ical and sub-tropical countries. Much importance likewise attaches to
houses being thoroughly ventilated, and to their being sufficiently roomy
to properly accommodate their inmates. The following table shows the
striking relationship that mortality bears to over-crowding:--

RELATION OF DEATH-RATE TO DENSITY OF POPULATION.

City. Mean number Average death-rate
of inhabitants per 1,000 inhabitants.
to each house.
London 8 24
Berlin 32 25
Paris 35 28
St. Petersburg 52 41
Vienna 55 47

Many other statistics could be quoted, but all follow the general trend
of those just given.

_Choice of Site._--In our rural districts the inhabitants have a wide
latitude in the matter of the selection of the location for their
houses, and it is usually the case that our people are sufficiently
intelligent to make the best use of their opportunities in this
direction. It may, however, be mentioned that it is generally considered
that building-sites in the neighborhood of cemeteries are not favorable
locations, nor should houses be erected in the vicinity of a
manufacturing plant that gives off injurious gases, or obnoxious
materials of other kinds. Inasmuch as we now know that malaria is
transmitted by a certain mosquito, and that by properly screening the
house their attacks may be avoided, the necessity no longer exists for
avoiding the vicinity of lakes and rivers as building-sites; such
localities being as a rule pleasant and often picturesque, they would
naturally under ordinary circumstances be selected, and there now remains
no reason why this may not be done,--provided that the house is so
constructed that mosquitoes can be effectually prevented from gaining
entrance.

Of much importance is the selection of a locality where good and pure
water can be easily procured, as otherwise disastrous consequences are
sure to follow.

The soil should be of a light and porous character, easily permeable by
water, and free from the decomposing remains of excretions of man or
animals. There is much reason for the belief also that the level of the
ground-water plays a somewhat important part in the salubrity of any
given locality, and it is generally considered that this should be at
least ten feet below the surface. It