XCVIII. RELATION OF ELEGPfRICITY TO IRRIGATION WORKS. 
ductors between Oolgate and Oakland is about 6 tons per 
mile, copper being used. On the lines between Hlectra 
and San Francisco stranded and solid aluminium conductors 
have been used. : 
At points where electricity is required these transmission 
lines are taken into substations, the voltage reduced by 
static transformers, similar to those used for raising the 
voltage at the generating stations, and if continuous 
currents are required for traction purposes, motor genera- 
tors or rotary converters are used to transform the three 
phase alternate currents. Turning to the Continent of 
Kurope and to India, it will be found that similar electric 
transmission schemes are in existence and are being further 
developed, although the distances are nowhere so great as 
in California. With regard to the sources of power for 
transmission, there is a very popular impression that water 
power is the only source of cheap power, but as a matter 
of fact there are not unfrequently circumstances in which 
coal is a more economical source of power than water, 
even where present in abundance. 
There is an instance of this in Australasia, the capital 
cost of this plant has been roughly £184 per kilowatt 
installed, the distribution being carried out by overhead 
lines which are not costly. Now £100 per kilowatt 
installed is a good price for an electrical plant operated by 
steam and having underground cables, which are much 
more costly than overhead lines, and there are instances 
in England where the capital cost is as low as £60 per 
kilowatt installed. The cost of the water and transmission 
line may therefore be taken as £84 per kilowatt installed. 
The output of the plant has been 1,600 units per kilowatt 
installed per annum, and this quantity of electricity can 
without doubt be generated by a good steam plant fora 
consumption of 4 tons of coal. The cost of this coal would 
