Nautilus (Verne) from seawater) is the craft's primary power source for propulsion and other services. "Nautilus" is double-hulled, and is further separated into water-tight compartments. Its top speed is . Its displacement is submerged. In Captain Nemo's own words: "Nautilus" uses floodable tanks in order to adjust buoyancy and so control its depth. The pumps that evacuate these tanks of water are so powerful that they produce large jets of water when the vessel emerges rapidly from the surface of the water. This leads many early observers of "Nautilus" to believe that the vessel is some species of whale, or perhaps a
Jules Verne "Roman de la Science" (novel of science), which would allow him to incorporate large amounts of the factual information he so enjoyed researching in the Bibliothèque. He is said to have discussed the project with the elder Alexandre Dumas, who had tried something similar with an unfinished novel, "Isaac Laquedem", and who enthusiastically encouraged Verne's project. At the end of 1854, another outbreak of cholera led to the death of Jules Seveste, Verne's employer at the Théâtre Lyrique and by then a good friend. Though his contract only held him to a further year of service, Verne remained connected to