page_title: Caisson lock
hierarchical_section_title: Caisson lock
caption_attribution_description: English: Sectional engraving of caisson lock built at Combe Hay, England
context_page_description: 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.
  It was designed primarily as a water-saving measure, and also was an attempt to minimise construction costs compared with other engineering solutions of the time. In use it was capable of replacing up to seven conventional locks. Other design benefits were speed of boat descent/ascent, and only a little loss of water when operating compared with a conventional boat lock.
context_section_description: 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 (or caisoon) 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.
  It was designed primarily as a water-saving measure, and also was an attempt to minimise construction costs compared with other engineering solutions of the time. In use it was capable of replacing up to seven conventional locks. Other design benefits were speed of boat descent/ascent, and only a little loss of water when operating compared with a conventional boat lock.
caption: Contemporary engraving of the lock at Combe Hay
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