CH. IX] 



DO AND DO NOT IN MICRO-PROJECTION 



317 



27. For high powers like oil 

 immersions, the screen distance 

 must be short, the screen and 

 light perfect, the room very 

 dark and the spectators close 

 to the screen ( 401-410). 



28. Remember the advan- 

 tages of the small-carbon arc 

 lamp for use on the house light- 

 ing system for drawing and for 

 demonstrating to a few ( 417). 



29. Use sunlight when it is 

 available (419). 



30. One can do excellent 

 micro-projection by home- 

 assembled apparatus ( 424). 



31. For passing from micro- 

 projection to lantern-slide pro- 

 jection it must be remembered 

 that the lantern-slide picture is 

 much brighter with the same arc 

 light. To avoid the great con- 

 trast, one would do well to use 

 a tinted glass in the magic 

 lantern to soften the light as 

 for opaque and lantern-slide 

 projection ( 282). 



32. Study faithfully the 

 "troubles" with the magic lan- 

 tern in Ch. I, and in this chap- 

 ter ( 435-439)- 



27. Do not try high power 

 projection for a long screen dis- 

 tance, a light room or a poor 

 screen, or anything else not in 

 accordance with the most exact- 

 ing work. 



28. Do not forget the advan- 

 tages of the small-carbon arc 

 lamp on the house lighting 

 system for drawing and demon- 

 strations for a few persons. 



29. Do not neglect the most 

 brilliant light, i. e., sunlight, 

 when it is available. 



30. Do not refrain from micro- 

 projection because you do not 

 have an expensive special out- 

 fit. Home-made apparatus is 

 often more effective and can be 

 assembled by any one. 



31. Do not forget the phy- 

 siology of vision in passing from 

 a dim to a brilliant light or the 

 reverse. 



32. Do not expect the appra- 

 atus to supply the brains. 



