No such strikingly original theory is propounded in the second part of "The Geology of the _Beagle_" dealing chiefly with volcanic islands. St. Jago, in the Cape de Verde Islands; Fernando Noronha, Terceira, Tahiti, Mauritius, St. Paul's, Ascension, St. Helena, and the Galapagos are in turn more or less fully described, according to the opportunities the explorer had possessed. To some extent, as in the succeeding part, Darwin adapts his views on mountain elevation too closely to those enunciated by Elie de Beaumont. The third part of the geology of the _Beagle_, entitled "Geological Observations on South America," was not published till 1846. Even this did not exhaust the contributions to geology made from the _Beagle_ voyage, for it did not include the papers on the "Connection of certain Volcanic Phenomena in South America" (1838); on the "Distribution of Erratic Boulders" (1841); on the "Fine Dust which falls on Vessels" (1845); and on the "Geology of the Falkland Islands" (1846). A second edition of the two latter parts of "The Geology of the _Beagle_" was published in one volume in 1876. Meanwhile, after spending a few years of his early married life in London, during which he was often in ill-health, Darwin fixed his residence in 1842 at Down House, near Beckenham, Kent. The little village of Down, three or four miles from the Orpington railway station, was near enough to London for convenient access, yet greatly secluded and thoroughly rural. The traveller's roving days were over, and his infirmity of health prevented him from undertaking very fatiguing journeys. After the cessation of his active work for the Geological Society, Darwin's chief public appearance was when he spoke at the Oxford meeting of the British Association, in 1847, when, strange to say, Ruskin was secretary of the Geological Section. At Down then, situated some 400 feet above the sea level on a plateau of chalk, interrupted by wavy hollows with beech woods on the slopes, about forty years of Darwin's life were passed. Down House, one of the square red brick mansions of the last century, to which have been since added a gable-fronted wing on one side and a more squarely-built wing and pillared portico on the other, is shut in and almost hidden from the roadway by a high wall and belt of trees. On the south side a walled garden opens into a quiet meadow, bounded by underwood, through which is seen a delightful view of the narrow valley beyond, towards Westerham.