ANNUAL ADDRESS, XXVII, 
the small vertical engines which are usually used for a section of 
shafting. The electric motors work at about 90% efficiency, and 
the loss in the short line wire between them and the main 
generator is comparatively trifling. 
The General Electric Company have constructed several instal- 
lations of electrical underground haulage plants for collieries, and 
I saw an excellent plant at work in San Francisco, for hoisting 
coal from ships and afterwards hauling it on a short electrical 
railway. 
Electric motors are employed to drive fans, centrifugal and 
other pumps, air compressors, and for a great variety of purposes. 
I will now briefly consider the generation of electricity by 
means of water power, and its transmission to long distances. 
There are many places where nature has provided large supplies 
of energy in the form of falling water, and to convey this energy 
to points where it may be utilized in an economical manner is a 
‘Problem of vast importance. The principal methols available 
for transmitting this power are :—Hydraulie Transmission, 
Pneumatic Transmission, and Electric Transmission. Which of 
these methods should be adopted for any given case will depend 
Upon prevailing conditions and requirements. Except for very 
‘Short distances however, electric transmission has no rival in 
Point of economy, flexibility, efficiency, or general utility. 
The distance over which power can be transmitted electrically 
depends primarily upon the electro-motive force that may be 
safely and judiciously employed, and when it is considered that 
for a given electro-motive force the cost in copper conductors 
increases directly, as the square of the distance, it follows that 
the cost of conductors will be an important factor in the financial 
Success of any scheme which the power is generated at a consider- 
able distance from the motors utilizing it. But the amount of 
©opper in any conductor is inversely proportionate to the square 
Of the electro-motive force—that is to say, if the distance and 
_ other conditions, except the electro-motive force be fixed, it will 
