Ignorance, more or less complete, as to the principles and powers with
which they dealt, was, in days gone by, the cause of many of the errors
and absurdities into which men were led in their efforts to mount the
atmosphere. Our space, however, forbids further consideration of this
subject, which is undoubtedly one of considerable interest, and
encircled with a good deal of romance.

Turning away from all those early and fanciful speculations, we now come
to that period in the history of balloon voyaging, or aeronautics, when
true theories began to be philosophically applied, and ascending into
the skies became an accomplished fact.

CHAPTER TWO.

THE FIRST BALLOONS.

The germ of the invention of the balloon lies in the discovery of Mr
Cavendish, made in 1766, that hydrogen gas, called inflammable air, is
at least seven times lighter than atmospheric air. Founding on this
fact, Dr Black of Edinburgh proved by experiment that a very thin bag,
filled with this gas, would rise to the ceiling of a room.

In Dr Thomson's _History of Chemistry_, an anecdote, related by Mr
Benjamin Bell, refers to this as follows:--

"Soon after the appearance of Mr Cavendish's paper on hydrogen gas, in
which he made an approximation to the specific gravity of that body,
showing that it was at least ten times lighter than common air, Dr
Black invited a party of friends to supper, informing them that he had a
curiosity to show them. Dr Hutton, Mr Clerk of Eldin, and Sir George
Clerk of Penicuik, were of the number. When the company invited had
arrived, he took them into a room where he had the allantois of a calf
filled with hydrogen gas, and, upon setting it at liberty, it
immediately ascended and adhered to the ceiling. The phenomenon was
easily accounted for; it was taken for granted that a small black thread
had been attached to the allantois, that the thread passed through the
ceiling, and that some one in the apartment above, by pulling the
thread, elevated it to the ceiling, and kept it in its position! This
explanation was so plausible, that it was agreed to by the whole
company, though, like many other plausible theories, it turned out
wholly fallacious, for, when the allantois was brought down, no thread
whatever was found attached to it. Dr Black explained the cause of the
ascent to his admiring friends; but such was his carelessness of his own
reputation, that he never gave the least account of this curious
experi