Daedaleum, a new Instrument of Optical Illusion. 37 



mirror or any second instrument, and of being displayed to 

 unlimited numbers at once. 



The apparatus is merely a hollow cylinder, or a moderately 

 high margin, with apertures at equal distances, and placed 

 cylindricaliy round the edge of a revolving disk. Any draw- 

 ings which are made on the interior surface in the intervals 

 of the apertures will be visible through the opposite aper- 

 tures, and if executed on the same principle of graduated ac- 

 tion, will produce the same surprising play of relative motions 

 as the common magic disk does when spun before a mirror. 

 But as no necessity exists in this case for bringing the eye 

 near the apparatus, but rather the contrary, and the machine 

 when revolving has all the effect of transparency, the phe- 

 nomenon may be displayed with full effect to a numerous 

 audience. I have given this instrument the name of Daeda- 

 leum, as imitating the practice which the celebrated artist of 

 antiquity was fabled to have invented, of creating figures of 

 men and animals endued with motion. The peculiarities in- 

 cident to this form of construction, some of which demand the 

 careful attention of artists, will appear from the following in- 

 vestigation. 



Let ABD in the annexed diagram (fig. 1.*) represent a cir- 



Fig. 1. 



cular section of the cylinder, C its centre, E the place of the 

 observer's eye, A an aperture brought on the line AC. For 

 the sake of a more general investigation, let any circle, Oo, P p y 



* It is necessary to remark here, that by a mistake of the engraver the 

 circles in thcahovc diagram are all of nearly equal strength, instead of the 

 middle one ATI), representing the section of the cylinder, being the strong- 

 est, and the outer and inner ones both faint, as in Mr. Horner's drawing. 

 — Edit. 



