20 Prof. S. P. Thompson on the Conservation of Electricity , 



as affording an intelligible explanation of universal gravita- 

 tion — an explanation which would be no less tenable were it 

 supposed that actual ultimate atoms of matter are impenetrable 

 to electricity. 



It would appear, also, that electricity thus uniformly dis- 

 tributed through the universe would exercise a definite pres- 

 sure throughout space, such as has been attributed to the 

 aether by Mr. Tolver Preston for the explanation of cohesion, 

 and by Mr. J. MacFarlane Gray for the explanation of certain 

 phenomena of thermodynamics. Doubtless, also, the alleged 

 aether is subject to a law of conservation, since we have no 

 evidence that we can create or annihilate it, either directly 

 or by transformation of it into any other physical quantity. 



There appears, therefore, no reason why the right name 

 should not be given to this supposed medium, which, in order 

 to avoid confusion with existing terms, might be called the 

 Electricity of Space. 



Electricity, then, fills all space. Its inequalities of dis- 

 tribution, where electro-kinetic forces have done work upon 

 it, result in placing more of it at certain points and less at 

 others, or, in other words ; in giving it a + and a — distribu- 

 tion. Its flow resembles that of an incompressible fluid, 

 being accompanied by relative motions along stream-lines, 

 with their respective pressures and tensions between the 

 various parts. Its centrifugal force gives rise to the rotatory 

 phenomena of electromagnetism and of magneto-optics. Its 

 vibrations are radiant light and heat. Just as the air can 

 take up the vibrations of a distant tuning-fork, and can convey 

 them in waves to a near one and set it in motion if tuned to 

 the right note, so the electricity of space can take up the 

 vibrations of a molecule of sodium in a distant star, and can 

 convey it in waves to a molecule of sodium in our laboratories 

 and cause it to vibrate — the energy of the waves in the inter- 

 vening space being alternately electro-kinetic and electro- 

 potential in form. The so-called actinic rays are but vibrations 

 of a higher frequency in the electricity of space. 



8. We have here an explanation that is, at any rate, pro- 

 bable of the action of actinic rays in bringing about chemical 

 reactions, especially those which, like photographic reactions, 

 consist in the splitting asunder of chemically-compound mole- 

 cules, and in producing gradual reduction to a simple state. 

 Where the vibrations impinge upon the surface of the sensi- 

 tive film, the waves penetrate at least a little way into the 

 film, and for at least a short depth it is exposed to the alter- 

 nating displacements of the electricity of space, and is there- 

 fore under the same conditions as if transient and verv 



