518 NATURE STUDY. 



THE WORK OF STREAMS. 



A visit to a brook, to observe the work of streams in 

 wearing away, carrying, and depositing material, will sup- 

 plement the rain study. Observe such points as the fol- 

 lowing : 



The velocity of the current. Swiftest in level or "steep" 

 parts of the stream ? In the middle, or at the sides ? On 

 the outside of a curve, or the inside ? In narrow or wide 

 places ? In shallow or deep places ? Why ? Compare 

 water in a curve to a wheel going around. Which part 

 goes most rapidly, the hub or the tire ? How does the 

 velocity affect the power the stream has of wearing away 

 the earth, and of carrying along mud, sand, or stones ? 

 Experiment and see. 



The wearing away, or erosion, by the stream. Show how 

 it wears away deposits of soil placed in it. Where does 

 the stream wear most, on the outside or inside of curves ? 

 Why ? In what kind of soil does it wear most rapidly ? 

 What makes the stream wind about so ? 



The carrying or transportation by the stream. Throw in 

 soil containing mud, sand, pebbles. Which drops first ? 

 Which is carried farthest ? Show by experiment differ- 

 ences in carrying-power in slow-flowing and swift-flowing 

 parts of the stream. Narrow or partly fill a portion of 

 stream, so as to increase its velocity, and note result on the 

 character of the bottom. Note appearance of bottom in 

 swift and slow parts of stream. The former is usually 

 sandy or stony, the latter muddy. Why ? 



The deposits by the streams. Where, how, and why bars, 

 islands, points, and shallows are formed. 



What the stream is making. Try to find illustrations 

 on a small scale, and to describe or define and explain the 



