The first balloon to cross the English Channel, piloted by Jean-Pierre Blanchard and John Jeffries, was a hydrogen balloon.
The flight began near Dover, England, on 7 January 1785, and ended near Calais, France. Blanchard was a French balloonist, while Jeffries was an American physician and scientist who financed and joined the expedition.
Their balloon used hydrogen, a gas lighter than air, rather than heated air. During the crossing, the balloon lost altitude, so the men threw equipment and clothing overboard to reduce weight. They reached the French coast after a flight of roughly two and a half hours.
This event is often confused with a hot-air-balloon crossing because it belongs to the same early era of aviation. In fact, gas and hot-air balloons use different lifting methods and have different operational characteristics.