Another branch of electric development concerns the storage of electricity. The storage battery is based upon principles discovered by Gaston Planté, and applied, since 1881, by Brush, by Faure, and others. Some of the larger lighting stations employ as reservoirs of electric energy large batteries charged by surplus dynamo current. This is afterwards drawn upon when the consumer’s load is heavy, as during the evening. The storage battery is, however, a heavy, cumbrous apparatus, of limited life, easily destroyed unless guarded with skill. If a form not possessing these faults be ever found, the field of possible application is almost limitless. The above by no means complete account of the progress in electric applications during the century just closed should properly be supplemented by an account of the accompanying great advances regarded from the purely scientific aspect. It is, however, only possible to make a brief reference thereto within the limits of this article. The scientific study of electricity and the application of mathematical methods in its treatment has kept busy a host of workers and drawn upon the resources of the ablest minds the age has produced. Gauss, Weber, Ampère, Faraday, Maxwell, Helmholtz, are no longer with us. Of the early founders of the science we have yet such men as Lord Kelvin, formerly Sir William Thomson, Mascart, and others, still zealous in scientific work. Following them are a large number, notable for valuable contributions to the progress of electrical science, in discoveries, in research, and in mathematical treatment of the various problems presented. Modern magnetism took form in the hands of Rowland, Hopkinson, Ewing, and many other able workers. Maxwell’s electro-magnetic theory of light is confirmed by the brilliant researches of the late Dr. Hertz, too early lost to science. Hertz proved that all luminous phenomena are in essence electrical. The wireless telegraphy of to-day is a direct outcome of Hertz’s experiments on electric waves. It is but little more than ten years since Hertz announced his results to the world. His work, supplemented by that of Branly, Lodge, Marconi, and others, made wireless telegraphy a possibility.