nual dampness in neighboring cellars, on lower ground, to the
manifest discomfort of those occupying the houses.

_Composition of soils._

Having thus discussed the location of the house with reference to its
surroundings, let us now more carefully examine the character of the
soil or earth foundation on which the house shall be built. All soil is
made up of varying proportions of mineral and vegetable matter in the
interstices of which there are usually to be found more or less air,
water, and watery vapor. The mineral substances of soil include almost
all of the known minerals, although many of them are found in
exceedingly small quantities. The most common and the most important
mineral elements of the soil of New York State are carbon, silicon,
aluminum, and calcium, which combine in various ways to make either
sand, sandstone, clay, shale, limestone, or other rock. The particular
form which these mineral elements assume is of interest in choosing a
location for a house, for two reasons:--

In the first place, it has been asserted that the mineral constituents
of a soil directly affect the health of persons living on that material.
For instance, the earlier writers on hygiene gravely pointed out that
very hard granite rocks, when weathered and disintegrated, became
permeated by a fungus and caused malaria. We are, however, now so sure
of the cause of malaria that we only laugh at a theory upheld by
scientists of only twenty years ago.

Some constitutional diseases, including goiter and cancer, have been
supposed to flourish in localities where an excess of calcium exists in
the soil, and it is true that these diseases do have an unusual
prevalence in certain limited districts; but no modern scientist
ventures to say whether the boundaries of those districts are determined
by the character of the soil constituents or by some other predisposing
factor. The truth is that, in matters not absolutely determined by
science, many theories usually have to be evolved and proved worthless
before the real cause is found.

In the matter of appendicitis, for instance, it was formerly asserted
that the seed of grapes was responsible for the local inflammation, and
that one could never have appendicitis if such seeds were not swallowed.
This theory is to-day almost forgotten, and one eminent surgeon has
asserted that the prevalence of this disease in a district depends on
the calcium in the soil, since it is to that mineral th