Note 19 — The Correlation of Vital and Physical Forces.
Reading edition
In this calculation the annual evaporation from the ocean is assumed to be about 9 feet. (See Dr. Buist, quoted in Maury’s Phys. Geography of the Sea, New York, 1861, p. 11.) Calling the water-area of our globe 150,000,000 square miles, the total evaporation in tons per minute, would be that here given. Inasmuch as 30,000 pounds raised one-foot high is a horse-power, the number of horse-powers necessary to raise this quantity of water 3½ miles in one minute is 2,757,000,000,000. This amount of energy is precisely that set free again when this water falls as rain.