Kennedy dashed out on the street and down the outside cellar stairs, followed by us.
He paused at the thick door and listened. Apparently there was not a sound from the other side, except a whir of a motor and a roar which might have been from the furnace. Softly he tried the door. It was locked on the inside.
Was the bomb-maker there still? He must be. Suppose he heard us. Would he hesitate a moment to send us all to perdition along with himself? How were we to get past that door? Really, the deathlike stillness on the other side was more mysterious than would have been the detonation of some of the criminal's explosive.
Kennedy had evidently satisfied himself on one point. If we were to get into that chamber we must do it ourselves, and we must do it quickly.
From the package which he carried he pulled out a stubby little cylinder, perhaps eighteen inches long, very heavy, with a short stump of a lever projecting from one side. Between the stonework, of a chimney and the barred door he laid it horizontally, jamming in some pieces of wood to wedge it tighter.
Then he began to pump on the handle vigorously. The almost impregnable door seemed slowly to bulge. Still there was no sign of life from within. Had the bomb-maker left before we arrived?
"This is my scientific sledge-hammer," panted Kennedy, as he worked the little lever backward and forward more quickly—"a hydraulic ram. There is no swinging of axes or wielding of crowbars necessary in breaking down an obstruction like this, now-
