xpiration.]

The patient is laid on his stomach, arms extended from his body
beyond his head, face turned to one side so that the mouth and
nose do not touch the ground. This position causes the tongue to
fall forward of its own weight and so prevents its falling back
into the air passages. Turning the head to one side prevents the
face coming into contact with mud or water during the operation.
This position also facilitates the removal from the mouth of
foreign bodies, such as tobacco, chewing gum, false teeth, etc.,
and favors the expulsion of mucus, blood, vomitus, serum, or
any liquid that may be in the air passages.

The operator kneels, straddles one or both of the patient's thighs,
and faces his head. Locating the lowest rib, the operator, with
his thumbs nearly parallel to his fingers, places his hands so
that the little finger curls over the twelfth rib. If the hands
are on the pelvic bones the object of the work is defeated; hence
the bones of the pelvis are first located in order to avoid them.
The hands must be free from the pelvis and resting on the lowest
rib. By operating on the bare back it is easier to locate the
lower ribs and avoid the pelvis. The nearer the ends of the ribs
the hands are placed without sliding off the better. The hands
are thus removed from the spine, the fingers being nearly out
of sight.

The fingers help some, but the chief pressure is exerted by the
heels (thenar and hypothenar eminences) of the hands, with the
weight coming straight from the shoulders. It is a waste of energy
to bend the arms at the elbows and shove in from the sides, because
the muscles of the back are stronger than the muscles of the
arms.

The operator's arms are held straight, and his weight is brought
from his shoulders by bringing his body and shoulders forward.
This weight is gradually increased until at the end of the three
seconds of vertical pressure upon the lower ribs of the patient
the force is felt to be heavy enough to compress the parts; then
the weight is suddenly removed. If there is danger of not returning
the hands to the right position again, they can remain lightly
in place; but it is usually better to remove the hands entirely.
If the operator is light and the patient an overweight adult,
he can utilize over 80 per cent of his weight by raising his
knees from the ground and supporting himself entirely on his
toes and the heels of his hands, the latter properly placed on
the ends o