208 Notes, chiefly Geological, [No. 171. 



fertilizes, it washes the feet of the eastern ghauts, receiving many moun- 

 tain tributaries to the base of Amboor-droog ; whence, turning the 

 northern flank of the Rajahpollium and Javadie hills, which bound the 

 right of the valley, it escapes easterly by Paliconda to Vellore. Thence 

 it crosses the Carnatic increased by the Poni ; by Arcot, Wallajahbad, 

 Conjeveram, and Chingleput to the Bay of Bengal, into which it flows 

 about three and a half miles, south of Sadras, in latitude 12° 28' N. 

 after a course of about 220 miles, marked during its progress through 

 the Carnatic by a narrow, verdant, winding zone of rich vegetation. 



The road from Chingleput to Carangooly lies at no great distance, 

 for the first and greater part of its course, from the right bank of the 

 river, over the plain on which the town and fort of Carangooly stand, to 

 the eastward of the large tank, and about thirteen miles SSW. from 

 Chingleput. A few low hills in the vicinity mark the prolongation 

 of the bed of hornblende rock observed at St. Thomas' Mount, Palave- 

 ram, and Chingleput. The prevailing soil is a sandy loam. 



Carangooly, like Chingleput, during our early wars with the French, 

 was a military post of great importance, though now reduced to 

 insignificance. The gates of the fort were blown open, and the place 

 stormed by Capt. Davis (January 24th, 1781) : Hyder's garrison was 

 700 strong. 



The fort was dismantled by General Stuart, in February 1783. 



Permacoil. — The route to Permacoil lies over a plain less cultivated 

 and more jungly than hitherto ; varied at Acherowauk by a range of 

 hills running for two or three miles in a SW. direction, flanking the 

 right of the road. At Permacoil the granitic rocks rise above the sur- 

 face in clusters varying from 100 to 300 feet high. The chief mass is 

 composed of felspar, quartz, mica, and hornblende, in some places 

 veined by a porphyritic granite with large plates of mica. The mica is 

 sometimes entirely replaced by hornblende in the same mass, and would 

 be termed a syenite by many geologists. 1 picked up a few crystals of 

 adularia in the gravelly detritus of a weathering vein, and some fine 

 specimens of an iridescent felspar. The felspar, which prevails in the 

 substance of the rocks, is reddish, and the mica dark coloured, but it 

 sometimes occurs in rich gold coloured scales and plates. 



The soil is a greyish, friable loam, passing into reddish and sandy, 

 and usually rests on a bed of kunker ; below which, in a bed of sand and 

 gravel, water is found at depths of from eight to fourteen feet from the 



