be used to any extent for commercial flying, or even flying
for sport. It is expensive, very wasteful of gasolene and oil, and
difficult to keep in repair.

For men who may have had some experience in the assembly of airplanes
at factories, or of rigging them at flying-fields, there is great
opportunity. Expert riggers who know their craft are few and hard to
get. They are invaluable for maintaining a machine in flying
condition. The use of airplanes in this country will require men for
rigging, for truing up the wires and struts. Each airplane must be
overhauled after a few hours of flight to discover hidden weaknesses
and to tighten sagging wires.

Rigging an airplane has some resemblance to rigging a ship for
sailing. The first requisite is to see that the machine is properly
balanced in flying position. There is a number of minute measurements
which come with the blue-print of every machine and which must be
followed out to the letter to get the most successful results. An
important detail is the pitch of the planes, or the angle of
incidence, as it is called. This is the angle which a plane makes with
the air in the direction of its motion. Too great a pitch will slow up
the machine by offering too great a resistance to the air; too small
an angle will not generate enough lift. The tail plane must be
attached with special care for its position. Its angle of incidence
must exactly balance the plane, and it must be bolted on so that there
is no chance of it cracking off under strain.

Radio operators will be in great demand for flying. Brig.-Gen. A.C.
Critchley, the youngest general officer in the British service, who
was a pilot in the Royal Air Force, said that the future development
of the airplane must go hand in hand with the development of wireless
communication. He added that the most difficult thing about flying,
especially ocean flying, was to keep the course in heavy weather.
There are no factors which will help a man on "dead" reckoning; and a
shift in wind, unknown to the navigator of a plane, will carry him
hundreds of miles from his objective. The wireless telephone was used
to some extent during the war for communication between the ground and
the air; it will be used to a greater extent in the next few years.

Another development which is being used by the navigators flying the
Atlantic is the radio compass. This instrument may be turned toward a
land or sea wireless station, of which the call is