PACIFIC RAILWAY, PRINCE RUPERT, BRITISH COLUMBIA. 227 
Referring to Plate 116, there will be seen the general design of the ma- 
chinery house for the different sections, and on one side of each section there 
will be provided an electrically driven air compressor having a capacity of 
500 cubic feet per minute. The air will be delivered to a receiver in the 
wing below, and from this to air piping carried along the bottom to each 
side of the wing, with multiple outlets for the connection of air hose to the 
pneumatic tools. Provision will also be made for connection between the 
sections of the dock when they are operating together. 
Electric current for operating the air compressors will be taken from 
the circuits supplying the motors for pumping the dock, and as air will be. 
used only after the dock is pumped up, the capacity of these circuits will be 
more than ample. 
OPERATING EQUIPMENT, BILGE BLOCKS, KEEL BLOCKS, ETC. 
Referring to Plate 112, there will be seen the arrangement of keel blocks 
and bilge blocks. The keel blocks are to be of oak 12 x 16 inches x 4 feet long. 
and are to have a height of 4 feet. The bilge blocks are to be on about 
12-foot centers and operated according to the usual American practice. 
by means of a galvanized chain on the floor of the dock and a leading rope 
through 6-inch sheaves secured to the wing near the deck, leading up and. 
returning over the pipe railing around the tops of the wings. The return rope 
leads to the tail dog and is used in tripping the dog and pulling the block out 
when the ship is leaving the dock. The bilge blocks are provided with 
an elevating screw which has been found to be of great service for removing 
blocks one at a time for painting. 
In the American practice of handling floating dry-docks, side shoring 
is not used. ‘There is a general practice, however, of using centering trams 
for locating and steading the vessel in position until firmly at rest upon the 
keel and bilge blocks. The arrangement of these trams can be seen in Plate 
112, showing the general design of the dock. 
ILLUSTRATIVE DISPLAY DRAWING. 
There is also submitted herewith, an illustrative display drawing or 
perspective view (Plate 117), carefully prepared as to relative scale and proper 
angular projection from the plans, the background being worked in from 
actual photographs taken approximately from the viewpoint of the 
illustration. : 
