3 i2 THE POPULAR SCIENCE MONTHLY. 



Meanwhile, the Newtonian theory of attraction, under the skillful 

 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 whirlpools of Descartes 

 offered hut 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 completely as the cumbrous epicycles 

 of Ptolemy had been dismantled by Copernicus and Kepler. The 

 mathematicians certified 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. Prophetic 

 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 divisibility in matter, or the cold- 

 ness 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 de- 

 cay, it was believed that the motion was, in a practical, if not in a 

 mathematical sense, perpetual. Thus it was that the splendors of 

 analysis dimmed the eyes of science to the intrinsic difficulties of 

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

 cealed the mystery that was lurking beneath it. A long experience 

 in the treatment of gravitation had supplied mathematicians with a 

 fund of methods and formulas suited to similar cases. As soon as 

 electricity, magnetism, and electro-magnetism took form, they also 

 were fitted out with a garment of attractive and repulsive forces act- 

 ing at a distance ; and the theories of Cavendish, Poisson, Aepinus, 

 and Ampere, indorsed as they were by such names as Laplace, Plana, 

 Liouville, and Green, met with general acceptance. 



The seeds, which were destined to take root in a later generation, 

 and disturb, if not dislodge, the prevalent interpretation of the force 

 of gravitation, were sown by a contemporary of Newton. They found 

 no congenial soil in which they could germinate and fructify until the 

 early part of the present century. At the present moment, we find 

 the luminiferous ether in quiet and undivided possession of the field 

 from w T hich the grosser material of ancient systems had been banished. 

 The plenum, reigns everywhere ; the vacuum is nowhere. Even the 

 corpuscidar theory of light, as it came from the hands of its founder, 

 required the reenforcement of an ether. Electricity and magnetism, 

 on a smaller scale, applied similar machinery. If there was a funda- 

 mental objection to the conception of forces acting at a distance, cer- 

 tainly the bridge was already built by which the difficulty could be 



