Joseph-Michel Montgolfier and Jacques-Étienne Montgolfier

Miniature on ivory, late 18th century; in the Musée Carnavalet, Paris.

Joseph-Michel Montgolfier and Jacques-Étienne Montgolfier were French brothers who were pioneer developers of the hot-air balloon and who conducted the first untethered flights. Modifications and improvements of the basic Montgolfier design were incorporated in the construction of larger balloons that, in later years, opened the way to exploration of the upper atmosphere.

(Read Orville Wright’s 1929 biography of his brother, Wilbur.)

Joseph and Étienne were 2 of the 16 children of Pierre Montgolfier, whose prosperous paper factories in the small town of Vidalon, near Annonay, in southern France, ensured the financial support of their balloon experiments. While carrying on their father’s paper business, they maintained their interest in scientific experimentation.

In 1782 Joseph-Michel Montgolfier and Jacques-Étienne Montgolfier discovered that heated air, when collected inside a large lightweight paper or fabric bag, caused the bag to rise into the air. The Montgolfiers made the first public demonstration of this discovery on June 4, 1783, at the marketplace in Annonay. They filled their balloon with heated air by burning straw and wool under the opening at the bottom of the bag. The balloon rose into the air about 3,000 feet (1,000 meters), remained there some 10 minutes, and then settled to the ground more than a mile and a half from where it rose. The Montgolfiers traveled to Paris and then to Versailles, where they repeated the experiment with a larger balloon on September 19, 1783, sending a sheep, a rooster, and a duck aloft as passengers. The balloon floated for about 8 minutes and landed safely about 2 miles (3.2 kilometers) from the launch site. On November 21, 1783, the first manned untethered flight took place in a Montgolfier balloon with Pilatre de Rozier and François Laurent, marquis d’Arlandes, as passengers. The balloon sailed over Paris for 5.5 miles (9 kilometers) in about 25 minutes.

The Montgolfiers brothers were honored by the French Académie des Sciences. They published books on aeronautics and continued their scientific careers. Joseph invented a calorimeter and the hydraulic ram, and Étienne developed a process for manufacturing vellum.