Home >> Collecting >> Antiques

18th Century English Barometers

A barometer is an instrument used to measure atmospheric pressure. Barometers have applications in meteorology, or weather forecasting, as well as in other fields. Many English barometers of the 18th century employed mercury, because the liquid metal is very responsive to atmospheric changes. Variations in atmospheric pressure cause the mercury to rise or fall inside a fine-bore glass tube at a constant rate that can be calibrated.

History
- Barometers first became available for domestic use in the early 18th century, according to antique barometer dealer Alan Walker. Stick barometers and, later, wheel barometers were used by farmers and wealthy landowners to give them a picture of prevailing weather systems so they could manage their crops and kitchen gardens more effectively. Many of the famous makers, such as Worthington &Allan, were based in London. However, there were also makers in Dumfries, such as Robert McPherson, and Dublin, such as Samuel Yeates.
Stick Barometers
- Until about 1775, nearly all barometers were of the stick type, usually using hardwood, such as mahogany and ebony, for the main structure. As the name suggests, a stick barometer is slender and cylindrical in shape, often with a flat back for wall mounting. Typically, the upper section has a scale in inches and indications such as "Very Dry," "Set Fair," "Rain" and "Stormy" forming the silvered brass register plate. The mercury tube is visible centrally on the plate, sometimes terminating in a hemispherical cistern cover.
Wheel Barometers
- Wheel barometers began to appear in the late 18th century. They might be more accurately called clock barometers, since they have a circular, clock-like face in their "bellies." The register plate is circular and has one or more hands to indicate outlook and air pressure. Above this, a symmetrically curving wooden pediment is usually home to a Fahrenheit thermometer for temperature readings. As with stick barometers, the wood used for wheel barometers is usually mahogany or another hardwood of similar quality.
Others
- Marine and scientific barometers of the period were used at sea and for meteorological and other kinds of experiments. Specialized barometers referred to as balloonists' barometers were produced for use in hot air balloons. Mountain barometers were used by land surveyors throughout the world. These were heavy instruments at first, according to barometer enthusiast and author Anita McConnell, and often needed to be carried to great heights before giving useful readings.

Antiques