Fig. 1. 



OPTICAL IMAGES. 



CHAPTEE I. 



1. Great importance of the subject in relation to all the effects of vision. 

 2. Explanation of how an object is seen with the naked eye. 3. 

 Images produced by plane reflectors. 4. How rays are reflected from 

 ' such surfaces. 5. Experimental verifications of this. 6. Image of 

 a point in a plane reflecting surface. 7. Image of an object in the 

 same. 8. Real and imaginary images. 9. Images produced by 

 spherical reflectors. 10. By a concave reflector. 11. Experimental 

 verification. 12. Variation of position, and magnitude of image. 

 13. Images in convex reflectors. 14. Images produced by transparent 

 bodies. 15. Refraction. 16. Cases in which light will not enter a 

 transparent body. 17. Reflection of objects in water. 18. The 

 fallacy of the fable of "the Dog and the Shadow." 19. Objects seen 

 at the bottom of a transparent body. 20. Case of water and glass. 

 21. Broken appearance of a rod immersed in water. 22. Cases in 

 which rays cannot emerge from a transparent body. 23. Experi- 

 mental verification. 24. Reflection by a rectangular Prism. 25. 

 Images produced by lenses. 26. Six kinds of lenses. 27. The axis 

 of a lens. 28. Example of each kind of lens. 29. Optical image 

 produced by a convex lens. bO. Relative position of the object and 

 image. 



1. THE images of visible objects produced by reflection from 

 smooth, or polished surfaces, natural and artificial, and by looking 

 through transparent media, bounded by surfaces having certain 

 curved shapes, play a part so important in the effects of vision, 

 that it must be regarded as highly interesting to explain the 

 optical principles upon which the production of such images 

 depends, so far at least as may be necessary to render intelligible 



LARDNER'S MUSEUM OP SCIENCE. o 81 



No. 80. 



