fc|§ MEASUREMENT OF AN ARC 



gles were begun at Paughur and Yerracondah, (fee the plan), and brought 

 down to the bafe ntar Bangalore ,< from which other triangles had been 

 extended foutherly in 1804, for the purpofe of obtaining fides of a 

 great length, for meafuring a perpendicular arc, but which anfwered 

 exceedingly well for the meridional ferie;. In the beginning of 1806,. 

 that feries was reaffumed, and carried down to the Coimbetoor country, 

 where a bafe was meafured, and a choice collection of zenith diftances 

 obferved, an account of which was given in my la ft communication* 

 which gives the particulars of the fouthern fe&ion of this arc. 



: In 1811, the triangles were again taken -up: at Paughur and Yerracon* 



■dak, and carried up to Gooty, for determining as ufual the height of that 



bafe above thefea; but when that meafurement was computed and 



reduced to the level of the fea, the triangles were computed back to 



the diftance Paughur and Yerracondah, differing from the fame diftanee 



brought from the bafe near Bangalore 1 A feet, which, proportioned to 



.the meafured bafe near Goaty, will make a difference of 3^ inches, 



fuppofing it to have been computed as a fide of the lafl .triangle, 



brought out from the bafe near Bangalore* ' The fuperintendence of 



thefe triangles was intruded to Lieutenant Riddell, of the. Company's 



iervice, while I was meafuring the bafe, and bbferving zenith diftances ; 



aji$thus terminated thefe operations; a fummary account of which I 



have; thought it neceffary to give, becaufe they have been carried on 



rat intervals only, and in point of time, bear bu't a fmall proportion, t<J 



that taken up oa:the geographical fcale. 3 : 



In the prefent volume of thefe Refearches, I have given the gene- 

 ral formulas for determining the figure and dimenfions of the earth, 

 • taking: my. own meafurements as ftated ift" that accbunt, and the different 

 meafurements in England, France^ and at the Polar Circle 3 from which a 



