i64 SCIENCE PROGRESS 



measurements. As regards the measuring apparatus described, it is perhaps 

 a pity that so little attention is given to the triode valve in this connection. 

 The description of these valves is left to the last chapter of the book, and 

 there their many applications in the laboratory and test-room are barely 

 touched upon. 



From the point of view of the practical engineer. Chapter XII is perhaps 

 the most important one in the whole book, as there the effect of " cost 

 problems " upon the construction of telephone lines is treated extensively. 

 Apart from its other good points, this chapter alone would make the book 

 valuable. 



The development of a satisfactory telephone repeater has long taxed the 

 ingenuity of telephone engineers, and the modern development of the triode 

 valve bids fair to provide a satisfactory solution. This aspect of the subject 

 of telephonic transmission is dealt with in the last chapter, but here the 

 author seems to be treading on less familiar ground. For instance, the 

 statement at the foot of p. 345 would rather imply that any negative voltage 

 greater than three or four volts could be used on the grid of a triode amplifier 

 for telephone work. With a large negative voltage, however, it would seem 

 that the repeater could scarcely be distorionless. It would also be interesting 

 to know the author's authority for the statement on p. 356, that the " ther- 

 mionic relay does not transmit such low frequency signals [17 periods per 

 second]." It is usually understood that a triode will amplify currents of 

 any frequency from zero upwards. 



The diagrams throughout the book are clear, and a number of useful 

 half-tone plates are also included, while the general appearance of the book 

 is good, although the formulae would look better if they had been printed 

 throughout in a uniform fount of type. The volume is the first of a series 

 of similar handbooks which are in course of preparation, and if the whole 

 of the series maintains the standard set by this one, it will indeed be a 

 valuable one. 



Philip R. Coursey. 



The Foundations of Music. By H. J. Watt, D.Phil. [Pp. xvi-f- 239, with 

 10 illustrations.] (Cambridge : at the University Press, 19 19. Price 

 i8s. net.) 



In this book the author's treatment is fullest when dealing with concords. 

 Thus, octaves, fifths, consecutive fifths and their prohibition, common 

 chords, etc., occupy over half the entire work. 



In discussing any controversial matters the various authorities on the 

 subject, ancient and modern, from Aristotle to Tschaikovsky, are carefully 

 cited. Although no entire solution is propounded for some of the age-long 

 problems here surveyed, the facts of the case are marshalled with care and 

 fullness and accordingly a noteworthy step is taken towards grappling with 

 their difficulties. 



Near the beginning of the book occurs a somewhat striking feature. 

 This is what the author terms his " volumic " theory of tone. Thus we 

 find the following passages. 



P. 6 : " Volume is properly used to distinguish that difference between 

 tones of different pitch that makes the low tone great, massive, all-per- 

 vasive, and the high tone small, thin, and light." 



P. 8 : " The attributes of tones thus far enumerated are : quality, 

 intensity, volume and pitch. The relations between these four are an im- 

 portant problem." 



P. 9 : " We may assume that pitch holds a central position in volume. 

 And, as pitch is ordinal, while volume suggests a volume of parts or 

 particles, we may go on to assume that pitch is constituted by a specially 



