462 



NATURE 



[September 29, 1923 



More Applications of Physics. 



A Dictionary of Applied Physics. Edited by Sir 

 Richard Glazchrook. In 5 vols. Vol. 5 : Aero- 

 nautics — Metallurgy — General Index. Pp. vii + 592. 

 (London : Macmillan and Co., Ltd., 1923.) 635. net. 



THE fifth and final volume of the " I)ictionar>' of 

 Applied Physics," now well known and justly 

 famous, edited by Sir Richard Glazebrook, deals with 

 two of the youngest physical sciences, aeronautics and 

 metallography. The former occupies about two-fifths, 

 and the latter the remainder of the book. The same 

 plan is adopted as in previous volumes, i.e. there is a 

 limited number of articles dealing with important 

 aspects of the two sciences, written by men of high 

 standing and authority in their subjects. Interspersed 

 between these is a series of headings in alphabetical 

 sequence, containing references to the articles in ques- 

 tion. It is natural that many of the articles should have 

 been contributed by present and former members of the 

 staff of the National Physical Laboratory, Teddington. 

 Whether, however, it was wise to make the proportion 

 so high as it is in the metallurgical section of the 

 volume may be questioned. A dictionary of this 

 kind should represent as wide a range of authoritative 

 opinion as it is possible to secure, and we think that 

 the editor would have been well advised to draw, more 

 than he has done, on the knowledge of metallographers 

 occupying positions in the metallurgical industries. 



The section on aeronautics opens with a valuable 

 article on full-scale aerodynamic research by Mr. 

 M'Kinnon Wood. The subject of experimental tests 

 of the strength of aeroplane, structures is dealt with 

 lucidly by Mr. William Douglas, while various aspects 

 of the theory of aeroplane structures are compre- 

 hensively treated by Mr. Cowley. Two articles by 

 Mr. Guy Barr on aeroplane wings follow, one dealing 

 with dopes, the other with fabrics. Mr. Barr also 

 contributes a lengthy and interesting article on diffusion 

 through membranes. The article on instruments used 

 in air-craft, by Mr. Dobson, deals with many novelties. 

 Prof. Bairstow contributes two articles, written with 

 great authority, on the performance of air-craft and 

 the stability of air-craft. A general outline of the 

 theory of the air-screw is given by Mr. Arthur Fage, 

 who also deals with the helicopter. This article may 

 be studied in conjunction with that recently written 

 by Prof. Bairstow in Nature (August 18), entitled 

 " The Helicopter : is it worth a prize ? " The problem 

 of the helicopter is that of an aerial machine " supported 

 in the air by the thrust of one or more air-screws 

 rotating about the vertical." As the author points 

 out, many of these have been constructed, but only a 

 few have supported their weight in the air, and none 

 NO. 2813, VOL. 112] 



has been successful when judged from the point of 

 view of practical utility. Experiments on air" 

 constitute the subject-matter of an imjwrtant ar 

 by the late Mr. J. R. Pannell and Mr. R. Jont 



The " engine " side of aviation is dealt with l>y thi 

 late G. H. Norman, Sqd.-Leader, R.A.F., in an anicli- 

 entitled " Air-cooled Engines for Air-craft." This 

 contains valuable data on the comparative perform- 

 ances of air-cooled and water-cooled engines. At the 

 present date the majority of engines are water-cooled, 

 but the author evidently considers that there is likely 

 to be a considerable increase in the use of air-cooled 

 engines in the future. The saving in weight due to 

 air-cooling may not be ven' great, and may in some 

 cases be counter-balanced by increased head resistance. 

 Its great advantage lies in the lower capital and 

 attendance costs and the simplicity of the engine 

 installation. Prof. J. C. McLennan contributes a short 

 article on the production and use of helium. He 

 estimates that from Empire sources, not more than 

 about 12,000,000 cubic feet per annum can be obtained, 

 the estimated cost being " not excessive." This, as 

 he points out, would only keep a ver>' few of the large 

 air-ships in commission, even if diluted with 15 per cent. 

 of hydrogen. The best method of extraction hitherto 

 discovered consists in producing the refrigeration 

 necessary to liquefy all the gases, except helium, by 

 the cold obtained from the natural gas itself. 



The subject of " Model Experiments in Aeronautics, 

 their Theory and Methods," is dealt with compre- 

 hensively by Messrs. E. F. Relf and H. B. Irving, and 

 the section closes with an article on " The Hydro- 

 dynamical Theor>' of Wing Surfaces." H. 

 Glauert. 



Part II. of the volume is entitled " Metallurgy'," but 

 almost the whole of the subject-matter relates to what 

 is usually called " Metallography." Dr. Haughton 

 contributes excellent articles dealing with tN-pical alloy 

 systems, the construction of equilibrium diagrams, and 

 the relationship between structure and physical con- 

 stants. It is a pity that the constitutional diagram 

 of the aluminium zinc alloys, on page 229, has been 

 reproduced, since it is inaccurate in certain respects, 

 and the correct diagram was published more than a 

 year ago. This might well have been used and would 

 have rendered unnecessar\- the footnote on page 230. 

 Dr. Haughton has drawn his diagrams with the hori 

 zontal ordinates indicating weight percentages. It is 

 not clear why he has preferred this arrangement. Thi 

 system of plotting atomic percentages on the horizontal 

 ordinates has many advantages. The diagram of the 

 iron nickel system reproduced on page 235 is incom- 

 plete in the upper range of temperature where the 6 

 to 7 inversion of iron takes place. The only metal the 



