might be made, it was considered that the keel structure and also
the cars should be made very strong in case of accidents
occurring. This, while materially increasing the strength of the
ship, added to its weight, and coupled with the fact that
modifications were made in the design, rendered the lift somewhat
disappointing. The hull structure was of the "Zahm" shape as in
No. 1, a considerable portion being parallel sided, while in
transverse section it formed a 17-sided polygon. In length it was
526 feet with a maximum diameter of 53 feet. The hull framework
was composed of triangular duralumin girders, both in the
longitudinal and transverse frames, while the bracing was carried
out by means of high tensile steel wires and duralumin tubes.
Attached to the hull was a V-shaped keel composed of tubes with
suitable wire bracings, and in it a greater part of the strength
of the structure lay. It was designed to withstand the vertical
forces and bending moments which resulted from the lift given by
the gasbags and the weights of the car and the cabin. The keel
also provided the walking way from end to end of the ship, and
amidships was widened out to form a cabin and wireless
compartment.

The wiring of the transverse frames was radial and performed
similar functions to the spokes of a bicycle wheel. These wires
could be tightened up at the centre at a steel ring through which
they were threaded and secured by nuts.

In addition to the radial wires were the lift wires) which were
led to the two points on the transverse frames which were
attached to the keel; on the inflation of the gasbags, the bags
themselves pressed upon the longitudinal girders on the top of