Fro. 104. 



o o 



o 



Fig. 105. 



Figs. 104-105. These dii^rams illustrate the obliteratiTe effect on faintly-showing contours of sharp and strong internal marks. The 

 reader will see, if he recedes from the picture, that the Butterflies' or Letters' contours near the bold marks vanish^ while those apart firom 

 markings remain perfectly distinct. The markings, at the same time, ally themselves to kindred details in the background. 



