G48 
Gotfiige Sanitation. 
which can be easily removed to allow of frequent cleaning. Both 
roof and cistern should be cleaned by brushing at least once or 
twice a year. 
It is well to allow the water to run through a wire netting 
into the cistern, so as to keep back straws, dead leaves, &c. Dr. 
Mitchell Wilson, of Doncaster, finds a box with a perforated zinc 
bottom, containing sand and gravel, useful for this purpose. 
Roberts’s “ percolator,” or “ rain-water separator,” does this 
by directing the first rain that falls into the drains, by means of a 
vessel which tilts over when full and then allows the rain water to 
pass into the cistern. In this way the roof and gutters are 
washed before the water is collected from them. 
Treatment of Impure Water. 
Filters . — In nearly every case where there is any suspicion 
of impurity in the water it may be rendered safe by filtering 
and boiling. There are many filters on the market, and with 
reference to them 
all it must be 
remembered that 
no filter is eapahle 
of acting j^rojyerlg 
without frequent 
cleansing or re- 
newal. 
The writer 
has known a 
filter to be used 
for ten years 
Fio. 13. -Sandstone Filter without being 
renewed, and it 
might have been in use still had not several cases of sore throat 
occurred in the house. 
One of the cheapest and simplest filters for cottage use is 
composed of a block of charcoal in the bottom of a glass funnel, 
the water having to pass through a considerable thickness of the 
charcoal before issuing. The charcoal block can easily be taken 
out, scrubbed, and roasted in a hot oven, and is again ready for use. 
Another simple filter can be made as follows : — 
Take an ordinary flower-pot of 12 indies in height, and in 
Ihe bottom put a layer of clean gravel, then one of finer 
gravel and sand, a layer of animal charcoal, and another layer of 
sand, each about inch in depth. The water is poured in at 
the top and filters out at the bottom. Such a filter should be 
