Thermometer and Temperature Scales
(historical perspectives of thermoscopes to thermometers: Daniel Fahrenheit, Galileo Galilei, Anders Celsius, and Lord Kelvin; among others, were major contributors to temperature calculations as we know them today)
"These "Florentine thermometers" were not very consistent nor accurate and were only roughly calibrated."
"In 1695, Guillaume Amontons, designed a thermometer using a glass tube filled with compressed air and then topped off with a level of mercury."
"Leopoldo's design was later improved and modified to use distilled wine."
"Leopoldo's design was later improved and modified to use distilled wine."
"The thermoscopes were notoriously inaccurate, because they were subject to changes in air pressure."
"Fahrenheit's scale was widely accepted and then partially superseded by the introduction of the 100-point scale suggested by Anders Celsius (1701-1744) in 1741."
". . . it was later realized that the phenomenon of changing air pressure had accounted for the variations in temperature readings in the open thermoscopes."
"A century later, in 1848, William Thompson proposed a temperature scale that would start at absolute zero but would use the same degree spacing as the centigrade scale."
". . . it was later realized that the phenomenon of changing air pressure had accounted for the variations in temperature readings in the open thermoscopes."
Thermoscopes to Thermometers
Daniel Gabriel Fahrenheit (1686-1736) invented the first accurate mercury thermometer in 1724 and developed the first widely used scale of temperature.
Fahrenheit was of German ancestry, born in Danzig (Gdansk, now in Poland) and he was reared in Holland where he did most of his work, and he is usually identified as Dutch (or German)
Galileo Galilei (1564-1642) and others had developed prior thermometers or thermoscopes in 1592 and later. The thermoscopes were glass tubes open at one end, partially filled with water or alcohol-water combinations.
The thermoscopes were notoriously inaccurate, because they were subject to changes in air pressure. Later Duke Ferdinand II (1611-1670) of Tuscany and Cardinal Leopoldo de Medici (1617-1675) both developed in about 1654, a closed glass thermometer, and it was later realized that the phenomenon of changing air pressure had accounted for the variations in temperature readings in the open thermoscopes.
Fahrenheit was the first to show that the boiling point of liquids varies at different atmospheric pressures, and suggested this as a principle for the construction of barometers or instruments for measuring atmospheric pressure, used especially in weather forecasting.
Leopoldo's design was later improved and modified to use distilled wine. These "Florentine thermometers" were not very consistent nor accurate and were only roughly calibrated. Different scientists working with such thermometers were frustrated in effort to communicate their experiments, because of the various scales of temperature employed.
In 1695, Guillaume Amontons (1663-1705), a French natural scientist, designed a thermometer using a glass tube filled with compressed air and then topped off with a level of mercury.
In 1708, Fahrenheit developed and suggested the wide use of a scale linked to the melting point of ice and the temperature of the human body. After experimenting with different temperature scales, he settled on 32 degrees for freezing water, 96 degrees for human temperature, and 212 degrees for boiling water.
Fahrenheit made further corrections of his scales using the same freezing and boiling points but he adjusted the scale in between so that the normal human temperature was established at 98.6 degrees as it is today.
Fahrenheit's scale was widely accepted and then partially superseded by the introduction of the 100-point scale suggested by Anders Celsius (1701-1744) in 1741. Celsius proposed that the boiling point of water be set at zero degrees and the freezing point at 100 degrees.
After his death, Carolus Linneaus (born Carl von Linné, 1707-1778) and others proposed inverting the scale, and the "centigrade scale" was introduced in about 1747.
A century later, in 1848, William Thompson (Lord Kelvin) (1824-1907) proposed a temperature scale that would start at absolute zero but would use the same degree spacing as the centigrade scale.
In 1948, the centigrade scale was renamed the Celsius scale in honor of the man who developed it.
For more than 200 years, the scale Anders Celsius devised was called centigrade, but in 1948 scientists honored him by renaming it Celsius.
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