Diving, aside from the pleasure afforded to good swimmers, is important in many different industries, particularly in fishing for pearls, corals, sponges, etc.

Without the aid of artificial appliances a skilful diver may remain under water for two, or even three minutes; accounts of longer periods are doubtful or absurd.

LONGITUDINAL SECTION OP HOPPER DREDGER, Employed on the River Clydo The Vessel steams to place of working and is moored by the Steam Winches a A at how and Hero to buoys, the Bucket Ladder B is then lowered by team power, and thereafter Buckets SCD in motion by gearing cc The depth of water at which the Bucket Ladder dredges is regulated by the Hoisting Shears and Chain Barrel DD, driven by shafting EE from the Engines. The Buckets discharge the material by the shoot r into the Hopper a. Tho dredged material is discharged by the doors of the Hopper being opened by the Lifting Chains h h. These doors axe hinged on to the side of Vessel, and suspended at centre by the Lifting Chains, which are cooaccted to geared Crab Winches 11.

SECTIONAL VIEW OF DTVIDING BELL AND BARGE, Employed on the River Clyde.

All the appliances are worked by steam, rendering manual labour unnecessary A is the Belt which is raised and lowered by means of the Chain and Steam Winch b. c c are Seats within the Bell; d d. Footboards. «. Air-pipe entering the Bell at f,, the air being supplied by Air-pump c driven by the Engine H. J is a Steam Crane for raising or lowering material. K k, Steam Winches for working moorings and shifting position of the barge.

Various methods have been proposed and engines contrived to render diving more safe and easy. The great object in all these is to furnish the diver with fresh air, without which he must either make but a short stay under water or perish.

Diving bells have been used very effectively. A diving bell is a contrivance for the purpose of enabling persons to descend, and to remain, below the surface of water for a length of time, to perform various operations, such as examining the foundations of bridges, blasting rocks, recovering treasure from sunken vessels, etc.

Diving bells have been made of various forms, more especially in that of a bell or hollow truncated cone, with the smaller end closed, and the larger one, which is placed lowermost, open.

The air contained within these vessels prevents them from being filled with water on submersion, so that the diver may descend in them and breathe freely for a long time provided he can be furnished with a new supply of fresh air when the contained air becomes vitiated by respiration. This is done by means of a flexible tube, through which air is forced into the bell.

A form, called the "nautilus," has been invented which enables the occupants, and not the attendants above, to raise or sink the bell, move it about at pleasure, or raise great weights with it and deposit them in any desired spot.