TEMPERATURE OF SPACE. 273 



Perhaps the position of our planetary system in the heavens 

 merits regard in the question under consideration. Besides the 

 sun, there are in the heavens millions of starry bodies which 

 transmit their luminous and calorific rays to the earth *. It is 

 therefore possible that different regions of infinite space may 

 possess different temperatures. This has been demonstrated by 

 the celebrated mathematician Poisson, who noticed that the 

 number of stars is so great that they form, as it were, a dome 

 around us. We know also that the sun and the planets are con- 

 stantly changing their position in space, and that probably the 

 sun with the planets revolves round a centre of a higher order 

 that is to say, round a fixed star of much larger size, and vastly 

 more distant. If, therefore, we may assume that the same 

 temperature does not prevail throughout all space in the heavens, 

 we shall obtain a simple explanation of the above-mentioned 

 phenomena. Suppose the sun with its planets, during the Mio- 

 cene epoch, to have traversed a portion of space warmer than 

 that in which it now moves, all the regions of the earth must 

 have participated equally in this increase of heat ; the temperate, 

 as well as the arctic zone, must have felt its influence. Hence 

 at that time the distribution of heat on the surface of the globe 

 would be more equable. In the epoch which may be termed 

 a year of the planetary system, colder periods alternated with 

 warmer ones : thus the Miocene period may be compared to the 

 summer, the Glacial period to the winter, and the existing geo- 

 logical age to the spring, of the planetary system. 



A good selection was made in the choice of the name Eocene 

 to indicate the commencement of the Tertiary period : it may 



of all geological ages, which formerly lived there. The soil of the ancient land 

 is preserved in vast deposits of coal, as well as in those of lignite, which abound 

 in so many localities, and also in the original sites of innumerable lacustrine 

 formations of Europe filled with organic remains. For example, in the case 

 of the Swiss Miocene, Prof. Heer finds in them the uninterrupted history of 

 the flora and fauna of Switzerland without the intercalation of any glacial 

 period. 



* According to the investigations of Mr. Huggins, the heat produced by 

 the radiation of the fixed stars is not unfelt on the earth, and may even be 

 measured. With a calorimeter constructed by himself he has obtained mani- 

 fest proofs of the heat furnished by Sirius, Pollux, and Arcturus. 



VOL. II. T 



