JAMES DWIGHT DANA 241 



His field excursions with his classes are gratefully remembered 

 by multitudes of students whose interest in geology was merely 

 incidental. The small number of advanced students who were 

 destined to be themselves geologists, came to know more intimately 

 the mind and heart of their master, and cherish his memory with 

 reverent love. 



A certain amount of teaching is undoubtedly a help to the inves- 

 tigator. The work of exposition is an aid to clear thinking. The 

 human interest of imparting knowledge and awakening the intel- 

 lectual life of others gives a new fervor to one's own intellectual 

 life and a new zest to the work of acquiring knowledge. It is, 

 however, the misfortune of many teachers to be so overloaded 

 with routine duties as to have no time for the work of investiga- 

 tion, of which they might otherwise be capable. It was the good 

 fortune of Professor Dana to have enough of teaching and not 

 too much. His teaching made him greater as an investigator, 

 and left him time for investigation. 



The career of Professor Dana reminds us in various ways of 

 that of Darwin. In the great duration of productive activity, in 

 the number and variety of the subjects which engaged their atten- 

 tion, in the adventurous world-wide exploration at the beginning of 

 the career of each, and the half-century of peaceful home life that 

 followed, the two careers were much alike. The experience of 

 the two great scientists was alike also in the fact of impaired 

 health, and of pathetic struggle to husband a scanty capital of 

 physical vigor and endurance so as to make it yield the largest 

 possible income of intellectual achievement. When about forty- 

 five years of age, Dana found his health showing signs of break- 

 down from the effects of overwork. In 1859-60 he was compelled 

 to take a year of rest, which was spent in travel in Europe. The 

 months of travel brought only partial restoration o health, and 

 he was not able to resume his college duties till 1862. In Decem- 

 ber of that year he wrote to Darwin: "I have worked to great 

 disadvantage, from one to three hours a day, and often not at all. 

 An hour's intercourse with the students in the lecture-room is a 

 day's work for me." The two illustrious sufferers could well 



