42 



SCIENCE 



[N. S. Vol. XXXIII. No. 837 



to terrestrial magnetism, for he said, "A 

 man usually talks best on the subject he 

 knows best." Note the diplomatic and 

 graceful manner in which he intimated to 

 me that I might possibly know a little 

 more as to the earth's magnetism than of 

 magnetism in general. However, since 

 magnetism is one of his own particular 

 fields of research, may we not hope that he 

 will decide to talk to us about this broad 

 subject himself when he reaches the retir- 

 ing age? 



In fact, I am quite ready to confess ig- 

 norance of the most absolute kind on the 

 whole subject of magnetism, terrestrial as 

 well as general. And I am all the more 

 willing to do so because I find myself in 

 excellent company. Was it not von Helm- 

 holtz who characterized "magnetism as the 

 most puzzling of natural forces"? Did 

 not Eowland say that next to gravity, the 

 greatest problem is that of terrestrial mag- 

 netism ? Was it Lorentz who said that our 

 ignorance in magnetism is the disgrace of 

 modern physics, or words to that effect ? 



On the whole, it perhaps does seem best 

 that one should talk, as far as he can, on an 

 occasion like this, concerning a subject 

 from his own directly acquired knowledge. 

 As a retiring president of the British As- 

 sociation some years ago aptly said, when 

 apologizing for confining himself chiefly to 

 his own immediate subjects instead of at- 

 tempting a complete general survey of the 

 progress of science: "Partial views are 

 better than inexact ones; and provision is 

 made for their completion in the annual 

 change of your officer." 



I must take it for granted that I owed 

 the honor of my election as vice-president 

 and chairman of this flourishing section, 

 two years ago, to the fact that it has been 

 my privilege to contribute something 

 towards the stock of our knowledge of the 

 earth's magnetism. I may therefore as- 



sume that you want me in the first instance 

 to "reveal myself in my own subject." I 

 will then only ask one favor of you in re- 

 turn, that you allow me to omit more or 

 less wearisome details and deal to-day only 

 with some of the broader aspects of terres- 

 trial magnetic research. 



Professor Arthur Schuster, diiring his 

 visit to Washington last September, one 

 day remarked jokingly to the speaker, "I 

 am not quite sure whether it has really 

 been best to have a special journal on ter- 

 restrial magnetism for gathering in the 

 chief papers. For when no such organ 

 existed physicists saw, at least occasionally, 

 an article on the subject in their journals, 

 even if they did not read it." The pre- 

 sumption evidently was that physicists 

 nowadays have less opportunity for im- 

 bibing knowledge on terrestrial magnetism 

 and kindred subjects. 



So then, if I, a terrestrial magnetician, 

 may be pardoned for knowing but little of 

 magnetism, or, for that matter, of physics 

 in general, possibly the pure magnetician 

 or the pure physicist would likewise in 

 turn have a valid right to ignorance in ter- 

 restrial magnetism and cosmical physics, 

 were it not for the contradictory fact that 

 he is often found to be the author of our 

 encyclopedia articles on these very topics. 

 His wisdom in these particular fields ap- 

 pears to be gained in that wholesome and 

 unwearisome manner employed by Herbert 

 Spencer, who "never began by attempting 

 to learn what had already been said." 

 "All my life," said he, "I have been a 

 thinker and not a reader, being able to say 

 with Hobbes that 'if I had read as much as 

 other men, I should know as little as 

 they.' " 



We are to spend a few moments together 

 to-day in looking at some of the broader 

 aspects of physical research in a field that, 

 with justice, many of you may look upon 



