576 TEE POPULAR SCIENCE MONTHLY 



movement of electrons which absorb light is quite independent of 

 temperature, thus confirming the theory that heat does not affect the 

 corpuscle as it does the atom, and that therefore space, if it were cor- 

 puscular (sub-atomic) in composition, could not possess temperature. 



Assuming that Poynting's calculation of the temperature of space 

 is right, or even adopting that of 1.5° Centigrade absolute, as was 

 more recently calculated by Schaeberle, we shall either have to accept a 

 material theory of the ether, like Mendeleef 's, or else suppose that molec- 

 ular dusts — solid, liquid or more likely gaseous — are present in space, 

 as material impurities in a sub-material medium. Such a supposition, 

 recently made by the author, 2 is not only possible, but is highly probable. 

 If, as is far from unlikely, this dust is found here and there in masses 

 more dense through which our planet glides, we do not have any fur- 

 ther to seek for another explanation of the aurora borealis and kindred 

 phenomena, which would be caused by the electrification of this dust 

 when near the earth. These auroras occur at irregular times, whereas 

 the theory of Arrhenius, which attributes them to cathodic rays emanat- 

 ing from the sun, would lead us to expect a continuous or periodic 

 performance. By adopting Villard's theory of the telluric origin of the 

 cathodic radiations of the phenomenon, we can introduce the cosmic 

 dust as a rarefied gas in which it is displayed. Zodiacal light will be 

 due to dusts burning when contacting with our atmosphere, just as on 

 a large scale and detachedly, meteorites will illuminate the sky. Night 

 brightness, as for instance the " extraordinary lightness of whole nights 

 in the year 1831, during which small print might be read in the latitude 

 of Italy and the north of Germany," mentioned by von Humboldt, 

 might have been due to a very dusty condition of space following solar 

 activity. Abney has claimed that the region of space which we are 

 traversing contains benzene vapor, ethyl hydride and other alcohol 

 derivatives; these would assuredly burn when in frictional contact with 

 the atmosphere. The more recent suggestion of a permanent corona 

 around the earth which becomes visible under certain conditions as sky 

 lightning does not stand analysis, but such a corona will exist as the 

 earth passes through dusty regions in space. 



If the sun, out of those vast cavities in the photosphere which are 

 called sun-spots, belches forth this cosmic dust, undoubtedly gaseous 

 in at least its early constitution, and the earth gravitates through it, 

 the electro-meteorological disturbances which are observed one week or 

 so after the appearance of spots would be, in a general way, fairly well 

 accounted for. It is significant that the growth of the red flames which 

 has been estimated about 200 miles a second corresponds to a period 

 of about six days to bridge the distance between the sun and the earth's 

 orbit. It is to be expected that this planet be influenced by a material 



2 Science, Nov. 20, 1908, p. 728. 



