But what are seven miles--what are even ten miles--compared with the four or five hundred miles of atmosphere-depth? With all our utmost efforts, we and the birds still find ourselves only able to creep and flutter on or near the floor of the ocean of air. What earth would be without her surrounding ocean of air, we can scarcely imagine. The atmosphere plays so extraordinary and essential a part in all around, that to picture its entire absence is not easy. We see faintly on the moon something of what an airless world must be. Yet since we only “see” from a distance of two hundred and forty thousand miles, that does not mean much. Imagination has to come in, and imagination is apt to play us curious tricks when running after affairs which lie outside the range of human experience. Without air, man and beast can not breathe. Without air, plants and trees can not grow. Without air, life as we know it--the lower animal life common to man and beast--is a thing impossible. Without air, our world would be, as we suppose the moon to be, a world of lifelessness. Air is earth’s outer robe, “for use and for beauty”--for use in modes uncountable; for beauty, not so much in itself as in the softening, the diffusing, the controlling effects of its presence. Air is a mighty ocean, in which all things living must dwell. Even the living things of the sea are not exceptions to this rule, for water itself is pervaded by air. A man, going into and under water, does not get beyond the touch of air; only, not being provided, like fishes, with breathing gills, he can not make use of what is there--he can not separate the air from the water, and so keep himself alive by breathing it. Some animals living in the water-ocean are as dependent upon the air-ocean as man himself for “the breath of life.” Whales are a remarkable example of this. They are not fishes, though often mistakenly called so, but belong to the same “family” of creatures as men and land-quadrupeds generally. A whale is warm-blooded, has no gills, and breathes atmospheric air, coming to the surface for it. A whale kept forcibly for a long while under water would be drowned exactly as a man would be. If a whale is thrown upon the shore, it does not die of suffocation, but of inanition. A fish’s gills are no more fitted to breathe air in bulk than a man’s lungs are fitted to breathe air diffused in minute particles through water. The fish out of water is suffocated by getting air too rapidly: the man under water by exactly the reverse. A whale breathes like a man, and on land it simply starves fast from lack of the incessant food required by such a huge carcass.