A true visionary and one of the world's beloved authors, Jule Verne predicted numerous inventions like electric submarines and space travel long before they became technically possible.
Luckily for us, his works are now in public domain, so I suggest a set with each stamp dedicated to one of his famous novels.
1) The Mysterious Island (French: L'Île mystérieuse)
An air balloon caught in a storm
2) 20 000 Leagues Under the Seas (French: Vingt mille lieues sous les mers)
Nautilus, the submarine
3) Around the World in Eighty Days (French: Le tour du monde en quatre-vingts jours)
Can be pretty much anything. I like the picture with the mechanic globe
4) In Search of the Castaways (French: Les Enfants du capitaine Grant)
I suggest a sailing ship
5) Journey to the Center of the Earth (French: Voyage au centre de la Terre)
A whole new world under the surface of our planet
6) Around the Moon (French: Autour de la Lune)
Many options here as well: space gun, space "train", the moon itself...