in turn and until it has silenced it. (546)

_In addition to the above, which the Infantry Drill Regulations gives
on the subject of machine guns, the following, based on the use of
machine guns in the European War, is given:_

=561. Machine guns essentially automatic rifles.= They are essentially
automatic rifles, designed to fire the ordinary rifle cartridge and
capable of delivering a stream of small bullets at a rate of as high
as 600 per minute. Experience in the European war has determined that
the rate of 400 shots per minute is the desirable maximum. Their
ranges are the same as for the rifle. The fire of a machine gun has
been estimated as equal to that of 30 men.

=562. Mounts.= Machine guns are usually mounted on tripods or wheels.
The weight of certain types is such that they can readily be carried
by the soldier from one point to another.

=563. Methods of transportation.= While machine guns are usually
designed to be carried or packed, they are easily adapted to various
methods of transportation. In the European war we find them mounted on
sleds during the winter campaign; on specially designed motor cycles
with side cars and accompanied by other motor cycles carrying
ammunition; on wheels; on wagons; on armored automobiles; aeroplanes;
and finally in the powerful "tanks" of the English.

=564. Concealment.= Machine guns while usually considered as _weapons
of emergency_ have been used in attack and defense in the European war
in all stages. Their mobility and deadly effect have made them of
great value. Once their position is discovered they are quickly put
out of action by artillery. Owing to this fact the armies in Europe
have used alternative positions and have used every means to conceal
the guns. Hedges, walls, and pits are used and every effort is used to
conceal the flame of discharge. This is usually accomplished by
keeping the muzzle well in rear of its cover or loop hole. Machine
guns almost invariably betray their positions as soon as they enter
into action. The present tendency seems to be to hold them concealed
and place them into position in the trenches or emplacements at the
moment of combat.

Extraordinary means have been resorted to in hiding the guns until
they are needed. In the German line, dugouts underground were
constructed to conceal the machine guns and crews. Often they
permitted the first line of the attack to pass over them and then
appeared in rear and opened a deadly