64 GENERATION AND DESTRUCTION OF HEAT. 



In the first case, the heat produced in the circuit corres- 

 pends to the heat of the chemical effects in the battery — is 

 merely the latent heat of the elements combined transferred 

 to the coil ; in the second case, a similar amount of heat is 

 generated without any chemical action, solely by the " work" 

 done in moving the machine. In the third case, the same 

 amount of heat is developed in the coil, but the chemical 

 action in the battery is increased or diminished in exact 

 proportion to the electro-motive force, with or against the 

 current, induced by the motion of the armature. So that, 

 '"the heat due to a given, chemical action is subject to an 

 increase or diminution directly proportional to the intensity 

 of the magneto-electricity assisting or opposing the voltaic 

 current." * We have, therefore, in magnetic-electricity, an 

 agent, capable by simple mechanical means of destroying or 

 generating heat." Having thus verified the first part of his 

 prediction, he now turns to the second part. 



He says: " Having proved that heat is generated by the 

 magneto-electrical machine, and that by means of the 

 inductive power of magnetism we can diminish or increase 

 at pleasure the heat due to chemical changes, it became an 

 object of great interest to inquire whether a constant ratio 

 existed between it and the mechanical power gained and 

 lost. For this purpose, it was necessary to repeat some of 

 the previous experiments, and to ascertain, whether at the 

 same time, that mechanical force was necessary in order to 

 turn the apparatus." 



His previous experience in measuring the power of his 

 electro-magnetic engines now stands him in good stead, 

 and he makes thirteen experiments, driving the apparatus 

 as a magneto-electric machine, using it as an electro- 

 magnetic engine, varying the intensity of his magnets and 



