Adjustable cistern barometer

{
  "id": "MLC-T-MET-003308",
  "term": "Adjustable cistern barometer",
  "field": "Meteorology and atmospheric science",
  "definition": "A mercury barometer featuring a reservoir, or cistern, with a flexible base that can be moved by an adjusting screw. Before each measurement, the screw is turned to bring the surface of the mercury in the cistern into exact contact with a fixed reference pointer, the zero point of the instrument's scale. This procedure compensates for the change in the cistern's mercury level as the column in the glass tube rises or falls, yielding a highly accurate pressure reading.",
  "see_also": [
    "Fortin barometer"
  ],
  "url": "https://mlchart.com/terminology/meteorology/adjustable-cistern-barometer/"
}