Disappearing 14-inch Rifle.  In 1941, it was 25 years old and ready for action.  The 14-inch Rifle was mounted on a disappearing carriage which was developed  at the end of the 19th century.  The theory was that the shore-based rifle could crouch behind 20 feet of concrete plus another 20 to 30 feet of hard packed earth in front of the concrete, rise to fire, return behind the barrier and thus be invisible to hostile invading fleets.  The 14-inch rifles had a range of 24,000 yards (13.64 miles).  14-inch disappearing rifles were in position at Fort Amador's (then Fort Grant) Battery Burnside on Noas Island (2 each), Battery Warren on top of Flamenco Island (2 each), Fort Sherman's Battery Stanley (1each), Battery Mower (1 each), Fort Randolph's Battery Webb (2 each).  It looks like the above photo was probably taken at Battery Warren on top of Flamenco Island.  Battery Warren had been built at the 250 foot elevation contour.  Underneath each gun were the powder magazines and projectile storage.  From this level an elevator descended 250 feet to a shoreline siding in a tunnel.