June 3, 1922; 



NATURE 



727 



International Astronomical Union. 



T^HE meeting of the International Astronomical 

 ^ Union at Rome on May 2^10 must be considered 

 an unqualified success. The unique interest of the 

 selected meeting-place was doubtless a useful auxiliary 

 in drawing together so large a number of delegates ; 

 upwards of 100 were present, representing England, 

 France, Italy, Spain, Holland, Belgium, Denmark, 

 Norway, Sweden, Poland, Egj-pt, S. Africa, Australia, 

 New Zealand, Canada, United States, Japan, etc. 



The inaugural meeting of the Union at Brussels in 

 July 191Q was mainly occupied with questions of 

 procedure ; the way was thereby cleared for more 

 purely astronomical discussions on the present 

 occasion. The main aim underlying these was the 

 co-ordination of various branches of observation and 

 computation, so as to obtain as large an output as 

 possible without waste of energy through unnecessary 

 duplication ; there was also consideration of methods 

 of observation and reduction, and of the unification 

 of notation. Much of the credit of the success 

 obtained is due to the presidents of the various 

 committees, who had drawn up careful and thorough 

 programmes, after correspondence with their mem- 

 bers ; these served as a basis for discussion, and were 

 in most cases endorsed with small changes. 



The opening meeting was held in the Campidoglio 

 in the presence of the King of Italy ; it was addressed 

 by the Mayor of Rome, the Minister of Public In- 

 struction, the president of the organising committee 

 (Prof. Volterra) and by the presidents of the astro- 

 nomical and geophysical unions (MM. Baillaud and 

 Lallemand). The subsequent meetings were in the 

 beautiful rooms of the Reale Accademia dei Lincei, 

 Palazzo Corsini. The Union met in full conference 

 at the beginning and end of the meeting ; the more 

 important discussions were carried on in separate 

 committees, the conclusions of which were reported to 

 the final meeting of the Union. 



A summary of the more important conclusions may 

 be of interest. In the matter of notation the Harvard 

 system of spectra was considerably amplified ; the 

 prefixes c, g, d are used to denote super-giants, giants, 

 and dwarfs ; e to denote the presence of emission 

 lines ; p, q to denote peculiarities tending in the 

 direction of Nova spectra ; s, n denote that the 

 spectral lines are sharp and diffused respectively (w 

 was used by Rowland to denote nebulous lines in the 

 solar spectrum) ; r denotes reversal, i.e. bright lines 

 with a dark centre ; k denotes stationary calcium lines. 



It is proposed to use Mo, M3, M8 instead of Ma, 

 Mb, Mc, and to drop M^, it being suspected that the 

 imderlying spectrum in the latter case is not of M 

 tvpe ; similarly No and N3 replace Na and N6. S is 

 used for a new type of red stars, to which R Cygni and 

 R Andromedae belong ; Q is used as before for Nova 

 spectra ; they are subdivided by the suffices, a, b, c, 

 u, X, y, z, in which the absorption spectrum grows 

 progressively weaker, and the bright-line spectrum 

 stronger ; in general a star traverses these types in 

 the above order in the weeks or months succeeding 

 the outburst. 



Another point of notation decided was that the con- 

 stellations should be given their Latin names, which 

 has been done in England but not in France. As 

 regards the Carte du Ciel, special votes of thanks were 

 passed to Cardinal Maffi and to the Nizam of Hydera- 

 bad for their great assistance in carrying out the 

 astrographic work at the Vatican Observatory and 

 at Hyderabad. Representations were sent to the 

 respective governments concerned, urging the com- 

 pletion of the work of photography and of printing 

 at the observatories of Catania, « Melbourne, and 



NO. 2744, VOL. 109] 



Sydney. The progress of work at the other observa- 

 tories is good or hopeful, though it was much retarded 

 by the war. Prof. Turner reported that the maps of 

 the lunar surface had been completed, and the list of 

 crater-names prepared, but not yet inserted on the 

 maps. M. Lecointe announced that the Uccle Obser- 

 vatory would not continue the distribution of 

 astronomical telegrams after the end of 1922. The 

 offer of M. Stromgren to send them from Copenhagen 

 (as he did for some years after the outbreak of war) 

 was accepted. 



The variable star committee met under the chair- 

 manship of Prof. H. Shapley ; it is in this section, 

 above all, that co-ordination of work is imperative. 

 It was decided to print several appendices, giving 

 bibliographies of variables, lists of those needing 

 observation, and determining centres of publication 

 for various classes of stars ; the Cracow Observatory 

 undertook the preparation of ephemerides of eclipsing 

 variables ; attention was also directed to the useful 

 reprints of Father Hagen's charts of the fields of 

 several variables. Regarding the nomenclature of 

 Novae, it was recommended to use the constellation 

 name followed by the year of discovery ; the method 

 of giving numbers i, 2, 3, etc., to the Novae in each 

 coJistellation leaves a doubt as to which early observa- 

 tions to include; their status as Novae is sometimes 

 doubtful. 



It was decided to continue to give the grants in aid 

 of the distribution of wireless time-signals, at least 

 for the next three years. Prof. Sampson, the presi- 

 dent of the committee, spoke in support of the great 

 value of these signals both for longitude determina- 

 tions and for checking the time determinations at 

 different observatories ; he discussed these recently, 

 finding that each observatory had frequently a large 

 discordance that remained nearly constant for some 

 time. These discordances were the subject of an 

 interesting debate between the astronomers and 

 geodesists ; the latter stated that they did not find 

 these discordances in their field work, and ascribed 

 them to irregularities of refraction due to the walls 

 surrounding the observing room. 



The committee on calendar reform reported in 

 favour of continuing the Gregorian calendar, and of 

 omitting one day in each year (two in leap-years) 

 from the weekly reckoning ; howiever, the latter point 

 was not adopted by the general meeting of the Union. 



The committee on stellar parallaxes expressed the 

 hope that workers would photograph each parallax 

 field at ten years' interval, in order to determine the 

 proper motions in each element of the comparison stars. 



Great praise is due to the Italian astronomers 

 for their excellent arrangements for the meeting, and 

 the help they afforded to the visitors ; mention may 

 be made in particular of Prof. Abetti, who showed 

 great skill as an interpreter. 



The next meeting was fixed for 1925 (probably in 

 August) at Cambridge, with Prof. W. W. Campbell 

 as president. The Geodetic and Geophysical Union 

 will meet in Madrid in 1924. 



The members of the Astronomical Union were 

 received in audience by the Pope on May 10, being 

 individually introduced to him by Prof. Pio Emanuelli, 

 secretary of the Vatican Observatory. The Pope 

 briefly addressed them, expressing the hope that the 

 meeting of so many nations for a common object 

 would tend to the pacification of the world, and that 

 their studies of the marvellous structure of the 

 heavens would lead to increased knowledge of and 

 reverence towards the Creator. 



A. C. D. Crommelin. 



