A HISTORY OF SCIENCE 



moods are exceptional. Our chief concern is with 

 strictly contemporary events with the deeds and per- 

 sonalities of scientific investigators who are still in the 

 full exercise of their varied powers. I had thought 

 that such outlines of the methods of contemporary 

 workers, such glimpses of the personalities of living 

 celebrities, might form a fitting conclusion to this 

 record of progress. There is a stimulus in contact 

 with great men at first hand that is scarcely to be gain- 

 ed in like degree in any other way. So I have thought 

 that those who have not been privileged to visit the 

 great teachers in person might like to meet some of 

 them at second hand. I can only hope that something 

 of the enthusiasm which I have gained from contact 

 with these men may make itself felt in the succeeding 

 pages. 



It will be observed that these studies of contem- 

 porary workers are supplemented with a chapter in 

 which a hurried review is taken of the field of cos- 

 mical, of physical, and of biological science, with ref- 

 erence to a few of the problems that are still unsolved. 

 As we have noted the clearing up of mystery after mys- 

 tery in the past, it may be worth our while in conclu- 

 sion thus to consider the hordes of mysteries which the 

 investigators of our own age are passing on to their suc- 

 cessors. For the unsolved problems of to-day beckon 

 to the alluring fields of to-morrow. 



