336 HELPS IN LESSON PREPARATION 



acid be taken through a tube? 22. Describe the harm 

 that may come to the teeth from eating candy; from using 

 tobacco. 



CHAPTER XXIII 



1. What may be called the windows of Jack's House? 

 2. Describe the white of the eye. 3. Tell what is said of 

 the cornea. 4. What and where is the iris? What pur- 

 pose does it serve? 5. What is the pupil of the eye? 

 6. What part of the eye performs the same work as the 

 lens of a camera? 7. Tell what the retina is, and to what 

 part of a camera it corresponds. 8. In order to have 

 vision of the eye distinct, where must the rays of light come 

 to a focus? 9. If our eyes are neither nearsighted nor 

 farsighted, on what part of the eye are the rays of light 

 focused when we look at a distant object? 10. When 

 we look at near objects, what is necessary in order to bring 

 the rays of light to a focus on the retina, provided our 

 eyes are normal ? 11. Why are the muscles of a normal 

 eye at rest when a person is looking at distant objects? 

 Why must its muscles always work when one is looking at 

 near objects? 12. Why is it restful to the eyes occasion- 

 ally to look off into the distance when we are doing close 

 work? 13. Tell what is meant by convergence, page 238. 

 14. State what is usually the cause of weak sight in persons 

 having otherwise normal eyes, and tell a good way to cure 

 it. 15. Give the points mentioned on pages 239 and 240 

 that we should be careful about while reading. 16. When 

 and why should colored glasses be worn? Why 

 should they not be worn at other times unless advised 

 by an oculist? 17. Give two good reasons why we should 

 neither read nor sew by twilight. 18. Why should we not 

 read by a flickering light? 19. When should we not do 

 close work by artificial light ? Why ? 20. Tell why read- 



