THE ASTRONOMICAL VIEW OF NATURE. 



347 



The great prominence given by Laplace to the gravita- 

 tional explanation of all natural phenomena, the fact that 

 all the observable movements of the universe, the shape 

 and size of the moving masses, and the orbits they de- 

 scribe, as well as many phenomena observable on the 

 surface of our globe, such as the aberration and refraction 

 of light, the phenomena of the tides, of atmospheric pres- 

 sure, and some of the more important molecular properties 

 of matter, could be perfectly or approximately described, 

 calculated, and predicted by gravitation or analogous at- 

 tractions, gave to what we may call following a hint 

 of Clerk Maxwell's the astronomical method ^ of con- 



doubt in his mind that such pheno- 

 mena " are owing to attractive and 

 repulsive forces between molecule 

 and molecule" ('Expos.,' 6"' ed., 

 p. 328). He saw in molecular at- 

 traction the cause of the solidity of 

 bodies, of chemical affinities, and of 

 the properties of chemical satura- 

 tion, which Berthollet had developed 

 about that time ('Expos.,' p. 360) ; 

 he thinks it likely that the law of 

 molecular attraction is the same for 

 all bodies, and he finally dwells on 

 the question whether the attraction 

 of gravity and molecular attraction 

 could be united under one common 

 law or expression (p. 363), and 

 throws out the idea that thus the 

 phenomena of physics and astro- 

 nomy might be brought under one 

 general law, adding, however, signi- 

 ficant!}', " Mais I'impossibilite de 

 connaitre les figures des molecules 

 et leurs distances mutuelles, rend 

 ces explications vagues et inutiles a 

 I'avancement des sciences." 



^ " Cavendish, Coulomb, and 

 Poisson, the founders of the exact 

 sciences of electricity and magnet- 

 ism, paid no regard to those old 

 notions of ' magnetic effluvia ' and 

 ' electric atmospheres ' which had 



been put forth in the previous 

 century, but turned their undivided 

 attention to the determination of 

 the law of force, according to which 

 electrified and magnetised bodies 

 attract or repel each other. In this 

 way the true laws of these actions 

 were discovered, and this was done 

 by men who never doubted that 

 the action took place at a distance, 

 without the intervention of any 

 medium, and who would have re- 

 garded the discovery of such a 

 medium as complicating rather 

 than as explaining the undoubted 

 phenomena of attraction. . . . 

 Ampere, by a combination of 

 mathematical skill with experi- 

 mental ingenuity, first proved that 

 two electric currents act on one 

 another, and then analysed this 

 action into the resultant of a sj's- 

 tem of push-and-puU forces be- 

 tween the elementary parts of 

 these currents. . . . Whereas the 

 general course of scientific method 

 then consisted in the application 

 of the ideas of mathematics and 

 astronomy to each new investiga- 

 tion in turn, Faraday seems to 

 have had no opportunity of ac- 

 quiring a technical knowledge of 



