expense and delay necessitated by, perhaps, repeated "lightering,"
i.e., reduction of the cargo.

Thus, the through traffic on large rivers like the Danube, with its
repeated obstacles to navigation, such as the "iron gate," and several
sand-banks known and dreaded by bargemen, would be materially
facilitated, any necessity for unloading part of the cargo being
obviated; moreover, such a duplex vessel composed of two semi-vessels
affords the advantage of utilizing to a fuller degree the power of
traction, and one large vessel will be more convenient for traffic
than two smaller ones.

Further, the mode of construction of the semi-vessels--both ends of
which are of a similar pattern--allows of their being navigated up and
down a water channel without the necessity of turning them round;
provision having also been made for the fixing of the rudder at either
end, which would therefore merely require exchanging. This is of some
advantage in narrow river beds and canals, and applies equally to the
duplex vessel as to the single semi-vessels.

[Illustration: FIG. 1.]

[Illustration: FIG. 2.]

[Illustration: FIG. 3.]

[Illustration: FIG. 4.]

[Illustration: FIG. 5.]