June 3, 1909] 



NATURE 



397 



j^iivnning iho pressure and delurmation of a confined 

 material element, and on the movements of fluids in 

 general, there are three sections dealing with pheno- 

 mena in which the influence of friction is neglisjible 

 or sensible, and covering the motion of waves and 

 th<' flow of water in pipes and channels. 



The second volume is occupied with the elucidation 

 of problems which appeal more particularly to the 

 jjractical engineer, who, apart from his interest in 

 the purely scientific aspect of an investigation, de- 

 mands for his use some definite, even if empirical, 

 tjuantitative solution. To arrive at such results, pos- 

 tulates of a more or less contestable character have 

 oftentimes to be assumed, and the processes cannot 

 be as rigorous as a mere theorist would desire. The 

 ^luestions treated in this way include the flow of 

 v.aler through orifices and over weirs, and in pipes 

 possessing abrupt changes of direction and sudden 

 restrictions of area. The influence of friction on un- 

 tlular movement is also expounded, and a final chapter 

 deals with water-hammer. 



The work is based on mathematical processes of a 

 verv advanced nature, and from considerations of 

 space the calculations, many of them intricate 

 enough, have been set forth as succinctly as possible. 

 For further information on particular points the 

 reader is referred to various sections of M. Bous- 

 sinesq's writings which deal specially with them. 

 There is a serviceable bibliographical index at the 

 end of each volume. 



The author manifests his keen appreciation of the 

 Iravaux pinitranis of M. Boussinesq, and concludes 

 his preface by stating : — " Qu'il n'est pas de question 

 d'hydrodynamique appliquee qui ne doive h. ce Maitre 

 des progres considerables." The tribute is just, and 

 will be heartily endorsed by British men of science. 



The Chad.-i.vxch Lectures, V>iiversity of London, Ses- 

 sion 1907-8. By W. D. Scott-Moncrieff. Pp. 7g. 

 (London : St. Bride's Press, Ltd., 1909.) Price 2S. 

 net. 

 The Chadwick lectures in the L^niversity of London 

 were established in 1907 for a period of five years, 

 the endowment being derived from the funds of the 

 trust created bv the will of a great sanitarian, Sir 

 Edwin Chadwick, K.C.B. The trustees have provided 

 that two short courses of lectures shall be delivered 

 each vear, at the University, upon subjects relating to 

 sanitary science, with special reference to recent ad- 

 vances in hygiene and municipal engineering. In the 

 lectures under review, Mr. \V. D. Scott-Moncrieff 

 deals with the subject of sewerage and sewage dis- 

 l)osal in four lectures. At the outset he deals with 

 facts which are mainly historical, tracing the evolu- 

 tion of our present methods, and summarising the 

 Acts of Parliament and the reports of Royal and 

 other Commissions relating to sewage disposal. He 

 then proceeds to a critical survey of the various pro- 

 visions which have been made, from time to time 

 and in different places, for purifying sewage. 



The lectures will serve exceedingly well to indicate 

 the lines upon which we are now advancing towards 

 the solution of the sewage problem, and the lecturer 

 is to be congratulated upon having made an interest- 

 ing, instructive, and suggestive contribution to the 

 subject of sewage disposal. He strongly emphasises 

 the waste of manurial values involved in modern 

 methods and the economy of ascertaining bv direct 

 experiment the conditions necessarv to success, in 

 every specific instance, before spending money in igr 

 norance of what these conditions really are. .As one 

 of the pioneers among British workers upon the bio- 

 logical purification of sewage, he remains a strong 

 advocate of that method. 



NO. 2066, VOL. 80] 



.After reviewing the enormous amount of study and 

 experiment which chemists, biologists, and engineers 

 have for many years devoted to the subject of sewage 

 purification, the reader will find food for contempla- 

 tion in the circumstance that the trend of modern 

 scientific opinion is in favour of the methods of 

 " mother earth." Biological agencies, " the scaven- 

 gers of nature," are now generally considered to 

 afl^ord at once the most economical and effectual 

 means of sewage purification. The natural dis- 

 posal of faeces upon earth had always proved satis- 

 factory so long as the soil was suitable in nature and 

 amount, but with the growth of our towns and the 

 introduction of the water-carriage svstcm a new set 

 of circumstances had to be faced. Large volumes of 

 water polluted with faecal matter had to be deal' 

 with; and the disposal of this, without causing a 

 nuisance or contaminating drinking-water supplies, 

 became the problem which is even now but partlv 

 solved. Mr. Scott-Moncrieff shares the verv general 

 view that it is by methods in which " nature's scaven- 

 gers " are placed under the best conditions for their 

 work that we are likely to obtain the best all-round 

 results. 



LETTERS TO THE EDITOR. 

 [The Ediloi does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can lie undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part 0/ Nature. 

 No notice is taken of ationyinous communications.] 



The Temperature of the Upper Atmosphere. 



Since my last letter on the above subject the columns of 

 Nature have contained some interesting data from Mr. 

 E. Gold, and an account of the meeting at Monaco on 

 .April I of the International Commission for Scientific 

 .Aeronautics. The proceedings of the commission seem to 

 have included the enunciation of a creed in which the 

 members expressed their individual belief in the existence 

 of an "isothermal layer" ialiter "stratosphere"). This 

 promulgation was apparently intended mainly for the 

 benefit of heretics in England. .As is not unusual with 

 creeds, an exact definition of the essential term strato- 

 sphere does not seem to have been supplied, and I am 

 thus in doubt whether I am or am not one of the elect. 

 The term " stratosphere " can hardly have been employed 

 in its very strictest sense, which would seem to imply 

 that at any given instant of time temperature is a function 

 only of the distance above the ground. This obviously 

 could not be true at altitudes where either a diurnal or an 

 annual variation was sensible, and I doubt whether 

 members of the commission are yet prepared to deny the 

 existence of these variations at the heights with which 

 they are concerned. In the' recent German balloon ascents 

 in Central .Africa temperatures were recorded which differ 

 somewhat notably from those met with at corresponding 

 heights in Europe, while in the polar regions tempera- 

 tures are sometimes recorded at ground-levels which are 

 lower than those usually encountered in balloon ascents 

 here. 



The term stratosphere is thus presumably intended 

 merely to indicate in a general way that at high levels the 

 rale of change of temperature in any horizontal direction 

 'is normally very small. In this sense I too am rather 

 disposed to be a stratospherist. What has been objected 

 to by myself, and I believe I speak for others in this 

 country, is the application of the term " isothermal layer " 

 to the whole of the upper atmosphere — so far as yet 

 explored by kites and balloons — which exists above the 

 level where fall of temperature with increase of height 

 ceases {cf. Mr. W. H. Dines, Nature, February 27, 1908, 

 p. 390). I see no objection to the application of the term 

 to a layer of finite thickness, if such exists, throughout 

 which rate of change of temperature with height is 

 vanishingly small. If ( and h denote temperature and 

 height, then, according to most Continental balloon 



