Marc Antoine LAUGIER, Essai sur l'architecture; [bound in suite] Félix-François d'ESPIE, Manière de rendre toutes sortes d'édifices incombustibles ou Traité de la construction des voûtes, faites avec des briques et du plâtre, dites voûtes plates et d'un toit de brique, sans charpente appelé comble briqueté, Paris, Duchesne, 1753& Paris, Duchesne, 1754 1 vol. in-12° : xvivp., 1f. (table), 293p. 9f, 2f. folded manuscript reading notes dated 1763; 80p. 2 large folding plates. Bound in full contemporary calf, lower jaw cracked but not detached. The binding features an undoubtedly revolutionary "gumming" of the gilded coat of arms at the foot of the spine, replaced by a piece adorned with a simple fleuron. Rare reunion of two works published a year apart by the same publisher. First edition of Laugier's first treatise, without the plates that only appear in the following edition. Abbé Laugier's work is a classic by this famous French amateur, who along with Blondel was one of the most influential architectural theorists of the Age of Enlightenment. Laugier's Essai, which advocates strict principles for the use of architectural elements, is considered a turning point and an important impetus for the change in taste of the period. The Comte d'Espie's work develops his theory on the construction of Roussillon, Saracen or Catalan-style vaults, enabling the replacement of framed ceilings and roof timbers with fireproof brick and plaster vaults. He used this technique in his private mansion in Toulouse, before it was adopted throughout Europe. Provenance: label on upper flyleaf "du fonds de Mathevon, libraire, quai du Rhône, près le Bon-rencontre, Lyon", stamp "Raymond Nöel" above this label and on both title pages.