Inventions in the Century

by William Henry Doolittle

We have seen that Davy produced a brilliant electric light with two pieces of charcoal in the electric circuit of a voltaic battery. Greener and Staite revived this idea in a patent in 1845. Shortly after Nollet’s machine, F. H. Holmes of England improved it and applied the current directly to the production of electric light between carbon points. And Holmes and Faraday in 1857 prepared this machine for use.

On the evening of December 8, 1858, the first practical electric light, the work of Faraday and Holmes, flashed over the troubled sea from the South Foreland Lighthouse. On June 6, 1862, this light was also introduced into the lighthouse at Dungeness, England. The same light was introduced in French lighthouses in December, 1863, and also in the work on the docks of Cherbourg. At this time Germany was also awake to the importance of this invention, and Dr. Werner Siemens of Berlin was at work developing a machine for the purpose into one of less cost and of greater use. Inventors were not yet satisfied with the power developed from either the voltaic battery or the magneto-electric machine, and continued to improve the latter.

In 1867, the same year that Faraday died, and too late for him to witness its glory, came out the most powerful magneto-electric machine that had yet been produced. It was invented by Wilde of London, and consisted of very large electro-magnets, or field magnets, receiving their electric power from the “lines of force” discovered by Faraday, radiating from the poles of a soft iron magnet, combined with a small magneto-electric machine having permanent magnets, and by which the current developed in the smaller machine was sent through the coils of the larger magnets. By this method the magnetic force was vastly multiplied, and electricity was produced in such abundance as to fuse thick iron wire fifteen inches long and one-fourth of an inch in diameter, and to develop a magnificent arc light. Quickly succeeding the Wilde machine came independent inventions in the same direction from Messrs. G. Farmer of Salem, Mass., Alfred Yarley and Prof. Charles Wheatstone of England, and Dr. Siemens of Berlin, and Ladd of America. These inventors conceived and put in practice the great idea of employing the current from an electro-magnetic machine to excite its own electric magnet. They were thus termed “self-exciting.” The idea was that the commutator (an instrument to change the direction, strength or circuit of the current) should be so connected with the coils of the field magnets that all or a part of the current developed in the armature would flow through these coils, so that all permanent magnets might be dispensed with, and the machine used to excite itself or charge its own field magnets without the aid of any outside charging or feeding mechanism.

Mr. Z. Gramme, of France, a little later than Wilde made a great improvement. Previously, machines furnished only momentary currents of varying strength and polarity; and these intermittent currents were hard to control without loss in the strength of current and the frequent production of sparks. Gramme produced a machine in which, although as in other machines the magnetic field of force was created by a powerful magnet, yet the armature was a ring made of soft iron rods, and surrounded by an endless coil of wire, and made to revolve between the poles of the magnet with great rapidity, producing a constant current in one direction. By Faraday’s discovery, when the coil of the closed circuit was moved before the poles of the magnet, the current was carried half the time in one direction and half in the other, constituting what is called an alternating current. Gramme employed the commutator to make the current direct instead of alternating.

Dynamo-electric machines for practical work of many kinds had now been born and grown to strength.

In addition to these and many other electrical machines this century has discovered several ways by which the electricity developed by such machines may be converted into light. I. By means of two carbon conductors between which passes a series of intensely brilliant sparks which form a species of flame known as the voltaic arc, and the heat of which is more intense than that from any other known artificial source. II. By means of a rod of carbon or kaolin, strip of platinum or iridium, a carbon filament, or other substance placed between two conductors, the resistance opposed by such rod, strip, or filament to the passage of the current being so great as to develop heat to the point of incandescence, and produce a steady white and pure light. Attempts also have been made to produce illumination by what is called stratified light produced by the electric discharge passing through tubes containing various gases. These tubes are known as Geissler tubes, from their inventor. Still another method is the production of a continuous light from a vibratory movement of carbon electrodes to and from each other, producing a bright flash at each separation, and maintaining the separations at such a rate that the effect of the light produced is continuous. But these additional methods do not appear as yet to be commercially successful.

It must not be overlooked that before dynamo-magneto-electric machines were used practically in the production of the electric light for the purposes of illumination, the voltaic battery was used for the same purpose, but not economically.

The first private dwelling house ever lighted in America, or doubtless anywhere else, by electricity, was that of Moses G. Farmer, in Salem, Massachusetts, in the year 1859. A voltaic battery furnished the current to conducting wires which led to two electric lamps on the mantel-piece of the drawing-room, and in which strips of platinum constituted the resisting and lighting medium. A soft, mild, agreeable light was produced, which was more delightful to read or sew by than any artificial light ever before known. Either or both lamps could be lighted by turning a button, and they were maintained for several weeks, but were discontinued for the reason that the cost of maintaining them was much greater than of gas light.

It was in connection with the effective dynamo-electric apparatus of M. Gramme above referred to that the electric candle invented by M. Paul Jablochoff became soon thereafter extensively employed for electric lighting in Paris, and elsewhere in Europe. This invention, like the great majority of useful inventions, is noted for its simplicity. It consists of two carbon pencils placed side by side and insulated from each other by means of a thin plate of some refractory material which is a non-conductor at ordinary temperatures, but which becomes a conductor, and consequently a light, when fused by the action of a powerful current. Plaster of Paris was found to be the most suitable material for this purpose, and the light produced was soft, mellow, slightly rose-coloured, and quite agreeable to the eye.

It having been found that carbon was better adapted for lighting purposes than platinum or other metals, by reason of its greater radiating power for equal temperatures, and still greater infusibility at high temperatures, inventors turned their attention to the production of the best carbon lamp.