238 APPLIED SCIENCE 



able conditions be treated as infinite, though we have no proof 

 that the laws now known hold good up to or nearly up to this 

 limit. When the Valentia end of the Atlantic Cable is joined 

 to the signalling battery, a current rushes into the cable without 

 any perceptible loss of time, but no effect whatever can be per- 

 ceived in America for at least one-tenth of a second ; after say 

 fifteen-hundredths of a second, the received current begins 

 rapidly to increase, according to a definite law, and if the battery 

 contact at Valentia is continued, the current entering the cable 

 there, and the current flowing out of the cable at Valentia, will 

 be sensibly equal after say two and a quarter seconds. After this 

 the currents would remain equal so long as the battery remained 

 in action. When the battery contact is broken at Valentia, and 

 the cable put to earth, the current flows on at Newfoundland 

 for "say one-tenth of a second, as if nothing had happened ; it 

 then begins rapidly to decrease, and sensibly ends say two and 

 a quarter seconds after the contact was broken. 



Thus the current arrives in gradually increasing waves, and 

 dies out in a precisely similar manner. (The numbers given are 

 not the result of direct experiment, but are probably not far 

 from the truth.) On an average three waves, or arrivals of 

 waves, are required to indicate a letter of the alphabet, and five 

 letters are required for each word, so that if on each occasion 

 the wave had to rise to its maximum and fall to its minimum, 

 each letter would require twelve seconds for its completion, and 

 one word per minute only could be sent. With the ordinary 

 Morse instruments used on land and short submarine lines, pro- 

 bably this result would be nearly the limit of the working speed. 

 On the Malta- Alexandria Cable, which has a larger core, and 

 one, therefore, better adapted for speed than the Atlantic Cable, 

 only 3*18 words per minute were obtained through 1,330 knots. 

 Calculated from this, and allowing for the difference of the 

 cores, the speed on the Atlantic Cables would be little more 

 than \\ word per minute ; and be it remarked that until the 

 present year no other instruments than these ordinary Morse 

 instruments were in practical use on submarine lines. Our 

 engineers were therefore bold when they promised seven or 

 eight times this speed by means of new instruments. More- 

 over, the New Atlantic, even allowing for the difference in length 



