HISTORY AND PROGRESS. 



47 



middle of which is a vertical pointer. In the lower part of 

 the case is a handle, on the arbor of which, inside, a commu- 

 tator is placed, so that when the electrical connections are 

 made, the movements of the handle and pointer to right or 

 left correspond. 



On the metallic face of the instrument are engraved 



Fig. 23. 



the deflections corresponding to the various letters of the 

 alphabet. Fig. 24 represents the interior view of the same. 

 A A is a long vertical coil of fine silk-covered wire, in the 

 middle of which a small magnetic needle plays, having at 



