assing moments,
is to give sudden and great buoyancy to the balloon. An admirable
opportunity for fairly estimating the dynamic effect of the sun's rays
on a silk globe, whose fabric was half translucent, was offered to
the French aeronauts when their balloon was spread on the grass under
repair, and for this purpose inflated with the circumambient air by
means of a simple rotatory fan. The sun coming out, the interior of
the globe quickly became suffocating, and it was found that, while the
external temperature recorded 77 degrees, that of the interior was in
excess of 91 degrees.

CHAPTER XVII. ADVENTURE AND ENTERPRISE.

A balloon which has become famous in history was frequently used in the
researches of the French aeronauts mentioned in our last chapter. This
was known as "The Giant," the creation of M. Nadar, a progressive and
practical aeronaut, who had always entertained ambitious ideas about
aerial travel.

M. Nadar had been editor of L'Aeronaut, a French journal devoted to the
advancement of aerostation generally. He had also strongly expressed
his own views respecting the possibility of constructing air ships that
should be subject to control and guidance when winds were blowing. His
great contention was that the dirigible air ship would, like a bird,
have to be made heavier than the medium in which it was to fly. As he
put it, a balloon could never properly become a vessel. It would only
be a buoy. In spite of any number of accessories, paddles, wings, fans,
sails, it could not possibly prevent the wind from bodily carrying away
the whole concern.

After this strong expression of opinion, it may appear somewhat strange
that such a bold theoriser should at once have set himself to construct
the largest gas balloon on record. Such, however, was the case and the
reason urged was not otherwise than plausible. For, seeing that a vast
sum of money would be needed to put his theories into practice, M.
Nadar conceived the idea of first constructing a balloon so unique and
unrivalled that it should compel public attention in a way that no other
balloon had done before, and so by popular exhibitions bring to his
hand such sums as he required. A proper idea of the scale of this
huge machine can be easily gathered. The largest balloons at present
exhibited in this country are seldom much in excess of 50,000 cubic
feet capacity. Compared with these the "Great Nassau Balloon," built by
Charles Green, which has b