Harbor Mine (Torpedo) Complex

The Harbor Mine or Torpedo Complex was constructed from 1908 to 1911 as part of a comprehensive harbor defense system for Narragansett Bay. The two-story concrete structure served as a mine storage warehouse where parts required for assembling mines, also called torpedoes, were stored. This building and two adjacent one-story structures had overhead rail cranes that lifted and moved heavy parts and subassemblies to tram carts, which carried them along a narrow-gauge rail system for assembly, insertion of explosives, and testing in nearby buildings before the mines were anchored in the bay. A one-story Cable Tank Building contained four oblong concrete water tanks where reels of insulated submarine cables were immersed and preserved until needed. These cables connected the mines to a small onshore facility called a mine casemate, located to the rear of the warehouse, from which mines in the bay could be detonated. Each of the four tanks could hold 20,000 feet of reeled cable. Components and cables were moved to the Loading Room at the western end of the complex, where the mines were assembled and tested after explosive charges were added. An overhead crane lowered the mines into circular pits in the floor so mechanics could prepare them for movement to the pier by narrow-gauge rail carts, and from there to designated areas of the bay by an Army Mine Planter. Clusters of 19 mines were then lowered into the bay and connected to a land-based mine casemate, from which specific groupings could be detonated on command.

Jamestown, Rhode Island · United States