Accession No

2594

Brief Description

bimetallic thermometer, by Holtzmann, Austrian, 1820 (c)

Origin

Austria; Vienna

Maker

Holtzmann

Class

meteorology; thermometry

Earliest Date

1820

Latest Date

1820

Inscription Date

Material

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

Dimensions

length 66mm; breadth 48mm; thickness 13mm

Special Collection

Provenance

Purchased from P. Delehar, London, England, 05/1980.

Inscription

‘Holtzmann
WIEN’

Description Notes

Bimetallic thermometer, Holtzmann, 1820 (c).

Circular-cased, bimetallic thermometer. Silver (?) case, fully glazed front and reverse, domed on front. Circular brass plate with central aperture and crossbar. Brass and steel bimetallic strip moving rack on brass arm via blued steel spring. Pinion moves against spiral spring. Blued steel double index hand and screws. White enamel dial with two scales: ‘Reaumur’ from 30-0-40 by 10 too 1˚ and ‘Fahrenheit’ from 38-0-122 by 10 to 1˚. Silver (?) suspension ring.

Condition: good.

References

Events

Description
The element of this bimetallic thermometer can be seen behind the dial. It consists of a coil of steel bonded to brass, the two metals differing in their expansion when heated and thus coiling more or less tightly, according to changes in temperature. One end of the coil is fixed, the other is linked to the double-ended pointer, which moves round a dial graduated in both degrees Fahrenheit and degrees Réaumur.

This example was made by Holtzmann in Vienna, around 1820.

The Fahrenheit scale takes 32 as the freezing point and 212 as the boiling point of water, and is named after the instrument maker Daniel Gabriel Fahrenheit (1686-1736), who spent many years perfecting thermometers. The French scientist Réné-Antoine Ferchault de Réaumur (1683-1757) also experimented with thermometer scales. After his death the Réaumur scale was generally taken as 0 for freezing and 80 for the boiling point of water.

26/03/2008
Created by: Dr. Anita McConnell on 26/03/2008

FM:42188