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THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. [September, 



ELECTRIC TELEGRAPHS. 





The application of the instantaneous transmission of electricity, as a 

 means of communication between distant places, promises to become 

 one of the most important inventions of tne present age, and to rival 

 even locomotion on railways in the facilities afforded of transmitting 

 information. The science of electricity is yet but in its infancy ; and 

 though it has, during the comparatively short period of its studv, with- 

 drawn much of the veil from the works of Nature, that which has 

 hitherto been revealed and already accomplished by its agency, serves 

 to show that it is capable of disclosing far greater mysteries, and of 

 being applied to much more important uses. When the transmission 

 of electricity instantaneously through miles of wire became known, it 

 was not long before the possibility of applying that property to the 

 communication of signals suggested itself to the fertile ingenuity of 

 man. The inconvenience of using frictional electricity, and the inter- 

 vals of time requisite for its excitement, however, formed difficulties 

 which could not be sufficiently overcome. Nothing, therefore, was 

 effected in the construction of such telegraphs, though the high state 

 of tension of frictional electricity renders it far better calculated for 

 traversing long lengths of wire than the electricity of feeble tension 

 excited by chemical action. The full tension of voltaic electricity, 

 indeed, prevents it from overcoming the resistance which even the 

 best conductors offer to its passage, aud unless the quantity developed 

 be great, ami the conducting wire be perfectly insulated, much of the 

 power will be lost in passing through a long circuit. It was not, con- 

 sequently, until after the discovery by Professor CErsted, in 1S19, 

 that the voltaic current would deflect a magnetic needle, and the 

 subsequent discovery that the efficacy of a feeble current on the 

 needle may be greatly increased by multiplying the convolutions of 

 the wire through which it passes, that the efforts to construct an 

 electrical telegraph assumed a practicable shape. 



When it was ascertained that on causing a current of voltaic elec- 

 tricity to pass over a magnetic needle freely suspended, the needle 

 was instantly deflected into a position acrcss the direction of the 

 current, it appeared reasonable to expect that, by employing several 

 wires and magnetic needles, and by causing the electric current to 

 deflect either of the needles at pleasure, their deflections might be so 

 regulated as to form intelligible symbols. In the first stage of the 

 invention, it was proposed to have as many magnetic needles as there 

 are letters in the alphabet, each one having a separate wire passing 

 over it connected with one of the poles of a voltaic battery. To each 

 needle was affixed a small screen, which, when the electric current 

 was not passing through the wire connected with it, concealed from 

 view a letter or a figure. A number of keys were arranged somewhat 

 in the manner of the keys of a pianoforte, each of which was connected 

 with one of the wires of the voltaic battery, and a letter was marked 

 on the key corresponding with the one concealed by the screen on the 

 needle to which it appertained. By touching any one of these keys 

 the metallic connection was completed, and the current of electricity, 

 on passing over the magnetic needle, deflected it, and exposed to 

 view the letter beneath. In this manner it is evident a correspond- 

 ence could be carried on between persons far apart by either spelling 

 the words, letter bv letter, or by agreeing to certain symbols for (he 

 expression of words or sentences. As the transmission of electricity 

 occupies no perceptible time, the deflection of the needle at the 

 distant station would take effect almost at the instant the voltaic cir- 

 cuit was completed by touching the corresponding key. This appli- 

 cation of electricity as a means of telegraphic communication, ap- 

 peared to realise in principle the most sanguine expectations of its 

 efficacy, hut in practice many difficulties arose. The number of wires, 

 and the perfect insulation" each one required, would have pre- 



