Miscellanies. 401 



18. Abstract of Mr. S. C. Walkerh paper entitled Researches con- 

 cerning the Periodical Meteors of August and November, read before 

 the Amer. Phil. Soc. Jan. 1841. — This paper contains — 1st, Tabular 

 statements of the relative velocities derived from corresponding obser- 

 vations of the same meteor at different stations, chiefly from Quetelet's 

 Catalogue. 2d. A catalogue of remarkable appearances of shooting 

 stars, also from Quetelet, with additions. 3d. Bessel's position of the 

 earth, in the ecliptic, at the date of the principal November showers. 

 4th. The convergent points hitherto observed for the relative paths of 

 the meteors of August, and 5th. Of those of November. The term pe- 

 riodical is restricted to the meteors, which, at a particular season of the 

 year, tend towards the convergent point for that season. Sporadic is 

 applied to the unconformable meteors seen on the same occasions. 

 Extraordinary showers of the second table are placed in the former 

 class, and are considered as differing from periodical meteors only in 

 numbers. The convergent point, as far as noticed for the periodical 

 meteors, is not far from the antipode of the earth's tangential direction. 

 The average relative velocities in table first, with the known convergent 

 points, for August and November, and other parts of the year, as far as 

 observed, afford on the cosmical theory, the most plausible estimate of 

 the elliptic elements of the orbit of periodical meteors. The well-known 

 formulae for computing these elements are stated ; and the differential 

 formulse are investigated for computing the probable errors of such ele- 

 ments, arising from errors of the relative velocities and directions de- 

 rived from the foregoing tables. The most plausible elements of the 

 periodical meteors, are thus found to have their perihelia inferior to that 

 of Mercury, and hence are only seen by us when near their aphelia ; 

 the orbits being necessarily very eccentric, or flattened, and their incli- 

 nations very great. Since many millions of these bodies are annually 

 encountered by the earth, including chiefly those which move in orbits 

 having small parameters, analogy leads to the inference, that the plan- 

 etary spaces inferior to Venus, abound in these bodies, of which only 

 a small proportion ever reach the earth's mean distance, or become 

 visible to us. This suggestion of a far greater aggregation of these 

 bodies near the sun, is supported by the analogy of the resisting medium 

 encountered by Encke's comet, which is only sensible at a distance 

 from the sun below that of Venus. Bessel's objections to the theory of 

 the resisting medium, that it is indicated by no other phenomenon in 

 nature, may be in some degree obviated by this analogy ; since a very 

 thin, light body, might be sensibly resisted by a great multitude of these 

 small meteors or asteroids, though their effect is insensible on Mercury 

 and the other primaries, owing to their superior mass and density, and 

 as Encke remarks, also insensible on Halley's and Biela's comets, 

 Vol. xLii, No. 2.— Jan.-March, 1842. 51 



