Page:Popular Science Monthly Volume 44.djvu/56

From Wikisource
Jump to navigation Jump to search
This page has been validated.
48
THE POPULAR SCIENCE MONTHLY.

rent, and adapted to be attached directly to the ordinary electric supply circuits.

Ideal this method of cooking and heating certainly is, and ideal it is likely to remain. There are many things electricity can do—many things it is doing which were without the bounds of our expectation of even yesterday—but supplying heat in

PSM V44 D056 Electric coil heater.jpg
Fig. 12.—Electric Coil Heater.

economic contrast with coal and gas for the ordinary operations of the household is not one of them. This is, of course, upon the condition that the current is generated by the combustion of fuel. In situations in which the current is produced by water power, and in which fuel is scarce and dear, the unit of heat furnished by electricity may very well bear comparison with that by direct combustion; but that you can not start with combustion, suffer the tremendous loss of the steam engine, the various losses of the electrical apparatus, pay a profit to the electric supply company, and still compete in point of economy with the primary process of combustion, would seem to be a proposition too clear to need demonstration. Looked at from the point of view of percentages, the steam engine makes a return of but ten per cent of the heat energy of the fuel, the dynamo can hardly be depended upon in practice for more than ninety per cent, and the converter, when this is used, may be counted to absorb ten per cent of the energy delivered to it. This leaves in the one case but nine per cent and in the other a little over eight per cent of the original energy at the disposal of the consumer. Some of this must inevitably be lost in the final heating operation, for, though the apparatus be designed never so well, it can not have an efficiency