114 



NA TURE 



[December i, 1892 



thirty grams of iodine, and then saturating the liquid with 

 chlorine gas. The temperature was raised slightly during the 

 operation, and upon subsequent cooling the compound CSCI4I was 

 deposited in the form of pale orange-coloured prismatic crystals 

 belonging to the monoclinic system. The compound is only 

 slightly soluble in water, but, with a little loss due to decompo- 

 sition, may be recrystallized from that liquid. It is, however, 

 quite stable in the air, and only decomposes upon heating, 

 thereby producing the tri-halogen compound, CsClgT, fusing at 

 238*, the melting-point of this latter compound. A similar com- 

 pound, containing rubidium instead of caesium, RbCl4T, may be 

 obtained in like manner in large orange-coloured tabular crystals, 

 likewise belonging to the monoclinic system, but of different 

 habitus to the crystals of the caesium compound. An analogous 

 compound containing potassium, KCI4I, was prepared so long 

 ago as the year 1839, by Filhol. Messrs. Wells and Wheeler 

 finally describe sodium and lithium salts of this description, both 

 of which, however, contain water of crystallization. They are 

 represented by the formula NaCl4T.2H20 and I.iCl4T.4HjO. 

 Both crystallize well, the former in rhombic prisms ; the latter, 

 however, is so extremely deliquescent that measurements of the 

 crystals have not been obtained. 



The additions to the Zoological Society's Gardens during the 

 past week include two Common Marmosets i^Hapale jacchus) 

 from South-east Brazil, presented by Mrs. Comolli ; an Otter 

 {Lutra vulgaris) British, presented by Mr. Frederick Collier ; 

 a Black-hacked Jackal {Cants mesomelas, jv.) from South 

 Africa, presented by Miss Thornton; a Common Jackal {Cants 

 atireus, ? ) from Fao, Persian Gulf, presented by Mr. W. D. 

 Gumming, C.M.Z. S. ; two Short-headed Phalangers {Belideus 

 brevkeps, 6 9 ) from Australia, presented by Capt. S. M. Orr ; 



a Lemur {Lemur •) from Madagascar ; six Crab-eating 



Opossums {Didelphys caucrivorus), four Ypecha '9^zA%{Aramides 

 vpecha) from South America, a Green-cheeked Amazon 

 {Chrysotis viridigenalis) from Columbia, a Yellow-cheeked 

 Amazon {Chrysotis autumnalis) from Honduras, purchased ; 

 a Nilotic Monitor ( Varanus niloticus) from Africa, received in 

 exchange ; two Shaw's Gerbilles {Gerbillus shawi) born in the 

 Gardens. 



OUR ASTRONOMICAL COLUMN. 



Comet Holmes (November 6, 1892). — The elements and 

 ephemeris of this comet have heen the subject of much c mputa- 

 tion during the present month. The first result obtained gave 

 a place resembling in many particulars that of the long-sought- 

 for Biela c^met ; hut owing to an error in one of the observa- 

 tions, the corrected elements stated otherwise. The current 

 numt>er of Astronomische Nachrichten (No. 3129) gives four 

 different systems of elements which have as yet been deduced, 

 and it is quite worth while to produce them here, showing also 

 the difference between the observed and reduced places for each 

 in particular : 



Elements, Berlin M.T. 



1892. 1892. 1892. 1892. 



T = Feb. 28 362 Mar. 19 '630 May 6'3oi June 6'84i 



339 "'"87 334 4690 328 i9'o9 



332 7'30 339 37'87 34^ 23-01 



24 5491 24 55-33 25 6-06 



0-26144 o-2o868 0-14910 



—081 -0-47 -fo'2o 



-t-o 84 -fo-58 +0 41 



(0 =: 340 25-ij2 



Q, = 329 21-15 



t — 24 5.;-i5 



log y = 0-27766 



Mean place \rfA... 

 (O -R) i^/S... 



04 



The latest information about the elements is that which has 

 originate I from Prof. Kreutz, who has found elliptic elements 

 for the comet ; he also says that the elements indicate that per- 

 turbations have taken place on account of the comet's proximity 

 to the planet Jupiter. The elements are reduced from the three 



places observed on November 9, 13, and 17, and are as 

 follows : — 



Epoch 1892 Nov. 17-5 M.T. Berlin. 



M = 22 18 37-1 



<» = 13 37 49*0) 



^ = 331 31 37 \ 1892.0 



i — 20 54 81) 



<p = 24 39 307 



fjL = 500" -407 

 log u - 0-567123 



U = 7-09 years. 

 Further observations of this comet are reported {Comptes 

 rendus, No. 21). At Algiers, MM. Trepied, Rambaud, and Sy 

 found its position on November 15, at 8h. 53m. 41s., Algiers 

 mean time, to be : App. R.A. oh. 43m. 22-28<. App. Decl. 

 + 37° 43' 3" '9- The corresponding values found at Lyon by M. 

 G. Le Cadet at 8h. 47m. 33s., Paris mean time, were : App. 

 R.A. oh. 43m. 22-725. App. Decl. + 37° 43' 5" -9. The 

 comet presented a bright nebulosity in the form of an elliptic 

 segment with its axis directed in the position angle 150°, its 

 length and breadth both being 10'. The northern edge appeared 

 rounded and well defined. At the focus of the ellipse a con- 

 densation could be distinguished, about 20" broad, with a 

 prolongation inclined to the axis of the ellipse. An attempt at 

 calculating the elements of the orbit has been made by M. 

 Schulhof. The slow motion of the comet renders this task very 

 difficult. Among the various systems of elements tentatively 

 fixed there is only one which fairly agrees with all observations. 

 In this the excentricity is as small as 0-355386, so that it will 

 probably be possible to follow the comet thronghout its orbit 

 with the most powerful instruments. The other elements thus 

 determined are : w = o°o'39"-i, Q, = 328° 32'4o"-7, 2 = 20° 26' 46" '8, 

 and log^ = 0-360966. 



At Bordeaux, M. F. Courty succeeded in photographing the 

 brighter portions of the comet on November 13, with one 

 hour's exposure. Another photograph, taken by MM. Paul and 

 Prosper Henry at Paris, was presented to the Academy by M. 

 Tisserand. It was obtained on November 14, with the chart 

 photographic equatorial. The exposure lasted two hours. It is 

 a very fine photograph, showing a well-defined and nearly 

 circular contour. The nucleus is bright, excentric and lengthened 

 out. Several stars can be seen through it. There is no tail 

 except the lengthening of the nucleus, which does not extend 

 beyond the limits of the nebulosity. 



A Bright Comet.— A telegram from Kiel states that Mr. 

 W. R. Brooks has discovered a bright comet. As determined 

 at Cambridge, U.S., its place was, on November 21, at 

 i6h. 44 -em. Cambridge M.T. 



R.A. I2h. 59m. 1 5 •6s. 



Decl. + 13° 50' 27" -o 



Daily motion +im. 32-;., and -h 25' respectively. 



Another telegram, also from Kiel, gives the position, as 



obtained at Vienna on November 24, at I5h. 497m. (Vienna 



M.T.), as 



R.A. I3h. 3m. 6-4S. 

 Decl. -i-i5°o'36". 



Astronomical Instruments up to Date.— We have 

 received a circular signed by Dr. L. Ambronn, of the Gottingen 

 Observatory, and Herr Julius Springer, publisher in Berlin, 

 setting forth the contents of a work which they propose to 

 publish with regard to the general principles, constructions, and 

 methods of using astronomical instruments in general. Such 

 a book, of course, to be of the greatest value to science, 

 must be completely done, but any one who is acquainted with 

 the compiler and publisher mentioned above will be sure that 

 each will do his share thoroughly and honestly. In constructing 

 such a compendium of instruments as this is proposed to be, 

 we might say it would be impossible for one man to do it alone, 

 for the present state of the feintechnik has reached such a high 

 pitch and the branches of astronomy are s ) numerous, that such 

 an undertaking would simply be out of question. The 

 object of this circular, besides stating the lines on which the 

 work will be written, is to request the co-operation of all observa- 

 tories. Astronomical science, especially the theoretical side, 

 owes much, as we all know, to German workers, so that we can 

 rely on a good response being given to this request. W.hat is 



NO. 1205, VOL. 47] 



