Submarine Appliances And Their Uses
Deep Sea Diving, &c., &c.

This vessel was run into and sunk in Belfast Lough, in about 45ft. of water, and ten miles from the shore. An examination of the wreck showed her to be embedded in clay, and the rise and fall of the tide being only about 9ft. at springs and 8ft. at neaps, there was very little assistance to be looked for in that direction. Messrs. Harland and Wolff, of Bel- fast, who undertook to raise her, had previously been engaged in raising the Earl of Dublin, and the pontoons used for that vessel, six in number, and having a combined buoyancy of 500 tons, were fortunately available. In addition to these, two larger pontoons, each 70ft. long by 12ft. wide by 9ft. deep, each containing 7,560 cubic feet, and each having a dis- placement of 216 tons, were constructed. Each of these pontoons was divided into six water- tight compartments, so that each or all of them could be filled with water or pumped out as desired. Thus the lifting power employed had a buoyancy equal to about 932 tons, the deadweight to be lifted being estimated at about 850 tons. Fi#. No. 68. The six smaller pontoons, or caissons, were placed together and rafted over at the head of the sunken ship, and a similar raft or floor was constructed upon the two larger pon- toons, which were floated to the after end of the wreck. These two rafts were afterwards connected by two stout beams fore and aft, binding the whole of the pontoons into one floating platform of the size of the vessel below. Cross logs or joists had been laid across the pon- toons in such a manner as to correspond in position with the side ports of the wreck, through which holes the lifting chains were afterwards passed by the divers. Of the ports there were twenty-five on each side, so that each had to bear a strain of about 17 tons. In each of the angles formed by the projecting ends of the joists and the sides of the pontoons was fitted a box bracket of wrought iron, carrying a hexagonal cast-iron sheave about loin, diameter, grooved for the links of the lifting chains, which were of ijin. diameter, and the links io|in. long, over all. On the top of each joist, two screws, each 5ft., jin. diameter, and of fin. pitch, were fixed, one on each side, by which to tighten or take in the lengths of the chains. The lower ends of the chains were fitted with hooks to take hold of the vessel through the side-lights. About 200 men were employed at first in putting the pontoons into place, putting down the cross-joints, or flooring, etc., and afterwards about 100 men to work the screws, etc. On taking in the chains by means of the screws and pulleys, the wreck was lifted and carried about 6ft. on the first day, but a nasty sea springing up, two of the lifting chains gave way, letting the fore ends of the two forward pontoons burst up, and breaking'three of the cross- joints and the top of the starboard pontoon, whilst the port pontoon was bent in by the extra strain thus brought upon it. This necessitated the filling of the fore-compartments of each of the forward tanks to relieve the strain on the Jbows, whilst the clivers went below to re- couple the chains. Other trifling difficulties occurred on the following day, but the wreck was continually moved for short distances and grounded, until, on the thirty-fifth day, the wreck was towed into Abercorn Basin. The number of tides in which the vessel was actually moved was fifteen; the other tides were employed in putting right the various little mishaps that occurred. The wreck, 850 tons in weight, had been lifted 45ft. and towed ten miles, the total cost of the operations being about ^6,000. 142