122 DIAMOND MINES OF PANNA, &c. 



The theory of Sir James Hall on the consolidation of strata fre- 

 quently recurred to me when examining the sandstone in which the dia- 

 mond is found ; I thought that I could discern much in favour of it, and 

 particularly in the gradual changes of its nature, from the lower to the 

 upper strata ; now if the principle of this theory is admitted to be correct 

 and applicable universally, it follows of course that it must be applied here ; 

 and then it may be questioned, how the diamond was preserved, under that 

 *degree of heat which must have been necessary to form its matrix the 

 gritstone ? In answer to this objection I suggest, that, the circumstance 

 of calc spar occurring in trap rocks is somewhat analogous, and if it is 

 admitted that compression under the weight of strata, and a superincumbent 

 ocean, had the effect of resisting the expansion of its carbonic acid and 

 constraining it to continue in combination with lime, might not the same 

 principle be reasonably enough applied, to account for the preservation 

 and detention of the elements of the diamond in the gritstone ? and again, 

 should it be further shewn that crystals, such as those with wJiich we 

 are familiar in nature, may be produced by slow cooling or other processes 

 according to the above theory, may we not look to it also, to account for 

 the crystalization of the gem ? 



This conjecture rests upon the truth or fallacy of Sir James Hall's 

 theory, or, on a modification of it, and when this theory is considered as 

 the result of long and patient experiment, and the high reputation of its 

 author is taken into account, it will require something more than limited 

 observation, or ordinary ability, to answer its objections ; my part, how- 

 ever, is merely the suggestion of a traveller, and I therefore conclude my 

 paper by expressing a hope, that this important mineral may meet with 

 more able investigation. 



VI. 



* See the Note appended to the article of Panna mines, p. 106, of this volume. 



