98 THE AXGLEE AXD HUNTSMAN 



larger fish are not removed, and the resulting shortage of 

 natural food will necessitate artificial feeding, an impor- 

 tant factor for consideration. 



"A pond may be located in a ravine, necessitating only 

 the erection of a dam. If the ravine is subject to heavy 

 freshets, it will be best to construct the dam of masonry or 

 heavy timbers, at least at its crest, and a spillway must be 

 provided and screened to prevent the escape of the fish. 

 In this latter particular great precaution must be exercis- 

 .ed, because if the screening is improperly done there will 

 be great danger of its clogging with ice and debris during 

 flood periods, resulting in damage to the pond. 



" Ponds that are wholly or partly surrounded by trees 

 are desirable in many respects. If possible, the ponds 

 should be shaded during the summer months ; but this does 

 not mean that they must be entirely void of sunlight, as 

 that is an important factor in the production of small aqua- 

 tic animal life. If surface water is strongly discolored by 

 decayed vegetation or contains other deleterious matter, it 

 should not be permitted to enter the pond. Small trenches 

 cut around the sides of the pond will usually be found val- 

 uable in carrying surface water to a waste ditch. In the 

 fall of the year care should be taken to keep the pond free 

 of leaves as far as possible, as they will cause considerable 

 trouble on the inlet and outlet screens. 



" Ponds should be so constructed that the overflow may 

 be conducted to a similar pond at a lower level. The water 

 may be used over a number of times by giving it a fall of 

 at least' 12 inches, so that it will become aerated before 

 entering another pond. 



"If the pond is slightly lower than the source of the 

 water, the natural surface of the ground may form the bot- 

 tom of the pond. In that case the embankment may be of 

 earth, but in order to provide for a firm foundation an exca- 

 vation of at least one foot lower than the pond bottom 

 should be made where the embankment is to extend. In a 



