p-proof course in the foundation
walls and extending up to the soil level. This water-proofing shall
consist of not less than two (2) ply of tarred felt (of weight
specified above), laid in hot, heavy coal-tar pitch, or liquid
asphalt, finished with a flow of hot pitch of the same character. This
water-proofing to be well stuck to the damp course in the foundation
walls. The layers of felt must break joints."

_Water-proofing and Damp-proofing of Cellar Floors._--"There shall be
laid, above a suitable bed of rough concrete, a course of
water-proofing consisting of not less than three (3) ply of tarred
felt (not less than fifteen (15) pounds weight per one hundred (100)
square feet), laid in hot, heavy coal-tar pitch, or liquid asphalt,
finished with a flow of hot pitch of the same character. The felt is
to be laid so that each layer laps two-thirds of its width over the
layer immediately below, the contact surface being thoroughly coated
with the hot pitch over its entire area before placing the upper
layer. The water-proofing course must be properly lapped on and
secured to the damp course in the foundation walls."

Other methods of damp-proofing foundations and cellars consist in the
use of slate or sheet lead instead of tar and tarred paper. An
additional means of preventing water and dampness from coming into
houses has been proposed in the so-called "dry areas," which are open
spaces four to eight feet wide between the house proper and the
surrounding ground, the open spaces running as deep as the foundation,
if possible. The dry areas are certainly a good preventive against
dampness coming from the sides of the house.

[Illustration: FIG. 4.

CONCRETE FOUNDATION AND DAMP-PROOF COURSE.]

_Subsoil Drainage._--By subsoil drainage is meant the reducing of the
level of the ground water by draining all subsoil water into certain
water courses, either artificial or natural. Subsoil drainage is not a
modern discovery, as it was used in many ancient lands, and was
extensively employed in ancient Rome, the valleys and suburbs of which
would have been uninhabitable but for the draining of the marshes by
the so-called "_cloacae_" or drains, which lowered the ground-water
level of the low parts of the city and made them fit to build upon.
The drains for the conduction of subsoil water are placed at a
certain depth, with a fall toward the exit. The materials for the
drain are either stone and gravel trenches, or, better,