The St. Charles herald. [volume] (Hahnville, La.) 1873-1993, 1918-06-01

! WIN nave III pushing llle pTpJtCtHe
from its course either to the right or
left. These two corrections are
! brought together and determine the
amount In degrees and minutes that
the muzzle of the gun must be shift
| ed from the target to the right or
left in order that the projectile Will
curve toward its goal At last We have
| our gun controlled so that II will hit
the target
larry Just a moment. A gun. the
text books tell US. is the simplest form
of gas engine. Did you ever know
two gas engines of the same model
that acted alike? Neither will two
guns Of the same model.
The Fifty Per Cent Zone.
If YOU have an automobile you know
that the piston rings wear out, allow
ing gases to escape, and thus reducing
the force with which the piston is
forced down. Also the cylinder be-
comes scored with the same result.
Now, If you fire your gun many times
the same thing happens. The projec-
band Of copper the piston ring that
seals the bore. If the bore is eroded
or II the rotating bands are not per-
feet certain escape Of gases occurs
and the flight of the projectile Is con-
sequently affected.
Again there may be a difference In
the weight Of powder charges or In the
weight Of the projectiles, which win
give slight variations in the flight Of
the projectiles. So that the battery
commander must know the dispersion
Of each piece. This he finds out from
observation Of his shots, and It
changes as the gun grows older BY
figuring the deviation Of q certain
group Of projectiles from the target,
and which are known as trial shots or
fire for adjustment, he finds out what |
Is known rs the mean error of the |
gun. This, multiplied by the facto. /!
.S45, well known to students Of prob.
abilities, gives the mean probable err |
ror. Multiplying by two, the result In
yards Is what is known as the 80 per
cent zone, within which so per cent Of
his projectiles will fall. This compu-
tation Is done longitudinally and lati-
giving q certain Oblong strip.
If the center Of this strip can be
placed on the target by observation of
fire the battery commander has done
Ill that he can. and may now open
ire for effect. Four times the so
Der cent zone gives the 100 per cent
zone, within which practically all his
shots will fall.
knowledge Of these zones is all i'm
,ortant. BY this means he can figure
irst line trenches without numbering
'ur infantry, and. what IS almost as
important, when it is necessary to save
he can easily compute how
many shots will be necessary to make
certain number Of hits on a given
arget.
And what about camoufiage? The
nemy airplanes are on the alert and
II gun positions must be disguised.
he battery commander must be a
laster Of camoutlage, able to erect
helters and under their cover to build
is emplacements, while by the exer-
Ise Of discipline he Restraints his men
rom making tracks about the posi-
ons which Will give away to the all.
aeing eye of the camera in the air
lie fact that guns are mounted there.
So that is why the student officers 6
t Fort Monroe blistered their ]
AIDS and strained their backs erect 6
x camouflages and digging dugouts
N bombproofs; that is why they dove 6
nd crawled under motortrucks and r
alved into differentials and gear g
lses. emerging dirty and grimy, but t
Apply; that is why they toiled for v
ours at night, working out lengthy a
in trigonometry until angles t
,nced before their eyes when they I
led to sleep and endless chains Of F
garithms curved themselves through a
cir brain cells. r