NOTES 483 



The Nobel Physics Prizes, 1915 



The Nobel Prize for Physics for the year 191 5 was awarded 

 to Prof. W. H. Bragg and his son W. L. Bragg, in recognition 

 of the importance of their joint work on the application of 

 X-rays to the determination of the atomic arrangement of 

 crystals. Prof. Bragg was born in 1862 at Stoneraise Place, 

 VVigton, Cumberland. He was educated at King William's 

 College in the Isle of Man and at Trinity College, Cambridge, 

 where he became third Wrangler in the year 1884. Two years 

 later he accepted an invitation to the Chair of Physics at 

 Adelaide University, and he remained there for the next twenty- 

 two years. In 1889 he married the daughter of Sir Charles 

 Todd, who, during his long service as Postmaster-General of 

 South Australia, was responsible for driving the telegraph line 

 from Adelaide to Port Darwin across the Australian continent : 

 his grandson has the unique distinction of becoming a Nobel 

 laureate in his twenty-fifth year ! 



At Adelaide, Prof. Bragg carried out research which 

 gained him world-wide fame ; in particular his work on the 

 range of ionisation of a-particles has become a classic in 

 the history of radioactivity. He was elected Fellow of the 

 Royal Society in 1907, and in 1909 returned to England as 

 Cavendish Professor of Physics at Leeds University, whose 

 laboratories thus gained the enviable distinction of being the 

 site of the X-ray experiments which were pursued there from 

 191 2 up to the time when, in 19 14, he was persuaded to accept 

 the Quain Chair of Physics at University College, London. 

 The immense importance of these experiments was speedily 

 recognised at home and abroad, and some months before the 

 Nobel award was announced Prof. Bragg and his son received 

 the Barnard Gold Medal from the University of Columbia — a 

 medal given quinquennially for distinguished scientific research. 

 W. L. Bragg also went to Trinity College, of which he is now 

 a Fellow, and his X-ray work was the direct outcome of his 

 father's suggestions when, at the end of his degree course, he 

 was seeking a fruitful line of research. In order to explain 

 how this came about it will be necessary to relate just a very little 

 of the history of the subject. 



The nature of X-rays had been the source of much discussion 

 from the time of their discovery by Rontgen in 1895, and 



