know that for the sake of saving a few pounds (most likely that they may
be frittered away in senseless, showy features) it often happens, that
if even a damp course is provided in the outer walls, it is dispensed
with in the interior walls. This can only be done with impunity on
really dry ground, but in too many cases damp finds its way up, and, to
say the least, disfigures the walls. Here I would pause to ask: What is
the primary reason for building houses? I would answer that, in this
country at least, it is in order to protect ourselves from wind and
weather. After going to great expense and trouble to exclude cold and
wet by means of walls and roofs, should we not take as much pains to
prevent them using from below and attacking us in a more insidious
manner? Various materials may be used as damp courses. Glazed
earthenware perforated slabs are perhaps the best, when expense is no
object. I generally employ a course of slates, breaking joint with a
good bed of cement above and below; it answers well, and is not very
expensive. If the ground is irregular, a layer of asphalt is more easily
applied. Gas tar and sand are sometimes used, but it deteriorates and
cannot be depended upon for any length of time. The damp course should
invariably be placed _above_ the level of the ground around the
building, and _below_ the ground floor joists. If a basement story is
necessary, the outer walls below the ground should be either built
hollow, or coated externally with some substance through which wet
cannot penetrate. Above the damp course, the walls of our houses must
be constructed of materials which will keep out wind and weather. Very
porous materials should be avoided, because, even if the wet does not
actually find its way through, so much is absorbed during rainy weather
that in the process of drying much cold is produced by evaporation. The
fact should be constantly remembered, viz., that evaporation causes
cold. It can easily be proved by dropping a little ether upon the bulb
of a thermometer, when it will be seen how quickly the mercury falls,