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Celsius, A

Name: Anders Celsius

Achievements:  The Celsius (or Centigrade) temperature scale.

Born: November 27, 1701; Uppsala, Sweden

Died: April 25, 1744; Uppsala, Sweden. Aged 42

Field & Discipline: Astronomy; Astronomer

Language: Swedish

Father: Nils Celsius

Mother: Unknown

Siblings: Unknown

Spouse: Unknown

Children: Unknown

Education: Unknown

Major Work:

"Observations Concerning the Two Constant Degrees on a Thermometer" (1742)

Life & Times:

In 1725 Celsius was made secretary of the Royal Society of  Sciences in Uppsala, and the same year was appointed professor of  mathematics at the university.    He was made professor of astronomy in April 1730,  and later that year published his first major work:  “A  Dissertation on a New Method of Calculating the Distance of the Sun from the  Earth.”

In 1732 he left Sweden and travelled around Europe for four years, during which he visited almost all the main observatories of  the day, and worked with many of the leading 18th-century astronomers. He  first visited observatories in Berlin and Nuremberg, where in 1733 he  published a collection of 316 observations of the  northern lights made by himself and others from 1716 to 1732. He was the first to realize from these observations that the aurora borealis involved magnetic forces.

He then travelled to Italy and then to Paris, where in 1735 he met the mathematician and  astronomer [invited on expedition by] Maupertuis*, who was preparing an expedition to measure  an arc of meridian in the far north, with the intention of verifying the  Newtonian theory that the Earth is a sphere flattened at the poles.

Maupertuis invited Celsius to join the expedition to Lapland, and in 1735  Celsius went to London, England in order to buy the necessary  astronomical instruments from the famous clock- and instrument-maker [bought instruments from] Graham*.   The following year he accompanied the expedition to Tornea in  northern Sweden (now Tornio, Finland), and during 1736-37 he assisted with measurements in Lapland.  When  compared with the results from a similar expedition to Peru,  near the Equator,  these  confirmed the Newton theory.

On return to France, in 1738 Celsius also became involved in the controversy surrounding Maupertuis, and in Maupertuis’ defence, against attacks by [involved in row with] Cassini*,  wrote:  “Disquisition on Observations Made in France for Determining the Shape of the Earth.”

Celsius returned to Uppsala in 1739, and devoted himself to improving astronomical studies and research at the university. His involvement in the French expedition had made him internationally famous, and helped him secure from the Swedish authorities the resources necessary to build a modern observatory in Uppsala in 1741,  equipped with the most  technologically advanced instruments then available, which Celsius had  purchased during his travels.

In 1740 he published: “On the constellation Aries”, an attempt to calculate the magnitude of 300 stars in Aries using  his own photometric system (in which light from the stars is filtered  through identical glass plates;  the magnitude of the stars then measured by  the number of glass plates needed to extinguish the light), and discovered  that the brightest star in the sky, Sirius, needed 25 of his plates to be  extinguished.  He also made observations of eclipses, and published a popular mathematics textbook: “Arithmetic for Swedish Youth” (1741).

In the early 18th century, geographical and meteorological observation and  measurement were considered part of the work of an astronomer, and during  the early 1740s Celsius contributed many geographical measurements to the  Swedish National Map project. He was also the first to suggest that the landmass of the Nordic countries was slowly rising above sea level.

In 1741-42 Celsius made his most important scientific contribution, when, to aid his meteorological observations he constructed his Celsius thermometer.   The Celsius [developed] temperature scale*, also called the Centigrade temperature scale because of the 100-degree interval between the defined points, is now based on 0° for the freezing point of water and 100° for the  boiling point of water. Celsius read his famous paper on his thermometer: "Observations  Concerning the Two Constant Degrees on a Thermometer"  to the Swedish  Academy of Sciences in 1742, and it was long known as the "Swedish  thermometer", only around 1800 becoming known as the Celsius thermometer.

Extra Connections: His work related to that of [work related to] Romer* and [work related to] Fahrenheit*

Assessment:  Major contributor to accuracy in measurement of heat.

Oneliner: Anders Celsius,  Swedish thermometer inventor

Bibliography: