OPTICAL PROPERTIES OF LENSES. 



Purpose of the Microscope. The microscope 

 is an instrument which magnifies near objects, so 

 that we are better able to examine their structure 

 than is possible with unassisted vision. 



Simple and Compound Microscopes. Micro- 

 scopes are divided into two classes simple and 

 compound the difference between the two being 

 as follows: With the simple microscope the object 

 is viewed directly and the magnified image shows 

 the object erect, or in its real position. It must 

 consist of one lens, but may consist of more, which 

 however are in close contact. With the compound 

 microscope a magnified image is observed and this 

 in a reversed position from the true one of the 

 object, so that what is right in the object is left in 

 the image. This must consist of at least two 

 lenses with suitable distance between them. 



Lenses. As microscopes depend upon the 

 action of lenses it seems fitting that these, as 

 well as the action of light passing through them, 



