412 



REPORT 1867. 



The last column of the Table shows that a single observer would not count 

 more than a fifth part, nor four observers more than t-wo-tlnrds of the meteors 

 ■visible in a given period. 



2. Mr. 11. P. Greg " On Meteoric Showers and their Ifadiant-poiuts. (Bul- 

 letins de I'Academie Koyale de Belgique, 2nd ser. vol. xxiii. No. 2, 1867.) 



'•The meteoric shower of the 2nd of January 1S67, Avas far less copious 

 than it appeared on the same date in l^G-'j and 18U-4. There is not impos- 

 sibly^ a period of five years in its return, and a seven-year period in the returns 

 of the shower-meteors of the 5th-15th of December. 



" The linear or oval extension of the radiant region in the case of fifteen or 

 twenty meteoric showers, some them of long duration (six or eight weeks), 

 appears to arise from the change of the angle of intersection of the orbits of 

 the meteoric bodies with the earth's orbit. In the course of two mouths (a 

 sixtli part of the whole circumference) the angle of intersection, at the points 

 where the earth enters and leaves the meteoric group, should imd.»rgo a very 

 appreciable alteration. In cases of very long duration, it is probable that 

 the orbits of the meteoric bodies nearly coincide with a part of the earth's 

 orbit, and that the meteors of such a group move for some time nearly in the 

 same, or in an opposite direction to the earth's path. 



" Suppose A B to be a portion of the earth's orbit, 11 the apparent place of 



the radiant region, E', E" two positions of the earth at entering and leaving 

 the meteoric group, embracing between them an interval of two months, 



