A child's motion or a parent's touch can impart such mechanical bouncing motion.Instead of, or in conjunction with, the linkage assembly of FIGS. 1-3 or the motor 144 and spring 148 arrangement shown in FIG. 4, various mechanisms, cam surfaces, linkages, dampers, springs, or other mechanical arrangements can be employedwithin the disclosed devices 20 or 120 to impart the vertical bounce movement