HUYGENS, Christiaan (1629-1695). Trait de la lumire... Avec un discours de la cause de la pesanteur. Leiden: Pieter vander Aa, 1690.
4o (228 x 192 mm). 2 parts in one, part 2 separately titled, continuously paginated, general title printed in red and black, both titles with printer's woodcut device, woodcut head-pieces and initials, 89 woodcut diagrams in the text, a few repeated. (Occasional light mostly marginal spotting or foxing.) Contemporary blind-panelled Dutch vellum over pasteboard (minor soiling, covers slightly bowed); quarter brown morocco felt-lined folding case.
Provenance: Thomas Herbert, eighth Earl of Pembroke (1656-1733), statesman, President of the Royal Society (1689-90), patron of John Locke--and dedicatee of Locke's Essay concerning Humane Understanding (author's presentation inscription "Pour Milord Pembrok" on title); 18th- or 19th-century shelfmark "I.a.27" on front pastedown.
FIRST EDITION, LARGE-PAPER ISSUE of Huygens' pathbreaking exposition of his wave or pulse theory of light. PRESENTATION COPY TO LOCKE'S PATRON, THE EIGHTH EARL OF PEMBROKE. Huygens had developed his theory of light in 1676 and 1677, and completed his Trait de la lumire 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 He read portions of the treatise to the Academy during the following year but left it unpublished, until Newton's Principia (1687) and a visit with Newton in 1689 stimulated him to have it printed at last.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..." (DSB). 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 Jean-Augustin 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.
The titles of this copy are in the probable earlier state, giving only the author's initials, as in the large-paper copy described by Horblit. The paper bears a watermark of crowned powder horn and pendant initials (resembling but not identical to Churchill 316), also as in the Horblit and Norman large-paper copies.
Macaulay describes Pembroke as a man of "eminent virtue," and of great learning, especially in mathematics." Although he was a Tory, "he was not illiberal as is proved by the dedication to him of Locke's Essay," which reads: "...in token of gratitude for kind offices done in evil times" (DNB). A FINE ASSOCIATION COPY.
Dibner, Heralds of Science 145; En franais dans le texte 25; Grolier/Horblit 54; NLM/Krivatsy 6124; Norman 1139.