uarters; four or five on duty at each platoon
headquarters; five from each machine gun company to
battalion headquarters. Messages sent by them should, if
practicable, be written and signed, and should be receipted
for by the addressee.
(c) By rockets and flares. Quickest means of liaison with the
artillery in rear.
(d) Domestic (message carrying) grenades.
(e) Dogs and carrier pigeons. Sent out to the rear from
battalion headquarters.
(f) One searchlight--with a radius of 3 miles--is furnished to
each company.
(g) Noise. Klaxon signals, etc., give warning of gas attacks.

E. OBSERVATION:

(a) Observers:
1. Must be men of infinite patience, keen hearing and
eyesight.
2. They are located behind the first line in positions
combining good view with concealment.
3. Each is provided with a panoramic map, made from
aeroplane photographs, of the enemy's trenches. On this
must be promptly noted every slightest change in the
trace, height of parapet, etc., of the enemy's line. Such
notes greatly assist in locating machine gun
emplacements.
4. Each observer will also record in a note book everything
of importance, with the time observed.
5. A report of changes, with an abstract of observer's
notes, is forwarded daily to regimental headquarters.
(b) Watchers (sentinels):
1. Stationed, one near the door of each dugout, in the
first line, support and intermediate trenches.
2. They must be carefully concealed.
3. They must watch over the parapet (never through slits or
loopholes) so as to have unrestricted view.
4. They are furnished with signal rockets and flares for
prompt communication with the artillery, and have
authority to use them.
5. Double sentinels are posted at night.
(c) Listening Posts:
1. Located, usually in shell holes, just inside the
entanglements. Connected with front line by tunnels.
Protected from grenades by heavy gratings, when
possible, and by concealment.
2. Occupied by 4 men (1 in command), in 3 reliefs. Usually
occupied only at night unless our