By the second century BC, the Chinese were making miniature hot-air balloons using eggshells. A book written at that time, The Ten Thousand Infallible Arts of the Prince of Huai-Nan, mentions this pastime: "Eggs can be made to fly in the air by the aid of burning tinder."
| An ancient commentary added to the text explains
further: "Take an egg and remove the contents from the shell, then ignite
a little mugwort tinder inside the hole so as to cause a strong air current:
The egg will of itself rise in the air and fly away." Mugwort
(Artemisia vulgaris) is a very common weed, the long, dried
stalks of which were used in China as tinder for lighting fires, and powdered
as a flammable element in incense sticks.