188 Britain's Heritage of Science 



had actually tried and found to work with a length of eight 

 miles of wire, the reply of the Secretary of the Admiralty 

 was that <v telegraphs of any kind are now totally unnecessary 

 and that no other than the one now in use will be adopted." 

 The word " now " seems to have referred to the conclusion of 

 the French war, and the telegraph mentioned as being in use 

 was the semaphore. 



Ronalds was the son of a London merchant ; his method 

 of transmitting signals consisted in charging and discharging 

 an electroscope through a long wire. In his experiments he 

 used a length of eight miles of wire, properly insulated and 

 embedded in the soil of a garden in Hammersmith. The 

 distinguishing feature of his apparatus consisted in an arrange- 

 ment founded on the same principle as the one so successfully 

 employed in the type-printing arrangement invented at a 

 much later date by Hughes. Two discs bearing the letters 

 of the alphabet near their circumferences were made to 

 rotate with the same speed at the two ends of the line. The 

 electroscope placed at the receiving end was discharged from 

 the sending end. The sender watched the moment when 

 the required letter passed a certain position, and the same 

 letter passing the corresponding position at the receiving 

 end at the moment of discharge could therefore be read off. 

 The two discs were adjusted by means of a signal before the 

 message was sent, and it only remained to ensure that the 

 discs rotated synchronously during the time it took to send 

 the message. Bits of the original wire with its insulating 

 covering were dug out later, and are now preserved in the 

 Science Museum at South Kensington. 



When the electromagnetic effects of currents had been 

 discovered, experiments by Gauss and Weber, Schilling and 

 Steinheil showed how they could be utilized in transmitting 

 signals. These experiments became known in England 

 through William Fothergill Cooke (1806-1879), knighted in 

 1869) who, in conjunction with Wheatstone, set to work to 

 devise a system of telegraphy that could be commercially 

 successful. The main difficulty was to reduce the number of 

 wires, which were at first thought to be necessary for indi- 

 cating the twenty -five letters; in this respect Ronalds had 

 been ahead of his successors. The difficulty was overcome 



