46 



E. Nose-Piece. This is an extra piece which 

 is attached to the lower part of the tube. 



Society Screw. This is a standard screw 

 which is cut into the nose-piece and is called so 

 from the fact that it was first established by the 

 Royal Microscopical Society of London. It is 

 also called the universal screw and is in general 

 use in this country and England ; it has lately 

 been adopted by some firms on the continent of 

 Europe. 



F. Objective. This is screwed into the nose- 

 piece and is called so because it is nearest the 

 object. It is the most important of the two opti- 

 cal parts (of the microscope proper) and upon its 

 perfection the distinctness of the image and 

 therefore the value of the instrument almost 

 entirely depends. 



G. Eyepiece or Ocular. It is called so because 

 it is nearest the eye and is the remaining optical 

 part. It magnifies the image given by the objec- 

 tive. This and objective .will be fully treated 

 later on. 



H. Draw-Tube. This is that portion of the 

 body which moves in the outer sheath and which 

 receives the eyepiece. It is provided for the pur- 

 pose of attaining different lengths and variations 

 in magnifying power. 



