mean stage of flow is
taken as the basis upon which to start the experiments. The experiments
and analysis of the water were made by Professor Riddell, at intervals
of three days, from May 21st to August 13, 1846, and reported to the
Association of American Geologists and Naturalists.

The water was taken in a pail from the river in front of the city of New
Orleans, where the current is rather swift. That portion of the river
contains a fair average of sedimentary matter, and it is sufficiently
distant from the _embouchure_ of the last principal tributary to allow
its water to mix well with that of the Mississippi.

'The temperature,' says the Professor, 'was observed at the time,
and the height of the river determined. Some minutes after, the
pail of water was agitated, and two samples of one pint each
measured out. The measure graduated by weighing at 60 degrees
Fahrenheit 7,295.581 grains of distilled water. After standing a
day or two, the matter mechanically suspended would subside to the
bottom. Nearly two thirds of the clear supernatant liquid was next
decanted, while the remaining water, along with the sediment, was
in each instance poured upon a double filter, the two parts of
which had previously been agitated, to be of equal weight. The
filters were numbered and laid aside, and ultimately dried in the
sunshine, under like circumstances, in two parcels, one embracing
the experiments from May 22 to July 15, the other from July 17 to
August 13. The difference in weight between the two parts of each
double filter was then carefully ascertained, and as to the inner
filter alone the sediment was attached, its excess of weight
indicated the amount of sediment.'

As the table may be interesting, showing the height and temperature of
the water as well as the result of the experiments at the different
times, we introduce it complete:

TABLE _showing the Quantity of Sediment contained in the Water
of the Mississippi River_.

Date of Height Temperature. Grains of Sediment
Experiment. of River in a Pint of
above Water.
Low
Water.

1846. ft. in. deg. A. B.
May 21 10 11 72 6.66 7.00
" 25 10 11 73 9.08 9.12
" 27 10 10 78 7.80 9.00