298 
SCOURING LANDS OF CENTRAL SOMERSET. 
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 
O O 
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 pre¬ 
ceded 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 sugges¬ 
tive 4 PrizeEssayonthe 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. 
c. Facts connected with Water. 
8. Certain waters in districts where scouring prevails 
appear to have a decided medicinal effect on the health of 
cattle that drink them. 
* ‘Journal of the Bath and West of England Society, 5 vol. iii, p. 52. 
