230 ELECTRO-TELEGRAPHY 1 



velocities are recorded, for which the nature of the wire or the conditions under which 

 it was placed were different. Whoatstono found the velocity of electricity under 

 different conditions from the above to be 288,000 miles per second. His wire was 

 copper, and was wound on a frame. The electricity that was employed by Mr. 

 Wheatstone in these experiments was obtained from the friction of glass against an 

 amalgam of tin. The various velocities are due partly to the conditions under which 

 the conducting wire is placed, and partly, no doubt, to the varied properties of 

 electricity from various sources. 



Electricity is obtained from other sources than friction with so much greater faci- 

 lity, and in forms so much more applicable and manageable for telegraphic purposes, 

 that frictional electricity has not been applied in real practice. It must not, however, 

 be passed over in this place, because one of the earliest telegraphs, perhaps the very 

 first in which a long length of wire was actually used, was actuated by this form of 

 electricity. In February 1753 a writer, dating from Renfrew, and signing himself 

 ' C. M.' wrote to the Scot's Magazine on ' An expeditious mode of conveying intelligence/ 

 The _ method proposed differed in no respect from that adopted by Dr. Watson, 

 frictional electricity being employed, and the signals being the movements of pith- 

 balls^ He, however, proposed the use of bells, upon which the electrified balls were 

 to strike, and thus, he says, the experimentalist ' will inform his correspondents by the 

 sound what wires have been touched ; and thus by some practice, they may come to 

 understand the language of the chimes in whole words, without being put to the 

 trouble of noting down every letter.' 



Lesage, we are informed by Moigno, in his ' Telegraphic Elcctriquc,' erected at Geneva 

 in 1774 a lino of twenty-four insulated metallic wires, insulated from each other, each 

 wire being connected at its farthest end with a pith-ball electrometer, which corre- 

 sponded to one of the letters of the alphabet. Lomond, in 1787, employed a single 

 electroscope, and by arranging a system of signals given by the divergence of the pith- 

 balls, transmitted intelligence by means of a single wire. This was seen by Arthur 

 Young, and described by him in his ' Travels in France.' In 1816 Mr. Eonalds esta- 

 blished, in the grounds attached to his residence at Hammersmith, eight miles of 

 wire suspended by silk to dry wood, besides 175 yards of buried wire in glass tubes 

 embedded in pitch and enclosed in troughs of wood. He obtained his electricity from 

 a common electrical machine, and his signals from the motion of light bodies, balls of 

 elder-pith, produced under circumstances analogous to those to which we have 

 already referred. At the far end of his telegraph wire two pith-balls were suspended 

 close together. Electricity applied at the home end of the wire at once diffused itself 

 throughout the conducting system, including the pair of light balls. Just as we have 

 seen gold-leaf recede after having approached rubbed amber, and acquired an electric 

 charge, so the pith- balls, each being charged with electricity, derived from the same 

 source, recede from each other ; and this in obedience to the fundamental laws of 

 static electricity, for which we must refer readers to treatises on the subject. Here, 

 then, we have one solitary signal. The manner in which Mr. Eonalds turned it into 

 language was ingenious. He pressed time into his service, and by combining time 

 and motion he obtained a language. He provided a clock movement at each station ; 

 the clocks were so regulated as to be synchronous in their movements ; each of them 

 carried, in lieu of a hand, a light disc, having the letters of the alphabet and other 

 signals engraved on it. The disc was hidden by a screen, in which was one opening. 

 It is obvious that if the clocks were started together, and had uniform rates, the same 

 letter at the same time would be visible through the opening in each screen ; and 

 letter by letter would pass seriatim and simultaneously before the respective openings. 

 If absolute uniformity is difficult for long periods, it is practicable for shorter. The 

 sender of a message watched the opening of his screen; the moment the lot tor 

 approached that ho desired to telegraph ho charged the wire with electricity, and the 

 balls at the far station moved ; the letter then visible there corresponded with the one 

 at the home station, and was road off. The sender watched till the next letter he 

 required came round, and so on. 



Let us now pass on to some of the leading features of electro-telegraphy, as it has 

 been realised of late years, and to a description of some of the telegraph instruments 

 that are most in use. 



Chemical action is the most fertile source of electricity. If a silver fork and a 

 steel knife are connected together by a piece of wire, and the fork is thrust into a 

 piece of meat, say a hot mutton-chop, the moment an incision is made in the Tin.tr 

 with the knife, electricity will pass along the wire and continue to do so while the 

 above disposition of things remains. Upon the proper test being applied, the elec- 

 tricity is readily detected. This is the OWrr&d frm of electricity. The .amount of 

 force in circulation in this particular combination is not very groat, and its power of 

 travelling to a distance is not very high, but still it is quite capable of producing good 



