Geoscience Reference
In-Depth Information
The surveying base was laid out on the winter ice and by December the river had
frozen hard enough to bear the scientists' weight. Like Picard's choice for the location
of his baseline on the plain where Orly airport is now, the surface ice was mostly level,
but there were obstructive blocks of ice and drifts of snow over its length of 7400 toises
(14 km). These had to be cleared so that the standard measuring sticks could be laid
down from end to end, and Maupertuis, Le Monnier and the others were only partly
successful in clearing the baseline. They pulled a triangular snow plow made of large
logs and dragged pointy end first to scrape the snow aside but it did not sink deep
enough into the snow. In another attempt they harnessed yoked cattle to the two ends of
a tree trunk but the log easily bounced over obstructions; in the end the baseline had to
be cleared by hand. They worked by twilight and the light of the aurora reflecting on
the snow, watched by Laplanders drawn by the novelty of the sight. As a standard
measure, they had taken an iron toise that had been calibrated against the standard at
Paris (it became known as the Toise du Nord), and they used this to make five-toise
measuring rods of fir. The rods were heavy and had to be laid out carefully on the snow.
The scientists did not trust their helpers to butt the ends of the rods together carefully
enough and always did these tasks themselves, noting each rod down on papers clipped
to boards strung around their necks. Like Picard, the expedition members guarded
against the possibility that, in the dark and the cold, they had miscounted the successive
placement of the rods. They did this by checking the length of the standard baseline with
a cord that they had measured but that stretched. This was not as accurate as the rods
but was longer and there was less chance of making a counting mistake.
As the winter drew in, it became practically impossible to work outside since the
temperature dropped to 15 to 25 degrees of frost. Maupertuis (1738) described the
icy labor:
Judge what it must be like to walk in snow two feet deep, with heavy poles in our hands,
which we must be continually laying upon the snow and lifting again, in cold so extreme
that whenever we would take a little brandy, the only thing that could be kept liquid, our
tongues and lips frozen to the cup and came away bloody, in a cold that congealed the
fingers of some of us… While the extremities of our bodies were thus freezing, the rest,
through excessive toil, was bathed in sweat. Brandy did not quench our thirst; we must have
recourse to deep wells dug through the ice, which were shut as soon as opened.
During the summer's work, the expedition had forgotten to take a crucial measure-
ment (the height of something that they had used to support instruments), and
Maupertuis returned to the mountain top in the snow to rectify the situation. He
remarked on the local methods of travel over snow that he had to adopt with a turn
of phrase that brings to mind images of the scientist tumbling head over heels; it
was the first time that he had used skis or a reindeer sledge. In order to walk, or
rather slide along, he wrote that the Lapps and Finlanders use “two straight boards
eight feet in length … to keep from sinking into the snow. But this way of walking
requires long practice.” Maupertuis' boat-shaped sledge was pulled by a half-wild
reindeer (
Fig. 23
) but Hellant, the interpreter, was practiced; he balanced well in his
sledge while Maupertuis drove at high speeds and often tumbled out. This infuri-
ated the reindeer but Maupertuis found that he could turn the sledge upside down
