mystery tour vs slog

mystery tour

noun
  • A short-duration outing by coach to a destination that is not revealed in advance 

slog

noun
  • A long, tedious walk, or session of work. 

  • An aggressive shot played with little skill. 

verb
  • To strike something with a heavy blow, especially a ball with a bat. 

  • To work slowly and deliberately at a tedious task. 

  • To walk slowly, encountering resistance. 

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