ngs, split-"air" turns, and stunts likely to be useful in a scrap.
For the rest, we sorted ourselves out, which pilot was to fly with which
observer, and improved the machines' accessories.

An inspiration suggested to the flight-commander, who although an
ex-Civil Servant was a man of resource, that mirrors of polished steel,
as used on the handlebars of motor-cycles, to give warning of roadcraft
at the rear, might be valuable in an aeroplane. Forthwith he screwed one
to the sloping half-strut of his top center-section. The trial was a
great success, and we bought six such mirrors, an investment which was
to pay big dividends in many an air flight.

Next the flight-commander made up his mind to bridge the chasm of
difficult communication between pilot and observer. Formerly, in
two-seaters with the pilot's seat in front, a message could only be
delivered on a slip of paper or by shutting off the engine, so that
one's voice could be heard; the loss of time in each case being ill
afforded when Huns were near. An experiment with a wide speaking-tube,
similar to those through which a waiter in a Soho restaurant demands
_cotelettes milaneses_ from an underground kitchen, had proved that the
engine's roar was too loud for distinct transmission by this means. We
made a mouthpiece and a sound-box earpiece, and tried them on tubes of
every make and thickness; but whenever the engine was at work the words
sounded indistinct as words sung in English Opera. One day a speedometer
behaved badly, and a mechanic was connecting a new length of the rubber
pitot-tubing along which the air is sucked from a wingtip to operate the
instrument. Struck with an idea, the pilot fitted mouthpiece and
earpiece to a stray piece of the tubing, and took to the air with his
observer. The pair conversed easily and pleasantly all the way to 10,000
feet. The problem was solved, and ever afterwards pilot and observer
were able to warn and curse each other in mid-air without waste of time.
The high-powered two-seaters of to-day are supplied with excellent
speaking-tubes before they leave the factories; but we, who were the
first to use a successful device of this kind on active service, owed
its introduction to a chance idea.

One by one our six war machines arrived and were allotted to their
respective pilots. Each man treated his bus as if it were an only child.
If another pilot were detailed to fly it the owner would watch the
performance jealously, a