32 Quantity of Water Consumed in Irrigation. 



tively necessary in the two soils mentioned. In a similar 

 way the author estimates the depth absorbed in a mixed 

 sand and clay soil at half an inch, making the depth of 

 each watering 2 J inches. 



13. To make, however, every reasonable allowance for 

 wasteful consumption on the Ganges canal, let a further in- 

 crease be made to the above estimated depths of waterings. 

 The average consumption per acre being 102,000 cubic feet 

 (seeg, Appendix B), suppose half be taken as having been used 

 in the fields in four waterings ; this would make the depth 

 of each watering in average soil 3 J inches, or one-sixth more 

 than above stated to be necessary ; the extra half-inch may 

 be considered as avoidable waste. For very light soil, a 

 depth of 5 inches may be taken (one inch of which is avoid- 

 able waste), making the consumpton for the season 20 inches, 

 or, say, 72,000 cubic feet per acre. For a mixed sand and 

 clay soil a depth of 3 inches may be allowed for a watering, 

 and 12 inches for the season, or say 44,000 cubic feet per 

 acre. These quantities are at best approximations, but it is 

 necessary to make some estimate of the kind before the 

 results obtained in India can be put in a form applicable to 

 any other country. The allowance for single waterings will, 

 in the opinion of the author, be found generally applicable 

 to other countries, under a system similar to that adopted in 

 India, whereby water is flowing on to any plot of land for a 

 short time only. Unless in very light soil, or in exceptional 

 circumstances, a depth of 3 to 4 inches seems to be suf- 

 ficient in European countries as well as in India. 



14. The year 1875-76 has been taken as an average year ; 

 the duty of the water (either 192 acres or 187 acres — see 

 par. 7) at least corresponds sufficiently with the average duty 

 (190 acres — see par. 3) of the ten years 1866-76 to make 

 it appear such. The quantities of water given in the last 

 paragraph, based on the returns of that year, will, the 

 author believes, be found ample to cover the average con- 

 sumption in the fields. It must not be overlooked by 

 any one wishing to verify the figures by further experiments 

 that, besides the consumption in the fields, it includes only 

 the loss in the small field-channels, or those for the supply 

 of one field only at a time ; loss in village water-courses, or 

 such as are intended to supply several fields at one time, is 

 not included. Probably it would seldom be convenient to 

 gauge the discharge so as to include field -channels only. 

 To allow, therefore, of results obtained in different places 



