24 Ol'servatlons oh the Measurement of 



and perfection of the instruments employed by t'nat skilful 

 observer, as well as the scrupnlous care bestowed on every 

 part of the service in which he was engEged. Bengal 

 lights were employed on this occasion as (ibjects at the 

 several stations, and their position appears lo have been de- 

 terniined with the utmost precision by the iheodolue of 

 Ramsden, which reduces all am-les to the plane of the 

 horizon, and with such a: degree >if correctness, that the 

 error in the sum of the thiee angles of any triangle is 

 scarcely, in anv instance, found to exceed three seconds of 

 a degree, and in general not more than a small ffaction of 

 a second. 



Accordingly the f:eodetical observations were conducted 

 with a degree of exactness which hardly can be exceeded; 

 and even if we suppose for a moment, th.it the chains made 

 use of in ihe mea.Hirement of the bases may not admit of 

 equal precision with the rodsof piatina employed in France ; 

 nevertheless, iRe degree of care employed m llieir construc- 

 tion, in the mode of using them, and the pains taken to 

 verify their measures, was such, that no error thai can have 

 occurred in the length of the base could make any per- 

 ceptible difl'erence in the sides of the series of triangles, of 

 which the whole extent does not amount to so much as 

 three <legrces. 



Nevertheless, the results deduced by the author, from 

 this measure alone, would lead to the sii|)posiiion that the 

 earih, instead of being flattened at the poles, is in fact mure 

 elevated at that part than at the equator, or at least that itis 

 surface is not that of a regular solid. For the measures» 

 of difi'erent degrees on the meridian, as reduced by Lieut. 

 Col. Mudge, increase progressively toward the equator. 



The following table of the different measures of a degree- 

 ni fathoms is given by the author in his meinuir. 



I>ntitudc. 



.^2" 50' 30" , C0766 



.52 38 56 60769 



52 28 6 60794 



^0820 

 60849 

 (50861 

 60890 

 60884 

 The singularity of these results excites a suspicion of 

 gome incorrectness in the observations themselves, or in 

 the method of calculating from them. The author has not 

 informed us in hi9 memoir, what were the formulae whigh 



