RIVARD, Dominique-François. Traité de la sphère, suivi d'un Traité du calendrier. Published in Paris by Desaint et Saillant in 1757. In-8 format. Full brown marbled basane, spine ribbed and decorated with double floral fillets, title in gold lettering in a gilt cartouche, speckled edges. Contemporary binding. IV and 156 pages; 84 pages, 3 folding plates of engraved geometrical figures for the Traité de la sphère and a folding table for the Traité du calendrier. Engraved headbands, ornamented initials. Minor rubbing, minor worm damage to second board. A few period annotations in the margins, on a leaf at the end of the volume and after the table of contents. Fresh interior. Third edition of this treatise by the mathematician Dominique-François Rivard (1697-1778), on the movements of the celestial sphere and the manner in which they are observed from the earth, with illustrative geometrical figures. It is followed by the Traité du calendrier, illustrated with several tables in the text and a folding table of "epactes des nouvelles et pleines lunes pour toutes les années depuis 1700 jusqu'à 2700". Handwritten bookplate on title. A working copy in its original binding in fine condition.