The Saint Paul globe. (St. Paul, Minn.) 1896-1905, 1903-07-02

must retain control over his muscles in
order to hold his balance and guide his
wheel. But this is only a beginning.
AS he rises. in a moment he is going
straight upward, and e.ie pressure
swiftly diminishes. when he whirls
across the overhead portion of the
track and reaches the center of the top
OF the curve his head is down, his feet
are up and his bicycle is on top of him.
They are sustained only by centrifugal
force. Grayitation is pulling them
straight downward with a force of 200
pounds. If the centrifugal force but
slightly exceeds gravitation at this
point, the rider, if he has time to anal
we his sensations, must feel almost as
II ne were floating like feather, de-
prived of nearly all weight.
The Critical Point.
This is the critical point. If the cal
culations have been correct, there will
be enough velocity remaining when the
top is reached to counterbalance grav-
itation, and even if the excess is slight,
the rider and his wheel will pass on,
and, once over the center, they are
henceforth secure against fall. They
downward journey. Theoretically, with.
a loop twenty feet in diameter. and
neglecting resistance. they much reach
the top with a velocity of nearly six
feet a second. In practice the velocity
would have to be considerably greater.
But consider the effects upon mind
and body Of the rapid changes of APP
parent weight that the rider under
= he ~ "a hiS
apperent weight was instantaneously
increased to prodigious amount, al
most crushing him down upon the
handle bar. This lasts but moment
and then, again almost instantaneously,
his weight drops from him, and at the
top of the loop he seems to weigh COM
paratively little, but only to be sec
ond later again. bent over the handle
bar by the pushing pressure. as the
wheel. having gained momentum,
swings upon the slope leading to the
stopping place.
1t is apparent, from what has been
said, that the principal peril involved is
personal in it's origin. The rider must
not allow his head to swim, or his mus
cles to relax their control over the
wheel Given perfect self command the
danger is reduced to: minimum.
Could Loop the World.
The same force that carries the rider
around his twenty-foot' circle would
carry him, through empty space, COM
pletely around the earth, If he could
start from a mountain top with
velocity of miles, instead Of a few
yards, per second. The needed velocity
varies with the radius of the circle
traversed.
Among the familiar examples Of CEN
trifugal force may be mentioned again
the case of bucket or pail of water,
swung about the head at the end of
rope, in such a manner that the water
remains in place even when the bucket
is upside down. This experiment is
easily tried. In order to impart the
requisite velocity to the mass of water
in the pail it Is only necessary to
swing it to and fro like. pendulum,
gradually, having thus been brought
to a:level with the shoulders, it can be
Whirled over the head, in a complete
circle, the rope remaining taut all the
time.
The pair of balls on the governor of
a steam engine act on the same prin-
ciple, for an increase ofvelocity, causing
them to whirl more rapidly around the
perpendicular axis to which they are
connected. drives them further apart
by centrifugal force.
This principle is also employed in
various mills to separate light and
heavy bodies, or particles that have
become mingled together, by causing
them to revolve with circular mo-
ton, whereby the heavy particles, de-
veloping more centrifugal force on ac-
count of their superior weight, are di-
vided from the others.
1t is the centrifugal force that throws
water in showers of drops from a
swiftly rotated grindstone, and gouts
of mud from speeding wheels. Great
fywheels are occasionally burst asun-
der by the centrifugal force developed
through their too rapid revolution.