hygrometer

Yoko Ogawaの "the memory police" を読み始めました。

"The box hasn't been used for a while and it's in pretty bad shape," he continued. "The paint is peeling and the latch was so rusted it was tricky to open. But I figured it out. The instruments are all broken--no mercury in the thermometer and a bent needle on the hygrometer--but that means no one else is likely to look inside. R's wife had left the package tucked out of sight in the back, just as we agreed."

上記の2番目の文章 "The paint is peeling and the latch was so rusted..." を転記した後に読み直すと、動詞の時制が現在形と過去形が混ざっていることに気づき原典を見直したが転記ミスではありませんでした。意図的なのか、ネイティブでも間違えるのか、あるいは元の日本語がその様になっていたのを忠実に訳したのかちょっと気になりました。
さて、"hygrometer" は初めて見る単語なので辞書を見ます。

・Collins Dictionary: any of various instruments for measuring humidity: Reptiles incubators generally consist of a thermostat and hygrometer.
・Cambridge English Dictionary: a piece of equipment used to measure humidity (= how much water there is in the air): Humidity in vials was measured daily using a hand-held digital hygrometer.

簡単な言い方だと "humidity meter" ですね。