Page:Popular Science Monthly Volume 49.djvu/234

220 force will more and more exclude heat from the chain of transformations which issue in the locomotive's flight, in the whirl of factory and mill; and thus in some degree is allayed the fear, never well grounded, that when the coal fields of the world are spent, civilization must collapse. As the electrician hears this foreboding, he recalls how much fuel is wasted in converting heat into electricity. He looks beyond either turbine or shaft turned by wind or tide, and, remembering that the zinc dissolved in his battery yields at his will its full content of energy, either as heat or electricity, he asks. Why may not coal and forest tree, which are but other kinds of fuel, be made to do the same?

In another field let us observe electricity as a factor of fruitfullness quite as singular. It was at first the chemist who emancipated electricity for new and myriad uses. His successor to-day is the engineer, who wins his spurs by bringing his generator to practical perfection, by improving his steam and gas engines to double their efficiency of thirty years ago. If to the engineer and mechanic the electric art owes much, magnificently has the debt been repaid. As we discover in replacing at our street door an old-fashioned moving bell pull by an electric wire armed with a push button, electricity transmits motion without movement of its conductor as a mass. Availing himself of this golden property, the machinist removes from his shop a labyrinth of wheels and belts and puts in their stead a few wires at rest, each in charge of the motor actuating a machine. Manifold gains result. The power needed to whirl these wheels and belts is saved, and when but one or two machines of a large number are to be set in motion the economy rises to a high figure, while the workshop is lighter, cleaner, more wholesome in every way. Since electricity is of all phases of energy the easiest to preserve from losses resembling leakage or friction, the current can not only be distributed throughout the largest workshop with convenience and economy, it can be sent to the shop from an engine or a water wheel many miles away, as in connecting motors at Buffalo to dynamos at Niagara, twenty-seven miles distant. With the transmission of electricity for distances vastly exceeding twenty-seven miles we have long been familiar in the telegraph. It is by improving the coverings which prevent the current escaping from its wire, by taking advantage of the fact that a wire can almost as well carry a current of high tension as of low, and, above all, by increasing the quantity of the current so as to make the enterprise worth while, that the telegraphy of power has followed upon the telegraphy of mere signals.

In the telegraph at work over long distances a remarkable peculiarity of electricity displays itself. In days of yore, when letters were intrusted to a chain of messengers, each of whom bore