Arnold & Son Instrument DBS Equation Sidereal

p150Arnold & Son is celebrating the work of watchmaker John Roger Arnold with the newly unveiled Instrument DBS Equation Sidereal. The initials “DBS” stand for the watch’s two major complications, “double balance” and “sidereal time”(a time scale based on the rate of the Earth’s rotation relative to the stars, rather than the sun). The watch is a tribute to two watches (Nos. 1 and 2) made by John Roger Arnold that showed mean solar and sidereal time on two separate subdials. Arnold created those two watches between 1796 and 1799.

To guarantee the precision of the sidereal time display on the DBS, Arnold & Son created a completely new movement with a double barrel/gear train and double balance/escapement running at different speeds that enables the watch to display mean solar time and mean sidereal time simultaneously.

The DBS Equation Sidereal features three subdials on its silvery-white and opaline dial. Sidereal time is displayed on the left subdial and mean solar time on the right. A subdial at 12 o’clock indicates the equation of both times on a 24-hour basis, showing the difference between mean solar time and sidereal time. The long central running seconds hand is for the solar time. The two barrels are wound using the crown on the right, but each time display is set separately using the crowns on the left and right so that neither of the displays is changed by accident.

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