4028. INVENTIONS, Air screw propeller.—
I went some time ago to see a machine
which offers something new. A man
had applied to a light boat a very large screw,
the thread of which was a thin plate, two feet
broad, applied by its edge spirally around a
small axis. It somewhat resembled a bottle
brush, if you will suppose the hairs of the bottle
brush joining together, and forming a spiral
plane. This, turned on its axis in the air, carried
the vessel across the Seine. It is, in fact,
a screw which takes hold of the air and draws
itself along by it; losing, indeed, much of its
effort by the yielding nature of the body it lays
hold of to pull itself on by. I think it May
be applied in the water, with much greater effect
and to very useful purposes. Perhaps it
may be used also for the balloon.—
To Professor James Madison. Washington ed. i, 447.
(P.
1785)
