d 10 years later it
was adapted at Blackhill on the Monkland canal (Scotland) to replace a
double flight of locks, in consequence of the traffic having been
interrupted by insufficiency of water. There the height to be overcome
was 96 ft. Two pairs of rails, of 7 ft. gauge, were laid down on a
gradient of 1 in 10, and on these ran two carriages having wrought iron,
water-tight caissons with lifting gates at each end, in which the barges
floated partially but not wholly supported by water. The carriages, with
the barge and water, weighed about 80 tons each, and were arranged to
counterbalance each other, one going up as the other was going down. The
power required was provided by two high pressure steam engines of 25
h.p., driving two large drums round which was coiled, in opposite
directions, the 2-inch wire rope that hauled the caissons. An incline
constructed on the Union canal at Foxton (England) to replace 10 locks
giving a total rise of 75 ft., accommodates barges of 70 tons, or two
canal boats of 33 tons. It is in some respects like the Monkland canal
incline, but the movable caissons work on four pairs of rails on an
incline of 1 in 14, broadside on, and the boats are entirely waterborne.
Steam power is employed, with an hydraulic accumulator which enables
hydraulic power to be used in keeping the caisson in position at the top
of the incline while the boats are being moved in or out, a water-tight
joint being maintained with the final portion of the canal during the
operation. The gates in the caisson and canal are also worked by
hydraulic power. The incline is capable of passing 200 canal boats in 12
hours, and the whole plant is worked by three men.

Lifts.

Vertical lifts can only be used instead of locks with advantage at
places where the difference in level occurs in a short length of canal,
since otherwise long embankments or aqueducts would be necessary to
obtain sites for their construction. An early example was built in 1809
at Tardebigge on the Worcester and Birmingham canal. It consisted of a
timber caisson, weighing 64 tons when full of water, counterpoised by
heavy weights carried on timber platforms. The lift of 12 ft. was
effected in about three minutes by two men working winches. Seven lifts,
erected on the Grand Western canal between Wellington and Tiverton about
1835, consisted of two chambers with a masonry pier between them. In
each chamber there worked a timber caisson, suspended at eit