The San Francisco call., 1897-05-30
NOv|CES MADE
GOOD TARGE IS
Heavy Batteries of the
Third Artillery in
Practice.
" Indirect Aiming" by M cans of
the Range.Finder Great
Success.
New Mechanical Apparatus for
Making Corrections for Wind,
Velocity, E.c.

The eight heavy batteries of the Third
Artillery stationed at Angel Island, Alca-
traz, Fort Mason and the Presidio COM
pleted their annual target practice With
the heavy rifled armament at the Presidio
on Friday. Each battery fired three
rounds from the Pinch breech- loading
ritled mortar and three rounds from the
Finch breech-loading steel rifles. None
OF the batteries had ever fired these guns
before, but for all that the targets made
were exceptionally good.
In the mortars an 800. pound shell was
fred at ranges of 7200 and 5000 yards.
For the former 70 pounds of brown prls-
matte powder was used and for the short
range 45A pounds. For these ranges the
m ortar is given an elevation between fifty
and sixty degrees and the shot takes
nearly minute IN its flight through the
air. With the 10 pound charge the she'll
starts with a velocity of nearly 1000 feet
a second and strikes with velocity of
about 100 feet less. but still quite sufficient
to penetrate the decks and lotion of any
ship afoat. Grouped in batteries of six
teen and having range OF six miles
these mortars will prove most formidable
weapons.
The firing is done by electricity, but the
most interesting part is the aiming. AS
the target is not in sight, what is called
indirect aiming" is resorted to- Observers
were stationed at Points Bonita and
Lobos, provided with an accurate instru-
mept for measuring horizontal angles,
something like large theodolite. These
angles were sent by telephone TO the GEN.
traI station at the mortar battery. These
angles were then plated on large chart
of the harbor, thus locating the exact
position of the target From this same
chart were taken the distance to the target.
and the exact angle at which the mortar
mus: be set to point toward the target.
By means of carefully computed range
tables, the elevation for the particular
range and initial velocity is then taken
out and the gun set.
At these long ranges, owing to the ro-
tation of the shot in the air and the Ion &
time OF its fight, the proiectile sweryes to
the right. If pointed direct at target
1000 yards away the .proiectile would
strike at point something over 400 y ard s
lowance for this drift must be carefully
CO imputed and applied in setting.
In similar way the point where the
shot strikes is plated and by measure
ments its exact deviation. right and left,
over and short. of the target becomes
known. From these data the proper cor
rections are made in the next shot.
The assumed target for the mortars is
an imaginary rectangle on the water, 100
yards by % yards, representing the deck
OF ship. The bits are given differen
values, according TO their position in
this rectangle.
For the 12-inch rifle the range was 6775
yards and two sized charges were used,
the larger of 800 pounds brown prismatic
powder made by the California Powder
Works. The projectils weighs 1000 pounds
and starts with the high velocity of 1925
feet q second. A 1000 yards this shot
would penetrate about twenty inches
OF steel. Owing TO the slow burning
nature of the powder used in al! heavy
guns the shock of discharge is much less
severe than in many field pieces usin g
quick-burning powder. No inconvenience
was suffered by standing quite close to
the gun during discharge.
The target was spar buoy located te-
yond the outer heads. The general
method of locating the target and plat
ting the shots was the same as in the NOR
tar firing, as at that range the target is
indistine uishable; but in addition use
was made Of the Lewis range-inder and