230 Scientific Intelligence. 



block. By increasing the gaseous pressure within the box the 

 diaphragm may be made to bulge slightly outwards and contrari- 

 wise by exhausting the gas the diaphragm is deflected inward. 

 The tension of the thin annular part is accordingly increased or 

 diminished and consequently the frequency of the central portion 

 of the diaphragm is raised or lowered. Thus by the variation of 

 the gas pressure within the box the fundamental pitch of the 

 diaphragm may be changed continuously between certain limits. 

 To adapt it to the reception of signals from a submarine sound 

 generator a simple microphone receiver with the usual battery 

 and head-telephone is attached to the underside of the diaphragm. 



In an experimental test of a three-inch diaphragm of this design 

 it was found that a variation of the pressure by 2 mm. of mer- 

 cury produced a noticeable change of audibility at the resonance 

 frequency. The variation of this frequency with the applied pres- 

 sure below the diaphragm was determined both under water and 

 in air, and was found to be a nearly linear relation, the absolute 

 values of the frequency of course being less in the former case. 

 The range of frequencies under water obtained was from 330 to 

 545 vibrations when the pressure was changed from — 30 cm to 

 + 30 cm. A variation of pressure from + 10 cm to — 30 cm, 

 which is easily furnished by the lungs alone, permits the dia- 

 phragm to be tuned from 320 to 480 vibrations. 



The mathematical constants of the diaphragm and the damping 

 factors are discussed at length as an aid to the design of particu- 

 lar receivers. — Froc. Boy. Soc. 99, 163, 1921. f. e. b. 



7. Fhilosophy and the New Physics; by Louis Rougier. Pp. 

 XV, 159. Philadelphia, 1921 (P. Blakiston's Son & Co.).— The 

 recent development of physical theories has furnished a new grist 

 for the technical philosophers, of which product the present work 

 is an example. It is a re-writing of the work of physicists and 

 was origially published uder the title of La Materialisation de 

 VEnergie. The author's thesis is that with the ascription 

 momentum to radiant energy, and its deflection in a gravi- 

 tational field, the conception of matter can be dispensed 

 with. In the eight chapters of the book he passes in review the 

 various speculations which have been made as to the dualism or 

 unity of matter and energy ; the electron theory ; the inertia and 

 weight of energy according to the relativity theory ; and the 

 structure of energy as suggested by the quantum theory. 



Unfortunately the author does not seem to be familiar with 

 recent radiation theory and the structure of the atom which pre- 

 sents the quantum in a much more plausible light. He is appar- 

 ently of that iconoclastic temperament which is sure the old is 

 wrong and that the new must be right. To another it would seem 

 that he is not sufficiently critical of his own exposition to see that 

 the new speculation introduces difficulties just as troublesome as 



