Physico-Mathesis de Lumine, Coloribus, et Iride..

Added title-page with a large engraved vignette & woodcut diagrams in the text. Both titles printed in red & black. 11 p.l. (including the added title-page), 535 pp., 8 leaves. 4to, fine antique mottled calf (some faint dampstains), sides panelled in gilt, spine richly gilt, red morocco lettering piece on spine. Bologna: Heirs of V. Benati, 1665.<br /> <p> First edition, the copy of William Molyneux (1656-98), astronomer, founder of the Dublin Philosophical Society, and author of the first treatise on optics in English (for more on Molyneux, see D.S.B., IX, pp. 464-66). This is Grimaldi's only book; in it he describes the discovery of optical diffraction. This is perhaps the rarest of all great optical books, especially in such good condition, and marks the first scientific attempt to establish a comprehensive wave theory of light. <P>The diffraction experiments which Grimaldi describes here show "that a new mode of transmission of light had been discovered and that this mode contradicts the notion of an exclusively rectilinear passage of light. Diffraction thus gave prima facie evidence for a fluid nature of light. The name 'diffraction' comes from the loss of uniformity observed in the flow of a stream of water as it 'splits apart' around a slender obstacle placed in its path."-D.S.B., V, p. 544. <P>Grimaldi repeatedly states that colors are not something different from light but are modifications of light produced by the fine structure of the bodies which reflect it, and probably consisting of an alteration in the type of motion and in the velocity of the light. The different colors are produced when the eye is stimulated by light oscillations whose velocities differ. All these views were of fundamental importance for the subsequent development of optics. <P>Newton was aware of Grimaldi's work, though only secondhand. The Englishman's great contribution to the knowledge of diffraction is his set of careful measurements which made clear the periodic nature of the phenomenon. <P>With the signature of William Molyneux on the second title-page. Bookplate of E.N. da C. Andrade. Very good copy.<br /> <p>❧ Albert, Norton, & Hurtes, Source Book of Ophthalmology, 919-contains "Grimaldi's work on the discovery of the diffraction (Newton's inflexion) of light...considered a classic in the history of optics, this work makes the first scientific attempt to establish the wave theory." Kemp, The Science of Art, p. 285.