Note:  Do not rely on this information. It is very old.

Troy Weight

Troy Weight may have taken its name from Troyes, where a celebrated fair was held, it being customary for many towns to have special weights, some of which became standards in large districts. It was probably brought into England from France in the time of the Black Prince. The name may, howeer, have been derived from Troynovant, the monks' name for London. There was, however, a pound of twelve ounces in use from very early times - long before the name troy was applied to it - but there were also other pounds, e.g. the merchant's pound (probably giving rise to the avoirdupois weight), and the Tower pound. The troy pound is mentioned in the reigns of Henry V. and Henry VI., in the years 1414 and 1423. In 1495 Henry VII. determined to standardise the pound troy, and caused copies of it to be given to knights, burgesses of boroughs, and other important men, "to be by them conveyed to certain cities, etc., appointed for the safe custody of the same" (Ruding's Coinage of Great Britain, vol. i. p. 295). But in the next year these weights were found to be wrong, and it was then ordained that every pound should contain twelve ounces of troy weight, and every ounce twenty sterlings, and every sterling be of the weight of thirty-two corns of wheat that grew in the midst of the ear of wheat, according the old laws of the land (op. cit., i. 295, from statute in the twelfth year of Henry VII.). It was customary for people to take bullion to the mints - of which there were several in olden times - and have it coined on payment of a certain fee, and in these cases either the troy or Tower pound was used. But in a proclamation given on November 5th, in the eighteenth year of Henry VIII., it was ordered that the pound Tower should be no more used, but that all gold and silver should be weighed by the pound troy, "being of twelve ounces, and heavier than the Tower pound by three-quarters of an ounce (op. cit., p. 305). A fee of two shillings and ninepence was paid for the coining of every pound troy of gold. Before the Conquest we find that the weight of a penny was to be thirty-two corns of wheat., and also that this is the same actual weight as the twenty-four grains troy mentioned in 1280 (Edward I.). The troy grain is, therefore, not the weight of a grain of wheat, but it is found to be the weight of a corn of barley, three grains of barley being equal in weight to four grains of wheat. The troy ounce was raised from the 432 grains troy of the Romans to 480 by the apothecaries, who found that the latter number of grains more easily lent themselves to division into drachms and scruples. The pound troy is divided for precious metals into twelve ounces; each ounce contains twenty pennyweights, each pennyweight twenty-four grains; but for drugs the ounce is divided into eight drachms, each drachm into three scruples, and each scruple into twenty grains. The troy pound and ounce are, however, little used now for medicines, drugs being bought by avoirdupois weight, and only prescriptions being made up by apothecaries' weight. The troy pound contains, as we see, 5,760 grains, while the avoirdupois pound contains 7,000. The use of the pennyweight and grain is gradually dying out, dealers in precious metals having largely adopted the decimal division of the ounce.