ferrule vs sprag

ferrule

verb
  • To equip with a ferrule. 

noun
  • The plastic band attaching the tip to the cue. 

  • The pinched metal band which holds the bristles of a paintbrush to the shaft. 

  • The metal spike at the end of the shaft of an ice axe. 

  • A band or cap (usually metal) placed around a shaft to reinforce it or to prevent splitting. 

  • A bushing for securing a pipe joint. 

  • A metal sleeve placed inside a gutter at the top. 

sprag

verb
  • To prop or sustain with a sprag. 

  • To check the motion of, as a carriage on a steep slope, by putting a sprag between the spokes of the wheel. 

noun
  • A billet of wood; a piece of timber, a similar solid object or constructed unit used as a prop. 

  • A young salmon. 

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