The Thermometer
Temperature is most commonly measured with a thermometer. A
thermometer is a sealed narrow glass tube that has no air inside, with a bulb in
the bottom containing liquid (Engelbert, 1997, p. 385). The liquid is usually
mercury, or a red-dyed alcohol (Engelbert, 1997, p. 385).
When the air is warmed, the liquid expands and crawls upward through a
small opening from the bulb into the tube (Engelbert, 1997, p. 385). When the
air is cooled, it does the opposite and drops to a lower level of the tube
(Engelbert, 1997, p. 385). There are small markings on the outside of the tube
which indicate the degree to which the liquid has risen or fallen, essentially
providing you with the temperature.
thermometer is a sealed narrow glass tube that has no air inside, with a bulb in
the bottom containing liquid (Engelbert, 1997, p. 385). The liquid is usually
mercury, or a red-dyed alcohol (Engelbert, 1997, p. 385).
When the air is warmed, the liquid expands and crawls upward through a
small opening from the bulb into the tube (Engelbert, 1997, p. 385). When the
air is cooled, it does the opposite and drops to a lower level of the tube
(Engelbert, 1997, p. 385). There are small markings on the outside of the tube
which indicate the degree to which the liquid has risen or fallen, essentially
providing you with the temperature.
A Brief History
Galileo Galilei invented
the first thermometer in 1593 ("HowStuffWorks "Thermometer"", 2009). Galileo referred to his instrument as a thermoscope which consisted of an air-filled glass bulb with a narrow glass tube, the
end of which was open and immersed in a container of colored water ("HowStuffWorks
"Thermometer"", 2009). Variations in the temperature of the air in the bulb caused the water
to rise or fall in the tube, on which a scale was marked ("HowStuffWorks
"Thermometer"", 2009). The mercury thermometer was not invented until 1714 by the German
physicist Gabriel Fahrenheit ("HowStuffWorks
"Thermometer"", 2009).
the first thermometer in 1593 ("HowStuffWorks "Thermometer"", 2009). Galileo referred to his instrument as a thermoscope which consisted of an air-filled glass bulb with a narrow glass tube, the
end of which was open and immersed in a container of colored water ("HowStuffWorks
"Thermometer"", 2009). Variations in the temperature of the air in the bulb caused the water
to rise or fall in the tube, on which a scale was marked ("HowStuffWorks
"Thermometer"", 2009). The mercury thermometer was not invented until 1714 by the German
physicist Gabriel Fahrenheit ("HowStuffWorks
"Thermometer"", 2009).