THE CONSTRUCTION OF PONDS. 77 



is the hatching-house described in a former chapter. 



After the young trout attain to the size of 

 about an inch or little over in length, or are old 

 enough to take food, they should be transferred 

 from the hatching-house to these pools where 

 they are to remain for a year; they are then to 

 be transferred to the upper pond where they re- 

 main another 3 r ear; on the following year they 

 are let into the middle pond by means of a 

 spout or conductor, with a gate at the upper end ; 

 this conductor should be made of durable ma- 

 terial, and be laid sufficiently low in the dam 

 to let the water together with the fish run from 

 the upper into the middle pond. 



The same arrangement is made in the mid- 

 dle dam, and the fish after remaining in the 

 middle pond a year, are let into the lower pond. 

 The pools and the two upper ponds are to be 

 supplied from year to year by successive crops 

 so that none of them are empty. 



When springs have not sufficient length for 

 such a succession of ponds, or perhaps only one 

 dam, the young trout may be kept for a year 

 in tanks or a pool, the water being supplied by 

 a spring, and then transferred to the pond, where 

 they must run their chance of being devoured; 

 if, however, the old fish are well fed, the pro- 

 bability is, a great proportion of the young fry 

 would escape. 



