he fact that it was he
who first adopted the use of coal gas in his calling. This, it will be
remembered, was in 1821, and it should be borne in mind that at that
time household gas had only recently been introduced. In point of fact,
it first lighted Pall Mall in 1805, and it was not used for the general
lighting of London till 1814.

We are not surprised to find that the great aeronaut at one time
turned his attention to the construction of models, and this with no
inconsiderable success. A model of his was exhibited in 1840 at the
Polytechnic Institution, and is described in the Times as consisting of
a miniature balloon of three feet diameter, inflated with coal gas. It
was acted on by fans, which were operated by mechanism placed in the
car. A series of three experiments was exhibited. First, the balloon
being weighted so as to remain poised in the still air of the building,
the mechanism was started, and the machine rose steadily to the ceiling.
The fans were then reversed, when the model, equally gracefully,
descended to the floor. Lastly, the balloon, with a weighted trail rope,
being once more balanced in mid-air, the fans were applied laterally,
when the machine would take a horizontal flight, pulling the trail rope
after it, with an attached weight dragging along the floor until
the mechanism had run down, when it again remained stationary. The
correspondent of the Times continues, "Mr. Green states that by these
simple means a voyage across the Atlantic may be performed in three or
four days, as easily as from Vauxhall Gardens to Nassau."

We can hardly attribute this statement seriously to one who knew as well
as did Green how fickle are the winds, and how utterly different are the
conditions between the still air of a room and those of the open sky.
His insight into the difficulties of the problem cannot have been less
than that of his successor, Coxwell, who, as the result of his own
equally wide experience, states positively, "I could never imagine a
motive power of sufficient force to direct and guide a balloon, much
less to enable a man or a machine to fly." Even when modern invention
had produced a motive power undreamed of in the days we are now
considering, Coxwell declares his conviction that inherent difficulties
would not be overcome "unless the air should invariably remain in a calm
state."

It would be tedious and scarcely instructive to inquire into the various
forms of flying machines that