FIGURE OF THE EARTH. 317 



tbe earth, and the great probability of the ellipticity of the globe. But as the 

 ideas of attraction and of central and centrifugal forces had not as yet become 

 familiarized, and as the phenomenon discovered by Richer might proceed from 

 an unknown cause, the Academy suspended its judgment upon the consequences 

 deducible from that pheuomeuon, until new and repeated observations should 

 confirm or disprove them. The confirmation was not long deferred, for llalley, 

 repeating four years after in St. Helena the same experiments v/hich Richer 

 had made, obtained an identical result, and the fact has subsequently been real- 

 ized in all the regions of the earth as well as upon the high seas. 



We may take this occasion to remark that in the study of nature there arc 

 problems whose solution, after resisting for ages all the forces of man, seems at 

 some determinate epoch to become practicable in a hundred different ways ; such 

 a problem, undoubtedly, was that which now occupies us. In the sixteenth 

 century Copernicus, Galileo, and Avhosoever thought as they did respecting the 

 movement of the earth, were regarded with scorn or aversion ; in the middle 

 of the seventeenth, the roundness and rotation of the globe are admitted Avithout 

 difliculty ; in 1G70 Picard determines by a satisfactory process the value of 

 the earth's radius ; two years later, the observations of Richer show that the 

 form of the globe differs sensibly from the spherical ; about the same time, Cas- 

 sini, by means of the telescope, perceives and measures the remarkable oblate- 

 ness of Jupiter, thus supplying from analogy a weighty reason for admitting 

 without other proof that of the earth ; while Huyghens and Newton, preceding 

 and directing, as it were, the methods of observation, deduce the same result 

 by process of reasoning, establish the extreme limits within which its numeri- 

 cal expression must be comprised, and ascend to the cause from which it pro- 

 ceeds. Honorable epoch for the human intellect in which such capital discov- 

 eries rapidly succeed one another ! "With the songs of triumph, however, soon 

 mingle the notes of discord, and for some years the problem of the figure of 

 the earth remains stationary and proves to be beset with unexpected difficul- 

 ties. 



The Academy of Paris, stimulated by the prompt and apparently satisfac- 

 tory termination of the measurement of the terrestrial degree by Picard, con- 

 ceived the idea of prolonging the operations instituted by that savant from oi)^. 

 extremity of France to the other, or, more precisely, from Amiens to Perpig- 

 nan ; a bold enterprise for that epoch, which the intelligent activity of Domin- 

 ico Cassini realized in the latter part of the century. But when Cassini, the 

 operations and calculations being concluded, compared with one another the 

 values of the 7^ of the meridian measured, he observed with surprise that their 

 length continually diminished from south to north, as if the curvature of the 

 earth increased towards the poles, or its radius diminished ; or, in other terms, 

 as if the compression of the globe corresponded to the equatorial region, contrary 

 to all that Avas then conjectured or deduced from theory ; a consequence which 

 the same astronomer still arrived at after having prolonged the French meridian 

 north from Amiens to Dunkirk, at the end of the year 1713. A conflict thus 

 became unavoidable and imminent. On the one hand, the authority of Newton 

 interposed itself; on the other, that, scarcely less weighty, of the French geom- 

 eters, as well as the national pride of the latter ; and as between the extremes 

 in discussion there could be no possible compromise, the scientific world Avas 

 divided into two parties ; all that had been done or deduced to determine the 

 true figure of the earth w^as brought before the tribunal of opinion, from the 

 principle of the universal attraction of matter to the ability of the observers who 

 had officiated in the measurement of the arc of the meridian. After much time 

 had been lost in barren and heated discussions, the French Academy of Sciences, 

 at the suggestion of Maupertuis and Bougucr, two of the most distinguished 

 savants of their age, adopted the only feasible plan for setting the question 



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