On her homeward voyage, the "Beagle" visited Tahiti, Australia, and some of
the coral-islands in the Indian Ocean, and Darwin had an opportunity of
testing and verifying the conclusion at which he had arrived by studying
the statements of other observers.

I well recollect a remarkable conversation I had with Darwin, shortly after
the death of Lyell. With characteristic modesty, he told me that he never
fully realised the importance of his theory of coral-reefs till he had an
opportunity of discussing it with Lyell, shortly after the return of the
"Beagle". Lyell, on receiving from the lips of its author a sketch of the
new theory, was so overcome with delight that he danced about and threw
himself into the wildest contortions, as was his manner when excessively
pleased. He wrote shortly afterwards to Darwin as follows:--"I could think
of nothing for days after your lesson on coral-reefs, but of the tops of
submerged continents. It is all true, but do not flatter yourself that you
will be believed till you are growing bald like me, with hard work and
vexation at the incredulity of the world." On May 24th, 1837, Lyell wrote
to Sir John Herschel as follows:--"I am very full of Darwin's new theory of
coral-islands, and have urged Whewell to make him read it at our next
meeting. I must give up my volcanic crater forever, though it cost me a
pang at first, for it accounted for so much." Dr. Whewell was president of
the Geological Society at the time, and on May 31st, 1837, Darwin read a
paper entitled "On Certain Areas of Elevation and Subsidence in the Pacific
and Indian oceans, as deduced from the Study of Coral Formations," an
abstract of which appeared in the second volume of the Society's
proceedings.

It was about this time that Darwin, having settled himself in lodgings at
Great Marlborough Street, commenced the writing of his book on "Coral-Reefs."