30 THE FISHERIES. 



them on their return to the river, in the ensuing 

 spring, averaging 12 lbs. and 14 lbs. weight. 



We have, therefore, thought it desirable to make 

 a few experiments with the utmost accuracy, with 

 the view of showing satisfactorily what aperture in 

 the fixed engine will allow a 51bs. salmon to escape. 



In the hecks or rails of cruives in Salmon- weirs, 

 if the bars are two and a quarter inches apart, and 

 placed perpendicularly, a 5 lbs. salmon will escape ; 

 in the bag, or stake net, if the meshes of the inner 

 chambers are of five and a half inches mesh, that is, 

 eleven inches all round, the same sized salmon will 

 escape. 



To ascertain this by experiment with salmon ob- 

 tained from the markets and from various rivers, 

 through different sized meshes, or throuo:h bars of 

 any aperture, is a matter of no difiiculty ; but we 

 considered it desirable to see salmon alive in a fish 

 pond pass voluntarily through the required spaces, 

 and then accurately to weigh them, and we made 

 some slight arrangements which enabled us to pro- 

 secute this inquiry satisfactorily, which we were not 

 enabled to do sooner than the arrival of the peal in 

 the rivers in June, July, and August of the present 

 year. 



During those months live salmon, at the Island- 

 bridge Salmon-fishery, were thrown into the fish 

 ponds, across which divisions were made of a five 

 and a half inch mesh, and bars of two inches, and 

 two and a quarter inches aperture, and then at all 

 leisure times we observed their movements, which 



