were much more economical to construct than the previous practice of constructing the standing heavy walls and fortified casemates of a more traditional gun emplacement. The entire battery could be hidden from view in place when not in use, unlike a traditional fort, enabling ambuscade fire. Higher rate of repetitive fire over non-disappearing types. Less fatigue for the gun crew. Disadvantages The disappearing gun had several drawbacks as well: Some British carriage designs restricted maximum elevation to under 20 degrees and thus lacked the necessary range to match newer naval guns entering service during the early part of the 20th century. (Buffington-Crozier carriages, at their final development, could manage 30 degrees on a 16-inch gun.) The additional elevation gained by mounting the same gun on a later non-disappearing carriage increased its range. The time taken for the gun to swing up and down and be reloaded slowed the rate of fire of some designs. Surviving records indicate a rate of fire of one round per one to two minutes for a British eight-inch (20 cm) gun, significantly slower than less complicated guns. (By contrast, the Buffington-Crozier 16-inch mount could manage one round per minute; the barbette mount was only 20 percent faster, and was slower at some elevations.) The improvement in the speed of warships demanded an increased rate of firing. The disappearing gun was at a disadvantage compared with a gun that stayed in position as one could not aim or reposition a disappearing gun while it was in the lowered position. The gunner still had to climb atop the weapon via an elevated platform to sight and lay the weapon after it was returned to firing position, or receive fire control information (range and bearing) transmitted from a remote location. Their relative size and complexity also made them expensive compared with non-disappearing mounts, In 1918, the 12" DC gun cost $102,000, the barbette mounted gun $92,000. This was more than made up, for some designs, by the reduced cost of protection. From the above reference, the cost of a 16" DC emplacement was $605,000, while a turreted gun's proportional cost was $2,050,000. Other applications Gun lift battery One very uncommon and even more complex type of disappearing gun was Battery Potter at Fort Hancock in the Coast Defenses of Sandy Hook, New Jersey. This and a number of 12-inch barbette emplacements were constructed due to the inability of