The Science of Discworld III: Darwin's Watch2012

Ever since a wizardly experiment inadvertently brought about the creation of Roundworld, the wizard scholars of Unseen University have done their best to put things on the right course. In Darwin's Watch they may face their greatest challenge yet: A man called Darwin has written a bestselling book called The Theology of the Species, and his theory of scientific design has been witlessly embraced by Victorian society. As a result, scientific progress has slowed to a crawl, and the wizards must find a way to change history back to the way it should have been.