Darwin's diaries: the equator, a leap year, and Brazil

By guest blogger, paleontologist and HMS Beagle archivist Dr Gordon Chancellor

HMS Beagle’s voyage round the world was well under way in March 1832. After three weeks in the Cape Verdes, Captain FitzRoy had completed his magnetic experiments and resumed the Beagle’s south-southwest course.

Flying fish, National Geographic

Darwin tells us in the Beagle diary that there were flying fish, but he had to leave his specimens of marine animals unlabelled because he felt so rough from sea sickness. At next landfall, on St Paul's Rocks, the crew spent their time trying to kill as many seabirds as possible, while Darwin made one of his first major discoveries. 

Almost all smaller oceanic islands around the world are volcanic, while most of the larger ones, such as the Falklands or New Zealand, are mainly composed of continental crust. St Paul’s Rocks are almost unique in being splinters of mantle rock from much deeper in the Earth, and it is to Darwin’s great credit that he recognised them as serpentine. As he wrote in his Geological diary ‘Is not this the first Island in the Atlantic which has been shown not to be of Volcanic origin?’ Darwin's St Paul’s specimens are still valuable after all these years, being extremely rare. 

The little Beagle crossed the equator on 17 February and poor Darwin and the other ‘griffins’ were tarred and feathered in the time-honoured fashion! The ship would stay in the southern hemisphere for four and a half years, bar a few days at the northern islands of the Galapagos in October 1835.

Crossing the line, by T. Landseer after Augustus Earle

A day after his equatorial ordeal, Darwin enjoyed the compensation of seeing the beautiful Magellanic Cloud and the Southern Cross constellation for the first time and the next day, Sulivan (who Darwin always misspelt ‘Sullivan’) caught a porpoise. 

By the 20th, they made the island of Fernando Noronha off the coast of Brazil, and Darwin spent a glorious seven hours climbing to the island’s peak, marvelling at the tropical vegetation in spite of the heat. Even Beagle buffs may have missed Darwin’s best description of the ecology of the island, to be found bizarrely in his Geological diary, and only recently published for the first time in Cambridge's Darwin Online resource.

Two months into the journey, Darwin was feeling homesick and seriously worried about the length of the voyage, but novelties like seeing the sun to the north kept his spirits up. On February 28th, the Beagle reached South America at Bahia. Darwin was to spend most of the next three and half years exploring the southern half of the continent. For now, we leave him on another leap year - February 29th, 1832 - wandering the jungle in raptures.