The result of all this is that anyone who lives in a village knows how many ‘acres’ its fields contain. He has not to measure anything; he has only to count strips, for he is not likely to confuse ‘acres’ with ‘half-acres’ and that is the only mistake that he could make.
Irregular length of acres.
If a shot had a curved boundary, little or no pains seem to have been taken to equalize the strips that lay within it by making additional width serve as a compensation for deficient length. The width of the so-called acre remained approximately constant while its length varied. Thus, to take an example from the map of Heyford, we see a shot which is bounded on the one side by a straight line and on the other by a curving road. At one end of it the acre contains 2 R. 8 P.; this increases to 2 R. 30 P.; then slowly decreases until it has fallen as low as 1 R. 36 P., and then again rises to 2 R. 2 P. When they were dividing the field, men attempted to map out shots in which approximately equal areas could be constructed; but, when a shot was once delimited, then all the acres in it were made equally broad, while their length could not but vary, except in the rare case in which the shot was a true rectangle[1295].
The selions or beds.
It is probable that the whole system was made yet more visible by the practice of ploughing the land into ‘beds’ or ridges, which has but recently fallen out of use. In our Latin documents these ridges appear as selions (seliones). In English they were called ‘lands,’ for the French sillon struck no root in our language. Anyone who has walked through English grass fields will know what they looked like, for they triumph over time and change[1296]. Now it would seem that a fairly common usage made four selions in each acre[1297]; in other words, each acre-strip was divided longitudinally into four waves, so that the distance from crest to crest or trough to trough was a perch in length. Where this usage obtained, you could tell how many acres a shot or field contained by merely observing the undulations of the surface. Even if, as was often the case, the number of selions in the acre was not four, still the number that went to an acre of a given shot would be known, and a man might argue that a strip was an acre because in crossing it he traversed three or six terrestrial waves[1298].
Acres divided lengthwise.
If we look at old maps, we soon see that when an acre was divided, it was always divided by a line that was parallel, not to its short ends, but to its long sides. No one would think of dividing it in any other fashion. Suppose that you bisected it by bisecting its long sides, you would force each owner of a half-acre to turn his plough as often as if he had a whole acre. Besides, you would have uneconomical furrows; the oxen would be stopped before they had traversed what was regarded as the natural distance for beasts to go. Divide your acre into two long strips, then your folk and beasts can plough in the good old way. Hence it follows that when men think of dividing an acre they speak only of its breadth. Hence it follows that the quarter of an acre is a ‘rood’ or ‘yard[1299]’ or virga or virgata of land. Its width is a rod or land-yard, and its length—but there is no need to speak of its length[1300].
The virgate.
How then does it happen that these terms ‘virgate’ and ‘yard of land,’ though given to a quarter of an acre, are yet more commonly given to a much larger quantity containing 30 acres or thereabouts? The explanation is simple. The typical tenement is a hide. If you give a man a quarter of a hide (an equitable quarter, equal in value as well as extent to every remaining quarter) you do this by giving him a quarter of every acre in the hide. You give him a rood, a yard, a virga[1301], a virgata in every acre, and therefore a rood, a yard, a virga, a virgata of a typical tenement[1302].
The double meaning of a yard.