SOURCES OF INFORMATION 



from ordinary social duties, his colleagues and pupils were 

 sure of a welcome, until departing strength compelled 

 him to economize the little that remained. In seeking to 

 regain his health he engaged in out-of-doors study of the 

 geological region which constitutes the New Haven plain 

 and its environments. Sometimes these excursions were 

 made alone, on foot or on horseback. Sometimes a 

 friend or pupil went with him. At length it became his 

 habit, at least once a year, to take his class with him into 

 the field, and there give them an informal lecture or ob- 

 ject-lesson. None of his auditors was likely to forget his 

 bearing on these occasions. He was so clear, so appreci- 

 ative of the mental attitude of his scholars, and so ap- 

 proachable that every student was charmed and inspired. 



Brief personal memoranda respecting his life have been 

 discovered in Mr. Dana's handwriting, jotted down per- 

 haps in answer to the inquiries of some editor or perhaps 

 for the information of his family ; but there is nothing 

 that can be termed an .autobiography. His journal of the 

 Exploring Expedition is not known to be in existence. 

 Many of his letters have been preserved, and among 

 them those which were written to the immediate mem- 

 bers of his family during his early journeys. They show 

 the characteristics of a young traveller, writing freely to 

 his nearest kin, with enthusiasm and affection. In later 

 life, his letters are largely taken up with what may be 

 called the business of a scientific man, brief, simple, 

 pointed, an answer to a question, or a question for an 

 answer. They are sometimes, but rarely, devoted to 

 scientific discussion. As the pages of the American 

 Journal were within his control, these became the place 

 of record for many current observations which would 

 otherwise have been committed to his correspondence. 



Among the letters that have come to light are a few 

 addressed to Darwin, while twenty of Darwin's to Dana 

 are at hand. There are many from Asa Gray, his life- 



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