Pair–case watch, 1682–83
Movement by Thomas Tompion (English, 1638–1713); inner case and dial by Nathaniel Delander (English, recorded 1668/69, died ca. 1691 or before 1705)
Outer case: leather with gold studs monogrammed RWR surmounted by a coronet (unidentified); Inner case and champlevé dial: gold, with blued steel hands; Movement: gilded brass, steel, partly blued, and silver; Diam. of back plate 1 7/16 in. (3.6 cm)
Gift of J. Pierpont Morgan, 1917 (17.190.1489ab)
This extraordinary watch records hours in Roman numerals and minutes in Arabic numerals on its chapter ring, with separate, concentrically mounted and easy-to-read hands for the hours and minutes. More surprising for its date, the watch has a separate chapter ring for seconds at the VI o'clock position of the dial. Still more surprising, it has a remarkably early stop mechanism that can be activated at will in order to measure short intervals of time. The watch exploited the relatively new invention of the balance spring applied to a venerable verge escapement, an application that increased the accuracy of the movement to a new level of precision that is reflected in the calibration of its dial. The clarity of the design of the dial is perhaps in part the contribution of Nathaniel Delander, one of Tompion's preferred casemakers. The fine engraving and matte gold on the dial is certainly his contribution to its beauty.