Accession No

2860


Brief Description

aneroid barometer and mercury-in-glass thermometer, by Edward John Dent, French and English, 1850 (c)


Origin

France; Paris and England; London


Maker

Dent, Edward John [maker and seller] Vidie, Lucien [patentee of the aneroid barometer]


Class

meteorology


Earliest Date

Jan. 1, 1847


Latest Date

Dec. 31, 1853


Inscription Date


Material

metal (brass, silver, steel, mercury); glass


Dimensions

height 128mm; diameter 121mm; thickness 42mm (height 146mm; 27-1-2000)


Special Collection


Provenance

Purchased from Peter Delehar, London, England, 07/1982.


Inscription

[On dial plate:]
Aneroid Barometer
E. J. DENT
Paris.
FAHRENHEIT’S THERMOMETER
2644


Description Notes

Aneroid barometer and mercury in glass thermometer, by Edward Dent, French and English, c. 1850. The Vidie capsule will have been manufactured in Lucien Vidie’s workshop in Paris; Dent will have finished the instrument for sale under license in London [see ‘Notes’ field].

Vidie capsule. Original spring mechanism (interior). Brass case with suspension ring. Glazed silvered dial = pressure 27½-31½ inches, numbered by 1, subdivided to 0.05 (and to 0.025 by dots). Also ‘Stormy’, ‘Much Rain’, ‘Rain’, ‘Change’, ‘Fair’, ‘Set Fair’ and ‘Very Dry’. Blued steel pointer, brass pointer moved by brass knob.

Inscriptions in centre of dial plate read: “Aneroid Barometer, E. J. DENT,
Paris. FAHRENHEIT’S THERMOMETER, 2644”

Curved round-bulb mercury in glass thermometer, divided on dial -14-138oF, numbered by 20, divided to 2o.

Instrument No. 2644.

Condition: good/fair.


References

Allison Ksiazkiewicz; 'Types of barometers'; Explore Whipple Collections online article; Whipple Museum of the History of Science; University of Cambridge: https://www.whipplemuseum.cam.ac.uk/explore-whipple-collections/meteorology/barometers/types-barometer


Events

Description
A barometer measures the pressure of the air around us. The precise pressure of the air depends upon the weather, so a barometer is useful for weather forecasting. It can also be used as an altimeter (see "how to use" a hypsometer).

This aneroid barometer is one of the earliest types, based on the ‘Vidie capsule’ devised by the French engineer Lucian Vidie in 1840. The pressure element is a small corrugated capsule partially evacuated of air. Increasing pressure compresses the capsule; decreasing pressure allows it to expand, the movements being linked to the longer pointer which moves round the dial.

This example was manufactured by the famous clock and watchmaker Edward Dent, using a capsule supplied from Paris. He has added the fine semi-circular mercury thermometer, graduated in degrees Fahrenheit.

The instrument maker Daniel Gabriel Fahrenheit (1686-1736) spent many years perfecting thermometers, and the Fahrenheit scale that is named after him takes 32 as the freezing point and 212 as the boiling point of water.
26/03/2008
Created by: Dr. McConnell on 26/03/2008


FM:43445

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