Barometers Realm

The case of the manometer is made of nickel-plated brass, which was the standard material for precision instruments of that era, providing corrosion resistance and a neat, polished appearance. The dial is crafted from silvered brass with fine engraving; the silvering protected the metal from oxidation and gave it a characteristic light, slightly matte finish. The pointer is made of blued steel, achieving its deep blue hue through a heat treatment process that also protected it against rust.

The mechanism relies on the Vidie-type aneroid capsule, originally invented and patented in 1844 for the first mercury-free barometer. Air is introduced through a specially fitted nozzle in the case into the space beneath the aneroid capsule. Changes in pressure cause the capsule to deform, and this deformation is transmitted through a lever mechanism and a rack to move the pointer. The scale is graduated in centimeters of mercury (cm Hg), ranging from 0 to 35, corresponding to the typical range used in medical measurements such as blood pressure monitoring.

Originally, such manometers were installed in medical sphygmomanometers, especially in the early models developed according to the Riva-Rocci method combined with auscultation techniques later refined by Korotkoff. Examples of aneroid capsule-based manometers include early medical sphygmomanometers used to measure blood pressure, portable vacuum gauges and low-pressure manometers for laboratory or aviation purposes, and combined instruments such as baro-thermo-hygrometers, all based on aneroid mechanics.