Accession No
6649
Brief Description
Wedgwood pyrometer, by Dumotiez, French, late 18th century
Origin
France; Paris
Maker
Dumotiez [maker] Wedgwood [designer]
Class
thermometry; physics
Earliest Date
1782
Latest Date
1820
Inscription Date
Material
wood; metal (brass)
Dimensions
190mm (length) x 85mm (width) x 25mm (depth)
Special Collection
Provenance
Purchased from Librairie Alain Brieux, 48 Rue Jacob, Paris, 75006, France on 20/12/2017.
Inscription
Dumotiez a Paris
Description Notes
Wedgewood pyrometer, by Dumotiez, French, late 18th century
Brass Wedgewood pyrometer in wooden box with sliding lid. Thick brass slab with two indentations/pockets for the insertion of pieces of ceramic/porcelain. Both indents, narrower at one end than the other, have scales along the bottom as per the Wedgewood scale. The bottommost scale is numbered 0o to 120o, from right to left, at 10o intervals (with further 1o and 5o intervals, unnumbered, in between). The top scale is numbered 120o - 240o from right to left with the same intervals as the scale below.
Pyrometer sits within wooden box and does not seem to be removable (although it is not clear whether it is purposefully fixed within the box). Box has sliding lid.
In good condition, complete.
References
Events
Description
The Wedgwood Pyrometer was invented by Josiah Wedgwood in 1782. Wedgwood, founder of the eponymous English pottery company, wanted to measure temperatures above 580.8 °C. Previously, temperatures above this could not have been measured as this is the temperature at which mercury boils. By accurately measuring these temperatures Wedgwood would have been able to improve this kilning of his pottery, which remained an imprecise skill in the 1700s. This device worked by measuring the shrinkage of clay following kilning and assuming this corresponded linearly to the temperature of the kiln. This style of pyrometer, as well as the Wedgwood scale invented to convert shrinkage into an equivalent temperature, was later found to be inaccurate.
19/03/2018
Created by: Rosanna Evans on 19/03/2018
FM:47266
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