454 Proceedings. 
Mr. George next gave some quotations from the “ Encyclopedia 
Britannica,” speaking in strong terms of the many advantages which slips 
possess over dry docks, particularly as to cost, which they quote as one to 
twenty ; he explained the method of using and working the slip, and quoted 
some examples as to the favour with which slips are now being looked upon. 
For instance, a slip for raising vessels of 3,000 tons register was supplied 
by Messrs. Morton to the Egyptian Government; 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 
Re tea 
: been ap li d to the question of the value of slips, but more practice is 
