[4] He designed the craft and then worked in conjunction with the Robert brothers, Anne-Jean and Nicolas-Louis, to build it in their workshop at the Place des Victoires in Paris.

[5] The brothers invented the methodology for the lightweight, airtight gas bag by dissolving rubber in a solution of turpentine and varnished the sheets of silk that were stitched together to make the main envelope.

[4] Charles and the Robert brothers launched[6] the world's first hydrogen filled balloon on 27 August 1783, from the Champ de Mars, (now the site of the Eiffel Tower) where Ben Franklin was among the crowd of onlookers.

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 four kilometres.

[8] The balloon flew northwards for 45 minutes, pursued by chasers on horseback, and landed 21 kilometers away in the village of Gonesse where the reportedly terrified local peasants destroyed it with pitchforks[7] or knives.

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 [fr].

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.

[5] 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.

Simon Schama wrote in Citizens: Montgolfier's principal scientific collaborator was M. Charles, ... who had been the first to propose the gas produced by vitriol instead of the burning, dampened straw and wood that he had used in earlier flights.

[11] Charles chose never to fly in this craft, but 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 La Caroline.

[4][12] Charles developed several useful inventions, including a valve to let hydrogen out of the balloon and other devices, such as the hydrometer and reflecting goniometer, and improved the Gravesand heliostat and Fahrenheit's aerometer.