tead of keeping it shut and to
counteract this the spring of the valve is inside the envelope. The
springs are set to open at a pressure of 25 to 28 mm.

Two gas valves are also fitted, one on the top of the envelope, the
other at the bottom. The bottom gas valve spring is set to open at 30
to 35 mm. pressure, the top valve is hand controlled only.

These valves are all very similar in design. They consist of two
wooden rings, between which the envelope is gripped, and which are
secured to each other by studs and butterfly nuts. The valve disc, or
moving portion of the valve, is made of aluminium and takes a seating
on a thin india rubber ring stretched between a metal rod bent into a
circle of smaller diameter than the valve opening and the wooden ring
of the valve. When it passes over the wooden ring it is in contact
with the envelope fabric and makes the junction gastight. The disc is
held against the rubber by a compressed spring.

The valve cords are led to the pilot's seat through eyes attached to
the envelope.

The system of rigging or car suspension is simplicity itself and is
tangential to the envelope. On either side there are six main
suspensions of 25 cwt. stranded steel cable known as "C" suspensions.
Each "C" cable branches into two halves known as the "B" bridles, which
in turn are supported at each end by the bridles known as "A." The
ends of the "A" bridles are attached to the envelope by means of Eta
patches. These consist of a metal D-shaped fitting round which the
rigging is spliced and through which a number of webbing bands are
passed which are spread out fanwise and solutioned to the envelope. It
will thus be seen that the total load on each main suspension is
proportionally taken up by each of the four "A" bridles, and that the
whole weight of the car is equally distributed over the greater part of
the length of the envelope. Four handling guys for manoeuvering the
ship on the ground are provided under the bow and under the stem. A
group of four Eta patches are placed close together, which form the
point of attachment for two guys in each case. The forward of these
groups of Eta patches forms the anchoring point. The bridle,
consisting of 25 cwt. steel cable, is attached here and connected to
the forepart of the skids of the car. The junction of this bridle with
the two cables from the skids forms the mooring point and there the
main trail rope is attached. This is 120 feet l