*9<* Jtoyal Society of London* 



imported in the form of angular blocks, incrufted with hbti' 

 ore, with pyrites, and mica ; fubfbmces which ufually ac- 

 company the corundum from China. 



A catalogue of 506 new nebulae, nebulous ftars, planetary 

 nebulae, and clutters of ftars, was laid before the Society by 

 William Herfchel, LL.D. F. K.S.J and the preliminary re- 

 Marks on the eonftruetion of the heavens were alio read. 



Dr. Herfchel takes a very enlarged view of the iidereal 

 bodies compofing the univerfe, as far as we can conjecture 

 their nature; and enumerates a great diverfity of parts that 

 enter into the conftrtteiion of the heavens, referring a more 

 complete difcuflion of each to a future time. The firft fpecies 

 are infulated ftars ; as fuch the author confiders ouPfun, and 

 all the brighteft (tars, which he fuppofes nearly out of the 

 reach of mutual gravitation ; for, ftating the annual parallax 

 of Sirius at 1", he calculates that Sirius and the fun, if left 

 alone, would be 3$ millions of years in falling together; and 

 that the action of ftars of the milky way, as well as others* 

 would tend to protract this time much more. Dr. Herfchel 

 conjectures that infulated ftars alone are furrounded bv pla- 

 nets. The next are binary iidereal fvftems, or double ftars: 

 from the great number of thefe which are vifible in different 

 parts of the heavens, and the frequent apparent equality of 

 the two ftars, Dr. Herfchel calculates the very great impro- 

 bability that they ihouid be at distances from each other at 

 all comparable to thofe of the infulated ftars: hence he in- 

 fers that they muft be fubjected to mutual gravitation, and can 

 only preferve their relative diftances by a periodical revolu- 

 tion round a common centre. In confirmation of this in- 

 ference he promifes foon to communicate a feries of obferva- 

 tions made on double ftars, mowing that manv of them have 

 actually changed their fituation in a progreflive courfe, the 

 motion of fome being direct, and of others retrograde. The 

 proper motion of our fun does not appear to be of this kind, 

 but to be rather the effect of fome perturbations in the neigh- 

 bouring fvftems. The fame theory is next applied to triple, 

 quadruple, and multiple fyflems of ftars, and particular hy- 

 pothetical cafes are explained by diagrams. Some fuch cafes, 

 Dr. Herfchel is fully perfuaded, have a real exiftencc in na- 

 ture. The fourth fpecies confifts of cluttering ftars, and of 

 the milky way: the ftars thus difpofed conftitute maft'es,; 

 which appear brighter in the middle, and fainter towards the 

 extremities, being, perhaps, collected in a fpherical form. 

 Groups of ftars the author diftinguifhes from thefe by a want 

 of apparent condenfation about a centre of attraction ; and 

 clufters of ftars, by a much more complete comprefiion near 



fuch 



