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Page:Popular Science Monthly Volume 34.djvu/442

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expenditure of 2,500,000,000 pounds of energy. Assuming that an area of 100 miles square with a mean depth of one mile was thus in vibration at any one instant of time—which is not improbable, considering the known rate of transmission and the long duration of the earthquake—the amount of energy thus represented would be 25 ✕ 10·12 foot-pounds. This energy might be generated by the fall under the action of gravity of a cube of rock 1,000 feet on each edge, the mass of which would be 75,000,000 tons, through a vertical distance of 166 feet." Also, assuming certain magnitudes, "I find the energy of a cubic mile of the Charleston earthquake, taken near enough to the epicentrum to be disturbed as above assumed, to be equal to 24,000,000,000 foot-pounds. The speed of transmission of this disturbance has been pretty well determined by Newcomb and Sutton to be approximately three miles per second, so that a cubic mile would be distributed in one third of a second. To do this would require 130,000,000 horse-power. Assuming that an area about the epicentrum 100 miles square was thus disturbed, the energy would be that of 24 ✕ 10·13 foot-pounds, and the rate of its expenditure would be that of 1,300,000,000,000 horse-power."

Gems.—The diamond became generally employed as a finished gem in France during the first quarter of the fifteenth century. The art of cutting it has gradually improved and developed, until now, two million five hundred thousand carats of diamonds are annually cut in Amsterdam. The principal source of supply has shifted from India to Brazil, and now to South Africa, whose Cape diamonds at present furnish ninety-five per cent of European supply. The quality of these diamonds, according to Mr. Alfred Phillips, has been purposely underestimated by interested parties. It is true that colorless diamonds have been found in the smallest proportions in South Africa, but it is equally beyond dispute that large numbers of the whitest and most faultless diamonds are exported from the Cape, while the mass of the material is conspicuous, whether white or colored, for its brilliancy. The ruby is next highest in value, and after it comes the sapphire, which is only another colored ruby. Although the cheapest of the major gems, its loss, according to Mr. Phillips, would be, on account of its intrinsic value and unrivaled blue color, a greater misfortune to the art-goldsmith than that of either the ruby or the emerald. The emerald is one of the most beautiful, although the softest, of the precious gems, and is easily fusible with borax into a colorless glass. The true emerald occurs in crystals seldom over one inch in length. The so-called Oriental emerald of India is not an emerald, but a green ruby or sapphire. The exquisite tones peculiar to the minor gems, or those of lesser value, establish them as a separate category when compared with the magnificent or acknowledged gems. Among them the amethyst was worn in the middle ages as an amulet and preservative in battle, and was distinguished as a pious or episcopal gem, figuring wherever it was desirable to impart serious beauty or dignity to the property of the church. Then we have the chrysolites, the topazes of various hues, and the garnets. Oriental varieties of which ranked with gems of a higher order rather more than a century ago. The opal was held in the highest repute in ancient times, first for its beauty, and then because its own mythology constituted it a harbinger of love and good-will. It has lost in value in modern times, through the influence of a silly superstition. The selenite, or moonstone, is a gem of great beauty, and admits of a great variety of applications, on account of the softness of its tint, which enables colored gems, diamonds, and enamels to be agreeably associated with it.

About a Crocodile.—"Ubique" (Parker Gillmore) tells, in "Land and Water," of a crocodile which he saw in Java almost seventeen feet long. "It frequented the vicinity of a place where the village women were in the habit of assembling to wash their clothes, and, if report spoke truly, many were the Malay females it had carried off. At length it was captured by using a live dog for bait. After being transferred from its watery home to the commandant's garden, it was safely secured upon the lawn by innumerable moorings. Our assistant surgeon administered the saurian an immense dose of strychnine, enough, as he said, to poison a regiment, but it had not the slightest injuri-