It has many divisors, all multiplying into the required sum of 4840 square yards. Thus, it is clear that a length of 4840 yards, with a breadth of one yard, is quite as much an acre as a length of 220 yards with a breadth of 22 (in other words, ten chains by one, or 22 × 10 × 22,) the usual and legal computation: that is to say, twenty-two strips of land each 220 yards long and one wide, if placed together in any position will make up an acre. Placed side by side they will make an oblong acre whose length and breadth are as 10:1. A space rather more than sixty-nine and less than seventy yards in each side would be a square acre; it is however not probable that the land generally allowed of square divisions, but rather that the portions were oblong, a circumstance in favour of the ploughman, whose labour varies very much with the length of the furrow. The present divisors of the acre are 5·5 and 40; combinations of these numbers make up the parts not only of the acre or square measure, but also the measure of length. Thus 5·5 × 40 = 220, which taken in yards are one furlong, and which with one yard’s breadth are 1⁄22 of an acre. Again, forty times 5·5 yards with a breadth of 5·5 yards (or 220 × 5·5) are 1210 yards square, ·25 of an acre: twice that, or forty times 5·5 with a breadth of eleven yards are ·5 acre: and twice that, or 220 × 20 (that is in modern surveying ten chains by one) = 4840 yards or the whole acre. The same thing may be expressed in another way: we may assume a square of 5·5 yards, which is called a rod, perch, or pole: forty of these make a rood, which is a furlong with a breadth of 5·5 yards; and four such roods, or a furlong with a breadth of twenty-two yards, are an acre of the oblong form described above, and which is still the normal or legal acre. My hypothesis goes on to assume that such, or nearly such, were the elements of the original calculation: in fact, that they were entirely so, with the substitution only of 5 for 5·5 as a factor. It remains to be asked why these numbers should be fixed upon? Probably from some notion of the mystical properties of the numbers themselves. Forty and eight are of continual recurrence in Anglosaxon tradition, and may be considered as their sacerdotal or mythical numbers: forty divided by eight gives a quotient of five; and these may have been the original factors, especially if, as there is every reason to believe, the first division of lands (whether here or on the continent matters not) took place under the authority and with the assistance of the heathen priesthood.