Military men, as histories of the Royal Navy in particular have shown, tend to be interested in controlling sanitary conditions. Among seamen, maintaining health was always essential otherwise ships could not remain at sea. The main theme of Dr. Katherine Foxhall’s interesting book is voyages to Australia.
People down on their luck fleeing to the colonies on the first available ship is a mainstay of 19th century fiction. It was a convenient way for an author to either get rid of an unnecessary character, or to bring a surprise new person into the narrative mix with dramatic effect.