Accommodation is provided for a wireless telegraphy operator, who
is also a gunner, his compartment being situated forward,
amidships is the pilot and abaft this seat is a compartment for
the engineer.

The engine selected was the 75 horse-power water-cooled Rolls
Royce, it being considered to be the most efficient for the
purpose. The engine is mounted upon bearers above the level of
the top of the car, and drives a four-bladed pusher propeller.

The car is suspended from an envelope of 70,000 cubic feet
capacity, and the system of rigging is similar to that in use on
all S.S. ships. The petrol is carried in aluminium tanks slung
on the axis of the envelope, identically with the system in use
on the S.S.P's. The usual elevator planes are adopted with a
single long rudder plane.

The speed of the Zero is about 45 miles per hour and the ship has
a theoretical endurance of seventeen hours; but this has been
largely exceeded in practice.

The original ship proved an immediate success, and a large number
was shortly afterwards ordered.

As time went on the stations expanded and sub-stations were
added, while the Zero airship was turned out as fast as it could
be built, until upwards of seventy had been commissioned. The
work these ships were capable of exceeded the most sanguine
expectations. Owing to their greater stability in flight and
longer hours of endurance, they flew in weather never previously