From the South of France to England and Scotland there is a concrete shape recognisable in the large unit of land-measure. The Provençal Saumado of 1600 square cano or toises, the Normandy acre of 160 square rods of 4 toises, the English acre of 160 square rods of 5-1/2 yards, the Scots acre of 160 square rods of 6 ells = 18·53 feet, are all connected by a common tradition of concrete form, and are all made up of four minor units: sesteirado, vergées, roods, &c. Looking back to the land-measures of Greece and Rome we find this same group of four lesser units in the tetragyon and heredium. The law may only recognise abstract superficial standards, but the peasant holds to the concrete units of form convenient for cultivation.
Notwithstanding Homer’s recommendation of mules as ‘better far than kine to drag the jointed plough,’ oxen are still used in the greater part of the world. In light soils one yoke of oxen is sufficient, but in heavy fallows, with deep-working ploughs, two, three or more yoke were used; and in feudal times it would appear that the four tenants of a hide or ploughland co-operated with their oxen. A furrow of 40 rods could thus be made easily in one breath, and as this length of a rood coincided approximately with the eighth of a mile, that division of the mile was also called a furrow-long or furlong. When ploughing up fallow-land the oxen, on getting to the end of the ‘shot,’ turned and took breath. The ploughman measured a rod-breadth from the first furrow by means of his goad, Scottice by the ‘fall’ of it, and this rod-breadth down which the oxen turned, the _tornatura_ of Italy, was a rood.
Sometimes between the roods a narrow unploughed strip, a balk of land, was left, marking the roods or ‘selions,’ four of which, side by side, made an acre, and forty of which made the square furlong, the ten-acre field.
Ploughing in roods, selions, square furlongs, is still far from extinct. In Brittany land is still reckoned by _seillons_ of so many furrows wide, or of so many _gaules_ or 12-foot rods. In Southern France fields are estimated in breadths of a _destre_, of the 12-foot rod corresponding roughly to the width cleared by a couple of mowers. In our Isle of Axholme, in North Lincolnshire, land is reckoned in selions of a rod wide and usually of a furlong in length; these selions or roods being grouped into furlongs, that is, actually or originally, into greater units of a square furlong = 40 roods or 10 acres.