OPTICAL INSTRUMENTS. 193 



The Multiplying G7as*. This glass is formed as a plano- 

 convex lens, the convex side of the lens being cut in what 

 the lapidaries term facets, consequently as many flats or 

 facets as are cut in the glass, so many objects will be seen. 

 They are sometimes mounted in a conical case, and by giv- 

 ing it a quick circular motion the objects appear to jump 

 one over the other. Price, $0.50 to $3.00. 



Fig. 709. 



Claude Lorraine Glass. (Fig. 709.) This consists of a 

 variety of different colored glasses, about one inch in diame- 

 ter, mounted in horn frame and turning on one centre, for 

 producing a great variety of colors and showing their com- 

 bination ; it also will be found both pleasing and useful for 

 viewing eclipses, clouds, landscapes, &c. 



Price, $1.50 to $3.00. 



Claude Black Glass Mirrors. Claude's black glass 

 mirrors, for perspective drawing. These are very useful for 

 the young artist, as they condense or diminish the view into 

 the size desired for the intended picture, and all objects 

 bear their relative proportions. Price, $2.50. 



VOL. n. 17 



