3 oo TEE POPULAR SCIENCE MONTHLY 



L' = 3.3 X (10) 10 stars of zero magnitude. 



Hence U = ^ X ^^ * - = 5.5 X (10) 7 X L. 



The average illumination in intergalactic space is very likely less than 

 one one-hundred-millionth of that of sunlight; but a majority of the 

 stars have less absorbent atmospheres than our sun, and as sunlight at 

 the earth's distance must be increased in the ratio 1 : 46,000 to give 

 the light emitted by the surface of the solar sphere, the average radiant 

 energy at stellar surfaces may be assumed as (10) 12 times the average 

 radiant energy in the star-lit ether. 



If V and L are the volume and average illumination of the ether, 

 V = the total volume of stellar material, and L' = the total light 

 from the combined surfaces of all of the stars, an instantaneous image 

 of the relation between the two bodies — ether and matter — that is to 

 say, a representation of the relation if there were an instantaneous 

 emission of light with an infinite velocity, would give 



VL : V'L'= (10) 12 X 1 : 1 X (10) 12 , 

 or equality. But if the element of time enters, and also the actual 

 velocity of light, the illumination at a given point in the ether will 

 increase with the time. Let the year be the unit of time. After one 

 billion years, supposing that the stellar radiation can have endured as 

 long as this, instead of unity for the ratio VL/V'L' as in the pre- 

 ceding equation, we shall have 



VL = V'L'X (10) 12 . 

 Considering the limiting surface of the ether to be, not an imaginary 

 circumscribing sphere, but the sum of the combined stellar surfaces 

 across which the sum total of stellar radiant energy is being constantly 

 transferred from matter to ether, the case stands about like this : 



Total Radiant Energy 

 Volume Radiation (Superficial) (Volumftriei 



12 



Stars = 1 Stars = (10) 12 Stars = (10) 



Ether=(10) 12 Ether = (10) 12 Ether =(10) 



24 



The large amount of the total radiant energy of the free ether, com- 

 pared with that of the stars may seem surprising, but it results from 

 the fact that the average illumination of the ether is due to the accu- 

 mulation of radiant energy from depths of space which are greater as 

 the ether is more transparent. Unless the radiant energy were ab- 

 sorbed, it could not do otherwise than accumulate. The accumulation 

 represents the combined radiation of an immense number of stars 

 whose average distance is to be measured in millions of light-years — 

 how many millions depends upon the time that the stellar radiation 

 remains in the ether before it is all absorbed. 



According to what precedes, the average ethereal energy can hardly 

 be less than the radiant energy from the stars within a range of a 

 million light-years, and may amount to many times this figure; and as 



