1869 E. A. Inglefield in 12 489 To prevent the probability of a similar occurrence, I constructed a revolution indicator... Thus there was constantly presented to the eye of the Officer on deck..a distinct signal, showing the number of revolutions at which the engines were working.
1922 14 754/3 They can now supply..revolution indicators..air sextants, [etc.].
2005 J. A. Barber iii. 52 When a specific speed is desired, the exact number of revolutions to be made [per minute] is indicated on the revolution indicator.