materials occasionally used are concrete, granite, marble, and
sandstone, any of which, on account of their durable character and the
beauty that they lend to structures made from them, may be selected for
building purposes, but inasmuch as they are rarely used in rural
districts, a detailed consideration of their peculiar advantages for
building purposes is not deemed here necessary.

The internal wall-coating of houses deserves more consideration than is
commonly accorded it, since the dyes used for coloring wall-paper and
curtains in some instances contain noxious materials. Chief among those
that are dangerous are the bright green pigments which commonly contain
arsenic as their principal constituent; where these or other poisonous
substances are employed in interior decorations the air, wherever the
room is kept closed, may become more or less impregnated with poisonous
gases, and serious consequences to the inmates may ensue.

_Screening Indispensable to Health._--Nothing is more important in
connection with house construction than having every opening thoroughly
screened. We have learned that both malaria and yellow fever are
transmitted always by certain kinds of mosquitoes, and it therefore,
becomes a matter of the greatest importance to effectually prevent the
entrance of these insects. It cannot be too strongly insisted upon that
we absolutely know that the statement just made is correct, and that
avoiding the diseases referred to becomes as a consequence entirely a
matter of preventing the entrance of mosquitoes into houses.

[Illustration: Fig. 1. ANOPHELES. (Malarial Mosquito.)]

[Illustration: Fig. 2. CULEX. (Common Mosquito.)]

The _Anopheles_ mosquito, which is the one that transmits malaria, often
exists in localities where the more common varieties do not occur, and on
account of the habits of this insect their presence is liable to be
overlooked. They seldom attempt to bite during the day, and it is only
rarely the case that they try to do so at night in a well lighted
room;--particularly where movement of any kind is going on. During the
day this mosquito remains perfectly quiet in the dark corners of the
house, and is very fond of resting on cobwebs, presenting, when doing so,
an appearance strikingly similar to that of fragments of leaves, soot or
of other natural objects that are frequently found suspended on such
structures. On account of these peculiarities and for the further reason
that