CH. I] 



MICROSCOPE AND ACCESSORIES 



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Figs. 23, 24, 25. Diagrams showing the formation of real and of virtual 

 images and of the retinal image in using the simple microscope. See the 

 explanation of Figs. 14, 15, 16. 



COMPOUND MICROSCOPE 



I 15. A Compound Microscope. — This enables one to see an enlarged, 

 inverted image. It always consists of two optical parts — an objective, to pro- 

 duce an enlarged, inverted, real image of the object, and an ocular acting in 

 general like a simple microscope to magnif y* this real image (Fig. 26). There 

 is also usually present a mirror, or both a mirror and some form of condenser or 

 illuminator for lighting the object. The stand of the microscope consists of 

 certain mechanical arrangements for holding the optical parts and for the 

 more satisfactory use of them. (See frontispiece.) 



§ 16. The Mechanical Parts of a laboratory, compound microscope are 

 shown in the frontispiece, and are described in the explanation of that.figure. 

 The student shoula study the figure with a microscope before him and become 

 thoroughly familiar with the names of all the parts. 



OPTICAL PARTS 



{S 17. Microscopic Objective. — This consists of a converging lens 

 or of one or more converging lens-systems, which give an enlarged, inverted, 

 real image of the object (Figs. 14, 26) . And as for the formation of real 

 images in all cases, the object must be placed outside the principal focus, in- 

 stead of within it, as for the simple microscope. (See \\ 12, 60, Figs. 16,26.) 



Modern microscopic objectives usually consist of two or more systems or 



