Exceptional Right-angle Siphon Barometer By Guieu Of Lyon – 19th Century

A rare and unique mercury siphon barometer, signed “Barometer by Guieu in Lyon”, most likely dating from the first half of the 19th century, around 1835–1855.

At first glance, this instrument intrigues with its entirely unusual design. Unlike the traditional vertical models typically encountered, this one features a spectacular L-shaped design, allowing for a long reading column while maintaining a particularly elegant wall-mounted format. This design, which is as technical as it is aesthetic, remains extremely rare.

The original glass tube fits perfectly into the wooden frame and draws the eye down to the lower reservoir. The weather labels, entirely hand-painted—“Heavy rain,” “Rain,” “Variable,” “Fine weather,” “Very dry”—as well as the scale in millimeters of mercury—attest to exceptionally meticulous craftsmanship.

The instrument is signed Guieu in Lyon, a name that is today virtually absent from the specialized literature on 19th-century French manufacturers of scientific instruments. Despite extensive research in manufacturers’ directories and accessible collections, no other identical barometer signed by this craftsman has been found. This lack of documentation supports the hypothesis that it was a limited-production piece made by a now-forgotten workshop in Lyon, or an instrument produced in a very small batch.

Given its design, signature, and unusual nature, this piece is far more than a mere decorative object. It is more reminiscent of an instrument intended for a scientific cabinet, a pharmacy, an educational institution, or an optician’s workshop than a traditional parlor barometer.

The piece as a whole displays a magnificent antique patina, true to its history, which fully contributes to its authenticity.

An unusual piece that will appeal equally to collectors of scientific instruments, enthusiasts of 19th-century curiosities, and those passionate about the history of science.

An extremely rare opportunity to acquire a signed Lyon barometer, as no comparable example has been found to date.