Horace-Bénédict de Saussure - ‎Essais sur l'hygrométrie - 1783

First quarto edition of one of the founding books of modern meteorology, which established hygrometry as an exact science, by the famous author of the "Voyages dans les Alpes", one of the greatest Swiss scholars of the 18th century. An octavo edition was published the same year.

In this very important work, Saussure (1740-1799) describes how to construct a hair hygrometer capable of measuring the level of humidity. The author also shares his discovery of how air expands and specifically becomes lighter as it becomes more humid.

"One of the most beautiful works," says Cuvier, "with which science was enriched at the end of the 18th century".

Two copper-engraved plates are bound at the end of the volume: the first depicts the hair hygrometer invented by the author and manufactured for the first time by Paul in Geneva.

Work as published, bound in interim binding. As is: loose covers, missing spine, water stains on the front cover and inside the book, visible on pages 264 to 285 and 304 to 336 (see photos).

Horace-Bénédict de Saussure, Professeur de Philosophie à Genève

‎Essais sur l'hygrométrie. I. Description d'un nouvel Hygromètre comparable. II. Théorie de l'hygrométrie. III. Théorie de l'évaporation. IV. Application des théories précédentes à quelques phénomènes de la météorologie.

Neuchâtel, Chez Samuel Fauche Père et Fils, 1783.

Quarto of XXIV - 367 pp.