554 



SCIENCE 



[N. S. Vol. XXXVIII. No. 981 



its energy, and that it did not matter how it 

 did it, whether by viscosity or hysteresis or 

 heat conduction or reflection or vortex mo- 

 tion. (I omit divergency because the only 

 functions I can find connected with divergency 

 which would prevent discontinuity either van- 

 ish at a short distance from the source, or 

 only exist at the lateral edges of the wave, and 

 hence do not affect spherical waves.) 



Now in a fluid like the ether, viscosity, 

 hysteresis and heat conduction losses can not 

 occur. Nor, if my work is correct, can reflec- 

 tion occur without vortex motion, and then 

 not necessarily. 



But the vortex motion is a necessity, in a 

 fluid like the ether, whenever a spherical wave 

 reaches a certain distance from its source. 

 And gravitational waves must therefore give 

 rise to vortices in the ether. 



And the satisfactory point about these vor- 

 tices is that they are exactly similar, irrespec- 

 tive of the intensity of the gravitational wave, 

 and dependent only upon the elasticity and 

 density of the medium. This therefore relieves 

 us of the necessity of assuming a single vor- 

 tex fllament. 



There are some points still to be cleared up. 

 For example, one might anticipate that the ro- 

 tational velocity of the vortices would be the 

 same as the translational velocity of the wave, 

 but there appear to be at least one, and pos- 

 sibly two, other types, with rotational veloci- 

 ties of the square and cube root of the wave 

 velocity; also in some respects the motion of 

 what I have called the oscilla appear to differ 

 from that of our standard vortex filament. All 

 this is at present rather hard to interpret, but 

 doubtless, as the difficulties of the analysis are 

 gradually overcome, we shall be able to visual- 

 ize the system more clearly. 



As the work is still under way, the above re- 

 sults would not have been published but for 

 the fact that it appears to have been generally 

 assumed at the last British Association meet- 

 ing that Planck's " quanta " theory and Max- 

 well's continuous medium theory are mutually 

 exclusive and that one or the other must be 

 given up. Now the results referred to above 

 show that this is not so, but that every con- 



tinuous medium theory must involve quanta, 

 and we might almost say that a continuous 

 medium begins to count as soon as it gets its 

 legs. A unit quantity is, therefore, just as 

 natural a thing as a flux; and in this connec- 

 tion it is interesting to note how, from Newton 

 and Leibnitz down to Maxwell and Planck the 

 English mind runs always to continuities and 

 fluxes and the German to quanta and infini- 

 tesimals. 



It may also be pointed out that quanta are 

 a necessary consequence of motion due to cen- 

 tral attraction. One visible example of this is 

 the gaps in Saturn's rings. These are due to 

 satellite resonance, but I have found that 

 nucleus resonance gives quanta,^ whether the 

 resonant nucleus be the sun or the positive 

 electron. The latter case is much the simpler, 

 as all the corpuscles are the same size and so 

 what we may call the " quanta orbits " are 

 simpler. 



From the above it will be seen that the 

 problem of the transmission of plane waves in 

 a frictionless fluid is not, as has been generally 

 assumed, a matter of no practical importance 

 and of interest to pure mathematicians only. 

 But that it is a matter of very great practical 

 importance, and that the complete solution of 

 the problem is of capital importance in many 

 fields, from the design of aeroplanes and the 

 calculation of frictional resistance of ships to 

 the theory of the constitution of the ether and 

 the structure of the positive charge. 



Reginald A. Fessenden 



THE SPECIFIC GRAVITY OF SILT^ 



In a report recently published by the De- 

 partment of State, entitled " Silt in the Eio 

 Grande," certain fundamental ideas are pro- 

 mulgated, concerning the specific gravity of 

 silt which seemed to the writer incorrect, and 

 of sufficient importance to be worthy of a 

 brief note in Science. 



The author, W. W. Follett, consulting engi- 

 neer of the International Boundary Commis- 



8 See also some of Darwin's papers. 



1 Published by permission of Director of the 

 United States Geological Survey, Washington, 

 D. C. 



