two completed clocks made by Bertolla. One is a
weight-driven lantern clock typical of the 18th century, Italian style
with brass dial, plates and posts, anchor escapement, and striking
work. The dial is engraved in the usual style of Bertolla's baroque
design, and the hands are of pierced bronze. Another clock associated
with Bertolla and found in the shop, was made by his nephew, Alessandro
Bertolla, who worked in Venice after his apprenticeship with his uncle
had been completed. This clock is a regulator with a seconds' pendulum
and sweep hand on an enameled dial. The original case has not survived.

[Illustration: Figure 30.--LAYOUT OF THE WHEELWORK of a clock made by
Bertolla for His Excellency Paulo Dona, inscribed "Design No. 1."
(_Courtesy of Museo Nazionale della Scienza e della Tecnica, Milan._)]

[Illustration: Figure 31.--PENDULUM ARRANGEMENT SKETCH for an
unidentified clock found in Bertolla's workshop. (_Courtesy of Museo
Nazionale della Scienza e della Tecnica, Milan._)]

[Illustration: Figure 32.--STRIKING CLOCK SKETCH found in Bertolla's
manuscripts. (_Courtesy of Museo Nazionale della Scienza e della
Tecnica, Milan._)]

[Illustration: 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._)]

[Illustration: 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._)]

[Illustration: 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 b