S82 Changes of Temperature of Air. 



their axis*, has not, I think, hitherto received the attention it 

 deserves. I believe that most phaenomena may be explained 

 by adapting it to the great electro-chemical discovery of Fa- 

 raday, by which we know that each atomic element is associ- 

 ated with the same absolute quantity of electricity. Let us 

 suppose that these atmospheres of electricity, endowed to a 

 certain extent with the ordinary properties of matter, revolve 

 with vast velocity round their respective atoms ; and that the 

 velocity of rotation determines what we call temperature. In 

 an aeriform fluid we may suppose that the attraction of the at- 

 mospheres by their respective atoms, and that of the atoms 

 towards one another, are inappreciable for all pressures to 

 which the law of Boyle and Mariotte applies; and that, con- 

 sequently, the centrifugal force of the revolving atmospheres 

 is the sole cause of expansion on the removal of pressure. By 

 this mode of reasoning, the law of Boyle and Mariotte receives 

 an easy explanation, without recourse to the improbable hy- 

 pothesis of a repulsion varying in a ratio different from that of 

 the inverse square. The phaenomena described in the present 

 paper, as well as most of the facts of thermo-chemistry, agree 

 with this theory ; and in order to apply it to radiation, we have 

 only to admit that the revolving atmospheres of electricity 

 possess, in a greater or less degree, according to circumstances, 

 the power of exciting isochronal undulations in the aether 

 which is supposed to pervade space. 



The principles 1 have adopted lead to a theory of the steam- 

 engine very different from the one generally received, but at 

 the same time much more accordant with facts. It is the opi- 

 nion of many philosophers that the mechanical power of the 

 steam-engine arises simply from the passage of heat from a hot 

 to a cold body, no heat being necessarily lost during the trans- 

 fer. This view has been adopted by Mr. E. Clapeyron in a 

 very able theoretical paper, of which there is a translation in 

 the 3rd part of Taylor's Scientific Memoirs. This philoso- 

 pher agrees with Mr. Carnot in referring the power to vis viva 

 developed by the caloric contained by the vapour, in its pass- 

 age from the temperature of the boiler to that of the con- 

 denser. I conceive that this theory, however ingenious, is op- 

 posed to the recognised principles of philosophy, because it 

 leads to the conclusion that vis viva may be destroyed by an 

 improper disposition of the apparatus: thus Mr. Clapeyron 

 draws the infierence, that "the temperature of the fire being 

 from 1000° (C.) to 2000° (C.) higher than that of the boiler, 

 there is an enormous loss of vis viva in the passage of the heat 

 from the furnace into the boiler." Believing that the power 

 * Elements of Chemical Philosophy, vol. i. p. 94. 



