DO AND DO NOT IN MICRO-PROJECTION [Cn. IX 



9. Make the room dark and 

 use a perfectly white image- 

 screen for micro-projection 

 ( 3 6 o)- 



9. Do not try to project with 

 the microscope in a room that 

 cannot be properly darkened or 

 with a dirty screen. 



i o . Use only the direct current 

 arc light for micro-projection, 

 unless compelled to use alter- 

 nating current ( 412). 



11. Use an ammeter and a 

 variable rheostat or other bal- 

 ancing device and be very 

 careful about the wiring (fig. 2-3 

 188). 



12. The arc lamp must have 

 fine adjustment screws to enable 

 one to keep the arc centered on 

 the objective front ( 362). 



13. Always use a water-cell 

 in micro-projection with the arc 

 lamp radiant ( 364). 



14. Use a mechanical 

 for serial sections ( 366). 



stage 



15. Blacken the objective 

 mounts, and all metal parts of 

 the projection apparatus to 

 avoid glare; make sure there 

 arc no shiny surfaces within the 

 projection apparatus ( 570- 



10. Do not use alternating 

 current if it is possible to obtain 

 direct current. 



n. Do not neglect the am- 

 meter and the variable rheostat 

 when installing a projection 

 microscope. 



12. Do not try to use an arc 

 lamp without fine adjustments, 

 otherwise the crater cannot be 

 kept centered. 



13. Do not project with the 

 arc lamp without using a water- 

 cell to absorb the radiant heat. 



14. Do not try to show 

 selected sections of a series 

 without the help of a mechani- 

 cal stage. 



15. Do not leave the objec- 

 tive mounts with brilliant re- 

 flecting surfaces to dazzle the 

 eyes of the operator, and do not 

 leave shiny surfaces within the 

 apparatus to give cross lights 

 and make the image dim. 



