Coast Artillery fire control system

In the U.S. Army Coast Artillery Corps, the term fire control system was used to refer to the personnel, facilities, technology and procedures that were used to observe designated targets, estimate their positions, calculate firing data for guns directed to hit those targets, and assess the effectiveness of such fire, making corrections where necessary. == Fire control instruments == The Coast Artillery's early fire control instruments supported optical rangefinding and position finding, either horizontal base or vertical base, with both systems usually present for each fort.

Source: Wikipedia — Coast Artillery fire control system (CC BY-SA 4.0)