February 9, 1922] 



NATURE 



71 



pounds has led to an excessive importance being 

 attached to valency phenomena in homopolar com- 

 pounds, whereas a complete theory should cover 

 the very large class of inorganic heteropolar com- 

 pounds formed by the majority of the elements. 

 The second essay is a short review of the work 

 which has been done on X-ray spectra and the 

 origin of X-rays, with particular reference to the 

 partitioning of electrons into shells surrounding 

 the nucleus. 



The author's style is somewhat involved, and for 

 : cader who is not a good German scholar the 

 aii^ument is sometimes difficult to follow. 



Our Bookshelf. 



(,1) Abridged Callendar Steam Tables, Centigrade 



Units. By Prof. H. L. Callendar. Pp. viii. 



i^. net. 

 Abridged Callendar Steam Tables, Fahrenheit 



Units. By Prof. H. L. Callendar. Pp. 8. 



\s. net. 

 ;i Callendar Steam Diagram, Centigrade Units. 



bd. net. 

 , ;) Callendar Steam Diagram, Fahrenheit Units. 



bd. net. (London : E. Arnold, n.d.) 

 The two sets of abridged tables (i) and (2) will 

 be found to contain all that is required for engi- 

 neering calculations. Table i in each set contains 

 the properties of saturated steam for pressures rang- 

 ing from 28-98 in. of vacuum up to 535-31 lb. per 

 sq. in. gauge pressure. Table 2 gives the total 

 heat of dry steam (superheated or supersaturated), 

 and table 3 contains the entropy values for dry steam 

 at various degrees of superheat and supersaturation. 

 On the first and last pages will be found notes of 

 the symbols and equations employed. The tables 

 are well arranged and clearly printed, and will be 

 of great service to students and engineers in practice. 



(3) The Centigrade steam diagram is also well 

 arranged and has convenient scales. (4) The curves 

 on the Fahrenheit steam diagram are copied from 

 those on the Centigrade diagram ; the numerals 

 printed on them are the corresponding Fahrenheit 

 numbers. Hence the scales on the Fahrenheit dia- 

 gram are not so convenient, and we think it would 

 have been better had this diagram been drawn inde- 

 pendently of the Centigrade diagram. 



Sfot and Arc Welding. By H. A. Hornor. 

 (Griffin's Technological Handbooks.) Pp. vii -|- 

 296. (London: Charles Griffin and Co., Ltd., 

 1920.) 155. 



The application of electric welding processes to 

 heavy steel construction, such as obtains in ship- 

 building, forms the main topic of this book. The 

 results of extensive tests conducted during the war 

 in the United States with the object of testing the 

 processes are also given. This work was, unfor- 

 tunately, discontinued at the time of the armistice, 

 but from the results it was shown that trustworthy 

 NO. 2728, VOL. 109] 



electrically welded joints can be made of greater 

 strength than corresponding riveted joints, and that 

 consequently some economy in mateiial can be ex- 

 pected. Special designs for all-welded ships are 

 discussed, and a good deal of interesting informa- 

 tion is given on other applications of both spot and 

 arc welding and the training of welders. Small all- 

 welded craft have already been constructed in 

 England, and the author shows that the technical 

 knowledge now available is sufficient for a consider- 

 able extension of this method of ship construction. 



Handbuch der biologischen Arbeitsmethoden. 

 Edited by Prof. Dr. Emil Abderhalden. 

 Abt. 5, Method en zum Studium der Funktionen 

 der einzelnen Organe des iierischen Organismus. 

 Teil 7, Heft i, Lieferung 12, Sinnesorgane. 

 Pp. 195. (Berlin und Wien : Urban und 

 Schwarzenberg, 1920.) 30 marks. 



The " Handbuch der biologischen Arbeits- 

 methoden," edited by Prof. Emil Abderhalden, 

 will consist of forty-eight parts, in which chemical, 

 physical, biological, psychological, and many other 

 methods are treated at considerable length. The 

 section under notice, by E. Budde, is devoted to 

 the mathematical theory of audition. The first 

 division of this contains a very full discussion of 

 free and forced small vibrations of a point, fol- 

 lowed by systems under non-linear forces, includ- 

 ing combination tones. The second division deals 

 with strings and membranes, while the third refers 

 to plane-waves in air. Having thus laid the 

 foundation, the author passes to the detailed treat- 

 ment of human audition, in which he reviews the 

 interpretations of the phenomena put forward by 

 the chief workers on the subject, but dwells espe- 

 cially on the parts played by the basilar membrane 

 and the endolymph. 



Turbines. By A. E. Tompkins. Third edition, 

 entirely revised. Pp. viii -f- 180. (London: 

 S.P.C.K. ; New York: The Macmillan Co., 

 1921.) 85. net. 



The early part of this book is taken up with his- 

 torical notes and some explanations of the principles 

 involved in the working of turbines. This is fol- 

 lowed by three chapters on water-wheels, turbine 

 pumps, and water turbines. The remainder of the 

 book deals with steam turbines. For the most part 

 the book is descriptive, and the simple language 

 employed, together with the many excellent draw- 

 ings, will render the volume of interest to the 

 general reader. The author has had considerable 

 experience in the working of turbines, and his 

 treatise on "Marine Engineering" is well known. 

 It is therefore rather surprising to find on p. 21, in 

 reference to a rotating wheel, that "every particle 

 of the wheel also tends to fly away from the axis in 

 a radial direction, due to centrifugal action or 

 force." This statement is somewhat misleading. 

 There are one or two misprints, and the accepted 

 notation for British thermal unit is B.Th.U., not 

 b.t.u. 



