[REAL, 1850] The Impulsoria, a locomotive powered by four horse's on treadmills.

https://www.frrandp.com/2021/02/the-impulsoria.html

Other than one prototype unit, however, the locomotive was never produced. By 1850, steam was clearly king, and any horse-powered railways outside of streetcar operations were on the way out. Thus, the Impulsoria became nothing more than a strange curiosity of an early railway engine.