412 Fisumve iy Aserican WATtTERs. 
itect should be a man of natural genius as well as learning 
in his profession, and be, withal, a good angler, or know the 
habits of his client. 
When the mill-power is of so much consequence that no 
water can be wasted, and if the fall be great, a fish-ladder is 
indispensable. Fish-ladders were first invented by Mr. Smith, 
of Deanston, in England, and were employed by him very 
successfully, and the great secret of his success was in the 
easy gradient which he gave them. His original plan was 
something like a fall of one foot in twenty; but so easy a 
gradient as this greatly lengthens the ladder, and adds very 
largely to the expense. The chief object of all ladders should 
be to deliver the water they carry to the spot where the fish 
are most likely to find it and to use it. This is, in all dams, 
close to the foot of the dam, and as near as may be conven- 
ient to the strong main stream. If the foot of the ladder 
should be carried too far down the stream below the dam, 
the fish which are at the foot ot the dam will be so far above 
the entrance to the ladder that they will not find it; and if 
it be in some wide eddy or part of the stream where it might 
be more easy to construct the ladder, the fish will not go to 
that part, out of the main stream, to seek it. When it is 
necessary, by reason of the height of the dam, to have a long 
ladder, it should be turned in the middle like a double pair 
of stairs, with a landing or pool half way, so as to deliver the 
water close to the foot of the dam. The far-famed fish-lad- 
der at Ballysadare, in Ireland, is made upon this principle, and 
by the aid of it salmon manage to surmount a fall above thir- 
ty feet in height. The opposite engraving will show the 
principle. 
A stone pier above the entrance of the water to the ladder, 
as at D, is essential in American waters to protect the ladder 
from the ice and the terrific ¢ébris of spring floods. The sal- 
mon are all turning their pretty noses toward the ladder, and 
many of them are ascending. They must think the Irish a 
kind people to have erected such a convenience for them. 
