Hearson's strophometer or revolution indicator
Subtitle: secured by letters patent, dated 24th May 1873 : an instrument for showing at a glance by the position of a pointer on a graduated dial the number of revolutions per minute an engine is at the time revolving : manufactured by Elliott Brothers ...
Publisher: Elliott Brothers
Published: 1875
Place of publication: London
Language: eng
Notes: "Description of Hearson's strophometer. Reprinted from 'Engineering', February 5th, 1875"--P. 2.