This impressive skeletonised calendar watch was made according to Thomas Dunn’s Patent. The provisional specification of Dunn’s Patent was dated 17th May, 1861 and numbered 1257, with the patent itself filed on 15th November, 1861. Within the patent it is written: "Watches are formed with glass cases over the inner works to keep out the dirt, and the inner framework is so lightened that nearly the whole of the works may be seen at any time, in order to detect small particles of dirt, before they injure the works
." A third part of the patent refers to the fitting of a "double shank working on a swivel"
to watches "so that a neck guard and a short guard may be used together."
This pendant, with a double bow and shown in figure 1 of the patent, is not incorporated in the present watch. The present watch, however, has a calendar whereas the patent does not. While the patent is without the engraving, other features and layout of the movement are identical.
A similar skeletonised movement by William Wood, also made according to Dunn’s patent, was examined by the Antiquarian Horology's Scottish section on 4th March, 1987 at Lauriston castle, Scotland. For a report of the visit, an illustration of the movement and part of the Dunn patent, see: Antiquarian Horology, No. 6, Vol. 16, June 1987, pp. 593-594, figs 6 & 7.