Basic construction and operation A plan and side view of a generic, empty canal lock. 1410–1475) constructed 18 pound locks on the Naviglio di Bereguardo (part of the Milan canal system sponsored by Francesco Sforza) between 14. Yet the first true pound lock was built in 1396 at Damme near Bruges, Belgium. This pound lock serviced many ships at once in a large basin. In medieval Europe a sort of pound lock was built in 1373 at Vreeswijk, Netherlands. The water level could differ by 4 or 5 feet (1.2 or 1.5 m) at each lock and in the Grand Canal the level was raised in this way by 138 feet (42 m). The gates were 'hanging gates' when they were closed the water accumulated like a tide until the required level was reached, and then when the time came it was allowed to flow out. The distance between the two locks was rather more than 50 paces, and the whole space was covered with a great roof like a shed. They replaced earlier double slipways that had caused trouble and are mentioned by the Chinese polymath Shen Kuo (1031–1095) in his book Dream Pool Essays (published in 1088), and fully described in the Chinese historical text Song Shi (compiled in 1345): Pound locks were first used in China during the Song Dynasty (960–1279 CE), having been pioneered by the Song politician and naval engineer Qiao Weiyue in 984. In contrast, an earlier design with a single gate was known as a flash lock. A pound lock has a chamber with gates at both ends that control the level of water in the pound. Pound lock A pound lock on the Keitele– Päijänne Canal at Äänekoski in Central FinlandĪ pound lock is most commonly used on canals and rivers today. Later canals used more and larger locks to allow a more direct route to be taken. Locks are used to make a river more easily navigable, or to allow a canal to cross land that is not level. The distinguishing feature of a lock is a fixed chamber in which the water level can be varied whereas in a caisson lock, a boat lift, or on a canal inclined plane, it is the chamber itself (usually then called a caisson) that rises and falls.

JSTOR ( March 2022) ( Learn how and when to remove this template message)Ĭanal lock and lock-keeper's cottage on the Aylesbury Arm of the Grand Union Canal at Marsworth in Hertfordshire, England Lock on the River Neckar at Heidelberg in Germany Three Gorges Dam lock near Yichang on Yangtze river, China A gate in the Hatton flight in England Iroquois Lock on the Saint Lawrence SeawayĪ lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways.

Unsourced material may be challenged and removed.įind sources: 'Lock' water navigation – news Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.

Wooden key holder single