?i.'pt. 2, 1S1>_\] 



269 



PROCEEDINGS 



[ Kii kwfXMl. 



AMERICAN PHILOSOPHICAL SOCIETY, 



HELD AT PlIILADELPRIA, EOR PROMOTING USEFUL KNOWLEDGE. 



Vol. XXX. 



December, 1892. 



No. 139. 



On the Mutual Relations Between the Orbits of Certain Asteroids. 



By Daniel Kirkwood, Rirerside, Cal. 

 {Read before the American Philosophical Society, September S, 1S92.) 



The present -n'riter, several years since,* called attention to the fact that 

 in some parts of the asteroid zone the orbits of particular members have 

 a striking resemblance to each other. These significant coincidences have 

 been regarded by astronomers as worthy of study, and, in addition to the 

 binary and ternary clusters pointed out by the writer, others have been 

 designated by Tisserand,f of Paris, and by Monck, of Dublin.:]: These 

 groups, according to the former, cannot be regarded as chance arrange- 

 ments. "A glance at the list," says Mr. Monck, "will show that the 

 resemblance frequently extends beyond a single pair and embraces what 

 may be called a family — a circumstance which is known to occur in the 

 case of comets also." The writer's list (which might be extended) is as 



follows : 



GROurs OP Asteroids. 



Names. a e i tt 



Huberta . . . 

 Hermione . . 



3.4586 

 3.4535 



II. 



K106) Dione...... 3.1670 



(104) Clymene . . . 3.1500 



(171) Ophelia 3.1554 



(62) Erato 3.1241 



(287) Silesia 3.1190 



(212) Medea 3.1157 



(86) Semele 3.1015 



(305) 3.0973 



(345) Vera 3.0960 



(323) Rosa 3.0937 



L(263)Adorea 3.0853 



*1887. tAnnuaire, 1891. 



PROC. AMER. PIIILOS. SOC. XXX. 139. 



0.1103 

 0.1255 



0.1788 

 0.1407 

 0.1143 

 0.1756 

 0.1217 

 0.1013 

 0.2193 

 0.1927 

 0.1975 

 0.1306 

 0.1385 



38 

 53 

 33 

 12 

 40 

 16 

 47 

 26 

 11 

 59 

 25 



3290 

 357 



25 



62 

 148 



39 



65 



66 



29 

 104 



27 

 106 

 184 



45' 

 36 



57 

 30 

 31 

 

 16 

 18 

 10 

 37 

 48 

 35 

 48 



X Sid. Mess., October, 1888, p. 334. 

 2l. PRINTED JAN. 3, 1893. 



