is to determine what the pressures are at
the different angles between the horizontal, and
laws have been formulated which enable the pressures
to be calculated.

DIFFERENCE BETWEEN LIFT AND DRIFT IN MOTION.--The
first observation is directed to the differences
that exist between the lift and drift,
when the plane is placed at an angle of less than
45 degrees. A machine weighing 1000 pounds
has always the same lift. Its mass does not
change. Remember, now, we allude to its mass,
or density.

We are not now referring to weight, because
that must be taken into consideration, in the
problem. As heretofore stated, when an object
moves horizontally, it has less weight than when
at rest. If it had the same weight it would not
move forwardly, but come to rest.

When in motion, therefore, while the lift, so
far as its mass is concerned, does not change, the
drift does decrease, or the forward pull is less
than when at 45 degrees, and the decrease is less
and less until the plane assumes a horizontal position,
where it is absolutely nil, if we do not consider
head resistance.

TABLES OF LIFT AND DRIFT.--All tables of Lift