174 
SECOND BOOK. 
fore, when there is no danger of malarial air entering 
from outside, the windows of the sleeping rooms 
should not be closed, unless the rooms are venti- 
lated in some other w r ay. 
8. Sleeping in rooms where the air is allowed to 
become foul and unhealthy causes us to rise in the 
morning with headache, or with a feeling of dulness 
and weariness, and may even bring on serious illness. 
Of course, the windows should not be kept open at 
night where the wind blows chiefly from malarial 
places. 
9. When, from any cause, a house shows signs of 
dampness in its walls or floorings, there is more 
need than ever for plenty of ventilation, because the 
moisture rising from the soil brings with it gases 
that are dangerous to health. Every ground-floor 
should therefore be raised above the soil, and air 
should pass freely through the space beneath it. 
THE CLOTHES WE WEAE. 
1. Before describing what are the best materials 
for clothing, it is well to say a few words about the 
heat of the body. 
2 . A doctor often places the bulb of a small 
thermometer in the mouth of a person who is ailing, 
to find out whether the body is at its proper 
temperature. He knows that it ought to have an 
