240 THE WONDERFUL HOUSE THAT JACK HAS 



do close work by bright sunlight, as it is likely to injure 

 the eyes. When one's eyes feel uncomfortable be- 

 cause of the reflection of intense sunlight from sand, 

 snow, or any other light surface, the protecting power 

 of the iris should be supplemented by wearing colored 

 plane glasses. Where such care is not taken, eyes may 

 become so irritated and sensitive that it is necessary 

 to remain days or weeks in a dark room. Even 

 blindness sometimes results from such exposure. 



One should not wear colored glasses where intense 

 sunlight does not make it necessary, unless so advised 

 by an oculist, for the eyes may be weakened by such 

 subdued light. It is also unwise to do close work by 

 twilight, since the changing light necessitates rapid 

 change in the accommodation of the eyes. Besides, 

 the light often becomes insufficient before the fact 

 is noticed. 



Any light used in reading should be strong and 

 steady, because a flickering light makes the muscles 

 work unnecessarily hard. Artificial light is much 

 more trying than daylight. On this account, when 

 our eyes feel weak and tired, we should use them 

 as little as possible in the evening. A complete rest 

 from such occupations, even for a day, will often give 

 great relief. It is much easier for the muscles of 

 accommodation, if any close work we are doing is kept 

 in a firm, steady position. For this reason, reading 

 while riding on a car or any moving vehicle is trying 

 to the eyes, as the jar resulting from the motion con- 



