The representative., 1898-05-04
STUDY OF MECHANICAL MOTION.
The Cinema tOgr raph Put to Move
Use in France.

Use in France.
The cnemato3raph mas been put to an
exceedingly ingenious application in France
of the study of problems in mechanics and
physics of the kind that they SO much de-
light In, and in the solution of which the
French 50 greatly excel. M. Fremont, of
the French Society of Civil Engineers re
Gently used the Instrument to demonstrate
the useless expenditure of force in the sys-
tenn of hand riveting which prevails there.
and which has long since been abandoned
IN this country as wasteful and eXtraVa-
CANT According to London Engineering.
the rivet hammers used weighed between
3.3 pounds and 81 pounds, each, or A
pounds with handle included. Completing
the head was done with hammers weighing
?.9 pounds to II pounds each, these being
used either swung or 'rased.' The
photographs showed that on the rise the
hammer moves slowly, Dut rapidly increases
in speed on its descent Using the heavy
hammers without swinging" them Il good
striker makes Il blows in 10 seconds, and
does in this time 3,3S6 foot-pounds of work,
or lo9 foot-pounds per second. This rate
cannot. however, be maintained, and if the
periods cf rest few and short. as in
horseshoe making, the rate Of work falls
to los or 115 foot-pounds per second.
On the other hand, an exceptionally good
man can for a short period work at the
rate of 202 foOt-poundS per second. When in
place of the hammer having a movement
OF quadrant only, it is swung the full
circle fewer blows are struck per minute,
but the work done by each blow is greater.
Thus with 154 pound hammer about nine
blows could be struck il l. seconds, each
or which would accomplish 231 foot-pounds
OF work; but the rate of working falls to
1874 foot-pOunds per second. Striking a
side instead of d down blow. an ordinary
man not specially accustomed to such work
blows seconds w,
sedge each of which is equivalent to from
14o to 1o9 foOt-pOunds. and the rate of work
is 123 foOt-pOundS per second. With riv-
eters accustomed to strike in this fashion
about 10 per cent better results are OBJ
tained. Usually, however. they use liz =
er sledGe weighing about 10 pounds, and
with this can strike I3 to II blows in Is
seconds, doing los fOOt-pOunds per second.
Swinging the Sledge, the number of blows
falls to 10 in Is seconds but the rate OF
work is unatered owing to the blows be-
ing heavier.
While the almost complete abandonment
of hand riveting in this country detracts
from the value of this particular investiga-
ton to our mechanics, the principle here
employed is, no doubt. applica BILE to the So
luton of many important problems. such as
the hammer blow of locomotive on the
rails when travelling at d different rate of
speed.
The analysis of motion is exceedingly
difficult when the object is moving a a high
rate of speed The first instantaneous pho
tograph of horses in motion appeared to be
grotesquely distorted No one ever believed
that horses ever placed their legs and
bodies in such ridiculous positions, simply
because no one had ever before caught lex
cept by a flash of lightning) an instantan-
eouS glimpse of an animal in motion. Our
ideas on this subject were entirely false
and these photographs of moving horses
made at the University Of Pennsylvania
shown to Meissonler. the great French
horse painter, about 15 years ago, caused
him, it is said, to weep over his mistakes
1t is not at all impossible that the applica
ton of the c;nematograph in the manner
described by NJ. Fremont may become q
recognized and highly valuable method OF
testing the accuracy of motion of ma
chnery and may be the means Of detecting
a want of per counterbalancing in large fly
wheels, which is always a source of more
or less danger. Almost every engine OF
machine is designed to move at certain
rates of speed. sometimes uniform, some
times variable and the only means of de
tecting whether the moving parts are out
of balance or "out of truth is the Vibration
caused thereby. If this is not sufficient tC
factory, but it is far from being accurate
therefore accidents are liable to occur from
Observation-Disclosures.