94 CHRONOMETERS. 



portion : the count-wheel commonly goes round 

 once in twelve or twenty-four hours ; the detent- 

 wheel moves round every stroke the clock strikes, 

 or sometimes but once in two strokes : wherefore 

 it follows, that, 2. as many pins as are in the pin- 

 wheel, so many turns has the detent-wheel in one 

 turn of the pin-wheel ; or, which is the same, the 

 pins of the [pin-wheel are the quotients of that 

 wheel divided by the pinion of the detent-wheel. 

 But if the detent-wheel move but once round in 

 two strokes of the clock, then the said quotient is 

 but half the number of pins. 3. As many turns of 

 the pin-wheel as are required to perform the strokes 

 of twelve hours, (which are 78,) so many turns 

 must the pinion of report have to turn round the 

 count- wheel once ; or thus : the quotient of 78 

 divided by the number of striking pins, shall be 

 the quotient for the pinion of report and the count- 

 wheel ; and this is in case the pinion of report be 

 fixed to the arbor of the pin-wheel, which is com- 

 monly done. An example will make this easy; 

 gHgfg the locking-wheel being 48, the pinion of 

 report 8, the pin-wheel 78, the striking 



fiixdr n P ms are *^» a so °f tne rest * Note, also, 

 0)00(10 that ^g diyided b y 13 gives 6j the q ll0t i ent 



? ^ of the pinion of report. As for the 

 warning-wheel, and fly-wheel, it matters little 

 what numbers they have ; their use being only 

 to bridle the rapidity of the motion of the other 

 wheels. 



The part of the mechanism of a watch which 

 shows the hour of the day, lies concealed from 

 sight between the upper plate of the watch frame 

 and the dial plate. In this ABC (Plate 5. % 7.) 

 is the uppermost side of the frame-plate, as it ap- 

 pears when detached from the dial-plate : the 



