754
��Popular Science Monthly
���Fig. 2. A mother top and her brood
����Fig. 3. A ball
which spins or
rolls on a wire
����Fig. 4. A top which climbs its string
���Fig. 5. A colored wind- mill top spun by air
��Mechanical Tops
SPINNING-TOPS, like toy soldiers and other necessities of boyhood, have existed for many years. Re- cently, the old standby made from a spool with a peg pushed through the center, has succumbed to more scientific devices. The principle of the gyroscope is frequently used. The little ballet dancer. Fig. i, can spin on her foot, her arm or her head, because of the gyro- scope mechanism which is concealed in- side it.
A toy which resembles an old hen and her brood of chickens, consists of one large top having several lateral cavities with small tops mounted in them, Fig. 2. When the big top is spun, a disk at- tached to its shaft rotates also, and the outside of this disk, touching each of the small tops, causes them to spin.
Jugglers and acrobats have a ball which will balance on a wire, resist all efforts to roll it, or roll in only one direction. Fig. 3. The gyroscope prin- ciple is involved in this toy.
Another top for balancing on a wire has an egg-shaped case with a removable cap. Fig. 4. The mechanism, enclosed within this case, spins in a tiny depres- sion. The case is mounted on a minia- ture truck of two wheels.
The principle that a whirling body tends to rotate about its shortest axis is demonstrated in a toy consisting pri- marily of a blow-mill encased in a circular tin box. Fig. 5. Attached to the axis of the fan is a long cord ter- minating in a hook. When the fan is ro- tated, the cord becomes rapidly twisted. A ring suspended from the hook will rotate in a horizontal position.
Variations from the simple ring may be used, one being a ring having a con- centric disk of primary colors. Rapid rotation tends to resolve the colors into white. The opposite phenomenon may be illustrated by means of irregular pieces of white cardboard with holes punched in them; they tend to break up white light into colors.
One of the newest ideas in toys is a real musical top. Fig. 6. A hollow cone has a vertical shaft projecting beyond the upper rim and having a central hole in which a nail may be inserted for
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