fronted him. Dropping on his knees he examined the base. “Nothing here!” he muttered, and waded into the tiny lake that spread out before him.
Step by step he advanced, feeling carefully of the brick wall at every interval, to detect any possible weak spot, when suddenly his feet slipped into a deep hole, he was drawn under, and swept by the force of some swift current, through a small hidden aperture in the wall. When he came to the surface, he grasped at a projecting ledge, and tried to ascertain what had happened. It did not take him long to guess. The marshy land in and about Leyden was constantly intersected by the formation of new brooks and streams. Not infrequently they would undermine the very wall itself, and in times of peace, these defects were always carefully watched and remedied. But in the terrible strain under which the city had existed for the past months, this one had evidently passed unnoticed, and in truth, no one would have sus-
