Neptunian vs hydrographic

Neptunian

adj
  • Of or pertaining to the planet Neptune. 

  • Of or pertaining to water or the sea. 

  • Of, pertaining to, or supporting Neptunism (“a discredited theory that rocks were formed from the crystallisation of minerals in the early Earth's oceans”). 

  • Pertaining to the astrological influence of the planet Neptune. 

  • Of or pertaining to Neptune, the Roman god of fresh water and the sea, the counterpart of the Greek god Poseidon. 

  • Formed by the action of water. 

noun
  • A person under the astrological influence of the planet Neptune. 

  • An (imaginary) inhabitant of the planet Neptune. 

  • A proponent of Neptunism. 

hydrographic

adj
  • Of or pertaining to hydrography. 

How often have the words Neptunian and hydrographic occurred in a corpus of books? (source: Google Ngram Viewer )