SLIPWAY AT DOVER. 495
The cr oss-pieces, or bilge-cods, are of oak, the four central pairs being
37 feet long and the remaining three, 33 feet long. They are secured to the
centre longitudinal by placing the ends of a pair of cods together, and
wedging out against two cast-iron knee-pieces with small teeth on their
faces, these fit into holes in the cods. The bilge-cods are shaped on the
upper face to a slope of about 1 in 14, and for the greater part of their
length, strips of iron, 3 inches wide, are let into them and upon these run
the sliding bilge-blocks. The longitudinals at the bottom of the cradle are
framed into oak cross-pieces, and are stiffened by four cast-iron brackets.
Figs. 488 and 489.—Plan and Elevation of Cradle.
Figs. 490 and 491. —Details of Cradle.
At about every 20 feet in length of the main and auxiliary cradles, a
pawl is fixed under the centre beam, working in the rack between the rails.
When not in use, it may be lifted up into a horizontal position. The
auxiliary cradles have no bilge-cods or blocks. Chains are fixed to the
sides of the main cradle and attached to the auxiliary lengths near the
centre. They have a sectional area of 1 square inch and are provided with
adjusting screws. The rollers are 8 inches in diameter, 3J inches wide on
the face, with a flange g inch deep. They are of iron, cast round a If-inch
Bessemer steel shaft, bossed out and roughened in the centre. The wrought-