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RESEARCHES CONCERNING THE PERIODICAL 



1832, and 1833, may or may not have been parts of the same extensive nebula, 

 or elliptic ring, or lens, having the sun in the focus of the orbit of each indivi- 

 dual. On this point we are unable to decide, for want of knowledge of the 

 deflection of the peculiar convergent points of the groups of 1799, and 1832". 

 If the deflection of this convergent point had been known to be very differ- 

 ent on these occasions, we should naturally pronounce them to have been 

 different and independent groups. On the contrary, if this deflection had 

 been known to be common, the probability of their being different portions of 

 the same group, ring, or lens would be much increased, and would be a ne- 

 cessary conclusion, unless we admit, which I think is extremely improbable, a 

 promiscuous character in their true directions and velocities, making a perfect 

 compensation of normal velocities, and resolving the supposed deflection of 8° 

 into the errors of observation. In fact, to suppose a perfectly promiscuous 

 character in the elements of motion, of such multitudes of bodies, and that 

 after revolving around the sun for so long a term, they should by mere acci- 

 dent exhibit at the same period of the year, and same portion of space, three 

 such brilliant displays as those of 1799, 1832, and 1833, is to assign an effect 

 without a cause. 



5. Isolated groups, like that of December 7th, 1838, having no established 

 anniversary or periodical character, but a great normal velocity, may be re- 

 garded as clusters of these small superior asteroids, having common elliptic 

 elements, for whose approximate determination no other datum is wanting but 

 the relative velocity of the group. 



6. The display of the 10th of August, if witnessed only once, would lead to 

 a conclusion similar to the preceding for December 7th, 1838. But when we 

 consider that the same phenomenon is recorded for more than half the anniver- 

 saries of this century, and in every instance, when carefully observed, has ex- 

 hibited the same true mean normal velocity and direction of motion, and the 

 same node, and radius vector; it becomes far more worthy of the consideration 

 of astronomers, and some law of distribution of the individuals composing these 

 groups, and of the groups themselves, is required to explain these remarkable 

 coincidences. Here all the peculiarities of periodical meteors are shown in 

 their greatest perfection. The uniformity in their relative directions indicates 



^* Olbers considers the character of parallelism of paths, of the bodies composing the displays of 

 1799, 1832, and 1833, to have been common to the three displays. . 



