238 A'AXS^Ii, C/TY KEVJEW OF SCIENCE. 



universal ether appears to have no specific heat may be owing to some such con- 

 dition of things as is here pointed out. The state of things which makes possible 

 the fifih condition, as before explained, gives us also the sixth and last, "Its 

 energy is unchangeable in time. * * '^ Its activity is incessant and 

 inexhaustible." One difficulty that has beset the undulatory theory of light has 

 been the supposed resistance to planetary motion it would produce. The condi- 

 tions of our theory of gravity are such that there could not possibly be any re- 

 sistance to a falling body by its presence for the simple reason that the body could 

 not fall without it. A balloon is not resisted in its rise by the atmosphere. It 

 would not be able to rise without it. The resistance of ether is in a direction 

 opposite to gravity. 



This guess at the cause of gravity you will perceive meets one after another 

 of the difficulties hitherto experienced by kinetic theories, but you are not on this 

 account to imagine that the true solution is found. Many a mere fiction has not 

 only answered to known conditions of an order of phenomenal manifestations, as 

 this does, but has also become a successful working hypothesis, which this has not. 

 Such theories if used properly, however, are often excellent scaffolds for the mind 

 to scale upon and build to the true. 



In consonance with the philosophic part of this book the author attacks phys- 

 ical science in nearly every one of its great theories. Chemistry and molecular 

 physics suffer the severest at his hands. In the concluding chapter he denies 

 holding the metaphysical belief of the absolute continuity of matter, yet most of 

 the work is taken up with an endeavor to overcome the common idea of its dis- 

 crete nature. His attack upon hard, inelastic atoms is well timed and sound, but 

 when he from this ground battles Avogadro's Law, Cauchy's finite spaces, Max- 

 well's kinetic theory of gases and Tyndall's atomic cause of light undulations, it 

 appears as if he stretched his points and made our ignorance do service for 

 knowledge. No living being can frame a theory that will not constantly be seen 

 in new lights with every progress of knowledge. No matter how perfect it may 

 be it is constantly subject to new strains and new explanations because of new and 

 unlooked for relations. Time after time they all must be challenged. It does 

 not therefore follow that if a theory appears to fail at some one point because we 

 have not all the facts, the theory is false. Take the Judge's objections to 

 Avogadro's law for example, and we will see that they are founded entirely on 

 our lack of knowledge of the facts upon which alone a true conclusion can be 

 built. It demands atoms with different qualities, he tells us, while all material 

 atoms, if the foundation of mechanics on which we build is true, should be exact- 

 ly alike. But these may be evolved articles^ we answer. That they cannot be, he 

 says, because of their specific heats. Again, we answer that they may be saturat- 

 ed with energy. Who knows? (Such molecules as we demand for our theory of 

 gravity would completely upset such an objection). We cannot find out. Shall 

 we, therefore, cast aside this law and leave the myriads of facts it has been the 

 means of discovering in utter chaos ? False theories have aided prevision to 

 some extent, but only because of the elements of truth attached to them. 



