Possibly because the sack thus corresponded nearly to the skippund (ship-pound) of the Baltic trade and of Scotland, a weight of 20 lispund each of 16 Norse Troy pounds or of 20 pounds of light standard = 352 to 375 lb. The Baltic skippund at the present day is about 350 lb.
In Scotland the sack of wool was ordered to be 24 stone, which was equivalent to 26 English stone, in proportion to the heavier weight of the Scots pound.
The Plantagenet domination in France caused the stone to pass there, though not always at English weight; and there being no regular weight in France between the pound and the quintal, local stones came into use. ‘Les laines vend on par sacs et par pois, par pierres, par claus et par livres,’ the French terms for the sack, the wey, the stone, the clove and the pound.[25] Sometimes the stone was called ‘gal’ (stone, _galet_, shingle) and the clove ‘demi-gal’ (Livre blanc de l’hotel de ville d’Abbeville). The French stone was of variable weight. One record gives the sack of wool (= 4 Montpellier light quintals) as of 25 pierres, which would make them 9 lb. each. Another record gives it as 36 stone of 9 standard pounds (= 10 English pounds).
See section on the Nail and the Clove, Chap. XX.
The stone appears to be extinct now in France; I find that as late as 1579 wool was sold in Burgundy by the wool-stone (_la pierre de laine_) = 12 French or about 13 English pounds.
While the old English wey or load was 16 × 16 = 256 lb., the wey ordered for wool was half a sack = 182 lb. It would seem that, once the King’s dues paid, the shipper was free to make up his sacks or sarplers of wool as most convenient to him. The customary wey or weigh (Sc. waugh or wall) seems to have been 32 cloves or nails of 7 lb. = 2 cwt. A ‘poke’ of wool ‘weand 4 C. 15 nallis,’ i.e. 4 cwt. and 105 lb. A sack might be ‘6 wall and 25 naill,’ i.e. 12 cwt. and 175 lb.
The wey or weigh became, in statute French, _poids_, _pois_; but the scribes took the wrong _pois_ and thinking it meant ‘pease’ made it _pisa_ in their Latin, just as they took the wrong ‘nail’ and made it L. _clavus_, and in French _clau_, through L. _clavis_, meaning a ‘key.’
While the fother is 17-2/3 cwt. for coal, it is 19-1/2 cwt. = 2184 lb. for lead. This peculiar unit, also called the char or load, is the consequence of a statute 31 Edw. I, perhaps the most confused and bewildering of the many confused medieval statutes on weights and measures, and one in which subsequent interpolations may be suspected. It ordered two stones, one of 12 lb. and another of 12-1/2 lb., and to keep up the pretence of there being no weight other than of Tower standard, it declared that a pound shall contain 25 shillings. This shilling standard may be put aside.