Raphael Semmes, Memoirs of Service Afloat During the War Between the States

[500] have no twilight to soften, and beautify the landscape; no clouds to shade us from the scorching heat, but the bald earth, as it revolved on its axis, would turn its tanned and weakened front to the full and unmitigated rays of the lord of day.

It affords the gas which vivifies, and warms our frames, and receives into itself that which has been polluted by use, and thrown off as noxious. It feeds the flame of life, exactly as it does that of the fire. It is in both cases consumed, and affords the food of consumption,—in both cases it becomes combined with charcoal, which requires it for combustion, and is removed by it, when this is over.

The first law of nature may be said to be vis inertia, and the atmosphere thus beautifully described, following this law, would be motionless, if there were not causes, outside of itself, to put it in motion. The atmosphere in motion is wind, with which the sailor has so much to do, and it behooves him to understand, not only the causes which produce it, but the laws which control it. ‘Whence cometh the wind, and whither goeth it?’ It comes from heat, and as the sun is the father of heat, he is the father of the winds. Let us suppose the earth, and atmosphere both to be created, but not yet the sun. The atmosphere, being of equal temperature throughout the earth, would be in equilibrium. It could not move in any direction, and there would not be the slightest breeze to fan the brow. Now let us suppose the sun to be called into existence, and to begin to dart forth his rays. If he heated the earth, and the atmosphere in all parts alike, whilst there would be a swelling of the atmosphere into greater bulk, there would still be no motion which we could call wind. But the earth being placed in an elliptical orbit, and made to revolve around the sun, with its axis inclined to the plane in which it revolves, now approaching, and now receding from the sun, and now having the sun in one hemisphere, and now in another, the atmosphere is not only heated differently, in different parts of the earth, but at different seasons of the year; and thus the winds are engendered.

Let us imagine this heating process to be going on for the first time. How we should be astonished? The atmosphere having hitherto had no motion, in our experience, we should