ILLUMINATION 273 



from the object we are looking at, and, in most cases of sunlight, 

 indirect sunlight should be reflected from the object to one's eyes. 



Windows should never be built in the rear of a school room unless 

 to obtain a good breeze during hot weather. Such windows ought 

 to be very high at least 8 feet above the floor so that all light be 

 reflected toward the ceiling. It is better to have such windows 

 hinged at the bottom and covered with an opaque shade. The 

 window can then be dropped to allow air to enter without allowing 

 light to fall from the back directly on students. Such windows 

 are sometimes called " breeze windows." South light is bad since 

 direct sunlight is obtained during a great part of the day. Too much 

 direct light often irritates and tires people. 



If windows are located on the east side, early morning light 

 enters the room, purifying the air. After ten o'clock in the morning 

 indirect rays of light enter, since the sun has moved to a position in 

 the heavens whence no direct light can enter the windows. 



Rooms which face the west, especially school rooms, are often 

 desirable since the direct sunlight does not enter the room until 

 after school hours. If the sun does begin to shine into the room in 

 the early afternoon, the room becomes very warm and uncomfortable 

 during hot weather. 



North light is unsatisfactory because little sunlight enters the 

 room at any time of the day. Hence, the room, although cool in 

 summer, has little of the purifying influence of the sun. 



Windows Shaded by Buildings. Buildings are sometimes very 

 close to each other, producing dark rooms. This has been largely 

 overcome by the use of ribbed or prism glass which diffuses the light 

 throughout the room. In many modern school houses this glass is 

 used at the top of the windows. Basements, dark halls, and dark 

 rooms may be easily made lighter by the use of ribbed glass. Very 

 frequently shop windows and store windows are provided with this 

 type of glass to obtain better illumination during the day. 



QUESTIONS 



1. Why is it impossible to look directly at the sun? 



2. Why do dark glasses assist us in looking at the sun? 



3. How should we sit with reference to the light when we are reading? 



