466 



NEGRETTI AND ZAMBRA, HOLBOEN TIADFCT, E.C., 



Ordinary form of A B C Telegraph, with Bell (fig. 2826). 



SIR C. WHEATSTONE'S PATENT ALPHABETICAL 



MAGNETO ELECTRIC TELEGRAPHS. 

 NEGRETTI AND ZAMBRA, AGENTS. 



2826 WHEATSTONE'S Instrument is a perfected modification of the original 

 Alphabetic Telegraph, invented and patented by him in 1840, the first step-by-step 

 telegraph instrument ever constructed. 



Any person able to read is able to manipulate this instrument. The operator 

 has merely to touch in succession, with the fingers of one hand, the keys corre- 

 sponding with the letters forming the message he wishes to transmit, whilst he 

 turns the handle with the other hand. In order to receive a message the operator 

 has only to watch the letters pointed to by the hand of the indicator. The corre- 

 spondence can be carried on at about twenty words per minute. 



The electric currents which actuate this instrument are produced by the 

 employment of a permanent magnet instead of a voltaic battery ; so that chemical 

 preparations are not required, and the instrument is therefore ready to be put in 

 action at any moment, at whatever distant place it may be removed to, and notwith- 

 standing however long it may have been in disuse. 



In the absence of voltaic batteries and of working contacts, and in the applica- 

 tion of finger keys, consists the essential superiority of these over all the other 

 ABC instruments which have been hitherto introduced. 



Fig. 2826 shows the ordinary arrangement for use on private lines. 

 Complete Telegraph for one Station, consisting of Communi- 

 cator and Indicator 



Alarm Bell, to work with the above Telegraph .... 



Communicator separately 



Indicator separately . 



21 



400 



14 



700 



