kalotrope

English

Noun

kalotrope (plural kalotropes)

1. A device invented by Thomas Rose that produces the optical illusion of transforming images by means of two concentric wheels moving in opposite directions.
   • 1858, The Annual of Scientific Discovery, Or, Year-book of Facts, page 238:

     The kalotrope exhibits to an entire company the well-known illusions of the Thaumatrope, but its claims to be considered a perfectly new optical arrangement rest in a peculiarity of action by which a number of illusive changes are brought over any one disc of devices.

   • 1858, The Popular Educator: A Complete Encyclopedia of Elementary, Advanced, and Technical Education, Volume 6, page 194:

     For the true kalotrope effects the two wheels are used; and in 1855 the inventor was kind enough to give the writer the following valuable information with regard to the discs to be used and devices best adapted to the kalotrope. the inner disc has images and the outer disc has slits through which to view them.

   • 1860, John Henry Pepper, The Boy's Playbook of Science, page 315:

     Thus, if we take a disc bearing twelve repeats of a ball in the interior of a ring, each repeat beingso painted that its position is advanced in the ring until it reaches the twelfth ring the point whence it started, and place this on the back disc of the kalotrope, having previously removed the first one, no effect is observed when the weel is rotated beyond the spreading out of the design and general appearance of hazy black circles.