First made by Frederic Houriet, this type of pocket thermometer was later produced by Urban Jürgensen and by Breguet. It was first described by Houriet himself in an advertising leaflet, of which each copy was hand-signed by him.This kind of bimetallic thermometer is illustrated by Urban Jürgensen in "Principes Généraux de l'Exacte Mesure du Temps par les Horloges", 1805, pl. XIX.This watch is published in the Ruscitti book, as no. 72.René Antoine Ferchault de Réaumur (1683-1757).French physicist and naturalist who invented an alcohol thermometer (1731) and the Réaumur temperature scale, in which the freezing point of water is 0° and the boiling point 80°. In 1710 he directed the official description of arts and trades in France. He investigated gold-bearing rivers, turquoise mines, and forests. He did research on the composition of Chinese porcelain, which led him to develop an opaque glass, and on the composition and manufacture of iron and steel, including a means ofinning iron. As a naturalist he is best known for his exhaustive study of insects; he also studied regeneration in crayfish and showed corals to be animals, not plants.Encyclopedia.com - The Columbia Electronic Encyclopedia, Sixth Edition, 2000 - Columbia University Press.