On the primitive Crystals of Carbonate of Lime. 455 



the descent on the other side was immediate, and as steep 

 as the one we had ascended ; but Lv throwing our legs 

 across it, as would be done on the ridge of a house, and 

 moving ourselves forward by our hands, we at jeno-th 

 reached that part of it where it gradually widened itself and 

 formed the summit of the chff, which we found to have a 

 perfectly flat surface, of the dimensions before stated. 



Judging this to be the most conspicuous situation, we 

 here planted the Union, and left a bottle sealed up contain- 

 ing a small account of the origin of the island, and of our 

 having landed upon it, and naming it Sabrina Island, 



Within the crater I found the complete skeleton of a 

 guard -fish, the bones of which being perfectly burnt, fell 

 to pieces upon attempting to take them up; and bv the 

 account of the inhabitants on the coast of St. Michael's, 

 great numbers of fish had beta destroyed durinsr the early 

 part of the erupt on, as large quantities, probably^suifocated 

 or poisoned, were occasionally found drifted into the small 

 inlets or bays. 



The island, like other volcanic productions, is com- 

 posed prmcipally of porous substances, and generally 

 burnt to complete cinders, with occasional masses of a 

 stone, which I should suppose to be a mixture of iron and 

 lime-stone; but have sent you specimens to enable you to 

 form a better judgement than you possibly can by any de- 

 scription of mine. 



LXX. On the primitive Crystals of Carbonate of Lime, 

 Bitler-Spar, and Iron-Spar. By William Hyde Wol- 

 LASTON, M.D. Sec. R.S.* 



W HKN I formerly described to the society a goniometer f 

 upon a new consfi-uction for measuring the angles of cry- 

 stals, I expressed an expectation that we should thereby be 

 enabled to correct former observations made by means of 

 less accurate instruments, I took occasion to mention one 

 instance of inaccurate measurement in the primitive angle 

 of the common carbonate of lime; and I have had itie sa- 

 tisfaction to find the necessity of a correction, in that in- 

 stance, confirmed by Mons. Mains, and admitted by the 

 Abbe Haiiy, in a work I published nearly at the same time. 



• from the Phi'osopJiical Trniisaclions fnr 18 "2, part i. 

 f Bhilosophlcal Transactions for I «()9. See Phil M.■^^,^ vol. xxxv. p.91. 

 J 'Isli!ea\i Comparatif des Ki'iultate de ia Crysiallograihieel de I'Analysf 

 Chimique. ' 



It 



