Physico-Mathesis de Lumine, coloribus, et iride, aliisque sequenti pagina indicatis by GRIMALDI, Francesco Maria - 1665

Bologna: heirs of Victorio Benacci for Girolamo Bernia, 1665. 1st Edition. Hardcover. Very Good. 1st Edition. Hardcover. 4to - over 9¾ - 12" tall. 4to (235 x 180 mm). [24], 535 [1], [16] pp. Signatures: [pi]2 a4 b6 A-Z4 2A-2Z4 3A-3Z4. Including first blank [pi]1, title page printed in red and black and with large engraved vignette, additional letterpress title also printed in red and black and with smaller woodcut device, text in double columns, several woodcut text illustrations and diagrams, 7 leaves of index and ad lectorem leaf at end. Bound in later limp vellum, yapp edges, spine with gilt-lettered red morocco label, red-dyed edges (vellum slightly soiled and spotted). Text only little browned throuhout, light staining and damp-spotting in places, first title with restoration at top corner (possibly from small erased stamp with 4 partially refinished letters). Provenance: Thomas Vroom (pictorial bookplate to front pastedown). All in all a very good copy. ----

DSB V, pp. 542-45; Riccardi I, 631 ('celebrated and scarce work'). FIRST EDITION of Grimaldi's only publication, the discovery of optical diffraction. In this important and celebrated work Grimaldi describes his discovery of the inflection of the solar rays near certain bodies. He was the first to declare that the diffusion of light was instantaneous. The diffraction experiments which Grimaldi describes 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. He discussed other fluid phenomena analogously with light. To explain color and the varieties of color he decided that a "change in agitation" of the luminous flow is responsible. A light ray is conceived like a column of fluid in vibration, but not regular vibration. Lighter colors are said to result from a greater density of rays and darker colors from a lower density ... Knowledge of his work appears in the work of both Hooke and Newton. Hooke performed his first series of diffraction experiments later in 1672, after the notice of Grimaldi's book in the Philosophical Transactions. Hooke referred to it, however, as inflexion and may have encountered diffraction phenomena independently. Newton was aware of Grimaldi's work, but only at secondhand, crediting Honoré Fabri as the source of his knowledge on diffraction. At first (1675) Newton described and attempted to account for only the internal fringes. His description shows that he could not have performed the experiment. By 1686 he came to deny the existence of internal fringes on the basis of experiments. In the Opticks he described and tried to explain only the external fringes, which he never ceased to regard as a sort of refraction." (DSB) - Visit our website to see more images!