210 THE ELECTRIC TELEGRAPH. 



the apparatus out of circuit and save it from injury in its own 

 endeavour to force a passage through it. He was first re- 

 minded of the necessity of protecting the instruments from 

 the effects of atmospheric electricity, by an accident which 

 happened to the apparatus at the Yesinet station, on the 5th 

 May, 1846, when all the wires were fused and the apparatus 

 rendered useless. 



His paratonnerre consisted of a piece of fine wire, fifteen to 

 twenty feet long, which he carried from the apparatus to the 

 termination of the line outside the telegraph bureau. The 

 insertion of this fine wire in the circuit did not appreciably 

 weaken the current by increasing the resistance of the line, 

 and when a stroke occurred the electricity melted the wire 

 on leaving the line before it could reach the apparatus. 



109. Fardley's Lightning Discharger. Fardley combined 

 both the systems of discharging between plates of metal and 

 of melting a fine wire, for better security for protecting a 

 line of 65 miles, in 1847. 



He divided the line wire at the station and brought the ends 

 within a distance of half a millimetre of each other at the 

 side of a stout wooden post, which supported also a wooden 

 roof to shield the ends from wet and dirt, instead of inserting 

 plates of metal in the line, as Steinheil and others had done. 

 To each of the parts of the divided line he joined some twenty 

 feet of fine metal wire, which formed the leading wires to the 

 apparatus. The line on either side, if struck by atmospheric 

 electricity, would then, in all probability, discharge itself 

 across the small space between the divided line wire to the 

 line on the other side ; but, should this not be the case, and 

 the fluid find its way along either of the leading wires, the 

 wire would be fused before the electricity could reach the 

 apparatus. The leading wires also terminated in a commu- 

 tator, by which the operator, during a thunderstorm, could 

 cut the apparatus entirely out of circuit, establishing at the 

 same time another connection between line and earth whereby 

 the line circuit remained entire. 



110. Nottebohm's Lightning Discharger. Nottebohm has 

 constructed and introduced a lightning discharger for use on 



