DUHAMEL, Jean Baptiste (1624-1706), a French astronomer and physician, was the son of an advocate, and was born at Vire, in Normandy, in 1624. He commenced his studies at Caen, aud completed them at Paris. At the age of eighteen he wrote a treatise on the Spherics of Theodosius, and added to it a tract on trigonometry, designed as an introduction to astronomy. At the age of twenty-one he became curé of Neuilly-sur-Marne, but without neglecting the duties of his calling, he continued to cultivate the physical sciences with zeal. In 1656 he was named almoner of the king; in 1663 he obtained the dignity of chancellor of the church of Bayeux; and in 1666, when Louis XIV. established the Royal Academy of Sciences, he was appointed perpetual secretary. He was preparing a history of the Academy when he died, August 6, 1706. He published numerous works on philosophy, divinity, and physical science.

DUHAMEL DU MONCEAU, Henry Louis (1700- 1782), a celebrated French botanist and agriculturist, was the son of Alexandre Duhamel, lord of Denainvilliers, and was born at Paris in 1700. He was placed at the Collége d’Harcourt, but made little progress in his studies, except that, notwithstanding the imperfect manner in which the natural sciences were there taught, he acquired such a taste for these branches of knowledge as led him to attend the lessons of Dufay and Bernard de Jussieu at the Jardin des Plantes. He now spent his time between the capital, where he pursued his botanical studies and held intercourse with scientists, and his estates at Gâtinais, where he employed his knowledge in arboricultural experiments. Having been requested by the Academy of Sciences to investigate the cause of the disease which was destroying the saffron plant in Gâtinais, he discovered that its destruction was owing to a parasitical fungus which attached itself to its roots. The work in which he demonstrated his discovery was judged worthy to appear in the transactions of the Academy, and gained him admission to that· body iu 1728. From then until his death he busied himself chiefly with making experiments in vegetable physiology, and recording and publishing his observations. Having learned from Sir Hans Sloane that madder possesses the property of giving colour to the bones, he fed animals successively on food mixed and unmiκed with madder; and he fomιd that their bones in general exhibited concentric strata of red and white, whilst the softer parts showed in the meantime signs of having been progressively extended. From a number of experiments he was led to believe himself able to explain the growth of bones, and to demonstrate a parallel between the manner of their growth and ...