XLIII.] CLASSIFICATION OF THE SCIENCES. 211 



smaller than these; for the subject-matters of the twin 

 sciences of meteorology and geology are not only special 

 to each planet, but are confined to the surface of the 

 planet: the domain of meteorology is confined to a few- 

 miles of height above the surface, and that of geology to 

 about as many of depth below. And the phenomena of 

 the distribution of life, again, are for the most part incom- 

 parably smaller than these : the largest trees are of insig- 

 nificant size in comparison with the mountain ; coral-reefs 

 are the only products of life that attain to geographical 

 importance, and they are small in comparison with conti- 

 nents. The laws of the distribution of living species on the 

 surface of the earth are united with palfeontology, or the 

 science of the fossil remains of extinct forms of life. The 

 subject of the distribution of living species may be called 

 geographical biology, and palaeontology may be called 

 geological biology ; but these form the subject of a single 

 science : the laws which determine the distribution of 

 species in the present cannot be separated from those 

 which have determined the distribution and the succession 

 of species in the past. 



"VVe have seen that, in the order of the vastness and Astro- 



the simplicity of the phenomena, astronomy comes first ^°^^y- 



among the cosmic sciences. Next to astronomy are those 



which treat of phenomena whereof the magnitude is such 



as to embrace an entire planet. There are three sciences 



W'hich treat of phenomena of this order of magnitude. 



First, the theory of the force of terrestrial magnetism. Terrestrial 



its distribution, and its fluctuations ; — this is not iden- ^^S*^*^*" 

 ' ' ism. 



tical with the abstract laws of magnetism, but is an appli- 

 cation thereof, just as astronomy is an application of the 

 abstract laws of dynamics. Second, meteorology, or the Meteoro- 

 theory of atmospheric changes and of the laws of climate ; °^' 

 — this science chiefly consists of applications of the 

 laws of heat and electricity to a great variety of circum- 

 stances, though it has a branch which stands in the same 

 relation to the laws of radiance, and treats of such 

 optical phenomena as rainbows and halos. Third, oceano- 



p2 



