March 14, 1901] 



NA TURE 



477 



reprints and translations of thirty-six papers of wide scientific 

 interest. Many branches of science are represented by the 

 papers, and the whole collection forms a most 'interesting and 

 valuable survey of subjects prominently before the scientific 

 world in 1898. Limitations of space prevent us from giving a 

 list of the papers reprinted from various reviews and scientific 

 periodicals, but we are glad to direct attention to the following 

 translations :^Recent progress accomplished by aid of photo- 

 graphy in the study of the lunar surface, from a paper by 

 MM. Loewy and Puiseux ; the Le Sage theory of gravitation, 

 translated from a paper by M. Prevost, with introductory note 

 by Dr. S. P. Lingley ; the extreme infra-red radiations, by Dr. 

 C. E. Guillaume ; the perception of light and colour, by M. G. 

 Lechalas ; progress in colour photography, by M. G. H. Niewen- 

 glowski ; oceanography, by M. J. Thoulet ; the relation of plant 

 physiology to the other sciences, by Dr. Julius Wiesner ; Pithe- 

 canthropus erecttis — a form from the ancestral stock of mankind, 

 by Dr. E. Dubois ; our present knowledge of the origin of man, 

 by Prof. E, Haeckel ; the laws of orientation among animals^ 

 by Captain G. Reynaud ; the theory of energy and the living 

 world — the physiology of alimentation, by M. A. Dastre ; a 

 sketch of Babylonian society, by Htrr F. E. Peiser ; the excava- 

 tions of Carthage, by M. P. Berger ; the origin of African civi- 

 lisations, by Dr. L. Frobenius ; dogs and savages, by Dr. IB. 

 Langkavel ; the life and works of Brown-Sequard, by M. Berthe- 

 lot. It will be seen from this list that the volume contains no 

 less than sixteen translations of papers on important subjects. 

 By publishing these translations, with the reprints, the Smith- 

 sonian Institution records the progress of scientific thought in a 

 most serviceable way, and enlarges the outlook of men of 

 science who do not read German and French with facility. 



The discovery of the organo-metallic compounds nearly half 

 a century ago, by Frankland, opened up a wide field of organic 

 synthesis, which has for some time been regarded as exhausted. 

 It has, however, been recently shown by M. Grignard that 

 many syntheses which are effected only with difficulty with the 

 zinc alkyls can be carried out with great ease with magnesium 

 compounds. In the current number of the Cotnptes rendus 

 M. Grignard gives a resume of his work in this direction, 

 together with a theoretical study of the reaction. By the action 

 of magnesium upon an alkyl iodide the compound RMgl is 

 first formed, and this condenses readily with aldehydes and 

 ketones, without there being any necessity to isolate the organo- 

 metallic compound, giving ultimately secondary or tertiary 

 alcohols, the yields being as high as 50 per cent. 



The additions to the Zoological Society's Gardens during the 

 past week include a Pardine Genet {Genetta pardind) from West 

 Africa, presented by Lady Moor ; a Common Otter {Lutra vul- 

 garis), British, presented by Mr. W. Radcliffe Saunders ; a 

 Yak (Poephagus grunniens) from Tibet, presented by Mr. A. E. 

 Pitt-Rivers ; a Blue Whistling Thrush {Myiophoneus coertileus) 

 from the Himalayas, a Jerdon's Green Bulbul {Ckloropsis 

 jerdoni), a Black-crested Yellow Bulbul {Otocampsajlaviventris), 

 two Blyth's Hill Partridges {Arboricula ritfigularis), an Indian 

 Green Barbet {Thereiceryx zeylonictis) from India, a Great 

 Barbet (Megalaema virens) from China, presented by Mr. E. W. 

 Harper ; a Grey-backed White-eye {Zosterops d>rsalis) from 

 Australia, presented by Mr. D. Seth-Smith ; a Buzzard {Buleo 

 vulgaris), European, presented by Mr. J. A. Harvie Brown ; 

 a Black Kite {Milvus migrans), European, presented by Mr. 

 H. Wreford ; a Red Kangaroo [Alacropus rufus) from Aus- 

 tralia, two Striated Jay Thrushes ( Grammatoptila striata) from 

 the Himalayas, two Rufous-chinned Laughing Thrushes 

 (lanthocincla rufigulatis), a Rat Snake (Zamenis mucosus) from 

 India, deposited ; a Black-faced Kangaroo {Macropus melanops) 

 from Tasmania, a Barraband's Parrakeet {Polytelis barrabandi) 

 from Australia, purchased. 



NO. 1637, VOL. 63] 



OUR ASTRONOMICAL COLUMN. 



Nova Persei.— The position of the star, as gi%en by th? 

 meridian circle at Greenwich, is 



I. s. 



During the fortnight since its discovery the star has under- 

 gone a remarkable series of changes both in brightness and 

 spectrum. 



Variation in Brightness. 

 Mag. Mag. Mag. 



Feb. 22 27 Feb 28 2"i March 6 2 '9 



23 O'lo March i 22 7 3'o 



24 0-65 2 23 8 3-2 



25 I -o 3 24 9 35 



26 i"i 4 2-6 10 37 



27 I-5-2-I .527 II 3 9 



In the current issue of Comptes rendus (vol. cxxxii. pp. 535- 

 538) M. H. Deslandres describes his observations on the spectrum 

 made with the spectroscope designed for line of sight measures 

 at the Meudon Observatory. The photograph of the star's 

 spectrum was obtained alongside a comparison showing the lines 

 of iron, calcium, hydrogen, helium and air. 



After noting the great breadth of the bright lines, he states that 

 the middle of each band is displaced towards the red with respect 

 to the terrestrial spectrum. The spectrum is similar to Nova 

 Aurigse, but the lines are broader. He then draws attention 

 to the minute structure of the H;8 (F) line of hydrogen, which 

 shows three maxima of brightness, the more refrangible com- 

 ponent being the most intense. The other lines show similar 

 structure, but not so clearly. 



On the other hand, the calcium lines at H and K each show 

 a fine, clear, dark line, the only sharp lines in the spectrum ; 

 both are displaced slightly towards the red M. Deslandres 

 discusses the two explanations of the width of the lines, that of 

 Doppler-Fizeau ascribing the appearance to motion, the other, 

 suggested by the experiments of Humphrey and Mohler and 

 Wilsing, indicating the cause to be the great pressure to which 

 the gases are probably subjected. He concludes by ascribing 

 the group of lines immediately less refrangible then H;3 to 

 magnesium and asterium, but these have been traced by other 

 observers to the most prominent enhanced lines of iron. 



Co-operation in Observing Variable Stars. — Circular 

 53 of the Harvard College Observatory consists of an outline 

 plan drawn up by the Director, Prof. E. C. Pickering, for 

 enabling a systematic investigation of variable stars to be made 

 by the cooperation of observers in various localities. This 

 has been induced by the fact that the number of long-period 

 variables is now so great that many of them are neglected. 



In the case of variables of small range the difficulty is not 

 so great, as the variation is in most cases regular, but many of 

 the variables of long period appear to change irregularly, and 

 continuous observations are required until the nature of the 

 changes are known. Moreover, the range is, in many cases, 

 .so great that the errors of observation are not sufficient to affect 

 seriously the form of the curve. 



It is recommended that in the vicinity of each variable a 

 series of about twelve comparison stars be selected, the brightest 

 being slightly brighter than the variable at maximum, and the 

 faintest fainter than the variable at minimum. The inter- 

 mediate ones should gradually decrease in brightness with about 

 half-a-magnitude differences. 



The actual magnitudes of all such stars brighter than the 

 seventh magnitude can be supplied from the meridian photo- 

 meter records, and means are now being adopted for furnishing 

 on a uniform scale the brightness of the faintest stars likely to 

 be visible in any telescope. At least one observation of each 

 star should be made every month. 



For searching out comparison stars the excellent charts of 

 Father Hagen are recommended for stars fainter than the ninth 

 magnitude. For brighter ones copies have been made of the 

 Bonn Durchmusterung charts, giving 3° square about each 

 variable, and these will be supplied to experienced observers 

 willing to co-operate in the work. A list of seventy-three 

 variables for which these charts will soon be ready is furnished. 



Dimensions of the Saturnian System. — Prof. T. J. J. 

 See has recently completed a long series of measures of the 



