STORAGE AND PASSES 289 



The gradient was so flat that there was no need 

 for a pass. All that was required was that the run of 

 the water over the smooth pitching should be broken. 



"The next most important difference is that, 

 instead of having only one opening for the water to 

 go through, I have from three to eight openings, 

 according to the width of the pass. The advantage 

 of this is that from three to eight times the quantity 

 of water that flows through the old pass goes through 

 the openings before any gets over the top. This 

 great increase entices fish to enter. Even if more 

 than double the quantity went down, the fish could 

 easily run through ; whereas, with so much, the old 

 pass would be quite useless. 



"The stones which are placed in the pass stand 

 from 18 inches to 30 inches high, according to the 

 size of pass. They are placed so that each row will 

 be opposite its neighbour, breaking the force of the 

 water 27 per cent. The fish do not have to jump 

 over each barrier, as in the old pass a task they 

 detest and usually decline. They swim through the 

 openings with the greatest ease, and never attempt 

 to jump over the top. The gradient being so flat, 

 they swim up the pass more quickly than one can 

 walk ; fish never remain in the pass. 



" The advantages of the flat gradient and the open- 

 ings are that spring and summer fish new from the sea 

 go straight through. In this the pass differs from 

 all other passes. Where control of the water can be 

 got at falls the pass can be made the same width 

 throughout; but at weirs where control has been 



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