English: This annotated photo is from "The Service of Coast Artillery," by Frank T. Hines and Franklin W. Ward, Goodenough & Woglom Co., New York, 1910, following p. 112.

It shows the 12-inch breech loading rifle, Model 1900 on a 1901 disappearing carriage. This 12-inch gun was one of the heaviest weapons that was widely employed in the U.S. Coast Artillery Corps. A companion weapon, the Model 1895 on a Model 1897 disappearing carriage was slightly lighter weight, but worked similarly.

This image shows the gun with its barrel raised above the top of the parapet, ready to fire. After firing, the recoil from the blast moved the muzzle of the gun backwards and and downward, bringing the breech down near the loading platform, where the gun's crew could easily swab it out and load another shell. While in this retracted position, the gun was protected by the parapet and could not be seen from seaward.

A deep pit beneath the gun held a sort of platform that was piled high with lead weights that together made up a counterweight. The recoil of the gun raised this counterweight. When a "tripping lever" was thrown, the counterweight fell, raising the gun into firing position. If the gun needed to be retracted without being fired, this was accomplished by the gun crew turning cranks on either side of the carriage and manually retracting it. The round counterweight pits for these guns (surrounded by semicircular steps that rise up to the loading platform) are visible today at many sites in the U.S. from which the guns have been removed.