Are we in danger of reverting to a “second childhood” when we study the
action of spinning tops? By no means, for we can learn much of great
scientific value in consequence, and even throw light upon certain
astronomical phenomena by an analysis of their motion.
Spinning bodies behave in a very different manner than the same bodies
do at rest. For example, you can loop a chain over a wheel, which
is then revolved with considerable rapidity. If, now, the chain is
suddenly disengaged, it will go running off like a solid hoop, and will
only collapse in an inert mass when it comes to relative rest.
If you throw a coin into the air it will come down “anyway.” But if
you give it a rapid spinning motion when throwing it upwards, it will
always come down with the same side upwards as when it started. (For
example, if “heads” is on top when thrown, it will invariably come down
“heads.”)
The same thing is true of a hat, an ink bottle, or any other object.
Another curious thing is that a spinning body, such as a top, can
maintain its balance at an angle, seemingly against the pull of
gravity, when the same body would at once fall to the floor when at
rest.
A gyroscopic top is a good example of this: it will lean far over to
the side, but it will not fall. Its spinning motion holds it in place.
If our earth were to stop its spinning motion, it would fall into the
sun at once, and we should all be burned alive.
When a top is spinning, it begins to “wobble,” and these oscillations
gradually increase until the top falls to the ground. If, when the top
is still, you hit it a smart blow in a north-and-south direction, it
will at once begin to “wobble” in an east-and-west direction. And vice
versa.
All spinning bodies tend to rise up onto their longest axis. Thus, if
you spin an egg rapidly, it will get up on end, and only settle back
onto its side as it slows down in its speed.
Again, all spinning bodies tend to point to the Pole Star. That is why
the North Pole of our earth is pointed in that direction. Every top,
every wheel of every factory, and on every train and automobile in the
country, when in revolution, is gently tugging to turn its axis to
point toward the Pole Star. This is a remarkable and little known fact.
Of course, the energy of the spinning body may not be sufficiently
strong to effect this, but the effort of the spinning body is there
nevertheless, and, if allowed to spin long enough and given free play,
will be found ultimately to point in that direction.
An electrically driven gyroscope will prove this. In fact, there is a
very interesting experiment, based upon this fact, by means of which
the revolution of the earth on its axis may be seen going on before the
eyes of the spectator, even if he is in a dark dungeon in the bowels of
the earth!