As soon as Jacques had fastened the wire to the ring he touched another heavy spring under the sill, then pulled hard on the trap-door; this gradually began to sink, and in a minute was in its place again. At the same time the brick that had been pushed in above came out into its place again, dust was then swept into the crack at the edge of the trapdoor, and no one who had not seen the latter raised would have dreamt of its existence.