Thermometer with putti

France, Louis XVI period
Carved and gilt bronze

Simulating a small temple, this finely carved and gilt bronze rectangular thermometer presents a base with a beaded pedestal, on which stands mounts simulating ribboned beams on bases adorned with rosettes, which capitals receive an entablature decorated with a frieze of heart stripes. Between the two bases, a relief represents a scene where putti play on volutes, one on the left, ringing a bell, the other in the centre, blowing in an instrument.
Painted and lacquered, the dial indicates the temperatures with a tubular mercury coil.

From bottom to top, the following gradations are annotated:
- Paris 1709
- Frozen rivers
- Ice
- Orange trees
- Temperate
- Silk Worms
- Ordinary baths - Paris 1753
- Chickens - Senegal

The overall is framed by a garland of flowers suspended from two vases of oblong shape in the lower part and two horns of plenty in the upper part. Spouting from the horns of plenty, flowers descend and meet volutes climbing from the vases.

History of the thermometer
Traditionally attributed to Galileo, who defined the principle, the invention of the thermometer dates back to the middle of the 17th century. The temperature is measured by the expansion of a liquid contained in a glass tube. Several physicists of the 17th and 18th centuries gradually perfected this instrument and proposed different scales before the adoption of current scales. The Grand Duke of Tuscany, Ferdinando I de’ Medici, created an alcohol thermometer with 50 graduations in 1654, but it was not until 1717 that the German Fahrenheit invented the first mercury thermometer and the scale which today bears his name.
In 1742, the Swedish Anders Celsius invented a scale ranging from 100 degrees for freezing water to 0 degrees for its boiling point, the same scale that was to be reversed after his death. In 1794, the Convention approved this scale of degrees centigrade, which is the most widely used today. The mercury or alcohol thermometer can be of direct reading or on a dial. In this case, a mechanism connects a float placed in the column to a needle.

It was at the end of the 17th century that the ancient thermometer and barometer left the laboratories of scientists to be admitted into the interiors of cultivated people. Indeed, in the 18th century, with the birth of encyclopaedic collections, instruments and machines became more and more appreciated both for their decoration, the preciousness of their materials but also for the beauty of their shape. At that time, science was taking a growing place in society, whether princes or wealthy aristocrats, enjoyed owning instruments associating them with the latest discoveries. If the manufacture of the mechanisms of barometers and thermometers requires the very particular skills of an optician, the manufacture of the object is entrusted to cabinet makers or bronzers, who create cases for these instruments, like this thermometer.

Bibliography
Camille Frémontier-Murphy, «Une collection d’instruments scientifiques au musée du Louvre, », L’Estampille-L’Objet d’Art, n°342, Décembre 1999, pp. 40-53.