die away vs spin down

die away

verb
  • To diminish or wane; to cease gradually. 

  • To die gradually or slowly. 

spin down

verb
  • To diminish in energy; to slow down or peter out; to be gradually canceled or ended. 

  • To reduce its speed of rotation. 

  • To reduce its spinning speed from that required for reading and writing. 

How often have the words die away and spin down occurred in a corpus of books? (source: Google Ngram Viewer )