'Tri-Compax' calendar chronograph wristwatch, c 1955-1960.
© Science Museum / Science & Society Picture Library
Wristwatch in a gold case made by Universal of Geneva, Switzerland. On the left of the main dial is a subsidiary seconds dial, directly opposite is a minute recording dial, at the top, the date and phases of the moon are shown, and at the bottom there is a dial that records the hours. The two windows on either side of the date and moon phase dial show, on the left, the day of the week and, on the right, the month of the year. Universal first introduced the 'Tri-Compax' calendar chronograph in the mid 1940s and continued the line with various construction modifications until the end of the 1970s.