The other two submarines on the station and motor-boats from the tender _Alert_ cruised about till they found the spot where oil and air-bubbles were coming to the surface. Two tugs then swept the bottom with a two-thousand foot sweep of chains and wire cables, which caught early the next morning on what proved to be the lost submarine, in three hundred feet of water, about a mile and a half outside the entrance to Honolulu Harbor. For twenty-four hours or so the navy department held out the hope that the men on board her were still alive and might be rescued. But there was nothing ready to rescue them with. Three weeks were spent in building the windlasses for an improvised salvage-dock made out of two mud scows. In the meanwhile, a detachment of the department’s most skilled divers were sent out from the Brooklyn Navy Yard. With their aid, strong wire cables were passed under the submarine’s hull. While engaged on this work, one of the divers, Chief Gunner’s Mate Frank Crilley, broke all deep submergence records by descending to a depth of 288 feet. As a result, his lungs were severely injured and he soon afterwards developed pneumonia. The wire ropes chafed through and were replaced by chains. Then the _F-4_ was lifted from the bottom and towed inshore to a depth of fifty feet. Here a heavy storm set in and the lines had to be cast off. Six big cylindrical-shaped pontoons were then built at San Francisco and brought out to Honolulu on the cruiser _Maryland_. Divers passed fresh chains under the _F-4_, the pontoons were sunk on either side of her, and coupled together. Then the water was blown out of the pontoons by compressed-air piped down from above, the _F-4_ was raised to the surface, and towed into dry dock. No decipherable written record was discovered inside her hull, which was filled with sand washed in through a large hole made in the plating by the chafing of the chains. But the story of the disaster was written in the plates and rivets of the vessel herself, and skilfully deduced and reconstructed by a board of inquiry, headed by Rear-Admiral Boush. Their report, which was not made public till October 27, told dramatically how the corroded condition of the lead lining in the battery tanks had let the acid eat away the rivets in the port wall of the forward tank. Salt water thus entered part of the battery, producing chlorin gas, which exploded violently, admitting more water, till the submarine began to sink by the head, in spite of the raising of her diving-rudders. “Automatic blow was tripped, and blow valve on auxiliary tank opened in the endeavor to check downward momentum. Manœuvering with propellers probably took place. The appreciable length of time requisite for air to build up in ballast tanks for the expulsion of sufficient quantities of water resulted in the vessel reaching crushing depth.