The Bamberg herald. [volume] (Bamberg, S.C.) 1891-1972, 1916-03-02

with field carriages on bad ground,
and in the case of naval mountlngs
varies not only with the same mount
ing in different parts of the ship, but
also when the gun is trained on dlt-
ferent bearings. MountingS carried
on a pedestal with ball race OF
small diameter, particularly If they
are balanced mountings, are extreme
~ unstable, the jump varying be-
tween positive and negative limits OF
as much as half degree. Errors OF
elevation with those mountings are
also caused by the movements of the
gun members on the platform and Dy
the fitting of the mounting by the
thrust at the elevation arc. with
hydro-pneumatic mountings the re-
coil and angle of departure are great
ly affected by the mere rate OF lire,
the frothing of the liquid and the lib
Grafton of air being dependent on
the time interval of rest between the
rounds.
Dials-The dials are graduated
from a calculated range that has been
correlated to the shooting of one or
more guns of the particular nature.
Any individual gun, however, may
range consistely short or over, due to
some pecularity not possible to de-
fine.
Instruments-Th are consider
able number of instrumental errors
which arise mainly from imperfect
adjustment, such as telescopes out OF
climation, displacement of the zero
reading of dials, range finders out
of level or incorrectly datumed, tide
cages incorrectly set, etc., that give a
permanently loaded error to the
shooting of the gun.
Droop-This is caused by the heat
strains of unequal cooling during
manufacture or by a lack of glrder
Stiffness. In both cases percept1Dle
notifications of the droop are
brought about during firing or by
the heating effect of mere sunshine.
Cases have been met where the bend
of field guns is beyond the condemn
ing limit when measured in the gun
park, but four or five minutes less
after the guns had been heated by
exposure to tropical heat for three
hours.
Choke and Metallic Fouling-
effect of choke and metallic fouling
is not only to increase bore resist
ance and thus cause variable muzzle
velocities, but also to make one gun
differ from another of the same ma
ture at the same period of its life.
The effect depends on, whether the
choke or coppering occurs in such a
position that the fate of burning Of
the charge is affected by lowering
the normal rate Of explosion of the
bore gases. Heavy guns, which cop
per rapidly, may lose as much as
fifty yards per round at 5000 yards.
Driving Band-When projectiles
are fired for recovery their driving
bands are found to be famed, &C.
centric, worn smooth or multiply
engraved. This irregular action
implies variable engraving and
refling resistance, and, in con-
sequence, variable muzzle velocl-
ty. In addition, with long shell, or
with a gun eroded at the commence
ment of the. rifling oblique loading
results, and heavy groove marking
on the body of the she'll itself.
Wear and Windage-Wear at the
commencement of the rifling gives
rise to over-ramming and to an en-
craving resistance less than that nor
NAL for a new gun. Heavy guns
have a rapid rate of wear and rapid
rate of fall of muZzle velocity
for about the first eighty sounds OF
their life, feature that is not ex-
hibited by guns below about 81 inches
calibre, these latter having a greatly
diminishing rate of fall of muzzle
velocity through their life. General
wear of the bore gives rise to gas
escape, fusing the driving band, lr-
regular rotation and fall of muzzle
velocity.
Wet Chamber-This is fruitful
cause of lack of agreement between
performance and intention. When
charges are burning in a gun the
principal mode of heat lot to the
wall is by radiation. The magnitude
of this heat loss is not generally ap-
preciated, although it is of the order
of 10 per cent. of the total heat of
oono huction The most imDOrtant