JAMES DWIGHT DANA 243 



great variety of volcanic phenomena. The book was the fruit of 

 manifold observation and mature thought. 



His intellectual activity and clearness of thought continued to 

 the very end of his life. In the last months he corrected the proofs 

 of the fourth edition of the Manual of Geology the noblest of 

 all his works. He had commenced a revision of the Text-book 

 of Geology, but the completion of that work was reserved for the 

 hand of a friend and pupil. The Journal of Science for March, 

 1895, contained a brief article on Daimonelix signed with the 

 initials, J. D. D. On Friday, April 12, he wrote a letter to Mr. 

 Frank Leverett, containing a clear discussion of the conditions of 

 eolian work and the limits of its effects. Two days later, on the 

 evening of Easter Sunday, he passed into the eternal rest. 



The appreciation of the work of Dana by other scientific men 

 was testified by the honors which came to him in abundance. 

 Amherst, Harvard, and Edinburgh gave him the degree of Doctor 

 of Laws, Munich that of Doctor of Philosophy. He was Presi- 

 dent of the American Association for the Advancement of Science 

 and of the Geological Society of America, and Vice-President of 

 the National Academy of Sciences. He was elected to membership 

 in the Royal Societies of London, Edinburgh, and Dublin, and 

 the Academies of Paris, Saint Petersburg, Vienna, Berlin, Giittin- 

 gen, Munich, Stockholm, and Buda-Pesth. He received the 

 Copley Medal of the Royal Society of London, the Wollaston 

 Medal of the Royal Geological Society of London, the Clarke 

 Memorial Medal of the Royal Society of New South Wales, and 

 the Walker Prize of the Boston Society of Natural History. 



The science to which the early years of Professor Dana's pro- 

 ductive activity were chiefly devoted was mineralogy. The System 

 of Mineralogy, published in 1837, took rank at once as a standard 

 treatise rather, one might be justified in saying, the standard 

 treatise of the science. 



In the first two editions, Dana followed the so-called " natural 

 classification " of Mohs, in which the groups depended chiefly on 

 conspicuous physical characters, such as hardness, luster, and 



