1864.] 345 [Chase. 



pleasure and instruction he had given to the members by this 

 exhibition. 



Mr. Lesley drew the attention of the members present to 

 the beautiful recent microscopical investigations of Prof. 

 Sorby into the metamorphic condition of rocks. 



Mr. Chase referred to the communication which he bad 

 made at the last stated meeting, and made further remarks 

 respecting the alleged connection between the variable rate 

 of the earth's rotation and the mean temperature of given 

 parts of its surface. 



Mr. Colburn's inquiry into the nature of heat suggests some in- 

 teresting speculations concerning other effects of rotation than those 

 that can be measured by the barometer. Recognizing the impossi- 

 bility that the sun should warm the whole solar system, as a simply 

 incandescent body, — the imprubability that its heat should result from 

 continuous combustion, and the probable approximate uniformity of 

 temperature in the upper regions of the atmosphere, in summer and 

 in winter, by day and by night, Mr. Colburn looks for the principal 

 sources of heat in the earth itself He supposes, 1, that the solar 

 attraction tends to draw into closer proximity the particles of air on 

 the heated side, and to separate them on the night-side of the earth, 

 thus producing heat of couipression, and cold of expansion : 2, that 

 the change of eastward velocity from 69,000 miles per hour at mid- 

 night, to 67,000 miles at noon, (s/c) necessarily produces a con- 

 version of motion into heat, and of heat into motion : and 3, that if 

 the earth is moving in a resisting medium, by which it is so retarded 

 that it approaches the sun at the rate of 1,000,000 miles in 3,000,000 

 years, its " lift" involves the annual abstraction of a heat-force equiva 

 lent to 752,665,108,390,000 horse-power! 



The third hypothesis has been often broached; the indications of 

 a resisting ether, which, as we have seen, are furnished by the 

 hourly barometric means, may, perhaps, yield the data for its final 

 verification or rejection. The supposed separating effect of the 

 sun's action in the most remote portions of the atmosphere, is so 

 problematical that it seems hardly deserving of any consideration, 

 and even if it existed, it is difficult to understand how it could pro- 

 duce a difference of more than a fraction of a degree in the range of 

 the thermometer. The alternate acceleration and retardation of 

 orbital velocity, can produce no accumulation of heat to supply any 



VOL. IX. — 2u 



