Lastly, we have still to explain the reason of the difference between the form of the Roman 'actus' and 'jugerum' and that of the early Bavarian and English acre.
The Egyptian arura was 100 cubits square.[598]
The Greek πλέθρον was 10 rods or 100 feet square.[599]
The Roman actus was 12 rods or 120 feet square.
The Roman 'jugerum' was made up of two 'actus' placed side by side, and was the area to be ploughed in a day.
Form of the acre or day's-work connected with the number of oxen in the team.
In all these cases the yoke of two oxen is assumed, and the length of the acre, or 'day-work,' is the length of the furrow which two oxen could properly plough at a stretch.[600]
The reason of the increased length of the Bavarian and the English acre was, no doubt, connected with the fact of the larger team.[601]
If the Bavarian team was of eight oxen, like that of the English and Welsh and Scotch common plough, it would seem perfectly natural that with four times the strength of team the furrow might also be assumed to be four times the usual length. In this way the Greek and Roman furrow of 10 or 12 rods may naturally have been extended north of the Alps into the 'furlong' of forty rods. [p388] . Now, there is a remarkable proof that long furrows, and therefore probably large teams, were used in Bavaria, then within the Roman province of Rhætia, as early as the second century. The remains of the Bavarian 'Hochäcker' are described as running uninterruptedly for sometimes a kilomètre and more, i.e. five times the length of the English furlong. And a Roman road with milestones, dating as early as A.D. 201, in one place runs across these long furrows in a way which seems to prove that they were older than the road.[602]
The Bavarian 'Hochäcker' and their long furrows.