Figure 20. — Front and rear views of Cooke's 

 2-needle telegraph, 1838. Note plunge battery. 

 From T. Shaffner, The Telegraph Manual, New 

 York, 1859, pp. 225-226. 



telegraph system.^* Davy's first telegraph (1836) was a 

 very crude electrostatic device with 26 wires — one for 

 each letter of the alphabet. However, this inventor's 

 experimentation developed rapidly and had pro- 

 gressed so far by the beginning of 1837 that he was 

 making successful tests on a needle telegraph through 

 a mile of wire in Regent's Park. Later in that year 

 Davy filed a caveat for an 8-wire needle telegraph that 

 included a relay. A working model of this was shown 

 in December 1837 at the Belgrave Institute in London. 

 This device had a keyboard of 12 keys that actuated 

 screens that uncovered the appropriate letters. 



In 1838 Edward Davy patented an instrument 

 that required two wires and a common return to 



2« J. J. Fahie, History of Electric Telegraph to the Tear 1837, 

 London, 1884, pp. 349-447, 516-529. 



actuate a combination needle and electrochemical 

 telegraph (British patent 7719, July 4, 1838). The 

 needles served as relays to close a local circuit, and 

 a chemical decomposition was thus produced on 

 a treated fabric; combinations of marks and spaces in- 

 dicated the desired letter. In spite of much ingenuity 

 and a considerable understanding of the electrical 

 problems involved, Davy never created an invention 

 that was brought to commercial application. Personal 

 matters forced him to leave England in 1839, just at 

 the time when the major problems of his telegraph had 

 been worked out and when it might have been pos- 

 sible for him to make a commercial success of his 

 invention. 



Alexander Bain of Edinburgh was more successful 

 than Davy as a competitor of Wheatstone and Cooke. 



292 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



