The herald., 1898-06-26
THE MISSING OF A BIG FORT
~ The Difficulties Of Long Range Gunnery

damage done by the fire OF our heavy gun!
At the Spanish forts The number of thos,
who think it easy to hit fort at five miles
with gun whose extreme range is tel
miles is amazing. But one who has hat
much experience with rifles at long-rang'
shooting at game will express more sur
prise that anything but large city shoult
be touched at all at any such distance. !
mere knowledge of the laws of projectile:
IL far from being enough to enable one tc
overcome the 'dificulty. The best nava
ofhcers are probably far from being experts
In long-distance work, because, with Tho
great expense of firing big guns and the
limited number of times they can be used
1t is Impossible for them to have the prac-
tice necessary to overcome such of the
difficulties as can be partly overcome. Upon
these are other difficulties that can never
be surmounted. and approximation is the
best one can expect.
The ofd-time stories of driving nail heads
snuffing candles at 100 yards, and boring
out squirrels eyes as matter of course
still go the rounds Of the great American
educator--"boiler plate"-just as II the las.
twenty-five years of American rifle shoot
fng at measured distances. with the best of
rifles cleaned every shot, with dead rest
and telescope sights, wind flags and gauges
and everything conducive to perfection,
had left no records in the numerous
matches. II the old rifles. with their lin
tied range, could do such wonders,
doubling the range doubles the capacity,
and when, with great cannon, this is ex-
tended from one mile to ten. the same ex-
tension Of hitting power results, of course.
This is the way most of those who have
never tried rifle reason, and our streets
are full of people who confidently expected
that our ships would drop shells into any
part of a fort they pleased at several miles.
An Uncertain Game
There seems no reliable information
about the accuracy of our best cannon,
even at short range. What they could he
made to do with excessive care in boring
and loading, such as is necessary in rifles
that make the fine records at matches, is
one thing. Whether they are so made and
handled do not know, nor would give a
snap for any account of the shooting with
out chance to cross-examine on the con-
ditions and results. Assuming them, how
ever, as accurate as the best of our rifles,
difficulties at once arise that make all long
distance shooting very uncertain. And their
number Is quite surprising to one who has
never had to deal with them.
The worst of them all is the rapid fall of
the projectile from the line on which it left
the gun-a fall constantly increasing.
Every one knows of this fall, theoretically.
But few know practically what it means.
This fall is exactly the same as If the ball
were dropped from a table. Firing 1t from
the table on horizontal line has no effect
on the law of gravity. Increasing the pow
der or velocity in any way merely increases
the distance at which it will strike the same
level as the ball dropped from the table.
Both will strike at the same time. This fall
Is sixteen feet in the first second. If a ball
be fired on level sixteen feet above water,
cutting string which let's fall another ball
suspended there, both will touch water at
the same instant though the one fired from
the gun may do it 1900 feet away. This is
not generally believed, but careful expert
ments long since put it beyond question.
This law cannot be circumvented by rails
ing the muzzle of the gun. The horizontal
line from the table representing the line of
fire may be raised to an angle of As degrees.
but the fall from that line Is just the same
You have merely increased the time within
whichit must strike the ground. and have so
increased the distance at which it will
strike. But 1t Is falling at the same rate as
If fired from level,
This rate increases In the ratio of the odd
cumbersome, three, five, seven. and so on.
Thus the fall for the second second is three
times that of the fall for the first second
three times sixteen. or forty-eight, and the
whole distance fallen in the two seconds is
about sixty-four feet At the end of each
second the velocity has increased about
thirty-two feet a second, which is carrying
1t through the next second at much faster
pace. being added to the velocity due that
second. ,,..-...-s. ..s
Suppose now that one of our big guns had
a muzzle velocity of 1000 feet second and
that it holds this throughout its flight,
which latter is far from being the case. on
account of the retardation by the air which
is far greater than any would suppose. To
travel four miles at 1000 feet second would
take about ten seconds. You must now null
tlpy sixteen, the fall for the first second.
by nineteen. the tenth number in the series
of ]. g. s. ETC.. of the odd numbers. This
gives. in round numbers, which am using
all through, 300 feet fall for the tenth sec
ond. The total fall for the whole ten sec
onds may be found by adding all the falld
for each Of the seconds, and is about 1900
feet.
Some Difficulties
Assuming the starting velocity of 2000
feet a second continued at four miles. we
nCw have the ball falling 300 feet in each 200O
feet. thirty feet in each 200, or enough 20
miss the body of a respectable ship. Will
any range finders work to within 200 feet at
four niles? The refraction and alteration
of Hight alone make it nearly impossible
But SUPPOSE they could, how long could a
ship rely on 1t when moving with wind and
tide and ocean currents as well as her own
power necessary to maintain steerage way?
Bat at four miles this difficulty is about
double, as 1t is not probable that any gun
we have can maintain a velocity of much
over 1000 feet second during the fourth
mile. No matter how high the velocity at
Z which It is started the longest bodied.
sharpest pointed ball of lead has it's velocity
greatly reduced at the end of 1000 yards.
The highest explosive known could not
throw ball of cork from our largest gun
half mile. If long bodied balls of lead
4 lose velocity so fast under the resistance of
the air, which increases as the squares of
Z the velocity. balls of iron, shorter, too. in
proportion to diameter, will lose much fast
Z er. And it will be still worse when made
hollow to carry an explosive which weighs
H little compared with iron. And shells, to be
destructive. must have a large cavity and
thus be very light compared with their d.
ameter.a This would make them lose We
- UUp ia No Itch Iii