The Rock Island Argus. (Rock Island, Ill.) 1877-1885, 1882-01-11
THE RIVER.
How the improvement is
Generally Conducted.
The Low Water Mark and
How Established.

ton, which deals with the Improvement oI
the Mississippi river as an entirety, although
the portion particularized is located below
the Future Great The information is
obtained from the interesting reports of
Captain Ernst, who has charge of the river
improvement, and who has given the sub
ject careful study and general attention.
The first point mentioned in the reports
is the navigable depth of the river between
st. Louis and Cairo, and on this point the
following report is made:
''THE cHANGEABLE CHARACTER
OF the bars and shoals in this portion of
the Mississippi river often making the nav
igation good at some places where in the
previous year it was bad, and vice versa,
render it desirable that record should be
kept of the depths found at different sea
sons where distractions are most often
found.
s'Without record of this kind the
engineer often has tradition alone to guide
him in deciding whether any given portion
of the river shall be the subject of i'm
provement or not. 1t will often happen
that this photographic survey will show
good channel at place where the year
before it was very bad, and where the year
after it may, without improvement be the
same.
1T is evidently impracticable, ON ac-
count of the cost, to provide special OBJ
servers who shall watch the appearance
and disappearance of every bar over long
stretch of the river
''THE ASSOCIATION
of ST Louis and New Orleans pilots has
furnished me the means of compiling rec
ord which will answer the purpose reasonably
well, and will think constitute n valuable
contribution to the history of this portion OF
the river. Whenever member has passed
over the river between st. Louis and Cairo,
he immediately makes q written report to
the association, noting any change in the
location of the channel and the depths
upon the bars. These reports, after serv-
ing their purpose with the association, have
been transferred to me.
THE depths were measured with the or
binary sounding lead of the boat, except
where tn ere were less than six feet, when
a rod was usually employed, giving a'more
accurate measurement.
At high stages the boats frequently did
not follow the deepest water, the reports
were much less frequent, and the measure
ments themselves were much less accurate.
The data procured in this way, at such
times, would be misleading rather than in
structive. The statement therefore, does
not include the reports made during the
spring months
The record, as it stands, gives a fair
picture of the condition of the river during
the low water season, as it appeared to
those engaged in navigating it. In many
cases a less depth is reported by one per
son than was found by another on the
same day, the difference being due to the
difficulty of following out the deepest
channel in wide expanse of water.
Strict accuracy cannot be claimed for any
one measurement, but if several days be
taken together, the guage record being
also considered, a close approximation to
the depth existing throughout the season
upon every bar will be found.
The river did not reach a very low
stage this year, and the navigation upon
the whole was better than it has sometimes
been in former years. The least depth
reported was that in the crossing from
Wahoo to Cape Girardeur which was five
feet The phenomenon of falling river,
attended by maintained or increased
depth upon the bars, is illustrated in
number of cases.
AN effort was made to procure similar
reports for the portions of the river above
St. Louis, but it was not successful"
STANDARD Low WATER.
The lowest water recorded at ST. Louis
is the low water of 1868. That level con
stitutes the zero of the guage at this place,
and it is usual in speaking of low water,
without other qualifications, to refer to the
lowest water or the zero of the guage
The term low-water, when applied 10
place of reference from which are to be
measured the channel depths, to be pro-
cured or maintained by the works of
Improvement, has never been defined"
such a level must be determined by
considerations different from those by
which the zero of gauge is fixed. The
latter may be anywhere, it being conven-
lent to place it so low that the reading
shall always have the plus sign. Low
water of 1858 seems a very proper level for
that purpose. But to take as the level be-
low which depth of 8 feet is to be pro-
cured, is to require more of the works than
is necessary.
''The season of lowest water always oc-
ours in the winter when the sources of sup
ply in the north are closed by frost. At
this season the river is subjected to ice
gorges, which, while putting stop to nav
igation, dam back the water and cause the
gauges to give indications which are en-
tirely abnormal. The low water of 1868
occurred on the 21st of December and
there is every indication in the record be-
fore and after that it was occasioned by an
ice gorge. For the purposes of
navigation it is matter of indifference
how little depth there may be in the
channel when the river is frozen over The
level from which it will be proper to meas
ure depths should be the lowest one to
which the river is likely to fall during the
navigable season. This can only be de-
termined by comparison of the gauge
record with the dates upon which naviga-
ton has been suspended on account of
ice for considerable number of YEARS
The gauge record kept at st. Louis up to
October 16, 1871, gives simply an approx
imation to the different stages Of the
river.
REGULAR GAUGE.
In October. 1871, a regular gauge was
established by the signal service, and was
read for the first time on the 18th of that
month and in 1878 the present perma-
nent gauge was established by Mai. Mer-
rill. reliable gauge record exists, then,
for only about ten years. This is, per-
haps, not a sufficient length of time to fix
with accuracy standard low water, but
as such a standard is constantly needed
for the purpose of studying photographic
maps itseems proper to select one which
CHI . Bf