MEASURES OF WEIGHT Origin of use of weights depends upon the principle of balance. Hence they were proba bly not introduced until some time after measures of length, surface, and capacity. The first English statute on the subject founded measures of weight upon a given quantity of wheat corns. The language of the ancient statute is interesting and sug gestive.
" An English penny, called a ster ling, round and without any clipping, shall weigh 32 wheat corns in the midst of the ear, and 20 pence do make an ounce, and 12 ounces 1 pound, and 8 pounds do make a gal lon of wine, and 8 gallons of wine do make a London bushel, which is the eighth part of a quarter." The pound weight provided by this statute known 8,s the tower pound, or the easterling or sterling pound (whence our word sterling as applied to silverware and otherwise), con tinued in use until about the time of Columbus, when the pound troy was substituted in its place. By a later statute a brass 1-pound weight was established as the imperial standard troy pound. It was declared to con tain 12 ounces of 20 pennyweights, each pennyweight containing 21 grains, so that 5,760 such grains shall be a troy pound, and 7,000 such grains a pound avoirdupois. It was further provided that 1 cubic inch of water weighed by brass weights in air, at a temperature of 62° F., and 30 inches bavmetic pressure, is the equivalent of 252.458 grains. This standard be came quite generally adopted in the United States, and in 1836 the Secre tary of the Treasury caused a uni form set of weights to be delivered to the governor of each State for local use. Thus a pound is practically the same in all parts of the English speaking world. There is still, how ever, great confusion in comparisons between weight and capacity meas ures, and the legislation of different States and countries in defining the number of pounds in a bushel of va rious grains, fruits, and vegetables, differs widely.
Systems of Weight.— There are three principal systems of weights in general use: avoirdupois weight, the universal standard, except as to the weight of the precious metals, jewels, and drugs; troy weight used in coin age and by jewelers (who also make use of a standard unit in weighing jewels called the carat); and apothe caries' weight, used by druggists and physicians. Avoirdupois weight, so
called from the Norman Avon du paid:, " goods of weight," is derived from the imperial standard polmd above mentioned, equal to 700 troy grains. The grain is the same in both avoirdupois and troy weight. For merly the ton consisted of 2,240 pounds, and the hundredweight of 112 pounds, divided into four quar ters of 28 pounds each. And this practice continues in Great Britain and in the United States custom house. In the ordinary commerce of the United States, however, it has become customary, as a matter of convenience, to reckon 100 pounds to the hundredweight, and 2,000 pounds to the ton; and this practice has been legalized in, some of the States. By act of Congress, however, when not specified to the contrary, the ton is to be construed as meaning 2,240 pounds. This is commonly called the long ton; that of 2,000 pounds the short ton. The long ton is most often used for weighing coal and iron at the mines, and for plaster, and in some other wholesale transactions in mining products. The shipping ton is 40 cubic feet, known as actual ton nage. The registered shipping ton is 100 cubic feet. The word ton is sup Posed to have been derived from the tun, an old British liquid measure tor ale or beer. A tun of water weighs a little over 9,200 pounds. Hence the ton weight seems to have been taken from the tun measure, of which it is a rongh equivalent.
Avoirdupois Weight.—The follow ing are English and American avoir dupois tables: American 16 drams 1 ounce (oz.).
16 ounces 1 pound (lb.).
25 pounds 1 quarter (qr.).
4 quarters 1 hundred (cwt.).
20 hundred 1 ton (T.).