140 Notices respecting New Books. 



thus removing the mouthpiece to a distance from the ear. The 

 former can be obviated to some extent by having an inelastic 

 mouthpiece or similar covering to the end of the tube. But 

 Mr. Woodward's device of putting a source of sound, such as a 

 reed, entirely within the tube, and a trumpet mouthpiece at N, 

 is undoubtedly the best and most suitable class method of making 

 the experiment. 



P.S. — With an ordinary pitch-pipe inserted atN, I have to-day 

 (July 25) repeated the experiment to the class of science teachers 

 now at South Kensington. A continuous blast of air was driven 

 through the pipe from an acoustic bellows ; and the loud note 

 heard at first was utterly extinguished by altering the relative 

 lengths of the tubes. By pushing the tube still further round 

 the note again came out; thus the sound of the pitch-pipe could 

 be turned on and off at pleasure. Extinction is not confined to a 

 mere line in adjusting the pipe, but spreads over a short and 

 definite range. In this case it is probably, as Professor Goodevc 

 suggests, the interference of two resonant columns of air, rather 

 than the coalescence of two progressive waves in opposite phases. 



XXIII. Notices respecting New Books. 



Statique Experimentale et Theorique des Liqiddes soumis aux seides 

 Forces MoUculalres. Par J. Plateau. 2 vols. 8vo, pp. 450 & 

 495. Ghent and Leipzig : P. Clemm. London: Triibner&Co. 

 1873. 

 rPHIS work consists essentially of the collected series of papers 

 -*- "On the Figures of Equilibrium of a Liquid Mass without 

 Weight," which the distinguished physicist of Grhent has published 

 in the ' Memoirs of the Belgian Academy of Sciences ' during the 

 years 1843 to 1868. The substance of these papers having appeared 

 from time to time in the pages of the ' Philosophical Magazine/ in 

 the form of comparatively full abstracts of the original memoirs, it 

 is not needful to say much here by way of introducing or recom- 

 mending the work to our readers. It should be observed, however, 

 that this book is not merely a republication, offering simply the 

 convenience of presenting in a collected form results which were 

 previously accessible only in a number of separate papers published 

 at intervals during a period of twenty-five years ; thanks to the 

 careful revision which the whole has received, and to numerous ad- 

 ditions (some of them of considerable extent, relating chiefly to the 

 work of other investigators in the same field of research), the work 

 before us possesses much of the continuity and completeness of a 

 systematic treatise. 



The chief scientific interest of the phenomena which Professor 

 Plateau has investigated lies in the simplicity of the physical prin- 

 ciple to which they are all of them referrible, and in the compre- 



