Parachute
a device by which a descent is made from a balloon or an eminence. It is a light structure, and affords a large area of resistance to the atmosphere. It is usually in shape like an umbrella, 20 to 25 feet in diameter.
It remains closed like an umbrella while the balloon to which it is attached is ascending, opening as soon as the descent begins, the expanded top serving to moderate its velocity. It was sometimes used by aviators during the World War (1914-1918) to escape from damaged aeroplanes.
Every observation balloon used in the war was equipped with parachutes.