122 CELESTIAL PHENOMENA. 



spheric origin of aerolites, do not appear (o me to have 

 much force. I would here refer to a remarkuble conversation 

 which took place between Newton and Conduit at Ken- 

 sington (s 5 ), and ask, why should not the substances be- 

 longing to one group of cosinical bodies, or to one planetary 

 system, be for the most part the same ? Why should it 

 not be so, if we permit ourselves to surmise that the 

 planets, and all the spheroidal masses which revolve 

 around the sun, have been formed by the gradual condensa- 

 tion of revolving rings of gaseous matter, separated from the 

 once more extended solar atmosphere ? We are, it seems 

 to me, no more entitled to call nickel and iron, olivine and 

 augite, which we find in meteoric stones, exclusively terres- 

 trial substances, than I should be to call plants which grow 

 wild in Germany, and which I might also meet with beyond 

 the Oby, " European species of the flora of Northern Asia." 

 If, in a group of cosmical bodies, the elementary substances are 

 tiie same, why should they not form determinate compounds 

 in accordance with their mutual affinities and attractions, as 

 in the polar regions of Mars resplendent domes of snow and 

 ice, and in other smaller cosinical masses, mineral aggrega- 

 tions, containing crystals of olivine, augite, and labradorite ? 

 Even in the field of what must necessarily be conjecture, its 

 course must not be arbitrary, or irrespective of induction. 



Extraordinary obscurations of the sun's disk have occa- 

 sionally taken place, so that stars have been seen even at 

 midday. A phenomenon of this nature, not to be explained 

 by a cloud of volcanic ashes, or by a fog of unusual elevation, 

 occurred in 1547, at the period of the eventful battle near 

 Miihlberg, and continued during three entire days. They were 

 attributed by Kepler, at one time to a " materia cometica, ' 



