The Voyage of the Beagle (Journal of Researches)

Darwin's narrative first appeared in May 1839 as volume III ('Journal and Remarks') of Captain FitzRoy's Narrative of the Surveying Voyages of H.M.S. Adventure and Beagle, issued in three volumes plus an appendix to volume II. Owing to its outsized popularity, Colburn reissued it separately that August using the same printed text sheets, with the preliminary leaves cancelled and reset and a new title page reading Journal of Researches into the Geology and Natural History of the various countries visited by H.M.S. Beagle...; this August 1839 separate issue is what is collected as Darwin's first book