The Washington times., 1901-11-17

breech. These are pressure plugs. When
the powder explodes it congresses them
and thus is recorded exactly the pres
sure exerted in the powder chamber.
After the plugs are in a wire is fitted
over the muzzle. 1t connects with one
of the Instruments in the office and rec
cords the time when the shot breaks it.
Then, as the projectile pierces frame
after frame along the range. they too,
telegraph the exact instant to waiting
Instruments.
But even the practically instantane-
Gus record made by an electric record
er is not swift enough in itself. EIec-
tricity has to be helped with ingenious
/ means. The wires that are scattered
along the range do not lead to an in
I strument that makes a record on paper
. That would be far too slow They lead
/ to the queer apparatus of polished steel
: that has been mentioned as being able
to record inconceivable fractions of sec
onds. It is known as the Siebert velOci-
meter. Its noticeable feature is 4
chunky. beautifully polished cylinder of
steel, few inches long. 1t has one
sharply pointed end. By this end
! which is magnetic, it just hangs to an
upper supporting arm. When the shot
breaks the first wire it in turn breaks
the electTo-magnet that holds the steel
bar. and down il falls. II has only few
inches to drop. Yet before it falls that
/ short distance the projectile has smash
/ ed through framework after framework.
I As the successive wires break, success
} sive circuits are broken, and tiny sharp
! gravers shoot out from the sides of the
instrument and strike that falling bar.
Each graver marks it, and by the time
! the shct has struck its mark the little
! steel cylinder just about reaches the end
/ of it's drop. Now, knowing to the thou
sandth part of a second how fast it
dropped, the ordnance expert can calcu-
late the swiftness of the projectile by
measuring the distances between the
marks scratched on the cylinder by the
gravers.
To measure the recoil another simple
method is used. One end of q long thin
strip of steel, with its face smoked to
uniform blackness, is fastened to the
carriage of the gun. Near the muzzle
tuning fork so arranged that little
spur on one of its jaws just touches
the face of the blaekened face of the
steel band. When all is ready for firing
this tuning fork is set 10 vibrating by
an electrical instrument that makes it
vibrate exactly one thousand times
second, without varying by a single vi
bration. When the cannon is discharged
the recon naturally jerks the steel band
backward, and the little spur on the
fork marks a long waving line on the
steel. The band is dipped in a solution
that fixes the record so it will not rub
off. Knowing just how far the gun re
coiled, a matter that is, of course, meas
ured easily, it is merely a question of
counting the waves marked on the
steel to determine how many thou
sandth parts of a second ii required for
the weapon TO complete the distance. |
And by knowing the velocity of recoil
it is possible, calculating the entire
weight of the gun ard carriage, to find
out how great was the force of recoil
in pounds, which is a most important
factor in determining the strength of
emplacements where the weapon is to !
be mounted finally.
While Sandy Hook IS officially prov |
ing ground it is fully as important as
a testing ground. The difference be- |
tween the two is this: When the Gov |
ernment decides to adopt an arm of a i
certain pattern. type guns are sent to
the Hook before the United States COM
mits itself to the final purchase of that |
particular kind of cannon. These type |
guns go to the testing department, |
where they are subjected to the most |
severe tests and experiments that can
be devised. Practically the testing
ground officers try to smash the gun
They try it with maximum and mini
mum charges of powder and projectiIe.
They let it weather" They load it to /
the bursting point. Sometimes a gun |
will undergo tests for year or more, |
each shot being carefully recorded and |
a little history being written about it |
before the Government gets a final re- |
port on it. Many a cannon has had /
enough to fill big book written about |
it in successive reports of tests, and |
then been rejected. II a gun gets the |
20. k mark from Sandy Hook it is
a good one. Foreign Governments re-
alize that more keenly than do the peo-
pie Of the United States Foreign mill
tary-men consider the proving grounds
on Sandy Hook as one Of the most au-
thoritative Government departments in
the world, and its reports are at pre-
mium in every War Office on the globe.
If type gun doesn't develop fever
ish pulse before its test is ended. and
If it is accepted finally, more guns of
the same pattern are ordered. An army
officer superintends every step of their
manufacture and sees that each is male
exactly like the gun that was tested.
As each is finished it is sent to Sandy
Hook to be proved" Five shots are
fired from it under service conditions.
and if it acts correctly it is sent on to
a coast fortification. Not a single gun
is mounted today in fort unless it has
been through the hands of the proving
ground officers
Congress often kindly aids in making
Sandy Hook unpleasant It is common
for an inventor to get a bill through
ordering the War Department to test |
his weapon or his explosive. for the
testing and proving grounds are for
trying projectilcs shells. and explosives
as well as guns. Time and again ex-
plosives or weapons have arrived at
the Hook that were so bizarre and eyi-