Sympiesometer

A sympiesometer is a compact and lightweight type of barometer that was widely used on ships in the 19th century.

One is a traditional mercury thermometer that is needed to calculate the expansion or contraction of the fluid in the barometer proper.

The other is the barometer, consisting of a J-shaped tube open at the lower end and closed at the top, with small reservoirs at both ends of the tube.

The basic idea is similar to the common weather glass that had been in use for some time, but the use of highly compressible hydrogen in a long, thin tube allowed much more accurate measurements, as changes in pressure resulted in much more movement of the liquid.

The basic concept was initially demonstrated by Robert Hooke, which he referred to as the Otheometer.

Sympiesometer inscribed at bottom Improved sympiesometer and at top A R Easton , 53 Marischal Street, Aberdeen. Owned by descendants of the Aberdeen shipbuilding Hall family.