The same is true of all manner of nuts, fruits, and vegetables. It is even true of animals, for they are enclosed in such varied coverings that their nature is often quite concealed from us. We may as well believe there is something in earth’s interior, away from winds and cold, as precious over and above its crust as the chestnut is better than the burr that encloses it; the fruit better than its rind; or fish, birds, and animals better than their skins. Knowing this, man, while he would grasp the greatness of the universe, may somewhat under-rate the contents of his own earth. Dr. Winchell in speaking of cold has said; “It has been demonstrated that an ice-cap resting several thousand years over any considerable portion of the surface would so reduce the subjacent temperature of the earth that for many centuries after the disappearance of the ice, a decrease of temperature would be discovered in penetrating downward. Even centuries later, so much cold would still remain within the earth, that the rate of increase of temperature would be less than if the ice-cap had not existed; and after 3,600 years, that rate would be only half the normal rate.”[12] Now if the earth’s crust will thus retain the cold why may it not as well retain the heat? In that case any excess of heat escaping from earth, over and above the heat it constantly receives from the sun, may be readily accounted for. It is claimed that the earth has large quantities of sunlight and heat stored in a liquid state, as petroleum; in a gaseous state, as natural gas; and in a solidified form, as coal; some of which are found at a depth of 1600 or more feet, although coal is sometimes found near the surface, and even upon the mountains. If these are all stored sunlight, why do they not accumulate over earth’s entire surface as well as in certain localities,—especially in the torrid zone where great heat exists,—and accumulate to-day as well as in former ages?