A. MATHEMATICS AND ASTRONOMY. 45 



two or three were discordant from the others to such an ex- 

 tent that but little weight could be attributed to them. 

 The linear length of the visible path in the atmosphere was 

 sixty-two geographical miles, the initial point of which was 

 twenty -two miles above the earth's surface, while its end 

 was four and a half miles high. The meteor moved nearly in 

 the plane of the ecliptic, and was approaching the sun at the 

 time that it passed through the earth's atmosphere, cutting 

 the earth's radius vector at an angle of forty-five degrees, the 

 curve of its orbit being that of a hyperbola, and its velocity 

 being somewhat slower than that of the ordinary shooting- 

 stars. The detonation that accompanied this meteor was 

 heard to a distance of forty miles, being most intense in the 

 neighborhood of the end of its path, where at nearly every 

 station it was reported as like the long rolling sound of 

 thunder. Jahresbericht der Schlesischen GeseUschaft, 1874. 



TWO GROUPS OF NOVEMBER METEORITES. 



Professor Kirkwood, of Indiana, communicates to the En- 

 glish journal Nature some remarks on the meteors of No- 

 vember 14, known as the Leonids, because their radiant 

 point is in the constellation of Leo. According to Professor 

 Kirkwood, there are indications of the existence of two dis- 

 tinct and widely separated clusters of meteors moving in or- 

 bits very nearly identical, and having therefore very nearly 

 the same radiant point. The principal cluster is that whose 

 appearance at intervals of 33j years was first demonstrated 

 by Professor Newton, while the second group, according to 

 Kirkwood, has a period of 33^ years. He suggests that if 

 these two clusters are originally derived from the same me- 

 teor cloud, then there must have been a considerable dis- 

 turbance in their orbits caused by the attraction either of 

 Uranus or of the earth. He cites nine recorded displays of 

 meteors indicating the existence of the second cluster. The 

 first of these occurred in the year 288, and was observed in 

 China on the 28th of September. 12 A, XII., 85. 



encke's comet. 



Dr. Van Asten, already known by his profound investiga- 

 tions into the movements of Encke's comet, announces that, 

 having lately come into the possession of a number of obser- 



