In this day, when the Arabic numerals assert an influence quite as potent as that which the lictors’ rods obtained in ancient Rome, the inquiries may not be destitute of interest—What amount of labour was involved in the construction of the Barrier, in what time could it be accomplished, and what, at the present value of labour and materials, would be the cost of its construction? [Sidenote: MONEY VALUE OF THE BARRIER.] The Wall is sixty-eight miles long; granting that it was only sixteen feet high, but had a continuous thickness of eight feet, we have 1,702,115 cubic yards of masonry, to say nothing of stations, mile-castles, and turrets. Twelve shillings per cubic yard is as near as may be the present value of masonry, such as that of which the Roman Wall consists—the cost of this part of the structure would therefore be 1,021,269_l._ Taking into account that the labour was forced, each cubic yard of the Wall would, at the least, require, in quarrying the stone, its carriage to the Wall, its setting, and other operations, one entire day’s exertions of one man. In this way we have 1,702,115 days’ labour in the stone Wall. Taking the north fosse at the dimensions already given, its excavation would involve the removal of 5,585,072 cubic yards. A modern excavator, stimulated by pay proportioned to his work, enjoying food, and raiment, and shelter, such as the ancient Briton was a stranger to, and possessing the advantage of good tools, and good organization, can remove the enormous quantity of twenty cubic yards of earth per day. The labourer, driven to his ungrateful task by a Roman task-master, and compelled to support himself as best he might, and to labour with tools of the rudest construction, would not accomplish the half of this task; the removal of eight yards _per diem_ would probably be an average day’s work. The excavation of the north fosse would thus, under these circumstances, involve 698,134 days’ labour. At the present time, when twenty cubic yards may be removed per man in a day, and when a day’s wages may be set down at half-a-crown, the whole cost of the excavation of the fosse would be 34,906_l._ In this estimate no account has been taken of the increased labour occasioned by cutting through the rocks that are sometimes met with. The entire absence of the ditch, however, in the hilly district, compensates for this omission.