The locations of the ends of the baseline are not precisely known. The northern measurement point was built on the east bank of the river, possibly on this shore area.
The marker could also be located on the small islands near the shore.
The southern end of the baseline was located west of Torne riverbank near the village of Niemis. The marker may have been somewhere in the vicinity of this felling field. On the left side of the picture you can see Aavasaksa rising on the other side of the river.
There was a large stone near the marker, on which the French carved two crosses as a sign. The stone in the picture is not the stone in question.

Baseline

The baseline is an approximately 14-kilometre long survey section on the Torne between Ylitornio and Övertorneå.

The northern end of the baseline is located on the eastern bank of the Torne, north of the mouth of the Tengeliönjoki river. The location of the marker is about 2 to 3 kilometres north of the Aavasaksa bridge junction. The exact location of the measurement point is not known.

The southern end of the baseline is on the west side of the river in the village of Niemis. It is about 14 kilometers from the northern point. The exact location of the southern marker is also unknown. According to Outhier’s map, the measurement point was located south of the mouth of the Armasjoki river.

According to Pierre Louis Moreau de Maupertuis, the baseline was the longest that had ever been measured in triangulation.

Triangulation is based on trigonometry. Once the length of one side of one triangle in a chain of triangles (the baseline) is known, the remaining sides can be calculated trigonometrically by measuring the angles between the sides. Triangulation had become an established method of cartography in the 1500s and 1600s.

The baseline was measured in severe winter frost on the ice of the Torne. Baseline end markers were erected in the summer and angles were measured for Aavasaksa Hill and Huitaperi Hill.

On their way along the Torne, the expedition had noticed that the river was particularly wide at Kainuunkylä and Koivukylä. This made the river a suitable candidate for a baseline.

Réginald Outhier explains how there are many islands in the river where hay is cut. There are many settlements on the shores, with fields of “beautiful round-eared barley and rye”. He describes the area as the most beautiful in the river valley.

As the rest of the expedition set off towards Pullinki Hill in late July, Alexis Clairaut and Charles Camus were left to determine the position of the baseline. They made long treks along the riverbanks and hills to find a suitable location for the baseline.

The angular measurements were taken in the summer, and in early December the expedition returned to Ylitornio to prepare for the measurements. They stayed at the Övertorneå vicarage on the west side of the river, near the Church of Matarenki.

The baseline was measured in late December during severe frosts.

Sources:

Maupertuis, Pierre Louis Moreau de. “Maan muoto”. Maan muoto ynnä muita kirjoituksia Lapista. Ed. Osmo Pekonen. Väyläkirjat, 2019 (orig. 1738).

Outhier, Réginald. Matka Pohjan perille. Maupertuis Foundation and Väyläkirjat, 2011 (orig. 1744).

A map

Guidelines for using the map
  • Red = Measurement point of the triangulation chain.
  • Green = Walking route.
  • Markers: Tap or click to get more information about the destinations.
  • Zoom out: Shows the location in the triangulation chain.
  • Drop icon: Locates the user’s location on the map.
  • Measure tool: Measure distances between locations.

Open the map in a new browser window.

On the old map

The baseline on the map drawn by Réginald Outhier (Carte du fleuve de Torneå, 1736).

Want a map for yourself? The map is currently sold as a poster (225 mm x 707 mm) in the shop of the Museum of Torne Valley (address Torikatu 4, Tornio).

The northern end of the baseline

Information

The northern end of the baseline is located on the east bank of Torne, about three kilometres north of the Ylitornio bridge or the Aavasaksa crossing.

The measurement point is probably in the area between highway 21 and the coastline.

There are several places to stop along Highway 21.

No trail.

Aavasaksa2,4 km
The southern end of the baseline14.4 km
(Distance as the crow flies.)

From the 23rd to 24th of August 1736
From the 21st to 30th of December 1736

The 21st of December 1736. “We made ready on Friday the twenty-first to begin our measurement from the northern signal. As a great deal of snow had fallen, eight machines were prepared to clear the road for those who measured: they were large logs of woods fastened together in the shape of a triangle, drawn by a horse, with the most acute angle foremost, so that the sides encreasing to the end, ranged the snow on both sides.”

Réginald Outhier. Journal of a Voyage to the North (Journal d’un voyage au Nord), 1744.

The 18th of August 1736. “The most convenient place for our Base had been already pitched upon. Messrs Clairaut and Camus, after having carefully viewed the banks of the River, had determined its Directon, and fixed its Length by Signals raised at either Extremity.”

The 23rd of August 1736. “The 22nd we went to Poiky-Torneå upon the banks of the River, where the Signal at the North end of the Base stood, to take the Angles that must connect it with the tops of the Mountains.”

Pierre Louis Moreau de Maupertuis. The Figure of the Earth (La Figure de la Terre), 1738.

Pictures from the northern end of the baseline

The pictures open in large size in the gallery by clicking on the picture.

The southern end of the baseline

Information

The southern end of the baseline is located on the west bank of Torne near the village of Niemis.

It is about 12 kilometres from the center of Övertorneå to the south.

No trail.

Huitaperi7 km
Aavasaksa14 km
The northern end of the baseline14.4 km
(Distance as the crow flies.)

From the 23rd to 24th of August 1736
From the 21st to 30th of December 1736

The 23rd of August 1736. “At three in the afternoon we reached the southern signal of the base, at a moment when the clouds of smoke were tolerably dispersed; but scarcely had we begun our observations, before the wind changing brought them back again. – – – In the evening we went down to Niemiby, which is a small village: we pitched our four tents there in the meadow, where we passed the night.”

Réginald Outhier. Journal of a Voyage to the North (Journal d’un voyage au Nord), 1744.

The 23rd of August 1736. “And next Day we set out for Niemiby, where the South Signal had been erected, in order to make the like Observations. We lay this Night in a pleasant Meadow; – – -”

Pierre Louis Moreau de Maupertuis. The Figure of the Earth (La Figure de la Terre), 1738.

Pictures from the southern end of the baseline

The pictures open in large size in the gallery by clicking on the picture.

The expedition on the map

Réginald Outhier has written a detailed description of the expedition’s journey from Paris to Tornio and back. The journey took two months each way and was made by boat and wagon. On the way back, the expedition was in a shipwreck in the Bay of Bothnia.

EXPLORE THE MAPS

Measurement points and other destinations