546 



NATURE 



[June 30, 192 1 



recent Government grant of 50o,oooL — a sum, 

 however, which is less than half what is required 

 to put the pensions of the senior members of the 

 university staffs upon a satisfactory footing. In 

 addition, the Carnegie Foundation will continue 

 to provide retiring allowances on the same non- 

 contributory basis to a certain number of old and 

 distinguished teachers. Next, in the British 

 system there is no specific provision for widows 

 or orphans, nor is there provision for disability 

 such as has been instituted by the Carnegie 

 Foundation " for the teacher who, despite his own 

 foresight and self-denial, finds himself and his 

 family the victims of disease or of accident." 

 The reserve accumulated to meet such claims is 

 now 220,000 dollars. 



Further, the American scheme is administered 

 from within, as opposed to the Federated System, 

 which is worked through insurance companies. 

 In consequence, there is economy in administra- 

 tive and other expenses. Insurance companies 

 are not philanthropic institutions. Mr. Fisher, 

 President of the Board of Education, on the 

 second reading of the School Teachers (Super- 

 annuation) Bill, . 1918, was aware of this 

 when he stated that if the Act were worked 

 through insurance companies there would be the 

 objection that public money was going in divi- 

 dends to the shareholders of these companies. 

 This is precisely what is happening in the 

 Federated Superannuation System to-day. The 

 Teachers' Insurance and Annuity Association 

 furnishes policies better suited to the teacher's 

 needs, and at lower cost, than companies operating 

 on a commercial basis. 



The report contains a mass of interesting 

 matter relating to pensions and pension schemes, 

 including arguments, by no means convincing, in 

 favour of contributor^^ schemes as opposed to 

 non-contributory. 



Lord Rayleigh's Scientific Papers. 



Scientific Papers. By Prof. John William Strutt. 

 Vol. vi., 1911-19. Pp. xvi-i-718. (Cambridge: 

 At the University Press, 1920.) 505. net. 



THE sixth 1 volume of Lord Rayleigh's col- 

 lected works, just issued by the Cambridge 

 University Press, contains his papers, nearly one 

 hundred in number, published between 191 1 and 

 his death in 1919. In fact, the last two papers,^ 

 Nos. 445 and 446, of the whole series were left 

 ready for publication, but had not appeared when 



1 A notice of vol. v. appeared in Nature for October 28, 1913. The 

 other volumes were reviewed at an earlier date. 



NO. 2696, VOL. 107] 



he died, while the concluding paragraphs of 

 No. 444, on "The Travelling Cyclone," were- 

 dictated by him only five days before his deathi 

 on June 30. He was happy in being able to con- 

 tinue his work until so near the end, and in his 

 fifty years of active scientific life to achieve so- 

 much. 



The papers in the volume range over a wide 

 list of subjects, and while none of them have the 

 importance of some of those appearing in earlier- 

 volumes — e.g. the series on the fundamental units 

 of electrical measurements, or the publications, 

 describing his work on gases and the discovery of 

 argon — they are marked, as ever, by his power 

 of clear thinking, his grasp of first principles, 

 and his ability to appreciate the essentials of 

 any problem which appealed to him. Some three 

 or four of the articles were contributed to the- 

 discussions of the Advisory Committee for Aero- 

 nautics, over which he presided for ten years. 

 Among these may be specially mentioned No. 389,. 

 the note on the formula for the gradient wind, 

 in which the formula connecting the velocity of 

 the wind, the barometric pressure, the latitude, 

 and the rotation of the earth, which had beem 

 employed by Gold and other meteorologists, is 

 derived, assuming the motion in two dimensions, 

 from hydrodynamical principles. The paper 

 No. 444, already mentioned, on "The Travelling 

 Cyclone," though not formally communicated to» 

 the Committee, arose out of its discussions. 



There are also some notes and reviews com- 

 municated to Nature, but most of the other 

 articles appeared in the Philosophical Magazine. 

 Hydrodynamics, optics, and acoustics form the 

 subject-matter of many — problems of vibrations in; 

 the solution of which the methods developed in 

 the theory of sound or in some of his earlier 

 optical work are employed with success. Of 

 recent years he returned to a number of optical 

 problems which in earlier days had interested him, 

 and advanced our knowledge by his work. Among 

 these papers may be mentioned several on the 

 scattering of light by small particles. The 

 problem was discussed in the well-known paper- 

 on "The Blue of the Sky," published in 1871, 

 and in 191 8 Lord Rayleigh gave the complete- 

 solution for a sphere in which the structure is- 

 symmetrical, but periodically variable, along the- 

 radius, while a further paper — Phil. Mag.,. 

 vol. XXXV.- — discussed the case of the scattering 

 of light by a cloud of similar small particles of 

 any shape oriented at random. He was led to- 

 investigate the question by the results of his. 

 eldest son's experiments on light scattered by 

 carefully filtered gases. 



