Twenty Thousand Leagues Under the Sea of the premiere adventure novels and one of Verne's greatest works, along with "Around the World in Eighty Days" and "Journey to the Center of the Earth". The description of Nemo's ship, the "Nautilus", was considered ahead of its time, as it accurately describes features on submarines, which at the time were very primitive vessels. A model of the French submarine "Plongeur" (launched in 1863) was displayed at the 1867 Exposition Universelle, where it was studied by Jules Verne, who used it as an inspiration for the novel. The title refers to the "distance traveled" while under the sea and
Twenty Thousand Leagues Under the Sea of underwater breathing apparatus designed by Benoit Rouquayrol and Auguste Denayrouze in 1865. They designed a diving set with a backpack spherical air tank that supplied air through the first known demand regulator. The diver still walked on the seabed and did not swim. This set was called an "aérophore" (Greek for "air-carrier"). Air pressure tanks made with the technology of the time could only hold 30 atmospheres, and the diver had to be surface supplied; the tank was for bailout. The durations of 6 to 8 hours on a tankful without external supply recorded for the Rouquayrol set in