the arms in place of the usual manipulators. It carried seven 90-cubic foot high pressure cylinders to provide breathing gas and control buoyancy. The ballast compartment covered the gas cylinders. For communication, the suit used hydrophones. The modern suit Peress' Tritonia Although various atmospheric suits had been developed during the Victorian era, none of these suits had been able to overcome the basic design problem of constructing a joint which would remain flexible and watertight at depth without seizing up under pressure. Pioneering British diving engineer, Joseph Salim Peress, invented the first truly usable atmospheric diving suit, the Tritonia, in 1932 and was later involved in the construction of the famous JIM suit. Having a natural talent for engineering design, he challenged himself to construct an ADS that would keep divers dry and at atmospheric pressure, even at great depth. In 1918, Peress began working for WG Tarrant at Byfleet, United Kingdom, where he was given the space and tools to develop his ideas about constructing an ADS. His first attempt was an immensely complex prototype machined from solid stainless steel. In 1923, Peress was asked to design a suit for salvage work on the wreck of SS Egypt which had sunk in the English Channel. He declined, on the grounds that his prototype suit was too heavy for a diver to handle easily, but was encouraged by the request to begin work on a new suit using lighter materials. By 1929 he believed he had solved the weight problem, by using cast magnesium instead of steel, and had also managed to improve the design of the suit's joints by using a trapped cushion of oil to keep the surfaces moving smoothly. The oil, which was virtually non-compressible and readily displaceable, would allow the limb joints to move freely at depths of , where the pressure was . Peress claimed that the Tritonia suit could function at although this was never proven. In 1930, Peress revealed the Tritonia suit. By May it had completed trials and was publicly demonstrated in a tank at Byfleet. In September Peress' assistant Jim Jarret dived in the suit to a depth of in Loch Ness. The suit performed perfectly, the joints proving resistant to pressure and moving freely even at depth. The suit was offered to the Royal Navy which turned it down, stating that Navy divers never needed to descend below . In