Driven by famine to eat scraps of skin and leather with which his rigging was here and there bound, to drink water that had gone putrid, his crew dying of hunger and scurvy, this man, firm in his belief of the globular figure of the earth, steered steadily to the northwest, and for nearly four months never saw inhabited land.  He estimated that he had sailed over the Pacific not less than twelve thousand miles.  He crossed the equator, saw once more the pole-star, and at length made land—­the Ladrones.  Here he met with adventurers from Sumatra.  Among these islands he was killed, either by the savages or by his own men.  His lieutenant, Sebastian d’Elcano, now took command of the ship, directing her course for the Cape of Good Hope, and encountering frightful hardships.  He doubled the cape at last, and then for the fourth time crossed the equator.  On September 7, 1522, after a voyage of more than three years, he brought his ship, the San Vittoria, to anchor in the port of St. Lucar, near Seville.  She had accomplished the greatest achievement in the history of the human race.  She had circumnavigated the earth.

The San Vittoria, sailing westward, had come back to her starting-point.  Henceforth the theological doctrine of the flatness of the earth was irretrievably overthrown.

Five years after the completion of the voyage of Magellan, was made the first attempt in Christendom to ascertain the size of the earth.  This was by Fernel, a French physician, who, having observed the height of the pole at Paris, went thence northward until be 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.