73 



University Studies. 



Vol. I. JULY, 1888. . No. i. 



I. — On the Transparency of the Ether. 



By' DeWITT B. BRACE. 



Whether light coming from the remotest members of the 

 visible universe has not been enfeebled to a greater extent 

 than the variation of distance would require, is still an open 

 question. If there be absorption at all, it must be exceed- 

 ingly small through spaces comparable with the dimensions 

 of the solar system, in order that the light of these distant 

 bodies may be perceived. 



It is proposed in the present paper to investigate the phe- 

 nomena which would occur if the energy were absorbed by 

 the ether itself through frictional forces or imperfect elastic- 

 ity. If absorption does take place, there must be a differen- 

 tial effect for varying wave-lengths, if the ether satisfies the 

 equations of motion of elastic bodies. Several arguments 

 have been advanced as proving that such an absorption 

 takes place, of which those of Cheseaux, Olbers, and Struve 

 are the most celebrated. Considerations on other grounds 

 would seem to suggest such a conclusion. Cheseaux and 

 Olbers, arguing from insufficient data as to stellar distri- 

 bution, have shown that if the number of stars is infinite 

 and distributed with anything like uniformity in space 

 there must be absorption of light, as otherwise the sky would 

 appear all over of a brightness approaching that of the sun, 



University Studies, Vol. I., No. i, July, 1888. I 



