PART I. CHAPTER I. I. ASTRONOMERS AND CARTOGRAPHERS. Cassini--Picard and La Hire--The arc of the Meridian and the Map of France--G. Delisle and D'Anville--The Shape of the Earth--Maupertuis in Lapland--Condamine at the Equator. Before we enter upon a recital of the great expeditions of the eighteenth century, we shall do well to chronicle the immense progress made during that period by the sciences. They rectified a crowd of prejudices and established a solid basis for the labours of astronomers and geographers. If we refer them solely to the matter before us, they radically modified cartography, and ensured for navigation a security hitherto unknown. Although Galileo had observed the eclipses of Jupiter's satellites as early as 1610, his important discovery had been rendered useless