1889.] of the various Species of Heavenly Bodies. 161 



In some irons, such as Zacatecas, they exist as big as walnuts, 

 firmly adherent, but they can be separated ; inside these are balls of 

 troilite often firmly embedded, so that on breaking the meteorite they 

 will divide, but in other cases so loose that they fall out, and they are 

 smooth enough to roll off a table. 



Sometimes chondroi have smaller ones sprinkled in them, sometimes 

 dark chondroi have white earthy kernels. 



In some cases these chondroi are so plentiful as to form nearly the 

 whole mass of the meteorite. They are often perfectly round, but 

 not always, and they are so often so loose that they tumble out and 

 leave an empty smooth spherical cavity. 



The stones chiefly consist of such chondroi and their debris. 



He adds that each magnetic chondros "is an independent crystal- 

 lised individual it is a stranger in the meteorite. Every chondros 

 was once a complete, independent, though minute meteorite. It is 

 embedded like a shell in limestone. Millions of years may have passed 

 between the formation of the spherule and its embeddal." 



He finally remarks that the chondroi of meteorites indicate a con- 

 densation of innumerable bodies such as we see must exist in the case 

 of comets ; further, that they have been formed in a state of unrest 

 and impact from all sides. Many meteorites are true breccias ; they 

 have many times suffered mechanical violence : in comets we have 

 seen precisely the conditions where such forces could operate, and 

 hence he arrives at the view that ; ' comets and meteorites may be 

 nothing else but one and the same phenomenon." 



Schiaparelli* in 1886 showed the probability that comets, with 

 which he had identified certain recurring streams of shooting stars, 

 were swarms of meteorites drawn from the depths of space by the 

 attraction of the outer planets of the solar system or by the general 

 attraction of the system itself. 



Schiaparelli did not look upon the head of a comet as a swarm of 

 meteors as Reichenbach did, but regarded it as the largest meteorite 

 in the stream which produced the star-shower. " Nous voici done 

 arrives a cette consequence veritablement inattendue, que la grande 

 comete de 1862 n'est autre qu'une ties Perseides du mois d'Aout, et 

 c'est probablement la plus considerable de toutes."f 



Professor Tait in 1869, supporting the opinion of Reichenbach, 

 showed that the cometary phenomena to which Reichenbach had 

 called attention could be mechanically explained by the assumption 

 of a cloud of meteorites. 



He writes : " The principal object of the paper is to investigate 

 how far the singular phenomena exhibited by the tails of comets, and 

 by the envelopes of their nuclei, the shrinking of their nuclei as they 



* 'Lea Mondes/ vols. 12 and 13, 1886. 



f Schiaparelli, ' Les Mondes,' vol. 13, p. 76, 1867. 



