June 29, 1905J 



NATURE 



207 



electric needle: Mr. David Owen; (i) the magnetic 

 rotatory dispersion of sodium vapour, (2) the fluorescence 

 of sodium vapour : Prof. R. \V. Wood. In addition to 

 illustrating his papers by experiments, Prof. Wood pro- 

 poses to show a number of other e.xperiments. 



At a meeting of the Faraday Society to be held on 

 Monday next, July 3, the following papers will be read : — 

 some notes on the rapid electrodeposition of copper : 

 Sherard Cowper-Coles ; the use of balanced electrodes : 

 W. W. Haldane Gee; (i) electrolytic oxidation of hydro- 

 carbons of the benzene series, part ii., ethyl benzene, 

 cumene and cymene ; (2) electrolytic analysis of antimony : 

 H. D. Law and F. Molhvo Perkin ; notes on heat insula- 

 tion, particularly with regard to materials used in furnace 

 construction : R. S. Hutton and J. R. Beard. 



OUR ASTRONOMICAL COLUMN. 

 Astronomical Occurrenxes in July:— 

 July 4. 4h. Venus and Jupiter in conjunciinn, Venus 2' 30' S- 

 ,, 5. Ilh. 34m. Minimum of Algol O Persei). 

 ,, 6. ih. Venus at greatest elongation, 45' 44' W. 

 ,, 15. Venus. Illuminated portion of disc = o'55i ; of Mars 



= o-88i. 

 ,, 16. Uranus parses i' north of i Sagittarii (Mag. 5'3). 

 ,, 23. Saturn. Oater major axis of outer ring = 43"'22; 



outer minor axis of outer ring = 6"'SS. 

 ,, 26. iih. Conjunction of Jupiler with the Moon, Jupiter 



4° 24' N. 

 ,, 27. loli. 6m. Minimum of Algol (fl Persei). 

 ,, 27-31. Epoch of Aquarid meteoric shower (Rsdiant 



339" -11°). 



New Obsekvatorv is Ai-GERIa. — The accompanying 



illustration of the Mustapha-Sup^rieur Observatory 



(Algeria) is reproduced from La \alurc (\o. 1671), wherein 



M. Lucien Libert describes in detail the situation and 



equipment of the institution. This observatory was 

 founded privately by M. Jouffray, and is situated to the 

 east of .■\lgiers, on a spur which forms the eastern 

 extremity of the Sahel plateau, at an altitude of 172 

 metres (about 564 feet) above the sea-level. A special 

 feature of this institution is its exclusive use of the decimal 

 system. The equipment includes a Leroy *' tropom^tre, " 

 i.e. a centesimal chronometer, which divides the day into 

 forty parts or " decagrades," and makes 100,000 beats 

 per day instead of the 86,400 beats made by the ordinary 

 chronometer. The elaborately fitted micrometer, which is 

 used in connection with a Secretan equatorial of 135 mm. 

 (5i inches) aperture and 187 cm. (6-i feet) focal length, 

 has its circle divided into 400 grades, the pitch of the screw 

 being i' (centesimal), and M. Libert contends that the 

 use of these scales effects an immense saving of time and 

 labour. The electrical and mechanical arrangements for 



NO. 1861, VOL. 72] 



illuminating and controlling the instruments and the dome 

 are described in detail, and appear to be as near perfection 

 as possible. .\ complete meteorological equipment is also 

 attached to the institution, and M. Libert pleads for the 

 foundation of a similar observatory in southern Algeria, 

 where the sky is but very rarely covered. 



A Suspected Sudden Change on Jupiter.— -At the meet- 

 ing of the Royal Astronomical Society held on May 12, a 

 note from Major Molesworth, R.E., was read in which 

 he described a suspected instance of sudden change on 

 Jupiter. Observing at Trincomaloe, Ceylon, on December 

 ■7. 1903, he made a sketch of the neighbourhood surround- 

 ing the dark spot F 87, situated on the southern edge of 

 the S. equatorial belt. This observation was made at 

 ih. 45-sm. G.M.T. At 2h. the observer suddenly noticed 

 a minute white spot, bright enough to cause him some 

 surprise at having omitted it from his previous observation, 

 preceding and touching F 87. At ah. 3m. this spot was so 

 obvious that its existence could not have escaped the most 

 casual observer, and later, at 2h. 5m., it had developed 

 into a bright oblique rift only separated by a narrow 

 streak from the spot F83. This appearance lasted so long 

 as the region remained readily observable. The region 

 was again examined on December 20, but no trace of the 

 outburst could be discerned. When first observed the 

 bright spot was preceding F 87, but later the oblique rift 

 appeared to enter the belt from a point immediately 

 following that feature. 



With a lengthy experience in observing Jupiter, Major 

 Molesworth has never before noticed any such change in 

 this region of the planet, but he is perfectly assured that 

 the phenomenon was real. The observations were made 

 under almost perfect conditions of seeing with a I2|-inch 

 Calver reflector fitted with a Steinheil monocentric eye- 

 piece magnifying 270 times (Monthly Notices, May). 



Brightness of Jupiter's Satellites. — In a recent -note 

 in these columns (May 18) attention was directed to the 

 results obtained by Prof. Wendell from a photometric in- 

 vestigation of the relative brightnesses of Jupiter's 

 satellites. He found that the invariable order of bright- 

 ness of the satellites was iii., i., ii., iv., but, from a study 

 of the photographic plates obtained at the Cape Observ- 

 atory during 1891, 1003, and 1904, Prof. W. de Sitter 

 finds that the order of magnitude was, invariably, iii., ii., 

 i.-, iv., the interval ii.-i. being always of the same order 

 as the intervals iii.-ii. and i.-iv. It thus appears that 

 there must be a considerable difference between the visual 

 and photographic magnitudes of these objects (.istrono- 

 inische Nachrichten, No. 4026). 



Elliptical Elements for the Orbit of Comet 1905 a. 

 — Finding that the places derived from parabolic elements 

 for the orbit of comet 1905 a did not agree sufficiently 

 well with those observed. Prof. Banachiewicz calculated 

 the following set of elements for an elliptical orbit from 

 several observations made at various places on March 27. 

 April 7, and April 27, and publishes the same in No. 4027 

 of the .istronomische Nachrichten : — 



T = 1905 April 408096 (Berlin M.T.). 



cc=35S 12 i7"-40^ leg,; =0-0470173 



9. =157 27 4175 V 1905-0 log ,' = 99856436 



i= 40 1 1 20-76 J P «: 20062 years 



The places derived from these elements were found to 

 agree far more satisfactorily with the observed places. 



According to a set of elements published by Herr A. 

 Wedemayer in No. 4023 of the same journal, the period 

 of this comet is about 279 years. 



Recent Positions of Eros. — The following positions for 

 Eros, on the dates, named, have been derived from photo- 

 graphs taken by Mr. .Manson at .'\requipa with the Bruce 

 telescope, apparently the first photographs of the asteroid 

 to be obtained since its recent conjunction with the sun : — 



1905 G.M.T. Exposure. 0(1900) 8(1900) 



h. m. m. h m. s. . , 



April II 1957 ... 70 ... 203637 ... -254-5 



12 2041 ... 134 ... 203834 ... -2455-6 



14 20 40 ... 45 ... 20 42 12 ... -24 39-1 



{.-istronofin'sc/ie Nachrichten^ No. 4027). 



