October 21, 1897] 



NATURE 



597 



science and education in the Dominion. Thanks to the en- 

 couragement given by the Canadian Government, the Society 

 has been able, year by year, to publish a large volume of the 

 jM-oceedings and transactions of its members. The papers and 

 monographs therein contained embrace a wide field of literary 

 effort— the whole range of archaeological, ethnological, historical, 

 geographical, biological, geological, mathematical and physical 

 sciences ; and they bear witness to fifteen years of creditable 

 work for the intellectual welfare of the Dominion of Canada. 



The additions to the Zoological Society's Gardens during the 

 past week include a White-collared Mangabey (Cenocelms col- 

 iaris, ? ) from West Africa, presented by Miss Daisy Kendall ; 

 a Beisa Antelope {Oryx beisa), a Caffer Cat (Felis caffrd) from 

 Somaliland, two Arabian Gazelles (Ca3«//a ara'nca, i (J ) from 

 Arabia, presented by Mr. J. Benet Stanford ; a Zinzibar Ante- 

 lope (Nesotraffits inoschalus, 9 ), an Augur Buzzard [Bttteo 

 aitgitr) from East Africa, presented by Mr. Cavendish ; a Red 

 River Hog ((Potaniocfuerus penicillatus, 9 ) from West Africa, 

 resented by Captain Smith, s.s. Boma : a Leopard {Felis 

 .irdtis, (J ) from West Africa, presented by Captain Humfrey ; a 

 C\\\Viz\i\\\z. {Chinchilla lanigera) Ixoxa. Chili, presented by Mr. 

 J. A. Wolffsohn ; an Egyptian Ichneumon {Herpestes ichneumon) 

 from Egypt, presented by Mr. Ernest A. Dixon ; a Spotted 

 River Turtle {Einyda vittata) from India, presented by Mr. A. 

 Felix; a Geoffroy's CaX {Felis ^eoffroii), a Matamata Terrapin 

 {Chelysjimbriata) ixomBva.i\\y presented by Mr. W. Brice ; a 

 Spotted Eagle Owl {Bubo mxculosus), a Delalande's Lizird 

 {Nucras delalandii), three Lineated Snakes {Bjidon linea'us), 

 eleven Rough-keeled Snakes {Dxsypeltis scabra), four Crossed 

 Snakes {Psammophis crucifer), ten Rufescent Snakes {Leptodira 

 Jiolambceia), two Rhomb-marked Snakes ( Triinerorhinus rhombe- 

 atiis) from Port Elizabeth, South Africa, presented by Mr. J. E. 

 Matcham ; a Wapiti Deer ( C<;rr'«x canadensis, i\ two Collared 

 Fruit Bats {Cynonycteris collaris), born in the Gardens ; a Great 

 Wallaroo \AIacropus robustus, ? ) from South Australia, pur- 

 chased ; a Cape Zorilla {Ictonyx zorilla) from South Africa, 

 deposited. 



OUR ASTRONOMICAL COLUMN. 



The Law ok Spectrai. Series.— Previously in this column 

 (vol. Iv. p. 137) we have referred to some of the work which 

 has been done with the object of finding satisfactory formulae 

 for the computation of the wave-lengths of lines which form 

 spectral series. Two further interesting communications have 

 recently been published, which are important in that they 

 suggest that the formula at present in use are only roughly 

 approximate for the series as a whole, and that the anomalies 

 which hero and there are found may eventually be satisfactorily 

 explained. The first of these communications is due to Prof. T. 

 N. Thiele {Astrofihysical Journal iox August), who has for some 

 time been occupied with investigations on the law of spectral 

 series, and whose remarks are of considerable importance. The 

 problem, as he states, is a very troublesome one, and those who 

 'ccupy themselves with it cannot hope to make, so far as his 

 ' s:perience goes, those little discoveries which relieve tedious 

 investigations. In fact, one's fundamental assumptions often 

 give way before the constant criticism to which they are 

 exposed. The general law of .series is, however, still wanting, 

 although the more or less complete resolution of spectra into 

 series may be now approximately accomplished. Prof. Thiele's 

 work has proved that the law, which expresses the wave- 

 lengths of the lines in a spectral series, must have the form 



K=n{n + cn 



when A is the wave-length, and c a constant which he calls the 

 phase of the series : all other formulae are only special cases of 

 this general one. Accepting this formula and all its conse- 

 quences some very interesting points arise, the m:)St important 

 being thit it is necessary to take into account not only the lines 



corresponding to positive values of «, but those when n is less 

 than o. This involves that a series must in general be com- 

 posed of (wo groups of lines, each of which would ordinarily be 

 called a series, or, as Prof. Thiele calls them, two branches, but 

 cases may arise when the two branches coincide. It does not 

 necessarily follow that both series will always be seen, as the 

 intensity of one may be much less than that of the other. In 

 cases where there are three, four, or more branches, the pairs 

 of branches must be separated out. Another point which arises 

 from this new idea is the question as to whether the double 

 series, ordinarily found in metallic spectra, may not also be 

 regarded as constituting a single series in which both the 

 negative and positive values of n are used. In the same paper 

 Prof. Thiele gives a modification of Prof. Pickering's formula for 

 use in more precise investigations. As an illustration of the 

 question of the relation between sharp and diffuse series as 

 branches of a single series, Prof. Thiele works out the lines in 

 the spectrum of helium, and he is led to the conclusion that 

 " in spite of the remarkable corre.spondence of these two series I 

 must therefore («V) deny their unity." The second paper, which 

 we can now only briefly refer to, is that by L. Rummel, read 

 before the Royal Society of Victoria in 1896, November 12 

 (vol. ix.). The author practically obtained a formula inde- 

 pendently but similar to that given by Balmer for com- 

 puting the wave-lengths of the spectral lines of the alkalis, 

 working out the substances lithium, sodium, potassium, rubidium, 

 and cjesium. In another paper, communicated by the author 

 to the same Society in 1897, June 10 (vol. x. ), he gives the 

 result of his investigation on the relationship between the spectra 

 of the alkalis and their atomic weights. 



The Variable Star tj Aquii,.^. — In the Memorie della 

 Societa degli Spettroscopisti Italiani, Prof. A. Belopolsky de- 

 scribes some preliminary researches which he has made with 

 respect to the motion of the variable star, rj Aquilae, as determined 

 by movement in the line of sight. Up to the present time he 

 has been able to secure twelve photographs, the duration of ex- 

 posure in all cases being less than an hour. The measures were 

 made relatively to the solar spectrum, which was superposed on 

 the spectrum of the star with the help of the artificial spectrum 

 of iron. Twelve prominent lines were used, and three systems 

 of readings were obtained ; namely, those given by comparing 

 the stellar and solar spectrum, the solar and artificial spectrum, 

 and the stellar and artificial spectrum. By means of a graphical 

 process the author determines the required and the direct dis- 

 placement. 



The following summary gives in tabular form the times of 

 observation, the intervals of time between the minimum and 

 the moment of observation, the radial velocity, and the velocity 

 relative to the sun. 



Plotting the curve of velocities, after the method of Rambaut 

 and Lehmann-Filhes, Prof. Belopolsky finds that the period 

 7d. 4h. is sufficiently satisfied on the supposition that the 

 changes of the radial velocity are due to orbital movement of 

 the star. A computation of the orbit, after the method described 

 m. Astronomische Nachrichten (No. 3242), leads the author to 

 the conclusion that the variation of light cannot be attributed 

 to an eclipse, as the time of eclipse ought to take place 2d. oh. 

 or 5d. iih. after the minimum, which is not in accordance with 

 the actual facts. This result is interesting in that it tends to 

 corroborate the conclusion arrived at by Dr. W. J. S. Lockyer 

 (" Resultate aus den Beobachtungen des veninderlichen Sternes 

 J) Aquiliv," 1897, Dulau and Co., London) in the latest 



NO. 1460, VOL. 56] 



