THE MICROSCOPE 



MICROSCOPICAL METHODS 



CHAPTER I 



THE MICROSCOPE AND ITS PARTS 



APPARATUS AND MATERIAL FOR THIS CHAPTER 



A simple microscope (§2, 12); A compound microscope with nose-piece 

 (Figs. 76-95) ; eye-shade (Fig. 67), achromatic ($ 23), apochromatic ({S 25) , dry 

 (^ 20), immersion (§21), unadjustable and adjustable objectives (§26,27); 

 Huygenian or negative (<S 45), positive (g 43) and compensation oculars 

 (§ 46); stage micrometer (Ch. IV); homogeneous immersion liquid (§ 21); 

 mounted letters or figures (§ 60); ground-glass and lens paper ($ 60). 



A MICROSCOPE* 



§ r. A Microscope is an optical apparatus with which one may obtain a 

 clear image of a near object, the image being always larger than the object ; 

 that is, it enables the eye to see an object under a greatly increased visual 

 angle, as if the object were brought very close to the eye without affecting the 

 distinctness of vision. Whenever the microscope is used for observation, the 

 eye.of the observer forms an integral part of the optical combination (Figs. 

 16, 26). 



(S 2. A Simple Microscope. — With this an enlarged, erect image of an 



* For the History of the Microscope see : Harting, Poggendorff, Mayall, 

 Carpenter-Dallinger, Petri ; and Gage, the Origin and Development of the 

 Projection Microscope. 



