112 Correspondence. 



Extract of a letter from Lieutenant Ochterlony, Madras Engineers, dated 



Ath January, 1841. 



I have been so exceedingly unwell since my return to Madras, that 

 I have been unable to attend to business of almost any description. 

 I have however not been unmindful of the promise I made about the 

 specimens which you required from South India, and have now ready 

 some of chromate of iron, copper ore, lead ore, and iron ore of Southern 

 India ; but I still require from Salem a good sample of the magnetic ore, 

 and of the cast iron produced at Porto Novo. 



I am also anxious to send you, if possible, some specimens of an ex- 

 ceedingly interesting sedimentary formation which has recently been 

 brought to light near Pondicherry, the fossils of which testify to its be- 

 ing equivalent to our cretaceous formation in Great Britain. Echini, 

 Belemnites, Turratiles, &c. and more recently Ammonites, have been 

 found in the rock, a limestone which it is likely will be found to extend 

 in a band as far south as Trichinopoly, where some similar specimens 

 of rock were found some time since, and if I can prevail on the discoverer, 

 Mr. Kaye of our C. S. to send up a few cooly loads you shall have some 

 forwarded. 



I shall shortly, I hope, if my health is restored, be able to publish 

 a report upon the metalliferous districts of Southern India, which, 

 from the facts and experience gained by actual mining, will, T hope, 

 throw a proper light upon the real nature of the deposits of the useful 

 metals which exist here, and shew that although a very general diffusion 

 of them actually prevails, in no one single instance or locality is any 

 thing like concentration found. In my own peculiar districts — Cuddapah, 

 Nellore, Gunton — the ores of copper, lead, and iron are disseminated 

 through vast extent of rock, but no true veins exist in any part, and it 

 wouldappear as if the electro-chemical or active agency, in a proper degree 

 of intensity, had been wanting to produce that concentration into beds 

 or veins without which no mining adventure can be warrantable. Indeed 

 the same defect in Nature's power, as it were, is evident over the whole of 

 Southern India, where the prevailing ore, that of iron, is found to occur 

 not in beds, masses, or veins, but as a portion of the rock, disseminated 

 throughout the mass, and obtained by breaking away the whole, and 

 washing the sand and other particles clear. In like manner gold occurs 

 disseminated through the sienitic rocks of Cumbatore and the south- 

 west, and being a precious metal, may in that form be worth mining 

 for, but no vein has ever been traced in that, or I believe any other part 

 of igneous rock which forms the terra firma of this part of India. 



