Passy, Nov^r 21^st, 1783

Dear Sir,

I received your friendly Letter of the 7^th 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. M^r. 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 M^r. 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.

Sir Joseph Banks.