7657. RIVERS, Velocity of.—
I shall
forward your ingenious paper on the subject of
the Mississippi to the Philosophical Society.
To prove the value I set on it, and my wish
that it may go to the public without any imperfection
about it, I will take the liberty of
submitting to your consideration the only passage
which I think may require it. You say,
“the velocity of rivers is greatest at the surface,
and generally diminishes downwards”.
And this principle enters into some subsequent
parts of the paper, and has too much effect
on the phenomena of that river not to merit
mature consideration. I can but suppose it at
variance with the law of motion in rivers. In
strict theory, the velocity of water at any given
depth in a river is (in addition to its velocity at
its surface) whatever a body would have acquired
by falling through a space equal to that
depth.—
To William Dunbar. Washington ed. iv, 537.
(W.
1804)
