holds it to the center may be elastic, and in that case, if the
centrifugal force is sufficient, the body will be drawn from the center,
stretching the elastic bond. It may be asked if this does not show
centrifugal force to be a force tending to produce motion from the
center. This question is answered by describing the action which really
takes place. The revolving body is now imperfectly deflected. The bond
is not strong enough to compel it to leave its direct line of motion,
and so it advances a certain distance along this tangential line. This
advance brings the body into a larger circle, and by this enlargement of
the circle, assuming the rate of revolution to be maintained, its
centrifugal force is proportionately increased. The deflecting power
exerted by the elastic bond is also increased by its elongation. If this
increase of deflecting force is no greater than the increase of
centrifugal force, then the body will continue on in its direct path;
and when the limit of its elasticity is reached, the deflecting bond
will be broken. If, however, the strength of the deflecting bond is
increased by its elongation in a more rapid ratio than the centrifugal
force is increased by the enlargement of the circle, then a point will
be reached in which the centripetal force will be sufficient to compel
the body to move again in the circular path.

Sometimes the centripetal force is weak, and opportunity is afforded to
observe this action, and see its character exhibited. A common example
of weak centripetal force is the adhesion of water to the face of a
revolving grindstone. Here we see the deflecting force to become
insufficient to compel the drops of water longer to leave their direct
paths, and so these do not longer leave their direct paths, but move on
in those paths, with the velocity they have at the instant of leaving
the stone, flying off on tangential lines.