MICROSCOPE AND ACCESSORIES. 



SIMPLE MICROSCOPE : EXPERIMENTS. 



§ 4. Employ a tripod or other simple microscope, and for object a 

 printed page. Hold the eye about two centimeters from the upper sur- 

 face of the magnifier, then alternately raise and lower the magnifier until 

 a clear image may be seen. (This mutual arrangement of microscope 

 and object so that a clear image may be seen, is called focusing, see § 

 37). When a clear image is' seen, note that the letters appear as with 

 the unaided eye except that they are larger, and the letters appear erect 

 or right side up, instead of being inverted, as with the compound mi- 

 croscope (§ 3, 34). 



Hold the simple microscope directly toward the sun and move it away 

 from and toward a piece of printed paper until the smallest bright point 

 on the paper is obtained. This is the burning point or focus, and as 

 the rays of the sun are nearly parallel, the burning 

 point represents approximately the principal focus 

 (Fig. 1). Without changing the position of the paper 

 or the magnifier, look into the magnifier and note that 

 the letters are very indistinct or invisible. Move the 

 magnifier a centimeter or two farther from the paper 

 and no image can be seen. Now move the magnifier 

 closer to the paper, that is, so that it is less than the fo- 

 cal distance from the paper, and the letters will appear 

 lic distinct. This shows that in order to see a distinct image 

 Triplet for ike Pocket, with a simple microscope, the object must always be 

 nearer to it than its principal focal point. Or, in other words, the object 

 must be within the principal focus. Compare § 34. 



After getting as clear an image as possible with a simple microscope, 

 do not change the position of the micro- 

 scope but move the eye nearer and farther 

 from it, and note that when the eye is in 

 one position, the largest field may be seen 

 (§ 33)- This position corresponds to the 

 eye-point (§ 36) of an ocular, and is the 

 point at which the largest number of rays 

 from the microscope enter the eye. Note 

 that the image appears on the same side of 

 the magnifier as the object (§ 34). 



Simple microscopes are very convenient 

 when only a small magnification (Ch. Ill) 

 is desired, as for dissecting. Achromatic, 

 triplets are excellent and convenient i ox th.e.^ 1QAK ~ SimpleMicroscopewithSpecial 



. -_ v . . . Mechanical Mounting to Hold and 



pOCket {tig. 8). For USe m Conjunction Foctts the Magnifier and to Support 



with a compound microscope, the tripod and Light the object. 



