L’Occhiale all’Occhio. Dioptrica Pratica […] Dove si tratta della Luce, della Refrattione de raggi, dell’Occhio, della Vista e degli aiuti, che dare si possono à gli occhi per vedere quasi l'impossibile. Dove in oltre si spiegano le regole pratiche di fabbricare Occhiali à tutte le viste, e Cannocchiali da osservare i pianeti, e le stelle fisse, da terra, da mare, et altri da ingrandire migliaia di volte i minimi de gli oggetti vicini.

Bologna: per l’herede del Benacci, 1660.

First and only edition of this important work on the making of lenses, spectacles, telescopes and microscopes, “the most comprehensive book on the subject” (Ilardi, p. 229). “Seventeenth-century account of dioptrics, dealing with light, refraction, the eye, vision, the invention of spectacles, the making of spectacles and telescopes. The book, which is essentially practical, aims at showing the optical worker how lenses are ground and how they may be used both to remedy visual defects and also for telescopes. The dedication ... is to Saint Lucia, the patron saint of the blind and those with diseased eyes” (British Optical Association Catalogue). “An important work in the history of optics, valuable as one of the earliest detailed accounts of methods of grinding and polishing lenses. A large number of fine woodcuts illustrate the machinery and processes described by the author” (Becker Catalogue). The first chapter contains an account of the invention of the telescope, and of Galileo’s role in it, and also of the invention of spectacles. The following three chapters deal respectively with optics, the anatomy of the eye, and the mechanics of vision. The remaining ca. 200 pages are devoted to the manufacture of lenses, with extensive discussion of the different kinds of lenses required for various purposes, and the different methods of their design and manufacture. There are descriptions of the Murano glassworks, opticians’ tables for the precise measurement of lenses, and illustrations of a lens grinder, glass-cutting shears, lathes and several optical instruments. The full-page portrait of Eustachio Divini, aged 49 years, bears an inscription stating that he is judged by scientists of optics to be the first to have fabricated large telescopes (occhialoni). As several of Divini’s works are addressed to Manzini it is reasonable to suppose that this work documents in part Divini’s discoveries. This is an unpressed copy on thick paper, bound in contemporary vellum, and with manuscript corrections in Manzini’s hand – see, for example, the copy at the Universidad Complutense de Madrid, which has the same corrections in the same hand as our copy.

Born of the Bolognese nobility, “Manzini established his own astronomical observatory on the grounds of his estates around Bologna and made his own telescopes, grinding the lenses for them himself … Manzini’s [book] was both a theoretical and practical compendium of what was known on optics and on the art of spectacle making from the fusion of glass and crystal to the fitting of glasses for various refractive errors and the insertion of precision lenses in telescopes and microscopes …

“In his preface, Manzini expressed his consternation in seeing the art of spectacle making being passed orally from one generation to the other without written instructions and often in strict secrecy so that much valuable information was lost forever. His book was designed to serve as a guide both in theoretical optics as developed by medieval authorities such as Alhacen (965-1040), Witelo (ca. 1230-80), [Roger] Bacon (1214/20-92) and by writers closer to his age such as Johannes Hevelius (1611-87), [Francesco] Maurolico (1494-1575), [Giambattista] della Porta (1535-1615), Christoph Scheiner (1573-1650), [Johannes] Kepler (1571-1630), Marin Mersenne (1588-1648) and [René] Descartes (1596-1650) among others, and in the actual shop practices followed by leading makers of scientific instruments, some of which he had helped to develop. He revealed that he had learned the first rudiments of hand-polishing lenses from a former mirror maker in Venice, Domenico Rambottino, a man without any education (huomo idiota affato) but very skilled in polishing lenses for telescopes, which he supplied throughout Italy and the New World (New Indies) (pp. 238-9). He received additional theoretical and practical instruction from some celebrated instrument makers of the age such as Francesco Fontana (1580-ca. 1656) in Naples, who brought the art to such a degree of perfection that he could rightly boast to be the most “sharp-eyes man from the creation of the universe to his time” (Preface). He reserved the highest praise for Eustachio Divini (1610-85) in Rome who rose above all others in the practice of this art, which can now be called “divine” (an allusion to his last name) because of his accomplishments (Preface). Even great Princes in Italy and elsewhere, he claimed, have not disdained to use their hands in this art through which men can now scan the skies and the stars and contemplate God’s creation. And, he observed, “there are few in the world that would not need the benefits of this art before dying” (Preface). There could hardly be a more enthusiastic and eloquent celebration of the usefulness, dignity, nobility, and even “divine” function of the relatively new profession of optical scientist and practitioner.

“The preface also emphasized the practical aspects of the art. Although Manzini distilled optical theory in his chapters on light and refraction for the benefit of those more skilled in mathematics, he advised other readers that these sections could safely be skipped, because they were not necessary to become “a perfect master” (maestro). They were advised instead to imitate Divini’s career, whose portrait graces the frontispiece of his book. Divini, according to Manzini, had relied more on experience, ingenuity, and good judgment than on books to achieve his astounding results in making the best lenses and telescopes in Europe. He was, indeed, credited by his colleagues to be the “first to have perfected the making of telescopes” [Preface].

“Manzini’s detailed and extensive description of lens grinding and polishing surpassed by far earlier treatments, including those published by Della Porta in his Magia naturalis (1589) and by Giovanni Sirtori in his Telescopium (1618). His exposition is based on these and other writings and above all on personal observation and practice as he consorted and worked with top-level masters of the art. It would be impossible to distill in a few sentences the complex steps of this process, which occupies the longest section of the book (pp. 199-263) … For our purposes it is sufficient to identify the five stages in the production of lenses: making templates for the tools for grinding and polishing, producing the sets of tools for different focal lengths, the selection of the glass blanks, the grinding process and the polishing process.

“The templates were made of metal (copper, steel, pewter, lead, and preferably brass) and were constructed in pairs, one convex, the other concave, of the same radius of curvature and each set was turned to a different focal length and labeled in feet as a measure of the focal length of the lens to be ground. The pairs in each set were ground against each other to ensure the accuracy of the surfaces of the lenses … The templates were used to form the grinding tools themselves, also made in pairs. Metals were used for these tools, usually iron but preferably brass. The glass blanks were cut into disc shapes from a larger plate of glass, and several of them were fixed with cement to a convex tool or mallet, which was cemented in turn to a post for grinding. All the lenses were then ground at the same time against the tools by hand, using progressively finer sizes of washed emery to bring the lens surface to a semi-polished state. The final polishing was done on a concave cast iron shell covered with a heavy woolen cloth without its nap, which was pressed into place by working the corresponding convex brass tool on it. The pores of the cloth were then filled with enough tripoli (putty powder, calcined tin) to make its surface level.

“Manzini advised that grinding and polishing of lenses was accomplished more precisely by hand than by machine. He wrote that he had never seen a lathe or machine capable of doing what the hand could despite the claims of inventors and mathematicians. He even added with a tinge of irony that he had seen one of these mathematicians/inventors, a non-Italian (Oltremontano) residing in a leading Italian city, working “many lenses” by hand “with extraordinary diligence and patience” [pp. 159-60]. But he was not a Luddite for his text is illustrated with various grinding/polishing machines, including one of his own improved lathes, which was superior to the lathe used by Ippolito Francini (1593-1653) (nicknamed Tordo), Galileo’s skilled lens-maker. He stressed, however, the necessity that theory must be informed by practice for the production of excellent lenses following his own example by observing artisans and working with them. This experience had taught him that the final testing of the lenses be done by a person with keen eyesight, operating in a darkened chamber to observe objects at various distances through the lenses with the light being provided by candles, torches, or oil lamps (pp. 252-55) …

“From the marriage of theory and practice, Manzini evolved tables of specific ages requiring appropriate radii of curvature for spectacle lenses … He distinguished six power degrees of lenses for various ages and for cataracts: 1. 40-50, known as “common vision” (vista commune); 2. 50-60; 3. 60-70; 4. 70-80; 5. Glasses for a half cataract; 6. Glasses for the entire cataract. As had been established two centuries earlier, he recognized two degrees of myopia – “weak and short vision” (viste deboli e viste corti). He cautioned, however, that these measures were averages for there were several “middle” degrees both for presbyopes and myopes and age alone was a very imprecise determining measure. It was necessary to try different models in spectacle shops [pp. 95-105]” (Ilardi, pp. 229-32).

“The preface mentions a long list of authorities … although few of them play any role in Manzini’s directions for telescope making. Among the few that do, Kepler is by far the one most frequently cited. As we shall see, Manzini uses Kepler’s theory in many ways and discovers in the Dioptrice (1611) results that seem to suggest to him new telescope designs.

“For one thing, Manzini appeals to Kepler’s authority to back well-known basic results of telescope making, as if they gained a new status by Kepler’s demonstrations in the Dioptrice. This is the case for the claim that in Dutch telescopes lenses must stand as far apart as the focal distance of the convex objective lens or nearly; that the aperture must change according to the brightness of the observed object; or that objective lenses of great convexity require eye-pieces of great concavity. Contrariwise to what [Cherubin] d’Orleans does [in La dioptrique oculaire, 1671], Manzini never follows or repeats Kepler’s geometrical arguments closely. However, he brings Kepler in when he wants to explain some relevant optical effect. For instance, he provides a qualitative, very general explanation of vision through telescopes with two or more convex lenses grounded on proposition 80 of the Dioptrice (the upright image of a visible thing seen through a convex lens is enlarged necessarily); Manzini uses it to explain why the combinations he sets forth will produce magnified vision. In another instance, he explains why astronomical telescopes have a wider field of view than Dutch telescopes do with references to Dioptrice’s propositions 81 (in which Kepler links the distance of the eye to the focus of a convex lens to the field of view), 86 (which contains Kepler’s account of the combination of two convex lenses) and 109 (where it is proved that in Dutch telescopes the concave ocular is always located very near the focus of the objective). In other instances, Manzini uses results from the Dioptrice to ground new rules of his invention. For instance, Manzini produces a table for Dutch telescopes that gives the recommended aperture size in relation to focal length. This is complemented by a new table that determines the best concavity of the ocular in relation to apertures. Manzini’s calculations of concavities for ocular lenses involve a geometrical argument grounded on Kepler’s theoretical understanding of the role of ocular lenses and on his law of refraction. In other instances, Manzini uses results from the Dioptrice to analyse instruments that Kepler never mentions. This is the case for the microscope (with one or more lenses), whose workings Manzini grounds on Kepler’s proposition 37 in the Dioptrice.

“Kepler’s interest in ‘cryptical’ instruments [discussed in the last propositions of Dioptrice] lead him to explore the optical effects of new combinations of lenses. Manzini does not talk of ‘cryptical’ instruments, but suggests a vast array of new telescope designs in which three, four and even five lenses are combined, and whose optical properties Manzini knows in a qualitative general way thanks to Kepler’s results about ‘cryptical’ instruments. He analyses first in some detail a variation upon the basic design of the Dutch telescope in which the tube is fitted with an additional convex lens whose convexity is about ¾ that of the main objective lens and which is located about half the length of the tube. Rules for fixing the ocular are to be obtained by trial and error. This design, says Manzini, comes from experience. Manzini reveals, however, that he knows in advance its main properties because they are foretold by two propositions Kepler devoted to ‘cryptical’ instruments. The instrument will be shorter, as demonstrated in the Dioptrice, proposition 135 (it shows how to make a working Dutch telescope whose objective is of small convexity but shorter than the focal distance of the objective lens), and it will magnify less, by proposition 125 (which proves that the contiguous application of two equally convex lenses halves their focal distance). On the other hand, experience shows that images are clearer and more distinct and the field of vision is wider. Manzini fills ten pages of his book (from page 177 to 186) with recipes which seem to originate in a combination of practical knowledge and general theoretical rules provided by Kepler’s Dioptrice” (Malet, pp. 292-4).

Little is known of Manzini’s life. Born at Bologna on 5 October 1600, he graduated in philosophy at the city’s University on 22 December 1625. A student of Giovanni Antonio Magini (1555-1617), he was a member of a group of Bolognese scientists who supported Galileo. In the first volume of his Almagestum novum (Bologna, 1651), Giovanni Battista Riccioli (1598-1671) praised Manzini’s philosophical and scientific knowledge. He was in contact with many of the leading scientists of the time, including Mario Bettini (1582-1657) (with whom he performed some experiments), Bonaventura Cavalieri (1598-1647) (who was supported by Manzini in developing mathematics at the University of Bologna), and Divini. Two letters from Divini to to Manzini were published, Lettera di E. D. all' Sig. Conte C. A. Manzini. Si ragguaglia di un nuovo lavoro e componimento di lenti che servono à occhialoni ó semplici ó composti (1663) and Lettera di E. D. intorno alle macchie nuovamente scoperte nel mese di Luglio 1665 nel Pianeta di Giove con suoi cannocchiali (1666). In addition to the present work, Manzini published Tabulae primi mobilis (1626), which presented tables for the construction of astrological charts,Stella Gonzaga sive geographica ad terrarum orbis ambitum, et meridianorum differentias (1654), containing his proposal for an improved method of measuring the earth, and Le comete discorso (1665), an account of his observations of the spectacular comets of 1664 and 1665. He died at Bologna in 1677.

Albert et al 1475; BL/STC 17th-century Italian Books II, p. 530; BOA p. 137; Becker 153; NLM/Krivatsy 7389; Riccardi II 96; Wellcome IV, p. 48. Vincent Ilardi, Renaissance vision from spectacles to telescopes, 2007 (pp. 229-234); Antoni Malet, ‘Kepler’s legacy: telescopes and geometrical optics, 1611-1669’, pp. 281-300, in The Origins of the Telescope, van Helden et al (eds.), 2010.



4to (223 x 158 mm), pp. [xii], 268, [4], with full-page engraved portrait of Eustachio Divini by the Austrian artist Johann Paul Schor (1615-74), known in Rome as ‘Giovanni Paolo Tedesco,’ and the Genoese engraver Joseph Testana. Woodcut illustration of telescope on title and seventeen woodcut illustrations in text. Manuscript corrections by Manzini to text. Contemporary limp boards, uncut (boards with some wear, private catalogue number stamped in ink on last page of text). Contemporary manuscript annotations in Italian on front pastedown and front flyleaf (recto and verso), and on four inserted sheets, that on flyleaf recto giving instructions for the construction of a helioscope, others apparently explanations of weights (of lenses?).

Item #4948

Price: $15,000.00

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