Many types of manipulators have been developed by the CEGB and there has been increasing use made of computers for control and display purposes. The ‘snake’ is a_multi-link manipulator in which the in­dividual units are motorised to enable the whole to be manoeuvred through a tortuous route. Computer control is employed to guide each link through the same path as the lead link and to reverse the process on withdrawal. Prompt programs are used extensively to assist the operator to recall critical sequences of operations and to provide data and work procedures.