312 ELEMENTS OF FARM PRACTICE 



It is now known that these germs or microbes cause 

 many of our contagious diseases, such as tuberculosis (con- 

 sumption), diphtheria, and typhoid fever. The mistress of 

 a household must remember that she cleans her house, not 

 only that it may look well-kept, but more especially to make 

 it sanitary. While dust and dirt in themselves may not be 

 directly harmful, they are likely to become hotbeds for 

 disease germs. 

 Questions: 



1. What may often be done to improve unsanitary conditions, 

 if they exist? 



2. Why should not fowls be allowed about the house? 



3. What are the objections to house flies, and how may they 

 be kept out? 



4. Explain the terms bacteria and germs or microbes. 

 Arithmetic: 



1. How many square feet of wire netting are required to make 

 a screen for a window 30 in. by 60 in.? What would the screen cost 

 at 2c. per square foot? 



2. What is the cost of screen at 2c. per square foot for a door 

 3 ft. by 7 ft.? 



3. Screen window frames are usually made of lumber 1 in. thick 

 and 2}4 in. wide. How much lumber is required to make a full size 

 screen frame for a window 30 in. by 60 in.? What is the lumber worth 

 at $35.00 per thousand feet? 



4. Screen door frames are usually made of lumber 134 in. thick 

 and 3 in. wide. How much lumber is required to make a screen door 

 frame 3 ft. by 7 ft.? What is the cost of the lumber at $35.00 per 

 thousand feet? 



5. What is the cost of material to make screens for a house having 

 3 doors and 14 windows? (Use sizes and prices given above.) 



VENTILATION 



Ventilation is Simple. — People and animals need pure 

 and fresh air in order that they may be healthy. Supply- 

 ing this fresh air is much simpler, especially in the country, 

 than is generally supposed. It is known that air moves 

 about easily, and that it presses down, due to its weight, 

 upon the earth. If, for any reason, the pressure is not the 

 same on all sides, the air will move in the direction of the 

 least pressure. Every pupil knows that when a fire is 

 lighted in a stove the heated air and smoke will rush up the 

 chimney. When air is heated, it expands; hence it becomes 

 lighter. This principle may be illustrated by heating a 

 bottle so that the air in it will be quite hot. -Then place 



