SCIOPTICON MANUAL. 77 



treatment. It is not damaged in the least, but ready 

 to make its mark again as often as it is necessary. 



This leaden mould is the typo that prints the picture, 

 a solution of gelatine and India-ink being poured over 

 it before the glass is placed in position. 



A slight pressure is given in a press of peculiar con- 

 struction, squeezing out the surplus ink; a few minutes 

 is allowed the ink to set, when the glass, being removed, 

 brings with it the delicate gelatine picture, which is well 

 named " Excelsior/' 



CHAPTEE YL 



COLORING SLIDES. 



WRITTEN FOB THE SCIOPTICON MANUAL. 



THE magic lantern has caused much astonishment 

 and delight from its origin to the present time. The 

 pictures or slides for it were formerly drawn or painted 

 on glass, and when magnified by the lantern lens, even 

 the most minute lines looked coarse, and every imper- 

 fection was brought out. Much time and care, therefore, 

 were requisite to make fine pictures, so that they were 

 comparatively rare and expensive, while the coarser 

 ones abounded; thus the lantern came to be regarded 

 as a toy, fit only for the amusement of children. An 

 instrument, however, so well calculated to aid in the 

 advancement of science and education, on account of 

 the size of the diagram that may be represented on the 

 disk, and the fact that the attention of an audience is 

 better secured when the only object visible is the dia- 



