"If you feel for it on your right you will find a rail. This is the rail of a bridge which crosses from this house to one in the street behind. When I took this room I took that house. It will remain empty. Cross the bridge. Close to your hand, on your left, you will find an iron ladder set straight against the wall. Descend it, you will land yourself on the flat roof of an outhouse. Within a foot of you, still to your left, there is a window. It will be always left unlatched. You have only to raise it, enter the empty house, strike a light, and walk downstairs into the street. To reach that particular house, in that particular street, by road, a policeman will have to walk two miles."
"How long is this bridge of yours?"
"Under twenty feet."
"And how wide?"
"Perhaps ten inches--it is a single plank. The rail by which you hold is firmly fixed and bolted at either end. What the whole arrangement was intended for originally is a puzzle I have not attempted to solve. I heard of it. I thought it might suit us."
"Don't you think we ought to do what the firemen do--have a full dress rehearsal? I, for one, should hardly care to seek that path to safety without having had some practical experience of the peculiarities and perils of the way."
Pendarvon laughed.
"You fellows can have a rehearsal to-night, if you like--only you will get yourselves into a deuce of a mess. I don't guarantee that you will be able to keep yourselves clean. I only guarantee that that way, at a pinch, you will be able to save your necks."
As he finished speaking, the electric bell rang twice; there was a pause; then a single ring; another pause; then twice more. Pendarvon went to a gong which was suspended from the ceiling outside the room. He struck it, not too loudly. A voice on the other side of the other door exclaimed--
"Gustave!"