HISTORY AND PROGRESS. 67 



with 1 1, or lastly, it may be placed on the other end of the 

 metal strip " communication directs" 



Fig. 34 represents the interior of the receiving instrument 

 seen from the back ; M M is a horizontal electro-magnet, 

 whose armature, suspended between screw points, carries 

 on its upper side a metallic rod q, which is limited in its 

 play by adjusting screws in the frame/. At right angles 

 to q, near the top, is a peg, q, working in a fork F, fixed to 



Fig. 34. 



one end of the horizontal shaft a. At the other end a pallet, 

 g, engages alternately with two parallel scape-wheels, im- 

 pelled by a clockwork in the case above, and placed so that 

 the thirteen teeth of the front and back wheels alternate when 

 looked at from the front. When the apparatus is at rest 

 and the armature held back by the spring, the pallet locks 

 into the teeth of the back wheel ; but on the attraction of 

 the armature to the poles of the magnet, the pallet springs 

 into the teeth of the front wheel, which, being half a tooth 

 in arrear, allows the wheels and pointer to turn one twenty- 

 sixth of the whole circle. As soon as the armature is released 

 the pallet leaves the teeth of the front wheel, and re- 

 enters between those of the other. The latter being half 



F2 



