The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1899-01-14
DIR. GATLING's BIG GUN.
Overwhelming of the Breech Ex-
plains the Bursting.

Richard ]. Calling. in New YORK Sun.
In your paper of the 9th and other of the
city's papers articles appeared relating to
the trials of the eight-inch Calling gun.
trust a brief statement coming from me as
the inventor in regard to the method of con-
strucdng the gun and the reason why the
gun was ruptured at the fifteenth round
may be of interest to your readers and the
general public. Every possible care was
taken to have the gun made of the best ma
terial, including the alloys used, and it
seemed after the gun was taken from the
mold that a perfect casting had been pro-
duced. The gun was then roughly bored
after which it was placed in an annealing
furnace preparatory to the mandreling, at
which process desired the members of the
ordnance board to be present.
A day was set by the board for such
mandreling to take place, which was the
18th of last March, and the board was to
be present. The heating up Of the gun was
commenced a few days previous to the
above date, and after the gun had become
redhot 1 received telegram from mem
press of business, the country being then
on the eve of war with Spain, it was re-
quested that the nandreling process be
postponed from the 18th until the 18th of
March.
The question then arose whether the gun
should be allowed 10 cool Off or be Kept
heated up in the furnace until the arrival OF
the board. l conferred with M. B9rtol, the
general manager of the Otis steel company,
and he thought it would be better to Keep
the gun still heated in the furnace than TO
allow it to cool off and then nave TO reheat
it, This delay was most unfortunate, for
the gun having to remain so long Cnearly
eight days and nights in the heated fur
mace became overannealed which greatly
injured the quality of the steel
The annealing furnace was so constructed
as to allow all parts of the gum to be heat
ed except about three feet of the muzzle
end, which extended outside o. furnace,
and this was done because the It end of
the gun was not to be mandI Some
two days before the mandreline as to take
place | requested Mr.. BartOl to have the
frO1 trnl nf = - 4 n
take in the entire gun, that we might get
the entire metal of the gun of an even tenn
peTature before the cooling process COM
menced, which latter was done by forcing
current of cold air through the bore of
the gun
/ wish the reader to bear in mind that the
metal in the muZzle of the gun was kept
heated for about two days only while, as
previously stated, the breech and main body
of the gun was kept heated for nearly eight
days and nights. All the metal that en-
tered into the gun was made in one furnace
and was of the same quality Of steel.
The test of the strength of the steel in
cast form before ii was put in the anneal-
ing furnace, samples OF which were taken
from both the breech and the muZZle
showed equal strength, which averaged
tensile strength of little over 100000 pounds
to the square inch.
inspector. after the gun had been man
dreled, cooled and taken from the anneal-
ing furnace. ordered that two sample pieces
should be taken from both the muzZle and
breech end Of the gun and tested. The sam
pies taken from the muzzle gave a tensile
strength of about $1,000 pounds 10 the square
inch. while the samples from the breech end
to my surprise gave less than 60.O00 pounds
to the square inch. Such being the case
firmly believe that this variation in the
strength Of the metal was caused by the
over and prolonged heating of the breech.
II is we'll known by expert steel men that,
when steel is overannealed. il loses in
great degree its strength and elasticity, and
science has not been able to restore strength
to oVerannealed steel.
These tests were made by the government
inspector. and his report of such test will
verify my statement in the case. A copy OF
the test was also kept by the Otis Steel
Company. and all have said In relation to
the breech and main body of the gun having
to remain so long in the furnace is well
known To Manager Bartol and all the Off
Gals of the Otis Steel Company.
Had ii not been for the unfortunate de-