SAUSSURE (Horace-Bénédict de). Essays on hygrometry. Neuchâtel, Samuel Fauche, 1783. In-4, full marbled calf binding, smooth spine decorated with title page, marbled edges (period binding). First edition, illustrated with a vignette as a headband and 2 plates hors texte in fine, one of which is fold-out. In this treatise, Saussure presents his famous hair hygrometer and discusses the effect of altitude on air temperature, hygrometry and pressure. The in-4° edition is considerably rarer than the in-8° edition published the same year. A copy in fine condition, enriched with a contemporary handwritten copy of the Mémoire sur un phénomène remarquable de météorologie, read to the Société des Naturalistes de Genève, by M. de Saussure in October 1797. Perret, n°3912 - Meckly, 167.