XVIII 
DARWIN AND GEOLOGY 
By J. W. Jupp, OB, LLD., F.RS. 
In one of the very interesting conversations which I had with 
Charles Darwin during the last seven years of his life, he asked 
me in a very pointed manner if I were able to recall the circum- 
stances, accidental or otherwise, which had led me to devote myself 
to geological studies. He informed me that he was making similar 
inquiries of other friends, and I gathered from what he said that 
he contemplated at that time a study of the causes producing 
scientific bias in individual minds. I have no means of knowing how 
far this project ever assumed anything like concrete form, but certain 
it is that Darwin himself often indulged in the processes of mental 
introspection and analysis; and he has thus fortunately left us—in 
his fragments of autobiography and in his correspondence—the 
materials from which may be reconstructed a fairly complete history 
of his own mental development. 
There are two perfectly distinct inquiries which we have to 
undertake in connection with the development of Darwin’s ideas on 
the subject of evolution : . 
First. How, when, and under what conditions was Darwin led 
to a conviction that species were not immutable, but were derived 
from pre-existing forms? 
Secondly. By what lines of reasoning and! research was he 
brought to regard “natural selection” as a vera causa in the process 
of evolution ? 
1 Mr Francis Darwin has related how his father occasionally came up from Down 
to spend a few days with his brother Erasmus in London, and, after his brother’s death, 
with his daughter, Mrs Litchfield. On these occasions, it was his habit to arrange 
meetings with Huxley, to talk over zoological questions, with Hooker, to discuss botanical 
problems, and with Lyell to hold conversations on geology. After the death of Lyell, 
Darwin, knowing my close intimacy with his friend during his later years, used to ask me 
to meet him when he came to town, and ‘‘talk geology.” The ‘‘talks” took place 
sometimes at Jermyn Street Museum, at other times in the Royal College of Science, 
South Kensington; but more frequently, after having lunch with him, at his brother’s 
or his daughter’s house. On several occasions, however, I had the pleasure of visiting 
him at Down. In the postscript of a letter (of April 15, 1880) arranging one of these 
visits, he writes: ‘‘ Since poor, dear Lyell’s death, I rarely have the pleasure of geological 
talk with anyone.” 
D. 
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