138 Lessons in Nature Study. 



shape of this little pond, and show where the sand is piled, 

 and where the little stream runs into it and out of it. 



The above lesson gives opportunities to bring out higher 

 lessons with higher classes. The rainfall as the origin of 

 streams and the laws of streams apply to the diminutive rill 

 whose source is the eaves of the house and whose mouth is 

 the little temporary pond in the lowest part of the school- 

 yard. Whole rivers and systems of rivers may be traced 

 and mapped, and the laws of their growth, flow, deposits, 

 and erosion studied from so humble an object, the water- 

 shed in this case being the roof of the building itself, and 

 for that reason all the more conspicuous. 



The formation of a mud-bank, S, and the delta, Z>, are well 

 worth study. This shows how streams are the enemies of 

 lakes. The inlets are constantly trying to fill up the lakes 

 with mud, while the outlets are trying to cut open a wider 

 and deeper channel to let out the water stored up. 



Our pupils found a rill flowing down the hillside, which 

 emptied into a small puddle of quiet water. At the mouth 

 of this rill a delta had formed with thirteen separate streams. 

 The sediment had been sorted in a truly wonderful manner. 

 Practical and systematic observations upon temperature by 

 the aid of the thermometer are valuable as lessons. They 

 are best given in the school-yard. I have found them very 

 helpful to geography work later on. 



TEMPERATURE. 



I wonder how warm it is this morning. Frank, you may 

 take the thermometer out and find how hot it is. Frank 

 returns, having found the thermometer to register 72. 

 Where did you take the temperature ? Go out and see if it 

 is just the same on the north side of the building, Mary. 

 Mary finds it only 70. Floyd is now sent out into the 

 road to find the temperature there. He returns and finds 

 the temperature about 71. Try to find the reason for such 

 difference of temperature. Is it warmer on the north or 



