Right on Time

Em­i­lie Yabut-ra­zon

Hong Kong Tatler - - Style -

t the stroke of mid­night, the date and day ap­pear si­mul­ta­ne­ously in the two win­dows on the dial of the Rolex Oys­ter Per­pet­ual Day-date. When the watch was launched in 1956, this in­stan­ta­neous si­mul­ta­ne­ous jump was a world first for wrist­watches. Dubbed the “mir­a­cle at mid­night,” the Rolex was the first model to spell the day of the week in full, clearly leg­i­ble at 12 o’clock and avail­able in 26 lan­guages. The si­mul­ta­ne­ous chang­ing of the date in­di­ca­tion, re­quired a mech­a­nism of suf­fi­cient ac­cu­racy and en­ergy to move both the day and date discs at pre­cisely the same mo­ment, but with an ef­fec­tive brake to en­sure they only ad­vanced a day at a time.

The move­ment re­quired two alu­minium discs, one above the other, the lower disc for the date and the up­per for the day. With 31 and seven teeth re­spec­tively, the discs were driven at their cen­tre by two in­de­pen­dent, star-shaped wheels con­nected to snail cams that ac­cu­mu­lated en­ergy as they turned dur­ing a 24-hour pe­riod. At mid­night, the cams’ en­ergy was re­leased and gave the cor­re­spond­ing tooth the im­pulse needed to push its star and, in turn, the disc. This in­ge­nious en­gi­neer­ing feat, which was then cov­ered by four patents, also of­fered the ad­van­tage of spread­ing en­ergy con­sump­tion evenly over a com­plete 24-hour cy­cle. This ef­fec­tively pre­served the pre­ci­sion of the cer­ti­fied chronome­ter’s move­ment.

Al­most six decades later, Rolex has in­tro­duced a new gen­er­a­tion of its Day-date watches equipped with the same mech­a­nism, but it’s been op­ti­mised to take time­keep­ing per­for­mance to a new level. The new cal­i­bres of­fer up to 50 per cent more re­serve power, a 15 per cent im­prove­ment in ef­fi­ciency, and are tested to a higher de­gree than a chronome­ter cer­ti­fied by the Swiss Of­fi­cial Chronome­ter Testing In­sti­tute (COSC).

The lat­est mod­els of the Day-date and

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