The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1889-01-23
THE BIG PNEUMATIC GUN.
Very Popular Now and Lots of New
Vessels Applying for IL.
New York SUM-

NEW 1Ork sun.
The Government has now invested enough
money in the system of firing dynamite shells
by means of expansivesforce of compressed
air, to feel much interest in the results of
Saturdays trial at Fort Lafayette. 1t has
made, to begin with, an appropriation of
100000 for these compressed air guns, to
be mounted in these forts ON land, as they
can safely throw huge bursting charges of
dynamite where gunpowder cannot. 1t has
also invested $35O,oOO In the Vesuvius, built
expressly to use such guns. 1t has provided
for coast defence vessel, to cost probably
S1.750.00O, and in the pending Navy bill it
will have submerged monitor TO cost ST.
100000, exclusive Of armament in each Of
which big dynamite thrower forms part of
the main battery. This same navy bill in
cludes an appropriation for another vessel Of
the Vesuvius type, to cost $450,0O0, using, of
course pneumatic guns, and several other
bills have been introduced which contemp-
late their use in harbor or cruising vessels.
In short, the pneumatic guns are already so
popular as to appear even in the plans of
vessels where Ghey seem to have no specially
appropriate place.
Accordingly it became desirable to know
exactly what can be expected of these
weapons. Saturdays experiment with the
15-inch pneumatic gun mounted at the Mar
lows in New York harbor showed that a
projectile containing over 800 pounds of
nitro-glycerine and 200 pounds of dynamite,
making an aggregate of over 500 pounds of
high explosives, can be safely discharged by
the use Of compressed air as the propelling
not been seriously questioned. The success
OF previous experiments with the pneumatic
apparatus had indicated that this enormous
bursting charge could be just as safely fired
as small one, since the steady and slowly
acting force of compressed air substituted
for the sudden shock of gunpowder acts in
tube of fifteen inches diameter precisely as
in one of eight inches. STILL since up to Sat-
urday no official experiment had been made
with a greater bursting charge than 100
pounds of the high explosives, the successful
discharge of 500 pounds is remarkable oc-
currance. The design for the Vesuvius re-
qUires that her three 15-inch guns should
throw projectiles containing 600 pounds each.
They are TO be little longer than the tube
used N Saturdays experiment 1t is fair
to inter that In the system OF throwing dyna-
mite projectiles originally invented by Mr..
Mefford. and improved by various persons
since. any required weight of dynamite can
be discharged with safety.
But there are other elements of effective
ness required by the contract with the Vesu-
vius, namely. range of mile, rapidity of
one shot In every two minutes, and a speei-
fed accuracy of fire. AS to the first Satur-
days firing showed that this can be secured,
since although the second shot fell nearly
One-hfth short of the mile, the first, with
preliminary bursting charge of only 200
pounds, had gone seventh of mile beyond,
and at the second short the air valves had
been disabled. As to the stipulated rapidty
of fire, 1t has been achieved in practice with
sand instead of dynamite proiectiles from
the shore guns, and little apprehension is
felt on that score. As to accuracy, the test
completely broke down yesterday through
leakage tn the air valve. combined perhaps
with the breaking of fiange on the rear
shaft that guides the projectile.. The latter,
IN fact tumbed over and over before it fell
into the water short Of the mark and there
exploded. At the next trial these defects
may be remedied. and then the question of
accuracy, practically the only one remaining
to be settled, will the determined.
But as to the use Of the dynamite guns in
land defences, there is already little doubt.
They will be of avail not only against land
attacks but also in preventing hostile fleets
from approaching within mile or mile and
half, TO deliver their fire. And although,
OF course, war vessels have effective ranges
three or four times as great as that, still, for
the projection Of channels and for coopera-
tive defence the pneumatic guns can be USE
ful. How 1t VIII be with these guns a1oat is
not quite as clear, because they are fixed in
the vessel, and can only throw their missels
effectively when the bow heads directly for
the target while their accuracy is further
impeded by the ships motion. Still, the
modern custom of using electricity to fire
heayy guns will help to counteract the draw
back of the ships motion with the pDeumat-
lc tubes, as with guns in general. The pres
ent series of experiments will show what can
be done with 15-inch pneumatic guns on land
and then the firing Of even one of Them. ac-
tually mounted on the Vesuvius, will show
what they can do on the water. When this
last 10 once accomplished, If the results are
satisfactory, Congress can go ahead without
hesitation to authorize other vessels in which
such guns are used.