The difference engine / William Gibson, Bruce Sterling.

Enhanced descriptions from Syndetics:

1855: The Industrial Revolution is in full and inexorable swing, powered by steam-driven cybernetic Engines.  Charles Babbage perfects his Analytical Engine and the computer age arrives a century ahead of its time.  And three extraordinary characters race toward a rendezvous with history--and the future:
 
Sybil Gerard --a fallen woman, politician's tart, daughter of a Luddite agitator
 
Edward "Leviathan" Mallory --explorer and paleontologist
 
Laurence Oliphant --diplomat, mystic, and spy.
 
Their adventure begins with the discovery of a box of punched Engine cards of unknown origin and purpose.  Cards someone wants badly enough to kill for....
 
Part detective story, part historical thriller, The Difference Engine is the collaborative masterpiece by two of the most acclaimed science fiction authors writing today.  Provocative, compelling, intensely imagined, it is a startling extension of Gibson's and Sterling's unique visions--and the beginning of movement we know today as "steampunk!"