224 THE MARINE TERMINAL OF THE GRAND TRUNK 
board feet. The entire bill of lumber will be of selected grade of Oregon 
pine or Douglas fir. 
As previously stated, it is the intention to have these pontoons built upon 
the launching platform under the building shed, using the tools and equipment 
provided for the plant. Sufficient room has been allowed to build three 
pontoons at the same time. Assoonas they are launched they will be moved 
into the basin between the pier and dry-dock platform and temporarily 
united together in correct relative position by timber clamps, when they will 
be ready for the erection of the steel wings. 
For further information relative to the use of wood for the construction 
of floating dry-docks, parties interested are referred to a paper on ‘Floating 
Dry-Docks in the United States—Relative Value of Wood and Steel for 
their Construction,’’ appearing in the Proceedings for 1910 of the Society 
of Naval Architects and Marine Engineers. 
STEEL WINGS. 
By referring to Plates 112 and 114, showing the completed structure and 
the design of the wing trusses and plating, a general idea will be gained of the 
construction of the wings. They consist of channel and angle frames on 3- 
foot centers corresponding to the trusses of the pontoons, and a covering 
of plating varying in thickness from one-half to five-sixteenths inch. The 
construction is greatly facilitated by reinforcing the plating against water 
pressure on the outside by horizontal angles. This does away entirely with 
troublesome intercostal connections and gives the material used very much 
greater value in the construction as a whole. 
By referring to the table of weights it will be seen that there are required 
about 2,200 tons of steel. Where the wing meets the deck of the 
pontoon there is a steel shoe secured to the frame of each pontoon and a 
corresponding shoe riveted to each frame of the wing. ‘These are connected 
together by a steel link about 15 inches long and pins, the upper one of 
which is tapered one-half inch to the foot. The driving of this pin wedges 
the pontoon and wing together. At the point of contact, the bottom of 
the wing is reinforced by a 12 x 3-inch plate and made water-tight by canvas 
packing saturated with red lead. On the outer side of the wing the method 
of securing is similar, except that the shoe on the pontoon is replaced by a 
cast-steel strap through-bolted to the pontoon. 
Provision is made for multiple punching on uniform centers of 
3 inches and 6 inches throughout and the intention is to have the material 
fabricated in Europe or the eastern part of the United States, all frames 
