6 MEASUREMENT OF AN ARC 



mentioned, I thought it reasonable to take the mean of the two degrees,, 

 which gave 60490 fathoms nearly, for the length of the degree in lati- 

 tude 11 59 54. 



Whatever may have been the cause of irregularity in the observations 

 made at Bomasundrum and Dodagoontah, the errors occasioned thereby 

 must be considerably reduced when the whole arc, including the present 

 measurement, is taken into account. I shall therefore take notice here 

 what the general result gives, by comparing the arcs Punnae and Doda- 

 goontah, Punnae and Bomasundrum, and Punnae and Paughur, which 

 last place was also a station of observation in the former part of the 

 operations. 



It appears from art. S. that the celestial arc between Punnae and 



o * li 



Putchapolliam is 2 50 1054; and the celestial arc between Putchapolliam 

 and Dodagoontah, by the observations in 1805 and 6, was- 2 o 9.79 ; and 

 therefore, the sum is 4 50 20.33, equal to the celestial arc between Punnae 

 and Dodagoontah. The terrestrial: arc between Punnae. and Putchapolliam, 

 is 1029100.5 feet, to which add 727334.6 feet, the terrestrial arc between 

 Putchapolliam and Dodagoontah, we have 1756435;! feet or 292739.3 

 fathoms, which compared with 4 50 20.33 will give the mean length 

 of the degree, equal 60496 fathoms; for latitude 10. 34 49,. the middle 

 >int of the arc. 



The former celestial arc between Putchapolliam and Bomasundrum was 

 3 o 1.S8, to which add 2 50 10.54 gives 5 50 12.42; and the terrestrial 

 arc between Putchapolliam and Bomasundrum 1088275 8 feet, to which add 

 1029100.5 feet, gives 2117376.3 ^feet, or 352S96 fathoms nearly, which 

 compared with 5 50 1242, gives 60462 fathoms for the mean length of 

 the degree in latitude 114 44 nearly, the middle point of the arc. 



