A compact, null-reading, tilting U-tube micromanometer with a rigid liquid container

A description is given of the design and performance of a manometer comprising an inclined sight tube and a movable reservoir, in which the need for a flexible connecting tube is avoided by tilting the whole liquid container about an axis nearly coincident with the centre line of the sight tube, with simple mechanical compensation for `cosine error'. The combined scatter in a calibration against a Chattock gauge was generally within ±0.0001 in. of liquid (±0.2 mtorr), the time lag and zero drift are much less than those of a Chattock gauge, the linear dimensions are about half those of a Chattock gauge of similar range, and the instrument can withstand large overloads with no change of zero reading.