A micromanometer is described for the measurement of differential pressures greater than 10−4in. of water with tolerable accuracy. The instrument uses concentric tubes to form the fluid passages and provides for remote indication of the level in the central tube by means of a mirrored float and telescope and scale arrangement. The highest instrument sensitivity obtained by the authors was 3.15×10−5in. of water applied pressure per mm of scale reading, but with suitable refinement in the optical system, it is felt that greater sensitivities are possible.