LF.T. XV. OF THE EARTH. 247

little more than the eleventh part of a Parisinch, in order to make it agree with the timesof the stars palling the meridian.

Natural philosophy and geometry were notthen by far so much cultivated as they are atpresent; and who could have believed, saysM. Voltaire, that from an observation so triflingin appearance, could have sprung so sublime andphilosophic a truth. A pendulum, like anyother falling body, is acted upon by the forceof gravity ; and, in consequence of Richer’s dis-covery, it was observed, that, smce the gravityof bodies is by so much the less powerful asthose bodies are farther removed from the centerof the earth, the region of the equator mustabsolutely be much more elevated than that ofFrance; and that, therefore, the figure of theearth could not be that of a sphere.

This reasoning, so very simple and natural,escaped the greatest philosophers of that time ; acertain proof that the strength of prejudice doesnot permit the slightest examination: theyeven contested Richer’s experiment. Metals areknown to be lengthened by heat, and contractedby cold, and to this cause they attributed thedifference which he had observed between thevibrations at Cayenne and at Paris. The mostintense summer heat will lengthen an irod rodof thirty feet long, about the eleventh part ofan inch ; but the question here was concerning

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