With his ship the Endurance being crushed by pack ice and sinking fast, Antarctic explorer Sir Ernest Shackleton ordered his men over the side, telling them to take only the barest of personal possessions, a limit of no more than two pounds each.

The one exception he made was for a five-string Windsor zither-banjo belonging to the expedition's meteorologist, a jaunty young man named Leonard Hussey. Although his repertoire was limited, Hussey had been keeping the party entertained through the long, dark, polar night, and Shackleton, keenly aware of the effects of stress and isolation on morale, wanted him to keep the tunes coming.

"It's vital mental medicine," Shackleton said of the music, "and we shall need it." And so Hussey brought