259 



[Ch£ 



theoretically condemn. There is fully as much dogmatism in physics as 

 in metaphysics. Whenever it springs from a well-grounded conviction, 

 which has been once thoroughly tested and which always courts a repeti- 

 tion of tests, it is not only unobjectionable but it is highly commendable. 

 On the other hand when it is merely theoretical, or the outgrowth of in- 

 veterate prejudice, it has no rightful place in any discussion which claims 

 to be scientific. 



196. Numerical Tests. 

 There has been an immense amount of valuable mathematical analy- 

 sis which has been misunderstood, or but partially understood, for 

 want of being properly tested. Results are never valid except for 

 the data which they embody ; they are always subject to modifica- 

 tion by neglected, unknown or new data. The "opprobrium of ther- 

 modynamics" amounts to nothing more than the statement that, from 

 the data which have been discussed hitherto, there appears to be a 

 universal tendency to physical stagnation and death. The principle 

 of equal action and reaction ought to furnish some means of escape from 

 this opprobrium. The waj^ of escape seems to have been indicated by the 

 identification of a common operative velocity in light, electricity, chemis- 

 try and gravitation. A single theoretical result which has been quantita- 

 tively verified, is worth more than a thousand that are thought to be be- 

 yond the reach of verification. The theory of dependent connection be- 

 tween stellar rotary oscillations and the reaction of cosmical inertia against 

 sethereal influence (Note 163 et al.), having been verified by the test of our 

 Sun, seems likely to open the way for a general recognition of an aethereal 

 reaction which will yield an exact compensation for all physical actions, 

 affording a more satisfactory explanation of stellar light and heat than can 

 be drawn from meteoric or shrinkage hypotheses. 



197. Velocity of Gramtating Action. 



Objections have been urged against the possibility of making gravitation 

 the etfect of light undulations unless we first overthrow Laplace's conclu- 

 sion, that gravity must act with at least a hundred million times the velocity 

 of light and that its action may be regarded as instantaneous. I answer : — 

 1. I have never claimed that any physical phenomenon is the effect of an- 

 other physical phenomenon, but merely that the phenomena of light and 

 gravitation are so related as to show that they may be effects of a common 

 cause. 2. The rapidity of action and the rapidity with which the results 

 of the action are propagated are two entirely different things. 3. If the 

 results of gravitating and luminous actions and reactions are identified in 

 stellar rotations, it is altogether likely that the forces upon which these re- 

 sults depend act with equal speed. 4. Even if it should be found neces- 

 sary to propagate gravitating undulations with a hundred million times the 

 velocity of light, it would be as easy to suppose a gravitating aether, with 

 a ratio of elasticity to density which is (100,000,000)^ times that of the 



PROC. AMER. FHILOS. SOC. XX. Ill 2g. PRINTED MAY 19, 1882, 



