290 Water Supply and Small Holdings, [july, 



conditions be too hilly to work with less than a full team, 

 ■as well as those in which surface water is always more 

 abundant than welcome, may be left out of consideration ; 

 but if attention is directed generally to average agricultural 

 areas, where the land is either moderately flat or gently un- 

 dulating, it may be found that permanent ponds are neither 

 so numerous nor so well situated as to make it easy to cut 

 up the land so that each unit shall have its own pond or 

 ponds. 



Flat land, if composed of light or sandy soil, absorbs a 

 very large percentage of the annual rainfall by infiltration, 

 ■whilst that of similar formation, but consisting of heavy soils, 

 has to be well ditched and drained to carry off periodical 

 ^excesses of rainfall. In either case, the water does not remain 

 in the surface hollows long enough to provide for dry spells. 



On an undulating formation, in other than porous soils, 

 ditches must be formed, running roughly parallel with the 

 watershed, in order to prevent the flooding of the fields dur- 

 ing storms, and the multiplication of intercepting ditches 

 due to small farming on any considerable scale in such 

 localities will tend to deprive the ponds of some of the water 

 which now finds its way into them. The more permanent 

 ponds, in almost all but clayey districts, are fed from below 

 as well as from above, and in the case of reliable all-the- 

 year-round ponds, such as those found in deep hollows, the 

 surface of the pond-water practically corresponds with the 

 level of saturation of the earth-water surrounding it. Such 

 ponds can afford to lose by evaporation many times their 

 apparent cubic capacity, as such losses as occur are instantly 

 made good by lateral influx; but evaporation does not, in 

 iact, affect these ponds as it affects others, because it is 

 checked by the trees which generally find a congenial home 

 in their vicinity. Any influence, such as the cutting of 

 surface ditches, which tends to prevent infiltration, must, 

 therefore, divert to the ditch outfall some of the water which 

 would otherwise find its way into the ponds by underground 

 channels. This tendency can, however, be corrected either 

 by leading the ditches into the ponds, where that is possible, 

 or by tapping the ditches by means of field drain-pipes. 



