Author(s) Derand, François
Title L’architecture des voutes...
Imprint Paris, S. Cramoisy, 1643
Localisation Besançon, Bibliothèque municipale, 11598
Subject Stereotomy, vaults
Transcribed version of the text


     François Derand was born in Vic-sur-Seille in the diocese of Metz between 1588 and 1591. He entered the Jesuit novitiate in Rouen. From 1613 to 1615 he studied philosophy at the Jesuit college at La Flèche, and he taught mathematics there from 1618 to 1621. He was ordained as a priest in 1621. From 1622 to 1629 he was in Rouen; in 1629 he was called to Paris to finish the church of the mother house begun by Brother Étienne Martellange. In 1633 he was cited in the building contract for the reredos of the high altar of the Jesuit church in La Flèche; he maintained control over the implementation directed by Pierre Corbineau, the celebrated reredos artist from Laval. In 1643, after publishing his treatise, Derand left Paris for Agde, summoned by Bishop François Fouquet, the superintendant's brother. Derand died in Agde in 1644; he is buried at the collège in Béziers.
Derand's title of architectus in building the church of his mother house does not prove that he possessed all the knowledge of a professional. On the building site itself, a practitioner assisted him constantly. He was probably only there to confer, to give ideas and projects. The only drawing extant definitely by him concerns the church of the Jesuit collège in Paris. It is not authoritative - that is the least one can say. Derand also intervened from 1622 to 1629 as præfectus fabricæ, always assisted by a practitioner, in the Jesuit church in Rouen, whose construction had begun in 1615. Perhaps his intervention was limited to covering the central nave with rib vaults, a medieval technique often resorted to by the Jesuits. It allowed them the optimal use of the masons' ability. They all mastered this technique perfectly; in addition, in the minds of the French it remained associated with the Christian past of the Eldest Daughter of the Church.
Probably because the rib vault was too well known, Derand deals only very rapidly with it in L'architecture des voûtes, his treatise on stereotomy published in 1643, his masterpiece. It is not the masterpiece of an architect, but of a scolarly mathematician, one of the founders of the science of stereotomy, the art of producing complex structures in freestone, particularly overhangs and coverings in which, through the artifice of putting in the keystone, the weight works against itself.
Stereotomy was a French specialty, as we have attempted to prove in the part of our Architecture à la française (1982) entitled "La stéréotomie, pierre de touche de la manière française". In his Premier tome de l’architecture (1567), Philibert De l’Orme was the first to publish the extraordinarily varied list of arches, vaults and matched supports which constitute a "topique" of French architecture. Derand's treatise clarifies the analysis of these works, a materialization of exercises in descriptive geometry. Modestly, Derand writes "les pratiques et autres connaissances que nous prétendons vous déduire en cet ouvrage, de prime abord et à la première vue que vous en aurez, ne produiront peut-être que des ténèbres ou si peu de lumières en votre esprit que si vous n’y prenez garde, vous pourriez vous en dégoûter bientôt". This science which the invention of the printing press had made public was in part a component of the arcanum magisterium, the masons' professional secret.
In 1642 Mathurin Jousse had published Le secret d’architecture in La Flèche, faithfully uncovering "les traits géométriques, couppes et dérobemens nécessaires dans les bastiments", Ahead of Derand by one year, it prevented Derand from being the first to publish a book entirely devoted to stereotomy. Jousse's treatise is a mediocre book, perhaps borrowed to a great extent from Derand's teaching at the collège in La Flèche, or even plundered from his manuscript of the book while in the process of being written. "Une pièce concernant le même sujet et mise au jour depuis six mois ou environ sous le titre le secret d’architecture m’a prévenu et surpris au milieu de mon impression" Derand wrote in his preface, "mais je l’ai reconnue fautive". François Le Bœuf's recent research has revealed that Jousse was not a master mason or an architect, as was believed, but a master locksmith and a merchant, a well-to-do erudite bourgeois who was among the suppliers of the collège in La Flèche. The hypothesis of copying is thus confirmed.
In his preface Derand also cites the Brouillon projet d’exemples d’une manière universelle by Girard Desargues, the celebrated mathematician. Desargues did not claim to give, as did Philibert De l’Orme, Jousse ou Derand, a "recueil de plusieurs pièces" with no connection among them, but to resolve all the particular problems of stereotomy by a sort of rule, the "manière universelle". With Desargues, technique fades out entirely behind science, whereas Derand writes, "l’on ne peut raisonnablement exiger de nos opérations une rigueur telle qu’on la recherche d’ordinaire ès matières de géométrie purement spéculative". He recommends the use of the elongated circle, which owes nothing to geometry, but everything to the practical genius of the preparer. Masons never understood Desargues' demonstration, whereas Derand's treatise appeared in all the architects' libraries.
Vaulting technique is an art. Derand insists in vain that a vault allows one to cover spaces longer than those covered by beams, that it resists fire better than framework, he recognized in vain that floors can be splendidly decorated, "néanmoins les voûtes ont toujours je ne sçay quoy de noble". Moreover Derand's vaults are decorated; Derand's ornamental style is a subject in itself. We know that he designed the façade of the mother church in Paris, today Saint-Paul-Saint-Louis, often considered the paragon of the "style jésuite" because of its ornamental overloading. He probably designed the ornaments of this church's high parts and vaults which present obvious analogies with the cartouches of the "style auriculaire" contained in the titles of the treatise's plates. Are they by Derand? Or by artists of ornamental pieces such as Jean Barbet, Pierre Collot ou Alexandre Francine working during the 1630s? Or even by Mathurin Jousse? Jousse's locksmithing belongs to the repertoire of that style, and he was active as an engraver. Is it tenable to hypothesize a collaboration between Jousse and Derand in Derand's publication which would have allowed Jousse to plagiarize Derand in his own treatise? Several different styles can be observed in the cartouches of L’architecture des voûtes. Was the auricular style progressively abandoned, or was there a simultaneous collaboration of various artists?
          L’architecture des voûtes was published in a new edition twice in the 18th century in Paris, in 1743 and 1755.

Jean-Marie Pérouse de Montclos (Centre national de la recherche scientifique, Paris) – 2009


Critical bibliography

F. Le Bœuf, "Mathurin Jousse, maître serrurier à La Flèche et théoricien d’architecture (vers 1575-1645)", In situ, 1, 2001.

F. Le Bœuf, introduction to Mathurin Jousse, Le Théâtre de l’art de Charpentier, Bibliothèque de l’architecture française, J.-M. Pérouse de Montclos (ed.), Paris, Éditions de l’Académie d’Architecture, 2003.

P. Moisy, Les églises des Jésuites de l’ancienne assistance de France, Rome, Bibliotheca Instituti Historici S. I., 1958, 12. 2 volumes.

J.-M. Pérouse de Montclos, L’architecture à la française. Du milieu du XVe siècle à la fin du XVIIIe siècle, Paris, Picard, 2001 (1st ed.: Paris, 1982).