The Grangeville globe. [volume] (Grangeville, Idaho) 1907-1922, 1915-11-04


Heavy Arnor Plate Without ExpIod-
ing Until After its Impact Was Dis
covered by Accident.
Everybody knows that the modern
shell is one of the most diabolical Of
mans inventions. but how many OF us
realize that it is also one of the most
delicate and complicated?
Recently some firms holding con-
tracts for making high explosive shells
took upon themselves to correct a
detail in the specification. and, us re
suit. certain thread was improved"
They will never do anything of the
kind again, because all their work was
rejected. The apparent absurdity-it
is, in fact. an absolute absurdity, from
an engineering point of view-is de-
signed Of set purpose
There is a somewhat similar anon
ally In the big shell for penetrating
armor plating. which was introduced
In consequence of an accident. One
day test shell was fired at piece of
armor plating from the soft side, and
the projectile went clean through it
and exploded after impact, whereas a
similar shell fred against the 'front.'
the hardened and tempered side-shat-
tered and left an indentation of only a
few inches.
This singular incident set somebody
thinking. and In consequence the high
explosive armor piercing shell is now
given soft nose. To the hard point is
attached cap of soft metal. with
which addition 1t viii go through the
toughest piece Of armor plate. What
happens OH impact seems to be this:
The cap spreads. holding the point and
is revolving rapidly-to force its way
unbroken through the hard face OF the
plate by sort of boring action
No less curious is another fact con-
corning the points of such projectiles
After the heads have been worked the
shells are left for weeks before they
undergo the next stage, because. strong
as they look. they are liable to snap.
Why? Think of the razor. Constant
stropping twists the grain, with the re-
suit that the steel gets ''tired" and will
not yield a keen edge. But If you put
the thing away for few weeks the
grain will return to its normal state,
and you can get satisfactory shave.
In q. similar way the grain of the steel
Is affected by working, though OF course
TO much greater extent. and until it Is
ssset' the makers must go cautiously.
Steel shows like eccentricity In the
making of test gauges. Some of the
measurements Of shells are very fine,
and the instruments employed are so
delicate that they have to be used
quickly lest the heat of the hand causes
the metal to expand.
Now, when a groove is cut In piece
of steel which Is to be used as test
gauge the work Is laid aside for weeks,
perhaps months Why not finish 1t at
once? Because the groove. though dead
true when cut out. may be otherwise in
a short time, even though it has been
absolutely untouched.
As concrete proof of the elaborate
nature of projectile making take the
case of the shrapnel she'll The steel
portion undergoes about score of op-
erations, and the brass cartridge case
attached to the base requires about six
teen, counting from the disk Of sheet
brass to the finished article. Then
there is the fuse, the delicacy OF which
resembles matchmaking.
Altogether the shell is subjected to
about forty inspections and may be re-
5ected at any stage.
After shell has survived this ordeal
1t ought to be. one would think. per
feet. but test shell is taken from
every 100 and actually fired from a gun
into bank OF sand. 1t Is then again
examined. and IL the contour about the
powder pocket Is expanded away goes
the whole batch. because If they were
fired the growing might be torn out of
the gun.
Perhaps the most striking illustration
OF the minute care exercised In projec-
tile making Is that every shell Is weigh
ed over and over again. II you produce
an eighteen FOUNDER high explosive
shell 1t must be only few drains over
or under its normal weight: otherwise
20 is rejected.
In this connection It may be Of inter
est to note that an explosive shell that
weighs only about seventy pounds VIII
break into a shower of some LOO
pieces. A single one Of the monster
projectiles fred from fifteen inch ma
val gun win weigh 1850 pounds. II
takes twelve seconds for the projectile
Of a twelve inch naval gun to reach its
point Of impact when firing at a range
Of i've miles. To fire a battleship
broadside costs about $4,000. - Ex.
change.
Literal.