from the measurement of an arc of the meridian , &c. 489 
miles each, the whole difference between these arcs and their 
chords would not be more than a fathom and a half. 
The number of base lines in this extensive arc, are five ; 
all measured with the chain extended in coffers; with 
elevating screws, &c; and every part of the operation has 
been performed with the greatest posssible attention. The 
one near Bangalore may be considered as the first ; and its 
height above the sea was obtained by a series of triangles 
connecting it with another base near St. Thomas’s Mount, 
whose height above the low water mark was determined by 
observations made at the sea beach, and at the race stand near 
the north end of the base (Asiat. Res. vol.viii.). The base lines 
to the southward are, the one in Coimbetoor, and the other 
near Tinnivelly, whose heights above the sea were determined 
from the Bangalore base. Those to the northward are, the 
base near Gooty, and the one near Daumergidda. The 
account of this last measurement, and of the curious experi- 
ments for comparing the steel chains with the brass standard 
scale, will appear in the 13th volume of the Asiatick Re- 
searches. The particulars of the other measurements may be 
seen in the 10th and 12th volumes of the same work. 
The great station of observation at Doddaguntah, is near 
the first base line; and it was at that station where the 
position of the meridian was fixed for extending it to the 
north and south. The latitude of that station was also 
determined by observing the zenith distances of a number of 
stars from the Greenwich catalogue for 1802. That latitude, 
however, was afterwards set aside from a supposed disturb- 
ance of the plummet. The latitude was afterwards fixed 
from observations made at Punnae, the southernmost station of 
