Dewar vs Dewar vessel

Dewar

noun
  • A glass or metal double-walled flask for holding a liquid without much loss or gain of heat; a vacuum bottle or thermos. Generally used for scientific purposes and in particular for cryogenic work. 

name
  • A surname from Scottish Gaelic. 

  • An unincorporated community in Black Hawk County, Iowa, United States. 

  • A city in Okmulgee County, Oklahoma, United States. 

Dewar vessel

noun
  • A type of double-walled vacuum flask with silver lining. 

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