Caisson lock

Type of canal lock

The caisson lock is a type of canal lock in which a narrowboat is floated into a sealed watertight box and raised or lowered between two different canal water levels. It was invented in the late 18th century as a solution to the problem posed by the excessive demand for water when conventional locks were used to raise and lower canal boats through large height differences. Such locks, each of which would only raise and lower boats through small height differences of a few feet, would not suffice when large height differences had to be tackled nor when water was in short supply. The caisson was thought to be one solution, although it transpired that the technology of the day was not capable of achieving this type of construction economically.

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