water column

plural water columns

1. environmental sciencesgeographyA 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 divingThe zone in which ascent and descent occur.
3. rail transportA 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

   2 more examples

   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

   Recent acquisitions include LMS open No 7991, formerly on the Severn Valley Railway, several wagons and a swan-necked water column.

   1979 August, “Preservation Scene: Midland Railway Trust”, in Railway World, page 429

   Synonyms: water crane

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