414 Fisuing iv AMERICAN WATERS. 
or falls formed at the passage past the steps. Indeed, if it 
be practicable, the more the chambers are hollowed out, so 
as to deepen the water as much as possible in places, and 
thus to break and deaden the force of the stream, the better. 
Excellent results have been obtained by this arrangement. 
Of course this adds somewhat to the expense, but people 
should consider rent when they are making a salmon-fishery, 
which, if it is made, may in all probability be worth a very 
large sum of money annually, to risk the loss of which for 
the want of any little precaution, which may cost but a very 
trifling sum comparatively, is very bad economy, and hence 
every possible chance should be given to the fish. 
Salmon-ladders can be made of wood, but they are far bet- 
ter of stone, being less liable to destruction or damage. It 
is a question, however, whether a salmon-ladder could not be 
better and more cheaply made and put together of iron. 
Such a structure might be supported very easily and firmly 
by means of light iron piles driven into the head of the river 
below the dam, and made in lengths which could be bolted 
on to the dam and riveted together, much easier than stone 
or mason’s work can be secured. 
Among other passes, there is one which is perhaps better 
suited to a natural fall, though it was in use formerly upon 
navigable rivers, where locks and dams were placed to suit 
the navigator. This was an artificial cut, coming into the 
river at the foot of the dam, but let out of the river some dis- 
tance above it, so as to make the ascent, which is broken by 
the dam, gradual and easy. There are many contrivances 
for helping fish surmount falls and dams, and they vary con- 
siderably, according to the nature and position of the ob- 
struction ; so that, while it is impossible to lay down any gen- 
eral rule of construction for all, yet the principle that a cer- 
tain depth and head of water is reserved for the passage of 
the fish, and that no fall of water up which a salmon has to 
pass should have a greater incline than 1 in 9 or 10, are those 
by which alone the construction can be guided. 
