od, the manual power provided gave but a very slow speed, and in
any wind it all the would-be airship became an uncontrolled balloon.

Henson and Stringfellow, with their light steam engines, were first to
attempt conquest of the problem of mechanical propulsion in the
air; their work in this direction is so fully linked up with their
constructed models that it has been outlined in the section dealing
with the development of the aeroplane. But, very shortly after these
two began, there came into the field a Monsieur Henri Giffard, who first
achieved success in the propulsion by mechanical means of dirigible
balloons, for his was the first airship to fly against the wind.
He employed a small steam-engine developing about 3 horse-power and
weighing 350 lbs. with boiler, fitting the whole in a car suspended from
the gas-bag of his dirigible. The propeller which this engine worked
was 11 feet in diameter, and the inventor, who made several flights,
obtained a speed of 6 miles an hour against a slight wind. The power
was not sufficient to render the invention practicable, as the dirigible
could only be used in calm weather, but Giffard was sufficiently
encouraged by his results to get out plans for immense dirigibles,
which through lack of funds he was unable to construct. When, later, his
invention of the steam-injector gave him the means he desired, he became
blind, and in 1882 died, having built but the one famous dirigible.

This appears to have been the only instance of a steam engine being
fitted to a dirigible; the inherent disadvantage of this form of motive
power is that a boiler to generate the steam must be carried, and this,
together with the weight of water and fuel, renders the steam engine
uneconomical in relation to the lift either of plane or gas-bag. Again,
even if the weight could be brought down to a reasonable amount, the
attention required by steam plant renders it undesirable as a motive
power for aircraft when compared with the internal combustion engine.

Maxim, in Artificial and Natural Flight, details the engine which he
constructed for use with his giant experimental flying machine, and his
description is worthy of reproduction since it is that of the only steam
engine besides Giffard's, and apart from those used for the propulsion
of models, designed for driving an aeroplane. 'In 1889,' Maxim says,
'I had my attention drawn to some very thin, strong, and comparatively
cheap tubes which were bein