Voyage of the Scotia 1902-04

William Speirs Bruce, 1867-1921

William S Bruce's barometer

This pocket aneroid barometer and altimeter and its case, now in the collection of the Royal Scottish Geographical Society, previously belonged to William S Bruce, leader of the 1902-1904 Scottish National Antarctic Expedition.

The instrument measures 48mm (1.9 inches) in diameter, and its main scale is graduated from 23 inches (584mm) to 31 inches (787mm) of pressure (mercury column equivalent), with general weather indications of Rain, Change and Fair as on domestic barometers.

It also has an adjustable outer scale from zero feet to 8,000ft (2,440m) of elevation, which can be used to measure the approximate amount of ascent or descent, assuming fairly constant atmospheric pressure at constant height during the observation period. An increase of 1,000ft (305m) in height produces a drop of approximately one inch (2.5cm) in atmospheric pressure, and vice versa.)