April 12, 19 17] 



NATURE 



^n 



physicists and astronomers alike are involved in this 

 problem, but it is evidently an elusive one. Curiously 

 enough, as Fowler has proved by comparison with 

 other spectra, general series relations would permit 

 us to assign the disputed series to hydrogen or to 

 helium impartially, and it seems possible that both 

 elements may give the same spectrum under appro- 

 priate conditions. Bohr has also concluded from the 

 formula derived from the assumption of the return 

 of an electron to a lithium atom which has lost three 

 electrons, that lithium would emit lines close to the 

 Ralmer series. Bohr has not yet succeeded in apply- 

 ing his method to the case where an electron returns 

 to a singly charged helium or lithium atom, and hence 

 has not been able to account for the known helium 

 lines, •which are assigned by Stark to singly charged 

 atoms. Nor has he taken account of atomic mag- 

 netic fields, which, as Humphreys, Allen, and others 

 have shown, may exercise an appreciable influence. 



One of the most fascinating fields of research is 

 that of fluorescence and resonance spectra, in which 

 much work has recently been done, particularly by 

 Wood. He has found that white light will excite the 

 complete band and line resonance spectrum of sodium 

 or iodine, but that a single exciting line will cause 

 the emission of a line of the same length, and also of 

 a number of lines approximately equally spaced 

 which mav not always coincide in position with one 

 of the absorption lines. Thus the vapour is caused 

 to emit forced vibration, giving a spectrum not its 

 owm. As Wood has suggested, this method enables 

 us to strike one key of the complex vibrating system of 

 the atom, instead of the whole keyboard at once. 

 Time does not permit a detailed account of this re- 

 markable work, but it is evident that it may render 

 great service in the study of the rnechanism of the 

 atom. Nor is there time even to mention any of the 

 results obtained in the field of absorption spectra. 



After reviewing the work of the pa«rt decade, we 

 may feel encouraged by the progress that has been 

 made both in the perfecting and application of 

 spectroscopic methods of research and in the dis- 

 cover}- of new phenomena. Some of these discoveries 

 have led to fundamental revisions of our notions of 

 atomic structure. The Rutherford atom has defi- 

 nitely displaced that of Thomson. In some respects 

 this has seemed to make the problem more difficult, 

 but it has at least defined it more precisely. Many 

 attempts have been made to represent an atomic 

 structure which would satisfv the necessary mathe- 

 matical conditions, most of them so impossible as to 

 be absurd or so speculative that they suggest no ex- 

 perimental tests of their validity. The great merit 

 of Bohr's hypothesis is that it does lend itself to such 

 tests, and it is for that reason that I have paid special 

 attention to th^ methods of experimental attack which 

 seem to give the most concrete results in this connec- 

 tion. Hesitant as we mav be to accept in all its 

 details a theorv' which asks us to abandon laws upon 

 w^hich we have pinned our faith, this theory, and the 

 quantum theorv as well, mav be the flashes of genius 

 which reveal incompletely the outlines of the truth 

 towards which we struggle along a dimly lighted path. 

 Fuller knowledge may resolve some of our difficulties 

 and reconcile apparent contradictions. Ptolemy's 

 theory of epic\cles would appear wholly irrational to 

 one acquainted with Newton's laws but ignorant of 

 Kepler's conclusions, yet it correctly described the 

 facts as Ptolemy saw them. Some day the Keoler 

 and the Newton of the atom mav appear, but their 

 task will not be an easv' one. If the astronomer is 

 baffled by the problem of three bodies which he can 

 see, how can we expect to define the exact laws 

 determining- the motions of the invisible hosts of 



NO. 2476, VOL. 99] 



electrons and positive charges in an atomic system? 

 How can we hope to picture correctly the mechanism 

 which emits radiations of almost infinite complexity, 

 or account for the additional complications called 

 forth by external forces? We may be almost tempted 

 to accept the pessimistic view e.xpressed by Planck in 

 his Columbia lectures, that nothing in the world 

 entitles us to believe that it will ever be possible to 

 represent completely through physical formulae the 

 inner structure of the atom. And Kayser has said : 

 " \ true theor}- must assume a complete knowledge 

 of electrical and optical processes, and th^efore is a 

 Utopia." 



But even if we never reach the goal, who can set a 

 limit to our approach to it? We may ne\-er set foot 

 upon the promised land, but some day we may per- 

 ceive its shadowv outlines dimlv from afar. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 

 The Joint Matriculation Board of the Universities 

 of Manchester, Liverpool, Leeds, Sheffield, and 

 Birmingham has revised its regulations for entrance 

 to the faculties of medicine, and no k>nger requires 

 that Latin should be taken as an obligatory' subject. 

 The conditions imposed by the board for entry to 

 the faculty of medicine are now identical with the 

 general conditions for entrance to the several faculties 

 of the Universities. 



We learn from Science that the libran,' of the late 

 Prof. Hugo Miinsterberg has been given to Harvard 

 University by a group of his friends. The library^ con- 

 sists of about 10,000 books, pamphlets, manuscripts, 

 charts, and other papers. Among the 3000 books in 

 the collection are the latest and most valuable on ex- 

 perimental and applied psychology, especially those 

 bearing on aspects of the subject to which Prof. Miin- 

 sterberg had devoted his time. 



According to a recent article in the Frankfurter 

 Zeitung and an interview with a prominent librarian 

 at Frankfort plans are being considered for the estab- 

 lishment of a general technical librar>' at Frankfort- 

 on-Main, to be open for public use. One of the lead- 

 ing city libraries has become interested in the project, 

 and a beginning has already been made. A demand 

 exists for a library which will be of service to all the 

 numerous branches of the industn,' and trade in and 

 about Frankfort, the most important industrial centre 

 in South and West Germany. In this manner a 

 broader spirit of scientific and technical investigation 

 will be fostered. An atiemp*- will be made to furnish 

 technical information which will have a historical as 

 well as a purely scientific value. Technical libraries 

 have existed previously, but they have not been open 

 to the general public. Such libraries have been the 

 property of scientific societies, technical associations, 

 and the larger industrial concerns. The ser\ice ren- 

 dered bv these scattered collections was comparatively 

 small, as it was limited to members of the respective 

 organisations owning them. These were usually ham- 

 pered by lack of means and lack of facilities for 

 organising and arranging to the best advantage. The 

 plan that is now under way would combine these 

 private and semi-private libraries and put them under 

 the control of one of the established city libraries at 

 Frankfort-on-Main. The library chosen for the purpose 

 is the Frieherrliche Carl von Rothschildsche Oflfent- 

 liche Bibliothek. In addition to technical books, it 

 is stated that the chief .technical magazines of Ger- 

 many and of the world are to be placed at the 

 disposal of the oublic. A special feature will be 

 the department for patent publications. Not only wi'l 



