The Collaborative International Dictionary
Hygrograph
Hygrograph \Hy"gro*graph\, n. [Gr. ? wet + -graph.] (Physics) An instrument for recording automatically the variations of the humidity of the atmosphere.
Wiktionary
hygrograph
n. Any of several forms of automated hygrometer that record humidity.
Usage examples of "hygrograph".
Besides these instruments we have a hygrograph -- we are well supplied.