Water in Relation to Health and Disease. 741 
it falls or by first percolating through the soil, while the means 
adopted for its artificial storage usually take the form of reser- 
voirs, wells, and tanks. From these it is distributed for use in 
various ways, — by open conduits, by covered drains, or by pipes 
of different kinds. In all these situations water is exposed to 
contamination, not only of an ordinary and harmless kind, but 
also of a hurtful and often of a poisonous character. The ex- 
tension of our mining and manufacturing industries and of other 
works has added considerably to the demand for water as a 
power in recent years, and also as a means of washing and 
manipulating ores and textile and other materials. In 
mining districts of the West and manufacturing districts of 
the North the river banks have become crowded with mills, 
mines, and manufactories, and every year there has been a 
growing activity in the many and various industries which they 
represent. Having regard, however, to the immense amount of 
polluting matter which the streams and rivers of this country 
receive daily, and the many poisonous compounds used in manu- 
facturing and other processes which pass into them, it must be 
confessed that the sickness and mortality resulting to live stock are 
from this cause, comparatively small, and there can be no doubt 
that the chemical and other methods which in recent years have 
been adopted to utilise what was formerly treated as “ waste ” 
have done much to render it so. Nevertheless, our rivers con- 
tinue to suffer serious pollution, and the land adjoining some of 
them has not only been adversely influenced, but in some 
instances altogether unfitted for agricultural purposes. Much 
of the immense amount of refuse annually cast out of collieries 
and mines has for economical and other reasons been thrown 
into adjacent streams. As a result, the beds of rivers have 
silted up, and their holding capacity has been greatly diminished. 
This has caused flooding of land, and led to the deposit of large 
quantities of polluting refuse on the pastures. Injury to herbage 
and to animals eating it has necessarily resulted, and in this 
way pollution of rivers has occasioned serious losses to farmers 
and landowners. In the course of inquiry into rivers’ pollution 
in 1874 it was shown that cattle frequently became sick, and 
not seldom died, after grazing upon meadows covered with mine 
refuse and colliery detritus, and instances were recorded in which 
as much as two pounds of coal dust was found in their stomachs 
after causing violent purging and fatal ulceration. 
Nearly every mining and manufacturing process gives rise to 
an effluent refuse more or less deleterious to life. The existence 
of some of these forms of refuse is made known by the peculiar 
discoloration of the water into which they flow. Some rivers of 
