'^SS On (he Crystalline Stnirlure of the 



full of rain, or othor similar causes, masses ^voul^.^ be dclached, ami 

 borne along to distances according to their size and weight. They 

 seemed all nearly of the same size, and of equal specific gravity, hence 

 Ave may infer, a transporling power of equal intensity had acted on all, 

 and hence, also, an additional argument might be derived for their being 

 true boulders. On finding, however, that in one part of its course, ihe 

 nullah was confined by an artificial bund, mainly con)j)osied of masses 

 similar to those strewed over the plain, the poss^ihiliiy, that the latter 

 might have been derived from the former, suggested itself, and naturally 

 tended to throw doubts on the first idea, that the masses had been 

 brought, by the force of the stream, from the distant hills ; evidence is 

 however, wanting to enable the inquirer to form any decided opinion, 

 and, therefore, it is best to rest satisfied with a simple statement of facts, 

 without attempting to draw conclusions, for which these cannol be deem- 

 ed sufficient warrant. 



Tlie road to Palliconda iniersects the range of hills which forms 

 the enclosure to the j lain of Amboor, at a distance of about half 

 a mile from the latter place. At this point, the road winds along 

 between two hills forming portions of the main range. To the left hand 

 of one of these, my attention was particularly directed*, and on exauiina- 



• At ralliconda, I examined with much interest the geological features of a large hill 

 in its vicinitj- which I subsequently found had been described by Dr. Benza. On com- 

 paring my notes with his description 1 found there was no essential difl'erence between 

 them, save in one or two trifling instances, arising from the diflerent degrees of atten- 

 tion with which we had examined ditferent localities. I will annex therefore in this note 

 only a vapid sketch of the results of my observations, referring those desirous of seeing 

 the subject treated in greater detail to the paper above alluded to. The plain at the base 

 of the hill is sandy, and strewed over it, there are masses of a sienite, which, as is proved 

 by the natural sections exposed at various points in the beds of the neighbouring nullahs, 

 forms the undeilaying rock of the whole. Traversing this there are dykes of trap and 

 porphyry, with veins of quartz and felspar. The two latter are sometimes found to- 

 gether — the quartz massive and the felspar crystalline, forming together a compound 

 coming under the class porphyry. Since it is a general principle, recognised in naming 

 different members of this class, to distinguish these by affixing the name of the matrix in 

 which the crystals are imbedded to that of the general class, I have ado{.ted the name of 

 quartz porphyry for the above. It may be remai'ked in passing that it is of the greater im- 

 portance to adhere to some general principles in the nomenclature of geology, as few sci- 

 ences have suffered more from these having been lost sight of. The progress of our studies 

 is most seriously impeded by the different arbitrary systems authors have employed, and 

 the necessity for a table of synonyms is absolute when we wish to compare different 

 works, each of which perhaps describes the same rock under names so different as to 

 render their identification quite impossible. Investigating a portion of this quartz porphyry, 

 I found a simple mineral to which 1 could not assign a name, never having seen it before. 

 The characteristics of this are as follow— lustre highly metallic, inclining to adaman- 

 tine— colour dark grey, nearly black— hardness between 7 and 8— fracture splintery- 

 structure lanuaated— specific gravity not numcricallj- determined, but high— crystalline 



