86 
being- about tlie 13th November, and the 10th August. Smaller 
manifestations of the same phenomenon are believed to recur be¬ 
tween the 22nd and 25th April, the 6th and 12th December, and 
about the 17th July. With regard to the origin of meteorites, the 
hypothesis has been put forward that they are derived from the 
vapours given off during the ebullition of the sun’s atmosphere, 
which it is supposed become condensed into a sort of lenticular disc 
perpendicular to the sun’s axis of rotation, and giving rise to the 
phenomenon known as the Zodiacal light. By further condensation 
in the interplanetary space, the metallic and other elements thus 
thrown off from the sun, are believed gradually to form the nuclei 
of meteorites, and the chemical constitution and interned structure 
of those which every now and then reach the surface of the earth 
would seem, according to Mr. Sorby, to support this view of them 
origin. 
