Sir jfohn Snell 257 



said : u They are so nearly fool-proof that even a drunken 

 man turned loose in one could hardly hurt himself." It 

 was not always so, for in the old-fashioned switch there 

 was metal carrying two thousand volts on either side of 

 the switch handle. For a healthy person two thousand 

 volts is a dangerous yet by no means a fatal shock, 

 though people with weak hearts have been killed by a 

 shock of no more than one hundred volts. 



Having asked whether the overhead cables were 

 affected by wind or weather, we learned that they are 

 made to withstand gales of fifty miles an hour and three- 

 eighths of an inch of ice forming on the wires themselves. 

 They are fitted with earth wires which form an almost 

 perfect protection against lightning, and with bird guards 

 which prevent large birds such as jackdaws from form- 

 ing connexions between charged wires, and incidentally 

 electrocuting themselves. 



Almost the only danger is that a gale may break off 

 a tree branch and blow it against two cables, thereby 

 causing a short circuit. Even wet straws blown against 

 the poles in a mass may cause a short circuit, but this 

 rarely happens. 



It is through the kindness of Sir John Snell that we 

 have been able to write this chapter on the modern 

 developments of electric power. Sir John Snell is a 

 Cornishman. He was educated for the Navy, but fortu- 

 nately or unfortunately he failed to pass the very strict 

 eyesight tests. He turned his attention to engineering, 

 and became a student at King's College, London, of 

 which he is now a Fellow. When only fifteen he went to 

 work for the firm of Messrs Woodhouse and Rawson, and 

 afterward went to Stockholm. He was only twenty- 

 three when he became assistant to Major-General Webber, 

 R.E., and three years later he held the important post of 

 Borough Electrical Engineer at Sunderland. In 1910 he 

 was a partner in the firm of Messrs Preece, Cardew, Snell, 



