290 Mr. W. H. Preece on some Physical Points 



A telephone was sent to Guernsey, and Mr. Willmot went to 

 Dartmouth, those two places being connected by a cable 60 

 miles long. Conversation was carried on, the articulation 

 being perfect though slightly muffled. This was a surprise ; 

 for it was felt that the static induction of a cable, by its retard- 

 ing influence, would have prevented articulation by lengthening 

 the waves of electricity and rolling them up as it were. 

 Through the kindness of Messrs. Latimer Clark, Muirhead, 

 and Co. I was able to repeat these experiments on an artificial 

 Atlantic cable, constructed to duplex the direct United-States 

 cable. With Mr. Willmot at one end and myself at the other, 

 there was no difficulty in speaking up to 100 miles, though 

 the muffling effect of induction was evident. Beyond this 

 distance up to 1.50 miles muffling commenced to seriously 

 impede conversation, and the sounds diminished considerably 

 in strength : it was like talking through a thick respirator. 

 The effect diminished rapidly up to 200 miles, beyond Avhich 

 articulation became impossible, though singing was distinctly 

 heard ; indeed singing was heard through the whole length 

 of the cable, 3000 miles long ; but this was traced to a secondary 

 cause, it being due to the induction of condenser on condenser. 

 Nevertheless there is no doubt that singing can be heard 

 through a much greater length than speaking, due to the 

 greater regularity of the successive waves of electricity. 



I subsequently experimented on the underground wires be- 

 tween Manchester and Liverpool, a distance of about 30 miles ; 

 and through this length we had no difficulty whatever in 

 speaking. Again, between Dublin and Holyhead, through the 

 cable 67 miles long, we spoke with ease, singing coming 

 through with remarkable power and effect. This cable con- 

 tains 7 distinct conductors. When one wire was used for the 

 telephone, the sounds could be heard on every other wire, but 

 in a feebler degree. When the other wires were working with 

 the ordinary telegraphic apparatus, induction was evident, but 

 not sufficiently intense to stop conversation. Each wire would 

 be surrounded with a wet serving of hemp ; but this was not 

 of sufficient conducting-power to entirely screen the effect of 

 induction. The same effect was experienced between Man- 

 chester and Liverpool, where the wires are made up into 

 cables of 7 conductors served outside with tarred hemp. 



The conclusion that I have come to is, that conversation 

 might be held through a single wire cable 200 miles long 

 with the apparatus that we now have ; what new apparatus 

 will do no man is rash enough to predict. 



The reason for this surprising result is not difficult to 

 explain : — 



