26 IRRIGATION. 



tains 20 per cent of sand needs to be irrigated but once 

 in fifteen days, while under similar circumstances, another 

 soil which contains 80 per cent of sand, should be irrigat 

 ed once in five days. The difference would be still greater 

 between soils varying still more in their character, and 

 less with those which may be classed between these 

 limits. 



As to the Climate. As already stated, by far the 

 largest portion of the water which falls upon the earth s 

 surface is removed by evaporation. Observations made 

 at Abbot s Hill, England, by Mr. Dickinson, during 

 eight years, showed that 90 per cent of the water which 

 fell in the summer, or between April 1st and October 1st, 

 was removed by evaporation, and only 10 per cent found 

 its way into the drains which were from 3 to 4 feet deep. 

 The total quantity of water which fell in those six months 

 was equal to 2,900,000 Ibs. per acre, and of this more 

 than 2,600,000 evaporated. It should be remembered 

 that this occurred in a moist, cool climate, the verdure 

 of the meadows in which is hardly equalled in any other 

 country, unless it be in the still more humid Ireland, 

 &quot;the emerald isle.&quot; In England showers occur almost 

 daily, and the winds blowing in any direction from the 

 sea, seldom more than a hundred miles distant, and gen 

 erally much less than that, are charged with moisture ; 

 the maximum summer temperature rarely reaches 80 

 degrees, and also from the more northern latitude, the 

 sun s rays fall at a comparatively low angle; if then, 

 under these conditions, evaporation carries off nine-tenths 

 of the moisture from the soil, what allowance must be 

 made in our climate, where the atmosphere is drier, the 

 summer temperature 20 degrees higher, and where the 

 sun s rays fall upon the surface more directly, and more 

 ardently. And further, if a large allowance must be 

 made in those parts of the country where the rain-fall 

 amounts to 40 inches and over, how much more liberal 



