This was by Fernel, a French physician, who, having observed the height of the pole at Paris, went thence northward until he came to a place where the height of the pole was exactly one degree more than at that city.
He measured the distance between the two stations by the number of revolutions of one of the wheels of his carriage, to which a proper indicator bad been attached, and came to the conclusion that the earth's circumference is about twenty-four thousand four hundred and eighty Italian miles.
Measures executed more and more carefully were made in many countries: by Snell in Holland; by Norwood between London and York in England; by Picard, under the auspices of the French Academy of Sciences, in France.
Picard's plan was to connect two points by a series of triangles, and, thus ascertaining the length of the arc of a meridian intercepted between them, to compare it with the difference of latitudes found from celestial observations.

The stations were Malvoisine in the vicinity of Paris, and Sourdon near Amiens.

The difference of latitudes was determined by observing the zenith-distances, of delta Cassiopeia.

There are two points of interest connected with Picard's operation: it was the first in which instruments furnished with telescopes were employed; and its result, as we shall shortly see, was to Newton the first confirmation of the theory of universal gravitation.
At this time it had become clear from mechanical considerations, more especially such as had been deduced by Newton, that, since the earth is a rotating body, her form cannot be that of a perfect sphere, but must be that of a spheroid, oblate or flattened at the poles.

It would follow, from this, that the length of a degree must be greater near the poles than at the equator.
The French Academy resolved to extend Picard's operation, by prolonging the measures in each direction, and making the result the basis of a more accurate map of France.