OP THE MICKOSCOPE. 21 



whether simple or compound must possess: 1. Certain means 

 for supporting the object and placing and maintaining it in 

 proper position; 2. Means for illuminating the object, whether 

 it be opaque or transparent; 3. Means for transmitting to the 

 eye an enlarged image of the object. 



NAMES OF THE DIFFEEENT PAKTS. 



The different parts which are employed for securing these 

 several ends, have been constructed of an almost endless variety 

 of forms, according to the fancies of the different makers and 

 the requirments of different microscopists. The following are 

 the names of the essential parts of a compound microscope of 

 ordinary construction. The names of the different parts of 

 the simple microscope are the same as those of the compound 

 microscope, but the latter has several parts which do not exist 

 in the former. 



The Stand is the term properly applied to the entire frame 

 used for supporting and illuminating the object and carrying 

 the optical part, the latter consisting of the eye-piece and the 

 objectives. Stands are frequently sold separately, or furnished 

 with eye-pieces only the purchaser making such a selection of 

 objectives as may best suit his special needs. 



The Base or Foot is that part which supports the rest of the 

 stand. 



The Body is the tube to which the eye-piece and objectives 

 are attached. 



The Arm is taat part which carries the body. 



The Collar is the tube in which the body moves. This is 

 found only in microscopes of the Continental form (Plate I) 

 and similar models. 



The Staae is the plate upon which the object is placed for 

 examination. 



The Eye-piece is the short brass tube, with its lenses, which 

 is next the eye. The eye-piece contains an Eye-Glass, which is 

 that next the eye; a Field-Glass, placed next the objective, and 

 a DiapJiragm, consisting of a brass plate with a hole through 

 it, and so arranged as to cut off the outer rays of light. The 



