THE SENSE OF SIGHT. 297 



ficial light. Such books being hard to hold, the elbows 

 gradually settle down against the sides of the body, and 

 thus the book is held too close to the eyes, or at a bad 

 angle, or the body assumes a bad position. 



6. Resting the Eyes. Frequently rest the eyes by 

 looking up and away from the work, especially at some 

 distant object. One may rest the eyes while thinking over 

 each page or paragraph, and thus really gain time instead 

 of losing it 



7. Strength of Light. Have light that is strong 

 enough. Remember that the law of the intensity of light 

 as affected by distance is that at twice the distance the 

 light is only one fourth as strong. Reading just before 

 sunset is not wise. One is often tempted to go on, not 

 noticing the gradual diminution of light. 



8. Evening Reading. In all ways endeavor to favor 

 the eyes by doing the most difficult reading by daylight, 

 and saving the better print and the books that are easier 

 to hold for work by artificial light. Writing is usually 

 much more trying to the eyes than reading. By carefully 

 planning his work the student may economize eyesight, 

 and it is desirable that persons blessed with good eyes 

 should be careful, as well as those who have a natural 

 weakness in the eyes. It often results that those inherit- 

 ing weak organs, by taking proper care, may outlast and 

 do more and better work than those naturally stronger, 

 but who, through carelessness, injure organs by improper 

 use or wrong use (ab-use). 



9. Artificial Light in the Morning. Reading before 

 breakfast by artificial light is usually bad. 



