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then called eyepiece or ocular. In the diagram 

 (Fig. 28) the course of rays from the object through 

 the objective and eyepiece is shown. O G repre- 

 sents the objective, F L the field lens and E L 

 the eye lens of the eyepiece. As the rays from the 

 object pass through the objective they are seen to 

 cross before reaching the field lens, are converged 

 as they pass through and further converged by the 

 eye lens E L. At the point c d they form a real 

 image of the object, which can readily be seen by 

 placing- a ground glass or piece of oiled paper at 

 this point. It is an interesting experiment and 

 one which we recommend trying. The eye lens 

 enlarges this image and forms a greatly magnified 

 virtual image at c f. From this diagram several 

 changes with consequent results can be noted. 



If the objective is of short focal length, a larger 

 real image is formed at c d. 



If the distance between objective and eyepiece 

 is increased, an enlarged real image at c d 

 results. 



If the eyepiece is of higher power, an enlarged 

 virtual image is formed at c f. 



In the same manner a reduced magnifying 

 power may be obtained by reversing these con- 

 ditions. 



As has already been stated a 1 inch lens with a 

 distance of 10 inches between it and the image 

 gives a power of 10 diameters, and the eyepiece 



