SignedSigned: BREGUET
Inscribedan oval sticker on base is labeled: 8-9-33.
FunctionThis instrument senses atmospheric temperature via the expansion/contraction of a metal helix.
The metal helix expands as the temperature increases, and starts to unwind. As a result, the transverse needle in the bottom points at a different angle.
Since the scale is in angle degrees, the instrument would need to be callibrated with known temperatures before its use.
It might be used to register variables other than temperature, such as humidity, simply by using a material for the helix that expands and contracts in response to that variable.
Historical AttributesAbraham Louis Breguet invented this sensitive thermometer, which uses a helical trimetallic strip of platinum, silver, and gold, around 1817. As temperature changes, the coil winds or unwinds, moving an index needle attached to the bottom around the temperature scale. This is a very early example made by the Breguet firm.
Such oval stickers are found on instruments from the Physics Department, Harvard University, so this example had later use for teaching.
Primary SourcesAndrew Ure, A Dictionary of Chemistry: On the Basis of Mr. Nicholson's, in which the Principles of the Science are Investigated Anew and Its Applications to the Phenomena of Nature, Medicine, Mineralogy, Agriculture, and Manufactures Detailed, American edition edited by Robert Hare, 2 vols., (Philadelphia, 1821).
ProvenanceSee Historical Attributions.