Plate from 18th century encyclopedia showing illustrations of various meteorological and pneumatic instruments. A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. Pressure tendency can forecast short term changes in the weather. Numerous measurements of air pressure are used within surface weather analysis to help find surface troughs, high pressure systems, and frontal boundaries. A eudiometer is a laboratory device that measures the change in volume of a gas mixture following a physical or chemical change. An anemometer is a device used for measuring wind speed, and is a common weather station instrument. Also shown is a laborartory air pump.