4.92 REPORT—1905. 
and sugar-cane crops yield from 62. to 8/., or even 10/. per acre, the well- 
to-do farmer can easily afford a centrifugal pump worked by steam power. 
Of these there are now many hundreds, fixed or portable, working on 
the Nile banks in Egypt. Where wind can be counted on the windmill 
is a very useful and cheap means of raising water. But everything depends 
on the force and the reliability of the wind. In the dry Western States of 
America wind power is largely used for pumping. It is found that this power 
is of little use if its velocity is not at least six miles per hour. (The mean 
force of the wind throughout the whole United States is eight miles per hour.) 
Every windmill, moreover, shou!d discharge its water into a tank. It is evident 
that irrigation cannot go on without cessation day and night, and it may be that 
the mill is pumping its best just when irrigation is least wanted. The water 
should, therefore, be stored till required. In America it is found that pumping 
by wind power is about two-thirds of the cost of steam power. With a reservoir 
6 to 15 acres may be kept irrigated by a windmill. Without a reservoir 3 acres 
is as much as should be counted on. Windmills attached to wells from 30 to 
160 feet deep cost from 30/, to 704. 
Artesian Wells, 
Up to now the Artesian well cannot be counted on as of great value for irriga- 
tion. Inthe State of California there are said to be 8,097 Artesian wells, of a 
mean depth of 210 feet, discharge 0°12 cubic feet per second, and original cost on an 
average 60/, Thirteen acres per well is a large outturn. 
In Algeria the French have bored more than 800 Artesian wells, with a mean 
depth of 142 feet, end they are said to irrigate 50,000 acres. But this is scattered 
over a large area, Otherwise, the gathering ground would probably yield a much 
smaller supply to each well than it now has. In Queensland Artesian wells are 
largely used for the water-supply of cattle stations, but not for irrigation. 
Well Irrigation. 
It is evident that where water has to be raised on to the field there is an outlay 
of human or mechanical power which may be saved if it can he brought to flow 
over the fields by gravitation. But there is one practical advantage in irrigating 
with the water raised from one’s own well or from a river. It is in the farmer’s 
own hands, He can work his pumpand flood his lands when he thinks best. He 
is independent of his neighbours, and can have no disputes with them as to when 
he may be able to get water and when it may be denied to him. In Eastern 
countries, where corruption is rife among the lower subordinates of Government, the 
farmer who sticks to his well knows that he will not require to bribe anyone; and 
so it is that in India about 13 millions of acres, or 30 per cent. of the whole annual 
irrigation, is effected by wells, Government may see fit to make advances to 
enable the farmer to find his water and to purchase the machinery for raising it ; 
or joint-stock companies may be formed with the same object. Beyond this all is 
in the hands of the landowner himself. 
Canal Irrigation. 
Irrigation on a large scale is best effected by diverting water from a river or 
lake into an artificial channel, and thence on to the fields. If the water surface 
of a river has a slope of 2 feet per mile, and a canal be drawn from it with a 
surface slope of 1 foot per mile, it is evident that at the end of a mile the water 
in the canal will be 1 foot higher than that in the river; and if the water in the 
river is 10 feet below the plain, at the end of 10 miles the water in the canal 
will be flush with the plain, and henceforth irrigation can be effected by simple 
gravitation. 
When there is no question of fertilising deposit, and only pure water is 
to be had, the most favourable condition of irrigation is where the canal or 
the river has its source of supply in a great lake. For, be the rainfall ever 
