g from a height downward.

(_e_) In the clear atmosphere of high altitudes.

_Objects seem more distant_--

(_a_) When looking over a depression in the ground.

(_b_) When there is a poor light or a fog.

(_c_) When only a small part of the object can be seen.

(_d_) When looking from low ground upward toward higher ground.

=1397. Effect of heat and cold.= Heat causes shots to strike high, and
cold causes them to strike low.

Therefore, if you shot on a warm day and made 5's, and recorded
temperature and other conditions in your score-book, you would know on
looking at your score sheets that you should raise your elevation, if
you were firing on a cold day.

=1398. Effect of moisture.= Dampness causes shots to strike high and
dryness causes them to strike low. Therefore, on damp days take lower
elevations than on dry days.

=1399. Effect of light.= Light affects the aiming without the beginner
knowing it. It does not, however, affect the travel of the bullet.

A dark target causes a tendency to aim farther below the bull's-eye
than if the target were bright. Therefore, use higher elevations with
dark targets. As it gets darker, higher elevations should be used.

If you _always aim carefully and correctly_ the light will have little
effect on your aiming,--that is, if your eyesight is good.

If you are shooting in a dull light and a bright sun comes out, say on
your right, there is a tendency to move the front sight to the
opposite (left) side of the rear sight notch, since the near (right)
edge is shaded and obscured somewhat. Therefore 1/4 to 1/2 windage
into the sun (right in this case) should be taken to overcome this.

In using battle sight, hold higher for a bright light.

We also raise our sights if a strong sun comes out. Therefore, we have
this rule: _Move your rear sight into the sun, just as you do for a
wind,--and raise your elevation._

=1400. Mirage= gives a wavering appearance to the target. It is heated
air that is moving. It is sometimes called "heat waves."

With the wind between 2 and 14 miles an hour on clear, hot days the
waves can be seen moving across the target.

When there is no wind or a light six o'clock wind, the waves go
straight up, or "boil." _Never fire when the mirage is boiling_,--wait
for it to move from one side to the other and then take windage to
correct for it.

=1401. Summary of temperature, light and moisture effects:=

_Raise elevation for_--