larly in the case
of a cargo of loose grain or other loose produce, the same must be
prevented from being upset by a kind of wooden casing.

Two semi-vessels loaded with different cargoes may be coupled
together, provided that there is not too much difference between their
respective draughts. Slight differences may be balanced by the water
compartments being filled to a greater or smaller extent.

The peculiar position of the hatches allows of loading the
semi-vessels separately as well as when coupled together.

If there is for the time being no necessity for using the vessels in
their capacity of separate and duplex barges, any kind of cargo might
be loaded that does not require large hatches.

The vessels, on account of their more complicated construction, will
be somewhat more expensive, but wherever the advantage offered by them
outweighs the extra expenditure, they can be used with success.

The innovation might be of particular importance where a new canal
system is being constructed, since the latter might be subdivided into
main canals and branch canals--similarly as in the case of ordinary
and narrow gauge railways--the main canal being built of a larger
section and with larger locks to suit the duplex barges, while the
branch canals could be planned of smaller dimensions calculated to
suit the semi-barge. Thus the first cost of such a canal system would
be materially reduced as compared with a canal installation of one
uniform section throughout.

Likewise in mountainous districts with rock soil it would be an
important consideration whether a canal had to be blasted out of the
solid rock or a tunnel cut, in dimensions suitable for a vessel of 6
or of 14 square meters section below the water line.

In this case, even in certain portions of a main canal--where rendered
desirable by the rocky nature of the ground--a smaller section might
be adopted, which would only be large enough for single semi-barges,
so that the duplex vessel would in these instances have to be taken
apart in the same way as in a branch canal.

The saving to be effected by constructing a canal on this principle,
as compared with a canal of one uniform section throughout, must be
considerable, and the advantages of the arrangement are apparent.

The appended figures will further illustrate the arrangement. Fig. 1
shows two separate semi-barges ready to pursue their journey
independently. Fig. 2 shows two semi-barges coupled toget