Traite d'Optique sur la gradation de la Lumiere: Ouvrage posthume de M. Bouguer, de l'Acaemie Royale des Sciences, &c. Et publie par M. l'Abbe de la Caille, de la meme Academie, &c.

Paris:: H.L. Guerin & L.F. Delatour, 1760., 1760. 4to. xviii, [2], 368 pp. Engraved printer's device on title-page, 7 engraved folding plates. Contemporary full mottled calf, raised bands, gilt-stamped spine panels and spine title; a few minor cover scars. Fine. FIRST EDITION. Bouguer, a brilliant French mathematician, astronomer and geophysicist, a child prodigy trained by his father, made some of the earliest recorded measurements in photometry. This is his final (and posthumous) work by the "father of photometry." / In 1729 he had published Essai d'optique sur la gradation de la lumiere, the object of which was to define the quantity of light (truncated) lost by passing through a given extent of the atmosphere, and he became the first known discoverer of what is now more commonly known as the Beer-Lambert law. Bouguer found the light of the sun to be 300 times more intense than that of the moon, and thus made some of the earliest measurements in photometry. "Just before he died, Bouguer completed a much larger book [this one] on photometry, the Traite d'optique sur la gradation de la lumiere. . . The Traite goes far beyond the Essai [d'optique sur la gradation de la lumiere, (1729)], describing a number of ingenious kinds of photometers, including a method of goniophotometry, and even attempting an elaborate theory of the reflection of light from rough surfaces, although this was not successful. The third and last part of the book, however, gives a valid elementary theory of the horizontal visual range through an obscuring atmosphere, arriving at a law, usually credited to H. Koschmieder, considered to belong to the twentieth century. It is fair to consider Pierre Bouguer not only the inventor of the photometer but also the founder of an important branch of atmospheric optics." [DSB]. / Bouguer's father was Jean Bouguer, a well-known hydrographer who authored a seminal treatise on navigation. Upon his father's death, Pierre—at age 15—succeeded the elder Bouguer as royal professor of hydrography. Pierre also wrote on hydrography. / Provenance: From the Alan deHaas collection [no markings]. / DSB Vol. II, pp. 343-44; Graesse I, 510; Norman 286; Wolf II, 167ff. (Inventory #: SS13176)