r the frozen earth to cling
to and by expansion tear off from the wall. If smooth, the joints in the
masonry can be pointed or filled with mortar, and thus a suitable
surface for the tar or asphalt is provided.

[Illustration: FIG. 9.--Rough-backed wall.]

In Fig. 9 (after Brown) is shown a cellar wall with rough, irregular
back, and it is easy to see how water would readily find its way down to
one of the projecting stones and then along such a stone, through the
wall into the cellar. With such a wall the action of the frost is more
severe than with a wall with a smooth back, so that the wall in Fig. 9
is gradually pulled apart by alternate freezings and thawings. Figure 10
(after Brown), on the other hand, shows the cellar wall as it should be
with smooth, even exterior, along which the water passes easily, with
gravel backing, through which the water escapes to the drainpipe.

[Illustration: FIG. 10.--Even-backed wall.]

_Damp courses in walls._

[Illustration: FIG. 11.--Four modes of making water-proof cellar walls.]

Another important means of keeping moisture from the cellar walls is to
provide what is called a damp course at about a level with the top of
the cellar floor. Where the soil is naturally damp, and where the cellar
wells are not adequately water-proof, a second damp course should be
provided at the level of the ground so that moisture from the damp
cellar walls may not pass up into the above ground portion, which is
naturally dry. These damp courses, in their simplest form, consist in
bringing the masonry level around the building, and painting the top
surface with liquid coal tar.

[Illustration: FIG. 12.--Waterproofing of cellar walls.]

Another method is to paint the masonry with liquid asphalt, and then
imbed in this paint a thickness of asphalt-covered building paper which
is again painted with asphalt. This may be done in the horizontal layer
where it could not conveniently be done vertically.

Four different ways used in France for securing dry cellar walls are
shown in Fig. 11. The heavy black line represents the damp course,
which, when added to the effect of the interwall space, which is shown
in all the drawings but the first, and there replaced by a deep drain,
insures absolute freedom from all moisture within the cellar. Figure 12
shows sections recommended by Dr. George M. Price, and indicates clearly
the location of the damp course.

_The cellar floor._

The floor of the cel