ear _run_ contribute to the speed of vessels;
but what the consecutive lines ought to be, in order to constitute a
perfect _bow_, or what those to form the _run_, no builder has yet
exemplified by uniformity of practice, or theoretically defined.
Ship-delineators profess the art as a mystery, and arbitrary forms are
assumed as the result of science. These lines ought to be, by an axiom,
founded on a law imposed by Infinite Wisdom for the perfect guidance of
inanimate matter. Projectiles, thrown obliquely, take their flight in
convex parabolic curves, wherein resistance is overcome by a minimum of
force; and elastic surfaces obey the converse of that law in opposing
certain external influences. It is a property of conic sections that a
straight line, centred in the apex, and caused to circumscribe the
surface of the cone, will apply itself continuously to all consecutive
parabolic curves. Hence curves similar to the flight of projectiles, and
to those formed by the flection of elastic surfaces, may be described on
a large scale simply by causing a straight line or beam to revolve as on
the axis of a cone, in contact with a parabolic or elliptical section.
Thus a consecutive series of convex parabolic or elliptical curves may
be substituted in ship-building for hollow fantastical lines. The
benefits from which application are, increased velocity, capacity,
strength, buoyancy, facility of steering, ease in hard seas, and
exemption from breaking or 'hogging.'" Diagrams and explanations thereof
accompanied this concise statement of the principle.

Great interest attended the development of Lord Dundonald's inventions.
"I need hardly assure you," wrote Lord Minto, on the 4th of October, "of
the very great satisfaction I derive from the continued and increasing
success of your rotatory engine; and I shall now look with no little
impatience for further evidence of its merits in the new steam-frigate
to which it is to be applied. I am glad, also, that you have turned your
attention to the construction of steamers of war. I have never been
satisfied with the properties of these vessels, much as their
construction has undoubtedly been improved of late years. It is
certainly a difficult subject, because some of the qualities essential
to a vessel under sail can only be obtained by some deviation from the
form calculated to give the greatest speed under steam; and I consider
fair sailing po