94 RESEARCHES CONCERNING THE PERIODICAL 



compute the R. A. and Dec. of the points of nearest approach of this trial point 

 to the several planes in which the observed paths are contained. Then, if 

 there is any general tendency of the relative directions to one point in the 

 sphere more than to another, this circumstance will be indicated by the posi- 

 tion of the points of nearest approach, and the mean of these several positions 

 will afford an approximate convergent point, from which the actual convergent 

 point for the evening may be ascertained. As a trial point it appears most 

 natural to commence with the antipode of the observer's tangential direction, 

 this being the point towards which a tendency of the relative paths should 

 naturally be impressed. Indeed, if we suppose the meteors moving with all 

 varieties of true direction and velocity, a compensation of the latter should be 

 expected to take place, as has been found to be the case with the former ; and 

 the outstanding, uncompensated position of the convergent point should be, as 

 just stated, the point opposite the observer's true direction. The only ob- 

 servers, as far as I know, who have detected such a relative convergent point, 

 on ordinary nights, are Mr. Fitch, of New Haven, ^^ who found this point to 

 advance in the ecliptic from August to December, remaining always about 90° 

 in advance of the sun, or 90° in arrear of the earth, and Mr. E. C. Herrick^^ 

 and others, who noticed the same phenomenon in April, 1839. Professor For- 

 shey,^' of Mississippi, who has given much attention to this subject, and C. L. 

 Von Littrow,^" adjunct at the Imperial Observatory of Vienna, who nightly 

 traced the paths of meteors for nearly a year, from 1837 to 1838, speak of the 

 existence of a convergent point as being peculiar to the dates of August 

 9th — 12th, and Nov. 11th — 13th. Also, Olbers" makes the prevalence of pa- 

 rallelism of paths and a radiant point in Leo the distinguishing feature of the 

 November phenomenon of 1838, these being present on the 13th,^ but not on 

 the 12th of that year. Nor do I read of any other authors but Messrs. Fitch and 

 Herrick, and their associates, who have discovered this motion. The a priori pro- 

 ' bability of the tendency towards such a convergent point, by the meteors seen on 

 ordinary nights, is so great that it is next to a miracle that it should not occur. 

 In case of its occurrence, the average discrepancy of the single results from 



87 Sill. vol. xxxiii., p. 386. as Letter received from Mr. Herrick. 



''s Mentioned in conversation, August, 1840. ^o Annalen, &c., 1838, p. xvii. 



" Astr. Nachr., 372. 



