River Falls journal. [volume] (River Falls, Pierce County, Wis.) 1872-2019, 1880-01-15
VELOCITY OF A RIFLE BULLET.
Professor Spices Experiments at Cooper
Union.
New York Tribune

Prof. Robert Spice, the Brooklyn
chemist and physicist, appeared last
evening at the Cooper institute, in lee
ture on projectiles. The great hail was
crowded in every part-many standing
in the aisles. When the well-known
face of Mr.. Cooper appeared, the au-
dience, as usual, gave him very hear
ty welcome, and the applause was re-
newed when. on the introduction of
Prof. Raymond, the lecturer came for
ward.
The task which Prof. Spice was to ac-
complish was to determine the actual
velocity of q rifle bullet fred across the
platform was 80 feet, which, the lectur-
er explained, was shorter than usual,
as the ordinary distance used in deter
mining this question was about 200 feet.
To carry this performance out he had
secured the cooperation of Lieut.. Il. l..
Merriam, of the Brooklyn 18th regi-
ment, who has gained some reputation
at the Creedmoor range, as evidenced
by the medals which he wore. In the
first place, Prof. Spice explained the APP
paratus to be used. He called the at
tention of the audience 10 mahogany
base II inches by 10 inches, on which
were placed two levers which carried
bent wires TO make marks on q piece of
smoked glass underneath the points,
One of these wires was connected with
a pendulum attached to an Atwood
machine, vibrating seconds. BY M cans
of electric currents, the lever connected
with the pendulum came down on the
glass precisely at the beginning of each
second, making a series of lines sepa-
rated by spaces somewhat similar to the
old Morse alphabet Consequently the
distance from the beginning of one line
to the beginning of the next, represented
Il second of time.
The second lever, exactly opposite,
had spring attached to one end, which
kept the point off the glass. 1t also had
two electro magnets, one at each end,
which had electric currents passing
through, of different strength--tf g
weaker current tending to pull the lev
er down on the glass; the stronger cur
rent tending to keep it elevated In
addition to this, the current from the
stronger magnet passed through loose
wire resting on two globules of mercu-
ry, and Immediately in frontof this wire
was to rest the muzzle of the rifle. The
weaker current passed through pre-
cisely similar loose wire, also placed on
two globules of mercury, which. wire was
placed thirty-two feet distant from the
first wire.
Lieut.. Merriam now came forward,
and loaded the rifle. 1t was n regular
Creedmoor, As calibre, 34-inch barrel,
and placed in it cartridge containing
a 450-grain ball, and 40 grains of pow
der, explaining that this was not a full
charge. He then took his position.
The object was 10 shoot away the wires
on the mercury. A box of sand was
placed to receive the ball.
The pendulum above described was
then set in motion. On its striking the
fifth second the plate of smoked glass
was drawn along by the descent of a
weight on the top of a column of sand
which run out of tube. On the sixth
second, Lieut.. Merriam pulled the trig-
ger and both wires vanished. On the
| first wire being broken, the point of the
CORES ponding lever descended on the
glass, but Immediately rose again by the
action of spring, when the bullet broke
the second wire. The consequence
this was that the point connected Will
| this lever scraped very short line OF
the smoked glass, while the other poin
| being kept down during the swing
the pendulum, scraped a longer space
Then the glass was withdrawn and
placed in the stcreoptican, projecting a
magnified image of the lines on the
screen. The relative lengths of these
| lines were ascertained, thus obvlating
| any source of error in measuring
| the minute lines ON the smoked
glass. This method of measuring the
lengths was claimed to be original by
| the professor.
| On this measurement it was found
that the shorter line was 5 inches long,
and the other line feet and two inches.
These numbers were brought down to
| the common fraction of inches, the re-
suit giving no inches for the longer
! space. 1t was then ascertained how
many times the former was contained
in the latter, and the fraction thus OBJ
| tanned was clearly the fraction of o sec
ton that the bullet took to pass from
one wire to another-thst is, 1-22 of a
second. Multiplying the distance be-
tween the two wires (33 feet), as above,
by the denominator of the above frac-
ton, the velocity of the bullet in fest
was obtained, namely, 726 feet in sec
ond.
The result was long applauded; and
the lecturer, to make things sure, de-
termined to repeat the experiment.
The second attempt was equally sue
cessful. Prof. Spice then proceeded to
give illustration Of experiments of the
well-known magicians, showing how
science and art are resorted to to de-
ceive the senses. His performances
and explanations were of great interest
to his hearers.
An Cid Maids Advice.