metrographs

Noun

metrograph (plural metrographs)

1. An instrument attached to a locomotive for recording its speed and the number and duration of its stops.
   • Metrographs have been devised for counting the revolutions and speed of locomotive wheels.1880 December 3, “Watham Watch Gauge”, in English Mechanic and Mirror of Science, volume 32, page 304
2. A device used to measure the flow and velocity of liquids.
   • Represented by R.W. Sparling, and C. F. Sherwood, exhibited the Sparling line of main line meters and metrograph recording instruments.1929, Contract Record, page 803
3. Any of various devices that continuously record several meteorological phenomena; a radiosonde or one of its precursors.
   • The automatic records of the sunshine recorder, the anemometer and the wind vane, are registered on one instrument, which is called a metrograph or improved triple register.1895 October 12, “How the Weather Bureau Forecasts Storms”, in Digest: Review of Reviews Incorporating The Literary Digest, volume 11, number 24, page 703
4. A device that uses reflection holograms to accurately measure three-dimensional objects, used primarily in orthodontics.
   • With the metrograph, the hologram is fixed and the point of light can be moved in the three orthogonal directions.1986, Proceedings of the 17th International Congress on High Speed Photography and Photonics, page 270