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The Doctors Celsius

Doctor Olof Celsius (1670–1756) created one of the oldest herbarium collections at the Swedish Museum of Natural History, his Flora Upplandica from 1730. It is a collection of 765 pressed specimens of plants from the Swedish province of Uppland. The four volumes, with a fifth hand-written volume, were compiled in duplicate with one set for the University of Uppsala and one set as a gift for HRH the Queen Ulrika Eleonora.

Celsius' herbarium from Uppland was an inspiration to young Linnaeus, who went on many excursions, either by himself or travelling with Dr. Celsius in Uppland to collect materials for inclusion in the work.

Dr. Anders CelsiusDr. Olof Celsius was the uncle of Professor Anders Celsius (1701~1744), the man who developed the modern system of temperature measurement. Anders Celsius was primarily an astronomer, but had a wide range of interests. At one point he was interested in developing a standardised method by which all thermometers could be calibrated for consistent accuracy. In his successful efforts, Celsius developed the modern scale that most countries now use to measure temperatures. This, however, was not the only work done by the young Celsius.

After Anders Celsius was appointed Professor of Astronomy at the University of Uppsala, he spent five years on his 'Grand Tour' of Europe meeting with the world's leading astronomers and visiting all the major observatories. Soon after his return he participated in a large scale experiment with Pierre de Maupertuis, their goal was to measure the length of a degree along a meridian, close to the pole, and compare the result with a similar expedition to Peru (today Ecuador) near the equator. The expedition confirmed Newton's opinion that the shape of the earth is actually slightly flattened at the poles.

With his assistant Olof Hiorter, Celsius proved that the Aurora Borealis was influenced by the Earth's magnetic field by observing the Northern Light's effect on compass needles. He also wrote a popular book on mathematics for young students, observed and recorded over 300 stars and was instrumental in establishing the first scientific observatory in Sweden. He died of tuberculosis at 42.

It is an interesting footnote in history that Anders Celsius originally set 0°C as the boiling point of water, while the freezing point was 100°C. This may seem strange today, but it was a natural result of the way he calibrated his instruments.

Some people have credited Linnaeus with suggesting the reversal, but it is more likely that the credit should go to Daniel Ekström, who manufactured the thermometers, and most of the other scientific instruments used by both Celsius and Linnaeus.


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