Maupertuis Memorial in Mount Kittisvaara in Pello in Finnish Lapland

A science expedition led by French mathematician and astronomer Pierre Louis Maupertuis travelled in the Tornio River Valley in 1736 – 1737. He was accompanied byAlexis Claude Clairaut, Charles Étienne Louis Camus and Pierre Charles Le Monnier, who were astronomers as well. The group also shared other interests, mathematics in particular.

Reginald Outhier and Swedes Anders Celsius and Anders Hellant also travelled with the expedition. The latter was originally from Pello. At the time, Finland was a territory of the Swedish kingdom. The goal of the expedition was to perform measurements that would determine whether the Earth was round or flattened at the poles. The expedition left its mark both on the history of science and on the traditional lore of the Tornio River Valley.

The expedition had to learn to cope with the local natural environment when performing their scientific work. A base line of 14.3 km was measured on the ice covering River Tornio. Triangulation was then employed to determine the length of a degree of the meridian arc. The southernmost measurement point was the church steeple in Tornio and the northernmost was Kittisvaara hill 4 km to the north of Pello town centre. A memorial, called Maupertuis Memorial, was erected on the hill in 1956.

Upon his return, Maupertuis reported that one degree of the meridian arc in Lapland was  57,437.9 toise long. (The old French unit toise is equal to 1.949 metres.) This result was compared to the 57,060 toise measured near Paris to demonstrate that the Earth was flattened – just like the theory predicted – at the poles. The measurements were later found to contain some fairly large errors, but they nevertheless pointed in the right direction. The King of France granted Celsius an annual pension of 1,000 livres.

Further information: (only in Finnish)