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then established himself, in order that, where he found worship 
already bestowed, he might lead it in the right direction. 
I propose therefore to consider the subject under the following 
heads :— 
Sources of supply. 
Quality of water supplied. 
Distinction of hard water from soft. 
Purifying water on a large scale. 
Purifying water on a small scale by filters. 
The water used for domestic purposes is derived from and 
dependent upon the rain-fall, whatever the immediate source, 
whether from wells, rivers, or springs. 
Rain water may be considered as absolutely pure when collected _ 
away from the impurities which always exist, more or less, in the 
atmosphere of large towns; and were it possible to collect it in 
sufficient quantities under such conditions, no better water could 
be desired for general purposes, but practically this is impossible, 
and so we are necessarily driven to seek for other sources of 
supply. 
One of these sources is that from wells—The water obtained 
from wells, properly constructed, is usually clear and limpid, but, 
as in springs, it partakes of the character of the strata through 
which it percolates ; and when derived from wells situated in towns 
or amongst buildings it cannot be held as desirable, on account of 
the danger of organic matter introducing itself. Such pollution has 
been found to exist when the infecting cause has been discovered 
at great distances, and only traced with difficulty—an instance of 
this occurred in the town of Croydon. 
In the case of Artesian wells, where the supply is drawn from 
deeper sources, this danger of contamination may be disregarded ; 
and where a sufficient supply can be obtained of suitable water, 
they have many advantages. It frequently happens, however, 
that after continued use the supply diminishes, and care has to be 
