Figure 25. — Interior of Bertolla's workshop, showing details of paneling and floor case with 

 Bertolla manuscripts. (Courtesy of Museo Xa-jonah delta Scienza e delta Tecnica. Milan.) 



Bertolla. The tall-case clocks are narrow and range 

 in height from 7% feet to 10!.> feet. The cases had 

 this excessive height in order to obtain the greatest 

 fall tor the month and year movements which Bertolla 

 constructed. For the weight assembly, he substituted 

 a drum wound with a key at the point of the driving 

 wheel in place of the customary pulley. The addition 

 of an intermediate wheel augmented the drop of the 

 weight. 



Bertolla's movements were solidly constructed from 

 well-hammered brass and iron. I le favored the recoil 

 anchor escapement in his clocks and the Graham 

 dead-beat anchor escapement with a seconds' pendu- 

 lum. The escapement was not always placed in the 

 traditional location in the upper center between 

 the plates. Bertolla occasionally displaced the pendu- 

 lum to one side, to the lower part of the movement 



or placed it entirely between two other small plates. 20 

 He utilized every type of striking work, including 

 the music-box cylinder common in the clocks of the 

 Black Forest and the rack and snail. Bertolla most 

 frequently employed the hour strike and grand 

 sonnerie. He often used a single hammer on two bells 

 of different sound with the rack and snail. An ex- 

 ample of this type is the clock he produced at the age 

 of 80. To achieve the necessary axis of rotation 

 for the hammer, which is perpendicular to the plate 

 when it strikes the hours, it moves to an oblique posi- 

 tion and displaces one of the two long pins in an 

 elongated opening. 

 Bertolla's dial plates were generally well executed, 



20 Piamontk, La Nauru Descrilta «/ Viaggiattore. 



62 



BULLETIN 240: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



