Electricity and Heat as Moving Powers. 69 



in this department. Moreover, in the face of such facts, we 

 need not wonder that we have, as yet, only obtained ^ part 

 of the power possessed by electricity. 



But it is to be remembered that there is a far better chance 

 of obtaining a larger portion of the theoretic power from 

 electricity than from heat, owing to the characters of the 

 agents. Let us attempt, in a few words, the explanation of 

 the reasons. The power of heat is developed, not by retain- 

 ing it as heat in a gaseous or liquid element, but by convert- 

 ing some of it into power, during the process of diluting or 

 diffusing the heat (from a state of intensity or concentration 

 in a comparatively small quantity of matter, such as the air 

 of the furnace and surface of the coke), by imparting it to 

 other colder matter. Now this process cannot be carried on 

 with the effect of obtaining power through the greater part 

 of the range of temperature, commencing at the heat of the 

 air at the moment of contact with the incandescent coal, but 

 can only commence at the comparatively low temperature at 

 which it is necessary to keep the apparatus (whether steam- 

 engine or air-engine) in which the heat is converted into 

 power. For example, it is obvious that the heat of a cubic 

 foot of air at 20,000° temperature (and the primary tem- 

 perature must be far higher), will generate scai'cely any more 

 steam in a boiler than 10 cubic feet of air at 2000°; and 

 yet a large extra amount of power might be obtained (had 

 we materials to stand the heat) out of the process of trans- 

 ferring the 20,000° of heat in 1 cubic foot into the 10 cubic 

 feet at 2000° ; and the large portion of this heat, which was 

 not yet rendered latent by the process, could be again used, as 

 at first supposed, with almost as much proportional efficiency 

 as if it were still in the most concentrated state. This con- 

 sideration accounts for the wide discrepancy between the 

 theoretic power due to heat and the power which is practi- 

 cally obtained from even the best Cornish engines ; in which, 

 nevertheless, scarce any heat is allowed to escape to waste, 

 except in the very diluted state of the warm condensation- 

 water. The above considerations may also indicate the direc- 

 tion in which inventive genius must work, in order to obtain 

 any greatly increased results. 



