Background The Robert brothers were skilled engineers with a workshop at the
Place des Victoires in Paris, who worked with professor Jacques Charles to build the first usable hydrogen balloon in 1783. Charles conceived the idea that hydrogen would be a suitable lifting agent for balloons because, as a chemist, he had studied the work of his contemporaries
Henry Cavendish,
Joseph Black and
Tiberius Cavallo.
First hydrogen balloon Jacques Charles designed the hydrogen balloon and the Robert brothers invented the methodology for constructing the lightweight, airtight gas bag. They dissolved
rubber in a solution of
turpentine and
varnished the sheets of
silk that were stitched together to make the main envelope. They used alternate strips of red and white silk, but the discolouration of the varnishing/rubberising process left a red and yellow result. Jacques Charles and the Robert brothers launched their balloon, the world's first
hydrogen-filled
balloon (called
Le Globe), on 27 August 1783, from the
Champ-de-Mars (now the site of the
Eiffel Tower);
Benjamin Franklin was among the crowd of onlookers. The balloon was comparatively small, a 35 cubic-metre sphere of rubberised silk, and only capable of lifting about 9 kg. It was filled with hydrogen that had been made by pouring nearly a quarter of a tonne of sulphuric acid onto half a tonne of scrap iron. The hydrogen gas was fed into the envelope through
lead pipes; but as it was not passed through cold water, great difficulty was experienced in filling the balloon completely (the gas was hot when produced, but as it cooled in the balloon, it contracted). Daily progress bulletins were issued on the inflation; and the crowd was so great that on the 26th the balloon was moved secretly by night to the Champ-de-Mars, a distance of 4 kilometres. The balloon flew northwards for 45 minutes, pursued by chasers on horseback, and landed 21 kilometres away in the village of
Gonesse where the reportedly terrified local peasants attacked it with pitchforks or knives and destroyed it. The project was funded by a subscription organised by
Barthélemy Faujas de Saint-Fond. (destroyed in 1871)
First manned hydrogen balloon flight At 13:45 on 1 December 1783, Professor Jacques Charles (after whom the
gas balloon came to be called a
Charlière ) and the Robert brothers launched a new manned balloon from the
Jardin des Tuileries in Paris, amid vast crowds and excitement. The balloon was held on ropes and led to its final launch place by four of the leading noblemen in France, the
Marechal de Richelieu,
Marshal de Biron, the Bailiff of Suffren, and the
Duke of Chaulnes. Jacques Charles was accompanied by Nicolas-Louis Robert as co-pilot of the 380-cubic-metre, hydrogen-filled, balloon. The envelope was fitted with a hydrogen release valve and was covered with a net from which the basket was suspended. Sand ballast was used to control altitude. They ascended to a height of about 1,800 feet (550 m) and landed at sunset in
Nesles-la-Vallée after a 2-hour, 5-minute flight covering 36 km. The chasers on horseback, who were led by the Duc de Chartres, held down the craft while both Charles and Nicolas-Louis alighted. Jacques Charles then decided to ascend again, but alone this time because the balloon had lost some of its hydrogen. The balloon ascended rapidly to an altitude of approximately 3,000 metres, rising into the sunlight again, so that Charles then saw a second sunset. He began suffering from aching pain in his ears so he 'valved' to release gas, and descended to land gently about 3 km away at
Tour du Lay. Unlike the Robert brothers, Charles never flew again. They carried a barometer and a thermometer to measure the pressure and the temperature of the air, making this not only the first manned hydrogen balloon flight but also the first balloon flight to provide meteorological measurements of the atmosphere above the Earth's surface. It is reported that 400,000 spectators witnessed the launch, and that hundreds had paid one crown each to help finance the construction and receive access to a "special enclosure" for a "close-up view" of the take-off. Among the "special enclosure" crowd was
Benjamin Franklin, the diplomatic representative of the
United States of America. Also present was Joseph Montgolfier, whom Charles honoured by asking him to release the small, bright green, pilot balloon to assess the wind and weather conditions. This event took place ten days after the world's first manned balloon flight by
Jean-François Pilâtre de Rozier using a
Montgolfier brothers hot air balloon. Simon Schama wrote in
Citizens:
Attempted dirigible: the elongated balloon The next project of Jacques Charles and the brothers was to build an elongated, steerable craft that followed
Jean Baptiste Meusnier's proposals (1783–85) for a
dirigible balloon. The design incorporated Meusnier's internal
ballonnet (air cells), a rudder, and an ineffective parasol-paddle based method of propulsion. On 15 July 1784 the brothers flew for 45 minutes from
Saint-Cloud to
Meudon with M. Collin-Hullin and
Louis Philippe II, the Duke of Chartres in their elongated balloon which was called
La Caroline. It was fitted with oars for propulsion and direction, but they proved useless. The absence of a gas release valve meant that the duke had to slash the
ballonnet to prevent rupture when they reached an altitude of about 4,500 metres. On 19 September 1784 the brothers and M. Collin-Hullin flew for 6 hours 40 minutes, covering from Paris to
Beuvry near
Béthune. En route they passed over
Saint-Just-en-Chaussée and the region of
Clermont de l'Oise. This was the first flight over 100 kilometers as well as over 100 miles. ==Commemoration==