Lal'es and Pools 



79 



digging shallow ditches on the right and left for 

 carrying off the surplus water when the minia- 

 ture lake is full. In constructing the dam, a 

 trench two feet wide, at right angles to the 

 stream, should be dug to the depth of one foot, 



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7^^^' i^^*m^ 



Fig. 7. A useful pond. 



or until solid ground, unmixed with vegetable 

 matter, is reached. Fill the trench with clayey 

 earth which is free from humus, which will pre- 

 vent the dam from leaking at the bottom where 

 it meets the natural soil. The stream which 

 feeds the lake or pond should be small, and 

 need not be perennial if the dam is raised as 

 high as it should l)e. If the water is dammed 

 back to the depth of twelve to fourteen feet, 

 and the l)anks of the pond are rather steep 

 (A, Fig. 7), a cool, useful miniature lake will 



