Three years before the Revolution, Testu-Brissy, a new aeronaut, gave himself the title of physicist and announced plans for a twenty-four hour balloon flight, using a hydrogen balloon with oars similar to Jean-Pierre Blanchard.He also described his first ascent, thus:[4] The first ascent by Testu-Brissy took place on June 18, 1786, at 4.50 pm, from the Jardin du Luxembourg to the plain of Montmorency, Val-d'Oise (approximately 15 kilometres (9.3 mi) north).

He then set off again and landed around 8 pm between Écouen and Wariville (near Litz, Oise circa 45 kilometres (28 mi) north).On 18 June 1786[dubious – discuss] he flew for 11 hours and made the first electrical observations as he ascended into thunderclouds.

He also experienced Saint Elmo's Fire, a phenomenon in which luminous plasma is created by a corona discharge from a rod-like object in an atmospheric electric field.

Thus on 26 Vendémiaire of year VII (in the French Republican calendar : Autumn, 26 Grape harvest, equivalent to October 17th, 1798) Testu-Brissy performed an equestrian balloon ascent which has remained famous.

He had built an elongated balloon to carry a large rectangular wooden platform where he sat astride his horse without it being tethered.