Spinning and Whipping Tops: The Stability of Rotating Bodies

摘要

The top has been known to most cultures throughout recorded history Fig. 20), for the fruits of certain trees and shrubs - e.g. acorns and pine cones - may be induced to spin upright on their bases without much difficulty. Alternatively, hard berries approaching a spherical shape may be pierced axially with a long thorn. Examples based on these symmetrical shapes are readily made freehand on any simple lathe from scraps of wood, and must have proved popular as playthings for children. However, practice enables skilful demonstrations to be exhibited by adults, and performances are still valued in Japan and South America. Some societies use polyhedral or polygonal tops - 'teetotums' - for games and prophecy.