376 FARM AND SCHOOL PROBLEMS. 



4. Prevention of weeds that would use up moisture through 

 transpiration. 



5. Tilling the land one season and raising a crop the next. 



6. Two seasons collection of moisture for growing one crop. 



7. Addition of vegetable moisture to the soil to hold water and 

 food for plants. 



EXPERIMENT. 



During the dry season examine the difference in moisture 

 between a plat of ground growing a heavy crop of weeds and a 

 plat that is growing no vegetation. 



EXERCISES. 



Learn the weather signals used by the weather bureau. 



1. White flag indicates fair weather. 



2. White and blue flag foretells local showers. 



3. Blue flag indicates rain or snow. 



4. White flag with black center foretells a cold wave. 



5. A blue triangular flag placed above the weather pen- 

 nant indicates rising temperature. If placed below 

 pennant it means falling temperature. 



Ask or petition your mail carrier to carry the weather 

 signals. 



Have some pupil draw upon the blackboard each day the 

 flag showing the weather report. 



Construct a small convenient place for holding and protect- 

 ing weather instruments. 



Some of the important instruments that should be owned 

 by the school are the following: 



List of Instruments. 



1. Mercurial Barometer. 



'1. Thermometers. 



3 . Wind vanes. 



4. Rain and Snow Gauges. 



5. Anemometers, with sunshine records. 



6. Barographs, thermographs, with devices making automatic 

 records. 



7. Kites, meteorographs, self registering instruments. 



The U. S. Weather Bureau will furnish addresses of man- 

 ufacturers of the above named instruments. 



