1984 - Discovery of Old No. 2 Basin Caisson

March. Discovery of No. 2 basin caisson.

During road surfacing works on the north-western corner of No. 2 basin the top of the original iron caisson of 1845 was discovered at the site of the old entrance. With the extension of the dockyard during the late 1860’s the Tidal basin was formed with a northern wall, (here was sited the coaling station); its eastern side formed the entrances to the Deep Dock (No. 9 Dock) and A & B Locks. It was decided to reform the old northern wall and to move the entrance to No. 2 Basin further into the Tidal Basin. The old entrance was walled up each side of the old caisson and filled with shingle and there the old caisson lay forgotten until 1976 when part of it was uncovered and quickly covered up again but in March contractors completely uncovered the old road deck of the caisson. The Portsmouth Royal Dockyard Historical Society was given the week-end to make a complete survey of the structure exposed, producing a paper entitled Discovery of the Steam Basin Caisson. The caisson is 80ft.6ins in length by 16ft.2 ins wide and with a depth of approx 34ft. and weighing some 400 tons. Next to Brunel’s “Great Britain”, it is probably the oldest ship-shaped iron structure in the world and at some time in the future will be rediscovered.