CIHM Microfiche Series (i\/lonographs) ICiVIH Collection de microfiches (monographies) Canadian Institute or Historical Microreproductions / Institut canadien de microreproductions historiques ©2000 Technical and Bibliographic Notes / Notes techniques et bibliographiques The Institute has attempted to obtain the best original copy available for filming. Features of this copy which may be bibliographically unique, which may alter any of the images in the reproduction, or which may significantly change the usual method of filming are checked below. Coloured covers / Couverture de couleur r~7| Covers damaged / Couverture endommag^e □ Covers restored and/or laminated / Couverture restaur^e et/ou pellicul^e Cover title missing / Le titre de couverture manque I I Coloured maps / Caries g6ogr^phiques en couleur □ Coloured ink (i.e. other than blue or black) / Encre de couleur (i.e. autre que bleue ou noire) □ Coloured plates and/or illustrations / Planches et/ou illustrations en couleur I I Bound with other material / D D Reli6 avec d'autres documents Only edition available / Seule Edition disponible n Tight binding may cause shadows or distortion along interior margin / La reliure serr^e peut causer de I'ombre ou de la distorsion le long de la marge int^rieure. Blank leaves added during restorations may appear within the text. Whenever possible, these have been omitted from filming / II se peut que certaines pages blanches ajout6es lors d'une restauration apparaissent dans le texte, mais, lorsque cela etait possible, ces pages n'ont pas et6 film^es. L'Institut a microfilme le meilleur exemplaire qu'il lui a ete possible de se procurer. Les details de cet exem- plaire qui sont peut-etre uniques du point de vue bibii- ographique, qui peuvent modifier une image reproduile. ou qui peuvent exiger une modification dans la metho- de normale de filmage sont indiques ci-dessous. D Coloured pages / Pages de couleur l/\ Pages damaged / Pages endommagees D Pages restored and/or laminated / Pages restaurees et/ou pelliculees y| Pages discoloured, stained or foxed / i_J Pages d^colorees, tachetees ou piqu6es I Pages detached / Pages detachees Showthrough / Transparence I I Quality of print varies / D D D Quality in^gate de I'impression Includes supplementary material / Comprend du materiel suppl6mentaire Pages wholly or partially obscured by errata slips, tissues, etc., have been refilmed to ensure the best possible image / Les pages totalement ou partiellement obscurcies par un feuillel d'errata, une pelure, etc., ont 6t6 filmees a nouveau de fa?on a obtenir la meilleure image possible. Opposing pages with varying colouration or discolourations are filmed twice to ensure the best possible image / Les pages s'opposant ayant des colorations vanables ou des decolorations sont filmees deux fois afin d'obtenir la meilleure image possible. Additional comments / Commentaires suppl^mentaires: Pagination is as follows: p. 274-277. La pagination est comme suit: p. 274-277, Thit item it filmed at the reduction ratio checked below / Ce document eat filmi au taux de rMuction indiqui ci-desioua. lOx 14x 18x 22x 26x 30x / 12x 16x 20x 24x 2SX 32x The copy filmed h«r« has b««n r«predue«d thanka to tha ganarosity of: Gerstein Science Information Centre University of Toronto Tha imagas appaaring hera ara tha bast quality possibia considaring tha condition and lagibii'ty of tha original copy and in kaaping with tha filming contract spacificationa. L'axamplaira film* fut raproduit grica A la ginArosit* da: Geri>tein Science Information Centre University of Toronto Las imaga* tuivantas ont At* raproduitas avac la plus grand soin. compta tanu da la condition at da la nattat* da l'axamplaira film*, at an conformity avac las conditions du contrat da filmaga. P" i-*i Original copias in printad papar covars ara filmad beginning with tha front covar and anding en tha last paga with a printad or illustratad improa- sion, or tha back covar whan appropriata. All othar original copiaa ara filmad iMginning on tha first paga with a printad or illustratad impraa- sion, and anding on tha laat paga with a printed or illuatratad impraaaion. Laa axamplairaa originaux dont la couvanura tn papiar aat impHmAa sont filmte an commancant par la pramiar plat at an tarminant soit par la darnlAra paga qui comporta una amprainte d'imprassion ou d'illustration, soit par la second plat, salon la caa. Tous lea autras axemplairas originaux sont film*s an commanpant par la pramiire paga qui comporta una ampreinte d'impreasion ou d'illustration at an tarminant par la darniire page qui comporte une telle empreinte. The last recorded frame on each microfiche shell contain tha symbol -^ (meening "CON- TINUED"), or the symbol ▼ (meening "END"), whichever applies. Un dee symboles suivents tppsraitra sur la derniire Imege de cheque microfiche, selon Is cas: la symbols — »> signifie "A SUIVRE", le symbols ▼ signifie "FIN". Mapa. plates, cherts, etc., may be filmed et different reduction ratios. Those too large tu be entirely included in one exposure ere filmed beginning in the upper left hend corner, left to right and top to bottom, as many frames aa required. The following diegrems illustrate the method: Lee cartas, planches, tableeux. etc.. peuvent itre filmte i das taux de riduction diffirents. Lorsque le document est trop grend pour Atre raproduit en un seul cliche, il est film* e psrtlr de I'engle supArieur gauche, de gauche i droite. et de heut en bea, en prenent le nombre d'imoges nicessaire. Lea diagrammas suivents illustrent le mtthode. 1 2 3 1 2 3 4 5 6 MKIOCOPV ItSmUTION TBI CHART (ANSI and ISO TEST CHART No 2| _^ ^jPP LIED IIVMGE ^BV '653 Foil Ma;' Slre,i P^S ''ocMester, f^^» Yci, U609 dS ^S ("6) 482 - 030O - Pnont ^S <"6) J«8 - 6989 - to. Wll Pmiini'^^U <] i¥ '^ii^¥^- ^ Repnnleil from the Ast«oihysicai Joiunal, Vol. XXVIII, No. 4. N-vrmber 1908 ^^-^\' ^^«^ ^ THE ORBIT OF i ORIONIS tZJ ■ -t •o J. S. PLASKKTT I'RINTKI) AT THK UNIVKRSIIV <1F CHK Alio I'RKSS (^A'^^n '5^V K^iPS'^;- ' ■<'. M TMK OK HIT OF < (>A7()A7.S' lis J ■' ri.\>Ki I I Acting on a >iipm>ti()n kindly made lo nic li\ Dr. Si lili -iiij^i r. a Icast-sijiiari's solution has lutn apiilitd 'i > tin- clctntni- of the orhii of i Oriotiis Tvcvnih jmhlislu'il in ilii> JouriuiL' .\> |>rtlirninar\ tltnirnt> thosi" (Iciirmincd in the ahovi- pajnr wtU' lakiii. and tlir ii^ piair- wtTr grouju'd into jO normal plan^. the -inn- a^ htlorr txcciit for some minor chan;4cs intro(■ j.Lk rs. TIk- piTiod was considered as very t losdy .! ti rniincd hy ilic imthod previously used and a eornilion eon>idered iinneei-.~ar\. From the oh'-ervation e(|uations wire fornnd the normal e(iua- tions below, tlu- following factor^ l)iinL; iiiirixiiHed for iiomo^eiieity: .V =8a: V = A>=i I2&; : Ktu, = 128.,. u- Am fii S,? 4f)rt/ V = 8y NOKMAI. ri.UAriOVS + 44.()68.v — 2Q.522V 4- v.^--- + 0-.^-7" ~i4.2()i;' -f cjS. 606=0 + 228.507y — 41 S<)(); -fh^.d^o/i *- ^(j oSijr --'44.074^-0 + 51.724: - -,s 4.ii" ,vVg-"<;;' - ,vi 44-' o + 76 Q4o;( +25 424;' - 56 ,^7,v-o 4-95.000;' — i5.S'X>'0 The solution of these e(|uatioi- L'ave tiie following corrected ele- ments: ' A^lrofthyuiiil Jiniriut!, 27. ;- 2, iijcS. t Astri'*ionji\cbe Wtt Itrichtrii. 136. 17. isijj, -^74 Tin: Oh'lUI Oh I DRliKM.S 275 V M K e y Period a sin t rrilmmi.iry f..rriilni IlJ o loq c)2 0.75 0,7552 110° I1.^?3I i.()4 (lays 1 (wi days + 20.7 km + J 1.34 km 29. 1.0 (lays 20.136 days 29,680,000 kill 28,867,000 km A comparixm of thr n !diial> ohlaimd from an ipht-mfris and from siihstilution in tlie obMTvation tciuations ^howid somr diltiT- cnccs of oviT a kilomcti-r and a sicond sohuion was mrcssary. For l)ri-liminary flrmcnls thosi- olitainol in the first -oluiion. fxcqit T, vvhicl) was incrt-a^'d to 2.01 days, witi- umiI. 'liif change in T was dm- to a lu-ttir aj^nrmunt tlurihy prciuci'd in tlu' ivsidual>. Using tin- samo Mib.-tituiions for lionu)gcmii> tluri' risull ihr normal c(|uations +45.OSH.V - 2S.047.V + 2.576s + o 726H -14.660:' - o --1=0 4-266.()()4.v -45.686: +65.208/< +4^ 697:' +II7-; 2=0 + 50.3723 -48.247« -33 053:' - 70.762=0 + 64.085X +jj.897f + 95.820=0 + 95.000:' + 34.800=0 Tlu'ir solution giv("^ for linal I'liimnts tlu' following: A' e y Period 109.90 + I 100 km o.754,S± 0046 ii3?28 ±1:083 1 993 ± .022 days^Juliun l>.i\ 2,417,387.993 + 21.34 io.856km 29. 136 days 28,()07,ooo km .\n t'plienu'ris computi'd from llu'sc ek'm(.'nt> >liows that ^pvi' has been reduced from 2>)nA to -'i'"^'- the probable error of an obser- vation of unit weight becoming ±().8S km, whili' the probable error> of the element^ become those given above. The cluinges from the first solution arc very small but the agreement between thi' ri'- siduals is now satisfactory. The \el.Kity-curve corresponding to the linal elements is given in the accompanying figure, with the IK)^itions of the normal i)laces as small circles. .\ comparison of a76 J. S. PLASKHTT int. OHUJl OF I ilRUfSIS 277 ihis with ilu- previous ''Rurr shows that thi- gtncral trend of the ()^J^^T\ati^)n> is more cl()>cly followed. The j)rol)ability of a seton> a knowiedj^e of the fact that the normal places with the highest resi