riffle vs sluice box

riffle

noun
  • A trough or sluice having cleats, grooves, or steps across the bottom for holding quicksilver and catching particles of gold when auriferous earth is washed. Also one of the cleats, grooves or steps in such trough. 

  • A succession of small waves. 

  • A swift, shallow part of a stream causing broken water. 

  • A quick skim through the pages of a book. 

  • In seal engraving, a small metal disc at the end of a tool. 

  • The act of shuffling cards; the sound made while shuffling cards. 

verb
  • To ruffle with a rippling action. 

  • To skim or flick through the pages of a book. 

  • To flow over a swift, shallow part of a stream. 

  • To shuffle playing cards by separating the deck in two and sliding the thumbs along the edges of the cards to mix the two parts. 

  • To leaf through rapidly. 

  • To idly manipulate objects with the fingers. 

  • To prepare samples of material using a riffler. 

sluice box

noun
  • A box with riffles along the bottom, used to trap heavier gold particles as water washes them and the other material along the box. 

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