The Jennings daily record., 1902-05-26

The bicycle loop presents d most
Interesting demonstration OF a great
scientific principle. which plays its
part in preventing the earth from
dropping into the sun. and the moon
from being precipitared upon the
earth no less than in keeping the
rider and his wheel from falling TO
the ground when he hangs, head
downward, in midair, at the top OF
the loop.
Centrifugal force is the agent con-
cerued i'll this seemingly miraculous
feat. force that has many appliances
in everyday life. some OF which-like
the swinging OF a bucketful of water
around the head without spiilins-
astonish the uninitiated, while others
are SO familiar that nobody stops to
think OF them. But when applied in
the case now under consideration,
centrifugal force presents itself in
most sensational form.
Yet. thrilling though it is TO watch
the bold rider defying gravitation
like a fly on the ceiling. without any
thing except his motion to hold him
in place. the natural law that he
obeyS is extremely simple and per
fectly certain in its operation Ii he
observes all the requirements OF that
law it will never fail him. so that
his safety depends entirely upon him
self.
He must develop a centrifugal force
great enough to cOuuterbalance his
weight when he is at the top Of the
circle. Mathematics, knowing the
size OF the loop. is able to tell him
how to develop the force needed. The
force depends upon the velocity with
which he moves. Ee acquires that
velocity. not by pedaliug. but by rid
ing down steep slope. How high
must the starting point be? A gen
eral rule applying to all such cases.
is that the elevation OF the point from
which he starts must be to the eieva-
ton of the top of the loop in a ratio
| exceeding that Of five to four.
The air resistance and the friction
| must all be carefully allowed for.
and this is the business OF the engln-
| eer who plans the apparatus Accord
| irgly. If the loop is twenty feet high,
! the starting platform must be more
| than twenty-five feet in height. and
| the acquired velocity must exceed
| that named above OF course. the loop
! may be less than twenty feet IN height
ana then all the other dimensions
will be proportionately reduced.
It is probable that. in the actual
case considered the velocity with
which the rider arrives at the bottom
Of the slope and begins the ascent oi
The circular loop Is at least thirty
miles an hour This velocity immedi.
ately and rapidly falls of as he COM
!ucnces the ascent OF the steepenins
curve so that when he reaches tn
Top he is moving only fast enough II
impart d centrifugal force eXceedin:
his weight ,or the effect Of sravita
,ion) ~ margin sufficiently large Il
insure his safety.
As the bicycle strikes the curve O
the loop and begins 10 ascend, tn
wheels are pressed against the trac
with tremendous force and the ride
is pitching forward with an energ
which only practice and trained mus
ces can enable him to withstand.
Is as II the weight OF half a dozen me
| had suddenly been thrown upon hil
| and his machine Il we estimate iii
actual weight OF bicycle and rider :
200 pounds then it can be shown thu
their combined weight. or rather the
pressure upon the track, owing to ceI
trifugal force. becomes, as they begi
the ascent OF the loop. more than
thousand pounds: And this, too
the minimum speed theoretically y
CURED to carry them around. In pra
,ice this pressure may be considerab
greater
Here. then. would seem to be a poll
of special danger. The rider must
prepared for this instantaneous i
crease of virtual weight. He has
Of keep his nerves steady and his he;