NATURAL HISTORY. 
31 
desirable that can be found for the production of 
every vegetable ; and in this manner it cannot but 
materially contribute to the salubrity of any country^ 
of which it is the prevailing rock." 
In confirmation of the truth of the principles here 
laid down by Dr. Henry^ it may be stated that the 
whole of this county in which the sand stone prevails 
enjoys a great freedom from severe febrile diseases^ 
the worst forms of typhous fever being rarely 
witnessed; and from my own experience I may 
assert that the hilly parts of Worcestershire^ where 
there is a clay soil^ as about Broadway, and the line 
of hills running in that direction, are much more 
prone to be affected with fever than the sand- 
stone district which comprises the lower parts of the 
county. This immunity from severe forms of fever is 
not confined to the rural population ; but is in a 
great measure also to be observed in the large towns. 
In Worcester it is a very rare thing to meet with 
very severe cases of fever, and the worst forms of the 
disease in this town are seen after flood-time in the 
vicinity of the river Severn. This river, which rises 
in Plinlimmon, in Montgomeryshire, becomes of con- 
siderable size before it enters Worcestershire a little 
above Bewdley. The bed, in its entire course through 
the county, is several feet below the banks ; it has 
been stated on an average 18 feet. This circumstance 
necessarily detracts considerably from the effect that 
would otherwise arise from so fine a stream passing 
through so rich a country. It does not, however, 
prevent the valley through which the river passes 
