The multiples of the pound were originally, like its divisions, in a sexdecimal series, with an alternative series to bring in the hundredweight, i.e. the true Cwt.
16 lb. 1 stone 16 stone 1 wey = 256 lb. 2 weys 1 quarter = 500 lb. approximately 8 „ 1 ton = 2000 lb. „ 16 „ 1 last = 4000 lb. „
The approximative relation of the quarter, strictly speaking of 512 lb., mattered but little, as it applied to corn-measure, in which the measured quarter, 8 bushels, varied from 500 lb. for wheat of 62-1/2 lb. to the bushel, to 512 lb. for heavy wheat of 64 lb. to the bushel. The arrangement was convenient for the corn-trade and could not give rise to fraud; and the main object of all laws on weights and measures should be to prevent fraud, especially in retail trade.
This convenient arrangement was altered in the times of Edward I and Edward III. The former King found the Cwt. of 100 lb. with a quarter of 25 lb. and a sixteenth = 6-1/4 lb. as its nail or clove. In his Acts there is mention of the 100 weight, the 1000 weight, the 2000 weight. But by the Ordinance of Measures 31 Edw. I, 1302, a distractingly obscure statute, no less than three different weights are ordered for the stone:
A London stone of 12-1/2 lb., one-eighth of the true Cwt.
A stone for groceries of 8 lb.; and 13-1/2 stone to make a Cwt. of 108 lb.
And the ‘fotmal’ of lead is to be 6 stones of 12 lb. but less 2 lb., ‘which are 70 lb. making 5 stones.’
Here then we see, besides a 12 lb. stone for lead,
(_a_) The true Cwt. of 100 lb. divided into quarters and nails.
(_b_) A transitional Cwt. of 108 lb. in 13-1/2 old half-stones of 8 lb.
(_c_) A new Cwt. of 112 lb. in 8 stones of 14 lb.
The Cwt. (centena) of 108 lb. seems to have been preparatory to the Cwt. of 112 lb. mentioned in this Ordinance (if it be not a later interpolation) and established later by Edward III. It preserved, for a time, the ancient half-stone of 8 lb., but by the inconvenient process of making 13-1/2 of these as the Cwt.; probably to prepare the merchant for a new Cwt. of 112 lb. first in 14 stones of 8 lb. and then in 8 stones of 14 lb.
This is the Cwt. which has come down from Edward III to the present day, against which trade has had to struggle more or less successfully ever since, and which torments the schoolboy with sums in tons, cwts., qrs. and lb.