Mémoire sur la recherche des moyens que l'on pourroit employer pour construire de grandes Arches de pierre de deux cents, trois cents, quatre cents, & jusqu'à cinq cents pieds d'ouverture, qui seroient destinées à franchir de profondes vallées bordées de rochers escarpés

One large folding engraved plate. 1 p.l., 44 pp. Large 4to, cont. half-sheep & marbled boards (minor foxing). Paris: de l'Imprimerie Nationale, 1793. First edition. "This Mémoire on his monumental concept of masonry bridges with spans of 200 to 500 feet is the rarest of all Perronet's works. Inspired by some of the great spans of the past (Verona 150ft or Pontypridd 178ft) he asks why, 'dans un siècle ou les sciences & les arts ont fait de si grands progrès, ne pourroit-on pas se flatter d'en établir solidement qui ayent encore plus d'ouverture?'... "Perronet is fascinated by the challenge of building such huge spans, particularly that of 500ft, and three main problems are considered. The first of these is the choice of stone and here he draws on his considerable knowledge, derived from experiments carried out on the strength of stone from quarries all over France, as well as citing his experience during the construction of the Neuilly bridge. The other two problems concern the design of centring for such a gigantic arch and the method of dismantling it after the keystone has been put in place. Here, too, he brings his unparalleled experience to bear in his design but cites the theoretical works of Parent, Buffon, Musschenbroek and Couplet to prove its feasibility... "The spandrels of his arch were to have been pierced by three voids, reminiscent of the Pontypridd bridge, and the design and construction of these are discussed, together with the retaining walls, the fill of the haunches behind the spandrel walls etc. Altogether a remarkable work (illustrated with a single magnificent plate)."-Elton, Cat. 5, 42. Perronet (1708-94), was the founding director of the École des Ponts et Chaussées and developed the classical stone arch bridge to its ultimate perfection. The fine and very large plate depicts the projected 500 foot bridge and has an engraved flap pasted over a portion of the image to show before-and-after effects. Very good copy. ❧ D.S.B., X, pp. 527-28. Picon, French Architects and Engineers in the Age of Enlightenment, pp. 167-68.