casemates, consist of alternating pairs of shell and cartridge rooms accessed via an ammunition passage at the front and a lighting passage behind. Great care was taken to reduce the possibility of an accidental explosion. The magazine workers wore special clothes and shoes to eliminate the risk of striking sparks and the floors of the cartridge stores were covered by wooden battens. The lighting was provided from oil lamps situated behind glass windows and accessed only from the lighting passage, which was physically separated from the rest of the magazine. Sets of lifting gear enabled the workers to winch the cartridges and ammunition up to the casemates, with which they could communicate via voice tubes. A defensible barracks made of brick, faced in Kentish ragstone on the fort's exterior, closes off the gorge. Its line is indented to facilitate small arms fire from loopholes and windows with armoured steel shutters. The first floor of the barracks had a veranda facing towards the fort's interior and supported on cast-iron pillars. The barracks provided accommodation for a wartime complement of six officers and 180 NCOs and men, though in peacetime only small maintenance detachments occupied the fort. It also accommodated storerooms and a hospital with room for fourteen patients. Although much of the barracks is now in poor condition, two of the kitchen ranges still survive and two rooms still contain service crests painted on their walls during the Second World War. An irregularly shaped parade area occupies the middle of the fort, which is divided by a sloping ramp leading up to the casemates. A small brick building – originally used as a laboratory or shell-filling facility – stands to the right of the ramp. The fort is entered through a single gateway on its west side, protected against landward attackers by a caponier. The front of the fort was surrounded by a dry ditch, in which there were originally four caponiers to provide musketry defence. A very wide outer wet ditch blocked access from the riverside. The roof of the fort, accessed via steps up from the open battery, was altered substantially during the first half of the 20th century to accommodate new guns and other structures. These include emplacements for 5.5-inch and 6-inch guns as well as 12-pdrs, searchlight positions, shelters, an observation post, a fire control building, a machine-gun parapet on the north caponier and a Royal Navy