Page:Roman Manchester (1900) by Charles Roeder.djvu/36

 when no longer required to make room for the suburb; (4) the formation of a road over it in the second century; (5) the final accumulation indicating when the station fell into decay.

.—We have once more to return to the northern wall. The situation of the Porta Principalis dextra evidently was a little west of Collier Street, now occupied by the little coalyard. It was 6 feet wide, but unfortunately its structure could not be traced, the upper part having been taken out for a culvert. At its base we find a course of rectangular stones, varying in length and height, 11 inches and 12 inches long, 19 inches by 10 inches and 24 inches by 12 inches; these, with the exception of the latter, which is of white millstone grit, were all of red sandstone. Only the internal part of the wall being exposed to view, it was, of course, impossible to follow the passage outside the wall and the access to it from the fosses. The stones were placed close together without the use of mortar. At Whitaker's time (see pp. 36-7, vol. i.) the gateway was still rising 4 feet to 6 feet high.

He also tells us (Principal Corrections, p. 12) that in the northern wall itself small circular arches were left, at certain distances, five or six in number, the facing of one side still remaining over two of them. They were found below the natural surface of the ground. He noted them carefully in 1772. One that was accidentally laid open from end to end disclosed the design of all. He says, "As the Romans carried their walls upwards they took off the pressure from the parts below and gave a greater strength to the whole, by turning little arches in their