" The Geology of the Voyage of the Beagle " 367 



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 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 1 ." The final chapter in Ly ell'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 



1 L. L. i. p. 70. 



