238 APPENDIX B. 



deteriorations when its action has been sustained 

 for a time with any energy. 



The general and philosophic acceptation of the 

 words perpetual motion should include not only a 

 motion susceptible of indefinitely continuing itself 

 after a first impulse received, but the action of an 

 apparatus, of any construction whatever, capable 

 of creating motive power in unlimited quantity, 

 capable of starting from rest all the bodies of na- 

 ture if they should be found in that condition, of 

 overcoming their inertia; capable, finally, of find- 

 ing in itself the forces necessary to move the whole 

 universe, to prolong, to accelerate incessantly, its 

 motion. Such would be a veritable creation of 

 motive power. If this were a possibility, it would 

 be useless to seek in currents of air and water or 

 in combustibles this motive power. We should 

 have at our disposal an inexhaustible source upon 

 -which we could draw at will. 



NOTE B. The experimental facts which best 

 prove the change of temperature of gases by com- 

 pression or dilatation are the following: 



(1) The fall of the thermometer placed under 

 the receiver of a pneumatic machine in which a 

 vacuum has been produced. This fall is very sen- 

 sible on the Breguet thermometer: it may exceed 

 40 or 50. The mist which forms in this case 



