Cyrus Smith is one of the protagonists of Jules Verne's novel The Mysterious Island. He is an officer in the Union Army during the American Civil War. He is a very skilled man, a fine literary example of 19th century engineer.
Cyrus Smith is also a man possessed of the kind of high moral qualities common in Verne's protagonists. He is selfless, noble, honest, courageous, and utterly devoted to his companions.
His practical knowledge of physics, chemistry, botany, navigation, and many other fields enables the Mysterious Island's colonists quickly to establish a thriving mini-civilization in isolation from the rest of the world.
