sweep auxiliaries,--which position they still hold to some extent, even
in vessels of considerable burden. But as the proportions of naval
architecture enlarged, these puny instruments were thrown aside;
although the importance and necessity of some such auxiliary in the
ordinary exigencies of marine life have always been felt and it has long
been earnestly sought.

From the first successful application of steam to navigation--by Fulton,
in 1803--it was supposed to be the simplest thing in the world to
provide ships with an auxiliary motor; but the result has shown the
fallacy of this conception.

For more than twenty years steam-navigation has advanced with giant
strides, overstepping several times the limits which science had
assigned it; but the paddle-wheel, by which the agency of steam has
been applied, forms so bad an alliance with canvas, and supplies so
indifferently the requirements of a man-of-war, that it has been
impossible by this intermediary to render steam the efficient coadjutor
of sails; and it is for this reason that steam so speedily took rank
as a primary motor upon the ocean; for, in all the successful marine
applications of steam by means of the paddle, steam is the dominant
power, and sails the accessory, or almost superfluous auxiliary. It is
the screw alone, in some of its modifications, which offers the means of
a successful and economical adaptation of steam to ships of war or of
commerce; for it is susceptible of a more complete protection than, the
paddle, and of an easy and advantageous combination with canvas.

The screw-propeller, in fact, has assumed so important a part in all
naval enterprise, that it may not be without interest to trace briefly
its rise and progress to the consideration it now commands, and