GRIMALDI, Francisco Maria.

Bononiae [Bologna]: Ex Typographia Haeredis Victorii Benatii, 1665

4to, 10 leaves, 535 pages, 8 leaves. Without the letterpress title-page (see below). Title-page printed in red and black with a large engraved vignette and additionally ruled in red by a contemporary hand. Text in double columns, diagrams and a few woodcuts in the text, divisional title to the second Book, woodcut ornaments. Contemporary vellum, spine lettered in ink (twice). Vellum a little dust-soiled, but a lovely, clean copy. Signature of William Jones (see below) in upper corner of title; Macclesfield bookplate on front pastedowm with shelfmark on free endpaper and small blind-stamp on first two leaves; bookplate of David L. DiLaura.

FIRST EDITION in which Grimaldi announced his discovery, and proved the existence, of optical diffraction, a term he also coined. This is among the rarest of the great books on optics, and it marks the first scientific attempt to establish a comprehensive wave theory of light. 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’ come from the loss of uniformity observed in a flow of stream of water as it ‘splits apart’ around a slender obstacle placed in its path” (DSB). Grimaldi repeatedly states that colours are not something different from light, but are modifications of it produced by the fine structure of the bodies which reflect it, and probably involving an alteration of the type of motion and velocity of the light. The periodic nature of light did not occur to Grimaldi (it was left to Newton in 1704 to prove the periodic nature of light), but his book was of fundamental importance for the subsequent development of optics. The book was issued with two title-pages, but in this copy the second (letterpress) title (a1) has been excised and discarded as unnecessary, probably at the time of binding. It is in all other respects a wonderful copy. Provenance: William Jones (1675–1749), mathematician and fellow of the Royal Society, who was trusted by Newton to publish his Analysis per quantitatum series (1711). Jones’s one time pupil was the Earl of Macclesfield; later Jones was on the staff at Shirburn Castle. Parkinson, Breakthroughs, 1665. DiLaura, Bibliotheca Opticoria, 135. Becker catalogue 162.3. See DSB for a full account of this book.

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