which was used as the weight unit in preference to the grain of wheat in some parts of the Roman empire. Furthermore this relation between barley-corns and wheat-corns can be proved to be a fact of Nature. In September, 1887, I placed in the opposite scales of a balance 32 grains of wheat “dry and taken from the midst of the ear,” and 24 grains of barley taken from ricks of corn grown in the same field at Fen Ditton, near Cambridge, and I thrice repeated the experiment; each time they balanced so evenly that a half grain weight turned the scale. The grain of Scotch wheat weighs ·047 gram, the Troy grain = ·064, ·047 × 4 = 188, ·064 × 3 = 192. Practically 4 wheat grains = 3 Troy grains.
Before passing from the Greek and Roman standards I may add that even higher denominations than the siliqua were expressed by the seeds of plants. The Romans made the lupin (lupinus) = 2 siliquae and under its Greek name of thermos (θερμός), it was assigned a like value (Metrol. Script. I. 81). In the Carmen de Ponderibus (Metrol. Script. II. 16), 6 grains of pulse (grana lentis) are made equal to 6 siliquae, and a like number of grains of spelt are given a similar value.