Jean-Baptiste DUHAMEL (1624-1706), astronomer, physicist and metaphysician, was the first perpetual secretary of the Académie des Sciences when it was founded by Colbert in 1666. Autograph manuscript, 6 pp. in-8. August-September 1675. Precious personal diary of Jean-Baptiste Duhamel, reporting on experiments by Mariotte, Cassini, etc., in particular during sessions at the Académie des sciences. "[...] M. Dodart proposed that an experiment be carried out on the distillation of the spirit of urine of children and old people to see if the spirit of children's urine is sulphurous and the spirit of old people's urine is acidic and dissolves gold [...]. Mr Marchand brought a plant named Lotus syncata flora purpurio, which has been described: this plant has not yet been described by any author [...]. Mr. Mariotte brought a pipe from his bench 15 feet one inch high, including half the height of a reservoir eight inches high, which contained a pint of water; we experimented that these eleven pints flowed in thirty seconds through a circular opening of six lines, made in the middle of the base. A second experiment was carried out with a tin tray, at the top of which there was a circular hole precisely one inch in diameter. Having made the water flow into the tub in such a way that it continuously overflowed by about the height of one line of the circular opening, three pints came out in 75 seconds [...]. Mr Cassini brought observations of the last eclipse made in England, which agree very well with those made at the observatory [...]. Mr Mariotte brought a report concerning a monster which came into the world on the eleventh of June 1675, it had two testes, 7 arms, 7 legs, a single trunk, two hearts attached by their base separated by their points in a single pericardium [...]. On Wednesday 28th August 1675 [...After leaving the bottle at a very gentle heat, the liquor took on the colour of garnet; the distilled vinegar having drawn no liquor from it, this coloured liquor, charged with the dye of garnet, lost its acidity [...]. M. Cassini read the observations he had made of Saturn and its satellites [...]. On Saturday the 7th of September 1675, Mr Cassini read his hypotheses concerning the movement of vibration in the moon, which he will continue on the first day [...]". Very rare 17th century scientific autograph manuscript.