of 



Latitudes for Local Attraction. 331 



positions which are in themselves highly unlikely, and in any 

 case entirely unproved. Such correction could be admissible 

 onlv in the case where the disturbances are recognized as 

 entirelv accidental and independent. The decision as to 

 whether they are so in general must be a matter of experience. 

 If stress might be laid on experiments made np to the present 

 dav. they would decide against the view to which we object : 

 but in fact they will bear no such strain. Meanwhile the 

 purpose which these corrections are meant to serve, namely 

 to raise the value of arc-measurements in determining the 

 mean figure of the earth, may be attained with incomparably 

 less trouble and to a much greater extent, in a perfectly un- 

 objectionable way : we have merely to determine more lati- 

 tudes. This might be gathered from what has been said : 

 but it is clear of itself when it is remembered that we have to 

 do with the mean figure of a body which is certainly irregular, 

 which figure can onlv be ascertained bv observations taken 

 at as many points as possible. 



•' From among the foregoing remarks we think we may 

 commend to further attention our objection to special deter- 

 minations of the mean density of the earth, as well as the 

 suggested expediency of an increase in the frequency of 

 stations of observation. 



" Finally, we must not neglect to defend ourselves expressly 

 against the conclusion that because we regard the repeatedly 

 mentioned levelling as of no avail for the purpose of aiding 

 in the problem of the figure of the earth, we therefore 

 think them altogether useless. So little is this the case, 

 that we do not hesitate rather to count these and similar 

 labours, and the solution of problems connected with them. 

 amongst the most important features of the higher geodesy. 

 It is only the application which it has been thought might 

 be made, in this direction, of particular materials, and the 

 opinion thence derived that such researches belong especially 

 to the essentials of arc-measurement, which is erroneous. 

 It would be going too far to attempt at present to describe in 

 fuller detail the aims which, in our opinion, ought to be the 

 principal ones : but we are glad, in reference to this question. 

 to be able to give our entire and unqualified assent to a re- 

 mark made by Gen. Schubert, which is. we think, a not un- 

 necessary one — namely, that it would not be right to limit 

 these researches to the disturbance of the plumb-line in the 

 direction of the meridian, as has been done in the case of the 

 English work before us." 



To the foregoing examination bv Dullen. and to the con- 

 elusions which he has founded upon it. I may signify my 



2B2 



