erryboat fashion, one at each end
of the vessel. Hence, each pair of rudders was toggled together by a
cross-yoke. This was probably operated by a tiller (possibly the
cross-yokes and tillers were of iron) pivoted under the beams of the gun
deck close to the ends of the ship. Tiller ropes led from a tackle under
the gun-deck through trunks to the spar deck, where the wheels were
placed. This allowed proper sweep to the tillers and operation of each
pair of rudders. The paddle wheel was apparently of iron, with wooden
blades, and agrees with Montgery's description. In the plan for the
model it is shown raised 18 inches above the original design position,
to agree with trial requirements.

[Illustration: Figure 7.--ORIGINAL LINES OF ROBERT FULTON'S _Steam
Battery_, a Danish copy dated September 12, 1817; found in Rigsarkivet,
Copenhagen.]

It should be observed that the close CL-to-CL frame spacing created a
hull having frames touching one another, at least to above the turn of
the bilge, so the vessel was almost solid timber, before being planked
and ceiled, from keel to about the loadline. The sides are not only
heavily planked but, after the frames were ceiled with extraordinarily
heavy, square timbering, a supplementary solid, vertical framing was
introduced inboard and another ceiling added. The sides scale about 5
feet from outside the plank to the inboard face of the inner ceiling at
the level of the gunports.

The hulls were tied together athwartship by the deck beams of the gun
deck and spar deck, except in the wake of the paddle wheel. Knees were
placed along the sides of the race at alternate gun-deck beams. In
addition, the 12 1-foot-square timbers, crossing the race at the rabbets
of the hulls, (mentioned by Montgery) are shown. These must have created
extraordinary resistance, even at the low speed of this steamer. The
deck details shown are the results of reconstruction of the inboard
works.

History of Double-Hull Craft

The use of catamaran hulls, or "double-hulls," has been periodically
popular with ship designers since the time of Charles II of England. The
earliest of such vessels known in the present day were four sloops or
shallops designed 1673-1687 by Sir William Petty, who was an inventor in
the field of naval architecture and received some attention from Charles
II and from the Royal Society.

The first Petty experiment, the _Simon & Jude_, later called _Invention
I_, was launched Octob