( 642 ) 



'! = « I /n I 



01' when 



\.\<Lim \y/~. 



Now 



Lim I / 1= Ltm 2 I / 



l^ ./;,+! y Dn 



therefore 



//,... ^,4-1 D„-\ ( u 



Lim = — 



Dn \1 



b^ . . . 6„+i .b^...h„ D„-o 

 Lim = — etc. 



Dn 



and finally 



1 =:. -^^ ^^ 1- ^ ^ etc. 



è, 2 .' ;>,6, ^ 3 .' b,b,b. 



Hence it is evident that « is a root of the equation I' (c) =: as 

 might be expected. 



Astronomy. — "Researches on the orbit of the periodic comet 

 Holmes and on the perturbations of its elliptic motion." By 

 Dr. H. J. ZwiERS. (Communicated by Prof. H. G. van de 

 Sande Bakhuijzen.) 



In 1902, after the reappearance of the comet Holmes in 1899 — 

 1900 I published in full the i-esults which I had derived from the 

 investigation of the observations after its return. ') With the most 

 accurate elements which I had been able to deduce from its appearance 

 in 1892 —93 I had calculated in advance the perturbations arising 

 from the action of Jupiter and of Saturnus and at first also of 

 the earth and thence I have derived a system of elements for 1899 

 September 9.0 mean time Greenwich, which served as a basis for 

 an ephemeris published in No. 3553 of the Astron. Nachrichten. 

 By means of this ephemeris the comet has been rediscovered at 

 the Lick Observatory and the relatively small ditference between the 

 observed and the computed place proved that the elements of the 



') Recherches sur I'oibite de la comète péiiodique de Holmes et sur les perturbations 

 de son mouvement elliptique, par Dr. H. J. Zwiers. Deuxième mémoire. Leyde, 

 E. J. Brill, 1902. 



