DISCOVERY 



271 



leased the gems from their original bed and distributed 

 them far and wide over the undulating or flat ground. 

 There are very many beautiful spots in the gemming 

 districts still quite undisturbed by the tourist. I 

 obtained a very fine specimen of Ceylon ruby in one 

 stream a little lower down from a fall, during my 

 course of inspection, but the Ceylon ruby is not counted 

 of first qualit}' as it is pale in colour ; the public 

 prefers the pigeon-blood colour of the Burma ruby. 



The most valued stones in Ceylon are the sapphires 

 and zircons of deep blue, and yellow to pure water- 

 white, topaz, amethysts, cats'-eyes, star-rubies and 

 star-sapphires, alexandritcs, olivines, and the like. 



Wanted — Mineralogists 



From the view of the mineralogist, Ceylon offers 

 perhaps the best hunting-ground. It has received 

 little or no attention from the mineral financier and 

 comparatively few men of mineral knowledge have 

 troubled about it. There are miles of streams and 

 square miles of deposits that have only been partially- 

 scratched by the native. There is still plenty of scope 

 for anyone interested in gems to go and fill his pockets 

 with many beautiful stones, and, if luck comes his way, 

 of obtaining something really beautiful and valuable 

 for his holiday. 



At the British Association's 

 Meeting 



The meeting of this famous association, which has come 

 to be looked on in the light of a national institution, was 

 held this year at Liverpool from September 12 to Sep- 

 tember ig. It was, perhaps, one of the most interesting 

 meetings ever held, since the place chosen is not only one 

 of the greatest ports in the world, but is also an impor- 

 tant centre of industry and the seat of a imiversity, and 

 this fact appears to have influenced many of the speeches 

 and discussions. We regret that the meeting was held 

 too late this year for us to include anything like a full 

 account of it in this number. We shall give our readers 

 further accounts of the work got through by certain of 

 the groups in subsequent numbers of DiscovicRV. Mean- 

 while a short summary will not be out of place. 



The Electrical Structure of Matter 



The characteristic note of the meeting was sounded on 

 the first day by Sir Ernest Rutherford, this year's Presi- 

 dent, who in the early stages of his speech on the above 

 subject commented on the benefits of the union of pure 



and applied science. " 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 investigator in the fundamental problem, 

 while the development of new methods and appUances 

 required for technical purposes often provides the investi- 

 gator with means of attacking still more difficult ques- 

 tions. " 



Passing on to the main thesis of his address. Sir Ernest 

 summarised with wonderful lucidity and comprehensive- 

 ness the advances made in man's knowledge of the struc- 

 ture of matter since the last Liverpool meeting twenty- 

 seven years ago. The atomic theory was first announced 

 by Dalton. Next the researches of Lord Kelvin and 

 others resulted in rough estimates of the " absolute 

 dimensions and mass of the atoms," which made scientists 

 reaUse the minute size of the atom and which led some of ■ 

 them to believe that the atomic theory could never be 

 proved by direct experiment. 



Up to this point only vague ideas were held as to the 

 possible structure of the atoms, but there was a general 

 belief that they " could not be regarded as simple un- 

 connected units." In 1897, however, the discovery of 

 what is now called the electron, " a mobile electrified unit, " 

 infinitely more minute than the lightest atom, and of the 

 fact that it could be freed from all the atoms of matter 

 by various methods, strengthened the belief, started by 

 . Mendeleefs studies of the periodic variations of the 

 properties of the elements, that it was probably the 

 common unit in the structure of atoms. Scientists now 

 began to attack tentatively on these lines the absorbing 

 problem of what the atom consisted of, the work of Sir 

 J. J. Thomson, who boldly took the view that it must 

 be " an electrical structure, held together by electrical 

 forces," contributing greatly to the development of this 

 subject. 



Meanwhile the study of radio-activity and the discovery 

 of radium revolutionised " our whole conception of the 

 atom and of the magnitude of the forces which held it 

 together." The extraordinary radio-active elements, 

 such as radium and uranium, enable scientists to study 

 the changes originating actually in the heart of their 

 radio-active atoms — changes which are due to atomic 

 explosions of power infinitely greater than that to be 

 found in ordinary physical or chemical processes. For 

 instance, the so-called a-particle expelled in the 

 majority of these explosions has now been proved to be 

 a charged helium atom, and this has revealed " the 

 importance of helium as one of the units in the structure 

 of the radio-active atoms, and probably also in that of the 

 atoms of most of the elements." 



These extraordinary bodies, then, have provided us 

 with much new knowledge of matter and also with tools 

 for further exploration, as in the case of a-particles, 

 which, used as projectiles to bombard and explore the 

 atom's interior, have " exhibited its nuclear structure," 

 and " led to artificial disentegration of certain light 

 atoms." 



The detection of the effect of a single atom was first 



