What is a Barometer?
The barometer is an instrument for the measurement of the weight of air. The simple barometer consists of a glass tube of circular section sealed at its upper end which stands in a cistern of mercury in such a way that its lower end is well immersed. The most common alternative to the cistern-tube arrangement is the use of a bent or ‘Siphon’ tube in which air pressure acts on the surface of the mercury in the short limb.
Barometer Features
When and Where Were Barometers Made?
The invention of the mercury barometer is generally credited to an Italian scientist Evangeslista Torricelli (1608-1647) who was a pupil of Galileo (1564-1642). His famous experiment with a mercury tube known as the ‘Torricelli Experiment’ was conducted c.1643.
The commercial manufacture of domestic mercury barometers began in England c.1680. It soon became fashionable among upper-class households to own one of these useful instruments. By the late 1700’s, the barometer was becoming a widely owned piece of furniture and during the next one hundred and fifty years large numbers were made.
Domestic barometers usually have a scale representing inches of mercury from 26 to 31 inches. In addition to these scales, domestic instruments are engraved on the register plate with familiar weather indications: ‘very dry’, ‘dry’, ‘settled fair’, ‘fair’, ‘changeable’, ‘rain’, ‘much rain’, ‘stormy’ or a variation of these. These weather indications are more for pleasing aesthetics and are not reliable guides to the weather; it is the movement of the mercury, not its absolute height, which predicts alterations to the weather.
There are many different types of barometer, from the earliest siphon tube examples to angle tube, straight tube or stick barometers, from wheel (banjo) barometers to aneroid barometers (meaning an instrument to measure pressure which does not contain liquid).
Barometers for Sale
A large number of barometers have undergone a great deal of alteration over the years and as such prices of barometers are influenced by condition, originality and authenticity. The best advice which applies to buying any type of barometer is to be vigilant and go to a reputable experienced dealer.
Olde Time Barometers for Sale
We supply a wide range of Barometers here at Olde Time. We have a huge choice with each barometer more unique the next.
Barometer Maintenance and Repair
In order to keep your barometer looking as good as new, here are some maintenance guidelines:
• Keep the barometer out of direct sunlight and avoid excessive hot or cold temperatures.
• If you have to move a mercury barometer, make sure that you lift it from the wall very slowly and be sure to always keep the barometer upright.
• Should you have to walk any distance with the barometer, first tip the barometer to 45 degrees, with the top as the highest point, and allow the mercury to reach the top of the tube (a gentle clunk should be heard). Then, proceed to walk slowly, always remembering to keep the barometer at 45 degrees. When returning the barometer to the upright position, make sure that you tilt the barometer slowly upright. By following these precautions, you will avoid spillage of mercury and damage to the delicate glass tube.
• A weekly feather dusting or cleaning of the casework with a mild natural beeswax or crystalline wax will help to remove fingerprints and a build-up of dust from the case. Crystalline wax is a mixture of refined waxes, blended to a formula used by the British Museum to revive and protect valuable furniture, leather, paintings, metals, marble, etc. It is available to buy from Olde Time.
• Never use household cleaners or abrasives of any kind to clean any part of the barometer.
An antique barometer should only be cleaned and overhauled by a specialist restorer. Never attempt to clean or repair an antique barometer yourself.
