Page:Popular Science Monthly Volume 64.djvu/400

396. The pound sterling continued to be the legal standard until 1496, when it was superseded by the pound troy.

King Edward II., in 1324, provided by statute that the inch should have the length of 'three barley corns, round and dry, laid end to end.' Of these inches 12 were to make one foot, and 36 of them one yard. The length of a barley corn must have been known to be quite as variable as that of the royal arm. Yard sticks were indeed kept in the royal exchequer, but care in preservation seems to have been quite as unknown as methods of precision in construction.

By the middle of the eighteenth century the influence of such men as Sir Isaac Newton had produced a very perceptible effect on English civilization. The Royal Society of London, chartered in 1662 and including all the scientific leaders of the kingdom, recognized the chaotic condition of English weights and measures; and in 1742 a standard yard was constructed by one of its members, George Graham, who determined the ratio of its length to that of a pendulum beating seconds. This pendulum length he found to be 39.14 inches. It is most unfortunate that this length was not adopted as that of the yard, even if its value was not known with the utmost precision. Had the inch been defined as one fortieth part of this length, and the foot as ten inches, not only would the foot have been made to accord with the actual length of the average masculine foot, but a decimal division of it would have been established. The binary division of the yard would have been maintained, and its value would have been so nearly the same as that of the meter, afterward adopted as an international unit of length, that identification of the British and metric units would have been easy. But the people were not seeking ideals. Graham's yard was constructed for the Royal Society and there is no evidence of its adoption by the government. The official standard until 1824 was a brass rod made in 1570. It had been broken and mended so badly that the joint was described to be 'nearly as loose as that of a pair of tongs.' A copy of Graham's yard was made by Mr. Bird for a parliamentary committee in 1758 and another in 1760, but not adopted until 1824. This was known as the 'imperial standard yard.' At the same time a brass weight which had been in the custody of the House of Commons since 1758 was adopted as the 'imperial standard troy pound.' But the avoirdupois pound was also officially recognized, the difference between the two being that the troy pound was defined to be 5,760 grains and the avoirdupois pound 7,000 grains. The 'imperial standard gallon' was made the official standard of capacity for both liquid and dry measure. Under certain standard conditions of measurement this was defined to be the volume of 10 avoirdupois pounds of water, or 227.274 cubic inches. The wine gallon of 231 cubic inches had previously been the standard of capacity since 1706.