60 



In 1854, aluminium soJd at £120,000 per ton; in 1856, at 

 £14,400 per ton; 1858-85, at £4,800; in 1886, at £3,400 per ton; 

 at the end of 1890, the price had declined to £720; at the end of 1891, 

 to £240; in 1900, it sold at £86; in 1910, at £62. 



The great fall in price followed the decline in the price of sodium 

 from 2,000 francs to 15 francs per kilogramme. Prior to the war, 

 aluminium had dropped to £60 per ton and had become one of the 

 cheaper metals. Comparison of the foregoing with the prices of 

 metals quoted on page 59 shows that, owing to the protective tariff, 

 the price of aluminium in the United States is higher than in Great 

 Britain. 



^ , . Certain properties of aluminium tend to bring it 



Transmission in keen competition with copper for the construction 



^"^^ of electric transmission lines; the economic question 



based on the relative prices of the two metals is the principal deter- 

 mining factor in choosing between the two. 



Aluminium is very light (2-7 against 8-9 for copper); it 

 has a very fair conducting capacity (34 against 57 for copper), and it 

 has relatively satisfactory strength (22 against 44 for copper). To 

 obtain the same total conducting capacity, only half the weight of 

 aluminium is required as compared with copper. Consequently, 

 compared by weight, aluminium may be said to have twice the 

 conducting capacity of copper. As, however, even the half weight 

 of aluminium has a larger volume than the corresponding quantity 

 of copper, the cooling of an open-air aluminium line is more effective 

 than that of a copper line. An aluminium line has also the advantage 

 as regards the stress caused by its own weight, but it is at a dis- 

 advantage as regards wind pressure and accumulation of snow. 



One of the reasons why aluminium has not been more extensively 

 used on transmission lines in the United States, is given in the follow- 

 ing editorial in the Electrical World*: 



"As is well known to our readers, the American price for alu- 

 minium is deliberately set by the powers that rule it at a figure which 

 just fails to encourage the very large use of the metal in preference 

 to copper. Under ordinary conditions an aluminium conductor at 

 American prices is just a few per cent cheaper than the equivalent 

 copper conductor, so little cheaper, in fact, that the extra cost of 

 supports and stringing the aluminium equals the saving. In Europe 

 and in Canada the ordinary quotations of aluminium are about the 

 same, pound for pound, as copper at the base price, and for hard- 

 drawn wire the saving in the use of aluminium figures out at from 

 35 to 40 per cent. This difference in condition is established by a 

 virtual monopoly of aluminium in this country, with the usual effect 



* Electrical World, New York, July 6, 1912. 



