THE EFFECT OF WEIRS. 37 
have the golden eggs; if we would have chickens we must 
let the fledglings grow ; and experience has shown that the 
provisions of the law relating to close time, spawning fish, 
and fry, which are based on this theory, are among the 
most valuable of all the enactments touching salmon 
fisheries. 
But “over-fishing,” whether by fair means or by foul, is 
not sufficient of itself to account for the depletion of some 
of our salmon rivers and the total ruin of others. All of 
them in this respect have been subject to the same disease ; 
and all of them have had the same remedy administered, 
yet, while the patient in one instance has recovered, he has 
obstinately persisted in dying in another. 
It is clear, therefore, that we must look for some cause 
over and above over-fishing as the principal factor in the 
deterioration of our salmon fisheries. This will be found 
in the artificial conditions of a densely populated manu- 
facturing and mining country, whose rivers have been 
made to serve many other purposes besides those of fish- 
production, in the furtherance of which the interests of the 
fisheries have too often been ignored. Dams for raising 
the water to supply a mill were among the earliest 
obstacles placed in the way of the incoming salmon, and, 
together with similar obstructions raised specially to 
facilitate the capture of the fish, barred their progress to 
the spawning grounds. Sometimes such dams were used 
to serve the double purpose of driving a mill-wheel and 
catching the fish. These obstructions, however, as already 
stated, very soon attracted attention, owing to the hindrance 
they caused to navigation. When, in 1215, the Barons 
wrung from King John the admission of the rights 
enumerated in Magna Charta, not the least important 
point on which they insisted was the demolition of all 
