?R0BLExMS IN SPHEROIDAL TRIANGLES, ]59 



1 mean not, however, to fupport the opinion, that the earth l^lie e^ith pro- 

 is not an dlipfoid ; but, on the contrary, (liould be very loth J^'^ I' '"'^'"P" 

 <o be obh'ged to give up an hypothefis, which is To beautiful in 

 theory, and has Hood its ground fo long. Many of our objec- 

 tions to it may very probably arife froni errors in obfervation?, 

 or from other caufes which have not yel been fully examined. 

 The remarks of Mr. FJayfair on this fubjedl are very ingenious, 

 and I hope will be confirmed by the phenomena: but if not, 

 I am convinced we have not the plea of inaccuracy to fet up 

 in this inftance. One of the ftrongeft objedions, however, 

 has been lately done away. The degree of the earth meafured particularly 

 in Lapland in the year 1736, has been found, by fome Swedifh^P f^I^^^^LaTand 

 gentlemen fent there for thdft purpofe, to err in excefs by no degree removes 

 lefs than 20S toifes. Now if we advert to the number ^ndTf'°^ ^^^ 



, QTubts enter- 



•naracter or the aftronomers who originally meafured this de-tainedon this 

 gree, it will be difficult for us to fet limits to the errors of^'^'^J^^' 

 other obfervers. Perhaps the anomaly in the degree at the 

 Cape of Good Hope arifes from the fame caufe. 



Fortunately, however, the great improvements, which have ^-te improve- 

 fince been made in the in(b-uments for cuaronomical obferva- Jl'J'J^^-g'^j^!^^'^^^^ 

 tions and geodaetical menfuration, afford us the means of bring- 

 ing the probable errors of obfervatlon within very narrow limits. 

 We may thus obtain a number of meafnres in different latitudes 

 of equal accuracy, and by comparing them together, the 

 queftion about the earth's figure may be put-beyond a doubt. 

 If this comparilbn fi-iall be found to give difft^rent ellipies, we 

 fhall then be fully warranted in rejedling the hypothefis en- 

 tirely and for ever. But till this is done, we may be allowed 

 to adopt an hypothefis, which is fo ilmple, fo good in theory, 

 and fupported by fo many flrong arguments and accurate ob- 

 fervations. ^ 



We have already remarked, that the degree lately meafured Mean compref. 

 ui the Myfore, compared with that in France and England, f°" ^'°'".'""- 

 gives -j-lo for the comprefhon at the poles : the correded de- 

 gree in Lapland gives -jl-j, and that meafured in Peru, -jj-^. 

 There is a confiderable difference between the compreffions 

 deduced from other meafures, but the mean falls between 

 thefe limits. From the befl obfervations of the length of 'the and from th; 

 pendulum that fwings feconds in different latitudes, the fsme P'^"'^"^"'"' 

 conclufion is alfo drawn ; the fecond pendulum near the pole 



compared 



