Six's thermometer

Six’s thermometer

ZIMSEC O Level Geography Notes: Temperature

  • The daily maximum and minimum temperatures are measured using Six’s thermometer (pictured above).
  • It was invented by James Six a British scientist hence the name Six’s thermometer.
  • It is also known as the Maximum and Minimum thermometer.
  • It is housed in a Stevenson’s screen.
  • Diurnal range is the difference between the maximum and minimum temperatures.

How it works

  • When temperature rises it pushes the alcohol in the left hand limp down and forces mercury in the right hand limp up.
  • The alcohol heats up and part of it is vaporized to occupy the conical bulb.
  • The reading is taken on the right hand limp  which is in the left hand limp contracts and some of the alcohol in the conical bulb liquefies so that the mercury flows in the opposite direction.
  • The minimum temperature is read just above the metal index on the right hand limp.

Common problems encountered when using the instrument

  • Failing to identify mercury or alcohol.
  • Failure to identify the maximum and minimum thermometer.
  • Reading errors for example taking the measurement of the maximum thermometer above the metal index and that of the minimum thermometer below the index.

Digital thermometers are becoming more and more common. They are not necessarily more accurate than the traditional mercury and alcohol thermometers but they are easier to read.

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