CH. VI] DRAWING BY THE AID OF PHOTOGRAPHY 



179 



parts will be in focus and in proper perspective. Then with the 

 projection apparatus using a photographic objective, print an enlarged 



FIG. 109. PROJECTION MICROSCOPE, TABLE, AND ADJUSTABLE DRAWING SHELF. 

 (Modified from Optic Projection). 



DB Drawing board with a 25 X 30 cm. glass plate in the middle for tracing 

 on the back of photographs. It is placed on the brackets to form the adjustable 

 shelf (ADS). 



Is Leveling screws in the bottom of the table legs. 



Rheostat The balance for regulating the electric current of the arc lamp. 



c c, ks Electric cable and knife switch. 



Table The projection table with drawer (d). This table is 100 cm. high, and 

 the top 125 cm. long and 50 cm. wide. It is stained by aniline black. 



ADS Adjustable shelf with a drawing board having a glass center 25 X 30 cm. 



bt Bolts with thumb nuts holding the shelf at any desired height on the legs. 



N R Mazda lamp and reflector to throw the light up through the picture which 

 is being traced. 



c Cable with separable cap to attach to the lighting system. 



Arc Lamp The right-angled carbon arc lamp for supplying light to the pro- 

 jection microscope. 



Condenser The three lens condenser and water bath (fig. no). 



Microscope The compound microscope with substage condenser and ocular. 



m 45 mirror or prism for reflecting the light directly downward upon the 

 drawing shelf. 



Axis, Axis The principal optic axis. 



picture as follows: Work in a dark room or at night. Place the 

 negative near the condenser as for lantern slide projection (fig. no). 

 Either the projection apparatus must be movable of a movable 



