Now, we will be off." Fastening the sheet firmly to one of the bars, he swung himself out, slid down the rope quietly and noiselessly, and entered the water, which was so cold that it almost took his breath away.

He swam a stroke or two along the wall, and waited until joined by both his comrades.

Their casemate being the end one, they had but some ten or twelve yards to swim to the angle of the wall.
Another fifty took them to a point facing the cut.

Fergus had paced it on the rampart above, and calculated that each stroke would take them a yard.

It was too dark to see more than the dim line of the wall on the other side.