4 COSMOS. 



sible to mathematical treatment, has been the means of in- 

 creasing in the most marvellous manner the splendour of the 

 higher forms of analysis, and has equally enlarged the limits 

 of the extensive domain of optics ; our earthly sphere, on 

 the other hand, by its heterogeneity of elements, and by the 

 complicated play of the expressions of force inherent in matter, 

 has formed a basis for chemistry, and for all those branches 

 of physical science which treat of phenomena, that have not 

 as yet been found to be connected with vibrations generating 

 heat and light. Each sphere has, therefore, in accordance 

 with the nature of the problems which it presents to our 

 investigation, exerted a different influence on the intellectual 

 activity and scientific knowledge of mankind. 



All celestial bodies, excepting our own planet and the 

 aerolites which are attracted by it, are, to our conception com- 

 posed only of homogeneous gravitating matter, without any 

 specific or so-called elementary difference of substances. 

 Such a simple assumption is, however, not by any means 

 based upon the inner nature and constitution of these remote 

 celestial orbs, but arises merely from the simplicity of the 

 hypotheses, which are capable of explaining and leading us 

 tc predict the movements of the heavenly bodies. This 

 idea arises, as I have already had occasion frequently to re- 

 mark (Cosmos, vol. i, pp. 44 49 and pp. 124 125 ; vol. iii, 

 pp. 2, 18, and 22 28), from, the exclusion of all recognition 

 of heterogeneity of matter, and presents us with the solu- 

 tion of the great problem of celestial mechanics, in which 

 all that is variable in the uranological sphere is subjected to 

 the sole control of dynamical laws. 



Periodical alternations of light upon the surface of the 

 planet Mars do indeed point, in accordance with its different 

 reasons of the year, to various meteorological processes, and 

 to the polar precipitates excited by cold in the atmosphere of 

 that planet, (Cosmos, vol. iv, p. 504). Guided by analogies 

 and reasoning, we may indeed here assume the presence of 

 ice or snow (oxygen and hydrogen), as in the eruptive 

 masses or the annular plains of the moon we assume the 

 existence of different kinds of rock on our satellite, but direct 

 observation can teach us nothing in reference to these points. 

 .urea Newton ventured only on conjectures regarding the 

 elementary; constitution of the planets which belong to our 



