120 SALMON FISHERY. 



with an aperture of fix inches by four inches, or of 

 the fame fize of the hole ; which frame muft be 

 covered with a brafs grating (for iron will ruft) of 

 a moderate ftrength, and clofe enough to prevent 

 the fmalleft water-moufe from paffmg through ; 

 otherwife all the fpawn 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 acrofs, as long as the 

 width of the trough, and about fix inches or more 

 wide, which, when nailed upon the edges of the 

 fide pieces, will keep them more fleady and firm. 



4. Let the lower end board, where the water is 

 to run off again, be at leaft three inches thick, as 

 the greateil preflure is againft it ; have an opening 

 cut in at the top, fix inches wide, and four inches 

 deep ; have a ravet made on the outfide, and ano- 

 ther on the infide, deep enough to leave at lead 

 an inch thick of the folid board in the middle, and 

 wide enough to admit a frame with a brafs-wired 

 grate on the outfide, which can be fhoved in from 

 the top ; the wires fliould not be above a line and 

 a half afunder, no more than thofe at the top, for 

 the fame reafon as mentioned before. In the in- 

 fide, oppofite this opening, fhove a bit of a board 

 in its groove downwards, to ftem the water either 

 entirely, or to regulate its running off, according as 

 you find it neceffary, or to pull it entirely out, 

 when the whole of the water is to run off. 



5. There muft be two flrong covers, one at 

 each fide of the middle crofs piece ; both covers 



muft 



