162 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1924 



develop from these two fundamental discoveries, but in the records 

 of the Liverpool meeting we see the dawning recognition of the pos- 

 sible consequences of the discovery of X rays, not only in their ap- 

 plication to medicine and surgery, but as a new and powerful agent 

 for attacking some of the fundamental problems of physics. The 

 address of Prof. J. J. Thomson, president of Section A, was devoted 

 mainly to a discussion of the nature of the X rays, and the remark- 

 able properties induced in gases by the passage of X rays through 

 them — the beginning of a new and fruitful branch of study. 



In applied physics, too, this year marked the beginning of another 

 advance. In the discussion of a paper which I had the honor to 

 read, on a new magnetic detector of electrical waves, the late Sir 

 William Preece told the meeting of the successful transmission of 

 signals for a few hundred yards by electrical waves which had been 

 made in England by a young Italian, G. Marconi. The first public 

 demonstration of signaling for short distances by electric waves 

 liad been given by Sir Oliver Lodge at the Oxford meeting of this 

 association in 1894. It is startling to recall the rapidity of the 

 development from such small beginnings of the new method of 

 wirdess intercommunication over the greatest terrestrial distances. 

 In the last few years this has been followed by the even more rapid 

 growth of the allied subject of radiotelephony as a practical means 

 of broadcasting speech and music to distances only limited by the 

 power of the transmitting station. The rapidity of these technical 

 advances is an illustration of the close interconnection that must 

 exist between pure and applied science if rapid and sure progress 

 is to be made. The electrical engineer has been able to base his 

 technical developments on the solid foundation of Maxwell's electro- 

 magnetic theory and its complete verification by the researches of 

 Hertz, and also by the experiments of Sir Oliver Lodge in this uni- 

 versity — a verification which was completed long before the prac- 

 tical possibilities of this new method of signaling had been generally 

 recognized. The later advances in radiotelegraphy and radiotele- 

 phony have largely depended on the application of the results of 

 fundamental researches on the properties of electrons, as illustrated 

 in the use of the thermionic valve or electron tube which has proved 

 such an invaluable agent both for the transmission and reception of 

 electric waves. 



It is of great interest to note that the benefits of this union of pure 

 and applied research have not been one-sided. If the fundamental 

 researches of the workers in pure science supply the foundations on 

 which the applications are surely built, the successful practical 

 application in turn quickens and extends the interest of the investi- 

 gator in the fundamental problem, while the development of new 

 methods and appliances required for technical purposes often pro- 



