apropos vs therewith

apropos

adv
  • By the way. 

  • To the purpose; appropriately. 

  • Timely; at a good time. 

adj
  • Of an appropriate or pertinent nature. 

  • by the way, incidental 

prep
  • Regarding or concerning. 

therewith

adv
  • Thereupon, forthwith; with that being said or done. 

  • In addition to that; besides, moreover. 

  • With this, that or those. 

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