When we pass to England, the very word grain which we employ to express our lowest weight unit, would of itself suggest that originally some kind of grain or seed was employed by our forefathers in weighing, but as the grain in use among us is the grain Troy, and as we have not yet learned its origin, it will not do to argue vaguely from etymology. But a little enquiry soon brings us to a time when the grain Troy did not as yet form the basis of English weights, and when a far simpler method of fixing the weight of the kings coinage was in vogue. It was ordained by 12 Henry VII. ch. V. “that the bushel is to contain eight gallons of wheat, and every gallon eight pounds of wheat, and every pound twelve ounces of Troy weight, and every ounce twenty sterlings, and every sterling to be of the weight of thirty-two grains of wheat that grew in the midst of the ear of wheat according to the old laws of this land11.” Going backwards we find that in 1280 (8 Edward I.) the penny was to weigh 24 grains, which by weight then appointed were as much as the former 32 grains of wheat. By the Statute De Ponderibus, of uncertain date but put by some in 1265, it was ordained that the penny sterling should weigh 32 grains of wheat, round and dry, and taken from the midst of the ear. Going back a step still further we find that by the Laws of Ethelred, every penny weighed 32 grains of wheat12, and as the pennies struck by King Alfred weigh 24 grains Troy, we may assume without hesitation that they were struck on the same standard of 32 grains of wheat. Thus from Alfred (871-901) down to Henry VII. (1485-1509), we find the penny fixed by this primitive method, and the actual weight of the coins, as tested by the balance at the present day, affords proof positive of the method.
But all the standards of mediaeval Europe (with the exception of the Irish) were based on the gold solidus of Constantine the Great13. The solidus (itself weighing 72 grains Troy or ⅟₇₂ of the Roman pound) was divided into 24 siliquae. The siliqua, or as the Greeks called it keration (κεράτιον, from which comes our word carat), was the seed of the carob, or as it is often called, St John’s Bread (Ceratonia siliqua L). Thus the lowest unit in the Roman system, as it is usually given, is found to be the seed of a plant. The