In 1730, Celsius published the (
New Method for Determining the Distance from the Earth to the Sun). His research also involved the study of auroral phenomena, which he conducted with his assistant
Olof Hiorter, and he was the first to suggest a connection between the
aurora borealis and changes in the magnetic field of the Earth. He observed the variations of a compass needle and found that larger deflections correlated with stronger auroral activity. At
Nuremberg in 1733, he published a collection of 316 observations of the aurora borealis made by himself and others over the period 1716–1732. Celsius traveled frequently in the early 1730s, including to Germany, Italy and France, when he visited most of the major European observatories. In Paris he advocated the measurement of an
arc of the meridian in
Lapland. In 1736, he participated in the expedition organized for that purpose by the
French Academy of Sciences, led by the French mathematician
Pierre Louis Maupertuis (1698–1759) to measure a degree of
latitude. The observatory was equipped with instruments purchased during his long voyage abroad, comprising the most modern instrumental technology of the period. In 1742 he proposed the Celsius temperature scale in a paper to the
Royal Society of Sciences in Uppsala, the oldest Swedish scientific society, founded in 1710. His thermometer was calibrated with a value of 0 for the boiling point of water and 100 for the freezing point. In 1745, a year after Celsius's death, the scale was reversed by
Carl Linnaeus to facilitate more practical measurement. Celsius conducted many geographical measurements for the Swedish General map, and was one of the earliest to note that much of Scandinavia is slowly rising above sea level, a continuous process which has been occurring since the melting of the ice from the latest
ice age. However, he wrongly posed the notion that the water was
evaporating. In 1725 he became secretary of the Royal Society of Sciences in Uppsala, and served at this post until his death from
tuberculosis in 1744. He supported the formation of the
Royal Swedish Academy of Sciences in Stockholm in 1739 by Linnaeus and five others, and was elected a member at the first meeting of this academy. It was in fact Celsius who proposed the new academy's name. ==Works==