ch. viii.] ORGANIZATION OF THE SCIENCES. 207 



has boon quite independent of any supposed hieraichical 

 order. Often, too, their interactions are more complex than 

 as thus instanced — involve more sciences than two .... So 

 complete in recent days has become this consensus among the 

 sciences, caused either by the natural entanglement of their 

 phenomena, or by analogies in the relations of their 

 phenomena, that scarcely any considerable discovery con- 

 cerning one order of facts now takes place without very 

 shortly leading to discoveries concerning other orders." 1 



Mr. Spencer goes on to describe the infinitely complex 

 manner in which the various sciences act upon the advance- 

 ment of the arts, and are reacted upon by that advancement. 

 He enumerates the vast multitude of arts, involving the 

 knowledge of many distinct sciences, which enter into the 

 economical production of such an apparently simple article 

 as a child's calico frock. He shows that the various sciences 

 by turns stand in the relation of arts to each other; and that 

 often the mere process of observation in any one science 

 requires the aid of half a dozen other sciences. But it is 

 needless for me to go on quoting from an essay which i3 

 easily accessible, and which should be read from beginning 

 to end by everyone who wishes to understand the true 

 character of scientific progress. I prefer to add an illustra- 

 tion or two, suggested by the progress of science during the 

 nineteen years that have elapsed since that essay was 

 published ; and to observe how Kirchhoff's discoveries in 

 a pectrum-analysis — rendered possible only through a great 

 advance in chemical knowledge — have reacted upon 

 astronomy, enabling Mr. Huggins to determine the proper 

 motion of Sirius, and consequently, by putting it in our 

 power to ascertain the motions of all those stars which, 

 moving directly towards or away from us, yield no parallax, 

 have laid the foundations for a general theory of sidereal 

 dynamics, to be further elaborated in the future. Or to take 



1 Spencer's Essays, 1st series, pp. 181 — 183, 214, 215. 



