ELEMENTARY PHOTO-MICROGRAPHY. 41 



The use of two lamps for lighting an object 

 from opposite sides is not to be confounded with 

 the " double lighting " where two different modes 

 of illumination are employed. This refers rather 

 to transmitted light for lighting up the field or 

 background, and reflected light for illumination of 

 the object itself. Such a combination gives results 

 different from those yielded when only one kind of 

 lighting is used, and the effect is modified accord- 

 ing as one or other of the lights predominates. 



Pleasing varieties of pictures of great delicacy 

 may also be obtained by putting a 3 x lin. slip of 

 ground-glass, or white porcelain, on the stage, 

 underneath the object when this is mounted on 

 clear glass. 



In the method of double lighting, the direct 

 light from behind the specimen will prevent over 

 intense shadows from the reflected or side light : a 

 fault met with in some photographs of thick 

 objects mounted on opaque light-coloured ground 

 and exposed only to one source of light. 



