28 SALMON [D,E. 



" To prevent any communication arising from an acciden- 

 tal overflow of the ponds themselves, I raised embankments 

 upon the intersecting walks of two feet in height, so that the 

 several families of fish which the ponds contain can have no 

 access, direct or indirect, to each other. Where the rivulet 

 is divided for the purpose of supplying the several ponds, I 

 have formed an artificial fall in each stream, of a construction 

 to prevent the fish from ascending one stream and descending 

 another. Finally, where the water discharges itself from the 

 ponds, the channels are so secured by wire-grating that it is 

 as impossible for the young fish to escape as for any other 

 fish to have access to them. The whole occupies an area of 

 nearly eighty feet square. 



" My experimental basins being thus prepared, my next 

 object was to secure the fish, the progeny of which were to 

 form the subject of experiment. With the view, there- 

 fore, of securing two Salmon, male and female, while in the 

 very act of continuing their kind, I provided myself with 

 an iron hoop five feet in diameter, on which I fixed a net 

 of a pretty large mesh, so constructed as to form a bag 

 nine feet in length by five feet in width. I then attached 

 the hoop and net to the end of a pole nine feet long, thus 

 forming a landing net on a large scale. The weight of the 

 net with its iron hoop being upwards of seven pounds, it in- 

 stantly sank to the bottom on being thrown into the water. 



" Being thus prepared with all the means of carrying my 

 experiment into practice, I proceeded to the river Nith on 

 the 4th January 1837, and readily discovered a pair of adult 

 Salmon engaged in depositing their spawn. They were in 

 a situation easily accessible, the water being of such a depth 

 as to admit of my net being employed with certain success. 

 Before proceeding to take the fish, I formed a small trench 

 in the shingle by the edge of the stream, through which I 



