JAMES DWIGHT DANA. 603 
The other and chief voyage was with the United States explor- 
ing expedition under Commodore Wilkes, which sailed in August 
1838 and reached New York on the return in June 1842. The route 
took him through the Southern Atlantic, the Straits of Magellan, 
up the western coast of South America, among the islands of the 
Pacific, to the western coast of North America, where he was 
shipwrecked and went overland from the mouth of the Columbia 
River through Oregon, across the flank of Mt. Shasta and through 
north California to San Francisco, thence across the Pacific again 
to the Sandwich Islands, Singapore and around the Cape of Good 
Hope into the Southern Pacific and thence home to New York. — 
In this long cruise he acted in the capacity of geologist and 
mineralogist, but by the failure of others to fill their places, he 
ultimately became the observer and reporter on all the natural 
history. The official reports he wrote were three: the first, ‘On 
Zoéphytes,” 741 pages with a folio atlas of 61 plates, was pub- 
lished in 1846; the second, ‘‘ On Geology,” 756 pages, with a folio 
atlas of 21 plates, was issued in 1849. The third was ‘“‘On the 
Crustacea,’ in two parts, with a total of 1620 pages and 96 folio 
plates, and was issued in 1854. A large number of lesser papers 
and treatises were founded upon facts accumulated during this 
voyage, Or upon investigations carried on in elaborating those 
observations. 
Three lines of investigations, which continued to occupy his 
attention more or less to the end of his life, were the direct out- 
come of the experiences of this voyage; these were about 1) Corals 
and Coral Islands, 2) Volcanoes and the associated problems of 
mountain making and continental development, and 3) Cephal- 
ization; the last topic being incident to the studies made in prep- 
aration of the report ‘On Crustacea.’’ In each of these problems 
he took keen interest and contributed greatly to their elucidation. 
His interest in volcanoes led him to make a journey to the Sand- 
wich Islands in the latter part of his life (1887) to see for him- 
self the changes that had taken place, and to compare Kilauea 
and other volcanoes of Hawaii as they had become, with their 
condition as observed by him in 1840. Asa result of these new 
