On Christmas Day 1866, Bartholomew Sulivan sat down to write a typically long and chatty letter to his old friend, Charles Darwin, commiserating on shared ill-health, glorying in the achievements of their children, offering to collect plant specimens, and reminiscing about their time together on board HMS Beagle:

Conrad Martens was born in London, the son of an Austrian diplomat. He studied landscape painting under the watercolourist Copley Fielding (1789–1855), who also briefly taught Ruskin. In 1833 he was on board the Hyacinth, headed for India, but en route in Rio de Janeiro, learned that Robert FitzRoy, captain of HMS Beagle, was looking for a replacement after Augustus Earle, the Beagle’s original artist, had become seriously ill.