Devices and Helps in Nature Study. 197 



To the Teacher. Such observations may be begun in 

 September and continue through the year. I prefer Sep- 

 tember 2oth as the best time for beginning these observa- 

 tions, for it is autumnal equinox and the shadow begins- to 

 lengthen then toward winter. 



A few hints to the children to watch the shadow and 

 measure it every noon will soon show them that the great 

 change from summer to winter is recording itself on the 

 ground. It is not advisable to measure the shadow every day. 

 Once or twice a week .is sufficient, and the lengthening of 

 the shadow will show itself more than if measurements are 

 taken daily. 



At the end of the month such questions as these may be 

 asked : What has been the hottest day this month ? What 

 was the temperature that day ? In what direction have the 

 prevailing winds been blowing ? How was the wind blow- 

 ing the hottest day ? The coldest day ? How has the 

 shadow changed during the month ? 



If possible, keep record of temperature with Centigrade 

 thermometer, and compare the readings C. and F. In the 

 above table the temperature is taken in degrees Fahrenheit. 



The shadow may also be measured in linear and in metric 

 units so as to give practice in both tables. It is also a good 

 plan to have a large card of Bristol-board ruled and the 

 weather record kept on it and hung up in the school-house 

 for reference. 



The following facts will usually be brought out : i. A 

 fall of temperature accompanies a change of wind toward 

 the north. 2. The thermometer shows less variation of 

 temperature on cloudy calm days than on clear gusty ones, 

 etc. 



An additional column may be added .headed " Weather," 

 and under this head may be placed such facts as rain, snow, 

 etc. 



Definition Cards. 



Some years ago the author made a collection of botanical 

 specimens to illustrate every definition in Gray's Botany. 



