PREFACE. 7 
in the ‘Scientific Corps” were Dr. Cuaries Pickertna, J. P. 
Cournouy, and Trrtan R. Prax, Zodlogists; Wu. Ricu and 
J. D. Brecxenripe®, Botanists; Horatio Hare, Philologist; 
JosEpH Drayton and A. T. Acars, Artists. 
Our cruise led us partly along the course followed by Mr. 
Cuarurs Darwin during the years 1831 to 1836, in the Voyage 
of the Beagle, under Captain Firzroy ; and, where it diverged 
from his route, it took us over scenes, similar to his, of coral and 
voleanic islands. Soon after reaching Sydney, Australia, in 
1839, a brief statement was found in the papers of Mr. Dur- 
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 Feejces, 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 
