PERIOD OF STRING 85 



from an actual photographic record of a short 

 current sent through the galvanometer. 



Returning now to the question of possible dis- 

 tance of transmission, it is clear that for a very 

 sensitive galvanometer the displacement for the 

 same current would require to be much greater ; 

 the period would be lengthened, / and / dimin- 

 ished, and the rate of working diminished also ; 

 with a silvered quartz fibre, the period would be 

 much longer than that of the flat silver ribbon now 



FIG. 39. Damping of oscillograph string. The ordinates 

 represent the displacement, d. 



in use, and the transmission would therefore be of 

 an altogether slower nature. The capacity of a 

 long line would be correspondingly higher, and 

 this would again necessitate slowness in the trans- 

 mission. 



The theoretical limits of distance of transmission 

 are fairly wide, but the practical limits are unfortu- 

 nately very different. Yet such distances as those 

 between London and Rome, London and Marseilles, 

 etc., should be by no means insuperable. 



That the telautograph could be put to other uses 

 than that of transmitting photographs is seen 

 from its ability to transmit writing. Written 



