Mr. Edison has achieved triumphs not only in giving sound its lasting registration, but in producing an electric light of new economy. Both exploits proceeded upon a masterly knowledge of properties. A century ago candles provided illumination both to rich and poor, the sole difference being that wax shone in the palace and tallow in the hut. The oil lamps which gleamed in the lighthouses of England and America, for all their bigness, were plainly of kin to the Eskimo saucer filled with blubber, edged with moss as wick. Yet for ages, from every hearth in Christendom, there had been the promise of better things as bituminous coals, or sticks of wood, had cheered as much by their light as by their warmth. We owe much to James Watt, who improved the steam-engine and gave it essentially the form it retains to the present hour. We owe also a weighty debt to an assistant of his, William Murdock, who, thanks to a suggestion from Lord Dundonald, attentively observed the process by which coals produce light. He saw that under stress of intense heat the solid fuel emitted streams of gas which burned with great brilliancy. Here gas-making and gas-burning went on at the same moment in the same place; might the process be separated, so that gas might be made here, and burned elsewhere at any convenient time? An experiment proved the project to be feasible, and forthwith the Soho Works, near Birmingham, in which Watt’s engines were built, were lighted by gas. Such was the beginning of an industry now important in many ways. To-day gas not only yields light, but heat and power, while, especially in metallurgy, fuels are more and more used after reduction to the gaseous form. How the Gas Mantle was Invented.