3'0 



NA rURE 



[July 30, 1908 



the governors additional professor of pfiysics, and Mr. S. 

 Herbert Cox as full-time professor of mining. .An addi- 

 tional professor of zoology, a professor of metallurgy, and 

 an assistant professor of botany are to be appointed shortly. 



The Manchester Microscopical Society is doing some 

 excellent pioneer work through the agency of its extension 

 section, the objects of which are to spread the knowledge 

 of microscopy and natural history among outside associa- 

 tions by means of lectures and demonstrations. We have 

 received a copy of the society's lecture list for 1908-g, and 

 find that local associations in or near Manchester may 

 select from forty-seven lectures on botanical, zoological, 

 and nature-study subjects, which certain members of the 

 society are willing to deliver gratuitously. The associa- 

 tions securing the services of lecturers are expected to pay 

 for hire of lantern-slides, travelling and out-of-pocket 

 expenses only. The Manchester Microscopical Society is 

 to be congratulated upon its efforts to bring scientific know- 

 ledge, in a popular form, before associations of persons 

 anxious to be instructed. Full particulars of this enter- 

 prising scheme may be obtained from Mr. R. Howarth, 

 honorary secretary of the section, 90 George Street, 

 Cheetham Hill, Manchester. 



We have received from Prof. L. Weber, of the University 

 of Kiel, a copy of his report to the Magistrate of Kiel on 

 the daylight illumination of the various primary and 

 secondary schools of the town, thirty-four in number. At 

 each of these schools measurements have been made of 

 the illumination of a surface placed horizontally on desks 

 selected as the best, medium, and worst illuminated, in 

 about four of the most representative of the rooms of the 

 school, on days when the illuminating power of the sky 

 was known. In addition, the solid angle subtended by 

 the portion of sky visible frpm each of the three 

 desks, and that subtended by the sky visible from 

 the middle window of each of the rooms tested, 

 were observed. The report contains a description of 

 the apparatus used, and details of some of the 

 most interesting cases are given. Prof. Weber considers 

 that an illumination equal to thirty candles at a metre 

 distance throughout the darkest month should be taken as 

 a minimum, and on this basis about 5 per cent, of the 

 rooms tested are deficient, and should be improved by the 

 provision of larger w-indows or by the trees in front of the 

 windows being trimmed. In congratulating Kiel on the 

 wisdom it has displayed in having an investigation of this 

 kind carried out, one is tempted to ask whether anv town 

 of the size of Kiel in this country has ever thought it 

 worth its while to have such measurements made, or is 

 everyone too much absorbed in the educational controversy 

 to think of the eyesight of the child? 



Earl Percy took part in the debate on the Indian Budget 

 in the House of Commons on July 22, and in his speech 

 gave a prominent place to the problems of Indian educa- 

 tion. After instituting a comparison between the con- 

 ditions of elementary education in this country and in 

 India, he said that in Englajid our system of education is 

 directed towards preparation for an industrial career. In 

 India almost the only industry is agriculture, but the system 

 does nothing to qualify the people for their calling in life, 

 and any special aptitude finds no outlet except in the law 

 or in Government employment. Speaking of technical 

 education, he remarked that it is seven years since a con- 

 ference at Simla went into all the phases of Indian educa- 

 tion, primary, secondary, and technical, and passed an 

 enormous number of resolutions, upon which it was ex- 

 pected prompt action would have been taken. The resolu- 

 tions dealt with the neglect of the study of the vernacular, 

 recommending that it should be carried on throughout ; 

 that the results of examination should be taken as pass- 

 ports to the universities and Government employment ; that 

 in secondary schools a modern side should prepare pupils 

 for a commercial career ; that relations should be estab- 

 lished between school authorities and chambers of com- 

 merce ; and, lastly, the subject of technical education was 

 dealt w-ith in a valuable report. Industrial institutionf; 

 were recommended for the diflferent provinces connected 

 With special local industries, with a system of apprentice- 

 ship in workshops under the supervision of Europeans, and 



NO. 2022, VOL. yS] 



the training of village schoolmasters iii tillage. Are we 

 really making substantial progress in any of these direc- 

 tions? he asktd,. and answered the question by saying the 

 whole reforming energy of the Government seems to have 

 been directed to. the universities. The increase in educa- 

 tional expenditure has taken place on too low a basis; the 

 total amount is almost insignificant. How can we ask 

 the Indian to believe that his own Government, which in 

 the last three or four years has sacrificed three or four 

 millions of revenue from the salt duty and opium, and is 

 contemplating large borrowing powers, cannot find money 

 enough to spend on the development of technical education, 

 which is of vital interest if the people of India are to be 

 prepared to take their proper part in the development of 

 industries? With regard to the general administration of 

 education. Earl Percy thinks we shall never get any real 

 enthusiasm or progress until the administration is reformed. 

 There is now a director-general of education, but it is 

 still the fact that, not only is there no member for educa- 

 tion in the Viceroy's Council, but the director-general, if 

 he wishes to bring any educational matter before tbe 

 member who represents the home department, has to do 

 so through the ordinary machinery of the office. Earl 

 Percy expressed the opinion that, having a member on the 

 Council directly representative of and responsible for educa- 

 tion, the director-general ought to be given the same right 

 and privilege of free access to the \'iceroy which it is pro- 

 posed to give to the new President of the Railway Board. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, May 7. — " Seleno-aluminium Biidges." 

 By Prof. George M. Minchin, F.R.S. 



A seleno-aluminium bridge consists of two plates, P, Q, 

 of aluminium separated by a very thin flake of mica and 

 having a thin layer of sensitive (or conducting; selenium 

 spread across one edge of the mica and the two adjacent 

 portions of the aluminium plates. We have thus the 

 separator of mica bridged over by the selenium, which, 

 of course, adheres to the two aluminium plates. If before 

 the bridge of selenium connected these plates, P, O, the 

 plates were connected in series with a battery and a gal- 

 vanometer, no current would flow, but when the selenium 

 bridges over the mica separator, the current passes. Let 

 Cj denote the strength of this current when the bridge 

 is completely screened from light. C„ will, of course, 

 depend on the voltage of the battery and the thickness of 

 the mica separator, as well as on the length of the edge 

 of mica covered by the selenium. 



If now the selenium layer is exposed to light, the 

 current will be increased — multiplied five times, or more, if 

 daylight is allowed to fall on the selenium. 



Owing to the extreme thinness of the mica, the intensity 

 of the light along any line of a spectrum (say that of a 

 star) can be measured if we know the w'ay in which the 

 current-strength, C, depends on the intensity, i, of the 

 light. The main object of experiments carried out recently 

 in the electrical laboratory at O-xford was to discover the 

 relation between C and i. After many assumptions of the 

 form C = C„-t-'cv^i, and others, it was found that no such 

 assumptions satisfy the observations, but that an equation 



of the form log ~i'", where i and « are constants 



C(i 

 for the particular kind of light employed, agrees very well 

 with experiment. Thus, suppose that we are using red 

 light of a particular wave-length, let C, be the value of 

 current when the intensity of this light is i',, and let C 

 be the current when the intensity is i ; then our equation 



log 





log 



(t) 



The red light employed was that obtained by passing the 

 light of a Nernst lamp through a thick column of water 

 (to cut off heat), and then through a solution of fuchsine. 

 This light was passed along a dark cylinder b metre-, 

 long, the length of w'hich could be varied by removing 

 metre lengths successively, and, as the selenium bridge 

 was at one end of this cvlinder, 1 was varied. Blue light 



