Of all the extraordinary journeys dreamed by Jules Verne, perhaps that to the center of the earth took us to regions least explored.
But these deep-lying rocks we can not reach exercise from afar their attraction which operates upon the pendulum and deforms the terrestrial spheroid. Geodesy can therefore weigh them from afar, so to speak, and tell us of their distribution. Thus will it make us really see those mysterious regions which Jules Verne only showed us in imagination.
This is not an empty illusion. M. Faye, comparing all the measurements, has reached a result well calculated to surprise us. Under the oceans, in the depths, are rocks of very great density; under the continents, on the contrary, are empty spaces.
New observations will modify perhaps the details of these conclusions.
In any case, our venerated dean has shown us where to search and what the geodesist may teach the geologist, desirous of knowing the interior constitution of the earth, and even the thinker wishing to speculate upon the past and the origin of this planet.
And now, why have I entitled this chapter French Geodesy? It is because, in each country, this science has taken, more than all others perhaps, a national character. It is easy to see why.
There must be rivalry. The scientific rivalries are always courteous, or at least almost always; in any case, they are necessary, because they are always fruitful.
Well, in those enterprises which require such long efforts and so many collaborators the individual is effaced, in spite of himself, of course; no one has the right to say: this is my work. Therefore it is not between men, but between nations, that rivalries go on.
So we are led to seek what has been the part of France. Her part I believe we are right to be proud of.
At the beginning of the eighteenth century long discussions arose between the Newtonians who believed the earth flattened; as the theory of gravitation requires, and Cassini, who, deceived by inexact measurements, believed our globe elongated. Only direct observation could settle the question. It was our Academy of Sciences that undertook this task, gigantic for the epoch.
While Maupertuis and Clairaut measured a degree of meridian under the polar circle, Bouguer and La Condamine went toward the Andes Mountains, in regions then under Spain which to-day are the Republic of Ecuador.
Our envoys were exposed to great hardships. Traveling was not as easy as at present.
Truly, the country where Maupertuis operated was not a desert, and he even enjoyed, it is said, among the Laplanders those sweet satisfac-
