2 VOELCKER on the Scouring Lands 



have to be considered in forming- a comprehensive and satisfac- 

 tory theory on this subject. Hence of all the explanations hitherto 

 offered, the best are but partially true, and they are frequently 

 irreconcilable with established facts. 



Leaving unnoticed several of the more palpably erroneous 

 surmisings, it may be observed that the cause of scouring, to 

 which cows and calves, and in a minor degree horses and sheep, 

 are liable on certain pastures, has been referred : 



1. To injurious substances which are supposed to exist in lias- 

 clay and scouring lands generally. 



2. To defective or inefficient drainage. 



3. To the drinking of water in districts where scouring 

 prevails. 



4. To certain medicinal plants, such as the Linum cathar 

 ticum, supposed to abound on scouring land. 



5. To injurious constituents of scouring herbage. 



6. To the poor and innutritious character of the herbage on 

 scouring meadows. 



The critical examination of these six theories may be preceded 

 by some facts gathered during a professional visit to some of the 

 worst scouring land on the Polden Hills, and by several statements 

 contained in Mr. Clarke's highly suggestive Prize Essay on the 

 Scouring Lands of Central Somerset.* 



On sifting carefully the practical evidence at our command, 

 little or no doubt, I think, can be entertained respecting the 

 reality of the following classified facts. 



a. Facts connected with the character of Scouring Land. 



1. Scouring land is most prevalent in the lias-formation. 



2. Such land is generally dark-coloured, and invariably rests on 

 an impervious clay subsoil. 



3. There is scouring clay-land resting on similar yellow or 

 blue tenacious clay subsoils, but not belonging to the lias-clays. 



4. On the other hand, not every lias-clay soil possesses this 

 peculiarity. 



5. No special analytical examination of scouring land and of 

 lias-clay subsoils has as yet been published. 



b. Facts connected with Drainage. 



6. In certain seasons cattle scour on some perfectly well- 

 drained soils, as much as on undrained pastures. 



7. In other well-authenticated cases drainage was found a 

 perfect cure. 





 * Journal of the Bath and West of England Society, vol. iii. p. 52. 



