166 



MEASUREMENT OF AN ARC ON THE 



when I observed the polar star at the south end of 

 the base Hne. 



It was discovered, that at Perumbaiik hill, there 

 had been an error in reading off the south end of 

 the base, most probably of 1 0" from the microme- 

 ters, as all the angles which had a reference to that 

 point, exceeded what they ought to have been by 

 ten or twelve seconds. In consequence of this dis- 

 agreement, I chose to take the supplemental angle 

 in the second and fourtli triangles, after the other 

 angles had been corrected. The distance of the 

 north end of the base from Perumbauh\ as deter- 

 mined in the second triangle, being taken as abase 

 in the third triangle, wherein the three angles have 

 been observed to determine the distance from Fe- 

 rumbauk to the Mounts and from the north end of 

 the base to the Mount, it appears that the latter 

 distance comes out within 0,4 of a foot to what 

 had been brought by the first triangle; and that 

 the distance from the south end of the base to Pe- 

 rumbaiik hill, derived from the second and fourth 

 triangles, differ only ,14 of a foot. The distance 

 from the Mount to Perumbauk being that from 

 which all the operations are to commence, I wished 

 to be as particular as possible in determining it, 

 and the results from the third and fourth triangles 

 make it 43493,4 and 43495,5, differing only one- 

 tenth of a foot-. 



Mount station from Perumbauk Hill 4349^,4. 



