reatest weights occur. In these
strengthened transverse frames the girders, while still remaining of
the triangular section, familiar in the other ships, are placed the
opposite way round, that is, with the apex pointing outwards.

The walking way is situated at the base of the hull passing through the
gas chambers, which are specially shaped for the purpose. The corridor
is formed of a light construction of hollow wooden struts and duralumin
arches covered with netting.

In all other leading features the design of the 23 class is adhered to;
the gasbags are the same, except for the alteration due to the internal
corridor, and the system of valves and the various controls are all
highly similar.

The arrangement of gondolas and the fitting of engines in all ways
corresponds to the original arrangement of R 23, with the exception
that they were suspended closer to the hull owing to the absence of the
external keel. The substitution of the wing car of the 33 class for
the original after gondola, carried out in the modifications undergone
by the ships of the 23 class, was not adopted in these ships, as the
wireless compartment installed in the keel in the former was fitted in
the after gondola in the latter.

The disposable lift of these ships under standard conditions is 7 1/2
tons, which shows considerable improvement on the ships of the former
classes.

Summarizing as before, the performances appear as under--

Speed:
Full 56 1/2 miles per hour
Normal 53 " " "
Cruising 45 " " "

Endurance:
Normal 19 hours = 1,015 miles
Cruising 23 1/2 " = 1,050 "

The two ships of this class, which were commissioned, must be regarded
within certain limits as most satisfactory, and are the most successful
of those that appeared and were employed during the war. Escort of
convoys and extended anti-submarine patrols were carried out, and
certain valuable experiments will be attempted now that peace has
arrived.

In spite of the grave misgivings of many critics, the structure without
the keel has proved amply strong, and no mishap attended this radical
departure on the part of the designers.

RIGID AIRSHIP No. 31 CLASS

The airship known as R 81 was a complete deviation from any rigid
airship previously built in this country. In this case the experiment
was tried of constructing it in wood in accordance with the pr