René Antoine Ferchault de Réaumur
French entomologist and inventor of the Réaumur temperature scale.
René Antoine Ferchault de Réaumur was a French entomologist and writer born in 1683 into a prominent family from La Rochelle. He studied philosophy at a Jesuit college in Poitiers and later civil law and mathematics in Bourges under his uncle, a canon. In 1703 he moved to Paris to continue studying mathematics and physics. By 1708, at age twenty-four, he was elected to the Académie des Sciences, nominated by his mathematics teacher Pierre Varignon. For nearly fifty years, the academy’s proceedings rarely lacked a paper by him. His early work focused on geometry, but he soon contributed to many fields. In 1710 he became chief editor of a government project on arts and trades, helping establish new manufactures and revive neglected industries. His discoveries about iron and steel earned him a pension of 12,000 livres, which he redirected to the academy for industrial experiments. In 1731 he invented the thermometer scale that bears his name, taking water’s freezing point as zero and graduating the tube into thousandths of the bulb’s volume; the boiling point of water happened to fall at 108 degrees on his alcohol thermometer. Later mercurial thermometers with eighty equal divisions between freezing and boiling are called Réaumur thermometers but differ from his original design. He studied natural history extensively, earning the nickname “the Pliny of the 18th century.” He demonstrated that echinoderms could regrow lost limbs, investigated spiders’ potential for silk production (a paper translated for the Kangxi Emperor), and observed wasps making paper from wood fibers, an insight that preceded industrial wood-pulp papermaking by over a century. He computed insect population growth rates and noted that natural checks prevent geometric increases. He studied the relationship between insect development and temperature, devised artificial incubation methods, and preserved birds and eggs. His six-volume work on insects described their appearance, habits, and habitats, and included experiments confirming that corals are animals. He also examined France’s gold-bearing rivers, turquoise mines, forests, and fossil beds, devised a method for tinning iron, and correctly distinguished iron, steel, and cast iron by carbon content. In 1735 he accepted a post as commander of the Order of Saint Louis but refused the salary. He died in 1757 from injuries after a fall from a h
- field
- Entomology, physics, mathematics, metallurgy
- nationality
- French
- known_for
- Réaumur temperature scale, studies of insects, iron and steel metallurgy
Lore & Background
Réaumur was a French entomologist and writer who contributed to many fields, especially the study of insects. He introduced the temperature scale that bears his name. He was born into a prominent family in La Rochelle and educated in Paris, studying philosophy at a Jesuit college in Poitiers and later civil law and mathematics in Bourges under an uncle. In 1703 he moved to Paris to continue studying mathematics and physics. In 1708, at age 24, he was nominated by his mathematics teacher Pierre Varignon and elected to the Académie des Sciences. For nearly half a century, hardly a year passed without a paper by Réaumur in the Académie's Mémoires. His early work focused on geometry. In 1710 he became chief editor of the Descriptions of the Arts and Trades, a government project that established new manufactures in France and revived neglected industries. For discoveries regarding iron and steel he was awarded a pension of 12,000 livres, but he requested the money go to the Académie for further experiments. In 1731 he became interested in meteorology and invented the Réaumur thermometer scale, taking the freezing point of water as 0° and graduating the tube into degrees each one-thousandth of the volume up to the zero mark; the boiling point of water happened to be 108° with the alcohol he used. He loved retirement and lived at his country residences, including his chateau La Bermondière in Maine, where a serious fall from a horse led to his death. He bequeathed his manuscripts, which filled 138 portfolios, and his natural history collections to the Académie des Sciences. His scientific papers covered many branches: he proved the strength of a rope is more than the sum of its strands, examined France's gold-bearing rivers and fossil beds, devised the method of tinning iron still employed, and investigated differences between iron and steel, correctly showing carbon content is greatest in cast iron, less in steel, and least in wrought iron. He wrote much on natural history, describing the locomotor system of echinoderms and confirming their ability to replace lost limbs. He studied the relationship between insect growth and temperature, computed insect population growth rates, and noted natural checks prevented geometric progression from matching actual populations. His six-volume work on insects described their appearance, habits and locality, and included experi
Reader's Guide
Réaumur's significance lies in his wide-ranging contributions across multiple sciences. He devised the method of tinning iron still employed, and correctly showed that carbon content differs in cast iron, steel, and wrought iron. In natural history, he described the locomotor system of Echinodermata and showed they could replace lost limbs. He wrote on spiders producing silk, which the Kangxi Emperor had translated into Chinese. His observations of wasps making paper from wood fibers are credited with influencing paper-making techniques, though industrial use of wood pulp came over a century later. He studied insect growth and temperature, computed population growth rates, and noted natural checks preventing geometric progression.
Did You Know?
- Réaumur proved experimentally that the strength of a rope is more than the sum of the strengths of its separate strands.
- He devised the method of tinning iron that is still employed.
Frequently Asked Questions
What is René Antoine Ferchault de Réaumur most famous for?
His most lasting legacy is the Réaumur temperature scale, a standardized system for measuring heat that saw wide adoption in French scientific and industrial practice. He is also well known for his detailed investigations into insect behavior and the metallurgical properties of iron and steel.
Which scientific fields did Réaumur contribute to?
His published work spanned entomology, physics, mathematics, and metallurgy, making him a genuine multi-disciplinary researcher of the 18th century. His insect studies and metal-composition experiments are generally regarded as his two deepest contributions.
Why is the Réaumur temperature scale historically significant?
It represented one of the first broadly adopted standardized scales for quantifying temperature, giving French laboratories and workshops a common reference point. Although it was eventually superseded by the Celsius scale, it helped establish the idea of a universal thermal measurement system.
Why does Réaumur matter to the history of chemistry and materials science?
His practical research into the composition and treatment of iron and steel provided knowledge that later metallurgists built upon. Combined with his entomological work and his role within the French Academy of Sciences, he helped shape the institutional and empirical foundations of 18th-century natural philosophy.
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