November 10, 1905.] 



SCIENCE. 



587 



American canals are on a large scale. The 

 Idaho Company's canal discharges 2,585 

 cubic feet, the Turlook Canal in California 

 1,500 cnbic feet, and the North Colorado 

 Canal 2,400 cubic feet per second. These 

 canals have all been constructed by cor- 

 porations or societies, in no case by govern- 

 ment. On an average it has cost about 

 32s. per acre to bring the water on to the 

 land, and a water-rate is charged of from 

 £2 8s. to £4 per acre, the farmer paying in 

 addition a rate of from 2s. to 10s. per acre 

 annually for maintenance. Distributary 

 channels of less than five feet wide cost less 

 than £100, up to ten feet wide about £150 

 per mile. 



THE INTRODUCTION OF IRRIGATION INTO A 

 COUNTRY. 



It is evident that there are many serious 

 considerations to- be taken into account 

 before entering on any large project for 

 irrigation. Statistics must be carefully 

 collected of rainfall, of the sources of water 

 supply available, and of the amount of that 

 rainfall which it is possible to store and 

 utilize. The water should be analyzed if 

 there is any danger of its being brackish. 

 Its temperature should be ascertained. It 

 should be considered what will be the effect 

 of pouring water on the soil, for it is not 

 always an unmixed benefit. A dry climate 

 may be changed into a moist, and fever and 

 ague may follow. In India there are large 

 tracts of heavy black soil, which with the 

 ordinary rainfall produce excellent crops 

 nine years out of ten, and where irrigation 

 would rather do harm than good. But in 

 the tenth year the rains fail, and without 

 artificial irrigation the soil will yield noth- 

 ing. So terrible may be the misery caused 

 by that tenth year of drought that even 

 then it might pay a government to enter on 

 a scheme of irrigation. But it is evident 

 that it might not pay a joint-stock com- 

 pany. 



In all cases it is of the first importance 

 to establish by law the principle that all 

 rivers or streams above a certain size are 

 national property, to be utilized for the 

 good of the nation. Even where there is 

 no immediate intention of constructing irri- 

 gation works it is well to establish this 

 principle. Otherwise vested rights may 

 be allowed to spring up, which it may be 

 necessary in after years to buy out at a 

 heavy cost. 



MODES OP DISTRIBUTING AND ASSESSING 

 WATER. 



Where the river is too inconsiderable to 

 be proclaimed as national property, and 

 where there is no question of spreading the 

 water broadcast over the land, but of be- 

 stowing it with minute accuracy over small 

 areas to rear valuable plants, such as fruit- 

 trees, it may be very well left to local socie- 

 ties or to syndicates of farmers to manage 

 their own affairs. Where irrigation is on 

 a larger scale, and its administration is a 

 matter of national importance, the control 

 of the water requires the closest considera- 

 tion, especially if, as is usually the case, 

 the area which may be irrigated exceeds 

 the volume of water available to irrigate it, 

 and where the water is delivered to the 

 fields by gravitation without the labor of 

 raising it. It must be decided on what 

 principle the farmer's right to the water 

 is to be determined. Is he to obtain water 

 in proportion to the area of his land which 

 is irrigable % If part of the irrigable land is 

 not yet cultivated, is some of the supply to 

 be reserved for such land % Is he to pay in 

 proportion to the area actually watered for 

 each crop, or to the area which he might 

 water if he chose ? Where the slope of the 

 land is sufficient to allow the water to flow 

 freely out of a sluice into the field channel, 

 it is not difficult to measure the water dis- 

 charged. Modules have been invented for 

 this purpose, and the owner of the field may 



