from it a portion of these salts for their own purposes, and so make it light enough to flow off on the surface instead of the bottom—it then goes polarward, dispensing warmth and moisture as it goes; and so climate may be influenced. Moreover, if the sea were not salt, there would be no coral islands to beautify its landscapes and give variety to its features; sea-shells and marine insects could not operate upon the specific gravity of its waters, nor assist in giving diversity to its climates; neither could evaporation give dynamical force to its circulation; its waters, ceasing to contract as their temperature falls below 39°, would give but little impulse to its currents, and impart no motion (§ 404) to its waters in the depths below: thus its circulation would be torpid, and its bosom lack animation. In some other parts of the ocean, instead of there being organic life capable of changing, by animal or vegetable secretions, the specific gravity of the supposed salt and heavy and hot water at 90°, there may be none such, as in a "Desolate Region." This water then may go off as an under-current freighted with heat to temper some hyperborean region or to soften some extra-tropical climate, for we know that such is among the effects of marine currents. At starting, it might have been, if you please, so loaded with solid matter that, though its temperature were 90°, yet, by reason of the quantity of such matter held in solution, its specific gravity might have been greater even than that of extra-tropical sea water generally at 28°. Notwithstanding this, after travelling below to certain latitudes, it may be brought into contact by the way, with those kinds and quantities of marine organisms that shall abstract solid matter enough to reduce its specific gravity, and, instead of leaving it greater than common sea water at 28°, make it less than common sea water at 40°; consequently, in such a case, this warm sea water, when it comes to the cold latitudes, would be brought to the surface through the instrumentality of shell-fish, and various other tribes that dwell far down in the depths of the ocean. Thus we perceive that these creatures, though they are regarded as beings so low in the scale of creation, may nevertheless be regarded as agents of much importance in the terrestrial economy; for we now comprehend how they are capable of spreading over certain parts of the ocean those benign mantles of warmth which temper the winds, and modify, more or less, all the marine climates of the earth.
489. The regulators of the sea.—The makers of nice astronomical
