The arpent de Paris was 100 of these square perches = 900 sq. toises = 0·844 acre.
The arpent commun is that of Quebec.
The arpent de Paris is that of Mauritius.
The acre de Normandie varies according to its perch, but it is always 160 sq. perches, and if these be standard it is equal to 2 acres. But the usual unit is the vergée or rood, of 40 perches = 1/2 acre.
It has been seen that the Jersey vergée is 40 perches of 22 reduced English feet square, the foot being 11 inches. This is an adaptation of a very general Normandy perch, 22 feet of 11 French inches. It is = 0·44 acre.
Local French land-measures varied considerably, from different standards of perch, from different lengths taken for the foot of the perch. But the size of the unit, Journal, Estrée, &c., &c., is very generally = 1400 to 1600 square perches or roughly about 1-1/2 acre. These measures, so irrational to the Parisian, are dear to the peasant’s heart; he understands them, and as people do not buy land as they would apples or eggs, no one is deceived.
The Estrée or Seterée (Setier seed-land) might be divided into 12 Boisselées (small-bushel lands).
Weight
The royal pound, livre poids de marc, the double-marc of Troyes, was one of several pounds current in Northern France. It was, like the royal foot, ascribed to Charlemagne, but his standard of weight, as known by his silver pennies, nearly always much above 24 grains, 1/20 of some ounce heavier than that of the Troyes marc, was probably altered later on. The royal pound, = 5570 grains, was raised for commercial purposes (about 1350) to 16 ounces = 7554·1 grains, the ounce = 472·13 grains.
The weight of the 12-ounce pound coincides very closely with that of the Bosphoric miná, 100 drachmæ of 56·66 grains; this is perhaps the origin of the story that it was sent to Charlemagne by Harūn al Rashid. Its ounce is also approximately the Tripoli ukyé of 10 dirhems × 470-3/4 grains, and nearer still to 471 grains, the weight of 10 of the dirhems of which 8 made the Provençal ounce.