double boiler vs sheet

double boiler

noun
  • A large pan containing hot water, into which other smaller pans are set in order to cook food at low heat (below the boiling point) or to keep food warm. 

  • A pair of interlocking pots, the lower one filled with water which when boiling heats the contents of the upper pot. 

sheet

noun
  • A flat metal pan, often without raised edge, used for baking. 

  • A layer of veneer. 

  • A piece of paper, usually rectangular, that has been prepared for writing, artwork, drafting, wrapping, manufacture of packaging (boxes, envelopes, etc.), and for other uses. The word does not include scraps and irregular small pieces destined to be recycled, used for stuffing or cushioning or paper mache, etc. 

  • A sail. 

  • A thin bed cloth used as a covering for a mattress or as a layer over the sleeper. 

  • A thin, flat layer of solid material. 

  • A line (rope) used to adjust the trim of a sail. 

  • The area of ice on which the game of curling is played. 

  • Precipitation of such quantity and force as to resemble a thin, virtually solid wall. 

  • A broad, flat expanse of a material on a surface. 

  • An extensive bed of an eruptive rock intruded between, or overlying, other strata. 

  • The space in the forward or after part of a boat where there are no rowers. 

verb
  • To form into sheets. 

  • Of rain, or other precipitation, to pour heavily. 

  • To cover or wrap with cloth, or paper, or other similar material. 

  • To trim a sail using a sheet. 

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