PECKHAM, John, GALLUCCI, Giovanni Paolo.

A good copy of the first edition of the first Italian translation of this fundamental optics manual—a ‘rare book’ (Riccardi I/1, 570), ‘rarer’—according to Guglielmo Libri—‘than the original work’ (‘Catalogo’, 1861, n.5656). Giovanni Paolo Gallucci (1538-c.1621) was a renowned mathematician and cosmographer, with interests in astrology; he was also a frequent translator of medical and scientific works, including ‘I tre libri’. This was a major optics manual written by the English Franciscan John Peckham (c.1230-92), student at Paris under St Bonaventure, and later professor at Oxford and archbishop of Canterbury. Inspired by the theories of Francis Bacon, whom he met either in Paris or Oxford, his ‘Perspectiva communis’ (1279) was said to be so named as it was widely used. In the following centuries it was ‘the most popular book on this subject’ as well as ‘the text-book until as late as about 1600’, when Kepler published the first modern study of optics (ten Doesschate, ‘Oxford’, 334). Gallucci’s vernacular translation made this fundamental yet concise work available to a broader audience. ‘Perspectiva’ was an explanation of the Arab mathematician Alhazen’s theories in 100 propositions, most followed by Gallucci’s brief commentary and illustrated with diagrams. Alhazen explored refraction, double vision and the physical circumstances that give rise to visual perception; he was the first recorded scientist to mention refraction by curved surfaces (ten Doesschate, ‘Oxford’, 323). Gallucci’s glosses feature examples taken from everyday life. For instance, ‘Propositio IX’ illustrates why a fire appears bigger at night, and bigger from afar, when one cannot distinguish the individual flames. Gallucci compares this to what happens in church to a short-sighted person who looks at the many lit candles: without his spectacles on, the candles will appear like they are big, and touching one another; with his spectacles on, the individual flames will be discernible and the candles smaller. The long section on mirrors discusses the reflection of colours, the angles of incidence, transparency, the function of lead on glass mirrors, mirrors made of iron or diamond, spherical or plain or shaped like a column, and the appearance of images on broken mirrors. An outstanding, clear scientific milestone and the basis of key modern optics theories including Kepler’s.