256 Prof. J. J. Thomson on the Emission of 



scatter light; and the scattered light will be polarized in the 

 same way as if the light had been reflected from small 

 particles. Since the corpuscles are in rapid motion if the 

 incident light is homogeneous, the spectrum of the scattered 

 light will by Dopler's principle broaden out into a band. 

 Similarly, if the corpuscles were illuminated by light showing 

 Frauenhofer's dark lines, these will be obliterated in the 

 scattered light. 



The most conspicuous example of a hot body is the sun, the 

 photosphere of which is supposed to contain large quantities of 

 carbon or silicon at a temperature far higher than any we can 

 produce by artificial means. Thus the photosphere must be 

 emitting corpuscles in large quantities, these coming from 

 such hot bodies will be moving with great velocities, and may 

 leave the sun and travel out through the solar system. These 

 corpuscles will scatter the light from the sun ; and since the 

 corpuscles are densest close to the sun, we should get a distri- 

 bution of luminosity due to the scattered light which would 

 be most intense close to the sun, and would fade away at 

 greater distances from it. The rate of decay would be fairly 

 rapid ; for not only would the intensity of the incident light 

 diminish inversely as the square of the distance, the number of 

 corpuscles per unit volume would also diminish according to 

 the same law ; so that the intensity of the light scattered from 

 the corpuscles would vary inversely as the fourth power of 

 the distance. It seeihs to me probable that many of the 

 phenomena of the corona may be due to light scattered by 

 corpuscles ejected from the sun. Since cathode-rays produce 

 luminosity when they pass through rarefied gas, the corpuscles 

 ejected from the photosphere would in their passage through 

 the chromosphere cause the gases in the latter to become 

 luminous. The presence of some of the corpuscles throughout 

 the solar system would cause each part of this system to 

 scatter a certain amount of light, so that no part of it would 

 be absolutely dark, nor would it be perfectly transparent. 

 I am not aware of the existence of any observations bearing 

 on the absorption of light by interplanetary space. 



The corpuscles when under the action of a wave or pulse of 

 electric and magnetic force will be pushed forward in the 

 direction in which the wave is travelling ; and thus if these 

 waves proceed from the sun, the latter will appear to repel 

 the corpuscles. 



To show this, let the direction of propagation of the wave 

 be along the axis of z, let X the electric force in the wave- 

 front be parallel to the axis of #, H the magnetic force 

 parallel to y. Let x, y, z be the coordinates of the corpuscle. 



