These rare Great Western Railway water tank level indicators are very scarce indeed, used in signal boxes to indicate to the signalman the lever of water in the large elevated tanks which supplied a number of water cranes around the station site such as Kemble or Pilning High Level. At Pilning for example water was pumped into the tank from a nearby Rhine (drainage ditch), when the water level was low a bell would ring in the box and the indicator show LOW, the signalman would go to the pumphouse and start the large "Blackstone" oil engine which drove the pump. This indicator is a first class example of one of these rare instruments and this was made in house by the G.W.R. , complete and in full working order this is a great addition to a rare instrument collector.
