Antique Walking Stick With 18th-century Mechanism, Barometer, Madeleine Gely Collection

An exceptional walking stick with a special mechanism, from the former collection of Madeleine Gely, in Paris. This walking stick is the one Madeleine Gely loaned for photography and description in Catherine Dike's reference work, "Les cannes à système" (Walking Sticks with a System), illustration 9/64.
It is described there as follows: A wooden barometer that opens in two parts, held together by an ivory handle. A small valve closes to prevent the mercury from escaping while walking with the stick. The deerskin covering, which prevents the mercury from escaping while still allowing atmospheric pressure to act on it, is also visible. The graduations and weather forecasts are inscribed in ink. A small thermometer, graduated in Fahrenheit and Réaumur degrees, is included along the barometer. It measures 39,76 inches in length and approximately 1,81 inches in diameter at the top of the pommel.
France, late 18th century.