68 THE BOOK OF NATURE STUDY 



fashion. The long twilight of summer should be emphasised, 

 and the increase in the number of nights where there is never 

 complete darkness as one passes northwards should be sug- 

 gested, as far as possible in connection with human life. In the 

 reading lessons also opportunities should be seized to indicate 

 the importance in human life of the sudden onset of darkness 

 in tropical and equatorial countries. 



In the summer evenings in this country we watch with un- 

 concern the disappearance of the sun beneath the horizon, know- 

 ing that a long stretch of daylight is still before us. Contrast 

 this with the countries where 



" The sun's rim dips ; the stars rush out : 

 At one stride comes the dark." 



No explanation of the differences in twilight can be profitably 

 attempted at the Nature Study stage, any more than we can hope 

 to make clear the actual movements of the earth ; but it is much 

 if the facts of observation can be brought out. Remembering 

 also that in the history of the race countless observations of the 

 main phenomena of the seasons were made before a science arose 

 which tried to correlate and explain these, it seems a sound method 

 to allow a period of mere collection of facts to precede also in 

 the history of the individual an attempt to find explanations. 



The noting of the changes in the length of the days as deter- 

 mined by the changes in the times of sunset and sunrise may 

 of course be done at any season of the year, and does not demand 

 anything beyond the necessary tables. Direct shadow observa- 

 tions should, however, be also made whenever the day permits. 

 If the conditions allow, the comparatively speaking imposing 

 experiment of a tall stick in the playground has no doubt much 

 to be said for it, but as so much of the school work must neces- 

 sarily be done in the schoolroom, open-air experiment may be 

 well supplemented or even replaced by a window-sill experiment 

 which permits of much more continuous observation. 



Whenever the day permits, take a few shadow observations. 

 If the room is sunny, this can be very simply effected by putting 

 a pin or darning needle into the cork of a gum bottle placed upon 

 the window-sill, or upon a desk if the sun enters the room freely. 

 Measure the height of the pin above the surface of the table 



