CONTENTS. 



XV 



Double refraction, .... 



Colours of thin films : iridescence, 

 Rainbows : primary and secondary, 



CHAPTER XXIII. Reflection and Refraction at Curved Sur- 

 faces, . ... 



Concave and convex mirrors : geometrical focus, 



Real and virtual foci, ..... 



Formation of images by mirrors, , 



Spectral illusions by means of concave mirrors, . 

 Lenses and their foci, . . . . . 



Convex and concave lenses : chromatic aberration, 

 Formation of images by lenses, . . 



Simple microscope, - . . . . . 



Magic lantern, . . . . 



To determine the focal length of a convex lens, 

 Camera obscura, . . . . 



Prism-lens for camera, 



Pinhole focus, 



Human eye, . . . ... 



Spectacles, . . . ... 



Telescopes with lenses, . ' . 



Reflecting telescopes, ..... 



Compound microscope, . 



9. RADIANT ACTION : INVISIBLE LIGHT, 



CHAPTER XXIV. Radiant Heat, .... 

 Radiant heat obeys law of reflection, . 

 Isolation of heat rays and separation from more re- 

 frangible rays, ..... 

 Reflection of radiant heat. Burning mirrors, . 

 Apparent reflection of cold, ... 

 Radiation and absorption : effect of nature of surface, . 

 The Light Mill or radiometer, . 

 Passage of radiant heat through water, . 

 Burning glass of ice, ..... 

 Sunshine recorder, ..... 

 Automatic meteorological registration, . . 



CHAPTER XXV. Radiant 



Photography, . 

 The collodion process, 

 Dry plate processes, 



Chemical Action or Actinism : 



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