chimneys and elsewhere rise in opposition to the force of
gravity? If so, cannot we discover this power, and apply it to
the service of mankind?"

We may imagine that such questions were in the minds of those two
French paper-makers, just as similar questions were in the mind
of James Watt when he was discovering the power of steam. But
one of the most important attributes of an inventor is an
infinite capacity for taking pains, together with great patience.

And so we find the two brothers employing their leisure in what
to us would, be a childish pastime, the making of paper balloons.
The story tells us that their room was filled with smoke, which
issued from the windows as though the house were on fire. A
neighbour, thinking such was the case, rushed in, but, on being
assured that nothing serious was wrong, stayed to watch the tiny
balloons rise a little way from the thin tray which contained the
fire that made the smoke with which the bags were filled. The
experiments were not altogether successful, however, for the bags
rarely rose more than a foot or so from the tray. The neighbour
suggested that they should fasten the thin tray on to the bottom
of the bag, for it was thought that the bags would not ascend
higher because the smoke became cool; and if the smoke were
imprisoned within the bag much better results would be obtained.
This was done, and, to the great joy of the brothers and their
visitor, the bag at once rose quickly to the ceiling.

But though they could make the bags rise their great trouble was
that they did not know the cause of this ascent. They thought,
however, that they were on the eve of some great discovery, and,