PK0(1RESS OF ASTIJONOMV lOK' ISHI AM» ISOJ. TIT) 



Mi\ Cliaiidlci's observations with tiic ;ilmii(';iiit;ir. in ISSI an<l l<s,sr), 

 tiist snji'uostcd to Iiiin, not only t lie ]>ossibilitv of a \ari;ition in liititudc, 

 Itiit the l;i\\ ot tlu' \:iriation. I'wcivo months' observations wore ot 

 couisc not surticient to estnl)lish ;\ pcriodii'ity of Ibnitecii months, 

 thou^li tliey miiilit sn,!n<>est it; confirmation was, Iiowever, furnish<'(l l)y 

 Dr. kiistncr, wlio. in iiis determination of the aberration from a sciics 

 of obs«>rvations coincident in time with those of the alinncantar, came 

 upon simihir anomalies, l-'url her evidence ])earini;- on the (jiiestion was 

 forthcoming- in tlie parallel determinations at Berlin. Prague, Potsdam, 

 and Pulkowa. which sliowe<l changes in ai)])arent latitude, not only 

 strikingly symi)athetic among themselves, but of the same range and 

 l)eriodicity as those noticed in 18X5; and Mr. Chandler -'was led to 

 make further investigations on the subject, which seem to establish the 

 nature of the law of these changes, and proceeded (ISill, Xovember) to 

 present them iji due order." 



The conse(iuent series of j)apers in the A.sfnmoniica} Jonrnal can 

 hardly tail to take its ]>lace as (»ue of the astronomical classics. The 

 following summary is made i>ui]»osely very brief because tlie seri<'S is 

 not yet com])]ete, and no doubr mm-h still remains to be said on such 

 an imi)ortant subject. But it will l»e seen that during the year ISIH' 

 (including ]»erliai>s tlie end of lS!>l)a most imjiortant a<lvance has 

 been made in fundanuMital astronomy. 



The first paper (regarding that already juentioned as preliminary) 

 deals with the observations with the Pulkowa vertical circle (bSGo- 

 lS7o), "which hav<' been juovcx-ative of so much in((uiry, so far without 

 any solution of the anomalies which they show in regard to the <pies- 

 tion of latitude variation.'' and the Washington prime \'crtical observa- 

 tions (ISCU-ISUT), '•'the most accuiate determinations of declination 

 e\er made at tlie ^'aval ()bser\alory."' which yet '"resulted in anomalous 

 values olthe aberration constant in tiie different yeais and a negative 

 ]»arallax in all." Mr. Chandler tinds that a iL'Tday jx'riod in the lati- 

 tude •■ furiushcs the true key to the troubies<tme discordances in the 

 Pulkowa latitudes." and "traces to their origin the anomalies in the 

 Washington obs<'i'\ations." Further, the comparison of tiie two seiies 

 leads to the same <-onclnsion as that ali-eady shown from the simul- 

 taneous series at l>eilin and (yand)iidgc (rni1<'(l States) in 18S.^ as to 

 the direction of the polar motion. In the lu'xt ]>aper it is mentioned 

 that observations at Melbourne ( ISfJ.J-lSSI i and liCAclcn (ISJI.'UlStjT) 

 are in complete accordance with thos«! made at the sanu' tinu' at Pul- 

 kowa and Washington ; ami that the 427-day p<'iiod a<'counts for the 

 contradictory results ()])tained by Di. Van licnnekelcr at Leyden. The 

 jnotion of the eaith's i)ole tor the |)eiiod ls(i{)-| sjo js tlius fairly estab- 

 lished. Tlie autlior ]iroceeds to eonsidci' earlici (»l>ser\ ations. In the 

 ]»ai>ers nund)ered ■'» and 4, th(^ systematic errors of l>radley"s observa- 

 tions, which w<'re reduced afresh lor this ])ur])ose, ar<' discussed, particu- 

 larly the colli mation enor. It is then concluded that the observ.itions 



