insulation prevented further application of this method 

 for a time. 



On April 18, 1838, Cooke secured British patent 

 7614 for a much simpler form of the needle telegraph 

 than the one he had patented with Wheatstone the 

 preceding year. This telegraph (figs. 20, 22) was 

 a 5-wire system that still used the five keys to transmit 

 the signal combinations but it required only two 

 needles to indicate the letters of the alphabet. The 

 speed of transmission was about 30 letters per minute. 

 This telegraph was first used on a 13-mile line that 

 was set up in May 1838 in order to control traffic on 

 that part of the Great Western railway that ran from 

 a borough of London (Paddington Station) to West 

 Drayton. The transmission lines were initially placed 

 in iron tubes 6 inches from the ground, but these lines 

 proved to be unsatisfactory, and the inventors soon 

 decided to use bare wire supported by insulators on 

 telegraph poles.-' 



In 1842 the telegraph line of the Great Western 

 railway was extended five more miles so that it ran 

 past West Drayton to Slough. Other lines were 

 soon put up, and by 1 844 the Yarm.outh and Norwich 

 railway was dispatching trains by telegraph; London 

 was in telegraphic communication with Dover by 

 1846 and with Edinburgh by 1848. 



Wheatstone and Cooke devised, in 1845, a single- 

 needle, 2-wire system (figs. 21, 22) over which the 

 average skilled operator could transmit about 25 

 words per minute (British patent 10655, May 6, 1845). 

 Either two tapper keys or a single drop handle was 

 used to make the signal combinations. This tele- 

 graph was popular in England until about 1900 and 

 was used for railway lines or telegraph offices where 

 the traffic was heavy but not enough to warrant 

 mechanization. 



The publicity attendant on the capture of a mur- 

 derer through a telegraph message ^^ in 1 845 attracted 

 the attention of the public to the new invention, and 

 it rapidly changed from a curious novelty to a neces- 

 sary means of communication. By the following year 

 the British government was seriously considering a 



21 "Wheatstone's Electric Telegraph," Mechanics' Magazine, 

 London, August 11, 1838, vol. 29, p. 320; "Galvanic Tel- 

 egraph," Mechanics'' Magazine, London, October 20, 1838, vol. 

 30, p. 48; "The Galvanic Telegraph at the Great Western 

 Railway," Mechanics' Magazine, London, September 7, 1839, 

 vol. 31, p. 432; Francis Whishaw, "The Electric Telegraph — 

 Mr. Cooke's Improved System as Applied to the Great Western 

 Railway," Mechanics' Magazine, London, June 3, IS'IS, vol. 38, 

 pp. 467-469. 



22 Illustrated London News, November 28, 1846, p. 339 



Figure i8. — Wheatstone and Cooke's 5-needle 

 telegraph receiver {top) and transmitter of 

 1837. Two keys on the transmitter had to be 

 depressed to select a given letter. From 

 R. Sabine, The History and Progress of the Electric 

 Telegraph, London, 1872, pp. 44-45. 



290 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



