being only a carver and gilder, and not a professor, 
 which to their minds logically disproved, of course, his 
 pretensions, and the general public somehow understood 
 what he wrote about ; for, as a recent writer remarks, 
 u thousands of persons, of all classes of society, at once 
 
ELECTROLYSIS. 193 
 
 became fascinated by the new art.*' At about this time 
 the Elkingtons of London began coating military and other 
 metal ornaments with gold and silver, simply by immersing 
 them in solutions of those metals. In 1840 John Wright, 
 a surgeon of Birmingham, came to them with the news 
 that he had succeeded in obtaining electrically a thick, 
 firm, and white deposit of silver, upon articles treated in 
 a liquid made by dissolving the cyanide of this metal in 
 an alkaline cyanide. The Elkingtons saw the value of 
 his discovery, and did what would have been impossible 
 in this country, embodied Wright's idea in their patent; 
 not for the purpose of depriving Wright of his reward, 
 but in order to perfect and complete the description of a 
 process which proved to be the basis of all successful 
 electroplating of gold and silver. Wright, in fact, profited 
 well, for he was paid a royalty of one shilling an ounce 
 for every ounce of silver deposited ; and a handsome 
 annuity was settled on his widow after his death. 
 
 The history of electro-chemistry from this point is that 
 of technical details, out of place here ; so that we pass at 
 once to practical applications, and these are fourfold : 
 first, electrotyping, or the copying of types, casts, or other 
 objects, by deposits of metal ; second, electroplating, or 
 the covering or plating of objects of baser metal, with a 
 thin film of another metal, usually gold or silver ; third, 
 the reduction of metals from solutions of their ores ; and, 
 fourth, the secondary or storage battery. 
 
 Electrotyping finds its widest utilization in the repro- 
 duction of engravings and pages set in type. A mould 
 of the object, made in wax, lightly covered with plumbago 
 so that a conducting surface may be present, is placed in 
 a bath of saturated solution of sulphate of copper, and 
 attached to the cathode, or pole at which the current leaves 
 the bath. A plate of copper is attached to the anode, or 
 
194 THE AGE OF ELECTRICITY. 
 
 wire at which the current enters. This plate is decom- 
 posed at the same rate as the copper is deposited from the 
 solution, on the plumbago-covered surface of the mould ; 
 and in this way the strength of the solution is kept uni- 
 form. The copper, as it is deposited, covers every por- 
 tion of the surface with a bright layer, usually starting 
 from the suspending wire and extending itself gradually 
 over the entire area. Generally the electrotyping opera- 
 tion takes about twenty-four hours ; but for newspaper 
 work this time is necessarily much shortened. It is not 
 uncommon for pages of illustrated papers, especially if 
 containing important engravings of recent events, to be 
 electrotyped in eight, six, and even four hours. 
 
 When a good adherent film of copper has been depos- 
 ited over the surface, the mould is removed. The wax 
 is melted to liberate the electrotype, which is then backed 
 with an alloy of lead, antimony, and tin. The plate thus 
 produced is an absolutely exact reproduction of the origi- 
 nal types or relief engraving from which the wax mould 
 was made. It only remains to mount the plate upon a 
 block of wood, type high, when it is ready to take its 
 place in the form which is placed in the printing-press. 
 Usually the woodcuts and types are set up and arranged in 
 page form, and then the whole page is electrotyped. The 
 pages before the reader have been thus prepared. When 
 an electrotype is to be submitted to hard usage, as when 
 a great many impressions are to be taken from it, it is 
 sometimes coated with a pellicle of electrically deposited 
 iron. Messrs. Christofle & Co. of Paris have recently 
 made very beautiful electrotypes by the direct deposition of 
 nickel in the mould, strengthened by a copper backing. 
 
 The electrotyping process has been used on a large 
 scale for the reproduction of statues of even colossal di- 
 mensions. In such cases, instead of making moulds the 
 
ELECTROLYSIS. 195 
 
 plaster-of -Paris figure itself is sacrificed. The mode of 
 operation is interesting. 
 
 After the figure is well saturated in linseed oil, it is 
 covered with a film of black-lead, and then placed in 
 a large cistern of sulphate-of-copper solution, which is 
 allowed to precipitate its copper on the object until a coat- 
 ing is formed of about one-sixteenth of an inch in thick- 
 ness. The object is then lifted from the bath, the copper 
 envelope cut through at suitable places, the plaster figure 
 broken away with great care, and the whole of it extracted. 
 The outer surfaces of the copper forms (with wires 
 attached) are now thoroughly varnished all over, to pre- 
 vent any deposit being formed thereon ; the forms exposed 
 to sulphuretted hydrogen, to prevent adhesion of the depos- 
 it ; and the parts are immersed in the depositing- vat again, 
 which is filled with copper solution. A dissolving plate of 
 pure electrotype copper is suspended within each portion, 
 and a deposit of copper thus formed all over its interior, 
 until a considerable thickness, varying from one-eighth to 
 one- third of an inch, is deposited, which requires a period 
 of three or four weeks. Each piece is now removed from 
 the liquid, washed, and the outer shell torn off ; when all 
 the parts of the figure remain nearly complete, and ready 
 for fixing together. Some of the objects made by this 
 process, by the Messrs. Elkington, are colossal. The 
 statue of the Earl of Eglinton is thirteen and a half feet 
 high, and weighs two tons ; and the vat in which it was 
 formed is capable of holding 6,680 gallons of liquid. 
 The Messrs. Christofle made a statue twenty-nine feet six 
 inches high, and weighing about five and a half tons. 
 About ten weeks were required to deposit the metal. 
 
 Electroplating is now practised with a great variety of 
 metals. The ordinary arrangement of a silver-plating 
 bath, to which a battery-cell supplies current, is represented 
 
196 THE AGE OF ELECTEICITY. 
 
 in Fig. 90. Of late years, the nickel-plating of all sorts 
 of metal articles, from the parts of steam-engines down 
 to surgical instruments, has become a very important 
 branch of the industry, replacing to a great extent gold 
 and silver plating. Nickel-plated articles take a fine pol- 
 ish, do not tarnish, and their coating is hard and lasting. 
 The solutions commonly used for nickel-plating were in- 
 vented by Mr. Isaac Adams, and patented in this coun- 
 try in 1869. They may be the double chloride of nickel 
 and ammonium, or the double sulphate of nickel and 
 
 Fig. 90. 
 
 ammonium ; the bath being neutral, that is, neither acid 
 nor alkaline, upon which fact the success of the Adams 
 process greatly depends. The cheapness of nickel, and 
 the rapidity with which it is deposited, from fifteen min- 
 utes to an hour, when the dynamo is used to supply cur- 
 rent, being sufficient time, have resulted in nickel-plating 
 becoming an eveiy-day process in many engineering work- 
 shops. 
 
 It can hardly be said, however, that nickel-plating is 
 anywhere carried on on the gigantic scale in which silver- 
 plating is practised, especially in Europe. The house of 
 
ELECTROLYSIS. 197 
 
 Cbristofle & Co. in Paris annually deposits more than thir- 
 teen thousand pounds of silver, and since its establishment 
 in 1842 has used not less than a hundred and eighty-five 
 tons of that metal. 
 
 Gold is usually deposited from the double cyanide of 
 gold, and potassium. The metal is sometimes deposited 
 in solid form upon moulds for the production of articles 
 of jewellery having very complex or under-cut ornaments 
 upon them. By the use of certain solutions, the gold- 
 plating can be beautifully colored ; and in this way the 
 red gold, orange gold, etc., of fashionable jewellery, are 
 produced. In gilding base metals, a film of copper or 
 brass is generally first produced upon them. The insides 
 of vessels are gilded by filling the vessel with the gold 
 solution, suspending a gold anode in the liquid, and pass- 
 ing the current. Many very beautiful objects of art are 
 made by incasing in gold, silver, and copper, for exam- 
 ple, ferns, foliage, flowers, insects, and lizards. So also 
 anatomical specimens, such as brains, have been thus 
 treated ; the electro-deposit preserving every minute wrin- 
 kle and fissure. An even more grim application has re- 
 cently been proposed by a French chemist who advocates 
 the coating of the bodies of the dead with impervious 
 platings of gold, silver, or copper, as a means of preserv- 
 ing them. He even suggested making statues in this way. 
 Copper has been deposited upon fabrics and upon glass, 
 and is almost invariably applied to the carbons of arc 
 lights. 
 
 The electrolytic refining of copper, for the purpose of 
 obtaining the metal in a chemically pure state, is largely 
 carried on in Europe. The Keith process of refining lead 
 is utilized, we believe, in this country only. The precious 
 metals are commonly separated in the electrolytic bath by 
 combining them with copper to form an anode and then 
 
198 THE AGE OF ELECTRICITY. 
 
 electrically depositing the copper, leaving the gold and 
 silver as a residuum. 
 
 A curious application of electroplating is in the manu- 
 facture of the so-called compound telegraph-wire, which 
 consists of a central wire of steel covered with a coating 
 of copper. This coating is deposited upon the steel by 
 galvanic action, while the wire is drawn continuously 
 through a long trough containing the solution. A wire 
 thus made is found to offer much less resistance to the 
 current than an ordinary iron wire. 
 
 Up to within a few years, the use of electricity for 
 actual work, such as lighting or driving motors, has been 
 attended with a great drawback, almost as important as 
 the high cost of generating the current ; and that is, it 
 has been necessary to make the electricity as it is needed. 
 We can store water in a reservoir, and use it to drive a 
 wheel at one time as well as another. We make gas dur- 
 ing the day, and store it in huge gasometers from which 
 a supply is drawn at night. But with electricity it is 
 necessary to keep a constant current flowing through 
 the conductor, equal to meeting all likely needs, whether 
 it is actually utilized or not. Of course this involves 
 continual expense, unremitting wear of machinery, and 
 a great deal of additional apparatus ready to take the 
 place of any thing which may break down or need re- 
 pair. Inasmuch, also, as the hours of the night when 
 lights are needed are few, it is necessary to have very 
 powerful machinery, capable of supplying a great deal of 
 electricity in a short time. The reader can easily imagine 
 how much greater the cost of gas would be if all of it 
 had to be made between the hours of G P.M. and midnight, 
 instead of its being produced as it is, throughout the day. 
 In fact, at the present time central stations for the supply 
 
ELECTROLYSIS. 199 
 
 of electricity from dynamos employ their capital fruitfully 
 only about six hours in the twenty-four. 
 
 The question of how to store electricity so that we can 
 generate it at one time, and use it at another, is therefore 
 of very great moment. We know, however, that electri- 
 city is not a thing capable of storage, any more than it is 
 a thing capable of being burned in a lamp. The water 
 which in falling drives a wheel is not consumed : simply 
 its energy is expended. If we go a step farther, and 
 cause the wheel thus driven to wind up a spring, or lift a 
 weight, we know that we can keep the spring wound up, 
 or the weight in its lifted position, as long as we choose ; 
 and that when we release the spring, or drop the weight, 
 then we can use the energy thus stored. So that we are 
 not to conceive of the idea of pouring an electrical fluid 
 into something, and keeping it there ; but of causing the 
 energy which exists in the form we know as electricity, to 
 become stored, just as the energy of the water becomes 
 stored in the wound-up spring or lifted weight. There is, 
 therefore, no such thing as storage of electricity. What 
 is really done is the changing of the electrical energy from 
 the active condition to the potential condition, from the 
 state in which it may be doing work, to the state in which 
 it is not doing work but is capable of so doing. 
 
 We have already found that if we plunge the ends of 
 two wires leading from a galvanic cell into water, or, 
 better, dilute sulphuric acid, bubbles of gas will appear 
 upon the immersed wires, hydrogen at the wire by which 
 the current leaves, oxygen at the wire by which it enters. 
 This experiment is usually shown by means of the appa- 
 ratus shown in Fig. 91. This consists of a glass vessel 
 (V) containing water, and also two glass test-tubes (AB) 
 inverted over a pair of platinum plates projecting up from 
 the bottom of the cell or vessel. These plates are con- 
 
200 THE AGE OF ELECTRICITY. 
 
 nected by wires to the poles of the voltaic battery (O), as 
 shown ; and therefore they act as electrodes, and pass the 
 current from the battery through the water. Now, as the 
 water is decomposed, the hydrogen gas is found to collect 
 on the cathode, by which the current is supposed to leave 
 the water, while the oxygen collects on the anode, by which 
 the current is believed to enter the water ; and as the gases 
 are lighter than the water, they rise into the upper ends of 
 the tubes. The volume of hydrogen at the cathode is 
 
 A B 
 
 Fig. 91. 
 
 always twice the volume of oxygen at the anode, and this 
 agrees with the known constitution of water. Further, the 
 quantity of water decomposed in a given time is propor- 
 tional to the strength of the electric current ; and hence, if 
 the tubes are graduated to show the volume of gases col- 
 lected in them, the instrument becomes a voltameter, or 
 current-measurer. Faraday arranged the apparatus in the 
 form shown in Fig. 92, so that the gas could easily be col- 
 lected and measured. Here two small platinum plates dip 
 in the acidulated water, and are connected to wires which 
 
ELECTROLYSIS. 
 
 201 
 
 pass up through the cork of the bottle : binding-screws 
 are attached to the upper ends of these wires, and a glass 
 tube fixed into the cork serves to discharge the gas formed 
 within. When the binding-screws are connected to the 
 poles of a battery, the water in the bottle is decomposed, 
 and the hydrogen and oxygen rise to the surface. 
 
 In this voltameter we have two plates and a liquid in a 
 suitable vessel. If one of these plates were zinc, and the 
 other copper, we know that the zinc would be attacked by 
 the acidulated water, 
 and the apparatus 
 would at once be a 
 galvanic cell capable 
 of yielding its own 
 current. But here the 
 plates are both of the 
 same material, im- 
 mersed in one liquid ; 
 and hence one is not 
 more attacked than the 
 other, and the arrange- 
 ment cannot act as a 
 galvanic cell. 
 
 When, however, the electric current from another bat- 
 tery is sent into the voltameter, then its plates respectively 
 yield, as we have seen, hydrogen and oxygen ; and these 
 gases, in fact, coat the plates. Now they have become 
 different. Hydrogen and oxygen form a galvanic pair 
 by themselves ; and as soon as the voltameter is discon- 
 nected from its charging battery, and its wires brought 
 into contact, a current is set up through that wire, which 
 goes from the hydrogen to the oxygen within the liquid. 
 
 It will be remembered, that, in referring to the so-called 
 polarization of the primary form of the galvanic battery, 
 
 Fig. 92. 
 
202 
 
 THE AGE OF ELECTRICITY. 
 
 Balttty 
 
 Fig. 93. 
 
 we noted that after the hydrogen had formed on the un- 
 attacked element, a current occurred from the hydrogen 
 to the zinc, which ran opposite to and so greatly weakened 
 or destroyed the original current. In the voltameter there 
 is a like action, and the current yielded by the voltameter 
 is in the reverse direction to that of 
 the battery current which charged it. 
 Let us fix this with a diagram (Fig. 
 93). Here we have first the primary 
 cell, with its wires joined. The cur- 
 rent goes in the liquid from zinc to 
 carbon, and thence back by the wire to 
 the zinc, the arrows showing the direc- 
 tion. Next, we connect the cell to the 
 voltameter (Fig. 94) . Here the current goes from the car- 
 bon to one plate of the voltameter, and produces oxygen 
 thereon ; then through the liquid to the other voltameter 
 plate, where hydrogen is generated ; then back to the zinc, 
 and so through the cell to the carbon again. Now dis- 
 connect the voltame- 
 ter, and join its wires 
 (Fig. 95). Then the 
 current goes in the 
 liquid from the hy- 
 drogen to the oxy- 
 gen, and then by the 
 wire back to the hy- 
 drogen. Compare 
 the direction of this 
 current as indicated by the arrows, with the direction of 
 the current in the battery cell, similarly indicated, and it 
 will be seen that the currents move in opposite directions. 
 We have now accomplished a very important result. 
 That is, by the action of an electric current we have made 
 
 Fig. 94. 
 
ELECTROLYSIS. 
 
 203 
 
 a contrivance into a galvanic cell which before was not 
 one ; or, to put it in another way, we have led a current 
 into something from which, after the source of supply is 
 wholly disconnected, we can get a current out. This 
 is electrical storage the misuse of the term aside. It 
 looks as if we had poured the electricity into the volta- 
 meter, just as we might pour in the liquid, and afterwards 
 drawn out the one as we might the other. 
 
 The voltameter reversed as above described yields, 
 however, only a momentary current ; for very little of the 
 gases stay on the plates, the greater portion mixing and 
 rising as we have seen. The gases do not act on either 
 plate, because the material of the latter, 
 platinum, is not easily attacked. 
 
 The first secondary battery was de- 
 vised by Ritter of Jena, very shortly 
 after the invention of the voltaic pile. 
 It had been found, that, if an oblong 
 slip of wet paper have its extremities in 
 contact with the poles of the pile, each 
 half of the slip will be electrified ; and 
 if it be removed from contact with the pile, by a rod of 
 glass or other non-conductor, its electric state will continue. 
 This was observed by Volta, and, according to Dr. Lardner 
 (writing in 1841), " was the means of suggesting to Ritter 
 the idea of his secondary pile ; which consisted of a series 
 of disks of a single metal, alternated with cloth or card 
 moistened in a liquid by which the metal would not be 
 affected chemically. If such a pile have its extremities 
 put in connection, by conducting substances, with the 
 poles of an insulated voltaic pile, it will receive a charge 
 of electricity in a manner similar to the band of wet paper, 
 one half taking a positive and the other a negative 
 charge ; and, after its connection with the primary pile 
 
204 
 
 THE AGE OF ELECTRICITY. 
 
 has been broken, it will retain the charge it has thus re- 
 ceived. The secondary pile, while it retains its charge, 
 produces the same physiological and chemical effects as 
 the voltaic apparatus." 
 
 In 1859 M. Gaston Plante made a secondary cell based 
 upon the principles above briefly sketched. Instead of 
 plates of platinum he used plates of 
 lead, rolled as shown in Fig. 90. The 
 consequence was, that, when the cur- 
 rent passed through these, the oxygen 
 produced at one plate combined with 
 the metal, and deposited lead oxide ; 
 the hydrogen as before remained free 
 on the other plate. Thus he produced 
 a cell in which, after the charging cur- 
 rent was removed, were elements of lead 
 and lead oxide. These being connected 
 yielded a current, but, however, for a 
 short time, because but very little of the 
 oxide was produced, a mere film on 
 the surface. Plante" thereupon devised 
 his so-called "forming" process, which 
 consisted in first charging his plates, 
 then discharging, then charging again 
 with the battery current reversed, and 
 so on, increasing intervals of rest being left between the 
 operations ; until finally he produced, through the repeated 
 oxidations and subsequent reductions of the oxidized ma- 
 terial to a metallic state, very porous or spongy plates. 
 These, by reason of their porosity, exposed a very large 
 surface to the oxidizing action of the current, so that the 
 result was as if he had charged a plate of great superficial 
 area. 
 
 As we have already shown, when batteries are connected 
 
 Fig. 96. 
 
ELECTROLYSIS. 
 
 205 
 
 in multiple arc, that is, all the zinc plates together, 
 and all the copper plates together, then the plates of 
 each kind act as one large plate, the surfaces of all being 
 added together. Plante found that if he charged a num- 
 ber of secondary cells connected in this way, and, after 
 charging, if he arranged his cells in series, that is, the 
 positive plate of one con- 
 nected to the negative plate 
 of the next, and so on, he 
 could obtain very powerful 
 currents for short periods of 
 time. 
 
 In 1880 M. Camille Faure 
 covered Plante" 's lead plates 
 with red lead, and then put 
 them in little flannel jackets. 
 The peculiarity of the red 
 lead is, that, on sending a 
 current through it, it is easily 
 changed into spongy lead ; so 
 that, instead of the ' ' form- 
 ing " operation taking weeks 
 and months, it can be done 
 in a few days or even hours. 
 This discovery apparently re- 
 moved the chief obstacle to 
 Planters cells becoming of 
 
 commercial value ; and when it was announced, it was 
 hailed as an extraordinary advance. 
 
 Since 1880 a great many patents have been obtained 
 for secondary batteries, and they now exist in many forms. 
 An example of the Faure type is Reynier's cell, which is 
 represented in Fig. 97. In a glass jar are placed two 
 spirals of rolled lead plate, against which the red lead is 
 
 Fig. 97. 
 
206 THE AGE OF ELECTRICITY. 
 
 held by serge instead of the felt or flannel which Faure 
 adopted. Mainly, however, the efforts of inventors have 
 been directed to reducing the weight of the cells, and to 
 devising new ways of holding the red lead on the plates. 
 Brush packs his red lead or other active material in a 
 frame of cast lead containing slots, cells, or openings. 
 Sellon also makes a plate with receptacles for containing 
 and holding the active material. 
 
 The storage-battery at the present time is simply a sub- 
 ject for further research and invention. No form of it 
 exists in which grave defects are not present. The value 
 and efficiency of many of the cells offered in the market 
 have been over-estimated, and often greatly misunder- 
 stood. None are more eager to grasp at possible im- 
 provements than those who to-day most loudly vaunt the 
 great merit of their own particular advertised contriv- 
 ances ; this not infrequently in the hope that the large 
 amounts of capital already risked may by some stroke of 
 good fortune be saved from loss. 
 
 The commonest defects of the storage-cell are ' ' nee- 
 dling," "buckling," and "disintegration." Needling is 
 the formation of the so-called "lead tree," fine spiculae 
 of metal between the electrodes, which causes short cir- 
 cuiting and rapid waste of current. Buckling is the defor- 
 mation or bending of the plates themselves, whereby one 
 plate often makes contact with another, and short circuit- 
 ing again follows. Disintegration and buckling also are 
 usually due to chemical changes in the electrodes. The 
 plates, disintegrating in time, drop to pieces. Besides 
 these difficulties, certain solutions cause very high internal 
 resistance in the cell ; and there are a variety of other 
 disadvantages. 
 
 One of the best forms of storage battery is that devised 
 by Mr. Willard E. Case, in which he uses a neutral liquid, 
 
ELECTROLYSIS. 207 
 
 from which he deposits metal on one electrode while 
 peroxidizing the other. 
 
 Mr. Case's investigations in the storage-battery have 
 led him to the remarkable discovery that heat can be 
 directly converted into electricity in the galvanic cell. He 
 places in his cell an electrode of tin, an electrode of car- 
 bon, and a liquid which at ordinary temperature will not 
 attack either electrode. Therefore no current is yielded. 
 But as soon as the liquid is warmed, and to do this the 
 cell, which is hermetically sealed once for all, is merely put 
 into hot water, chlorine is set free from the liquid, and 
 attacks the tin. Then the current starts, and continues 
 until all the tin is converted into chloride. Now, if the 
 cell be allowed to cool, the chlorine releases the tin, and 
 returns to the liquid ; and so the cell regains its original 
 state. The chlorine, in fact, is a chemical pendulum, 
 swinging from liquid to tin, and from tin to liquid, as often 
 as the heat is applied and removed. Of course the cell 
 lasts indefinitely ; theoretically, forever. No material is 
 used up in it. The temperature is never above that of 
 boiling water. Its electro-motive force is about one-quarter 
 volt. 
 
 In one sense this cell may be regarded as a heat-storage 
 battery : it is really a wonderfully efficient heat-engine. 
 It is not merely a most beautiful and ingenious illustration 
 of the correlation and interconvertibility of the natural 
 forces, but an advance apparently destined to be of the 
 highest practical value. 
 
 Electrolysis has been applied to the rectification of 
 alcohols, the improvement of wines, and to the deposition 
 of aniline dyes. 
 
208 THE AGE OF ELECTRICITY. 
 
 CHAPTER XI. 
 
 THE ELECTRIC TELEGRAPH. 
 
 THE earliest suggestion of the electric telegraph appears 
 in the Prohisiones Academics of Strada, an Italian Jesuit, 
 who in 1617 spoke of " the instantaneous transmission 
 of thoughts and words, between two individuals, over an 
 indefinite space," caused by a species of loadstone, which 
 possesses such virtue,- that, if two needles be touched 
 with it, and then balanced on separate pivots, and the 
 one turned in a particular direction, the other will sympa- 
 thetically move parallel to it. These needles were to be 
 poised and mounted on a dial with the letters of the 
 alphabet around. 
 
 In " The Spectator " of 1712, Addison proposes the 
 sending of love-letters in this way. In 187G, when the 
 speaking telephone first appeared, and before many peo- 
 ple had any conception of its extraordinary capabilities, 
 4 'The New- York Tribune" suggested that its principal 
 value might lie in the fact that lovers and diplomatists 
 could thus secretly converse ; and thus history repeated 
 itself. 
 
 There was no lack of experiments upon electric tele- 
 graphs during the last century. All of them depended 
 upon the idea of sending the charge of static or frictional 
 electricity through one or more wires ; for the galvanic 
 battery had not yet been invented. 
 
THE ELECTRIC TELEGRAPH. 209 
 
 In 1729 Gray and Wheeler produced motion in light 
 bodies at a distance of 666 feet. In 1747 Dr. Watson, 
 in the presence of many scientific persons, transmitted 
 electricity through twenty-eight hundred feet of wire and 
 eight thousand feet of water, thus making use of the 
 earth circuit. In the following year Franklin fired spirits 
 on one side of the Schuylkill River, by the discharge from 
 an electrical battery on the opposite bank. 
 
 Then followed a curious series of endeavors to adapt 
 the results of the experiments of Watson and Franklin 
 to every-day use. The first practicable form of electric 
 telegraph was described in "The Scots Magazine" in 
 1753, in an anonymous communication over the initials 
 C. M. The article was entitled " An Expeditious Method 
 of conveying Intelligence." It was proposed to extend 
 wires, equal in number to the letters of the alphabet, 
 between two distant places ; support them at intervals on 
 glass fixed to solid bodies ; let each wire terminate in a 
 ball ; place beneath each ball a shred of paper on which 
 the corresponding letter of the alphabet has been printed. 
 Bring the farther end of the first wire into contact with 
 an excited glass tube, and the paper A will instantly rise 
 to the first ball. Thus the whole alphabet may be repre- 
 sented. Here, evidently, was the idea of complete insu- 
 lation of the conducting wire, and at the distant end the 
 production of a signal which should be either visible or 
 audible*; for the inventor also proposed a series of bells, 
 differing in tone from A to Z, instead of the paper. 
 
 Very little is known of the inventor. Sir David Brews- 
 ter asserts that his name was Charles Morrison. It is 
 frequently quoted as Charles Marshall. In fact, about 
 the only definite information ever obtained was from a 
 very old Scotch lady who remembered a "very clever 
 man, of obscure position, ' who could make lichtnin' write 
 
210 THE AGE OF ELECTRICITY. 
 
 an' speak, and who could licht a room wi' coal reek ' (i.e., 
 coal smoke)." That a great genius thus became lost to 
 the world, can hardly be doubted ; for here was a man 
 who had seen farther into the mysteries of electricity than 
 Franklin himself. We can easily imagine his fate. Being 
 ahead of his time, his neighbors those typical neighbors 
 of the inventor, who mend the adage to make the prophet 
 not only without honor, but with positive dishonor, in his 
 own country called him a visionary and a madman. 
 There is more true pathos in the many stories of the 
 stout hearts thus broken, than in all the romantic vicissi- 
 tudes of the Abelards and the Heloises since the Flood. 
 
 For several years following, little advance was made. 
 Lomond in 1787 proposed a single wire and a pith-ball 
 electrometer. Reizen in 1794 contrived a telegraph like 
 Marshall's, but added letters of the alphabet cut out in 
 pieces of tin-foil and rendered visible by sparks. Cavallo 
 went back to the single-wire idea, and used sparks to 
 designate the various signals, and an explosion of gas 
 to alarm the operator. 
 
 Then came a lapse of some fifteen years, and mean- 
 while the voltaic pile was discovered. When the inventors 
 came to apply this to telegraphy, they went to work in 
 the same old way. Soemmering, in 1809, used as many 
 wires as there were signals, but varied these by producing 
 them by the decomposition of water. The battery not 
 proving very successful, Mr. (afterwards Sir) Francis 
 Ronalds abandoned it in favor of the more intense dis- 
 charge of the Leyden-jar ; and arranged a pith-ball elec- 
 trometer at the end of his line, wherewith he made his 
 signals. 
 
 This was done in 1816. Seventy years had elapsed 
 since Watson's experiment proving the possibility of 
 transmitting the electrical discharge over long distances. 
 
THE ELECTRIC TELEGRAPH. 211 
 
 Yet the actual advance made toward a practicable and 
 useful electric telegraph had been scarcely any thing. 
 The discharge could be sent over one wire ; and repeated 
 sparks, or movements of a pith-ball, would indicate sig- 
 nals the weather permitting. It could be sent over 
 twenty-six wires, and each wire might then make its own 
 signal. The signals might be produced by the decomposi- 
 tion of water or salts, or by explosions, or illuminations of 
 tin-foil letters. It is not surprising that the Lords of the 
 Admiralty in 1813, after considering one of the many plans 
 submitted to them, said that as the war was not over, and 
 money scarce, they thought best not to carry it into effect. 
 Oersted's grand discovery came in 1819, and in 1820 
 Ampere devised the galvanometer. He was quick to see, 
 that, if the current could deflect the needle at a short 
 distance, there was a possibility of its doing the same at 
 a long distance ; but he was unable, apparently, to break 
 away from the multiple- wire idea. He, too, proposed the 
 use of as many wires as letters or signals to be indicated. 
 That happened in the same year that the electro-magnet 
 was invented by Arago. Looking back on these proceed- 
 ings now, it seems as if all these philosophers and inventors 
 of Europe were groping through a labyrinth, one following 
 the blind lead of the static charge, and another that of 
 the multiple wire ; some rejecting the very means which 
 would conduct them to a successful ending, in the belief 
 that they were merely obstacles ; others clinging to obsta- 
 cles, in the belief that they were clews. In 1820 the 
 actual elements of the telegraph of to-day were in their 
 grasp. They had the electro-magnet, the conducting wire, 
 and the galvanic battery ; but no eyes to see what could 
 be accomplished by these means. So far as they knew, 
 no battery could send its current over a long line, and 
 magnetize something at the other end. 
 
212 THE AGE OF ELECTRICITY. 
 
 The European philosophers kept on groping. At the 
 end of five years, one of them reached an obstacle which 
 he made up his mind was so entirely insurmountable, 
 that it rendered the electric telegraph an impossibility 
 for all future time. This was Mr. Peter Barlow, fellow 
 of the Koyal Society, who had encountered the question 
 whether the lengthening of the conducting wire would pro- 
 duce any effect in diminishing the energy of the current 
 transmitted, and had undertaken to resolve the problem. 
 Here is his conclusion in his own words : 
 
 " It had been said that the electric fluid from a common 
 electrical battery had been transmitted through a wire four 
 miles in length, without any sensible diminution of effect, 
 and to every appearance instantaneously ; and if this 
 should be found to be the case with the galvanic current, 
 then no question could be entertained of the practicability 
 and utility of the suggestion before adverted to. I was 
 therefore induced to make the trial, but I found such a con- 
 siderable diminution icith only two hundred feet of wire, as 
 at once to convince me of the impracticability of the scheme." 
 
 Barlow's conclusion would possess no especial interest 
 now, other than that which would necessarily attach to the 
 views of any eminent observer of the period, were it not 
 for the singular fact, that the circumstance of its publica- 
 tion had probably more to do with the later successful 
 realization of the electric telegraph, than any other occur- 
 rence in the history of the invention. The year following 
 the announcement of Barlow's conclusions, a young grad- 
 uate of the Albany (N.Y.) Academy byname Joseph 
 Henry was appointed to the professorship of mathemat- 
 ics in that institution. Henry there began the series of 
 scientific investigations which is now historic ; thus bril- 
 liantly opening a career which at its end found him easily 
 the first among American scientists. 
 
THE ELECTRIC TELEGRAPH. 213 
 
 Up to that time, electro-magnets had been made with 
 a single coil of naked wire wound spirally around the 
 core, with large intervals between the strands. The core 
 was insulated as a whole : the wire was not insulated at 
 all. Professor Schweigger, who had previously invented 
 the multiplying galvanometer, had covered his wires with 
 silk. Henry followed this idea, and, instead of a single 
 coil of wire, used several. He says, " These experiments 
 conclusively proved that a great development of mag- 
 netism could be effected by a very small galvanic ele- 
 ment ; and, also, that the power of the coil was materially 
 increased by multiplying the number of wires, without 
 increasing the length of each." He also found that he 
 could obtain stronger results with the wires so wound that 
 the pitch of one spiral should be the reverse of that of 
 the spiral beneath it. And lastly he discovered that a 
 magnet with a long fine-wire coil must be worked by a 
 battery having high electro-motive force, composed of 
 a large number of cells in series, when a distant effect 
 was required ; and that the greatest dynamic effect close 
 at hand is produced by a battery of a very few cells of 
 large surface, combined with a coil or coils of short thick 
 wire around the magnet. 
 
 " But, be this as it may," says Henry, after describing 
 his discoveries as above very briefly outlined, "the fact 
 that the magnetic action of a current from a trough is at 
 least not sensibly diminished by passing through a long 
 wire is directly applicable to Mr. Barlow's project of form- 
 ing an electro-magnetic telegraph, and also of material 
 consequence in the construction of the galvanic coil." 
 
 Barlow had said that the gentle current of the galvanic 
 battery became so weakened, after traversing two hundred 
 feet of wire, that it was idle to consider the possibility of 
 making it pass over even a mile of conductor and thec 
 
214 THE AGE OF ELECTRICITY. 
 
 affect a magnet. Henry's reply was to point out that the 
 trouble lay in the way Barlow's magnet was made. The 
 resistance of the line weakened the current. Start, then, 
 with a strong current, an " intensity current," Henry 
 said : let the line resistance weaken it, but make the mag- 
 net so that the diminished current will exercise its full 
 effect. Instead of using one short coil, through which 
 the current can easily slip, and do nothing, make a coil of 
 many turns ; that increases the magnetic field : make it 
 of fine wire, and of higher resistance. And then, to prove 
 the truth of his discovery, Henry put up the first electro- 
 magnetic telegraph ever constructed. In the academy at 
 Albany, in 1831, he suspended 1,060 feet of bell-wire, 
 with a battery at one end and one of his magnets at the 
 other ; and he made that magnet attract and release its 
 armature. The armature struck a bell, and so made the 
 signals. 
 
 Annihilating distance in this way was only one part of 
 Henry's discovery. He had also found, that, to obtain 
 the greatest dynamic effect close at hand, the battery 
 should be composed of a very few cells of large surface, 
 combined with a coil or coils of short coarse wire around 
 the magnet, conditions just the reverse of those neces- 
 sary when the magnet was to be worked at a distance. 
 Now, he argued, suppose the magnet with the coarse short 
 coil, and the large-surface battery, be put at the receiving- 
 station ; and the current coming over the line be used 
 simply to make and break the circuit of that local battery. 
 That is a very small thing to do, very different from mak- 
 ing the tired current, so to speak, work a lot of signalling 
 or recording mechanism. The local battery and magnet 
 then do the hard labor ; the current coming over the line 
 merely controls the force : or, in other words, instead of an 
 engine driven by power coming from a very long distance, 
 
THE ELECTRIC TELEGRAPH. 215 
 
 and wasted greatly on its way, we have one operated by 
 power immediately at hand, but controlled from a point 
 miles away. This is the principle of the telegraphic 
 " relay." In 1835 Henry worked a telegraph-line in that 
 way at Princeton. And thus the electro-magnetic tele- 
 graph was completely invented and demonstrated. There 
 was nothing left to do, but to put up the posts, string the 
 lines, and attach the instruments. The question asked 
 thousands of years before by the prophet, "Canst thou 
 send lightnings, that they may go, and say unto thee, 
 Here we are?" Henry had answered in the affirmative. 
 It remained for other men, following his example, to go 
 and do likewise. 
 
 It is, as we have said, a common misfortune of invent- 
 ors, to be ahead of the times in which they live ; and this 
 was Henry's experience. It is true that he contributed to 
 the result himself, by refusing to patent his ideas, and so 
 hiding his light under a bushel. But the fact none the 
 less remains, that here was a discovery not merely of 
 transcendent importance, but one which the world had 
 been eagerly trying to make for years ; and yet, when it 
 was achieved, no one stood ready to put it to practical 
 use. So little was it known or appreciated, that when on 
 April 15, 1837, the Secretary of the Treasury, Hon. Levi 
 Woodbury, sent out a circular letter proposing inquiries 
 on the subject of a system of telegraphs for the United 
 States, the Franklin Institute of Philadelphia, the leading 
 scientific body of the land, could find nothing better to 
 recommend than the semaphore, or mechanical telegraph. 
 The report advocates the erection of forty stations be- 
 tween New York and Washington ; each station being a 
 building twenty-two feet square, with a quadrangular 
 pyramidal roof on which the swinging arms of the sema- 
 phore were to be mounted. By moving the arms into 
 
216 THE AGE OF ELECTRICITY. 
 
 different positions, numbers and letters were to be indi- 
 cated, and the observer at one station would be enabled to 
 recognize the signals made at the next station, some seven 
 miles away, by means of a telescope. "In conclusion," 
 says the report, ' ' the committee would respectfully sug- 
 gest to the Secretary of the Treasury to consider the pro- 
 priety of causing two telegraphs to be erected, in which 
 careful experiments may be made on all the points which 
 bear upon the general questions submitted to him by the 
 House of Representatives." 
 
 Meanwhile one electric telegraph had been erected in 
 this country. This was based on the use of the static 
 discharge. It was put up by Harrison Gray Dyer, on a 
 race-course on Long Island ; and it is a noteworthy fact, 
 that he strung his wires on glass insulators upon trees and 
 poles. The electrical discharge, after passing over the 
 wire, acted upon litmus paper to produce a red mark. 
 The difference in time between the sparks indicated dif- 
 ferent letters, arranged in an arbitrary alphabet ; and the 
 paper was moved by hand. This line was used in 1827- 
 28. 
 
 It will be apparent, therefore, that, at the time the fore- 
 going report was made by the Franklin Institute, both of 
 the two known systems of electric telegraphy had been 
 practically tested in this country ; the static-discharge 
 telegraph by Dyer, and the electro-magnetic telegraph by 
 Henry. "In 1832," says Henry, "nothing remained to 
 be discovered in order to reduce the proposition of the 
 electro-magnetic telegraph to practice. I had shown that 
 the attraction of the armature could be produced at any 
 distance, and had designed the kind of a battery and coil 
 around the magnet to be used for this purpose. I had 
 also pointed out the fact of the applicability of my experi- 
 ments to the electro-magnetic telegraph." Five years 
 
THE ELECTRIC TELEGRAPH. 217 
 
 after this, the learned scientists of the Franklin Institute 
 offered to the Government the services of their committee 
 to experiment, not upon electric telegraphs, but sema- 
 phores ! 
 
 Among the replies forwarded to the Secretary of the 
 Treasury, in answer to his circular, were three letters 
 signed Samuel F. B. Morse, all advocating the establish- 
 ment of an electro-magnetic telegraph. Morse was an 
 artist of some repute, but not in any sense an educated 
 electrician. In the latter part of the year 1832, while on 
 a homeward voyage from Europe, he conceived the idea 
 of an electric or electro-chemical telegraph, and devised a 
 system of signs for letters to be marked by the breaking 
 and closing of the electric circuit. Dr. C. T. Jackson of 
 Boston was a passenger on the same vessel ; and, being 
 well versed in electricity, Morse went to him for informa- 
 tion. It appears, however, that neither Morse nor Jack- 
 son at that time had conceived of any thing more than an 
 electro-chemical telegraph, in which the current might de- 
 compose chemical compounds so as to leave a permanent 
 mark. Morse's idea, from the beginning, seems to have 
 been principally to make the current record itself. In 
 1835 Morse was appointed to a professorship in the Uni- 
 versity of New York, and then he contrived the mechani- 
 cal arrangement which formed the basis for his subsequent 
 inventions. This consisted, at the receiving-station, of a 
 strip of paper about half an inch in breadth, moved length- 
 wise over a roller by clock-work. Above the paper hung 
 a pendulum which vibrated across the paper, and carried 
 at its lower end a pencil. Normally, as the paper moved 
 along, the pencil traced a simple straight line. Near the 
 pendulum was an electro-magnet, the armature of which 
 was attached to the pendulum. The electro-magnet was 
 connected to the line wire. Whenever a current came 
 
218 THE AGE OF ELECTRICITY. 
 
 over the wire, the magnet was energized, and caused to 
 attract its armature, and so cause the pencil to move 
 across the paper, so that zigzag lines were produced, 
 which represented letters, numbers, etc. 
 
 Morse encountered the same trouble which all previous 
 experimenters before him, Henry alone excepted, had met. 
 His current was dissipated before it reached the end of 
 the line. He then adopted the relay plan in the spring of 
 1837. On Nov. 28, 1837, Morse wrote to the Secretary : 
 "We have procured several miles of wire, and I am happy 
 to announce to you that our success has thus far been 
 complete. At the distance of five miles, with a common 
 Cruikshank's battery of eighty-seven plates (4 by 3J inches 
 each plate), the marking was as perfect on the register as 
 in the first instance of half a mile. We have recently 
 added five miles more, making in all ten miles, with the 
 same result ; and we have no doubt of its effecting a 
 similar result at any distance." 
 
 In 1838 Morse took his apparatus to Washington, and 
 exhibited it to Congress ; but that body, despite the rec- 
 ommendations of its committees, took no action. Four 
 years passed by, during which time Morse made appeal 
 after appeal. He was at last successful. 
 
 He says, "My bill had indeed passed the House of 
 Representatives, and it was on the calendar of the Senate ; 
 but the evening of the last day had commenced with more 
 than one hundred bills to be considered and passed upon 
 before mine could be reached. Wearied out with the anx- 
 iety of suspense, I consulted one of my senatorial friends. 
 He thought the chance of reaching it to be so small, that 
 he advised me to consider it as lost, lu a state of mind 
 which I must leave you to imagine, I returned to my lodg- 
 ings to make preparations for returning home the next 
 day. My funds were reduced to a fraction of a dollar. 
 
THE ELECTRIC TELEGRAPH. 219 
 
 In the morning, as I was about to sit clown to breakfast, 
 the servant announced that a young lady desired to see 
 me in the parlor. It was the daughter of my excellent 
 friend and college classmate, the Commissioner of Patents 
 (Henry L. Ellsworth). She had called, she said, by her 
 father's permission, and in the exuberance of her own 
 joy, to announce to me the passage of my telegraph-bill 
 at midnight, but a moment before the Senate's adjourn- 
 ment. This was the turning-point of the telegraph inven- 
 tion in America. As an appropriate acknowledgment for 
 the young lady's sympathy and kindness, a sympathy 
 which only a woman can feel and express, I promised 
 that the first despatch by the first line of telegraph from 
 Washington to Baltimore should be indited by her : to 
 which she replied, 'Remember, now, I shall hold you 
 to your word.' In about a year from that time, the line 
 was completed ; and, every thing being prepared, I ap- 
 prised my young friend of the fact. A note from her 
 enclosed this despatch : ' What hath God wrought.' These 
 were the first words that passed on the first completed 
 line of electric wires in America." 
 
 Congress appropriated thirty thousand dollars for the 
 construction of Morse's experimental line between Wash- 
 ington and Baltimore, a distance of forty miles. It was 
 put in operation in the spring of 1844, and was shown 
 without charge until April 1, 1845. Congress, during the 
 session of 1844-45, made an appropriation of eight thou- 
 sand dollars to keep it in operation during the year ; 
 placing it, at the same time, under the supervision of the 
 Postmaster-General. He fixed the first tariff of charges 
 at one cent for every four characters made by or through 
 the telegraph. 
 
 The object of imposing a tariff was to test the profita- 
 bleness of the enterprise. The result of the experiment 
 
220 THE AGE OF ELECTRICITY. 
 
 for the four days after April 1 w/is amusing. It was then 
 very shortly after Folk's inauguration ; and Washington 
 was crowded with office-seekers, of whom large numbers 
 came to stare at the telegraph as one of the sights of the 
 capital. On the morning of April 1, a gentleman walked 
 into the office, and directed that the operation of the con- 
 trivance be exhibited to him. The operator said he would 
 be pleased to do so, at the regular charge of one cent per 
 four characters, and it would therefore cost very little for 
 the visitor to send his name to Baltimore, and have it 
 telegraphed back, or make some other simple test. The 
 applicant said that he did not propose to pay any thing ; 
 did not wish to send any message, but merely wanted to 
 see the thing work. The operator remained firm. Then 
 the gentleman got angry. He informed the operator that 
 this was a new administration, and he had unlimited 
 influence, and if the operator did not at once exhibit 
 the machine, he would have him removed. The operator 
 simply referred his visitor to the Postmaster-General, and 
 the interview terminated. 
 
 This was as near as the new telegraph-office got to col- 
 lecting any revenue for the first three days. On April 4 
 the same party returned, and renewed his demand, and 
 finally said he had no money but a twenty-dollar bill and 
 one cent. He was told that he could have a cent's worth 
 of telegraphing, if that would answer, to which he agreed. 
 Thereupon Washington sent Baltimore one signal which by 
 a pre-arranged code meant, " What time is it? " and Bal- 
 timore sent back a single signal meaning "One o'clock." 
 The charge for the two characters was half a cent ; but 
 the office-seeker laid down the whole cent, and departed 
 satisfied. 
 
 This was the entire income of the Washington office for 
 the first four days of April, 1845. On the oth, twelve and 
 
THE ELECTRIC TELEGRAPH. 221 
 
 a half cents were received. The 6th was Sunday. On 
 the 7th, the receipts ran up to sixty cents ; on the 8th, 
 to $1.32 ; on the 9th, to $1.04. It is worthy of remark, 
 that more business was done by the merchants over the 
 line after the tariff was laid, than when the service was 
 gratuitous. 
 
 When Morse began his petitions to Congress, several 
 of Henry's friends, knowing what he had accomplished, 
 urged that he present, not his claims, for that idea he 
 would not entertain, but evidence of the fact that the 
 principles of the electro-magnetic telegraph belonged to 
 the science of the world. Shortly after this, Henry made 
 the acquaintance of Morse, whom he describes as an "un- 
 assuming and prepossessing gentleman, with very little 
 knowledge of the general principles of electricity, magnet- 
 ism, or electro-magnetism." Morse made no claims LO 
 any thing but "his particular machine and process for ap- 
 plying known principles to telegraphic purposes ; " and 
 so, adds Henry, " instead of interfering with his applica- 
 tion to Congress, I gave him a certificate in the form of 
 a letter, stating my confidence in the practicability of the 
 electro-magnetic telegraph, and my belief that the form 
 proposed by himself was the best that had been pub- 
 lished." 
 
 Morse obtained his first patent in June, 1840. Others 
 were subsequently secured. Infringements of all sorts 
 followed, and protracted suits, which resulted, however, 
 in Morse's favor. As a consequence, Morse is popularly 
 regarded as the inventor of the electro-magnetic telegraph. 
 He has no right to the title, nor did he himself establish 
 claim thereto. The true inventor was Joseph Henry. 
 Neither is Morse entitled to the credit of having devised 
 the mechanism of the telegraphic instrument attributed 
 to him ; nor of the dot-and-dash alphabet that bears his 
 
222 THE AGE OF ELECTRICITY. 
 
 name. That was the work of Alfred Vail, who was em- 
 ployed by Morse to improve and develop the invention. 
 Vail produced the first so-called Morse instrument in the 
 fall of 1837, entirely of his own design, and without sug- 
 gestion from Morse, and arranged it to emboss alphabetic 
 characters devised by himself. Morse, in such late rec- 
 ognition as he made of what Vail had done, might well 
 have heeded the lesson in magnanimity given by Henry 
 to him. 
 
 The student who undertakes to glean the history of the 
 telegraph from English books will note with surprise very 
 little mention of Henry. In fact, most English writers 
 claim that the true inventors of the electro-magnetic tele- 
 graph were Professors Cooke and Wheatstone of England. 
 This leads us to a brief review of what was going on in 
 Europe during the period between Henry's first dis- 
 cover} 7 , and the successful operation of Morse's line in 
 this country. 
 
 In 1820 Ampere merely suggested the idea that a series 
 of needles could be deflected by currents coming over as 
 many wires ; eight years later, Trebouillet proposed a 
 single wire and an electroscope ; and finally in 1832-33 
 Schilling, a Russian counsellor of state, went back to the 
 multiple- wire idea. In 1833-35 two German scientists 
 devised a needle telegraph in which a galvanometer-needle 
 was made to move by currents generated by a coil moved 
 to and fro on a magnet ; the transmitter being, in fact, a 
 small magneto-electric machine. 
 
 Meanwhile, in England, Barlow's conclusion that the 
 electro-magnet could not be worked over long distances 
 of wire became regarded as a fixed fact. Cooke in 1837, 
 at the suggestion of Faraday, applied to Professor Wheat- 
 stone for some way of overcoming his " inability to make 
 the electro-magnet act at long distances." Wheatstone 
 
THE ELECTRIC TELEGRAPH. 223 
 
 says that he at once told Mr. Cooke that this difficulty 
 was insurmountable, and exhibited to him at Kings Col- 
 lege experiments which supported the conclusion. This 
 was not only after Henry's inventions were completed, 
 but even after Morse had made his applications of them. 
 But then, what could so distinguished a scientist as 
 Wheatstone know of the work of a mere professor in an 
 American college, still less of the ideas of an American 
 portrait-painter? Besides, how could he be expected to 
 know more about what American inventors and discoverers 
 had done, than the Franklin Institute, which held its meet- 
 ings not fifty miles from Henry's line, and which, neverthe- 
 less, solemnly advised the Government of the United States 
 to experiment upon semaphores, and to pay $100,000 first 
 cost, and $62,500 annual charges, for a series of them 
 between New York and Washington ? 
 
 After they had concluded that the thing could not be 
 done, Wheatstone and Cooke, in 1837, applied for an 
 English patent for it, in which, among other devices, 
 they describe five wires and five needles, two of which 
 indicated the letters of the alphabet placed around, 
 and also a method of deflecting telegraphic magnetic 
 needles by electro-magnets ; these last being in horseshoe 
 form, placed opposite one another, with the needle between 
 their poles. The description of Wheatstone's first experi- 
 ments, published in "Chambers' Journal" in 1870, is 
 worth quoting: "In July, 1837, wires were laid down 
 from Eustou Square to Camden Town Stations, by the 
 sanction of the North-western Railway ; and Professor 
 Wheatstone sent the first message to Mr. Cooke between 
 the two stations. The professor says, ; Never did I feel 
 such tumultuous sensation before, as when, all alone in 
 the still room, I heard the nee'dles click ; and as I spelled 
 the words, I felt all the magnitude of the invention now 
 
224 THE AGE OF ELECTRICITY. 
 
 proved to be practical beyond cavil or dispute.' The 
 form of telegraph now in use was substituted because of 
 the economy of its construction, not more than two wires 
 (sometimes only one) being required. Of course several 
 persons claimed to have invented the telegraph before 
 Professor Wheatstone. In the same month that the pro- 
 fessor was working upon the North-western Railway, there 
 was one in operation invented by Steinheil of Munich ; 
 but Wheatstone' s patent had been taken out in the month 
 before. An American named Morse claims to have in- 
 vented it in 1832, but did not put it in operation till 1837. 
 After this his system was generally adopted in the United 
 States. It is a recording one." 
 
 It is a curious fact that the patent granted to Wheat- 
 stone and Cooke in this country, for their telegraph, is 
 earlier in date by just ten days than the first patent ob- 
 tained by Morse. 
 
 It is not possible, within the limits of the present work, 
 to trace farther the history of the telegraph. Even at 
 the early period of which we have been writing, it had 
 resolved itself into two great types, depending upon the 
 kind of signals given, the visual or needle telegraph, 
 the electric adaptation of the old semaphore which required 
 the receiver to watch the oscillations of a needle ; and the 
 recording telegraph, wherein the current was made to 
 write its own message upon a slip of paper. The needle 
 telegraph is not in use in the United States : it is essen- 
 tially an English instrument, and is still largely employed 
 in England upon the railways. Recording instruments of 
 various forms are used in the United States ; but, in the 
 majority of instances throughout the world, telegraph- 
 signals are read by the clicking sound produced by the 
 armature of the receiving magnet. 
 
 The amount of mechanical ingenuity expended in devis- 
 
THE ELECTRIC TELEGRAPH. 225 
 
 ing telegraphic apparatus has been and still is wonderful. 
 To explain even the best-known systems in any detail, 
 would require the dryest of descriptions of complicated 
 mechanism, extended to the limits of a cyclopaedia. We 
 shall therefore endeavor to indicate what the telegraph 
 can do, rather than how its machinery operates ; resorting 
 to explanation of the latter only where it may be indis- 
 pensable to an understanding of the results achieved. 
 
 If we stretch a wire between the points A and B, and 
 attach the ends of the wire to plates buried in the earth, 
 then we have a circuit. If we place a battery in the wire, 
 
 as in Fig. 98, then a current will pass from the battery, 
 to and along the wire, in the direction of the arrow (for 
 example) , and thence to the distant earth plate. From 
 this earth plate the current will apparently return by way 
 of the earth, to the earth plate attached to the battery, 
 and so back to the battery itself. 
 
 But how is it that a current sent, for example, over a 
 thousand or more miles of wire, can find its way back 
 through the earth to its source? About this there is a 
 great deal of confusion. One writer regards the earth as 
 a reservoir in which the positive electricity on the one side, 
 and the negative on the other, are absorbed and lost. 
 Another, considering the earth still as a reservoir, con- 
 
226 THE AGE OF ELECTRICITY. 
 
 chides that it offers no sensible resistance to the passage 
 of a current. A third holds that the electricity is pumped 
 into the earth at one point, and out of it at another ; and 
 so on through a variety of hypotheses, to attempt to 
 reconcile which is simply bewildering. 
 
 According to Faraday's theory, the earth plays the part 
 of a conductor, and becomes polarized by the passage of 
 a current, the same way as any other part of the circuit. 
 Recent experiments of Mr. Willoughby Smith go to sub- 
 stantiate this view. Mr. Smith says that " the current 
 passes through the earth or water, which amounts to 
 the same thing as through an ordinary conductor, in 
 dispersed and curved lines. How far such curves extend, 
 I am not prepared to speak positively ; " but they prob- 
 ably " extend over the whole world, and what are termed 
 the magnetic poles of the same are the immediate cause 
 of the lines assuming the curved form. From whatever 
 source a current emanates, it will diffuse itself over the 
 whole mass of matter interposed, without in any way 
 mixing or blending with a current or currents emanating 
 from any other source or sources. The nearest analogy 
 to this which I can think of is that the mind of each 
 human being in this world of ours is constantly directing 
 what are called lines of thought from its brain, or battery, 
 far and wide, and those numberless lines of thought, so 
 far as our own knowledge extends, never blend or become 
 confused, but go and return each one to the source from 
 which it emanates in precisely the same way as lines of 
 electro-motive force when similarly manipulated. . . . 
 Messages by electric signals have been sent and correctly 
 received through a submarine cable two thousand miles in 
 length, the earth being one-half of the circuit, by the aid 
 of electricity generated by means of an ordinary gun-cap 
 containing one drop of water ; and, small though the 
 
THE ELECTRIC TELEGRAPH. 227 
 
 current emanating from such a source naturally was, yet 
 I believe it not only polarized the molecules of the copper 
 conductor, but also in the same manner affected the whole 
 earth through which it dispersed on its way from the out- 
 side of the gun-cap to its return to the water it contained." 
 The battery in Fig. 98, the wire, and the earth are in 
 closed circuit ; that is, there exists a path through which 
 the current can continuously flow until the battery is 
 exhausted. If, however, we should break the wire, and 
 leave the ends separated, then we should have an open 
 circuit over which no current passes or can. pass until we 
 unite the separated ends once more. If we attach a lever, 
 or, as it is called, a key, movable by the hand, to 
 
 Wii-e 
 
 Fig. 99. 
 
 one part of the separated wire, as in Fig. 99, and ar- 
 range the key so that at will we can cause it to make 
 contact with the other part of the wire, then, if we leave 
 the key open, we have an open circuit ; if we bring the 
 key into contact with the opposite part of the wire, so that 
 it bridges the interval between the two separated parts, 
 then the effect is the same as if the wire were continuous, 
 and we have a closed circuit. 
 
 We can therefore start with either an open circuit or a 
 closed circuit. If we choose an open circuit, every time 
 we move the key into contact with the opposite part of the 
 wire, we let the current pass : if we prefer a closed circuit 
 through which the current constantly travels, we can inter- 
 rupt the current as often as we desire, simply by moving 
 
228 THE AGE OF ELECTRICITY. 
 
 the key out of contact. And by making the periods of 
 contact or the periods of interruption short or long, or 
 more or less frequent, we can allow currents varying in 
 duration and frequency to pass over the line. 
 
 At the opposite extremity of the line to that at which 
 our key is placed, something is necessary to reveal the 
 currents which come over ; and for this purpose, as we 
 have already explained, the electro-magnet is employed. 
 
 In Fig. 100, there is shown a closed circuit. Whenever 
 we press down the key, the current which excites the 
 magnet at the far end of the line is interrupted ; and 
 the magnet, which has attracted its armature to its pole, re- 
 leases it. The armature is thus moved from one position 
 
 Fig. 100. 
 
 to another, and so held as long as the current remains 
 broken, which is until we move the key into contact and 
 back to its original position. Then the magnet attracts 
 its armature back to its original place. 
 
 The consequence is, therefore, that the armature at the 
 distant end of the line copies, so to speak, the movement 
 of the key at the sending end. If the key is held down, 
 and the circuit opened, for a certain period, the armature 
 remains released and retracted for that period : if the key 
 be held down only for an instant, the armature is instantly 
 retracted and attracted. Consequently, in order to send 
 signals, we have simply to manipulate the key very much 
 as a key of a piano is touched when it is desired to pro- 
 duce a note of greater or less duration. 
 
THE ELECTRIC TELEGRAPH. 229 
 
 It will be remembered, that, in describing Morse's 
 original apparatus, we stated that a pencil-point rested 
 upon a slip of moving paper, and by the attraction of a 
 magnet made sidewise zigzag marks thereon. Leaving 
 out the idea of sidewise motion, suppose we move the 
 point at intervals away from the paper, which keeps on 
 travelling. Then we shall make broken lines, long or 
 short, depending upon the length of the intervals of time 
 during which we keep the pencil away from the paper. 
 For example : suppose above a magnet, as shown in Fig. 
 101, we arrange an armature fastened to one end of a 
 pivoted lever which carries a pencil at its opposite end. 
 
 Fig. 707. 
 
 This pencil bears against the under side of a strip of 
 paper, which is moved under a roller, by clock-work or 
 any other suitable means. So long as the current comes 
 over the line, the magnet will attract its armature, and 
 keep the pencil-point pressed against the paper, on which 
 a continuous line will be made. But if the current is 
 broken, which is done by manipulating the key at the 
 sending end of the line, as already explained, then the 
 magnet will no longer attract its armature, and the pencil- 
 point end of the lever will drop down, or be drawn down 
 by a spring, so that the pencil will no longer mark. Now, 
 we have only to agree upon an alphabet made up of short 
 lines and long ones, arranged in a different way for each 
 letter, to make the apparatus spell out words. 
 
230 
 
 THE AGE OF ELECTRICITY. 
 
 The shortest signal that can be made is, of course, a 
 dot ; and this at the sending end involves opening the cir- 
 cuit and closing it very quickly by a sudden movement of 
 the key. The dot is usually taken as the standard ; and 
 with dots are combined dashes, which may be regarded as 
 lines produced while the current is passing three times 
 as long as is necessary to make a dot. The letter A may 
 therefore be represented by a dot and a dash ; J, by a 
 single dot ; F, by dot, dash, dot ; and so on, through 
 various combinations in which the spaces or intervals be- 
 tween the dots and dashes also are used to cause varia- 
 tions to produce a different symbol for each letter : so that 
 
 any one knowing these 
 
 -drrtialttre Jetxtr 
 
 Fig. 102. 
 
 symbols can read the 
 message from the marked 
 paper as easily as from a 
 printed page. 
 
 This is Morse's record- 
 ing system, which he used 
 on his first line, and for 
 
 which Vail invented the alphabet of dots and dashes still 
 employed all over the country. 
 
 Nowadays, however, telegraph-operators receive mes- 
 sages by sound ; and the recording part of Morse's con- 
 trivance is little used. To this end the receiving magnet 
 is arranged about as indicated in Fig. 102. Here the op- 
 posite end of the armature moves between fixed stops, and 
 strikes them alternately, producing a sharp click. It is a 
 great puzzle to many people, to understand how it is that 
 a telegraph-operator sitting beside one of these little in- 
 struments, which appears to be rattling away with great 
 rapidity, manages to comprehend what it says, apparently 
 as well as if the instrument actually spoke to him. Of 
 course long practice has as much to do with this skill, as 
 
THE ELECTRIC TELEGRAPH. 231 
 
 it has in enabling any one to comprehend readily a foreign 
 language. The lever, however, in striking its stops, pro- 
 duces two distinct sounds, according as it meets one or the 
 other stop. When a dot is made, the lever strikes one 
 stop, and instantly afterward the other : when a dash is 
 signalled, there is a longer delay between the sounds. 
 The two sounds are in themselves just alike ; but the dot 
 and dash, to a practised ear, are easily distinguishable, 
 because there is a longer wait, or delay, between the clicks 
 which begin and end a dash, than those which begin and 
 end a dot. We say, to a practised ear, because to the 
 ordinary organ there is no apparent difference. The 
 average hearer can of course perceive that there is an 
 irregularity about the clicks, and that they do not come 
 at regular intervals like the beats of a clock-pendulum ; 
 but all the instruction ever given by written description 
 never made a skilful telegraphic sound-reader, and proba- 
 bly never will. To learn to manipulate a key so as to send 
 dots and dashes with fair speed, is not difficult ; but to 
 translate a bewildering succession of clicks, spelling out 
 words at the rate of perhaps thirty a minute, simultane- 
 ously to write down the received message, and to do this 
 with perhaps other instruments in the room clicking away 
 at the same time, and perhaps unlimited conversation 
 going on, and all this with the knowledge that a blunder 
 may involve the company in an expensive lawsuit, is not 
 an accomplishment easily acquired. Yet a skilful opera- 
 tor can send and receive forty-five words per minute. 
 
 When a telegraph-line is of considerable length, or for 
 any other reason offers much resistance to the passage of 
 the current, Henry's invention of the relay is employed ; 
 which is placed in the main line, and merely performs the 
 duty of opening and closing the circuit of a local battery 
 at the receiving station, which in turn operates the sounder 
 
232 
 
 THE AGE OF ELECTRICITY. 
 
 Fig. 103. 
 
 already described. The diagram (Fig. 103) will render 
 the relay arrangement easily understood. The current 
 coming over the line excites the magnet marked "relay," 
 which attracts its armature, and thus moves the latter into 
 
 contact with a stop. The 
 circuit of the local battery is 
 thus established through the 
 magnet of the sounder. 
 
 The closed-circuit system 
 which is in almost universal 
 use throughout the United 
 States is shown in its sim- 
 plest form in Fig. 104. At 
 each key there is a circuit-closing lever whereby the line 
 is kept closed, so that a current constantly traverses the 
 line. This current goes from the main battery at New 
 York, for example, through the circuit-closing lever, to 
 the relay magnet 
 which attracts its 
 armature. In Fig. 
 104 the sounders 
 and local batteries 
 are not shown. 
 But when this 
 armature is at- 
 tracted, it makes 
 contact with a 
 stop, and thus 
 completes the circuit from the local battery through the 
 sounder at New York. Hence, at the New- York end, 
 both armatures stand normally attracted. After passing 
 through the New-York relay, the current goes over the 
 ninety miles or so of line to the Philadelphia relay, which 
 attracts its armature, and establishes a local circuit through 
 
 Fig. 104. 
 
THE ELECTRIC TELEGRAPH. 233 
 
 the sounder in Philadelphia. This is the normal condition 
 of affairs. 
 
 Suppose now New York wants to send a despatch to 
 Philadelphia. The first thing that the New- York operator 
 does is to open his circuit-closing lever, when all of the 
 armatures both at his and at the Philadelphia end will 
 be released. Then he manipulates his key, making and 
 breaking the current to form the desired signals ; and as 
 he does so, all of the armatures at both ends of the line 
 will respond, so that the Philadelphia receiver has merely 
 to listen to the clicks of his sounder to receive the mes- 
 sage. Meanwhile the New- York sender's instruments keep 
 clicking too, which indicates to him that the message is 
 reaching Philadelphia. If, however, his instruments should 
 stop, he would know that the Philadelphia man had opened 
 the circuit. Then he would close his own lever, and wait 
 for a message from Philadelphia explaining the reason of 
 the break, such, for instance, as " message not under- 
 stood," or something of that sort. The instruments at 
 the Philadelphia end being the same as those at the New- 
 York end, a message from Philadelphia to New York 
 would of course be transmitted in the same way. It will 
 be seen, however, that there is but one main-line battery, 
 which is at the New- York end. In practice this battery is 
 usually divided, half of it being placed at each terminal 
 station. As many as forty intermediate stations are some- 
 times operated in this manner. 
 
 So far we have described simply a main line, the cur- 
 rent of which establishes a new circuit at the receiving 
 end, so that the work of recording the message, or of 
 operating the sounder, is thrown upon a battery at that 
 end. But suppose we have to telegraph over very long- 
 distances say from Augusta, Me., to San Francisco, 
 Cal. A single main-line battery might be wholly unable 
 
234 THE AGE OF ELECTRICITY. 
 
 to send its current through so much resistance ; and if we 
 divided the line into short sections, it would be necessary 
 for the operator at each station to receive and understand 
 the message, and then repeat it to the next station. In 
 the early days of telegraphing, this was in fact done ; but 
 now it is automatically accomplished by a simple exten- 
 sion of the relay principle known as "repeating." In- 
 stead of there being simply a short local circuit in the 
 receiving station, which is controlled by the arriving cur- 
 rent, the latter governs a circuit which extends, perhaps, 
 a long distance to another station. The current which 
 comes to station No. 2 closes contact in a circuit which 
 extends still farther to station No. 3, and so on from 
 station to station, until the sounder at the far-distant end 
 of the series of lines is operated ; just as if one could fire 
 a gun, and with the bullet strike the trigger of a distant 
 gun, the missile from which would fire a third gun, and so 
 on. So that, in practice, suppose a message to be sent from 
 Augusta, at which place the battery is located. When the 
 key is closed, a current goes over the line, and energizes 
 a magnet at New York, for example. This magnet then 
 closes the circuit, say, between New York and Chicago, 
 and in this circuit there is a new battery located at New 
 York. The current from New York closes at Chicago 
 the circuit between that city and San Francisco, and finally 
 San Francisco receives the message on its sounder in the 
 usual way. Repeaters are also often used for connecting 
 one or more branch lines with a main line, for the purpose 
 of transmitting press news, etc., simultaneously to differ- 
 ent places. This enables all the stations in connection 
 to communicate with each other as readily as if they were 
 situated upon the same circuit. 
 
 The use of repeaters has aided many very wonderful 
 feats of rapid long-distance telegraphing. The news of 
 
THE ELECTRIC TELEGRAPH. 235 
 
 the Hanlan-Trickett rowing match in England, in 1881, 
 travelled to Sydney, Australia, a distance of twelve thou- 
 sand miles, in one hour and twenty minutes. The distance 
 from Singapore to Sydney, 5,070 miles, was traversed in 
 thirty-five seconds. There were fourteen repetitions of 
 the message en route. But perhaps the most extraordi- 
 nary direct long-distance telegraphing is that now possible 
 between London and Calcutta, seven thousand miles, 
 of which a writer in the London ' ' Telegraphist ' ' gives 
 the following graphic account : 
 
 " In the basement of an unpretentious building in Old 
 Broad Street, we were shown the Morse printer in connec- 
 tion with the main line from London to Teheran. We 
 were informed that we were through to Emden ; and with 
 the same ease with which one ' wires ' from the city to the 
 West End, we asked a few questions of the telegraphist in 
 the German town. When we had finished with Emden, we 
 spoke with the same facility to the gentleman on duty at 
 Odessa. This did not satisfy us, and in a few seconds we 
 were through to the Persian capital (Teheran) . There were 
 no messages about, the time was favorable, and the em- 
 ployees of the various countries seemed anxious to give us 
 an opportunity of testing the capacity of this wonderful line. 
 
 "T H N (Teheran) said, 'Call Kurrachee ; ' and in 
 less time than it takes to write these words, we gained the 
 attention of the Indian town. The signals were good, 
 and our speed must have equalled fifteen words a minute. 
 The operator at Kurrachee, when he learnt that London 
 was speaking to him, thought it would be a good opportu- 
 nity to put us through to Agra ; and to our astonishment 
 the signals did not fail, and we chatted pleasantly for a 
 few minutes with Mr. Malcom Khan, the clerk on duty. 
 To make this triumph of telegraphy complete, Agra 
 switched us on to another line, and we soon were talking 
 
236 THE AGE OF ELECTRICITY. 
 
 to a native telegraphist at the Indian Government cable 
 station, Calcutta. At first the gentleman ' at the other 
 end of the wire ' could not believe that he was really in 
 direct communication with the English capital, and he 
 exclaimed in Morse language, ' Are you really London ? ' 
 Truly this was a great achievement. Metallic communi- 
 cation without a break from London, to the telegraph- 
 office in Calcutta ! Seven thousand miles of wire ! The 
 signals were excellent, and the speed attained was not less 
 than twelve, perhaps fourteen, words per minute." 
 
 One of the most paradoxical of all the applications 
 of electricity is that which appears to solve that rather 
 insoluble problem of how to make two locomotives pass 
 each other while moving in opposite directions on a 
 single track. This is the so-called duplex system of teleg- 
 raphy, whereby two messages are transmitted over one 
 wire simultaneously and in opposite directions. 
 
 To explain the duplex without resort to technicalities, 
 is exceedingly difficult, chiefly because it is scarcely pos- 
 sible to suggest an analogy which meets all conditions. 
 It should be remembered, that, in dealing with electricity, 
 our ideas of lapse of time are very apt to lead us alto- 
 gether astray ; and we frequently consider occurrences as 
 simultaneous, because they seem so to be to our senses, 
 when in fact they are necessarily successive. So, in the 
 case of the duplex, for all practical purposes two mes- 
 sages do travel in opposite directions on one and the same 
 wire ; but probably the signals in one direction alternate in 
 inconceivably small periods of time with those coming 
 from the opposite direction. To obtain any clear idea 
 of the duplex, therefore, it is necessary to forget the 
 apparent paradox, and simply to regard the apparatus as 
 affording means whereby each of two widely separated 
 operators may control an instrument at the end of the line 
 
THE ELECTRIC TELEGRAPH. 237 
 
 distant from him. On such a line, at each end there is, 
 of course, a sending key and a receiving instrument. 
 But ordinarily, when two receivers are thus connected, a 
 current sent upon the line affects both of them. Hence 
 if A at one station, while telegraphing to B at the other, 
 keeps his receiver clicking under his own signals, B at the 
 other end, in sending to A, cannot exercise the necessary 
 control over A's receiver ; and in the same way, if B's 
 receiver is constantly disturbed by B, it cannot correctly 
 be governed by the signals sent by A. Therefore the 
 main principle of the duplex is to arrange matters so that 
 A's signals will affect, not A's receiver, but B's receiver ; 
 and conversely, so that A's receiver will respond only to 
 B's signals, and B's receiver to A's signals. 
 
 There are several ways of doing this ; but for these, the 
 reader is referred to the technical treatises. 
 
 The diplex is a system by which two messages can be 
 sent at once in the same direction ; and is called " diplex " 
 in contradistinction to the "duplex," where two messages 
 are sent simultaneously in opposite directions. In the 
 diplex, the two keys are of course at the sending station, 
 and the two relays are at the receiving station. Ke}' num- 
 ber one sends a weak current, while key number two sends 
 a stronger current. The two relays are so arranged that 
 one will respond to the strong current, and the other to 
 the weak ; when both currents are sent at once, both re- 
 lays respond. It is this system, using both poles of the 
 battery in connection with the so-called bridge duplex, 
 which forms the so-called quadruples of Edison. A de- 
 scription of the quadruplex would, however, be altogether 
 too technical for these pages. 
 
 Multiple telegraphic systems have for their object the 
 transmission of a large number of messages simultaneously 
 over the same wire. The harmonic system is one of the 
 
238 THE AGE OF ELECTRICITY. 
 
 most ingenious of these, although it has never come into 
 extended practical use. It depends upon thep rinciple of 
 acoustics, that two tuning-forks or tuned reeds will vibrate in 
 unison, and be set in vibration one by the other ; whereas, 
 of two forks not in unison, the reverse is true. Suppose, 
 for example, half a dozen tuning-forks A, B, (7, />, E, F, 
 be arranged conveniently together, and suppose three per- 
 sons should strike three other tuning-forks respectively in 
 unison with A, B, and C of the series. Then the air-waves 
 produced by the three forks set in vibration would affect 
 only A, B, C ; and these three forks would respond, the 
 others remaining silent. Now suppose the three persons 
 mentioned should strike their forks simultaneously, and in 
 a particular way ; as, for instance, say that each person 
 should make the signals of a different telegraphic mes- 
 sage in the Morse alphabet by taps on his fork. Clearly, 
 the result of all these taps sounding together would be a 
 confused jumble to the ear, but when the combined sounds 
 reached the three tuning-forks A, B, and C, they would 
 be disentangled. The tuning-fork A would be entirely 
 indifferent, audibly, to the vibrations affecting B and (7, 
 and would not reproduce them, but would pick out and 
 respond only to those emanating from a fork in unison 
 with it. So also of forks B and (7; and, consequently, 
 three messages made simultaneously might thus be trans- 
 mitted through the air, and analyzed at the receiving 
 forks. In multiple harmonic telegraphy, these vibrations 
 are transmitted by the electric current, through a wire, 
 instead of by waves of condensation and rarefaction in 
 the air. If two tuned reeds be sounded together, then 
 the electrical impulses from each, moving at different 
 rates at the same moment, will traverse the wire simulta- 
 neously, and these will be disentangled by each of twc 
 receiving reeds vibrating responsively under the impulse 
 
THE ELECTRIC TELEGRAPH. 239 
 
 of the transmitting reed in unison with it. In this manner 
 two messages are sent simultaneously over a single wire, 
 and received by sound separately from different reeds. 
 And the same principle governs the sending of more mes- 
 sages by the aid of a greater number of reeds, and under- 
 lies the construction of the harmonic telegraphs of Gray 
 and others. 
 
 One of the most recent inventions in multiple teleg- 
 raphy is that of Mr. Delany. A great many varieties of 
 telegraph-apparatus depend upon synchronism between the 
 movements of certain devices in the transmitting apparatus, 
 and certain other devices in the receiving apparatus. Two 
 tuning-forks are said to be synchronous when they make 
 the same number of vibrations in the same time, and have 
 motions exactly similar. Mr. Delany has succeeded in 
 keeping two bodies, separated by hundreds of miles, 
 in synchronous rotation for periods of upward of seventy 
 hours, without variation during that time of the one-thou- 
 sandth part of a second. This is equivalent to two 
 entirely independent bodies, separated from each other by 
 hundreds of miles, starting together and passing through 
 a distance of nearly one hundred miles without varying 
 the one-hundredth part of an inch in that entire distance, 
 or the one-thousandth part of a second during that entire 
 time. The practical consequence is that circuits ranging 
 in number from six to seventy-two, according to their 
 capacity, have been obtained over a single wire, admitting 
 of the possibility of the transmission of from six to 
 seventy-two separate messages at practically the same 
 time, either all in one direction or any portion of the 
 whole number in opposite directions. Another extraor- 
 dinary performance of Mr. Delany's apparatus was the 
 automatic transmission of a single dot back and forth 
 over the same wire between Boston and Providence, at 
 
240 THE AGE OF ELECTRICITY. 
 
 practically the same instant of time, travelling over dif- 
 ferent circuits in rotation backward and forward for five 
 minutes, during which time it travelled four hundred and 
 fifty thousand miles. Mr. Delany's system is based on 
 two main principles : first, that of synchronism, or the 
 simultaneous motion of similar pieces of apparatus at 
 two different places ; and, second, that of distributing to 
 several telegraphists the use of a wire for very short equal 
 intervals of time, so that, practically, each operator has 
 the line to himself during these periods. 
 
 Farther on, we shall see the great importance of syn- 
 chronism in fac-simile telegraphy. But, in connection 
 with the transmission of messages in the usual way, Mr. 
 Delany's apparatus greatly increases the capacity of every 
 wire, and probably at the present time allows of more 
 messages being simultaneously transmitted over a given 
 conductor, at the same time, than any other telegraphic 
 system. 
 
 It is of course needless here to go into the minute 
 details and very complex mechanism employed in multiple 
 telegraphy : nor, in fact, shall we attempt, in the many 
 forms of intricate devices which must find mention here, 
 to do more than generally outline what they will accom- 
 plish. As we have seen, duplex, quadruplex, and other 
 multiple telegraphic systems increase the capacity of wires, 
 and expedite business through rendering it possible to 
 send many messages at one time. There are many sys- 
 tems, however, which provide for very rapid transmission. 
 
 It will easily be understood, that, where telegraphic 
 transmission depends upon the manipulation of a key by 
 the human hand, a limit of speed is very soon reached. 
 And not only this, but the human machine tires and makes 
 errors ; the signals lose legibility and clearness ; and, in 
 short, the various accidents and failures incident to all 
 
THE ELECTRIC TELEGRAPH. 241 
 
 handiwork become manifest in greater or less degree. 
 When, however, manipulation by the operator is replaced 
 by the action of a machine, then not only great speed but 
 precision within certain limits is obtained : and hence auto- 
 matic instruments, both for the sending and receiving of 
 telegraphic messages, have been invented and are in use. 
 
 Automatic telegraphy is largely employed in England, 
 where it was first proposed in 1846 by Alexander Bain. 
 He punched broad dots and dashes in paper ribbon, which 
 was drawn with uniform velocity over a metal roller and 
 beneath brushes of wire, which thus replaced the key ; for, 
 whenever a hole occurred, a current was sent by the 
 brushes coming in contact with the roller. The same idea 
 is now applied to the musical instrument known as the 
 mechanical orguinette, in which a strip of paper having 
 apertures of various sizes is moved in front of the melo- 
 deon reeds so as to control the air supply to them, and 
 hence the notes produced. Bain used as a recording in- 
 strument his chemical marker, wherein the current was re- 
 ceived through a strip of paper moistened with a chemical 
 solution which became decomposed on the passage of the 
 current, so that the contact point in touching the paper 
 caused dots and dashes of a bright blue color to appear. 
 
 The apparatus used throughout Great Britain is that 
 invented by Professor Wheatstone. Its construction is 
 too complicated for description here ; but, in general 
 terms, it includes a punching-machine for producing the 
 perforated strips of paper, a transmitting apparatus 
 through which these strips are very rapidly passed, and 
 a receiving device which marks on another strip dots and 
 dashes in ink. The punching-machine will make the holes 
 in three or even four strips at a time, and in the hands of 
 an experienced operator will punch at the rate of forty 
 words a minute. The disposition of holes in a strip when 
 
242 THE AGE OF ELECTRICITY. 
 
 thus prepared is shown in Fig. 105 ; the large openings 
 being for the message, and the centre row of small ones 
 serving to receive the teeth of a wheel which in turning 
 moves the strip along at uniform speed. When the paper 
 is thus prepared it is run through the transmitter, which is 
 permitted to operate to send a current whenever certain 
 moving rods can pass through the holes and establish a 
 contact, the currents being alternately positive and nega- 
 tive. If a succession of currents in reverse directions are 
 caused to pass upon the line, the receiver at the opposite 
 end will record a series of dots. To make a dash, one 
 reversal of the current is missed ; and, in brief, the func- 
 
 Fig. 1C5. 
 
 tion of the paper is so to regulate the motion of the trans- 
 mitter as to produce reversal, or missing of reversal, of 
 the current at the proper moments, and thus to cause the 
 current to flow in such a way as to form dots and dashes. 
 The speed is determined by the rate at which the receiver 
 can receive ; because the apparatus contains a controlling 
 electro-magnet which takes time to be magnetized and 
 demagnetized, and hence, if the current reverses too 
 quickly, the marks will run together instead of being 
 separate, and distinct. The maximum useful speed is 
 about a hundred and thirty words per minute on a short 
 line. One strip of punched ribbon will do for any number 
 of circuits, so that from a central telegraph-station a 
 single strip disseminates news to many places. 
 
THE ELECTRIC TELEGRAPH. 243 
 
 With Edison's system of automatic transmission, a 
 much greater speed than this has been obtained. The 
 receiving apparatus here consists simply of a wire tipped 
 with tellurium, which always rests on the moistened paper. 
 The effect of the current is to decompose the water in the 
 paper, and through the effect of the tellurium the contact 
 point makes a dark mark. Mr. Edison in this way claims 
 to have transmitted 3,150 words in a minute, on a line 
 between New York and Washington. 
 
 We have now seen what can be done in the way of quick 
 transmission. Next in importance is legibility at the re- 
 ceiving end ; or, rather, the possibility of receiving mes- 
 sages, not in dots and dashes, but in ordinary characters. 
 For this purpose type-printing and autograph systems are 
 employed. The first printing telegraph actually used was 
 that devised by Royal E. House of Vermont in 1846, 
 now obsolete. It was followed by Hughes's system, in 
 which the principle of synchronism between the sending 
 and receiving instruments entered materially into the suc- 
 cess of its working. Hughes's apparatus is not used in 
 this country. It has two type-wheels kept rotating syn- 
 chronously together at each station by means of a train 
 of gearing provided with a governor. Connected to the 
 mechanism is a transmitting cylinder, arranged with and 
 controlled by a keyboard having a key for each letter of 
 the alphabet. A printing-lever, controlled by an electro- 
 magnet placed in the main line, causes the printing of a 
 letter upon a long fillet of paper while the type-wheel is 
 rapidly moving. This movement is caused by the energiz- 
 ing of the controlling magnet by the transmission of a 
 single wave of electricity from the distant station at the 
 proper time. Simultaneously with the printing of a letter, 
 the type-wheel, by the action of the printing-lever, is 
 thrown slightly forward or backward, thus correcting at 
 
244 THE AGE OF ELECTEICITY. 
 
 every impression any slight variation in the synchronous 
 movement of the wheel. 
 
 The printed despatches on the long slips of paper now 
 delivered by the Western Union Telegraph Company are 
 transmitted by Mr. G. M. Phelps's electro-motor telegraph. 
 In this system, the gearing of the Hughes apparatus is 
 replaced by a simple but powerful electro-motor. As in 
 the Hughes machinery, the transmitting device and type- 
 wheel of the receiving instrument are caused to revolve 
 synchronously under control of a governor, and each sepa- 
 rate letter is printed by a single pulsation of the electric 
 current, of a determinate and uniform length, transmitted 
 at a determinate time ; but, unlike the Hughes apparatus, 
 the motion of the type-wheel is arrested while each letter 
 is being printed, and it is automatically released the in- 
 stant the impression has been effected. By this means a 
 very high speed of transmission has been attained. 
 
 There is one form of printing telegraph which is notable 
 for the danger attending its use. It has probably, inno- 
 cently, been the means of more injury to the human race 
 than the most potent of electrical torpedoes, which it re- 
 sembles occasionally in effect, that is, metaphorically 
 speaking. We allude to the stock exchange "ticker" 
 when combined with a widely fluctuating market. For 
 the benefit of those who have never watched the motions 
 of the intricate little mechanism, let us say, while wait- 
 ing for the next quotation, it may be explained, that 
 there is usually a t} T pe-wheel rotated by a lever from an 
 electro-magnet. The magnet is excited, and the lever 
 worked, by pulsations over the wire. The lever turns the 
 type-wheel step by step. Usually there are two type- 
 wheels ; one printing the cabalistic letters which indicate 
 the name of the stock, and the other the quotation in 
 numbers. When a letter or number is to be printed, the 
 
THE ELECTRIC TELEGRAPH. 245 
 
 proper wheel is brought into position, and then another 
 magnet operates to bring the "tape" into contact with 
 the type. 
 
 Despatches may be sent automatically, and received in 
 printed characters, by several systems, of which Bonnelli's 
 is an example. The message is set up in ordinary type, 
 which are connected to the battery and earth. Over the 
 face of the type passes a comb of fine points of wire, 
 each point being connected to a separate line proceeding 
 to the distant station, and the line wires there being con- 
 nected to another and similar comb, which is moved over 
 chemically prepared paper. When the comb at the send- 
 ing end is rubbed over the raised parts of the characters, 
 the comb at the receiving end receives a current which 
 decomposes the chemicals in the paper, producing a mark 
 similar to the character traversed. Little use has been 
 made of systems of this character. 
 
 The autographic telegraph is one of the most ingenious 
 of the various known systems. It is not used in this 
 country, although recently the improvements in effecting 
 synchronism have directed anew the attention of inventors 
 to its possibilities. It transmits the handwriting of the 
 sender, and also simple drawings. Its advantages at pres- 
 ent appear to depend on whatever benefits may be derived 
 from these capabilities ; thus it may be useful to send 
 sketches and illustrations to newspapers, or to verify sig- 
 natures, or to telegraph bank-checks in facsimile : but 
 beyond this, it has not much promise. Its operation de- 
 pends upon synchronism at both ends of the line. Cas- 
 selli's apparatus, which is used in France, consists of two 
 large pendulums kept swinging in unison by electro-mag- 
 nets placed in the line wire. One pendulum transmits 
 electric waves at certain intervals, which, acting upon the 
 magnets, cause them to correct variations from exact 
 
246 THE AGE OF ELECTRICITY. 
 
 unison of swing. The message for transmission is written 
 upon metallic foil, with a non-conducting ink : this is laid 
 upon a platen connected to the earth through a battery. 
 A fine platinum wire connected to the line wire is recipro- 
 cated from one end of the foil to the other ; the foil being 
 advanced one-hundredth of an inch after each reciproca- 
 tion, until the point has passed over the whole of the foil. 
 The platinum point, when passing over the foil, allows 
 the current from the battery to go to the line. At all 
 points, however, where it passes over the non-conducting 
 ink with which the message is written, the current is pre- 
 vented from passing to line. At the distant station a 
 similar point is reciprocated over a platen upon which is 
 laid a sheet of chemically prepared paper: the passage 
 of the circuit through the reciprocated point and moistened 
 paper causes a blue mark to appear. If both pendulums 
 are started at the same instant, the form of the metallic 
 foil upon which the message is written will be reproduced 
 upon the chemical paper by blue lines blending one into 
 the other. But owing to the non-transmission of any cur- 
 rent where the transmitting point passes over the non- 
 conducting ink, no mark will appear ; hence the message 
 would be inscribed in white characters on a blue ground, 
 were it not for an ingenious little device which reverses 
 the action, causing the characters to appear in blue. In 
 Fig. 106 is represented a design as prepared and then trans- 
 mitted in facsimile by Casselli's apparatus. In the more 
 recent forms of writing telegraph, notably Cowper's, a 
 different principle is employed ; the message, in fact, being 
 transmitted by the act of writing it. The idea followed is, 
 that every position of the point of a pen, as it forms a 
 letter, can be determined by its distance from two fixed 
 lines say, the adjacent edges of the paper. Hence if 
 these distances, so to speak, are transmitted by telegraph, 
 
THE ELECTRIC TELEGRAPH. 
 
 247 
 
 and recombined, so as to give a resultant motion to a dupli- 
 cate pen, a duplicate copy of the original writing is pro- 
 duced. Cowper uses two separate circuits, one to transmit 
 the vertical, the other the horizontal, movements of his pen. 
 
 And now we come to the most wonderful of all tele- 
 graphs, - that which transmits messages from continent 
 to continent, for thousands of miles, under the depths of 
 the sea. "Does it not seem all but incredible to you,'* 
 said Edward Everett in his oration at the opening of 
 
 Original. 
 
 Fig. 106. 
 
 Facsimile. 
 
 Dudley Observatory, " that intelligence should travel for 
 two thousand miles along those slender copper wires far 
 down in the all- but fathomless Atlantic, never before pen- 
 etrated by aught pertaining to humanity, save when some 
 foundering vessel has plunged with her hapless company 
 to the eternal silence and darkness of the abyss ? Does 
 it not seem, I say, all but a miracle of art, that the 
 thoughts of living men the thoughts that we think up 
 here on the earth's surface, in the cheerful light of day 
 about the markets and the exchanges, and the seasons, 
 and the elections and the treaties and the wars, and all the 
 fond nothings of daily life, should clothe themselves with 
 
248 THE AGE OF ELECTRICITY. 
 
 elemental sparks, and shoot with fiery speed in a moment, 
 in the twinkling of an eye, from hemisphere to hemi- 
 sphere, far down among the uncouth monsters that 
 wallow in the nether seas, along the wreck-paved floor, 
 through the oozy dungeons of the ray less deep ; that the 
 last intelligence of the crops, whose dancing tassels will 
 in a few months be coquetting with the west wind on these 
 boundless prairies, should go flashing along the slimy 
 decks of old sunken galleons which have been rotting for 
 ages ; that messages of friendship and love, from warm 
 living bosoms, should burn over the cold green bones of 
 men and women whose hearts, once as warm as ours, 
 burst as the eternal gulfs closed and roared over them, 
 centuries ago ! " 
 
 It is not definitely known who originated the idea of 
 submarine telegraph-lines. The notion was often dis- 
 cussed long before it even approached successful realiza- 
 tion. The first working-line was laid down by Professor 
 Morse, between the Battery in New- York City and Gov- 
 ernor's Island. This was in October, 1842. What Morse 
 might have demonstrated with that line, can only be con- 
 jectured. It came to an untimely ending. The very next 
 morning after it had been laid, some conscienceless mari- 
 ners hauled up the wire on their anchor, and, probably 
 realizing its advantages if devoted to splicing their stand- 
 ing rigging, cut off and confiscated as much of it as they 
 conveniently could. In the same year Col. Samuel Colt, 
 of revolver fame, put down a submarine line between Fire 
 Island and Coney Island and New- York City, and, it is 
 said, successfully operated it. In Europe the first sub- 
 marine line was laid by Lieutenant Siemens, between 
 Deutz and Cologne, across the Rhine, a distance of about 
 hslf a mile ; and on this wire gutta-percha was first used 
 as an insulating covering. The first sea-line extended 
 
THE ELECTRIC TELEGRAPH. 249 
 
 between Dover and Calais, a distance of twenty-four miles, 
 and was laid in 1850. 
 
 The earliest suggestion of the possibility of a trans- 
 atlantic cable appears to have been made by Gen. Horatio 
 Hubbell and Mr. J. H. Sherburne of Philadelphia, who 
 united in a memorial which was presented to the United- 
 States Senate by Vice-President Dallas, and to the House 
 of Representatives by Hon. J. R. Ingersoll, on Jan. 29, 
 1849. In this memorial the existence of the plateau or 
 table-land between Newfoundland and Ireland is first 
 announced to the world as the course over which the tele- 
 graph cable might be, and over which it finally was, suc- 
 cessfully laid. The Senate was inclined to ignore the 
 subject, and not even refer it to the limbo of a committee. 
 But one senator, Mr. Jefferson Davis, finally moved its 
 reference to the Committee on Commerce, remarking that 
 "the world was not yet prepared for the project, but 
 might be soon." Congress did not grant the memorialists' 
 request for a vessel to make the necessary soundings ; but 
 five years later Lieutenant Berryman conducted the sur- 
 veys of the ocean bottom upon which Lieutenant Maury 
 made the reports which determined the cable route over 
 the plateau. 
 
 The first attempt to lay a transatlantic cable was made 
 in August, 1857. After about 380 miles had been sub- 
 merged, the engineer thought that there was not sufficient 
 strain on the line, and ordered more applied. It was not 
 properly done, and the cable snapped. In August, 1858, 
 the work was successfully accomplished ; the cable extend- 
 ing from Valentia Bay, Ireland, to Trinity Bay, New- 
 foundland, a distance of 1,950 miles. Congratulatory 
 messages were interchanged between the Queen and the 
 President, and a few other despatches were sent during 
 the ensuing fortnight ; and then the cable refused to work. 
 
250 THE AGE OF ELECTRICITY. 
 
 A defect in it was found, but all attempts to remedy it 
 proved unsuccessful. 
 
 Of course, a good many people had important despatches 
 coming over the cable, or expected to send them ; and 
 when it began to fail, there were innumerable messages 
 sent to Trinity Bay to find out what the trouble was. The 
 manager there, an electrician named De Sauty, usually 
 sent back the most re-assuring replies, and continued quite 
 roseate in his anticipations until the cable positively refused 
 to transmit any thing more, and then he disappeared from 
 public gaze. All this has been told in verse by that most 
 charming of humorists, Dr. Oliver Wendell Holmes, in 
 the following poem, which, as the Professor at the Break- 
 fast Table, he declares to be his " only contribution to 
 the great department of ocean-cable literature. As all 
 the poets of this country will be engaged for the next six 
 weeks in writing for the premium offered by the Crystal- 
 Palace Company for the Burns Centenary (so called, ac- 
 cording to our Benjamin Franklin, because there will be 
 na'ry a cent for any of us) , poetry will be very scarce and 
 dear. Consumers may consequently be glad to take the 
 present article, which by the aid of a Latin tutor and a 
 professor of chemistry will be found intelligible to the 
 educated classes." 
 
 DE SAUTY. 1 
 
 AN ELECTRO-CHEMICAL ECLOGUE. 
 
 PROFESSOR. BLUE-NOSE. 
 
 PROFESSOR. 
 
 Tell me, O Provincial ! speak, Ceruleo-Nasal ! 
 Lives there one De Sauty extant now among you, 
 Whispering Boanerges, son of silent thunder, 
 Holding talk with nations ? 
 
 1 Reprinted by kind permission of Dr. Holmes. 
 
THE ELECTRIC TELEGRAPH. 251 
 
 Is there a De Sauty ambulant on Tell us 
 Bifid-cleft like mortals, dormient in night-cap, 
 Having sight, smell, hearing, food-receiving feature 
 Three times daily patent ? 
 
 Breathes there such a being, O Ceruleo-Nasal ? 
 Or is he a my thus, ancient word for " humbug," 
 Such as Livy told about the wolf that wet-nursed 
 Romulus and Remus ? 
 
 Was he born of woman, this alleged De Sauty, 
 Or a living product of galvanic action 
 Like the acarus bred in Crosse's flint solution ? 
 Speak, thou Cyano-Rhinal! 
 
 BLUE-NOSE. 
 
 Many things thou askest, jackknife-bearing stranger, 
 Much-conjecturing mortal, pork-and-treacle waster, 
 Pretermit thy whittling, wheel thine ear-flap toward me. 
 Thou shalt hear them answered. 
 
 When the charge galvanic tingled through the cable 
 At the polar focus of the wire electric, 
 Suddenly appeared a white-faced man among us: 
 Called himself "Ds SAUTY." 
 
 As the small opossum held in pouch maternal 
 Grasps the nutrient organ whence the term mammalia, 
 So the~unknown stranger held the wire electric, 
 Sucking in the current. 
 
 When the current strengthened, bloomed the pale-faced 
 
 stranger, 
 
 Took no drink nor victual, yet grew fat and rosy, 
 And from time to time in sharp articulation 
 Said, "All right! DE SAUTY." 
 
 From the lonely station passed the utterance, spreading 
 Through the pines and hemlocks to the groves of steeples, 
 Till the land was filled with loud reverberations 
 Of "All right! DE SAUTY." 
 
252 THE AGE OF ELECTRICITY. 
 
 When the current slackened, drooped the mystic stranger, 
 Faded, faded, faded, as the stream grew weaker, 
 Wasted to a shadow, with a hartshorn odor 
 Of disintegration. 
 
 Drops of deliquescence glistened on his forehead, 
 Whitened round his feet the dust of efflorescence, 
 Till one Monday morning, when the flow suspended, 
 There was no De Sauty; 
 
 Nothing but a cloud of elements organic, 
 C, O, H, N, Ferrum, Chlor., Flu., Sil., Potassa, 
 Calc.,Sod., Phosph., Mag., Sulphur, Mang. (?), Alumin. (?), 
 
 Cuprum ( ?), 
 Such as man is made of. 
 
 Born of stream galvanic, with it he had perished. 
 There is no De Sauty, now there is no current ! 
 Give us a new cable, then again we'll hear him 
 Cry "All right! DE SAUTY." 
 
 Shortly after the failure of the first Atlantic cable, 
 other deep-sea cables became inoperative, and immense 
 sums of money were lost. In 1865 the immense " Great 
 Eastern" steamship, which had proved a veritable white 
 elephant to its owners, was fitted for service to transport 
 a new cable. After about half of this line had been laid, 
 it broke, and the hapless promoters of the enterprise 
 feared that some three million dollars had been added to 
 the great aggregate of losses already incurred. Prepara- 
 tions were, however, at once made for another attempt 
 during the following year. The managers of the enter- 
 prise, at the head of which was Mr. Cyrus W. Field, had 
 indomitable faith in its practicability. A close watch 
 was kept on the broken line, now resting on the ocean- 
 bed. u Night and day," says an English journal of 
 the time, " for a whole year an electrician was always 
 
THE ELECTRIC TELEGRAPH. 253 
 
 on duty, watching the tiny ray of light through which 
 signals are given ; and twice every day the whole length 
 O f w i re 1,240 miles was tested for conduction and 
 insulation. The object of observing the ray of light 
 was of course not any expectation of a message, but 
 simply to keep an accurate record of the condition of the 
 wire. Sometimes, indeed, wild incoherent messages from 
 the deep did come ; but these were merely the results of 
 magnetic storms and earth-currents, which deflected the 
 galvanometer rapidly, and spelt the most extraordinary 
 words, and sometimes even sentences of nonsense, upon 
 the graduated scale before the mirror. Suddenly, early 
 one morning the observer noticed a peculiar flicker of the 
 light which to his experienced eye showed that a message 
 was on hand. In a few minutes afterward, the unsteady 
 flickering was changed to coherency, and at once the cable 
 began to speak, to transmit the appointed signals which 
 indicated human purpose and method at the other end, 
 instead of the hurried signs, broken speech, and inarticu- 
 late cries of the still illiterate Atlantic. After the long 
 interval in which it had brought nothing but the moody 
 and often delirious mutterings of the sea stammering 
 over its alphabet in vain, the words ' Canning to Glass ' 
 must have seemed like the first rational word uttered by 
 a fever-patient when the ravings had ceased. The exact 
 spot in the trackless ocean where that cable had parted 
 had been found ; the slender wire had been picked up, 
 although two miles down under the sea; and from the 
 great ship the signals were being sent." 
 
 Meanwhile the new cable, stronger, lighter, and more 
 flexible than its predecessors, had been successfully car- 
 ried across the Atlantic by the " Great P^astern," and was 
 in working order. Then the ship went back, and, as 
 already stated, picked up the broken end. How this 
 
254 THE AGE OF ELECTRICITY. 
 
 wonderful feat of engineering was accomplished, Mr. 
 Field thus graphically tells : 
 
 "After landing the cable safely at Newfoundland, we 
 had another task, to return to mid-ocean, and recover 
 that lost in the expedition of last year. This achievement 
 has perhaps excited more surprise than the other. Many, 
 even now ' don't understand it,' and every day I am asked 
 how it was done. Well, it does seem rather difficult to 
 fish for a jewel at the bottom of the ocean two and a half 
 miles deep. But it is not so very difficult when you know 
 how. It was the triumph of the highest nautical and 
 engineering skill. We had four ships, and on board of 
 them some of the best seamen in England, men who knew 
 the ocean as a hunter knows every trail in the forest. 
 There was Captain Moriarty, who was in the ' Agamem- 
 non ' in 1857-58. He was in the ' Great Eastern ' last 
 year, and saw the cable when it broke ; and he and Cap- 
 tain Anderson at once took their observations so exact 
 that they could go right to the spot. After finding it, 
 they marked the line of the cable by a row of buoys ; for 
 fogs would come down, and shut out sun and stars so that 
 no man could take an observation. These buoys were 
 anchored a few miles apart. They were numbered, and 
 each had a flagstaff on it so that it could be seen by day, 
 and a lantern by night. Thus having taken our bearings, 
 we stood off three or four miles, so as to come broadside 
 on, and then, casting over the grapnel, drifted slowly 
 down upon it, dragging the bottom of the ocean as we 
 went. At first it was a little awkward to fish in such deep 
 water ; but our men got used to it, and soon could cast a 
 grapnel almost as straight as an old whaler throws a har- 
 poon. Our fishing-line was of formidable size. It was 
 made of rope, twisted with wires of steel, so as to bear 
 a strain of thirty tons. It took about two hours for the 
 
THE ELECTRIC TELEGRAPH. 255 
 
 grapnel to reach the bottom, but we could tell when it 
 struck. I often went to the bow, and sat on the rope, 
 and could feel by the quiver that the grapnel was dragging 
 on the bottom two miles under us. But it was very slow 
 business. We had storms and calms and fogs and squalls. 
 Still we worked on day after day. Once, on the 17th of 
 August, we got the cable up, and had it in full sight for 
 five minutes, a long, slimy monster, fresh from the ooze 
 of the ocean's bed ; but our men began to cheer so wildly 
 that it seemed to be frightened, and suddenly broke away, 
 and went down into the sea. This accident kept us at 
 work two weeks longer ; but finally, on the last night of 
 August, we caught it. We had cast the grapnel thirty 
 times. It was a little before midnight on Friday that we 
 hooked the cable, and it was a little after midnight Sunday 
 morning when we got it on board. What was the anxiety 
 of those twenty-six hours ! The strain on every man's 
 life was like the strain on the cable itself. When finally 
 it appeared, it was midnight : the lights of the ship and 
 in the boats around our bows, as they flashed in the faces 
 of the men, showed them eagerly watching for the cable 
 to appear in the water. At length it was brought to the 
 surface. All who were allowed to approach crowded to 
 see it. Yet not a word was spoken : only the voices of 
 the officers in command were heard giving orders. All 
 felt as if life and death hung on the issue. It was only 
 when it was brought over the bow and on the deck, that 
 men dared to breathe. Even then they hardly believed 
 their eyes. Some crept toward it to feel of it, to be sure 
 it was there. Then we carried it along to the electrician's 
 room, to see if our long-sought- for treasure was alive or 
 dead. A few minutes of suspense, and a flash told of 
 the lightning current set free. Then did the feeling long 
 pent up burst forth. Some turnt away their heads, and 
 
256 THE AGE OF ELECTRICITY. 
 
 wept. Others broke into cheers, and the cry ran from 
 man to man, and was heard down in the engine-rooms, 
 deck below deck, and from the boats on the water and 
 the other ships, while rockets lighted up the darkness of 
 the sea. Then with thankful hearts we turned our faces 
 again to the west. But soon the wind rose, and for thirty- 
 six hours we were exposed to all the dangers of a storm 
 on the Atlantic. Yet in the very height and fury of the 
 gale, as I sat in the electrician's room, a flash of light 
 came up from the deep, which, having crossed to Ireland, 
 came back to me in mid-ocean, telling that those so dear 
 to me, whom I had left on the banks of the Hudson, were 
 well and following us with their wishes and their prayers. 
 This was like a whisper of God from the sea, bidding me 
 keep heart and hope. The ' Great Eastern ' bore herself 
 proudly through the storm, as if she knew that the vital 
 cord which was to join two hemispheres hung at her stern ; 
 and so, on Saturday the 7th of September, we brought 
 our second cable safely to the shore." 
 
 As we all know, other cables have since been laid across 
 the Atlantic with comparative ease, by the aid of special 
 machinery and specially constructed vessels. The French 
 cable between St. Pierre and Duxbury, Mass., went into 
 operation in 1869 ; followed by the direct cable between 
 Ballinskilligs Bay, Ireland, and Rye, N.H., via Nova 
 Scotia, in 1875 ; and the Mackay-Bennett cable ten years 
 later. 
 
 The cable laid by the "Great Eastern " in 18G5-6G is 
 represented in Fig. 107. The current is conducted by a 
 strand of copper wires ; the remainder of the cable serving 
 to secure insulation, and to protect it from abrasion, etc. 
 
 The transmission of telegraphic signals through a long 
 submarine cable is a very different matter from accom- 
 plishing the same thing over a land line of similar length ; 
 
THE ELECTRIC TELEGRAPH. 257 
 
 and it is therefore necessary to explain, in as simple terms 
 as possible, some of the principal difficulties encountered, 
 and how the cable is made to operate in spite of them. 
 
 In describing the invention of the Leyden-jar, in an 
 earlier chapter, we noted the curious fact, that, while elec- 
 tricity cannot pass through an insulating substance such 
 as glass or air, it can act across the same by induction. 
 And in the Leyden-jar we have an illustration of this ; 
 for, when a plus charge of electricity is imparted to the 
 inner coating, it acts inductively on the outer coating, 
 attracting a minus charge into the face of the outer coat- 
 ing nearest the glass, and repelling a plus charge to the 
 outside of the outer coating, and this through the hand 
 
 Fig. 107. 
 
 or wire to the earth. After the jar has acquired its full 
 charge, it will, as we have already seen, retain it for a 
 considerable period of time. 
 
 When a quantity of electricity flows through a line, in 
 the form of a current, the first portion of the current is 
 retained or accumulated upon the surface of the wire in 
 the same way that a charge is retained and accumulated 
 upon the surface of a Leyden-jar. The wire itself answers 
 to one of the conducting coatings of the jar ; the earth, 
 or other wires connected to earth, to the other conducting 
 coating ; and the air, to the glass or separating di-electric. 
 The quantity of electricity thus accumulated depends 
 upon the length and surface of the wire, upon its proxim- 
 ity to the earth, and upon the insulating medium that sepa- 
 
258 THE AGE OF ELECTRICITY. 
 
 rates it from the earth. This power of retaining a charge 
 is called the electro-static capacity of the circuit. 
 
 The effect of this accumulation is to hold back or pre- 
 vent the appearance of the first portion of the current sent 
 at the distant station ; and, furthermore, before a current 
 in the reverse direction can be sent through the circuit, 
 the whole of this charge upon the wire must be withdrawn 
 or neutralized before a second charge of opposite sign can 
 be accumulated upon it. The result of this is to prolong 
 the current flowing out at the distant end. 
 
 In submarine cables, the conducting wires are separated 
 from the earth upon which the cable rests, and the water 
 which surrounds it, simply by the insulating covering ; 
 and hence the whole cable becomes one huge Leyden-jar 
 of much capacity. The consequence is, that the current 
 is retarded so much, that, unless the signals are sent very 
 slowly, they will run together and be illegible. The retar- 
 dation upon an Atlantic cable is about four-tenths of a 
 second. Twenty dots per second can be firmly and clearly 
 recorded on a short overground line, with little induction ; 
 while on a long cable, not more than two dots per second 
 can be received. 
 
 Besides the difficulties due to retardation, earth-cur- 
 rents varying in strength are set up in the cable, by rea- 
 son of its connecting portions of the earth which happen 
 to be of different potentials. These were the cause of the 
 strange signals which came from the broken cable of 1865 ; 
 and at times they acquire such magnitude as to become 
 " electric storms," interrupting the circuits to such an 
 extent as greatly to hinder working, and sometimes en- 
 dangering the safety of the cable itself. It is necessary, 
 therefore, in cable telegraphy, to counteract the ill effects 
 of earth-currents, and also to reduce to the lowest possi- 
 ble point the retarding influence of induction ; and the 
 
THE ELECTRIC TELEGRAPH. 
 
 259 
 
 n 
 
 ^al 
 
 m^^Mlfc////A Lx 
 
 \ 
 a z 
 
 
 ordinary apparatus used in telegraphing upon land lines 
 becomes useless for this purpose. 
 
 Two new instruments, not necessary upon land lines, 
 are therefore introduced ; the. first being the condenser, 
 which prevents induction, and sharpens the signals ; and 
 the second being the mirror galvanometer, or siphon 
 recorder, which indicates or records them. 
 
 The condenser is simply a modified form of Leyden-jar, 
 of large surface, and constructed to have any desired capa- 
 city. It is usually made of alternate layers of paraffined 
 paper or mica and 
 tin-foil ; as indicat- 1 
 ed in Fig. 108, in 
 which the dark lines 
 a a 1 a 2 , b b 1 6 2 , repre- 
 sent tin-foil, and the 
 shaded intermediate 
 portions, the paraf- 
 fined paper. The 
 series a a 1 a? of tin- 
 foil sheets are con- 
 nected together, thus forming one of the coatings of the 
 Leyden-jar ; and the alternating sheets b b 1 b 2 are united 
 to form the other coating. If we connect one pole of a 
 battery to the sheets a a 1 a 2 , and the other pole to the 
 sheets b b 1 b 2 , the condenser will be charged with a quantity 
 of electricity depending upon the number of battery-cells 
 used, upon the surface of the plates opposed to each other, 
 and upon the number of plates in the respective sets. In 
 this way condensers of any desired capacity can be made, 
 having a charge varying from that accumulated upon one 
 mile of overground wire up to that accumulated upon an 
 Atlantic cable. The unit or standard of reference by 
 which capacity is known is called the microfarad, and is 
 
 Fig. 108. 
 
260 THE AGE OF ELECTRICITY. 
 
 equivalent to the charge contained by about three miles of 
 cable. 
 
 The conventional mode of representing a condenser is 
 by two parallel lines as a 6 : in Fig. 109, from which illus- 
 tration the operation of the condenser, when applied to a 
 telegraphic line, will easily be understood. 
 
 Let us suppose that A B is a cable crossing the Atlantic. 
 At one end is an ordinary key and battery, and at the 
 other a condenser having one set of its conducting plates 
 connected to the cable, and the other set to a galvanometer 
 which in turn is connected to earth. The circuit is evi- 
 dently broken at the condenser, so that it is impossible 
 
 %J^ -CaMc 
 
 L 
 
 Credit 
 
 -m^Uct 
 
 k &vy 
 
 ^\Eart/i- coiutcctioit JEart/v 
 
 Fig. 109. 
 
 for the battery current to proceed directly to the galva- 
 nometer ; but if we depress the key, a current flows from 
 the battery into the cable to charge it. The plate a of 
 the condenser, being thus charged in (say) positive elec- 
 tricity, attracts across the paraffined paper interposed 
 between it and the opposite plate 6, electricity of opposite 
 name, and repels electricity of the same name, which 
 apparently passes to earth through the galvanometer in 
 the form of a short current or pulsation. When the key 
 is returned to its normal position, the cable is discharged, 
 the positive charge on b is released, and it flows to earth 
 in the reverse direction through the galvanometer, in the 
 
THE ELECTEIC TELEGRAPH. 
 
 261 
 
 form of a second current or pulsation. Thus, whenever 
 we depress the key, we affect the galvanometer with a 
 reversal. 
 
 By using galvanometers or other receiving apparatus 
 of the most sensitive character, which are actuated by 
 the first appearance of the current, cables are worked 
 with the smallest electro-motive force ; and generally by 
 suitably determining the size of the condenser, the num- 
 ber of cells, and the delicacy of the galvanometer, we 
 can transmit signals which give the maximum speed with 
 
 the minimum expenditure of power. In practice the con- 
 densers used have a capacity equal to that of about sev- 
 enty miles of cable. From four to ten cells of one form 
 of Daniell's battery furnish the current. 
 
 The receiving apparatus is either a mirror galvanometer 
 or a siphon recorder, both instruments of remarkable 
 sensitiveness, devised by Sir William Thomson. The 
 general arrangement of the mirror galvanometer is shown 
 in Fig. 110, where C is a coil of fine insulated wire, sur- 
 
262 THE AGE OF ELECTRICITY. 
 
 rounding a small magnetic needle hung by a silk fibre, 
 and carrying a tiny mirror attached to it. The details 
 are shown in the lower figure, where C C are sections 
 through the coil. At M is the magnet-needle, carrying 
 in front of it a small mirror. This needle is enclosed 
 in a small chamber, glazed by a lens 6r, and inserted in 
 the hollow of the coil C. A curved magnet H is sup- 
 ported over the coil to adjust the position of the smaller 
 magnet in the chamber. Now a ray of light from a lamp 
 L in front of the galvanometer is thrown upon the tiny 
 mirror, and reflected back upon a white screen or scale 
 S. The coil C is connected between the end of the con- 
 ductor of the cable and the earth-plate, as in the land 
 circuit ; a condenser, however, being usually interposed 
 between the cable and the galvanometer. 
 
 Then the signal currents in passing through the coil 
 deflect the tiny magnet hung within it ; and the mirror, 
 being carried by the magnet, throws the beam of light off 
 in a different direction. Positive, or " dot," currents are 
 arranged to throw the spot of light toward the left side 
 of the scale ; and negative, or " dash," currents throw it 
 to the right side. Thus the wandering of the spot of light 
 on the screen, watchfully followed by the eye of the clerk, 
 is interpreted by him as the message. Letter by letter he 
 spells it out, and a fellow-clerk writes it down word for 
 word. 
 
 Sometimes the fellow-clerk .is a lady, frequently per- 
 haps now, since the fair sex has proven its ability to 
 manage the key, and this circumstance may account 
 for the publication in a scientific journal, some years ago, 
 of the following capital parody on Tennyson's " Bugle 
 Song:" 1 
 
 i By Professor J. Clerk Maxwell. 
 
THE ELECTRIC TELEGRAPH. 263 
 
 A LECTURE ON THOMSON'S GALVANOMETER 
 
 Delivered to a Single Pupil, in an Alcove with Drawn Curtains. 
 
 The lamp-light falls on blackened walls, 
 
 And streams through narrow perforations ; 
 The long beam trails o'er pasteboard scales, 
 
 With slow decaying oscillations. 
 Flow, current, flow ! set the quick light spot flying ! 
 Flow, current! answer, light spot ! flashing, quivering, dying. 
 
 Oh, look ! how queer ! how thin and clear, 
 
 And thinner, clearer, sharper growing, 
 This gliding fire with central wire 
 
 The fine degrees distinctly showing. 
 Swing, magnet, swing ! advancing and receding ; 
 Swing, magnet ! answer, dearest, what's your final reading ? 
 
 O love ! you fail to read the scale 
 
 Correct to tenths of a division ; 
 To mirror heaven those eyes were given, 
 
 And not for methods of precision. 
 Break, contact, break ! set the free light spot flying. 
 Break, contact ! rest thee, magnet ! swinging, creeping, dying. 
 
 This receiver, however, like the sounder, has the disad- 
 vantage of leaving no permanent record ; and Sir William 
 Thomson has therefore introduced his siphon recorder on 
 several long cables, for instance, the Eastern Telegraph 
 Company's lines to India, and the Anglo-American Com- 
 pany's cables across the Atlantic. The principle of its 
 action is just the reverse of the mirror galvanometer. In 
 that instrument, a tiny magnet moved within a fixed coil 
 of wire ; in the siphon recorder, a light coil of wire moves 
 between the poles of a powerful magnet. The signal 
 currents pass through the suspended coil to earth ; and in 
 doing so the coil turns to left or right, according as the 
 currents are positive or negative. These movements of 
 
264 THE AGE OF ELECTRICITY. 
 
 the coil are communicated by a connecting thread to a 
 fine glass siphon, which is constantly spurting ink upon 
 a band of travelling paper ; and hence the trace of the 
 ink on the paper follows and delineates the movements of 
 the coil. So fine is the bore of the siphon, that the ink 
 will not run unless it is electrified. A specimen of the 
 message it furnishes is given in Fig. Ill, which represents 
 the alphabet. 
 
 That some day we shall be able to transmit pictures by 
 telegraph, is not without the bounds of reasonable possi- 
 bility ; not drawings or designs, such as can now be sent 
 by the autographic systems, but actual photographs, images 
 of things existing in front of the transmitting instrument, 
 so that a person in one place can see what is going on in 
 
 -n^nFNT/ 1 -^^ 
 
 TA/ir- y lnhA^^ 
 
 Fig. 111. 
 
 another. The first step in this direction has already been 
 accomplished by Mr. Shelford Bidwell, in his exceedingly 
 ingenious telephotograph, by means of which it is now 
 quite possible to transmit shadows or silhouettes. The 
 principle of Mr. Bid well's apparatus is based upon the 
 fact that the resistance of crystalline selenium varies with 
 the intensity of the light falling upon it. Its operation 
 depends, as in the autographic telegraph, upon the syn- 
 chronous movement of two cylinders at opposite ends of 
 the line, and will be easily followed by the aid of the 
 diagram, Fig. 112. 
 
 The transmitting instrument consists of a cylindrical 
 brass box, mounted upon but insulated from a metal spin- 
 dle. The spindle is divided in the middle ; and the halves, 
 while rigidly joined together, are insulated from each 
 
THE ELECTEIC TELEGRAPH. 
 
 265 
 
 other by a layer of wood. One of the ends of the spin- 
 dle has a fine screw-thread cut on it ; the other end is 
 plain. The spindle is arranged to revolve in metal bear- 
 ings, one of which is threaded so that when the spindle 
 rotates it also has an endwise longitudinal movement like 
 
 Fig. 112. 
 
 that of the cylinder of the phonograph. At a point mid- 
 way between the ends of the brass box mounted on the 
 spindle, a small hole is drilled ; and behind this hole is 
 fixed a selenium cell, the two terminals of which are con- 
 nected respectively to the halves of the spindle, and the 
 bearings of this last are connected electrically to binding- 
 
266 THE AGE OF ELECTRICITY. 
 
 screws on the base of the instrument. In the engraving, 
 Y represents the transmitter. The hole in the cylinder is 
 at 77, and at S is the selenium cell. 
 
 The receiving instrument shown at X (Fig. 112) con- 
 tains another cylinder, similar to that of the transmitter, 
 and mounted on a similar spindle, which, however, is not 
 divided nor insulated from the cylinder. An upright pil- 
 lar 7), fixed midway between the two bearings, and slight- 
 ly higher than the cylinder, carries an elastic brass arm 
 with a platinum point P, which presses normally upon 
 the surface of the cylinder. To the brass arm, a binding- 
 screw is attached, and a second binding-screw in the stand 
 is joined by a wire to one of the brass bearings. 
 
 In operation the cylinder of the transmitter Y is brought 
 to its middle position, and a picture not more than two 
 inches square is focussed upon its surface by means of a 
 lens. The cylinder of the receiver is covered with paper 
 soaked in a solution of potassium iodide. 
 
 The two cylinders are caused to rotate slowly and syn- 
 chronously. The pin-hole at H, in the course of its spiral 
 path, will cover successively every point of the picture 
 focussed upon the cylinder ; and the amount of light fall- 
 ing at any moment upon the selenium cell will be propor- 
 tional to the illumination of that particular spot of the 
 projected picture which for the time beiug is occupied by 
 the pin-hole. During the greater part of each revolution, 
 the point P will trace a uniform brown line ; but when the 
 hole happens to be passing over a bright part of the pic- 
 ture this line is enfeebled and broken. The spiral traced 
 by the point is so close as to produce, at a little distance, 
 the appearance of a uniformly colored surface ; and the 
 breaks in the continuity of the line constitute a picture 
 which, if the instrument were perfect, would be a mono- 
 chromatic counterpart of that projected upon the trans- 
 
THE ELECTRIC TELEGRAPH. 267 
 
 mitter. Fig. 113 represents an image as projected by a 
 magic-lantern upon the transmitter, and Fig. 114 the same 
 reproduced by the receiver. A selenium cell whereby the 
 
 Fig. 113. 
 
 electrical resistance to the current is varied, is also used 
 in connection with the photophone hereafter described. 
 
 Telegraphy is by no means confined to communication 
 between fixed stations. It is now perfectly possible to 
 
 Fig. 774. 
 
 communicate with express-trains travelling at high speed, 
 and it is not unlikely that some means will be found of 
 maintaining telegraphic communication with ships at sea. 
 Probably the earliest suggestion of transmitting a current 
 
268 THE AGE OF ELECTRICITY. 
 
 to a moving vehicle was that made by Wright and Bain in 
 1842. These inventors proposed the ingenious plan of 
 having a pilot-engine run some live miles ahead of the 
 locomotive of a rail way- train, and of establishing electri- 
 cal communication between the two, so that in event of 
 any accident, such as the derailment of the pilot-engine, 
 the fact would be instantly known to the driver of the 
 locomotive. The battery was to be carried on the loco- 
 motive ; and circuit was made from the battery to an 
 electro-magnet, and thence to a continuous conductor laid 
 between the rails, along which contact-springs on the loco- 
 motive rubbed. The pilot-engine also carried springs held 
 in contact with the central conductor ; and the current 
 thence passed to a governor on the pilot, which, while the 
 engine was in motion, was driven by the wheels. So long 
 as the pilot-engine was running all right, tho governor 
 kept the circuit closed ; but if the engine stopped, the 
 governor balls fell, opening the circuit, so de-energizing 
 the electro-magnet on the following locomotive. The 
 magnet was thus caused to release its armature, and thus 
 to sound an alarm, and move a pointer on a dial to the 
 word "Danger." A somewhat analogous system exists 
 on several European railways, in which a contact brush or 
 plate on the locomotive closes a circuit through the rails, 
 so that the approach of the train is thus signalled to a 
 station, or the driver is warned, by the sounding of an 
 alarm, that a switch before him is not properly set. By 
 the same means, the engine-whistle may also be blown, or 
 the brakes automatically set in operation to stop the train. 
 Two systems of telegraphic apparatus have recently been 
 devised for communicating with moving trains. Phelps's 
 arrangement is based on the well-known fact that if two 
 w r ires are extended parallel, near but not touching each 
 other, and a current is sent through one, a momentary 
 
THE ELECTRIC TELEGRAPH. 269 
 
 current is excited in the other wire, opposite in direction 
 to that flowing in the first. A telegraph-wire is arranged 
 in the centre of the railway-track, and another wire is 
 attached to the bottom of the railway-car, with which last- 
 mentioned wire is connected a telegraph-sounder within 
 the car. Whenever an electrical signal is sent through 
 the track telegraph wire, it produces by induction a cor- 
 responding current in the wire attached to the car, and 
 this current works the sounder, thus delivering the mes- 
 sage. It matters not how fast the train may be moving, 
 if the wire on the bottom of the car is brought within a 
 short distance of the telegraph or track wire, any strong 
 electric impulses, such as telegraph signals, that are pass- 
 ing along the track wire, will be taken up by induction by 
 the car wire, and delivered by the sounder ; and, vice 
 versa, when the operator on the moving car operates the 
 lever of his telegraph instrument, and sends electrical im- 
 pulses or messages through the wire that hangs below the 
 floor of the car, these impulses will be taken up by induc- 
 tion by the track wire, and conveyed to .the sounding 
 instrument of the railway-station. By this system com- 
 munication has been successfully maintained with a train 
 running forty miles per hour. 
 
 In another system devised by Edison and others, the 
 induction takes place between the wires strung in the 
 usual way on poles beside the track, and the metal roofs 
 of the cars which are electrically connected together. An 
 insulated wire runs from the roof of the telegraphing car, 
 to a switch at the operator's desk ; and by means of this 
 switch the circuit may be completed through a receiving 
 or a transmitting instrument. The receiver may either be 
 an ordinary telephone, or a pair may be used and held to 
 the ears somewhat after the manner of ear-muffs. After 
 coming from the receiver, the wire is carried under the 
 
270 THE AGE OF ELECTRICITY. 
 
 car, and connected to a strip of copper which is pressed 
 against a copper cylinder on one of the axles by means of 
 a spring, thus giving a ground connection by the axle and 
 wheel. When, however, a message is to be transmitted, 
 the switch connects the roof to the secondary wire of an 
 induction coil, with the primary of which a battery, a 
 Morse key, and a vibrating circuit-breaker are in circuit. 
 When the current is established, the vibrator, which con- 
 tains a metallic reed, is thrown into rapid movement ; the 
 free end of the reed at each vibration striking against a 
 button, and so sharply making and breaking the circuit 
 into a great number of waves or pulsations. These pul- 
 sations in the primary coil induce currents of high poten- 
 tial in the secondary coil, which, so to speak, charge the 
 roof as if it were one plate of a condenser. The wires 
 on the poles thus become charged by induction, as the 
 opposite plate of a condenser is charged, through the inter- 
 vening air ; and as this charge is governed by the 
 manipulation of the Morse key, which throws the vibrator 
 into and out of action, dots and dashes of the Morse 
 alphabet can be signalled. 
 
 New applications of the telegraph are constantly being 
 invented. We are only at the very beginning of its utili- 
 zation in the affairs of every-day life, and yet its developed 
 capabilities are bewildering. There is little exaggeration 
 in the statement that one can sit at home, and "steer a 
 torpedo boat in New- York harbor, or ring the bells in 
 Boston, or play the organ in St. Peter's, or explode a 
 mine in China, or write a letter on the desk of a cor- 
 respondent in Constantinople," and perhaps, in the 
 future, talk to a friend in Australia, and even see him 
 face to face. 
 
 From forty miles in 1844, the total length of telegraph- 
 wires in the United States has increased to 671,000 miles 
 
THE ELECTEIC TELEGRAPH. 271 
 
 in 1886 : enough to extend to the moon and back again, 
 and then go nine times around the earth. Nearly two 
 millions of miles of wire form an iron network over the 
 globe ; and the great army of the telegraphers numbers 
 over three hundred thousand souls. 
 
272 THE AGE OF ELECTRICITY. 
 
 CHAPTER XII. 
 
 THE SPEAKING TELEPHONE. 
 
 THE principle underlying all forms of apparatus for 
 transmitting intelligence between distant points, by the 
 aid of electricity, is to cause certain mechanical motions 
 produced at one point to be imitated at the other. And 
 these mechanical motions may range from the slow move- 
 ment of a telegraph-key worked by the human hand, to 
 the very rapid and complex vibrations of the air which the 
 ear and brain translate into the sensation of sound. The 
 motion of the telegraph-key is copied by the motion of 
 the sounder armature, or that of the recording stylus ; in 
 autographic telegraphy, the movement of the point which 
 traces the design is imitated by that of the point which re- 
 produces the same ; and the various synchronic systems 
 have for their object the exact duplication at the separated 
 stations of definite mechanical movements occurring at 
 the same rate in the same time. 
 
 The simplest way of transmitting mechanical motion 
 between distant points is by means of some solid body 
 extending between them. The connecting-rod of an en- 
 gine transmits movement from piston-rod to fly-wheel ; by 
 means of belts, we can cause one rotating shaft to move 
 another at a considerable distance away ; by pulling a 
 cord or wire in one part of a house, we can ring a bell at 
 another. In all of these instances, the whole of the com- 
 
THE SPEAKING TELEPHONE. 273 
 
 municating body whether it be rod or belt or wire 
 moves simultaneously. 
 
 Motion, however, may also be transmitted by means of 
 waves or pulsations in the communicating body, which 
 then does not move as a whole. In such case, the move- 
 ment is first imparted to the particles of the body nearest 
 the source. These are set vibrating, or swinging to and 
 fro ; and in so travelling they communicate their motion 
 to a succeeding set of particles, which in turn swing or 
 vibrate ; these, again, in turn actuate the particles next in 
 advance ; and so the vibration or wave travels from one 
 end of the body to the other. This is called wave or 
 vibratory^ motion. Light, for example, is propagated by 
 motion of this kind, in an assumed luminiferous ether ; 
 heat, sound, and probably electricity, by wave-motions in 
 the molecules of matter. We see this vibratory motion 
 constantly at work in waves on water. 
 
 When any body vibrates in air or water, or any material 
 substance, the air or other substance is set in motion, 
 and the waves are propagated farther and farther from 
 the impelling source, until finally their energy becomes 
 exhausted. This movement of the air, on reaching the 
 human ear, causes the sensation of sound, provided it is 
 competent to affect the mechanism of hearing. It has 
 been determined that the ear cannot perceive sounds when 
 the number of vibrations is less than sixteen, or more than 
 thirty-two thousand, per second ; but the limits of hear- 
 ing vary greatly. If the vibrating body be in the open 
 air, the impulses spread equally on all sides around ; 
 sometimes having great mechanical force, as when an 
 explosion of dynamite shatters walls even at a consider- 
 able distance. So also the air is competent to carry very 
 minute vibrations ; as, for instance, those which, as we 
 shall see hereafter, cause the different quality of human 
 
274 THE AGE OF ELECTRICITY. 
 
 voices. In order to prevent the diminution in intensity of 
 the air-waves caused by the vibration of our vocal organs 
 in speaking, clue to their spreading in all directions, the 
 speaking-tube is employed ; and this is the most common 
 mode of carrying the voice between distant points. Here 
 the column of air is enclosed in a pipe, and the pulsations 
 are passed on from end to end, almost without loss, over 
 short distances. 
 
 Solids such as wood, metal, the earth, and liquids such 
 as water, are much better conductors of sound than air or 
 other gases. A faint scratch of a pin on a long board is 
 very easily heard through the board many feet away, even 
 though it may not be audible through the air to the per- 
 son making it. Savages often discover the proximity of 
 enemies or of prey by applying an ear to the ground, and 
 hearing the tread. The mutterings of earthquakes, due 
 to subterranean explosions or upheavals, are heard through 
 amazing distances of earth. The velocity of sound in 
 air is about 1,120 feet per second ; in water, about four 
 times, and in metals from four to sixteen times, as great. 
 
 The idea of transmitting sounds of the voice through 
 solid conductors is known to date back to 1G67. At that 
 date Dr. Robert Hooke wrote : "It is not impossible to 
 hear a whisper at a furlong's distance, it having already 
 been done ; and perhaps the nature of the thing would not 
 make it more impossible though that furlong should be ten 
 times multiply 'd. And though some famous authors have 
 affirmed it impossible to hear through the thinnest plate of 
 muscovy glass : yet I know a way by which it is easie 
 enough to hear one speak through a wall a yard thick. 
 It has not yet been thoroughly examin'd how far otacous- 
 ticons may be improv'd nor what other wayes there may 
 be of quick'ning our hearing or conveying sound through 
 other bodies than the air : for that that is not the only me- 
 
THE SPEAKING TELEPHONE. 275 
 
 dium I can assure the reader, that I have by the help of a 
 distended wire propagated the sound to a very considerable 
 distance in an instant or with as seemingly quick a motion 
 as that of light, at least incomparably quicker than that 
 which at the same time was propagated through the air, 
 and this not only in a straight line or direct but in one 
 bended at many angles." 
 
 In 1819 Sir Charles Wheatstone invented his magic 
 lyre, and in 1831 exhibited it at the Polytechnic Institution 
 in London. He called it the telephone, thus inventing the 
 name. Performers on various instruments were placed in 
 the basement of the building, and the sounds which they 
 produced were conducted by solid rods through the princi- 
 pal hall, in which they were inaudible, to sounding-boards 
 in a concert- room on an upper floor, where the music was 
 heard by the audience precisely as if it were being per- 
 formed there. It is related, that, shortly after Sir Charles 
 Wheatstone had invented the above device, he invited a 
 distinguished foreign musician a noted performer on 
 the violoncello to dine with him. In order to surprise 
 his guest, he suspended a violoncello in his entrance-hall, 
 arranging in contact with it a concealed rod which com- 
 municated with a like instrument in another room. On 
 the arrival of the visitor, he was left alone in the hall, 
 and naturally his attention was at once attracted by the 
 strains of music apparently coming from no visible source, 
 yet clearly being produced in the same apartment. Finally 
 he traced them to the instrument on the wall, examined 
 it critically, could find no reason for them ; and then as 
 if struck with sudden terror, with a cry of dismay, the 
 affrighted musician rushed out of the house. Nothing 
 could convince him that the instrument was not bewitched, 
 nor induce him to trust himself again in its proximity. 
 
 Meanwhile there had been known probably since time 
 
276 THE AGE OF ELECTRICITY. 
 
 immemorial, for the Chinese are said to have used it ages 
 ago an apparatus called the "lover's telegraph," in 
 which sounds of the voice were transmitted between dis- 
 tant points, over a stretched string or wire. The contriv- 
 ance will easily be understood from Fig. 115, in which A 
 and B are hollow cylinders, usually of tin, each having 
 one end covered with a piece of membrane. The string 
 is fastened at each extremity to the centres of the mem- 
 branes, and is strained taut when the instrument is used. 
 Words spoken into one cylinder are very clearly heard by 
 a listener at the open end of the other. Just how and 
 why this little device operates, is by no means clear. 
 
 Fig. 115. 
 
 The membrane spoken to, however, vibrates correspond- 
 ingly to the air-waves made by the speaker's voice ; and 
 probably the impulses passing over the string move the 
 other membrane so that it copies the motions of the first, 
 and thus becomes a body vibrating in a particular way, 
 an,d competent in turn to make air- waves which the ear 
 recognizes as speech, just as if the vocal organs of the 
 original speaker had been transported to the distant end of 
 the line. We say " probably," because it is by no means 
 certain that this happens ; and, in fact, there is a great deal 
 to be discovered about the instrument. Whatever may be 
 the true reason, it is certain that speech is very clearly 
 transmitted and reproduced ; and in its more improved 
 modern forms the device now known as the acoustic tele- 
 
THE SPEAKING TELEPHONE. 277 
 
 phone is much more efficient for short lines, where the wire 
 can be suspended clear of other objects, than any telephone 
 depending on electricity, which of course this does not. 
 
 In tracing the history of the telegraph, we have noted 
 some of the early attempts made to produce sound-signals 
 at the far end of the line. Prior to Morse's invention, it 
 was difficult to record the operation of the current ; and 
 to rely on visual signals was to depend on the watchfulness 
 of the receiving operator at all times. One inventor pro- 
 posed explosions which would very effectually alarm the 
 sleepiest attendant ; another rang bells, and so on. For 
 several years succeeding the introduction of Wheatstone's 
 needle telegraph in England, this problem was widely 
 studied. In 1837 Professor Page of Washington discov- 
 ered that an electro-magnet when magnetized and demag- 
 netized gives forth a sound ; and when the current through 
 its coil is rapidly established and broken, these sounds 
 may succeed each other with sufficient velocity to produce 
 a musical tone, the pitch of which will depend upon 
 the number of times the sound is produced per second. 
 Page's discovery was made the basis of further investiga- 
 tions by Wertheim and others. 
 
 In 1854 M. Charles Bourseul published one of those 
 curious speculations which have so often foreshadowed 
 remarkable inventions. It is very frequently sometimes 
 too frequently the case, that the imagination of the 
 reader, after the event, causes him to detect in these prior 
 records the recital of ideas never broached until long 
 afterwards ; just as one can find in Milton such lines as 
 these : 
 
 " When with one virtuous touch 
 The arch-chymic sun, so far from us remote, 
 Produces with terrestrial humor mixed 
 Here in the dark, so many precious things 
 Of color glorious, and effect so rare," 
 
278 THE AGE OF ELECTRICITY. 
 
 and thence argue that photography must have been known 
 in Milton's time. Bourseul, however, wrote much less 
 oracularly than is common in the circumstances. He 
 says, " I have, for example, asked myself whether speech 
 itself may not be transmitted by electricity ; in a word, 
 if what is spoken in Vienna may not be heard in Paris. 
 The thing is practicable in this way. We know that 
 sounds are made by vibrations, and are adapted to the 
 ear by the same vibrations which are reproduced by the 
 intervening medium. But the intensity of the vibrations 
 diminishes very rapidly with the distance ; so that it is, 
 even with the aid of speaking-tubes and trumpets, impossi- 
 ble to exceed somewhat narrow limits. Suppose that a 
 man speaks near a movable disk, sufficiently flexible to 
 lose none of the vibrations of the voice, that this disk al- 
 ternately makes and breaks the current from a battery : you 
 may have at a distance another disk ivhich will simulta- 
 neously execute the same vibrations. It is true that the 
 intensity of the sounds produced will be variable at the 
 point of departure at which the disk vibrates by means of 
 the voice, and constant at the point of arrival where it 
 vibrates by means of electricity ; but it has been shown 
 that this does not change the sounds. It is, moreover, 
 evident that the sounds will be reproduced at the same 
 pitch. The present state of acoustic science does not 
 permit us to declare a priori if this will be precisely the 
 case with the human voice. The mode in which these 
 syllables are produced has not yet been sufficiently inves- 
 tigated. It is true that we know that some are uttered 
 by the teeth, others by the lips, and so on ; but this is 
 all. 
 
 " However this maybe, observe that the syllables can 
 only reproduce upon the sense of hearing the vibrations 
 of the intervening medium : reproduce precisely these vi- 
 
THE SPEAKING TELEPHONE. 279 
 
 brat ions, and you will reproduce precisely these syllables. 
 ... It need not be said that numerous applications of 
 the highest importance will immediately arise from the 
 transmission of speech by electricity. Any one who is 
 not deaf and dumb may use this mode of transmission, 
 which would require no apparatus except an electric bat- 
 tery, two vibrating disks, and a ivire." 
 
 There can be no question as to the remarkable knowl- 
 edge possessed by the writer, especially as indicated by the 
 words Italicized. Bourseul had undoubtedly realized the 
 fundamental principle, that, in order to reproduce sounds 
 in air at the distant end of a wire, the apparatus must be 
 competent to copy the vibrations which originally were 
 imposed on the sending apparatus by the voice. He 
 clearly saw, however, that his conception was by no means 
 adequate to the object. 
 
 Thus two ideas were well established before 1860 : first, 
 that it might be possible to cause an object to vibrate 
 by the voice, so as to make and break a current passing 
 upon a telegraph-line, causing in that current pulsations 
 corresponding in frequency with the vibrations due to the 
 sounds produced ; and, second, that when a current, rap- 
 idly interrupted, entered the coils of an electro-magnet, 
 the magnet would yield a sound which would be a musical 
 tone depending for its pitch upon the number of times the 
 current was interrupted per second. 
 
 But Bourseul, who proposed the making and breaking 
 of the current by the disk moved by the voice, apparently 
 knew nothing about reproducing the tone by the electro- 
 magnet ; and Page, who invented "galvanic music," knew 
 nothing about interrupting the current by voice-controlled 
 mechanism. And this brings .us to the remarkable history 
 of Philipp Reis, the man in whom his Fatherland persists 
 in recognizing the true inventor of the speaking telephone. 
 
280 THE AGE OF ELECTRICITY. 
 
 A tablet so inscribed marks the house in which he was 
 born, and a like inscription is graven on the monument 
 publicly reared in his honor. 
 
 Johann Philipp Reis was born at Gelnhaussen in the 
 principality of Cassel, Germany, in 1834. His father, a 
 master baker, gave him a good education, and finally ap- 
 prenticed him to a color-manufacturer. A natural taste 
 for scientific subjects led to his becoming in 1851 a mem- 
 ber of the Physical Society of Frankfort, where he began 
 the studies which subsequently led him to take up teaching 
 as a profession. In 1858 Reis became a tutor in Gamier' s 
 Institution for Boys at Friedrichsdorf, and this was his 
 position in life when he began his electrical experiments. 
 The instrument which, in probable ignorance of Wheat- 
 stone's long-prior use of the name, he called u das Tele- 
 plion," was devised in I860 ; and he lectured on it publicly 
 at various times between 1861 and 1864. Between those 
 who misunderstood it entirely, and those who, like Pog- 
 gendorf, refused even to publish Reis' memoir on the 
 apparatus because the transmission of speech by electricity 
 was regarded as too chimerical for serious consideration, 
 the invention met with little or no appreciation. Various 
 professors lectured upon it, and several instruments were 
 sold to physical laboratories throughout the world ; but 
 outside of Reis himself and a few intimate friends, it is 
 doubtful if any one regarded the invention as more than 
 a scientific curiosity creditable, of course, to its origina- 
 tor, but by no means giving him any title to fame. Reis 
 lived until 1874, but his labors upon his telephone appear 
 to have ended ten years before his death. His opponents 
 say, that, having failed to transmit speech by his appara- 
 tus, he perforce dropped it ; his friends, that he laid it 
 aside partly from ill health, but mainly from a feeling of 
 deep disappointment because of the lack of appreciation 
 
THE SPEAKING TELEPHONE. 281 
 
 which it encountered among his brother scientists. It 
 does not appear that he made any other inventions ; and 
 to his early decease may perhaps be attributed the fact 
 that he rose to nothing higher than an humble tutorship. 
 What with ill health, and the sense of many rebuffs prey- 
 ing upon him, his life, he says in his autobiographical 
 notes, was one of "labor and sorrow ; " yet there is little 
 in Reis' history to support this conclusion, especially when 
 contrasted with the records of the privations and hardships 
 which have fallen to the lot of many of the world's great- 
 est inventors. Reis does not appear ever to have suffered 
 from poverty, nor to have depended in any sense upon 
 the success of his invention for support. He was able to 
 leave a useful trade, to prosecute studies which fitted him 
 for his own chosen occupation, teaching, and equally 
 able to secure a permanent position as a tutor, which 
 afforded him not only leisure for the prosecution of his 
 investigations, but congenial associates who have testified 
 to their appreciation of his efforts. Contrast this with the 
 long penury and want of Howe, of Whitney, of Henry 
 Cort, and a host of others, and Reis' lot in life was 
 comparatively enviable. 
 
 Reis, moreover, lacked that peculiarity of inventors, 
 persistence. It is enough to say, that, if he had the 
 knowledge of the immense importance of his invention 
 which is now ascribed to him, his failure to prosecute it 
 for the last ten years of his life between the ages of 
 thirty and forty, when the enthusiasm of youth has hardly 
 begun to be tempered with the conservatism which comes 
 with later years is simply phenomenal. Most inventors 
 imbued with a great thought, like Stephen Gray, never 
 relinquish it until death ; and in the face of suffering and 
 poverty, their devotion to their ideals too often results in 
 sacrifices and self-denials far greater than those which, 
 
282 THE AGE OF ELECTRICITY. 
 
 when otherwise directed, have provoked the admiration 
 of the world, and made men heroes. 
 
 Reis devised several forms of telephonic instruments, 
 including many merely experimental, and substantially 
 embodied in more complete devices. His manipulative 
 skill was of a very low order. He had an actual poverty 
 of resource in adapting means to ends. He differed from 
 the generality of inventors, who construct means first, and 
 evolve theories afterwards. 
 
 In order to understand what Reis did, it is necessary to 
 recall a few salient facts relative to sound, to some of 
 which reference has already been made. 
 
 Sound, as we have seen, is due simply to wave-motion 
 or vibration of the air, or other material medium in which 
 the motion is propagated. The waves or vibrations may 
 differ in length, in frequency, or in shape. We can always 
 see on the ocean long waves and short waves, waves fol- 
 lowing each other rapidly or slowly, and waves smooth 
 and glassy, like the ground-swell, or broken up on their 
 surfaces into multitudinous smaller waves, as when the 
 wind blows strongly. The length of a sound-wave 
 that is, the path over which the air-particles swing to and 
 fro determines the loudness of the resulting sound; the 
 frequency of the waves, the pitch of the sound, a higher 
 or lower note on the musical scale ; and the shape of the 
 wave governs the quality or timbre of the sound, upon 
 which depends the difference between the sound of a flute 
 and that of a violin, between the sweet note of the night- 
 ingale and the screech of a peacock, and between articu- 
 late speech and a groan or a howl or a moan. 
 
 We can thus form some notion of what a complex thing 
 an air-wave produced by speech is. We are constantly 
 raising and lowering our voices, and hence there are waves 
 of all conceivable lengths. We are also constantly using 
 
THE SPEAKING TELEPHONE. 283 
 
 different notes of the musical scale, and modulations of 
 all sorts, even in talking ; and so the waves are set in 
 motion by our vocal apparatus with all degrees of fre- 
 quency. And, finally, we articulate, we use inflections ; 
 our voice is rough or harsh, or sweet and melodious ; and 
 so imposed on the air-waves are all sorts of ripples, smaller 
 waves, which contort and change their shapes. 
 
 It is not difficult to conceive that the simple frequency 
 of the waves of sound may set a disk free to be moved, 
 like a drum-head, vibrating with like frequency ; so 
 that, as Bourseul points out, we can cause that disk to 
 make or break an electrical current as many times per 
 second as there are air-vibrations in that time. But when 
 the same disk is made, by the same waves, to vibrate over 
 a long path or a short path, and even, at different periods 
 of its motion, to travel slower or faster for infinitesimal 
 intervals of time, corresponding to the little waves which 
 articulation imposes on the large ones, how are we to 
 modify the electric current by these motions? Merely 
 making and breaking the current will simply cause it to 
 set Page's needle, at the other end of a line, into vibra- 
 tion as many times per second as the current is made and 
 broken per second ; and, if the " makes " and " breaks " 
 are fast enough, the needle will sing in its own voice a 
 note of corresponding pitch. There will be no variations 
 in loudness, and the sound produced will not resemble the 
 sound transmitted, except that both will be pitched on 
 the same note. The needle will sound just the same when 
 the same note is sung to the circuit-breaking disk by a 
 Patti, or a stearn-whistle, just the same if the sound be 
 produced by the most silvery-tongued of orators, or a 
 hyena. Nothing but the pitch of the sound, nothing but 
 the succession of vibrations making that pitch, will modify 
 the current. 
 
284 THE AGE OF ELECTRICITY. 
 
 Heis, as we have said, knew all about these curious and 
 Complex characteristics of the sound-wave. He was a 
 professor of physics, and it was his business to know 
 them. Beyond this he knew of an ingenious little piece 
 of apparatus called the phonautograph, which consisted of 
 a cylinder, over one end of which was stretched a sheet 
 of membrane ; to the membrane a little stylus was fas- 
 tened, the free end of which rested on a rotating cylinder 
 covered with lamp-black. When any one talked into the 
 phonautograph, the membrane diaphragm vibrated ; and 
 when the cylinder was turned, and at the same time moved 
 lengthwise, the little stylus fastened to the membrane 
 traced queer curves and sinuosities characteristic of the 
 sounds produced : and so, in fact, in this way the sounds 
 wrote down their own peculiarities. 
 
 Now we can see the problem which was before Reis. 
 Bourseul had proposed to make the thing which under the 
 influence of the current was to vibrate, and so reproduce 
 the sounds at the receiving end, copy the movements of 
 the thing vibrated by the voice at the sending end. Reis 
 knew how complex the vibrations were, and equally knew 
 that a stretched membrane would follow them, and could 
 be set in motion by them. But how was the current to be 
 controlled by the membrane, so that it in turn would gov- 
 ern something else far off at the other end of a wire, and 
 make it copy the movements of that membrane ? Let the 
 reader think for a moment on the enormous difficulty in- 
 volved. Not only must the current be modified in some 
 way, to copy the frequency and amplitude (length) of the 
 air-vibrations, but every little minor peculiarity of the vi- 
 brations superimposed on those vibrations, these over- 
 vibrations, these ripples on the large waves, often occur- 
 ring at the rate of tens of thousands per second. Imagine 
 a mechanism made by human hands capable of doing this ! 
 
THE SPEAKING TELEPHONE. 
 
 285 
 
 Reis may be said to have exposed the tremendous ob- 
 stacles which lay in the path of any one who should attempt 
 to carry into practice Bourseul's theory ; and for this he is 
 entitled to lasting credit. Knowing what obstacles there 
 are, is next best to knowing how to surmount them. But 
 the first does not involve invention ; the second does. 
 
 Reis began by carving a model of a human ear out of a 
 piece of oak. Figs. 116 and 117 
 
 show it in 
 
 and section. 
 
 Fig. 116. 
 
 Fig. 117. 
 
 Through this he made a hole which he closed by a piece of 
 thin membrane at b (Fig. 117), to imitate the drum of the 
 natural ear. On the back he fastened a tin plate which 
 served as a support for a little lever c d, pivoted to the plate 
 at its middle, and resting at its lower end c against the 
 membrane, and its upper end d against a strip of spring- 
 metal g which was fastened by the two screws represented 
 to the under edge of the ear. The screw h was intended to 
 regulate the pressure of the spring g on the lever d. One 
 
286 THE AGE OF ELECTRICITY. 
 
 wire from the battery went to the spring g; and the cur- 
 
 Fig. 118. 
 
 rent was conducted, therefore, through that spring, through 
 the little lever c d, then to the tin supporting plate, and 
 
THE SPEAKING TELEPHONE. 
 
 287 
 
 then to the line. This is a transmitting instrument into 
 which speech is to be uttered. This instrument, in its 
 most improved form, is represented in Fig. 118 ; and it is 
 hardly necessary to point out how slight the modification 
 that was effected. Instead of the carved ear, there is a 
 tube a, closed as before with a membrane b. On the tube 
 is a support e, which carries a little pivoted lever c as 
 before, one end resting against the membrane, the other 
 against a spring d which can be adjusted to the lever. 
 The current goes from the battery to the spring, so to 
 
 Fig. 119. 
 
 the lever, to the metal tube and its support, and so to 
 line. 
 
 Reis' last form of transmitter is represented in Fig. 119. 
 It is simply a box A, into the side of which passes a 
 speaking-tube. In the lid of the box is a round hole, in 
 which is arranged as before a membrane diaphragm. On 
 this diaphragm is fastened a flat bit of platinum, which 
 is electrically connected to a binding-post by a strip of 
 copper. Above the platinum rests a point of the same 
 metal, which was fastened at the apex of a loose angular 
 piece of metal. The angle piece is supported at the end of 
 
288 THE AGE OF ELECTRICITY. 
 
 one leg b by a sort of pivot ; and at the end of its other leg 
 a it has a point dipping into a little cup of mercury. This 
 mercury cup is connected by a wire to the binding-screw 
 /, in the engraving, so that the current from the battery 
 might be said to enter at the screw /, thence go to the 
 little tripod or angle piece ; and as the point at the apex 
 of this rests by gravity simply on the scrap of platinum 
 fastened on the diaphragm, the current proceeds to the 
 platinum, and so by the copper strip to the screw d, 
 hence to line. 
 
 Reis made two receiving instruments, one of which is 
 shown in Fig. 119 in connection with the transmitter just 
 described. It is simply and purely Page's needle, which 
 is seen passing through two supports, surrounded by its 
 coil, and resting on a sounding-box. Reis' other receiver, 
 which he abandoned in favor of the needle instrument, is 
 represented in Fig. 118. It was modified from a telegraph- 
 sounder ; m m being the usual electro-magnets, before 
 which was suspended an armature *', loosely hung in a 
 standard &, and provided with adjusting screws / and o. 
 The current passed through the magnet coils in the usual 
 way. 
 
 The reader has now before him substantially all that 
 Reis did. The instruments represented in Fig. 119 were 
 those manufactured for the market, and they found their 
 way to the United States. They were exhibited in New 
 York in 1869, 1870, and 1871. 
 
 But how do these instruments work? And how, if at 
 all, do they transmit speech? And, if they transmit 
 speech, why did the world not have the speaking tele- 
 phone twelve or fifteen years earlier than it did? It has 
 cost already several hundred thousand dollars just to talk 
 about those questions, and the end of the expense is not 
 yet in this country, at least. However existing contro- 
 
THE SPEAKING TELEPHONE. 289 
 
 versies may be decided, three irreconcilable views of Reis' 
 instruments will always be taken ; and these are : 
 
 First, That Reis merely combined Bourseul's contact- 
 breaking disk and wire with Page's singing needle ; using 
 the voice to make the disk vibrate, and so make and 
 break the circuit correspondingly with the frequency of 
 the vibrations. This doctrine denies the possibility of 
 Reis' apparatus ever having transmitted speech, or ever 
 having been able to do so, because an electrical current now 
 interrupted and now established must during the periods 
 of interruption cease altogether. Hence the necessary 
 vibrations are constantly being dropped out, and can never 
 be reproduced at the receiver, because never existing on 
 the line ; while those .that do affect the current simply 
 cause the needle to sing in its own voice, depending, as 
 we have already explained, upon the rapidity or frequency 
 of the closing of the circuit. 
 
 Second, That Reis' instruments, even if they do make 
 and break the circuit in the manner described, will never- 
 theless transmit speech by virtue of the making and break- 
 ing. This is absurd ; and although it has been gravely 
 advanced, and innumerable specious contrivances devised 
 to establish its truth, all that these show is that speech 
 can be transmitted through certain things different from 
 Reis' apparatus even despite occasional interruptions in 
 the circuit, just as an occasional pressure on the wind- 
 pipe may stop speech from time to time, and yet the 
 speaker manage to make himself understood. 
 
 Third, That Reis' contact points above noted never 
 broke circuit at all, but were always held together by the 
 weight of the superimposed angle piece in Fig. 119, or 
 the spring in Fig. 118. When this is the case, Reis'ttrans- 
 mitter if carefully used will transmit spoken words. 
 
 If Reis' transmitter was not capable of transmitting 
 
290 THE AGE OF ELECTRICITY. 
 
 speech, it is of course immaterial whether his receiver 
 could reproduce speech or not. He never could have 
 known whether it was or was not operative for the pur- 
 pose. If, however, Reis' transmitter could and did trans- 
 mit speech, then it is very important to know whether his 
 receiving instrument would reproduce speech, for a like 
 reason. It will suffice here to say, that, with a fully 
 operative transmitter, either of Reis' receivers can be 
 made to reproduce the speech sent. 
 
 At the time that this work is written (1886), a contest 
 of unexampled bitterness, into which even the Government 
 of the United States has been drawn as a party, rages 
 over the question who invented the arc of transmitting 
 articulate speech by electricity, and the speaking tele- 
 phone. It is scarcely possible to make even the simplest 
 statements without risking acrimonious contradiction from 
 some quarter or other : even to doubt, is often to invite 
 instant condemnation. In the recital which follows, it 
 has been the endeavor to state facts, without partisan 
 color. 
 
 The multiple harmonic telegraph of Mr. Elisha Gray, 
 which has already been described in the chapter on teleg- 
 raphy, was widely exhibited throughout the United States 
 in the years 1875 and early in 1876, under the name of 
 the " telephone." During this period, and for some time 
 before, Mr. Gray had been studying the problem of articu- 
 late transmission. It is alleged, that, as early as 1874, 
 he invented an apparatus which is a complete speaking 
 telephone ; but it appears that he did not construct it, nor 
 in any wise test it, until some years afterwards. At the 
 time Gray was lecturing upon his harmonic telegraph, 
 or musical telephone, as it was then commonly called, 
 and prosecuting his other researches, Mr. Alexander 
 Graham Bell, then a teacher of a system of visible speech 
 
THE SPEAKING TELEPHONE. 
 
 291 
 
 to the deaf and dumb in a public institution in Boston, 
 was likewise at work upon telegraphic inventions. Foi 
 several years, beginning in 1870, Mr. Bell was studying 
 multiple telegraphic transmission by musical tones. He 
 devised various forms of apparatus for that purpose, and, 
 among other things, a receiving instrument which is rep- 
 resented in Fig. 120. This consists simply of an electro- 
 magnet placed vertically, over the poles of which extends 
 a thin bar of steel clamped to a support. This con- 
 trivance was contrived for use with a device for mechani- 
 cally interrupting the current, the latter consisting in a 
 steel reed kept in continuous vibration by an electro- 
 magnet and a local 
 battery. The reed in 
 vibrating made and 
 broke the current to 
 the line ; and this cur- 
 rent, passing to the 
 electro-magnet in the 
 receiving apparatus, 
 caused that magnet to attract 
 steel bar before it. If 
 
 Fig. 120. 
 
 and release the elastic 
 the normal rate of vibration of 
 the transmitting reed was the same as that of the re- 
 ceiving reed, then the latter would vibrate strongly, and 
 yield a note of the same pitch as that of the transmitting 
 reed ; but if the normal rates of vibration of the two reeds 
 were different, then the receiver would keep silent. The 
 principle of this is fully explained on page 238, in refer- 
 ence to Gray's harmonic telegraph. 
 
 During 1874 Mr. Bell did a great deal of thinking about 
 transmitting speech by electricity, and a little work on his 
 harmonic telegraph ; and this state of affairs continued 
 until the summer of 1875. On the second day of June 
 of that year, w r hile experimenting with his multiple tele- 
 
292 THE AGE OF ELECTRICITY. 
 
 graph apparatus, Mr. Bell made an accidental discovery 
 which, he says, " convinced me in a moment that the 
 speaking telephone I had devised in the summer of 1874 
 would if constructed prove a practically operative instru- 
 ment." The Italics are ours. Mr. Bell had arranged in 
 his workshop three experimental telegraph-stations, at one 
 of which were several of his circuit-breaking transmitting 
 reeds, and at each of the others an equal number of re- 
 ceivers, of the form represented in Fig. 120. Thus there 
 were three transmitters tuned to notes of different pitch, 
 as A, B, and C, at one station ; and at each of the other 
 stations, three receivers tuned to the same notes, A, B, C. 
 When transmitter A was in operation, only the reeds A 
 at the two distant stations should respond ; and so, for 
 transmitters B and C, only the reeds B and C should 
 correspondingly vibrate. While the experiment was in 
 progress, Mr. Bell's assistant, Mr. Watson, finding that 
 one of the reeds of the receivers at the station where he 
 was located adhered to the pole of the magnet, forcibly 
 plucked it away. At the same moment Mr. Bell, at the 
 other receiving station, noticed a motion in the reed of 
 the receiver, which corresponded to the receiver whose 
 reed had been plucked. "At all events," he says, "the 
 reed of the receiver at station 2 vibrated at a time when 
 no vibration was expected, so that the fact of its vibra- 
 tion immediately attracted my attention. I therefore kept 
 Mr. Watson plucking the reed at station 3 while I made 
 various changes at stations 1 and 2. These changes 
 proved that the vibration I had observed had indeed been 
 caused by the plucking of the reed at station 3, even when 
 there was no battery upon the circuit at the time. To 
 make the matter perfectly sure, we separated the receivers 
 B of stations 2 and 3, and connected them upon a circuit 
 by themselves, as shown in Fig. 5 of my March 7, 187G, 
 
THE SPEAKING TELEPHONE. 
 
 293 
 
 patent, but without any battery in the circuit. [The figure 
 here referred to by Professor Bell is represented in Fig. 
 121. EE are the two receivers, each having an electro- 
 magnet, in front of the pole of which is arranged a spring 
 armature or reed A. The reed is fastened at one end at 
 h.~\ Upon plucking the reed of one of the receivers, the 
 reed of the other was thrown into very considerable vibra- 
 tion. The vibrations produced by the plucking were still 
 more intense when a battery was included in the circuit. A 
 number of experiments were made to prove that the con- 
 siderable amplitude of movement noticed was not caused by 
 any vibrations mechanically conducted along the wire frorj 
 one instrument to the other, but that the vibration of tha 
 
 one receiving reed was due to electrical undulations caused 
 by the vibration of the other receiving reed. The discovery 
 therefore that was made on the 2d of June, 1875, teas that 
 the vibrations caused in the armature of a receiving instru- 
 ment, by electrical undulations occasioned by the vibration 
 of the armature of another instrument in the same circuit 
 as the first, would be of very considerable force. As I have 
 already explained, I had had the idea since the summer 
 of 1874, that vibrations produced in this way would be of 
 very slight amplitude, and that they might not prove suffi- 
 ciently violent to produce audible effects that would prove 
 practically useful either for the purpose of the reproduc- 
 tion of articulate speech, or for the purposes of multiple 
 telegraphy. The experiments described above convinced 
 
294 THE AGE OF ELECTRICITY. 
 
 me that this was a mistake. The vibrations produced in 
 tuned reeds were so great in amplitude that I felt sure 
 that they were even sufficiently great to be mechanically 
 utilized in any system of multiple telegraphy. Even when 
 the reeds of the two instruments connected in circuit (Fig. 
 124), (but without a battery), were not in tune with one 
 another, that is, did not have the same normal rate of 
 vibration, the feeble forced vibrations electrically pro- 
 duced in the one by the mechanical plucking of the other, 
 though barely sufficient to produce a visible motion, were 
 quite sufficient to cause a very perceptible sound." 
 
 The reader has now before him Mr. Bell's own descrip- 
 tion, not exactly of how he invented the speaking tele- 
 phone, but how he became convinced that a speaking 
 telephone which he had in his mind would prove " a prac- 
 tically operative instrument." 
 
 So far he had simply observed that the current produced 
 in the coil of an electro-magnet, by vibrating an armature 
 in front of the pole of that electro-magnet, was stronger 
 than he had believed ; that is, it was strong enough, after 
 passing over a telegraph-line, to set another armature, in 
 front of another electro-magnet, vibrating audibly. 
 
 Mr. Bell's next step was to try whether he could move 
 the armature the reed of the sending instrument by 
 the air-waves produced by the voice, instead of mechani- 
 cally by the finger. Just as Reis had done before him, 
 and the inventor of the phon autograph before Reis, he 
 made a hollow tube, and covered one end with a piece of 
 membrane. He fastened his vibrating reed to the centre 
 of that membrane. The apparatus as Mr. Bell says he 
 made it is represented in Fig. 122. The electro-magnet is 
 placed above the membrane diaphragm ; the armature fas- 
 tened to the centre of the membrane. In order to leave 
 the armature free to follow the membrane, the former was 
 
THE SPEAKING TELEPHONE. 
 
 295 
 
 hinged to its support. Mr. Bell supposed that when some 
 one talked to the diaphragm of this instrument, the magnet 
 being connected to a line of wire, another person listening 
 at a similar instrument also connected to the line would 
 hear what was said. Unfortunately, when he caused the 
 instruments to be made, they would not operate. He says 
 he " knew from theory that the articulation was there ; " 
 but there is obviously a wide difference between knowing 
 of the presence of a thing by theory, and producing it. 
 
 This was the condition of affairs when Professor Bell 
 obtained his celebrated 
 patent which has since 
 been judicially con- 
 strued to cover the 
 whole art of transmit- 
 ting speech by electri- 
 city. Like Reis, he had 
 formulated theories in 
 his own mind, and had 
 made apparatus which 
 he hoped would practi- 
 cally realize them. But 
 neither Reis so far as the world knew, nor Bell so far as 
 he knew, had ever successfully transmitted one word by 
 electricity, at the respective times when death ended the 
 labors of the one, and when the monopoly of a great 
 public need fell into the hands of the other. 
 
 By the summer of 1876 Mr. Bell had considerably 
 modified the form of his apparatus ; and at the Centennial 
 Exposition he exhibited it before various distinguished 
 persons, and succeeded in transmitting a few simple and 
 easily recognizable words and phrases. 
 
 During the following year Mr. Bell applied himself 
 assiduously to the improvement of his apparatus, and 
 
 Fig. 122. 
 
296 
 
 THE AGE OF ELECTRICITY. 
 
 finally by June, 1877, brought it to the familiar form in 
 which it has remained ever since. Our engraving (Fig. 
 123) shows it split in two lengthwise. The outer casing is 
 of hard rubber. Through the middle runs a bar magnet, 
 on the end of which is the wire coil. The ends of the coil 
 
 Fig. 123. 
 
 are connected by wires running through the case to two 
 binding-posts, to which the circuit connections are fas- 
 tened. Between the cover and case proper is clamped the 
 diaphragm of thin sheet-iron which is disposed as close to 
 the end of the magnet as possible without touching it. 
 
 fig. 124. 
 
 Finally, in the cover there is a recess which serves to con- 
 verge the sounds uttered into the instrument toward the 
 central sound aperture. This is known as a magneto 
 telephone, and may be used both as a transmitter and 
 a receiver, that is, it may be employed at both ends of a 
 line as shown in Fig. 124, which is simply a diagram of the 
 
THE SPEAKING TELEPHONE. 297 
 
 important parts ; A and B being two permanent magnets, 
 C and D being diaphragms respectively in front of each, 
 and E and F being the coils. One end of each coil may 
 be connected to ground, and the other ends connected to 
 line. When permanent magnets are used, the transmitting 
 instrument produces its own current : when a battery is 
 placed in circuit, the telephone current is, as already 
 stated, superposed on the main current. The first tel- 
 ephone lines commercially employed had magneto tele- 
 phones for both transmitters and receivers, but at the 
 present time in this country the magneto telephone is used 
 solely as a receiver. 
 
 It is a matter of history, that Mr. Bell has been the 
 recipient of great honors, not merely as the inventor of 
 the electric speaking telephone, but of the art of teleph- 
 ony, of transmitting and receiving articulate speech 
 by the aid of the electrical current. And it is also well 
 known, that, under Mr. Bell's earliest patent bearing date 
 March 7, 1876, a gigantic corporation has asserted an in- 
 flexible control in the United States over every telephone 
 line. This control mainly is based on the famous fifth 
 claim of Mr. Bell's patent, which is as follows : 
 
 "The method and apparatus for transmitting vocal or 
 other sounds telegraphically, as herein described, by caus- 
 ing electrical undulations similar in form to the vibrations 
 of the air accompanying the said vocal or other sounds, 
 substantially as set forth." 
 
 We have already alluded incidentally to the undulatory 
 current in contradistinction to the intermittent or inter- 
 rupted current. The so-called undulatory-current theory 
 is that which is most commonly accepted to explain the 
 action of the telephone. It involves the idea that only 
 an unbroken current, variable in strength, can be modified 
 by all the characteristics of a sound-wave ; that such a 
 
298 
 
 THE AGE OF ELECTRICITY. 
 
 current will be undulatory in form, and that its undula- 
 tions will copy or correspond to all the undulations of the 
 sound-waves affecting the transmitting telephone, however 
 minute, and, after passing over a wire, will cause in the 
 receiving instrument the reproduction of the original 
 sounds in all their characteristics. This is substantially 
 the undulatory-current theory. 
 
 There are two principal ways in which an electric cur- 
 rent is subjected to the influence of the voice. One, we 
 have already seen, involves an armature in the form of a 
 thin plate, which is vibrated by the sound-waves due to 
 
 Fig. 125. 
 
 speech in front of the pole of an electro-magnet, as rep- 
 resented in Fig. 124. The other method depends simply 
 on interposing in a closed circuit, two pieces of conducting 
 material in loose but constant contact as represented in 
 Fig. 125. One of these pieces, A, may be attached to the 
 plate vibrated by the speaker's voice, and the other piece, 
 B, may be held in constant contact with the first by a 
 spring, for example. The battery current passes from 
 one piece to the other, then to the line, and to a magneto 
 receiving instrument. When speech is uttered before the 
 diaphragm, the vibrations of the plate communicate them- 
 selves to the loose joint, and create variations in the re- 
 sistance offered by this joint to the current. The result 
 
THE SPEAKING TELEPHONE. 299 
 
 is, that the current is modified by the diaphragm vibrations, 
 just as it is when the diaphragm is moved before the pole 
 of a magnet ; only, in the one case a current already flow- 
 ing is more or less diminished in strength, and in the other 
 it is more or less increased in strength. To illustrate : 
 Suppose there is attached to a bucket of water a flexible 
 pipe, as in Fig. 126, through which the water can freely 
 flow. Then, by compressing the pipe in the hand, the 
 escape of the water can be more or less prevented, while 
 some flow always continues. The contact pieces -4, /?, 
 in Fig. 125, when governed by the diaphragm, act like the 
 hand in Fig. 126. Again, suppose the case of a railway- 
 train, which can be made to move faster while constantly 
 
 Fig. 126. 
 
 running, by turning on more or less steam to the engine : 
 that represents the conditions of the magneto telephone. 
 So also, while running at a given speed, the train can be 
 more or less checked by the brakes ; that represents the 
 conditions of the resistance telephone. In both cases, the 
 train keeps on moving, but its speed is varied. 
 
 The reader will doubtless notice at once the similarity 
 between the resistance form of telephone represented in 
 Fig. 125, and Reis' transmitter represented in Fig. 118. 
 The whole controversy as to Reis hinges simply on the 
 question whether Reis did or did not maintain his loose 
 contact pieces in constant contact. If he did, he had a 
 resistance telephone, using an unbroken current, which 
 will transmit speech : if he did not, he had simply a , 
 
300 THE AGE OF ELECTRICITY. 
 
 circuit-breaker, causing a broken current, which will not 
 transmit speech. 
 
 Leaving the Reis question aside, however, it is a singu- 
 lar fact, that the first articulate speech obtained by Mr. 
 Bell was transmitted not only after his patent had been 
 obtained, but with an apparatus which Mr. Bell had never 
 before made, or even described so that any one else could 
 make it. In fact, the first words sent by Mr. Bell were 
 not transmitted by the magneto telephone at all, but by a 
 very imperfect form of resistance instrument, the con- 
 struction of which was first described, not by Mr. Bell, 
 but by Mr. Elisha Gray. It consisted of a membrane 
 vibrated by the voice, and carrying a wire which dipped 
 in water. A battery current was conducted to the water, 
 passed to the wire, and so to the line. When the mem- 
 brane was vibrated, it moved the wire up and down in the 
 water, and so altered the length of the non-submerged 
 portion of the wire, thus varying its resistance to the 
 passage of the current. For practical purposes this ap- 
 paratus is of no value, but it will always be of great 
 historical interest for the reasons above stated. 
 
 In May, 1878, Professor D. A. Hughes announced his 
 discovery of the microphone, so called because it rendered 
 audible very minute sounds ; and this discovery was, that, 
 if two pieces of conducting material be supported in very 
 delicate contact, then the resistance offered by the joint 
 to a current passing through it will be modified by very 
 faint sounds, and the current, correspondingly affected, 
 caused to reproduce them in a receiving telephone. This 
 is of course the principle of the resistance telephone, 
 which, in fact, is now commonly known as the microphone. 
 Hughes made his microphone in the form represented in 
 Fig. 128, in which A is a stick of hard carbon pointed at 
 its ends, and held between two supports of like material 
 
THE SPEAKING TELEPHONE. 
 
 301 
 
 projecting from an upright board. The battery current 
 was led, as indicated by the wires, to one support through 
 the carbon, and out through the other support ; and a re- 
 ceiving telephone was connected in the circuit. A great 
 many stories about hearing flies' footsteps, etc., were 
 published when this apparatus first appeared, which were 
 more fantastic than accurate. It is true that some faint 
 sounds can at times be recognized ; but as a general rule, 
 true of all over-delicate microphonic contacts, the breaks 
 
 Fig. 127. 
 
 in continuity of the circuit caused by vibrations being 
 strong enough to actually separate the parts of the loose 
 joint, result simply in explosive cracks and snaps in the 
 receiver, which practically obliterate all other sounds. In 
 the resistance telephone, the transmitter of the present 
 day, the chief problem has always been the devising of 
 mechanical means of holding the contact pieces together 
 so delicately that they will be under control of the minut- 
 est speech vibrations, and yet not so lightly that the 
 grosser vibrations as when words are loudly spoken 
 can throw them apart. 
 
302 THE AGE OF ELECTRICITY. 
 
 Shortly after the announcement by Hughes of his 
 microphone, Mr. T. A. Edison laid claim to the discov- 
 ery, asserting that he had some time prior found out that 
 "semi-conductors" whatever they may be, including 
 carbon, however vary their resistance with pressure. 
 Mr. Edison at various times has contrived telephones in 
 which a block of carbon, for example, is pressed against 
 a diaphragm. It has been conclusively demonstrated by 
 many investigators, that the pressure, greater or less, on 
 carbon, has nothing to do with variations of resistance 
 offered by that material to a current. Mr. Edison's 
 instruments for a short time were commercially used in 
 this country. 
 
 Of the various claimants to the invention of the tele- 
 phone, none has presented a more remarkable history 
 than Daniel Drawbaugh. Mr. Drawbaugh is one of 
 those universal geniuses capable of turning his hand to 
 any mechanical work, and of doing it well. He has 
 always resided in an out-of-the-way little hamlet called 
 Eberly's Mills, near Harrisburg, Penn. As an electri- 
 cian, he is self taught. Between the years 18G7 and 
 1876, he claims to have invented and actually used 
 every type of telephone now known. He began with a 
 transmitter made out of a jelly- tumbler, in which he used 
 powdered carbon to vary the resistance correspondingly 
 to the motion of a diaphragm vibrated by the voice ; and 
 a receiver contrived from a mustard-can, but in other 
 respects nearly identical with the first telephones made 
 by Professor Bell. From these devices as starting-points, 
 onward, he has constructed a series of telephones, more 
 and more specialized in construction, until finally the 
 instruments which he claims to have had at the time 
 when Professor Bell made his earliest experiments ap- 
 proach closely in efficiency to the best forms of the pres- 
 
THE SPEAKING TELEPHONE. 303 
 
 ent day. Mr. Drawbaugh has produced a large number 
 of his telephones, and many witnesses to prove that he 
 had them at the times he fixes. His claims are at this 
 writing before the courts for adjudication. If they are 
 ultimately sustained, there can be no question but that 
 Mr. Drawbaugh's position as an electrical discoverer will 
 be wholly unrivalled. Within the last four years, he has 
 invented over thirty new telephones. 
 
 At the date of this work (1886) , over a thousand patents 
 in the United States alone have been granted for various 
 forms of telephones, and devices thereunto appertaining. 
 The great majority of instruments differ merely in unes- 
 sential details. With the resistance transmitters, changes 
 on means for holding the two contact pieces together have 
 been rung to such an extent that it seems that every con- 
 ceivable contrivance for the purpose must have been sug- 
 gested. Magneto telephones are not used commercially 
 as transmitters ; for the modifications they produce in the 
 current are feeble compared with those caused by the 
 resistance instrument. They are, however, commonly 
 employed as receivers ; and, as has been already stated, 
 the form which they now have has undergone no material 
 change for some nine years. An immense amount of 
 ingenuity has also been expended in devising telephone 
 circuits and systems so as to allow of intercommunication 
 between exchanges and subscribers. 
 
 The form of transmitting telephone in common use 
 throughout the United States is that known as the Blake 
 transmitter, a sectional view of which is given in Fig. 
 128. The contact pieces are here a platinum point which 
 is supported on a light spring c, and a button of carbon, 
 7i, held in a heavy mass or anvil e, which is supported by 
 a spring d. Both springs c and d are held in a plate F, 
 which is itself sustained by a spring plate g upon a bracket 
 
304 
 
 THE AGE OF ELECTRICITY. 
 
 B'. The platinum point rests against the diaphragm, and 
 also against the carbon button ; these parts being held in 
 light contact by the several springs. On the lower part 
 of the plate F is an inclined plane against which bears 
 the point of an adjusting-screw G. The current from the 
 
 battery is conducted 
 through the primary wire 
 of the induction coil /, 
 thence through the con- 
 tact pieces, and so back 
 to battery. The second- 
 ary wire of the induction 
 coil communicates with 
 the line. The Blake 
 transmitter is by no 
 means the best, or even 
 one of the best, of the 
 carbon transmitters. 
 
 Various forms of trans- 
 mitters have been devised, 
 in which springs for hold- 
 ing the carbon contact 
 pieces together are omit- 
 ted, and the action of 
 gravity substituted. One 
 of the simplest instru- 
 ments of this kind was 
 devised by Mr. Daniel 
 Drawbaugh in 1881, and 
 is illustrated in Fig. 129. To the rear side of a diaphragm 
 A is attached a little prism B of hard carbon ; and a simi- 
 lar prism C is secured to the back-board of the instrument. 
 These prisms do not touch each other, but resting upon 
 their inclined faces is a cylinder />, also of carbon. The 
 
 Fig. 128. 
 
THE SPEAKING TELEPHONE. 
 
 305 
 
 battery current passes through the three pieces of carbon, 
 which remain always in proper adjustment simply by the 
 weight of the carbon cylinder. This instrument has been 
 adopted by the United States Signal Service, and has been 
 officially pronounced of special efficiency 
 for military purposes in the field, etc. 
 
 For producing loud sounds in the re- 
 ceiving instrument, the transmitters which 
 use blocks or buttons of carbon are far 
 inferior to those employing carbon in 
 comminuted form. The usual construc- 
 tion of these instruments is represented 
 in Fig. 130, in which A is a diaphragm 
 of metal, B a fixed plate of metal, and 
 C a mass of pulverized coke placed 
 between the two. The current passes 
 from the diaphragm through the coke, to the back plate, 
 and so out. This telephone operates by reason of the 
 immense number of contacts occurring between 
 the particles of carbon. It is necessary simply 
 to cause the air-vibrations due to the voice to jar 
 or shake the mass. Fig. 131 represents a pulver- 
 ized-carbon transmitter constructed by the author, 
 in its full working size. It consists simply of a 
 cylindrical box of hard rubber, lined within with 
 a ring of brass, A, to 
 which one of the con- 
 ducting wires is fast- 
 ened. A disk of brass 
 
 fig. 129. 
 
 Fig, 130. 
 
 Fig. 131. 
 
 B is firmly attached to 
 one of the inner faces, so as not to touch the ring A. The 
 space in the box is loosely filled with comminuted coke, 
 and then the cover is permanently fastened in place. In 
 external appearance the instrument is nothing but a button 
 
306 THE AGE OF ELECTRICITY. 
 
 from which the connecting wires extend. This contrivance 
 transmits speech clearly when held in the fingers close 
 to the mouth. Just why conducting bodies in loose but 
 constant contact will cause a variation in the resistance 
 to, and so render an electrical current capable of copying, 
 speech vibrations, is not definitely known. Any pieces 
 of conducting material will so operate, even silver, the 
 best of electrical conductors. The results, however, are 
 much better when the contact pieces are of carbon, or 
 other material of comparatively low conductivity. It ap- 
 pears probable that the true cause of the effect is varia- 
 tions in the iufinitesimally thin air film existing between 
 the parts of the joint. 
 
 With all telephone transmitters, at the present time, 
 induction coils are used ; the contact pieces and battery 
 being connected in the primary circuit, and the secondary 
 wire of the coil to line. The principal object is to increase 
 the electro-motive force of the modified current so that it 
 may overcome the resistance due to long lines, and thus 
 enable speech to be transmitted over greater distances 
 than if the direct battery current were used. 
 
 As we have stated, the ingenuity of telephone inventors 
 has chiefly been directed to the production of new forms 
 of transmitters ; and some of these are remarkable as sci- 
 entific curiosities. Professor Blake has transmitted speech 
 by the earth's magnetism, by arranging a diaphragm before 
 a rod of soft iron, the latter being held in the position of 
 the dipping needle, and thus becoming a magnet by induc- 
 tion from the earth. Mr. Bell has devised a telephone in 
 which the vibrations of the diaphragm produce a rubbing 
 contact between pieces of glass and silk, so that, as he 
 claims, the instrument "maybe made to transmit artic- 
 ulate speech by means of frictional electricity generated 
 by the voice itself." Another curious transmitter devised 
 
THE SPEAKING TELEPHONE. 307 
 
 by Mr. Bell consists of a toy balloon about six inches in 
 diameter, made of thin rubber and coated with plumbago. 
 This is held between two fixed plates, and the current 
 passes over the conducting envelope. The expansion and 
 contraction of the body of confined air in the balloon is 
 said to modify the resistance of the plumbago coating. 
 Neither of the above instruments is of much practical 
 utility. 
 
 The great majority of telephone transmitters vary sim- 
 ply in the arrangement of their contact pieces. In some, 
 multiple contacts are used, ranging from two or more 
 pairs of carbons held together by springs, and all gov- 
 erned by the same diaphragm, up to a dozen or more 
 pairs. The carbons in some instruments are held together 
 by gravity, and in others by hydraulic pressure. In some 
 forms of apparatus, the carbon is pulverized : in others it 
 takes the shape of balls like shot. 
 
 In telephone receivers, but little change has been 
 effected since they have come into public use. In lieu of 
 one magnet, several are sometimes employed. The metal 
 diaphragm which forms the armature is in many forms 
 polarized by a metallic connection with the magnet. The 
 only part in the telephone receiver absolutely necessary to 
 the reproduction of the sound is the coil. The diaphragm 
 may be omitted, and sound will be heard from both coil 
 and magnet. If the magnet is left out, the coil alone will 
 speak, though the sound in such case will be much weaker. 
 A simple platinum wire .001 inch in diameter and six 
 inches long, stretched between a pillar and a diaphragm, 
 will expand and contract under the influence of the cur- 
 rent, and so reproduce speech. 
 
 Mr. Edison has invented .a so-called electro-chemical 
 telephone-receiver, in which there is a cylinder composed 
 mainly of chalk, against which rests a platinum strip 
 
308 
 
 THE AGE OF ELECTRICITY. 
 
 which is also secured to a diaphragm. The circuit passes 
 through cylinder and strip, and the cylinder is rotated at 
 uniform speed. The friction between cylinder and strip 
 causes the diaphragm to be drawn inward, that is, to- 
 ward the cylinder, so that the diaphragm is thus brought 
 to a certain position. When a current passes through the 
 instrument, the friction of strip and cylinder is reduced, 
 and the diaphragm flies back by its own elasticity. As 
 the variation in friction corresponds to the variations in 
 the strength of the current coming to the instrument, the 
 
 diaphragm is thus caused to 
 vibrate so as to reproduce 
 speech sent from the other 
 end of a line. This appara- 
 tus produces loud sounds, but 
 has not come into any practi- 
 cal use. 
 
 One of the most ingenious 
 of the telephones is Professor 
 Dolbear's condenser receiver, 
 which is represented in Fig. 
 132. This consists simply of 
 two metallic disks (7, Z), sup- 
 ported in the case of the instrument so as to be very close 
 together, but not in contact. One disk is pressed upon 
 by a screw at its middle, and is thus prevented from 
 vibrating ; the other is free to vibrate. One of these 
 disks is connected to line, the other to earth. The line 
 wire at the transmitting end is connected to the secondary 
 wire of an induction coil, in the primary circuit of which a 
 transmitter is included. As the varying currents flow into 
 and out of this condenser, the two disks attract one another 
 more or less strongly ; and thereby vibrations are set up 
 which correspond to the vibrations of the original sounds. 
 
 Fig. 132. 
 
THE SPEAKING TELEPHONE. 309 
 
 There is no instrument which employs such delicate 
 forces, performs such intricate motions, or requires greater 
 accuracy in construction, than the telephone. The total 
 path of the vibrating air-particle is perhaps one millionth of 
 an inch ; its period (half vibration) is as short as J T of a 
 second in many instances. Within this small limit of time 
 and space, lie packed all the variations which distinguish 
 from each other all words of all languages. The minute- 
 ness of these distinctions escapes computation and state- 
 ment ; and yet the telephone acts by taking note of them 
 and reproducing them. The electrical force available in 
 the magneto instruments has been reckoned at x^oVu^ f 
 that due to a single cell of battery ; and it is variations 
 of more or less within this maximum limit which give rise 
 to the speech heard at the receiver. 
 
 It has been estimated that currents of a ten-millionth 
 of an ampere will give audible sounds. With delicately 
 adjusted transmitters, especially those using pulverized 
 carbon, it is not at all necessary to place the instrument 
 near the mouth in speaking. It may simply be placed 
 against some part of the body, preferably near the chest. 
 With the little button transmitter above described, speech 
 can be transmitted clearly when the instrument is pressed 
 against the head, the throat, and the chest. The best 
 results are obtained when the apparatus is placed directly 
 over the breast- bone. 
 
 Wherever a conductor carrying a current is in proximity 
 to another conductor forming a closed circuit, the current 
 in the first conductor induces a current moving in opposite 
 direction in the second conductor. These induced cur- 
 rents are often produced upon telephone lines by telegraph 
 currents in neighboring wires, or stray currents in the air 
 or earth ; and the result is that the telephone current may 
 be so retarded or modified that it no longer represents 
 
310 THE AGE OF ELECTRICITY. 
 
 the speech vibrations imposed upon it. A great many 
 devices have been suggested to get rid of this induction. 
 A return metallic conductor double wire has been 
 found the most efficacious so long as the insulation is 
 good ; but the expense of two wires on each circuit ren- 
 ders this plan impracticable for ordinary uses. Cables 
 have been suggested, provided with envelopes of metal 
 connected to earth for the purpose of leading to ground 
 the currents induced on them ; but these contrivances 
 generally act just the opposite from that which is expected 
 of them, the ground connection apparently leading currents 
 from earth to the line instead of the reverse direction. 
 "Wherever a telephone-line approximates a telegraph-line, 
 the Morse signals can be plainly heard in the telephone 
 receiver ; and where a Wheatstone automatic instrument 
 is at work, or, as in the case of electric-lighting wires, 
 where a dynamo is supplying the current, the roars and 
 whirs heard in the telephone completely obliterate all 
 other sounds. 
 
 The distance over which a telephone-line will receive 
 induced currents from another -conductor is astonishing. 
 In the early days of the telephone, Professor Blake, by 
 connecting a receiver to a railroad- track, heard distinctly 
 the Morse signals traversing the wires on the poles more 
 than forty feet distant. 
 
 Telephoning over submarine cables is impracticable for 
 long distances, owing to the effects of induction and retar- 
 dation. Tests on artificial lines representing the Atlantic 
 cable show that probably the maximum distance over 
 which speech can be distinguished does not exceed a hun- 
 dred and fifty miles. Conversation has, however, been 
 successfully maintained between Brussels, Belgium, and 
 Dover, England, through sixty miles of cable and two 
 hundred miles of air line. So also speech has been trans- 
 
THE SPEAKING TELEPHONE. 311 
 
 mitted between Holyhead find Dublin. In every sub- 
 marine cable, before a signal can be made at the receiving 
 end, the whole cable must be charged up with electricity ; 
 and if there be not sufficient electricity sent in for this 
 purpose, practically no signal appears at the distant end. 
 With telephone currents on long cables, the whole of the 
 electricity is, as it were, swallowed up ; that is, none ap- 
 pears at the distant end, or, if it does appear, it is rolled 
 up in one continuous wave, bereft of those rapid variations 
 that reproduce sonorous vibrations. 
 
 A telephone circuit when in connection with the earth 
 gives distinct evidence of every visible flash of lightning, 
 however far off the thunder-storm may be. No difference 
 in time has been observed between seeing the flash and 
 hearing the sound. If the instrument be connected to the 
 gas and water systems of a house, distinct evidence of 
 the flash can be heard, and even cracklings attributed to 
 an aurora have been distinguished in this way. Earth- 
 currents those which naturally flow in the earth's crust 
 can often be clearly recognized. 
 
 Professor Bell has proposed to utilize the inductive in- 
 fluence of one circuit upon another to enable vessels at 
 sea to communicate by telephone without the need of in- 
 tervening wires. A conducting wire, say, a mile in length, 
 is trailed over the stern of a vessel, and supplied with 
 electricity from a dynamo on board. Circuit is made from 
 the dynamo through the wire, and so back by the water. 
 It is supposed that a conductor thus arranged will induce 
 currents upon a similar conductor trailing behind the other 
 vessel, whenever the two come in inductive proximity, so 
 that speech can thus be transmitted. It is not at all 
 improbable that ultimately, through the telephone, means 
 will be found of warning vessels of the approach of other 
 ships, and the direction in which they are moving ; and 
 
312 THE AGE OF ELECTRICITY. 
 
 possibly, by some thermo-electric arrangement, the prox- 
 imity of icebergs will also be indicated. 
 
 Theoretically it is difficult to assign any distance over 
 which speech may not be telephonically transmitted. Con- 
 versation has easily been maintained through an artificial 
 resistance equal to that of a telegraph-line girdling the 
 world ; but between talking through artificial resistances, 
 and actual wires, there is a very great difference. So long 
 as the effects of induction and leakage cannot be neutral- 
 ized, the possible distance of telephoning must depend on 
 accidental conditions. Sometimes it is utterly impossible 
 to get speech over a line a few miles in length. Cases 
 have been found where a line first passing over water and 
 then over earth, or extending over rock and then gravel, 
 would refuse to transmit until taken down and carried 
 around the shore of the water-course or away from the 
 varying soil. Speech has, however, been excellently trans- 
 mitted between Chicago and New York, Washington and 
 New York, and Boston and New York, on the regular 
 telegraph-lines. 
 
 Telephoning without wires is already a possibility, and 
 promises extraordinary results in the near future. Tele- 
 phones have been fixed upon a wire passing from the 
 ground floor to the top floor of a large building, the gas- 
 pipes being used as a return, and the Morse signals sent 
 from a telegraph-office two hundred and fifty yards away 
 have been distinctly read ; in fact, if the gas and water 
 systems be used, it is impossible to exclude telegraphic 
 signals from the telephone circuit. There are several cases 
 on record of telephone circuits miles away from any tele- 
 graphic wires, but in a line with the earth terminals, pick- 
 ing up telegraphic signals. When an electric-light system 
 uses the earth, it-4s stoppage to all telephonic communica- 
 tion in its neighborhood. The whole telephonic communi- 
 
THE SPEAKING TELEPHONE. 313 
 
 cation of Manchester, England, was one day broken down 
 from this cause ; and in the city of London the effect was 
 at one time so strong as not only to destroy telephonic 
 communication, but to ring the bells. A telephone circuit 
 using the earth for return acts as a switch to the earth, 
 picking up the currents that are passing, in proportion to 
 the relative resistances of the earth and the wire. Speech 
 has been transmitted across water-courses, by the aid of 
 large metal plates wholly submerged ; the water apparently 
 closing the circuit between the plates. 
 
 Mr. Van Rysselberghe, a Belgian electrician, has suc- 
 ceeded in transmitting telegraphic and telephonic messages 
 over the same wire ; an apparently impossible feat in view 
 of the constant breaking of the circuit by the telegraph 
 instruments, tending not only to render the current inter- 
 mittent, and thus unable to receive all the sound- vibrations, 
 but also to produce in the receiving instrument loud ex- 
 plosive noises which effectually drown articulation. Mr. 
 Van Rysselberghe has succeeded in talking between Paris 
 and Brussels, over a wire nearly two hundred miles long, 
 which was used at the same time for ordinary telegraph- 
 ing. His principle is to retard the telegraphic currents, 
 so as to modify their rise and fall, by means of condensers 
 and electro- magnets. The difficulty with this plan is that 
 it retards telegraphy ; and it is doubtful whether the dis- 
 advantages due to this reason will not more than compen- 
 sate for any advantages gained by the invention. 
 
 The practical applications which have been made of the 
 telephone to various purposes are legion. One of the 
 most interesting features of the Paris Electrical Exhibition 
 of 1881 was a room fitted up with some eighty telephone 
 receivers which connected with an assemblage of micro- 
 phone transmitters arranged around the front of the stage 
 of the Grand Opera. Listeners in the receiving- room 
 
314 THE AGE OF ELECTRICITY. 
 
 could hear the music with perfect distinctness ; and as 
 each person was provided with two receivers communicat- 
 ing with transmitters placed at opposite parts of the stage, 
 by remarking the difference in loudness of the sound at 
 either ear he could thus in a measure follow the move- 
 ments of the singer about the stage. In Brooklyn, tele- 
 phone transmitters have been arranged near the pulpits 
 of several popular preachers, so that members of the 
 congregation unable to attend may listen to the sermon 
 in their own dwellings. 
 
 Two very beautiful applications of the telephone have 
 been made by Professor Hughes. These are respectively 
 
 Fig. 133. 
 
 known as the induction balance and the sonometer. The 
 induction balance is illustrated by diagram in Fig. 133. 
 The current from a small battery B, connected with a micro- 
 phone 3/, passes through two coils of wire P l P. r wound on 
 bobbins fixed on a suitable stand. Above each of these 
 primary coils are placed two secondary coils S l S 2 , of wire 
 of the same size and of exactly equal numbers of turns of 
 wire. The secondary coils are joined to a telephone T, and 
 are wound in opposite directions. The result of this arrange- 
 ment is that whenever a current either begins or stops flow- 
 ing in the primary coil P l it induces a current in /6\, and P 2 
 in /S' 2 . As t and S. 2 are wound in opposite directions, the 
 two currents thus induced in the secondary wire neutralize 
 
THE SPEAKING TELEPHONE. 315 
 
 one another ; and, if they are of equal strength, balance 
 one another so exactly that no sound is heard in the tele- 
 phone. But a perfect balance cannot be obtained unless 
 the resistances and the co-efficients of mutual induction 
 and self-induction are alike. If a flat piece of silver or 
 copper (such as a coin) be introduced between ^.and P l 
 there will be less induction in S t than in S. 2 , for part of 
 the inductive action in P l is now spent in setting up cur- 
 rents in the mass of the metal, and a sound will again be 
 heard in the telephone. But balance can be restored by 
 moving S 2 farther away from P. 2 until the induction in $ 2 
 is reduced to equality with S v when the sounds in the tele- 
 phone again cease. It is possible by this means to test 
 the relative conductivity of different metals which are 
 introduced into the coils, and even to detect a counterfeit 
 coin. The induction balance has also been applied in 
 surgery, to detect the presence of a bullet in a wound ; 
 for a lump of metal may disturb the induction when some 
 inches distant from the coils. Its first trial as a bullet 
 finder was in the case of President Garfield ; but unfortu- 
 nately the instrument then proved of little avail, as it was 
 deceived by the presence of metallic springs in the bed. 
 
 The sonometer is a special form of balance for examin- 
 ing either the loudness of sounds, or the capacity of any 
 ear for distinguishing sounds. It involves an ingenious 
 arrangement of induction coils upon a graduated rod, 
 which furnishes a scale of sensitiveness of hearing. 
 
 Dr. Boudet has succeeded in recording automatically 
 speech reproduced by a telephone receiver, by removing 
 the diaphragm and substituting a delicate armature carry- 
 ing a stylus which made tracings on smoked paper. Some 
 similarities between the sinuous lines traced have been 
 detected, but there is evidently much to be discovered 
 before we shall be able to read the telephone's writing. 
 
816 THE AGE OF ELECTRICITY. 
 
 The telephone has been used to hear the mutterings of 
 earthquakes, and of volcanoes before eruption. It has 
 served as a means of communication from earth to bal- 
 loons, and from vessel to vessel at sea. It allows watch- 
 men on the surface to listen to the operation of the pumps 
 in deep mines, and to communicate with the miners. 
 Buried in the earth, it has proven an efficient means of 
 detecting subterranean springs, the gurgle of which is 
 plainly heard. So also it has been proposed to place 
 microphones on the picket-lines of armies in the field, 
 or along, roads or around camps, to reveal the movements 
 of the enemy. It is employed to reveal the bodily sounds, 
 such as heart-murmurs and the throbbing of the pulse. 
 
 In 1873 Mr. Willoughby Smith, while experimenting 
 with the metal selenium as a means of measuring large 
 resistances to electric currents, discovered that the mate- 
 rial itself was very sensitive to the action of light, which 
 apparently manifested itself by causing changes in the 
 resistance of the selenium. One of the first practical 
 applications of this discovery was the construction, by Dr. 
 William Siemens, of a so-called artificial eye, in which a 
 selenium plate was arranged to serve as a retina, upon 
 which a lens converged the light. In front of the lens 
 were arranged two sliding screens, which answered to lids ; 
 and these were controlled by an electro-magnet in circuit 
 with the selenium, with which also a galvanometer was 
 connected. Whenever the lids were opened, the light 
 falling through the lens upon the piece of selenium caused 
 a variation in the resistance offered by the latter to the 
 electrical current passing through it, so that any changes 
 in the intensity of the light were shown by the movement 
 of the galvanometer needle. The electro-magnet, how- 
 ever, was adjusted to control the lids automatically, so 
 that, as Dr. Siemens described it, here was " an artificial 
 
THE SPEAKING TELEPHONE. 
 
 317 
 
 eye, sensitive to light and to differences in color, wtu'ch 
 gives signs of fatigue when it is submitted to the prolonged 
 action of light, which regains its strength after resting 
 with closed lids," and which closes its lids automatically 
 on the occurrence of a vivid flash. 
 
 Shortly after the telephone came into use, Mr. Smith 
 connected a piece of selenium with the instrument, and 
 then for the first time actually heard a ray of sunlight fall 
 upon the bar. Others had conceived of the same idea, 
 and were working at it ; but Professor Bell, in conjunction 
 with Mr. Sumner Tainter, was probably the first to per- 
 
 Flg. 134. 
 
 feet an apparatus to transmit speech by a ray of light, 
 and to realize what Professor Bell called " the extraordi- 
 nary sensation of hearing a beam of sunlight laugh, cough, 
 and sing, and talk with articulate words." This appara- 
 tus is called the photophone. It is operated by the voice 
 of the speaker to produce variations in a parallel beam of 
 light, corresponding to the variations in the air produced 
 by the voice. 
 
 The simplest form of apparatus consists of a plane 
 mirror of flexible material, such as silvered mica or 
 microscopic glass. Against the back of this mirror, the 
 speaker's voice is directed, a speaking-tube being used as 
 
318 THE AGE OF ELECTRICITY. 
 
 represented in the diagram, Fig. 134. In this engraving 
 B is the transmitter upon which the mirror M reflects a 
 beam of light, which passes through a lens L, and then 
 through a vessel A of alum-water, which serves to cut off 
 the heat-rays. The beam reflected from the mirror M 
 passes through a lens 72, and then travels over the inter- 
 vening space to a parabolic mirror (7, by which it is 
 reflected and concentrated upon the selenium cell 8. 
 This cell is included in circuit with a battery P and a pair 
 of telephones T T. 
 
 When speech is uttered into the speaking-tube behind 
 the transmitter, the silvered disk is alternately bulged out 
 and in, and in this way it becomes more or less concave 
 or convex ; the degree of change in its form depending 
 upon the variations in the sound. When the disk is most 
 convex, then the ray reflected from it will be most widely 
 scattered or diverged, and hence, of the whole beam, a 
 smaller proportion will be received by the mirror C. Con- 
 sequently the amount or fraction of the beam of light 
 falling upon the mirror C depends upon the curvature of 
 the disk, which in turn is governed by the speech-vibra- 
 tions. Now, the more light falls upon the mirror (7, 
 the greater the quantity converged upon the selenium, 
 and hence the greater the conductivity of this last to the 
 battery current passing through it. In fine, therefore, 
 the resistance of the selenium becomes modified, through 
 the medium of the varying light, correspondingly to the 
 sound-vibrations of speech ; the current affected by pass- 
 ing through that resistance is correspondingly modified ; 
 and hence the original sounds are reproduced in the 
 telephone. 
 
 Of course here is the transmission of articulate speech 
 without wires of any sort, and simply by the agency of a 
 beam of light. Over how great an interval this can be 
 
THE SPEAKING TELEPHONE. 319 
 
 clone, is not yet definitely determined : the longest distance 
 up to the present time is two hundred and thirty-three 
 yards. 
 
 The musical or direct photophone produces sounds from 
 intermittent beams of light. The beam is received on a 
 mirror, and by means of a lens brought to a focus upon 
 a disk pierced with numerous holes arranged in a circle. 
 The disk is rapidly rotated, from one to five or six 
 hundred times per second, and the light passing through 
 the holes, and thus rapidly interrupted, is converged by a 
 lens upon a disk of ebonite from which extends a tube 
 conveying the sounds to the ear. Disks of all substances 
 apparently vibrate under the interrupted beam, producing 
 very distinct musical sounds. By cutting off the light at 
 any moment, by an opaque screen worked by a telegraph- 
 key, Morse signals can be easily sent. Sounds have thus 
 been transmitted for distances of a mile and somewhat 
 over. 
 
 What improvements the future will bring to the speak- 
 ing telephone, can hardly be conjectured. In the way of 
 loud-talking receivers, much has already been accom- 
 plished of which the public knows little. Ordinary re- 
 ceiving telephones can be made to talk loud enough to 
 be easily heard throughout a good-sized room, and at a 
 distance of thirty or forty feet from the instrument. 
 Transmitters are already sufficiently sensitive to speech 
 to satisfy all practical needs. A good instrument should 
 easily transmit speech uttered twenty feet away from it. 
 The ordinary commercial instruments will not do this, 
 simply because they are very inferior types. The great 
 need is means for neutralizing the effects of induction, 
 leakage, retardation, and other accidental conditions inci- 
 dent to all lines. When that is accomplished, there should 
 be no more difficulty in talking between New York and 
 
320 
 
 THE AGE OF ELECTRICITY. 
 
 San Francisco than from room to room in the same 
 building. 
 
 In May, 1886, Mr. Simmer Tainter patented a curious 
 combination of phonograph and telephone, which is, in 
 fact, an electrical phonograph. The phonograph, as 
 hitherto known, is an apparatus for mechanically record- 
 ing and reproducing sounds, including spoken words. 
 Although it is very frequently described in electrical 
 works, it is not in any sense an electrical instrument. The 
 ordinary form of phonograph, as devised by Mr. T. A. 
 Edison, is represented in Fig. 135. When the cylinder A 
 is revolved on its own axis, it also moves laterally ; and, 
 
 
 Fig. 135. 
 
 while it is thus moving, the operator talks or sings into 
 the mouthpiece B, on the rear side of which is a thin 
 plate or diaphragm, which carries a needle-point. The 
 plate is thus thrown into vibration ; and the needle-point 
 is so caused to make an indented furrow spirally around a 
 sheet of soft tin-foil which smoothly envelops the cylinder. 
 Under a magnifying-glass this furrow looks like a series 
 of very minute dots ; but it is the handwriting of the 
 sound. 
 
 After the foil is indented as described, the cylinder is 
 brought back to its original position, and the needle-point 
 is placed at the beginning of the line of dots. Then the 
 
THE SPEAKING TELEPHONE. 
 
 321 
 
 cylinder is revolved as before ; but now the needle-point 
 runs over and into the elevations and depressions made in 
 the foil, and thus the thin plate carrying the point is set 
 into vibrations which reproduce the original sounds. 
 
 In some forms of mechanical 
 phonograph, in place of the 
 revolving cylinder A a rotat- 
 ing flat circular disk is used, 
 on the face of which a spiral 
 line of indentations is pro- 
 duced in the manner already 
 described. Mr. Tainter uses 
 such a disk, which he covers F ' 9 ' 136 ' 
 
 with wax in which he produces his indentations. From 
 this wax-covered disk he makes an electrotype facsimile ; 
 and then using his electrotype as a pattern to guide an 
 automatically operating cutting-tool, he reproduces all the 
 dots or indentations upon the crest 
 of a spiral ridge which is formed 
 on the face of a disk of iron or 
 other magnetic material. A por- 
 tion of the face of this iron disk 
 is shown in Fig. 136. The disk 
 thus prepared is called a "mag- 
 netic record;" and it is mounted 
 upon a shaft, as shown in edge 
 view in Fig. 137, by which it is 
 revolved between the poles of a 
 horse-shoe magnet. One pole of 
 this magnet is quite close to the rear 
 side of the disk ; the other pole carries a needle, the point 
 of which is placed very near to the indented ridge on the 
 disk, but does not touch it. In the mechanical phono- 
 graph, it will be remembered, the needle actually follows 
 
 if/Toft. 
 
 Fig. 137. 
 
322 THE AGE OF ELECTRICITY. 
 
 the line of dots. Here the needle is entirely separated 
 from the indentations. Hence, because the needle is at- 
 tached to one pole of the magnet, and the disk is very 
 close to the other pole, both needle and plate become mag- 
 netized by induction ; and as they are at opposite poles of 
 the magnet, and, .besides, are very close together, a very 
 strong magnetic field exists between them. Finally, 
 around the needle is a coil of wire, the ends of which 
 are connected to a receiving telephone of the usual form. 
 
 The reader will have no difficulty here in recognizing all 
 the parts of a magneto-electric machine in which the mag- 
 net (disk) revolves in front of the core (needle), and so 
 induces a current in the coil surrounding the core. Now, 
 while a perfectly smooth circular plate magnet might be 
 revolved in the way shown, in front of a coil, without 
 causing any current in the latter, here we have a plate 
 magnet on which there is a continuous line of eleva- 
 tions and depressions which successively pass before the 
 needle-point. Of course the surface of the magnet at 
 the bottom of a depression is farther from the point than 
 is the surface at the top of an elevation. Hence, as the 
 magnet revolves, the distance of its surface from the nee- 
 dle-point is constantly changing, and therefore changes are 
 produced in the magnetic field around the needle-point ; 
 and hence currents are set up in the coil of which the nee- 
 dle is the core, and in a telephone connected with the 
 coil. In this way^ the telephone is made to reproduce 
 the sounds which in the beginning caused the indentations 
 in the waxed plate. 
 
 The most striking feature of the apparatus lies in the 
 fact that here is apparently simply an iron disk revolving 
 quite slowly, and not in contact with any thing. A little 
 coil of wire is fastened near to it, and a telephone is in 
 circuit with that wire. The indented foil of the mechani- 
 
THE SPEAKING TELEPHONE. 323 
 
 cal phonograph, being rubbed by the needle, soon wears 
 out ; and, indeed, after three or four repetitions of the 
 sound, the articulation becomes very much blurred if not 
 altogether indistinct. But this iron disk will last forever. 
 There is no frictional contact to wear it out. It is far 
 more durable as a record than even the printed page ; and, 
 like the latter, it may by electrotyping be infinitely re- 
 duplicated. Who knows but that the books of the future 
 will be made in this way? Imagine the author dictating 
 his thoughts to the slowly revolving waxed plate, and fin- 
 ally sending them to the world in the form of an iron 
 plate. And then the reader or, rather, the hearer 
 simply goes to the collection of plates which forms his 
 library, selects his volume, fastens it on the shaft driven 
 by a little electro-motor, touches the button which starts 
 the machine, puts his telephone to his ear, and listens to 
 the author's words read by the author, and so given the 
 meaning which the author intended. And further, by per- 
 haps a little stretch of fancy, think how any one of the 
 noted novelists who nowadays delight the public by read- 
 ings of their own romances, might, so to speak, expand 
 himself. He might, for example, discourse each of his 
 novels before a separate plate. When a lecture-committee 
 invites him to the platform, in lieu of a disagreeable 
 railroad-journey taken by himself, he merely forwards the 
 plate of the desired novel, by express. It is the plate 
 which comes on the platform, and not the reader 
 although, no doubt, a life-sized photograph of the author 
 could be exhibited to add to the illusion. As it is as 
 easy to connect a hundred telephones as one, to the coil, 
 there the audience might sit, there a score of audiences 
 might sit, in as many different towns all over the land, 
 each person listening through his own telephone, while 
 the dignified functionary who usually introduces lecturers 
 
324 THE AGE OF ELECTRICITY. 
 
 might also turn the plate by a foot- treadle, regulate the 
 current, and acknowledge the applause. 
 
 In fact, it would not even be necessary for an audience 
 to gather. The plate would probably be sent directly to 
 the central office of the local telephone exchange ; and the 
 subscribers would stay at home, and hear the lecture or 
 reading over the lines. 
 
 Of course, noted singers might also have their plates, 
 and the plates at least would never be indisposed and un- 
 able to sing. And, as for congressmen, to them the in- 
 vention might prove indeed a boon ; for a powerful oration 
 duly impressed on a magnetic record plate could techni- 
 cally be delivered in Congress through the medium of a 
 machine which would revolve the disk at say twenty thou- 
 sand revolutions a minute ; and then be re-delivered before 
 one's constituents with all the emphasis to be got out of 
 one revolution in five minutes. 
 
 Fanciful speculation, however, aside, Mr. Tainter's in- 
 vention is of much ingenuity ; and, while it is difficult to 
 predict many practical every-day applications for it, that 
 it will prove stimulative and suggestive to further research 
 in the same field, is certainly to be expected. 
 
THE INDUCTION COIL. 325 
 
 CHAPTER XIII. 
 
 THE INDUCTION COIL, AND POWERFUL ELECTRIC DISCHARGES. 
 
 ALTHOUGH machines for the production of static or 
 f rictional electricity have been made the subject of many 
 ingenious improvements within recent years, they have 
 found little practical application out of the laboratory or 
 lecture-room. Wherever discharges of high potential elec- 
 tricity are required, the same can be much more conven- 
 iently and certainly obtained through the agency of the 
 induction coil. Two classes of static electrical machines 
 are, however, recognized, those in which a plate or 
 cylinder of glass is constantly excited by friction, and as 
 constantly discharged into a reservoir of force ; and those 
 in which the electric is excited by friction at the com- 
 mencement of the operation, but is not itself discharged. 
 A small initial charge is given, for example, to a piece of 
 ebonite ; and a revolving glass disk is thus caused to re- 
 ceive a succession of charges which are transferred to a 
 condenser or conductor, which in turn re-acts upon the 
 original charge, and gradually raises it to a high tension. 
 
 The first type of machine, depending entirely upon fric- 
 tion, has become nearly obsolete, because of its defects 
 and the labor of working it. The second type, known 
 as induction machines, produces equal effects with only a 
 fraction of the mechanical work. The latest and best 
 forms of this apparatus are those devised respectively 
 by Voss and Wimshurst. 
 
326 THE AGE OF ELECTRICITY. 
 
 Where very powerful electrical discharges are now re- 
 quired, they are produced by means of the inductorium, 
 or induction coil. In explaining the phenomena of induc- 
 tion, and Faraday's great discoveries relating thereto, we 
 noted that whenever a conductor through which a current 
 was passing was moved into proximity to another con- 
 ductor forming a closed circuit, an induced current was 
 caused in the second conductor ; and that this happened 
 whether the first conductor was moved into proximity to 
 the second, or the second into proximity to the first ; and 
 this was illustrated in Fig. 43. Now, it is not at all 
 necessary to move either conductor in order to induce a 
 current by one in the other. The two conductors as, for 
 example, the two coils in Fig. 43, may be rigidly fixed in 
 a stationary position, and the current itself moved into or 
 out of one of them ; that is, by establishing it or inter- 
 rupting it. By this arrangement one conductor is always 
 in the magnetic field of force of the other ; and when we 
 make or break the current, we simply produce the field of 
 force or cause it to disappear. Every time we "make" 
 the circuit in the so-called primary conductor or coil, we 
 induce in the other, or secondary conductor or coil, a 
 momentary current in the opposite direction ; and at every 
 break of the primary current, a powerful secondary cur- 
 rent in the same direction is caused. 
 
 In the induction coil, there are two coils of wire. The 
 primary coil is made of larger wire, so that it may carry 
 strong currents, and produce a powerful magnetic field at 
 ;he centre. It has few turns, so as to keep the resistance 
 low, and to prevent the inductive action of the turns of the 
 coil on each other. Within this coil is an iron core, which, 
 becoming itself magnetized by the current passing through 
 the primary coil which immediately surrounds it, increases 
 the number of lines of force passing through the coils. 
 
THE INDUCTION COIL. 327 
 
 This core is usually made of a bundle of straight fine 
 wires. Finally, wound around the outside of the primary 
 coil is the secondary coil, which is made of very thin wire 
 in an immense number of turns. All of the wire is very 
 carefully insulated, so that the currents traverse its entire 
 length. Every time the current is established or broken 
 in the turns of the primary coil, a momentary current is 
 induced in the turns of the secondary coil ; and the com- 
 bined inductive effect of the turns of the primary coil, 
 upon the immense number of turns of the secondary coil, 
 occurring instantaneously, results in a current, or rather a 
 discharge, of enormous electro-motive force. 
 
 Fig. 138. 
 
 In order to produce the necessary rapid interruptions of 
 the current in the primary coil, an automatic circuit- 
 breaker is provided. This may be simply a vibrating 
 armature of an electro-magnet, alternately energized and 
 de-energized, which armature in vibrating alternately makes 
 and breaks the primary circuit. This arrangement is used 
 m comparatively small induction coils, such as the one 
 illustrated in Fig. 138 ; but in larger machines, such as 
 represented in P'ig. 139, Foucault's interrupter is used. 
 This consists in an arm of brass L, which dips a platinum 
 wire into a cup of mercury M, from which it withdraws 
 the point, so breaking circuit in consequence of its other 
 end being attracted to the core of the coil whenever the 
 
328 
 
 THE AGE OF ELECTRICITY. 
 
 coil is magnetized. When the coil is demagnetized the 
 arm is drawn out by a spring, so breaking the circuit. 
 
 As has been above stated, whenever a current is passed 
 through a conductor, it acts inductively upon itself, pro- 
 ducing a current which is known as the extra current. 
 When the circuit is established, this extra current moves 
 against the main current, diminishes its force, and pre- 
 vents it rising to its full value. When the circuit is 
 
 Fig. 139. 
 
 broken, the extra current moves with the main current, 
 and increases the strength of the latter just at the moment 
 when it ceases altogether. The extra current in the pri- 
 mary coil of an inductorium would materially interfere 
 with its efficiency. To prevent this, it is usual to connect 
 in the circuit of the primary coil a small condenser, made 
 of alternate layers of tin-foil and paraffined paper, into 
 which the current flows when the circuit is broken. The 
 effect of the condenser is first to make the break of the 
 circuit more sudden by preventing the spark of the extra 
 
THE INDUCTION COIL. 329 
 
 current from leaping across the interrupter, and, second, 
 to accumulate the electricity of this self-induced extra 
 current in order that when circuit is again made, the 
 current shall attain its full strength gradually instead of 
 suddenly, thereby causing the inductive action in the 
 secondary circuit at "make" to be comparatively feeble. 
 
 In the arrangement shown in Fig. 139, the battery is con- 
 nected to the binding posts 6, b' ', in circuit with which are 
 a commutator at C, the primary wire of the coil which is 
 secured to the posts /, /, and also the interrupter or break 
 L, M. The condenser is disposed in the base of the in- 
 strument, and connects with the posts /, /. So that the 
 battery current flows normally through the primary coil, 
 is broken at the interrupter, and the extra current due to 
 the breaks enters and is diffused in the condenser. The 
 ends of the secondary coil connect with the upper ends 
 of the glass posts at A, B, and between the terminals of 
 this coil the discharge or spark is produced. 
 
 The most powerful induction coil in existence is that 
 constructed by Apps for the late Mr. Spottiswoode. The 
 secondary wire is 280 miles in length, and contains 341,850 
 turns. With thirty Grove cells this apparatus is compe- 
 tent to yield a spark forty-two inches long between the 
 terminals of the secondary coil. These terminals are 
 placed above the coil, in the same position as the termi- 
 nals ^1 B in the much smaller coil represented in Fig. 139. 
 The sparks produced by such a machine as this are verit- 
 able flashes of lightning, accompanied by reports, which 
 represent the thunder in miniature. In order to produce 
 a spark forty-two inches in length from a galvanic battery 
 only, it has been calculated that from sixty thousand to a 
 hundred thousand cells of the most favorable construction 
 would be required. 
 
 Fig. 140 represents the great Spottiswoode coil. The 
 
330 THE AGE OF ELECTRICITY. 
 
 discharge occurs between the disk and the small ball 
 shown immediately in front of the cylinder, and usually 
 appears as a zigzag line of bluish-white light accompanied 
 by both a crackling and a hissing sound. When the 
 points are brought within some two or three inches of 
 each other, the discharge appears as a mass of yellow 
 flame from a half to three-quarters of an inch thick. The 
 twenty-eight-inch spark will perforate a piece of glass 
 three inches in thickness, and it is calculated that a glass 
 block twice as thick could be penetrated by the forty-two- 
 inch spark. 
 
 When a high-tension discharge of electricity is sent 
 through rarefied air or through a vacuum, the appearance 
 of the spark greatly changes. In rarefied air, the light 
 assumes a red glow, and a beautiful green radiance is pro- 
 duced when a part of the glass is colored with uranium. 
 
 Induction coils, of course on a small scale, are used in 
 medical electric apparatus. Their most important practi- 
 cal employment is in connection with the telephone trans- 
 mitter, wherein the coil renders the working current from 
 the battery of greater force, and so enables speech to 
 be transmitted over longer distances. The huge coils 
 above described have proved of great assistance in the 
 study of the behavior of the electrical current in rarefied 
 media ; and a very elaborate series of investigations was 
 made by Mr. Spottiswoode, by the aid of his coil, into 
 the nature of the peculiar striae or stratifications into which 
 the electric discharge separates when passed through nar- 
 row tubes. When the exhaustion of a so-called vacuum 
 tube is carried considerably beyond the point which gives 
 the best striae and luminous effects, a new set of phenom- 
 ena is produced ; the residual gas in the tube developing 
 so many new and curious properties that Mr. William 
 Crookes, F.R.S., has asserted that the gas may in fact 
 
THE INDUCTION COIL. 331 
 
 be regarded as matter in a fourth or ultra-gaseous state. 
 To the known conditions of matter, solid, liquid, and 
 gaseous, he thus adds one which he terms " radiant." 
 
 Probably the most important application of static or 
 frictional electricity to industrial use is the electric mid- 
 dlings-purifier devised by Messrs. Smith and Osborne. 
 This consists of a series of hard rubber rolls electrified 
 by the friction of hair, silk, wool, or other suitable mate- 
 rial ; under which rolls the middlings pass slowly to a 
 shallow receiver, the latter being rapidly shaken so as to 
 bring the bran to the top. The light particles of bran 
 leap to the rolls, and cling thereto until brushed into a 
 shallow gutter placed in front of each roll. Meantime 
 the heavy and electrically rejected middlings descend by 
 gravity, and pass through the bolts in the order of their 
 fineness. Travelling brushes constantly sweep the bran 
 from the gutters, into the bran-receiver on the side of 
 the purifier. In this receiver is a spiral conveyer. By the 
 time the last line of rolls is reached, the material has 
 been successively diminished by the abstraction of the 
 bran and the screening out of the several grades of mid- 
 dlings, until only a trifling quantity of heavy refuse (if 
 there be any) is left to pass over the tail of the purifier 
 into the spout provided for it. The bran which adheres 
 to the rolls is brushed off when it reaches the sheepskin 
 cushion, which lightly touches the top of the roll to 
 electrify the hard rubber. 
 
 The curious suggestion has been made, that perhaps 
 the lightning can be made to produce artificial diamonds 
 through the volatilization of carbon confined in an im- 
 mensely strong vessel. It was proposed to place such a 
 vessel, containing some form of carbon, in the circuit of 
 a lightning-rod, so that the current would necessarily pass 
 through the carbon in going to earth ; the idea being, that 
 
332 THE AGE OF ELECTRICITY. 
 
 after volatilization the carbon would perhaps crystallize 
 into the diamond. This seems rather more fantastic than 
 practicable. 
 
 The discharge of statical electric machines has been 
 found very efficacious in causing the deposition of smoke ; 
 the particles forming flakes, and rapidly sinking. Rooms 
 filled with dense smoke have thus been rapidly cleared. 
 A useful application of this discovery has been made in 
 effecting the condensation of volatilized lead, for which 
 purpose long passages, some two miles in length, are 
 ordinarily required. 
 
 Whether the actual lightning discharge will be utilized, 
 remains yet to be seen. Many years ago Mr. Andrew 
 Crosse erected insulating supports throughout his grounds, 
 and on these stretched three thousand feet of exploring 
 wire, by means of which the electricity of the air could 
 be conveyed into the house and there examined. When 
 connection was made with the inner coating of his great 
 Ley den-battery of fifty jars, exposing 146 square feet of 
 coated surface, remarkable effects were obtained. Iron 
 w i re ^fa of an inch thick and thirty feet in length was 
 fused into red-hot balls ; strips of metal laid on glass, 
 and placed in circuit, were on discharge of battery instantly 
 dissipated, leaving only metallic streaks. 
 
OTHER APPLICATIONS OF ELECTRICITY. 333 
 
 CHAPTER XIV. 
 
 THE APPLICATIONS OF ELECTRICITY TO MEDICINE, WAR, 
 RAILWAYS, TIME, MUSIC, ETC. 
 
 THE utilizations of electricity reveal the most singular 
 contrasts. It is a vigilant and sleepless sentinel : it guards 
 the signals which protect the swift-rushing express ; it 
 warns us of the inroad of thieves or the outbreak of fire 
 in our dwellings, the leak in the vessel, or the low water 
 in the steam-boiler. On the other hand, it is a most 
 treacherous foe : it drives and explodes the deadly tor- 
 pedo, which, all concealed under water, steals noiselessly 
 upon the fated ship ; it fires the hidden mine beneath the 
 very feet of the unsuspecting battalion ; and from its inert, 
 harmless-seeming wires, the merest casual touch may bring 
 forth instant death, swift as the greater lightning, J n the 
 hands of the physician, the curative effects of the electric 
 current render it a potent ally for the relief of human suf- 
 fering : yet its destructive certainty will in time render it 
 the instrument of execution of the last penalty of the law. 
 
 It annihilates time and space in the telegraph ; yet it 
 may govern the one in hundreds of clocks simultaneously, 
 and measure the other as it is traversed by the railway- 
 train or the steamship. It will impel the locomotive ; and, 
 equally, it will control the brake which stops its motion. 
 It will deposit the flakes of the smoke-cloud ; or fire the 
 charge which hurls aloft whole acres of rock, and opens 
 
334 THE AGE OF ELECTRICITY. 
 
 great rivers to navigation. It will light up the inner cav- 
 ities of the living body, so that the eye of the surgeon 
 may explore them ; or illuminate the eternal darkness of 
 the depths of the great sea, so that the retina of the cam- 
 era may see and record their mysteries. It will indicate 
 for us the heat of the steel-furnace, or that of the far 
 distant stars. In one form it will tear asunder the atoms 
 of water ; in another, cause them to re-unite. It will set 
 type, and drive the printing-press ; operate the intricate 
 pattern-mechanism, and move the loom. It is already in 
 use to control the warmth of the hatching egg : it has been 
 proposed to use the current to cremate the bodies of the 
 dead. It will protect a freezing-chamber from too high 
 a temperature, or a vineyard from the effects of frost. It 
 will make engravings and etchings, and then reproduce 
 its work ad infinitum. It will aid in dyeing and in bleach- 
 ing. It will reveal the approach of the earthquake or the 
 rumblings of the volcano, or the almost imperceptible 
 sounds of the human heart. It will steer a ship, and indi- 
 cate her course. It will give to new wine the flavor of 
 the oldest vintages. It will ring the chimes in the steeple, 
 or the bells in the kitchen. It will turn on the gas in our 
 dwellings, light it for us, and turn it off. It will record 
 the votes which change the destiny of a great nation, or 
 set down the music of the last popular melody. It will 
 talk in our voices, hundreds of miles away. It will forge 
 in San Francisco the signature we make in New York, 
 From the great organ it will evoke all its majestic har- 
 monies, and yet set free the tumult of whole broadsides 
 
 of those 
 
 " Mortal engines whose rude throats 
 The immortal Jove's dread clamors counterfeit." 
 
 Where in the history of all magic are there wonders 
 greater than these ? 
 
OTHER APPLICATIONS OF ELECTRICITY. 335 
 
 And we can do no more than suggest their vast multi- 
 plicity. To attempt to compile even a mere list of the 
 various applications of electricity to specific purposes, 
 might well prove a hopeless task ; for, if fairly compre- 
 hensive to-day, to-morrow might find it behind the times. 
 There is no exaggeration in the statement : the record of 
 the hundreds of patents issuing weekly from the Patent 
 Office of this country will amply substantiate it, and the 
 files of the many technical periodicals will furnish super- 
 abundant proof. Since the first pages of this work were 
 written, a few months ago, Professor Hughes has an- 
 nounced the results of his discoveries in the nature and 
 character of electrical conductors, which, if not likely to 
 engage popular attention, are fairly revolutionary of former 
 ideas, and, in point of scientific interest and economic 
 importance, can hardly be over-estimated. So also, since 
 then, the first announcement has come of the possibility 
 of the direct conversion of heat into electricity in the 
 galvanic cell, using no temperature above that of boiling 
 water, a discovery great in its potency of future benefits, 
 for it may mark the beginning of the end of the reign of 
 steam. 
 
 The medical use of electricity electro-therapeutics 
 belongs to the domain of the specialist physician. In the 
 hands of the skilful practitioner, electricity as a curative 
 agent often proves of incontestable value. A discussion 
 of even the elementary principles of this branch of the 
 science would be out of place in these pages ; so that we 
 restrict ourselves simply to some of the more curious and 
 salient facts attending the influence of electricity in and 
 upon the animal economy. It is now believed that the 
 production of electricity is constant in all the living tissues. 
 Electrical currents occur in the muscles and nerves, and 
 
336 THE AGE OF ELECTRICITY. 
 
 between different surfaces of the body. All of the bodily 
 organs yield electrical currents when they are divided. 
 
 It is well known that electricity can be tasted. A cop- 
 per coin and a silver coin, placed respectively above and 
 below the tongue, will produce a sharp acrid flavor very 
 easily recognized. An ingenious telegrapher once suc- 
 ceeded in receiving messages sent to a wrecked railroad- 
 train in this way. After the accident, which occurred at 
 a long distance from any station, the telegraph-wires 
 beside the road were cut, and a message easily sent by 
 alternately making and breaking contact of one end of 
 the wire with the other. There was, of course, no receiv- 
 ing instrument available ; but the ingenious operator sim- 
 ply placed the ends in his mouth, and as the story goes 
 managed to read the signals sent him, simply by the 
 recurrence of the acrid galvanic taste. 
 
 It further appears that the current is capable at least 
 of stimulating the senses of smell, hearing, and sight. 
 Hitter discovered that a feeble current transmitted through 
 the eyeball produces the sensation as of a bright flash of 
 light. Curiously enough, on the other hand, it has been 
 proved that when a frog's eye is exposed to light, a cur- 
 rent is produced in the optic nerve. A strong current 
 causes in some people the perception of blue and green 
 colors flowing between the forehead and the hand. Volta 
 and Ritter heard musical sounds when a current was 
 passed through the ears ; and Humboldt found a sensa- 
 tion to be produced in the organs of smell when a current 
 was passed from the nostril to the soft palate. 
 
 Quite an effective battery has been made from frogs' 
 thighs, and it has been determined that the electro-motive 
 force of a current from a frog's muscle equals about -J of 
 a volt. When properly prepared, the legs of a frog con- 
 stitute a galvanometer which will reveal excessively deli- 
 
OTHEE APPLICATIONS OF ELECTRICITY. 337 
 
 cate induction currents barely recognizable by the most 
 sensitive instruments. The effect of electrical currents on 
 newly killed animals is very remarkable. A grasshopper 
 has thus been made to emit its chirp ; fishes, sheep, oxen, 
 and rabbits undergo spasmodic muscular contractions. 
 Strong currents applied to the bodies of executed crimi- 
 nals have produced contortions of the most horrible char- 
 acter, and evoked motions of the members and organs 
 almost identical with those of life. The power of con- 
 tracting under the influence of the current appears to be a 
 distinguishing property of protoplasm wherever it occurs. 
 The amoeba, the most structureless of organisms, suffers 
 contractions ; and the sensitive-plant, and the Dionaea or 
 Venus's fly-trap, both close when electrified. In the liv- 
 ing human body, the contraction of muscles produces cur- 
 rents. These Dubois-Reymond obtained from his own 
 muscles by dipping the tips of his fore-fingers into two 
 cups of salt water communicating with the galvanometer 
 terminals. A sudden contraction of the muscles of either 
 arm produced a current from the contracted toward the 
 uncontracted muscles. 
 
 "It appears," says Dr. Golding Bird, "that we are 
 constantly generating this agent, and that quoad the sup- 
 ply of electric matter in man far exceeds the torpedo or 
 the electric eel, and is only prevented from emitting a be- 
 numbing shock whenever he extends his hand to greet his 
 neighbor, from the absence of special organs for increas- 
 ing its tension. . . . Some, indeed, have gone the danger- 
 ous length of regarding electricity as the principle of life 
 itself, and have dared to place it on a level with the divine 
 essence, which, emanating from the Creator, constitutes 
 what, for want of a better name, we call vitality. These 
 pretensions have been given to this agent from its effects 
 when made to traverse the muscles of recently killed 
 
338 THE AGE OF ELECTRICITY. 
 
 animals, but more particularly when conveyed along the 
 spinal nerves of a recently executed malefactor. This, 
 in the hands of Dr. Ure in his celebrated experiment upon 
 the murderer Clydesdale, worked on the dead but yet 
 warm corpse a horrible caricature of life : by calling into 
 violent contractions the muscles of the face, all the ex- 
 pressions of rage, hatred, despair, and horror, were de- 
 picted upon the features, producing so revolting a scene 
 that many spectators fainted at the sight. But this ex- 
 periment, striking as it was, merely afforded an additional 
 proof of the susceptibility of the muscles to the stimulus 
 of the electric current ; and, when divested of its dramatic 
 interest, becomes not more remarkable than the first ex- 
 periment of Galvani on the leg of a frog." 
 
 The natural currents of the body will readily affect the 
 telephone, the making and breaking of a muscular current 
 being plainly perceptible in the instrument. M. Boudet 
 of Paris has even used the telephone as a means of hear- 
 ing the workings of the muscles in certain paralytic and 
 nervous ailments ; while the resistance telephone, or mi- 
 crophone, has proved to be a stethoscope capable of 
 revealing murmurs in the circulation which cannot be 
 detected by the ordinary instrument. 
 
 There are always a vast number of so-called electrical 
 appliances in the market, in the shape of "electric" 
 brushes, "electric" garments, "electric" belts, etc. 
 Whatever curative value lies in these things resides mostly 
 in the imagination of the user. Many of them are wholly 
 incapable of producing any electrical effect whatever upon 
 the body. It is a safe rule, never to attempt the use of elec- 
 tricity remedially, save under the advice of a regular phy- 
 sician ; for, in certain bodily ailments, the current wrongly 
 employed may be productive of great and lasting injury. 
 
 Some of the delusions about the curative effects of elec- 
 
OTHER APPLICATIONS OF ELECTRICITY. 339 
 
 tricity have been very singular and amusing ; and perhaps 
 the first of them furnishes as good an instance as any of 
 the extraordinary credulity with which they have been 
 received, not only by the general public, but often by 
 men really learned in science. In the year 1747 Signior 
 Johannes Francisco Pivati, a "person of eminence" in 
 Venice, propounded the remarkable theory, that if odorous 
 substances were confined in a glass vessel, and the vessel 
 electrically excited, the odors "and other medicinal vir- 
 tues " would transfuse through the glass, and permeate 
 the person holding the vessel ; and from the person so 
 permeated, all manner of diseases, like exorcised spirits, 
 would at once depart, while the individual himself would 
 be delightfully perfumed. In this absurdity even so emi- 
 nent a philosopher as Winkler of Leipsic firmly believed ; 
 and then, not content with merely believing, he proceeded 
 to improve upon Pivati's stories in a way that must have 
 disheartened any one who had hitherto believed in him. 
 He said that he had not only perfumed a whole company 
 with cinnamon ; but that by merely connecting a globe 
 filled with balsam, by means of a long chain extending 
 from the globe to his patient, the latter's " nose was filled 
 with a sweet smell, and after sleeping in a house a con- 
 siderable distance from the room where the experiment 
 was tried, he rose very ' chearful ' in the morning, and 
 found a more pleasant taste than ordinary in his tea." 
 Think of the transmission of perfumes by telegraph ! 
 The Royal Society sent to Winkler for tubes, and invited 
 him to repeat some of his alleged wonderful results. But 
 he found it inexpedient to try. Benjamin Franklin dealt 
 the finishing stroke to the humbug, by a series of experi- 
 ments which clearly demonstrated the entire " improbabil- 
 ity of mixing the effluvia or virtue of medicines with the 
 electric fluid." 
 
340 THE AGE OF ELECTEICITY. 
 
 Frequently during the last century, and even occasionally 
 nowadays, persons have been brought before the public 
 as possessed of wonderful inherent electrical properties. 
 Sometimes they merely transmit disagreeable shocks to 
 individuals who approach them ; and at others, they con- 
 tent themselves with performing extraordinary feats of 
 strength, which are attributed to "electricity" somewhere 
 in or about the performer. There was Angelique Cotton 
 of Finisterre, France, who in 1846 is said to have thrown 
 down powerful men, and to have taken chairs away from 
 the strongest athletes. The chronicle says that her neigh- 
 bors had her exorcised without avail, and that she was 
 4 ' most electric after dinner." At the present time elec- 
 tric boys flourish chiefly in dime-museums, where the de- 
 ception is quite neatly done. A strong battery usually 
 communicates with the metal plate on which the boy 
 stands, and with a similar metal plate on the other side of 
 a railing before which the visitor must place himself in 
 observing the phenomenon. When the visitor touches the 
 boy, circuit is made through the bodies of boy and visitor, 
 and both receive a shock. The boy is used to it, and 
 bears the infliction stoically : the visitor, who is just as 
 electric as the show itself, experiences a spasmodic con- 
 traction, and departs much gratified. Some visitors have 
 been thoughtless enough to present their knuckles to the 
 lobes of the ears or the ends of the noses of electric boys, 
 with the result of causing to the phenomenon much bodily 
 misery, not to mention some interference with the orderly 
 and peaceful progress of the entertainment. 
 
 Very powerful electric currents will cause death as 
 instantaneous as, and in all respects similar to, that due 
 to the lightning stroke. Several fatal accidents have 
 occurred through workmen, engaged in adjusting electric 
 lights, grasping the ends of wires leading to the dynamos ; 
 
OTHER APPLICATIONS OF ELECTRICITY. 341 
 
 and there have been many instances where people having 
 incautiously touched the brushes of dynamos in motion 
 have been instantly killed. Professor Tyndall once, while 
 lecturing, accidentally received the discharge of a large 
 battery of Leyden-jars ; which, he says, first caused a 
 complete obliteration of consciousness, and then the curi- 
 ous sensation of a floating body to which the several mem- 
 bers were one by one attached, until he finally recognized 
 that he was all there, and resumed his normal condition. 
 No permanently injurious effects followed. 
 
 It appears to be demonstrated, that death by the electric 
 shock is painless, for the reason that the nerves do not 
 have time to convey the sense of the injury to the brain 
 before life is extinct. The substitution of the electrical 
 shock for the present inefficient and demoralizing mode of 
 enforcing the death-penalty, is strongly advocated; and 
 there is little reason to doubt that in time it will be effected. 
 A bill to this end was introduced in the New-York Legis- 
 lature in 1886. With electric-light conductors conveying 
 deadly currents throughout the streets, it would be a very 
 easy matter to carry branches of these to the usual place 
 of execution, and despatch the criminal instantly, cer- 
 tainly, and painlessly, by the mere touch of a button. It 
 is said that a current of a strength of one-tenth ampere 
 is as much as any one can safely allow to traverse his 
 body in the period of one second ; and this strength will 
 depend upon the bodily resistance, which varies between 
 six thousand and fifteen thousand ohms, depending mate- 
 rially upon the condition of the skin, whether moist or dry. 
 
 There has been one application of electricity to slaugh- 
 tering purposes, not only proposed but patented. On 
 March 30, 1852, a United-States patent was granted to 
 Dr. Albert Sonnenburg and Philipp Rechten, of Bremen, 
 Germany, for an electric whaling- apparatus, which is not 
 
342 THE AGE OF ELECTRICITY. 
 
 without ingenuity, however impracticable it doubtless is. 
 The whale is harpooned in the usual way, but to the iron is 
 connected a stout metallic cable leading to a hand magneto 
 machine in the whale-boat. The bottom of the boat is 
 well coppered. As soon as the harpoon has struck, the 
 pole is withdrawn so that the head of the harpoon, together 
 with the metallic conductor, remains in the animal. "The 
 machine," say the inventors, "is now set in motion; the 
 electric current through the metallic conductor and the head 
 of the whale-iron circulates in the body of the fish or ani- 
 mal, and returns from the same through the salt water to 
 the copper bottom of the boat, and thence by means of a 
 short metallic conductor to the machine. The fish or ani- 
 mal receives about eight tremendous strokes at each turn- 
 ing of the machine handle." The inventors fail to explain 
 what inducement is offered to the crew of the boat, to 
 make them relinquish their oars, and turn a crank, during 
 the rather critical moments when their craft is moored to 
 a wild whale. 
 
 Several species of creatures inhabiting the water have 
 the power of producing electric discharges by certain por- 
 tions of their organism. The best known of these are the 
 torpedo, the gymnotus, and the silurus, found in the Nile 
 and the Niger. The raia torpedo, or electric ray, of which 
 there are three species inhabiting the Mediterranean and 
 the Atlantic, is provided with an electric organ on the 
 back of its head. This organ consists of laminae com- 
 posed of polygonal cells to the number of eight hundred 
 or a thousand, or more, supplied with four large bundles of 
 nerve-fibres : the under surface of the fish is negative, and 
 the upper positive. In the gymnotus electricus, or Surinam 
 eel, the electric organ goes the whole length of the body, 
 along both sides. It is able to give a most terrible shock, 
 and is a formidable antagonist when it has attained its full 
 
OTHER APPLICATIONS OF ELECTRICITY. 343 
 
 length of from five to six feet. Humboldt gives an inter- 
 esting account of the combats between the electric eels 
 and the wild horses, driven by the natives into the swamps 
 inhabited by the gymnotus. Prof. S. P. Thompson has 
 called attention to the curious point that the Arabian name 
 for the torpedo, ra-ac7, signifies lightning. 
 
 Electrical apparatus for aiding medical diagnosis, or for 
 surgical purposes, exists in many ingenious forms. The 
 so-called dental engines, for actuating the burrs and other 
 implements used in operations on the teeth, are now driven 
 by small electric motors. A still smaller engine is con- 
 cealed in the handle of the plugger which compacts the 
 gold fillings in teeth ; so that the instrument need only be 
 placed in position, and the work usually done by the den- 
 tist's assistant with a mallet is automatically accomplished. 
 An instrument containing a minute platinum wire, rendered 
 white hot by the current, is employed as a substitute for 
 the needle in the destruction of nerves. A truly diaboli- 
 cal contrivance of an English dentist is an arrangement 
 of extracting- forceps and a battery, so contrived, that, 
 as the tooth is removed, a severe shock is administered to 
 the victim. The peculiar benefit of this device appears 
 to reside in the fact that the patient is hurt so much by 
 the shock, that he fails to notice the less pain involved 
 in the actual extraction of the tooth. The electric light 
 is a valuable aid to the dentist. Miniature incandescent 
 lamps are arranged with mirrors, so that they can be in- 
 serted in the mouth, and their rays directed at will. The 
 oral cavity is illuminated so brilliantly that any departure 
 from normality can easily be detected, while the light 
 transmitted through the teeth reveals with much clearness 
 any evidence of unsoundness. 
 
 As dental fillings often consist of different metals, 
 such as silver, tin amalgam, and gold, electrical cur- 
 
344 THE AGE OF ELECTRICITY. 
 
 rents are frequently set up between them, the natural 
 liquids of the mouth forming the conducting fluid. In 
 such cases, gradual wearing-away of the attacked metal 
 follows ; and instances have been known where unaccount- 
 able aches in filled teeth have been cured by removing a 
 filling of one metal, and substituting an inert substance or 
 a metal of different electrical character. 
 
 In surgery, fine platinum wires highly heated by the cur- 
 rent are used for cauterizing purposes, and for the removal 
 of abnormal growths. The gastroscope consists of a rigid 
 horizontal tube, terminating in one direction in an eye- 
 piece, and in the other prolonged into a partially flexible 
 tube which can be passed down the oesophagus until its 
 end reachv-s the stomach. At the end of the tube is a 
 tiny glass lantern, in which is a piece of platinum wire 
 which is rendered brilliantly incandescent by the current. 
 From this, light radiates freely on all sides, and illuminates 
 the interior of the stomach. In the tube above the lan- 
 tern is a little window. Into this a portion of the rays 
 from the lantern are reflected back by the sides of the 
 stomach. Finally there is a very ingenious arrangement 
 of lenses and prisms, whereby the image of the side of 
 the stomach is reflected back to the observer's eye at the 
 eye-piece of the tube. The extremity of the gullet tube, 
 with its little window, can be made to revolve, so that, 
 after the instrument is once adjusted, the operator can 
 easily inspect the different parts of the interior of the 
 stomach. 
 
 The laryngoscope consists simply of a tongue depresser, 
 on the end of which is mounted a small incandescent 
 lamp. It is used for examining the interior cavities of 
 the nose and mouth. The light has also been usefully 
 employed in photographing the larynx. The photographic 
 apparatus, which is quite small, is brought into position, 
 
OTHER APPLICATIONS OF ELECTRICITY. 345 
 
 and, by the pressure of the finger on a button, the elec- 
 tric circuit is closed through both a small lamp and rn 
 electro-magnet. The lamp illuminates the parts to be 
 photographed, and the magnet opens the objective, so 
 that the photograph is instantly taken on very sensitive 
 prepared plates. 
 
 Trouve's electric probe consists of three distinct parts, 
 a battery, a probe, and an indicator. The probe proper 
 is a pipe, flexible or rigid, constructed so that the pre- 
 liminary probing may be effected, and then the stylets of 
 the indicating apparatus introduced. The indicator con- 
 tains in its interior a very small electro-magnet with a 
 vibrator in connection with two steel rods which pass into 
 the body of the probe tube. These rods are insulated 
 from each other, so that, as soon as they touch any 
 metallic body in the wound, circuit is thereby established 
 through them, and the vibrator moves, thus revealing the 
 fact. 
 
 The induction balance has also been applied to the 
 detection of metallic substances in the body. It was 
 used, it will be remembered, unsuccessfully in the case of 
 President Garfield. Professor Bell has devised another 
 method of ball-finding, which involves the insertion of a 
 needle near where the ball is supposed to be. This needle 
 being connected by wire with one terminal of a telephone, 
 while a metallic plate laid on the skin is connected with 
 the other terminal, when the point of the needle reaches 
 the ball a current arises (the ball and metallic plate natur- 
 ally forming a couple), and a sound is heard in the tele- 
 phone. The needle may be inserted in several places, 
 with little pain, and even this may be reduced by ether 
 spray. 
 
 It has been proposed to use the thermo-pile for measur- 
 ing bodily temperatures with accuracy ; and a system has 
 
346 THE AGE OF ELECTRICITY. 
 
 even been suggested, whereby a physician sitting in his 
 office can observe the temperature of his entire circle of 
 fever-patients successively, by simply connecting by tele- 
 graph-lines each one in turn with a galvanometer suitably 
 disposed on his desk, after which he might telephone 
 back his instructions or prescriptions to the several attend- 
 ants. It is not without the bounds of probability, that 
 some one will yet devise an alarm contrivance which will 
 automatically call up the physician whenever a patient's 
 temperature reaches a certain danger point. 
 
 The applications of electricity to military uses bid fair 
 to do much toward the revolution of modern systems of 
 warfare. The electric light is of great utility, both afloat 
 and ashore. Its beam swept around the horizon reveals 
 the approach of an enemy, or lights up fortifications so 
 that a bombardment may be unerringly directed upon 
 them. Flashed in the faces of an attacking force, it is 
 bewildering. On board of vessels of war, it is of espe- 
 cial utility in illuminating the sea around the ship, thus 
 revealing the approach of torpedo-boats. It may be car- 
 ried up by balloons and thus employed for reconnoitring. 
 Incandescent lights have been used for night signalling, 
 the signals being indicated by rapid extinctions and illu- 
 minations according to some predetermined code. 
 
 Great guns are now fired by means of the electric fuse, 
 and this has been found of great value on board ship. 
 It eliminates the inaccuracies of fire due to the rolling of 
 the vessel during the necessary movement of the arm in 
 pulling the usual lock-string. The gun can be discharged 
 by electricity the instant a good sight of the object is 
 obtained. So also the use of electricity allows of an 
 absolutely simultaneous broadside, which may produce 
 tremendous effects when several powerful guns are trained 
 
OTHER APPLICATIONS OF ELECTRICITY. 347 
 
 upon a single point. On board of war-vessels, the firing 
 of the guns is now controlled by the captain from the 
 bridge, by means of a so-called annunciator, whereby 
 either individual guns or the entire battery may be fired 
 as desired. It also shows at a glance what guns are ready 
 for firing, and, by means of a tell-tale arrangement, indi- 
 cates to the crews of the guns just when the latter are 
 about to be discharged. 
 
 Heavy guns are now trained by means of electro- 
 motors ; and in England, mechanism of this description 
 has been adapted to the great cannon in the Spithead 
 forts. 
 
 It is probable that in the future, electricity will entirely 
 supersede the dangerous and unreliable fulminating sub- 
 stances now used as the means of igniting the charges in 
 fire-arms. Tests have recently been made with a rifle 
 fired by electricity, in which a small primary galvanic 
 battery is set in the stock of the gun, and connected with 
 the cartridge, which contains a fine wire which is heated 
 by the passage of the current, and in this way the powder 
 is ignited. As it is necessary merely to press a trigger 
 or button, to establish the circuit, this arrangement does 
 away with much of the ordinary lock mechanism. 
 
 It has been proposed to use the gases generated by the 
 decomposition of water, as a means of projecting shot 
 and shell, in lieu of gunpowder or other explosive ; and 
 an electrolytic cartridge has been contrived, which consists 
 simply of a sealed glass tube containing water, into which 
 the ends of wires from a battery enter. The water is 
 supposed to be decomposed by the passage of the current, 
 and then a spark passing between the terminals fires the 
 evolved gases. The practicability of this device is by no 
 means assured. 
 
 The electric sight is an ingenious substitute for the bit 
 
348 THE AGE OF ELECTRICITY. 
 
 of white cotton, or other easily visible material, often fast- 
 ened by sportsmen on the front sights of their weapons 
 when hunting at night. It is simply a thread of platinum 
 wire enclosed in a glass tube, and rendered white hot at 
 will by a current from a small galvanic battery arranged 
 in the stock of the piece. A. larger incandescent lamp 
 may be arranged near the breech and upon the barrel, and 
 provided with lenses so that its beam is thrown directly 
 upon the object aimed at. 
 
 Many very ingenious instruments have been devised, 
 wherein electricity is employed for measuring the velocity 
 of projectiles, by the aid of which some of the most diffi- 
 cult problems in gunnery have been solved. One of these 
 contrivances registers, by means of electric currents upon 
 a recording surface travelling at a uniform and very high 
 speed, the precise instant at which a projectile passes cer- 
 tain defined points in the bore of the gun. Another, 
 which determines the initial velocity of projectiles in the 
 proof of gunpowder, is capable of correctly measuring 
 periods of time as short as -g-o 1 ^ P ar ^ f a second. 
 
 For the explosion of mines or counter-mines, in siege 
 operations, the electric fuse is now indispensable. So, 
 also, submarine mines, or fixed torpedoes as they are 
 termed, are not only exploded by electricity, but the ease 
 with which the current can be Controlled allows of their 
 being blown up exactly at the moment when an attacking 
 vessel is in range. A harbor to be protected, for exam- 
 ple, is completely studded with these torpedoes sunk out 
 of sight, but all connected in electric circuit with certain 
 firing-stations ashore. By means of lenses, an image of 
 the whole harbor, or all of it within a certain range, is 
 thrown upon a whitened table in a dark chamber, well 
 protected by bomb-proofs, so that the progress of the 
 devoted ship is easily watched without danger until she 
 
OTHER APPLICATIONS OF ELECTRICITY. 349 
 
 has become hopelessly entangled. The positions of the 
 submerged mines being accurately known, and in fact 
 marked upon the whitened table, it simply remains to 
 watch the instant that the image of a vessel comes over a 
 marked point ; and then the simple pressure of a key 
 transmits the current which explodes the mine. Friendly 
 vessels may thus be allowed to pass in safety, while hostile 
 ships can be promptly destroyed. Some submarine torpe- 
 does are so arranged, that, when a vessel strikes them, a 
 weight is thrown across two contact points, one of which 
 is in connection with the fuse and the other with the bat- 
 tery, so that the current is thus led to the fuse, and the 
 mine automatically exploded. Another arrangement is 
 such, that, when the torpedo is struck, the effect is simply 
 the establishment of a weak current, not sufficient to blow 
 up the torpedo, but enough to make a signal on shore. 
 This shows that the apparatus is in order, and that the 
 exploding current can be sent or not as the shore operator 
 desires. In order to detect the presence of fixed torpe- 
 does in an enemy's harbor, an instrument has been in- 
 vented by Capt. McEvoy, called the "torpedo detector," 
 of which the action is somewhat similar to that of the 
 induction balance ; the iron of a torpedo-case having the 
 effect of increasing the number of lines of force embraced 
 by one of two opposiuo$boils, so that a current induced 
 in one coil overpowers that induced in the other, and a 
 distinct sound is heard in a telephone-receiver in circuit. 
 
 There are two kinds of torpedoes now in use by nearly 
 all nations : namely, defensive torpedoes, which are sta- 
 tionary, and are moored in harbors and channels ; and 
 offensive torpedoes, which seek the enemy's ship, and 
 either explode on striking it, or are blown up at the will 
 of the controlling operator on shore. One of the earliest 
 suggestions of exploding a moving torpedo by electricity 
 
350 THE AGE OF ELECTRICITY. 
 
 was made by Lieutenant Henry Moor, U.S.N., who in 
 1846 addressed a long memorial to President Polk, asking 
 for means wherewith to experiment upon his notion of 
 attaching electric wires to shells so that, after these mis- 
 siles had been projected, they could be exploded whenever 
 desired. The idea being obviously impracticable in the 
 form presented, it does not appear that the desired experi- 
 ments were made. Since then, however, the idea has 
 been over and over again suggested, of dropping torpe- 
 does upon cities and fortifications, from balloons sent aloft 
 by the besieging force. There is a very fatal possibility 
 in the suggestion. Great damage might be done by letting 
 fall a " dejectile " anywhere within such a large area of 
 populated country as exists in and around New York City, 
 for instance ; and there seems to be no practical reason 
 why a current sent over a wire connected to the balloon 
 could not easily control mechanism which would determine 
 the fall of the torpedo at any desired instant. 
 
 Without doubt, however, the most terribly effective and 
 dangerous application of electricity to war purposes is 
 that which has now reached an advanced state of devel- 
 opment in the so-called fish torpedo. The Sims electric 
 torpedo, which has already been adopted by the Govern- 
 ment of the United States^ is a submarine boat with a 
 cylindrical hull of copper, pointed at both ends, and some 
 twenty-eight feet in length by eighteen inches in diameter. 
 This hull, in which is placed the four hundred pounds of 
 explosive (dynamite) is submerged, and is supported at a 
 certain depth by a float. Both hull and float are protected 
 from obstructions by a sharp steel blade which runs from 
 the bow of the hull to the top of the float, and from the 
 stern of the float to the stern of the hull. The blade is 
 set at such an angle as to make the torpedo dive under or 
 cut through any obstacle. Within the hull is an electro- 
 
OTHER APPLICATIONS OF ELECTRICITY. 351 
 
 motor which drives the propelling screw. To this motor, 
 electric current is supplied by a cable leading from a 
 dynamo on shore, or on the ship from which the boat is 
 despatched. By means of this current, the operator from 
 his station on shore or on shipboard can at will start, stop, 
 or steer the torpedo, and explode the charge, which can 
 also be arranged to explode by contact of the boat with 
 the attacked object. 
 
 The terrible potency of this weapon can hardly be over- 
 estimated. In time of war these deadly " fish " will lurk 
 in bomb-proof canals adjacent to harbors and water-ways, 
 ready to slip out the moment a hostile ship comes within 
 range ; or they will be anchored in different parts of the 
 port, prepared to move on their fearful errand on the pres- 
 sure of a key. No signs of them will be visible. They 
 shoot along like huge sharks tinder the surface ; and, if 
 the water be a little rough, nothing betrays their where- 
 abouts. The first knowledge an enemy has of his peril is 
 the frightful explosion beneath his very feet, which hurls 
 his ship aloft in shattered fragments. 
 
 Conflicts between war-vessels, when thus armed, will be 
 narrowed down simply to a question of which vessel first 
 renders her torpedo effective. Guns and armor will count 
 for nothing in such a battle, which will be more like a duel 
 across a pocket-handkerchief, where the odds, slight as 
 they are, favor the man who first raises his pistol to cover 
 a vital point on his adversary. The torpedo, supplied 
 with current from the dynamo on board the war-ship, will 
 run ahead of its huge consort, and be propelled by its own 
 power. Electric snap cables attach it to the vessel. The 
 enemy may be far ahead, but the torpedo can travel at the 
 rate of eleven mile's an hour. The attacking vessel waits 
 only to get within a mile or so of her adversary, and then 
 she u lets slip the" fish "of war." The operator on 
 
352 THE AGE OF ELECTRICITY. 
 
 board ship watches the two little balls which are fastened 
 above the float, just visible above the waves, visible, 
 however, only when one knows where to look for them, 
 and has a good glass handy. He keeps these balls in 
 line; this enables him to see where the "fish" is going, 
 and a touch on a button steers the torpedo in either direc- 
 tion. The enemy, anticipating perhaps some such attack, 
 encompasses himself with floating booms. No matter : the 
 fish goes under them. Suddenly a galvanometer-needle, 
 which the operator is intently watching, moves : the 
 "fish" thus signals back word that it has met its prey. 
 The exploding button is pressed. A column of spray 
 
 Fig. 141. 
 
 leaps into the air ; a dull explosion is heard ; a great black 
 monster rolls over on its side, and then the waves break 
 above the huge iron-clad and its crew of hundreds of souls. 
 Fig. 141 represents the "fish." The electric cable is 
 shown passing into the lower portion of its submerged 
 hull ; and at the stern is the propelling-screw which is 
 protected by a guard-ring from chance entanglement with 
 ropes, nets, or other obstructions. The rudder is on the 
 upper part of the hull, just forward of the screw. In 
 order to show just what this apparatus has actually done, 
 we append (Fig. 142) a facsimile of a chart of an experi- 
 mental trial made by General Abbot, U.S.A., at the 
 Willet's Point torpedo-station. Here the course of the 
 fish as it was guided from the shore is accurately plotted, 
 
OTHER APPLICATIONS OF ELECTRICITY. 353 
 
 so as to show all its windings. Note the curve on the 
 left, indicating the doublings of the torpedo in its sinuous 
 course, as if it were chasing some victim vainly attempt- 
 ing in this way to escape ; and note also how it can be 
 sent out to run two or three thousand feet, and then 
 caused to return like a falcon to the hand of its control- 
 ler. Even if an enemy does sight the partly submerged 
 
 Fig. 142. 
 
 float, it will do him no good to fire at it. It is filled with 
 cork or like light material, and more than half of it might 
 be torn away without much impairing its buoyancy. 
 
 How to defend against a torpedo of this sort, is an un- 
 solved problem. Heavy nettings around a vessel might 
 stop one fish ; but if the immediate explosion did not sink 
 the ship itself, it would tear the netting, however strong, 
 to pieces, and there would be an open way for another 
 
354 THE AGE OF ELECTRICITY. 
 
 fish, sent immediately on the heels of the first. The 
 telephone bids fair to be a good means of detecting the 
 approach of a submarine torpedo ; for, if one of its ter- 
 minal wires is connected with a submerged plate, the 
 sound of the rapidly approaching fish can easily be heard. 
 This would be of little avail, however, unless some sort 
 of dredging-craft could run quickly in behind the fish, and 
 cut the electric cable ; but in the time which it would take 
 to recognize the approaching danger, and to notify the 
 cutting vessel, supposing the latter to be in perfect 
 readiness, the torpedo would probably get alongside 
 and do its work. The problem is one of great impor- 
 tance, and many inventors are hard at work upon it. 
 
 Military telegraphs are now indispensable to armies in 
 the field. Miles of wire are carried on reels, in specially 
 constructed wagons, which hold also batteries and instru- 
 ments. Some of the wire is insulated so that it can rest 
 on the ground, and thus be laid out with great speed ; 
 while other wire is bare, and is intended to be strung up 
 wherever conveniently possible. For mountain service, 
 the wires and implements are carried by pack-animals ; 
 and often, for reconnoitring, reels of wire are carried 
 like knapsacks on the backs of the men. All modern 
 armies now have a regularly drilled telegraph-corps ; and 
 telegraphic communication is constantly maintained be- 
 tween an advance-guard and the main body of an army, 
 or between different divisions or brigades on the field. 
 During the English operations in Egypt, the advance- 
 guard was not only kept in communication with head- 
 quarters, but with England ; so that, after the battle of 
 Tel-el Kebir, news of the victory was telegraphed to the 
 Queen, and her answer received, within forty-five minutes. 
 
 The telephone in its various forms is also of great mili- 
 tary value. It enables constant communication to be held 
 
OTHER APPLICATIONS OF ELECTRICITY. 355 
 
 between pickets, skirmish-lines, scouting parties, and the 
 officer in general command. It has been proposed to 
 bury sensitive microphones in the earth along roads, 
 around forts and camps, so that the approach or move- 
 ments of a hostile force could instantly be detected. 
 Actual experiment has proved that a delicate apparatus of 
 this sort will render audible the sound of a spade scraping 
 upon the earth, when digging is going on some five hun- 
 dred feet away from the buried instrument ; and the foot- 
 falls of men and horses, and the rumble of wheels, occur- 
 ring at even greater distances, can easily be recognized. 
 
 The most noted of the early experiments in electrical 
 blasting was the destruction of the submerged hull of the 
 ill-fated "Royal George " man-of-war, in 1840. The most 
 famous of recent electrical blasts was the destruction of 
 Flood Rock in the East River, near New- York City, in the 
 fall of 1885. Some idea of the immensity of this work 
 may be derived from the fact that the total area under- 
 mined was over nine acres, and that 21,670 feet of galleries 
 honeycombed the solid rock. In the roof and tops of the 
 piers left to support it, over thirteen thousand holes were 
 made. The explosives used were dynamite and rack-a-rock, 
 a mixture of chlorate of potash and di-nitro-benzole. Into 
 each dynamite cartridge, an electric fuse was placed, filled 
 with fulminate of mercury, and containing a small platinum 
 bridge, which, when the current passes, is heated to red- 
 ness, and the fulminate thus exploded. The entire mine 
 was divided into twenty-four independent circuits, each 
 circuit representing or covering a certain section. Within 
 each circuit were twenty-five fuses or mine-exploders. 
 Each of the twenty-four circuits had its own wire, and the 
 like ends of all the wires were brought together ; the posi- 
 tive ends, for example, being dipped into one cup of mer- 
 
356 THE AGE OF ELECTRICITY. 
 
 cury, and the negative ends into another and a separate 
 cup. It was simply necessary to unite the two cups of 
 mercury by a single wire in circuit with a battery, to send 
 a current through all the circuits simultaneously. The 
 cartridges in the drill-holes were not electrically connected, 
 nor were any fuses arranged in them. The current simply 
 exploded the six hundred " mine-exploders " distributed 
 through the galleries ; and the forty thousand cartridges, 
 containing seventy-five thousand pounds of dynamite and 
 two hundred and forty thousand pounds of rack-a-rock, 
 detonated " by sympathy." 
 
 For marine use, electric lights are employed for the 
 running lights of vessels. Electric telegraphs are utilized 
 to signal directions from the bridges of steamers to the 
 engine-room and helm ; and numerous devices have been 
 contrived, whereby the compass-needle in moving is caused 
 to control an electric circuit which through suitable mechan- 
 ism governs the rudder, so that a vessel can be made to 
 steer herself upon any given course. Various forms of 
 electric logs have been invented, which provide for a con- 
 tinuous registration, on board the ship, of the actual dis- 
 tance travelled through the water. The great English 
 iron-clad "Colossus" was launched by the aid of elec- 
 tricity ; a weight, which in falling removed the dog-shores, 
 being controlled by a large electro-magnet, so that at the 
 proper moment the simple pressure of a button allowed the 
 huge craft to move freely into the water. The propulsion 
 of small vessels by electro-motors has already been referred 
 to. It is probable that these engines will come into more 
 and more extended use afloat for the hoisting and bracing 
 of yards, the lifting of heavy weights, and other work, for 
 which manual labor on sailing-vessels, or steam on steam- 
 ships, is now employed. 
 
OTHER APPLICATIONS OF ELECTRICITY. 357 
 
 For any one who has been to sea, it is not hard to real- 
 ize the terrible odds against any unfortunate who falls into 
 the black darkness of the waves at night from the rigging 
 of a fast vessel. The ship may leave the swimmer a mile 
 or more astern before her speed can even be checked ; and 
 to reverse her course involves sweeping around a circle 
 miles in length. And then how is the man to be found, 
 amid the multitudinous and ever-changing hills and val- 
 leys of the waves ? Here, however, the electric light has 
 proved of splendid utility. A British man-of-war recently 
 was steaming at moderate speed one very dark night, when 
 suddenly the always appalling cry of " Man overboard ! " 
 was raised. Two of the officers, who had seen the sailor 
 fall from the rigging, heroically leaped into the water to 
 his rescue. Almost instantly the electric light on the lofty 
 deck flashed out its great beam, revealing the three men 
 clinging to a life-buoy. As the ship lost her way, and 
 then came about, the brilliant ray followed them ; and so, 
 when the life-boat was lowered, it was simply necessary to 
 steer in the path of the beam to reach the buoy. In six 
 minutes after the alarm was given, the men were saved, 
 the boat hoisted, and the ship once more on her course. 
 
 Among the more important applications of electricity 
 to railway purposes, is that of working automatic signals, 
 which guard the road, and give warning of danger, with- 
 out the intervention of man. It is a requisite of any 
 signal-system, that the normal condition of its signals 
 should indicate danger ; so that in case of any derange- 
 ment of apparatus, accidental or intentional, warning will 
 be given. Thus failure to act will at most stop or check 
 the movement of a train. In Hall's system, an open cir- 
 cuit is employed, and the current which keeps the signals 
 set at " safety " is transmitted over wires. This current 
 
358 THE AGE OF ELECTRICITY. 
 
 being broken by an engine entering a block-section, and 
 touching a circuit-closer, sets the signal at "danger.'* 
 The so-called Union system uses a closed circuit, with an 
 electric current moving through the rails. When a section 
 of road is guarded by this device, the entrance of a loco- 
 motive breaks the current simply by placing its wheels 
 upon the conducting rails, and thereupon visible signals of 
 danger are given ; and when a train approaches a station 
 or crossing, a warning bell is rung. To electric railways 
 and railway telegraphs, reference has already been made. 
 The electric lighting of railway-trains is now accom- 
 plished by the aid of storage-batteries and incandescent 
 lamps ; the batteries being supplied by a small dynamo 
 carried on the locomotive. Electric brakes, which depend 
 upon the attractive energy of electro-magnets being ex- 
 erted to press the "shoes" against the wheels, are used 
 on some European railways. 
 
 The earliest application of electricity to music was prob- 
 ably that made by Pere Laborde in 1755, in his so-called 
 clavecin electrique. This curious instrument is described 
 in Sigaud de la Fond's treatise of 1767, as follows : "A 
 bar of iron insulated on a silken cord carries bells of differ- 
 ent sizes for the different notes, two bells being supplied 
 for each note. One of the two bells is suspended by a 
 brass wire, the other by a thread of silk. The hammer, 
 held by a silken cord, hangs between the two. From the 
 bell suspended by the silk, extends a brass wire, the end 
 of which is fastened by a second cord, and terminates in 
 a ring which receives a small iron lever, which rests on 
 an insulated iron bar. By this arrangement the bell sus- 
 pended by the brass wire is electrified from the iron bar 
 which carries it ; and the other, which is hung from this 
 bar by the silk thread, is electrified by the other iron bar, 
 
OTHER APPLICATIONS OF ELECTRICITY. 359 
 
 on which the lever rests. When a key is pressed down, 
 the lever is raised, and caused to touch the non-insulated 
 bar. At the same instant the hammer is set in motion, 
 and strikes the two bells with such rapidity that a single 
 undulating [si'c] sound is produced, which imitates very 
 closely the tremolo effect of the organ. As soon as the 
 lever falls on the electrified rod, the hammer stops. Thus 
 each key controls a lever, and each lever a pair of bells ; 
 and in this way airs may be played as on any other 
 clavecin." 
 
 The idea of controlling the hammers of a piano by 
 electro-magnets, which should be energized and de-ener- 
 gized from a distant station, was suggested several years 
 ago ; and a glowing prospectus was issued by an electro- 
 musical company which proposed to play any one's piano 
 after a few alterations in its inner mechanism by 
 electricity. There was to be a central station, in which 
 was to be located the single controlling keyboard which 
 governed all the pianos of the various subscribers ; and 
 here noted artists were to play between stated hours. 
 When any subscriber desired music in his parlor, he had 
 only to consult the programme, distributed daily, to learn 
 what morceau was in process of performance, and then 
 turn his switch, when his piano would instantly begin ; so 
 that in the humblest dwelling the choicest productions of 
 the great masters, executed by the Von Bulows and the 
 Liszts and the Rubinsteins of the day, were to be as read- 
 ily available and as familiar as the "Maiden's Prayer" 
 and "Monastery Bells." Of course there were some 
 obvious difficulties attending this scheme ; such, for ex- 
 ample, as that of the possibility of receiving the wrong 
 tunes, the "Dead March in Saul," for example, at a 
 dancing-party, or the last minstrel ditty at a funeral : but 
 the addition of an electric annunciator which would auto- 
 
360 THE AGE OF ELECTRICITY. 
 
 matically exhibit the name of the piece, it was believed, 
 would prevent this trouble. So far as is known, the plan 
 never went into practical effect, although some electro- 
 musical concerts were given, in which half a dozen pianos 
 were played in unison, making much noise but little music. 
 In the explosive concert-performances, such as delight the 
 ears of the throngs at Coney Island and other popular 
 resorts, electricity is an indispensable assistant. To Mr. 
 Patrick Gilmore is probably due the credit of discharging 
 a whole battery of cannon in strict accentuation, with the 
 "Anvil Chorus," by means of electric fuses and wires 
 leading from the conductor's desk ; the effect being, both 
 metaphorically and literally, "stunning." 
 
 The harmonic telegraph, whereby musical sounds can 
 be transmitted between distant points, has already been 
 explained. Electric organs have been constructed, in 
 which the action and stops are entirely controlled by the 
 closing of circuits by the keys, etc. In Grace Church, 
 New York, the chancel organ is placed in a chamber built 
 for the purpose at the angle formed by the east wall of 
 the south transept and the chancel wall. The gallery 
 organ stands at the west end of the church, over the main 
 entrance. The echo organ is situated on the roof, over 
 the intersection of nave and transept. These organs are 
 connected with the keyboards in the chancel, and are thus 
 under the complete control of one performer. A curious 
 contrivance, called a melograph, has been devised by Mr. 
 Carpenter, which both registers and reproduces music. 
 The operator manipulates keys like those of a piano, 
 which control currents which operate perforators in an 
 endless strip of paper, cutting long or short slits accord- 
 ing to the duration of the note struck. This paper pro- 
 ceeds to a second apparatus, where circuit is made only 
 through the openings in the paper strip, and thus only cer- 
 
OTHER APPLICATIONS OF ELECTRICITY. 361 
 
 tain reeds are set in operation, to reproduce the original 
 melody. An electrical recording device has also been 
 invented, designed to rescue the fugitive improvisations of 
 musical genuises from oblivion. Whenever a key is struck, 
 a note is marked telegraphically on a moving strip of 
 paper. 
 
 Possibly the reader, while seated in a theatre or opera- 
 house, and waiting for the curtain to rise, has devoted a few 
 minutes to wondering how the innumerable burners of the 
 great chandelier which hangs from the dome are lighted ; 
 or how, even by the longest of poles, a match can be car- 
 ried to gas-jets located apparently in the most inaccessible 
 places. Then suddenly there is a succession of sharp 
 cracks ; and, before one's eyelids can rise after the in- 
 voluntary wink, every burner is aflame. This is electrical 
 gas-lighting. Electricity is a generous rival. Perhaps 
 because of the inapproachable superiority of its own light, 
 it can afford to help its weaker antagonist. Closer or 
 nearer inspection of the myriad gas-burners of a theatre 
 will show that they are all connected by delicate wires, 
 and that at the tip of every one of them are a couple of 
 metal points, between which the circuit is interrupted. 
 Now, when a powerful electric current is sent into the 
 wire, it travels over the conductor until it reaches one of 
 these breaks, over which it jumps from point to point ; 
 and in its leap a spark appears. The gas is first turned 
 on to all the burners. No matter how many they may be, 
 the passage of the current is so infinitely swift that the 
 spark at the tip of every one of them is made at the same 
 instant, and every outgoing stream of gas is thus ignited 
 at once. This is a very old invention. It appears to 
 have been first made public by one Joseph Beck, in an 
 English scientific paper, in 1839. At the same time it is 
 
362 THE AGE OF ELECTRICITY. 
 
 perhaps the simplest, as well as most commonly used, 
 arrangement of electrical gas-lighting apparatus. There 
 are many more modern contrivances for the same purpose, 
 which display exceptional ingenuity. For example, there 
 are several forms of so-called automatic lighters, which on 
 the first pressure of a button, no matter how far distant 
 from the burner, a communicating wire being present, not 
 only light the gas, but before doing so turn it on. Then, 
 on a second pressure of the same button, the gas is turned 
 off. This has been applied to street-lights, so that all the 
 gas-lamps in a large district can thus be automatically 
 lighted and extinguished without any help from the tradi- 
 tional lamp-lighter and his ladder. Then there are simple 
 little contrivances connected to individual burners, so that 
 it is necessary simply to pull down a hanging wire, or 
 merely to turn on the gas by the cock in the ordinary way, 
 when a little spring is wiped past a metal point on the 
 burner-tip, a spark made, and the gas lighted. Of course 
 it is a great convenience, on going into a dark room, to 
 be saved the hunt for fugitive matches, and to have noth- 
 ing to do but find the fixture, and turn on the gas ; and it 
 is even a greater comfort for paterfamilias to know that 
 when strange noises in the lower part of the house arouse 
 him in the middle of the night, he has not to descend into 
 the darkness to meet an unknown fate, but simply to touch 
 a button by his bedside, when every burner in every room, 
 if he so desires, will blaze, and render his further investiga- 
 tion whether it be for cats or burglars at least free 
 from nameless fears of an unseen and hence mysterious 
 intruder. 
 
 The number of varieties of electric alarms, indicators, 
 and annunciators, is simply legion. Most of them are 
 automatic in their action. Others like the hotel annun- 
 
OTHER APPLICATIONS OF ELECTRICITY. 363 
 
 ciators, which, when a button is pressed in a room, cause 
 a bell to sound in the office, and reveal the number of the 
 apartment whence the signal comes require a closing or 
 breaking of the circuit by hand. The mechanism of all 
 of these contrivances embodies an electro-magnet, which, 
 when the current is established by pressing the button, 
 attracts a metal shutter bearing the number, and thus 
 moves it so that the number becomes visible through an 
 opening in a screen ; or else the magnet acts to release a 
 catch so that the shutter is allowed to fall into view. The 
 automatic contrivances either simply give an alarm as by 
 ringing a bell or exhibiting a signal, or else actually control 
 the power of some contrivance which does certain work. 
 Sometimes an alarm is given, and mechanism operated at 
 the same time. Thus electrical low- water regulators have 
 been devised for steam boilers, which, when the water 
 falls below a certain level, turn on the steam to sound the 
 whistle, and also open the feed valve to let in a supply of 
 water. Other electrical regulators have been arranged in 
 connection with the dampers of furnaces, to open and 
 close them at the proper time. So also, in connection 
 with steam-engines, electrical governors have been adopted, 
 which control the slide-valves and the admission of steam. 
 Nearly all the electrical heat-regulators depend upon the 
 elongation or contraction of a so-called thermostatic bar, 
 made of metals very sensitive to differences in temper- 
 ature ; or upon the movement of the mercury in a ther- 
 mometer-tube. When the heat of an apartment exceeds a 
 certain limit, the bar expands, or the mercury in the ther- 
 mometer rises, and establishes a circuit, through which 
 the current, being free to pass, actuates mechanism for 
 opening a ventilator or damper, and so letting cool air into 
 and hot air out of the chamber. This idea has been very 
 successfully applied to artificial incubators, in which it is 
 
364 
 
 THE AGE OF ELECTRICITY. 
 
 necessary to maintain a temperature of about 102 Fah. 
 very uniformly during the long incubating period. One 
 contrivance of this class is arranged to regulate the 
 temperature of an incubator heated by hot water from a 
 small boiler, with great accuracy. The damper opens and 
 shuts responsive to even a fraction of a degree difference 
 in temperature, and the proportion of eggs hatched often 
 as high as eighty-two per cent shows how perfectly the 
 sentinel current does its work. 
 
 In some cases the body to be expanded by heat is made 
 
 Fig. 143. 
 
 in the form of a spring as at S, in Fig. 143. When the 
 temperature rises, the end of the spring makes contact 
 with the point P, and thus establishes the electrical circuit 
 from one wire to another. 
 
 Burglar-alarms are now in every-day use. Some of 
 them depend upon the bringing into contact of two pieces 
 of metal by the opening of a door or window, thus estab- 
 lishing the circuit from a battery to an alarm-bell and 
 to an annunciator showing the location of the place of 
 attempted entry. Others depend upon the breaking of a 
 closed circuit, releasing some form of alarm. Others are 
 especially adapted to safes, so that in event of a burglar 
 breaking in, or even tampering with the receptacle, the 
 
OTHEE APPLICATIONS OF ELECTRICITY. 365 
 
 alarm is caused to sound. Door-mats and matting are 
 also constructed with contact plates brought together by 
 the pressure of the foot of a person stepping on them, 
 and thus establishing a current to a bell which thus gives 
 warning of any one entering or moving about a protected 
 room. In large cities where district telegraph companies 
 are in existence, arrangements are made whereby all the 
 doors and windows of a residence can be connected with 
 an alarm at a central station ; so that the occupant can 
 leave the house untenanted, with confidence that any bur- 
 glar attempting to enter will at the same time, and indeed 
 without his own knowledge, signal his own proceedings to 
 the station, whence a policeman will be sent after him long 
 before he can do any mischief. 
 
 In brief, there are almost as many alarms, regulators, 
 and indicators, as there are special circumstances needing 
 them. One of the most ingenious contrivers of appara- 
 tus of this sort was the famous French conjuror Robert 
 Houdin, who retired, after his eventful career, to a charm- 
 ing mansion called the "Priory," in the village of St. 
 Gervais. There he amused himself by devising a variety 
 of ingenious electrical contrivances, many of which are 
 graphically described in the following extract published 
 several years ago : 
 
 " The main entrance to the Priory is a carriage-way closed by a 
 gate. Upon the left of this is a door for the admission of visitors 
 on foot : on the right is placed a letter-box. The mansion is sit- 
 uated a quarter of a mile distant, and is approached by a broad and 
 winding road well shaded with trees. 
 
 " The visitor presenting himself before the door on the left sees 
 a gilt plate bearing the name of Robert Houdin, below which is 
 a small gilt knocker. He raises this according to his fancy; but, 
 no matter how feeble the blow, a delicately tuned chime of bells 
 sounding through the mansion announces his presence. When 
 the attendant touches a button placed in the hall, the chime ceases, 
 
366 THE AGE OF ELECTRICITY. 
 
 the bolt at the entrance is thrown back, the name of Robert Hou- 
 din disappears from the door, and in its place appears the word 
 * entrez ' in white enamel. The visitor pushes open the door, and 
 enters ; it closes with a spring behind him, and he cannot depart 
 without permission. 
 
 " This door in opening sounds two distinct chimes, which are 
 repeated in the inverse order in closing. Four distinct sounds 
 then, separated by equal intervals, are produced. In this way a 
 single visitor is announced. If many come together, as each holds 
 the door open for the next the intervals between the first two and 
 the last two strokes indicate with great accuracy, especially to a 
 practised ear, the number who have entered ; and the preparation 
 for the reception is made accordingly. A resident of the place is 
 readily distinguished ; for, knowing in advance what is to occur, 
 he knocks, and at the instant when the bolt slips back he enters. 
 The equidistant strokes follow immediately the pressing of the 
 button. But a new visitor, surprised at the appearance of the 
 word 'entrez,' hesitates a second or two, then presses open the door 
 gradually, and enters slowly. The four strokes, now separated by 
 a short interval, succeed the pressing of the button by quite an 
 appreciable time ; and the host makes ready to receive a stranger. 
 The travelling beggar, fearful of committing some indiscretion, 
 raises timidly the knocker; he hesitates to enter, and when he does 
 it is only with great slowness and caution. This the chimes un- 
 erringly announce. It seems to persons at the house as if they 
 actually saw the poor mendicant pass the entrance; and in going 
 to meet him they are never mistaken. 
 
 "When a carriage arrives at the Priory, the driver descends 
 from his box, enters the door by the method now described, and is 
 directed to the key of the gate by a suitable inscription. He un- 
 locks the gate, and swings open its two parts; the movement is 
 announced at the house, and on a table in the hall bearing the 
 
 words, 'The gate is ,' appears the word 'open' or 'closed,' 
 
 according to the fact. 
 
 "The letter-box, too, has an electric communication with the 
 house. The carrier, previously instructed, drops in first all the 
 printed matter together; then he adds the letters one by one. Each 
 addition sounds the chimes ; and the owner, even if he has not yet 
 risen, is apprised of the character of his despatches. To avoid 
 sending letters to the village, they are written in the evening; and 
 a commutator is so arranged, that, when the carrier drops the mail 
 
OTHER APPLICATIONS OF ELECTRICITY. 367 
 
 into the box the next morning, the electricity, in place of sound- 
 ing the chimes in the house, sounds one over his head. Thus 
 warned, he comes up to the house to leave what he has brought, 
 and to take away the letters ready for mailing. 
 
 " ' My electric doorkeeper then [says Houdin] leaves me nothing 
 to be desired. His service is most exact; his fidelity is thoroughly 
 proven; his discretion is unequalled; and as to his salary, I doubt 
 the possibility of obtaining an equal service for a smaller remuner- 
 ation.' 
 
 " M. Houdin possesses a young mare whom he has named 
 Fanchette. To this animal he is much attached, and cares for her 
 with the greatest assiduity. A former hostler, who was an active, 
 intelligent man, had become devoted to the art so successfully prac- 
 tised by his employer in previous years. His knowledge, however, 
 was confined to a single trick; but this he executed with rare abil- 
 ity. This trick consisted in changing the oats of his master into 
 five-franc pieces. To prevent this peculation, the stable, distant 
 from the house seven or eight rods, is connected with it by elec- 
 tricity so that by means of a clock fixed in the study the necessary 
 quantity of food is supplied to the horse, at a fixed hour, three 
 times a day. The distributing apparatus is very simple, consisting 
 of a square box, funnel-shaped, which discharges the oats in the 
 proportion previously regulated. Since the oats are allowed to fall 
 only when the stable-door is locked, the hostler cannot remove 
 them after they are supplied; nor can he shut himself in the sta- 
 ble, and thus get the oats, as the door locks only upon the outside. 
 Moreover he cannot re-enter, and abstract them, because an alarm 
 is caused to sound in the house if the door be open before the oats 
 are consumed. 
 
 ''This study clock transmits the time to two dial-plates. One, 
 placed upon the front of the house, gives the hour of the day to 
 the neighborhood; the other, fastened to the gardener's lodge facing 
 the house, gives the time to its inmates. Several smaller dials, 
 operated similarly, are placed in various apartments. They all, 
 however, have but a single striking part; but this is powerful 
 enough to be heard over the entire village. Upon the top of the 
 house is a tower containing a bell on which the hours of meals are 
 announced. Below this is a train of wheel-work to raise the ham- 
 mer. To avoid the necessity of winding up the weight every day, 
 an automatic arrangement is employed which utilizes a force ordi- 
 narily lost. Between the kitchen, situated upon the ground-floor, 
 
368 THE AGE OF ELECTRICITY. 
 
 and the clock-work in the garret, there is a contrivance so arranged 
 that the servants in going to and fro about their work wind up the 
 weight without being conscious of it. An electric current, set in 
 motion by the study regulator, raises the detent, and permits the 
 number of strokes indicated by the dial. The manner of distrib- 
 uting the time from the study, Houdin finds very useful. When, 
 for any reason, he wishes the meals hurried or retarded, he presses 
 a secret key, and the time upon all the dials is altered to suit his 
 convenience. The cook finds often that the time passes very rap- 
 idly; while a quarter of an hour or more, not otherwise attainable, 
 is gained by M. Houdin. 
 
 " Every morning this clock sends, at different hours, electric 
 impulses to awaken three persons, the first of whom is the gar- 
 dener. But, in addition, this apparatus forces them to rise, by con- 
 tinuing to sound until the circuit is broken by moving a small key 
 placed at the farther end of the room. To do this, the sleeper 
 must rise, and then the object sought is accomplished. 
 
 "The poor gardener is almost tormented by this electricity. 
 The greenhouse is so arranged that he cannot raise its temperature 
 above 50 F., or let it fall below 37 F., without a record in the 
 study. The next morning Houdin says to him, ' Jean, you had too 
 much heat last night; you will scorch my geraniums ;' or, 'Jean, 
 you are in danger of freezing my orange-trees; the thermometer 
 descended to three degrees below zero (29 F.) last night.' Jean 
 scratches his head, and says nothing; but he evidently regards 
 Houdin as a sorcerer. 
 
 "A similar thermo-electric apparatus placed in the woodhouse 
 gives warning of the first beginning of an incendiary fire. As a 
 protection against robbers, all the doors and windows of the house 
 have an electric attachment. This so connects them with the 
 chimes, that the bells continue to sound as long as the door or 
 window remains open. During the day-time the electric com- 
 munication is interrupted; but at midnight, the hour of crime, it 
 is re-established by the study clock. When the owner is absent, 
 however, the connection is permanent. Then the opening of the 
 door or window causes the great bell to sound like a tocsin. Every- 
 body is aroused, and the robber is easily captured. 
 
 " A pistol-gallery is upon the grounds, and Houdin often amuses 
 himself in shooting. But in place of the ordinary methods of 
 announcing a successful shot, a crown of laurels is caused to appear 
 suddenly above the head of the marksman. A deep road passes 
 
OTHER APPLICATIONS OF ELECTRICITY. 369 
 
 through the park, which it is sometimes necessary to cross. On 
 reaching it, no bridge is to be seen; but upon the edge of the 
 ravine a little car appears, upon which the person desiring to cross 
 places himself. No sooner is he seated than he is rapidly trans- 
 ported to the opposite bank. As he steps out, the car returns 
 again to the other side. This being a double-acting arrangement, 
 the same aerial method is made use of in returning. 
 
 " I finish here my description," says Houdin. " Ought I not to 
 reserve some few and unexpected details for the visitor who comes 
 to raise the mysterious knocker below which, it will be remem- 
 bered, is engraved the name of Robert Houdin ? " 
 
 Electricity is employed in timepieces in three ways. 
 Thus it is made use of as a motive-power, to swing a 
 pendulum, and replace the springs or weights of an ordi- 
 nary clock. Or, it is employed for transmission : a cen- 
 tral clock sends an electric current every second, half- 
 minute, or minute, to one or more dials placed at a 
 distance, which cause the hands to advance respectively 
 a second, a half-minute, or a minute. Or, electricity is 
 used to regulate clocks and dials propelled by ordinary 
 weights and springs, and adjusts the hands every hour, 
 every six hours, or every twenty- four hours. It is this 
 system of synchronism which has been adopted by the 
 city of Paris for the public clocks. It was first invented 
 by Dr. Locke of Cincinnati in 1848 ; and Congress 
 awarded him a premium of ten thousand dollars for his 
 invention, designing to use it in astronomical researches 
 and in determining longitude. 
 
 Time-signals are now transmitted to every important city 
 and to all railroads in Great Britain, from the Greenwich 
 Observatory. In other parts of Europe, especially in 
 Germany and France, electric clocks are everywhere used. 
 In Paris, the standard clock of the National Observatory 
 is connected by special lines with about thirty "horary 
 centres." At these points are placed clocks, the pendu- 
 
370 THE AGE OF ELECTRICITY. 
 
 lums of which are continuously controlled by impulses 
 sent every second from the observatory ; and they, in their 
 turn, distribute their beats to numerous stations in the 
 vicinity. The whole city is thus supplied with time uni- 
 form and correct to a second. 
 
 In the United States, time-signals are sent from the 
 standard clock in Cambridge Observatory to many sta- 
 tions in Boston, and at intervals are transmitted over 
 the telephone-lines. Standard time is also marked on the 
 tapes of the stock-exchange tickers. From the National 
 Observatory in Washington, time-signals are sent to New 
 York ; and the operator at this station despatches the cur- 
 rent which drops the time-ball on the Western Union Tele- 
 graph Building in the metropolis, two hundred and forty 
 miles distant. The ball, after being hoisted, is held by a 
 simple catch mechanism which is controlled by an electro- 
 magnet. At the moment of noon, New- York time, the 
 officer in charge at Washington closes the circuit, the mag- 
 net retracts its armature, the catch is slipped, and the ball 
 drops. The instant the ball reaches the base of the pole, 
 the fact is automatically telegraphed to Washington. 
 Owing to the great height of the ball when raised, it is 
 visible for many miles around ; and directly or indirectly 
 the clocks and watches of nearly three millions of people 
 are thereby kept from straying very far from the true 
 time. 
 
 In referring to some military uses of electricity, we have 
 mentioned the very remarkable apparatus which records 
 minute intervals of time. This is the electro-chronograph ; 
 and by its aid not only is time measured with wonderful 
 exactitude, but by its recording apparatus it enables us to 
 note the precise instant when an event occurs. This is of 
 great value to astronomers in securing a record, for ex- 
 ample, of the transit of a heavenly body across the merid- 
 
OTHER APPLICATIONS OF ELECTRICITY. 371 
 
 ian ; for the observer has only to keep his eye on the 
 object, and tap with his finger a button or key at the 
 proper moments. 
 
 Who, in his youthful days, has not read the story of 
 Aladdin and that wonderful lamp which procured such 
 marvellous things for its lucky owner? The fervid ima- 
 gination of the Oriental romancer fairly runs riot in de- 
 scribing the "forty basins of massy gold;" and the 
 beautiful slaves "bearing large golden basins filled with 
 all sorts of jewels, each basin being covered with a silver 
 stuff embroidered with flowers of gold;" and the gor- 
 geous edifice with " its treasury filled with bags of money, 
 the palace with the most costly furniture, and the stables 
 with the finest horses in the world." And all this from 
 the happy thought of a thrifty dame to rub the lamp clean ; 
 for it is only when the lamp is rubbed, that the " genie of 
 gigantic size" appears, and the feast of wonders begins. 
 No doubt we think in our boyish wisdom, that such things 
 are all very well to read about, and a great many times 
 too ; but of course we know that such marvels are not to 
 be taken in sober earnest. 
 
 But, O reader of maturer years, did not a "genie of 
 gigantic size," whom we have named Electricity, come to 
 us if not at the rubbing of a lamp, certainly at the rub- 
 bing of a bit of amber? And what did Aladdin's genie 
 do half as wonderful as ours has done? If Aladdin's 
 sprite could transport him from place to place, cannot 
 ours do as much for us ? and very much more, for it can 
 carry our very thoughts, even our spoken words, perhaps 
 some day our faces. And as for the wealth it has showered 
 upon us, who can estimate the value to humanity of the 
 telegraph alone, all its other works aside? The rash re- 
 quest to seek the "roc's egg of the Caucasus " marked a 
 
372 THE AGE OF ELECTRICITY. 
 
 limit to the power of the fabled Afrite. Who will set 
 metes and bounds to the new power and potency which 
 comes to answer our 
 
 "best pleasure: be't to fly, 
 To swim, to dive into the fire, to ride 
 On the curled clouds" ? 
 
 "It maybe said," writes Priestley, "that there is a 
 ne plus ultra in every thing, and therefore in electricity. 
 It is true, but what reason is there to think that we have 
 arrived at it ? " 
 
 And to-day, entering as we are upon the very Age of 
 Electricity, surrounded on all sides by its marvels, famil- 
 iar with them when the mere fact of such familiarity in 
 itself surprises us, that question asked one hundred and 
 twenty years ago, in the feeblest infancy of the science, 
 is as unanswerable now as then. 
 
INDEX. 
 
 Academy, French: award to 
 Volta, 32; to Bell, 139; refuses 
 to consider Jobard's lamp, 138; 
 on Crosse's insects, 65. 
 
 Acoustic telephone, 276; vibra- 
 tions, 282. 
 
 Accumulation of electricity by 
 animals, 30; in Leyden-jar, 15. 
 
 Accumulator. See Secondary 
 battery and Leyden-jar and 
 Auto-accumulator. 
 
 Addison refers to telegraph, 208. 
 
 Air-pump, Sprengel's, 140. 
 
 Alarms, electric, 362. 
 
 Amber, attraction of, 8; excita- 
 tion of, 4; legend of, 2; soul, 1. 
 
 Ampere, the, 40; how measured, 
 41. 
 
 Ampere, Professor, experiments, 
 85; galvanometer, 211. 
 
 Ancients, knowledge of elec- 
 tricity, 5; of magnet, 69. 
 
 Animals, effects of electricity 
 on, 16, 18, 24, 28, 58, 335. 
 
 Annunciators, 362. 
 
 Arago, experiments on electro- 
 magnet, 85. 
 
 Arc, incandescence, system, 144. 
 
 Arc light. See Light, electric. 
 
 Arc, voltaic, 130; E. M. F. of, 
 132; color, 131; temperature, 
 131. 
 
 Armature, 81; dynamo, induc- 
 tion in, 101; polarized, 82; 
 Siemens's, 109. 
 
 Atmosphere, magnetic, 68, 77. 
 
 Atmospheric battery, 60. 
 
 Attraction, magnetic, 72. 
 
 Auto-accumulator, 60. 
 
 Bacon, Lord, on Gilbert's dis- 
 coveries. 7. 
 
 Bain, automatic telegraph, 241. 
 
 Balloons, electric, 176, 180; elec- 
 tric lighting of, 147. 
 
 Barlow, experiments on tele- 
 graph, 212. 
 
 Barnacles, removing, by elec- 
 tricity, 63. 
 
 Bath, electroplating, 195. 
 
 Battery, cost of motors driven 
 by, 165; frog, 336; galvanic, 
 35; heat, 207; storage, 201; 
 voltaic cup, 32. See also Gal- 
 vanic cell. 
 
 Beccaria, experiments on animal 
 electricity, 28. 
 
 Bell, electric, 170. See also 
 Alarms. 
 
 Bell, Professor A. G., telephonic 
 investigations, 291. 
 
 Bevis, Leyden-jar, 17. 
 
 Blasting, electric, 355. 
 
 Boat, electric, 160, 176. 
 373 
 
374 
 
 INDEX. 
 
 Bonnelli telegraph, 245. 
 
 Bottle, electric, 20. 
 
 Bourbouze electro-motor, 155. 
 
 Bourseul, suggestion of tele- 
 phone, 277. 
 
 Boy, electric, 340. 
 
 Boyle, Robert, electric discov- 
 eries, 8, 122. 
 
 Boze, beatification, 125; electric 
 martyrdom, 16; invention of 
 prime conductor, 13. 
 
 Brard carbon-burning cell, 54. 
 
 Brush discharge, the, 128. 
 
 Brush arc light, 132; dynamo, 
 115; secondary battery, 206. 
 
 Buckling in storage cells, 206. 
 
 Buffon, experiments with light- 
 ning, 23. 
 
 Bunsen, galvanic cell, 52. 
 
 Buoy, electric light, 147. 
 
 Cabseus, electric discoveries, 8. 
 
 Cable, Atlantic, 249-256; circuit 
 of, 260; first suggestion of, 249; 
 picking up, 253; submarine, 
 first, 248; submarine, construc- 
 tion of, 256; retardation in, 
 256; telephoning on, 310. 
 
 Callaud, galvanic cell, 51. 
 
 Candle, electric, 145. 
 
 Cannon, firing by electricity, 346. 
 
 Carbon, burned in galvanic cells, 
 53; burning battery, 61; ele- 
 ments, 49; filaments, 139; in 
 telephones, 306. 
 
 Carlisle, discovery of electrolysis, 
 183. 
 
 Carriages, electric lighting of, 147. 
 
 Cartridge, electrolytic, 347. 
 
 Case, W. E., heat battery, 207; 
 secondary battery, 206. 
 
 Casselli telegraph, 245. 
 
 Cavendish on lightning-rods, 26. 
 
 Cell, galvanic, 35. See Galvanic 
 cell. 
 
 Chronograph, electric, 348, 370. 
 
 Circuit, 35; telegraphic, 227. 
 
 Clavecin, electrical, 358. 
 
 Clocks, electrical, 369. 
 
 Coils, magnetic effect of, 79; 
 currents in 92-101; induc- 
 tion, 325. 
 
 Collinson, Franklin's letters to, 
 18, 22. 
 
 Colt, submarine telegraph, 248. 
 
 Commutator, 104. 
 
 Compass, mariner's, 70. 
 
 Condenser, 31, 259; telephone, 
 308. 
 
 Conduction, discovery of, 10. 
 
 Conductors, 39; prime, 13. 
 
 Cotugno, experiments, 30. 
 
 Coulomb, the, 40. 
 
 Cowper, telegraph, 246. 
 
 Crookes, experiments with high 
 tension electricity, 330. 
 
 Crosse, electric insects, 64; ex- 
 periments with lightning, 332. 
 
 Cunreus, experiments with Ley- 
 den- jar, 15. 
 
 Cures, electric, 28, 30. 
 
 Current, magnetic effect of, 77; 
 path of, in cell, 45; qualities 
 of, 40. 
 
 Currents, alternating, 104; dan- 
 gerous, 341 ; due to mechanical 
 motion, 92. 
 
 Daft, electric locomotive, 173. 
 D'Alibard, experiments with 
 
 lightning, 23. 
 Dal Negro, electro-motor, 154. 
 
INDEX. 
 
 375 
 
 Daniell, galvanic cell, 50. 
 
 Davenport, electro-motor, 157. 
 
 Davidson, electric locomotive, 
 162. 
 
 Davy, Sir H. Discovery of arc 
 light, 128; electrolytic produc- 
 tion of metals, etc., 187; on 
 protecting vessels, 63. 
 
 Death by electricity, 341. 
 
 De Moleyn's electric lamp, 136. 
 
 De la Rue, galvanic battery, 59. 
 
 De Lor, experiments with light- 
 ning, 23. 
 
 Depolarization of cells, 59. 
 
 " De Sauty," 250. 
 
 Diamond, electric light from, 122. 
 
 Diplex telegraph, 237. 
 
 Discharges, electric, compared, 
 57; high power, 325. 
 
 Dolbear, condenser telephone, 
 308. 
 
 Drawbaugh, telephonic inven- 
 tions. 302. 
 
 Duchemen, buoy battery, 62. 
 
 Dufay, discoveries of, 11. 
 
 Duplex telegraph, 236. 
 
 Dyer, telegraph, 216. 
 
 Dynamic electricity, 57. 
 
 Dynamo, the, 100; and battery 
 compared, 98; and magneto- 
 electric machines compared, 
 100; and electro-motors com- 
 pared, 168; Brush, 115; direct 
 current, 106; Edison, 116; effi- 
 ciency of, 107; Gramme, 106; 
 operation and construction of, 
 112; classification of, 111; Sie- 
 mens, 108, 114; Wilde, 110. 
 
 Earth batteries, 62; for electric 
 lighting, 137. 
 
 Earth currents, 258; return, 225. 
 
 Eatables as galvanic elements, 65. 
 
 Edison, automatic telegraph, 243; 
 chemical telegraph, 308; lamps, 
 140; microphone, 302; phono- 
 graph, 320; quadruplex tele- 
 graph, 237; railway telegraph, 
 269. 
 
 Eel, electric, 342. 
 
 Electric light. See Light, elec- 
 tric. 
 
 Electricity, 35; from magnets, 
 88; medical uses of, 335; of 
 human body, 338; utilizations 
 of, 333. 
 
 Electrics, 7. 
 
 Electrodes, 182; in telephones, 
 306. 
 
 Electro-generative combustible, 
 54. 
 
 Electrolysis, 182; Cruickshank's 
 discoveries, 184; Davy's dis- 
 coveries, 185; delusions con- 
 cerning, 186; discovery of, 
 182; Faraday, laws of, 189; 
 phenomena of, 187; Hitter's 
 experiments, 184; theory of, 
 190. 
 
 Electrolyte, 35. 
 
 Electro-magnet, the, 68; Am- 
 pere's experiments, 5; Ara- 
 go's experiments, 85; Henry's 
 experiments, 86; how made, 
 83; Joule's, 84; polarity of, 80; 
 strength of, 84; Sturgeon's, 86. 
 
 Electro-metallurgy, 182; Bird's 
 discoveries, 192; De la Rue's 
 discoveries, 192; claimants of 
 invention of, 192. 
 
 Electro-motive force, 39; of gal- 
 vanic cells, 52. 
 
376 
 
 INDEX. 
 
 Electro-motor, 152; advantages 
 of, 174; Bourbouze's, 155; cost 
 of, compared Avith galvanic 
 batteries, 1(55; Dal Negro's, 
 154; Davenport's, 157; effi- 
 ciency of, 170; first rotary, 
 150; Froment's, 159; Henry's, 
 154; McGawley's, 156; princi- 
 ples of, 153, 166. 
 
 Electropborus, the, 31. 
 
 Electroplating, 192. 
 
 Electro therapeutics, 3, 5, 28, 30, 
 335. 
 
 Electrotyping, 193. 
 
 Elements in galvanic cell, 35. 
 
 Elkingtons, electroplating, 193. 
 
 Engine, electro-magnetic, 152. 
 
 Everett, E., oration on submarine 
 telegraph, 247. 
 
 Eye, Siemens's artificial, 316. 
 
 Faraday, discovery of laws of 
 electrolysis, 189; on magneto- 
 electricity, 88; Mayo's im- 
 promptu on, 89; on strength 
 of galvanic cell, 58; test of 
 Davenport's motor, 158; theory 
 of earth return, 226; vollam- 
 eter, 200. 
 
 Faure, secondary battery, 205. 
 
 Feast, Franklin's electric, 19. 
 
 Field, Cyrus W., account of re- 
 gaining cable, 254. 
 
 Field-magnets, 100; of force, 75. 
 
 Filament, carbon, 139. 
 
 Fire, electricity supposed to be, 
 50. 
 
 Fireplaces, electricity in, 53. 
 
 Foucault, electric-light regulator, 
 129. 
 
 Fountain, electric, 150. 
 
 Franklin, early telegraph experi- 
 ments, 209; electric feast, 19; 
 explains Leyden-jar, 19; kite 
 experiment, 21 ; letters to Col- 
 linson, 22; on George III., 26; 
 theory of electricity, 19; upsets 
 Pivati's tube experiments, 339. 
 
 Franklin institute, report on tele- 
 graphs, 215. 
 
 Frog's legs, electric phenomena 
 of, 28. 
 
 Froment electro-motor, 159. 
 
 Fuse, electric, 348. 
 
 Galvani, 28, 31. 
 
 Galvanic battery, and boiler, 
 and dynamo compared, 52; 
 arrangement of, 43; largest, 
 63. 
 
 Galvanic cell, the, 41; Bunsen's, 
 52 ; Callaud's, 51 ; carbon 
 burned in, 53, 61; Daniell's, 
 50; gravity, 51; Grenet's, 59; 
 Leclanche's, 49; polarization 
 of, 47, 58; life supposed to be 
 generated in, 64; of the future, 
 62; resistance on, 46; Smee's, 
 48; strength of current of, 58; 
 water analogy, 44; work of 
 the, 43; with eatables as ele- 
 ments, 65. 
 
 Galvanic cells, electro-motive 
 force of, 52. 
 
 Galvanism, 29. 
 
 Galvanometer, Thomson's, 261; 
 poem on, 263. 
 
 Gas battery, 59. 
 
 Gas lighting, electric, 59. 
 
 Gilbert, "De Magnete," 7. 
 
 Gnomon, electric, 24. 
 
 Gold plating, 197. 
 
INDEX. 
 
 377 
 
 Gordon, invents cylinder electric 
 
 machine, 13. 
 Gramme, ring, 106. 
 Gravesande theory of electricity, 
 
 10. 
 
 Gravity, galvanic cell, 51. 
 Gray, Elisha, liquid telephone, 
 
 300. 
 Gray, Stephen, discoveries, 10, 
 
 209. 
 Great Eastern, laying cable by, 
 
 254. 
 
 Greeks, knowledge of amber, 2. 
 Grenet galvanic cell, 49. 
 Grove gas battery, 59; galvanic 
 
 cell, 161. 
 
 Guericke, Von, discovery of elec- 
 tric repulsion, 8 ; produces 
 
 electric light, 122. 
 Gummert, discovery of electric 
 
 light in vacua, 127. 
 
 Hair, effect of electricity on, 9. 
 
 Harmonic telegraph, 238. 
 
 Hawkesbee, electric machine, 15; 
 experiments on electric light, 
 124. 
 
 Heat battery, Case's, 188. 
 
 Henry, Joseph, experiments on 
 electro -magnet, 86; on elec- 
 tro-motors, 154; on telegraph, 
 212. 
 
 Houdin, electric alarms, 305. 
 
 Hughes, Professor, induction 
 balance, 314; microphone, 300; 
 sonometer, 314. 
 
 Incandescence arc system, 144. 
 Incandescent electric lamps, 136. 
 Incubator, electric, 363. 
 Induction balance, 314; coils, 
 
 306, 326, 329; in telephone 
 lines, 309; magnetic, 72. 
 
 Insulation, discovery of, 11. 
 
 Insulators, 39, 248. 
 
 Insects, electrical, Crosse's, 64. 
 
 Jablochkoff, atmospheric bat- 
 tery, 60; auto-accumulator, 60; 
 candle, 145; carbon-burning 
 cell, 53. 
 
 Jack, electric, 20. 
 
 Jacobi, discoveries in electro- 
 metallurgy, 192; electric boat, 
 160. 
 
 Jamin, magnet, 86. 
 
 Jenkin, telpherage, 177. 
 
 Jordan, discoveries in electro- 
 metallurgy, 192. 
 
 Killing of animals by shocks, 18. 
 
 Kite, Franklin's, 21. 
 
 Kleist, von, discovery of Leyden- 
 
 jar, 15. 
 Kendall, carbon battery, 61. 
 
 Lamp, electric, Foucault's regu- 
 lator, 129; Brush's, 132; Sie- 
 mens's, 133; Soleil, 146; De la 
 Rue's, 138; incandescence arc, 
 144; incandescent, 136; incan- 
 descent distribution of current 
 in, 143; duration of, 151; in- 
 candescent, Edison's, 142; in- 
 candescent, Jobard's, 138 ; 
 incandescent, construction of, 
 139; incandescent, Muthel's, 
 143; incandescent, Swan's, 142; 
 incandescent, surgical, 148. 
 
 Launching by electricity, 356. 
 
 Laws of electricity, 35. 
 
 Leyden-jar, 15. 
 
378 
 
 INDEX. 
 
 Light, conversion of electricity 
 into, 119. 
 
 Light, electric, applications of, 
 146; arc, 128; at sea, 356; 
 Boze's, 126; by earth batteries, 
 137; candle, 145; cost of, 151; 
 distribution of current, 143; 
 early modes of producing, 122; 
 economy of, 151; Edison's ex- 
 periments, 140; first from gal- 
 vanic current, 128; from dia- 
 mond, 122 ; genesis of, 8 ; 
 Hawksbee's experiments, 122; 
 incandescence arc, 144; incan- 
 descent, 136 ; influence on 
 vegetation, 150; in lighthouses, 
 135; in vacuo, 127; from mer- 
 cury jet, 123; photographs by, 
 129; spark, 146; statistics of, 
 151 ; theatrical effects by, 130, 
 149; theory of, 120; towers for, 
 137; Wake's experiments, 124. 
 
 Lightning, electro-motive force 
 of, 59; fusing metals by, 332; 
 identity with electricity, 9, 21 ; 
 rods, 25. 
 
 Loadstone, 70. 
 
 Locomotive, electric, Daft's, 173; 
 Davidson's, 162; Hall's, 163; 
 Lillie's, 163; of 1845, 162; 
 Page's, 163 ; Siemens' s, 171 ; 
 Sprague's, 174. 
 
 Lyncurium, 5. 
 
 Lyre, Wheatstone's, 275. 
 
 Machine, frictional electric, 12, 
 58, 325. 
 
 Magnet, currents produced by, 88 ; 
 Geilbert on the, 7; Jamin's, 
 86; Newton's, 86; origin of 
 the, 69; permanent and elec- 
 
 tro, compared, 80; strength of 
 86. 
 
 Magnetic motors, 71. 
 
 Magnetism and electricity, iden- 
 tity of, 33; conversion of, 68; 
 known to ancients, 3. 
 
 Magnetization, 85. 
 
 Magneto-electricity, 88-96. 
 
 Magneto-electric machines, 90- 
 112. 
 
 Magneto-induction, 94. 
 
 Medicine, electricity in, 28, 30, 
 335. 
 
 Microphone, 300. 
 
 Middlings-purifier, electric, 331. 
 
 Mines, electricity in, 148, 348. 
 
 Minus electricity, 19. 
 
 Morse, S. F. B., 217, 248. 
 
 Motion, converted into electri- 
 city, 97; transmitting, 272. 
 
 Motors. See Electro-motors. 
 
 Motors, magnetic, 71-164. 
 
 Music, electric, 358. 
 
 Needle telegraph, 224. 
 
 Needling, 206. 
 
 Negative electricity, 11. 
 
 Newton, Sir I., magnet, 86; elec- 
 tric discoveries, 8. 
 
 Nicholson, discovery of electro- 
 lysis, 183. 
 
 Nickel-plating, 196. 
 
 Nobili, rings, 189. 
 
 Nollet, Abbe, 18, 20, 25. 
 
 Ocean, in galvanic cell, 62. 
 Odor, electrical, 336. 
 Oersted, 33. 
 
 Ohm, the, 40; laws of, 39; stand- 
 ard, 40. 
 Organ, electric, 358, 
 
INDEX. 
 
 379 
 
 Pacenotti, ring, 160. 
 
 Page, Professor, electro-music, 
 277; electric locomotive, 163. 
 
 Peltier effect, 56. 
 
 Phonograph, the, 320. 
 
 Phosphorus, mercurial, 123. 
 
 Photophone, the, 314. 
 
 Photographs by electric light, 
 129-148. 
 
 Piano, electric, 358. 
 
 Pile, voltaic, 31 ; Zamboni's, 63. 
 
 Pixii, magneto-electric machine, 
 90. 
 
 Planta, electric machine of, 13. 
 
 Plante, secondary cell, 204. 
 
 Plants, effect of electricity on, 
 150. 
 
 Plus electricity, 19. 
 
 Potential, electric, 36. 
 
 Polarity of compass, 8; of mag- 
 nets, 71. 
 
 Polarization of cells, 47. 
 
 Poles, magnetic, 71. 
 
 Positive electricity, 11. 
 
 Raia torpedo, 342. 
 
 Railway, electric, Daft, 173 ; 
 Hall's, 163; Lillie's, 163; in 
 United States, 173; of 1845, 
 162; Siemens' s, 171 ; Sprague's, 
 174. 
 
 Railway signals, electric, 357. 
 
 Railway telegraphs, 267. 
 
 Railway telepherage, 179. 
 
 Recording telegraph, 229. 
 
 Refining, electro, 197. 
 
 Regulator, Foucault's, 129. 
 
 Reis, telephone investigations, 
 280. 
 
 Relay, telegraph, 232. 
 
 Repeater, telegraph, 234. 
 
 Repulsion, electrical, 8. 
 Resinous electricity, 11. 
 Resistance, 39; interval of cells, 
 
 46. 
 
 Retardation in cables, 256. 
 Reynier, secondary battery, 205. 
 Ronalds, telegraph, 210. 
 Royal Society criticises Franklin, 
 
 22; refuses recognition of Boze, 
 
 127. 
 
 Rechmann, death of, 24. 
 Ritter, electrolytic discoveries, 
 
 184, 203. 
 
 Sauer, sunlight cell, 66. 
 
 Schulze, Professor, on Crosse 
 insects, 65. 
 
 Secondary battery, 201 ; Brush's, 
 206; Case's, 206; defects of, 
 206; Faure's, 205; Plante's, 
 204; Sellon's, 206 ; Reynier' s, 
 205. 
 
 Seebeck, discovery of thermopile, 
 55. 
 
 Sellon secondary battery, 206. 
 
 Ships, electric lighting of, 147. 
 
 Shocks from Leyden-jar, 18. 
 
 Siemens arc light, 133; amateur, 
 110; artificial eye, 316; dy- 
 namo, 108; electric locomotive, 
 171; submarine cable, 248. 
 
 Sight, electric, 347. 
 
 Signals, railway, electric, 357. 
 
 Silk, discovery of, as insulator, 
 11. 
 
 Siphon recorder, 261. 
 
 Scemmering, telegraph, 210. 
 
 Soleil light, 146. 
 
 Solokow, 25. 
 
 Sonometer, Hughes', 314. 
 
 Sound from magnets, Page's 
 
380 
 
 INDEX. 
 
 discovery, 277 ; transmitted 
 through solids, 274; vibrations, 
 273; wave motion, 282. 
 
 Sounder, telegraph, 230. 
 
 Spark, electric light, 146. 
 
 Spencer, electro, metallic discov- 
 eries, 192. 
 
 Spectra, magnetic, 73. 
 
 Sprague, electric locomotive, 174. 
 
 Sprengel, air-pump, 140. 
 
 Starr, incandescent lamp, 136. 
 
 Static electricity, 57. 
 
 Static-electric machines, 325. 
 
 Statues, electrotyping, 194. 
 
 "Steams," electrical, 10. 
 
 Steering, electrical, 356. 
 
 Storage of electricity, 199. 
 
 Strada, refers to telegraph, 208. 
 
 Strength of current, 41. 
 
 Sturgeon, electro-magnets, 86. 
 
 Sulzer, discovery of electric ef- 
 fects of metals, 30. 
 
 Sulphur-globe electric machine, 
 8. 
 
 Sunlight cell, 66. 
 
 Sun, electric, 147. 
 
 Swan incandescent lamp, 142. 
 
 Taste, electrical, 30, 336. 
 
 Telegraph, Ampere's, 211; auto- 
 graphic, 245; automatic, 241; 
 Barlow's experiments, 212; di- 
 plex,237; duplex, 236; Dyer's, 
 216; early experiments, 208; 
 Edison's, 243 ; electro-mag- 
 netic, invention of, 221; first 
 in Europe, 223; first in United 
 States, 219; Franklin institu- 
 tion report on, 215; harmonic, 
 237, 290; Henry's, 212; Lom- 
 ond's, 210; Lover's, 276; mili- 
 
 tary, 354; Morse's, 217; multi- 
 ple, .237; principles of, 225; 
 printing, 243; railway, 267; 
 Reizen's, 210; recording, 229; 
 relay, 232; repeater, 234; sig- 
 nals, 230; Ronald's, 210; Stem- 
 mering's, 210; submarine, 247; 
 system, 232; Trebouillet's, 222; 
 Vail's, 272; Wheatstone's, 223; 
 wires, length of, 270; writing, 
 246. 
 
 Telegraphing, long distance, 234. 
 
 Telephone, the, 272 ; balloon, 307 ; 
 Bell's, 291-295; Bourseul's sug- 
 gestion, 277; chemical, Edi- 
 son's, 307 ; condenser, 308 ; 
 current, 309; Drawbaugh's in- 
 ventions, 302; friction, Bell's, 
 306; Gray's, 290; in theatres, 
 313 ; liquid, 300 ; magneto, 
 principles of, 296 ; military 
 uses of, 354; odd uses of, 316; 
 patent, Bell's, 297; receiver, 
 296; records, 315; Reis's, 280; 
 resistance, principles of, 298; 
 system, Van Rysselberghe's, 
 313; transmitter, Benjamin's, 
 305; transmitter, Blake's, 303; 
 transmitter, Drawbaugh's, 304; 
 undulatory current, theory of, 
 297. 
 
 Telephoning, at sea, 311 ; by 
 earth's magnetism, 306; long 
 distance, 312; without wires, 
 312. 
 
 Telephotograph, 264. 
 
 Telpherage, 177. 
 
 Theatres, electric light in, 130. 
 
 Theories of electricity, 10, 19, 28, 
 29, 31, 35. 
 
 Thermo-electric battery, 55. 
 
INDEX. 
 
 381 
 
 Thermo-galvanic cell, 54, 207. 
 Thermopile, the, 55. 
 Thompson, effect, the, 56. 
 Thomson, spark light, 146. 
 Ticker, telegraph, 244. 
 Timbre, 282. 
 Time by electricity, 369. 
 "Torpedo," the, 5, 342. 
 Torpedo, electrical, 352. 
 Tourmaline, electricity of, 5. 
 Towers, electric light, 137, 147. 
 Transmission of power, 175. 
 Trebouillet, telegraph, 222. 
 Tricycles, electric, 176. 
 Tubes, Pivati's, 339. 
 
 Undulatory current in tele- 
 phones, 297. 
 
 Vacuum, magnetic effects in, 
 
 97. 
 Vacuum tubes, electricity in, 
 
 127, 330. 
 Van Rysselberghe, telephone 
 
 system, 313. 
 Vegetation, effect of electric light 
 
 on, 150. 
 
 Velocity of electric discharge, 18. 
 Vessels, protecting by galvanic 
 
 action, 63. 
 
 Vestal fire, electrical, 3. 
 Vitreous electricity, 11. 
 Volta, Alessandro, 31; letter to 
 
 Banks, 182. 
 Voltaic arc, 128. 
 Voltaic cell, 48. 
 
 Voltaic pile, 31; duration of, 63: 
 electrolysis by, 183; secondary, 
 203. 
 
 Voltameter, 200. 
 
 Volt, the, 40. 
 
 Wall, Dr., notes identity of amber 
 sparks and lightning, 9. 
 
 War, applications of electricity 
 to, 346. 
 
 Water, electrolysis of, 58, 183. 
 
 Watson, Dr., early telegraph ex- 
 periments, 18, 209; exposes 
 Boze, 126; on lightning-rods, 
 26. 
 
 Weekes, electric lighting towers, 
 137. 
 
 Whales, killing by electricity, 
 341. 
 
 Wheatstone, automatic tele- 
 graph, 241. 
 
 Wheatstone and Cooke, tele- 
 graph, 222. 
 
 Wheatstone, Sir C., magic lyre, 
 275. 
 
 Winkler, on Leyden-jar, 16; on 
 glass globe machine, 13. 
 
 Wire, electroplating, 198. 
 
 Work, electrical, 37. 
 
 Wright and Bain, railroad tele- 
 graph, 268. 
 
 Wright, discoveries in electro- 
 plating, 193. 
 
 Zamboni, dry pile, 63. 
 
 Zinc, consumption of, in cells, 53. 
 
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 eries, and a h'stori; al account of the progrc ss of th i fine arts. 
 The subj cts t'eated are of universal interest, and they are 
 discussed in a popu'ar and interesting manner. 
 
 The illustrations are very numerous, and leave nothing to be de- 
 sired on the score of completeness; they add materially to 
 the attractiveness and v.alue of the s res, whi h is by far the 
 most thorough, interesting and valuab'e of the kind ever pro- 
 duced. 
 
ILLUSTRATED LIBRARY OF WONDERS. 
 
 FROM THE BOSTON GLOBE. 
 
 "For young and old the series, in authority, sound information, and 
 popular interest and usefulness, is undoubtedly the best ever published" 
 
 THE WONDERS OF MAN AND NATURE. 
 
 Sold Separately at $1.OO per Volume. 
 The Set, 8 Volumes in a Box, $8.<JO. 
 
 Intelligence Of Animals, with Illustrative Anecdotes. From the French of 
 ERNKST MENAUT. W th 54 illustrations. 
 
 ''The reading of such a book will both instruct and interest young students, and we 
 might add almost equally so those who are more advanced in years. It is a wise thing for 
 both parents and teachers to impress upon young learners just such facts as here narrated. It 
 begets a feeling of interest in dumb animals, and adds new interest to all their movements." 
 
 Chicago Inter Ocean. 
 Mountain ^Adventures in Various Parts of the World Se'ected from the 
 
 narratives of celebrated travellers. With an introduction and additions 
 
 by Hon. J. T. HEADLEY. With 41 illustrations. 
 
 "J. T. Headley's selections from the narratives that celebrated travellers have written of 
 their mountain adventures in various parts of the world." Boston Advertiser. 
 
 Tlodily Strength and Skill in all tAges and Countries. By GUIL- 
 
 L\UME DEPPING. Translated by Charles Russell. With 70 illustrations. 
 ''To modern lovers of athletic sports the compilation is highly viseful and instructive. It 
 has seventy spirited illustrations." Journal of Commerce. 
 
 Wonderful Escapes. Revised from the French of F. BERNARD, and orig- 
 inal chapter by RICHARD WHITING. 
 
 ''It consists of an account of the most extraordinary escapes from captivity, from the time 
 of classic antiquity down to the present era. Among the stories will be found those of Bene- 
 venuto Cellini, Grotius, Baron Trenck, Cassandova, La Valette, Louis Napoleon, and James 
 Stephens. They are largely an to- biographical and afford a large fund of exciting and interest- 
 ing reading." Boston Gazette. 
 
 Thunder and Lightning. ByW. DEFONVIFLLE. Translated and edited 
 by T. L. Phipson, Pn.D. With 39 large illustrations. 
 
 "A bx>k which, from the nature of the subject, as well as from the skillful and common-sense 
 mode of treatment, well deserves to be re-issued. In spite of the progress of science it well 
 stands the test of time, and few books of the kind better repay perusal. It is one of those in 
 which one learns that fact is stranger than fiction. The marvellous plays an important part in 
 its pages." The Star. 
 
 Adventures on the Great Hunting Grounds of the World. By VIC- 
 TOR MEUNIER. With 22 illustrations. 
 
 ''Here are remarkable facts and stories about the hunting of the gorilla, the tiger, the lion, 
 the hippopotamus, the elephant, and other fierce and mighty creatures, well told and well illus- 
 trated." Philadelphia Evening Bulletin. 
 
 Wonders Of the Human "Body. From the French of A. LE PILEUR, 
 Doctor of Medicine. With 45 illustrations by Leveille. 
 
 The Sublime in Nature. From descriptions of Celebrated Travelers and 
 Writers. By FERDINAND DE LANOYE. With 44 illustrations. I2mo. $1.00. 
 
'LLUSTRATED LIBRARY OF WONDERS 
 
 FROM THE CHRISTIAN ADVOCATE. 
 
 ''These book! may be bought with the certainty that they will give 
 unbounded pleasure of a good kind to the -well-grown children of a 
 family, and that the matur; -will pick them up as eagerly as those who 
 are younger ." 
 
 THE WONDERS OF SCIENCE 
 
 Sold Separately at $l.OO p*r Tolttme. 
 The Set, 8 Volumes in a Box, $8.0O. 
 
 Heat, Its Phenomena and Laws. By ACHFLLE CAZIN. Translated and 
 edited by Elihu Kiel. With a new chapter on "Recent Improvements in 
 the Application of Heat.'' With 93 illustrations. 
 
 "The treatise aims to give a simple account of heat pher omem and is of interest to rather 
 advanced young students of science. The cheap price, one dollar per volu ne, will enable 
 studious young folks to add to their home library shelves these solidly attractive books." 
 
 Ph ila delph ia. L edger. 
 
 Wonders of the Heavens. By CAMILLE FIAMMARTOM. Translated from 
 the French by Mrs. Noimon Lockyer. With 48 illustrations. 
 "It is an inter jsting, popular, yet authoritative presentation of the wonders of the heavens." 
 
 Christian Rrgi*ter. 
 
 Wonders Of Optics. By F. MARION. Tr n^latedand edited by Charles 
 M. Quin, F.C S. With 71 illustrations and a colored fro uispiece. 
 "The author h s an official po ition in Paris, and shows his capability as a popular writer 
 in the volume before us. An original chapter on the ' Spectroscope' has been added. The 
 book abounds not only in facts, but illustrative anecdotes, many of curons interest. Some 
 seventy-five illustrations add to the value and interest of the book." Christian Register. 
 
 The Sun. By AMEDEE GUILLEMIN. Translated from the French by T. L. 
 PHIPSON, l J h.D. With 58 illustrations. 
 
 "It is a popular account ot the ' life of the earth,' and a very interesting one too. 11 Brook' 
 lyn Union. 
 
 Wonders of ^Acoustics ; or, The Phenomena of Sound. By R. 
 
 RADAU. With an additional chapter on the reproduction and transmission 
 of articulate speech. Withuo illustrations. 
 
 "There are few more enjoyable or more instructive books in any language. The subject 
 is looked at from almost every imaginable point of view." N. Y. Star. 
 
 Wonders of Water. Translated from the French of GASTOV TISSANDTER. 
 
 Edited, with additions, by SCHELE DE VERE, of the University of Virginia. 
 
 Illustrated with 64 engravings and charts. 
 
 "Everything connected with the subject is set forth in a clear and simple but comprehen- 
 sive style, embracing the physical and chemical properties of water ; ils uses the system of cir- 
 culation, the action of water on continents, etc. Like all the volumes in this series, it is a perfe< t 
 compendium of information in reference to ,he subject on which it treats." Christian at Work. 
 
 Wonders of the Moon. Translated from the French of AMEDEE GUILLE- 
 Miv by Mis, M. G. Mead. Edited, with additions, by MARIA MITCHEL, 
 Vassar College. With 43 illustrations. 
 
 Meteors, Aerolites, Storms, and Atmospheric Phenomena. From 
 
 the French of ZURCHER and MARGOLLE, by Wm. Lackland. With 23 
 illustrations by Lebreton. 
 
ILLUSTRATED LIBRARY OF WONDERS 
 
 FROM THE N. Y. JOURNAL OF COMMERCE. 
 
 "Suck a. library, brim full cf pictures, is a joy to the household, besides 
 being a means of solid instruction" 
 
 The BONDERS of ART and ARCH/EOLOGY. 
 
 Sold Separately at $1.OO per VoUime. 
 The Set, 8 Volumes in a liojc, 
 
 Egypt 3,300 Years Ago ; or, Rameses the Great. By F. 
 
 OYE. W ith 40 illustrations. 
 
 'In this small handsome book of less than 300 pages, one finds compressed a very large 
 amount of information upun one of the most interesting subjects now inviti ig attention." Chi- 
 cago Standard. 
 
 Wonders Of Sculpture. By Louis VIARDOT. With chapter on Amer- 
 ican Sculpture by CLARKNCE COOK. With 62 illustrations. 
 
 "An excellent portable hand-book of the different schools of art, with short notices of lead- 
 ing artists." Zion's Herald. 
 
 Wonders of Glass Making in All Ages. By A. SUAZAY. With 63 
 
 illustrations. 
 
 "Apart from the intrinsic interest of the book as a pleasant history of an art to which the 
 world owes so much that is useful and beautiful, the reader may gather from it a large amount of 
 technical knowledge which will be of service to him in judging of glassware as a purchaser." 
 
 Journal of Commerce. 
 
 Wonders Of European Art. Translated from the French of Louis 
 VIARDOT. With n illustrations. 
 
 "A short summary of the achievements of the Spanish, German, Flemish, Dutch and 
 French schools of painting. It is written primarily for the benefit of readers who have access to 
 the Louvre, but its terse condensations suit it to the needs of those who desire a compact and 
 rudimentary general survey of European painting." N. Y. Commercial Advertiser. 
 
 Wonders of Pompeii. By MARC MONNIER. With 32 illustrations. 
 
 "M. MONNIER does not vaunt his erudition, though he may be an archseologi-t of the most 
 distinguished merit : what he aims to do is to describe an old city buried in A. D. 79, and to 
 present us with clear ideas of what Pompeii was like when it was a live and bustling place, and 
 contrast those past conditions with those of to-day." N. Y. Times. 
 
 Wonders of Architecture. By M. LEFEVRE. With a Chapter on 
 English Architecture by R. DONALD. With 60 illustrations. 
 "In this volume we have a good account of former works in Architecture in different coun- 
 tries and ages, and there are sixt y illustrations, including views of buildings, of which no one ever 
 <ires." Philadelphia Evening Bulletin. 
 
 The Wonders Of Italian Art. By Louis VIARDOT. With 28 illustrations. 
 
 "His criticism and description are of a sort calculated to inform the average stude.it of the 
 subject, and the book contains several good illustrations of famous pictures." Philadelphia 
 American. 
 
 The Wonders of Engraving. By GEORGES DUPLESSIS. With 34 illus- 
 trations. 
 
 CHARLES SCT^IBNER'S SONS, Publishers, 
 
 743 & 745 BROADWAY, NEW YORK, 
 
1,4. DAY USE 
 
 RETURN TO DE^K ^ROM WHICH BORROWED 
 
 LOAN DEPT. 
 
 RENEWALS ONLY- 5L. NO. 642-3405 
 
 This book is aue on the last date stan 3ed clow, or 
 
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 Renewed books are subject to imme. I. 
 
 1 '6 19723 
 
 IlBHArtY 
 
 1989 
 
 
 
 LD21A-60m-6,'69 
 (J9096slO)476-A-32 
 
 General Library 
 
 University of California 
 
 Berkeley