8 MEASUREMENT OF AN ARC 



Bringing down the grand arc, 'have been finally fixed. And here it may- 

 be proper to observe, that in, the tenth volume of Asidtick Researches f 

 I have mentioned the latitude of Dodagoontah to '".be 12 59 59.91 as 

 determined by nine stars from the Greenwich observations of 1802; and 

 from that, the latitude of the Observatory at Madras was deduced, and 



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was found to be 13 4 8.7. But if it be allowed that the plummet has 

 been drawn to the northward while observing atDodagoontah, the obser- 

 vations at that place would give the latitude less than it really is. Under 

 this conviction, I have made Punnae the fixed latitude which was deter- 

 mined by eigjit of the same stars that were observed at Dodagoontah, 

 and was found to be 8 9 38.39, and by setting off from that parallel, and 

 computing according to the lengths of the degrees given in art. 3, Appen- 

 dix ; the latitude of Dodagoontah is found to be 13 o 1.9 which is 2 more 

 than before, and therefore the latitude of the observatory at Madras as de- 



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duced from that of Dodagoontah, will be 13 4 11 nearly. 



After the deductions enumerated in this summary, the whole of the 

 measurements both in England, France, and at the polar circle, have 

 been compared, by using the degree in latitude 11 6 24, being the most 

 southern of the recent operations ; and from these different data, three 

 ellipticities have ' been computed, and the mean taken, which will give 

 an ellipsoid whose polar and equatorial diameters are to each other as 

 1 : 1.003242 nearly. From this, and the degree above mentioned, 

 various conclusions have been drawn, in the appendix to this memoir, to 

 which I shall refer the reader, and proceed to give a detailed statement, 

 of all:the particulars which are the immediate subject of this paper. 



Trichinopoly ,- Jfov. 1st. 1809. 



