fune 26, 1884] 



NA TURE 



Group 1. Mean period 206-37 days. Kp. 1S64 Jan. 17-47. 



Group 2. Mean period 212-52 days. Ep. 1880 Sept. 24-21. 



Such a difference is well worthy of further investigation. The 

 magnitude at maximum has varied between 7-8 and 9-3. 



There does not appear to be any earlier observation of this 

 star than that by Bessel on January 6, 1833, when it was esti- 

 mated a ninth magnitude. It was not observed either by Lalande 

 or D'Agelet. Prof. Schbnfeld's elements in his second catalogue, 

 which assume a- uniform period of 208-8 days, would give a 

 maximum on October 6, 1881 ; according to Mr. Baxendell, it 

 took place on November 21. 



Communications from Mr. Knott and Herr Wilsing, of the 

 Observatory, Potsdam, on Ceraski's short-period variable, U 

 Cephei, have appeared in the Astronomische Nachrichten. Mr. 

 Knott, from 20 minima observed by him between 1880 October 

 23 and 1884 March 20 finds for elements — 



Ep. 18S2 April 19-92641 G.M.T. + 2-4928722 d. E. 

 Herr Wilsing has collected 61 minima by different observers 

 between 1S80 July 3 and 18S4 April 9, and finds (similarly 

 expressed) — 



Ep. 1881 Nov. 21-34640 G.M.T. 4- 2'492S646d. E. 

 To the suspected circumpolar variables recently named in thi s 

 column may be added Bradley 392, which figures in our cata" 

 Iogues with various estimates of magnitude from 4-5 (Arge~ 

 lander's Zones) to 7 and 8 (Taylor and Lalande) ; generally, 

 however, it has been called a sixth magnitude. Doubtless in 

 many, perhaps in most, cases, such discordances arise from 

 errors of estimation, through clouds, &c, or from misprints. 

 but in others, as in the case of Schwerd's magnitudes of U 

 Cephei (6-7, 8, 10 respectively), they are known to have been 

 caused by a real fluctuation in the star's brightness, and hence it 

 seems worth while to examine similar instances of disagreement 

 in the catalogues. 



Missing Nebul.e.— In Riimker's Catalogue are two objects 

 observed as nebula; which were missed byD'Arrest and Auwers. 

 In No. 1542 of the Astronomische Nachric hten Mr. G. Riimker 

 has given the particulars of the observations from his father's 

 manuscripts. The first nebula was observed on May 27, 1841, 

 and its apparent place was R.A. 13I1. 52m. 3S-20S., Decl. + 

 45 3°' I3"'8. The Hamburg mean time of the observations 

 was 9h. 31m. 43s. In the Durchvmsterung we find a star thus — 



8-8 ... 13b. 53m. io-os. +4S°3i'7 ... K. 

 Consequently Argelander identifies this starS'Sm. with Riim- 

 ker's nebula. Two questions arise in such a case, and not for 

 the first time : Was a comet projected on the place of Argelan- 

 der's object at the time of Riimker's observation ? or (more im- 

 probably), Was the star at that time surrounded by nebulosity 

 which has since become invisible ? Bessel, we know, observed 

 a nebulosity on November 8, 1832, in a position where only a 

 star 9-3 m. was subsequently seen by Argelander and D' Arrest. 

 We refer to Riimker's first nebula more especially because its 

 place was not very far from that which might have been occu- 

 pied by the third comet of 1858, recently shown to be periodical 

 by M. Schulhof. If that comet were at perihelion about 1841 

 April 21-8, its right ascension might have agreed with that of 

 Rumker's nebula, but the declination would be given by calcu- 

 lation about 6° further north. Whether with the consequent 

 period of revolution, which, assuming three periods, 1841-58, 

 would be near M. Schulhof's lower limit, the action of the 

 planet Jupiter during the first revolution could have caused such 

 difference from the orbit for 1858 as to reconcile the discordance 

 in the observed and computed declination, we cannot say, though 

 it hardly appears likely. Still it may be worth while to mention 

 the above approximate coincidence, as M. Schulhof has searched 

 unsuccessfully for an indication of a former appearance of the 

 comet in question. 



GEOLOGICAL NOTES 

 Triclinic Pyroxene.— Mr. J. T. Harris Teall points out to 



wi5 SmCe the paper was written on tnis subject by Mr. 

 H hitman Cross, to which reference was made in Nature (ante, 

 p. 155), this author has found that, after reconsidering the matter 

 in the light of the researches of Fouque and Michel Levy on 

 the optical properties of monoclinic pyroxene, a great majority of 

 the instances cited by him as indicating a triclinic pyroxene are 

 explainable as augite, and that the few cases which still seem 



anomalous are not in themselves sufficient to justify a reference 

 to the triclinic system. The mistake was made in specimens not 

 cut rigidly parallel to the axis, for it appears that the ellipsoid of 

 elasticity is so situated as to produce very great variations in 

 optical behaviour in sections which are but little inclined to each 

 other. [Amer. Journ. Science, No. 151, xxvi. p. 76]. 



The Brussels Museum and its Work.— The second volume 

 of the Bulletin of the Musee Royal a 'Histoire Naturelle de Bclgiqitc 

 has just been completed by the issue of a fourth fasciculus. In 

 this part geology and palaeontology continue to assert their 

 supremacy. M. Dollo supplies a paper on a gigantic fossil bird 

 (Gas/ornis Edwardsii, Lemoine) from the lower part of the 

 Landenian stage at Mesin, near Mons. Having completed the 

 summary description of the Iguanodons, but not being yet in a 

 position to publish his expected large monograph on that im- 

 portant group, he has in the meantime turned to the Crcco- 

 dilians of Bernissart, of which he furnishes here a preliminary 

 notice. They consist of four individuals capable of division into 

 two well-marked groups — two large specimens indicating an 

 animal about two metres in length, to which he gives the name 

 of Goniopholis simus, and two small forms which he regards as 

 belonging to a new genus, named by him Bernissartiu. M. 

 Ernest Van den Broeck, following up the memoir published in a 

 previous number of the Bulletin by his colleague, M. A. Rutot, 

 offers a note on a new mode of classification and of graphic notation 

 for geological deposits, based upon the study of marine sedimen- 

 tation. The veteran palaeontologist, Dr. L. G. De Koninck, 

 contributes an essay on the Spinjer mosquensis and its affinities 

 with other species of the same genus. 



Geological Survey of Belgium.— Appended to the last 

 number of the Buleliu of the Musee Royal is a Report by M. 

 Dupont, Director of the Museum, on the state of the detailed 

 geological map of Belgium, which is being prepared under his 

 supervision. The preliminary examination, which was estimated 

 to require six years, having been completed, the continuous survey 

 of the formations has been prosecuted, each important group 

 being intrusted to an officer specially qualified for its investiga- 

 tion. Nineteen sheets are in the course of preparation for publi- 

 cation. Of these the greater number belong to the remarkable 

 Devonian territory which forms so interesting and important a 

 part of Belgian geology. We see from the map that these sheets 

 are mainly the work of M. Dupont himself. He spent 100 

 day, in the field last year almost entirely among the Devonian 

 rocks. M. Mourlon devoted his time to tracing the area of the 

 Famennian beds. The third section, under the charge of M. 

 Van den Broeck, has made progress among the oligocene Tertiary 

 deposits of Central and Northern Belgium. The' fourth section, 

 supervised by M. Rutot, spent half of the season in mapping the 

 Eocene deposits of Limbourg, and the remainder in prosecuting 

 the investigation of Hainault, Brabant, Flander-. and the study 

 of the Upper Cretaceous rocks and base of the Eocene series, 

 the Eocene part of three sheets being finished. Dr. Purves, in 

 charge of the fifth section, has devoted his energy to the mapping 

 of the Jurassic rocks of Luxembourg, and the study of the Cre- 

 taceous series of Hainault and Limbourg. The total number 

 of days spent in field-work by the whole staff has been 512. 



Geology of Finmark.— Mr. Karl Pettersen continues his 

 contributions to our knowledge of the geology of the Norwegian 

 coast. In a recent memoir (A rchiv for Math, og Naturvidenskab., 

 Bd. viii. p. 322) he describes that picturesque tract lying between 

 the mouth of the Kvenangen Fjord and the Refsbotten, which 

 includes the lonely Jokelfjord and Bergsfjord with the islands of 

 Stjerno, Seiland, Sorb, and Kvalo. The greater portion of this 

 area is occupied by various crystalline rocks— gneiss, mica-schist, 

 gabbro, diorite, &c. — referred by the author to the Laurentian 

 series. Above these lie certain certain mica-schists with includerl 

 beds of limestone, which, under the name of the Tromso mica- 

 schist group, are assigned to the Cambrian system. 



American Jurassic Dinosaurs.— In the American Journal 

 of Science (April 1884) Prof. Marsh continues the valuable series 

 of papers which he has contributed to our knowledge of the 

 structure and affinities of the Jurassic Dinosaurs. In part viii. 

 he discusses the carnivorous order Theropoda, two nearly perfect 

 skeletons belonging to which have enabled him to throw some 

 new and most important light on the order. An almost perfect 

 skeleton, above seventeen feet long, has been named by him 

 C, ratosaui us, and presents some novel features in dinosaurian 

 organisation. It has a large horn on the skull, a new, strange. 



