VOL. XLIIlJ PHILOSOPHICAL TRANSACTIONS. 147 



either side, but directly upon his limbs like the camel, and that he rises as sud- 

 denly as that beast. There is something vei-y particular in his voice, which imi- 

 tates the creaking noise of a child's rattle, or the croaking of some birds, rather 

 than the voice of any quadruped except the deer, which exhibits something like 

 it in rutting time. 



Of certain perfect minute Crystal Stones. By J. Parsons, M.D., F.R.S. 



N° 476, p. 468. 



Fig. 12, pi. 2, represents a small crystal magnified. It is one of a great num- 

 ber brought by a very curious gentleman from Gibraltar, who has caused many 

 of them to be set in buckles of different kinds, for the wear of his lady and him- 

 self: and though they are not polished by art, yet they look very bright, and 

 produce a very good effect in the buckless. 



They were found accidentally. This gentleman saw a man cleaving a rock 

 near that town, and observed a great quantity of fine black powder fall from its 

 crevices ; which he examined, and found these little stones in clusters, consisting 

 of no more than 12 or 14 each ; and each cluster lying at considerable distance* 

 from one another. They are all of the same form, some less perfect than others, 

 and are in general hexagonals. 



Concerning the specific Gravity of Diamonds. By Mr. John Ellicot, F. R. S. 



N° 476, p. 468. 



From some experiments Mr. E. made, it appears highly probable, that what 

 has formerly been published concerning the specific gravity of diamonds, is not 

 to be depended on. Those in Mr. Boyle's works he thinks very erroneous, and 

 the specific gravity too low. 



The scales in which the diamonds were weighed by Mr. E. turned very sen- 

 sibly with the 200th part of a grain ; and as one of the diamonds weighed above 

 92 grains, it was capable of being weighed to less than the 1 8000th part : several 

 of them were weighed twice over both in water and air, and the weights found to 

 agree to the greatest exactness ; and if to this is added the very near agreement 

 of the weights of the several diamonds, though weighed at different times, and 

 at a considerable distance from each other, he thinks it highly improbable, that 

 there could be any considerable mistake in these trials ; and therefore their spe- 

 cific gravities, as in the following table, may fully be depended on. 



He sets down the weights of the several diamonds both in air and water, that 

 if any mistake should have happened, it may be the more easily rectified. 



u2 



