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.