life buoy vs salvager

life buoy

noun
  • Something that rescues one from difficulties. 

  • A buoyant object (most commonly torus-shaped) that is used as a life-saving device by keeping a person afloat. 

salvager

noun
  • A person who engages in salvage work 

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