The applet offers an interactive version of Benham's top, or Benham's disk, named after the English toymaker Charles Benham, who, in 1895, marketed a top with the pattern the applet attempts to mimic. When the disk is spun sufficiently fast the line arcs blend into colorful circles. The effect was actually reported in 1838 by G. T. Fechner after whom the colors are named, Fechner colors. The distribution of colors depends on the way in which the arcs are combined.