Ch. I] 



SIMPLE AND COMPOUND MICROSCOPES 



in the first only a retinal image is formed, while in the second, a screen 

 image and from that a retinal image. 



In this book the first form of microscope is mainly considered except 

 in Ch. VI and VII, where the projection microscope is much used. 



§ 2a. The word Microscope is 

 from two Greek words: /uf/cp6s — 

 mikros, small, and aKoirdv — 

 skopein, to see. The word was 

 compounded and given a Latin 

 form by Giovanni Faber of the 

 Academy of the Lincei, as shown 

 by a letter of his to Cesi, Presi- 

 dent of the Lyceum, dated April 

 13,1625. Faber says: "As I also 

 mention his [Galileo's] new 

 occhiale to look at small things 

 and call it Microscopium. "Jour. 

 Royal Microscopical Society, 

 1889, p. 578; Carpenter-Dallin- 

 ger, p. 125. 



Simple and Compound 

 Microscopes 



§ 3. A simple microscope 

 or magnifier is a lens or a 

 combination of lenses to use 

 with the eye, and with it an 

 enlarged, erect image is seen, 

 that is, the enlarged image 

 has all its parts in the same 

 position as in the object it- 

 self (fig. 4), and but one 

 image is formed, and that is formed upon the retina. 



§ 4. A compound microscope is one in which a lens, or combination 

 of lenses, called an objective, forms a real image, and this real image 

 is looked at, as if it were an object, by the eye and a magnifier or 

 simple microscope known as an ocular. The image seen has the 

 object and its parts inverted. In the compound microscope two 

 images are formed, one by the objective independent of the eye, and 

 the other on the retina by the action of the eye-lens of the ocular and 

 the cornea and crystalline lens of the eye (fig. 3). 



Fig. 



4. Fine Print Seen by the Unaided 

 Eye and through a Magnifier. 



