Original caption: "Fort Cronkhite. AA 1. Three Inch Antiaircraft Battery. This particular battery was located on a bald, rocky dome that had no natural cover of any height. Personnel shelters, mess hall, offices and magazines were all built underground. Simulated rocks cover all passageways above ground between guns and other structures. A framework of wood and chicken wire covered with burlap and and platered with a mixture of casting plaster, cement, sawdust or sisal make a convicincing rock. Coloring matter may be included but spraying the finished rock is more satisfactory. In the photograph, the 'rocks' have not yet been painted."