upward tendency, they
thought, on account of its electrical properties, which caused it to be
repelled from the ground. It is scarcely necessary now to point out
that the true cause of the upward tendency lay in the rarefaction of the
air by the heat of the fire, and that hot air has a tendency to rise
because its bulk is greatly increased beyond the same quantity of the
surrounding cold air.

Although wrong in assigning the cause of the result, they were right in
the application of it. While on a visit to Avignon Joseph Montgolfier
procured a silk bag having a small opening at its lower end, and a
capacity of about fifty cubic feet. Under the orifice some paper was
burnt; the air inside was heated and expanded so as to fill the bag,
which, when let go, soared rapidly up to the height of seventy or eighty
feet, where it remained until the air cooled and allowed it to descend.
Thus did the _first_ balloon ascend in the month of November 1782.

Delighted with their success, the indefatigable brothers resolved to
make further experiment on a larger scale. They procured a quantity of
packcloth or coarse linen, formed it into a globe about ninety feet in
circumference, lined it with paper, and lighted a fire under it in an
iron choffer. This balloon went up with a force which they estimated as
equivalent to 500 pounds.

After this the Montgolfiers appeared to have become ambitious of
accomplishing greater things, and giving to their discoveries publicity;
for we are told that, "they invited the members of the provincial
meeting of the states of the Vivarais, then assembled at Annonay, to
witness the first _public_ aerial ascent. On the 5th June 1783, amidst
a very large concourse of spectators, the spherical bag or balloon,
consisting of different pieces of linen, merely buttoned together, was
suspended from cross poles. Two men kindled a fire under it, and kept
feeding the flame with small bundles of chopped straw. The loose bag
gradually swelled, assuming a graceful form, and in the space of five
minutes it was completely distended, and made such an effort to escape
that eight men were required to hold it down.

"On a signal being given the stays were slipped, and the balloon
instantly rose with an accelerating motion till it reached some height,
when its velocity continued uniform, and carried it to an elevation of
more than a mile. All was admiration and transport. Amidst the shouts
of unbounded applause,