88 THE BOOK OF NATURE STUDY 



frost should be also entered. The date of cutting the hay, of the 

 ripening of Wheat or Oats should be recorded. If these charts 

 are kept and compared from year to year, the effect of climatic 

 changes, which are perhaps the most important factor in the 

 cultivation of Wheat and other cereals, can be estimated. It is 

 quite possible, in agricultural districts, to have charts of this kind 

 kept by even the lower classes in a school. The date of the flower- 

 ing of the different weeds found in fields may also be observed ; 

 in this way children come to associate certain plants with the reap- 

 ing of Corn. Even those who live near a town can observe a 

 great deal in the market gardens, so common in the neighbourhood 

 of towns. 



BIBLIOGRAPHY. A. D. Hall, Rothamsted Experiments ; A. D. Hall, The Soil. 



