and Origin of the Diamond. 457 



" There is another circumstance to which I must advert, but I do so with 

 diffidence^ and under a hope that it will be considered merely conjectural. 

 Dr. Brewster supposes the diamond to have originated like amber, perhaps 

 from the consolidation of vegetable matter, and that it gradually acquired its 

 crystalline form by the influence of time, and the slow action of corpuscular 

 forces. The late Dr. Voysey adverted to this opinion in his account of the 

 diamond mines of Southern India ; and on the occasion of publishing an 

 abstract of that paper in his Journal of Science, Dr. Brewster observed that 

 he saw no reason to alter his opinion. Now, as the rock matrix of the diamond 

 of Panna appears, in some respects, though not altogether, to resemble that 

 of BanganpiUi in Southern India, there would seem to be little chance of 

 any conjecture being useful; still, however, as every opinion regarding the 

 origin of this fine mineral is as yet theoretical, I will not withhold what oc- 

 curred to me on this subject, though I again repeat that I offer it with great 

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

 quently recurred to me when examining the sandstone in which the diamond 

 is found : I thought that I could discern much in favour of it, and particu- 

 larly 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 shown that 

 crystals, such as those with which we are familiar in nature, may be pro- 

 duced by slow cooling, or other processes, according to the above theory, 

 may we not look to it also to account for the crystalhzation 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 ordi- 

 nary ability to answer its objections ; my part, however, is merely the sug- 

 gestion of a traveller, and I therefore conclude my paper by expressing a 

 hope that this important mineral may meet with more able investigation." 



