64 Royal Society: — 
In subterranean or submarine lines of less than 100 miles length, 
it would be easy, by means of simple battery applications, followed by 
connexions with the earth, or by means of simple electro-magnetic 
impulses at one end of the wire, to give ten or twelve of such signals 
per second without any confusion of utterance at the other end. The 
confusion of utterance which would be experienced in working thus 
through longer lines would be easily done away with, in any length 
up to 500 miles, by following up each battery application with a 
reverse application for a shorter time, or by following up each electro- 
magnetic impulse by a weaker reverse impulse, so as approximately 
to fulfil the condition (described in my former communication), of re- 
ducing the subsidence of the electrification in the wire to the double 
harmonic form. It would, I believe, be readily practicable to send 
distinctly five or six such signals per second (each a distinct letter of 
an alphabet of six) through a wire of 500 miles length in a submarine 
cable of ordinary dimensions. To perform the electrical operations 
required for sending a message on this system, mechanism might be 
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 ;4,th of 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 
