100 RONALDS. 



aware of the difficulties arising from imperfect insulation, which 

 had baffled his predecessors, Mr. Ronalds secured the success of his 

 apparatus both by employing better means of insulation than had 

 hitherto been adopted, and also by making iise of a form of apparatus 

 which should of itself be capable of supplying any loss of electricity 

 which might arise from defects in the insulation.* Mr. Ronalds 

 placed his telegraph wire in glass tubes surrounded by wooden 

 troughs lined with pitch, which were placed in a trench dug in his 

 garden at Hammersmith. He also suspended eight miles of wire 

 by silken cords from a wooden frame erected on his lawn, through 

 which he was enabled to successfully pass messages except in wet 

 weather, the cords not being protected from the wet. 



Mr. Ronald's peculiar form of apparatus may be thus briefly de- 

 scribed: At two stations were placed two clocks, with a dial with 

 20 letters placed on the arbour of the second-hand ; in front of each 

 of these dials was placed a screen with a small orifice cut in it so 

 that, as the dial revolved, only one letter could be seen at a time. 

 The clocks were made to go isochronously, and were started at the 

 same instant with the same letter appearing on the dial through 

 the orifices of each of the screens, both dials, therefore, as they 

 revolved, would of course continue to show similar letters. This 

 formed the readable index of his telegraph ; means of communica- 

 tion between the two stations were produced in the following 

 manner : connected with each end of the telegraph wire, and placed 

 in front of the clocks, were two pith ball electrometers, upon which 

 a constant stream of electricity, produced from an ordinary frictional 

 machine, operated and consequently kept in a state of divergence, 

 except when a letter on the dial was to be denoted ; the electricity 

 was then partially discharged by breaking the connection, the pith 

 balls in a measure collapsed, and the distant observer was thereby in- 

 formed to note down the letter then visible through the orifice on the 

 screen. In this way letter after letter might be denoted and intel- 

 legence of any kind conveyed. All that was absolutely required for 

 the success of Mr. Ronald's telegraph was, that the clocks should 

 go isochronously during the time intelligence was being transmitted, 

 for, by a preconcerted arrangement, both clocks might be easily 

 started at the same letter upon a given signal. The attention of 

 the distant observer was called by the explosion of gas by means of 

 an electric spark. In 1823, Mr. Ronalds published a full description 

 of his telegraph, in a work entitled, ' Descriptions of an Electrical 

 Telegraph, and of some other Electrical Apparatus.' 



In 1825, Mr. Ronalds invented a perspective tracing instrument, 

 to facilitate drawing from nature or from plans and elevations, an 

 account of which he published in 1828 in a work entitled, ' Mecha- 



* This peculiarity of Mr. Ronalds' apparatus is stated in full by Mr. Highton, 

 C.E., in his work on the ' Telegraph,' page 50. London, John Weale. 



