Philosophical State of the Physical Sciences. 497 



Newton's law of distance. He substitutes the word gravitation, 

 but only as a blind expression by which the facts are generalized. 

 According to Comte's philosophy, the laws of Newton are on an 

 equality with the laws of Kepler, only they are more compre- 

 hensive, and the glory of Kepler has the same stamp as that of 

 Newton. Hegel, the eminent German metaphysician, must have 

 looked at the subject in the same light when he wrote these 

 words : — ■" Kepler discovered the laws of free motion ; a discovery 

 of immortal glory. It has since been the fashion to say that 

 Newton first found out the truth of these rules. It has seldom 

 happened that the honour of the first discoverer has been more 

 unjustly transferred to another." Shelling goes further in the 

 same direction : he degrades the Newtonian law of attraction 

 into an empirical fact, and exalts the laws of Kepler into neces- 

 sary results of our ideas. 



Meanwhile the Newtonian theory of attraction, under the 

 skilful generalship of the geometers, went forth on its triumphal 

 march through space, conquering great and small, far and near, 

 until its empire became as universal as its name. The whirl- 

 pools of Descartes offered but a feeble resistance, and were finally 

 dashed to pieces by the artillery of the parabolic comets; and 

 the rubbish of this fanciful mechanism was cleaned out as com- 

 pletely as the cumbrous epicycles of Ptolemy had been dis- 

 mantled by Copernicus and Kepler. The mathematicians certi- 

 fied that the solar system was protected against the inroads of 

 comets, and the border warfare of one planet upon another, and 

 that its stability was secure in the hands of gravitation, if only 

 space should be kept open, and the dust and cobwebs which 

 Newton had swept from the skies should not reappear. Pro- 

 phetic eyes contemplated the possibility of an untimely end to 

 the revolution of planets, if their ever-expanding atmospheres 

 should rush in to fill the room vacated by the maelstroms of 

 Descartes, When it was stated that the absence of infinite di- 

 visibility in matter, or the coldness of space would place a limit 

 upon expansion, and, at the worst, that the medium would be 

 too attenuated to produce a sensible check in the headway of 

 planets, and when in more recent times even Encke's comet 

 showed but the slightest symptoms of mechanical decay, it was 

 believed that the motion was, in a practical, if not in a mathe- 

 matical sense, perpetual. Thus it was that the splendours of 

 analysis dimmed the eyes of science to the intrinsic difficulties 

 of Newton's theory, and familiarity with the language of attrac- 

 tion concealed the mystery that was lurking beneath it. A long 

 experience in the treatment of gravitation has supplied mathe- 

 maticians with a fund of methods and formulas suited to similar 

 cases. As soon as electricity, magnetism, and electromagnetism 



Phil. Mag. S. 4. No. 321. Suppl. Vol. 48. 2 K 



