candleholder vs rush candle

candleholder

noun
  • A device for holding one or more lit candles 

  • A person who holds a candle to assist another person who is working in dim light. 

rush candle

noun
  • A candle of tallow or wax that uses a piece of rush as a wick. 

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