field work vs parapet

field work

noun
  • A temporary fortification in the field 

  • The collection of raw data, in the field 

parapet

noun
  • A fortification consisting of a wall. 

  • Part of a perimeter that extends above the roof. 

  • A low protective wall. 

  • Hyponym: balustrade 

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