Evening star. [volume] (Washington, D.C.) 1854-1972, 1894-07-21

knife against the side Of the larger weight
and dents its polished surface. That dent
measures on the side OF the long weight,
the difference in time between the starting
of The long ani the starting of the short
weight. That difference in time divided by
the distance between the screens Is the
velocity of the shell at a point midway be-
tween the screens. table hanging on the
wall. carefully computed. shows the iea-
tive speed at the moment the projectile
left the mouth of the gun. The process Is
Doth simple and quick. In minute after
the proiectile has been fred, the operator
in the office touches the signal button and
rings to the operator at the gun the figures
showing the speed of the projectiie. There
are.three of these chronographs and one CT
them is check on each of the others.
Mounting Gums and Armor.
The chronogra PHI is a French invention
and. in fact. most of the ideas for the naval
proving ground came from France 1t is
said that there is private proving ground
In France which is the finest in the world.
Experiments TO prove the efficiency Of ar
NOR, projectiles and powder are a matter of
twenty-five years in our navy. Until three
years ago these experiments were conducted
at Annapolis. In 1891 the proving ground
was es tablished at Indian Head because the
location was more convenient When heavy
ordnance is to be tested, II Is loai ed on
car and shipped on a barge from the navy
yard at Washington. At the wharf at In
dian Head this car is run off, and with a
steam capstan Is hauled through the valley
TO the place where the gun Is to be mount
ed. 1t takes day two to set mp a big
gun big travelling crane swings il into
the air and drops it on the carriage. 4
thirteen Inch gun has been mounted in a
single day. but that is a record
To mount piece of armor for a test Is
even more difficult and slow. Armor is
mounted against an oak backing thirty-six
lhghes thick-usuaily three thicknesses Of
OAK timber bolted together This backing
Is prepared at the navy yard and shipped
TO Indian Head. When the backing has
been mounted against bank of sand, the
armor plate is lifted into place and bolted
there. Then all hands stand aside and Mr..
Mason turns loose one OF his big guns Ii
the projectile does not make mincemeat OF
TIE plate. 1t passes the test. Not infre-
qucntly the big l.eW-pound protectil IS mere
~ rdb their noses against the armor, leav-
Ing little dent. Sometimes they bury
themselves little way in it and stick there
sometimes they shattered into frag-
mentS.
Expensive Experiments
These armor experiments are expensive
Not long ago all armor plate iepresen; ing
d group OF plates manufactured by the
bethlehem iron worAs, was put up to be
shot at and the gunner sms shed it to pieces
Its value was S20.0DD-just that one piece
II the plate had proved effective-if it had
paid fer it, as the plate was a failure the
loss fell on the contractor He lost not
only that $1,000 plate. but the group of
Plates which Ii represented. Fortunately
an )tner plate from the group can be tested
and II 1t is proved to be up to the standard
II WIN be accepted. III the plate selected for
a test proves to be below standard the
contractor may put up second plate. and
II this stands the test the government may
can for third plate to be tested. Even
though the projectiles do not do more tFan
Gent the surface of plate. IT cannot be
USED as part Of the armor of one Of our
ships. Its only Is as a target for pro-
JectiieS which are to be tested They do
not look very costly, these projectilSs but
one OF them which reached about to my
waist, with which Mr. Mason mad smashe1
a healthy steel plate to small fragments a
rev DAYS before, was valued at $3.50: and
ever time one of these probe ctilas is pu,
70 test Ii Is spoiled. 1t IL pro5a Die that
Mr. Mason can destroy more government
property in five minutes than ordinary
wear and tear would injure in as many
years.
The'work Of testing guns and ,,rojectiles
ana powders and armor plates goes on the
year round. This little community at In
dian Head has its own machine shops Its
engines, boilers. powder magazines loading
rooms. and. In fact. all OF the paraphernalia
Tor Carrying on its business expeditiously
aad effectively. Ii IL one of the most c, etly
ana one OF the most useful bureaus Of the
Navy Department
GEORGE GRANTHAM Balm.