JAPANESE MAGIC MIRROR—PIERS. 119 
the screen had to be placed much nearer the mirror in order to 
obtain a distinct image. 
I have heard an explanation given for this phenomena which 
appears to be very rational. It is said that the face of the mirror, 
previous to being polished, is scraped by an instrument which 
quickly reduces the rigid portions caused by the raised designs 
on the back, while the thinner and more elastic portions give 
under the tool and thus retain their convexity. 
