37 



ERECT IMAGES IN DRAWINGS 



[CH. X 



Objegtive 



Objecl-h 

 Object-a 



FIG. 210. DIAGRAM TO SHOW THAT THE SIZE OF THE. IMAGE DEPENDS 



UPON THE DISTANCE OF THE OBJECT FROM THE CENTER OF THE LENS. 



(From The Microscope). 



The object at Object-a necessitates an image at Image-a; while if the same 

 object is moved closer to the lens, as at Object-b, the image will move farther 

 from the lens (Image-b) and be correspondingly larger. 



// The principal foci of the lens (objective). 



axis The principal axis of the lens. 



Secondary axis a, Secondary axis b Represent the secondary axes which 

 mark the limit of the object and the two images. 



With the object farther from the lens the secondary axes are in full lines, 

 while for the object nearer the lens the secondary axes and the image are shown 

 by broken lines. 



523. For a translucent vertical screen. The object is put on 

 the stage facing the objective and right edge up. The image will 



