Machine Design

Backtalk 11/08/2012

300-year-old thermometer resurfaces Daniel Gabriel Fahrenheit had a strong interest in natural science and a fascination with new inventions. In 1714, he invented the mercury thermometer. It divided the freezing and boiling points of water into 180°.

The top of the 300-year-old brass instrument, thought to have been lost to history, resurfaced when it went up for sale at Christie’s in London. In a private collection for more than 40 years, it is one of only three known examples in existence today. The 4½-in.-tall instrument sold for more than £67,000 (~$107,386,00 in U.S. dollars). The scale on the thermometer is marked from 0 to 132°F and is so small that the numbers had to be written on both sides of the mercury tube.

James Hyslop, speaking on behalf of Christie’s, said, “Until now, only two originals were thought to exist. And these are both in the Boerhaave Museum in the Netherlands. So to have this one emerge is very exciting. It is impossible to pinpoint exactly when it was made, but one in the museum is dated 1718, and this was probably made between 1715 and 1730.

“He made barometers with thermometers on the side, but this was one was a special scientific thermometer. The mercury tube is not the original and has been replaced, but it was clearly designed so the tubes could be taken out. It was a thermometer for scientific purposes, perhaps for measuring the temperature of liquids.”

Fahrenheit’s other great invention was the Fahrenheit scale. It was the first widely used temperature scale. 32°F was the freezing point of water and 212°F was the boiling point of water, set by Fahrenheit himself. 0°F was based on the temperature of an equal mixture of water, ice, and salt. Fahrenheit based his scale on the temperature of the human body.

Fahrenheit was born 1686 in Danzig in the Polish-Lithuanian Commonwealth. He began training as a chemist, and his personal interest in natural science led to his studies and experimentation in the field. He later moved to the Dutch Republic, where he spent the rest of his life. He died in The Hague in 1736.

The Celsius scale was invented in 1742 by Swedish astronomer Anders Celsius. The scale has 100° between the freezing point (0°C) and boiling point (100°C) of pure water at sea-level air pressure. The term ‘Celsius’ was adopted in 1948 by an international conference on weights and measurements. The scale’s simplicity led to it superseding the Fahrenheit as the universal temperature scale.

© 2012 Penton Media, Inc.

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