CYLINDRICAL MIRRORS. 



169 



mation of distorted pictures by reflection from cylindrical 

 and conical mirrors. In these representations the original 

 image from which a perfect picture is produced is often 

 PO completely distorted, that the eye cannot trace in it 

 the resemblance to any regular figure, and the greatest 

 degree of wonder is of course excited, whether the original 



image is concealed or exposed to view. These distorted 

 pictures may be drawn by strict geometrical rules ; but I 

 have shown in Fig. 11 a simple and practical method 

 of executing them. Let M N be an accurate cylinder 

 made of tin-plate or of thick pasteboard. Out of the farther 

 side of it cut a small aperture abed', and out of the 

 nearer side cut a larger one A B C D, the size of the 

 picture to be distorted. Having perforated the outline of 



