CH.r\ 



MICROSCOPE AND ACCESSORIES 



29 



FUNCTION OF AN OBJECTIVE 



53. Put a 50 mm. objective on the microscope or screw off the 

 front combination of a 16 mm.,(^-in.), and put the back combination 

 on the microscope for a low objective. 



Place some printed letters or figures under the microscope, and 

 light well. In place of an ocular put a screen of ground glass, or a 

 piece of lens paper, over the upper end of the tube of the microscope.* 



*Ground glass may be very easily prepared by placing some fine emery or 

 carborundum between two pieces of glass, wetting it with water and then rubbing 

 the glasses together for a few minutes. If the glass becomes too opaque, it may 

 be rendered more translucent by rubbing some oil upon it. 



