148 SCIENCE PROGRESS 



This edition of Watson's well-known text-book shows signs of a good 

 deal of revision by its new editor, Mr. H. Moss, Lecturer in Physics at the 

 Imperial College of Science, London. It has been his aim to " ensure that 

 the standard of all parts of the book should be at least equal to that of the 

 pass degree of any university." This aim has been achieved in so far that 

 it is probable that anyone having a thorough knowledge of the whole of the 

 book would succeed in scraping through his degree examination ; but he 

 certainly would not have any idea even of the existence of many pheno- 

 mena with which a university teacher would consider it essential that his 

 pass students should have at least a nodding acquaintance. Further, he 

 would be seriously disturbed by many of the questions which are to be 

 expected in, say, the pass papers in the London B.Sc. The editor can verify 

 this by looking up some of these papers and then referring to his treatment 

 of viscosity and radiation pressure, to take two examples at random. It 

 is, of course, obvious that to revise and add to a book of this type, 

 standard, and dimensions is an enormous task only to be completed slowly 

 edition by edition ; nevertheless, there are certain points which might have 

 received attention. We find, for example, that the old definition of the 

 coefficient of thermal conductivity is still retained, although it contains a 

 really inexcusable misstatement of fact ; the definition of entropy is equally 

 misleading, and the curves showing the variation of the resistance of metals 

 with temperature are still shown as straight lines passing through the abso- 

 lute zero of temperature with no indication of the results obtained by 

 Kamerhngh Onnes at very low temperature. A book published in 1920 and 

 intended for pass students should contain a brief mention of work of this 

 character. These things apart, the book remains a magnificent and enduring 

 monument to the ability of its original author. When we express a desire 

 for improvement we also express our conviction that it will continue in 

 demand and growth. Finally, it may be pointed out that Messrs. Long- 

 mans would do well to overhaul the original blocks and the original type 

 in the next edition. 



D. O. W. 



Physical and Chemical Constants. By G. W. C. Kaye. O.B.E., M.A., D.Sc, 

 and Prof. T. H. Laby, M.A. [Pp. viii + 161. Fourth Edition.] 

 (London : Longmans, Green & Co., 192 1, Price 14s. net.) 



There is no need, in a review of the fourth edition of these tables, to praise 

 them ; they have been long since tried and trusted friends in every physical and 

 chemical laboratory. It is, however, fitting that we should express our grati- 

 tude to the authors for the trouble they took in the original compilation and 

 that they are taking in keeping it up to date. The principal changes appear 

 in the sections relating to terrestrial constants — gravitational and magnetic 

 —in Heat and in Electricity. Further, it is stated that some 700 additions 

 and alterations have been made in the physical constants of chemical com- 

 pounds. The recent work on X-ray spectra has necessitated the addition 

 of three pages of the wave-lengths of the hnes of the K, L, and M series 

 spectra of the elements, while two more pages contain most useful tables of 

 spark-gap voltages for sparks between needle-points and spheres of various 

 sizes. The spark-gap method for measuring large potential differences now 

 being standard for voltages above 70 kilo volts. The changes in the table 

 of Atomic and Radioactive constants since the first edition was published 

 in 191 1 are remarkably few, the charge associated with the electron becomes 

 1*59 X 10-20 coulombs instead of i'57 X 10-20^ the mass x^V of the mass 

 of the hydrogen atom instead of tAtt- Avogadro's constant 2705 x 10 - ^9 

 molecules per c.c. instead of 2-75 and the number of coulombs carried by 



