catechism vs wringer

catechism

noun
  • A basic manual in some subject. 

  • A set of questions designed to determine knowledge. 

  • A book, in question and answer form, summarizing the basic principles of Christianity. 

wringer

noun
  • Something that causes pain, hardship, or exertion; an ordeal. 

  • One who wrings. 

  • A device for drying laundry consisting of two rollers between which the wet laundry is squeezed (or wrung); a mangle. 

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