René Antoine Ferchault de Réaumur (February 28, 1683 - October 17, 1757) was a French scientist of wide-ranging interests who made contributions in many fields, especially entomology.

Réaumur was born and educated at La Rochelle. He was taught philosophy in the Jesuits' college at Poitiers, and in 1699 went to Bourges to study civil law and mathematics under the charge of an uncle, canon of La Sainte-Chapelle. In 1703 he came to Paris, where he continued the study of mathematics and physics, and in 1708, aged only twenty-four, was elected a member of the Académie des Sciences. From this time onwards for nearly half a century hardly a year passed in which the Mémoires de l'Académie did not contain at least one paper by Réaumur.

At first his attention was occupied by mathematical studies, especially in geometry. In 1710 he was placed in charge of a major government project--the official description of the useful arts and manufactures--which resulted in the establishment of manufactures new to France and the revival of neglected industries. For discoveries regarding iron and steel he was awarded a pension of 12,000 livres; but, content with his ample private income, he requested that the money should go to the Académie des Sciences for the furtherance of experiments on improved industrial processes. In 1731 he became interested in meteorology, and invented the thermometer scale which bears his name: the Réaumur. In 1735, for family reasons, he accepted the post of commander and intendant of the royal and military order of Saint-Louis; he discharged his duties with scrupulous attention, but refused the pay. He took great delight in the systematic study of natural history. His friends often called him "the Pliny of the 18th century".

He loved retirement and lived at his country residences, including La Bermondière (Maine), where he had a serious fall from a horse, which led to his death. He bequeathed his manuscripts, which filled 138 portfolios, and his natural history collections to the Académie des Sciences.

Réaumur’s scientific papers deal with most branches of science; his first, in 1708, was on a general problem in geometry; his last, in 1756, on the forms of birds' nests. He proved experimentally the fact that the strength of a rope is more than the sum of the strengths of its separate strands. He examined and reported on the auriferous (gold-bearing) rivers, the turquoise mines, the forests and the fossil beds of France. He devised the method of tinning iron that is still employed, and investigated the differences between iron and steel, correctly showing that the amount of carbon (sulphur in the language of the old chemistry) is greatest in cast iron, less in steel, and least in wrought iron. His book on this subject (1722) was translated into English and German.

Réaumur wrote much on natural history. Early in life he described the locomotor system of the Echinodermata, and showed that the supposed vulgar error of crustaceans replacing their lost limbs was actually true. In 1710 he wrote a paper on the possibility of spiders being used to produce silk, which was so celebrated at the time that the Chinese emperor Kang-he had it translated into Chinese.

He also studied botanical and agricultural matters, and devised processes for preserving birds and eggs. He elaborated a system of artificial incubation, and made important observations on the digestion of carnivorous and graminivorous (grass-eating) birds. His greatest work is the Mémoires pour servir a l'histoire des insectes, 6 vols., with 267 plates (Amsterdam, 1734-42). It describes the appearance, habits and locality of all the known insects except the beetles, and is a marvel of patient and accurate observation. Among other important facts stated in this work are the experiments which enabled Réaumur to prove the correctness of Peyssonel's hypothesis, that corals are animals and not plants.de:René Antoine Ferchault de Réaumur es:René Antoine Ferchault de Réaumur fr:René-Antoine Ferchault de Réaumur