clock jack

noun Horology.

jack¹(def 19).

Origin of clock jack

1925–30; earlier jack of the clock-(house), jackaclock; see jack¹

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for clock jack

Historical Examples of clock jack

So he took the matter in hand and invented a clock-jack that was much better than the imported one.
Christopher and the Clockmakers
Sara Ware Bassett