The motor in the _Ville de Paris_ was at the front of the car, the
operator behind it. This car had the excessive weight of nearly 700
pounds. The _Patrie_ employed a non-combustible shield over the motor,
for the protection of the envelope: its steering wheel was in front and
the motor about in the middle of the car. The gasoline tank was under
the car, compressed air being used to force the fuel up to the motor,
which discharged its exhaust downward at the rear through a spark
arrester. Motors have battery and magneto ignition and decompression
cocks, and are often carried on a spring-supported chassis. The
interesting _Parseval_ propeller has four cloth blades which hang limp
when not revolving. When the motor is running, these blades, which are
weighted with lead at the proper points, assume the desired form.
Balloons usually carry guide ropes at head and stern, the aggregate
weight of which may easily exceed a hundred pounds. In descending, the
bow rope is first made fast, and the airship then stands with its head
to the wind, to be hauled in by the stern rope. For the large French
military balloons, this requires a force of about thirty men. The
_Zeppelin_ descends in water, being lowered until the cars float, when
it is docked like a ship (see page 84). Landing skids are sometimes
used, as with aeroplanes.
The balloon must have escape valves in the main envelope and ballonets.
In addition it has a "rip-strip" at the bottom by which a large cut
can be made and the gas quickly vented for the purpose of an emergency
descent. Common equipment includes a siren, megaphone, anchor pins,
fire extinguisher, acetylene search light, telephotographic apparatus,
registering and indicating gages and other instruments, anemometer,
possibly carrier pigeons; besides fuel, oil and water for the motor,
and the necessary supplies for the crew. The glycerine floated compass
of Moisant must now also be included if we are to contemplate genuine
navigation without constant recourse to landmarks.