8i6 



NATURE 



[June 24, 1922 



is obscurity. Some vast and general views on the 

 construction of the heavens, and the laws which may 

 regulate the formation and motions of sidereal 

 systems, have, it is true, been struck out ; but, like 

 the theories of the earth which have so long occupied 

 the speculations of geologists, they remain to be 

 supported or confuted by the slow accumulation of 

 a mass of facts ; and it is here, as in the science just 

 alluded to, that the advantages of associated labour 

 will appear more eminently conspicuous. 



While much obscurity still remains, this vast terri- 

 tory has been definitely annexed and occupied. From 

 the planetary system we have passed to the stellar 

 system ; and I am not sure if even the study of that 

 great aggregation of stars which we used to think 

 was the whole universe is not becoming a little old- 

 fashioned, and the really up-to-date young astronomer 

 would refuse to bother about anything nearer than 

 a globular cluster. At least it is one of the most 

 startling features of recent research that so much 

 exact knowledge has been obtained of the conditions 

 of stars in globular clusters, not one of which is nearer 

 than 10,000 light-years — knowledge which in many 

 respects far surpasses in precision that which it has 

 been possible to obtain for the much nearer denizens 

 of our own star-cloud. 



It may be of interest to examine how this centrifugal 

 tendency is reflected in our Monthly Notices, and I 

 have prepared a table to show how the subject-matter 

 of the papers has changed. The figures claim no great 

 accuracy, because it is often difficult to classify the 

 papers clearly and uniformly ; and, of course, the 

 statistics do not distinguish important papers or long- 

 continued observations from trivial notes and con- 

 troversies. But on the whole the figures seem to be 

 truly representative. 



Classification of Papers in Monthly Notices, R.A.S. 



1840. i860. 1880. 1900. 1919. 1920. 

 {3 years.) 

 Instrumental ... 6 4 11 3 6 5 

 Solar System ... 39 69 73 56 14 21 

 Stellar universe. . . 18 13 22 21 49 40 

 Geodesy, navigation, seis- 

 mology, etc. ... 14 36 . . 5 II 



Ancient observations . 2 i ' i . . i i 

 Mathematical (not classed 



above) .... . . • • 2 . . i 12 



(Ditto, omitting ephemerides, tabular observations, etc., 



and formal reports of phenomena.) 



Solar system ... 9 38 34 21 11 17 



Stellar universe. . . 7 n 16 12 33 32 



It appears that the serious change did not begin 

 until after 1900. Although it shows itself quite sud- 

 denly in the statistics, it had been steadily prepared 

 for during a long period. It must be remembered 

 that much of the heaviest work on the stars is by its 

 nature excluded from the Monthly Notices, and appears 

 only in the more voluminous publications of observa- 

 tories. Solar, lunar, and planetary observations are 

 not usually too bulky to include. Much long-continued 

 preparation for proper motions, spectral classification, 

 radial velocities, stellar magnitudes, etc., began to 

 come to fruition between 1900 and 1910. But I think 

 the great impetus to sidereal astronomy came from 

 Kapteyn's discovery, which I have mentioned among 

 the six landmarks of the century. The two star- 

 streams were the first taste of the many amazing 

 results contained in the statistics collected or being 

 collected. They were the first indication to us of 

 something like organisation among the myriads of 



NO. 2747, VOL. 109] 



stars. Paradoxical as it may seem, the duality of the 

 stellar system was the first clear indication to us of its 

 unity. In the earlier years most of the papers classified 

 in the table as referring to the stellar universe dealt 

 with particular objects — variables, rapid binaries, 

 Novae. It was a period of individualism. But from 

 1900 onwards the great democracy of the stars was 

 brought into prominence, and a great wave of stellar 

 socialism began. Kapteyn is the typical pioneer of a 

 numerous body of investigators who view the heavens 

 in the spirit of Xavier le Maistre in " Voyages autour 

 de ma Chambre " : 



The most brilliant stars have never been those which 

 I contemplate with most pleasure ; but the tiniest 

 ones, those which, lost in immeasurable distance, 

 appear only as barely perceptible points, have always 

 been my favourite stars. 



Yet perhaps in the very latest years there has been 

 a reaction towards individualism. The statistical 

 mill is no longer working overtime. The queer stars, 

 such as Cepheids, runaway dwarfs, special binaries, 

 are beginning to contribute more largely to the general 

 perfection of the whole scheme. Strange objects 

 which persist in showing a type of spectrum entirely 

 out of keeping with their luminosity, may ultimately 

 teach us more than a host which radiate according to 

 rule. 



It is noticeable that in the early years the dis- 

 proportionate excess of papers on the solar system 

 compared with the outside regions of the universe 

 was not so marked as it afterwards became. This is 

 no accident. The founders of the Royal Astronomical 

 Society, while confessing almost complete ignorance 

 of this domain, were resolved that it should be attacked, 

 and had the conviction that patient research would 

 make the advance possible. Indeed, it was just this 

 which was placed among the most prominent reasons 

 for banding together. With regard to eclipses, planets, 

 and comets, it might be possible to struggle along 

 individually ; but the problems involving thousands 

 of stars were too vast for one man or for one generation. 

 They saw that the observations were being piled up, 

 but without uniformity and without system. To quote 

 again from their address : — 



One of the first great steps towards an accurate 

 knowledge of the construction of the heavens is an 

 acquaintance with the individual objects which they 

 present : in other words, the formation of a complete 

 catalogue of stars and of other bodies, upon a scale 

 infinitely more vast than has yet been undertaken, 

 and that shall comprehend the most minute objects 

 visible in good astronomical telescopes. To form 

 such a catalogue, however, is an undertaking of such 

 overwhelming labour as to defy the utmost exertions 

 of individual industry. It is a task which, to be 

 accomplished, must be divided among members ; but 

 so divided as to preserve a perfect unity of design. 

 . . . The intended foundation of an Observatory at 

 the southern extremity of Africa, under the auspices 

 of the Admiralty, may serve to show the general 

 sense entertained of the importance of this subject, 

 and the necessity of giving every possible perfection 

 to our catalogue of the fixed stars. Deeply impressed 

 also with the importance of this task, and fully aware 

 of its difficulty, the Astronomical Society might call 

 upon the observers of Europe and of the world to 

 lend their aid in its prosecution. Should similar 



