oratory vs prayer rug

oratory

noun
  • A private chapel or prayer room. 

  • Eloquence; the quality of artistry and persuasiveness in speech or writing. 

  • A Roman Catholic chapel; a building for public or private worship that is not a parish church. 

  • A Catholic church belonging to the Oratory of Saint Philip Neri. 

  • The art of public speaking, especially in a formal, expressive, or forceful manner. 

prayer rug

noun
  • A small rug on which Muslims kneel to pray. 

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