Miscellanies. AOL 
18. Abstract of Mr. S. C. Walker’s paper entitled Researches con- 
cerning the Periodical Meteors of August and November, read before 
the Amer. Phil. Soc. Jan. 1841.—This paper contains—Ist, Tabular 
ae 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 
bers. ‘The convergent point, as far as noticed for the periodical 
ee meteors, is not far from the antipode of the earth’s tangential direction. 
ee The average relative velocities in table first, with the known convergent 
out points, for August and November, and other parts ofthe year, as far as 
#5 observed, afford on the cosmical theory, the most plausible estimate of 
_ the elliptic elements of the orbit of periodical meteors. The well-known 
formuls for computing these elements are stated; and the differential 
formule 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 roultitude of 7 
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. xir, No. 2.—Jan.—March, 1842. OE pce eee as 
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