ry hardly existed. Until
1916, the greater proportion of our machines, and almost all our
engines, were French, and we were very dependent upon France for the
replacement of our heavy losses in material. By the end of the war the
bulk of our material was of British design and construction, though
there was still a certain number of British built engines of French
design. One American engine--the Liberty--was also employed. The fact
that in October, 1918, the Royal Air Force had 22,171 machines and
37,702 engines on charge, and that during the ten months January to
October the output of machines had been 26,685 and of engines 29,561,
gives some idea of the enormous growth in production.

In the first few months of the war it was not possible to progress far
with new inventions or improvements. Fortunately, our Aircraft Factory
had evolved in the B.E. a machine of considerable stability which in
this respect compared favourably with German machines, and was well
adapted to its work of reconnaissance.

Technical progress during the war often unfortunately involved the loss
of valuable lives, as for instance those of Professor Hopkinson and
Busk, to both of whom heavy debts of gratitude are owed, but gradually
obstacle after obstacle, problem after problem, was successfully tackled
by our designers and constructors. With a view to enlarging the field of
observation, staggered planes were introduced in the B.E.2c. This
machine also proved that it was possible to calculate the degree of
stability and thus paved the way for the design of aeroplanes with
indifference to stability and increased man[oe]uvrability for fighting
purposes, or with great inherent stability for bombing. During 1915 the
B.E.2c was used for all purposes, but the extra loading involved by the
increasing use of aeroplanes for bombing and fighting caused a decrease
in the rate of speed and climb, and our aeroplanes were temporarily
inferior in fighting power to the Fokker.

The necessity of preventing the enemy obtaining information soon led to
the development of air fighting. At the beginning of the war the sole
armament of aeroplanes was the rifle or revolver. The machine gun soon
followed, but its use in tractor machines was impracticable on account
of the danger of hitting the airscrew. The first "fighters" were
therefore two-seater pushers, such as the "Short-horn" Maurice Farmans
which, though not designed for fighting, and too slow to chase enemy