Troy-weight

Troy-weight seems to have taken its name from a weight used at the fair of Troyes, an important centre of commerce during the middle ages. Like Cologne, Toulouse, and other towns, Troyes may have had its own special system of weights. A Troy pound (of what value is unknown) is first mentioned in Britain in 1414, long before which period the standard pound of 12 oz. as well as another pound of 12 oz. (the Tower pound) was in use. The term 'Troy' was first applied to the standard pound in 1495, but at the same time no change seems to have been made in its value, and it continued, as before, to be exclusively employed by the dealers in the precious metals, gems, and drugs. See POUND. The troy pound contains 12 oz., each ounce 20 pennyweights, and each pennyweight 24 grains; thus the pound contains 5760 grains, and is to the avoird. pound as 144 to 175; while the troy ounce is to the avoird. ounce as 192 to 175. (The apothecaries' oz. and lb. are now practically obsolete; drugs are bought and sold by avoirdupois, though compounded by apothecaries' weight.) The old English pound, to which the term Troy was afterwards applied, was doubtless the pound of silver; and the Tower pound of 12 oz. differed from it only by $\backslash frac\{3\}\{4\}$ths of an ounce.