longevously vs set in stone

longevously

adj

  • In a longevous way; with longevity; for an extended amount of time. 

set in stone

adj

  • Permanent; certain; firm. 

verb

  • To render something permanent, certain, or firm. 

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