THE ELECTRIC TELEGRAPH. 



style which marks by pressure a band or ribbon of paper drawn 

 from the roll R, and carried between the rollers o and o' ; P the 

 ribbon of paper discharged from the rollers o o', after being 

 impressed by t with the telegraphic characters ; I, &, &c., clock- 

 work from which the rollers o o' receive their motion, by which 

 motion the ribbon of paper is drawn from the roller K ; / the 

 spring which draws the arm H of the electro-magnet from the 

 armature ; s s the upright pieces supporting the clockwork ; B B 

 the base supporting the instrument ; D, the key commutator, by 

 which the current transmitted along the line-wire is alternately 

 transmitted and suspended ; m, w, w', n', wires by which the coil 

 of the electro-magnet and the poles of the station battery are put 

 in connection with the line-wires. 



The general principle of this and all similar apparatus has 

 been already so fully expained in 153, et seq., that little more 

 need be said here to render it intelligible. If it be desired to 

 transmit a despatch to a distant station, the battery at the trans- 

 mitting station is put in communication with the line-wire, and 

 by the action of the key D the current is alternately transmitted 

 and suspended during longer and shorter intervals, which are 

 determined by the conventional telegraphic letters. The action 

 of the style t against the ribbon of paper which passes over it at 

 the station receiving the despatch, corresponds exactly with the 

 action of the key D at the station from which the despatch is 

 transmitted ; and combinations of longer and shorter marks or lines 

 and dots are produced upon the ribbon of paper by its pressure, as 

 is shown in the figure. 



The particular combinations of lines and dots used to express 

 the letters are obviously arbitrary. As a matter of convenience 

 and means of expedition, the letters of most frequent occurrence 

 are expressed by the most simple signs, and consequently the 

 selection of signs for the different letters will vary with the language 

 in which the dispatch is expressed. 



The following are the telegraphic characters adopted by Mr. 

 Morse for the English language : 



42 



