JUNE 7, 1906] 



NATURE 



'35 



Mii. T. Fisher I'nwin has published a second edition of 

 " Moihocis in Plant Histology," by Dr. C. J. Chamberlain, 

 of Ihc- University of Chicago. The first edition of the book 

 appiared in iqoi, and was reviewed in our issue of 

 November 28, 1901 (vol. Ixv., p. 75). It is only necessary 

 to say of the present edition that more attention has been 

 given to the collection of materials. Prof. Kleb's methods 

 for securing various reproductive phases in the algrc and 

 \m\^\ have been outlined, and methods for growing other 

 laboratory material are more complete. New chapters 

 dealing with microchemical tests, free-hand sections, special 

 methods, and the use of the microscope are included. 



OVR ASTRONOMICAL COLUMN. 



Si'N-srOT AND CiiROMOsniERic SpECTRA. — A paper of 

 exceptional interest to workers in solar physics was read 

 by Prof. A. Fowler at the April meeting of the Royal 

 Astronomical Society. 



Whilst observing the bright lines in the spectra of 

 metallic prominences on the sun's limb, Prof. Fowler has 

 been able to classify them into " long " and " short " 

 lines, a fact which points to their origin being in the 

 higher and the lower chromosphere respectively ; he also 

 states the fact that the lines emitted by the upper chromo- 

 sphere, the " long " lines, are those which, speaking 

 generally, are enhanced when passing from the arc to the 

 spark in terrestrial spectroscopy. 



Further, Prof. Fowler found that these long lines are 

 generally -weakened in sun-spot spectra, whilst the short 

 lines are generally widened, or strengthened. The evidence 

 for this differential treatment of " enhanced " and " arc " 

 lines in the solar atmosphere is most conclusive for the 

 elements iron, titanium, and chromium (the Observatory, 

 No. 370). 



Proi'osed Daily Photographs of Chromospheric R-iidi- 

 ATIONS. — A paper by M. Deslandres, which is published in 

 the Compies rendus for May 7, discusses in detail the 

 possibilitv of obtaining daily photographs of the radiations 

 emitted by the solid and liquid particles of the chromo- 

 sphere, without waiting for the rare occasions afforded by 

 tot.ll eclipses of the sun. 



In order to do this M. Deslandres proposes to employ 

 an apparatus similar to that used by hiin for the same 

 purpose during the last eclipse, and to obtain a concentrated 

 image of the chromosphere, without the photosphere, by 

 a special arrangement of mirrors and lenses. 



If the coloured screens are insufficient, it is suggested 

 that the spectroheliograph might be employed. By obtain- 

 ing the ordinary spectroheliograms with K, and K^, and 

 then another in which the bright interspaces, i.e. the con- 

 tinuous spectruin, were projected on to the primary slit, it 

 would be possible to separate the parts due to the particles 

 from those parts of the chromospheric radiations due to 

 permanent gases. 



M. Deslandres further suggests that the same methods, 

 if successful in this instance, might be employed for the 

 analysis of the structure of other celestial bodies such as 

 nebul.-v and comets. 



Stars with Variable Radial Vixocities. — .\ list of four 

 stars the radial velocities of which have been found to be 

 variable is published by Mr. J. H. Moore in No. 3, vol. 

 xxiii., of the .Astrophysical Journal. 



The radial velocity of t Ursae Majoris has been found to 

 vary between — i km. and —10 km., that of A. Hydrfe 

 between -(-15 km. and -|-24km., and that of fi. Ursae Majoris 

 betwi-en —16 km. and +2y-^ km. In the case of 

 A' Ophiuchi, discovered to be a spectroscopic binary bv 

 Mr. S. .'\lbrecht, the variation of the velocity is found to 

 agree, in point of time, with the light variation, both 

 hax'ini^ the period 17-12 days. 



Four other spectroscopic binaries with variable velocities 

 are announced by Prof. Frost in the same journal. The 

 first two, B.D. — i°.ioo4 and 29 Canis Majoris, are re- 

 markable for the long range of their velocities and their 

 short periods. In the former of these two, the radial 

 velocity changed from 4-132 km. on February 12 to 



xo. 1 9 10, VOL. 74] 



-34 kin. on February 16, whilst that of the second star 

 changed as follows: — igo6 January 26, —164 km.; 

 January 29, —3 km.; February 12, —243 km.; February 

 16, -92 km. Owing to under-exposure, these results are, 

 however, slightly uncertain. 



The stars V Orionis and T Monocerotis have also been 

 shown to have variable velocities in the line of sight. 



Observations of Nova Persei No. 2. — No. 96 of the 

 I.ick Observatory Bulletins is devoted to the publication of 

 the results obtained by Messrs. Townley and Maddrill from 

 magnitude observations of Nova Persei No. 2. 



The observations extended over the period February 24, 

 1901, to July S, 1902, the magnitude on the latter date 

 being 9-4. 



The table given contains the weighted, mean magnitudes 

 of the Nova on more than one hundred nights, with notes 

 on the observing conditions and the comparison stars and 

 instruments employed. 



Observations of Shadow Bands. — In No. 4086 of the 

 Astronomischc Nachrichten Dr. M. Roso de Luna, of 

 Madrid, briefly describes a new arrangement of screens for 

 the observation of the shadow bands during total eclipses 

 of the sun. Altogether ho proposes to employ six screens, 

 one horizontal, two vertical (N. and S. and E. and \V.), 

 one oriented to the azimuth of the sun at the moment of 

 totality and another perpendicular to it, and one placed in 

 the direction of the wind. 



Such an arrangeinent was employed at Soria (Spain) 

 during the last eclipse, and the following results obtained ; — 

 breadth of bands, 2 cm. : distance from one band to the 

 next, 6 cm. ; velocitv of the movement of the bands, 

 30 metres per minute. 



The Radial Motion of ;3 Arietis. — In No. 4090 of the 

 .{strononiische Nachrichten Ilerr H. Ludendorff publishes 

 the results obtained from an investigation of the radial 

 velocities of .\rietis during the period October 21, 1902, 

 to December 16, 1904. 



Thirty-seven spectrograms were obtained with the spectro- 

 graph No. iv. (three prisms) of the Potsdam Observatory 

 attached to the 32-3 cm. refractor, and the range of the 

 velocities determined was from -|-6o km. (on January 19, 

 1903) to —17 km. (on December 25, 1903)- 



From an analysis of the results, Herr Ludendorff con- 

 cludes that the period of B Arietis is 321/n days, where h 

 is equal to or less than 5. 



Publications of the Nicolas Observatory, St. Peters- 

 burg. — We have just received vols. iii. and xiv. (series ii.) 

 of the " Publications de I'Observatoire central Nicolas, 

 St. Petersburg." 



The former contains a catalogue of right-ascensions of 

 the principal stars contained in the Pulkowa catalogue for 

 the epoch 18850, the results being based on observations 

 made between September, 1880, and November, 1887, with 

 the meridian telescope. The catalogue is published in the 

 same form as those which appeared in 1845 and 1S65. 



Vol. xiv. contains a part of the results of the observ- 

 ations made with the vertical circle of the observatory 

 between May i, 1896, and May 19, 1899. The remaining 

 part of the results and the discussion of the whole are 

 reserved for the next volume (xv.) of the publications. 



THE ROYAL OBSERVATORY, GREENWICH. 

 'yUE annual inspection of the Royal Observatory, Green- 



-'■ wich by the Board of Visitors took place on Wednes- 

 day, May 30, when the .Astronomer Royal submitted a 

 report of the w^ork accomplished during the twelve months 

 May II, 1905, to May 10, 1906. A brief summary of this 

 report is given below. 



The new working catalogue of stars of the ninth magni- 

 tude and brighter, situated between declinations -(-24° and 



■1-32°, is now complete, and includes more than 12,000 

 stars ; the star-places have all been accurately brought up 

 to 1910 from the Astronomische Gesellschaft catalogues. 



K new determination of the oivot errors of the transit 

 instrument, made during November, showed that the errors 

 in the form of the pivots are insensible. The determination 

 of the co-latitude for 1905 has been delayed by the necessity 



