German silver open faced lever observation watch Circa 1912

Silver precision watch
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A German silver open faced observation watch, model Ingeneur, made by J. Assmann in Glashütte, circa 1913. The bridge movement with a piston tooth lever escapement and gold screw compensation balance. White enamel dial with Arabic hour numerals, an outer minute track, sunk subsidiary seconds and spade hands. A plain case. Dial and case signed J Assmann Glashütte, movement signed J Assmann Glashütte i.S., case and movement with matching numbers.
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Diameter: 60 mm
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Weight: 151 g
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Signed: J Assmann Glashütte i.S.
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The Ingenieur model series was identical to the J. Assmann marine observation watch with a bridge movement. The aim was specifically to target the civilian market segment.
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In quite a few research institutes and industrial companies, these precision timepieces were in demand as tools for precise time measurement in scientific and technical work processes. For example, the Royal Astrophysical Observatory and the Royal Geodetic Institute in Potsdam owned several of these watches.
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The bridge movement used in this watch is a custom made ebauche from the Swiss company Le Coultre & Cie, which delivered it to order of the J. Assmann company from 1902 onwards. The ebauches were elaborately finished and fine tuned in Glashütte so that they demonstrably corresponded to the Glashütte rule that is still valid today.