Figure 33.—Fifteen-day striking clock sketch, inscribed "Design No. 3," found in Bertolla's workshop. (Courtesy of Museo Nazionale della Scienza e della Tecnica, Milan.)
Figure 34.—Dial plate of a brass lantern clock made by Bertolla at the age of 80. (Courtesy of Museo Nazionale della Scienza e della Tecnica, Milan.)
Figure 35.—Movement of brass lantern clock produced by Bertolla at the age of 80, showing details of movement and double bell. (Courtesy of Museo Nazionale della Scienza e della Tecnica, Milan.)
One of the most interesting of Bertolla's clocks, and probably the last one which he produced, was found in his workshop. This timepiece indicates the hours, minutes and quarters by means of a single hand or index. The weight-driven clock strikes the hours and quarters on two bells with a single hammer. The chapter ring, which is soldered to the dial plate, is marked for the minutes on the outer rim and for the four quarters inside it. Over the center of it, is a semicircular opening in the dial plate through which is visible a revolving disk attached behind the dial plate. This disk is marked with the hours and revolves from right to left, the current hour being indicated by a projection from the minute ring. The brass dial plate is engraved with simple floral designs in the corners and around the broken arch. There is no comparison between this crude and simple decoration and the extremely fine quality of the engraving on the dial plate of the Borghesi clock, for instance. In the center of the dial plate is engraved the following: