electro-chronograph

Century Dictionary and Cyclopedia

1. n. A chronograph on which the record is made by electrical means: much used in astronomical observatories and in the laboratory for noting the precise instant or duration of transits and similar phenomena. See chronograph.

GNU Webster's 1913

1. n. (Astron. Physics) An instrument for obtaining an accurate record of the time at which any observed phenomenon occurs, or of its duration. It has an electro-magnetic register connected with a clock. See chronograph.