A 10-inch coast artillery gun and a "disappearing" mount emplaced in Battery Grubbs on Fort Mills (World War II, Corregidor).  This type of mount is designed to employ a hinged counterweight to raise the gun for firing above the parapet of the gun emplacement and then to recoil back and down under cover for reloading.  Fort Mills had 23 batteries with 56 coast artillery guns and mortars, of which six batteries were equipped with disappearing mounts.  In addition, there were 13 anti-aircraft batteries with 76 guns. Click here to enlarge.