November 2, 1899J 



NATURE 



and we find that the gaseous and proto-metallic stars in- 

 crease in number as the proper motion decreases. We 

 find also the ratio of the metallic to the gaseous and the 

 proto-metallic. We begin with a ratio of 17, and end 

 with something like a ratio of half, so that the results 

 may be considered to be pretty definite. These results 

 were obtained by Kapteyn with 591 stars which were 

 common to Stumpe's catalogue of proper motions and the 

 Draper catalogue dealing with spectra. The general result 

 may, therefore, be stated that at the nearest distance the 

 metallic stars are seventeen times more numerous than 

 yaseous stars, and at the greatest distance they are not 

 half the number. Here again the question arises, how 

 far the intrinsic brightness of these bodies, in relation to 

 their distance from us and the possible greater or less 

 extinction of light in space, has to be taken into consider- 

 ation. That is a problem which will require a considerable 

 amount of work in the future. It is rather remarkable 

 that if we take the stars with very great proper motion, 

 very much greater than the average, we find with regard 

 to four that three of them are undoubtedly metallic, but it 

 is possible that the star 1830 Groombridge, which is al- 

 ways looked upon as the star which beats the record in 

 velocity seeing that it would travel from London to Pekin 

 in about two minutes, is not a metallic star.' 



We are now in a position to make a general summary 

 of the stellar distribution not only in relation to 

 chemistry, but in relation to distance. Taking the 

 chemistry as the basis, we can see what happens to the 

 gaseous, proto-metallic stars and so on, with regard not 

 only to their proper motions, but in regard to the Milky 

 Way. 



Summary of Stellar Distribution. 



Group. 



Proper motion. 



Gaseous stars Smallest 2 (Monck) 



Proto-metallic Intermediate (Monck) ... 



Metallic ... '■ Di v. i. Greatest (Kapteyn) 



I Div. 2. Small (Kapteyn) 



Mixed flutings ? 



Carbon ... I ? 



Relation to Milky Way. 



Milky Way 



IcCl( ■ 



Condensed 



(Pickering and McClean)' 

 Brighter ones n^t notably 



condensed in Milky Way 



(McClean) 

 Tend to collect in Milky Way, 



more especially the fainter 



stars (Pickering) 

 Not condensed in Milky Way 



(Pickering and McClean) 

 Collected in Milky Way 



(Kapteyn) 



The gaseous stars, which we have seen have the 

 smallest proper motion, are condensed in the Milky 

 Way. The proto-metallic stars, which have but inter- 

 mediate proper motion, are notably condensed in the 

 Milky Way according to McClean, and tend to collect 

 in the Milky Way more especially with the fainter stars 

 according to Pickering. When we come to deal with 

 the metallic stars, we find that there is no special con- 

 densation in the Milky Way. The greater number are 

 not condensed in the Milky Way. 



That being so, then, we may take a still further 

 general view. We find that the bright-line stars, the 

 new stars, are almost exclusively in the Milky Way and 

 are far away from us ; that the gaseous stars are chiefly 

 in the Milky Way and are far away from us ; that the 

 proto-metallic stars are not so confined to the Milky 

 Way, and they are not so far away from us. But when 

 we come to the metallic stars and the carbon stars they 

 have not much obvious connection with the Milky Way, 

 and they are close to us. Unfortunately, with regard to 



1 These stars are — „ 



1830 Groombridge 7-04 ... Gaseous or proto-metallic. 



22758 5-196 ... Metallic. 



2 578... 4'o49 ... Probably metallic. 



D.C. 583 3-7 ... Metallic. 



2 Kapteyn finds small proper motions for gaseous and proto-metallic 

 stars, but does not separate them into two groups. 



NO. 1566, VOL. 61] 



the metallic fluting stars the information is not certain^ 

 so that it is best not^to say anything about it. Mr. 

 McClean has dealt with a very small number, and he 

 shows that they, like Duner's stars, the carbon stars, 

 have very little relation to the Milky Way. We thus 

 obtain a tremendous separation between the hot stars 

 with their great distance and the cooler stars with their 

 smaller distance. 



But we can go further. As the stars become hot in 

 consequence of meteoritic collisions, we should expect to 

 find nebulous conditions following suit ; seeing that 

 nebuke are masses of meteorites, we should expect to 

 find especially the gaseous nebula; and results depending 

 upon their presence in the region where the hottest stars 

 exist. 



The planetary nebulae consist of streams of meteorites 

 moving generally in spirals or in circular paths. There 

 is no very great disturbance. We get a bright line 

 spectrum from them, and we know they are practically 

 limited to the Milky Way. We have found that the 

 bright-line stars are limited to the Milky Way ; they are 

 simply stars involved in nebulas. There again we get a 

 connection between the Milky Way and nebulae. The 

 new stars are due to fixed nebulas driven into by moving 

 nebulc-e, and they are also limited practically to the Milky 

 Way ; there again we have the nebulous touch. A 

 piece of work which has not been done, but which badly 

 wants doing, is to see whether those nebulous regions 

 which Sir William Herschel was the first to chronicle 

 have or have not a strict relation with the Milky Way. 

 I have, in fact, made a preliminary inquiry into this 

 matter, and it suggests that these nebulosities are most 

 profusely distributed in the vicinity of the Milky Way 

 just as is the case with the gaseous nebulae. 

 {To be continued.) 



SOME REMARKS ON RADIATION PHENO- 

 MENA IN A MAGNETIC FIELD} 

 T N many articles which have recently appeared con- 

 ■*■ cerning the work which has been done in the study 

 of radiation phenomena in a magnetic field, I find that, 

 from the historical point of view, there are some state- 

 ments which are not quite correct, and to which I now 

 desire to attract attention. This appears to me desirable, 

 as it is much easier, and much better, to test and 

 correct errors of statement at the outset than after a lapse 

 of time. 



In the first place, it has been very generally accepted 

 that the quartet form which occurs in the magnetic effect 

 was first observed by M. Cornu ; but on reference 

 to the enclosed paper ( Trans. Roy. Dublin Society, vol. 

 vi., series ii., p. 385, read December 22, 1897), you 

 will see that the quartet form,'^ the sextet, and other vari- 

 ations of the magnetic triplet were not only observed, 

 but were photographed and exhibited to an audience in 

 Dublin in the latter end of the year 1897. On the other 

 hand, it was not until the following year (1898) that M. 

 Cornu (working quite independently) announced in the 

 Comptes rendus that he had observed the quartet form. 

 Now the Comptes rendus being a weekly journal which 

 is widely read, lends itself admirably to the rapid diffu- 

 sion and circulation of new results, whereas the scientific 

 Transactions of a local learned society are slow in appear- 

 ing and little read or known outside their immediate 

 place of publication. For this reason, the observations 

 of M. Cornu became generally known, while mine 

 remained unknown outside Dublin. 



It is true, however, that I endeavoured to have them 



1 These remarks were addressed to Sir Normaa Lockyer in tbecours:ofa 

 correspondence, and have been thought of sufficient interest for publication. 



2 The quartets are clearly shown, as well as the triplet form, m the plate 

 attached to the paper, and reproduced from the photographs shown at the 

 meeting when the paper was read. 



