page_title: Submarine mines in United States harbor defense
section_title: Maintenance
hierarchical_section_title: Submarine mines in United States harbor defense / Maintenance
caption_attribution_description: English: This plan of the mine-handling facilities at Fort Strong comes from the U.S. Army Engineers' Reports of Completed Works (RCWs) for Fort Strong, Long Island, Boston Harbor, and is indicated as being updated through October, 1921. The notes in red have been added for use on Wikipedia, with building dimensions obtained from other RCWs. The coordinates of the center of the mine casemate were observed from Google Maps and are included to index the location of the map.
context_page_description: The modern era of defending American harbors with controlled mines or submarine mines began in the post-Civil War period, and was a major part of US harbor defenses from circa 1900 to 1947.
context_section_description: Extensive on-shore facilities, as well as a small fleet of mine-planting boats, supported each mine casemate. For Fort Strong in Boston Harbor, these facilities are illustrated in the map shown at right.
  The mine wharf was where mine planters tied up to load or unload their cargo of mines and connecting cable. This wharf was equipped with a heavy lifting crane. From the wharf, returning mines were carried by the mine tramway (a rail system) to the torpedo storehouse ("torpedo" was an old alternate term for "mine"). This storehouse was the largest building in the mine complex, and was used to store the mines, on large racks, when they had been pulled from the water for testing, repair, or storage (for example, when peace had broken out). Loaded mines were also stored in the underground magazines of those gun batteries which were disarmed about 1925, at the top of the bluff on the northern end of the fort. These magazines were reached by following the tramway off the map towards the lower left, where it ran up a gradual slope past the "reservoir" (water tower).
  Another branch of the tramway lead to the loading room, where the TNT charges for the mines were loaded into or unloaded from the mines. A very small TNT storehouse was immediately adjacent to the loading room. Only one box of TNT – 100 lb (45 kg), or half of the load for an average mine – was supposed to be taken from this storehouse at a time for loading.
  Another branch of the tramway track lead to the cable tanks, large concrete tanks filled with seawater pumped from the harbor and used for insulation and conductivity testing of the many miles of electrical cable that were used for mine operations. The torpedo storehouse had its own smaller tanks that were used for submergence testing of the mine casings and their fuzes, which were inserted into the casings through watertight plugs.
  The mine casemate (pictured in the photo above and in the plan drawing) is also shown on the map. Its coordinates (42.329388°N 70.958288°W) indicate the approximate center of the structure. All traces of the other mine facilities were destroyed by the City of Boston in the 1990s during the redevelopment of the northern end of the fort and its parade ground for use as a summer camp for city children.
caption: A 1921 map of the mine-handling facilities at Fort Strong, Long Island, Boston Harbor.
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