Now, however, a third turned up and Christie's offered it for sale in their October 9 Travel, Science and Natural History sale at South Kensington.
A household name during his lifetime and even more so in the centuries since, Daniel Gabriel Fahrenheit was a physicist, engineer, and glass blower, best known for the temperature scale bearing his name which is still used today in many countries, as well as for his invention of both the alcohol and mercury thermometers.
At 4½in (11.5cm) long, the brass thermometer, shown here, with replacement tube was slightly smaller than the Leiden examples and was signed Fahrenheit and Am∫t for Amsterdam, where he lectured in chemistry from 1718.
Originally, the recently rediscovered thermometer would have been used for scientific experiments to give accurate observations around ambient room temperature.
The example at Christie's came from a private collection put together in the 1970s and carried an estimate of £70,000-100,00,.
James Hyslop, scientific specialist at Christie's, said: "Inscribed on the back by Fahrenheit himself, this is an exceptional piece which has no precedent, and which I expect to cause a real buzz with connoisseurs and institutions on every continent around the globe."
In setting the estimate, Mr Hyslop took as his guide the c.1690 Dutch silver microscope by Antoni van Leeuwenhoek, the greatest pioneering microscopist of the 17th century, which sold at South Kensington on April 8, 2009, taking £260,000.
However, the mercury thermometer did not reach these kind of levels and, as it was, it did not get to its low estimate but was allowed to sell at £55,000.
The buyer's premium was 25/20/12%
