HISTORY AND PROGRESS. 



71 



wheel attached to the barrel, on which is wound a cord 

 passing over a pulley and carrying the weight G. 



The escapement r is formed by a horizontal wheel, on the 

 rim of which are sixty vertical steel pins thirty projecting 

 downward, and the same number upwards arranged alter- 

 nately at equal distances from each other. The prongs of a 



Fig. 36. 



steel fork lock into the pins, and are just so far apart, that 

 when one prong touches the rim on one side, the next pin can 

 pass under the other prong. The fork is supported by a bell- 

 crank lever, h, turning on the axis w, between upright bear- 

 ings. An armature, A, of soft iron is supported by the lower 

 arm of the lever, opposite the poles of an electro-magnet, M, 

 which regulates the movements of the fork and scape-wheel. 

 The poles of the magnet are covered with thin pieces of 

 German silver soldered to them, to prevent the armature 

 making close contact with them. The figure shows the arma- 

 ture attracted to the poles, which is the position of rest of 

 the apparatus. 



