continuum vs incessancy

continuum

noun
  • A continuous extent. 

  • The nondenumerable set of real numbers; more generally, any compact connected metric space. 

  • A continuous series or whole, no part of which is noticeably different from its adjacent parts, although the ends or extremes of it are very different from each other. 

  • A touch-sensitive strip, similar to an electronic standard musical keyboard, except that the note steps are ¹⁄₁₀₀ of a semitone, and so are not separately marked. 

incessancy

noun
  • The quality of being incessant; unceasingness. 

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