But it was not until the sixteenth century that the study of the earth’s size and figure began again to attract attention. The fact that it did so, and the interest that was thereafter maintained in this investigation, stand in the first instance to the honour of French science. The Spanish and Portuguese congress which attempted in 1524 to lay down the boundary fixed under the Pope’s award as separating the areas of Spanish and Portuguese dominion in the new world--a line lying 370 leagues west of the Cape Verd Islands--failed utterly; the length neither of a degree nor of a league could be agreed upon. Jean Fernel (1497–1558) in France, however, made measurements by calculation from the revolutions of a carriage wheel and by means of quadrant observations, and reached a fair estimate of a degree. A Dutchman, Willibrord Snell, who published his results in 1617, laid the foundation of modern methods of survey by applying to the measurement of an arc between Alkmaar and Bergen-op-Zoom the system of a series of triangles and the trigonometrical computation of the distance. During the century which intervened between the labours of Fernel and of Snell, it is clear that interest was waking in the development of precise methods of land-surveying, for the compass was probably first applied to this work at the beginning of the period; in 1571 we find Leonard Digges introducing in England an instrument which represented the theodolite at an early stage; and Jean Pretorius at Wittenberg in 1590, and Philip Danfrie in France in 1597, with his graphometer, foreshadowed that most valued equipment for detailed survey work, the plane-table. [Illustration: Fig. 12.--Cross-staff.]