Prelude to Eternity. Brian Stableford

In an alternate England in which Cromwell's revolution succeeded, Michael Laurel attends a 19th-century party to witness the demonstration of the first time machine. But Michael comes to realize that the entire future of the world might be at stake–and the past as well–if the machine malfunctions. How can he, a mere artist, possibly make a difference to the ultimate fate of the universe? A grand adventure in the style of A. E. van Vogt and Thomas Love Peacock.