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 



economic contrast with coal 

 and gas for the ordinary op- 

 erations 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 compari- 

 son with that by direct com- 

 bustion; but that you can 

 not start with combustion, 

 suffer the tremendous loss of 

 the steam engine, the various 

 losses of the electrical appa- 

 ratus, pay a profit to the elec- 

 tric 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 in- 

 evitably be lost in the final heating operation, for, though the ap- 

 paratus be designed never so well, it can not have an efficiency 



FIG. 12. ELECTRIC COIL HEATER. 



