Modified Theory of Gravitation. 97 



involved a continual expenditure of energy for the main- 

 tenance of gravitational attraction, the conservation of energy 

 in such cases being " apparent only/' The present theory is 

 equally open to this criticism ; but the objection is a meta- 

 physical rather than a physical one, and in view of recent 

 developments it has hardly the force which it might have 

 appeared to have some forty years ago. We have become 

 accustomed to the idea that our rapid motion through a 

 medium of enormous density not only fails to provide us 

 with a useful source of energy, but defies the most refined 

 attempts to detect it by means of terrestrial observations. 



And there is nothing more inherently improbable in the 

 notion that our universe may be traversed by waves of 

 enormous energy, perceptible to us only by means of a 

 minute secondary effect — gravitation. That we should be 

 unable, even in our dealings with this feeble residual pheno- 

 menon, to extract with continual profit the minutest portion 

 of the energy so abundantly propagated, is a view which 

 may appear to us somewhat ironical, but which is not out of 

 harmony with the trend of modern physical conceptions. 



45. Whatever may be the difficulties of the theory, this 

 attempt to contribute something towards the explanation of 

 gravitation has appeared to me sufficiently suggestive to be 

 worth publication ; the more so as incidentally certain 

 questions are raised, some of which, it may be hoped,, are 

 capable of being decided by experiment. 



Appendix A. 



Electromagnetic Phenomena which might conceivably arise 

 from Gravitation. 



46. Since in this paper gravitation is regarded as a 

 secondary or residual effect, due to the influence of atomic 

 matter on the propagation of compressional a3therial wave, 

 it might have seemed more logical to discuss the electro- 

 magnetic phenomena possibly produced by such waves, before 

 considering effects of a like character which might be 

 supposed to arise from gravitational attraction. In the first 

 place, how T ever, gravitation is known to exist, and in the 

 second place, the effects to be considered, being statical, 

 are comparatively simple. Accordingly gravitation may be 

 dealt with first in this connexion. 



47. Independently of any theory as to the cause of gravi- 

 tation, if we suppose that ordinary matter is made up of 

 electrons, then it seems reasonable to conclude that any 

 influence exerted on matter can be analysed into influences 



Phil Mag. S. 6. Vol. 17. No. 97. Jan. 1909, H 



