the Luminiferous ^Ether. 403 



makes 590,000,000,000,000 (6 x 10 14 nearly) complete cycles 

 of movements every second, for a wave-length of ^-^- of an 

 inch ? The number of such complete movements in air for 

 the fundamental c is only 264 ; and hence the ratio of the 

 former to the latter of these numbers is nearly 2 x 10 12 . The 

 ratio of the specific heat given in (22) to that of hydrogen 

 is nearly l^x 10 12 , which is not so different from that just 

 given for the ratio of cyclical movements in a second of the 

 aether and air. The velocity of sound in air at 493° F. above 

 absolute zero is about 1090 feet per second ; but if the tem- 

 perature could be reduced to 20° F., absolute, the law being 

 extended so far, the velocity would be only 



V=109^/^=217feet; 



493 



but the velocity of light is 982,000,000 feet per second, a 

 number about 4^ million times the former, and near a 

 million of times that of the velocity in air under ordinary 

 conditions. The ratio of the mass of air in a cubic foot at sea- 

 level to that of a cubic foot of the aether as computed, far ex- 

 ceeds any of these ratios. The fact is, the known qualities of 

 the aether in transmitting light and heat so far transcend 

 those of any known terrestrial substance, that we might anti- 

 cipate the fact that, in regard to magnitude, all its properties 

 will be extremely exceptional when compared with such sub- 

 stances. We must accept substantially the number in equation 

 (22), or subject this medium to different laws than those of 

 gases. 



We may deduce this result by another process ; thus, since 

 the specific heats of different gases are as the squares of the 

 wave-velocities in the respective substances, the other elements 

 being the same, if the specific heat of air be 0*23, we should 

 have for the specific heat of the aether 



c=0- 28 (i5M™°)° = 46xlOU 



as before. The correct value of the specific heat of air, 0*2375, 

 would give over 47 x 10 11 , and nearly 48 x 10 11 ; but these 

 differences are quite immaterial in this connection, the object 

 being to check the former result, and find chiefly qualitative 

 values. 



On the other hand, in order that common air might be able 

 to transmit a wave of the known velocity of light, its specific 

 heat being taken constantly at 0*23, its temperature would be, 



