112 SECTIONAL ADDRESSES. 
available. | Moreover, there is as yet no standard basis on which 
potential power is computed. 
The power available from a given stream during the wet season 
is many times as great as during the dry season unless sufficient storage 
is available to equalise the flow throughout the year, and the cost of 
such storage would in general be prohibitive, even if it were physically 
possible to provide it. 
The United States Geological Survey takes the maximum useful, 
flow of a stream as being that which may be guaranteed during six 
months in each year. The minimum flow is taken as the average which 
can be guaranteed over the two driest consecutive seven-day periods 
in each year, along with the additional flow which may be obtained 
during this period by developing any available storage capacity in the 
upper waters of the stream. Estimates of potential power based on 
storage capacity are, however, subject to a wide margin of error owing 
to the limited data available, and in the following table the potential 
water power is estimated on the basis of the maximum flow as just 
defined, and in terms of continuous 24-hour power. 
(Millions of Horse-Power.) 
— Available Developed 
Great Britain . A 5 3 : ‘ 0-9 0-2 
Canada Z ‘ 23-0 3-28} 
eS Australia 
3 = Africa (East) 
5S = s» (South) : : 
Tad » (West) . , ‘ : 30°0 to 0-7 
3-3-5 | British Guiana . : ; : 50-0 
8:56 | India and Ceylon : 2 : | 
loa] a New Zealand , 5 : : 
Papua 2 : - - 
Austria ; ‘ 2 4 6-5 0-57 
Brazil . ¢ 4 : 2 26-0 0-32 
Dutch East Indies . : 4 : = 5-5 — 
France . , * 5 : 5-6 1:6 
Germany. E : : : : - 15 0-75 
Iceland . é . ' ‘ ¢ 5 4-0 1-0? 
Italy . - . : : ; : 4:0 1-25 
Japan : ; - - 8-0 15 
Norway . : 5 - : : : 7-5 1-25 
Russia. 3 E i é 2 y 20-0 1:0 
Spain. : : : : c - 5:0 0-88 
Sweden . ; A 5 P : ‘ 6-2 1:2 
Switzerland . 4 : - ‘ 2 4-0 1-4 
United States of America. : ; F 28-0 9-8 
Adopting these figures it appears that the available horse-power 
of the world is of the order of two hundred millions, of which 
approximately twenty-five millions is at present developed or is in 
course of development. 
Power Available in Great Britain and in the British Empire.—With 
the noteworthy exceptions of Canada and New Zealand, practically 
1 Including projected extensions to plants now in operation. 
? Projected but not yet constructed. 
