Directly the man went out Hamerton placed the packet of pepper in the only pocket of his coat, in which there was already a couple of handkerchiefs and his watch.
"I didn't think I should obtain the pepper so easily," he soliloquized. "It will come in very handy before many days are past."
Hamerton made a late start that evening. Detroit was in a very communicative mood, tapping out messages with tremendous zeal, till his friend had to caution him not to make so much noise, through fear of being overheard.
It was just twelve when Hamerton, using the steel as a lever, found to his great delight that the stone was actually loose. For the next half-hour he worked like one possessed, with the result that the slab was displaced. Half-dreading the outcome of his investigations, Hamerton groped cautiously with his hand into the deep cavity. Almost at arm's length his fingers touched a mass of rubble. The floor was hollow.
Now, for the first time since his incarceration, the Sub wedged the door of his cell by means of the stool. Thus he was fairly safe from interruption, and in the event of a nightly visitation he might be able to replace the stone and hide the traces of his handiwork before admitting his jailers.
This done, he attacked the slab adjoining the hole in the floor. By dint of much heaving he succeeded in displacing it without having recourse to the tedious process of chiselling out the cement.
"I wish I had a box of matches," he muttered. "Only a mole could find its way about in that hole. Well, here goes!"
So saying, he lowered himself into the pit, so black that by contrast his cell was fairly illuminated, for the searchlights were constantly flashing skywards.
Between the under side of the stone floor and the rubble on which he stood was a space of about eighteen inches in height. It was like sitting on the summit of a mound, for the surface descended on all sides. Hamerton was standing on the crown of one of the vaulted arches of the store under the prison cells. During his exercise hour in the courtyard he had made the discovery that the room on the ground floor was vaulted.
"Easy ahead!" he muttered between his closed teeth, for the dust rose in clouds in the confined space. Before he had crawled very far the height increased sufficiently for him to be able to kneel upright. Then his hands came in contact with a wall—the division between his cell and that occupied by the American.