"All ready?" asked Whittinghame.
"Ay, ay, sir."
A metallic clang echoed through the after-section. The bolt action had been unlocked and No. 5 compartment was no longer joined to the remaining three divisions.
Slowly the ultra-hydrogen was pumped out of several of the ballonettes, and gently the independent division sank towards the earth.
Stationed at an open flap in the floor, Dacres "conned" the descending part of the airship under his command. Once or twice it was necessary to start the motors to bring the two hundred odd feet of gas-bag immediately over the rectangular courtyard of the Cavarale.
By the aid of his night-glasses Dacres could distinguish the outlines of the prison with tolerable ease. Nevertheless, every moment of the descent was one of suspense.
At any instant the huge overhead bulk might be seen by an alert sentry. In that case a bomb was to be thrown into the soldiers' quarters, and profiting by the confusion the airship was to descend as fast as possible and let loose her armed crew upon the terrified garrison; but only in case of extreme necessity were explosives to be used.
Only five hundred feet more. Perfect silence reigned below, while the only sound that came from No. 5 section was the laboured breathing of the twelve men as they strove with their pent-up feelings.
"Sentry!" whispered Callaghan pointing to a motionless figure on the wall nearest to the city.
Dacres nodded. He would not trust himself to speak.