NOTES 455 



possibly ruined, by officers who did not understand them. Delay, too, arose from 

 the fact that the judges of outside inventions were frequently not unbiassed, for 

 the reason that they themselves were technical officers interested in, and perhaps 

 actually working on, the same projects. Prof. Gray would have a testing board 

 of practical, well-qualified physicists and other experts, none of whom were 

 inventors of appliances of the same kind as those submitted for their judgment. 

 He viewed with alarm the lack of appreciation of scientific education still dis- 

 played by the authorities. Scientific eminence is almost a disqualification, and 

 control, even of research, is in the hands of "good business men — the supermen 

 of the present age." In this connection Prof. Gray welcomed the proposal to 

 found an Institute of Physics, for he believes that reform lies to a great extent 

 in the organisation of scientific men themselves. At the same time he uttered a 

 warning against making organisation itself a fetish, and opposed ultra-centralisa- 

 tion. Another danger which he foresees is the emphasis which appears always 

 to be laid on the industrial side of research. Prof. Gray pleaded for pure science 

 as by far the most important thing, and asked that the scientific discoverer may 

 be free, like Faraday, to follow where his researches lead. Then, in the long run, 

 as in Faraday's case, the practical results will surpass all expectation. 



The latter part of Prof. Gray's address dealt with the teaching of physics. He 

 deprecated the tendency to regard dynamics, not as a part of physics, but as 

 applied mathematics. At the same time he believes in the thorough study of 

 mathematics, and regards as mischievous the attitude of ultra-simplicity exempli- 

 fied by the statement of an eminent practical engineer that " all the calculus an 

 engineering student requires could be learned in an hour or two." Prof. Gray also 

 made brief reference to modern developments in molecular physics, particularly to 

 the recent work of Sir E. Rutherford on the collisions of a-particles with atoms 

 of small mass. 



The Proceedings of the Section included an interesting discussion on 

 Thermionic Vacuum Tubes, which was opened by Prof. Eccles, who gave a 

 general description of the very varied uses of these tubes. The three-electrode 

 thermionic vacuum tube has practically revolutionised wireless telegraphy during 

 the war. Used for amplifying continuous wave-signals, magnifications of, perhaps, 

 100,000-fold are obtained, and transmission across the Atlantic is now possible 

 with a receiving antenna consisting of a coil of wire only 3 or 4 ft. square. Tubes 

 can also be used as producers of high-frequency alternating current, and can 

 be made of sufficient size to become powerful wireless transmitters. The action 

 of the tube depends on the electronic emission from hot bodies, and it is possible 

 that it may have a great future in that we may be able to derive electricity direct 

 from fuel, without machinery. Prof. Eccles described the construction of the 

 tube, and pointed out that, used as an amplifier, a single tube will give a faithful 

 reproduction in the proportion 20 : 1, while several, used in cascade, will give 

 much greater ratios. There is almost complete absence of lag and of reaction on 

 the original circuit. As a detector the tube, if nearly but not quite oscillating, 

 readily responds to incoming signals of the same frequency, and is thus most 

 efficient. Or, if oscillating with supersonic frequency, the stimulus of incoming 

 signals of nearly the same frequency gives rise to a " beat " note which can, by 

 adjustment, be rendered audible. 



Prof. Fortescue drew attention to the lines upon which it might be hoped still 

 further to improve the tubes. At present only 4! per cent, of the power used in 

 heating the filament is available. Filaments coated with lime are temporarily 

 more efficient, but deteriorate. Thermal production of electrons is really 



