John Baptiste du, a very learned philosopher and writer, born at Vire in Normandy in 1624, was the son of an advocate esteemed for his knowledge, probity, and conciliating spirit. He commenced his studies at Caen, and completed them at Paris. His progress in philosophy was rapid, and at eighteen he wrote a treatise, in which he explained the Spheres of Theodosius, to which was added a tract upon Trigonometry, designed as an introduction to astronomy. Natural philosophy, as then taught, was only a collection of vague, puzzling, and barren questions; but Duhamel undertook to establish it upon right principles, and with this view published his *Astronomia Physica*. In 1666 Colbert having proposed to Louis XIV. a scheme, which was approved by his majesty, for establishing a Royal Academy of Sciences, Duhamel was appointed perpetual secretary; a situation for which he was eminently qualified, both by his acquirements and by his talent for managing the different parties into which that learned society was divided. Besides, he wrote in Latin with remarkable purity and elegance (a great advantage at a period when the French had not become an European language); and, by reason of this accomplishment, he accompanied Colbert first to the congress of Aix-la-Chapelle, and afterwards to England, when his patron proceeded to that country in the capacity of French ambassador. He subsequently visited Holland, and then returned to France, where, between 1670 and 1673, he gave to the world the results of his observations, in three publications. His next production was a course of philosophy, which he composed for the use of the students in the College of Burgundy; a work in which, if he did not exclude the ancient systems, the weakness and absurdity of which already began to be perceived, he at least combated their grosser errors, and succeeded in recommending new truths, without in any degree involving himself in trouble by doing so. He then published a course of theology, which met with great success, and of which he was required to execute an abridgment for the use of the schools. But all his labours did not prevent him from assiduously attending the sittings of the Academy, of which he was preparing a history; his zeal enabled him to surmount all difficulties; even the very infirmities which announced his approaching dissolution could not abate his ardour for study; and he was still meditating new undertakings, when death surprized him in the midst of his projects, on the 6th of August 1706, at the age of eighty. His principal works are 1. *Astronomia Physica*, Paris, 1660, in 4to; 2. *De Meteoris et Fossilibus*, ibid., 1660, in 4to; 3. *De Consensu Veteris et Novae Philosophiae libri iv.*, Paris, 1663, in 4to; 4. *De Corporum Affectionibus, cum manifestis tum occultis, libri duo*, Paris, 1670, in 12mo; 5. *De Mente Humana*, libri iv. Paris, 1672, in 12mo; 6. *De Corpore Animate*, libri iv. Paris, 1673, in 12mo; 7. *Philosophia Vetus et Nova ad usum Scholae accommodata*, Paris, 1678, in four vols. 12mo; 8. *Theologia Speculatrix et Practica*, Paris, 1691, in seven vols. 8vo; 9. *Regiae Scientiarum Academiae Historia*, Paris, 1698 and 1701, in 4to. Duhamel also translated into Latin the *Traité des Droits de la Reine sur plusieurs États de la Monarchie d'Espagne* of Bilain, Paris, 1667, in 4to.