to control the ship fore and aft, although
it is doubtful whether such a plan would
have any advantages, since this should be wholly
within the control of the pilot.

Laterally the ship should not be out of balance;
fore and aft this is a necessity, and as the great
trouble with all aeroplanes is to control them
laterally, it may well be doubted whether it would
add anything of value to the machine by having
an automatic fore and aft control, which might,
in emergencies, counteract the personal control of
the operator.

ANGLE INDICATOR.--In flight it is an exceedingly
difficult matter for the pilot to give an accurate
idea of the angle of the planes. If the air is
calm and he is moving over a certain course, and
knows, from experience, what his speed is, he may
be able to judge of this factor, but he cannot tell
what changes take place under certain conditions
during the flight.

For this purpose a simple little indicator may
be provided, shown in Fig. 66, which is merely a
vertical board A, with a pendulum B, swinging
fore and aft from a pin a which projects out
from the board a short distance above its center.

The upper end of the pendulum has a heart-
shaped wire structure D, that carries a sliding
weight E. Normally, when the aeroplane is on
an even keel, or is even at an angle, the weight
E rests within the bottom of the loop D, but
should there be a sudden downward lurch or a
quick upward inclination, which would cause the
pendulum below to rapidly swing in either
direction, the sliding weight E would at once move
forward in the same direction that the pendulum
had moved, and thus counteract, for the instant
only, the swing, when it would again drop back
into its central position.

_Fig. 66. Angle Indicator._

With such an arrangement, the pendulum would
hang vertically at all times, and the pointer below,
being in range of a circle with degrees
indicated thereon, and the base attached to the
frame of the machine, can always be observed,
and the conditions noted at the time the changes
take place.

PENDULU