Vol. LVI. 
No. 2482. 
NEW YORK, AUGUST 21, 1897. 
M.00, PER YEAR. 
FISH CULTURE ON FARMS. 
HOW TO BUII.D A DAM. 
For Large or Small Streams. 
Trout do very well, as do all other fish in ponds of 
the ordinary kind. Every farm on which there is a 
flowing stream should have a pond, if it is only for 
making ice in the winter, 
either for use in the summer 
dairy—for no dairy can be 
worked for all it is worth 
without ice in the summer—or 
for use in the household and 
the harvest field. It is well 
to kill two birds with one 
stone, and it is easy to do this 
where a pond, even of small 
size, may be made. The dam 
for confining the water is the 
only difficulty that presents 
itself, and this becomes easy 
if one recognizes two simple 
facts, that water is heavy, and 
will go through a very small 
hole, and that once it makes 
a very minute opening, it 
enlarges this very quickly. A 
dam must be, therefore, ab¬ 
solutely tight, or be made of 
solid materials, so that the 
water, finding a small creek, 
will not be able to enlarge it. 
The pressure of water is equal 
to 62 pounds on every square 
foot, so that the aggregate 
pressure on a dam 10 feet high 
and 20 feet long is equal to 
more than six tons. No won¬ 
der that dam builders, not re¬ 
alizing this enormous press¬ 
ure, fail to make safe dams. 
As a dam is mostly the weak¬ 
est at the bottom, and the 
whole of this pressure is ex¬ 
erted just there, the dam goes 
out unexpectedly, unless it is 
built on really scientific and 
safe principles. These are, 
that there must be no leak, or 
if it is impossible to prevent 
it—which it never is, with 
good work—the materials of 
the dam must be such as will 
not wash away to the smallest 
extent. 
To build a safe and perma 
nent dam these rules are in¬ 
violable, whether the dam be 
small or great. A trench is 
to be dug for the bottom of 
the dam to the solid rock or 
clay, and to a sufficient depth 
in the clay, to make a per¬ 
fectly impervious bottom by 
thorough puddling, and a 
closely-jointed core of plank 
driven into the clay to a depth 
of, at least, a foot. This 
trench is dug across the 
stream, the earth being 
thrown on either bank, or partly on each to make the 
filling. The plank core is then made double, the 
joints being broken, and to get these planks close to¬ 
gether, it is well to put two or three scantling length¬ 
wise, and bolt them through both planks, to draw 
them together. The lower side of this core is 
strengthened by braces of*planks solidly placed, and 
spiked at the top to resist the pressure of the water. 
The whole is then filled in with solid earth without 
stones or any rubbish. If any of such waste is put in, 
the water soaking, as it may, through the earth, and 
meeting these, will soak along them, making a little 
opening-which will increase, and the result will be 
the washing out of the lower part of the dam ; this 
weight being removed, the inside pressure will in¬ 
evitably start the core, and some time the dam will 
give way. 
The dam should slope inside, one foot in one ; that 
is at an angle of 45 degrees; but outside, the slope 
should be 1% foot to one horizontal. A dam so made 
will be safe against floods of any kind if the top is 
covered with planks to avoid washing of the earth by 
overflow, unless it be covered with a plank skin, well 
fastened to beams imbedded in the earth. This mode 
of construction is indispensable for the whole width 
of the stream ; the sides or wings may be made of 
solid earth, but so high that no overflow can occur 
there. It is well to provide a plank flume at one side 
for a waste way for high 
water, to relieve the dam from 
overflows. This center of the 
dam may have a flooring of 
plank the whole length, with 
side wings in which grooves 
are made to receive a plank or 
two to raise the water if it be 
desired in a dry time. A dam 
thus made will stand as long 
as the builder lives, and his 
children after him, if the tim¬ 
ber is of good, dry, white oak, 
or of any other durable tim¬ 
ber ; but hemlock or other 
easily decaying wood should 
not be used. 
For a fish pond, this middle 
floor, with the planks fitted 
on it, is useful to prevent the 
fish from escaping down the 
stream, if this is not desired. 
This is done by fitting in 
frames made of half or quarter 
inch wire net, through which 
the water may escape, but the 
fish cannot. Fish will jump 
quite a height in ascending a 
stream to get over a fall, but 
I never knew or heard of them 
jumping to go down a stream 
over such an obstacle as this. 
Instinct impels them to go up 
stream to spawn, and this is 
the only way in which fish 
will try to go over obstacles. 
Fish ladders are made for fish 
to go up over dams, and they 
will overcome a very swift 
current in this endeavor. 
These ladders are made by 
putting a trough on one side 
of the dam, down into the 
water below, and placing 
cross pieces alternately from 
one side, to a few inches of 
the other, thus making small 
places where there is dead 
water in which the fish may 
rest if they wish, without 
being washed down again; 
they will get over any sort of 
dam with sufficient help in 
this way. 
For a larger dam, some dif¬ 
ferent method must be em¬ 
ployed to withstand the 
greater pressure. I have re¬ 
cently built a dam 17 feet 
high and 75 wide in this way : 
Heavy timbers of whole trees 
were bedded in the bottom of 
the stream, the ends resting 
against solid rock blasted out for the purpose. Two 
such mudsills were laid in this way, and on these, 
heavy timbers were laid three feet apart and sup¬ 
ported in several places between, by blocks pinned to 
them. Other timbers were then laid across the stream 
parallel with the sills, the front ones gradually going 
back so as to make the front slope 1% foot in one. 
THE CRIMSON RAMBLER ROSE. Fig. 223. See Rtjralisms, Page 550. 
