454 Proceedings. 



Mr. George next gave some quotations from tlie " Encyclopsedia 

 Britannica," speaking in strong terms of tte many advantages vs^liicli slips 

 possess over dry docks, particularly as to cost, wticli tHey quote as one to 

 twenty ; lie explained the method of using and working tte slip, and quoted 

 some examples as to the favour with whicli slips are now being looked upon. 

 Eor instance, a slip for raising vessels of 3,000 tons register was supplied 

 by Messrs. Morton to the Egyptian G-overnment; and Messrs. Inglis, of 

 Glasgow, in 1867, erected a slip 800 feet in length for raising vessels of 

 3,000 tons, dead weight. 



There did not appear to be on record any instance in which a ship has 

 sustained permanent injury, when being placed on a slip, or in being 

 launched. In the case of the first vessel placed on the Melbourne slip, she 

 was satisfactorily raised out of the water, but, from the subsidence of the 

 ways, would not run off again ; the vessel was not permanently injured. 

 The same difficulty as in Melbourne occurred in launching the " Great 

 Eastern," in 1857, and with the iron-clad " Northumberland," of 6,650 tons 

 register, and weighing 8,000 tons, at the Millwall Ironworks. The sub- 

 sidence of the ways in the two last examples is not much to be surprised at, 

 when we remember that the foundation of the ways consisted of Thames 

 mud. 



On the other hand, graving docks also are not free from liability to 

 accident. At Marseilles, the " Imperatrice," a steam ship of upwards of 

 2,000 tons register, fell bodily a height of three feet, from the giving way of 

 the struts, after the water had been pumped out of the dock, and everything 

 moveable in the vessel was broken. 



The principal objection urged against slips is, that in launching a vessel 

 she would be liable, as the phrase goes, to " break her back," from the fact 

 of her after part being afloat, and lifted by the action of the water, while her 

 fore part was fixed in the carriage. This the author endeavoured to dispel 

 by entering into a consideration of the force of waves during storms, and 

 argued that a ship that could be so strained in being launched from a slip 

 as to be at all damaged, would not be in a fit state to resist the action of the 

 sea during a storm, and therefore would be much better in port. 



Mr. George concluded by remarking, that extremes are dangerous in all 

 things, and that he was not then prepared to assert the superiority of slips 

 over docks, or docks over slips, but to show that those who are prepared to 

 do so ought also to be prepared to support their assertions, either by citing 

 some high authority, or by adducing facts in support of their assertions. 

 Theory, practice, and science must all naturally be brought to bear on such 

 a subject ; docks have been subject to all three. Theory and science have 

 been applied to the question of the value of slips, but more practice is 



