first effort, then followed the M type, which signifies "medium
sized," and also the semirigid Forlanini.

In the Forlanini type the envelope is divided into several
compartments with an internal rigid keel and to-day these ships
are of considerable size, the most modem being 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