n the fact that the combination and separation of the
vessels can be effected, without the least disturbance of the
cargo, in a minimum of time.

It facilitates the utilization, to the highest possible extent, of the
varying conditions and dimensions of canal locks and rivers.

The transition from rivers to canals, and from larger canals to
smaller ones, is expedited by the possibility afforded of, on the
arrival at the locks, dividing the vessel in a space of a few minutes;
of passing with the semi-vessel, singly, the various smaller locks or
the shallow canal, after which the two sections may be re-combined and
navigated again as one vessel. The process of "folding up" the two
vessels will of course take longer than that of separation.

On rivers, the channels of which are interrupted by sand banks and
rapids, the same operation may be carried out, thus avoiding the
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.]

Each semi-barge on its part is also constructed of two equal
halves--which are, however, inseparable--and as there is no distinct
stem or stern, any one of these semi-vessels will fit any other
semi-vessels of the same dimensions, and can be attached to the same
by means of the coupling apparatus, and the two "folded up" into one
duplex vessel. This process does not present any