In simple dissecting microscopes like the Barnes, in 

 which the mirror is in a fixed position, the microscope 

 should be set squarely before 

 the source of light. Diffused 

 day light is always preferable 

 to any artificial illumination. 

 Whatever the source of 

 light may be it is seldom too 

 strong when viewing opaque 

 objects; in fact the want of 

 sufficient light is too often ex- 

 perienced, especially indoors. 

 With transparent objects, 

 however, whether viewed by 

 looking toward the light 

 or by means of a reflecting 

 mirror the contrary is too 

 often the case, so that an 

 object is viewed in a glare 

 of light and is liable to in- 

 juriously affect the eye. 

 When the light is too strong reduce it or change the 

 position of the body or the instrument. 



While in some classes of work it is perhaps unnec- 

 essary to have the very best magnifiers, such as the 

 Aplanatic or Hastings' Aplanatic Triplets, the latter 

 can always be recommended, when the means will 

 permit, on account of the higher results and greater 



Correct manner of holding 

 magnifier and object. 



