Abstract
An apparatus which is capable to measure a small pressure and its changess in the circumstances of low temperature and pressure was devised, The main part consists of a capsule which has a thin plate of mica (for the lack of hysteresis and the small temperature coefficient of elasticity) and is contained in a glass case in order to isolate the capsule from the surrounding. The mica plate consists of one plate of electric condenser, the other is a fixed metallic plate over the mica plate. A pressure difference to be measured is introduced between mica capsule and glass case. The deflection of mica due to pressure is transferred to the change of electric capacity, and then measured by the electric apparatus with sensitive devices of vacuum tubes (oscillator, detector and amplifier.)
The main difficulties of measurment consists in the construction of mica capsule and the stable adjustment of electric parts. The maximuz sensitivity obtained is 12.5 volt/cm.
