Ii 4 



NATURE 



[October io, 191 8 



d Ltd., referring to th< article by 

 Mr. Chapman Jones, in Nature <>t Octobei .s, on 

 coloiii 1 tised plates, write to say that the filter 

 used for thi photographs mentioned in the article was 

 nut a yellow filter, but their pale green filtei No. 240, 

 ntroduced for use with their special rapid 

 panchromatic plate:. Mr. Chapman Junes did not for 

 wish 10 suggest that Messrs. llfprd were 

 not familiar with the proper use oi certain light- 

 filters, and regrets thai his article should have given 

 that impression, li is verj satisfactory to have their 

 assurance that the lack ol perfection in the one 

 example examined is due to the priming and reproduc- 

 tion processes rather than to the photography, owing 

 chieflj iu the difficulties in obtaining suitable inks. 

 \ reference to Mr. Chapman Jones's article will show 

 thai he <liil not credit anyone with having produced 

 .1 plate "i even 1 tiveness throughout the visible 

 normal solai spectrum, or, indeed, the spectrum of 

 any other of the usual light sources. Those who 

 use II ford X-ray plates will find a pamphlet just 

 issued 1>\ the company oi considerable service, 

 especially il the) have difficulty in getting contrast, 

 of are uncertain as to the best method of treating 

 them The "Notes" also contain advice as to print- 

 ing from the plates, and the application of films fur 

 denial purposes which are put up in a special manner 

 read\ Foi use. Hall a dozen excellent reproductions 

 are included. 



THE latest catalogue of Messrs. J. Wheldon and 

 Co., j8 1. real Queen Street, W.C.2 (New Sen,,, 

 No. 85), deals with ornithology, and should be of 

 interest and service to manv readers of Nature. It 

 contains many first and rare editions, and is con- 

 veniently arranged under the headings of British 

 Islands, Cage Birds, Game Birds, etc., Pigeons and 

 Poultry, Europe, Asia, Africa, North America, South 

 America, Australasia, General Systems, etc.. Miscel- 

 lanea, and Morphology. We notice that Messrs. 

 \\ heldon have for disposal man) sets and lung runs of 

 scientific serials, e.g. the this, "British Birds," 

 "Novitates Zoologicse," "Proceedings of the Zoological 

 Society of London," the Zoologist, etc. The cata- 

 logue is sent post free on receipt of 2d. 



OUR ASTRONOMICAL COLUMN. 

 1 m. Mh furnace Spectra.- An important study of 



the spectra of calcium, strontium, barium, and mag- 

 nesium, as produced in the electrii furnace al tem- 



11 es of 11150°, 2000°, and 2350 C, lias been made 



Dr. A. S. King at the Mount Wilson laboratory 



bhys. /■•mil., vol. \Kiii., p. 13). The extension 



■ 1 rvations into the ultra-violet has shown that 



i limil beyond' which no lines arc emitted 



mperature, and that the limit advances 



tow. 11 ! hortei wave-lengths with increase of tem- 



peratu th< case of the continuous spectrum 



of an it solid. The observations bring OUl 



verj cli ...1, hi istics of the various lines, and 



permit th sification in relation to temperature. 



I be line a is unique among the calcium 



lines, being th arc and much weaker at high 



than ai lov thi tin 11.11 1 , it is much 



strengthened in tie- spectra ol sun-spots, and ma) be 



used with confidenci s a low-temperature indicator. 



In agreement with pi : . ,|,,. magnesium line 



• v -457 r was also found to be a 1 1 v-temperature line of 



extreme type. In thi aim, there is nut 



merely a sharpening of Hie li - compared with 



the arc, but in several cases , resolution 



f diffuse arc lines into two,, ... onents ; the 



■ 1 lines possibly occur among the Cant absorp- 



in lines of the solar spectrum, su that the 

 XO. 2554, VOL. I02] 



solar conditions in the region where these lines are 

 ptiidun-il involv, a moderately high temperature com- 

 bined with iu.', pressure. 



The Nebular Hypothesis. The present position of 

 the nebulai hypothesis is discussed by Prof. J. H. Jeans 

 in an interesting article which appears in the October 

 issue of Scientta. The absence of adequate observa- 

 tional evideno oi successive stages in the process 

 conceived b) 1 aplace being possibl) due to instru- 

 mental limitations, the hypothesis can onl) 1 ed 



by mathematical research on the sequeno oi con- 

 figurations oi a rotating and condensing mass , gas. 



t )n the assump thai the mass is homogeneous and 



incompressible, it has been shown thai systems 

 corresponding 1 losely with binary and multiple stars 

 would be produced. When account is taken of the 

 increase of density towards the centre, onl) approxi- 

 mate solutions of the problem an- available. It 

 appeals, how, er, thai for densities greater than one- 

 quartei thai ol water the resuli would be ven similat 

 to thai for an incompressible mass, while for lower 

 densities the form assumed would be that of the lens- 

 shaped figure deduced by Ruche. In the latter case, 

 after the attainment of a certain critical velocity, no 

 further change of shape would be produced, but 

 matter would be ejected from the periphery, and, as 

 a result of tidal forces, the ejected matter would take 

 the form of two spiral arms. It can be further shown 

 thai these filaments will only break up when the) are 

 on a sufficiently massive scale, and that when a 

 reasonable value is assumed for the density of the 

 primitive nebula, the condensation nuclei would be 

 comparable in mass with the sun. It is thus suggested 

 that, while the process imagined by I. aplace is quite 



inapplicable to the solar system, its action is exhibited 



on a far grander scale in the giant masses of tin spiral 

 nebulae; the products of disintegration are not planets 

 and satellites, bui streams of stat s. 



THE PROBLEM OF ADULT EDUCATION. 

 |~"vUR1N(t the Session of 1917 the Ministei ol 

 -•--' Reconstruction, the Rt. Hon. Christopher 



Addison, appointed a Committee, of which the Master 

 oi Balliol is the chairman, "to consider the provi- 

 sion for, and possibilities of, adult education (other 

 than technical or vocational) in Great Britain, and to 

 make 1 ecommendations." 



The Committee has recentl) issued a most im- 

 portant interim report m ,1 7, price a/.i, which 



demands the earnest consideration of all who are. 

 interested in the industrial, social, intellectual, and 

 moral well-being of the nation. 



As a resuli of its inquiries and of the evident 

 the Committee has come to the conclusion that 

 before the just claims of adult education can be con- 

 sidered and adi quately met, it is indispensable to 

 have regard to the industrial and social conditions 

 under which tin nation exists. There is unquestion- 

 ably a wide and growing demand for education foi 

 adults of a non-vocational character, with a view to 



fuller persona] development and witli the object of 

 promoting a healthier social intercourse and generall) 

 of equipping lb,- workers, both men and women, for 

 wider industrial, social, and political responsibilities, 

 so that the) may lake their full and rightful 

 share in the national life and well-being. It is fullv 

 recognised in the report that the development of the 

 education of the child and of the adolescent, fore- 

 shadowed by Mr. Fisher's measure, now happily 



become law, is essential to further opportunities for 

 the continued education of the adult, who will thereb) 

 be the bettet fitted to avail himself of the experiences 

 of life, and to seek and find a wise solution of the 



