36 THE POPULAR SCIENCE MONTHLY. 



longer contests the share in education which is claimed by the 

 new, or is blind to the supreme influence which natural knowl- 

 edge is exercising in molding the human mind. 



A study of the addresses of my learned predecessors in this 

 office shows me that the main duty which it falls to a president to 

 perform in his introductory address is to remind you of the sali- 

 ent points in the annals of science since last the association visited 

 the town in which he is speaking. Most of them have been able 

 to lay before j^ou in all its interesting detail the history of the 

 particular science of which each one of them was the eminent 

 representative. If I were to make any such attempt I should 

 only be telling you with very inadequate knowledge a story 

 which is from time to time told you, as well as it can be told, 

 by men who are competent to deal with it. It will be more suit- 

 able to my capacity if I devote the few observations I have to 

 make to a survey not of our science but of our ignorance. We live 

 in a small, bright oasis of knowledge, surrounded on all sides by 

 a vast unexplored region of impenetrable mystery. From age to 

 age the strenuous labor of successive generations wins a small 

 strip from the desert and pushes forward the boundary of knowl- 

 edge. Of such triumphs we are justly proud. It is a less attract- 

 ive task but yet it has its fascination as well as its uses to turn 

 our eyes to the undiscovered country which still remains to be 

 won, to some of the stupendous problems of natural study which 

 still defy our investigation. Instead, therefore, of recounting to 

 you what has been done, or trying to forecast the discoveries of 

 the future, I would rather draw your attention to the condition 

 in which we stand toward three or four of the most important 

 physical questions which it has been the effort of the last century 

 to solve. 



Of the scientific enigmas which still, at the end of the nine- 

 teenth century, defy solution, the nature and origin of what are 

 called the elements is the most notable. It is not, perhaps, easy 

 to give a precise logical reason for the feeling that the existence 

 of our sixty-five elements is a strange anomaly and conceals some 

 much simpler state of facts ; but the conviction is irresistible. 

 We can not conceive, on any possible doctrine of cosmogony, 

 how these sixty-five elements came into existence. A third of 

 them form the substance of this planet. Another third are use- 

 ful, but somewhat rare. The remaining third are curiosities 

 scattered haphazard, but very scantily, over the globe, with no 

 other apparent function but to provide occupation for the col- 

 lector and the chemist. Some of them are so like each other that 

 only a chemist can tell them apart ; others differ immeasurably 

 from each other in every conceivable particular. In cohesion, in 

 weight, in conductivity, in melting point, in chemical proclivities 



