/ '/ /,////// ' / f ///< ' yc . ,. /// . '/"I,-, //,,,,,/ //'//-// /y . ^W, ,-,/. ^ ' s // /. //ft */ //I HISTORY OF ELECTRICITY (THE INTELLECTUAL RISE IN ELECTRICITY) FROM ANTIQUITY TO THE DAYS OF BENJAMIN FRANKLIN BY PARK BENJAMIN, Ph.D., L.L.B. Mem. Am. Inst. Elec. Engrs. ; Assoc, Mem. Soc. Naval Architects and Marine Engrs. ; Foreign Member Br. Inst. of Patent Agents ; Editor-in-Chief Appleton s Cyclopaedia of Applied Mechanics and Modern Mechanism ; A uthor of The Age of Electricitv The Voltaic Cell, etc.^ etc. NEW YORK JOHN WILEY & SONS 53 East Tenth Street 1898 COPYRIGHT, 1895. BY PARK BENJAMIN All rights reserved. Hraimworth, Munn and Barber, Printers and Binders, Brooklyn, N. Y. OF THE UNIVERSITY OF PREFACE. IN this work I attempt to show how there came into the world the knowledge of the natural force, which we call electricity ; a force which, within the memory of many now living, has found its most important applications to the needs of mankind, and which exhibits a promise and potency of future benefit, the full extent of which no one can safely venture to predict. The research has taken many years, has necessitated the gathering of a large collection of ancient, and now ex- ceedingly scarce, writings, not commonly found even in great libraries, and the sifting of an immense mass of recorded facts and theories, often arising in fields far re- moved from those in which it might naturally be supposed the requisite data would be discovered. The Greek and Roman classics, the results of modern investigation into the old civilizations of Phoenicia, Egypt and even of people of prehistoric epochs, the Norse histories, the an- cient writings of the Chinese and Arabs, the treatises of the Fathers of the Church, the works of mediaeval monks, magicians, cosmographers and navigators, the early poetry of modern France and Italy ; these, mentioned at random, are some of the sources which have been drawn upon, together with the records of the experiments and discoveries of the natural philosophers of all ages. I have made it a rule to note the original founts wherever it seemed to me that such references would be of benefit to others desiring to verify facts or to go over the same ground, and as pro- viding a useful bibliography ; while, at the same time, I have endeavored to avoid a multiplicity of annotations (3) 207110 4 PREFACE. relative to immaterial points, which impose only needless labor and uncertainty upon the student. Above all things, I have sought to write a straight, plain, simple, and, I hope, fairly logical and interesting story. I have rigidly excluded technicalities and scien- tific demonstrations, which, however interesting to the professional electrician, are as Greek to the general reader ; for I address this no more to the wise men of the wires and the dynamos and the batteries, than to the great pub- lic whom we all serve, and for whose good we all labor. Popular science, so called, is too often dilute science. Scientific discussions of a didactic or abstract nature, or involving a Babylonish terminology, and requiring minds trained to understand them, cannot be rendered any easier to the mental digestion of intellects engrossed in other departments of the world's work, and, hence, not so edu- cated, by mechanically mixing them with the water of an engaging rhetoric. The facts and the arguments based on them must be digested and brought into true solution, so that the food offered will be easily assimilable ; and that is what I have tried here to do. Perhaps this work may usefully tend to show that elec- tricity, at the present time, is not u in its infancy." It has undoubtedly a vast amount of work yet to do, and I am patriotic enough to believe at the hands of our Amer- ican inventors, first of all will yet accomplish things un- dreamt of in our philosophy ; but it will do this not with the feeble uncertainty of the nursling, but with the vigor and might of maturity. Moreover, although in ancient days electricity, in common with all other natural mani- festations, was regarded as a mystery, none the less the knowledge of it, as these pages seek to prove, forced its way through the clouds of ignorance and superstition with the unerring directness of a projectile driven through the mist from a modern gun. Electricity is not now occult, it is not mystic, it is not magic, its workings are no more wonderful than are the rise and fall of the tides ; in fact, it PREFACE. 5 may be safely said, that we know more about its laws and their consequences than we do about those which deter- mine the fall of a stone to the ground. I end this essay which has been more of pleasure than of toil fully conscious of the errors and inconsistencies which must be in it. At every turn there have been tan- gled skeins to unravel, whereof the true clews have, no doubt, often been missed ; diverging roads, where one selects a path never without misgivings. But with all due submission, I venture to believe that a faithful effort, even if misdirected, is better than none at all, although in that consciousness may well lie the only justification for this book. PARK BENJAMIN. CONTENTS. PAGE Introduction n CHAPTER I. Ancient sources of amber 15 Amber legends 16 The Syrian women and their amber spindles 17 The lodestone 19 Lodestone legends 22 Greek knowledge of the lodestone and the Samothracian rings. . . 23 The Magnetes 26 Egyptian knowledge of the lodestone 28 Magnetic knowledge of the Hebrews 29 CHAPTER II. The opening of the Egyptian ports 30 Greek Nature-worship . 31 Thales of Miletus and the beginning of Greek philosophy 32 The Magnet-soul 33 Diogenes Laertius on Thales 34 Aristotle and the foreshadowing of the inductive method 38 Theophrastus, and the first physical description of the amber effect . 39 The mythical Lyncurium 41 The University of Alexandria 44 Legends of magnetic suspension Mahomet's coffin 45 Lucretius' De Natura Rerum and its description of magnetic effects . 47 Ancient medical uses of amber 52 CHAPTER III. The polarity of the magnet , , . , . 53 Unknown to ancient Greeks 54 Or to ancient Phoenician navigators 55 The Betulae 56 No knowledge of polarity among ancient Egyptians 57 Or among the Etruscans 59 Polarity possibly known to the prehistoric Nomad races 61 Relations of Akkadians and Chinese 63 Ancient China and Chinese chronology 64 The Chinese south-pointing carts 67 (vi) CONTENTS. Vli Ancient Chinese knowledge of amber and of the geomancer's Com- pass 75 The Chinese not natural navigators 77 Nor reliable astronomers 79 Nor competent inventors 80 The Mariner's Compass probably not of Chinese origin 85 CHAPTER IV. The Dark Ages and the rise of Scholasticism 86 First distinction between magnetic and electric effects drawn by St. Augustine 87 Patristic references to the lodestone and amber 90 Old medical uses of the lodestone 93 Claudian's Idyl 93 The Fables of the Magnetic Rocks 96 Ancient Arab navigation 102 The Compass not used in early voyages on the Indian Ocean .... 103 Nor by the Spanish Saracens ic8 Nor on Spanish ships until 1403 in CHAPTER V. The Northmen and their early voyages 112 Physical science among the Anglo-Saxons 115 The Norman invasion and the poem of William Appulus of Amalfi . 116 Scholastic philosophy 118 Alexander Neckam 120 His treatise de Natura Rerum 122 The doctrine of similitudes , . . . . 124 And of virtues 125 Applied to the lodestone 127 The first European description of the Mariner's Compass 129 And the remarkable magnetic discoveries preceding 131 The Compass points 133 Gottlaud, the great nautical rendezvous 134 Wisbuy and its laws 135 The Finns and Lapps 137 Their sorcery and relationship to Chinese 139 And possible ancient knowledge of Compass 141 The garlic myth 142 The punishment for tampering with the Compass 144 The Compass possibly of Finn origin and emanating from Wisbuy . 145 CHAPTER VI. Thirteenth century thought 148 William the Clerk on the Compass 149 The Bible of Guyot de Provins 152 viii CONTENTS. PAGE And other mediaeval poems referring to magnetic polarity 154 The spurious treatise of Aristotle 157 Mediaeval lodestoue myths and fables 159 Roger Bacon and his discoveries 160 Ancient conceptions of the universe 163 CHAPTER VII. Peter Peregrinus 165 His perpetual motion 167 His marvelous magnetic discoveries 169 His development of the Mariner's Compass 184 Flavio Gioja and his Compass card 187 Plagiarists of Peregrinus 191 CHAPTER VIII. The revival of literature in Europe 193 Henry the Navigator and Portuguese voyages 194 Christopher Columbus and his magnetic discoveries 196 Attempts to account for Compass variation by the Magnetic Rocks . 202 The voyages of Vasco da Gama and Magellan 205 Peregrinus' disclosure of the magnetic field of force 207 Hartmann partly recognizes Dip of the Compass needle 209 Norman's discovery and explanation of Dip 211 Magnetic deceptions of the period 219 Paracelsus and his magnetic nostrums 220 CHAPTER IX. Fra Paolo (Pietro Sarpi) 224 His treatises on the magnet . 225 Cesare observes magnetism by earth's induction 227 The Jesuits dispute Sarpi's discoveries 228 John Baptista Porta 230 His Society 231 His relations to Sarpi 232 His treatise on natural magic and the magnetic discoveries therein recorded 234 And especially the magnetic field of force 235 And telegraphic communication by magnets 239 Jerome Fracastorio 241 Jerome Cardan 243 And his differentiation of magnetic and amber effects 249 The physicians as physicists 255 CHAPTER X. William Gilbert 258 The object of his work 268 CONTENTS. IX PAGE His errors 274 His mode of thought 275 His Terrella and his magnetic theories 277 His magnetic discoveries 288 The inception of his study of electricity 294 The discovery of the Electrics 299 Gilbert's electrical experiments 303 His electrical theory ^ 307 His electrical discoveries recapitulated 313 CHAPTER XL Gilbert's treatises 315 Francis Bacon and his suppression of Gilbert's later work 318 Bacon's criticisms on Gilbert * 321 Bacon's studies in magnetism and electricity 324 CHAPTER XII. Physical science in England in time of James I . . . . 332 The great Universities ... 333 William Barlowe and Mark Ridley, and the controversy between them .336 Physical Science in Italy. . , 341 Galileo and his indebtedness to Gilbert 344 Galileo's magnetic researches 347 The electric discoveries of Nicolaus Cabaeus 349 The magnetic and electric theories of Rene* Descartes 356 The amber and the magnet in English literature 367 The Rosicrucians and Van Helmont 372 Sir Kenelm Digby, and the rise of physical science in England . . . 377 Sir Thomas Browne, destroyer of errors . . . , 380 Some early notions of telegraphy 382 Otto von Guericke 389 His theory of virtues 392 His extraordinary electrical discoveries made with the sulphur globe 396 CHAPTER XIII. The founding of the English Royal Society 404 Science at the Court of Charles II 406 Robert Boyle 414 His philosophy 416 His electrical discoveries 420 Physical observations in America, and Madam Sewall's sparkling skirt 425 Robert Hooke 426 Isaac Newton and the reduction of electricity under the reign of law. 435 Halley's magnetic theories 447 OF THE UNIVERSITY OF INTRODUCTION. THE intellectual rise in electricity is worthy of histori- cal investigation, not merely because of the material results, actual and potential, which have come from it, but because it shows clearly anew the marvellous power of the human mind as an instrument of discovery, capable of correcting its own errors. Beginning with a single phenomenon, afterwards including effects all, for long periods, seemingly fortuitous and uncorrelated, this rise has involved questions of an interest second only to that which mankind has yielded to the great issues of life and eternity; questions which challenged the human under- standing and compelled it to measure itself against them. From one fact it came to include many facts, from one conception grew many conceptions, coincidently with the increase in human learning, the broadening of human thought, and the development of human intelligence. The initial idea the germ found its lodgment in some brain existing at an epoch far beyond the limits of history. The discovery of amber in the ancient lake dwellings of Europe suggests the possible perception of it by pre-historic man. The accidental rubbing against the skins with which he clothed himself may have caused an attraction by the resin, thus electrified, of the light fur in sufficiently marked degree to arrest his attention. Be- tween such a mere observation of the fact, however, and the making of any deduction from it, vast periods may have elapsed; but there came a time at last, when the amber was looked upon as a strange inanimate substance which could influence or even draw to itself other things; and this by its own apparent capacity, and not through (12) INTRODUCTION. 13 any mechanical bond or connection extending from it to them; when it was recognized, in brief, that nature held a lifeless thing showing an attribute of life. This was more than a mere impression. It was an en- igma demanding resolution, and thus endowed with inher- ent and eternal vitality. At some other time, perhaps not until after the advent of an Iron Age, a similar power to that of the amber was seen in the attraction of the lodestone for iron. Because of this similitude the ancients somewhat hazily imagined both effects to be essentially one. Progress in discovery concerning either was therefore progress in knowledge concerning both. This is also true from our modern point of view, for not only are the phenomena of magnetism and of electricity directly correlated and interconvertible, but the concept of magnetism perhaps most widely accepted at the present time, holds it to be merely an electric state; the condition of electricity in whirling or vortex motion. The attempt to account for magnetic attraction as the working of a soul in the stone led to the first attack of human reason upon superstition and the foundation of philosophy. After the lapse of centuries, a new capacity of the lode- stone became revealed in its polarity, or the appearance of opposite effects at opposite ends ; then came the first util- ization of the knowledge thus far gained, in the mariner's compass, leading to the discovery of the' New World, and the throwing wide of all the portals of the Old to trade and civilization. The predominance of the magnet in human thought was yielded to the amber, when the strange power of the latter was found to exist also in other things. The keen-eyed discoverers saw this new force annihilate time and space, and flash into light ; pursued it even to its hiding-place in the clouds ; beheld it grow from the feeble amber-soul into the mighty thunderbolt ; watched it until the whole uni- verse showed itself pervaded with it. 14 INTRODUCTION. This was a true intellectual rise. It was the Intellect at work building the universe of which it is the key ; finding anew that Nature also is working in every detail after the laws of the human rnind. 44 It is not, then, cities, or mountains, or animals, or globes that any longer command us, but only man ; not the fact, but so much of man as is in the fact" 1 So in this research, I have felt that it is not so much the trials and the discoveries made in this great and new field of Nature which attract us, instructive and useful, even momentous as they are for after all to many they are but abstractions not these, so much as the breathing human beings, who in the far past saw them and deciphered them in the light of those other days, and of whose life they formed a part ; who thought of them, and whose thoughts lived on, and became immortal, and moved downward through generation after generation to us ; even as our thoughts, joining theirs, will pass through the ages to the generations yet to come. 1 Emerson : Natural History of Intellect. CHAPTER I. x THE use- of amber begins with the dawn of civilization. The discovery of beads in the royal tombs at Mycenae and at various places throughout Sardinia and the territory of ancient Etruria, proves that trade in it existed in prehis- toric times; while the identity in chemical constitution of the amber ornaments of Mycenae and the Baltic amber from the Tertiary formation of the Prussian Samland, the coasts of southern Sweden and the northern Russian pro- vinces, indicates the far distant source from which the resin was anciently derived. 1 Who first brought the resin from the Baltic Sea to the L,evant is an undetermined question, since it is known to have come southward across Europe by land as well as around the continent by water. The Phoenicians those far-sighted and consummately keen traders, whose commercial and maritime supremacy is still unrivaled by that of any modern nation extended their voyages past the gates of the world into the unknown ocean in search of both the amber of the Northern Sea and the tin of Cornwall; for to obtain the latter the makers of bronze from all quarters flocked to the great metal market of Sidon. Both commodities also came by way of the Rhine * and the Rhone to Marseilles and across the Alps to Etruria and chiefly to the valley of the Po, besides elsewhere by other land routes, along all of which stores of tin and amber have been found as they were ages ago hidden when the caravans were attacked or fell victims to the natural perils of the road. While these ways are known to have existed, and the amber trade over them to have been maintained before Rome or Carthage were 1 Schliemann c Mycenae and Tiryns, 1876, 203, 245 ; Tiryns, 1886, 369. Mmcox : Prehistoric Civilizations, 1894. ds) 16 THE INTELLECTUAL RISE IN ELECTRICITY. founded, it may be that the Phoenician voyages to the Baltic were of still greater antiquity, for the beads of Mycenae date from at least two thousand years before our era. The amber was used by the ancient world as a jewel and for decoration. Its color and lustre reminded the fan- ciful Greeks of the virgin gold which glistened in the sands of Pactolus, even as the brilliant metal had itself recalled to them the yellow sunshine. Afterwards they applied the same name to the compounds of metals which, when burnished, gave a golden glow. They were all chil- dren of the sun "Elector" reflecting in miniature his radiance. Thus, in common with native gold and the silver-gold alloys, the amber, in Hellenic speech, came to be called "electron." 1 Throughout Greek literature, even from the time of Homer and Hesiod, the mention of it is frequent. It is inlaid in the royal roof of Menelaus, it bejewels the brace- lets of Penelope, the necklaces of Eumoeus, 2 and the shield of Hercules. 3 Legends cluster thick about it. Through the lost tragedy of ^schylus, the Hippolyta of Euripides and the Metamorphoses of Ovid comes the myth of Phaeton, recounting his death by the thunderbolt and fall into the river Eridanus, and the , transformation of the weeping Heliades into poplars ever sighing and shedding their amber tears beside the stream. The Greek traders coming to the mouth of the Po for their cargoes, easily believed the story perhaps told to conceal the true source that the resin had been gathered under the poplar trees along the banks, or on the Electrides the islands at the outlet of the river. Long afterwards, so firmly did the 1 The ancient Greek poets called the sun rp^xrop and Homer repeatedly so terms it (Iliad. Z/ 513: T/ 398). "Electron" is used very indefi- nitely by the Greek classic writers and in fact has no permanent gender, though commonly neuter. See Rossignol : Les Me"taux Dans 1'Anti- quite", 345. Paris, 1863. 1 Odyssey. Hesiod : Scutum Herculis. ! ^ TRADITIONS OF THE AMBER. 17 legend persist, men came to search the shores of Eridanus for amber, as the Spanish adventurers sought the Eldorado in the new world. "Dost thou think that we would tug against this torrent for two oboli a day?'' laughed the boatmen of the Po to the discomfited Lucian, "could we find riches under the poplar trees for the picking up?" To the mythical tales set afloat by the traders, became added the fancies of the poets. Amber is gathered, so ran one fable, by the maiden guardians of the golden Hesper- ides as it falls from the poplars into Lake Electrum ; it is the slime of drear Lake Cephisis, the sweat of the laboring soil under the fierce rays of the sun, the tears of the Indian birds for the death of Meleager, said others. And the sailors told of other Electrides islands in the German ocean and off the Calabrian coast where grew the tree "Electrida," and of stones in far-off Britain "purging thick amber." It often happens that historical facts become embedded, as it were, in the names of things, and thus preserved, and the knowledge of them so passed down through cen- turies. Just as we find now locked in the yellow depths of the amber, bodies of insects which lived ages ago, so in one of the designations which the people of ancient times gave to it is embalmed, perhaps, the story of how elec- tricity first became known to the civilized world. The Syrian women, Pliny says, 1 called the amber "har- paga" or "the clutcher;" which is obviously based on a peculiarity of it altogether different from that which caused it to be likened to an embodied sunbeam. This name, in turn, came from its use in spinning, the oldest handiwork known to the race, and in the mode of spinning which has been employed since the very beginning of civilization. So that we may conjecture that the name came down from the old Phoenicians, and that the amber which they 1 Pliny : lib. xxxvii. c. I ; Aldrovandus : Musaeum Metallicum. Milan, 1648, 404. 2 18 THE INTELLECTUAL RISE IN ELECTRICITY. worked into beads and ornaments found its place in the hands of every woman who spun with the distaff, and who could afford the luxury of a spindle made of the much- prized substance. The way in which the spinning was done by distaff and spindle, Catullus tells : "The loaded distaff in the left hand placed, With spongy coils of snow-white wool was graced, From these the right hand lengthening fibres drew, Which into thread 'neath nimble fingers grew. At intervals a gentle touch was given, By which the twirling whorl was onward driven. Then, when the sinking spindle reached the ground, The recent thread around its spire was wound, Until the clasp within its nipping cleft Held fast the newly finished length of weft." As the spindle descended, and at the same time whirled around, it rubbed against the loose feminine garments ; thus it became electrified, as amber always does when rubbed, so that on nearing the ground, it drew to itself the dust or bits of leaves or chaff lying there, or sometimes at- tracted the light fringe of clothing. The spinner easily saw this, because the chaff would leap up to the excited resin, or the fringe filaments extend themselves toward it, and moreover, unless she were careful, the dust and other substances so attracted would become entangled in her thread. Therefore, she called her amber spindle, the u clutcher ; " for it seemed to seize these light bodies as if it had invisible talons which not only grasped, but held. This was probably the first intelligent observation of an electrical effect. It is singular that it should have become apparent through the earliest practical, in contradistinc- tion to merely ornamental, use of the amber, though per- haps nothing strange that it is due to the keener percep- tion of woman. THE LODESTONE. 19 The lodestone or magnetite is an ore of iron 1 which sometimes crops out as a rock above the surface of the ground. The accidental bringing of an iron object into the neighborhood of the outcropping stone probably caused the first observation of the attractive power of the rock for the metal, and thus furnished the basis for the legend which Pliny copies from the poet Nicander (who wrote it two centuries before his time), concerning the Shepherd Magnes, who, while guarding his flock on the slopes of Mount Ida, suddenly found the iron ferrule of his staff and the nails of his shoes adhering to a stone ; which subsequently became called after him, the " Magnes Stone," or "Magnet." This legend, in various forms, retained its vitality up to comparatively recent times. As masses of magnetite were discovered in various parts of the world, the stories of its attractive power became greatly exaggerated, especially, as I shall hereafter show, during the Middle Ages. In fact, magnetic mountains which would pull the iron nails out of ships, or, later, move the compass needle far astray, did not lose their place among the terrors of the sea until after the seventeenth century had become well advanced. The phenomena of the lodestone are, however, two-fold. It not only attracts iron objects, but it has polarity, or, in other words, exhibits opposite effects at opposite ends ; by reason of which, when in elongated form and supported so as freely to turn, it will place itself nearly in the line of a meridian of the earth that is, nearly in a north and south direction. This is its directive tendency, or, as William Gilbert called it in 1600, its "verticity," and upon this quality, as is well known, depends the use of the magnet- ized needle in the mariner's compass. We may conclude that whoever gained the first knowl- edge of the attractive power of the lodestone, was also acquainted with iron, if he had an iron object to present aOs, sp. gr. 5.2, contain2 72.41 per cent, of iron. Osborn: Metallurgy of Iron and Steel. 20 THE INTELLECTUAL RISE IN ELECTRICITY. to the stone and in this way perceived its attraction. Iron, however, is never found in a metallic state in nature, except in meteorites. Excluding this infinitesimal supply, the metal is obtained from its ores, by means usually involving the development of intense heat, so that to devise modes of attaining the necessary tempera- tures, let alone the even more complex mental work of contriving apparatus and processes for separating the metal, requires advanced powers of observation and inven- tion. Hence modern ethnological and geological author- ities unite with Lucretius 1 and other ancient writers in affirming that the Age of Iron has always followed that of brass or bronze. So far, therefore, as establishing the probable time of the discovery of the attractive force of the lodestone is concerned, it is immaterial whether we consider that the phenomenon was first remarked as an effect of outcropping magnetite upon iron brought near to it; or as one exerted by fragments of magnetite in an iron mine upon other fragments of the same substance, or upon extracted iron. In any case, the observation of the fact seems necessarily to have followed the advent of an Iron Age, and therefore may not extend indefinitely back into prehistoric times. On the other hand, with regard to the directive tendency of the lodestone a different conclusion is reached. To sus- pend an elongated piece of the stone and see it turn itself in a definite direction; or to do this repeatedly and with different pieces and thus learn that the phenomenon is true of this particular stone and not of other stones, obvi- ously involves no necessary knowledge of its attractive effect on iron. Therefore, if we admit the possibility of sufficient intelligence in the race then living, we may con- jecture that an acquaintance with magnetic polarity may have existed among the earliest peoples of which we have any tradition. I shall show hereafter that reason for such conjecture is by no means absent, which if ac- 1 De Natura Rerum, v. THE IRON AGE. 21 cepted, places human knowledge of the directive tendency of the lodestone not only far beyond the limits of history, but even suggests the utilization of that knowledge by wandering hordes for their actual guidance over the wil- dernesses of the earth, at the same extremely remote epoch. For the present, however, it is necessary to deal with modern civilization and periods within historical times, and therefore, to begin with an inquiry into the familiarity of the western world with magnetic attraction ; for what- ever the Asiatic people may have known concerning mag- netic polarity, there is no trustworthy evidence that the nations of Europe had the slightest acquaintance with it before the twelfth century of our era. It is especially difficult to determine the positive date when any nation made the transition from the bronze to the iron age, and practically impossible to do so in the cases of people who either inhabited countries where iron does not abound, or who never acquired the art of obtain- ing it. In such event, the substitution of implements of iron necessarily imported from other countries for the native ones of bronze, to which the population had become accustomed by ages of use, was an exceedingly slow pro- cess, retarded by the mental inertia of the times, and often by national pride in home customs and handiwork. Hence arises the seeming anomaly that among people far advanced in civilization, the general use of iron can be recognized only at a comparatively late period in their history; while among barbarians, incomparably below them in intellectual attainments, we find evidence of its employment at immensely earlier periods. In Denmark, for example, the age of iron corresponds to that of the beech tree. Hesiod, writing in 850 B. C., speaks of the time when "men wrought in brass, when iron did not exist;" and Homer, although frequently referring to weapons and implements of bronze, mentions iron but rarely. The Aztecs, at the time of the Conquest, knew nothing of the metal, although their soil was impregnated 22 THE INTELLECTUAL RISE IN ELECTRICITY. with it. The Peruvians, under the same natural condi- tions, were equally ignorant 1 The traditions of magnetic attraction, however, date from periods far earlier than the days of Nicander. The iron of antiquity was mined chiefly on the islands and coasts of the