ume gradually some
abnormal angle, without his own sensations telling him what is taking
place. The craft may, for the sake of illustration, incline sideways,
imperceptibly to the pilot, till it begins to side-slip. But science
can meet this danger by providing inclinometers, fitted within the
hull so that the aviator can see them easily; and by means of these
instruments, which are illuminated at night, it is possible for a
pilot to tell, merely by a glance, at what angle his machine is moving
forward through the air--whether it is up or down at the bow, or
whether its position laterally is normal.

The beginner, on his first cross-country flight, need not be troubled
by such intricacies. He is flying, one assumes, on a fine day, with
the land spread clearly below him. So as he moves through the air,
listening always to the hum of his motor, he need have no fear,
granted that his observation is ordinarily keen, of losing his way.

Naturally, being a novice, he will feel the responsibility of his
position. His eyes will rove constantly from one instrument to another;
as indeed, from habit, do those of a practised flyer. He will glance
at the height recorder; then at the engine revolution indicator; then
at the dial which tells him what his speed is relative to the air.
There is a dial, also, showing the pressure in his petrol-tank; while
there will be a clock on his dashboard at which he will glance
occasionally, after he has marked some position away on the land below,
so as to determine what progress he is making from the point of view
of time.

Besides these preoccupations, and the ceaseless even if almost
unconscious attention that he must pay to his engine, there is the
need to bear constantly in his mind's eye the lie of the land. Should
his motor fail suddenly, or something happen which necessitates an
immediate descent, it is imperative that he should be able, without
delay, to choose from the ground that is visible below him some field
or open space that will provide a safe landing-point. And this is
easier said than done. The earth, when viewed by a airman who looks
down almost directly upon it, is apt to be deceptive as to its
contour. A field that is selected say, from a height of several
thousand feet, may not prove--as the aviator nears it in his glide--to
be at all the haven he imagined it. More than once, seeking to alight
on a field which appeared to him, as he was high above it, to be level
as a bi