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brass, glass, nickel silver, steel, wood
Before us is a Compact Maxant Barograph dating to approximately 1980, manufactured by the French scientific instrument maker Leon Maxant. The instrument is housed in a rectangular protective case with transparent sides, mounted on a substantial pedestal.
The case has a strict geometric form and is made of Honduran mahogany (Swietenia macrophylla), a wood long valued in instrument making and fine furniture production for its stability, density, and refined texture. The warm golden-brown tone of the wood is enhanced by a clear varnish that reveals the characteristic soft figure of the grain.
The upper part of the case is fitted with a cast brass carrying handle, allowing the instrument to be easily transported. On the side of the case lid there is a small brass latch that secures the lid in the closed position. The lid is constructed so that all four sides contain glass panels, providing a complete view of the mechanism from every direction and allowing unobstructed observation of the recording process.
The barograph stands on a solid pedestal made of sapele (Entandrophragma cylindricum), distinguished by its more pronounced wavy grain and characteristic copper-brown tone. The base provides stability to the instrument while creating a visual contrast with the more restrained texture of the mahogany case.
Inside the case is a classic aneroid barograph mechanism.
The central element of the system is a cylindrical drum, within which a clockwork movement is installed, providing a weekly running period. The drum slowly rotates around its axis, carrying with it the paper recording chart mounted on its surface.
The paper chart is secured to the drum by means of a brass retaining clip, which holds it precisely in position. The chart bears a printed coordinate grid that allows the changes in atmospheric pressure to be recorded over the course of a week.
The measuring element of the instrument consists of a stack of three aneroid capsules made of nickel silver. Each capsule is a sealed corrugated metal chamber containing an internal spring that prevents the walls from collapsing completely.
Under changes in atmospheric pressure, the capsule walls deform slightly—compressing when the pressure rises and expanding when it falls. These extremely small movements are amplified by a lever transmission system, which converts them into a larger mechanical displacement.
This motion is transmitted to a long metal arm, at the end of which a recording pen is mounted. The pen touches the rotating chart and continuously traces, in ink, a graph of atmospheric pressure changes over time.
In this way the instrument automatically produces a barogram on the chart—a continuous record of pressure variations throughout the week.
The compact Maxant barograph represents a characteristic example of mid-twentieth-century French meteorological instrumentation, in which a precise mechanical instrument is combined with a carefully crafted wooden case. Its transparent construction allows the operation of the mechanism to be observed, transforming the instrument not only into a scientific recorder of atmospheric pressure but also into a striking object of applied engineering aesthetics.
