Definition of "indagator"

For that, being the number of the Elements, Principles, or Materiall Ingredients of Bodies, is an enquiry whole truth is of that Importance, and of that Difficulty, that it may as well deserve as require to be searched into by such skilfull Indagators of Nature as your selves.

1661, Robert Boyle, The Sceptical Chymist, pages 5–6