were the rule in the earlier months of the war, as most of the
machines would not climb above 4000-7000 feet. Much of the observation
was performed at something between 1000 and 2000 feet, so that aircraft
often returned with a hundred or so bullet-holes in them.

Meanwhile the important work of artillery spotting was being developed.
New systems of co-operation between artillery and aeroplanes were
devised, tested, and improved. At first lamps or Very's lights were used
to signal code-corrections, but these were soon replaced by wireless
transmission from the observation machine. Targets which could not be
ranged on through ground observation posts became targets no longer,
after one shoot ranged from the air. As the number of available aircraft
increased, so did the amount of observation for the guns, until finally
the entire front opposite the British was registered for bombardment and
divided into sections covered by specified artillery machines.

Aerial fighting, now so essential and scientific a branch of modern war,
was rudimentary in 1914. Pilots and observers of the original Flying
Corps carried revolvers, and many observers also equipped themselves
with rifles, but the aeroplanes were not fitted with machine-guns. Such
scraps as there were consisted of one machine manoeuvring round an
opponent at close quarters for the chance of a well-aimed shot. Under
these circumstances to "bring down" or "drive down out of control" an
enemy was extremely difficult, though a very gallant officer, since
killed in action, once killed two German pilots within five minutes with
his revolver.

Soon the possibilities of aerial machine-guns were quickly recognised.
The R.F.C. adopted the Lewis, which from the points of view of lightness
and handiness was well suited for aircraft, and the German airmen
countered with a modified Hotchkiss and other types.

But the stable observation machines, while excellent for reconnaissance
and artillery spotting, allowed their crews only a small arc of fire,
and not until the German single-seater scouts and our Bristol scout,
then a comparatively fast machine, appeared on the western front in the
spring of 1915 did the destruction of aeroplanes become an everyday
occurrence. With the introduction of scouts for escort and protective
duties came formation flying and concerted attack.

Fighting craft continued to increase in speed and numbers. As the
struggle became more and more intense, so di