THE HISTORY OF THE MICROSCOPE 



21 



One of Von Leeuwenhoek's microscopes con- 

 sisted of a lens, embedded in a large sheet of 

 copper with a movable rod which acted as a 

 mount for the specimen. 



pound microscope of to-day is a very 

 complicated and delicate instrument. 

 It should always be handled with intel- 

 ligence and care. 



Problem. Place a compound microscope 

 before you and find the various parts as they 

 are mentioned. 



Von Leeuwenhoek placed a 

 small aquatic animal in a glass 

 tube which he fastened in 

 front of a microscope. Through 

 the lens he saw the circulation 

 of blood in the animal's tail. 



I. There are three distinct sets of parts : 



A. The mechanical part supports the 



other parts and makes possible their controlled movements. 



B. The optical j^art does the actual magnifying which is made possible 

 by the rays of light passing through the lenses. 



C. The illuminating part is used to direct and regulate the light. 



II. All of the mechanical parts together constitute the stand, which has a 

 heavy base supporting a leg or pillar. Projecting horizontally from the top of 

 the pillar, parallel with the base, is the stage. There is a hole in the middle of 

 the stage through which the light passes. Above the stage is a continuation 

 of the pillar, and extending from this over the stage is the arm, which carries a 

 vertical tube. Projecting on both sides of the arm are disks with ridged edges. 

 These are connected with a pinion that causes the tube to go up or down when it 



