CHAPTER II 



COMPOUND MICROSCOPES 



The compound microscope has undergone wonderful changes 

 since 1667, the days of Robert Hooke. When we consider the 

 crude construction and the limitations of Robert Hooke 's micro- 

 scope, we marvel at the structural perfection and the unlimited 

 possibilities of the modern instrument. The advancement made 

 in most sciences has followed the gradual perfection of this 

 instrument. 



The illustration of Robert Hooke's microscope (Fig. 7) will 

 convey to the mind more eloquently than words the crudeness 

 of the early microscopes, especially when it is compared with 

 the present-day microscopes. 



STRUCTURE OF THE COMPOUND MICROSCOPE 



The parts of the compound microscope (Fig. 8) may be 

 grouped into — first, the mechanical, and, secondly, into the 

 optical parts. 



THE MECHANICAL PARTS 



1. The foot is the basal part, the part which supports all 

 the other mechanical and optical parts. The foot should be 

 heavy enough to balance the other parts when they are inclined. 

 Most modern instruments have a three-parted or tripod- 

 shaped base. 



2. The pillar is the vertical part of the microscope attached 

 to the base. The pillar is joined to the limb by a hinged joint. 

 The hinges make it possible to incline the microscope at any 

 angle, thus lowering its height. In this way, short, medium, 

 and tall persons can use the microscope with facility. The 

 part of the pillar above the hinge is called the limb. The limb 

 may be either straight or curved. The curved form is pref- 

 erable, since it offers a more suitable surface to grasp in trans- 

 ferring from box or shelf to the desk, and vice versa. 



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