670 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



5. The phenomena of the star in Corona appear to show that in 

 this ol)ject, at least, great physical changes are in operation. 



6. There exist in the heavens true nebulae. These objects con- 

 sist of luminous gas. 



7. The material of comets is very similar to the matter of the 

 gaseous nebulre, and ma}'- be identical with it. 



8. The bright points of the star clusters may not be in all cases 

 st^ars of the same order as the sep.arate bright stars. 



It may be asked what cosmical theory of the origin and relations 

 of the heavenly bodies do these new facts suggest. It would he 

 eas}?^ to speculate, but it appears to me that it would not be philo- 

 sophical to dogmatize at present on a subject of which we know 

 so little. Our views of the universe are undergoing important 

 changes. Let us wait for more facts, with minds unfettered by 

 any dogmatic theorj^ and therefore free to receive the obvious 

 teaching, whatever it may be, of new observations. 



The Diamond. 

 This precious gem, consisting of pure carbon, is generally asso- 

 ciated with a quartose rock called itacolumite, from Itacolumi, a 

 mountain in Brazil. It is a kind of sandstone which often con- 

 tains talc, chlorite, and mica. A thin strip of it will sometimes 

 bend without breaking, and is known by the common name of 

 flexible sandstone. Diamonds have been found in Brazil, India, 

 Borneo, Russia, and occasionally in North Carolina, Georgia, and 

 Virginia. With regard to their formation, Dr. Percy, in a late 

 lecture, said : "The question is, if this itacolumite be, as there 

 is no doubt it is, a rock of sedimentary origin, have the diamonds 

 been developed in the rock, by some means or other, subsequent 

 to its formation, or were they deposited there cotemporaneously 

 with it ?" That is the point, and so far as he knew, it is a point 

 which has not been clearly made out at present. All attempts 

 concerning the artificial production of the diamond have hitherto 

 proved most singularly abortive, and we have not the slightest 

 clue in the world to the mode in which the diamond has been made 

 in nature. It is evident that the condition or conditions of its 

 formation must be excessively rare, because the quantity of dia- 

 monds is, comparatively speaking, so small. He could not help 

 thinking — and it is the opinion of those who have directed atten- 

 tion to this subject — that one day or other we shall be able to crys- 

 tallize carbon; but it does not follow that we should be able to 



