Marine chronometer with electrical contact mechanism, extremely rare

Ca. 30 x 16 x 15 cm, wooden box, 2 chronometers with brass cases, spring detent chronometers, dials with power reserve indicator, No. 9759, with movement intact, extremely rare. It is believed that G.U.B. produced 35 of these double chronometers, which were used to compare Greenwich Mean Time with sidereal time, and it is assumed that 25 of these were converted into standard marine chronometers, leaving only 10 original examples in existence!

Estimation:-

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