Dock engineering had been developing since the sixteenth century. But engineers were not part of the dockyard officer corps who nevertheless had to conduct such works. This had been acceptable when structures were wooden and foundations firm, but not when stone structures had to be set upon frail and leaking footings as at Portsmouth. The achievement of communication with, the comprehension of and cooperation from the yard officers were major challenges for the Inspector General. Although based at the Admiralty in London, he was aided by his office Architect and the secondment to him of the assistant to the Master Shipwright at Portsmouth, Henry Peake. Both Bentham and the officers were aided by the Master House Carpenter who had held his post since 1777. But in communication the officers stuck rigidly to the letter of regulations. Bentham used models and plans to express his requirements but would not consider himself responsible for mistakes in their execution. The nature of the works at Portsmouth demanded special knowledge of dam construction, pile driving, masonry, stones and cements, but this was nothing without knowledge of the clay and shale strata underlying the works. To build larger, deeper and stronger, Bentham invented the ‘inverted masonry arch’ for entrances to the basin and docks. He also developed the floating caisson to close them. The works were described in 1798 to the Secretary for War as ‘stupendous’. Indeed, the conversion of the Boat Channel for frigates gave Portsmouth double the docks of any other yard.