150 THE RAISING OF THE DRY-DOCK DEWEY. 
Regarding commercial floating dry-docks, with which type I am more intimately 
acquainted, I should perhaps state that they are usually placed in a dredged berth 
and that while the depth of water is sufficient to lower the dock to take the maximum 
draught for which it was designed, it is rarely or never deep enough to entirely sub- 
merge the dock. This is not, however, universally the case. In some ports, such 
as New Orleans and Seattle, the depth of water is very much greater than required, 
and in such localities special precautions must be taken. ‘This is also true of the 
Port of Prince Rupert, B.C. A paper relative to the dry-dock for this port is to be 
read at this meeting, in which a novel method of guarding against entire submer- 
gence will be referred to. 
VICE-PRESIDENT McFarLaNnp:—Is there any further discussion? Does any 
gentleman wish to comment on the paper of Constructor Adams? I am sure, in 
the absence of the author, you will all wish me to have spread on the minutes of this 
meeting that this paper was very highly appreciated by the Society. 
Nava, Constructor ApAms (Communicated):—I have read carefully the 
valuable discussion of Mr. William T. Donnelly, on my paper on the subject of 
raising the Dry-Dock Dewey, and I wish to submit the following comments and 
points of additional information: 
Mr. Donnelly notes that only the barest details of the various parts ai the work 
were given in the paper. ‘here were in reality a great many annoying difficulties 
encountered in the course of the work, but their description would have taken up 
so much space that I deemed it unwise to attempt to cover them in the paper, and 
I therefore confined the paper only to the main points of the work as a whole which 
were necessary for a full understanding of the subject. 
Mr. Donnelly seems to have inferred from my paper that there was consider- 
able leakage through the bulkheads themselves. As a matter of fact, I think there 
was little if any leakage through the bulkheads except at the very tops, which I 
think contributed very little to the flow of water from one side to the other. So 
far as I know from my experience in handling the dock, and also in raising it, all 
bulkheads were watertight at the bottoms and sides. I believe that the non-water- 
tightness at the tops was a part of the original construction. Under operating con- _ 
ditions the tops of these bulkheads need not be watertight. It was only in the work 
of raising that such non-watertightness at the tops proved disadvantageous, as it 
allowed the compressed air to go from one tank to another all over the dock, and 
thus prevented raising by compressed air alone. The leakage of water from one 
tank to another encountered in raising, was in my opinion, practically entirely 
through leaky or broken valves and corroded piping and much of it is inherent in 
the quick-opening valves and it cannot be avoided with this arrangement for drain- 
age and pumping. Mr. Donnelly seems also of the opinion that the experience with 
this dock would make it seem desirable to reduce the number of interior bulkheads. 
Personally, I am of the opinion that this is not desirable. I think the bulkheads in 
