40 



X.i TURE 



[November 8. 1S94 



. OUR ASTRONOMICAL COLUMN. 



A Comet on the Eclipse Photographs of 1893. — A 

 year ago I'rof. Schaebeile ann mnced that the eclipse photo- 

 graphs taken by him at Chile in April 1S93, showed a comet- 

 like structure in the corona near the sun's south pole. The 

 photographs taken by ihe British observers in Brazil and Africa 

 were examined in order to see if they showed the cometary 

 object, but nothing could then be made out. It is well known, 

 however, that faint objects can be easily found when the 

 observer knows what can be seen, and where to look for it. 

 Prof. Schaeberle and Prof. Iloldenwere confident that a comet 

 was photographed upon the corona of the 1S93 eclipse, and, 

 with the ilea of obtaining confirmation of the discovery, the 

 latter sent Mr. \V. H. Wesley copies from negatives obtained 

 at Chile and Brazil, having marks upon them showing the exact 

 position of the object in question. These guides have fulfilled 

 their purpose, for Mr. Wesley says, in the Olsenalory, that 

 Ihey clearly point out a cometary structure in the corona. The 

 object is ex'remely faint, and, unless particular attention is 

 drawn to it, appears like a forked coronal ray. Evidently the 

 only way to prove ihat the object was really a comet was to 

 measure its angular distance from the moon's limb on the photo- 

 graphs taken at the different eclipse stations. Mr. Wesley has 

 done this, and he finds that the distances are: Chile, 29'; 

 Brazil, 36'; Africa, ±47'. Tnerefore, it is concluded "the 

 evidence of motion relatively to the sun, given by the compari- 

 son of the plates taken at the three stations, seems to place the 

 nature of Prof. Schaeberlc's intetcsling discovery beyond a 

 doubt." 



The Tra.nsit of Mercury. — The transit of Mercury across 

 the sun on Saturday, November 10, is a matter of more interest 

 to American than to European astronomers. The planet will 

 enter upon the sun's disc at 98' from the North point, counting 

 towards the East, and will leave at a point 50' from the North, 

 counting towards the West. It will reach the sun's limb at five 

 minutes to four in the afternoon ; but as (he sun sets at Green- 

 wich about twenty minutes later, there will not be much oppor- 

 tunity for observation in London. In America, however, if 

 the weather is favourable, the planet will be observed during 

 the whole of the five hours it will take in transiting. The 

 following are the Greenwich Mean Times of the phases of the 

 transit : — 



Ingress, exterior contact 



Ingress, interior contact 



Leait distances of centres (4 26""8) 



Egress, interior contact 



Egres.s, exteri.>r contact 



Nov. 10 



3 55 3>-2 

 3 57 ■5'4 

 6 33 4«-5 

 9 10 264 

 9 12 io'4 



MiRA Ceti. — Mr. Fowler writes from South Kensington to 

 draw attention to the (act that this remarkable variable will be 

 suitably placed for observations during its progress to Ihe next 

 maximum. .According to the Ct'w/<;///i'« to thi Ohscrvatory^ the 

 dale of minimum was September 24, and the maximum may be 

 expected about Febrmry next. It will be of great interest to 

 obtain a spectroscopic record during Ihe rise lo maximum, with 

 special reference to the lime ol appearance of the bright lines of 

 hydrogen, which have been seen near Ihe time of maximum. 



Mr. Fowler observed the spectrum on October 24, with ihe 

 three-foot reflector, and it did not then differ from the spectrum 

 of such a star as a llerculis, in which the hydrogen lines are nol 

 known to appear bright. The bright part of the spectrum 

 which is coincident wih Ihe carbon band near A 5165 was rela- 

 tively leu bright, however, than when it was observed near the 

 lut maximum. 



Return of Encke's Comet.— It is reported that Encke's 

 comet was observed at Rome by Prof. Cerulli, near the 

 predicted place, on November I. According to a search 

 cphemeti- given in Ihe Asliononiiic/it Naclirichleii, No. 3260, 

 for Berlin midnighi, the cornel's place for November 8 is 

 R.A. 22h. 59m. 30s. Decl. -(- 12° 32' 18 . The comet passes 

 perihelion next February. 



Two Variahle Stars.— In a Wohingham Ohicrvatory 

 Circular, No. 40, daled Oc ober 30, the Kev. T. E. Espin 

 says: "The vaiiabiliiy of two red stars, R.A. oh. 49'om. 

 Decl. -f 58' r and R.A. ih. 498m. Decl. -I- 58' 46' has been 

 definitely ascertained." 



NO. 1306, VOL. 51] 



OBSERVATIONS OF MARS. 



A L.\RGE proportion of the October number of Astronomy 

 •^ <j«i/ Astro-Physics is devoted lo articles on Mars, illus- 

 trated by several coloured plates. Schi.iiarelli's map ol Mars 

 forms Ihe frontispiece ; Prof. Schaeberle contributes nine 

 drawings of the planet ; and there are three plates containing 

 drawings made at the Lowell Observatory, Flagstaff, .\rizona, 

 by Mr. Percival Lowell, Prof. W. II. Picketing, and Mr. .\. 

 E. Douglass. The following statement, from an article by Prof. 

 Pickering, is a chronological summary of Ihe more important 

 facts and discoveries relating 10 .Mars. It is chiefly compiled 

 from Flammarion's monograph on Mars, and should be of 

 special interest at the present time : — 



272 i!.c. The first known observation of Mars is recorded 

 in Piolemy's Almagest. 



1610. The phases of Mars were discovered by Galileo. 



1659. The first sketch showing surface detail was made by 

 Huyghens. He also suggested a rotation in 24 hours. 



1666. Cassini determined Ihe rotation of Mars to take place 

 in 24 hours 40 minutes. lie also observed the polar caps, and 

 " be distinguished on the di.sc of Mars, near the terminator, a 

 while spot adv.mcing into the dark portion, and representing 

 without doubt, like those of the moon, a roughness or irregu- 

 larity of the surface." This latter statement is curious, but the 

 effect was undoubtedly due lo irradiation, since his telescope 

 was entirely inadequate to enable him lo observe such a delicate 

 phenomenon. 



1777. With the exception of Huyghens, Hooke, and pos- 

 sibly M.iraldi, no one succeeded in making recognisable 

 sketches of Ihe surface detail upon Mars for over a century, 

 until Sir William Herschel took the matter up in this year. 



1783. -Sir William Herschel delected Ihe variation of the 

 size of the polar snow caps with the seasons, measured the 

 polar compression, and determined Ihe inclination of the axis of 

 the planet to its orbit. 



17S5-1S02. Schrmter made an extended study of the planet. 

 His drawings are upon Ihe whole rather belter than those of 

 Herschel. He discovered among other things the very dark 

 spots to which Prof. Pickering has referred in his publications 

 as the Northern and Equatorial Seas. He, however, supposed 

 them lo be clouds. 



1S40. Beer and Maedler published the first map of the 

 planet, assigning latitudes and longitudes to Ihe various mark- 

 ings. On this map are indicated the first canals, and the first 

 of the small lakes, so many of which have been discovered 

 during Ihe last few years. The canals are Nectar and 

 Agathodaemon and portions of Hades and Tartarus. The lake 

 is Lacus Phoenicis. Their map is the first satisfactory repre- 

 sentation of Ihe entire surface of the planet. The only region 

 whiih previous observers had clearly distinguished was that in 

 the vicinity of the Syrtis Major. 



1858. Secchi made a careful study of the colours exhibited 

 by Ihe planel. 



1862. Lockyer made the first series of really good sketches 

 of Ihe planel, showing all the characteristic forms with which 

 we are now so familiar. His drawings, and also those of some 

 of the other observers, give the first indications of the appear- 

 ance of Ihe central branch in Ihe V, so called by .Secchi. 



1864. Dawes detected eight or ten ol ihe canals. 



1867. Huggins delected lines due lo Ihe presence of water 

 vapour in the spectrum of Mars. 



1867. Proctor determined the period of roUation of Mars 

 within 01 second. 



1877. Hall discovered the two satellites of Mars. 



1877. Green made a very excellent series of drawings of the 

 planel, superior to anything which had preceded them. 



1877. Schiaparclli made Ihe first extensive Iriangulation of 

 the surface of the planet, and added very largely lo the number 

 of known canals. 



1879. Schiaparelli detected the gemination of Nilus, the 

 first known double canal. 



1S82. .Schiaparelli discovered numerous double canals, and 

 announced that the appearance formed one of the characteristic 

 phenomena of the planet. 



Mr. Percival Lowell reports ihc observations of Mars made 

 at the Lowrll Observatory, in continuation of those recorded in 

 our issue of September 13. The subjoined abstract of Ihe paper 

 raises some interesting points. The suitability of the site of the 

 observatory may be judged from the fact that the planet has 



