Page:Popular Science Monthly Volume 7.djvu/363

Rh as a whole, is a new and somewhat ambitious term which is striving to obtain a footing in science; and, as the Sun evidently plays one of the leading parts in it, we naturally ask what is his line of action and what he does. And our inquiries are advancing not only under the guidance of more extended views, but by the help of bold and patient research already resolutely carried out. Astronomers long concentrated (with great success) their talents within the limits of our solar system, ignoring the rest of the universe, as if it were necessarily excluded from the domain of positive knowledge. The first step taken out of those narrow bounds was Fourier's conception of the important influence of the temperature of interstellar space, due to the heat given out by the stars.

Fourier's notion has recently been amplified by the account which has been taken of the chemical radiations that reach us from the same source. On beholding tiny stars imprint their image on the photographer's sensitive plate in less time than the Moon herself, we cannot help believing that the actinic power of these myriads of distant strangers—outsiders to our system though they be—must exert some kind of influence upon our world.

Do not meteorites and shooting-stars put us in daily relation with cosmic materials, which reach us straight from the depths of space, or which have not formed part of our system for more than a few centuries? Moreover (and it is another view of the question), within our system itself we observe phenomena which we cannot attribute to the ordinary action of solar heat, and which, nevertheless, are evidently connected with the sun. From which we draw the obvious conclusion that the Sun has active powers of which we are ignorant; that the same is the case, perhaps, with the planets themselves; in short, that we have yet to investigate a multitude of relations between the earth and other heavenly bodies, of whatever kind. We naturally hope to prove the mutual influence of the stars, more particularly in respect to terrestrial magnetism and the electricity of our globe—as a striking instance of which may be cited M. Becquerel's happy hypothesis of the solar origin of atmospherical electricity. The only fear is, lest, once embarked in this line of speculation, we should be tempted to carry it too far.

There is less danger of error in studying certain actions of the sun which, though still mysterious, are constant and undeniable. By fixing our attention on the sun himself, the source of all energy here below, we run less risk of being led astray. For example: do we find, in known solar phenomena, any reason to believe that the Sun has other means of action besides his attraction, his heat, and his light? The answer, "Yes," is ready. The Sun possesses and exercises a plainly-marked repulsive power, of which meteorology has hitherto taken no account, although our atmosphere must experience its effects. Of the existence of this special force no doubt is entertained by astronomers