Description

Unusual Wedgwood-type pyrometer or thermometer signed “Pixii père et fils Rue de Grenelle St Germain 18 Paris”. The instrument measures 172x64mm and it made in brass/bronze.

“Thanks to its simplicity, the pyrometer designed by Josiah Wedgwood c. 1785 enjoyed immense success in the following decades. The need to introduce physics-based measurement systems into chemistry led Wedgwood to take an instrument originally developed by experimental physicists and adapt it to the requirements of the chemical laboratory. The instrument relies on the property of clay to shrink in proportion to the rise in temperature. It was used to measure the temperature of chemical ovens. 

The pyrometer […consists] in a rectangular brass plate to which three rulers are fastened with screws. 

The rulers are separated by two grooves narrowing at one end and designed so that, if they were placed one after the other, the second would form the extension of the first. The thermometric scale, engraved on both external sides of the two grooves, carries a subdivision into single degrees from 0 to 240° Fahrenheit (i.e., from -17.7° to 115.5° Celsius).”

https://catalogue.museogalileo.it/object/WedgwoodsPyrometer.html

Rare signature “Pixii père et fils”.