joint to allow equalization of pressure. The suit was designed to have four joints in each arm and leg, and one joint in each thumb, for a total of eighteen. Four viewing ports and a chest-mounted lamp were intended to assist underwater vision. Unfortunately there is no evidence that Bowdoin's suit was ever built, or that it would have worked if it had been. Atmospheric diving suits built by German firm Neufeldt and Kuhnke were used during the salvage of gold and silver bullion from the wreck of the British ship SS Egypt, an 8,000 ton P&O liner that sank in May 1922. The suit was relegated to duties as an observation chamber at the wreck's depth of , and was successfully used to direct mechanical grabs which opened up the bullion storage. In 1917, Benjamin F. Leavitt of Traverse City, Michigan, dived on the SS Pewabic which sank to a depth of in Lake Huron in 1865, salvaging 350 tons of copper ore. In 1923, he went on to salvage the wreck of the British schooner Cape Horn which lay in of water off Pichidangui, Chile, salvaging $600,000 worth of copper. Leavitt's suit was of his own design and construction. The most innovative aspect of Leavitt's suit was the fact that it was completely self-contained and needed no umbilical, the breathing mixture being supplied from a tank mounted on the back of the suit. The breathing apparatus incorporated a scrubber and an oxygen regulator and could last for up to a full hour. In 1924 the Reichsmarine tested the second generation of the Neufeldt and Kuhnke suit to , but limb movement was very difficult and the joints were judged not to be fail-safe, in that if they were to fail, there was a possibility that the suit's integrity would be violated. However, these suits were used by the Germans as armored divers during World War II and were later taken by the Western Allies after the war. In 1952, Alfred A. Mikalow constructed an ADS employing ball and socket joints, specifically for the purpose of locating and salvaging sunken treasure. The suit was reportedly capable of diving to depths of and was used successfully to dive on the sunken vessel SS City of Rio de Janeiro in of water near Fort Point, San Francisco. Mikalow's suit had various interchangeable instruments which could be mounted on the end of