glean vs surmise

glean

verb
  • To gather information in small amounts, with implied difficulty, bit by bit. 

  • To collect what is left behind (grain, grapes, etc.) after the main harvest or gathering. 

  • To gather what is left in (a field or vineyard). 

  • To frugally accumulate resources from low-yield contexts. 

noun
  • A collection made by gleaning. 

surmise

verb
  • To imagine or suspect; to conjecture; to posit with contestable premises. 

noun
  • Thought, imagination, or conjecture, which may be based upon feeble or scanty evidence; suspicion; guess. 

  • Reflection; thought; posit. 

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