Base end station
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Base end stations were used by the United States Army Coast Artillery Corps as part of fire control systems for locating the positions of attacking ships and controlling the firing of seacoast guns, m
A Depression Position Finder (on the left) and an Azimuth Scope at Fort Standish MA
7-Story FCT at Point Allerton MA
Rear view of brick 2-story FCT from 1904 at Fort Andrews in Boston Harbor.
8-Story FCTs Nahant MA
Plotting board
Videos
A plotting board was a mechanical device used by the U.S. Army Coast Artillery Corps as part of their fire control system to track the observed course of a target, project its future position, and der
Base end station
…from either station could be calculated through triangulation. If the target's bearing from each station was sent to a plotting room and input to a plotting board, the position of the target could be estimated and firing coordinates for a gun battery could be calculated. Some base end stations were located in…
Photo of plotting board table top
Relation between plotting board and the actual geography of the harbor
Plotting room, with Whistler-Hearn board
A series of observed positions (blue circles) established the likely track of the target. Using the plotting board, the set forward point was determined, based upon the target's observed course and speed and an assumption about when the gun was to be fired.