over 600,000 cubic feet capacity. During
the war, Italian airships were developed on entirely dissimilar lines
to those in other countries. Both we and our Allies, and to a great
extent the Germans, employed airships exclusively for naval operations;
on the other hand, the Italian ships were utilized for bombing raids in
conjunction with military evolutions.

For this reason height was of primary importance and speed was quite a
secondary consideration, owing to the low velocity of prevailing winds
in that country. Flights were never of long duration compared with
those carried out by our airships. Height was always of the utmost
importance, as the Italian ships were used for bombing enemy towns and
must evade hostile gunfire. For this reason weight was saved in every
possible manner, to increase the height of the "ceiling."

In addition to the types already mentioned, three other varieties have
been constructed since the war--the Usuelli D.E. type and G class. The
G class was a rigid design which has not been proceeded with, and, with
this single exception, all are of a semirigid type in which an
essentially non-rigid envelope is reinforced by a metal keel. In the
Forlanini and Usuelli types the keel is completely rigid and assists in
maintaining the shape of the envelopes, and in the Forlanini is
enclosed within the envelope. In the other types the keel is in
reality a chain of rigid links similar to that of a bicycle. The form
of the envelope is maintained by the internal pressure and not by the
keel, but the resistance of the latter to compression enables a lower
pressure to be maintained than would be possible in a purely non-rigid
ship.

The M type ship is of considerable size, the P smaller, while the D.E.
is a small ship comparable to our own S.S. design. The review of these
three countries brings the early history of airships to a conclusion.
Little of importance was done elsewhere before the war, though
Baldwin's airship is perhaps worthy of mention. It was built in
America in 1908 by Charles Baldwin for the American Government. The
capacity of the envelope was 20,000 cubic feet, she carried a crew of
two, and her speed was 16 miles per hour. She carried out her trial
flight in August, 1908, and was accepted by the American military
authorities. During the war both the naval and military authorities
became greatly interested in airships, and purchased several from the
French and English. In a