at N, and the earth from the line V—U by a tunnel driven from the slope of the hill to the point V. Later, when I had taken measurements in the cross-cut tunnel from N to Y, we filled it up with the earth from the two tunnels to north and south. It happened at the same time we were filling up the tunnel in the English School garden, and we had a fourth gang engaged in tracing the street. Hence for two or three days the surface-field of the excavations appeared deserted. Of over 20 workmen employed only two were visible, the man at the rope above the shaft for the street-tunnel and his boy with the basket. The consumption of candles during those two or three days was tremendous.
The two gangs met at the point R. I was in the southern gallery at the time, and clasped the finger of the head workman in the other gallery through the tiny hole first made. This was soon enlarged, the air rushed through, the candles flared up with a brightness they had not had for many days, and the tired boys drew a long breath. Between U and P the scarp was never more than 4 feet high above its base (from N to V we always followed the base), and at one point it was only 2 feet high. At several points stones had been clearly quarried from its top, and chippings and some large stones still left were in evidence. At such places frames were necessary, but at other points we could sometimes tunnel for several feet through the hard, firm débris without any shoring up. For example, in the cross-cut gallery, though the rock had been evidently quarried, in many places chippings had not been left, and few frames were used. Indeed, while our main galleries at the moment of writing still remain open, we have removed a great part of the frames for use elsewhere, with the result that hardly anything has caved in. This does not mean that the frames were unnecessary while the work was advancing, for then the concussion of the picks, the constant roll of the wheelbarrow, and the tread of the workmen, would have brought down the earth had there been no frames.
We traced the main scarp from V to W, and then along its turn to X, where we came on an aqueduct. Its north side is formed partly by the continuation of the scarp along the line X—Y, the scarp being here only a couple of feet high, so that the wall of the aqueduct (3 feet high) is completed by rubble masonry. Its south wall consists of rabble. The aqueduct is, hence, not rock-hewn at this point, but has its floor on the rock, and runs along the rock-scarp. It is covered with roughly-hewn slate. The width at the top is about 2 feet 3 inches, the sides slope down and at some points it has a channel 8 inches wide at the bottom. The walls are covered with two layers of mortar, the inner coat consisting of rough lime with small bits of pottery inserted, and the outer of finer lime. The mortar is exceedingly hard. For a long distance the aqueduct is quite clear from earth, but at one point it is choked up with fallen blocks. At intervals air-holes (covered with a slab) appear to have led to the surface. It runs about parallel with the "Low Level Aqueduct," some thirty feet to the north. It is very likely a continuation of the aqueduct found by Warren some 500 feet to the east,
