May 25, 1893] 



NA TURE 



81 



bromides have been obtained in good crystals. When selenious 

 acid is dissolved in hydrobromic acid and to the solution of 

 selenium tetrabromide thus formed a solution of potassium 

 bromide is added, and the mixture evaporated and allowed to 

 cool, a deep orange-coloured precipitate is produced, consisting 

 of small regular octahedrons of potassium selenium bromide, 

 KoSeBr,,. These crystals are decomposed by water like those of 

 the tellurium salts previously described, a colourless solution 

 being obtained which contains selenious and hydrobromic acids 

 and potassium bromide. They dissolve without decomposition, 

 however, in dilute hydrobromic acid and separate from the 

 solution again upon evaporation. The ammonium salt (NHj)^ 

 SeBr.j, is likewise readily obtained by employing ammonium 

 bromide instead of potassium bromide. A precipitate of minute 

 dark-coloured regular octahedrons is usually at once obtained 

 upon adding the ammonium bromide, and the mother liquor 

 after filtration yields by spontaneous evaporation beautiful garnet 

 red octahedrons, modified by faces of the cube, which frequently 

 >;xceed half a centimetre in diameter and exhibit a brilliant 

 semi-metallic lustre. 



Notes from the Marine Biological Station, Plymouth. — 

 Last week's captures include a number of the Lucernarian 

 Depastrum cyathiforine (one individual exhibiting a lateral bud), 

 several varieties of the Actinian T/ioi: {Sagartia) sphyroJeta, the 

 Mollusca Scpiola allanika, Philineaperta and .'Eolidklla Alderi, 

 and species of the Cumacean genera Diastylis, Ipliinoc and 

 Pseudocuma. There has been no noteworthy change in the 

 floating fauna. The following animals, in addition to the larger 

 number of those already recorded, are now breeding : — the 

 Actinian Urticina felina ( = Tealia cfassiconiis), the Cumacean 

 Pseudociima cercaria,i\it Brachyura Xanthofloridus and rivulosus 

 and the Echinid Echinus miliaris. 



The additions to the Zoological Society's Gardens during the 

 past week include a Chacma Baboon (Cy«;)f<'//ia/;/.r/or^a,-(«j, 

 (J ), a Lion (Fdis ho, $ ) from South Africa, presented by Mr. 

 Frederick VaughanKirby; a Mozambique Monkey (C.friro/iM^fa/j 

 fygeryl/irus, i ) from East Africa, presented by Mr. Lewis 

 Atkinson; a Sykes's Monkey (Cenopilhecm allngularis, i) s. 

 Garnett's Galago (Galago garnelli) from East Africa, presented 

 by Mr. Thomas E. C. Remington; a Diana Monkey (Cerco- 

 pit/uats diana, 9 ) from West Africa, presented by Surg.-Major 

 S.J. Flood; a Japanese Deer (Cervtts sika, i) from Japan, 

 presented by Mr. C. J. Lucas ; two Emus (Dromitus nov,e- 

 IwUandia) from Australia, presented by Mr. Charles E. 

 Milbum ; four Sociable Marsh Hawks (Koslrhamiis sociabilis) 

 from South America, presented by Mr. G. R. Gibson ; two 

 Madagascar Weaver Birds (Fondia madagascanensis) from 

 Mad.-igascar) presented by Mr. Ginn ; a Laughing Kingfisher 

 {Dacelo giganlea) from Australia, presented by Mr. W. B. 

 Brett : a Radiated Tortoise (Testudo radiala) hom Madagascar, 

 presented by Mr. B. Smith ; a Bonnet Monkey {Macactis 

 siniais, i) from India, (two Mexican Guans {Penelope pur- 

 purascens) from Central America, a Wattled Guan ( Uburria 

 ■■carunculala) from United States of Columbia, deposited ; a 

 White-lipped Peccary {Dicolyks labiatus, <J ) from South 

 America, an Orange-winged Amazon (Chrysalis amazonica) 

 from South America, twelve Spotted Salamanders [Salamandra 

 maculosa) European, purchased ; a Reindeer (Pangifcr laran- 

 tins, i ) born in the Gardens. 



I 



OUR ASTRONOMICAL COLUMN. 



The Total Solar Eclipse (April, 1S93).— In Comptes 

 Reudus for March 15 (No. 20) M. Deslandres gives a brief pre- 

 limmary account of some of the main results that he has been 



NO. 1230. VOL. 48 I 



able to gather from the photographs taken by him during the 

 recent total solar eclipse. The instrumental equipment that he 

 had, enabled him to obtain photographs of the corona, to study 

 its spectrum, to examine the coronal light in the most refrangible 

 part of the ultra-violet region, and to measure the rotation of 

 the corona by the method of the displacement of lines in the 

 spectrum. "The coronal photographs showed luminous jets of a 

 length equal to twice the diameter of the sun, while the general 

 outline had a form somewhat usual at times of maxima spot 

 frequency. With regard to the spectroscopic results, the large 

 dispersion that was employed in one case was found to have 

 been too great ; but from the photographs taken wfith the small 

 dispersive instrument at least fifteen new coronal and chromo- 

 spherical lines have been discovered. Perhaps the most inte- 

 resting results obtained relate to the rotation of the corona. 

 The negatives showed the spectra of two points exactly on 

 opposite sides of the corona, situated in the equatorial plane of 

 the sun, at a distance equal to two-thirds of his diameter. The 

 lines in the spectra indicated large displacements, which on 

 measurement were found to correspond to velocities of 5 and 7 

 kilometres. The conclusion to be gathered from such a result 

 as this is that the corona must travel nearly with the disc in its 

 motion and thus be subject to its periodical rotational movement. 



The Eclipse of April, 1S93.— It is very satisfactory to 

 hear that the photographs taken by the English party situated 

 at Fundium, on the west coast of Africa, have, on closer 

 examination, turned out very excellent. There seems great 

 reason also to believe that many old points may be cleared up, 

 while hope is also entertained of raising some new ones. 



Finlay's Periodic Comet.— A telegram from Kiel informs 

 us that Finlay's comet has been found. It runs as follows :— 

 18 May, l6h. 15m. 6s., Capetown 

 K-A. 355° 30' 18" N.P. D. 95° 1' 50" 

 Dim. 



Variable Star Nomenclature. — Now that a systematic 

 means has been adopted for numbering the minor planets 

 until their orbits are fully recognised, much unnecessary 

 confusion has been avoided. Just as it was with asteroids so 

 it is with variable stars, many stars being termed such 

 although their variability has not been confirmed. To correct 

 such errors and to eliminate various other sources of mis-nota- 

 tion, such as that of putting a catalogue letter in front of the 

 constellation in which the star is situated, when another star in 

 the constellation is so known in the star maps. Prof. Chandler 

 adds a few notes with reference to the catalogue which will now 

 soon be forthcoming (Astronomische Nachrichten 3 161). He 

 also gives a partial list of some of the letters that will be adopted 

 to avoid further complexity. 



Jupiter's Satellites.— In this column, vol. xlvii., p. 51S, 

 we referred to the important work that was being carried 

 on at Arequipa by Prof. Pickering with reference both to the 

 telescopic appearances of Jupiter and his system of satellites. 

 Since that time further observation?, more especially of the 

 satellites, have occupied his attention, and an account of them is 

 given in the current number of Astronomy and Astrophysics 

 (No. 1.15). The first investigation he undertook was to find out 

 whether the rotations of the satellites on their axes were retro- 

 grade or direct. To do this the alternate lengthening and 

 shortening of the discs were minutely observed, use being made 

 of the revolution of the earth, since it is on this account that 

 afier opposition with direct motion of rotation a given phase 

 will be presented earlier, and with retrograde motion a given 

 phase will be presented later than if the observations had been 

 made from the centre of the sun. Working with the first satel- 

 lite it was found th.it a series of observations occupied about 

 two hour.', and upon the hypothesis of a direct rotation the 

 synodic period was I3h. 3m. 25-83., and upon a retrograde 

 motion hypothesis, I3h. 3m. loSs. 'The conclusion of the dis- 

 cussion of the observations here given is that the rotation is pro- 

 bably retrograde. In the clear air of Arequipa, and with excel- 

 lent instrumental equipment. Prof. Pickering has been able to 

 make many quite unique observations. We have mentioned before 

 the flattening of the disc of the second satellite when about to 

 undergo an occultation. This observation has later been con- 

 firmed, and thus shown to be a genuine observed fact. The 

 reappearance of the third satellite on January 27 has given per- 

 haps a better series of observations of this atmospheric effect. 

 When the satellite was half uncovered "it was noted that the 

 cusps were distinctly rounded as in the case with the sun when 



