Weight matters.
I was thinking he could have combined it with a balloon to be able to give the balloon some steering. But with a steam engine - that would be some balloon. I wonder when the first modern style airplane propeller was invented? Combine it with a bicycle pedal power and a balloon might be enough for steering?
Okay - here’s what I found on the net:
“In 1852, Jules Henri Giffard invented the first full-size powered airship, which used a three-bladed propeller paired with a 3-horsepower steam engine. And in 1873, aviation pioneer Alberto Santos-Dumont built steerable aluminum airships powered by large wooden propellers.”