Caisson House and the bridge above lock 5 of the Combe Hay flight of the Somerset Coal Canal. The grade II listed house is named after Robert Weldon's Caisson Lock which, along with two others, was intended to remove the need for a flight of 22 locks and consequent great use of water. The first caisson was constructed in 1796 but suffered significant operational difficulties which culminated in the Canal Committee being trapped within when it became stuck during operation. This led to the caisson idea being abandoned and an inclined plane was substituted until the conventional locks were built.