74 FORESTS, WOODS, AND TREES 
Sheep-grazing is from the waterworks’ point of view the least 
objectionable of farming pursuits. Grouse moors are still less 
objectionable, especially where the growth of peat is kept under 
proper control and suitable channels are cut for the water.” 
Sheep-grazing, though generally believed to be innocuous, 
is not without danger, as frequently the sheep die, and 
their dead bodies are found in the streams. In one 
gathering ground, in order to encourage early notice, the 
corporation offers 5s. each for the bodies of dead sheep 
that may be found. J. W. Hill of Cincinnati, who built 
many waterworks in the United States, criticised (3) severely 
the Edinburgh Water Trust for permitting sheep-grazing 
on the Talla watershed, and said it was a hazardous 
experiment. He instanced the occurrence in Switzerland 
and in the Rocky Mountains of epidemics of typhoid 
fever, due to the water supply being contaminated by 
eattle which grazed on the gathering ground. He objected 
to any occupation of the catchment area of a watershed by 
either man or animals. W. L. Strange (4) says: “ All 
surface catchments are liable to pollution, for even in 
pastoral areas there is contamination from man, animals, 
and vegetation, and filtration is therefore necessary. 
Pathogenic germs multiply rapidly and one cannot depend 
on their easy destruction. Silt in drinking water taken 
from rivers in India gives rise to bowel complaints, due to 
numerous minute flakes of mica in the silt.” 
In the gathering grounds which supply water to New 
York and Boston, U.S.A., there are numerous dwelling- 
houses; and the American engineer Hazen says it is 
unnecessary to remove the population from a water catch- 
ment area if suitable precautions are taken. Dr. A. C. 
Houston writes to me in reference to this: “ Hazen incurs 
serious responsibilities by such a statement. Everything 
turns on the perfected nature of the precautions, and 
certainly as a counsel of perfection an uninhabited area 
is most desirable. Still I am free to admit that by storage, 
filtration (5), and sterilisation the most impure water can 
be rendered safe for domestic use.” The question of supply 
