COMMON THINGS CLOCKS AND WATCHES. 



wider is the range of its vibrations the more intense is the force 

 with which it descends to the vertical direction, and consequently 

 wide vibrations are performed in as short a time as more contracted 

 ones. Now the vibrations of the balance-wheel are subject to like 

 conditions. The witer the range of its vibrations, the more in- 

 tense is the force with which the recoil of this spring carries it back 

 to its position of rest, and consequently it swings through these 

 wide vibrations in the same time as through more contracted ones, 

 in which the force of the spring is proportionally less intense. 



The oscillation of the balance-wheel regulates the motion of 

 watchwork in the same manner by means of an escapement- wheel, 

 as that in which the pendulum regulates the motion of clock- 

 work. The pallets and the escapement- wheel are, however, very 

 variously formed in different watches. 



35. Having thus explained generally the powers by which 

 clocks and watches are moved and regulated, it now remains to 

 show how the necessary motions are conveyed to the hands by 

 suitable combinations of wheels and pinions. 



In fig. 17 (p. 1), are represented the works of a common watch, 

 moved by a mainspring A, and regulated by a balance-wheel H ; 

 the wheels and pinions, however, being changed in their relative 

 positions, and the fusee being omitted, so as to show more visibly 

 the connections and mutual dependency of the many parts. The 

 external extremity of the mainspring is attached to the base, o, 

 of a column of the frame. Its internal extremity is attached to 

 the lower end of an axle, of which the square end, T, at the top 

 enters a hole in the dial-plate into which the key is inserted when 

 the watch is to be wound up. The ratchet-wheel B is fixed 

 upon this axis so as to turn with it, but the other wheel c under 

 the ratchet-wheel is not fixed upon it, the axis being free to turn 

 in the hole in the centre of c, through which it passes. A catch 

 n o is attached by a pin on which it plays to the face of the 

 wheel c, and its point o is pressed against the teeth of the 

 ratchet-wheel B, by a spring provided for that purpose. When 

 the key is applied upon the end T, and turned in the direc- 

 tion in which the hands move, the ratchet-wheel is turned 

 with it, and the point o of the catch pressed constantly 

 against the teeth while it turns falls from tooth to tooth with 

 an audible click, and thus produces the peculiar sound, with which 

 every ear is familiar, while the watch is being wound up. During 

 this process the wheel c does not turn with the axle, which only 

 passes through the hole in its centre without being fixed upon it, 

 but the mainspring, A, being attached to the axle is coiled more 

 and more closely round it, and re-acts against the fixed point o 

 with greater and greater force. 

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