the Luminiferous ^Ether. 397 



considering the sun as the only attracting body, we have g 

 at the sun 28'6 x 32% and at the earth z=2lQr, r== 441,000 

 miles, the sun's radius; S = ^x 10~" 24 , equation (9), and 

 e=^xlO~~ Q ; and these, in (14) and (15), give 



28-6x32-2x2x33xl0 6x 210 x52g0 



£ = € 4X35x1024 2L1 



1 



= eQ€ Tmm nearly, (16) 



8= V*^ nearly, (160 



for the tension and density of the aether at the surface of the 

 sun under the conditions imposed. But the millionth root of 

 e is practically unity ; hence the elasticity and density at the 

 sun is practically the same as at the earth. 



Now, starting at the sun with this result, and finding the 

 density at a distance z from it, then making z infinite, we shall 

 get the 995,000th root of e, the value of which is also sensibly 

 equal to unity; hence the density at infinity would be sensibly 

 the same as at the surface of the sun, the difference in the 

 densities at the sun and at infinity being less than 1 0Q * Q00 part 

 of that at the sun. In order to make the density vary sen- 

 sibly with the distance, the attraction of the central body must 

 be something like a million times as great as that of the sun, 

 or have a diameter a million times as large ; but there being 

 no such known body, therefore the density and tension of the 

 cether may be considered uniform throughout space. Such has 

 been our conception of it ; and it is an agreeable surprise to 

 find it so fully confirmed by analysis. 



If the density were uniform, the weight of a given volume 



of it would vary as the force of gravity. At the surface of the 



sun a cubic foot would weigh [equation (10) multiplied by 



28'6, or] 57 x 10~ 24 ; hence, for a height h it would weigh 



57 nk r 2 57 rh 



IP 24 Jo {r + z) 2 10 24 ' r + V t 17 ' 



13 

 which for A=co becomes y^ of a pound, which is the pressure 



upon a square foot of the sun of a column of infinite height 

 under the conditions imposed. This would compress the first 

 foot of the column about 1 000 000 of its length, and would cause 

 a corresponding increase in the density, the value of which, 

 after this compression, will be found by multiplying the value 

 given in equation (9) by 1 9 9 9 9 ^ ? which will leave the result 

 sensibly the same as before. Hence, from this standpoint, we 



