breastgirth vs breaststrap

breastgirth

noun

  • An oblong application supporting the mammaries of a human female 

  • A piece of horse tack for preventing the saddle to slip backwards. 

breaststrap

noun

  • An oblong application supporting the mammaries of a human female 

  • A piece of horse tack for preventing the saddle from slipping backwards. 

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