324 FIGUKE OF THE EARTH. 



seen from this slight analysis of Schubert's work that there is a wide field for 

 the exercise of doubt. 



If it be conceded that the spherical figure of the earth is not admissible, and 

 the elliptical appears as little accordant with the most probable results of obser- 

 vation, what other geometrical type will represent, better than these two, or 

 more approximately than the second, the general form of our globe ] None, in 

 fact; for neither the more complicated figure, which Bougucr imagined, nor the 

 idea of separating the axis of symmetry from the polar axis, suggested by Klii- 

 gel, conceptions, both of them, which the theory of the attraction and primeval 

 riuidity of the earth excludes, are found to be exempt from the grave incon- 

 veniences which oppose themselves to the adoption of the second supposition. 

 Of this truth Schubert himself supplies us with a good proof. In his memoir 

 above cited, after analyzing the divergences, with reference to the form of the 

 earth, according to the elements from which that form is deduced, and investi- 

 gating the causes from which so great a discordance might proceed, he concludes 

 by maintaining that the earth resembles, not so much an ellipsoid of revolution, 

 as an ellipsoid of three axes, or, what is the same thing, that the meridians are 

 to be regarded as unequal ellipses, and the equator and parallels as also el 

 lipses, and not as circles, as had, till that date, been believed. But the same 

 astronomer, who seems so Avell persuaded of this consequence from his first in- 

 vestigations in April, 1859, afiirms, in January, 1861,* that, setting aside the 

 arc of India, he does not find, in the rest of the geodesic operations, any grounds 

 for doubting that the terrestrial globe is an ellipsoid of revolution, compressed 

 in the direction of the poles. What does this change of opinion, tliis vacillation, 

 in a man of Schubert's merit prove, if not that this last figure represents that 

 of the earth, as far as a geometrical abstraction can represent the forms, full of 

 life and harmonious adaptability, of natural objects ? 



But, admitting the elliptical form, it still remains to determine its constitutive 

 elements, and its dimensions ; and, with this view, what is the combination of 

 arcs of meridian which should be preferred to the rest, whether for the precision 

 ■with which those arcs have been measured, the merit of the geometers to whom 

 the operations were intrusted, or the favorable circumstances of time and terri- 

 tory in which they were executed 1 No single combination whatever : First. 

 Because all that astronomers of merited reputation and conscientiousness profess 

 to have done should be considered to be well done, or, at least, to be comparable 

 with what other astronomers, endowed Avitli the same qualities, are capable of 

 realizing, under the penalty of introducing into the science a principle of endless 

 confusion. Secondly. Because the differences which occur in the elements of 

 the terrestrial ellipsoid, taken by sejDarate combinations of arcs of meridian, indi- 

 cate, not so much a defect in the operations, or a fault in the observers, as a real 

 irregularity in the form of the earth, or the existence of disturbing causes, such 

 as the local attraction of mountains, and even those, scarcely avoidable in prac- 

 tice, which proceed from the unequal density and thickness of a plane surface. 

 And thirdly. Because if, in all strictness, the form which we seek docs not co- 

 incide with the preconceived figure, the interests of truth will always vindicate 

 their claim to recognition, if not by an apparent simplicity, at any rate by other 

 more fertile qualities than pertain to any theory, however simple and seductive. 

 In order, then, to deduce the geometrical figure of the earth the proper course 

 would seem to be to take into view all the partial measurements Avhich have 

 been made, or such, at least, as are distinguished by some notable circumstance, 

 as the place to which they correspond, the extent they embrace, or the accuracy 

 which has marked their execution, rejecting, of course, all which manifest care- 

 lessness on the part of the observers, or defect in the instruments which they 

 have been obliged to employ ; and, assuming that the ellipsoid of revolution is, 



* Astronomische Nachrkhtcn, No. 1303. 



