Jerusalem cross vs Maltese cross

Jerusalem cross

noun
  • A flowering plant Lychnis chalcedonica (syn. Silene chalcedonica) of the family Caryophyllaceae 

  • a cross variant consisting of a large cross potent surrounded by four smaller Greek crosses, one in each quadrant. 

Maltese cross

noun
  • A flowering plant Lychnis chalcedonica (syn. Silene chalcedonica) of the family Caryophyllaceae 

  • A cross having four equal arms resembling arrowheads joined at the points 

  • Synonym of Geneva wheel 

  • A position on the rings where the gymnast's body is horizontal and straight, with arms to the side; a horizontal planche. 

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