540 



Modern Submarine Telegraphy. 



[March 12, 



Bj these means weak signals are built up at the receiving end 

 of the cable, ^nd the speed of working can thus be materially 

 increased. 



Fig. 9. — High Speed Relay (Side view). — The pointer is con- 

 structed of quartz fibres kept in tension by a thin copper wire, 

 the whole weight of the pointer being not more than one or two 

 grains. 



It is fortunate that the class of signal that has the greatest 

 difficulty in getting throngh the cable is the easiest to be added to 

 when received. The " high speed " relay works therefore not from 

 the signals received from the cable only, but also from those that it 

 transmits through its own local ch'cuit, the record that it makes 

 being the combined action of the two.* 



For most of the calculations in this lecture I am indebted to 

 Professor Perry. This, I am sure, is a sufficient guarantee for their 

 accuracy. 



[S.G.B.] 



* A scientific man of my acquaintance tells me that I ought to put things 

 in this way. A fluttering current arrives too weak to make a signal, but all 

 it can do is ^ust to hint that it wishes to make a signal, the hint is recognised 

 and the local battery makes the signal required. 



