THE MICROSCOPE 



27 



certain point that they will slowly ignite materials 

 placed at the principal focus. 



For purposes of magnification objects are placed 

 either beyond or within the focal point. While 

 in both instances magnification is apparent to the 



FIG. 10. Refraction of Light Rays by Lenses. 



1. Double convex lens causes convergence of rays to focal point (F). 2. Double 

 concave lens causes divergence of rays from focal point (F). 



observer, it will be found that the reasons for these 

 apparent enlargements of the image are different in 

 the two cases. Objects placed beyond the focal 

 point of a lens will give rise to enlarged images, termed 

 real images, which can be projected upon a screen. 

 The degree of enlargement is directly proportional 



