Figure 4.

Schematic cross-section of manometer cellar beneath the NBS/NIST gas thermometer laboratory. The manometer is mounted upon a concrete pier that was made separate from the laboratory building to minimize vibration. A dedicated air conditioning system, vigorous air circulation, multi-point air-temperature sensing, and carefully designed controllers maintain millikelvin stability in the cellar temperature. The anteroom is used to temper and store a collection of end standard gage blocks and as a toolroom. (Reprinted from reference [5].)