Among edifices now entirely illuminated by the Swan system may be mentioned twenty-one steam vessels, including several war ships—the _City of Rome_, an Anchor Liner, which is second only to the _Great Eastern_ in point of size, and several passenger boats in the Cunard and White Star Lines. One of the greatest objections to gas as an indoor illuminant is the fact that not only does it burn a large amount of the oxygen of the air, but it also gives off during combustion carbonic acid gas and other poisonous vapors, besides a great amount of heat, thus vitiating the atmosphere. In public buildings where there is much gas burnt and little ventilation, this is seen to advantage, the air becoming in a short space of time hot and unwholesome. Now in the case of the incandescent electric light, this is altogether altered, the incandescent filament which produces the light, although in itself enormously hot, is too small in point of size to radiate much heat, and the fact of its being hermetically enclosed in a glass globe, which is impervious to the atmosphere, entirely prevents the escape of any noxious gases. The same circumstance prevents there being any consumption of oxygen. These facts make the electric light far more wholesome than gas for the illumination of music-halls, churches, or other places of concourse. In a recent trial in the Town Hall at Birmingham, the employment of gas raised the temperature of the atmosphere thirty-eight degrees in three hours, while the building was equally well lighted with electricity for seven hours with a rise in temperature of only two degrees. Thus, after a period of lighting by electricity 2.33 times as long as by gas, the temperature at the ceiling was increased by only 1-19th of the amount due to gas. Another great advantage consequent to the employment of incandescent lighting, is the greater immunity from accidental fire; for as the carbon filament is instantly entirely consumed, the moment the glass envelope is broken it is impossible for the lamp to ignite anything in its vicinity however inflammable. The experiment has been tried of breaking a lighted incandescent lamp in a vessel containing gunpowder, with perfect safety. As these lamps may be placed in any position, they lend themselves very readily to ornamental and decorative purposes. At the recent electrical exhibition at the Crystal Palace a very beautiful chandelier of Edison lamps was shown, in which the lamps, which were of very small size, formed the petals of finely worked glass and brass flowers. This chandelier had a really magnificent effect when lighted. These and other facts too numerous to mention, demonstrate that electricity, when properly applied, will be a far more elegant, safe, and wholesome agent for illuminating purposes, than coal-gas as now employed. But in order to have the full benefits of its use, a system is required by which the electric current shall be produced and conveyed to the lamps.