The St. Charles herald. [volume] (Hahnville, La.) 1873-1993, 1918-05-25

Will have in pushing the proJectls
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 OF
left in order that the projectile VIII
curve toward its goal. At last we have
our gun controlled so that II Will nit
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 De-
comes scored with the same result.
Now, If you fire your gun many times
the same thing happens. The pro1ec-
tile Is the piston and the retaining
band of copper the piston ring that
seals the bore. If the bore Is eroded
or II the rotating bands are not per-
feet a certain escape Of gases occurs
and the flight Of the projectile Is con-
SeQuently affected.
Again, there may be q difference IN
the weight Of powder charges or In the
weight Of the protectiles, which VIII
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 II
changes as the gun grows Older. by
figuring the deviation Of certain
group Of projectiles from the target
and which are known as trial shots OF
fire for adjustment, he finds out what
is known as the mean error OF the
gun. This, multiplied by the factor
s45 well known to students of prob
abilities, gives the mean probable er
ror. Multiplying by two, the result IL
wards is what is known as the 90 pei
cent zone, within which so per cent OF
; his projectiles will fall. This compu
totion Is done longitudinally and latf
tudinally, giving q certain oblong strip
If the center Of this strip can o.
nlaced on the target by observation o.
, FRO the battery commander has don'
al that he can, and may now opei
Ara for effect. Four times the o.
, nor cent zone gives the 100 per cen
, zone. within which practically all nj
, shots will fall.
Knowledge Of these zones is all I'm
5 nortant. BY this means he can tigur
: ont how near he can come to our owl
, first line trenches without murderlnl
y orr infantry, and, what is almost a
(. imnortant, when it Is necessary to saw
( ammunition he can easily compute nov
| | many shots will be necessary TO max
q certain number Of hits on givel
2 target.
! And whit about camoufiage? tn
e enemy airplanes are on the alert an
n oil pun pOsitiOnS must be disguised
q Tho battery commander must be
!. master Of camOuflage, able to erec
j shelters and under their cover to bull
:. his emplacements, while by the excl
t else of discipline he restrains his me
e from making tracks about the pos
: tions which will give away to the al
q seeing eve Of the camera In the al
) the fact that guns are mounted ther'
|. So that is why the student omcei
r Of Fort Monroe blistered thel
=. hands and strained their backs cree
Ing camouhages and digging dugou'
J. ana bombproofs; that is why they doE
d and crawled under motortrucks an
/. de,yed into differentials and ges
Is cases. emerging dirty and grimy, o.
I. nanny: that is why they toiled Il
Is bours at night, working out length
ID problems in trigonometry until angie
h. danced before their eyes when the
D. tried to sleep and endless CHAINS
ID Ioparithms curved themselves throue
ID their brain cells.
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