This amusing instrument consists of a turning wheel, upon which figures
are seen to walk, jump, pump water, &c. The disc or wheel should be
of stout card-board, upon which should be painted, towards the edge,
figures in eight or ten postures. Thus, if it is wished to represent
a man bowing, the first position is a man standing upright; in the
second, his body has a slight inclination; in the third, still more;
and so on, to the sixth position, where the body is most bent: the four
following, represent the figure recovering its erect posture, so that
the fifth and seventh, the fourth and eighth, the third and ninth, and
second and tenth figures, have the same posture. Between each of the
figures on the wheel, should be a slit, three-fourths of an inch long,
and one-fourth of an inch wide, in a direction parallel with the radii
of the wheel, and extending to an equal distance from the centre.
To work this instrument, place the figured side of the wheel before
a looking-glass, and cause it to revolve upon its centre; then look
through the slits or apertures, and you may observe, in the glass,
the figures bowing continually, and with a rapidity proportionate
to the rate at which the wheel turns. The illusion depends on the
circumstance, that the wheel between each aperture is covered, while
the figure goes further. That the deception may be complete, it is
necessary that every part of the figures not bowing shall be at an
equal distance from the centre of the wheel, and from the slits; also
that the figures possess equal thickness and colour.