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development of the technology to manufacture capillary glass tubes. These tubes were then
used with water and alcohol in a thermometric device resembling the bulb thermometer, and
these devices eventually led to the development of a practical temperature-measuring
instrument.
A temperature scale proposed by Gabriel D. Fahrenheit, a German physicist (1686–1736), in
1715 attempted to incorporate body temperature as the median point on a scale having 180 divisions
between the freezing point and the boiling point of water. Fahrenheit also successfully used mercury
as the liquid in a bulb thermometer, making significant improvements over the attempts of Ismael
Boulliau in 1659. In 1742, the Swedish astronomer Anders Celsius
1 (1701–1744) described a
temperature scale that divided the interval between the boiling and freezing points of water at 1 atm
pressure into 100 equal parts. The boiling point of water was fixed as 0, and the freezing point of
water as 100. Shortly after Celsius’s death, Carolus Linnaeus (1707–1778) reversed the scale so that
the 0 point corresponded to the freezing point of water at 1 atm. Even though this scale may not have
been originated by Celsius (1), in 1948 the change from degrees centigrade to degrees Celsius was
officially adopted.
As stated by H. A. Klein in The Science of Measurement: A Historical Survey (2),
From the original thermoscopes of Galileo and some of his contemporaries, the measurement of
temperature has pursued paths of increasing ingenuity, sophistication and complexity. Yet temperature
remains in its innermost essence the average molecular or atomic energy of the least bits making up
matter, in their endless dance. Matter without motion is unthinkable. Temperature is the most
meaningful physical variable for dealing with the effects of those infinitesimal, incessant internal motions
of matter.
8.2 TEMPERATURE STANDARDS AND DEFINITION
Temperature can be loosely described as the property of an object that describes its hotness
or coldness, concepts that are clearly relative. Our experiences indicate that heat transfer tends
to equalize temperature, or more precisely, systems that are in thermal communication
eventually have equal temperatures. The zeroth law of thermodynamics states that two
systems in thermal equilibrium with a third system are in thermal equilibrium with each
other. Thermal equilibrium implies that no heat transfer occurs between the systems, defining
the equality of temperature. Although the zeroth law of thermodynamics essentially provides
the definition of the equality of temperature, it provides no means for defining a
temperature scale.
A temperature scale provides for three essential aspects of temperature measurement: (1) the
definition of the size of the degree, (2) fixed reference points for establishing known temperatures,
and (3) a means for interpolating between these fixed temperature points. These provisions are
consistent with the requirements for any standard, as described in Chapter 1.
1 It is interesting to note that in addition to his work in thermometry, Celsius published significant papers on the aurora
borealis and the falling level of the Baltic Sea.
310 Chapter 8 Temperature Measurements
14:53:55 Page 310
development of the technology to manufacture capillary glass tubes. These tubes were then
used with water and alcohol in a thermometric device resembling the bulb thermometer, and
these devices eventually led to the development of a practical temperature-measuring
instrument.
A temperature scale proposed by Gabriel D. Fahrenheit, a German physicist (1686–1736), in
1715 attempted to incorporate body temperature as the median point on a scale having 180 divisions
between the freezing point and the boiling point of water. Fahrenheit also successfully used mercury
as the liquid in a bulb thermometer, making significant improvements over the attempts of Ismael
Boulliau in 1659. In 1742, the Swedish astronomer Anders Celsius
1 (1701–1744) described a
temperature scale that divided the interval between the boiling and freezing points of water at 1 atm
pressure into 100 equal parts. The boiling point of water was fixed as 0, and the freezing point of
water as 100. Shortly after Celsius’s death, Carolus Linnaeus (1707–1778) reversed the scale so that
the 0 point corresponded to the freezing point of water at 1 atm. Even though this scale may not have
been originated by Celsius (1), in 1948 the change from degrees centigrade to degrees Celsius was
officially adopted.
As stated by H. A. Klein in The Science of Measurement: A Historical Survey (2),
From the original thermoscopes of Galileo and some of his contemporaries, the measurement of
temperature has pursued paths of increasing ingenuity, sophistication and complexity. Yet temperature
remains in its innermost essence the average molecular or atomic energy of the least bits making up
matter, in their endless dance. Matter without motion is unthinkable. Temperature is the most
meaningful physical variable for dealing with the effects of those infinitesimal, incessant internal motions
of matter.
8.2 TEMPERATURE STANDARDS AND DEFINITION
Temperature can be loosely described as the property of an object that describes its hotness
or coldness, concepts that are clearly relative. Our experiences indicate that heat transfer tends
to equalize temperature, or more precisely, systems that are in thermal communication
eventually have equal temperatures. The zeroth law of thermodynamics states that two
systems in thermal equilibrium with a third system are in thermal equilibrium with each
other. Thermal equilibrium implies that no heat transfer occurs between the systems, defining
the equality of temperature. Although the zeroth law of thermodynamics essentially provides
the definition of the equality of temperature, it provides no means for defining a
temperature scale.
A temperature scale provides for three essential aspects of temperature measurement: (1) the
definition of the size of the degree, (2) fixed reference points for establishing known temperatures,
and (3) a means for interpolating between these fixed temperature points. These provisions are
consistent with the requirements for any standard, as described in Chapter 1.
1 It is interesting to note that in addition to his work in thermometry, Celsius published significant papers on the aurora
borealis and the falling level of the Baltic Sea.
310 Chapter 8 Temperature Measurements