88 Singular Optical Illusion, <$-c. 



A leafless branch, which becomes verdant on the twirling of 

 the card. 



A female in one dress on one side, and another dress on the 

 other. 



The body of a Turk, with his head on the reverse. 



The Watchman's box on one side, and himself on the 

 other. 



Harlequin and Columbine on different sides, appear toge- 

 ther by the revolution of the card. 



A comic head on one side, which, on turning round, be- 

 comes invested with a wig. 



A man sleeping, and awakened by being turned round. 



The principle of the thaumatrope may be extended to many 

 other devices. Parts of a sentence may be written on one 

 side, and the rest of the sentence on the other ; and we may 

 even put halves of the letters or words on one side, and the other 

 halves on the other side. This method of breaking down let- 

 ters or words or sentences may be varied ad infinitum, and 

 will furnish us with a variety of rotatory cyphers. 



Those who have used the thaumatrope, must have been 

 dissatisfied with the general effect of the two combined pic- 

 tures. There is a hobbling motion arising from the imper- 

 fection of the method adopted to produce the rotatory motion, 

 which entirely destroys the effect ; and it is manifest, that the 

 rotatory motion should be produced by quite different means. 



If strings are adopted, they ought to be attached to the 

 circular pieces of card, so that the axis of rotation should be 

 in the plane of the card ; but a solid axis of rotation is decid- 

 edly preferable, and will produce much more pleasing combi- 

 nations. 



No. VII. Singula)- Optical Illusion seen through a Telescope. 



If we direct a telescope to the surface of a distant field on 

 which there are ro objects, such as trees, houses, &c. and if 

 the field of the telescope embraces nothing but the surface of 

 the field, the eye will speedily recognize that the field is hori- 

 zontal or slightly inclined to the horizon, from the perspective 

 of the furrows or drills upon its surface, or even from its 



