The Aeolipile

Although the Victorian Era was the golden age of Steam power (hence, Steampunk), the technology actually goes back to ancient times.

The Aeolipile is a primitive rocket-style jet engine whose invention is generally credited to Hero of Alexandria circa 100 A.D. But in fact, writings exist by the Roman engineer Vitruvius that describe the Aeolipile a century before Hero was born, and the Greek inventor Ctesibius spoke of it circa 250 B.C.

The device is appallingly simple: a sealed caldron of water is placed over a heat source. As the water boils, steam rises up into the narrow pipes into the hollow sphere. The steam is expelled from two bent outlet tubes on the ball, resulting in rotation of the ball and generating thrust due to the same principle as rockets and jets.