Webster’s Revised Unabridged Dictionary · 1913
Hydroscope
Hy′dro·scope (hī′drō·skōp), n. [Hydro-, 1 + -scope.] 1. An instrument designed to mark the presence of water, especially in air. Weale.
2. A kind of water clock, used anciently for measuring time, the water tricking from an orifice at the end of a graduated tube.