§ ' MEASUREMENT m AN ARC 



drawn from them, than from toy experiments made by such pendulum* 

 as have been generally used for those purposes. 



The arc, which is the subject of this communication, is a continuation of 

 the same meridian line, whose position was determined at the station of 

 Dodagopntah in Mysoor, In 1805, and is the meridian on which the for- 

 mer arc was computed. The present arc commences at Putchapolliam 

 station in Coimbetoor, where the former one terminated, and concludes 

 at Punnae near Cape Comorin. The positions to the southward fall 

 very favorably, and the place of observation at Punnae is only 98.3 

 feet east from the meridian of Dodagoontah. There is one station 

 (Permaul malli) on a very lofty mountain, which has not yet been 

 observed at, on account of the difficulty in getting at it; and besides, the 

 season when I was in Coimbetoor was not favorable for ascending such 

 high places. In consequence of this, there are four triangles wherein 

 only two angles in each have been observed ; an omission which at pre- 

 sent must be dispensed with ; but the base of verification near Tinnivelly 

 will shew that no important error has crept into the operations. 



The measurement of the base line in Coimbetoor, and the observations 

 for the zenith distances of stars, were completed in the beginning of 1806; 

 but I have recorded them at full length here, as being the. commencement 

 of this section of the grand arc. The base near Tinnivelly was measur- 

 ' ed early in, the present year, and the triangles continued to the southern 

 station near the sea beach, a few miles east from the lines of Travancore, 

 At this station, I sat down to observe the same stars, which had been ob- 

 served at Putchapolliam, and with equal success. Having finished there, 

 I returned to Palamcoitah, with an intention of making another set of ob- 

 servations, and for that purpose I ere6led a small observatory on the - 



