SCIENCE 



[N. S. Vol. LIV. No. 1383 



mighty. I have never known a great scientist 

 to make that blunder. And there ought never 

 to be one who makes it because the business 

 of science is to see things as they are. Madame 

 Curie has always remained simple, modest 

 and unafPected in the face of the world's ap- 

 plause. That is the highest compliment which 

 a fellow scientist can pay her, and the surest 

 sign that she is not an ordinary person. 

 With that I have paid my tribute of respect 

 and honor and admiration to the discoverer. 



Now for the discovery. How did it come 

 about? What is it? What is its significance 

 immediate? Wliat is its significance remote 

 and far-reaching? In order to answer that 

 series of questions I wish to begin by disabus- 

 ing your minds of the idea, if they harbor it, 

 that a discovery in science is an isolated event. 

 A science grows in the main as does a planet 

 by the process of infinitesimal accretion. 

 Practically every experiment in physics is a 

 modification of an experiment which has gone 

 before. Almost every new theory is built like 

 a great mediaeval cathedral, through the ad- 

 dition by many builders of many different ele- 

 ments, one adding a little here and another 

 a little there so that to the eye of a distant 

 observer in the clouds the whole structure 

 seems to move forward in a practically con- 

 tinuous way. Even when you get close up and 

 begin to see the discontinuities, for they are 

 there, each experiment in the development of 

 a given field of science is found to have a pedi- 

 gree just as truly as has a race horse. Man- 

 o'-war did not develop his marvelous speed 

 in one generation. A dozen sires and dams 

 contributed to that result. In precisely the 

 same way, when in 1896 Henri Becquerel, pro- 

 fessor of physics in the University of Paris, 

 discovered the new, extraordinary property 

 which certain types of matter were found to 

 possess and which was named radio-activity, 

 that discovery was sired by one made a year 

 before by Roentgen, and Roentgen's was sired 

 by Leonard's, and Leonard's by that of Hertz 

 in 1886, and Hertz's by the work of Maxwell, 

 and Maxwell's by that of Faraday in 1831, and 

 Faraday's by that of Oersted in 1819, and Oer- 

 sted's by Volta's, and Volta's by Franklin's, and 



so on without limit. And the point to which I 

 wish to call your attention now is that it is of 

 incalculable importance that there should be 

 people like those who have given this gramme 

 of radium to Madame Curie who have a vision 

 that extends, not to this generation only, but 

 to the generations that are to come a hundred, 

 two hundred years ahead, and who consciously 

 set about starting such, a train of scientific 

 discovery and progress. 



But for our present purpose I wish to break 

 into this chain of scientific development at 

 the discovery by Professor Becquerel of this 

 extraordinary phenomenon of radio-activity 

 made in the physical laboratory in which 

 Madame Curie had been studying for some 

 years. The discovery itself was really a simple 

 thing, as are practically all great discoveries. 

 The year before Roentgen had found his X- 

 rays, as he called them, which had the pe- 

 culiar property of making it possible for one 

 to see his own skeleton. That attracted the 

 world's attention and Professor Becquerel was 

 endeavoring to see whether rays that would 

 penetrate in that fashion could be produced 

 from other sources. He naturally took ura- 

 nium, because of its fluorescent property, to 

 see whether it, under the action of light, 

 might perhaps transmute the light waves into 

 penetrating waves of the kind Roentgen had 

 obtained. Wliat did he find? He tried it in 

 the light and he tried it in the dark, and he 

 found that it was not necessary to have light 

 at all, but that a bit of uranium put away 

 in a black paper on top of a photograph plate, 

 itself would blacken the plate. In other 

 words, there was a property of self-activity in 

 that uranium. It emitted rays of some kind 

 which would affect a photographic plate and 

 discharge an electroscope. The discharge of 

 an electroscope, in popular language, is simply 

 this: When you comb your hair on a cold 

 winter day and it stands out in all directions, 

 it is because it becomes electrically charged. 

 If now a bit of radioactive substance is held 

 above your head, your hair will fall dovm 

 again, i.e., your electroscope will be discharged. 

 The laboratory electroscope is merely a gold- 

 leaf which stands out like your hair when it 



