604 THE JOURNAL OF GEOLOGY. 
studies he wrote ‘‘Characteristics of Volcanoes, with contribu- 
tions of facts and principles from the Hawaiian Islands,’ 400 
pages, in 1890. Much might be said in elaboration of this 
subject, —the influence of the experiences of 1838-42 in 
shaping his future investigations and contributions to science — 
and some of the developments of his geological theories and 
works will be briefly traced beyond; but space will not here admit 
the discussion of the equally interesting contributions Dana made 
to the subject of organic evolution and the correlations between 
the conditions of life, geological time, and the structure and form 
of organisms. His studies in the several fields of organisms, 
minerals and geology made in the earlier, most active period of 
his life (if there was any time in his life when his activity was 
abated except by sickness) were an important factor in enabling 
him to understand nature intimately in her more hidden work- 
ings, which by most observers is seen from only one side and 
therefore but partially comprehended. After returning from 
the exploring expedition, he spent two years at Washington 
working on the reports, then he went to New Haven where he 
resided throughout the remainder of his life. 
In the interval between the first two ocean voyages, he was 
Professor Silliman’s Assistant in Yale college, and then produced 
his first important work, A System of Mineralogy: including an 
extended treatise of crystallography with an appendix containing 
the application of mathematics to crystallographic investigation, 
and a mineralogical bibliography. The first edition was of 594 
pages and was published in 1837. The title though long givesa 
concise description of the scope of this book which at once took 
a first place as a treatise on mineralogy in the English language, 
and in its successive editions it has not lost its place up to the 
present day. 
That geology was his favorite study is shown by the number 
of titles in the bibliography. Dividing the list by decades, begin- 
ning with 1835, for the first three decades the number of titles is 
almost equally distributed in the three groups: Geology 37, 
Mineralogy 34, Zodlogy 38. After 1865, however, but seven 
