EULER Leonhard Dioptricae. Pars prima continens librum primum de explicatione principiorum ex quibus constructio tam telescopiorum quam microscopiorum est petenda. Pars 2 continens librum secundum de constructione telescopiorum dioptricorum. Pars 3 continens librum tertium de constructione microscopiorum.

DSB, IV, 467-482 ; DiLaura, 494; Daumas. Les Instruments scientifiques, pp. 202-205.

First edition of the foundation of the calculation of optical systems.

The astronomer Joseph Jérôme Lefrançois de Lalande's (1732-1807) own copy. "The result of this polemic, in which both parties were partly right and partly wrong, was the creation by Dollond of achromatic telescopes (1757), a turning point in optical technology. For his part, Euler, in his Dioptrica, laid the foundations of the calculation of optical systems" (D.S.B.).

"C'est grâce à l'invention de l'objectif achromatique, par exemple, que l'on put songer à établir le mètre étalon sur la mesure du quart du méridien, ou encore que Claude Chappe put réaliser son télégraphe optique" (cf. Daumas, Histoire de la science, p. 911). Director of the Observatoire de Paris from 1769 until his death, Lalande's celebrity is in part based on his observations on the orbit of Venus. "In 1760 he succeeded Delisle as professor of astronomy at the Collège Royal. Lalande was an excellent teacher and had many distinguished pupils during his forty-six years of service at the Collège Royal, including J.B.J. Delambre, G. Piazzi, P. Méchain, and his nephew, Michel Lalande… The most important calculations of the solar parallax from the transit of 1769 were those of Lalande (published in his Mémoire sur le passage de Vénus observé le 3 juin 1769)" (DSB). The great astronomer is also the author of the indispensable work, the Bibliographie astronomique published in 1804.

Lalande's signature is placed on the inside covers of each volume, the fly-leaf of vol. II contains the following note : "il rejette encore les lunettes achromatiques, p. 331".

Broad margined copy.