CH. X] DRAWING WITH THE MAGIC LANTERN 329 



has some sort of device, like a Hooke's jointed rod, so that the lamp 

 may be adjusted without getting up (see fig. 43). 



For the arc lamp on the house circuit see Ch. Ill and 486 below. 



463. Other radiants for drawing. Any of the sources of light 

 discussed in the first six chapters can be used for drawing. One 

 must use the precautions given in those chapters for getting a good 

 screen image by a proper alignment and separation of the elements 

 of the apparatus, and by suiting the darkness of the room to the 

 light. 



DRAWING WITH THE MAGIC LANTERN 



464. Drawing wall diagrams. The simplest form of projec- 

 tion for drawing is with the magic lantern. With it the preparation 

 of wall diagrams is very easy (fig. 185). 



If one has a lantern slide of the picture or object to be drawn it is 

 put into the lantern as for ordinary projection. The drawing- 

 board is then arranged at a distance to give the desired size, and 

 then all the lines traced with a crayon, a brush or a coarse pen. One 

 can use water colors or paints. For the black nothing is better 

 than India ink. 



If one has a smooth wall to which the drawing paper or cloth can 

 be fastened, then the lantern can be moved closer or farther away 

 to get the desired size. 



If one has no lantern slide, then a negative may be made of the 

 subject to be drawn, and the negative used in the lantern instead of 

 the lantern slide. The negative should not be too dense or the 

 lines will not come out clearly. 



For making negatives to draw from, it is advantageous to use 

 lantern-slide dry plates. These will be of the right size for the 

 lantern and are more transparent than ordinary negatives. 



For lettering diagrams nothing is more convenient than the large 

 rubber type found in sets used in advertising and sign making. 



465. Getting the desired size. Any desired size may be 

 obtained by varying the distance between the drawing surface and 

 the projection objective. Either the lantern or the drawing surface 

 or both must be movable. 



