Traité de la lumière. Ou sont expliquees les causes de ce qui luy arrive dans la reflexion, & dans la refraction. . . Avec un discours de la cause de la pesanteur by HUYGENS, Christiaan - 1690

Leiden: Pieter van der Aa, 1690. 1st Edition. Hardcover. Very Good. 1st Edition. Hardcover. 4to (198 x 158 mm). [8], 1-124 [2] 125-128 [2] 129-180 pp. Signatures: *4 A-P4 Q2 R4 S2 T-Z4 Aa2. Two parts in one, separate title to part two, continuous pagination, general title printed in red and black, both titles with printer's woodcut device, woodcut head-pieces and initials, 89 woodcut diagrams in text. Bound in contemporary calf, spine rebacked and with gilt-lettered morocco label (little rubbing to board sand extremities, corners bumped), red-spinkled edges. Text little browned, marginal light dust soiling, first four leaves with just a few mm of light dampstaining at top edge, very minor occasional spotting, a few short tears not affecting text. A fine, unsophisticated, wide-margined and unmarked copy. ----

Dibner 145; Horblit 54; Norman 1139; Sparrow 111; Evans 32; D.S.B. VI, p.609-10; En francais dans le texte 25. FIRST EDITION of Huygens' pathbreaking exposition of his wave theory of light. Huygens had developed his theory in 1676 and 1677, and completed his Traite de la lumière in 1678. He read portions of the treatise to the Academy during the following year but left it unpublished, until Newton's Principia (1687) and a visit with Newton in 1689 stimulated him to have it printed at last. "Light, according to Huygens, is an irregular series of shock waves which proceeds with very great, but finite, velocity through the ether. This ether consists of uniformly minute, elastic particles compressed very close together. Light, therefore, is not an actual transference of matter but rather of a 'tendency to move,' a serial displacement similar to a collision which proceeds through a row of balls [...] Huygens therefore concluded that new wave fronts originate around each particle that is touched by light and extend outward from the particle in the form of hemispheres." (D.S.B.). Huygens was able to explain reflection and refraction using this theory, of which he became completely convinced in August 6, 1677, when he found that it explained the double refraction in Iceland spar. His view of light was opposed to the corpuscular theory of light advanced by Newton. In the second part of the work, the Discours de la cause de la pesanteur, written in 1669, Huygens expounded his vortex theory of gravity, a purely mechanistic theory that also contrasted markedly with Newton's notion of a universal attractional force intrinsic to matter. Indeed, Huygens added to the original treatise of 1669 a review of Newton's theory, rejecting it out of hand because of the impossibility of explaining it by any mechanical principle or law of motion. Huygens' work fell into oblivion during the following century, but his theory of light was confirmed at the beginning of the 19th century by Thomas Young, who used it to explain optical interference, and by Augustin-Jean Fresnel a few years later. Modern physics has reconciled Newton's and Huygens' theories in discerning both corpuscular and wave characteristics in the properties of light. There are two states of the two title leaves known. Our copy is with the author's initials only on both titles (no priority established).