nts may easily be lost in the maze of trenches.

Latrines should be run out about 20 feet from boyaux at points
directly in rear of lateral trenches. If possible they should be
placed so that men cannot enter them without passing near the platoon
leaders. This will prevent men from leaving the front line, under the
pretense of going to latrines, during bombardments or mining
operations. The trench leading to a latrine should be constructed like
a boyau, and the pit should be close to the side nearest the enemy, to
give the best possible protection from shell fire. There are three
types of trench latrines: Deep boxes which are covered and have rough
seats; short straddle trenches or trenches equipped with a single
horizontal bar, and portable cans, used where the ground or the
limited space make it impossible to dig pits. These cans should be
emptied daily into holes behind the trenches, which are covered after
the cans are emptied into them.

Urinals should be separate from the latrines. They may be either holes
about three feet deep filled with stone, troughs with a covered pit at
the end, or portable cans.

Shelters. For the protection of men not actually on duty three forms
of shelters are used. The _splinter-proof_ is a form of light shelter
whose covering affords protection only against splinters. These are
usually on the reserve line. About 12 inches to 20 inches of earth
over a roof of logs or planks will afford protection from splinters
and shrapnel. Curved sheets of iron may also be used. The _deep
shelter_ or _bomb-proof_ is a chamber constructed by digging from the
surface and constructing a roof. To protect against eight-inch
shells the top of the chamber should be twenty feet below the surface.
Heavy beams or sections of railroad iron are laid across the roof.
Above them is a layer of earth several feet thick; then another layer
of timber extending to undisturbed ground on the sides with concrete,
crushed stone, metal, etc., above to make a percussion surface for
exploding projectiles that penetrate the upper layer of earth. This
layer fills in the rest of the space to the level of the ground.

[Illustration: Plate No. 20.]

Shelters should not exceed six feet in width, but can be of any
length. This will prevent the crushing in of the roof timber by the
explosion of a projectile buried in the upper layer of earth. The
principles of constructing shelters will be considered under
"Dugouts," as they