344 



Substage 

 Condenser 



DRAWING WITH HOUSE CURRENT 



[Cn. X 



Microscope _ 



Objective '' ^ Ocular 



FIG. 192. 



DIAGRAM OF THE MICROSCOPE ARRANGED FOR DRAWING ON A 

 HORIZONTAL SURFACE. 



The light is from an arc lamp supplied by the house current (fig. 188, 189). 



A right-angled prism is used to reflect the rays down upon the drawing sur- 

 face. 



The designations are self explanatory except in the ocular r i means the real 

 image formed by the objective and field lens (see fig. 207). 



The adjustment screw heads at the side of the microscope are: 



/ a Fine adjustment. 



c a Coarse adjustment. 



H The handle in the pillar for carrying the microscope. 



(3) From the difficulty of getting the small lamp and condenser 

 in the optic axis without the use of an optical bench it has been 

 found much easier to get the light upon the specimen and through 

 the microscope by placing the arc lamp and its condenser at right 

 angles to the microscope, and to use the regular microscope mirror 

 for reflecting the beam through the substage condenser (fig. 193). 

 If the substage condenser is not used, the mirror reflects the beam 

 directly on the specimen, as for low power projection. 



