My predecessor had laid the foundations of the east wall of the convent, but being ill acquainted with the nature of the ground at Jerusalem, he discovered too late that they rested, especially on the north-east, on unsolid ground, namely, on the vaulted roof of a subterranean building, and as the walls rose they began to crack. Some of the masons were just aware of the existence of the vault when I came; but no one had entered, or measured it, or examined its whole length, so that I was the first to do this and determine its age. In order to build a buttress at the north-east corner, and at the same time to lay new foundations in a small plot of land on the north, I was obliged to dig a hole, 18 feet deep, below the level of the street, which rises towards Bezetha: and on the 3rd of June came upon a layer of large slabs, each 4 or 5 feet long, 3 or 4 wide, and 9 or 10 inches thick. On removing two of these I found a square hole, through which I entered, or rather fell, into the vault I was looking for, but the intense heat and foul air compelled me to beat a hasty retreat, and have the aperture enlarged to permit the air to circulate more freely. Meanwhile I continued excavating a little to the north, and met with the wall bounding the vault on that side, and found, 4-1/2 feet below its top, (measured from the outer surface,) the original entrance; by which I obtained easy access for myself and afterwards for many others. The end of the east side of this gallery is just at the south-east angle of the building on the north, separated from the body of the convent by a small level street; and it terminates at the north-west angle of the _Haram-es-Sherîf_; the floor throughout the whole length slopes slightly and is formed in the rock: though the place was partly filled with earth at the north end, and with filthy stinking mud at the south, I thoroughly examined it and made a plan and elevation. At the entrance a stone staircase, with steps about 2-1/2 feet wide, afforded an easy descent; but unfortunately I was obliged to mutilate this, in order to construct a pier to sustain the weight of the north-east corner of the building above. The side walls are founded on the rock, which appears above the level of the floor, at a distance of 69 feet from the entrance, and gradually rises in them up to the southern extremity. They are built of squared blocks, generally 3-1/2 feet long, and from above 2 to 3 high, perfectly fitted together. The semicircular vaulting is admirable, being formed of oblong stones, 2-1/2 feet long, and 8 inches high. Its exact regularity is its most striking feature.