The cell itself was like a tomb. It was about ten feet long by eight broad and twelve high, lit by one small window which looked out on to a dirty, dingy quadrangle, surrounded on all sides by the buildings of the Holy Office. The unglazed window itself was barred up with stout iron bars, which were deeply sunk into the wall, the thickness of which was fully four feet, and much too thick and strong for them ever to dream of breaking through without the aid of tools, plenty of time, and no interruption. The ledge below the grating was foul, and piled high with the accumulated filth of years; and the cell walls were damp and slimy, covered with a growth of fungus nourished by the hot and steamy moisture. The building itself was some hundreds of years old, having been an Aztec temple before the Spaniards had taken it over and adapted it for its present purpose. The cell door, which had been of stone in Mexican times, consisted now of a thick and solid slab of teak, strongly bound with iron, and stout enough to resist the attack of a battering-ram. Chancing once to glance upward and toward the door--having heard some slight sound outside,--Roger was just in time to catch sight of an eye-- a dark, shining, and sinister orb--glued to a small hole in the door, which he had not before noticed, and which was apparently covered when not in use for spying purposes. It was evident that a watch, constant and strict, was to be maintained upon them, and that therefore any attempt at escape on their part, which they might be ill-advised enough to hazard, would be discovered at once and promptly frustrated. In fact, it appeared that escape was too absolutely hopeless and impossible to be thought of seriously. As Roger glanced up, the eye vanished, leaving them with the unpleasant sensation of being continually watched. "We are being spied upon, Harry," whispered Roger. "I saw an eye at the door just now." And he indicated the place to his friend. Harry rose and went toward the door, and as he did so both lads caught the sound of a retreating footstep. "If we had anything suitable," replied Harry, "we might close it up. But I suppose it would be quite useless for us to do so; they would only clear it out again, and very likely torture us for our pains." "Well," remarked Roger, "if they do here, as they did at La Guayra--that is, always pass our food in through a trap in the wall, and never enter the cell,--we might risk doing it and see what happens. They can but open the hole once more. And we can make no plans, nor indeed can we do anything, while we are watched constantly; so we might try it at all events."