Page:Popular Science Monthly Volume 78.djvu/586

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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 corpuscular (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 molecular 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,[1] 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 further 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 emanating 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 80 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

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