PREFACE. 7 



in the " Scientific Corps " were Dr. Charles Pickering, J. P. 

 Couthouy, and Titian R. Peale, Zoologists ; Wm. Bicn and 

 J. D. Breckenridge, Botanists ; Horatio Hale, Philologist ; 

 Joseph Drayton and A. T. Agate, Artists. 



Our cruise led us partly along the course followed by Mr. 

 Charles Darwin during the years 1831 to 1836, in the Voyage 

 of the Beagle, under Captain Fitzroy ; and, where it diverged 

 from his route, it took us over scenes, similar to his, of coral and 

 volcanic islands. Soon after reaching Sydney, Australia, in 

 1839, a brief statement was found in the papers of Mr. Dar- 

 win's theory with respect to the origin of the atoll and barrier 

 forms of reefs. The paragraph threw a flood of light over the 

 subject, and called forth feelings of peculiar satisfaction, and of 

 gratefulness to Mr. Darwin, which still come up afresh when- 

 ever the subject of coral islands is mentioned. The Gambier 

 Islands, in the Paumotus, which gave him the key to the 

 theory, I had not seen; but on reaching the Feejees, six 

 months later, in 1840, I found there similar facts on a still 

 grander scale and of more diversified character, so that I was 

 afterward enabled to speak of his theory as established with 

 more positiveness than he himself, in his philosophic caution, 

 had been ready to adopt. His work on Coral Reefs appeared 

 in 1842, when my report on the subject was already in man- 

 uscript. It showed that the conclusions on other points, which 

 we had independently reached, were for the most part the 

 same. The principal points of difference relate to the reason for 

 the absence of corals from some coasts, and the evidence there- 

 from as to changes of level, and the distribution of the oceanic 

 regions of elevation and subsidence — topics which a wide 

 range of travel over the Pacific brought directly and constantly 

 to my attention. 



In the preparation of the present work my former chapter 



