Thomas Hankins and Robert Silverman investigate an array of instruments from the seventeenth through the nineteenth century that seem at first to be marginal to science--magnetic clocks that were said to operate by the movements of sunflower seeds, magic lanterns, ocular harpsichords (machines that played different colored lights in harmonious mixtures), Aeolian harps (a form of wind chime), and other instruments of "natural magic" designed to produce...