16 . 



B. Pillar. It is that portion which is fastened to 

 the base and may be one or two, according to the 

 construction of the stand. It carries upon its upper 

 end the joint or axis. 



C. Arm. This is connected with the pillar by the 

 joint and supports all theworhing parts of the instru- 

 ment. 



D. Body. This is the tube-portion to which the 

 optical parts are attached. 



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 Micro- 

 scopical Society of London. It is also called the /////- 

 versa! 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. Objectives. 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 optical 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. Eye-Piece 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 objective. This 

 and objective will be treated more fully later on. 



