Anders Celsius

Everyone living is Sweden and for that matter many people in the rest of the world have occasion every day to recall the last name of an Uppsala University natural scientist who was born in Uppsala in 1701 and was named Anders Celsius. It is when we want to know how warm it is outdoors or indoors and look at our thermometers that often include the letter C, which stands for Celsius.

Portrait of Anders Celsius
Lithograph probably after oil painting by Olof Arenius (1700-1766). The lithograph is part of Uppsala University's art collection

The celisus temperature scale

He did not invent the thermometer. It had been known for more than a century, in our country as well. Fahrenheit and Réamur had preceded Celsius, and there had been other proposals as well. But in 1741 he constructed a thermometer that was superior in its precision. It had a scale of 100 degrees, with 0 for the boiling point of water and 100 for its freezing point. A few years after it started to be used, Celsius died (1744). The centigrade scale was then reversed, and the thermometer as we know it today was created. It has been claimed that it was Linnaeus who lay behind this reform, but it was probably one of the Royal Swedish Academy of Science’s instrument-makers that came up with the idea.

The observatory

However, Anders Celsius was not primarily a meteorologist but rather an astronomer. In 1730 he was appointed to the professorial chair in the subject. This science had been on the decline in Sweden. But Sten Lindroth wrote about Celsius: ‘He immediately filled the office with living content and undertook astronomical observations with the poor instruments that were available.’ It was a matter of creating an observatory in Uppsala; the old one had been destroyed in the Great Fire of 1702. Celsius made use of and rebuilt a building on Svartbäck Street. It was suitably furnished for astronomy, and, as he was very good at begging, it was also equipped with modern instruments.

The observatory was ready in 1741. The building can still be seen on Svartbäcksgatan. It stands out because is situated at an angle. When the streets were regulated in the 1640s the original house had been allowed to stand where it was, to the credit of the city planners of the day. Celsius lived in the building himself, and since he was a lifelong bachelor, he did not need more space.

An old picture of the Celsius building when it used to be an observatory, next to a picture of the building today. The old picture has a tower that the new is missing.
The Celsius House then and now. The lower part of the house is preserved and is situated on Svarbäcksgatan, next to St. Per Gallerian.

The greatest inspiration

He belonged to a famous learned family. His father, Nils Celsius, was named professor of mathematics but is best known as headmaster of the ‘Trivial’ School in Uppsala. Anders studied at his hometown university and excelled there. But he imbibed the greatest inspiration for his activities during a four-year journey in Germany and Italy, with a side trip to Paris. He was already a professor at the time.

The measurment of degrees in Tornedalen

Otherwise, Newton’s theories meant a great deal to Celsius, but even more important was the contact he had with the French mathematician P L de Maupertuis, who was a few years his senior. The latter took the initiative for the measurement of degrees in 1736-1737 that came to occupy such a prominent place in the scientific history of Sweden. The fact that he chose Sweden, says Tore Frängsmyr, was primarily thanks to Celsius. The team of six, which included Celsius, set up in Tornedalen.

It was a rugged experience. In the summer they were at the mercy of mosquitoes, and in the winter it was so cold that everything froze, except the vodka. But they achieved their goal and could establish by their measurements that the earth is flatter at the poles. A French team reached the same conclusions simultaneously in Peru.

The late years

For his work Celsius was awarded an annual state pension of 1,000 livres from France. Economically he was thus relatively comfortable. But he had led a rough life on his ambitious expeditions and with his nocturnal observations outdoors. He contracted tuberculosis and died at the age of 43. In one respect he was a forerunner of Darwin, as he stubbornly maintained to his dying day that the chronology of the Bible did not square with the findings arrived at by scientific research in his field.