188.3.] "i-^' [Kiikwood. 



The phenomenon of 1813 was the most brilliant of this series observed 

 in recent times. The interval between 585 and 1813 is 1238 years, or 

 thirty-seven periods of 33.19 years ; and the whole series of phenomena 

 are represented as follows : 



From 585 to 1582 ... 997 y = 30 periods of 83.23 years. 

 1582 to 1813 ... 231 y = 7 " 33.00 " 



1813 to 1847 . . . 33.19 = 1 period of 33.19 " 

 1847 to 1880. .. 33.19 = 1 " 33.19 " 



The observed shower of 1582 was probably near the close of the cluster's 

 passage across the earth's orbit. Thirty times the mean period of 33.19 

 years gives the epoch 1581.56, and the remaining dates are then perfectly 

 harmonized. 



The respective periods of the comet and the three meteoric groups are 

 as follows : 



Tempel's comet 33.28 years. 



Group A. (Newton) 33.25 " 



Group B 33.31 " 



Group C 33. 19 " 



During the last five hundred years the period of Group A seems to have 

 been rather more than 33.25 years. The meteoric display of 1366 was con- 

 temporaneous, or nearly so, with the apparition of the comet, and the 

 complete separation of this cluster from the original mass may have then 

 occurred. "The comet of 1866 was invisible to the naked eye; that 

 of 1366, seen under similar circumstances, was a conspicuous object. The 

 statement of the Chinese historian that ' it appeared nearly as large as a 

 tow measure,' though somewhat indefinite, certainly justifies the conclu- 

 sion that its magnitude has greatly diminished during the last 500 years."* 

 Is the less apparent magnitude a consequence of separation at that epoch ? 



The following table aflords the means of comparing the elements of the 

 comet and those of the principal meteoric group : 



Nov. Meteors. Tempel's Comet. 



Perihelion passage Nov. 10, 1866. Jan. 11, 1866. 



Longitude of perihelion 56° 26' 60° 28' 



Long, of ascending node 231° 28' 231° 26' 



Inclination 17° 44' 17° 18' 



Perihelion distance 0.9878 0.9765 



Eccentricity 0.9046 0.9054 



Semi- major axis 10.3400 10.3240 



Period 33.2.500 y. .33.1760y. 



Motion Retrograde. Retrograde. 



Computer Schiaparelli. Oppolzer. 



The orbit of Tem-pel's comet and of the meteors associated with it is 

 * Comets and Meteors, p. .32. 



