301. The rivers of India, and the measure of the effective evaporation from that ocean.—The rivers of India are fed by the monsoons, which have to do their work of distributing their moisture in about three months. Thus we obtain 0.065 inch as the average daily rate of effective (§ 282) evaporation from the warm waters of this ocean. If it were all rained down upon India, it would give it a drainage which would require rivers having sixteen times the capacity of the Mississippi to discharge. Nevertheless, the evaporation from the North Indian Ocean required for such a flood is only one-sixteenth of an inch daily throughout the year.[1] Availing myself of the best lights—dim at best—as to the total amount of evaporation that annually takes place in the trade-wind region generally at sea, I estimate that it does not exceed four feet.
302. Physical adjustments.—We see the light breaking in upon us, for we now begin to perceive why it is that the proportions between the land and water were made as we find them in nature. If there had been more water and less land, we should have had more rain, and vice versa; and then climates would have been different from what they are now, and the inhabitants, neither animal nor vegetable, would not have been as they are. And as they are, that wise Being who, kind providence, so watches over and regards the things of this world that he takes note of the sparrow's fall, and numbers the very hairs of our head, doubtless designed them to be. The mind is delighted, and the imagination charmed, by contemplating the physical arrangements of the earth from such points of view as this is which we now have before us; from it the sea, and the air, and the land, appear each as a part of that grand machinery upon which the well-being of all the inhabitants of earth, sea, and
- ↑ In his annual report of the Society {Transactions of the Bombay Geographical Society from May, 1849, to August, 1850, vol. ix.), the late Dr. Buist, the secretary, stated, on the authority of Mr. Laidly, the evaporation at Calcutta to be "about fifteen feet annually; that between the Cape and Calcutta it averages, in October and November, nearly three-fourths of an inch daily; between 10° and 20° in the Bay of Bengal, it was found to exceed an inch daily. Supposing this to be double the average throughout the year, we should," continues the doctor, "have eighteen feet of evaporation annually." All the heat received by the intertropical seas from the sun annually would not be sufficient to convert into vapour a layer of water from them sixteen feet deep. It is these observations as to the rate of evaporation on shore that have led (§ 280) to such extravagant estimates as to the rate at sea.
