De radiis visus et lucis in vitris perspectivus et itide tractatus ... In quo inter alia ostenditur ratio instrumenti cuiusdam ad clare videndum, quae sunt valde remota excogitate ...

Venice: Tomasso Baglioni, 1611.

First edition, extremely rare, of this important early work on the optics of the telescope and related optical phenomena, and containing the first essentially correct theory of the rainbow to be published. Dominis and Galileo were both teaching mathematics and physics in Padua at the same time, and it is almost certain that they knew each other. The present work has the same publisher as Galileo’s Sidereus nuncius of the previous year. Dominis sought to provide the theoretical explanation behind Galileo’s telescopic observations, and his work appears to have been completed before Galileo’s, although published later (see below). The work was edited by Dominis’s friend Giovanni Bartolo. “In the preface, Bartolo says that the work is based on notes prepared by De Dominis for his lectures at Padua and Brescia twenty years before; but he adds that De Dominis himself had revised these notes and inserted an explanation of the newly-invented telescope” (Ockenden, p. 42). This preface is the source for the erroneous claim that Galileo ‘invented’ the telescope. The second half of the book is taken up with the phenomena of refraction and reflection in raindrops and the rainbow. Newton owned a copy of this book (Harrison 535) and referred to it twice in his Opticks, stating that Dominis was the first to present a correct theory of the rainbow, involving double refraction and internal reflection of sunlight in raindrops. This led to a dispute with Descartes and his supporters, who held that the first correct explanation of the rainbow was given in Descartes’s Discours (1637). ABPC/RBH list only one copy since the Honeyman copy sold in 1979 (both of these copies were in modern bindings).

“Dominis had written two works on physics by the time he lectured on mathematics in Padua. The first one, De radiis visus et lucis, deals with lenses, telescopes, and the rainbow. Dominis knew how light was refracted in its passage from one medium to another, but he was not always consistent in his assertions. He held that it was possible that in some cases light could pass through the border of a medium without being refracted—for instance, into a thin layer of water. In general, his observations on refraction in lenses were correct.

“After the invention of the telescope Dominis added its theoretical explanation to his work. His explanation was not entirely satisfactory, however, because his knowledge of the law of refraction was incomplete. He concluded that the image of an object was enlarged by increasing the angle of sight, which he had previously defined correctly. Thus Dominis describes in particular detail the effect on the angle of sight of a lens of greater curvature or of a greater distance between the lens and the object being viewed. With the same thoroughness he examined lens combinations, in particular the combination of a convex object glass and a concave eyepiece. This work led to his discovery of the conditions under which the magnification of an image is possible” (DSB).

The correct elementary explanation of the rainbow in terms of reflection and refraction of the Sun’s rays in raindrops was given by the Persian astronomer and physician Qutb Al-Din and the Teutonic Dominican theologian Theodoric of Freiburg as early as the fourteenth century, but their work remained unpubished until the nineteenth century (although Regiomontanus had considered publishing Theodoric’s work on optics). Many other scholars attempted explanations in the intervening centuries. Johannes Kepler gave a variey of incorrect and sometimes fanciful explanations, but in correspondence with Thomas Harriot in the years 1606-1609 he gave essentially the correct one. However, this was not included in his Dioptrice, published in the same year as the present work, nor in any of his other published works. So closely does Dominis’s theory of the rainbow resemble Descartes’s account in Les météores (appended to the Discours) that several scholars, notably Leibniz and Newton, accused Descartes of plagiarism.

Newton owned a copy of Dominis’s work and must have studied it with some care, since he refers to the preface by Bartolo, and to the experiments which Dominis claimed to have made with “a phial full of water, and with globes of glass filled with water.” E. T. Whittaker suggested that his study of De radiis may have originated Newton’s interest in atmospheric optics (Preface to Newton, Optics (1931), p. xii). On the rainbow, in Prop. IX, Prob. IV of his Opticks (1704), By the discovered Properties of Light to explain the Colours of the Rain-bow, Newton wrote: “This Bow never appears but where it rains in the Sun-shine, and may be made artificially by spouting up Water which may break aloft, and scatter into Drops, and fall down like Rain. For the Sun shining upon these Drops certainly causes the Bow to appear to a Spectator standing in a due position to the Rain and Sun. And hence it is now agreed upon, that this Bow is made by refraction of the Sun's Light in Drops of falling Rain. This was understood by some of the Ancients, and of late more fully discovered and explained by the Famous Antonius de Dominis Archbishop of Spilato, in his Book De Radiis Visus & Lucis, published by his Friend Bartolus at Venice, in the Year 1611, and written above twenty Years before. For he teaches there how the interior Bow is made in round Drops of Rain by two refractions of the Sun's Light, and one reflexion between them, and the exterior by two refractions and two sorts of reflexions between them in each Drop of Water, and proves his Explications by Experiments made with a Phial full of Water, and with Globes of Glass filled with Water, and placed in the Sun to make the Colours of the two Bows appear in them. The same Explication Des-Cartes hath pursued in his Meteors, and mended that of the exterior Bow.” The final sentence seems to support the charge of plagiarism against Descartes, who represented his theory as wholly original. Newton’s view was accepted by Christian von Wolf in his Mathematisches Lexicon (1716), by Henry Pemberton in A view of Sir Isaac Newton’s Philosophy (1728) (p. 394), and by Voltaire in Lettres Philosophiques (1734) (Lettre 16, Sur l’optique de Mr. Newton).

The close relationship between this book and the Sidereus nuncius goes beyond their shared printer: both works have the same printer’s device on the title, and both have the same licenser, Giovanni Battista Breatto. Dominis’s work was granted its licence on 3 February 1610; the Sidereus on 8 March 1610. Thus, Dominis’s was probably the first account of the telescope, following Galileo’s public demonstration of the instrument on 25 August 1609, and before Galileo’s own account in the Sidereus. The reason for the delay in publishing De radiis is uncertain, but its licence states that it is a work of 69 pages, rather than the published 78; it is possible that the publisher decided to delay publication so that Dominis could update the text to take into account the Sidereus.

Marco Antonio de Dominis was born in 1566 at Arbe, an island off the Dalmatian coast. He was descended from a distinguished Italian family, and became a brilliant pupil of the University of Padua. He entered the order of the Jesuits, and even during his noviciate was appointed professor of mathematics at Padua, and of logic and rhetoric at Brescia. He was exceedingly ambitious, and became successively bishop of Segni and archbishop of Split, the town in Dalmatia where his family of popes and princes reigned as a dynasty. During the Venice interdict in 1606, Dominis sided with Paolo Sarpi and fell into the Protestant orbit of the British embassy in Venice. In 1617 Dominis slipped out of Italy with a purloined copy of the manuscript of Sarpi’s sensational book on the Council of Trent, and made his way along the Rhine and finally to England where, on 3 December 1617, he pronounced himself to be a Calvinist. James I made him dean of Windsor, and Dominis published Sarpi’s book without the author’s permission, appending a dedication to James I. Within a few years his ecumenical histrionics were too much for the English and he was expelled. In Brussels he appealed to the then Pope, his friend, schoolmate and relative Gregory XV, promising a renunciation of his Protestantism if he could return to Rome. This was arranged, and on 24 November 1622 he formally renounced his heresies and damned Sarpi’s book. He returned to scientific speculation and wrote a book about the tides, Euripus, seu de fluxu et refluxu maris, published posthumously at Rome in 1624. Galileo disliked the book intensely, although Dominis’s explanation of the tides was correct, unlike Galileo’s. “A certain cleric has published a little treatise,” Galileo would write in the Dialogo, “wherein he says that the moon, wandering to and fro in the heavens, attracts the oceans. The mass of water follows the moon, so that the ocean is full in that part of the world laying under the power of the moon.” With the death of Gregory XV in July 1623, Dominis lost his protector, and under the new Pope, Urban VIII, he was soon denounced for his exploits among the protestants. In September 1624, he was detained in the papal prison at Castel Sant’Angelo, and after a ten-hour interrogation became ill and died. Three months later, his body was exhumed and the casket taken ceremonially to the Dominican basilica of Santa Maria Sopra Minerva in Rome. Dominis’s casket was painted with black pitch, his soul was was formally condemned, his writings banned, and his property forfeited. His decomposed body was removed from the casket and publicly burned, along with all his books. All his works were placed on the Index librorum prohibitorum.

This is an extremely rare book, and has been for a very long time. “N. J. Poisson, writing in 1671, says he was unable to procure a copy, although he made every effort to do so (Commentaire ou remarques sur la méthode de Mr. Descartes, Paris, 1671, p. 209). Several later writers have alluded to the unusual rarity of this work, which may indicate that some attempt was made to suppress it” (Ockenden, p. 42, note 5).

Carli and Favaro 37; Cinti 33; Albertet al 529; Sommervogel III, column 130 (no 1); Riccardi I 447-448; Norman 645 (bound with Sidereus nuncius); Ockenden, ‘Marco Antonio de Dominis and His Explanation of the Rainbow,’ Isis 26 (1936), pp. 40-49. OCLC lists copies in US at Brown, Johns Hopkins, Harvard, Burndy, Smithsonian, Linda Hall, New York Public, Miami (School of Medicine), Chicago, Caltech & Oberlin.



4to (214 x 154 mm), pp. [viii], 78, [2, errata], with woodcut printer’s device on title and numerous woodcut diagrams in text. Contemporary limp vellum with old paper and label on spine, remains of ties. A fine, unpressed copy.

Item #5094

Price: $70,000.00