ELECTRIC TELEGRAPHS. 



407 



Fig. 6. 



ceal the armature from view. The armature turns about an horizontal 

 axis (V V), and is attached to an opposing spring which draws it 

 back from the magnet. The tension of this spring can be regulated 

 by means of a lever acted on by a key outside the 

 box. When a current is sent, the armature is at- 

 tracted to the magnet ; when the current ceases, 

 the spring draws it back ; and it thus moves con- 

 tinually to and fro during the transmission of a 

 message. An upright arm {I) is attached to the 

 armature, and carries an horizontal arm (c), which 

 lies between the two prongs of a fork (d), repre- 

 sented on a larger scale in Fig. 6. This fork vi- 

 brates about an horizontal axis (a b), to which is at- 

 tached the vertical pallet (*). This pallet acts upon 

 an escapement- wheel (O), toothed in a peculiar 

 way, the thickness of the teeth being only half the 

 thickness of the wheel, and the teeth on one-half of the thickness 

 being opposite the spaces on the other half. The total number of 

 teeth is 26, thirteen on each half of the thickness. 



When no current is passing, the pallet (i) is engaged with one of 

 the teeth on the remote side, as represented in Fig. 6. When a cur- 

 rent passes, the armature is attracted, and the pallet is moved over to 



Escapement. 



Fig. 7. 



Breguet'3 Manipulator. 



the near side, thus releasing the tooth with which it was previously en- 

 gaged, and becoming engaged with the next tooth on the near side of 

 the wheel. The wheel, which is urged by a clock-movement, thus ad- 

 vances ^g- of a revolution; and the hand on the dial, being attached 

 to the wheel, moves forward one letter. When the current ceases, the 



