May 4, 191 1] 



NATURE 



323 



^ r,.!iiinorum, and its calculated magnitude is i5'0. The 

 o^--rvation by Dr. Wolf on .March 19 showed tlie actual 

 brightness, to be about one magnitude fainter than the 

 ephemeris value (Astronomische Nachricliteii, No. 4485). 



Proper Motions in Sin-spot Groups. — Dr. W. 

 Brunner, Zurich, has an important and interesting paper 

 in Xo. 3, vol. xl., of the Mciiwrie di Astrofisica cd Astro- 

 nomia, in which he discusses the relation^ (Kitting between 

 the proper motions observed in spot-group^ and the solar 

 aci'vity pmduring the groups. The discussion is based on 

 th- •xaiuiiKuJon of Wolfer's Zurich drawings for the period 

 iS.Sj-Kjos, and the spots born on the visible hemisphere 

 are considered separately from those whicli, having first 

 br<»k"n out on the invisible hemisphere, are first seen at 

 th'- . a>tirn limb ; only the proper motions in longitude are 

 di^cii^srd, and, in general, these are in the sense which 

 m ik.- the various members of the group diverge inter se. 



Th.- general conclusions, in brief, are that this diver- 

 g.Mn •' i> not accidental, but is connected with the phase of 

 dev.-loi)m.'iu of the group. In the early stages of develop- 

 ment tlii- diverging tendency is strongly marked, but it 

 rapidly \v:in>'s until it disappears seven or eight days after 

 the tir^t oiiilinak, unless a recrudescence of activity takes 

 |)lace, whiii the same phenomena r(:api)iai-. Taking as 

 positive tile proper motion, which is in tin- direction of the 

 diurnal motion, it is found that the groups in which 

 n'gaiiv'- motion is dominant are more numerous at the 

 epoch-, of maxima in the undecennial period. But it is 

 found that the magnitude of the proper motion is inde- 

 pendent of the phase of the solar activity and also of the 

 ivliographic latitude. As naturally follows from the first 

 conclusion, those spots born on the invisible hemisphere, 

 h.-ino ^.-M-ral (la\s old when first seen, exhibit the proper 

 mu!;<)n> in j I's^ marked d.gree than those of which the 

 p:::nar\- phages of development are observed. 



Tin Raiio 1;!. 1 \\i;i;n thk Diameter of a F'hotogr.^phic 

 l.MA(.i; AMI l-;\i'(.>srKK." -Tn the measurement of photographic 

 magniiutles ii\ in'a>uriiig the diameter of the star images 

 i- i- as>.Lnn.-d. in the formula usually employed, that the 

 : nii'i. T i- pi i>portional to the square of the intensity of 

 ■ 1' light. Not agreeing with the principle of this assump- 

 tion. Dr. Kenneth Mees recently made some experiments, 

 under laboratory conditions, in which he produced easily 

 measurable images with greatly differing exposures. He 

 finds that the diameter of the small image of a fine slit or 

 point is proportional to the logarithm of the exposure 

 given, and assuming that increase of exposure is effectively 

 quivalent to increase of intensity, this would mean that 

 he diameter of a star image should he proportional to the 

 ingarithm of the intensity of the light->ource rather than 

 to its square. Dr. Mees suggests that the astronomical 

 equation i~ li.i-~ed upon a modification of the trur law 

 d€f>endent on the conditions of the formation of iniage.s in 

 telescopes {Astniphysiiiil Journal, vol. xxxiii., Xn. i). 



Photogr.vi'iiic Mi.asi i;i.s nv Stellar Te.mpek aures and 

 Diameters. — In Xo. 44Si of th.' Astronomischc Xcicliricliten 

 Herr Adolph Hntitek ptd)lishes an interesting paper on a 

 photospectroscopic method of determining the effective 

 temperatures and relative diameters of stars. The photo- 

 graphic intensities of various parts of tlf sperirum are 

 compared, and from th< r^ suiting dat.i .1 t inperature 

 scale is formed. This r,ini;e> from 4000° for 1; Pegasi to 

 n6oo for Algol, eiei,t si.ns being considered, and agrees 

 fairlv wej! with the I'ot-vd.un values wh'M-e comparable. 

 It aUo pl.ii • ~ the .'ieiit ^i;i,-v in ill'' iirogr.'ssive order 

 shown h\' th'- Kensington l<inp' rature rut\'e The com- 

 parison of diameters sh<>w> that a l.yi.e i-> o- 1 ^r. iter than 

 thf sun, whilst o Aquil.-c is hut r-o tini'-- ^^nai-i . 



' Observer's Ha.ndhook for 191 i. An . \e. l- 



1' ok for amateur and other astronomei ^ i^ issued 



bv ;!;■ ' \ .t Kinoniii al Society of Canada, :u)d 'diled 



by M: * h.ini. The first two lunnher- w-.C'- pub- 



lished , . , , ...d iniiS, ,111(1 then the e\pi rinient ot puhlish- 

 ing th'- inloi in.itinn in instalments in th' so(i'-i\\ Journal 



was tri'-'l. This l)roVed unsatisfactoi\ . nel :h !'.rin'-i 



custom of having a separate vf>lin)ie h.i 



The book should prove of inv.ilii.dij. 



rapidly growing body of ainnteur .isii..i," h'- 



Dominion, and it is hop<>d to juihli^h th' \. >! i ,\2 



bf-fo-'" fhe beginning of the new year. 



.\ >. 2166, VOL. 86] 



THE IMPERIAL EDUCATION CONFERENCE. 



''PHH public sessions of the first conference of delegates 

 *■ summoned by the British Government to represent the 

 Overseas Dominions were held in London on four after- 

 noons, April 25-28. The President of the Board of Educa- 

 tion welcomed the representatives, and presided at each 

 meeting. Administrative problems were, it is believed, 

 discussed at the morning sessions, to which only the official 

 delegates were invited. The proceedings at these morn- 

 ing ni'-'-tings W'T'- private, the conference agreeing at its 

 first ni'-'-t!n;_; that, in order not to hamper discussion, no 

 ref)on should b'- made until the close of the conference, 

 when an official summary will be issued. At the time 

 of writing, all that can be said with certainty is that the 

 private sessions are being prolonged into the week follow- 

 ing the public meetings. Admission to the afternoon dis- 

 cussions was by tickets issued to representative adminis- 

 trators and teachers. The attendance of the overseas dele- 

 gates in the afternoons was not large. The programme 

 drawn up by the Board of Education included papers on 

 the teaching of geography, history and arithmetic, manual 

 work, the organisation of secondary education in Scotland, 

 engineering, and vocational education. All the papers were 

 by well-known British workers in the educational field. 



Chair>}ian's Prologue. 



Mr. Runciman said that the conference originated from 

 requests made in 1907 to the Imperial Government to 

 summon an Imperial Conference to deal purely with educa- 

 tional affairs. {," The Federal Conference on Education," 

 held in 1907, was initiated by the League of the Empire, 

 and was unofficial and highly successful.) Since 1907 the 

 Department of Special Inquiries and Reports had been in 

 direct communication with the Dominions, India, and the 

 Colonies, there had been improved circulation of reports, 

 and memoranda had been compiled during the four years 

 which would be issued shortly. x\ssistance was being 

 given every day in the week in the selection of teachers, 

 e.g. for Alberta, Australia, and South Africa. They had 

 also arranged through the Department that the privileges 

 now given to the teachers in the United Kingdom in 

 French and German schools should be extended to teachers 

 throughout the Empire. Assistance was continually being 

 given to visiting oflficials. A library of considerable 

 dimensions had grown up containing carefully selected and 

 organised contributions from all over the world. The 

 problems to be faced h(^re and overseas were very similar. 

 There were thi- difticulties of the supply and training of 

 teachers, the problem of giving freedom of organisation 

 while retaining control of finance. All the subjects of 

 pedagogy wre of universal interest. They had to deal 

 with the puzzle of the classification of schools, with rural, 

 urban, and technical problems. The United Kingdom 

 might learn from Canada, Canada from Australia. 

 Australia from South .Africa, and so forth. They wished 

 to bring to the common stock the intellectual forces of the 

 whole Knipir'-, and feed the vei-\- i-oot of Iniperi.-il strength. 

 The Empire' w.i^ .i pr.-uiical working concern, not iiieri-h' 

 a sentimental vision, and they were met to discn-s pi-.uiical 

 questions. 



Imperial llistiuv and Geography. 



Mr. H. J. M.ickindei , M.T., read a paper on the teach- 

 ing of geography from an imperial point of view, and 

 the use which could and should be made of visual instruc- 

 tion. He asked for attention to a mode of teaching which 

 might have peciditir \.ilue in the consolidation of the 

 Empire, a work in which the part of the teacher must be 

 as great as that of th' -talesman. The Empire existed 

 bv the free consent ot the peoples, and this consent 

 niu-t he h:is'-d on a j-,ason.dili^ agreement in r' 

 ,iiin- ,ind synipath_\- in regard to difficulties. It 

 part of the teacher to exorcise the devils of ignoi.im' ,m'i 

 local prejudice. Geography should be taui^ht as a sp. ciil 

 mode of thought — a special form of visu.ilis.it ion whiih If 

 would not 'I'-sciib.' otherwise than as " thinkine ^.,-o- 

 grai)hic.illy. " lie went on to describt^ th.' woik «>l th'- 

 \ i-.ual Instruction Coinniitti'i-, .md concluded h\ urgint; 

 th.'it geographv should 1)'- tin- 1 hii'f outlook suliject in our 

 school curriculuni, and >hould he t.iught bv methods which 

 demand visii.ilisation. W'e should .-liin .at educating the 

 citizens of the many parts of the British Empire to 



