In Search of the Castaways by Jules Verne

In IN SEARCH OF THE CASTAWAYS, tells the story of the quest for Captain Grant of the 'Britannia,' a shipwrecked vessel. After finding a bottle cast into the ocean by captain Grant, Lord and Lady Glenarvan of Scotland contact the young daughter and son of Captain Grant, and moved by their loss, Lord and Lady Glenarvan launch a rescue expedition. The main difficulty is that only the latitude of the wreck (37 degrees South) is known; thus, the expedition will have to search along the 37th parallel of the southern hemisphere for the missing castaways.