VALENCIENNES, Pierre-Henri de. Élémens de Perspective Pratique: à l'usage des artistes, suivis de Réflexions et conseils à un élève sur la peinture, et particulièrement sur le genre du paysage. 4to. A Paris, chez l'auteur, Desenne, Duprat, an VIII. [1799/1800]. [1 ff] half-title, title-page, xii (contents), xxix (avant-propos et préface), [3]pp, errata et avis au relieur., 644pp., 36 folding engraved plates. A very good copy in original mottled calf, gilt decorated spine with red morocco label. Some slight surface wear to the spine, and small ‘thumb-print’ size water mark to the blank leading edge of a number of the plates. Old mark on the facing versos of two plates, but with very little show through. An important and highly influential treatise on the development of the plein air landscape sketch. Valenciennes’ treatise became in effect “the bible for Neo-Classical landscape painters in 19th century France. [His] own Italian sketches... anticipate Corot in their qualities of informal composition, free brushwork and brilliant observation of the phenomena of nature... [and] Corot often turned to Valenciennes ideas throughout his career.” Later in the century Camille Pissarro specifically recommended to his son Lucien that he should study this treatise on classical landscape by Valenciennes. see: M. Clarke. Corot and the Art of Landscape, 1991.