It was about the month of March, 1837, that Darwin completed this work upon his rocks, and also the unpacking and distribution of his fossil bones and other specimens. We have seen that November, 1832, must certainly be regarded as the date when he FIRST realised the important fact that the fossil mammals of the Pampean formation were all closely related to the existing forms in South America; while October, 1835, was, as undoubtedly, the date when the study of the birds and other forms of life in the several islands of the Galapagos Islands gave him his SECOND impulse towards abandoning the prevalent view of the immutability of species. When then in his pocket-book for 1837 Darwin wrote the often quoted passage: "In July opened first note-book on Transmutation of Species. Had been greatly struck from about the month of previous March on character of South American fossils, and species on Galapagos Archipelago. These facts (especially latter), origin of all my views" ("L.L." I. page 276.), it is clear that he must refer, not to his first inception of the idea of evolution, but to the flood of recollections, the reawakening of his interest in the subject, which could not fail to result from the sight of his specimens and the reference to his notes.
Except during the summer vacation, when he was visiting his father and uncle, and with the latter making his first observations upon the work of earthworms, Darwin was busy with his arrangements for the publication of the five volumes of the "Zoology of the 'Beagle'" and in getting the necessary financial aid from the government for the preparation of the plates. He was at the same time preparing his "Journal" for publication.
During the years 1837 to 1843, Darwin worked intermittently on the volumes of Zoology, all of which he edited, while he wrote introductions to those by Owen and Waterhouse and supplied notes to the others.
Although Darwin says of his Journal that the preparation of the book "was not hard work, as my MS. Journal had been written with care." Yet from the time that he settled at 36, Great Marlborough Street in March, 1837, to the following November he was occupied with this book. He tells us that the account of his scientific observations was added at this time. The work was not published till March, 1839, when it appeared as the third volume of the "Narrative of the Surveying Voyages of H.M. Ships 'Adventure' and 'Beagle' between the years 1826 and 1836". The book was probably a long time in the press, for there are no less than 20 pages of addenda in small print. Even in this, its first form, the work is remarkable for its freshness and charm, and excited a great amount of attention and interest.
In addition to matters treated of in greater detail in his other works, there are many geological notes of extreme value in this volume, such as his account of lightning tubes, of the organisms found in dust, and of the obsidian bombs of Australia.
Having thus got out of hand a number of preliminary duties, Darwin was ready to set to work upon the three volumes which were designed by him to constitute "The Geology of the Voyage of the 'Beagle'". The first of these was to be on "The Structure and Distribution of Coral-reefs". He commenced the writing of the book on October 5, 1838, and the last proof was corrected on May 6, 1842. Allowing for the frequent interruptions through illness, Darwin estimated that it cost him twenty months of hard work.
Darwin has related how his theory of Coral-reefs which was begun in a more "deductive spirit" than any of his other work, for in 1834 or 1835 it "was thought out on the west coast of South America, before I had seen a true coral-reef." ("L.L." I. page 70.) The final chapter in Lyell's second volume of the "Principles" was devoted to the subject of Coral-reefs, and a theory was suggested to account for the peculiar phenomena of "atolls."Darwin at once saw the difficulty of accepting the view that the numerous and diverse atolls all represent submerged volcanic craters. His own work had for two years been devoted to the evidence of land movements over great areas in South America, and thus he was led to announce his theory of subsidence to account for barrier and encircling reefs as well as atolls.
Fortunately, during his voyage across the Pacific and Indian Oceans, in his visit to Australia and his twelve days' hard work at Keeling Island, he had opportunities for putting his theory to the test of observation.
On his return to England, Darwin appears to have been greatly surprised at the amount of interest that his new theory excited. Urged by Lyell, he read to the Geological Society a paper on the subject, as we have seen, with as little delay as possible, but this paper was "withdrawn by permission of the Council." An abstract of three pages however appeared in the "Proceedings of the Geological Society". (Vol. II. pages 552-554 (May 31, 1837).) A full account of the observations and the theory was given in the "Journal" (1839) in the 40 pages devoted to Keeling Island in particular and to Coral formations generally. ("Journal (1st edition), pages 439-69.)It will be readily understood what an amount of labour the book on Coral reefs cost Darwin when we reflect on the number of charts, sailing directions, narratives of voyages and other works which, with the friendly assistance of the authorities at the Admiralty, he had to consult before he could draw up his sketch of the nature and distribution of the reefs, and this was necessary before the theory, in all its important bearings, could be clearly enunciated. Very pleasing is it to read how Darwin, although arriving at a different conclusion to Lyell, shows, by quoting a very suggestive passage in the "Principles" (1st edition Vol. II. page 296.), how the latter only just missed the true solution. This passage is cited, both in the "Journal" and the volume on Coral-reefs. Lyell, as we have seen, received the new theory not merely ungrudgingly, but with the utmost enthusiasm.
