942 Sir Oliver Lodge on 



that experiment the times of a to-and-fro journey are com- 

 pared, when # = and when = 90°; and, as everyone now 

 knows, the null result of that experiment, combined with 

 my experiment establishing the absence of convective or 

 viscous etherial drift ('Nature,' vol. xlvi. pp. 165 and 501, 

 or Phil. Trans, 1893 and 1897), necessitated some novel 

 explanation, and led to the FitzGerald-Lorentz contraction. 



(Parenthetically I take this opportunity of correcting- a rather con- 

 fusing misprint or slip in the summary of my historical suryey 

 communicated to the Physical Society in May 1892, which appears 

 on page 165 of ' Nature,' vol. xlvi. Of the two terms in the expression 

 for T', above the middle of the first column, the drift angle should 

 appear only in the second term, while in the first term the angle should 

 be the much smaller aberration angle e, which is essentially of the second 

 order in v/V.) 



Hence a flow of ether need not be objected to on the 

 ground of a perceptible disturbance to rays of light ; but 

 instinctively one feels that a Le Sage-like hypothesis con- 

 cerning gravity is not likely to be on right lines. There 

 must admittedly be a stress in the ether between two 

 particles of" matter, but it should be a static rather than a 

 kinetic stress, and should not be accompanied by locomotion. 

 Locomotion of the ether is objectionable for a variety of 

 reasons : the only motion permissible in a universal medium 

 of infinite extent is a circulatory or vortex motion, such as 

 might occur along lines of magnetic force. Magnetic lines 

 are always closed curves; there is no known way of gene- 

 rating them ; they always pre-exist, though thev may be 

 of atomic or molecular magnitude, and in a magnetic field 

 are opened out so as to enclose a perceptible area. This is 

 generally admitted to be the process of magnetisation ; and 

 when the magnetism ceases the lines shrink up into infini- 

 tesimal, or practically infinitesimal, orbits again. That the 

 quantum is associated with these ultimate magnetic units is 

 exceedingly likely (cf. Dr. 11. Stanley Allen, Proc. R. S. 

 Edin. November 1920); and an association of electric units 

 with the magnetic ones is all that is necessary to account 

 for radiation. 



In the Phil. Mag. for April 1921, I ventured on a specu- 

 lation that matter is a sink as well as a source of radiation — 

 a sink not of ether but of the radiation movement of ether. 

 Annulling of the electric component in an ether wave, 

 though the process commonly generates heat, may also 

 under some conditions liberate the magnetic component, 

 which, at a distance of X/7ry2 from a resonating particle, 

 is left behind by the electric component. By analogy it 



