The seventh wedge, however, gave, at its wider end, on the entrance-gate, which was a square, semi-fortified building, pierced by a tunnel, gated at each end, and further protected by an outside yard, or roofless porch, also gated. The inmost of these three gates opened on to a small courtyard, and this narrowed again into an alley which gave access to the central tower. Briefly then the whole gaol consisted of six wedges opening, by a door in their narrow end, into the central cylinder; and a seventh wedge split in two by an alley leading between high mud walls from the gateway to that central tower; the key to the position. In the two halves of the split wedge lay the warders' barracks, the solitary cells, the cook rooms, the hospital; and the entry to these was by a door on either side of the little courtyard, just beyond the inner gate. From the corner of this, also, rose the outside stair leading to the roof of the square, brick gateway. Thus the fifteen hundred prisoners were broken up into companies of about two hundred each, and were absolutely without possibility of communication so long as the central tower was in the hands of authority. Unless there was time to undermine the mud walls, and tools, also, wherewith to work. Of these, however, there were none in the gaol. Nothing, even, that could be used to take their place, except in that seventh section which held the executive of the gaol; and there Dr. Dillon meant to leave no hands to use them, if he could compass it. As he pulled up to regain his breath before walking up to the gate and giving the countersign, the whole place lay quiet and dark. So far, good. There was the risk, however, of the plot being known, and of the sentry refusing him entrance. It was not, however, and the next moment, calmly as if he was merely on one of his not infrequent rounds of unexpected night inspections, Dr. Dillon passed from the outer porch to the tunnel, and told the sentry at the inner gate to light the lamp in the little office room to one side. "Call the superintendent," he said to the first man, "and you can tell him I am going to inspect the solitary cells." He added this because he knew it would give time, since the superintendent would be sure to give a private look round, first, to see all was in order, and remove possible traces of tobacco or opium,--those luxuries out of which so much money can be made by gaol officials.