Ensayo de una memoria sobre un nuevo método de medir las montañas,: por media del termómetro, y el agua hirviendo: seguida de un apéndice Que contiene algunas observaciones muy importantes y útiles para la mejor inteligencia de dicha Memoria.

Burdeos: Imprenta de Lawalle Jóven y Sobrino,, 1819. Discovering the hypsometric principle First edition of the posthumously published work in which Caldas describes his principal scientific achievement, the discovery of a method for measuring altitude by the boiling point of pure water. Caldas (1768-1816), a self-taught scientist - and a lawyer and military engineer - from Popayán, New Granada, independently discovered the hypsometric principle and in 1801 constructed the first hypsometric thermometer. Later that same year he met Alexander von Humboldt, who had heard of Caldas and was impressed by the quality of his work given his extreme academic isolation. "Humboldt trained Caldas in many scientific methods and introduced him to new instruments; when the group travelled to Chile Humboldt began to teach him botany, which would continue to be his focus for many years" (NHM). Caldas went on to become director of the Astronomical Observatory of Santa Fe and to establish El Semanario, the first weekly geographical periodical in the Viceroyalty. During the Spanish American Reconquista he was executed by firing squad aged 48 for his involvement in the fight for New Granada's (modern-day Colombia's) independence. Quarto (230 x 185 mm). Contemporary dark brown sheep, smooth spine backed with lighter brown sheep, new endpapers. Folding engraved plate of thermometer facing p. 20, tables to text. Without the half-title. Extremities lightly worn, a few scuffs to boards, front endpapers a little tight causing some stiffness in hinge, three discreet paper repairs to gutter of title page, the contents generally crisp and clean with just a few neat pencilled marginal notes and a few instances of faint foxing. A very good copy. See Natural History Museum's biography of Caldas, JSTOR Global Plants database.