112 Mamujement of Ponds and TJ'eUs. 



and it" a pond be placed there, drains from the rest of the fiekl 

 can in addition be brought into the pond. Nor, unless the land 

 is very flat, need the waste-pipe (which is in effect but a con- 

 tinuation of a drain) be placed quite as low as the supply-pipe ; 

 for I have often seen water running fast into a pond from a drain 

 whose mouth was considerably below the surface of the water in 

 the pond. At the same time, as the bulk of water in the pond 

 must have a tendency to hold back the water in the drain, I dare 

 not recommend that the waste-pipe should ever be more than 

 12 or 18 inches higher than the supply-pipe, and then only in 

 cases where the land to be drained is some feet higher than the 

 surface of the pond, otherwise I should be particularly careful to 

 keep a clear fall of some depth below the supply-pipe. 



By thus draining a field into a pond, or in other words, making 

 a pond at the mouth of a drain, a good supply of water may often 

 be obtained in summer from a thunder-shower, which would 

 otherwise have raised the pond only an inch or two ; so that this 

 single advantage often makes a very small pond, or even a good 

 deep hole at a drain's mouth, equivalent to a large pond in a 

 woi'se situation. 



Need I remind my readers that rats, rabbits, and foxes are 

 very fond of frequenting drains ? Indeed I once knew a 4-inch 

 pipe between two ponds blocked up by the bodies of two eels 

 which had tried to pass each other in opposite directions. All 

 danger, however, of this sort may be easily avoided by the simple 

 precaution of inserting between the two last pipes of the drain 

 a piece of perforated zinc, or galvanised wire-netting of a small 

 mesh. But where the water from a ditch is conducted into a 

 pond, it is very essential to filter it through a strong close wattle, 

 or better, through two, at a distance of a few feet from each other ; 

 otherwise the pond will be soon choked up, the ditch proving of 

 more harm than good. 



We now come to the second question, viz., is a pond in this 

 lowest part of the field likely to hold water ? And here the 

 would-be pond-digger will find a small acquaintance with geology 

 very useful. If he knows what stratum is subjacent to the surface- 

 soil, he can tell to what depth he may safely penetrate. Should 

 the stratum be porovxs, as sand, gravel, or limestone, he must not 

 dig down to it, for he could never depend upon his pond holding 

 water, except perhaps where the adjoining country is almost a 

 perfect flat ; as, for instance, an elevated table-land, or low-lying 

 meadows, where gravel is often a good water-bearing stratum. 

 If, however, there is any fall of the land in the neighbourhood of 

 the pond, a porous substratum will be almost sure to let out the 

 water. It is possible, certainly, so to puddle the bottom and 



