Part 255

"Electricity, through its etymology at least, traces its lineage back to Homeric times. In the Odyssey reference is made to the 'necklace hung with bits of amber' presented by the Phœnician traders to the Queen of Syra. Amber was highly prized by the ancients, having been extensively used as an ornamental gem, and many curious theories were suggested as to its origin. Some of these, although mythical, were singularly near the truth, and it is an interesting coincidence that in the well-known myth concerning the ill-fated and rash youth who so narrowly escaped wrecking the solar chariot and the terrestrial sphere, amber, the first known source of electricity, and the thunder-bolts of Jupiter are linked together. It is not unlikely that this substance was indebted, for some of the romance that clung to it through ages, to the fact that when rubbed it attracts light bodies. This property it was known to possess in the earliest times: it is the one single experiment in electricity which has come down to us from the remotest antiquity. … The power of certain fishes, notably what is known as the 'torpedo,' to produce electricity, was known at an early period, and was commented on by Pliny and Aristotle. {770} … Up to the sixteenth [century] there seems to have been no attempt to study electrical phenomena in a really scientific manner. Isolated facts which almost thrust themselves upon observers, were noted, and, in common with a host of other natural phenomena, were permitted to stand alone, with no attempt at classification, generalization, or examination through experiment. … Dr. Gilbert can justly be called the creator of the science of electricity and magnetism. His experiments were prodigious in number, and many of his conclusions were correct and lasting. To him we are indebted for the name 'electricity,' which he bestowed upon the power or property which amber exhibited in attracting light bodies, borrowing the name from the substance itself, in order to define one of its attributes. … This application of experiment to the study of electricity, begun by Gilbert three hundred years ago, was industriously pursued by those who came after him, and the next two centuries witnessed a rapid development of science. Among the earlier students of this period were the English philosopher, Robert Boyle, and the celebrated burgomaster of Magdeburg, Otto von Guericke. The latter first noted the sound and light accompanying electrical excitation. These were afterwards independently discovered by Dr. Wall, an Englishman, who made the somewhat prophetic observation, 'This light and crackling seems in some degree to represent thunder and lightning.' Sir Isaac Newton made a few experiments in electricity, which he exhibited to the Royal Society. … Francis Hawksbee was an active and useful contributor to experimental investigation, and he also called attention to the resemblance between the electric spark and lightning. The most ardent student of electricity in the early years of the eighteenth century was Stephen Gray. He performed a multitude of experiments, nearly all of which added something to the rapidly accumulating stock of knowledge, but doubtless his most important contribution was his discovery of the distinction between conductors and non-conductors. … Some of Gray's papers fell into the hands of Dufay, an officer of the French army, who, after several years' service, had resigned his post to devote himself to scientific pursuits. … His most important discovery was the existence of two distinct species of electricity, which he named 'vitreous' and 'resinous.' … A very important advance was made in 1745 in the invention of the Leyden jar or phial. As has so many times happened in the history of scientific discovery, it seems tolerably certain that this interesting device was hit upon by at least three persons, working independently of each other. One Cuneus, a monk named Kleist, and Professor Muschenbroeck, of Leyden, are all accredited with the discovery. … Sir William Watson perfected it by adding the outside metallic coating, and was by its aid enabled to fire gunpowder and other inflammables."

_T. C. Mendenhall, A Century of Electricity, chapter 1._

ELECTRICITY: A. D. 1745-1747. Franklin's identification of Electricity with Lightning.

"In 1745 Mr. Peter Collinson of the Royal Society sent a [Leyden] jar to the Library Society of Philadelphia, with instructions how to use it. This fell into the hands of Benjamin Franklin, who at once began a series of electrical experiments. On March 28, 1747, Franklin began his famous letters to Collinson. … 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." Meantime, numerous experiments with the Leyden jar had convinced Franklin of the identity of lightning and electricity, and he set about the demonstration of the fact. "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 sentry-box, from which should rise a pointed iron rod, insulated 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 evident to the senses by sparks being emitted when a key, a knuckle, or other conductor was presented to it. Philadelphia 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 the hempen string terminated, a key was fastened. With this apparatus, on the appearance of a thunder-gust approaching, 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. Repeated 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. … Franklin'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. … Nevertheless, public opinion became settled … that they did protect buildings. … Then the philosophers raised a new controversy as to whether the conductors should be blunt or pointed; Franklin, Cavendish, and Watson advocating points, and Wilson blunt ends. … The logic of experiment, however, showed the advantage of pointed conductors; and people persisted then in preferring them, as they have done ever since."

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_P. Benjamin, The Age of Electricity, chapter 3._

ELECTRICITY: A. D. 1753-1820. The beginnings of the Electric Telegraph.

"The first actual suggestion of an electric telegraph was made in an anonymous letter published in the Scots Magazine at Edinburgh, February 17th, 1753. The letter is initialed 'C. M.,' and many attempts have been made to discover the author's identity. … The suggestions made in this letter were that a set of twenty-six wires should be stretched upon insulated supports between the two places which it was desired to put in connection, and at each end of every wire a metallic ball was to be suspended, having under it a letter of the alphabet inscribed upon a piece of paper. … The message was to be read off at the receiving station by observing the letters which were successively attracted by their corresponding balls, as soon as the wires attached to the latter received a charge from the distant conductor. In 1787 Monsieur Lomond, of Paris, made the very important step of reducing the twenty-six wires to one, and indicating the different letters by various combinations of simple movements of an indicator, consisting of a pith-ball suspended by means of a thread from a conductor in contact with the wire. … In the year 1790 Chappe, the inventor of the semaphore, or optico-mechanical telegraph, which was in practical use previous to the introduction of the electric telegraph, devised a means of communication, consisting of two clocks regulated so that the second hands moved in unison, and pointed at the same instant to the same figures. … In the early form of the apparatus, the exact moment at which the observer at the receiving station should read off the figure to which the hand pointed was indicated by means of a sound signal produced by the primitive method of striking a copper stew pan, but the inventor soon adopted the plan of giving electrical signals instead of sound signals. … In 1795 Don Francisco Salva … suggested … that instead of twenty-six wires being used, one for each letter, six or eight wires only should be employed, each charged by a Leyden jar, and that different letters should be formed by means of various combinations of signals from these. … Mr. (afterwards Sir Francis) Ronalds … took up the subject of telegraphy in the year 1816, and published an account of his experiments in 1823," based on the same idea as that of Chappe. … "Ronalds drew up a sort of telegraphic code by which words, and sometimes even complete sentences, could be transmitted by only three discharges. … Ronalds completely proved the practicability of his plan, not only on [a] short underground line, …. but also upon an overhead line some eight miles in length, constructed by carrying a telegraph wire backwards and forwards over a wooden frame-work erected in his garden at Hammersmith. … The first attempt to employ voltaic electricity in telegraphy was made by Don Francisco Salva, whose frictional telegraph has already been referred to. On the 14th of May, 1800, Salva read a paper on 'Galvanism and its application to Telegraphy' before the Academy of Sciences at Barcelona, in which he described a number of experiments which he had made in telegraphing over a line some 310 metres in length. … A few years later he applied the then recent discovery of the Voltaic pile to the same purpose, the liberation of bubbles of gas by the decomposition of water at the receiving station being the method adopted for indicating the passage of the signals. A telegraph of a very similar character was devised by Sömmering, and described in a paper communicated by the inventor to the Munich Academy of Sciences in 1809. Sömmering used a set of thirty-five wires corresponding to the twenty-five letters of the German alphabet and the ten numerals. … Oersted's discovery of the action of the electric current upon a suspended magnetic needle provided a new and much more hopeful method of applying the electric current to telegraphy. The great French astronomer Laplace appears to have been the first to suggest this application of Oersted's discovery, and he was followed shortly afterwards by Ampere, who in the year 1820 read a paper before the Paris Academy of Sciences."

_G. W. De Tunzelmann, Electricity in Modern Life, chapter 9._

ELECTRICITY: A. D. 1786-1800. Discoveries of Galvani and Volta.

"The fundamental experiment which led to the discovery of dynamical electricity [1786] is due to Galvani, professor of anatomy in Bologna. Occupied with investigations on the influence of electricity on the nervous excitability of animals, and especially of the frog, he observed that when the lumbar nerves of a dead frog were connected with the crural muscles by a metallic circuit, the latter became briskly contracted. … Galvani had some time before observed that the electricity of machines produced in dead frogs analogous contractions, and he attributed the phenomena first described to an electricity inherent in the animal. He assumed that this electricity, which he called vital fluid, passed from the nerves to the muscles by the metallic arc, and was thus the cause of contraction. This theory met with great support, especially among physiologists, but it was not without opponents. The most considerable of these was Alexander Volta, professor of physics in Pavia. Galvani's attention had been exclusively devoted to the nerves and muscles of the frog; Volta's was directed upon the connecting metal. Resting on the observation, which Galvani had also made, that the contraction is more energetic when the connecting arc is composed of two metals than where there is only one, Volta attributed to the metals the active part in the phenomenon of contraction. He assumed that the disengagement of electricity was due to their contact, and that the animal parts only officiated as conductors, and at the same time as a very sensitive electroscope. By means of the then recently invented electroscope, Volta devised several modes of showing the disengagement of electricity on the contact of metals. … A memorable controversy arose between Galvani and Volta. The latter was led to give greater extension to his contact theory, and propounded the principle that when two heterogeneous substances are placed in contact, one of them always assumes the positive and the other the negative electrical condition. In this form Volta's theory obtained the assent of the principal philosophers of his time."

_A. Ganot, Elementary Treatise on Physics; translated by Atkinson, book 10, chapter 1._

Volta's theory, however, though somewhat misleading, did not prevent his making what was probably the greatest step in the science up to this time, in the invention (about 1800) of the Voltaic pile, the first generator of electrical energy by chemical means, and the forerunner of the vast number of types of the modern "battery."

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ELECTRICITY: A. D. 1810-1890. The Arc light.

"The earliest instance of applying Electricity to the production of light was in 1810, by Sir Humphrey Davy, who found that when the points of two carbon rods whose other ends were connected by wires with a powerful primary battery were brought into contact, and then drawn a little way apart, the Electric current still continued to jump across the gap, forming what is now termed an Electric Arc. … Various contrivances have been devised for automatically regulating the position of the two carbons. As early as 1847, a lamp was patented by Staite, in which the carbon rods were fed together by clockwork. … Similar devices were produced by Foucault and others, but the first really successful arc lamp was Serrin's, patented in 1857, which has not only itself survived until the present day, but has had its main features reproduced in many other lamps. … The Jablochkoff Candle (1876), in which the arc was formed between the ends of a pair of carbon rods placed side by side, and separated by a layer of insulating material, which slowly consumed as the carbons burnt down, did good service in accustoming the public to the new illuminant. Since then the inventions by Brush, Thomson-Houston, and others have done much to bring about its adoption for lighting large rooms, streets, and spaces out of doors."

_J. B. Verity, Electricity up to Date for Light, Power, and Traction, chapter 3._

ELECTRICITY: A. D. 1820-1825. Oersted, Ampere, and the discovery of the Electro-Magnet.

"There is little chance … that the discoverer of the magnet, or the discoverer and inventor of the magnetic needle, will ever be known by name, or that even the locality and date of the discovery will ever be determined [see COMPASS]. … The magnet and magnetism received their first scientific treatment at the hands of Dr. Gilbert. During the two centuries succeeding the publication of his work, the science of magnetism was much cultivated. … The development of the science went along parallel with that of the science of electricity … although the latter was more fruitful in novel discoveries and unexpected applications than the former. It is not to be imagined that the many close resemblances of the two classes of phenomena were allowed to pass unnoticed. … There was enough resemblance to suggest an intimate relation; and the connecting link was sought for by many eminent philosophers during the last years of the eighteenth and the earlier years of the present century."

_T. C. Mendenhall, A Century of Electricity, chapter 3._

"The effect which an electric current, flowing in a wire, can exercise upon a neighbouring compass needle was discovered by Oersted in 1820. This first announcement of the possession of magnetic properties by an electric current was followed speedily by the researches of Ampere, Arago, Davy, and by the devices of several other experimenters, including De la Rive's floating battery and coil, Schweigger's multiplier, Cumming's galvanometer, Faraday's apparatus for rotation of a permanent magnet, Marsh's vibrating pendulum and Barlow's rotating star-wheel. But it was not until 1825 that the electromagnet was invented. Arago announced, on 25th September 1820, that a copper wire uniting the poles of a voltaic cell, and consequently traversed by an electric current, could attract iron filings to itself laterally. In the same communication he described how he had succeeded in communicating permanent magnetism to steel needles laid at right angles to the copper wire, and how, on showing this experiment to Ampere, the latter had suggested that the magnetizing action would be more intense if for the straight copper wire there were substituted one wrapped in a helix, in the centre of which the steel needle might be placed. This suggestion was at once carried out by the two philosophers. 'A copper wire wound in a helix was terminated by two rectilinear portions which could be adapted, at will, to the opposite poles of a powerful horizontal voltaic pile; a steel needle wrapped up in paper was introduced into the helix.' 'Now, after some minutes' sojourn in the helix, the steel needle had received a sufficiently strong dose of magnetism.' Arago then wound upon a little glass tube some short helices, each about 2¼ inches long, coiled alternately right-handedly and left-handedly, and found that on introducing into the glass tube a steel wire, he was able to produce 'consequent poles' at the places where the winding was reversed. Ampère, on October 23rd, 1820, read a memoir, claiming that these facts confirmed his theory of magnetic actions. Davy had, also, in 1820, surrounded with temporary coils of wire the steel needles upon which he was experimenting, and had shown that the flow of electricity around the coil could confer magnetic power upon the steel needles. … The electromagnet, in the form which can first claim recognition … was devised by William Sturgeon, and is described by him in the paper which he contributed to the Society of Arts in 1825."

_S. P. Thompson, The Electromagnet, chapter 1._

ELECTRICITY: A. D. 1825-1874. The Perfected Telegraph.