Part 2

"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.

"The European philosophers kept on groping. At the end of five years [after Oersted's discovery], 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 [1825] Mr. Peter Barlow, fellow of the Royal Society, who had encountered the question whether the lengthening of the conducting wire would produce any effect in diminishing the energy of the current transmitted, and had undertaken to resolve the problem. ... 'I found [he said] such a considerable diminution with only 200 feet of wire as at once to convince me of the impracticability of the scheme.' ... The year following the announcement of Barlow's conclusions, a young graduate of the Albany (N. Y.) Academy--by name Joseph Henry--was appointed to the professorship of mathematics in that institution. Henry there began the series of scientific investigations which is now historic. ... 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. ... Barlow had said that the gentle current of the galvanic battery became so weakened, after traversing 200 feet of wire, that it was idle to consider the possibility of making it pass over even a mile of conductor and then affect a magnet. {773} Henry's reply was to point out that the trouble lay in the way Barlow's magnet was made. ... Make the magnet 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 the 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 necessary 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. ... 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 telegraph was completely invented and demonstrated. There was nothing left to do, but to put up the posts, string the lines, and attach the instruments."

_P. Benjamin, The Age of Electricity, chapter 11._

"At last we leave the territory of theory and experiment and come to that of practice. 'The merit of inventing the modern telegraph, and applying it on a large scale for public use, is, beyond all question, due to Professor Morse of the United States.' So writes Sir David Brewster, and the best authorities on the question substantially agree with him. ... Leaving for future consideration Morse's telegraph, which was not introduced until five years after the time when he was impressed with the notion of its feasibility, we may mention the telegraph of Gauss and Weber of Göttingen. In 1833, they erected a telegraphic wire between the Astronomical and Magnetical Observatory of Göttingen, and the Physical Cabinet of the University, for the purpose of carrying intelligence from the one locality to the other. To these great philosophers, however, rather the theory than the practice of Electric Telegraphy was indebted. Their apparatus was so improved as to be almost a new invention by Steinheil of Munich, who, in 1837 ... succeeded in sending a current from one end to the other of a wire 36,000 feet in length, the action of which caused two needles to vibrate from side to side, and strike a bell at each movement. To Steinheil the honour is due of having discovered the important and extraordinary fact that the earth might be used as a part of the circuit of an electric current. The introduction of the Electric Telegraph into England dates from the same year as that in which Steinheil's experiments took place. William Fothergill Cooke, a gentleman who held a commission in the Indian army, returned from India on leave of absence, and afterwards, because of his bad health, resigned his commission, and went to Heidelberg to study anatomy. In 1836, Professor Mönke, of Heidelberg, exhibited an electro-telegraphic experiment, 'in which electric currents, passing along a conducting wire, conveyed signals to a distant station by the deflexion of a magnetic needle enclosed in Schweigger's galvanometer or multiplier.' ... Cooke was so struck with this experiment, that he immediately resolved to apply it to purposes of higher utility than the illustration of a lecture. ... In a short time he produced two telegraphs of different construction. When his plans were completed, he came to England, and in February, 1837, having consulted Faraday and Dr. Roget on the construction of the electric-magnet employed in a part of his apparatus, the latter gentleman advised him to apply to Professor Wheatstone. ... The result of the meeting of Cooke and Wheatstone was that they resolved to unite their several discoveries; and in the month of May 1837, they took out their first patent 'for improvements in giving signals and sounding alarms in distant places by means of electric currents transmitted through metallic circuits.' ... By-and-by, as might probably have been anticipated, difficulties arose between Cooke and Wheatstone, as to whom the main credit of introducing the Electric Telegraph into England was due. Mr. Cooke accused Wheatstone (with a certain amount of justice, it should seem) of entirely ignoring his claims; and in doing so Mr. Cooke appears to have rather exaggerated his own services. Most will readily agree to the wise words of Mr. Sabine: "It was once a popular fallacy in England that Messrs. Cooke and Wheatstone were the original inventors of the Electric Telegraph. The Electric Telegraph had, properly speaking, no inventor; it grew up as we have seen little by little."

_H. J. Nicoll, Great Movements, pages 424-429._

"In the latter part of the year 1832, Samuel F. B. Morse, an American artist, while on a voyage from France to the United States, conceived the idea of an electromagnetic telegraph which should consist of the following parts, viz: A single circuit of conductors from some suitable generator of electricity; a system of signs, consisting of dots or points and spaces to represent numerals; a method of causing the electricity to mark or imprint these signs upon a strip or ribbon of paper by the mechanical action of an electro-magnet operating upon the paper by means of a lever, armed at one end with a pen or pencil; and a method of moving the paper ribbon at a uniform rate by means of clock-work to receive the characters. ... In the autumn of the year 1835 he constructed the first rude working model of his invention. ... The first public exhibition ... was on the 2d of September, 1837, on which occasion the marking was successfully effected through one third of a mile of wire. Immediately afterwards a recording instrument was constructed ... which was subsequently employed upon the first experimental line between Washington and Baltimore. This line was constructed in 1843-44 under an appropriation by Congress, and was completed by May of the latter year. On the 27th of that month the first despatch was transmitted from Washington to Baltimore. ... The experimental line was originally constructed with two wires, as Morse was not at that time acquainted with the discovery of Steinheil, that the earth might be used to complete the circuit. {774} Accident, however, soon demonstrated this fact. ... The following year (1845) telegraph lines began to be built over other routes. ... In October, 1851, a convention of deputies from the German States of Austria, Prussia, Bavaria, Würtemberg and Saxony, met at Vienna, for the purpose of establishing a common and uniform telegraphic system, under the name of the German-Austrian Telegraph Union. The various systems of telegraphy then in use were subjected to the most thorough examination and discussion. The convention decided with great unanimity that the Morse system was practically far superior to all others, and it was accordingly adopted. Prof. Steinheil, although himself ... the inventor of a telegraphic system, with a magnanimity that does him high honor, strongly urged upon the convention the adoption of the American system." ... The first of the printing telegraphs was patented in the United States by Royal E. House, in 1846. The Hughes printing telegraph, a remarkable piece of mechanism, was patented by David E. Hughes, of Kentucky, in 1855. A system known as the automatic method, in which the signals representing letters are transmitted over the line through the instrumentality of mechanism, was originated by Alexander Bain of Edinburgh, whose first patents were taken out in 1846. An autographic telegraph, transmitting despatches in the reproduced hand-writing of the sender, was brought out in 1850, by F. C. Bakewell, of London. The same result was afterwards accomplished with variations of method by Charles Cros, of Paris, Abbé Caseli, of Florence, and others; but none of these inventions has been extensively used. "The possibility of making use of a single wire for the simultaneous transmission of two or more communications seems to have first suggested itself to Moses G. Farmer, of Boston, about the year 1852." The problem was first solved with partial success by Dr. Gintl, on the line between Prague and Vienna, in 1853, but more perfectly by Carl Frischen, of Hanover, in the following year. Other inventors followed in the same field, among them Thomas A. Edison, of New Jersey, who was led by his experiments finally, in 1874 to devise a system "which was destined to furnish the basis of the first practical solution of the curious and interesting problem of quadruplex telegraphy."

_G. B. Prescott, Electricity and the Electric Telegraph, chapter 29-40._

ELECTRICITY: A. D. 1831-1872. Dynamo Electrical Machines, and Electric Motors.

"The discovery of induction by Faraday, in 1831, gave rise to the construction of magneto-electro machines. The first of such machines that was ever made was probably a machine that never came into practical use, the description of which was given in a letter, signed 'P. M.,' and directed to Faraday, published in the Philosophical Magazine of 2nd August, 1832. We learn from this description that the essential parts of this machine were six horse-shoe magnets attached to a disc, which rotated in front of six coils of wire wound on bobbins." Sept. 3rd, 1832, Pixii constructed a machine in which a single horse-shoe magnet was made to rotate before two soft iron cores, wound with wire. In this machine he introduced the commutator, an essential element in all modern continuous current machines. "Almost at the same time, Ritchie, Saxton, and Clarke constructed similar machines. Clarke's is the best known, and is still popular in the small and portable 'medical' machines so commonly sold. ... A larger machine [was] constructed by Stöhrer (1843), on the same plan as Clarke's, but with six coils instead of two, and three compound magnets instead of one. ... The machines, constructed by Nollet (1849) and Shepard (1856) had still more magnets and coils. Shepard's machine was modified by Van Malderen, and was called the Alliance machine. ... Dr. Werner Siemens, while considering how the inducing effect of the magnet can be most thoroughly utilised, and how to arrange the coils in the most efficient manner for this purpose, was led in 1857 to devise the cylindrical armature. ... Sinsteden in 1851 pointed out that the current of the generator may itself be utilised to excite the magnetism of the field magnets. ... Wilde [in 1863] carried out this suggestion by using a small steel permanent magnet and larger electro magnets. ... The next great improvement of these machines arose from the discovery of what may be called the dynamo-electric principle. This principle may be stated as follows:--For the generation of currents by magneto-electric induction it is not necessary that the machine should be furnished with permanent magnets; the residual or temporary magnetism of soft iron quickly rotating is sufficient for the purpose. ... In 1867 the principle was clearly enunciated and used simultaneously, but independently, by Siemens and by Wheatstone. ... It was in February, 1867, that Dr. C. W. Siemens' classical paper on the conversion of dynamical into electrical energy without the aid of permanent magnetism was read before the Royal Society. Strangely enough, the discovery of the same principle was enunciated at the same meeting of the Society by Sir Charles Wheatstone. ... The starting-point of a great improvement in dynamo-electric machines, was the discovery by Pacinotti of the ring armature ... in 1860. ... Gramme, in 1871, modified the ring armature, and constructed the first machine, in which he made use of the Gramme ring and the dynamic principle. In 1872, Hefner-Alteneck, of the firm of Siemens and Halske, constructed a machine in which the Gramme ring is replaced by a drum armature, that is to say, by a cylinder round which wire is wound. ... Either the Pacinotti-Gramme ring armature, or the Hefner-Alteneck drum armature, is now adopted by nearly all constructors of dynamo-electric machines, the parts varying of course in minor details." The history of the dynamo since has been one of a gradual perfection of parts, resulting in the production of a great number of types, which can not here even be mentioned.

_A. R. von Urbanitzky, Electricity in the Service of Man, pages 227-242._

_S. P. Thompson, Dynamo Electrical Machines._

ELECTRICITY: Electric Motors.