Important German silver half-second deck chronometer Circa 1914

Silver open faced deck chronometer
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An important German silver open faced half-second deck chronometer, circa 1914. Delivered to the Imperial and Royal Hydrographic Institute in Pola in 1914. Extremely rare chronometer movement, diamond endstone, pivoted detent escapement in the manner of Moritz Grossmann, helical hairspring, screwed gold chatons, finest engraved balance cock. Silvered and grained dial with Roman hours and outer minute divisions, original hands. Engine-turned case with gold hinges. Dial and movement signed and numbered, case numbered, case and movement with matching numbers. Comes with an Extract from the Archives.
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Diameter: 63 mm
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Weight: 188 g
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Signed: A. Lange & Söhne Glashütte bei Dresden
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These extremely rare Glashütte chronometers were manufactured for maritime purposes. The watches were constructed with 14400 half-oscillations in one hour, so that the second hand is able to make half-second jumps. All have a pivoted detent escapement, which was built in two versions: as a chronometer escapement in the manner of Berthoud and as a chronometer escapement in the manner of Julius Grossmann with an additional safety lever to prevent the escape wheel from running through after removing the balance wheel. 
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According to the Lange & Söhne archives, this piece was part of a delivery of 20 half-second deck chronometers No. 64861-64880 to the Imperial and Royal Hydrographic Institute in Pola.