DIVING BELL, ON THE SHANNON WORKS. 247 for working the crab and the air-pump ; and it was moved along the transverse balks by means of bevel gear connected with its wheels. A similar travelling frame, and having a carriage with a crab winch upon it, was also placed upon the longitudinal framing, for lowering the stones into the sea, which was done in the following manner. The stone, aflerbeing cut to the proper dimensions, was fitted with a common " Lewis," and as soon ns it was lowered to the

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... ottom of the sea, the hook of the crab chain was detached from the Lewis, by the use of what was termed a "tripping line," which, being pulled, drew the hook out ofthe ring. The frame was then removed to procure and lower another stone. The hell frame was then brought over the place, where the stone had been sunk, and being lowered, the men in it having found the stone, hooked it on to a chain slung from the interior of the bell, and by this means the stone was carried to