Spinning top

They may be set in motion by twirling a handle with the fingers, by pulling a rope coiled around the body, or through a built-in auger (spiral plunger).

By rapidly spinning the top, Forbes created the illusion of a single color that was a mixture of the primaries:[4][The] experiments of Professor J. D. Forbes, which I witnessed in 1849… [established] that blue and yellow do not make green, but a pinkish tint, when neither prevails in the combination…[and the] result of mixing yellow and blue was, I believe, not previously known.Maxwell took this a step further by using a circular scale around the rim with which to measure the ratios of the primaries, choosing vermilion, emerald, and ultramarine.

A typical fist-sized model, traditionally made of wood with a blunt iron tip, is meant to be set in motion by briskly pulling a string or rope tightly coiled around the body.

The rope is best wound starting near the tip and progressing up along the widening body, so that the tension of the string will remain roughly constant while the top's angular speed increases.

In these models, the actual top may be enclosed in a hollow metal shell, with the same axis but decoupled from it; so that the toy may appear to be stationary but "magically" balanced on its tip.

[6] Modern tops have several sophisticated improvements, such as ball bearings of ruby or a hard ceramic like tungsten carbide, that reduces the friction with the ground surface.

Typically the top will at first wobble until friction and torque between the tip and the underlying surface force it to spin with the axis steady and upright.

[8] After spinning upright (in the so-called "sleep" position) for an extended period, the angular momentum will gradually lessen (mainly due to friction), leading to ever increasing precession, finally causing the top to topple and roll some distance on its side.

[11] The Jean Shepherd story "Scut Farkas and the Murderous Mariah" revolves around top-spinning in the fictional Depression-era American city of Hohman, Indiana.

The top is a focal element and metaphysical symbol in the movie Inception (2010), directed by Christopher Nolan and starring Leonardo DiCaprio.