Sir yohn Snell 247 



burning day and night, for it costs a lot to relight a cold 

 furnace. And the bill for coal is enormous. In a station 

 which the writer recently went over this bill amounts to 

 thirty thousand pounds a year. When a station is a single 

 unit the furnaces can never be extinguished nor the 

 dynamos be allowed to cease running, but if that station 

 is connected with another, then in slack times it is able to 

 shut down and take its current from the other station. 



This results in a very great economy in coal and labour, 

 and the arrangement is very convenient when repairs are 

 needed. Power can thus be provided more cheaply. At 

 present the average price in England is sixpence a unit 

 for lighting and a penny farthing for heating and power. 

 When the scheme is complete, these prices should fall to 

 twopence for lighting and a farthing for power. Then 

 electricity will be far cheaper than oil. 



There is another advantage in the national system, 

 At present the loss of power between the station and the 

 consumer is seventeen per cent., but with the grid system, 

 says Sir John Snell, this will be reduced to two and a half 

 per cent. The cables will carry current at no less than 

 one hundred and thirty-two thousand volts, compared 

 with a maximum in the past of sixty-six thousand volts. 

 The various stations are being linked up by chains of 

 latticed steel masts, sixteen feet square at the base and 

 up to eighty feet in height, carrying the main high-tension 

 lines. 



In America voltages up to two hundred and fifty 

 thousand are being conveyed, but for this purpose no 

 ordinary wire is sufficient. The conductor used is a tube 

 of copper, the centre of which is filled with oil. If over- 

 loaded, a wire heats, and eventually fuses. 



It is difficult to believe that only fifty years have passed 

 since electric lighting came into being, and that power has 

 been carried by cable for an even shorter period. Between 

 1870 and 1880 Edison and Swan solved the problem of 



