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Object Overview
This Precision Aneroid Barometer, manufactured in 1995 by the renowned German brand Fischer, is a high-precision instrument designed for measuring absolute atmospheric pressure for scientific purposes (in particular for meteorological stations) and for navigation. The barometer comes in a lockable protective case made of beechwood, equipped with a handle. The total weight including the barometer is 1.4 kg.
The barometer itself is crafted from an ultralight aluminum alloy and features a thin chromed bezel holding a rather thick mineral glass. Mounted on the glass is a trend indicator hand with a knurled chromed knob.
The 125 mm dial, made of aluminum alloy, carries a concentric barometric scale: calibrated on the inner ring in millimeters of mercury, ranging from 680 to 800, and on the outer ring in hectopascals, ranging from 900 to 1060.
The indicating hand is a long, slender blued-steel lever with a brass bushing in the center for attachment to the movement’s axis. The pointing end is not the traditional sharp tip but instead takes the form of an elongated rectangular outline — a small open frame. The opposite end serves as a counterbalance, widened and slightly rounded to offset the weight of the hand and prevent distortion.
6488
self-elastic stacked capsule movement
aluminium, beryllium, chrome, copper, glass
The barometer operates on five sensitive aneroid capsules, stacked one upon another, transmitting their movement to a stable, well-balanced lever mechanism and then onto the toothed sector of the rotating pointer shaft. The use of a spiral spring prevents any play in the gear engagement.
The aneroid capsules are made from a special alloy (likely copper-beryllium) and are self-sustaining in their elasticity. Such capsules are also referred to as “self-springing,” since unlike conventional designs they have no internal or external springs to counterbalance the stretching of their walls; here, elasticity is achieved solely through the properties of the alloy.
The sensitive element is highly practical, resistant to aging and elastic after-effects. Temperature errors of both the aneroid and the frame are compensated by a bimetal mechanism within the range of –40 °C to +40 °C. The transmission lever system is well dynamically balanced. The transfer to the pointer axis is carried out by means of a small driving wheel and a segment furnished with extremely fine teeth.
On the instrument’s case there is an inventory number of the NMi organization, as well as calibration marks from the same company.
The Nederlandse Meetinstituut, or NMi, is a historically significant organization in the field of metrology in the Netherlands. Its origins go back to the 19th century, when the country maintained a state service of weights and measures known as IJkwezen, responsible for the calibration and inspection of measuring instruments. In 1989 this service was privatized and transformed into a joint-stock company, NMi N.V., which consisted of several specialized divisions. Among them was the NMi Van Swinden Laboratory, which served as the national standards laboratory, alongside companies dealing with certification and inspection of measuring devices within the framework of legal metrology. Later the structure was reorganized, and in 2009 the national laboratory was renamed VSL (Van Swinden Laboratory), becoming the official custodian and developer of the Netherlands’ national measurement standards. At the same time, the NMi brand continued to operate in the field of legal metrology and certification, where the organization remains an independent expert in testing, inspection, and conformity assessment of scales, meters, fuel dispensers, and other measuring instruments under European directives. The NMi label on the barometer indicates that the instrument was once part of the institute’s inventory and used in its work as a reference or standard device for calibrations, which adds historical significance and documents its connection to official metrological practice in the Netherlands.