On 4 April, they entered the harbour of Rio de Janeiro to make observations of longitude from Villegagnon Island. Darwin took in the sights of the city then made an expedition into the interior, returning to the ship on 24 April. By then, Robert McCormick had left the ship, with permission from the admiral in command, and returned to England. Assistant Surgeon Benjamin Bynoe was made acting surgeon in his place. McCormick felt "very much disappointed in my expectations of carrying out my natural history pursuits, every obstacle having been placed in the way of my getting on shore and making collections" while the gentleman Darwin received all the invitations from dignitaries onshore and was given facilities to pack his collections. On 26 April, Darwin moved into a house he had rented at Botafogo and stayed there with three others when "Beagle" left on 10 May to recheck observations at Bahia. FitzRoy had found a discrepancy of in the meridian distance of longitude between his measurements and those of Albin Roussin, and decided to go back. A seaman, a ship's boy and a young midshipman had caught a fever after visiting the Macacu River and died. When the ship returned to Rio on 3 June, FitzRoy confirmed that his measurements of Bahia and the Abrolhos reefs were correct, after which he sent these corrections to Roussin. They sailed from Rio on 5 July.