306 



had recourse to, and, by the use of perforated slips, as in Bain's and 

 other systems, it would be easy to work from twelve to twenty of the 

 six-fold varied signals per second through lines of less than 100 miles 

 length. Operating by the hand is, however, I believe, generally pre- 

 ferred for ordinary telegraphing ; and no such speed as the last-men- 

 tioned could be attained even by a skilful operator working with 

 both hands. Six distinct letters or signs of an alphabet of thirty, 

 could, however, I believe, be delivered per second by the two hands 

 working on a key-board with twelve keys (perhaps like those of a 

 pianoforte), provided the keys are so arranged as to fulfil the follow- 

 ing conditions : 



(1) That by simply striking once any one of a first set of six of 

 the keys, an electric operation of one or other of the six varieties shall 

 be made twice, the second time commencing at a definite interval 

 (perhaps -j^h ^ a second) later than the first. 



(2) That by striking one or other of the remaining six keys at 

 the same time, or very nearly at the same time, as one of the first 

 set, the second operation of the double electric signal will be that 

 corresponding to the key of the second set which is struck, instead 

 of being a mere repetition of the operation corresponding to the key 

 of the first set. 



It would certainly be easy to make a key-board to fulfil these 

 conditions with the aid of some clockwork power. Then by arranging 

 the thirty-six permutations and doubles of the six simple signals to 

 represent an alphabet of thirty-six letters and signs, an experienced 

 operator would have to direct his mind to only six different letters 

 per second, while executing them by six double operations with his 

 fingers. That it would be possible to work by hand at this rate there 

 can be no doubt, when we consider the marvels of rapid execution so 

 commonly attained by practice on the pianoforte ; and it appears not 

 improbable that in regular telegraphic work, practised operators of 

 ordinary skill could perform from four to six letters with ease per 

 second, or from forty to sixty words per minute, on lines of not more 

 than 100 miles length. The six signals per second, which, according 

 to the preceding estimate, could be distinctly conveyed by a sub- 

 merged wire of .500 miles in length, could of course be easily per- 

 formed by the hand, with the aid of a key-board and clockwork 

 power adapted to make the double operations for giving rapid sub- 



