bombing aeroplane is essentially an instrument of projection. It extends “range” beyond any distance possible to a gun. The army aeroplanes of 1914 were, in 1916, mentioned by the aviators as “those old-fashioned ‘busses’.” In 1918, airmen employed similar scornful language concerning the machines of 1916. However, the range of the 1914 aeroplanes greatly excelled that of any gun; they could venture at least a hundred miles from their bases. By 1918, they were venturing two or three hundred miles; and the Allied armies planned, in the spring of 1919, to make regular raids on Berlin, some four hundred miles away.
To adopt again the terminology of artillery; as the aeroplane grew in range, so did it grow in calibre. The bombs dropped on Paris in 1914 were not much bigger than a grape-fruit; the bombs prepared for Berlin in 1919 were eight feet high and carried half a ton of explosive or gas-generating chemicals. Not only were they greater in themselves than any gun-shell, but they carried a heavier bursting-charge in proportion to their size. As you increase the calibre and range of a gun, you must increase the thickness of the steel casing which forms the shell, and correspondingly reduce the proportion of explosives or gas-forming chemical. But an air bomb—which is dropped, not fired—needs only a very thin casing. A big shell is in bulk mostly steel; an air bomb is mostly chemical. It was in shells like these that we would have packed our
