Page:Popular Science Monthly Volume 25.djvu/86

78 infinitesimal in comparison, is not here taken into the calculation. But, were it more considerable, it would not be important in this connection, for it falls upon all parts of the earth about equally.

It is evident, from the present condition of the earth's surface, that at the time it was a molten mass, and for a long time thereafter, it radiated heat into space much more rapidly than it received heat from the sun; but nevertheless the heat of the sun is, and always has been, offsetting the loss of heat from the earth by radiation to the full extent of the heat which the earth had been receiving from the sun during the time.

But this sun-heat, this offset to radiation, has not been received by all parts of the earth equally. The equatorial belt, or torrid zone, has always received the most per square foot, or in proportion to its area. The two intermediate or temperate zones have received the next largest amount per square foot, or in proportion to their area; while the polar or frigid zones have received the least per square foot, or in proportion to their area. If the amount of sun-heat received at the equator be rated at 1,000, then, upon the same basis, the average of sun-heat throughout the torrid zone should be rated at 975, the average sun-heat throughout the temperate zones at 757, and the average sun-heat throughout the frigid zones at 454, or less than one half that of the torrid and less than two thirds that of the temperate zones. We speak here, and shall hereafter, of the geographical zones of the earth for the sake of convenience.

The greatest amount of heat received from the sun and offsetting radiation from the earth, other things being equal, is, of course, as we have seen, at the equator, and less and less every degree north and south of this line to the poles. If, then, the frigid zones have been during all this time receiving the least heat from the sun—the least offset to their own loss of heat by radiation—does it not follow that they were the first parts of the earth sufficiently cooled to maintain vegetal and animal life? The inference seems inevitable.



HE title at the head of this article may appear to some a contradiction in terms. But it is not really so. And no religious man need shrink from saying: "I am a Christian agnostic. I hold firmly by the doctrine of St. Paul, who exclaims, in sheer despair of fathoming the unfathomable, 'O the depth of God! How unsearchable are his judgments, and inscrutable his ways!' I say, with Job and all the great prophets of the Old Testament, ’Canst thou by searching find 