water column

Noun

water column (plural water columns)

1. (environmental sciences) A notional column of water from the surface to the bottom in a natural setting, notable for the differences in physical and chemical properties at various depths.
2. (deep-sea diving) The zone in which ascent and descent occur.
3. A column alongside a railway track used to replenish a steam engine's water supply.
   • At Carlisle, as is customary, there was a very slow stop for the engine to draw to the water column.1943 January and February, Cecil J. Allen, “British Locomotive Practice and Performance”, in The Railway Magazine, page 16
   • There could be no easy reversion to the pre-electrification timetable, as that provided for working over the Hyndland branch, which no longer existed, and new stations had come into use at Hyndland and Garscadden; moreover, water columns all along the routes concerned had been removed.1961 March, “Talking of trains”, in Trains Illustrated, page 130

   Synonyms:

   water crane

4. The column of water inside the graduated cylinder of a pressure gauge that measures pressure in inches of water.