The force by which bodies in air press towards the centre of the earth; and the measured quantity of that force, in any body, is the weight of it. The earliest attempt on record to define measure of capacity and weight, by referring them to some natural standard, was made in the 51st year of the reign of Henry III., a.d. 1266; it is as follows:thirty-two wheat corns in the midst of the ear, and twenty pence to make an ounce, and twelve ounces one pound, and eight pounds do make a gallon of wine • and eight gallons of wine do make a London bushel, which is the eighth part of a quarter." These weights and measures were again precisely specified and confirmed in the reign of Henry VII., in the year 1496. The first statute that directs the use of the avoirdupois weight is the twenty fourth of Henry VIII., wherein it is directed to be used for weighing butchers' meat in the market, though it has been used for weighing all kinds of coarse bulky articles of ordinary consumption. This pound contains 7000 troy grains; while the troy pound contains only 5760 grains.

The difference between the troy and avoirdupois weight may be more exactly determined by reference to the annexed tables.

"An English penny, called a sterling, round and without clipping, shall weigh

Troy Weight.

 Cubic inches of water. 1/1252458 of a cubic inch of water = 1 grain = .0039610571428 24 grains = 1 pennyweight = •0950653714285 20 pennyweights = 1 ounce = 1.901307428571 12 ounces = 1 pound = 22.815689142857

A cubic inch of distilled water, at the maximum density weighs 253 troy grains.

Avoirdupois Weight.

 Cubic inches of water. 27 11/32 grains = 1 dram = .10831015625 16 drams = 1 ounce = 1.7329625 16 ounces = 1 pound = 27.7274 28 pounds = 1 quarter cwt. = 776.3672 4 quarters = 1 cwt. = 3105.4688 20 cwt = 1 ton = 6210.93760
 175 troy pounds = 144 avoirdupois pounds. 175 troy ounces = 192 avoirdupois ounces.

By an act of parliament made in the fifth year of his late majesty George IV., it was enacted that there should be adopted on, and after the 1st of May, 1825, throughout the United Kingdom, a uniformity of weights and measures. The following is, according to Mr. Gutteridge, the rationale of the improvement introduced by this act. "Take a pendulum which vibrates seconds in London, on a level with the sea, in a vacuum; divide all that part thereof which lies between the axis of suspension, and the centre of oscillation, into 391393 equal parts; then will ten thousand of those be an imperial inch, twelve whereof make a foot, and thirty-six a yard. Take a cube of one such inch of distilled water, at 62° of temperature, by Fahrenheit's thermometer; let this be weighed by any weight, and let such weight be divided into 252458 equal parts, then will one thousand of such parts be a troy grain; and 7000 of these grains will be a pound avoirdupois, the operation having been performed in air. Ten pounds, such as those mentioned of distilled water, at 62° of temperature, will be a gallon, which gallon will contain 277 cubic inches, and 274 one thousandth parts of another cubic inch." By the authority aforesaid it is also enacted, "that a cubic inch of distilled water in a vacuum, weighed by brass weights, also in a vacuum, at the temperature of 62° of Fahrenheit's thermometer, shall weigh 252.724grains:" and, "that the standard measure of capacity, as well for liquids as for dry goods not measured with heaped measure, shall be the gallon containing ten pounds avoirdupois weight, of distilled water weighed in air, at the temperature of 62°, the barometer being thirty inches." This gallon, therefore, containing 277.274 cubic inches, is about one-fifth greater than the old wine gallon, one thirty-second greater than the old dry gallon, and one-sixtieth less than the old beer gallon.

Eight such imperial gallons to be a bushel, eight such bushels to be a quarter of corn or other dry goods; the quart to be one-fourth, and the pint one-eighth of the above gallon, and none of these measures to he heaped up. The said standard bushel, which will therefore contain eighty pounds, avoirdupois, of water, is required to be a cylinder with a plain and even bottom, the extreme diameter of which is nineteen and a half inches. No other bushel than this is to be employed for coals, or other commodities usually sold by heaped measure.