SOME DEW-PONDS IN DORSET. 25 



In re-making two ponds for me on Stratton Down Mr. 

 Lane, a well-known pond maker, of Fordington, used first 

 a layer six inches thick of well-worked-up clay laid on the 

 solid chalk, then a coating of gas tar, to prevent the worms 

 working through, then another six inches of puddled clay, 

 the whole being covered with a coating of flint pitching to 

 prevent the cattle treading the clay, no straw being used. 

 As rain or mist ponds these have been most successful. 



Thus it will be seen there is a great divergence of opinion 

 as to how these ponds should be formed, but I think it will 

 be generally admitted that rain, mist, and fog are the chief 

 elements which contribute to their supply. 



I now propose to give you some account of my researches 

 in this direction, on the downs around Dorchester during 

 the late summer, and for the convenience of reference I 

 propose to number my ponds. 



No. 1, 



Which, for the sake of further distinction, we will call the 

 " Grimstone Down Dew-Pond," I examined on the 3rd 

 of August, 1911. This pond on plan is practically square, 

 being 42 feet by 40 feet in measurement at the top of the 

 bank, with runlets at the corner angles ; it is 6ft. Gin. deep, 

 including the bank, and as there is a silting up of about a foot, 

 the original depth would have been 7ft. 6in. It is made on 

 the north-west side of the hill, and would command a con- 

 siderable gathering surface. It is placed some 580 feet 

 above sea-level, as shown by the contour on the Ordnance 

 Map. It is covered with vegetation, and has not been known 

 to contain water within living memory. On cutting a trench 

 through the centre I first came upon a layer, some 10 inches 

 thick, of black alluvial soil, which had the appearance of a 

 silting up, or might have been decayed vegetable matter. 

 Then came a carefully laid layer of packed flints, followed by 

 a layer of stiff red clay mixed with lime, which appeared to 

 .have been laid on in layers on the solid chalk, to a thickness 



