Dear Sir,
I received your friendly Letter of the 7th Inst. I am glad my Letters
respecting the Aerostatic Experiment were not unacceptable. But as more
perfect Accounts of the Construction and Management of that Machine
have been and will be published before your Transactions, and from
which Extracts may be made that will be more particular and therefore
more satisfactory, I think it best not to print those Letters. I say
this in answer to your Question; for I did not indeed write them with
a view of their being inserted. Mr. Faujas de St. Fond acquainted me
yesterday that a Book on the Subject which has been long expected, will
be publish'd in a few Days, and I shall send you one of them. Enclosed
is a Copy of the _Procès verbal_ taken of the Experiment made yesterday
in the Garden of the Queen's Palace la Muette where the Dauphin now
resides which being near my House I was present. This Paper was drawn
up hastily, and may in some Places appear to you obscure; therefore I
shall add a few explanatory Observations.
This Balloon was larger than that which went up from Versailles and
carried the Sheep, &c. Its bottom was open, and in the middle of the
Opening was fixed a kind of Basket Grate in which Faggots and Sheaves
of Straw were burnt. The Air rarified in passing thro' this Flame rose
in the Balloon, swell'd out its sides, and fill'd it.
The Persons who were plac'd in the Gallery made of Wicker, and attached
to the Outside near the Bottom, had each of them a Port thro' which
they could pass Sheaves of Straw into the Grate to keep up the Flame,
& thereby keep the Balloon full. When it went over our Heads, we could
see the Fire which was very considerable. As the Flame slackens, the
rarified Air cools and condenses, the Bulk of the Balloon diminishes
and it begins to descend. If those in the Gallery see it likely to
descend in an improper Place, they can by throwing on more Straw,
& renewing the Flame, make it rise again, and the Wind carries it
farther.
_La Machine poussée par le Vent s'est dirigée sur une des Allées du
Jardin._ That is against the Trees of one of the Walks. The Gallery
hitched among the top Boughs of those Trees which had been cut and were
stiff while the Body of the Balloon lean'd beyond and seemed likely to
overset. I was then in great Pain for the Men, thinking them in danger
of being thrown out, or burnt for I expected that the Balloon being no
longer upright the Flame would have laid hold of the inside that leaned
over it. But by means of some Cords that were still attach'd to it, it
was soon brought upright again, made to descend, & carried back to its
place. It was however much damaged.
_Planant sur l'Horizon._ When they were as high as they chose to be,
they made less Flame and suffered the Machine to drive Horizontally
with the Wind, of which however they felt very little, as they went
with it, and as fast. They say they had a charming View of Paris &
its Environs, the Course of the River, &c but that they were once
lost, not knowing what Part they were over, till they saw the Dome of
the Invalids, which rectified their Ideas. Probably while they were
employed in keeping up the Fire, the Machine might turn, and by that
means they were _desorientés_ as the French call it.
There was a vast Concourse of Gentry in the Garden, who had great
Pleasure in seeing the Adventurers go off so chearfully, & applauded
them by clapping &c. but there was at the same time a good deal of
Anxiety for their Safety. Multitudes in Paris saw the Balloon passing;
but did not know there were Men with it, it being then so high that
they could not see them.
_Développant du Gaz._ That is, in plain English, _burning more straw_;
for tho' there is a little Mystery made, concerning the kind of Air
with which the Balloon is filled, I conceive it to be nothing more than
hot Smoke or common Air rarify'd, tho' in this I may be mistaken.
_Aiant encor dans leur Galerie les deux tiers de leur
Approvisionement._ That is their Provision of Straw; of which they
carried up a great Quantity. It was well that in the hurry of so
hazardous an Experiment, the Flame did not happen by any accidental
Mismanagement to lay hold of this Straw; tho' each had a Bucket of
Water by him, by Way of Precaution.
One of these courageous Philosophers, the Marquis d'Arlandes, did me
the honour to call upon me in the Evening after the Experiment, with
Mr. Montgolfier the very ingenious Inventor. I was happy to see him
safe. He informed me that they lit gently without the least Shock, and
the Balloon was very little damaged.
This Method of filling the Balloon with hot Air is cheap and
expeditious, and it is supposed may be sufficient for certain purposes,
such as elevating an Engineer to take a View of an Enemy's Army, Works,
&c. conveying Intelligence into, or out of a besieged Town, giving
Signals to distant Places, or the like.
The other Method of filling a Balloon with permanently elastic
inflammable Air, and then closing it is a tedious Operation, and
very expensive; Yet we are to have one of that kind sent up in a few
Days. It is a Globe of 26 feet diameter. The Gores that compose it
are red and white Silk, so that it makes a beautiful appearance. A
very handsome triumphal Car will be suspended to it, in which Mess^rs.
Robert, two Brothers, very ingenious Men, who have made it in concert
with Mr. Charles propose to go up. There is room in this Car for a
little Table to be placed between them, on which they can write and
keep their Journal, that is take Notes of every thing they observe, the
State of their Thermometer, Barometer, Hygrometer, &c which they will
have more Leisure to do than the others, having no fire to take Care
of. They say they have a contrivance which will enable them to descend
at Pleasure. I know not what it is. But the Expence of this Machine,
Filling included, will exceed, it is said, 10,000 Livres.
This Balloon of only 26 feet diameter being filled with Air ten times
lighter than common Air, will carry up a greater Weight than the other,
which tho' vastly bigger was filled with an Air that could scarcely be
more than twice as light. Thus the great Bulk of one of these Machines,
with the short duration of its Power, & the great Expence of filling
the other will prevent the Inventions being of so much Use, as some may
expect, till Chemistry can invent a cheaper light Air producible with
more Expedition.
But the Emulation between the two Parties running high, the Improvement
in the Construction and Management of the Balloons has already made
a rapid Progress; and one cannot say how far it may go. A few Months
since the Idea of Witches riding thro' the Air upon a Broomstick, and
that of Philosophers upon a Bag of Smoke, would have appeared equally
impossible and ridiculous.
These Machines must always be subject to be driven by the Winds.
Perhaps Mechanic Art may find easy means to give them progressive
Motion in a Calm, and to slant them a little in the Wind.
I am sorry this Experiment is totally neglected in England where
mechanic Genius is so strong. I wish I could see the same Emulation
between the two Nations as I see between the two Parties here. Your
Philosophy seems to be too bashful. In this Country we are not so much
afraid of being laught at. If we do a foolish thing, we are the first
to laugh at it ourselves, and are almost as much pleased with a _Bon
Mot_ or a good _Chanson_, that ridicules well the Disappointment of
a Project, as we might have been with its Success. It does not seem
to me a good reason to decline prosecuting a new Experiment which
apparently increases the Power of Man over Matter, till we can see to
what Use that Power may be applied. When we have learnt to manage it,
we may hope some time or other to find Uses for it, as Men have done
for Magnetism and Electricity of which the first Experiments were mere
Matters of Amusement.
This Experience is by no means a trifling one. It may be attended with
important Consequences that no one can foresee. We should not suffer
Pride to prevent our progress in Science. Beings of a Rank and Nature
far superior to ours have not disdained to amuse themselves with making
and launching Balloons, otherwise we should never have enjoyed the
Light of those glorious objects that rule our Day & Night, nor have had
the Pleasure of riding round the Sun ourselves upon the Balloon we now
inhabit.
With great and sincere Esteem, I am,
Dear Sir,
Your most obed^t
& most humble Servant,
B. FRANKLIN
Sir JOSEPH BANKS.
(POSTPONEMENT OF CHARLES' AND ROBERT'S ASCENSION.)