The sluice gate inside this pit was raised and lowered using high pressure water. Raising the sluice allowed water to flow in or out of the lock to balance the levels on both sides of the gates.
Site: Lock keeper and hydraulic sluice (4 memorials)
SE16, Princes Court
None of these four plaques are visible in our photo (and still this was the best position form which to take the photo!) all being hidden by the building. The Office plaque is on the right side of the building. The Sluice plaque is on the railings to the right. The Bridge plaque is on the railings closest to the bridge. The Engine plaque is inside the pit behind the building.