Definition of "fire engine"
(archaic) Steam engine.
Quotations
This discovery gave a great impulse to mechanical ingenuity, and many schemes were contrived to make this new agent available as a motive power; but the first of these projects that appears to have been of any avail was the fire engine of Captain Tomas Savery, who produced a vacuum by condensing steam in close vessels, and then applied the vacuum so obtained to the elevation of water.
1868, John Bourne, A Treatise on the Steam-engine in Its Various Applications to Mines, Mills, Steam Navigation, Railways, and Agriculture, page 4