Longines. A fine and rare stainless steel Siderograph double split-second chronograph deck watch

SIGNED LONGINES, AERO-N. NO. 6425252, CIRCA 1939

细节

Longines. A fine and rare stainless steel Siderograph double split-second chronograph deck watch
Signed Longines, Aero-N. No. 6425252, circa 1939
With Marine Nationale cal. 21.29, nickel-finished jewelled lever movement, the two-tone silvered dial with inner ring calibrated for 360 degrees in black with black hand doing a complete rotation in 23 hours and 56 minutes, inner red ring calibrated for 10 units with corresponding red hand, outer blue ring calibrated for 60 units, up and down indicator, the large circular case with chronograph button in the band, the back secured by three screws, case, dial and movement signed
94 mm. diam.

拍品专文

This watch is accompanied by photocopies of Longines Siderographe Ref. 6081 description and operating instructions in French and photocopies of Heinrich Pavel's article Der Siderographe, from Alte Uhren und moderne Zeitmessung 5/86 edition.

The Siderograph is named after the expression 'sidereal', or 'star time', and was originally developed for astro-navigation.

The sidereal time watch is an ordinary watch that is sped up by adjustment of the mechanism so that it will indicate 24 hours of sidereal time for every 23 hours and 56 minutes approximately of solar time. A Siderograph is a combination of a clock and a navigation instrument and keeps a reference time equivalent to the time at Greenwich longitude.