high power objectives, except when substage condenser 

 is used, which subject is left for future consideration. 



The sources of light are either daylight or artificial 

 light. In the former the light from a northern sky is 

 preferable and in the latter a flat-wick oil lamp, or a 

 Welsbach gas burner. An ordinary gas flame should 

 not be used on account of the difficulty of obtaining 

 equal illumination and the constant flickering which is 

 very injurious. When using the flat-wick lamp the 

 narrow edge of the flame should be used, as this is 

 more intense than the broad side. 



Fig. 46. Fig. 47. 



Illuminating object with plane mirror. Illuminating object with concave mirror. 



When using daylight place the microscope, as 

 nearly as possible, directly before a window, and when 

 a lamp is employed have it on the table either in front 

 or at the right side of the microscope and within 

 easy reach. 



