METEORS — WHIPPLE 



249 



were ejected from the comet approximately 5,000 years ago and 

 another group more recently, about 1,300 years ago. It is not entirely 

 clear whether these ejections represent unusually rapid disintegra- 

 tions of the comet at those times, possibly by asteroidal collisions, or 

 whether the perturbing action of Jupiter has been such as to make 

 it possible for us now to observe only those meteors that were ejected 

 at those two times. The latter hypothesis appears to be the more 

 likely. 



Table 1. — Comets and associated meteor streams 



Comet stream 



(A.U.) 



P 



(yrs.) 



Orbital elements 



le 



1861 I. 

 Lyrids. 



1910 II_— 

 ■q Aquarids 

 Orionids..- 



1951 c 



June Draconids 



1862 III. 

 Perseids. 



1946 V 



October Draconids 



1950 e 



Taurids (N) 



Taurids (S) 



Arietids (S) 



p Taurids (Day) 

 f Perseids (Day) 



1866 I__ 

 Leonids. 



1852 III 



Andromedids. 



1917 1 



Monocerotids. 



0.921 

 0.918 



0.587 



0.542 



1. 159 



0. 963 

 0.951 



0.996 



0.338 

 0.320 

 0. 372 

 0.296 



0. 977 

 0. 985 



0. 861 



1939 X. 

 Ursids. 



0. 190 

 0. 186 



1.022 

 0.915 



415. 

 >50 



76.0 



21. 4 



6. 1 



119. 6 

 95. 1 



6.6 



3.30 

 3. 13 



3.49 

 2. 64 



33.2 

 37.5 



6.6 

 6.6 



145. 3 



0. 983 

 0. 969 



0.967 



0.930 



0. 654 



0. 960 

 0. 955 



0.72 



0. 847 

 0.849 

 0.835 

 0.845 



0.905 

 0.918 



0.756 



213?4 

 213. 9 



111.7 



86. 8 



170.4 



152.8 

 151.2 



171. 8 



185.2 

 298. 4 

 111. 9 

 122.2 



171.0 

 173.7 



223. 3 



29? 9 

 31. 8 



57.3 



29. 8 

 94.3 



137.5 

 138. 1 



196. 2 



334. 7 



221. 8 



45. 1 



27. 2 



231. 4 

 235.0 



245.9 



79? 8 

 79.9 



162.2 



163.2 



21. 7 



113.6 

 113.7 



30.7 



12. 4 

 3.2 

 5.4 

 6.0 



162. 7 

 162. 5 



12. 6 



13. 6 



14. 37 



0.993 

 1.002 



0.821 

 0.845 



121.3 

 128. 2 



207.0 

 212.2 



87. 5 

 81.6 



269. 8 

 264.6 



32.7 

 35.2 



54.7 

 52.5 



243? 4 

 245. 6 



169.0 



116. 5 



264.7 



290.2 

 289. 3 



159.9 

 160.2 

 156. 9 

 149. 5 



42. 4 

 48. 7 



109. 1 



208.8 

 209.9 



116.8 

 116.8 



Orbital elements for the comets: Baldet and de Obaldia (1952). 

 Orbital elements for the meteor streams: Whipple (1954). 



