solidity vs unsteadiness

solidity

noun
  • Moral firmness; validity; truth; certainty. 

  • The state or quality of being solid. 

  • The solid contents of a body; volume; amount of enclosed space. 

unsteadiness

noun
  • The quality of being unsteady. 

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