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words per minute) on the general plan which I explained in my last 

 communication ; and that no higher battery power than from 150 to 

 200 small cells of Daniell's (perhaps even considerably less) would 

 be required. Whether or not this system may ultimately be found 

 preferable to the very simple and undoubtedly practicable method of 

 telegraphing invented by Mr. Wildman Whitehouse, can scarcely be 

 decided until one or both methods shall have been tested on a cable 

 of the dimensions of the Atlantic cable, either actually submerged or 

 placed in perfectly similar inductive circumstances. 



II. Method for telegraphing through submarine or subterranean 

 lines of not more than 500 miles length. 



The plan which I have proposed to describe for rapid signalling 

 through shorter wires, has one characteristic in common with the 

 plan I have already suggested for the Atlantic telegraph ; namely, 

 that of using different strengths of current for different signals. 



But in lines of less than 500 miles, condensed pulses, such as have 

 been described, may be made to follow one another more rapidly 

 than to admit of being read off by an observer watching the image of 

 a scale in a suspended mirror ; and a new plan of receiving and 

 recording the indications becomes necessary. 



Of various plans which I have considered, the following seems 

 most likely to prove convenient in practice. 



Several small steel magnets (perhaps each about half an inch 

 long) are suspended horizontally by fine threads or wires at different 

 positions in the neighbourhood of a coil of which one end is con- 

 nected with the line wire and the other with the earth. Each of 

 these magnets is held in a position deflected from the magnetic 

 meridian by two stops on which its ends press ; and two other small 

 stops of platinum wire are arranged to prevent it from turning 

 through more than a very small angle when actuated by any de- 

 flecting force making it leave the first position. When a current 

 passing through the coil produces this effect on any one of these 

 magnets, it immediately strikes the last-mentioned stops, and so 

 completes a circuit through a local battery and makes a mark on pre- 

 pared electro-chemical paper. For each suspended magnet there is 

 a separate style, but of course one battery is sufficient for the whole 



