According to the Archives of the Uhrenmuseum Glashütte, the present marine chronometer, featuring the rare lever escapement, hence the designation "Ankerchronometer", was sold to the Kriegsmarinewerft, Wilhelmshaven (military navy wharf) on 27 September 1940 for the amount of 920 Reichmarks. It is part of a small series of only around 430 examples of this type ever made.
Around 1935, the German Hydrographic Office commissioned A. Lange & Söhne with the development of a going barrel lever escapement chronometer, most likely in connection with the launch of the small high speed warship, the E-Boat.
The movement presented by the celebrated German maker had an integral balance wheel by Richard Griessbach with a steel cylindrical balance spring and a power reserve of 35 hours.
The chronometers were in production from 1936 to 1942 and made in two series: the first with a brass lever and a balance wheel with a diameter of 20 mm., serial numbers 1001 to 1164, the second numbered 1165 to 1430 (including the present lot) with a beryllium lever and an 18 mm. balance wheel.
A similar lever chronometer, number 1230, is described and illustrated in A. Lange & Söhne - eine Uhrmacher-Dynastie aus Dresden by Reinhard Meis, p. 289.
The designation Ankerchronometer (lever chronometer) appears in A. Lange & Söhne books around 1882, starting with a pocket chronometer with serial number 12434.
The particularity of these "Ankerchronometers" is the extremely large balance resulting in more precise timekeeping corresponding to the rates required for a chronometer, thus the name. For an additional sum (25 Marks in the beginning) the watches would be submitted for trial at the Observatories in Leipzig or in Hamburg and could obtain a rating certificate.