n of individual
living, but also with those broader questions having to do with the
cause and spread of disease, with the transmission of bacteria from one
community to another, and with those natural influences which, more or
less under the control of man, may affect a large area if their natural
destructive tendencies are allowed to develop.

Being written by an engineer, the following pages deal rather with the
structural side of public hygiene than with the medical side, and in
the chapters dealing with contagious diseases emphasis is attached to
quarantine, disinfection, and prevention, rather than to etiology and
treatment. The book is not, therefore, a medical treatise in any sense,
and is not intended to eliminate the physician or to give professional
advice, although the suggestions, if followed out, undoubtedly will have
the effect of lessening the need of a physician, since the contagious
diseases referred to may then be confined to single individuals or to
single houses.

It has not been possible, within the limits of this one book, to
describe at length the various engineering methods, and while it is
hoped that enough has been said to point the way towards a proper
selection of methods and to a right choice between processes, the
details of construction will have to be worked out in all cases, either
by the ingenuity of the householder or by the aid of some mechanic or
engineer.

Finally, it may be said that two distinct purposes have been in mind
throughout,--to promote the comfort and convenience of those living in
the rural part of the community who, unfortunately, while most happily
situated from the standpoint of health in many ways, have failed to give
themselves those comforts that might so easily be added to their life;
and in the second place, to emphasize the interdependence of the rural
community and the urban community in the matter of food products and
contagious diseases, an interdependence growing daily as interurban
communications by trolley and automobile become easy.

Cities are learning to protect themselves against the selfishness of the
individual, and city Boards of Health have large powers for the purpose
of guarding the health of the individuals within their boundaries. The
scattered populations of the open country are not yet educated to the
point at which self-protection has made such authority seem to be
necessary, and it is left largely to an exalted sense of duty towards
t