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 Great[1]. The solidus (itself weighing 72 grains Troy or 1/72 of the Roman pound) was divided into 24 siliquae. The siliqua, or as the Greeks called it keration ([Greek: keration], 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 same holds of the Greek system, for the drachma is described as containing 18 kerata or keratia, whilst according to others "it contains three grammata, but the gramma contains two obols and the obol contains three kerata, and the keras contains four wheat grains[2]." From this we see that the keration or siliqua was further reduced to 4 sitaria, or grains of wheat, whilst from another ancient table of weights[3] we learn that the siliqua likewise equals 3 barley-corns (siliqua grana ordei iii). Hence it appears that 3 barley-corns = 4 wheat grains. Thus both Greek and Roman systems just like the English and Irish take as their smallest unit a grain of corn. This also throws important light on the origin of that mysterious thing, the Troy grain. We saw above (8 Edward I.) that at the time of its introduction into England that 24 grains Troy = 32 grains of wheat, that is the Troy grain stands to wheat grain as 3 : 4. But as we have just seen that the siliqua = 3 barley-corns, and also = 4 wheat-corns, it follows that 3 barley-corns = 4 wheat-corns. And as 3 Troy grains = 4 wheat-corns, it likewise follows that 3 Troy grains = 3 barley-corns, or in other words, the barley-corn and]
