The learned Franciscan friar, Roger Bacon, who lived in the
thirteenth century, seems to have thought of the possibility of
producing a contrivance that would float in air. His idea was
that the earth's atmosphere was a "true fluid", and that it had
an upper surface as the ocean has. He quite believed that on
this upper surface--subject, in his belief, to waves similar to
those of the sea--an air-ship might float if it once succeeded in
rising to the required height. But the difficulty was to reach
the surface of this aerial sea. To do this he proposed to make a
large hollow globe of metal, wrought as thin as the skill of man
could make it, so that it might be as light as possible, and this
vast globe was to be filled with "liquid fire". Just what
"liquid fire" was, one cannot attempt to explain, and it is
doubtful if Bacon himself had any clear idea. But he doubtless
thought of some gaseous substance lighter than air, and so he
would seem to have, at least, hit upon the principle underlying
the construction of the modern balloon. Roger Bacon had ideas
far in advance of his time, and his experiments made such an
impression of wonder on the popular mind that they were believed
to be wrought by black magic, and the worthy monk was classed
among those who were supposed to be in league with Satan.



CHAPTER III
The First Man to Ascend in a Balloon

The safe descent of the three animals, which has already been
related, showed the way for man to venture up in a balloon. In
our time we marvel at the daring of modern airmen, who ascend to