3^4 Br'tt'ifh Mineralogical Soclefj. 



ajlero'tds the difcovervof fuch bodies in the heavens neccffarlly 

 requires a particular method of obferving, which hitherto aftro- 

 nomershave but fcldom purfued. On account of their minute- 

 nefs, they fo far lie bevond the power of good telefcopes to di- 

 flinguifli them, th:it Dr. Herirhel in his five ditferent reviews 

 of the zodiac detected none of thofc concealed objects; where- 

 as, had they Icfs refembled very fmatl tetefcopic flars, he muft 

 have infallibly detected them. It is therefore, he fays, only 

 by a dilieent and accurate attention to minute ftars, in the 

 view of difcovering amongft them fuch as may he in motlony 

 that afteroi'ls can fuccefsfully be dillinguiflied from the mul- 

 titudinous colleftion of telefcopical fiars which fo much 

 abound in ihe heavens. A fearch of this kind, from its na- 

 ture, cannot be carried on exxept in obfervatorics furnithcd 

 with fixed inftrunicnts, which, it is well known, make no 

 part of Dr. Hcrfchel's apparatus. In the conclufion of his 

 paper, honourable notice is taken of the affociation of twenty- 

 four aftronomers in Germany who have portioned out the 

 zodiac into as many parts, in order more eft'eAually to explore 

 it. As this new method of fearching, in the hands of Piazzi 

 and Olbers, fo quickly produced important difcoveries, Doftor 

 Herfchel thinks it highly probable that more celeftial bodies 

 of the clafs of afleroids remain concealed, which may fooner 

 or later be found out in confequence of their obferved motions. 

 On the 20th, the reading of a paper, by Richard Chene- 

 vix, Elq. on the chemical analyfis of corundum, was begun. 

 The chemical fafts delivered in this paper, with Count Bour- 

 non's mineralogical account of the fame fubftance, already 

 alluded to, will porfeft our knowledge refpecling corundum. 



BRITISH MINERALOGICAL SOCIETY. 



Defcnptton of the Satin Spar, by A. Alkin, 



The fatin fpar, charaAeriftic fpecimens of which have 

 been prefented to the fociety's cabinet by the late Mr. Mohr, 

 and Mr. Richard Phillips, is a mineral as yet peculiar to the 

 nei<^hbourhood of AKion Moor, in Cumberland, where it 

 lies fo near the furface as to be occafionally thrown up by 

 the plough. 



Its colour is a pure white, fometimes ftained by an ochrey 

 yellow tint of more or lefs intenfity. 



It occurs in thin ftrata from one to three or four inches 

 thick, traverfed by thin irregular feams of pyrites parallel to 

 the direAion of the ftratum. 



Its luftre is between pearly and fatiny, coufidcrably cha- 

 toyant. 



Its 



