PKOCiRKSS OF ASTRONOMY FOR 1891 AND 18{)2. 701 



la's coiiM't (iv in l.ss'.t \ : but iiincli iiioic tor siii)]i(isiii,ii- thai similar Ix'- 

 lia\ior may he common, in greater or loss de.^rco. escai)in,ii' attention 

 ordinarily from the (lifticuit \' of pliotomctric comparisons in tliccascof 

 isolated comets, butcasily attracting the e\e. by contrast, when two 

 objects nearly alike are in tin' same tield." 



Mr. Chandler's discussion of the orbits of these com pan ions est aid itches 

 the important j)ro[)osition that liie foice wnicli led to the separation of 

 the components A and (', whatexcr its nature, o]»erated in tlie plane of 

 the comet's orbit, and |)ro(bice(l no chan<ie in that })lane or in the form of 

 the conic section, but only in its size, and in the direction *4' its major 

 axis. With reference to the identity with JjexeiPs comet. Air. Chaiidlei- 

 sees 110 suflicient reason in the differences of the i)eriod of revolution 

 (28. IS years, accoidinj;- to ^Nlr. Poor, instead of -7 years) to reject the 

 sn|)position ; it is necessary to carry the computation of the pertui'ba- 

 tions a little larther back. 



Comet IS!K( II. — The last observation in iSl»] was on iVlay -!» by Si)it- 

 aler at ^'ienna; Imt it was aiiain favorably situated in -lanuary and 

 i'\'bruary, ISD'J, ami was observed at Xice up to Fi'bruaiy I, IS!)!', 



Conu't l.SDl I : DiscoMMcd by J>arnard at the Lick Observatory on 



-Couu-t a I8!n. :\l;ii<.h 20. 18!>1, and independently hy l)ennin«>- at 

 Bristol on ^lar<'h -ii). It w as (|uitebi\^ht, tenth to eleventh magiiituch', 

 about 1' in diameter and with a tail 10' to .'>0' long. At the time of dis- 

 covery its position was a':;.^ !.■)''->, (5- -f-45°; i! moved rapidly south, 

 increusing- in briUiancy, ami was followed alter perihelion till duly, tlie 

 last observation ha\ing api»arently been obtained at Cordoba <»:i July 

 l>, 1801. 



Comet l.Sid II: I'irst detected upon this its second api>earance by 



CoiiK-t h isiti. Spitaler. of \ienna. on May 1, 1891. and by Bar- 



^('omct 1884 111. nai'd on .Alay o, its position agreeing closely with 

 z^VVolfs comet. , |^],(. (>])], emeris. It was at hrst small and f.unt, 

 but in August it liad a 1>riglit nucleus of tin- elexenth magnitude, with 

 coma of iV to 4' diameter: it decreased in brightness again alter the 

 middle of October, but was observed till March ;>1, 18!»2. I'.arly in 

 ►Septeml)er the cs)met ])assed oxer the groU]» of the Pleiades, and the 

 ♦•ircumstance was taken ad\ antage of by a nundx-r ot astionomers to 

 determine whether the light from these stars underwent any refraction 

 in ])assing through the material of which the comet was composed. 

 The results ol)taiiH'd were for the most part negative, with the i»ossibIe 

 excepti(»n of an ol)ser\ation l»y IJurnlnim on vSeptembei' 2, when the 

 difference of de<-liuat ion lielwcen 21 and 22 Asterope seemed to show 

 some change as the com<'1 passed (txcr them. 



'I'lie orl)it of this comet nniy bring it al times close to -lupiter. and 

 indeed the |)erturbations b\' that plami m ISTo were so great that an 

 altogether new oi'bit resulted. The period of revolution is about si.x: 

 and three-fourths yeuis. 



