325 On Breeding ofF'i^h, and the. 



ture of six inches by four inches, or of the same size as 

 the hole ; which frame must be covered with a brass gra- 

 ting (for iron will rust) of a moderate strength, and close 

 enough to prevent the smallest water-mouse from passing 

 through ; otherwise all the spawn and young fry will be in 

 danger of being devoured by them. 



(3) Near the middle of this box or trough lay another 

 piece of thick board across, as long as the width of the 

 trough, and about six inches or more wide ; which, when 

 nailed upon the edges of the side pieces, will keep them 

 more steady and firmer. 



(4) Let the lower end-board, where the water is to run 

 off again, be at least three inches thick, as the greatest 

 pressure is against it ; have an opening cut in the top six 

 inches wide and four inches deep, and a rabbet made on 

 the outside and anotiier on the inside, deep enough to leave 

 at least an inch thick of the solid hoard in the middle, and 

 wide enough to admit a frame with a brass wire grate like 

 (2) on the outside, which can be shoved in from them ; 

 th« wires should not be above a Ime and a half asunder, 

 like those at the top, and for the same reason men- 

 tioned before. In the inside, opposite this opening, shove a 

 bit of board in in its groove downwards, to stem the water 

 either entirely, or to regulate its running off, according as 

 you find it necessary, or to pull it entirely out when the 

 whole of the water is to ruii off. 



(5) Tiiere must be two strong covers, one between the 

 two cross pieces described in (2,3), and the other below 

 the middle cross-piece quite to the lower end (4); both 

 covers n)ust be fastened behind with strong hinges, and 

 before with handles to lift them conveniently up by ; and 

 as these boards are apt to warp, on account of the water 

 within and the air without, it is requisite to have each 

 clamped with two or three cross-pieces. 



(6j If you think fit to give the young fishes more air 

 than what enters at the two brass grates, you may have in 

 each cover a hole made of the same size, and guarded with 

 a brass wire grate, as (S), and for the same reasons : I have 

 done this out of precaution, but have found it in the end 

 to be unntcessary. 



§ II. 



(]) Spring-water out of rocks or stony ground is the 

 properest for breeding trouts or salmon ; but where it is 

 not to be had, any other spring- water may do, provided 

 the current is strong enough to prevent freezing in cold 

 frosty weather. 



(2) If 



