yo2 



VARIATIONS IN TEMPERATURE OF SPACE. 



[Ch/XIII. 



mathematician and nhilosoDher, M 



He 



begins by assuming, 1st, that the sun and our planetary 

 system are not stationary, but carried onward by a common 

 movement through space; 2dly, that every point in space 

 receives heat as well as light from innumerable stars sur- 

 rounding it on all sides, so that if a right line of indefinite 

 length be produced in any direction from such point, it must 

 encounter a star either visible or invisible to us. 3dly ? 

 he then goes on to assume, that the different regions of 

 space, which in the course of millions of years are traversed 

 by our system, must be of very unequal temperature, inas- 

 much as some of them must receive a greater, others a less 

 quantity of radiant heat from the great stellar inclosure. 

 If the earth, he continues, or any other large body, pass from 

 a hotter to a colder region, it would not readily lose in the 



imb 



region, 



but retain a temperature increasing downwards from the 

 surface, as is the actual condition of our planet.*" 



Now the opinion originally suggested by Sir W. HerscheL 



i 



that our sun and its attendant planets were all 

 onward through space, in the direction of the constellation 



moving 



Hercules, is ver 

 to be confirmed. 



climates. Mr. Hopk 



[j thought by modern astronomers 

 3 amount of the movement is still 

 >ed must be its extent before this 

 material alteration in the terrestrial 

 when treating of this theory, re- 



marked 



remote 



distant from each other, that there are no points in space 

 among them, where the intensity of radiating heat would be 



o'm 





except at points very near to each star. Thus, in order that 

 the earth should derive a degree of heat from stellar radia- 

 tion comparable to that now derived from the sun, it must 

 be in close proximity to some particular star, leaving the 

 aggregate effect of radiation from the other stars nearly the 

 same as at present. This approximation, however, to a single 



* Poisson, Theorie Matliemat. de la Chaleur, Comptes Eendus de l'Acad. des Sci., 



Jan. 30. 1837. 







