The daily morning journal and courier., 1895-03-09
 WORhING IN DEEP WATER.
Difficulty in Getting More Than Eighty Feet Be ow the Surface.
 LI-- aL

l hA NtlLiHE MOTt lilhu EhA9
 Feet Be ow the Surface.
 From the Marine Engineer.l
 The subject of raising submerged
 wrecks is a most interesting one, though
 the practicability of such operations
 seems as yet to be limited to depths of
 about 15O to 200 feet, and even at that
 limit there are few divers who can
 stand the heavy pressure. About sixty
 or eighty feet seems to be the limit at
 which divers can work for any length
 of time without undue risk of life. H.
 M. 5, Victoria lies, it is said, in about seyenty-four fathoms of water, so there | appears to be but little probability that any attempts will be made to raise her,
 her gigantic mass being also a serious drawback to such salving operations. l Thomas w. Wales has communicated good deal of interesting information on the subject in a paper read before the Institute of Marine Engineers at Car diff He gives details of exper- fence of lifting vessels with lighters and pontoons. The pontoons or light CTS must have sufficient buoyancy to ex- ceed the weight of the submerged ves- sel, and the pontoons and lighters are brought to the submerged vessel at low water and large chain or wire cables of sufficient number and strength are passed under the wreck and adjusted into position with the aid of tugs and steam winches
 Generally divers are necessary to as- sist in passing the cables under the ship, and, on MT. Aisbitt's authority, it seems that sometimes considerable damage Is done to the salved vessels by the cutting into her plating of the chains and cables, unless their strain Is carefully distributed over the surface of the plating and over the hull of the vessel. As the tide rises and the wreck is thus lifted, it is lowed toward the shore until 1t Is beached high and dry, when any holes can be conveniently closed and the wreck foated and dock ed. This, however, describes an oper- alton of salvage where the position, size and condition of the wreck are cas- fly dealt with.
 Where a vessel Is wrecked upon a rock with extensive damage to it's bot tom, which cannot bee losed by divers, platforming is often used as a method of raising This method in particular requires the closest calculation, not on- ly as the buoyancy given to raise the wreck. but also that she shall float up- right with sufficient free board to be | lowed into safety when raised, or all | the labor may be thrown away by an | accident when she floats. Platforms | have to designed and placed to suit the | of the particular cases. Sometimes they are laid diagona1ly | within. four feet of the deck beams at one end and dip of twelve feet at the other. Sometimes they must be laid higher al one side than the other, and unless the internal weight or cargo is adjusted accordingly this may cause the vessel to turn turtle when she floats. The support of the platform to the hull or deck of the vessel must be carefully thought out for If wreck be a single decked vessel the whole of the platform strain must not be taken on its deck. Diagonal chains may be used to tie the hatch coamings and beams to the ships frames to strengthen such deck. Each division of the platform should have scuttling hatch to allow the receding tide to escape, or the air from the under side of the platform with a rising tide An air pipe should be fitted to each div sion and carried higher up above deck md iron bulkheads are not reliable for platform ends, as they are