Author(s) Bullant, Jean
Title Recueil d’horlogiographie...
Imprint Paris, V. Sertenas, 1561
Localisation Paris, Ensba, Les 130
Subject Gnomonic, Sundials


     We owe one of the very first books printed in French- if it is not the first in its scope and its permanence- to Jean Bullant, architect of the Constable Anne de Montmorency, dealing with the use and manufacture of sundials. “Nuls par cy devant n’en ont escrit en nostre vulgaire” he writes in his dedication, which is almost true. His book on horology (he also uses the word horlogiographie) was printed in Paris in 1561 by Jean Bridier for Vincent Sertenas. The author paid to have it printed.
There were multiple reasons prompting Jean Bullant to undertake the project of writing this first book. The first was that with the death of Henri II he was denied the post of controller of the king’s buildings and, for the moment, serving only Constable Montmorency, he did not wish to “to waste his time in idleness”, as he wrote in his subsequent treatise on architecture. The second reason is that following the example of Vitruvius, his major cultural reference, horology seemed to be a natural subordinate to architecture. The third one is that on this subject there were a large number of writings that he could refer to and even copy. In his dedication to the duc de Montmorency, peer and constable of France, Bullant indicates that his book is “tiré par la pratique du compas des autheurs qui par cy devant en ont escrit, comme Sebastien Muster, et le très-excellent, et très-docte mathématicien Oronce Finé”. In fact Sebastian Münster (1489-1552), a German cosmograph, who taught mathematics, geography and Hebrew in Basel, was the originator of the treatises on modern gnomonics. In 1531 in Basel, he brought out the Compositio horologiorum, in plano... et variis quadrantibus, in 1533 the Horologiographia, and then in 1551 the Rudimenta mathematica.
Oronce Fine (1494-1555), the first one to hold the chair of mathematics in the Collège royal founded by François I, incontestably influenced Bullant, who might have attended the very popular courses given by the professor at the royal school. Oronce Fine published his Protomathesis in Paris, in 1532, which includes a study on the art of making solar clocks (De solaribus horologiis et quadrantibus libri IIII) which Guillaume Cavellat published separately in 1560. If, according to the historian of science Jean-Étienne Montucla (Histoire des mathématiques, Paris, H. Agasse, 1799-1802), “Munster is sometimes mistaken, but Oronce Fine very frequently”, Jean Bullant made the very judicious choice to borrow from the first rather than from the second. Among the diagrams in his treatise, many can be found in the Rudimenta mathematica, some were borrowed from the De solaribus horologiis and others are common to both treatises. For example the large illustration “of the clock under the equator” (page 34 of Bullant’s treatise) comes from page 40 in Fine (ed. in 1560) and from page 109 in Munster (ed. in 1551). Moreover Munster’s and Fine’s books are written in Latin, and that was the fourth reason prompting Bulland to write. He wanted to write a book in French, for not only “was he not Latin” but also he was concerned to write “for the profit and usefulness of artisans and people who use a compass”. And these artisans were still numerous in spite of the considerable progress in mechanical clock-making at the end of the 16th century. Their job was to draw sun dials in situ or to manufacture them in the workshop, for various latitudes. As for Bullant, he “for a long time has made the proofs of these quadrants and clocks”. Thus he wrote a practical treatise on horology and left “the great (theoretical) secrets of the aforementioned quadrants to those who are more curious”. He uses simple instructions for construction, linked to diagrams with few technical terms. When he offers calculations he presents them in algorithm form and gives examples of them by varying one parameter. For example, in chapter 28, in order to determine the latitude of a place (the height of the Arctic pole at that place), he gives several examples of calculations by varying the date of observation of the sun at noon.
The first chapter, very much inspired by eébastian Münster, describes the way to construct the basic triangle of which one side would bear the style whose shadow determines the hour on all sorts of dials : horizontal, vertical, etc. To construct this, Bullant marshalls an essential fact : the latitude of the place containing the dial ; for it is only in the next-to-last chapter of the book that he gives the way to calculate it. Likewise in the following chapters, which examine one by one the different positions in the space of a plane dial, in order to determine the lines indicating the hours, he uses the meridian whose geometric determination is described only in the last chapter. Therefore the composition of the collection does not observe a very rigorous internal logic. Nevertheless, the whole book is far from being rambling. Bullant has classified the problems. First, the decision of the place for the style or “gnome” (ch. 1), then, the lines indicating the hours (ch. 2-15), and finally, the placing of the twelve signs of the zodiac (ch. 16-21). Having done this, he describes several designs of a universal sundial allowing one to tell time in all places (ch. 22-24). In these chapters (and the two following ones) Oronce Fine’s influence is predominant. For example, “the illustration demonstrating the description of the quadrangular clock” on page 99, comes from the one on page 179 of Oronce Fine’s treatise (ed. 1560). It only remains for Bullant to deal with nocturnal hours, either by using “the moon’s rays”, or by plotting the stars. This is the subject of chapters 25 to 27.
Bullant, as an architect, could have expressed his opinion on the aesthetics of sundials, on their insertion in an architectural ensemble or on the way to render their details legible and the way to prepare walls, but he limited his subject out of modesty and a concern for effectiveness. By giving artisans “beginning, input, and knowledge” in horology, he contributed to disseminate scientific and technical facts in a society in the midst of important economic and social mutation (like Bernard Palissy, another protégé of the constable, who published his Recepte véritable in 1563). Jean Bullant, a theoretician of architecture, one of the best “sectarians of Vitruvius” according to Fréart de Chambray’s expression, must also be considered an erudite person who was on the same wavelength as the cultural reality of his period.
In 1562 Bullant signed a publisher’s agreement with Guillaume Cavellat, who published that year the architect’s little treatise on geometry followed by his treatise on horology. He bought six hundred copies of it from Bullant. The two treatises were published again, together, in 1564 by Guillaume Cavellat. His widow published the collection on horology separately in 1598 and the two treatises together in 1599. Finally, in 1608, their daughter Denise brought out a new edition of Bullant’s geometry and practical horology enlarged by texts by Oronce Fine and Pierre Appian.

Jean-Pierre Manceau (Tours) – 2009

Critical bibliography

J.-P. Manceau, "La place des mathématiques dans les écrits de Jean Bullant et Philibert De l’Orme", Journal de la Renaissance, 6, 2008, pp. 161-172.

P. Renouard, Imprimeurs et libraires parisiens du XVIe siècle, Fascicule Cavellat, Marnef et Cavellat, Paris, Bibliothèque nationale, 1986, p. 159, n° 186.