1878.] 



The Magic Mirror of Japan. 



137 



AB and BC of the mirror be about equal to one another, the amount 

 of light falling on them will also be equal ; and, since the illuminated 

 areas DE and EF are about equal, they will be equally bright. But if 



Fig. 1. 



a portion AB of the mirror be, for any reason, natter than the re- 

 mainder, then the quantity of light which falls on it, instead of being 

 reflected so as to illuminate the area DE of the screen, will only illu- 

 minate some such area as GH. Now, this area being smaller than 

 EF, but receiving the same quantity of light, will appear much brighter 

 than EF ; in addition, too, the spaces DG and HE receive but very 



Fig. 2. 



t 





A 







Ifcl 















t 







little light, and are consequently relatively dark, the excess of bright- 

 ness, therefore, of the area GH will be apparently much heightened 

 by contrast. And exactly the same reasoning applies to fig. 2, in 

 which the mirror is illuminated by a beam of light diverging from 



