58 PROCEEDINGS OF THE NEW HAVEN MEETING 



thinking. If a scientific man is not required to teach so mneh as to exhaust 



bis time and strength, bis teaching fits bim for better work as an investigator. 

 It was tbe good fortune of Professor Dana to have enough of teaching and not 

 too much. His most fruitful work was done during the period of his profes- 

 sorship in Yale. His greatest and most influential book, tbe "Manual of Ge- 

 ology.'" was published in 1862; and tbe fourth edition, the last iuportant work 

 of bis life, was published in 1895. 



The career of Professor Dana reminds us in various ways of that of Dar- 

 win. Tbe two men were alike in the great duration of productive activity : in 

 the number and variety of tbe subjects which engaged their attention : in the 

 adventurous, world-wide exploration at the beginning of the career of each, 

 and in tbe half-century of peaceful home life that followed. They were alike 

 also in the experience of impaired health, and of a pathetic struggle to hus- 

 band a scanty capital of physical vigor and endurance and make it yield the 

 largest possible income of intellectual achievement. 



I have elsewhere put on record 1 my own estimate of the work of Dana in 

 the three sciences to which different periods of his life were chiefly devoted — 

 mineralogy, zoology, geology. Today tbe discussion of bis scientific work has 

 been assigned to others most fit to appraise it at its true value. My dnty is to 

 speak of the general characteristics of the man. 



The characteristic that most impressed all who really knew him was his 

 profound sense of the sac-redness of truth. With absolute sincerity be sought 

 to know the truth and to tell tbe truth to others. No pride in what is wrongly 

 called consistency made him unwilling to change his opinions. He seeme 1 to 

 take pleasure iu confessing ignorance or error. In tbe third edition of his 

 "System of Mineralogy." when he cast aside the classification and the Latin 

 binomial nomenclature of the former editions, he wrote iu tbe preface : "To 

 change is always seeming fickleness. But not to change with the advance of 

 science is worse : it is persistence in error." He said to me. in speaking of the 

 changes introduced iu the third edition of the '"Manual of Geology" : "When 

 a man is too old to learu he is ready to die. or at least he is not fit to live." 

 The frankness with which he changed his opinions and bis teachings on the 

 subject of evolution when more than threescore years of age is a striking illus- 

 tration of his loyalty to truth. It was in 1S74. in the second edition of the 

 "Text-book of Geology." that he first avowed himself, though iu somewhat 

 qualified fashion, a believer in the doctrine which he had so earnestly antag- 

 onized. His conversion would probably have come somewhat earlier but for 

 the fact that, ou account of his impaired health at the time, he did not read 

 tbe '•Origin of Species" until several years after its publication. The same 

 delicate sense of truth which made bim so ready to change opinions made it 

 possible for bim to bold opinion in abeyance. He knew that he did not know 

 some things and he would not assert plausible conjectures as truths. Pro- 

 fessor Farriugfon has preserved- some of tbe aphorisms which he uttered from 

 time to time, which might well be adopted as maxims by all students of sci- 

 ence. "I think it better to doubt until you know. Too many people assort 

 and then let others doubt." "I have found it best to be always afloat in regard 

 to opinions on geology." 



1 Jordan : Leading American men of science. New York, 1810, pp. 233-268. 

 - Journal of Geology, vol. 3, p. 335. 



