Two centuries of shipbuilding by the Scotts at Greenock

100 Work on the Building Berths : Pneumatic Tools.
by a simple and ingenious cableway, known in the Works as
the " switchback," from its resemblance to the well-known
amusement railway. A derrick-post stands at the head
of the berth adjacent to the skids on which the frames
are riveted. The cable stretches from a small derrick at
the foot of the shipbuilding berth over a pulley at the
top of the large derrick-post, and thence, through a similar
block at its base, to an electric winch. The frame or unit
of the ship's structure is suspended on a running block on
the cable, which is then made taut, partly by the working of
the winch and partly by the large derrick post being inclined
backwards. The running block with its load travels down
the taut cable by gravity, under the guidance of the squad
of fitters. The gradient of the cableway is only sufficient
to enable the load to move slowly to its position in the
shipbuilding berth.
The double - bottom frames and margin plates are
united with the keel-plate, and subsequently there are suc-
cessively worked into the structure the tank top plates, side
frames, the skin plates, beams, bulk-heads, and other units,
portable hydraulic punches and riveters being largely used.
Pneumatic tools are also extensively employed for boring,
drilling, riveting, chipping, caulking, etc. There are from
130 to 140 of these tools in use on vessels in course of
construction.
There are ten building berths ranging in length up
to 700 ft. ; but slight alterations would enable the firm
to build vessels of still greater size. Several of these are
shown on the engraving on Plate XXXVII. , facing page 88.
The launching ground is probably the finest in the river,
the channel being here of great depth and very wide, as is
shown on the engraving opposite. Indeed, ordinary merchant
vessels with full lines are launched without any check
chains ; the fine-ended ships — mail steamers and cruisers —
are, as a precautionary measure, checked by drags in the