98 RESEARCHES CONCERNING THE PERIODICAL 



that degree of plausibility which naturally belongs to the statements quoted 

 from Olbers and Quetelet, respecting the relative velocities of meteors in ex- 

 traordinary showers, and the coincidence therewith of the single instance of 

 relative velocity for one of the November meteors computed by Professor 

 Twining. I shall here subjoin the principal data which we possess concern- 

 ing the convergent point for the extraordinary displays of August 9th — 11th 

 and November 11th — 13th. The angle of deflection of the former from the 

 theoretic convergent point for isolated meteors is 39°.4; that of the latter only 

 8°.2, a quantity not much exceeding the probable error. So that one impor- 

 tant criterion of extraordinary character is wanting in the November period, 

 namely, a well marked and manifest deflection of their convergent point 

 from that of isolated and promiscuous meteors. The convergent point of 

 the "meteoric abundance," so called, of December 7th, 1838, was found by 

 Mr. Herrick" to be nearly the same as that of the August period. This 

 would give a deflection of 104° from the point opposite the observer's direc- 

 tion. As this phenomenon is not known to have presented itself before nor 

 since, it may, perhaps, be considered as an example of an isolated cluster of 

 these bodies having common elements of motion in a plane highly inclined to 

 the ecliptic, in a period which we have no means of estimating, since the want 

 of corresponding observations concerning the relative velocity of any one of 

 these bodies leaves us in doubt how far these velocities were conformable with 

 those of Table I. One consequence follows, however, from this high angle of 

 deflection, that the mean normal velocity of the cluster could not have been 

 less than that of the observer, and that the single bodies must have been 

 superior planets. An attempt will be made to deduce the most plausible esti- 

 mate of the elements of the asteroids of August and November, after discussing 

 the circumstances connected with the question of their anniversary returns. 



3^ Sill. XXXV., p. 363. Perhaps a part of the same cluster or ring was seen by Benzenberg, in 

 1798, on the 6th of December. The uncertainty concerning the convergent point prevents us 

 from deciding. If this point were common, a period of forty years would give a relative velocity 

 of about 1 1 geographical miles per second. 



