se and has followed its brother or sister to the
grave. Cases of tuberculosis have been known to follow each other almost
year after year, as one member of a family after another occupied a room
where the infection persisted, either in the carpet or furniture, which
was never properly disinfected. Such cases must be left to the good
sense, intelligence, and understanding of the persons concerned. The
police power can never in this age take the place of an enlightened
sense in the community, nor are laws, as a matter of fact, of any use
except as they are sustained and enforced by public sentiment.

QUALITY OF WATER

There is another way in which the police power of the state exercises
control over rural communities, and that is in the matter of food which
the country generally supplies to the city. Perhaps the pollution of
water, which is, after all, one kind of food, is as important as any
matter covered by health laws.

In most cities to-day the pollution of streams is prohibited on two
grounds, first, that the streams are public property, even though for a
part of their course they may be owned individually. The sum of the
parts making up the whole stream involves so many individuals as to
imply public ownership, and inasmuch as one individual is limited in
his uses of the stream by the principle already referred to, he cannot,
even on his own land, do what he pleases with a stream or with its
waters. When streams are navigable, according to the law of this
country, no private ownership can exist, for the waters are controlled
and owned by the federal government. This latter body, in general, does
not undertake to control the quality of such waters, but there are many
laws covering the quantity of water in such streams, limiting the
amounts that can be withdrawn, restricting the filling up or silting of
such streams, and qualifying the bridging or damming of such waterways.
In small streams, such as are generally found in rural communities, the
vital principle of ownership is always limited by the requirement that
no owner shall so interfere with the normal quantity or quality of water
in the stream as to prevent their full enjoyment by the next man
downstream whose rights are equal with his own. This means, in the
matter of quantity, that while one individual may water stock in a
stream or may pump water from a stream for household use, he may not
withdraw from the stream the entire volume to use for irrigation,