coal scuttle vs coal scuttle helmet

coal scuttle

noun
  • A metal container of varying shapes, equipped with a handle for carrying coal for use on a domestic fire. 

coal scuttle helmet

noun
  • a style of soldier's helmet that looks the same as or similar to the helmet used by current Chilean soldiery, German soldiery at the end of WWI and during WWII, and Chinese soldiery during the Second Sino-Japanese War 

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