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XCIII. An Experiment indicating that Matter takes up na 

 Room in the JEther. By C. V. Burton, IJ.Sc* 



1. IN a former paper t it was suggested as a possibility 

 A that electrically neutral bodies moving through the 

 aether might exert forces on one another in virtue of their 

 motion; and it was shown that such effects were to be 

 expected unless a certain simple condition were fulfilled. 

 Briefly expressed, the condition is that matter should take 

 up no room in the sether, a form of statement which 

 perhaps needs further explanation. When surrounded by 

 the atmosphere, a body impermeable to air is commonly said 

 to displace its own volume of air : the room which the 

 body occupies in the air is positive, and its measure is the 

 volume of the body. Similarly, in complete accordance with 

 the common use of terms, we may say that, in an atmosphere 

 traversed by sound-waves, the rarefactions take up positive 

 and the condensations negative room, the disturbance as a 

 whole taking up no room. Regarding matter and aether, the 

 question may be proposed whether the mean setherial density 

 is less (greater) in a region where matter is present than in a 

 vacuum, the room which matter takes up in the sether being 

 in that case positive (negative); or whether the presence of 

 matter produces on the whole no modification of aetherial 

 density, so that matter takes up no room whatever in the 

 aather. When it is stated that, within the limits of accidental 

 error, the latter conclusion is supported by the experiment to 

 be described, this is not to be taken as implying that electrons 

 and atomic nuclei are of vanishingly small dimensions, but 

 rather that the modifications of setherial conditions which 

 constitute these entities are not such as involve, on the whole, 

 any appreciable change of density. 



2. The nature of the experiment will be most readily 

 understood in relation to the effects which should have been 

 observed if these had been appreciable. In ordinary hydro- 

 dynamics (discontinuities apart) a solid body moving through 

 an unbounded liquid produces at remote points the effect of a 

 doublet; the direction and strength of the equivalent doublet 

 depending not merely on the volume and motion of the body, 

 but on its shape and orientation. The case which we have 

 to consider is somewhat analogous but essentially simpler. 

 Thus " let F be a physical magnitude characteristic of all 

 electrically neutral matter and defined as follows : If into a 



* Communicated by the Author, 

 t Phil. Mag. Jan. 1909. 



