456 Sir Oliver J. Lodge [Feb. 28, 



diminution of this force due to lateral motion is inevitable. And the 

 resulting lateral expansion or longitudinal contraction, or both, is of 

 the right order of magnitude. So this acts as a previously quite 

 unsuspected compensating effect, which exactly neutralises the drift 

 effect otherwise to be anticipated. Thus, by superposition of two 

 positive consequences of drift, the Michelson experiment, like every 

 other yet made, declines to indicate that there is any drift at all. 



Hence, after many such negative results, it seems to become 

 hopeless to enquire experimentally as to our motion through ether. 

 Unless indeed gravitation were exempt from the otherwise universal 

 compensation. In that case the electrical theory of matter applied to 

 the motion of planets might jield a residual result. But my recent 

 enquiry into this problem has suggested that gravitation too is in 

 the conspiracy, ■"• and in that case there is some ground for the con- 

 tention of the extreme Relativists, not only that we do not know our 

 motion — with which everyone agrees — but that we never shall know 

 it : and, in fact, that motion of matter through ether is a phrase 

 without meaning. 



I hope we shall not too readily shut the door on further attempts 

 in this direction ; and as a conservative physicist I may be allowed 

 to lament the extraordinary complexity introduced into physics 

 and into natural philosophy by the principle of relativity, as so 

 remarkably and powerfully developed by the mathematical genius 

 of Einstein, with complication even of our fundamental ideas of 

 space and time. The complications do not commend themselves to 

 all of us, and I for one should be glad to return to the pristine 

 simplicity of Newtonian dynamics, modified of course by the electrical 

 theory of matter ; admitting the FitzGerald-Lorentz contraction, and 

 admitting also the variation of effective inertia with speed. These 

 things do not destroy, but supplement, Newtonian dynamics. They 

 generalise it in a legitimate and intelligible manner. Such compli- 

 cations as these are clearly in accordance with truth and are to be 

 welcomed ; but the complicated theory of gravitation created this 

 century by Einstein, and developed by his successors, and the con- 

 sequent overhauling of space and time relations, do not at present 

 commend themselves to me, nor I think to others of what I suppose 

 must be called the older school. 



Meanwhile the full-blown theory has the courage of its convic- 

 tion and has predicted a definite result, viz. the deflexion of a ray 

 of light by the sun's limb, equal to 1*75 seconds of arc. The 

 prediction is going to be tested during the solar eclipse of May 29 

 this year, between Brazil and the Gulf of Guinea. Let the issue be 

 clearly understood. If a star-ray grazing the sun is deflected 

 J second it will mean only that light has weight, that the wave-front 



♦ See The Philosophical Magazine for August, 1917, and February, 1918, 

 pp. 145, 155 and 156. 



