30 NATURAL HISTORY OF THE SALMON. 



the Stormontfield bleachfield; this lade comes off 

 the Tay about a mile farther up the river than 

 the ponds. As will be seen in the plan, a pipe 

 (the mouth of which is covered with perforated 

 zinc) is taken from the lade to the filtering pond, 

 the water from which, after being filtered, rises 

 into the upper canal, and flows through the 

 hatching-boxes, which empty themselves into the 

 lower canal, the water from thence escaping into 

 the rearing pond by means of a small artificial 

 stream plentifully supplied with large gravel as 

 shelter to the young fish. A current is kept 

 constantly running through the pond, at the 

 east end of which there is an outlet having a 

 sluice; and just before the water enters the river 

 there is another sluice, for intercepting the de- 

 scending smoults, for the purpose of marking. 

 It will be seen by the plan that there are 300 

 boxes in all, laid out into 25 parallel rows, with a 

 walk or path between each, twelve boxes being in 

 in the row, each box 6 feet long by 1 foot 6 inches 

 broad and 1 foot deep. The fall from the upper to 

 the lower end of each box is 2 inches, and 2 feet in 

 all, so as to allow the water to flow freely through 

 them ; but experience has proved that the fall is 

 not sufficient, and that the quantity of water 



