THE RAISING OF THE DRY-DOCK DEWEY. 145 
dams first installed. The dock’s central centrifugal pump was started 
about 2.30 A. M. on June 29, 1910. “That night there was a strong wind 
and a heavy rain. The valves of tanks Nos. 6 and 7 aft were the only ones 
open at first. All forward tanks were shut off and the stop valve in the 
main line was closed just abaft the dock’s forward centrifugal pump. ‘This 
stop valve shut off half of compartments 1 and 7 forward and also some 
smaller intermediate compartments in the central pontoon, as well as the 
whole forward-end pontoon. After a very few minutes from the time the 
dock’s own pump was started it was noticed that the after end, which was 
already nearly afloat, was beginning to come up. After about fifteen 
minutes pumping the whole after end was seen to be coming up rapidly 
and the forward end of the sunken side was coming up slowly. ‘The star- 
board forward corner was being forced down. ‘This condition continued 
until the after end of the sunken side had been raised about 4 feet higher 
than the forward end of the sunken side. At this time the deck of the after 
sunken end was just coming out of the water. The forward compartments 
on the sunken side were then opened to the centrifugal pump, after which 
the sunken side came up uniformly and there was no further difficulty in 
having absolute control over the dock. The additional 2,400 tons of buoy- 
ancy obtained by clearing the machinery spaces, together with the com- 
pressed air in the after pontoon, gave sufficient buoyancy to the sunken 
side and low end so that it came up before there was any appreciable lifting 
of the high side, such as had been the case when it was attempted to raise 
the dock by one of her pumps alone. The dock came up perfectly from 
the start. It was desired to begin lifting the low end slightly ahead of the 
high end so as to provide a fairly equal height of water in all the tanks and 
thus obtain better control over the action of the dock. Furthermore, it 
was feared that if the dock were to be lifted on an even keel in the fore and 
aft direction, the sunken side might come up with a jump cn breaking away 
from the mud. This might have been accompanied by disastrous results, 
such as carrying away the big flexible steam hose or striking some of the 
power floats or the Wompatuck. By daylight,at about 4.45 A. M., the 
sunken side was well out of the water and the machinery spaces were opened 
up for access. “Three-quarters of an hour after this, steam was up on the 
dock’s own forward boiler in the sunken side and the Wompatuck was 
later disconnected and the final completion of the raising was done by 
steam fron the dock’s boiler. By 7 A. M. the floor of the dock was com- 
pletely clear of water, but the pumping was continued to bring the dock to 
the light condition which was accomplished about 10.45 A. M. 
In clearing the machinery spaces of water on the sunken side, the side 
