English: This photo of a U.S. Coast Artillery plotting room probably dates from the 1920s. The semi-circular "table" is a Whistler-Hearn plotting board. The two soldiers closest to the camera (wearing telephone headsets) are the plotting board arm setters, setting the primary and auxiliary arms of the plotting board to azimuths called in by observers at the battery's two base end stations.

The soldier seated at center-rear of the photo is likely operating a range correction board, used to quantify various factors that would affect the range achieved by a shell fired from one of the guns. The soldier seated at the right of the photo (wearing a headset) is likely operating a deflection board, used to quantify factors that would affect the direction (or azimuth) of a shell being fired. Both of these pieces of equipment were used to obtain corrected firing data.

The three windowed pieces of equipment on the rear wall are likely recorders for meteorological data (temperature, wind speed, wind direction, barometric pressure) used to make some of these corrections.

This plotting room appears to have been partially above ground, although many were completely buried for protection from counter fire. The light-colored tube in the rear-center appears to be a speaking tube, which may run up to a Battery Commander's position above the plotting room, or to an observation or gun position.