the early versions of the Buffington-Crozier carriage to accommodate a 12-inch gun. Built in 1892, the battery covered the approaches to New York harbor. Instead of using recoil from the gun to lower the weapon, two 12-inch barbette carriages were placed on individual hydraulic elevators that would raise the 110-ton carriage and gun 14 feet to enable it fire over a parapet wall. After firing, the gun was lowered for reloading using hydraulic ramrods and a shell hoist. While the operation of the battery was slow, taking 3 minutes per shot, its design allowed a 360° field of fire. Since its design was not further pursued, Battery Potter was disarmed in 1907. Battery Potter required much machinery to operate the gun lifts, including boilers, steam-powered hydraulic pumps, and two accumulators. Due to the inability to generate steam quickly, Battery Potter's boilers were run nonstop during its 14-year life, at significant cost. After the proving of the Buffington-Crozier carriage for 12-inch guns, the United States Army abandoned plans to build several additional gun lift batteries. Naval artillery The concept was also attempted for conversion to a naval use. HMS Temeraire was completed in 1877 with two disappearing guns ( muzzle-loading rifles on Moncrieff-type carriages) sinking down into barbette structures (basically circular metal protective walls over which the gun fired when elevated). This was to combine the ability of the early pivot guns to swivel with the protection of more classical fixed naval guns. A similar design was later used in Russia for the first ship of the Ekaterina II-class battleships and also used in the monitor Vitse-admiral Popov. It has been suggested that both the harsh saltwater environment and the constant swaying and rolling of a ship at sea caused problems for the complex mechanism. If the mechanism seemed too temperamental for the open sea, it was not true for rivers and harbors. Armstrong and Mitchell's 1867 HMS Staunch, a gunboat described as a "floating gun carriage", used a single Armstrong rifled muzzle loader on a lowering platform with next to no armor. It was a resounding commercial success; there were 21 direct copies, and another six near-sisters, plus six near-copies (see List of gunboat and gunvessel classes of the Royal Navy). Known as the "flatiron" gunboats, these vessels had a single large gun kept behind hinged shields, rather than a complex disappearing mount. The simplified mounts were intended as much