CH. X] 



PROJECTION APPARATUS FOR DRAWING 



321 



substitute can be made by means of opaque curtains enclosing one 

 corner of a room. This would be something like the early drawing 

 rooms or tents used by Kepler and others for sketching landscapes 

 (fig. 88, 89). It is advantageous to have the cloth curtains 

 rendered fire -proof by saturating them with a solution of sodium 

 tungstate, or some other fire-proofing solution (see Popular Science 

 Monthly, Vol. LXXXI, 1912, p. 397). 



(Proceedings of the Amer. Assoc. Adv. Science, Vol. XLIII, 

 1894, p. 119.) 



FIG. 179. PHOTOGRAPHIC AND DRAWING BOOTH (P D) IN A LARGE 



LABORATORY. 



This booth contains water and electric supply for photography and for 

 projection work including drawing, printing and photo-micrography. 



PROJECTION APPARATUS FOR DRAWING 



456. The apparatus used for drawing may be the ordinary 

 magic lantern (fig. 1-2), the projection microscope (fig. 121), the 

 opaque lantern (fig. 92-111), or a photographic camera (fig. 117, 

 217). 



457. Drawing on a vertical surface. For this, the only addi- 

 tion to any of the forms of projection apparatus is a vertical draw- 

 ing-board, mounted so that it may be moved to a greater or less 

 distance from the apparatus to get the desired size of image. Or 

 one may use a fixed wall for the drawing surface and move the 



