The Rise and Fall of the Mercury Barometer

By: Judy Penz Sheluk

As seen in The Antique Shoppe Newspaper, January 2008

 In 1648, another physicist, Rend Descartes, and mathematician Blaise Pascal of France added a paper scale to ‘Torricelli’s tube’ for the study and measurement of air pressure, essentially creating the first barometer. It was Pascal’s theory that air pressure decreased with altitude above sea level, and enlisted his brother-in-law, Florin Perier, to carry a barometer to the peak of the Puy-de-Dome Mountain. Pascal’s hypothesis proved correct; Perier observed a diminishing mercury column height as he climbed to the mountain’s summit.

 Not much more happened until 1660, when correlations between variations in atmospheric pressure and changes in the weather were first observed by two Englishmen, Robert Boyle and Robert Hooke. Their experiments led to the development of a practical barometer, and by 1670, the leading clock and instrument makers in England began to construct barometers for scientific and domestic use.

 “The English had the lead in the manufacture of barometers well in hand by the time Charles 11 left the throne in 1685, and they dominated world production for the next two centuries,” said Charles Probst, a dealer and collector of antique barometers since 1985, and co-owner of Charles Edwin, Incorporated [www.charles-edwin.com].

 “The period from 1680-1800 is the most desirable in the development of the barometer,” said Probst. “Early clientele were wealthy, and makers were eager to please with fine cabinetry and metalwork. Unfortunately, many barometer cases suffer when relocated to America. The English have a notoriously wet atmosphere, and wood used to 100 damp years can fall apart or crack when exposed to the harsh realities of central heating. Consequently, many early examples have had some necessary restoration. This is perfectly acceptable, providing the work has been done by a professional antique furniture restorer.”

 The earliest barometers were made in a stick form, and are not known for their accurate weather forecasting ability. “There is no physical alteration you can make to an antique stick barometer to correct its reading,” said Jill Probst. “They are all made to operate at sea level, period. At elevations up to 1,000 feet, there is an altitude correction table which can help in the reading of the stick barometer. At elevations above about 1,000 feet, the common household variety just won't work. As specialists in the field, Charles and I recommend you enjoy them for the lovely antique they are, and rely on the local news for your weather forecasts.”

 The shape of barometers changed during the last quarter of the 18th century with an influx of Italian instrument makers to England. These makers produced a variety of styles in great quantity. Banjo barometers, also referred to as wheel or dial, were first made around 1790 and soon became the style of choice. As time evolved, additions to the case included a hygrometer, (an instrument which measures humidity), thermometer, a convex ‘butler’s’ mirror and level.

 Most English barometers also followed the furniture trends of the time, and these changes are reflected in the type of wood used. Until 1720, walnut was the wood of choice; later examples included rosewood and mahogany, with ebony and satinwood trim, and in-laid mother-of-pearl or shell. Styles were reflective of the times, influenced in the manner of Chippendale, Hepplewhite, Sheraton and Victorian furnishings. Until 1840, register plates were usually made of brass; with the advent of the Victorian period, the use of ivory and bone was prevalent.

 Barometers were also made for use at sea. “These barometers began to appear in quantity during the last days of George 111’s reign,” said Charles Probst. “By the 1820s, they were being made both for the Royal Navy and merchants. Many marine barometers are marked with seaport origins, where major ships’ outfitters practiced.”

 In America, barometers were not produced in quantity until 1840. Most are machine-made stick forms, similar to the mantle and shelf clocks made in the same era. “These can often be found for a few hundred dollars, although restoration costs frequently exceed purchase prices due to crude assembly methods and economies in the original production,” said Probst.

 Several other countries produced mercury barometers, including Italy, Russia, Germany, France, Holland and Denmark. Since barometers are considered a scientific instrument, the country of origin must be recorded on the barometer, and often includes the maker’s name and address. Unless specifically made for export, the weather indicators will also be in the language of the country for which it is made.

 Perhaps the most common complaint among barometer owners is that the barometer shows ‘Fair’ while a torrential downpour is happening outdoors. “That’s because a barometer is a device for predicting weather changes,” explained Jill. “It was never meant to provide an instant readout of current conditions. A change in the level of the mercury indicates the passage of a high or low pressure front over your area, and a corresponding change in weather. Falling atmospheric pressure precedes stormy or unsettled conditions, and a rise indicates the approach of settled weather.”

 Although still made today, the mercury barometer was largely replaced by the invention of the aneroid barometer in 1843, which measures air pressure using an evacuated sealed chamber. Unlike the delicate mercury barometer, aneroid barometers require no special precautions when moved, and are generally accurate when properly adjusted.

Sidebar: Dealing with Mercury Barometers  97 words

 Mercury barometers should never be moved suddenly because air bubbles in the column upset the calibration of the instrument. In the case of wheel barometers, there is an additional danger of mercury overflowing from the open end of the tube. Mercury is a poisonous metal which can be absorbed through the skin.

 Mercury is considered a hazardous material, and cannot be transported by airplane. If you are caught with a mercury barometer aboard a flight, you will be detained, and the possibility exists that you could lose the barometer and/or be heavily fined.

Photo listing: All photos are courtesy of Charles Edwin, Incorporated [www.charles-edwin.com]. Prices are for impeccably restored, substantially original barometers in working order.

Photos 1790 to 1850 illustrate the evolution of case design in banjo barometers, also referred to as dial or wheel. Although barometers were invented in the 1640s, early versions were the stick type. The banjo-style barometer saw its first popularity near the end of the 18th century, and production of these soon outnumbered the earlier stick versions.

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