Letters on natural magic, addressed to Sir W. Scott / [Sir David Brewster].

  • David Brewster
Date:
1833
Catalogue details

Licence: Public Domain Mark

Credit: Letters on natural magic, addressed to Sir W. Scott / [Sir David Brewster]. Source: Wellcome Collection.

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    nous circles by whirling round a burning stick, in which case the circles are always red. In virtue of this property of the eye, an object may be seen in many places at once; and we may even exhibit at the same instant the two opposite sides of the same object, or two pictures painted on the opposite sides of a piece of card. It was found by a French philosopher, M. D'Arcet, that the impression of light continued on the retina about the eighth part of a second after the lumi- nous body was withdrawn, and upon this principle Dr. Paris has constructed the pretty little instru- ment ca.\\e(\i\\eThav7natropp, oxlheM^onder-tiirner. It consists of a number of circular pieces of card, about two or three inches broad, which may be twirled round with great velocity by the application of the fore-finger and thumb of each hand to ]jieces of silk string attached to opposite points of their circumference. On each side of the circular piece of card is painted part of a picture, or a part of a figui'e, in such a manner that the two parts would form a group or a whole figure, if we could see both sides at once. Harlequin, for example, is painted on one side, and Columbine on the other, so that by twirling round the card the two are seen at the same time in their usual mode of combina- tion. The body of a Turk is drawn on one side, and his head on the reverse, and by the rotation of the card the head is replaced upon his shoulders. The principle of this ilhision may be extended to many other contrivances. Part of a sentence may be written on one side of a card and the rest on the reverse. Particular letters may be given on one side, and others upon the other, or even halves or parts of each letter may be put upon each side,