504 



NATURE 



[June i6, 192 i 



Prof. Einstein's Lectures at King's College, London, and the University of Manchester- 

 After the public lecture Prof. Einstein was the guest 

 of the Principal of King's College at a dinner given; 

 in the college. The Principal's guests included Lord. 

 Haldane, the Dean, the Vice-Principal, and many of 

 the professors of King's College, the Astronomer 

 Royal, Prof. Eddington, Prof. Lindemann, Prof. 

 Whitehead, and others. In responding to his health, 

 Prof. Einstein made an interesting revelation of his 

 attitude to the quantum theory. This theory was, he 

 said, presenting a difficult problem to physics, but the 

 very nature of the difficulty served to bring into relief 

 the attractiveness and satisfaction of the principle of 

 relativity. That principle had served to give a simple 

 and complete explanation of experimental facts which 

 under any other aspect were discordant. In the 

 quantum theory as it stood at present we were 

 faced with discordant experimental facts, and 

 were searching for the principle on which to interpret 

 them. 



The Adamson lecture was delivered at the Univer- 

 sity of Manchester on Thursday, June 9, by Prof. 

 Einstein, who had been invited by the council in 

 accordance with a Senate recommendation passed on 

 February 3. At the opening of the proceedings the 

 honorary degree of D.Sc. was conferred on Prof. 

 Einstein. The lecture, which was delivered in German 

 without an interpreter before a very large audience, 

 was on the theory of relativity, and dealt in par- 

 ticular with th^ relation between geometry and 

 physics. Prof. Einstein described how geometry had 

 developed from a collection of individual theorems^ 

 discovered empirically to a body of doctrine in which 

 the logical connection between these theorems is per- 

 ceived and explained. The logical structure required 

 as its foundation a set of axioms, which constitute 

 the residue of empiricism in the theory. The axioms- 

 of Euclid acquired such authority that in time they 

 came to be regarded as necessities of human thought 

 owing to the inherent nature of the mind, and thus 

 the illusion was created that Euclidean geometry is 

 free from anything empirical or arbitrary. On apply* 

 ing geometry to physics the tacit assumption was 

 made that lengths measured by and on solid bodies 

 correspond to lengths in Euclidean geometry. Prof. 

 Einstein showed how the gradual discovery, through 

 physical experiment and observation, of the fact that 

 for objects of astronomical dimensions the axioms of 

 Euclid do not hold good, had led first to the special, 

 and then to the general, theory of relativity. He 

 devoted the latter part of his lecture to the exposition 

 of a non-Euclidean geometry (interpreting geometry in 

 the sense of the theory of the possible positions of 

 objects in space) in a plane, the objects in the plane 

 being shadows of circular "beetles" inhabiting a 

 sphere, the source of light being on the sphere, and 

 the plane being a tangent plane at the opposite end 

 of the same diameter. 



THE most noticeable circumstance in the lecture 

 which Prof. Einstein delivered on June 13 at 

 King's College on "The Development and Present 

 Position of the Theory of Relativity " was the beauty 

 and simplicity of his account of the theory. He made 

 no attempt to enliven it by introducing any of the 

 delightful illustrations which, however illuminating 

 and attractive they may be to the popular mind, sur- 

 round it with a halo of scientific romance. On the 

 other hand, he found no occasion to have recourse to 

 the blackboard, and he entirely omitted anything 

 which required mathematical formulae for its expres- 

 sion. He seemed, too, with earnestness and obvious 

 sincerity to disclaim for himself any originality, and 

 he deprecated the idea that the new principle was 

 revolutionary. It was, he told his audience, the direct 

 outcome and, in a sense, the natural completion of 

 the work of Faraday, Maxwell, and Lorentz. More- 

 over, there was nothing sf>ecially, certainly nothing 

 intentionally, philosophical about it. The whole theory 

 was experimental in its origin, and the satisfaction 

 it brought was simply in the fact that it put us in 

 possession of a method of scientific research which 

 not only did not bring us into conflict with observed 

 facts, but also positively accorded with them. 



The most absorbing part of the lecture was the 

 exposition of his concept of our universe as being 

 spatially a closed system and yet boundless. In this 

 connection he referred to the work of Ernst Mach, 

 who had been the first to direct attention to a dis- 

 tinct point in which the Newtonian theory of motion 

 is unsatisfactory. It led Mach to endeavour to alter 

 the mechanical equations so that the inertia of 

 bodies should be attributed to their relative motion 

 with reference, not to Newton's fictitious absolute 

 space, but to the sum total of all other measurable 

 bodies. 



Prof. Einstein's modesty served only to give force 

 to the impression which all received, and which Lord 

 Haldane (who presided) admirably expressed, that we 

 were welcoming not only one who is himself a man 

 of genius, but one whose discovery is to be ranked 

 with those of Newton, Galileo, and Copernicus — dis- 

 coveries which in revolutionising thought have turned 

 scientific inquiry in a new direction and enlarged 

 the scientific horizon. In one aspect, as Lord Hal- 

 dane pointed out, Einstein's revolution is more pro- 

 found than that of the greatest of his predecessors, 

 for while Copernicus and those who followed him 

 corrected our deductions from phenomena within a 

 generally accepted framework, Einstein has shown 

 us the need of reconstituting our conception of that 

 framework itself. It is not of choice, but of neces- 

 sity, that the principle of relativity has raised a 

 problem, and that the profoundest problem, in meta- 

 physics — the problem of the relation of reality itself to 

 knowledge. 



Physico-chemical Problems Relating to the Soil. 



THE Faraday Society held a general discussion on 

 May 31 on physico-chemical .problems relating 

 to the soil. Sir Daniel Hall, in taking the chair, 

 said that the papers to be presented would show that 

 physico-chemical studies of soil were now as necessary 

 as those of a purely chemical or physical nature. 



Dr. E. J. Russell, director of the Rothamsted Ex- 

 perimental Station, in opening the discussion, gave a 

 general review of the phenomena associated with the 

 four main headings into which the subject was 

 divided : — Soil moisture, organic constituents of the 

 soil, adsorption phenomena, colloidal phenomena, etc. 



The section on soil moisture was opened by Mr. 



NO. 2694, VOL. 107] 



B. A. Keen (Rothamsted), who dealt with the system 

 soil-soil moisture, and pointed out that it was neces- 

 sary to assume a complex colloidal coating over the 

 soil-grains. The paper concluded with an account of 

 the quantitative relations brought out by the freezing- 

 point method of examining soil solution. Prof. Sven 

 Oden (Stockholm), in a note on the hygroscopicity of 

 clay, showed that the hygroscopicity of soils was not 

 necessarily proportional to the total surface area of 

 the particles. Prof. Hoagland (University of Cali- 

 fornia) and Prof. Shull (University of Kentucky) for- 

 warded papers dealing with the relation between the 

 soil solution and the plant. The former dealt mainly 



