74 Scientific Intelligence. 



is not feasible m the case of ordinary light because of the 

 extremely short wave-lengths of visible radiations. 



A few facts about the apparatus merit attention. The linear 

 oscillator consisted in a spark gap 046 mm. long. The sparks 

 passed in a stream of hydrogen gas which was saturated with 

 alcohol vapor. The resonator was provided with a detector of 

 new form, the details of which are partially withheld because of 

 certain patent rights. Its success, however, seems to depend 

 primarily upon the use of a crystal of molybdenum-glance. The 

 waves emitted by the oscillator had a length of 40 cms. and a 

 logarithmic decrement of about 0-6. The vibrations of the reso- 

 nator were strongly damped (1*2). Both the oscillator and the 

 resonator were kept at a distance of five wave-lengths (200 cms.) 

 above the floor. The screen consisted of a zinc sheet 0-4 mm. 

 thick, the other dimensions being 290 and 300 cms. The dif- 

 fracting edge was vertical so that all explorations were made in 

 the equatorial plane of the vertical oscillator. 



After applying small corrections, necessitated by the presence 

 of slight unavoidable disturbing influences, the intensities 

 obtained experimentally agreed with the values calculated from 

 Oseen's analysis, well within the limits of observational error. 

 The monograph closes with a two-page chart of the loci of con- 

 stant intensity. This map is very instructive since its contour 

 lines bring out the intensity hills and valleys very strikingly, and 

 as it illustrates the parallel case in optics. The investigation 

 brought to light a new phenomenon which is consistent with 

 Oseen 's theory so far as the calculations have as yet been carried. 

 It is this, the intensity of the diffraction field as obtained with 

 Hertzian waves fluctuates within the geometrical shadow of the 

 screen instead of falling off gradually and smoothly as it does in 

 the case of ordinary light. The existence of this phenomenon was 

 carefully verified and especial pains were taken by the author to 

 prove that the result is not spurious. H. s. u. 



6. On the Mechanical Theory of the Titrations of Bowed 

 Strimgs and of Musical Instruments of the Violin Family, with 

 Experimental Verification of the Results: Part I; by C. V. 

 Raman. Pp. iii, 158 ; 28 figures and 26 plates. Calcutta, 1918 

 (Bulletin No. 15. The Indian Association for the Cultivation 

 of Science). — This monograph (which does not include all of 

 Part I) is a very valuable contribution to the subject because 

 purely empirical results have been eliminated by giving full 

 mathematical explanations of all of the phenomena, from the 

 simplest to the most complex, produced experimentally. ''Not 

 only does the theory succeed in explaining all the known phe- 

 nomena but it has also justified itself by predicting many new 

 relations and results which have been tested experimentally." 



It is not possible to give an adequate idea of the scope of the 

 investigation in a brief notice. Attention should be called, how- 



