January 30, 19 13] 



NATURE 



603 



by means of rigid surfaces, the stability asked for 

 being somewhat similar to that of a Canadian canoe, 

 which allows rolling' up to a certain inclination for 

 very small movements of the occupant, but offers 

 great resistance to any motion beyond that limit. 

 Such stability, if realisable, would leave the aeroplane 

 sensitive to the pilot's control except in cases of 

 emergency, when the aeroplane had departed con- 

 siderably from its position of equilibrium, when it 

 would assist the pilot to regain control. If, alter- 

 natively, it should ultimately be decided that the pilot 

 must be assisted automatically, then some such device 

 as the Clarke Johnson gyroscopic control exhibited 

 might be used. 



SCIENCE AT RECENT EDUCATIONAL 

 CONFERENCES. 



IX a previous article (January 23) reference was 

 made to the teaching of physiology and hygiene 

 in schools. At the London County Council Confer- 

 ence of Teachers a considerable portion of the pro- 

 gramme was concerned, directly or indirectly, with 

 these subjects. Prof. Starling presided at the fourth 

 session, and referred to the training in physiology 

 of the teacher and the training in physiology or 

 hygiene of the child. It was sufficient if the child 

 was brought up with the knowledge of the rules of 

 right living, but these rules were founded on physio- 

 logy, and the teacher must have reason for the faith 

 that was in him. On that ground the Physiological 

 Society had appealed to the Board of Education to 

 provide additional facilities for the study of physiology 

 by teachers, and to make such studv compulsory. 



At the same meeting Prof. Leonard Hill gave an 

 address on open-air and exercise, Mrs. Truelove read 

 a paper on instruction in infant care in girls' schools, 

 and Mr. A. J. Green discussed the value of the open- 

 air school. It is further to be noted that, at each of 

 the three preceding sessions of this conference, sub- 

 jects bearing closely on the health of the children 

 were brought forward, and the medical profession 

 figured prominently in the discussions. As we are all 

 aware, the tendency to pay regard to the physical 

 welfare of school children is prominent in the pro- 

 grammes of other educational meetings — e.g. British 

 •Association, Section L. Why this exceptional solicitude 

 at the present time? 



It may be granted that administrative and political 

 factors have given much strength to this movement, 

 but there are perhaps somevvhat deeper reasons for 

 the ready response of teachers to the call now made 

 upon them to regard their work as one of the agents 

 in determining the health of the nation in years to 

 come. One of these deeper reasons is that biology, 

 with her handmaiden evolution, is come into her own. 

 The child is viewed as an organism ; teachers and 

 administrators are thinking biologically. The old 

 platform tag, mens saiia in corpore sano. implied a 

 dualitv of mind and body, whereas to-dav we recog- 

 nise that the mens and corpus are educationally in- 

 separable. The psychology of McDougall and the 

 newer school is the offspring of a union of the old 

 psychology with biology — it is not a mere change of 

 the old, but a new-born science. And of this new 

 source of inspiration teachers are drinking in increas- 

 ing numbers. 



The papers of the third session of the L.C.C. Con- 

 ference were devoted entirely to an exposition of the 

 modern teachings of psychology on the subject of 

 attention. Prof. Spearman, who presided, stated the 

 relations between psychology and education as those 

 NO. 2257, VOL. 90] 



of "equal allies who had a joint mission — perhaps the 

 greatest national mission — the making of the nation 

 itself." The words just quoted give the clue to the 

 other great influence which, side by side with psycho- 

 logy — the thinking biologically of the individual — is 

 now influencing the trend of educational ideals and 

 progress. This second influence is to be found in 

 the growing sense of social and economic inter- 

 dependence — the thinking biologically of communities 

 — the viewing of the State as an organism, and even 

 of world-commerce as an organism. Hence the feel- 

 ing that an education lacks an important essential 

 which neglects that promising avenue of human pro- 

 gress — the study of economics. There also flows from 

 this sense of social solidarity an increased sense of 

 responsibility for the economic conditions affecting 

 the lives of the poorer classes. 



These trends of thought and feeling found respective 

 expression in the educational conferences in the dis- 

 cussions on economics for schoolboys at the L.C.C. 

 Conference, when secondary education was being dis- 

 cussed, and in those on household economics of the 

 poor, at the meeting of Te.achers of Domestic Sub- 

 jects. At this meeting Mr. J. Wilson proposed to 

 weave the two threads of State and domestic 

 economics when he suggested that, in the allocation 

 of the State Development grants, the claims of in- 

 vestigation into possible improvements of methods or 

 appliances used in household work should receive con- 

 sideration. 



That thousands of teachers assembled during their 

 Christmas holidays in twenty conferences in order to 

 " talk shop " shows to every thoughtful person that 

 the teaching profession is spiritually sound. This 

 article fails if it does not indicate, however imper- 

 fectly, that the profession is studying its calling with 

 the methods of science, and is no longer satisfied with 

 empiricism. The growth of a body of educational 

 workers thus animated with scientific purpose is the 

 best warrant, if not of the present existence, at least 

 of the imminent development, of a science of educa- 

 tion. G. F. Daniell. 



MODERN MICROSCOPICAL OPTICS WITH 

 SPECIAL REFERENCE TO FLUORITE 

 OBJECTIVES. 



GAUSS'S theory of lenses and other optical 

 systems, which was published in 1840 in his 

 " Dioptrische Untersuchungen," and subsequently 

 largely e.xtended by many other investigators, rendered 

 it possible to apply the cardinal theorems relating to 

 the formation of optical images to the most com- 

 plicated systems of lenses, of which already in Gauss's 

 time the microscope objectives furnished a good 

 example. This theory paved the way for the com- 

 putation of microscopic objectives and furnished a 

 means of studying the optical principles of the micro- 

 scope as a whole and the objective and eyepiece con- 

 sidered separately. 



Even before Gauss, Fraunhofer in 1820 had suc- 

 ceeded in devising a complete system, enabling him 

 to compute telescope lenses, and a little later Seidel 

 and Steinheil evolved a similarly complete system 

 for the computation of photographic lenses. 



Prof. E. Abbe, who in 1S66 became associated with 

 the optical establishment of Carl Zeiss in Jena, was 

 the first to venture upon a complete calculation of 

 the microscope objective by applying the theory of 

 Gauss. After a series of futile attempts, he estab- 

 lished a system by which a microscope objective could 

 be computed in every detail. The methods by which 



